JP2019053098A - Electrophotographic photoreceptor, process cartridge, image forming device, and image formation method - Google Patents

Abstract

To provide an electrophotographic photoreceptor which, while securing sensitivity, suppresses a rise in residual potential.SOLUTION: Provided is an electrophotographic photoreceptor comprising: a conductive substrate 1; an organic photosensitive layer provided on the conductive substrate (for example, a charge generation layer 2 and a charge transport layer 3 or an organic photosensitive layer 6 of single layer type); an inorganic protective layer 5 provided on the organic photosensitive layer and including a group 13 element and oxygen, the sum of element composition ratios of the group 13 element and the oxygen to all elements constituting the inorganic protective layer 5 being 0.70 or greater, the inorganic protective layer 5 including a first region where the sum of element composition ratios of the oxygen and the group 13 element (oxygen/group 13 element) is 1.10 to 1.30 inclusive and a second region where the sum of element composition ratios of the oxygen and the group 13 element (oxygen/group 13 element) is 1.40 to 1.50 inclusive on the organic photosensitive layer in the order stated, the second region being the uppermost layer.SELECTED DRAWING: Figure 1

Description

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

  Patent Document 1 discloses a substrate, a photosensitive layer, a protective layer containing oxygen and gallium, a first region existing on the outer peripheral surface side, and a side closer to the substrate than the first region And a protective layer having a second region having an atomic ratio [oxygen / gallium] larger than that of the first region in this order.

In Patent Document 2, a base, a photosensitive layer provided on the base, and a protective layer provided on the photosensitive layer and containing oxygen and gallium, the first region existing on the outer peripheral surface side. And a second region that is closer to the substrate than the first region and has a larger atomic ratio [oxygen / gallium] than the first region, and the second region than the second region. A protective layer having a third region present on a side closer to the substrate and having a smaller atomic ratio (oxygen / gallium) than the second region, and each region has an absorption coefficient of 1 × As each light absorption edge energy obtained from a wavelength of 10 ⁶ (m ⁻¹ ), the light absorption edge energy in the first region is FE1, the light absorption edge energy in the second region is FE2, and the third The light absorption edge energy in the region is FE3. 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 ≧ FE1 An electrophotographic photoreceptor to satisfy is described.

JP 2011-028218 A JP 2011-197571 A

  For example, an electrophotographic photoreceptor provided with an inorganic protective layer may cause scratches in the inorganic protective layer. When the thickness of the inorganic protective layer is increased in order to increase the mechanical strength of the inorganic protective layer, the residual potential may increase. On the other hand, when the stoichiometric ratio of the material forming the inorganic protective layer is reduced in order to suppress the increase in the residual potential, the sensitivity may be lowered.

An object of the present invention is to provide an electrophotographic photosensitive member having an inorganic protective layer, wherein the inorganic protective layer is composed of only a layer having an elemental composition ratio of oxygen and gallium (oxygen / gallium) of 1.40 to 1.50. Or a volume resistivity of only 2.0 × 10 ¹⁰ Ωcm or more, or the inorganic protective layer has an oxygen / gallium elemental composition ratio (oxygen / gallium) of 1 When composed of only a layer having a volume resistivity of not less than 10 and not more than 1.30, or composed of only a layer having a volume resistivity of not less than 2.0 × 10 ⁷ Ωcm and not more than 1.0 × 10 ¹⁰ Ωcm In contrast, it is an object to provide an electrophotographic photosensitive member that suppresses an increase in residual potential while ensuring sensitivity even when the thickness of the entire inorganic protective layer is increased.

  The above problem is solved by the following means.

The invention according to claim 1
A conductive substrate;
An organic photosensitive layer provided on the conductive substrate;
An inorganic protective layer provided on the organic photosensitive layer, which contains a Group 13 element and oxygen, and the elemental composition ratio of the Group 13 element and oxygen to all elements constituting the inorganic protective layer A first region in which the sum of oxygen and the group composition element of oxygen and the group 13 element (oxygen / group 13 element) is 1.10 or more and 1.30 or less, and A second region having an elemental composition ratio of oxygen and the Group 13 element (oxygen / Group 13 element) of 1.40 to 1.50 on the organic photosensitive layer in this order; An inorganic protective layer in which the second region is the uppermost layer;
An electrophotographic photosensitive member comprising:

The invention according to claim 2
A conductive substrate;
An organic photosensitive layer provided on the conductive substrate;
An inorganic protective layer provided on the organic photosensitive layer, which contains a Group 13 element and oxygen, and the elemental composition ratio of the Group 13 element and oxygen to all elements constituting the inorganic protective layer Of the first region having a volume resistivity of 2.0 × 10 ⁷ Ωcm or more and 1.0 × 10 ¹⁰ Ωcm or less and a volume resistivity of 2.0 × 10 ¹⁰ Ωcm. An inorganic protective layer having the second region as described above on the organic photosensitive layer in this order, and the second region being the uppermost layer;
An electrophotographic photosensitive member comprising:

The invention according to claim 3
The electrophotographic photosensitive member according to claim 1, wherein the group 13 element is gallium.
The invention according to claim 4
The electrophotographic photosensitive member according to claim 1, wherein a thickness of the first region is thinner than a thickness of the second region.
The invention according to claim 5
The electrophotographic photosensitive member according to claim 4, wherein a ratio of a thickness of the second region to a thickness of the first region (a thickness of the second region / a thickness of the first region) is 3 or more and 100 or less.
The invention according to claim 6
6. The electron according to claim 4, wherein the thickness of the first region is 0.01 μm or more and 0.1 μm or less, and the thickness of the second region is 0.3 μm or more and 1.0 μm or less. Photoconductor.
The invention according to claim 7 provides:
The electrophotographic photosensitive member according to claim 1, wherein the total thickness of the inorganic protective layer is 3 μm or more and 10 μm or less.
The invention according to claim 8 provides:
The electrophotographic photosensitive member according to claim 7, wherein the total thickness of the inorganic protective layer is 3 μm or more and 6 μm or less.
The invention according to claim 9 is:
The electrophotographic photosensitive member according to any one of claims 1 to 8, wherein the first region and the second region are repeatedly laminated in the order of the first region and the second region. body.
The invention according to claim 10 is:
The electrophotographic photosensitive member according to claim 9, wherein the number of repetitions in which the first region and the second region are repeatedly stacked in the order of 3 to 10 times.
The invention according to claim 11 is:
The electrophotographic photoreceptor according to any one of claims 1 to 10, wherein the organic photosensitive layer has a layer containing a charge transport material, a binder resin, and silica particles.
The invention according to claim 12
The electrophotographic photosensitive member according to claim 11, wherein the content of the silica particles is 40% by mass or more and 80% by mass or less with respect to the entire layer including the charge transport material and the binder resin.
The invention according to claim 13 is:
The electrophotographic photosensitive member according to claim 1, wherein the conductive substrate has a thickness of 1.5 mm or more.

The invention according to claim 14 is:
The electrophotographic photosensitive member according to any one of claims 1 to 13,
A process cartridge that is detachable from the image forming apparatus.
The invention according to claim 15 is:
The electrophotographic photoreceptor according to any one of claims 1 to 13,
Charging means for charging the surface of the electrophotographic photosensitive member;
An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member;
Developing means for developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner to form a toner image;
Transfer means for transferring the toner image to the surface of the recording medium;
An image forming apparatus comprising:

  According to the first and third aspects of the invention, in the electrophotographic photosensitive member provided with the inorganic protective layer, the inorganic protective layer has an elemental composition ratio of oxygen and gallium (oxygen / gallium) of 1.40 to 1.50. Even when the thickness of the entire inorganic protective layer is increased compared to a case where only a certain layer or only a layer which is 1.10 or more and 1.30 or less is formed, the residual property is ensured while ensuring the sensitivity. An electrophotographic photosensitive member that suppresses an increase in potential is provided.

According to the invention of claim 2, in the electrophotographic photosensitive member provided with the inorganic protective layer, only the layer having a volume resistivity of 2.0 × 10 ¹⁰ Ωcm or more, or 2.0 × 10 ⁷ Ωcm or more. An electrophotographic photosensitive member is provided that suppresses an increase in residual potential while ensuring sensitivity as compared with a case where only a layer having a size of 0 × 10 ¹⁰ Ωcm or less is formed.

According to the inventions according to claims 4, 5, and 6, in the inorganic protective layer, electrophotography in which a decrease in sensitivity is suppressed as compared with the case where the thickness of the first region is the same or thicker than the thickness of the second region A photoreceptor is provided.
According to the seventh and eighth aspects of the invention, there is provided an electrophotographic photoreceptor in which the generation of scratches on the inorganic protective layer is suppressed as compared with the case where the thickness of the entire inorganic protective layer is less than 3 μm.
According to the invention of claim 9, the thickness of the entire inorganic protective layer is greater than when the first region and the second region are repeatedly laminated in the order of the second region and the first region. Even when the thickness of the electrophotographic photosensitive member is increased, an electrophotographic photosensitive member is provided which suppresses an increase in residual potential while ensuring sensitivity.
According to the invention of claim 10, in the inorganic protective layer, when the total thickness of the inorganic protective layer is thicker than when the number of repetitions of repeatedly laminating the first region and the second region is less than 3 times. Even so, it is possible to provide an electrophotographic photosensitive member that suppresses an increase in residual potential while ensuring sensitivity.
According to the inventions according to claims 11 and 12, when the organic photosensitive layer is a function-separated type photosensitive layer of the charge generation layer and the charge transport layer, the charge transport layer contains only the charge transport material and the binder resin. Compared to the case, an electrophotographic photoreceptor in which the generation of scratches on the inorganic protective layer is suppressed is provided.
According to the thirteenth aspect of the present invention, there is provided an electrophotographic photosensitive member in which the generation of scratches on the inorganic protective layer is suppressed as compared with the case where the thickness of the conductive substrate is less than 1.5 μm.

According to the invention of claim 14 or 15, in the electrophotographic photosensitive member provided with the inorganic protective layer, the inorganic protective layer has an elemental composition ratio of oxygen and gallium (oxygen / gallium) of 1.40 or more and 1.50 or less. When it is composed of only a certain layer or only a layer having a volume resistivity of 2.0 × 10 ¹⁰ Ωcm or more, or an element composition ratio of oxygen and gallium (oxygen / gallium) of 1.10 or more. Compared to the case where it is composed of only a layer having a volume resistivity of 30 or less, or the case where it is composed of only a layer having a volume resistivity of 2.0 × 10 ⁷ Ωcm or more and 1.0 × 10 ¹⁰ Ωcm or less. Provided is a process cartridge or an image forming apparatus including an electrophotographic photosensitive member that suppresses an increase in residual potential while ensuring sensitivity even when the thickness of the entire layer is increased. .

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 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 the inorganic 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 inorganic protective layer of the electrophotographic photoreceptor 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 present invention will be described in detail.

[Electrophotographic photoreceptor]
The electrophotographic photosensitive member according to the first embodiment includes a conductive substrate, an organic photosensitive layer provided on the conductive substrate, and an inorganic protective layer provided on the organic photosensitive layer, and includes a group 13 element. And the sum of the elemental composition ratios of the group 13 element and oxygen with respect to all the elements that contain oxygen and constitute the inorganic protective layer is 0.70 or more, and the elemental composition ratio of oxygen and the group 13 element The first region where (oxygen / Group 13 element) is 1.10 or more and 1.30 or less, and the elemental composition ratio of oxygen and the Group 13 element (oxygen / Group 13 element) is 1.40 or more. And an inorganic protective layer having a second region of 1.50 or less in this order on the organic photosensitive layer, the second region being the uppermost layer.

An electrophotographic photoreceptor according to a second embodiment includes a conductive substrate, an organic photosensitive layer provided on the conductive substrate, an inorganic protective layer provided on the organic photosensitive layer, and a Group 13 element. And the sum of the elemental composition ratios of the group 13 element and oxygen with respect to all the elements that contain oxygen and constitute the inorganic protective layer is 0.70 or more, and the volume resistivity is 2.0 × 10 ^7. A first region having a resistance of Ωcm to 1.0 × 10 ¹⁰ Ωcm and a second region having a volume resistivity of 2.0 × 10 ¹⁰ Ωcm or more are provided in this order on the organic photosensitive layer. And an inorganic protective layer whose uppermost layer is the uppermost layer.

Electrophotography according to the first embodiment and the second embodiment (in this specification, matters common to the first embodiment and the second embodiment are referred to as “this embodiment”). Specifically, when the organic photosensitive layer is a single-layer type organic photosensitive layer, the organic photosensitive layer includes, for example, a charge generation material, a charge transport material, and a binder resin.
On the other hand, when the organic photosensitive layer is a function-separated type organic photosensitive layer, the organic photosensitive layer is preferably an organic photosensitive layer having a charge generation layer and a charge transport layer in this order on a conductive substrate, This charge transport layer includes, for example, a charge transport material and a binder resin. The charge transport layer may be composed of two or more layers.

Here, conventionally, a technique for forming an inorganic protective layer on an organic photosensitive layer is known.
While the organic photosensitive layer has flexibility and tends to be deformed, the inorganic protective layer tends to be inferior in toughness although it is hard. Therefore, the inorganic protective layer may be damaged.

  For example, in the developing process, when the carrier scatters from the developing means and the scattered carrier adheres to the electrophotographic photosensitive member, the carrier reaches the transfer position while adhering to the electrophotographic photosensitive member. At the transfer position, a pressing force is applied with the carrier sandwiched between the electrophotographic photosensitive member and the transfer means. For this reason, the inorganic protective layer may cause scratches (such as dent-like scratches and streak-like scratches) when the carrier rubs between the electrophotographic photosensitive member and the transfer unit.

In order to improve the mechanical strength of the inorganic protective layer, for example, it is conceivable to increase the thickness of the inorganic protective layer. However, when the thickness of the inorganic protective layer is increased, charges are likely to accumulate in the inorganic protective layer, so that the residual potential may increase.
On the other hand, in order to suppress an increase in residual potential, it is conceivable to reduce the stoichiometric ratio of the material forming the inorganic protective layer. An inorganic protective layer having a small stoichiometric ratio tends to suppress charge accumulation. However, if the stoichiometric ratio of the material forming the inorganic protective layer is reduced, the inorganic protective layer is likely to be colored, so that the exposure amount for reducing the potential is increased. As a result, the sensitivity may decrease.

On the other hand, in the electrophotographic photosensitive member according to this embodiment, the inorganic protective layer contains a Group 13 element and oxygen, and the Group 13 element and the oxygen element with respect to all elements constituting the inorganic protective layer. The sum of the composition ratios is 0.70 or more.
In the electrophotographic photosensitive member according to the first embodiment, the inorganic protective layer has a first elemental ratio of oxygen and a Group 13 element (oxygen / Group 13 element) of 1.10 to 1.30. A region and a second region having an oxygen / group 13 element of 1.40 to 1.50 on the photosensitive layer in this order. The second region is the uppermost layer of the inorganic protective layer.
In the electrophotographic photosensitive member of the second embodiment, the inorganic protective layer has a first region having a volume resistivity of 2.0 × 10 ⁷ Ωcm or more and 1.0 × 10 ¹⁰ Ωcm or less and a volume resistivity. A second region having a size of 2.0 × 10 ¹⁰ Ωcm or more is provided on the photosensitive layer in this order. The second region is the uppermost layer of the inorganic protective layer.

  In the electrophotographic photosensitive member of the first embodiment, the inorganic protective layer has a second region close to the stoichiometric ratio formed on the first region having a small stoichiometric ratio. In the first region having a small stoichiometric ratio, oxygen vacancies are generated, and thus electric charges are likely to move. As a result, when an electric field is applied, electrons in the second region are supplied to the first region, whereby charge accumulation is suppressed, and the potential is likely to decrease. As a result, the inorganic protective layer is considered to suppress an increase in residual potential. In addition, the first region having a small stoichiometric ratio is more likely to be colored than the second region having a close stoichiometric ratio. Since the second region formed on the first region that is easy to be colored is the uppermost layer of the inorganic protective layer, a decrease in light transmittance is suppressed, so that a decrease in sensitivity is suppressed. it is conceivable that.

  In the electrophotographic photosensitive member of the second embodiment, the inorganic protective layer has a second region having a high volume resistivity formed on a first region having a low volume resistivity. In the first region, since the resistance is low, electrons flow easily, and the electrons in the second region are supplied to the first region, so that it is considered that charge accumulation is suppressed. As a result, it is considered that the increase in residual potential is suppressed. In addition, a high-resistance second region that is difficult to be colored is the uppermost layer of the inorganic protective layer, and a low-resistance first region in which charges easily move is formed below the second region. Therefore, it is considered that the exposure amount for attenuating the surface potential is reduced. As a result, it is considered that the decrease in sensitivity is suppressed.

  From the above, in the electrophotographic photosensitive member according to the present embodiment (the first embodiment and the second embodiment), the sensitivity is improved even when the thickness of the entire inorganic protective layer is increased due to the above configuration. It is presumed that the increase in the residual potential is suppressed while ensuring.

  The first region and the second region are repeatedly laminated in this order from the photosensitive layer side to the photosensitive layer, so that even if the thickness of the entire inorganic protective layer is increased, the sensitivity is further improved. While ensuring, it becomes easy to suppress the rise in the residual potential. When the first region and the second region are repeatedly laminated on the photosensitive layer (for example, the number of repetitions is 3 to 10) to form an inorganic protective layer having a desired thickness, the thickness is thin. A large number of first regions and second regions are provided. Therefore, a large number of first regions in which electrons easily flow are formed in contact with the second region, so that charges easily move in the entire inorganic protective layer, and charge accumulation is reduced in the second region, thereby reducing the residual potential. It is thought that it becomes easy to suppress the rise of Moreover, since the thickness of the second region is thin, it is considered that sensitivity is easily secured.

  In addition, the electrophotographic photosensitive member according to the present embodiment suppresses an increase in residual potential while ensuring sensitivity even when the thickness of the entire inorganic protective layer is increased. The thickness can be increased. Therefore, it becomes easy to suppress generation | occurrence | production of the damage | wound of an inorganic protective layer. Furthermore, since the outermost surface is formed by the second region, the mechanical strength of the inorganic protective layer is easily improved. In this respect as well, the occurrence of scratches on the inorganic protective layer is easily suppressed.

Here, the organic photosensitive layer of the electrophotographic photoreceptor according to the exemplary embodiment may include silica particles. By using silica particles in the organic photosensitive layer, it is considered that the silica particles function as a reinforcing material for the organic photosensitive layer. Therefore, it is considered that cracking of the inorganic protective layer is suppressed by making the organic photosensitive layer difficult to deform.
For example, when the organic photosensitive layer is a single-layer type organic photosensitive layer, the organic photosensitive layer may further contain silica particles. When the organic photosensitive layer is a function-separated type organic photosensitive layer, the charge transport layer may further contain silica particles. However, when the charge transport layer is composed of two or more layers and silica particles are used, the charge transport layer of the layer constituting the surface (the uppermost layer of the charge transport layer) is a charge transport material, a binder. It is good to be comprised including resin and a silica particle.

Hereinafter, the electrophotographic photoreceptor according to the exemplary embodiment will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.
FIG. 1 is a schematic cross-sectional view showing an example of an electrophotographic photosensitive member according to this embodiment. 2, 3 and 4 are schematic cross-sectional views showing other examples of the electrophotographic photosensitive member according to the present embodiment, respectively.

  An electrophotographic photoreceptor 7A shown in FIG. 1 is a so-called function-separated photoreceptor (or laminated photoreceptor), and an undercoat layer 1 is provided on a conductive substrate 4, on which a charge generation layer 2 and a charge are formed. The transport layer 3 and the inorganic protective layer 5 have a structure formed in order. In the electrophotographic photoreceptor 7A, an organic photosensitive layer is constituted by the charge generation layer 2 and the charge transport layer 3. In the inorganic protective layer 5, the first region 5 </ b> A and the second region 5 </ b> B are formed on the charge transport layer 3. The charge transport layer 3 includes a charge transport material and a binder resin, and contains silica particles as necessary.

  The electrophotographic photoreceptor 7B shown in FIG. 2 has a function separated into the charge generation layer 2 and the charge transport layer 3 as in the electrophotographic photoreceptor 7A shown in FIG. It is a separation type photoreceptor. 3 includes the charge generation material and the charge transport material in the same layer (single layer type organic photosensitive layer 6 (charge generation / charge transport layer)).

In the electrophotographic photoreceptor 7B shown in FIG. 2, an undercoat layer 1 is provided on a conductive substrate 4, and a charge generation layer 2, a charge transport layer 3B, a charge transport layer 3A, and an inorganic protective layer 5 are formed thereon. It has a structure formed sequentially. In the electrophotographic photoreceptor 7B, an organic photosensitive layer is constituted by the charge transport layer 3A, the charge transport layer 3B, and the charge generation layer 2.
As in the electrophotographic photoreceptor 7 </ b> A shown in FIG. 1, the inorganic protective layer 5 has a first region 5 </ b> A and a second region 5 </ b> B formed on the charge transport layer 3. The charge transport layer 3A and the charge transport layer 3B are configured to include a charge transport material and a binder resin. The charge transport layer 3A contains silica particles as necessary. When silica particles are used, they are contained in the charge transport layer 3A, and the charge transport layer 3B may or may not contain silica particles.

The electrophotographic photoreceptor 7C shown in FIG. 3 has a structure in which an undercoat layer 1 is provided on a conductive substrate 4, and a single-layer type organic photosensitive layer 6 and an inorganic protective layer 5 are sequentially formed thereon. It is.
The single-layer type organic photosensitive layer 6 includes a charge transport material and a binder resin, and includes silica particles as necessary.

In the electrophotographic photoreceptor 7D shown in FIG. 4, the undercoat layer 1 is provided on the conductive substrate 4 like the electrophotographic photoreceptor 7A shown in FIG. 1, and the charge generation layer 2, the charge transport layer 3, And the inorganic protective layer 5 has the structure formed sequentially. As in the electrophotographic photoreceptor 7A shown in FIG. 1, the inorganic protective layer 5 has a first region 5A and a second region 5B formed on the charge transport layer 3. However, in the electrophotographic photoreceptor 7D, the inorganic protective layer 5 includes the first region 5A and the second region 5B which are repeatedly laminated in this order from the charge transport layer 3 side. In the electrophotographic photoreceptor 7D, the first region 5A and the second region 5B are stacked three times.
The charge transport layer 3 includes a charge transport material and a binder resin, and contains silica particles as necessary. In addition, the number of repetitions in which the first region 5A and the second region 5B are stacked is not limited to three, and may be four or more.

  In each of the electrophotographic photosensitive members shown in FIGS. 1, 2, 3, and 4, the undercoat layer 1 may or may not be provided. In addition, each electrophotographic photosensitive member shown in FIGS. 1, 2, and 3 has a first region 5A and a second region 5B in this order as in the electrophotographic photosensitive member 7D shown in FIG. You may laminate | stack repeatedly.

  Hereinafter, each element will be described based on the electrophotographic photosensitive member 7A shown in FIG. 1 as a representative example. In some cases, the reference numerals are omitted.

(Conductive substrate)
Examples of the conductive substrate include metal plates (eg, aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.), metal drums, metal belts, etc. Is mentioned. In addition, as the conductive substrate, for example, paper, resin film, belt, etc. coated, vapor-deposited or laminated with a conductive compound (for example, conductive polymer, indium oxide, etc.), metal (for example, aluminum, palladium, gold, etc.) or an alloy, etc. Also mentioned. Here, “conductive” means that the volume resistivity is less than 10 ¹³ Ωcm.

  When the electrophotographic photosensitive member is used in a laser printer, the surface of the conductive substrate has a center line average roughness Ra of 0.04 μm or more and 0.5 μm for the purpose of suppressing interference fringes generated when laser light is irradiated. The surface is preferably roughened below. When non-interfering light is used as a light source, roughening for preventing interference fringes is not particularly required, but it is suitable for extending the life because it suppresses generation of defects due to irregularities on the surface of the conductive substrate.

  Examples of roughening methods include wet honing by suspending an abrasive in water and spraying the conductive substrate, centerless grinding in which the conductive substrate is pressed against a rotating grindstone, and grinding is performed continuously. And anodizing treatment.

  As a roughening method, without roughening the surface of the conductive substrate, conductive or semiconductive powder is dispersed in the resin to form a layer on the surface of the conductive substrate. A method of roughening with particles dispersed in the layer may also be mentioned.

  In the roughening treatment by anodic oxidation, a metal (for example, aluminum) conductive substrate is used as an anode, and an oxide film is formed on the surface of the conductive substrate by anodizing in an electrolyte solution. Examples of the electrolyte solution include a sulfuric acid solution and an oxalic acid solution. However, the porous anodic oxide film formed by anodic oxidation is chemically active as it is, easily contaminated, and has a large resistance fluctuation due to the environment. Therefore, the pores of the oxide film are blocked by the volume expansion due to the hydration reaction in pressurized water vapor or boiling water (a metal salt such as nickel may be added) against the porous anodic oxide film, and more stable hydration oxidation It is preferable to perform a sealing treatment for changing to a product.

  The thickness of the anodized film is preferably, for example, 0.3 μm or more and 15 μm or less. When this film thickness is within the above range, the barrier property against implantation tends to be exhibited, and the increase in residual potential due to repeated use tends to be suppressed.

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

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

  The thickness (wall thickness) of the conductive substrate is preferably 1 mm or more, and preferably 1.2 mm or more, from the viewpoint of ensuring the strength of the photoreceptor and suppressing the occurrence of scratches on the inorganic protective layer. More preferably, it is 1.5 mm or more. The upper limit of the thickness of the conductive substrate is not particularly limited. For example, it is preferably 3.5 mm or less from the viewpoint of suppressing the occurrence of scratches on the inorganic protective layer and the operability or manufacturability of the photoreceptor. It may be 3 mm or less, and may be less than 3 mm. When the thickness of the conductive substrate is in the above range, the bending of the conductive substrate is easily suppressed, and the generation of scratches on the inorganic protective layer is easily suppressed.

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

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

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

  For example, the content of the inorganic particles is preferably 10% by mass or more and 80% by mass or less, and more preferably 40% by mass or more and 80% by mass or less with respect to the binder resin.

  The inorganic particles may be subjected to a surface treatment. Two or more inorganic particles having different surface treatments or particles having different particle diameters may be mixed and used.

  Examples of the surface treatment agent include a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, and a surfactant. In particular, a silane coupling agent is preferable, and an amino group-containing silane coupling agent is more preferable.

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

  Two or more silane coupling agents may be used in combination. For example, a silane coupling agent having an amino group and another silane coupling agent may be used in combination. Other silane coupling agents include, for example, vinyltrimethoxysilane, 3-methacryloxypropyl-tris (2-methoxyethoxy) silane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycol. Sidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- ( Aminoethyl) -3-aminopropylmethyldimethoxysilane, N, N-bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, and the like, but are not limited thereto. It is not a thing.

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

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

  Here, the undercoat layer may contain an electron-accepting compound (acceptor compound) together with the inorganic particles from the viewpoint of enhancing the long-term stability of the electric characteristics and the carrier blocking property.

Examples of the electron accepting compound include quinone compounds such as chloranil and bromoanil; tetracyanoquinodimethane compounds; 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitro-9-fluorenone, and the like. 2- (4-biphenyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole, 2,5-bis (4-naphthyl) -1,3,4- Oxadiazole compounds such as oxadiazole and 2,5-bis (4-diethylaminophenyl) -1,3,4 oxadiazole; xanthone compounds; thiophene compounds; 3,3 ′, 5,5 ′ tetra- electron transporting substances such as diphenoquinone compounds such as t-butyldiphenoquinone;
In particular, the electron-accepting compound is preferably a compound having an anthraquinone structure. As the compound having an anthraquinone structure, for example, a hydroxyanthraquinone compound, an aminoanthraquinone compound, an aminohydroxyanthraquinone compound, and the like are preferable, and specifically, for example, anthraquinone, alizarin, quinizarin, anthralfin, and purpurin are preferable.

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

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

  In the dry method, for example, while stirring inorganic particles with a mixer having a large shearing force or the like, an electron-accepting compound dissolved directly or in an organic solvent is dropped and sprayed with dry air or nitrogen gas. It is a method of adhering to the surface of inorganic particles. When the electron-accepting compound is dropped or sprayed, it is preferably performed at a temperature not higher than the boiling point of the solvent. After dropping or spraying the electron-accepting compound, baking may be performed at 100 ° C. or higher. The baking is not particularly limited as long as it is a temperature and time for obtaining electrophotographic characteristics.

  In the wet method, for example, an electron-accepting compound is added while dispersing inorganic particles in a solvent by stirring, ultrasonic waves, a sand mill, an attritor, a ball mill, etc., and after stirring or dispersing, the solvent is removed to remove electrons. This is a method of attaching a receptive compound to the surface of inorganic particles. The solvent removal method is distilled off by filtration or distillation, for example. After removing the solvent, baking may be performed at 100 ° C. or higher. The baking is not particularly limited as long as it is a temperature and time for obtaining electrophotographic characteristics. In the wet method, the water content of the inorganic particles may be removed before adding the electron-accepting compound. Examples thereof include a method of removing while stirring and heating in a solvent, and a method of removing by azeotropic distillation with a solvent. Can be mentioned.

  The attachment of the electron-accepting compound may be performed before or after the surface treatment with the surface treatment agent is performed on the inorganic particles, or may be performed simultaneously with the attachment of the electron-accepting compound and the surface treatment with the surface treatment agent.

  The content of the electron-accepting compound is, for example, from 0.01% by mass to 20% by mass with respect to the inorganic particles, and preferably from 0.01% by mass to 10% by mass.

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

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

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

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

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

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

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

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

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

  There is no particular limitation on the formation of the undercoat layer, and a well-known formation method is used. For example, a coating film for forming an undercoat layer in which the above components are added to a solvent is formed, and the coating film is dried. And heating as necessary.

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

  Examples of the dispersion method of the inorganic particles when preparing the coating liquid for forming the undercoat layer include known methods such as a roll mill, a ball mill, a vibration ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker.

  Examples of the method for applying the coating liquid for forming the undercoat layer onto the conductive substrate include, for example, a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method. The usual methods, such as these, are mentioned.

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

(Middle layer)
Although illustration is omitted, an intermediate layer may be further provided between the undercoat layer and the photosensitive layer.
An intermediate | middle layer is a layer containing resin, for example. Examples of the resin used for the intermediate layer include an acetal resin (for example, polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, Polymer compounds such as polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, melamine resin, and the like can be given.
The intermediate layer may be a layer containing an organometallic compound. Examples of the organometallic compound used for the intermediate layer include organometallic compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon.
The compounds used for these intermediate layers may be used alone or as a mixture or polycondensate of a plurality of compounds.

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

The formation of the intermediate layer is not particularly limited, and a well-known formation method is used. For example, a coating film of an intermediate layer forming coating solution in which the above components are added to a solvent is formed, and the coating film is dried and necessary. It is performed by heating according to.
As the coating method for forming the intermediate layer, usual methods such as a dip coating method, a push-up coating method, a wire bar coating method, a spray coating method, a blade coating method, a knife coating method, and a curtain coating method are used.

  For example, the thickness of the intermediate layer is preferably set in a range of 0.1 μm to 3 μm. An intermediate layer may be used as the undercoat layer.

(Charge generation layer)
The charge generation layer is, for example, a layer containing a charge generation material and a binder resin. The charge generation layer may be a vapor deposition layer of a charge generation material. The vapor-deposited layer of the charge generation material is suitable when an incoherent light source such as an LED (Light Emitting Diode) or an organic EL (Electro-Luminescence) image array is used.

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

  Among these, in order to cope with near-infrared laser exposure, it is preferable to use a metal phthalocyanine pigment or a metal-free phthalocyanine pigment as the charge generation material. Specifically, for example, hydroxygallium phthalocyanine disclosed in JP-A-5-263007, JP-A-5-279591, etc .; chlorogallium phthalocyanine disclosed in JP-A-5-98181; More preferred are dichlorotin phthalocyanines disclosed in JP-A No. 140472, JP-A No. 5-140473 and the like; and titanyl phthalocyanine disclosed in JP-A No. 4-189873.

  On the other hand, in order to cope with laser exposure in the near-ultraviolet region, as the charge generation material, condensed aromatic pigments such as dibromoanthanthrone; thioindigo pigments; porphyrazine compounds; zinc oxide; trigonal selenium; Bisazo pigments and the like disclosed in 2004-78147 and JP-A-2005-181992 are preferred.

  The above-described charge generation material may also be used when using an incoherent light source such as an LED having an emission center wavelength of 450 nm to 780 nm and an organic EL image array. However, from the viewpoint of resolution, the photosensitive layer is 20 μm or less. When the thin film is used, the electric field strength in the photosensitive layer is increased, and a charge decrease due to charge injection from the substrate, that is, an image defect called a black spot is likely to occur. This becomes conspicuous when a charge generating material that easily generates a dark current is used in a p-type semiconductor such as trigonal selenium or a phthalocyanine pigment.

On the other hand, when an n-type semiconductor such as a condensed ring aromatic pigment, perylene pigment, azo pigment or the like is used as the charge generation material, dark current hardly occurs and even a thin film can suppress image defects called black spots. . Examples of the n-type charge generation material include compounds (CG-1) to (CG-27) described in paragraphs [0288] to [0291] of JP2012-155282A. It is not limited.
The n-type determination is performed by using a time-of-flight method that is usually used, and is determined by the polarity of the flowing photocurrent, and an n-type is more likely to flow electrons as carriers than holes.

The binder resin used for the charge generation layer is selected from a wide range of insulating resins, and the binder resin is selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinyl anthracene, polyvinyl pyrene, and polysilane. You may choose.
As the binder resin, for example, polyvinyl butyral resin, polyarylate resin (polycondensate of bisphenol and aromatic divalent carboxylic acid, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, Examples thereof include polyamide resin, acrylic resin, polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, and the like. Here, “insulating” means that the volume resistivity is 10 ¹³ Ωcm or more.
These binder resins are used singly or in combination of two or more.

  The mixing ratio of the charge generation material and the binder resin is preferably in the range of 10: 1 to 1:10 by mass ratio.

  In addition, the charge generation layer may contain a known additive.

  The formation of the charge generation layer is not particularly limited, and a known formation method is used. For example, a coating film of a charge generation layer forming coating solution in which the above components are added to a solvent is formed, and the coating film is dried. And heating as necessary. The charge generation layer may be formed by vapor deposition of a charge generation material. Formation of the charge generation layer by vapor deposition is particularly suitable when a condensed ring aromatic pigment or perylene pigment is used as the charge generation material.

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

Examples of a method for dispersing particles (for example, a charge generation material) in a coating solution for forming a charge generation layer include, for example, a media disperser such as a ball mill, a vibrating ball mill, an attritor, a sand mill, a horizontal sand mill, a stirring, an ultrasonic disperser, etc. Medialess dispersers such as roll mills and high-pressure homogenizers are used. Examples of the high-pressure homogenizer include a collision method in which a dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision in a high pressure state, and a penetration method in which a fine flow path is dispersed in a high pressure state.
In this dispersion, it is effective that the average particle size of the charge generation material in the coating solution for forming the charge generation layer is 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.15 μm or less. .

  Examples of methods for applying the charge generation layer forming coating solution on the undercoat layer (or on the intermediate layer) include blade coating, wire bar coating, spray coating, dip coating, bead coating, and air knife coating. And usual methods such as a curtain coating method.

  The film thickness of the charge generation layer is, for example, preferably set in the range of 0.1 μm to 5.0 μm, more preferably 0.2 μm to 2.0 μm.

(Charge transport layer)
The charge transport layer is, for example, a layer containing a charge transport material and a binder resin. The charge transport layer may be a layer containing a polymer charge transport material. Further, the charge transport layer may contain silica particles as necessary.

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

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

In Structural Formula (a-1), Ar ^T1 , Ar ^T2 , and Ar ^T3 are each independently a substituted or unsubstituted aryl group, —C ₆ H ₄ —C (R ^T4 ) ═C (R ^T5 ) (R ^T6), or _{-C 6 H 4 -CH = CH-} CH = C (R T7) shows the ^{(R T8).} R ^T4 , R ^T5 , R ^T6 , R ^T7 , and R ^T8 each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.
Examples of the substituent for each group include a halogen atom, an alkyl group having 1 to 5 carbon atoms, and an alkoxy group having 1 to 5 carbon atoms. Examples of the substituent of each group also include a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

In Structural Formula (a-2), R ^T91 and R ^T92 each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. R ^T101 , R ^T102 , R ^T111 and R ^T112 are each independently ^substituted with a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an alkyl group having 1 to 2 carbon atoms. A substituted amino group, a substituted or unsubstituted aryl group, —C (R ^T12 ) ═C (R ^T13 ) (R ^T14 ), or —CH═CH— ^CH═C (R ^T15 ) (R ^T16 ), R ^T12 , R ^T13 , R ^T14 , R ^T15 and R ^T16 each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Tm1, Tm2, Tn1, and Tn2 each independently represent an integer of 0 or more and 2 or less.
Examples of the substituent for each group include a halogen atom, an alkyl group having 1 to 5 carbon atoms, and an alkoxy group having 1 to 5 carbon atoms. Examples of the substituent of each group also include a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

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

  As the polymer charge transporting material, known materials having charge transporting properties such as poly-N-vinylcarbazole and polysilane are used. In particular, polyester-based polymer charge transport materials disclosed in JP-A-8-176293 and JP-A-8-208820 are particularly preferable. The polymer charge transport material may be used alone or in combination with a binder resin.

  The charge transport layer may contain silica particles. The content of the silica particles is preferably 40% by mass or more and 80% by mass or less with respect to the entire charge transport layer including the silica particles, from the viewpoint of suppressing generation of scratches on the inorganic protective layer. In the same way, the lower limit of the content of silica particles may be 45% by mass or more, or 50% by mass or more. Further, the upper limit of the content of the silica particles may be, for example, 75% by mass or less or 70% by mass or less from the viewpoint of dispersibility of the silica particles.

Examples of the silica particles include dry silica particles and wet silica particles.
Examples of the dry silica particles include combustion method silica (fumed silica) obtained by burning a silane compound and deflagration method silica obtained by explosively burning metal silicon powder.
Wet silica particles include wet silica particles obtained by neutralization reaction between sodium silicate and mineral acid (precipitation silica synthesized and aggregated under alkaline conditions, gel silica particles synthesized and aggregated under acidic conditions), and acidic silicic acid. Examples thereof include colloidal silica particles (silica sol particles) obtained by polymerization with alkalinity, and sol-gel silica particles obtained by hydrolysis of an organic silane compound (for example, alkoxysilane).
Among these, silica particles have low surface silanol groups and a low void structure from the viewpoint of generation of residual potential and suppression of image defects due to deterioration of other electrical characteristics (inhibition of reduction of fine line reproducibility). Method silica particles are preferably used.

  The volume average particle diameter of the silica particles is preferably 20 nm or more and 200 nm or less, for example. The lower limit of the volume average particle diameter of the silica particles may be 40 nm or more, or 50 nm or more. The lower limit of the volume average particle diameter of the silica particles may be 150 nm or less, 120 nm or less, or 110 nm or less.

  The volume average particle diameter of the silica particles is determined by separating the silica particles from the layer, observing 100 primary particles of the silica particles with a scanning electron microscope (SEM) device at a magnification of 40000 times, and analyzing the particles by image analysis of the primary particles. The longest diameter and the shortest diameter of each are measured, and the equivalent sphere diameter is measured from this intermediate value. The 50% diameter (D50v) in the cumulative frequency of the obtained sphere equivalent diameter is obtained, and this is measured as the volume average particle diameter of the silica particles.

The surface of the silica particles is preferably surface-treated with a hydrophobizing agent. Thereby, silanol groups on the surface of the silica particles are reduced, and generation of residual potential is easily suppressed.
Examples of the hydrophobizing agent include known silane compounds such as chlorosilane, alkoxysilane, and silazane.
Among these, as the hydrophobizing agent, a silane compound having a trimethylsilyl group, a decylsilyl group, or a phenylsilyl group is desirable from the viewpoint of easily suppressing the occurrence of a residual potential. That is, the surface of the silica particles preferably has a trimethylsilyl group, a decylsilyl group, or a phenylsilyl group.
Examples of the silane compound having a trimethylsilyl group include trimethylchlorosilane, trimethylmethoxysilane, 1,1,1,3,3,3-hexamethyldisilazane, and the like.
Examples of the silane compound having a decylsilyl group include decyltrichlorosilane, decyldimethylchlorosilane, and decyltrimethoxysilane.
Examples of the silane compound having a phenyl group include triphenylmethoxysilane and triphenylchlorosilane.

The condensation rate of the hydrophobized silica particles (Si—O—Si ratio in the SiO ₄ — bonds in the silica particles: hereinafter also referred to as “condensation rate of the hydrophobizing agent”) is, for example, the surface of the silica particles It is preferably 90% or more, more preferably 91% or more, and more preferably 95% or more with respect to the silanol group.
When the condensation rate of the hydrophobizing agent is within the above range, the silanol groups of the silica particles are further reduced, and the occurrence of residual potential is easily suppressed.

The condensation rate of the hydrophobizing agent indicates the ratio of condensed silicon to the total bondable sites of silicon in the condensed portion detected by NMR, and is measured as follows.
First, silica particles are separated from the layer. The separated silica particles were subjected to Si CP / MAS NMR analysis with Bruker AVANCE III 400 to determine the peak areas according to the number of substitutions of SiO, and each of the two substitutions (Si (OH) ₂ (0-Si) ₂ -), 3-substituted (Si (OH) (0- Si) 3 -), 4 -substituted _{(Si (0-Si) 4} -) the value of the Q2, Q3, Q4, the condensation ratio of hydrophobic treatment agent formula : (Q2 × 2 + Q3 × 3 + Q4 × 4) / 4 × (Q2 + Q3 + Q4)

The volume resistivity of the silica particles may be, for example, 10 ¹¹ Ωcm or more, desirably 10 ¹² Ωcm or more, and more desirably 10 ¹³ Ωcm or more.
When the volume resistivity of the silica particles is set in the above range, a decrease in electrical characteristics is suppressed.

The volume resistivity of the silica particles is measured as follows. The measurement environment is a temperature of 20 ° C. and a humidity of 50% RH.
First, silica particles are separated from the layer. Then, the separated silica particles to be measured are placed on the surface of a circular jig provided with a 20 cm ² electrode plate so as to have a thickness of about 1 mm or more and 3 mm or less to form a silica particle layer. A 20 cm ² electrode plate similar to the above is placed on this and the silica particle layer is sandwiched. In order to eliminate voids between the silica particles, a load of 4 kg is applied on the electrode plate placed on the silica particle layer, and then the thickness (cm) of the silica particle layer is measured. Both electrodes above and below the silica particle layer are connected to an electrometer and a high voltage power generator. A high voltage is applied to both electrodes so that the electric field has a predetermined value, and the current value (A) flowing at this time is read to calculate the volume resistivity (Ωcm) of the silica particles. The calculation formula of the volume resistivity (Ωcm) of the silica particles is as shown in the following formula.
In the formula, ρ is the volume resistivity (Ωcm) of the silica particles, E is the applied voltage (V), I is the current value (A), I ₀ is the current value (A) at an applied voltage of 0 V, and L is the silica particles. Each layer thickness (cm) is expressed. In this evaluation, the volume resistivity when the applied voltage was 1000 V was used.
Formula: ρ = E × 20 / (I−I ₀ ) / L

Specific examples of the binder resin used for the charge transport layer include polycarbonate resins (homopolymerized types such as bisphenol A, bisphenol Z, bisphenol C, and bisphenol TP, or copolymerized types thereof), polyarylate resins, and polyesters. Resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl acetate resin, styrene-butadiene copolymer, vinyl chloride-acetic acid Vinyl copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-acrylic copolymer, ethylene-alkyd resin, poly-N Vinylcarbazole resins, polyvinyl butyral resins, and polyphenylene ether resin. These binder resins are used alone or in combination of two or more.
The mixing ratio of the charge transport material and the binder resin is preferably 10: 1 to 1: 5 by mass ratio.

  Among the above binder resins, polycarbonate resins (homopolymerized types such as bisphenol A, bisphenol Z, bisphenol C, and bisphenol TP, or copolymerized types thereof) are preferable. A polycarbonate resin may be used individually by 1 type, and may be used together 2 or more types. Moreover, it is more preferable that the homopolymerization type polycarbonate resin of bisphenol Z is included among polycarbonate resins by the same point.

  Note that the binder resin may be used in combination with a binder resin having a viscosity average molecular weight of less than 50,000.

  From the viewpoint of suppressing the occurrence of scratches on the inorganic protective layer, the binder resin preferably has, for example, a viscosity average molecular weight of 50,000 or less. It may be 45000 or less, and may be 35000 or less. The lower limit of the viscosity average molecular weight is preferably 20000 or more from the viewpoint of maintaining the properties as a binder resin.

Here, the measurement of the viscosity average molecular weight of the binder resin uses the following one-point measurement method.
First, after peeling off the inorganic protective layer from the photoreceptor to be measured, the photosensitive layer to be measured is exposed. Then, a part of the photosensitive layer is scraped to prepare a measurement sample.
Next, the binder resin is extracted from the measurement sample. 1 g of the extracted binder resin is dissolved in 100 cm ³ of methylene chloride, and its specific viscosity ηsp is measured with an Ubbelohde viscometer in a measurement environment at 25 ° C. Then, a relational expression of ηsp / c = [η] +0.45 [η] ² c (where c is the intrinsic viscosity [η] (cm ³ / g) from the concentration (g / cm ³ ) is calculated by H. Schnell. The viscosity average molecular weight Mv is determined from the given equation [η] = 1.23 × 10 ⁻⁴ Mv ^0.83 .

  In addition, the charge transport layer may contain a known additive.

  The formation of the charge transport layer is not particularly limited, and a known formation method is used. For example, a coating film of a charge transport layer forming coating solution in which the above components are added to a solvent is formed, and the coating film is dried. This is done by heating as necessary.

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

  Coating methods for applying the charge transport layer forming coating solution on the charge generation layer include blade coating method, wire bar coating method, spray coating method, dip coating method, bead coating method, air knife coating method, curtain A usual method such as a coating method may be mentioned.

  When particles (for example, silica particles or fluororesin particles) are dispersed in the charge transport layer forming coating solution, the dispersion method may be media dispersion such as ball mill, vibration ball mill, attritor, sand mill, horizontal sand mill, etc. A medialess disperser such as an agitator, an agitator, an ultrasonic disperser, a roll mill, or a high-pressure homogenizer is used. Examples of the high-pressure homogenizer include a collision method in which a dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision in a high pressure state, and a penetration method in which a fine flow path is dispersed in a high pressure state.

The surface roughness Ra (arithmetic average surface roughness Ra) of the surface on the inorganic protective layer side in the charge transport layer is, for example, 0.06 μm or less, preferably 0.03 μm or less, more preferably 0.02 μm or less. is there.
When the surface roughness Ra is in the above range, the smoothness of the inorganic protective layer is increased and the cleaning property is improved.
In order to set the surface roughness Ra within the above range, for example, a method of increasing the thickness of the layer can be used.

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

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

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

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

(Inorganic protective layer)
-Composition of the inorganic protective layer-
The inorganic protective layer in the electrophotographic photoreceptor of this embodiment is composed of the following materials.
That is, the sum of the elemental composition ratios of the group 13 element and oxygen with respect to all the elements containing the group 13 element and oxygen and constituting the inorganic protective layer is 0.70 or more.
In particular, the material constituting the inorganic protective layer in the electrophotographic photosensitive member of the first embodiment has an element composition ratio of oxygen and a group 13 element (oxygen / group 13 element) of 1.10 or more and 1.30 or less. A first region and a second region in which oxygen / group 13 element is 1.40 or more and 1.50 or less are included. Then, the first region and the second region are provided in this order on the photosensitive layer, and the second region is the uppermost layer. The group 13 element is preferably gallium in terms of suppressing the increase in the residual potential while ensuring the sensitivity. In addition, since the Group 13 element is gallium, the occurrence of scratches on the inorganic protective layer is easily suppressed.

  In the first region, the elemental composition ratio of oxygen and the group 13 element (oxygen / group 13 element) is 1.20 or more and 1.30 or less in terms of suppressing the increase in the residual potential while ensuring the sensitivity. It is preferable that it is 1.25 or more and 1.30 or less. In the same way, in the second region, the elemental composition ratio of oxygen and the Group 13 element (oxygen / Group 13 element) is preferably 1.45 or more and 1.50 or less, and 1.47 or more and 1 .50 or less is preferable.

Here, in each of the first region and the second region, when each elemental composition ratio (oxygen / Group 13 element (particularly gallium)) is within the above range, the volume resistivity in each region can be easily controlled. Become. That is, the volume resistivity in the first region is 2.0 × 10 ⁷ Ωcm or more and 1.0 × 10 ¹⁰ Ωcm or less, and the volume resistivity in the second region is 2 × 10 ¹⁰ Ωcm or more and 1 It becomes easy to satisfy the range of 0.0 × 10 ¹¹ Ωcm or less. In this respect, the material constituting each region of the inorganic protective layer of the electrophotographic photosensitive member according to the second embodiment is the material constituting each region of the inorganic protective layer of the electrophotographic photosensitive member according to the first embodiment. It is good that it is the same material as.

  Further, the sum of the elemental composition ratios of the group 13 element (particularly gallium) and oxygen with respect to all the elements constituting the inorganic surface layer is 0.70 or more, for example, 15 such as N, P, As, etc. When a group element or the like is mixed, the effect of combining these with a group 13 element (especially gallium) is suppressed, and the composition of oxygen and group 13 element (particularly gallium) that can improve the hardness and electrical properties of the inorganic surface layer. It becomes easy to find an appropriate range of the ratio (oxygen / Group 13 element (especially gallium)). In view of the above, the sum of the elemental composition ratios is preferably 0.75 or more, preferably 0.80 or more, and more preferably 0.85 or more.

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

Here, for example, when the inorganic protective layer is configured to include gallium, oxygen, and hydrogen as necessary, from the viewpoint of excellent mechanical strength, translucency, flexibility, and excellent conductivity controllability. The preferred elemental composition ratios are as follows.
The elemental composition ratio of gallium is, for example, preferably 0.20 or more and 0.50 or less, preferably 0.25 or more and 0.40 or less, and more preferably 0.000 or less with respect to all the constituent elements of the inorganic protective layer. 30 or more and 0.40 or less.
The elemental composition ratio of oxygen is, for example, preferably 0.30 or more and 0.70 or less, preferably 0.30 or more and 0.60 or less, and more preferably 0.000 or less with respect to all the constituent elements of the inorganic protective layer. 35 or more and 0.55 or less.
The elemental composition ratio of hydrogen is, for example, preferably 0.10 or more and 0.40 or less, preferably 0.10 or more and 0.30 or less, more preferably 0.00 with respect to all the constituent elements of the inorganic protective layer. 15 or more and 0.25 or less.

Here, the elemental composition ratio, the atomic ratio, etc. of each element in the inorganic protective layer are determined by Rutherford back scattering (hereinafter referred to as “RBS”) including the distribution in the thickness direction. NEC 3SDH Pelletron, CE & A RBS-400 as the end station, and 3S-R10 as the system are used. 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 about 109 ° with respect to the incident beam.

Specifically, the RBS measurement is performed as follows. First, a He ++ ion beam is incident perpendicularly to the sample, the detector is set at 160 ° with respect to the ion beam, and the back scattered He signal is measured. Measure. 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 only 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. From the measured composition, the density is assumed by calculation, and the thickness is calculated using this. The density error is within 20%.

The elemental composition ratio of hydrogen is obtained by hydrogen forward scattering (hereinafter referred to as “HFS”).
In HFS measurement, NEC 3SDH Pelletron is used as an accelerator, CE & A RBS-400 is used as an end station, and 3S-R10 is used as a system. The analysis uses the CE & A HYPRA program. And the measurement conditions of HFS are as follows.
-He ++ ion beam energy: 2.275 eV
Detection angle: Grazing Angle 30 ° with respect to 160 ° 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.

-Characteristics of inorganic protective layer-
As described above, the inorganic protective layer in the electrophotographic photosensitive member according to the second embodiment includes the first region having a volume resistivity of 2.0 × 10 ⁷ Ωcm or more and 1.0 × 10 ¹⁰ Ωcm or less, and a volume resistance. The second region has a rate of 2.0 × 10 ¹⁰ Ωcm or more.
4. The volume resistivity of the first region is preferably 1.0 × 10 ⁸ Ωcm or more and 1.0 × 10 ¹⁰ Ωcm or less in terms of suppressing the increase of the residual potential while ensuring the sensitivity. It is preferably 0 × 10 ⁸ Ωcm or more and 5.0 × 10 ⁹ Ωcm or less. In similar terms, the volume resistivity of the second region may be at 3.0 × ^{10 10} Ωcm or more, and preferably 4.0 × ^{10 10} Ωcm or more. In addition, although the upper limit of the volume resistivity of a 2nd area | region is not specifically limited, For example, 1.0 * 10 < ¹¹ > ohm-cm or less is mentioned.
The volume resistivity in each region of the inorganic protective layer of the electrophotographic photoreceptor according to the first embodiment is the range of the volume resistivity in each region of the inorganic protective layer of the electrophotographic photoreceptor according to the second embodiment. It is good to satisfy.

This volume resistivity is obtained by calculation based on the electrode area and the sample thickness from the resistance value measured under the conditions of a frequency of 1 kHz and a voltage of 1 V using an LF meter ZM2371 manufactured by nF.
The measurement sample is a sample obtained by depositing a film on an aluminum substrate under the same conditions as the measurement of the inorganic protective layer to be measured, and forming a gold electrode on the film by vacuum deposition. Alternatively, it may be a sample in which the inorganic protective layer is peeled off from the electrophotographic photosensitive member after fabrication, and is partially etched, and is sandwiched between a pair of electrodes.

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

The elastic modulus of the entire inorganic protective layer is preferably 30 GPa or more and 80 GPa or less, and preferably 40 GPa or more and 65 GPa or less.
When this elastic modulus is within the above range, the formation of concave portions (scratch-like scratches), peeling and cracking of the inorganic protective layer can be easily suppressed.
This elastic modulus is an average value obtained from a measured value from an indentation depth of 30 nm to 100 nm by obtaining a depth profile by a continuous stiffness method (CSM) (US Pat. No. 4,848,141) using Nano Instor SA2 manufactured by MTS Systems. Is used. The following are the measurement conditions.
・ Measurement environment: 23 ℃, 55% RH
-Indenter used: Diamond regular triangular pyramid indenter (Berkovic indenter) triangular pyramid indenter-Test mode: CSM mode Note that the measurement sample is a sample formed on the substrate under the same conditions as those for forming the inorganic protective layer to be measured. Alternatively, a sample obtained by peeling off the inorganic protective layer from the electrophotographic photoreceptor after production and partially etching it may be used.

  In the electrophotographic photoreceptor according to the present exemplary embodiment, the thickness of the first region is preferably smaller than the thickness of the second region in terms of suppressing an increase in residual potential while ensuring sensitivity. Similarly, the ratio of the thickness of the second region to the thickness of the first region (the thickness of the second region / the thickness of the first region) is 3 to 100 (preferably, 10 or more and 100 or less, more preferably 10 or more and 30 or less.

  Furthermore, the thickness of the first region is 0.01 μm or more and 0.1 μm or less (preferably 0.03 μm or more and 0.09 μm or less) from the viewpoint of suppressing the increase in the residual potential while ensuring the sensitivity. Is good. In the same manner, the thickness of the second region is preferably 0.3 μm to 1.0 μm (preferably 0.4 μm to 0.9 μm).

In the electrophotographic photoreceptor according to the exemplary embodiment, the total thickness of the inorganic protective layer is preferably, for example, more than 1.5 μm and not more than 10 μm, preferably not less than 3 μm and not more than 10 μm, and preferably not less than 3 μm and not more than 6 μm. The following is more preferable.
When the total film thickness of the inorganic protective layer is within the above range, the occurrence of scratches on the inorganic protective layer is easily suppressed.

-Formation of inorganic protective layer-
For the formation of the inorganic protective layer, for example, a known vapor deposition method such as plasma CVD (Chemical Vapor Deposition), metal organic vapor phase epitaxy, molecular beam epitaxy, vapor deposition, sputtering or the like is used.

  Hereinafter, the formation of the inorganic protective layer will be described with reference to specific examples while showing an example of the film forming apparatus in the drawings. In addition, although the following description shows the formation method of the inorganic protective layer comprised including gallium, oxygen, and hydrogen, it is not restricted to this, According to the composition of the target inorganic protective layer, a well-known formation method Should be applied.

  FIG. 5 is a schematic diagram showing an example of a film forming apparatus used for forming the inorganic protective layer of the electrophotographic photosensitive member according to the present embodiment. FIG. 5A is a case where the film forming apparatus is viewed from the side. 5B is a schematic cross-sectional view taken along line A1-A2 of the film formation apparatus illustrated in FIG. 5A. In FIG. 5, 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 for injecting gas introduced from the gas introduction pipe 215. A shower nozzle having an opening, 217 is a plasma diffusion unit, 218 is a high-frequency power supply unit, 219 is a flat plate electrode, 220 is a gas introduction tube, and 221 is a high-frequency discharge tube unit.

In the film forming apparatus shown in FIG. 5, 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. 6 may be used instead of the plasma generator provided in the deposition apparatus shown in FIG. FIG. 6 is a schematic diagram showing another example of the plasma generator used in the film forming apparatus shown in FIG. 5, and is a side view of the plasma generator. In FIG. 6, 222 is a high frequency coil, 223 is a quartz tube, and 220 is the same as that shown in FIG. This plasma generator is composed of 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. 6). Connected with. 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. 5, a rod-shaped shower nozzle 216 extending along the discharge surface is connected to the discharge surface side of the 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 organic photosensitive layer is used.

The inorganic protective layer is formed as follows, for example.
First, oxygen gas (or helium (He) diluted oxygen gas), helium (He) gas, and hydrogen (H ₂ ) gas as needed are introduced into the high-frequency discharge tube portion 221 from the gas introduction tube 220, and 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 hydrogen is formed.
As the substrate 214, for example, a substrate on which an organic photosensitive layer is formed is used.

The temperature of the surface of the substrate 214 during the formation of the inorganic protective layer is preferably 150 ° C. or lower, more preferably 100 ° C. or lower, and particularly preferably 30 ° C. or higher and 100 ° C. or lower because an organic photoreceptor having an organic photosensitive layer is used.
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.
The temperature of the surface of the substrate 214 may be controlled by a heating means, a cooling means (not shown in the figure) or the like, or may be left to a natural temperature rise 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 inorganic protective layer, trimethylindium is introduced into the deposition chamber 210 through the gas introduction tube 215 and the shower nozzle 216, thereby forming a film containing nitrogen and indium on the substrate 214. In this case, the film absorbs ultraviolet rays that are generated when the film is continuously formed and deteriorate the organic photosensitive layer. For this reason, damage to the organic photosensitive layer due to generation of ultraviolet rays during film formation is suppressed.

Further, as a dopant doping method during film formation, SiH ₃ and SnH ₄ are used for n-type, and biscyclopentadienylmagnesium, dimethyl calcium, dimethylstrontium, etc. are used in a gas state for p-type. use. 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. An inorganic protective layer is obtained.

In the film formation apparatus described with reference to FIGS. 5 and 6, active nitrogen or active hydrogen formed by discharge energy may be controlled independently by providing a plurality of active apparatuses, or may be combined 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 (inorganic protective layer) constituting a three-dimensional bond is formed.

The plasma generating means of the film forming apparatus shown in FIGS. 5 and 6 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. 5 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.

  For forming the inorganic protective layer, for example, the base 214 having an organic photosensitive layer formed on the base is placed in the film forming chamber 210, and mixed gases having different compositions are introduced to form the inorganic protective layer.

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 214, it is desirable to 0.01 W / cm ² or more 0.2 W / cm ² or less in the range of the surface area of the substrate. The rotation speed of the substrate 214 is desirably in the range of 0.1 rpm to 500 rpm.

  The element composition ratio (oxygen / Group 13 element) and volume resistivity of the first region and the second region of the inorganic protective layer are adjusted by controlling the pressure and high-frequency power of the plasma generator, for example. The Further, the flow rate is adjusted by the flow ratio of trimethylgallium, helium-diluted oxygen, and hydrogen supplied to the plasma generator. Specifically, it is adjusted by the flow ratio of trimethylgallium and helium diluted oxygen. The thicknesses of the first region and the second region are adjusted according to the supply time of trimethylgallium and helium-diluted oxygen supplied to the plasma generator.

As described above, an example in which the organic photosensitive layer is a function separation type and the charge transport layer is a single layer type as an electrophotographic photoreceptor has been described. However, the electrophotographic photoreceptor shown in FIG. In the case where the transport layer is a multilayer type), the charge transport layer 3A in contact with the inorganic protective layer 5 has the same configuration as the charge transport layer 3 of the electrophotographic photosensitive member shown in FIG. The charge transport layer 3B not to be used may have the same configuration as a known charge transport layer.
However, the thickness of the charge transport layer 3A is preferably 1 μm or more and 15 μm or less. The film thickness of the charge transport layer 3B is preferably 15 μm or more and 29 μm or less.

On the other hand, in the case of the electrophotographic photosensitive member shown in FIG. 3 (example in which the organic photosensitive layer is a single layer type), the single layer type organic photosensitive layer 6 (charge generation / charge transporting layer) is the charge transporting layer of the electrophotographic photosensitive member. 3 and the charge generating material are preferably used except that the charge generating material is included.
However, the content of the charge generating material in the single-layer type organic photosensitive layer 6 is 0.1% by mass or more and 10% by mass or less (preferably 0.8% by mass or more and 5% or less) with respect to the entire single-layer type organic photosensitive layer. Mass% or less). The content of the charge transport material is preferably 5% by mass or more and 50% by mass or less with respect to the total solid content.
The film thickness of the single-layer type organic photosensitive layer 6 is preferably 15 μm or more and 30 μm or less.

Further, the inorganic protective layer may be formed on the photosensitive layer by repeatedly laminating a combination of the first region and the second region in this order.
For example, in the electrophotographic photosensitive member shown in FIG. 4, an example in which the inorganic protective layer is configured by repeating the combination of the first region and the second region in the order of three repetitions. Is shown. Note that the number of repetitions represents the number of repetitions of this unit, with the combination of the first region and the second region stacked in this order from the photosensitive layer side as one unit. The number of repetitions of the repeated combination of the combination of the first region and the second region may be two times, for example. The number of repetitions of the first region and the second region is preferably 3 or more and 10 or less from the viewpoint of further suppressing the increase in the residual potential while ensuring the sensitivity. The number of repetitions may be 4 times or more, or 5 times or more. Further, it may be 9 times or less, or 8 times or less.

  In the formation of the inorganic protective layer, each layer may be formed continuously by introducing mixed gases having different compositions according to the target elemental composition ratio or volume resistivity, or separately. It may be done independently. Moreover, what is necessary is just to select the film-forming conditions for each layer according to the element composition ratio or volume resistivity made into the objective.

[Image forming apparatus (and process cartridge)]
The image forming apparatus according to the present embodiment includes an electrophotographic photosensitive member, a charging unit that charges the surface of the electrophotographic photosensitive member, and an electrostatic latent image formation that forms an electrostatic latent image on the surface of the charged electrophotographic photosensitive member. Means, developing means for developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner to form a toner image, and transfer means for transferring the toner image to the surface of the recording medium; Is provided. The electrophotographic photosensitive member according to the present embodiment is applied as the electrophotographic photosensitive member.

  The image forming apparatus according to the present embodiment includes an apparatus having fixing means for fixing a toner image transferred to the surface of a recording medium; direct transfer for directly transferring the toner image formed on the surface of the electrophotographic photosensitive member to the recording medium Type apparatus; intermediate transfer in which the toner image formed on the surface of the electrophotographic photosensitive member is primarily transferred onto the surface of the intermediate transfer member, and the toner image transferred onto the surface of the intermediate transfer member is secondarily transferred onto the surface of the recording medium. Type of apparatus; apparatus with cleaning means for cleaning the surface of the electrophotographic photosensitive member after the toner image is transferred and before charging; after the toner image is transferred, the surface of the electrophotographic photosensitive member is irradiated with a charge eliminating light before charging. A known image forming apparatus such as an apparatus provided with an electrophotographic photoreceptor heating member for raising the temperature of the electrophotographic photoreceptor and reducing the relative temperature is applied.

  In the case of an intermediate transfer type apparatus, the transfer means includes, for example, an intermediate transfer body on which a toner image is transferred to the surface, and a primary transfer that primarily transfers the toner image formed on the surface of the electrophotographic photosensitive member to the surface of the intermediate transfer body. A configuration including a transfer unit and a secondary transfer unit that secondarily transfers the toner image transferred onto the surface of the intermediate transfer member onto the surface of the recording medium is applied.

  The image forming apparatus according to the present embodiment may be either a dry developing type image forming apparatus or a wet developing type (developing type using a liquid developer).

  In the image forming apparatus according to the present embodiment, for example, the part including the electrophotographic photosensitive member may have a cartridge structure (process cartridge) that is detachable from the image forming apparatus. As the process cartridge, for example, a process cartridge including the electrophotographic photosensitive member according to this embodiment is preferably used. In addition to the electrophotographic photosensitive member, the process cartridge may include at least one selected from the group consisting of a charging unit, an electrostatic latent image forming unit, a developing unit, and a transfer unit.

  Hereinafter, an example of the image forming apparatus according to the present embodiment will be described, but the present invention is not limited thereto. In addition, the main part shown to a figure is demonstrated and the description is abbreviate | omitted about others.

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 100 according to this embodiment includes a process cartridge 300 including an electrophotographic photosensitive member 7, an exposure device 9 (an example of an electrostatic latent image forming unit), and a transfer device 40 (primary. Transfer device) and an intermediate transfer member 50. In the image forming apparatus 100, the exposure device 9 is disposed at a position where the electrophotographic photosensitive member 7 can be exposed from the opening of the process cartridge 300, and the transfer device 40 is interposed between the electrophotographic photosensitive member via the intermediate transfer member 50. 7, and a part of the intermediate transfer member 50 is disposed in contact with the electrophotographic photosensitive member 7. Although not shown, it also has a secondary transfer device that transfers the toner image transferred to the intermediate transfer member 50 to a recording medium (for example, paper). The intermediate transfer member 50, the transfer device 40 (primary transfer device), and the secondary transfer device (not shown) correspond to an example of a transfer unit. In the image forming apparatus 100, the control device 60 (an example of a control unit) is a device that controls the operation of each device and each member in the image forming device 100, and is connected to each device and each member. ing.

  In the process cartridge 300 in FIG. 7, an electrophotographic photosensitive member 7, a charging device 8 (an example of a charging unit), a developing device 11 (an example of a developing unit), and a cleaning device 13 (an example of a cleaning unit) are integrated in a housing. I support it. The cleaning device 13 includes a cleaning blade (an example of a cleaning member) 131, and the cleaning blade 131 is disposed so as to contact the surface of the electrophotographic photosensitive member 7. The cleaning member may be a conductive or insulating fibrous member instead of the cleaning blade 131, and may be used alone or in combination with the cleaning blade 131.

  In FIG. 7, as an image forming apparatus, a fibrous member 132 (roll shape) for supplying the lubricant 14 to the surface of the electrophotographic photosensitive member 7 and a fibrous member 133 (flat brush shape) for assisting cleaning are shown. Examples are provided, but these are arranged as necessary.

  Hereinafter, each configuration of the image forming apparatus according to the present embodiment will be described.

-Charging device-
As the charging device 8, for example, a contact type charger using a conductive or semiconductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube or the like is used. Further, a non-contact type roller charger, a known charger such as a scorotron charger using a corona discharge or a corotron charger may be used.

-Exposure device-
Examples of the exposure device 9 include optical system devices that expose the surface of the electrophotographic photoreceptor 7 with light such as semiconductor laser light, LED light, and liquid crystal shutter light in a predetermined image-like manner. The wavelength of the light source is set within the spectral sensitivity region of the electrophotographic photosensitive member. As the wavelength of the semiconductor laser, near infrared having an oscillation wavelength near 780 nm is the mainstream. However, the present invention is not limited to this wavelength, and an oscillation wavelength laser in the 600 nm range or a laser having an oscillation wavelength of 400 nm to 450 nm as a blue laser may be used. In addition, a surface-emitting type laser light source that can output a multi-beam is also effective for color image formation.

-Developer-
Examples of the developing device 11 include a general developing device that performs development by bringing a developer into contact or non-contact with the developer. The developing device 11 is not particularly limited as long as it has the functions described above, and is selected according to the purpose. For example, a known developing device having a function of attaching a one-component developer or a two-component developer to the electrophotographic photosensitive member 7 using a brush, a roller, or the like can be used. Among these, those using a developing roller holding the developer on the surface are preferable.

  The developer used in the developing device 11 may be a one-component developer including a toner alone or a two-component developer including a toner and a carrier. Further, the developer may be magnetic or non-magnetic. A well-known thing is applied for these developers.

-Cleaning device-
As the cleaning device 13, a cleaning blade type device including a cleaning blade 131 is used.
In addition to the cleaning blade method, a fur brush cleaning method and a simultaneous development cleaning method may be employed.

-Transfer device-
Examples of the transfer device 40 include known transfer chargers such as 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, and a corotron transfer charger. Can be mentioned.

-Intermediate transfer member-
As the intermediate transfer member 50, a belt-like member (intermediate transfer belt) containing polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber or the like having semiconductivity is used. Further, as the form of the intermediate transfer member, a drum-like member may be used in addition to the belt-like member.

-Control device-
The control device 60 is configured as a computer that controls the entire device and performs various calculations. Specifically, the control device 60 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory) storing various programs, and a RAM (Random Access Memory) used as a work area when executing the programs. ), A nonvolatile memory for storing various information, and an input / output interface (I / O). Each of the CPU, ROM, RAM, nonvolatile memory, and I / O is connected via a bus. Each part of the image forming apparatus 100 such as the electrophotographic photosensitive member 7 (including the drive motor 30), the charging device 8, the exposure device 9, the developing device 11, and the transfer device 40 is connected to the I / O.

  Note that the CPU executes, for example, a program (for example, a control program for an image forming sequence or a recovery sequence) stored in a ROM or a nonvolatile memory, and controls the operation of each unit of the image forming apparatus 100. The RAM is used as a work memory. The ROM and the non-volatile memory store, for example, programs executed by the CPU and data necessary for the processing of the CPU. Note that the control program and various data may be stored in another storage device such as a storage unit, or may be acquired from the outside via the communication unit.

  Various drives may be connected to the control device 60. As various drives, data is read from a computer-readable portable recording medium such as a flexible disk, magneto-optical disk, CD-ROM, DVD-ROM, USB (Universal Serial Bus) memory, etc. And a device for writing. When various types of drives are provided, a control program may be recorded on a portable recording medium, and this may be read and executed by a corresponding drive.

FIG. 8 is a schematic configuration diagram illustrating another example of the image forming apparatus according to the present embodiment.
An image forming apparatus 120 shown in FIG. 8 is a tandem multicolor image forming apparatus equipped with four process cartridges 300. In the image forming apparatus 120, four process cartridges 300 are arranged in parallel on the intermediate transfer member 50, and one electrophotographic photosensitive member is used for one color. The image forming apparatus 120 has the same configuration as that of the image forming apparatus 100 except that it is a tandem system.

  Note that the image forming apparatus 100 according to the present embodiment is not limited to the above configuration, and is, for example, a cleaning device around the electrophotographic photosensitive member 7 and downstream of the transfer device 40 in the rotation direction of the electrophotographic photosensitive member 7. The first toner neutralizing device may be provided on the upstream side of the rotation direction of the electrophotographic photosensitive member with respect to 13 so that the polarity of the remaining toner is aligned and easily removed with a cleaning brush. Alternatively, a configuration may be adopted in which a second static elimination device for neutralizing the surface of the electrophotographic photosensitive member 7 is provided on the downstream side in the rotation direction of the electrophotographic photosensitive member and on the upstream side in the rotational direction of the electrophotographic photosensitive member relative to the charging device 8. .

  In addition, the image forming apparatus 100 according to the present embodiment is not limited to the above-described configuration, and a well-known configuration, for example, a direct transfer type image forming apparatus that directly transfers a toner image formed on the electrophotographic photoreceptor 7 to a recording medium. It may be adopted.

  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.

[Preparation and production of silica particles]
-Silica particles-
1,1,1,3,3,3-hexamethyldisilazane (Tokyo Chemical Industry Co., Ltd.) as a hydrophobizing agent on 100 parts by mass of untreated (hydrophilic) silica particles “trade name: OX50 (manufactured by Aerosil)” 30 parts by mass) were added and reacted for 24 hours, and then filtered to obtain hydrophobized silica particles. The condensation rate of the silica particles was 93%. The silica particles have a trimethylsilyl group on the surface. The volume average particle diameter of the silica particles is 40 nm.

<Example 1>
-Production of undercoat layer-
100 parts by mass of zinc oxide (average particle diameter 70 nm: manufactured by Teika: specific surface area value 15 m ² / g) is stirred and mixed with 500 parts by mass of tetrahydrofuran, and a silane coupling agent (KBM503: manufactured by Shin-Etsu Chemical Co., Ltd.) 1.3 parts by mass Part was added and stirred for 2 hours. Tetrahydrofuran was then distilled off under reduced pressure and baked at 120 ° C. for 3 hours to obtain a silane coupling agent surface-treated zinc oxide.
110 parts by mass of the surface-treated zinc oxide was stirred and mixed with 500 parts by mass of tetrahydrofuran, a solution prepared by dissolving 0.6 parts by mass of alizarin in 50 parts by mass of tetrahydrofuran was added, and the mixture was stirred at 50 ° C. for 5 hours. did. Then, the zinc oxide to which alizarin was imparted by filtration under reduced pressure was filtered off, and further dried at 60 ° C. under reduced pressure to obtain alizarin imparted zinc oxide.
60 parts by mass of this alizarin-provided zinc oxide, 13.5 parts by mass of a curing agent (blocked isocyanate Sumijoule 3175, manufactured by Sumitomo Bayern Urethane Co., Ltd.), and 15 parts by mass of butyral resin (ESLEC BM-1, manufactured by Sekisui Chemical Co., Ltd.) Were mixed with 85 parts by mass of methyl ethyl ketone to obtain a mixed solution. 38 parts by mass of this mixed liquid and 25 parts by mass of methyl ethyl ketone were mixed, and dispersed for 2 hours with a sand mill using 1 mmφ glass beads to obtain a dispersion.
Dioctyltin dilaurate: 0.005 parts by mass and 40 parts by mass of silicone resin particles (Tospearl 145, manufactured by Momentive Performance Materials) are added to the resulting dispersion as a catalyst to obtain a coating solution for forming an undercoat layer. It was. This coating solution is applied onto an aluminum substrate having an outer diameter of 30 mm, a length of 365 mm, and a thickness (thickness) of 1.0 mm by a dip coating method, followed by drying and curing at 170 ° C. for 40 minutes, and an undercoat layer having a thickness of 19 μm. Got.

-Fabrication of charge generation layer-
Positions where the Bragg angle (2θ ± 0.2 °) of the X-ray diffraction spectrum using the Cukα characteristic X-ray as a charge generation material is at least 7.3 °, 16.0 °, 24.9 °, 28.0 ° A mixture comprising 15 parts by mass of hydroxygallium phthalocyanine having a diffraction peak at 10 parts, 10 parts by mass of vinyl chloride / vinyl acetate copolymer (VMCH, manufactured by Nihon Unicar) as a binder resin, and 200 parts by mass of n-butyl acetate, Dispersion was performed in a sand mill for 4 hours using 1 mmφ glass beads. To the obtained dispersion, 175 parts by mass of n-butyl acetate and 180 parts by mass of methyl ethyl ketone were added and stirred to obtain a coating solution for forming a charge generation layer. This charge generation layer forming coating solution was dip coated on the undercoat layer and dried at room temperature (25 ° C.) to form a charge generation layer having a thickness of 0.2 μm.

-Preparation of charge transport layer-
Into 65 parts by mass of silica particles (1), 250 parts by mass of tetrahydrofuran was added, and 25 masses of 4- (2,2-diphenylethyl) -4 ′, 4 ″ -dimethyl-triphenylamine was maintained at a liquid temperature of 20 ° C. As a binder resin, 25 parts by mass of a bisphenol Z-type polycarbonate resin (viscosity average molecular weight: 30000) was added and mixed with stirring for 12 hours to obtain a coating solution for forming a charge transport layer.

  This coating solution for forming a charge transport layer was applied onto the charge generation layer and dried at 135 ° C. for 40 minutes to form a charge transport layer having a thickness of 30 μm to obtain an electrophotographic photoreceptor.

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

-Formation of inorganic protective layer-
First, Table 1 shows conditions for forming the inorganic protective layer.
The following film forming apparatus was used for forming the inorganic protective layer.
・ Method: Plasma CVD, capacitive coupling type, frequency of high frequency power supply 13.56 MHz, magnetic fluid type for substrate rotation, rotary introduction machine installed ・ Vacuum chamber shape: cylindrical type, diameter 165 mm × length 1050 mm
-Discharge electrode: Dimensions 850 mm x 85 mm, distance between discharge electrode and substrate 40 mm
・ Gas flow setting by mass flow controller ・ Vacuum evacuation by rotary pump and mechanical booster pump ・ Achieving vacuum before film formation: 1.0 × 10 ⁻² Pa
In Table 1, O ₂ gas represents He diluted 40% concentration oxygen gas, H ₂ gas represents 100% concentration hydrogen gas, TMG gas represents 100% concentration trimethyl gallium gas, and He gas represents 100% helium gas.

Moreover, each characteristic in Table 1 was measured as follows.
Atom ratio: A sample film formed to a thickness of 1.0 μm on a silicon substrate having a thickness of 0.5 mm was evaluated by EDS (energy dispersive X-ray analyzer) and the method described above.
Spectral transmittance: A sample film formed to a thickness of 1.0 μm on a quartz substrate having a thickness of 1.0 mm was evaluated for light transmittance at a wavelength of 780 nm with an ultraviolet-visible spectrophotometer.
Volume resistivity: A gold electrode having a diameter of 2 mm was formed and evaluated by a DC sputtering method on a sample film formed to a thickness of 1.0 μm on an aluminum substrate having a thickness of 1.0 mm.

(Formation of the first region)
The organic photoreceptor (1) produced above was placed on a substrate support member in the film forming chamber of the film forming apparatus, and the film forming chamber was evacuated through the exhaust port until the pressure reached 0.01 Pa. The evacuation was performed within 5 minutes after the replacement of the high-concentration oxygen-containing gas.
Next, as shown in Table 2, the film was formed under the film forming conditions of Condition 4. That is, He-diluted 40% oxygen gas (6 sccm) and H ₂ gas (500 sccm) are introduced from a gas introduction tube into a high-frequency discharge tube portion provided with a flat plate electrode having a diameter of 85 mm. A 13.56 MHz radio wave was set at an output of 500 W, matching was performed with a tuner, and discharge was performed from the plate electrode. The reflected wave at this time was 0 W.
Next, trimethylgallium gas (7.5 sccm) was introduced from the shower nozzle into the plasma diffusion portion in the film formation chamber via the gas introduction tube. At this time, the reaction pressure in the film forming chamber measured with a Baratron vacuum gauge was 25 Pa.
In this state, the organic photoreceptor (1) was formed for 4 minutes while rotating at a speed of 500 rpm, and the first region of the inorganic protective layer was formed on the surface of the charge transport layer of the organic photoreceptor (1) with a film thickness of 0. .05 μm.

(Formation of second region)
Next, the high frequency discharge was stopped and changed to He diluted 40% oxygen gas (13 sccm), H ₂ gas (500 sccm) and trimethyl gallium gas (10 sccm), and then high frequency discharge was started again.
In this state, the organophotoreceptor (1) on which the first region was formed was formed for 27 minutes while rotating at a speed of 500 rpm, and a second region having a thickness of 0.5 μm was formed on the first region. .

  Next, the first region was formed on the second region in accordance with the operation procedure for forming the first region. Further, the second region was formed again on the first region formed on the second region in accordance with the operation procedure for forming the second region. This operation is repeated, the first region and the second region are repeatedly laminated, and the first region and the second region are repeated eight times, so that the second region becomes the outermost layer. An inorganic protective layer having a total thickness of 4.4 μm was formed. The time for forming the entire inorganic protective layer was 245 minutes.

  The electrophotography of Example 1 in which an undercoat layer, a charge generation layer, a charge transport layer, and an inorganic protective layer (first region + second region) were sequentially formed on the conductive substrate through the above steps. A photoreceptor was obtained.

<Examples 2 to 17, Comparative Examples 1 to 10>
According to Table 2 and Table 3, the element composition ratio, the volume resistivity, the number of repetitions of the first region and the second region in the first region and the second region of the inorganic protective layer, the total thickness of the inorganic protective layer (Film thickness), the thickness of each region of the first region and the second region, the amount of silica particles in the charge transport layer, and the thickness (thickness) of the conductive substrate were changed as in Example 1. Thus, an electrophotographic photosensitive member of each example was obtained. In addition, the composition of the charge transport layer was adjusted so that the mass% of the silica particles became the value shown in Table 1 as an amount with respect to the entire charge transport layer.

(Evaluation)
-Evaluation of sensitivity and residual potential of photoconductor-
Using a universal scanner capable of setting a predetermined charging potential and exposure amount, the sensitivity and residual potential of each example were evaluated.
Sensitivity evaluation: Evaluated as half-exposure when charged to -700V. After charging to -700 V, the half-exposure amount (mJ / m ² ) that the photoreceptor surface potential immediately after charging becomes half (-350 V) by light irradiation (light source: semiconductor laser, wavelength 780 nm, output 5 mW). ) Was measured.
Evaluation of residual potential: The potential (V) of the photoreceptor surface after light attenuation was measured.

-Evaluation of dents and scratches on the photoreceptor-
The photoconductor obtained in each example was attached to a multifunction machine manufactured by Fuji Xerox, DocuCenter V 7775, and 10 images were continuously formed, and this was repeated to form a total of 10,000 images. Thereafter, the surface of the photoreceptor was observed with an optical microscope (field size: 500 μm × 500 μm), the number of dents and scratches was counted, and evaluated according to the following evaluation criteria. The dents (dents) and scratches were judged as follows.
Deflection shape specification: Ellipse shape with aspect ratio of 0.8 to 1.2 within maximum diameter of 50 μm. Scratch shape specification: width within 50 μm and length of 0.1 mm to 3 mm in the circumferential direction of the photoreceptor. Streaky shape-dent evaluation criteria-
A (◎): No dent observed in 10 fields of view (0)
B (◯): One dent in observation of 10 fields C (Δ): Two or more dents in observation of 10 fields, and 4 or less in dents in observation of one field D (x): 10 fields of observation Two or more dents in observation, and five or more dents in one field of view -Scratch evaluation criteria-
A (◎): No scratches observed in 20 fields of view (0)
B (◯): No flaws are observed by observation of 10 fields (0), and 1 flaw is observed by observation of 20 fields C (Δ): 1 flaw is observed by observation of 10 fields D (×): More than 2 scratches in 10 fields of view

  The conditions shown in the film formation conditions column in Tables 2 and 3 are the same as the film formation conditions shown in Table 1. In Tables 2 and 3, [Ga] + [O] represents the sum of the elemental composition ratios of gallium and oxygen with respect to all elements constituting the inorganic protective layer.

  From the above results, it can be seen that, in this example, the sensitivity is ensured and the increase in the residual potential is suppressed as compared with the comparative example.

1 subbing layer, 2 charge generation layer, 3, 3A, 3B charge transport layer, 4 conductive substrate, 5, 5A, 5B, 5C inorganic protective layer, 7, 7A, 7B, 7C, 7D electrophotographic photosensitive member, 8 Charging device, 9 Exposure device, 11 Developing device, 13 Cleaning device, 14 Lubricant, 30 Drive motor, 40 Transfer device, 50 Intermediate transfer member, 60 Control device, 100 Image forming device, 120 Image forming device, 131 Cleaning blade, 132 Fibrous member (roll shape), 133 Fibrous member (flat brush shape), 300 Process cartridge, 210 Deposition chamber, 211 Exhaust port, 212 Substrate rotating part, 213 Substrate support member, 214 Substrate, 215, 220 Gas introduction Tube, 216 shower nozzle, 217 plasma diffusion unit, 218 high frequency power supply unit, 219 plate electrode, 221 high Frequency discharge tube, 222 high frequency coil, 223 quartz tube,

Claims (15)

A conductive substrate;
An organic photosensitive layer provided on the conductive substrate;
An inorganic protective layer provided on the organic photosensitive layer, which contains a Group 13 element and oxygen, and the elemental composition ratio of the Group 13 element and oxygen to all elements constituting the inorganic protective layer A first region in which the sum of oxygen and the group composition element of oxygen and the group 13 element (oxygen / group 13 element) is 1.10 or more and 1.30 or less, and A second region having an elemental composition ratio of oxygen and the Group 13 element (oxygen / Group 13 element) of 1.40 to 1.50 on the organic photosensitive layer in this order; An inorganic protective layer in which the second region is the uppermost layer;
An electrophotographic photosensitive member comprising: A conductive substrate;
An organic photosensitive layer provided on the conductive substrate;
An inorganic protective layer provided on the organic photosensitive layer, which contains a Group 13 element and oxygen, and the elemental composition ratio of the Group 13 element and oxygen to all elements constituting the inorganic protective layer Of the first region having a volume resistivity of 2.0 × 10 ⁷ Ωcm or more and 1.0 × 10 ¹⁰ Ωcm or less and a volume resistivity of 2.0 × 10 ¹⁰ Ωcm. An inorganic protective layer having the second region as described above on the organic photosensitive layer in this order, and the second region being the uppermost layer;
An electrophotographic photosensitive member comprising:   The electrophotographic photosensitive member according to claim 1, wherein the group 13 element is gallium.   The electrophotographic photosensitive member according to claim 1, wherein a thickness of the first region is thinner than a thickness of the second region.   The electrophotographic photosensitive member according to claim 4, wherein a ratio of a thickness of the second region to a thickness of the first region (a thickness of the second region / a thickness of the first region) is 3 or more and 100 or less.   6. The electron according to claim 4, wherein the thickness of the first region is 0.01 μm or more and 0.1 μm or less, and the thickness of the second region is 0.3 μm or more and 1.0 μm or less. Photoconductor.   The electrophotographic photosensitive member according to claim 1, wherein the total thickness of the inorganic protective layer is 3 μm or more and 10 μm or less.   The electrophotographic photosensitive member according to claim 7, wherein the total thickness of the inorganic protective layer is 3 μm or more and 6 μm or less.   The electrophotographic photosensitive member according to any one of claims 1 to 8, wherein the first region and the second region are repeatedly laminated in the order of the first region and the second region. body.   The electrophotographic photosensitive member according to claim 9, wherein the number of repetitions in which the first region and the second region are repeatedly stacked in the order of 3 to 10 times.   The electrophotographic photoreceptor according to any one of claims 1 to 10, wherein the organic photosensitive layer has a layer containing a charge transport material, a binder resin, and silica particles.   The electrophotographic photosensitive member according to claim 11, wherein the content of the silica particles is 40% by mass or more and 80% by mass or less with respect to the entire layer including the charge transport material and the binder resin.   The electrophotographic photosensitive member according to claim 1, wherein the conductive substrate has a thickness of 1.5 mm or more. The electrophotographic photosensitive member according to any one of claims 1 to 13,
A process cartridge that is detachable from the image forming apparatus. The electrophotographic photoreceptor according to any one of claims 1 to 13,
Charging means for charging the surface of the electrophotographic photosensitive member;
An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member;
Developing means for developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner to form a toner image;
Transfer means for transferring the toner image to the surface of the recording medium;
An image forming apparatus comprising: