Electrophotographic photoreceptor, process cartridge, and image forming device

Abstract

The present invention relates to an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus. An electrophotographic photoreceptor comprises a conductive substrate and a photosensitive layer, wherein the outermost surface layer contains fluorine-containing resin particles, wherein (1) the fluorine atom concentration at the surface of the outermost surface layer is 1.5 to 5.0 times the fluorine atom concentration at a depth of 1 μm from the surface of the outermost surface layer; or (2) the ratio (N2 / N1) of the number density (N1) of agglomerates of the fluorine-containing resin particles in a first region of the outermost surface layer from the surface to 1 / 2 of the layer thickness to the number density (N2) of agglomerates of the fluorine-containing resin particles in a second region of the outermost surface layer from 1 / 2 of the layer thickness to the bottom of the outermost surface layer is less than 0.95, and the ratio (S2 / S1) of the area ratio (S1) of the fluorine-containing resin particles in the first region to the area ratio (S2) of the fluorine-containing resin particles in the second region is within the range of 1±0.1.

Description

Technical Field

[0001] The present invention relates to an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus. Background Art

[0002] Patent document 1 proposes "a photoreceptor characterized in that the photoreceptor contains fluororesin particles in the outermost layer of the photoreceptor, the fluorine atom content of the outermost surface of the photoreceptor increases and becomes saturated due to repeated use in an electronic photographic device, wherein the fluorine atom saturation content of the outermost surface is 20 to 60 atm%."

[0003] Patent Document 2 discloses “an electrode paste composition comprising metal particles containing copper as a main component, a flux, glass particles, a solvent, and a resin”.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2005-266036

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 2011-090214 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] The present invention provides an electrophotographic photoreceptor capable of suppressing the occurrence of image defects compared to the following cases: an electrophotographic photoreceptor comprising a conductive substrate and a photosensitive layer, wherein the outermost surface layer contains fluorine-containing resin particles, wherein the fluorine atom concentration at the surface of the outermost surface layer is less than 1.5 times or exceeds 5.0 times the fluorine atom concentration at a depth of 1 μm from the surface of the outermost surface layer; or an electrophotographic photoreceptor comprising a conductive substrate and a photosensitive layer, wherein the outermost surface layer contains fluorine-containing resin particles, and wherein the fluorine atom concentration at the depth of 1 μm from the surface of the outermost surface layer is less than 1.5 times or exceeds 5.0 times the fluorine atom concentration at a depth of 1 μm from the surface of the outermost surface layer. The ratio (S2 / S1) of the area ratio of the fluororesin particles in one region to the area ratio (S2) of the fluororesin particles in the second region of the outermost surface layer from 1 / 2 of the above-mentioned layer thickness to the bottom surface of the outermost surface layer is 1±0.1, wherein the ratio (N2 / N1) of the number density (N1) of the agglomerates of the fluororesin particles in the first region from the surface to 1 / 2 of the layer thickness of the outermost surface layer to the number density (N2) of the agglomerates of the fluororesin particles in the second region from 1 / 2 of the above-mentioned film thickness to the bottom surface of the outermost surface layer is 0.95 or more.

[0010] Means for solving problems

[0011] The above topics are discussed through the following <1> ~ <17> That is,

[0012] <1> An electrophotographic photoreceptor comprising a conductive substrate and a photosensitive layer,

[0013] The outermost surface layer contains fluorine-containing resin particles,

[0014] The fluorine atom concentration at the surface of the outermost surface layer is not less than 1.5 times and not more than 5.0 times the fluorine atom concentration at a depth of 1 μm from the surface of the outermost surface layer; or the ratio (N2 / N1) of the number density (N1) of the agglomerates of the fluorine-containing resin particles in a first region from the surface to 1 / 2 of the layer thickness of the outermost surface layer to the number density (N2) of the agglomerates of the fluorine-containing resin particles in a second region from 1 / 2 of the film thickness to the bottom surface of the outermost surface layer is less than 0.95,

[0015] The ratio (S2 / S1) of the area ratio (S1) of the above-mentioned fluorine-containing resin particles in the first region of the above-mentioned outermost surface layer from the surface to 1 / 2 of the layer thickness to the area ratio (S2) of the above-mentioned fluorine-containing resin particles in the second region of the above-mentioned outermost surface layer from 1 / 2 of the above-mentioned film thickness to the bottom surface of the above-mentioned outermost surface layer is within the range of 1±0.1.

[0016] <2> As mentioned above <1> In the electrophotographic photoreceptor, the fluorine-containing resin particles occupy an area of ​​0.33% to 1.1% of the surface area of ​​the outermost layer.

[0017] <3> As mentioned above <2> In the electrophotographic photoreceptor, the fluorine-containing resin particles occupy an area of ​​0.36% to 0.95% of the surface area of ​​the outermost layer.

[0018] <4> As mentioned above <1> ~ <3> The electrophotographic photoreceptor according to any one of the preceding claims, wherein the photosensitive layer comprises a charge generating layer and a charge transporting layer,

[0019] The outermost surface layer is the charge transport layer.

[0020] The concentration of the charge transport material at the surface of the charge transport layer is 0.4 times or more and 0.6 times or less of the concentration of the charge transport material at the center of the thickness of the charge transport layer.

[0021] <5> As mentioned above <4> In the electrophotographic photoreceptor, the concentration of the charge transport material at the surface of the charge transport layer is 0.45 to 0.56 times the concentration of the charge transport material at the center of the thickness of the charge transport layer.

[0022] <6> like <1> In the electrophotographic photoreceptor, the ratio (N2 / N1) is not less than 0.1 and not more than 0.8.

[0023] <7> like <1> or <6> The electronic photographic photosensitive body, wherein the ratio (N3 / N1) of the number density (N1) of the agglomerates of the above-mentioned fluorine-containing resin particles in the first region from the surface of the above-mentioned outermost surface layer to 1 / 2 of the layer thickness to the number density (N3) of the agglomerates of the above-mentioned fluorine-containing resin particles in the third region from 9 / 10 of the layer thickness away from the surface of the above-mentioned outermost surface layer to the bottom surface of the above-mentioned outermost surface layer is less than 0.9.

[0024] <8> like <7> In the electrophotographic photoreceptor, the ratio (N3 / N1) is 0.7 or less.

[0025] <9> like <1> 、 <6> ~ <8> The electronic photographic photosensitive body described in any one of the preceding claims, wherein the ratio (D2 / D1) of the average diameter (D1) of the agglomerates of the above-mentioned fluorine-containing resin particles in the first region of the above-mentioned outermost surface layer from the surface to 1 / 2 of the layer thickness to the average diameter (D2) of the agglomerates of the above-mentioned fluorine-containing resin particles in the second region of the above-mentioned outermost surface layer from 1 / 2 of the above-mentioned film thickness to the bottom surface of the above-mentioned outermost surface layer is greater than 2.

[0026] <10> like <9> In the electrophotographic photoreceptor, the ratio (D2 / D1) is 3 or more and 30 or less.

[0027] <11> like <1> 、 <6> ~ <10> The electrophotographic photoreceptor according to any one of the preceding claims, wherein the number density (N1) of the aggregates of the fluorine-containing resin particles in the first region from the surface to 1 / 2 of the layer thickness of the outermost layer is 5 particles / 100 μm 2 More than 50 / 100μm 2 the following.

[0028] <12> like <1> 、 <6> ~ <11> The electrophotographic photoreceptor according to any one of the preceding claims, wherein the number of carboxyl groups in the fluorine-containing resin particles is 10 6 The number of carbon atoms is 0 to 30, and the amount of the basic compound in the fluorine-containing resin particles is 0 ppm to 3 ppm.

[0029] <13> like <12> The electrophotographic photoreceptor, wherein the number of the carboxyl groups is relative to every 10 6 The number of carbon atoms is 0 to 20, and the amount of the basic compound is 0 ppm to 3 ppm.

[0030] <14> A processing box having <1> ~ <13> The electrophotographic photoreceptor according to any one of the preceding claims,

[0031] It is configured to be attached to and detached from the image forming apparatus.

[0032] <15> A processing box having <1> ~ <5> The electrophotographic photoreceptor according to any one of the preceding claims is configured to be mounted on and removed from an image forming apparatus.

[0033] The process cartridge includes a cleaning member configured to contact the electrophotographic photoreceptor to clean the electrophotographic photoreceptor.

[0034] The contact pressure of the cleaning member on the electrophotographic photoreceptor is 1.0 g / mm or more and 4.0 g / mm or less.

[0035] <16> An image forming apparatus comprising:

[0036] <1> ~ <13> The electrophotographic photoreceptor according to any one of the preceding claims;

[0037] a charging mechanism configured to charge the surface of the electrophotographic photoreceptor;

[0038] an electrostatic latent image forming mechanism configured to form an electrostatic latent image on the charged surface of the electrophotographic photoreceptor;

[0039] a developing mechanism configured to develop the electrostatic latent image formed on the surface of the electrophotographic photoreceptor using a developer containing a toner to form a toner image; and

[0040] The transfer mechanism is configured to transfer the toner image to a surface of a recording medium.

[0041] <17> An image forming apparatus comprising:

[0042] <1> ~ <5> The electrophotographic photoreceptor according to any one of the preceding claims;

[0043] a charging mechanism configured to charge the surface of the electrophotographic photoreceptor;

[0044] an electrostatic latent image forming mechanism configured to form an electrostatic latent image on the charged surface of the electrophotographic photoreceptor;

[0045] a developing mechanism configured to develop the electrostatic latent image formed on the surface of the electrophotographic photoreceptor using a developer containing a toner to form a toner image;

[0046] a transfer mechanism configured to transfer the toner image to a surface of a recording medium; and

[0047] A cleaning mechanism is configured to clean the surface of the electrophotographic photoreceptor by bringing a cleaning member into contact with the surface of the electrophotographic photoreceptor.

[0048] The contact pressure of the cleaning member on the electrophotographic photoreceptor is 1.0 g / mm or more and 4.0 g / mm or less.

[0049] Effects of the Invention

[0050] according to <1> The scheme can obtain an electrophotographic photoreceptor capable of suppressing the generation of image defects compared with the following situations: an electrophotographic photoreceptor having a conductive substrate and a photosensitive layer, the outermost surface layer containing fluorine-containing resin particles, wherein the fluorine atom concentration at the surface of the above-mentioned outermost surface layer is less than 1.5 times or exceeds 5.0 times the fluorine atom concentration at a depth of 1 μm from the surface of the above-mentioned outermost surface layer; or an electrophotographic photoreceptor having a conductive substrate and a photosensitive layer, the outermost surface layer containing fluorine-containing resin particles, and the outermost surface layer having a depth of 1 μm from the surface to 1 / 2 of the layer thickness. The ratio (S2 / S1) of the area ratio of the fluororesin particles in one region to the area ratio (S2) of the fluororesin particles in the second region of the outermost surface layer from 1 / 2 of the above-mentioned layer thickness to the bottom surface of the outermost surface layer is 1±0.1, wherein the ratio (N2 / N1) of the number density (N1) of the agglomerates of the fluororesin particles in the first region from the surface to 1 / 2 of the layer thickness of the outermost surface layer to the number density (N2) of the agglomerates of the fluororesin particles in the second region from 1 / 2 of the above-mentioned film thickness to the bottom surface of the outermost surface layer is 0.95 or more.

[0051] according to <2> or <3> According to the scheme, compared with the case where the area occupied by the above-mentioned fluorine-containing resin particles on the surface of the above-mentioned outermost surface layer is less than 0.36% or exceeds 0.95%, an electronic photographic photosensitive body capable of suppressing the generation of streak-like image defects and residual potential can be obtained, wherein the above-mentioned streak-like image defects are caused by friction between the photosensitive body and its contact components caused by vibration.

[0052] according to <4> or <5> The present invention relates to an electronic photographic photoreceptor having an outer surface having a charge transfer layer and an outermost surface having a charge transfer layer, wherein the concentration of the charge transfer material at the surface of the charge transfer layer is less than 0.45 times or exceeds 0.56 times the concentration of the charge transfer material at the center of the thickness of the charge transfer layer.

[0053] according to <6> The embodiment can provide an electrophotographic photoreceptor having both better sensitivity and wear resistance than the case where the ratio (N2 / N1) is less than 0.1 or exceeds 0.8.

[0054] according to <7> In the embodiment, compared with a case where the ratio (N3 / N1) of the number density (N1) of the agglomerates of the fluororesin particles in the first region from the surface of the outermost layer to 1 / 2 of the layer thickness to the number density (N3) of the agglomerates of the fluororesin particles in the third region from 9 / 10 of the layer thickness from the surface of the outermost layer to the bottom surface of the outermost layer exceeds 0.9, an electrophotographic photoreceptor having both improved sensitivity and wear resistance can be provided. In addition, an electrophotographic photoreceptor can be provided in which the generation of color spots caused by the incorporation of needle-shaped foreign matter is further suppressed.

[0055] according to <8> The embodiment can provide an electrophotographic photoreceptor having both better sensitivity and wear resistance than when the ratio (N3 / N1) exceeds 0.7. In addition, it can provide an electrophotographic photoreceptor in which the generation of color spots caused by the mixing of needle-shaped foreign matter is further suppressed.

[0056] according to <9> The scheme can provide an electronic photographic photosensitive body with better sensitivity and wear resistance compared to the case where the ratio (D2 / D1) of the average diameter (D1) of the agglomerates of the above-mentioned fluorine-containing resin particles in the first area from the surface to 1 / 2 of the layer thickness of the above-mentioned outermost surface layer to the average diameter (D2) of the agglomerates of the above-mentioned fluorine-containing resin particles in the second area from 1 / 2 of the above-mentioned film thickness to the bottom surface of the above-mentioned outermost surface layer is less than 2.

[0057] according to <10> The embodiment can provide an electrophotographic photoreceptor having both better sensitivity and wear resistance than the case where the ratio (D2 / D1) is less than 3 or exceeds 30.

[0058] according to <11> The embodiment of the present invention is characterized in that the number density (N1) of the aggregates of the fluorine-containing resin particles in the first region from the surface to 1 / 2 of the layer thickness of the outermost surface layer is less than 5 / 100 μm 2 Or more than 50 / 100μm 2 Compared with the case of , an electrophotographic photoreceptor having both better sensitivity and wear resistance can be provided.

[0059] according to <12> The number of carboxyl groups in the fluorine-containing resin particles is relative to 10 6 Compared with the case where the number of carbon atoms exceeds 30 and the amount of the basic compound is 0 ppm or more and 3 ppm or less, an electrophotographic photoreceptor having excellent charging properties can be provided.

[0060] according to <13> The solution is the same as the number of carboxyl groups per 10 6 Compared with the case where the number of carbon atoms is more than 20 and the amount of the basic compound is 0 ppm or more and 3 ppm or less, an electrophotographic photoreceptor having excellent charging properties can be provided.

[0061] according to <14> or <16> The solution can obtain a processing box or image forming apparatus capable of suppressing the generation of image defects compared with the following situation: an electrophotographic photoreceptor having a conductive substrate and a photosensitive layer, the outermost surface layer containing fluorine-containing resin particles, the fluorine atom concentration at the surface of the outermost surface layer being less than 1.5 times or exceeding 5.0 times the fluorine atom concentration at a depth of 1 μm from the surface of the outermost surface layer; or an electrophotographic photoreceptor having a conductive substrate and a photosensitive layer, the outermost surface layer containing fluorine-containing resin particles, and the outermost surface layer having a depth of 1 μm from the surface to 1 / 2 of the layer thickness. The ratio (S2 / S1) of the area ratio of the fluororesin particles in the first region to the area ratio (S2) of the fluororesin particles in the second region of the outermost surface layer from 1 / 2 of the above-mentioned layer thickness to the bottom surface of the outermost surface layer is within the range of 1±0.1, wherein the ratio (N2 / N1) of the number density (N1) of the agglomerates of the fluororesin particles in the first region from the surface to 1 / 2 of the layer thickness of the outermost surface layer to the number density (N2) of the agglomerates of the fluororesin particles in the second region from 1 / 2 of the above-mentioned film thickness to the bottom surface of the outermost surface layer is greater than 0.95.

[0062] according to <15> or <17> The scheme can obtain a processing box or image forming device that can suppress the occurrence of image defects compared with the following situation: a processing box or image forming device, which has an electronic photographic photoreceptor and a cleaning member that contacts the above-mentioned electronic photographic photoreceptor to clean it, the electronic photographic photoreceptor has a conductive substrate and a photosensitive layer, the outermost surface layer contains fluorine-containing resin particles, the fluorine atom concentration at the surface of the above-mentioned outermost surface layer is not less than 1.5 times and not more than 5.0 times the fluorine atom concentration at a depth of 1 μm from the surface of the above-mentioned outermost surface layer, wherein the contact pressure of the above-mentioned cleaning member on the above-mentioned electronic photographic photoreceptor is less than 1.0 g / mm or exceeds 4.0 g / mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 This is a schematic cross-sectional view showing an example of the layer structure of the electrophotographic photoreceptor according to the first embodiment.

[0064] Figure 2 This is a schematic structural diagram showing an example of the image forming apparatus according to the first and second embodiments.

[0065] Figure 3 This is a schematic structural diagram showing another example of the image forming apparatus according to the first and second embodiments.

[0066] Figure 4 This is a schematic cross-sectional view showing an example of the layer structure of the electrophotographic photoreceptor according to the second embodiment.

[0067] Figure 5 This is a schematic cross-sectional view showing another example of the layer structure of the electrophotographic photoreceptor according to the second embodiment. DETAILED DESCRIPTION

[0068] The following describes an embodiment of the present invention. These descriptions and examples are provided to illustrate the embodiment and are not intended to limit the scope of the invention.

[0069] In the numerical ranges described in stages in this specification, the upper limit or lower limit described in one numerical range may be replaced by the upper limit or lower limit of the numerical range described in another stage. In addition, in the numerical ranges described in this specification, the upper limit or lower limit of the numerical range may be replaced by the value shown in the Examples.

[0070] Each component may contain two or more corresponding substances.

[0071] When referring to the amount of each component in a composition, if two or more substances corresponding to each component are present in the composition, the amount refers to the total amount of the two or more substances present in the composition unless otherwise stated.

[0072] <First Implementation>

[0073] <Electrophotographic Photoreceptor>

[0074] The electrophotographic photoreceptor (hereinafter also referred to as "photoreceptor") of this embodiment includes a conductive substrate and a photosensitive layer provided on the conductive substrate, and the outermost surface layer contains fluorine-containing resin particles.

[0075] Furthermore, the fluorine atom concentration measured at the surface of the outermost surface layer is 1.5 to 5.0 times the fluorine atom concentration measured at a depth of 1 μm from the surface of the outermost surface layer.

[0076] The photoreceptor of this embodiment, due to the above-described configuration, can suppress the occurrence of streak-like image defects and residual potential caused by friction between the photoreceptor and its contact member due to vibration. The reason for this is presumably as follows.

[0077] When a photoreceptor containing fluorine-containing resin particles on its outermost surface layer is transported while assembled in a process cartridge or image forming apparatus, vibrations during transport can cause friction between the photoreceptor and contacting components (such as cleaning components), sometimes causing the rubbed areas of the photoreceptor to become triboelectrically charged to a positive electrode. Furthermore, if the photoreceptor is charged during image formation while areas of triboelectrically charged positive electrode exist on its surface, the surface potential of the photoreceptor may become uneven in the form of streaks, sometimes resulting in image defects. Furthermore, residual charge can remain in the photosensitive layer of the photoreceptor, sometimes resulting in a residual potential.

[0078] On the other hand, for the photoreceptor containing fluorine-containing resin particles in the outermost surface layer of this embodiment, the fluorine atom concentration measured on the surface of the outermost surface layer is not less than 1.5 times and not more than 5.0 times the fluorine atom concentration measured at a depth of 1 μm from the surface of the above-mentioned outermost surface layer. In other words, the surface of the outermost surface layer contains a large number of fluorine-containing resin particles. The fluorine-containing resin particles have a high negative polarity, so even if the photoreceptor and the components in contact with the photoreceptor rub against each other due to vibration during transportation, the positive charge generated by the friction is easily eliminated, and the frictional charging of the rubbed part of the photoreceptor to the positive electrode can be suppressed. Therefore, even if the photoreceptor is charged during image formation, the surface potential of the photoreceptor is unlikely to produce striped unevenness, and the residual potential is also suppressed.

[0079] Therefore, it is presumed that the photoreceptor of this embodiment can suppress the occurrence of streak-like image defects and residual potential caused by friction between the photoreceptor and its contact member due to vibration.

[0080] Hereinafter, the photoreceptor according to this embodiment will be described in detail.

[0081] Hereinafter, the electrophotographic photoreceptor according to this embodiment will be described with reference to the drawings.

[0082] As Figure 1 The electrophotographic photoreceptor 7A shown has a structure in which an undercoat layer 1, a charge generating layer 2, and a charge transporting layer 3 are sequentially stacked on a conductive substrate 4. The charge generating layer 2 and the charge transporting layer 3 constitute a photosensitive layer 5.

[0083] It should be noted that the electrophotographic photoreceptor 7A may have a layer structure in which the undercoat layer 1 is not provided.

[0084] Alternatively, the electrophotographic photoreceptor 7A may include a single-layer photosensitive layer integrating the functions of the charge generating layer 2 and the charge transporting layer 3. In the case of a photoreceptor including a single-layer photosensitive layer, the single-layer photosensitive layer constitutes the outermost layer.

[0085] The electrophotographic photoreceptor 7A may also include a surface protective layer on the charge transport layer 3 or a single-layer photosensitive layer. In the case of a photoreceptor including a surface protective layer, the surface protective layer constitutes the outermost layer.

[0086] Hereinafter, each layer of the electrophotographic photoreceptor of this embodiment will be described in detail.

[0087] (Conductive substrate)

[0088] Examples of the conductive substrate include metal plates, metal drums, and metal strips made of metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.). Examples of the conductive substrate include conductive compounds (e.g., conductive polymers, indium oxide, etc.), metals (e.g., aluminum, palladium, gold, etc.), or paper, resin films, and strips coated, vapor-deposited, or laminated with alloys. Here, "conductive" means a volume resistivity of less than 10 13 Ωcm.

[0089] When using an electrophotographic photoreceptor in a laser printer, the surface of the conductive substrate is preferably roughened to a centerline average roughness Ra of 0.04 μm to 0.5 μm to suppress interference fringes generated during laser irradiation. While roughening to prevent interference fringes is not particularly necessary when using non-interference light as the light source, it can help to further extend the life of the printer by suppressing defects caused by surface irregularities on the conductive substrate.

[0090] Examples of the roughening method include wet honing in which an abrasive is suspended in water and sprayed onto the conductive substrate; centerless grinding in which the conductive substrate is continuously ground by pressing it against a rotating grindstone; and anodizing.

[0091] As a method for roughening the surface, the following method can also be cited: instead of roughening the surface of the conductive substrate, conductive or semiconductive powder is dispersed in a resin to form a layer on the surface of the conductive substrate, and the surface is roughened using particles dispersed in the layer.

[0092] The roughening treatment of anodic oxidation is to form an oxide film on the surface of the conductive substrate by using a conductive substrate of a metal system (such as aluminum) as an anode and performing anodizing in an electrolyte solution. As an electrolyte solution, for example, sulfuric acid solution, oxalic acid solution, etc. can be enumerated. However, the porous anodized film formed by anodic oxidation has chemical activity in its original state, is easily contaminated, and the resistance change due to the environment is also larger. Therefore, it is preferred that the porous anodized film is subjected to the following sealing treatment: in pressurized steam or boiling water (metal salts of nickel, etc. can also be added), the volume expansion due to the hydration reaction is utilized to block the micropores of the oxide film so that it becomes a more stable hydrated oxide.

[0093] The thickness of the anodic oxide film is preferably 0.3 μm to 15 μm, for example. When the film thickness is within the above range, it tends to exhibit a barrier property against injection and to suppress an increase in residual potential due to repeated use.

[0094] The conductive substrate may be subjected to treatment with an acidic treatment liquid or boehmite treatment.

[0095] The treatment based on the acidic treatment liquid is carried out 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 can be, for example, in the range of 10% by mass to 11% by mass of phosphoric acid, 3% by mass to 5% by mass of chromic acid, and 0.5% by mass to 2% by mass of hydrofluoric acid. The overall concentration of these acids can be in the range of 13.5% by mass to 18% by mass. The treatment temperature is preferably, for example, 42°C to 48°C. The film thickness of the coating is preferably 0.3 μm to 15 μm.

[0096] Boehmite treatment can be performed, for example, by immersing the film in pure water at 90°C to 100°C for 5 to 60 minutes, or by contacting the film with heated steam at 90°C to 120°C for 5 to 60 minutes. The film thickness is preferably 0.1 μm to 5 μm. Anodization treatment can also be performed using an electrolyte solution with low film solubility, such as adipic acid, boric acid, a borate, a phosphate, a phthalate, a maleate, a benzoate, a tartrate, or a citrate.

[0097] (Base coating)

[0098] The undercoat layer is, for example, a layer containing inorganic particles and a binding resin.

[0099] Examples of inorganic particles include particles with a powder resistance (volume resistivity) of 10 2 Ωcm or more 10 11 Inorganic particles below Ωcm.

[0100] Among these, examples of the inorganic particles having the above-mentioned resistance value include metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles, and zinc oxide particles are particularly preferred.

[0101] The specific surface area of ​​the inorganic particles based on the BET method can be, for example, 10 m 2 / g or above.

[0102] The volume average particle size of the inorganic particles can be, for example, 50 nm to 2000 nm (preferably 60 nm to 1000 nm).

[0103] The content of the inorganic particles is preferably from 10% by mass to 80% by mass, and more preferably from 40% by mass to 80% by mass, based on the binder resin.

[0104] The inorganic particles may be surface-treated. Two or more inorganic particles having different surface treatments or different particle sizes may be mixed and used.

[0105] Examples of the surface treatment agent include silane coupling agents, titanate coupling agents, aluminum coupling agents, surfactants, etc. Silane coupling agents are particularly preferred, and silane coupling agents having an amino group are more preferred.

[0106] Examples of the silane coupling agent having an amino group include, but are not limited to, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane.

[0107] Silane coupling agents can be used in combination of two or more. For example, a silane coupling agent having an amino group can be used in combination with other silane coupling agents. Examples of such other silane coupling agents include vinyl trimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyl triacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane, but are not limited thereto.

[0108] 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.

[0109] The treatment amount of the surface treatment agent is preferably, for example, 0.5% by mass or more and 10% by mass or less relative to the inorganic particles.

[0110] Here, from the viewpoint of long-term stability of electrical characteristics and high carrier-blocking properties, the undercoat layer may contain an electron-accepting compound (acceptor compound) in addition to the inorganic particles.

[0111] As electron-accepting compounds, for example, there can be mentioned: quinone compounds such as chloranil and bromoaniline; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone; oxadiazole compounds such as 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole, 2,5-bis(4-naphthyl)-1,3,4-oxadiazole and 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole; xanthone compounds; thiophene compounds; electron-transporting substances such as diphenoquinone compounds such as 3,3',5,5'-tetra-tert-butyldiphenoquinone, etc.

[0112] In particular, as the electron-accepting compound, a compound having an anthraquinone structure is preferred. As the compound having an anthraquinone structure, for example, hydroxyanthraquinone compounds, aminoanthraquinone compounds, aminohydroxyanthraquinone compounds, etc. are preferred, specifically, for example, anthraquinone, alizarin, quinizarin, anthraquinone, purpurin, etc. are preferred.

[0113] The electron-accepting compound may be contained in the undercoat layer in a dispersed state together with the inorganic particles, or may be contained in the undercoat layer in a state of being attached to the surface of the inorganic particles.

[0114] Examples of a method for attaching the electron-accepting compound to the surface of the inorganic particles include a dry method and a wet method.

[0115] The dry method is, for example, a method in which the inorganic particles are stirred using a mixer having a large shearing force, while an electron-accepting compound is directly added dropwise or an electron-accepting compound dissolved in an organic solvent is added dropwise and sprayed together with dry air or nitrogen to adhere the electron-accepting compound to the surface of the inorganic particles. When the electron-accepting compound is added dropwise or sprayed, it is preferably done at a temperature below the boiling point of the solvent. After the electron-accepting compound is added dropwise or sprayed, it can be further calcined at 100°C or above. There are no particular restrictions on calcination as long as the temperature and time are such that electrophotographic properties can be obtained.

[0116] The wet method is, for example, the following method: while dispersing the inorganic particles in a solvent using stirring, ultrasonic waves, a sand mill, an attritor, a ball mill, etc., an electron accepting compound is added, and after stirring or dispersing, the solvent is removed to allow the electron accepting compound to adhere to the surface of the inorganic particles. The solvent removal method is, for example, filtration or distillation. After the solvent is removed, it can be further calcined at 100°C or above. There is no particular limitation on the calcination temperature and time as long as the electrophotographic characteristics can be obtained. In the wet method, the water contained in the inorganic particles can be removed before adding the electron accepting compound. As examples thereof, a method of removing the water by stirring and heating in a solvent and a method of removing the water by azeotropy with the solvent can be cited.

[0117] The electron-accepting compound may be attached before or after the inorganic particles are surface-treated with a surface treatment agent, or the electron-accepting compound may be attached and the surface treatment with a surface treatment agent may be performed simultaneously.

[0118] The content of the electron-accepting compound can be, for example, 0.01% by mass to 20% by mass, and preferably 0.01% by mass to 10% by mass, relative to the inorganic particles.

[0119] Examples of the adhesive resin used in the primer layer include: acetal resins (e.g., polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, unsaturated polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-modified alkyd resins, urea resins, phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, alkyd resins, epoxy resins, and other known polymer compounds; zirconium chelate compounds; titanium chelate compounds; aluminum chelate compounds; titanium alkoxide compounds; organic titanium compounds; and silane coupling agents.

[0120] Examples of the binder resin used in the primer layer include charge-transporting resins having charge-transporting groups and conductive resins (eg, polyaniline).

[0121] Among these, the binder resin for the primer layer is preferably a resin that is insoluble in the coating solvent of the upper layer, and is particularly preferably a thermosetting resin such as urea resin, phenol resin, phenol-formaldehyde resin, melamine resin, urethane resin, unsaturated polyester resin, alkyd resin, epoxy resin; or a resin obtained by reacting at least one resin selected from the group consisting of polyamide resin, polyester resin, polyether resin, methacrylic resin, acrylic resin, polyvinyl alcohol resin, and polyvinyl acetal resin with a curing agent.

[0122] When two or more of these adhesive resins are used in combination, the mixing ratio thereof is set as needed.

[0123] The undercoat layer may contain various additives in order to improve electrical characteristics, enhance environmental stability, and enhance image quality.

[0124] Examples of additives include known materials such as polycyclic condensed and azo-based electron-transporting pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. As mentioned above, silane coupling agents are used for surface treatment of inorganic particles, but can also be added to the primer layer as an additive.

[0125] Examples of the silane coupling agent as an additive include vinyltrimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0126] Examples of the zirconium chelate compound include zirconium butoxide, zirconium ethyl acetoacetate, zirconium triethanolamine, zirconium acetylacetonate butoxide, zirconium ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octanoate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, zirconium methacrylate butoxide, zirconium stearate butoxide, and zirconium isostearate butoxide.

[0127] Examples of the titanium chelate compound include tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, titanium acetylacetonate, titanium polyacetylacetonate, titanium octylene glycollate, ammonium titanium lactate, titanium lactate, ethyl titanium lactate, triethanolamine titanium, and polyhydroxy titanium stearate.

[0128] Examples of the aluminum chelate compound include aluminum isopropoxide, aluminum monobutoxide diisopropoxide, aluminum butyrate, aluminum diisopropoxide diethylacetoacetate, and aluminum tris(ethylacetoacetate).

[0129] These additives may be used alone or in the form of a mixture or polycondensate of two or more compounds.

[0130] The Vickers hardness of the primer layer may be 35 or higher.

[0131] The surface roughness (ten-point average roughness) of the undercoat layer can be adjusted to 1 / (4n) to 1 / 2 of the wavelength λ of the exposure laser used (n is the refractive index of the upper layer) to suppress moiré patterns.

[0132] To adjust the surface roughness, resin particles or the like may be added to the primer layer. Examples of the resin particles include silicone resin particles and cross-linked polymethyl methacrylate resin particles. Furthermore, to adjust the surface roughness, the primer layer may be ground. Examples of the grinding method include polishing, sandblasting, wet honing, and grinding.

[0133] The formation of the undercoat layer is not particularly limited and can be performed by a known formation method. For example, it can be formed by forming a coating film of an undercoat layer-forming coating liquid prepared by adding the above-mentioned components to a solvent, drying the coating film, and heating as needed.

[0134] Examples of the solvent used for preparing the coating liquid 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, and ester solvents.

[0135] Specific examples of these solvents include common organic solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, dichloromethane, chloroform, chlorobenzene, and toluene.

[0136] Examples of the method for dispersing the inorganic particles when preparing the coating liquid for forming an 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.

[0137] Examples of methods for applying the undercoat layer-forming coating liquid to the conductive substrate include common methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0138] The film thickness of the primer layer is preferably set within the range of, for example, 15 μm or more, and more preferably 20 μm or more and 50 μm or less.

[0139] (Middle layer)

[0140] Although not shown in the figure, an intermediate layer may be further provided between the undercoat layer and the photosensitive layer.

[0141] The intermediate layer is, for example, a layer containing a resin. Examples of the resin used for the intermediate layer include polymer compounds such as acetal resins (e.g., polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-modified alkyd resins, phenol-formaldehyde resins, and melamine resins.

[0142] The intermediate layer may be a layer containing an organic metal compound. Examples of the organic metal compound used in the intermediate layer include organic metal compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon.

[0143] These compounds for the intermediate layer may be used alone, or may be used in the form of a mixture or polycondensate of two or more compounds.

[0144] Among these, the intermediate layer is preferably a layer containing an organometallic compound containing a zirconium atom or a silicon atom.

[0145] The intermediate layer can be formed by any known method without particular limitation. For example, the intermediate layer can be formed by forming a coating film of an intermediate layer-forming coating liquid prepared by adding the above-mentioned components to a solvent, drying the coating film, and heating the coating film as needed.

[0146] As a coating method for forming the intermediate layer, a common method such as a dip coating method, an extrusion coating method, a wire bar coating method, a spray coating method, a blade coating method, a knife coating method, or a curtain coating method is used.

[0147] The thickness of the intermediate layer is preferably set to be within a range of, for example, 0.1 μm to 3 μm. The intermediate layer may also be used as a primer layer.

[0148] (Charge Generation Layer)

[0149] The charge generating layer is, for example, a layer comprising a charge generating material and a binder resin. Alternatively, the charge generating layer may be a vapor-deposited layer of the charge generating material. This vapor-deposited layer of the charge generating material is suitable for use with non-interference light sources such as LEDs (Light Emitting Diodes) or organic EL (Electro-Luminescence) image arrays.

[0150] Examples of the charge generating material include azo pigments such as disazo and trisazo; condensed-ring aromatic pigments such as dibromoanthanthrone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

[0151] Among these, metal phthalocyanine pigments or metal-free phthalocyanine pigments are preferably used as charge-generating materials to cope with near-infrared laser exposure. Specifically, hydroxygallium phthalocyanine disclosed in Japanese Patent Application Laid-Open Nos. 5-263007 and 5-279591, chlorogallium phthalocyanine disclosed in Japanese Patent Application Laid-Open No. 5-98181, dichlorotin phthalocyanine disclosed in Japanese Patent Application Laid-Open Nos. 5-140472 and 5-140473, and titanyl phthalocyanine disclosed in Japanese Patent Application Laid-Open No. 4-189873 are more preferable.

[0152] On the other hand, in order to cope with laser exposure in the near-ultraviolet region, preferred charge-generating materials include condensed-ring aromatic pigments such as dibromoanthanthrone; thioindigo pigments; tetraazaporphyrin compounds; zinc oxide; trigonal selenium; and disazo pigments disclosed in Japanese Patent Application Publication No. 2004-78147 and Japanese Patent Application Publication No. 2005-181992.

[0153] The above-mentioned charge-generating materials can also be used when using non-interference light sources such as LEDs and organic EL image arrays with a central emission wavelength of 450nm to 780nm. However, from the perspective of resolution, when using a photosensitive layer with a film thickness of 20μm or less, the electric field intensity in the photosensitive layer increases, which can easily lead to a decrease in charge due to charge injection from the substrate, i.e., image defects known as so-called black spots. This problem becomes more pronounced when using charge-generating materials such as trigonal selenium and phthalocyanine pigments, which are prone to generating dark current in p-type semiconductors.

[0154] In contrast, when n-type semiconductors such as fused aromatic pigments, perylene pigments, and azo pigments are used as charge-generating materials, dark current is less likely to occur, and image defects known as black spots can be suppressed even when formed into thin films. Examples of n-type charge-generating materials include, but are not limited to, compounds (CG-1) to (CG-27) described in paragraphs

[0288] to

[0291] of JP-A-2012-155282.

[0155] The n-type is determined by the polarity of the flowing photocurrent using the commonly used time-of-flight method, and the type in which electrons flow more easily as carriers than holes is determined as the n-type.

[0156] The binder resin used in the charge generating layer can be selected from a wide range of insulating resins. Alternatively, the binder resin can be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane.

[0157] Examples of the binder resin include polyvinyl butyral resin, polyarylate resin (a polycondensate of bisphenols and aromatic divalent carboxylic acids), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin, polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, and polyvinyl pyrrolidone resin. Here, "insulating property" means a volume resistivity of 10 13 Ωcm or more.

[0158] These adhesive resins may be used alone or in combination of two or more.

[0159] The mixing ratio of the charge generating material to the binder resin is preferably within a range of 10:1 to 1:10 in terms of mass ratio.

[0160] The charge generating layer may further contain other known additives.

[0161] The charge generating layer can be formed using any known methods, without particular limitation. For example, a coating film of a charge generating layer-forming coating solution prepared by adding the aforementioned components to a solvent can be formed, followed by drying the coating film and, if necessary, heating to form the charge generating layer. The charge generating layer can also be formed by vapor deposition of the charge generating material. Vapor deposition of the charge generating layer is particularly suitable for using condensed-ring aromatic pigments or perylene pigments as the charge generating material.

[0162] Examples of the solvent used to prepare the charge generating 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-butyl acetate, dioxane, tetrahydrofuran, dichloromethane, chloroform, chlorobenzene, and toluene. These solvents may be used alone or in combination of two or more.

[0163] Methods for dispersing particles (e.g., charge generating material) in the charge generating layer coating solution include, for example, using a media disperser such as a ball mill, vibrating ball mill, attritor, sand mill, or horizontal sand mill; or a media-free disperser such as a stirrer, ultrasonic disperser, roller mill, or high-pressure homogenizer. Examples of high-pressure homogenizers include a collision method, which disperses the dispersion by causing liquid-liquid collision or liquid-wall collision under high pressure; and a penetration method, which disperses the dispersion by penetrating a fine flow path under high pressure.

[0164] During the dispersion, it is effective that the average particle size of the charge generating material in the charge generating layer-forming coating liquid is 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less.

[0165] Examples of methods for applying the charge generating layer-forming coating liquid onto the undercoat layer (or intermediate layer) include common methods such as blade coating, wire rod coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0166] The film thickness of the charge generating layer is set, for example, preferably within a range of 0.1 μm to 5.0 μm, and more preferably within a range of 0.2 μm to 2.0 μm.

[0167] (Charge Transport Layer)

[0168] The charge transport layer is, for example, a layer containing a charge transport material and a binder resin. The charge transport layer may also be a layer containing a polymer charge transport material.

[0169] When the charge transport layer is the outermost surface layer, the charge transport layer contains fluorine-containing resin particles in addition to the binder resin and the charge transport material.

[0170] It should be noted that when other layers (such as a surface protective layer) are provided on the charge transport layer and the charge transport layer is not the outermost layer, the charge transport layer only needs to contain a binding resin and a charge transport material, and may also contain other additives as needed. The binding resin, charge transport material, and other additives are the same as when the charge transport layer is the outermost layer.

[0171] - Adhesive resin -

[0172] The adhesive resin used in the charge transport layer can include polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-modified alkyd resin, phenol-formaldehyde resin, styrene-modified alkyd resin, poly-N-vinyl carbazole, polysilane, etc. Among these, as the adhesive resin, polycarbonate resin or polyarylate resin is preferred. These adhesive resins are used alone or in combination of two or more.

[0173] The mixing ratio of the charge transport material to the binder resin is preferably 10:1 to 1:5 in terms of mass ratio.

[0174] Here, regarding the content of the binder resin, for example, relative to the total solid content of the photosensitive layer (charge transport layer), it is preferably from 10% by mass to 90% by mass, more preferably from 30% by mass to 80% by mass, and further preferably from 40% by mass to 70% by mass.

[0175] - Charge transport materials -

[0176] Examples of charge transport materials include electron-transporting compounds such as p-benzoquinone, chloranil, bromoquinone, and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds; cyanovinyl compounds; and vinyl compounds. Other examples of charge transport materials include hole-transporting compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted vinyl 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 to these.

[0177] As the charge transport material, from the viewpoint of charge mobility, a triarylamine derivative represented by the following general formula (a-1) and a benzidine derivative represented by the following general formula (a-2) are preferred.

[0178]

[0179] In the general formula (a-1), Ar T1 、Ar T2 and Ar T3 Each independently represents a substituted or unsubstituted aryl group, -C6H4-C(R T4 )=C(R T5 )(R T6 ) or -C6H4-CH=CH-CH=C(R T7 )(R T8 ). R T4 、R T5 、R T6 、R T7 , and R T8 Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.

[0180] Examples of substituents for the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. Examples of substituents for the above groups include substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms.

[0181]

[0182] In the general formula (a-2), R T91 and R T92 Each independently represents 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. T101 、R T102 、R T111 and R T112 Each independently represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted by an alkyl group having 1 or more and 2 or less carbon atoms, 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 represents 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.

[0183] Examples of substituents for the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. Examples of substituents for the above groups include substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms.

[0184] Here, among the triarylamine derivatives represented by the general formula (a-1) and the benzidine derivatives represented by the general formula (a-2), the one having "-C6H4-CH=CH-CH=C(R T7 )(R T8 )" and triarylamine derivatives having "-CH=CH-CH=C(R T15 )(R T16 )" benzidine derivatives.

[0185] As polymeric charge transport materials, known materials having charge transport properties, such as poly-N-vinylcarbazole and polysilane, are used. Polyester-based polymeric charge transport materials disclosed in Japanese Patent Application Laid-Open Nos. 8-176293 and 8-208820 are particularly preferred. It should be noted that polymeric charge transport materials can be used alone or in combination with a binder resin.

[0186] The concentration of the charge transport material measured on the surface of the charge transport layer is preferably 0.4 times to 0.6 times the concentration of the charge transport material measured at the center of the thickness of the charge transport layer, more preferably 0.45 times to 0.56 times, and further preferably 0.45 times to 0.54 times.

[0187] By making the ratio of the concentration of the charge transport material measured on the surface of the charge transport layer to the concentration of the charge transport material measured at the center of the thickness of the above-mentioned charge transport layer within the above-mentioned range, more charge transport material is contained in the center of the thickness of the charge transport layer compared to the surface of the charge transport layer.

[0188] The charge transport material includes a hole transport material, which has a high positive polarity. Therefore, if the charge transport material, including the hole transport material, is contained in a larger amount in the center of the charge transport layer, the photoreceptor surface can be further prevented from triboelectrically charging to a positive polarity due to friction. Consequently, even when the photoreceptor is charged during image formation, streaky variations in the surface potential of the photoreceptor are less likely to occur. This further reduces the occurrence of streaky image defects and residual potential caused by friction between the photoreceptor and its contact members due to vibration.

[0189] The method for determining the concentration ratio of the charge transport material in the above-mentioned charge transport layer is described. The charge transport layer is cut obliquely in the thickness direction, and the portion corresponding to the surface of the charge transport layer of the cross section and the portion corresponding to the center of the thickness of the charge transport layer are analyzed by microscopic infrared spectroscopy. The peak (1583.5cm) of the C=C stretching vibration origin of the charge transport material is calculated from the measurement results at the surface of the charge transport layer and the center of the thickness of the charge transport layer. -1 ) area ÷ the peak derived from C=O of the adhesive resin (1770 cm -1 ) area". The above value obtained from the measurement result of the surface of the charge transport layer is divided by the above value obtained from the measurement result at the center of the thickness of the charge transport layer to calculate.

[0190] As a method for making the ratio of the concentration of the charge transport material measured on the surface of the charge transport layer to the concentration of the charge transport material measured at the center of the thickness of the above-mentioned charge transport layer within the above-mentioned range, there can be cited a method of forming a charge transport layer by quickly removing the solvent in the charge transport layer coating liquid after applying the charge transport layer coating liquid.

[0191] Methods for quickly removing the solvent from the charge transport layer coating liquid include: a method of heating the surface of the coating film formed by the charge transport layer coating liquid while blowing air; a method of reducing the thickness of the conductive substrate in order to facilitate heat transfer to the coating film formed by the charge transport layer coating liquid; etc.

[0192] -Fluorine-containing resin particles-

[0193] Examples of the fluorine-containing resin particles include particles of a homopolymer of a fluoroolefin and particles of a copolymer of two or more fluoroolefins, that is, a copolymer of one or more fluoroolefins and a non-fluorine-containing monomer (ie, a monomer having no fluorine atoms).

[0194] Examples of the fluoroolefin include perhaloolefins such as tetrafluoroethylene (TFE), perfluorovinyl ether, hexafluoropropylene (HFP), and chlorotrifluoroethylene (CTFE), and non-perfluoroolefins such as vinylidene fluoride (VdF), trifluoroethylene, and vinyl fluoride. Among these, VdF, TFE, CTFE, and HFP are preferred.

[0195] On the other hand, examples of non-fluorine-containing monomers include hydrocarbon olefins such as ethylene, propylene, and butene; alkyl vinyl ethers such as cyclohexyl vinyl ether (CHVE), ethyl vinyl ether (EVE), butyl vinyl ether, and methyl vinyl ether; alkenyl vinyl ethers such as polyoxyethylene allyl ether (POEAE) and ethyl allyl ether; organosilicon compounds having a reactive α,β-unsaturated group such as vinyltrimethoxysilane (VSi), vinyltriethoxysilane, and vinyltri(methoxyethoxy)silane; acrylates such as methyl acrylate and ethyl acrylate; methacrylates such as methyl methacrylate and ethyl methacrylate; and vinyl esters such as vinyl acetate, vinyl benzoate, and "VeoVA" (trade name, a vinyl ester manufactured by Shell). Among these, alkyl vinyl ethers, allyl vinyl ethers, vinyl esters, and organosilicon compounds having a reactive α,β-unsaturated group are preferred.

[0196] Among these, as fluorine-containing resin particles, particles with a high fluorination rate are preferred, and particles of polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE) and the like are more preferred, and particles of PTFE, FEP, and PFA are particularly preferred.

[0197] In the fluorine-containing resin particles, every 10 6 The number of carboxyl groups per carbon atom is preferably 0 or more and 30 or less, more preferably 0 or more and 20 or less.

[0198] Here, the carboxyl group of the fluorine-containing resin particles is, for example, a carboxyl group derived from a terminal carboxylic acid contained in the fluorine-containing resin particles.

[0199] Examples of methods for reducing the carboxyl group content of fluororesin particles include: 1) not irradiating the particles during production; and 2) irradiating the particles in the absence of oxygen or at a reduced oxygen concentration.

[0200] The carboxyl group content of the fluorine-containing resin particles is measured as follows according to the description in Japanese Patent Application Laid-Open No. 4-20507.

[0201] Fluorine-containing resin particles were preformed using a press to produce a film of approximately 0.1 mm thickness. The produced film was subjected to infrared absorption spectroscopy. Fluorine-containing resin particles with completely fluorinated carboxylic acid terminals produced by contacting fluorine gas with the fluorine-containing resin particles were also subjected to infrared absorption spectroscopy. The number of terminal carboxyl groups (per 10 6 number of carbon atoms) = (l×K) / t

[0202] l: absorbance

[0203] K: Correction coefficient

[0204] t: film thickness (mm)

[0205] The absorption wave number of carboxyl group is 3560 cm -1 , the correction factor is 440.

[0206] Examples of the fluororesin particles include particles irradiated with radiation (also referred to herein as "radiation-irradiated fluororesin particles") and particles obtained by polymerization (also referred to herein as "polymerized fluororesin particles").

[0207] Radiation-irradiated fluororesin particles (fluororesin particles obtained by irradiation) refer to fluororesin particles obtained by simultaneously subjecting the polymerized fluororesin to radiation polymerization and granulation, or fluororesin particles obtained by decomposing the polymerized fluororesin by radiation irradiation, thereby reducing the molecular weight and forming fine particles.

[0208] The radiation-irradiated fluorine-containing resin particles generate a large amount of carboxylic acid by irradiation with radiation in the air, and therefore also contain a large amount of carboxyl groups.

[0209] On the other hand, polymerized fluorine-containing resin particles (fluorine-containing resin particles obtained by a polymerization method) refer to fluorine-containing resin particles that are granulated while being polymerized by a suspension polymerization method, an emulsion polymerization method, or the like, and are not irradiated with radiation.

[0210] The fluorine-containing resin particles may be polymerized fluorine-containing resin particles. As described above, the polymerized fluorine-containing resin particles are granulated simultaneously by suspension polymerization, emulsion polymerization, or the like, and are not irradiated with radiation.

[0211] Here, the production of fluororesin particles by suspension polymerization is a method in which monomers for forming fluororesin are suspended in a dispersion medium together with additives such as a polymerization initiator and a catalyst, and the polymer is granulated while polymerizing the monomers.

[0212] The production of fluororesin particles by emulsion polymerization is, for example, a method in which monomers for forming fluororesin are emulsified together with additives such as a polymerization initiator and a catalyst in a dispersion medium using a surfactant (i.e., an emulsifier), and the polymer is granulated while the monomers are polymerized.

[0213] In particular, the fluorine-containing resin particles may be particles obtained without irradiation during the production process.

[0214] Among these, the fluororesin particles may also be radiation-irradiated fluororesin particles obtained by irradiating with radiation in the absence of oxygen or under conditions where the oxygen concentration is reduced.

[0215] The average particle size of the fluorine-containing resin particles is not particularly limited, but is preferably from 0.2 μm to 4.5 μm, and more preferably from 0.2 μm to 4 μm.

[0216] The average particle size of the fluorine-containing resin particles is a value measured by the following method.

[0217] The maximum diameter of the fluororesin particles (secondary particles formed by aggregation of primary particles) is measured using a scanning electron microscope (SEM) at a magnification of, for example, 5000x or greater. This measurement is performed on 50 particles, and the average value obtained is defined as the average particle size of the fluororesin particles. A JSM-6700F manufactured by JEOL Ltd. is used as the SEM, and secondary electron images are observed at an accelerating voltage of 5 kV.

[0218] From the viewpoint of dispersion stability, the specific surface area (BET specific surface area) of the fluorine-containing resin particles is preferably 5 m 2 / g above 15m 2 / g or less, more preferably 7m 2 / g above 13m 2 / g or less.

[0219] The specific surface area is a value measured by a nitrogen replacement method using a BET-type specific surface area measuring instrument (Flowsoap II 2300 manufactured by Shimadzu Corporation).

[0220] From the viewpoint of dispersion stability, the apparent density of the fluorine-containing resin particles is preferably from 0.2 g / ml to 0.5 g / ml, more preferably from 0.3 g / ml to 0.45 g / ml.

[0221] In addition, the apparent density is a value measured according to JIS K6891 (1995).

[0222] The melting temperature of the fluorine-containing resin particles is preferably 300°C or higher and 340°C or lower, more preferably 325°C or higher and 335°C or lower.

[0223] In addition, the melting temperature is the melting point measured according to JIS K6891 (1995).

[0224] When the charge transport layer is the outermost surface layer, from the perspective of suppressing the occurrence of streak-like image defects and residual potential caused by friction between the photoreceptor and its contact members due to vibration, the area occupied by the fluorine-containing resin particles measured on its surface is preferably not less than 0.33% and not more than 1.1%, more preferably not less than 0.36% and not more than 0.95%, and further preferably not less than 0.38% and not more than 0.90%.

[0225] By ensuring that the surface area occupied by the fluorine-containing resin particles measured on the charge transport layer is within the above-mentioned range, the surface of the charge transport layer is provided with a large number of fluorine-containing resin particles having a high negative polarity. This makes it easier to eliminate positive charges generated by friction even when vibration during transport causes friction between the photoreceptor and a member in contact with the photoreceptor, further suppressing triboelectric charging of the rubbed portion of the photoreceptor toward the positive electrode. Consequently, even when the photoreceptor is charged during image formation, streaky variations in the surface potential of the photoreceptor are less likely to occur, further suppressing the occurrence of streaky image defects and residual potential caused by friction between the photoreceptor and its contact members caused by vibration.

[0226] The method for measuring the area occupied by fluororesin particles is described below. The surface of the charge transport layer is observed over a 120 μm x 90 μm area using a scanning electron microscope (SEM). The total area of ​​the fluororesin particles exposed on the charge transport layer is calculated and then divided by the observed area (i.e., 120 μm x 90 μm). This is used to calculate the area occupied by the fluororesin particles.

[0227] The content of the fluorine-containing resin particles is preferably 1% by mass to 20% by mass, more preferably 5% by mass to 15% by mass, and even more preferably 7% by mass to 10% by mass, relative to the charge transport layer.

[0228] -Fluorine atomic concentration-

[0229] In the photoreceptor of this embodiment, when the charge transport layer is the outermost layer, the fluorine atom concentration measured on the surface is 1.5 to 5.0 times the fluorine atom concentration measured at a depth of 1 μm from the surface of the charge transport layer.

[0230] By setting the fluorine atom concentration of the charge transport layer to the above configuration, a large amount of fluorine-containing resin particles are contained on the surface of the charge transport layer, which can suppress the occurrence of streak-like image defects and residual potential caused by friction between the photoreceptor and its contact member due to vibration.

[0231] From the perspective of suppressing the generation of streak-like image defects and residual potential caused by friction between the photoreceptor and its contact members due to vibration, the fluorine atom concentration measured on the surface of the charge transport layer is preferably 2.0 times or more and 5.0 times or less of the fluorine atom concentration measured at a depth of 1 μm from the surface of the above-mentioned charge transport layer, and more preferably 2.5 times or more and 4.0 times or less.

[0232] The fluorine atom concentration was measured using X-ray photoelectron spectroscopy (XPS). First, the surface of the charge transport layer was analyzed using XPS to calculate the concentration of fluorine atoms in all elements. Next, sputtering was performed from the surface of the charge transport layer to a depth of 1 μm, exposing a portion of the charge transport layer at a depth of 1 μm from the surface. The surface was then analyzed using XPS to calculate the concentration of fluorine atoms in all elements.

[0233] The XPS measurement conditions were a tube voltage of 40 kV and a tube current of 90 mA.

[0234] -Additives, Formation Methods, and Film Thickness-

[0235] The charge transport layer may contain other known additives.

[0236] As the additive, for example, a dispersant is preferred.

[0237] The dispersant is preferably a dispersant containing a fluorine element, and specifically, a fluorine-containing graft polymer can be mentioned.

[0238] Examples of the fluorine-containing graft polymer include polymers obtained by homopolymerizing or copolymerizing a polymerizable compound having a fluorinated alkyl group (hereinafter also referred to as "fluorinated alkyl group-containing polymer").

[0239] Specific examples of the fluorinated graft polymer include homopolymers of (meth)acrylates having a fluoroalkyl group, random or block copolymers of (meth)acrylates having a fluoroalkyl group and a monomer having no fluorine atom, etc. (Meth)acrylates refer to both acrylates and methacrylates.

[0240] Examples of the (meth)acrylate having a fluoroalkyl group include 2,2,2-trifluoroethyl (meth)acrylate and 2,2,3,3,3-pentafluoropropyl (meth)acrylate.

[0241] Examples of the monomer not containing a fluorine atom include (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 2-ethoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, benzyl (meth)acrylate, ethyl carbitol (meth)acrylate, phenoxyethyl (meth)acrylate, 2-hydroxy (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, hydroxyethyl o-phenylphenol (meth)acrylate, and o-phenylphenol glycidyl ether (meth)acrylate.

[0242] Specific examples of the fluorine-containing graft polymer include block or branched polymers disclosed in US Pat. No. 5,637,142 and Japanese Patent No. 4,251,662. Specific examples of the fluorine-containing graft polymer include fluorine-based surfactants.

[0243] The content of the fluorinated graft polymer relative to the content of the fluorinated resin particles is preferably 1.0 mass % to 15.0 mass %, more preferably 2.0 mass % to 10.0 mass %, further preferably 3.0 mass % to 8.0 mass %.

[0244] When the charge transport layer is the outermost layer, it is preferred that the type and content of the fluorinated graft polymer are as described above, because this facilitates the inclusion of a large amount of fluorinated resin particles on the surface of the charge transport layer and the fluorine atom concentration of the charge transport layer is easily within the above-described configuration.

[0245] The charge transport layer can be formed by any known method without particular limitation. For example, a charge transport layer can be formed by forming a coating film of a charge transport layer-forming coating liquid prepared by adding the above-mentioned components to a solvent, drying the coating film, and heating the coating film as needed.

[0246] Examples of solvents used to prepare the charge transport layer coating solution include common organic solvents such as aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene; ketones such as acetone and 2-butanone; halogenated aliphatic hydrocarbons such as dichloromethane, chloroform, and vinyl chloride; and cyclic or linear ethers such as tetrahydrofuran and diethyl ether. These solvents may be used alone or in combination of two or more.

[0247] Examples of the coating method for coating the charge transport layer-forming coating liquid on the charge generating layer include common methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0248] The film thickness of the charge transport layer is set, for example, preferably within a range of 5 μm to 50 μm, more preferably within a range of 10 μm to 30 μm.

[0249] (Surface protection layer)

[0250] The surface protective layer is provided on the photosensitive layer as needed. The surface protective layer is provided for the purpose of, for example, preventing chemical changes in the photosensitive layer during charging or further improving the mechanical strength of the photosensitive layer.

[0251] Therefore, a layer composed of a cured film (crosslinked film) can be applied as the surface protective layer. Examples of these layers include the layers shown in the following 1) or 2).

[0252] 1) A layer consisting of a cured film of a composition comprising a reactive group-containing charge transport material having a reactive group and a charge transport skeleton in the same molecule (i.e., a layer comprising a polymer or a crosslinked product of the reactive group-containing charge transport material)

[0253] 2) A layer composed of a cured film of a composition comprising a non-reactive charge transport material and a reactive group-containing non-charge transport material having no charge transport skeleton but having a reactive group (i.e., a layer comprising a non-reactive charge transport material and a polymer or crosslinked product of the reactive group-containing non-charge transport material)

[0254] Examples of the reactive group of the reactive group-containing charge transport material include chain polymerizable groups, epoxy groups, -OH, -OR [wherein R represents an alkyl group], -NH2, -SH, -COOH, -SiR Q1 3-Qn (ORQ2 ) Qn [Among them, R Q1 represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, R Q2 represents a hydrogen atom, an alkyl group, a trialkylsilyl group, and Qn represents an integer of 1 to 3] and other known reactive groups.

[0255] The chain polymerizable group is not particularly limited as long as it is a functional group capable of free radical polymerization, and is, for example, a functional group having at least a carbon double bond. Specifically, examples include groups containing at least one selected from a vinyl group, a vinyl ether group, a vinyl sulfide group, a styryl (vinylphenyl) group, an acryloyl group, a methacryloyl group, and derivatives thereof. Among them, due to its excellent reactivity, the chain polymerizable group is preferably a group containing at least one selected from a vinyl group, a styryl (vinylphenyl) group, an acryloyl group, a methacryloyl group, and derivatives thereof.

[0256] The charge transport skeleton of the reactive group-containing charge transport material is not particularly limited as long as it has a known structure in electrophotographic photoreceptors. Examples thereof include structures in which the skeleton is derived from a nitrogen-containing hole transport compound such as a triarylamine compound, a benzidine compound, or a hydrazone compound, and is conjugated with a nitrogen atom. Among these, a triarylamine skeleton is preferred.

[0257] The reactive group-containing charge transport material, non-reactive charge transport material, and reactive group-containing non-charge transport material having a reactive group and a charge transport skeleton may be selected from known materials.

[0258] The surface protection layer may contain other known additives.

[0259] The formation of the surface protective layer is not particularly limited and can be carried out by a known formation method. For example, it can be carried out as follows: a coating film of a surface protective layer-forming coating liquid is formed by adding the above-mentioned components to a solvent, the coating film is dried, and a curing treatment such as heating is performed as needed to form the surface protective layer.

[0260] Examples of solvents used to prepare the coating solution for forming the surface protective layer include aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; ether solvents such as tetrahydrofuran and dioxane; cellosolve solvents such as ethylene glycol monomethyl ether; and alcohol solvents such as isopropyl alcohol and butanol. These solvents may be used alone or in combination of two or more.

[0261] In addition, the coating liquid for forming a surface protective layer may be a solvent-free coating liquid.

[0262] Examples of methods for applying the coating liquid for forming a surface protective layer onto a photosensitive layer (e.g., a charge transport layer) include common methods such as dip coating, extrusion coating, wire rod coating, spray coating, blade coating, knife coating, and curtain coating.

[0263] The thickness of the surface protective layer is preferably set within a range of, for example, 1 μm to 20 μm, more preferably 2 μm to 10 μm. It should be noted that when the surface protective layer is the outermost layer, it contains fluorine-containing resin particles. Since the fluorine-containing resin particles contained in the surface protective layer are the same as those described above, a detailed description of the fluorine-containing resin particles will be omitted.

[0264] (Single-layer photosensitive layer)

[0265] The single-layer photosensitive layer (charge generation / charge transport layer) is, for example, a layer containing a charge generation material and a charge transport material, and, if necessary, a binder resin and other known additives. It should be noted that these materials are the same as those described for the charge generation layer and charge transport layer. When the single-layer photosensitive layer is the outermost layer, the single-layer photosensitive layer contains fluorine-containing resin particles.

[0266] Furthermore, the content of the charge generating material in the single-layer photosensitive layer may be from 0.1% to 10% by mass, preferably from 0.8% to 5% by mass, relative to the total solids. Furthermore, the content of the charge transport material in the single-layer photosensitive layer may be from 5% to 50% by mass, relative to the total solids.

[0267] The method for forming the single-layer photosensitive layer is the same as the method for forming the charge generating layer and the charge transporting layer.

[0268] The film thickness of the single-layer photosensitive layer can be, for example, 5 μm to 50 μm, and preferably 10 μm to 40 μm.

[0269] <Image Forming Apparatus (and Process Cartridge)>

[0270] The image forming apparatus of this embodiment includes: an electrophotographic photoreceptor; a charging mechanism for charging the surface of the electrophotographic photoreceptor; an electrostatic latent image forming mechanism for forming an electrostatic latent image on the surface of the charged electrophotographic photoreceptor; a developing mechanism for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor using a developer containing toner to form a toner image; and a transfer mechanism for transferring the toner image to the surface of a recording medium. The photoreceptor of this embodiment described above is employed as the electrophotographic photoreceptor.

[0271] The image forming device of this embodiment can apply the following well-known image forming devices: a device equipped with a fixing mechanism for fixing the toner image transferred to the surface of a recording medium; a device of a direct transfer method for directly transferring the toner image formed on the surface of an electronic photographic photoreceptor to the recording medium; a device of an intermediate transfer method for transferring the toner image formed on the surface of an electronic photographic photoreceptor once to the surface of an intermediate transfer body, and then transferring the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium for a second time; a device equipped with a cleaning mechanism for cleaning the surface of an electronic photographic photoreceptor after the toner image is transferred but before charging; a device equipped with a static elimination mechanism for eliminating static by irradiating the surface of an electronic photographic photoreceptor with static elimination light after the toner image is transferred but before charging; a device equipped with an electronic photographic photoreceptor heating component for increasing the temperature of the electronic photographic photoreceptor and lowering the relative temperature; and the like.

[0272] In the case of an intermediate transfer type device, the transfer mechanism is, for example, configured as follows: an intermediate transfer body for transferring a toner image on a surface, a primary transfer mechanism for transferring a toner image formed on the surface of an electronic photographic photosensitive body to the surface of the intermediate transfer body for the first time, and a secondary transfer mechanism for secondary transferring the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium.

[0273] The image forming apparatus of the present embodiment may be any of a dry development system image forming apparatus and a wet development system (development system using a liquid developer) image forming apparatus.

[0274] It should be noted that, in the image forming apparatus of this embodiment, for example, the portion comprising the electrophotographic photoreceptor may be a cartridge structure (process cartridge) that is attachable to and detachable from the image forming apparatus. As a process cartridge, for example, a process cartridge comprising the photoreceptor of this embodiment is suitable for use. It should be noted that, in addition to the electrophotographic photoreceptor, the process cartridge may further comprise, for example, at least one member selected from the group consisting of a charging mechanism, an electrostatic latent image forming mechanism, a developing mechanism, and a transfer mechanism.

[0275] An example of the image forming apparatus according to the present embodiment is shown below, but the present invention is not limited thereto. It should be noted that the main parts shown in the drawings will be described, and descriptions of other parts will be omitted.

[0276] Figure 2 This is a schematic structural diagram showing an example of the image forming apparatus according to the present embodiment.

[0277] like Figure 2As shown, the image forming apparatus 100 of this embodiment includes: a process cartridge 300 including an electrophotographic photoreceptor 7; an exposure device 9 (an example of an electrostatic latent image forming mechanism); a transfer device 40 (a primary transfer device); and an intermediate transfer body 50. It should be noted that in the image forming apparatus 100, the exposure device 9 is positioned so as to expose the electrophotographic photoreceptor 7 through the opening of the process cartridge 300, and the transfer device 40 is positioned so as to face the electrophotographic photoreceptor 7 across the intermediate transfer body 50, with the intermediate transfer body 50 being positioned so as to partially contact the electrophotographic photoreceptor 7. Although not shown, the image forming apparatus 100 also includes a secondary transfer device that transfers the toner image transferred to the intermediate transfer body 50 to a recording medium (e.g., paper). It should be noted that the intermediate transfer body 50, the transfer device 40 (a primary transfer device), and the secondary transfer device (not shown) constitute an example of a transfer mechanism.

[0278] Figure 2 The process cartridge 300 in the embodiment integrally supports the electrophotographic photoreceptor 7, the charging device 8 (an example of a charging mechanism), the developing device 11 (an example of a developing mechanism), and the cleaning device 13 (an example of a cleaning mechanism) within a housing. The cleaning device 13 includes a cleaning blade (an example of a cleaning member) 131, which is arranged to contact the surface of the electrophotographic photoreceptor 7. It should be noted that the cleaning member may be a conductive or insulating fibrous member other than the cleaning blade 131, and may be used alone or in combination with the cleaning blade 131.

[0279] It should be noted that Figure 2 In the example shown, the image forming apparatus includes a fibrous member 132 (rolled) for supplying lubricant 14 to the surface of the electrophotographic photoreceptor 7 and a fibrous member 133 (flat brush) for assisting cleaning. However, these members are arranged as needed.

[0280] Next, each structure of the image forming apparatus according to this embodiment will be described.

[0281] -Charging device-

[0282] As the charging device 8, for example, a contact charger using a conductive or semiconductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube, etc. can be used. Alternatively, a non-contact roller charger, a scorotron charger using corona discharge, a corona charger, or other known chargers can be used.

[0283] -Exposure device-

[0284] As the exposure device 9, for example, there can be cited an optical system device that uses semiconductor laser light, LED light, liquid crystal light valve light, etc. to expose the surface of the electrophotographic photoreceptor 7 according to a predetermined image. The wavelength of the light source is set to be within the spectral sensitivity range of the electrophotographic photoreceptor. As the wavelength of the semiconductor laser, near-infrared light with an oscillation wavelength of around 780nm is the mainstream. However, it is not limited to this wavelength, and a laser with an oscillation wavelength of approximately 600nm or a laser with an oscillation wavelength of more than 400nm and less than 450nm as a blue laser can also be used. In addition, in order to form a color image, a surface-emitting laser source that can output multiple beams is also effective.

[0285] -Developing device-

[0286] Examples of the developing device 11 include conventional developing devices that perform development with or without contact with a developer. The developing device 11 is not particularly limited as long as it has the functions described above, and can be selected based on the intended purpose. Examples include known developing devices that utilize a brush, roller, or the like to deposit a single-component developer or a two-component developer onto the electrophotographic photoreceptor 7. Of these, a developing roller having a developer retained on its surface is preferably used.

[0287] The developer used in the developing device 11 may be a single-component developer consisting of only a toner or a two-component developer consisting of a toner and a carrier. Furthermore, the developer may be magnetic or non-magnetic. These developers may be known developers.

[0288] -Cleaning device-

[0289] The cleaning device 13 is a cleaning blade type device including a cleaning blade 131 .

[0290] The cleaning blade 131 preferably contacts the electrophotographic photoreceptor 7 with a contact pressure of 1.0 g / mm to 4.0 g / mm.

[0291] Here, the contact pressure with respect to the electrophotographic photoreceptor 7 refers to a load per unit length of the contact portion of the cleaning blade 131 applied to the electrophotographic photoreceptor 7 , that is, a linear pressure.

[0292] By making the contact pressure of the cleaning scraper 131 on the electrophotographic photoreceptor 7 within the above-mentioned range, the friction generated by the friction between the electrophotographic photoreceptor 7 and the cleaning scraper 131 due to vibration is reduced, the surface of the electrophotographic photoreceptor 7 is difficult to be frictionally charged, and the generation of striped image defects and residual potential are suppressed, so it is preferred.

[0293] From the perspective of suppressing the generation of streaked image defects and residual potential caused by friction between the photosensitive body and its contact components due to vibration, the contact pressure of the cleaning scraper 131 on the electronic photographic photosensitive body 7 is more preferably not less than 1.5 g / mm and not more than 3.5 g / mm, and further preferably not less than 2.0 g / mm and not more than 3.0 g / mm.

[0294] It should be noted that, in addition to the cleaning blade method, a brush cleaning method and a simultaneous development and cleaning method may also be used.

[0295] -Transfer device-

[0296] Examples of the transfer device 40 include known transfer chargers such as a contact transfer charger using a belt, a roller, a film, or a rubber blade, a scorotron transfer charger using corona discharge, and a corona transfer charger.

[0297] -Intermediate transfer body-

[0298] A belt-shaped transfer member (intermediate transfer belt) made of polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber, etc. imparted with semiconductivity is used as the intermediate transfer member 50. In addition, a drum-shaped transfer member can be used as the intermediate transfer member in addition to a belt-shaped transfer member.

[0299] Figure 3 This is a schematic structural diagram showing another example of the image forming apparatus according to the present embodiment.

[0300] Figure 3 The illustrated image forming apparatus 120 is a tandem-type multi-color image forming apparatus equipped with four process cartridges 300. In image forming apparatus 120, the four process cartridges 300 are arranged in parallel on an intermediate transfer member 50, with one electrophotographic photoreceptor used for each color. It should be noted that, except for the tandem design, image forming apparatus 120 has the same configuration as image forming apparatus 100.

[0301] Second Implementation Method

[0302] -Electrophotographic photoreceptor-

[0303] The electrophotographic photoreceptor of this embodiment includes a conductive substrate and a photosensitive layer provided on the conductive substrate, wherein the outermost surface layer contains fluorine-containing resin particles.

[0304] In the electronic photographic photosensitive body of this embodiment, the ratio (N2 / N1) of the number density (N1) of the agglomerates of the above-mentioned fluorine-containing resin particles in the first region of the above-mentioned outermost surface layer from the surface to 1 / 2 of the layer thickness to the number density (N2) of the agglomerates of the above-mentioned fluorine-containing resin particles in the second region of the above-mentioned outermost surface layer from 1 / 2 of the above-mentioned film thickness to the bottom surface of the above-mentioned outermost surface layer is less than 0.95.

[0305] In the electronic photographic photosensitive body of this embodiment, the ratio (S2 / S1) of the area ratio (S1) of the above-mentioned fluorine-containing resin particles in the first region of the above-mentioned outermost surface layer from the surface to 1 / 2 of the layer thickness to the area ratio (S2) of the above-mentioned fluorine-containing resin particles in the second region of the above-mentioned outermost surface layer from 1 / 2 of the above-mentioned film thickness to the bottom surface of the above-mentioned outermost surface layer is within the range of 1±0.1.

[0306] In an electrophotographic photoreceptor having an outermost surface layer comprising fluororesin particles, the fluororesin particles have the effect of improving the wear resistance when the cleaning blade contacts the outermost surface layer. However, the fluororesin particles have a high tendency to cohesion, so for the outermost surface layer comprising the fluororesin particles, a technique of dispersing the fluororesin particles in a nearly uniform state over the entire layer while suppressing the cohesion of the fluororesin particles is adopted. However, if the fluororesin particles are dispersed in a nearly uniform state, the fluororesin particles have a tendency to physically hinder the charge transportability of the outermost surface layer. As a result, there is a tendency to reduce the charge transportability in the outermost surface layer when the electrophotographic photoreceptor is exposed, that is, to reduce the sensitivity.

[0307] On the other hand, the electrophotographic photoreceptor of this embodiment has excellent sensitivity and wear resistance due to the above-mentioned configuration. The reason for this is not necessarily clear, but it can be presumed as follows.

[0308] In the electrophotographic photoreceptor of the present embodiment, the ratio (N2 / N1) of the number density (N1) of the agglomerates of the above-mentioned fluorine-containing resin particles in the first region from the surface to 1 / 2 of the layer thickness of the outermost surface layer to the number density (N2) of the agglomerates of the above-mentioned fluorine-containing resin particles in the second region from 1 / 2 of the above-mentioned film thickness to the bottom surface of the above-mentioned outermost surface layer is less than 0.95. That is, in the first region (the surface side in contact with the cleaning blade) and the second region (conductive substrate side), the number of agglomerates of the fluorine-containing resin particles in the first region is less, and the fluorine-containing resin particles are dispersed in a state close to uniform. Therefore, it is believed that the surface side in contact with the cleaning blade is brought into play with wear resistance. In addition, by increasing the number of agglomerates in the second region, the region in which there is no fluorine-containing resin particles increases, and the physical obstruction of the charge transportability of the outermost surface layer caused by the fluorine-containing resin particles is suppressed. As a result, it is believed that the reduction in sensitivity can be suppressed.

[0309] Furthermore, in the electrophotographic photoreceptor of this embodiment, the ratio (S2 / S1) of the area ratio of the fluororesin particles in the first region (S1) to the area ratio of the fluororesin particles in the second region (S2) is 1±0.1 or less. This means that the amount of fluororesin particles present in both the first region (the surface in contact with the cleaning blade) and the second region (the conductive substrate side) is consistent regardless of the degree of aggregation. Consequently, even when the electrophotographic photoreceptor of this embodiment is driven for extended periods of time, it is believed to exhibit excellent wear resistance.

[0310] Layer Structure of Electrophotographic Photoreceptor

[0311] Hereinafter, the layer structure of the electrophotographic photoreceptor will be described with reference to the drawings.

[0312] Figure 4 107A is a schematic cross-sectional view showing an example of the layer structure of the electrophotographic photoreceptor of this embodiment. The electrophotographic photoreceptor 107A has the following structure: a primer layer 101 is provided on a conductive substrate 104, and a charge generating layer 102, a charge transport layer 103 and a surface protective layer 106 are formed thereon in this order. The electrophotographic photoreceptor 107A has a photosensitive layer 105 whose functions are separated into the charge generating layer 102 and the charge transport layer 103. Figure 4 The electrophotographic photoreceptor 107A shown having the laminated photosensitive layer 105 is referred to as a “laminated photoreceptor”.

[0313] Figure 5 This is a schematic cross-sectional view showing another example of the layer structure of the electrophotographic photoreceptor of this embodiment. The electrophotographic photoreceptor 107B has a structure in which an undercoat layer 101 is provided on a conductive substrate 104, and a photosensitive layer 105 and a surface protective layer 106 are formed thereon in this order. The electrophotographic photoreceptor 107B has a single-layer photosensitive layer in which the charge generating material and the charge transporting material are contained in the same photosensitive layer 105 to integrate their functions. Figure 5 The electrophotographic photoreceptor 107B shown having the single-layer photosensitive layer 105 is also referred to as a “single-layer photoreceptor”.

[0314] The electrophotographic photoreceptor in this embodiment may or may not be provided with the undercoat layer 101 and the surface protective layer 106 .

[0315] The following describes each layer of the electrophotographic photoreceptor of this embodiment in detail. It should be noted that the conductive substrate 104, undercoat layer 101, intermediate layer, charge generation layer 102, and single-layer photosensitive layer of the second embodiment have the same configuration as the first embodiment, and therefore description thereof will be omitted. Note that reference numerals will be omitted for clarity in the description.

[0316] The Outermost Layer

[0317] The electrophotographic photoreceptor of the present embodiment contains fluorine-containing resin particles in the outermost surface layer.

[0318] In the electronic photographic photosensitive body of this embodiment, the ratio (N2 / N1) of the number density (N1) of the agglomerates of the above-mentioned fluorine-containing resin particles in the first region of the outermost surface layer from the surface to 1 / 2 of the layer thickness to the number density (N2) of the agglomerates of the above-mentioned fluorine-containing resin particles in the second region of the outermost surface layer from 1 / 2 of the above-mentioned film thickness to the bottom surface of the above-mentioned outermost surface layer is less than 0.95.

[0319] In the electronic photographic photosensitive body of this embodiment, the ratio (S2 / S1) of the area ratio (S1) of the above-mentioned fluorine-containing resin particles in the first region of the outermost surface layer from the surface to 1 / 2 of the layer thickness to the area ratio (S2) of the above-mentioned fluorine-containing resin particles in the second region of the outermost surface layer from 1 / 2 of the above-mentioned film thickness to the bottom surface of the above-mentioned outermost surface layer is within the range of 1±0.1.

[0320] When the electrophotographic photoreceptor has a surface protective layer, the outermost surface layer refers to the surface protective layer.

[0321] In the case of a laminated electrophotographic photoreceptor having no surface protective layer, the outermost surface layer refers to a charge transport layer.

[0322] In the case of a single-layer type electrophotographic photoreceptor having no surface protective layer, the outermost surface layer refers to the photosensitive layer.

[0323] [State of the outermost surface layer]

[0324] "Agglomerates of fluorine-containing resin particles" refers to a group of primary particles of fluorine-containing resin particles existing within a distance of 1 μm between particles. However, if there are no particles within 1 μm around a primary particle, one primary particle is counted as one agglomerate.

[0325] The primary particles constituting the aggregates only need to be present within a region of 1 μm from each other, and the particles may be in contact with each other, adjacent to each other without contact, or a combination of the two.

[0326] The inter-particle distance refers to the shortest straight-line distance connecting any two points on the outer edges (surfaces) of adjacent primary particles.

[0327] For example, when aggregates are present on the boundary between the first region and the second region, or on the boundary between the second region and the third region, the aggregates are counted as being present in the region where the area of ​​the aggregates is greater.

[0328] (Ratio of the number density of the fluorine-containing resin particle aggregates in each region) Ratio (N2 / N1)

[0329] In the electronic photographic photosensitive body of this embodiment, the ratio (N2 / N1) of the number density (N1) of the agglomerates of the above-mentioned fluorine-containing resin particles in the first region of the outermost surface layer from the surface to 1 / 2 of the layer thickness to the number density (N2) of the agglomerates of the above-mentioned fluorine-containing resin particles in the second region of the outermost surface layer from 1 / 2 of the above-mentioned film thickness to the bottom surface of the above-mentioned outermost surface layer is less than 0.95. From the perspective of making an electronic photographic photosensitive body with excellent sensitivity and wear resistance, it is preferably greater than 0.1 and less than 0.8, and more preferably greater than 0.2 and less than 0.7.

[0330] Ratio (N3 / N1)

[0331] In the electrophotographic photoreceptor of this embodiment, from the perspective of achieving both excellent sensitivity and wear resistance and suppressing the occurrence of color spots caused by the incorporation of needle-shaped foreign matter, the ratio (N3 / N1) of the number density (N1) of the fluororesin particle aggregates in the first region of the outermost layer, extending from the surface to 1 / 2 of the layer thickness, to the number density (N3) of the fluororesin particle aggregates in the third region extending from 9 / 10 of the layer thickness from the surface of the outermost layer to the bottom surface of the outermost layer is preferably 0.9 or less, more preferably 0.7 or less. The ratio (N3 / N1) is also preferably 0.2 or more and 0.8 or less, more preferably 0.3 or more and 0.7 or less.

[0332] In the past, when needle-shaped conductive foreign matter, such as carbon fibers, entered an electrophotographic photoreceptor, they would penetrate the outermost surface layer. This penetrated area would experience insulation breakdown due to the voltage from the charging component, easily generating leakage current. In this area where leakage current occurs, charging becomes poor, sometimes resulting in color spots when forming an image. This phenomenon is particularly pronounced in electrophotographic photoreceptors with an outermost surface layer (particularly a charge transport layer) containing fluorine-containing resin particles, where the interface between the fluorine-containing resin particles and the resin is weak, easily causing insulation breakdown.

[0333] On the other hand, in the electrophotographic photoreceptor of this embodiment, particularly by setting the ratio (N3 / N1) within the above range, the number density of fluorine-containing resin particle aggregates in the second region is further reduced. Therefore, even if conductive foreign matter penetrates, insulation breakdown is less likely to occur. As a result, the generation of color spots due to leakage current is believed to be suppressed.

[0334] Number density (N1, N2 and N3)

[0335] From the perspective of obtaining an electrophotographic photoreceptor having both excellent sensitivity and wear resistance, the number density (N1) of the aggregates of the fluorine-containing resin particles in the first region of the outermost layer from the surface to 1 / 2 of the layer thickness is preferably 5 particles / 100 μm. 2 More than 50 / 100μm 2 Less than 6 / 100 μm, more preferably 6 / 100 μm 2 More than 30 / 100μm 2 Less than, more preferably 8 / 100 μm 2 More than 20 / 100μm 2 the following.

[0336] There is no particular limitation on the method for adjusting the ratio (N2 / N1) and the ratio (N3 / N1) of the number density of agglomerates of fluororesin particles in each region, and examples thereof include: in the formation of the outermost surface layer, (1) a method for adjusting the number of treatments of the homogenizer when preparing a coating liquid containing fluororesin particles; (2) a method for adjusting the amount or type of fluororesin particles; (3) a method for adjusting the content of fluororesin particles in the outermost surface layer while using a plurality of coating liquids having different solid content concentrations of fluororesin particles to form a coating film with a concentration difference in stages; (4) a method for adjusting the drying temperature of the coating film in stages; (5) a method for increasing the relative speed between the coated material and the coating liquid during coating; etc.

[0337] There is no particular limitation on the method for adjusting the number density (N1 to N3) of the aggregates of the fluororesin particles in each region, and examples thereof include: in the formation of the outermost surface layer, (1) a method for adjusting the number of treatments of the homogenizer when preparing a coating liquid containing fluororesin particles; (2) a method for adjusting the amount or type of fluororesin particles; (3) a method for adjusting the content of fluororesin particles in the outermost surface layer while using a plurality of coating liquids having different solid content concentrations of fluororesin particles to form a coating film with a concentration difference in stages; (4) a method for adjusting the drying temperature of the coating film in stages; (5) a method for increasing the relative speed between the coated material and the coating liquid during coating; etc.

[0338] The number density (N1 to N3) of the fluorine-containing resin particle aggregates and the ratio (N2 / N1, N3 / N1) of the outermost layer can be confirmed as follows: (1) The outermost layer of the electrophotographic photoreceptor is cut in the thickness direction to obtain a test piece with the cross section as the observation surface.

[0339] (2) The observation surface of the test piece was observed using a scanning electron microscope (SEM) (manufactured by JEOL Ltd.: JSM-6700F). An image was captured and the number of fluororesin particle aggregates in the first region of the outermost surface layer, from the surface (i.e., layer thickness 0 μm) to 1 / 2 of the layer thickness, was calculated by image analysis. The number of aggregates was converted to the number per unit area and this value was defined as the number density (N1) of the fluororesin particles. Similarly, the number of aggregates of fluororesin particles in the second and third regions was calculated and the values ​​converted to the number per unit area were determined.

[0340] (3) The above (1) and (2) are performed on the cross section of the outermost surface layer at any three locations in the electrophotographic photoreceptor, and the arithmetic average thereof is taken as the number density (N1, N2 and N3) of the fluorine-containing resin particles in each region.

[0341] (4) Calculate the ratio (N2 / N1) and the ratio (N3 / N1) respectively.

[0342] (Ratio of the area ratio of the fluorine-containing resin particles in each region) Ratio (S2 / S1)

[0343] In the electronic photographic photosensitive body of this embodiment, the ratio (S2 / S1) of the area ratio (S1) of the above-mentioned fluorine-containing resin particles in the first region from the surface to 1 / 2 of the layer thickness of the outermost surface layer to the area ratio (S2) of the above-mentioned fluorine-containing resin particles in the second region from 1 / 2 of the above-mentioned film thickness to the bottom surface of the above-mentioned outermost surface layer is within the range of 1±0.1. From the perspective of making an electronic photographic photosensitive body with better wear resistance, it is preferably above 0.97 and below 1.07, and more preferably above 0.95 and below 1.05.

[0344] There is no particular limitation on the method for adjusting the ratio (S2 / S1) of the area ratio of the fluororesin particles in each region, and examples thereof include: in the formation of the outermost surface layer, (1) a method for adjusting the number of treatments of the homogenizer when preparing a coating liquid containing fluororesin particles; (2) a method for adjusting the amount or type of fluororesin particles; (3) a method for adjusting the content of fluororesin particles in the outermost surface layer while using a plurality of coating liquids having different solid content concentrations of fluororesin particles to form a coating film with a concentration difference in stages; (4) a method for adjusting the drying temperature of the coating film in stages; (5) a method for increasing the relative speed between the coated material and the coating liquid during coating; etc.

[0345] The area ratio (S2 / S1) of the aggregates of the fluorine-containing resin particles can be determined as follows: (1) The outermost surface layer of the electrophotographic photoreceptor is cut in the thickness direction to obtain a test piece with the cross section as the observation surface.

[0346] (2) The observation surface of the test piece was observed using a scanning electron microscope (SEM) (manufactured by Hitachi, Ltd.: S-4100), and an image was captured. The image was then input into an image analyzer (LUZEXIII, manufactured by NIRECO Co., Ltd.). Furthermore, the total area of ​​all fluororesin particle aggregates in the first region of the outermost surface layer, from the surface (i.e., layer thickness 0 μm) to 1 / 2 of the layer thickness, was determined by image analysis. The area ratio of the fluororesin particle aggregates relative to the area of ​​the first region was then determined. Similarly, the area ratio of the fluororesin particle aggregates in the second region was determined.

[0347] (3) The above (1) and (2) are performed on the cross section of the outermost surface layer at any three locations of the electrophotographic photoreceptor, and the arithmetic average thereof is used as the area ratio (S1 and S2) of the fluorine-containing resin particles in each of the first and second regions.

[0348] (4) Calculate the ratio (S2 / S1).

[0349] (Ratio of average diameters of agglomerates of fluorine-containing resin particles in each region) Ratio (D2 / D1)

[0350] In the electronic photographic photosensitive body of the present embodiment, from the perspective of making an electronic photographic photosensitive body with better sensitivity and wear resistance, and from the perspective of suppressing the generation of color spots caused by the mixing of needle-shaped foreign matter, the ratio (D2 / D1) of the average diameter (D1) of the agglomerates of the above-mentioned fluorine-containing resin particles in the first area from the surface to 1 / 2 of the layer thickness of the outermost surface layer to the average diameter (D2) of the agglomerates of the above-mentioned fluorine-containing resin particles in the second area from 1 / 2 of the above-mentioned film thickness to the bottom surface of the above-mentioned outermost surface layer is preferably greater than 2, more preferably greater than 3 and less than 30, and further preferably greater than 5 and less than 30.

[0351] There is no particular limitation on the method for adjusting the ratio of the average diameters (D2 / D1) of the aggregates of the fluororesin particles in each region, and examples thereof include: in the formation of the outermost surface layer, (1) a method for adjusting the number of treatments of the homogenizer when preparing a coating liquid containing fluororesin particles; (2) a method for adjusting the amount or type of fluororesin particles; (3) a method for adjusting the content of fluororesin particles in the outermost surface layer while using a plurality of coating liquids having different solid content concentrations of fluororesin particles to form a coating film with a concentration difference in stages; (4) a method for adjusting the drying temperature of the coating film in stages; (5) a method for increasing the relative speed between the coated material and the coating liquid during coating; etc.

[0352] The ratio of the average diameters of the aggregates of the fluorine-containing resin particles (D2 / D1) can be confirmed as follows.

[0353] (1) The outermost surface layer of the electrophotographic photoreceptor is cut in the thickness direction to obtain a test piece with the cross section as the observation surface.

[0354] (2) The observation surface of the test piece is observed using a scanning electron microscope (SEM) (manufactured by Hitachi, Ltd.: S-4100), and an image is captured. The image is then fed into an image analyzer (LUZEXIII, manufactured by NIRECO Co., Ltd.). Furthermore, the area of ​​each of the aggregates of the fluororesin particles in the first region of the outermost surface layer, from the surface (i.e., layer thickness 0 μm) to 1 / 2 of the layer thickness, is determined by image analysis. The equivalent circle diameter of each aggregate is then calculated from this area value, and the 50% diameter (D50) at the cumulative frequency based on the number of equivalent circle diameters obtained is taken as the average diameter (D1) of the aggregates of the fluororesin particles in the first region. Similarly, the average diameter (D2) of the aggregates of the fluororesin particles in the second region is determined.

[0355] (3) Calculate the ratio (D2 / D1).

[0356] (Primary Particle Size of Fluorine-Containing Resin Particles in Each Region)

[0357] In the electronic photographic photosensitive body of this embodiment, from the perspective of making an electronic photographic photosensitive body with better sensitivity and wear resistance, and from the perspective of suppressing the generation of color spots caused by the mixing of needle-shaped foreign matter, the primary particle size (D11) of the above-mentioned fluorine-containing resin particles in the first region from the surface to 1 / 2 of the layer thickness of the outermost surface layer, and the primary particle size (D12) of the above-mentioned fluorine-containing resin particles in the second region from 1 / 2 of the above-mentioned film thickness to the bottom surface of the above-mentioned outermost surface layer are each preferably greater than 20nm and less than 800nm, more preferably greater than 50nm and less than 600nm, and further preferably greater than 100nm and less than 500nm.

[0358] The primary particle size (D11 or D12) of the fluorine-containing resin particles in each region can be determined as follows: (1) The outermost surface layer of the electrophotographic photoreceptor is cut in the thickness direction to obtain a test piece with the cross section as the observation surface.

[0359] (2) The observation surface of the test piece is observed using a scanning electron microscope (SEM) (manufactured by Hitachi, Ltd.: S-4100), and an image is captured. The image is then introduced into an image analysis device (LUZEXIII, manufactured by NIRECO Co., Ltd.). Furthermore, the area of ​​all fluororesin particles (primary particles) in the first region of the outermost layer, from the surface (i.e., layer thickness 0 μm) to 1 / 2 of the layer thickness, is determined by image analysis. The equivalent circle diameter of each primary particle is then calculated from this area value, and the 50% diameter (D50) at the cumulative frequency based on the number of equivalent circle diameters obtained is used as the primary particle diameter (D11) of the fluororesin particles in the first region. Similarly, the primary particle diameter (D12) of the fluororesin particles in the second region is determined.

[0360] [Fluororesin particles]

[0361] The outermost surface layer contains fluorine-containing resin particles. The fluorine-containing resin particles may be used alone or in combination of two or more.

[0362] ·carboxyl

[0363] The fluorine-containing resin particles preferably do not contain carboxyl groups, or even if they do, they contain only a very small amount. Specifically, from the perspective of obtaining an electrophotographic photoreceptor with excellent charging properties, the number of carboxyl groups in the fluorine-containing resin particles is preferably 10 6 The number of carbon atoms is preferably 0 or more and 30 or less, more preferably 0 or more and 20 or less.

[0364] The carboxyl group of the fluorine-containing resin particles is a carboxyl group derived from a terminal carboxylic acid contained in the fluorine-containing resin particles.

[0365] The method for reducing the amount of carboxyl groups in the fluororesin particles is not particularly limited, and examples thereof include: (1) a method in which no radiation is irradiated during the fluororesin pelletization process; (2) a method in which the irradiation is performed under conditions in which oxygen is absent or the oxygen concentration is reduced; etc.

[0366] The amount of carboxyl groups in fluororesin particles is determined as follows according to Japanese Patent Application Laid-Open No. 4-20507. The fluororesin particles are preformed using a press to produce a film with a thickness of approximately 0.1 mm. The produced film is subjected to infrared absorption spectrum measurement. Fluorine-containing resin particles whose carboxylic acid ends are completely fluorinated by contacting fluorine gas with fluororesin particles are also subjected to infrared absorption spectrum measurement. The number of terminal carboxyl groups (per 10 6 number of carbon atoms).

[0367] The number of terminal carboxyl groups (per 10 6 number of carbon atoms) = (l×K) / t

[0368] l: absorbance

[0369] K: correction coefficient,

[0370] t: film thickness (mm)

[0371] The absorption wave number of carboxyl group is 3560 cm -1 , the correction factor is 440.

[0372] Basic compounds

[0373] The fluorine-containing resin particles preferably contain no basic compounds, or even if they do, only a trace amount. Specifically, to achieve excellent charging properties in an electrophotographic photoreceptor, the amount of basic compounds in the fluorine-containing resin particles is preferably from 0 ppm to 3 ppm, more preferably from 0 ppm to 1.5 ppm, and even more preferably from 0 ppm to 1.2 ppm. Note that ppm is based on mass.

[0374] Specific examples of the basic compound contained in the fluororesin particles include: 1) a basic compound derived from a polymerization initiator used when the fluororesin particles are polymerized and simultaneously granulated; 2) a basic compound used in the step of agglomeration after polymerization; 3) a basic compound used as a dispersing aid to stabilize the dispersion after polymerization; and the like.

[0375] Examples of the basic compound include amine compounds; hydroxides of alkali metals or alkaline earth metals; oxides of alkali metals or alkaline earth metals; acetates (for example, amine compounds are particularly preferred); and the like.

[0376] Examples of the basic compound include those having a boiling point (boiling point at normal pressure (1 atm)) of 40°C to 130°C (preferably 50°C to 110°C, more preferably 60°C to 90°C).

[0377] Examples of the amine compound include primary amine compounds, secondary amine compounds, and tertiary amine compounds.

[0378] Examples of the primary amine compound include methylamine, ethylamine, propylamine, isopropylamine, n-butylamine, isobutylamine, tert-butylamine, hexylamine, 2-ethylhexylamine, sec-butylamine, allylamine, and methylhexylamine.

[0379] Examples of the secondary amine compound include dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, diisobutylamine, di-tert-butylamine, dihexylamine, di(2-ethylhexyl)amine, N-isopropyl-N-isobutylamine, di(2-ethylhexyl)amine, di-sec-butylamine, diallylamine, N-methylhexylamine, 3-methylpiperidine, 4-methylpiperidine, 2,4-dimethylpiperidine, 2,6-dimethylpiperidine, 3,5-dimethylpiperidine, morpholine, and N-methylbenzylamine.

[0380] Examples of the tertiary amine compound include trimethylamine, triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, triisobutylamine, tri-tert-butylamine, trihexylamine, tri(2-ethylhexyl)amine, N-methylmorpholine, N,N-dimethylallylamine, N-methyldiallylamine, triallylamine, N,N-dimethylallylamine, N,N,N',N'-tetramethyl-1,2-diaminoethane, N,N,N',N'-tetramethyl-1,3-diaminopropane, N,N,N',N'-tetraallyl-1,4-diaminobutane, N-methylpiperidine, pyridine, 4-ethylpyridine, N-propyl Diallylamine, 3-dimethylaminopropanol, 2-ethylpyrazine, 2,3-dimethylpyrazine, 2,5-dimethylpyrazine, 2,4-lutidine, 2,5-lutidine, 3,4-lutidine, 3,5-lutidine, 2,4,6-trimethylpyridine, 2-methyl-4-ethylpyridine, 2-methyl-5-ethylpyridine, N,N,N',N'-tetramethyl-1,6-hexanediamine, N-ethyl-3-hydroxypiperidine, 3-methyl-4-ethylpyridine, 3-ethyl-4-methylpyridine, 4-(5-nonyl)pyridine, imidazole, N-methylpiperazine, etc.

[0381] Examples of the hydroxide of an alkali metal or an alkaline earth metal include NaOH, KOH, Ca(OH) 2 , Mg(OH) 2 , and Ba(OH) 2 .

[0382] Examples of the oxides of alkali metals or alkaline earth metals include CaO and MgO.

[0383] Examples of acetates include zinc acetate and sodium acetate.

[0384] There are no particular restrictions on the method for reducing the amount of alkaline compounds contained in the fluororesin particles. Examples include: (1) a method of washing the particles with water, an organic solvent (alcohols such as methanol, ethanol, isopropanol, tetrahydrofuran, etc.) after the particles are manufactured; 2) a method of heating the particles (for example, heating to a temperature of 200°C to 250°C) after the particles are manufactured to remove the alkaline compounds by decomposition or vaporization; and the like.

[0385] The amount of the basic compound contained in the fluorine-containing resin particles is measured as follows.

[0386] -Pre-treatment-

[0387] When measuring the outermost surface layer containing fluorine-containing resin particles, the sample of the outermost surface layer is immersed in a solvent (e.g., tetrahydrofuran), and the substances other than the fluorine-containing resin particles and the solvent-insoluble substances are dissolved in the solvent (e.g., tetrahydrofuran), and then added dropwise to pure water, and the precipitate is filtered out. The solution containing PFOA obtained at this time is captured. The insoluble matter obtained by filtering is further dissolved in a solvent, and then added dropwise to pure water, and the precipitate is filtered out. This operation is repeated a total of 5 times. Then, 800 mg of fluorine-containing resin particles are added to 1.5 ml of chloroform to dissolve the alkaline compound from the fluorine-containing resin particles to obtain a measurement sample.

[0388] -Determination-

[0389] On the other hand, a calibration curve (calibration curve from 0 ppm to 100 ppm) is obtained from the concentration of the basic compound and the peak area values ​​of the basic compound solution (methanol solvent) with known concentration using gas chromatography.

[0390] The sample was then measured using gas chromatography, and the amount of basic compounds in the sample was calculated from the obtained peak area and the calibration curve. The calculated amount of basic compounds in the sample was divided by the amount of fluororesin particles used in the sample to calculate the amount of basic compounds contained in the fluororesin particles. The measurement conditions were as follows.

[0391] -Measurement conditions-

[0392] Headspace sampler: (HP7694, manufactured by HP)

[0393] · Measuring instrument: Gas chromatograph (HP6890 series, manufactured by HP)

[0394] Detector: Flame ionization detector (FID)

[0395] Column: (HP19091S-433, manufactured by HP)

[0396] Sample heating time: 10min

[0397] Split ratio: 300:1

[0398] Flow rate: 1.0ml / min

[0399] Column temperature setting: 60℃ (3min), 60℃ / min, 200℃ (1min)

[0400] Fluorine-containing resin

[0401] Examples of the fluorine-containing resin constituting the fluorine-containing resin particles include: (1) particles of homopolymers of fluoroolefins; (2) copolymers of two or more fluoroolefins, i.e., copolymers of one or more fluoroolefins and a non-fluorine-containing monomer (i.e., a monomer having no fluorine atoms); and the like.

[0402] Examples of the fluoroolefin include perhaloolefins such as tetrafluoroethylene (TFE), perfluorovinyl ether, hexafluoropropylene (HFP), and chlorotrifluoroethylene (CTFE), and non-perfluorinated olefins such as vinylidene fluoride (VdF), trifluoroethylene, and ethylene fluoride. Among these, the fluoroolefin preferably contains one or more selected from the group consisting of VdF, TFE, CTFE, and HFP.

[0403] Examples of the non-fluorine-containing monomer include hydrocarbon olefins such as ethylene, propylene, and butene; alkyl vinyl ethers such as cyclohexyl vinyl ether (CHVE), ethyl vinyl ether (EVE), butyl vinyl ether, and methyl vinyl ether; alkenyl vinyl ethers such as polyoxyethylene allyl ether (POEAE) and ethyl allyl ether; organosilicon compounds having a reactive α,β-unsaturated group such as vinyltrimethoxysilane (VSi), vinyltriethoxysilane, and vinyltri(methoxyethoxy)silane; acrylic esters such as methyl acrylate and ethyl acrylate; methacrylic esters such as methyl methacrylate and ethyl methacrylate; vinyl esters such as vinyl acetate, vinyl benzoate, and "VeoVA" (trade name, vinyl ester manufactured by Shell); and the like. Among these, the non-fluorine-containing monomer preferably contains at least one selected from the group consisting of alkyl vinyl ethers, allyl vinyl ethers, vinyl esters, and organosilicon compounds having a reactive α,β-unsaturated group.

[0404] Among these, the fluorine-containing resin preferably contains a resin with a high fluorination rate, more preferably contains one or more resins selected from the group consisting of polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE) and ethylene-chlorotrifluoroethylene copolymer (ECTFE), and further preferably contains one or more resins selected from the group consisting of PTFE, FEP and PFA.

[0405] ·Method for granulating fluorine-containing resin

[0406] There is no particular limitation on the method for granulating the fluororesin, and the granulation method may be any of a method of granulating by irradiation with radiation (in this specification, the obtained particles are also referred to as "radiation-irradiated fluororesin particles"), a method of granulating by polymerization (in this specification, the obtained particles are also referred to as "polymerization-type fluororesin particles"), and the like.

[0407] Radiation-irradiated fluororesin particles (fluororesin particles obtained by irradiation) are fluororesin particles obtained by simultaneously granulating the polymerized fluororesin through radiation polymerization, and then reducing the polymerized fluororesin to a low molecular weight and micronizing it through radiation irradiation. Radiation-irradiated fluororesin particles generate a large amount of carboxylic acid upon exposure to radiation in the air, and therefore contain a large amount of carboxyl groups.

[0408] Polymerized fluororesin particles (fluororesin particles obtained by a polymerization method) are fluororesin particles that have been granulated during polymerization by methods such as suspension polymerization and emulsion polymerization and have not been irradiated. Polymerized fluororesin particles are produced by polymerization in the presence of a basic compound and therefore contain the basic compound as a residue.

[0409] Among these, the fluorine-containing resin particles are preferably polymerizable fluorine-containing resin particles. As described above, the polymerizable fluorine-containing resin particles are granulated simultaneously by suspension polymerization, emulsion polymerization, or the like, and are not irradiated with radiation.

[0410] Fluorine-containing resin particles are produced by suspension polymerization, for example, by suspending monomers for forming the fluorine-containing resin together with additives such as a polymerization initiator and a catalyst in a dispersion medium, and then forming the polymer into particles while polymerizing the monomers.

[0411] Fluorine-containing resin particles are produced by emulsion polymerization, for example, by emulsifying monomers for forming fluorine-containing resins together with additives such as polymerization initiators and catalysts in a dispersion medium using a surfactant (i.e., an emulsifier), and then forming polymer particles while polymerizing the monomers.

[0412] Average particle size

[0413] There is no particular restriction on the average particle size of the fluororesin particles, but it is preferably 0.1 μm to 4 μm, more preferably 0.1 μm to 2 μm. Fluororesin particles (especially PTFE particles, etc.) with an average particle size of 0.1 μm to 4 μm tend to contain a large amount of PFOA. Therefore, fluororesin particles with an average particle size of 0.1 μm to 4 μm tend to have reduced charging properties. However, by suppressing the amount of PFOA within the above range, it is believed that the charging properties of fluororesin particles with an average particle size of 0.1 μm to 4 μm are improved. The average particle size of the fluororesin particles is a value measured by the above method.

[0414] Specific surface area

[0415] From the viewpoint of dispersion stability, the specific surface area (BET specific surface area) of the fluorine-containing resin particles is preferably 5 m 2 / g above 15m 2 / g or less, more preferably 7m 2 / g above 13m 2 The specific surface area is a value measured by a nitrogen replacement method using a BET-type specific surface area measuring instrument (Flowsoap II2300 manufactured by Shimadzu Corporation).

[0416] Apparent density

[0417] From the viewpoint of dispersion stability, the apparent density of the fluorine-containing resin particles is preferably from 0.2 g / ml to 0.5 g / ml, more preferably from 0.3 g / ml to 0.45 g / ml. The apparent density is a value measured in accordance with JIS K6891 (1995).

[0418] Melting temperature

[0419] The melting temperature of the fluorine-containing resin particles is preferably 300° C. to 340° C., more preferably 325° C. to 335° C. The melting temperature is the melting point measured in accordance with JIS K6891 (1995).

[0420] (Fluorinated dispersant)

[0421] A dispersant having fluorine atoms (hereinafter also referred to as a "fluorine-containing dispersant") may be attached to the surface of the fluorine-containing resin particles. The fluorine-containing dispersant may be used alone or in combination of two or more.

[0422] Examples of the fluorine-containing dispersant include polymers obtained by homopolymerizing or copolymerizing a polymerizable compound having a fluorinated alkyl group (hereinafter also referred to as "fluorinated alkyl group-containing polymer"), fluorinated surfactants, and the like, preferably containing a fluorinated alkyl group-containing polymer.

[0423] Specific examples of fluoroalkyl group-containing polymers include homopolymers of (meth)acrylates having fluoroalkyl groups, random or block copolymers of (meth)acrylates having fluoroalkyl groups and monomers not having fluorine atoms, etc. It should be noted that in this specification, (meth)acrylate refers to both acrylates and methacrylates.

[0424] Examples of the (meth)acrylate having a fluoroalkyl group include 2,2,2-trifluoroethyl (meth)acrylate and 2,2,3,3,3-pentafluoropropyl (meth)acrylate.

[0425] Examples of the monomer not having a fluorine atom include (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 2-ethoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, benzyl (meth)acrylate, ethyl carbitol (meth)acrylate, phenoxyethyl (meth)acrylate, 2-hydroxy (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, hydroxyethyl o-phenylphenol (meth)acrylate, and o-phenylphenol glycidyl ether (meth)acrylate.

[0426] Furthermore, examples of fluorine-containing dispersants other than those mentioned above include block polymers and branched polymers disclosed in US Pat. No. 5,637,142 and Japanese Patent No. 4,251,662.

[0427] The fluoroalkyl group-containing polymer preferably includes a fluoroalkyl group-containing polymer having a structural unit represented by the following general formula (FA), and more preferably includes a fluoroalkyl group-containing polymer having a structural unit represented by the following general formula (FA) and a structural unit represented by the following general formula (FB).

[0428] Next, a fluoroalkyl group-containing polymer having a structural unit represented by the following general formula (FA) and a structural unit represented by the following general formula (FB) will be described.

[0429]

[0430] In the general formulas (FA) and (FB), R F1 、R F2 、R F3 and R F4 Each independently represents a hydrogen atom or an alkyl group.

[0431] X F1 represents an alkylene chain, a halogen-substituted alkylene chain, -S-, -O-, -NH-, or a single bond.

[0432] Y F1 represents an alkylene chain, a halogen-substituted alkylene chain, -(C fx H 2fx-1 (OH))- or single bond.

[0433] Q F1 It represents -O- or -NH-.

[0434] fl, fm, and fn each independently represent an integer greater than or equal to 1.

[0435] fp, fq, fr, and fs each independently represent an integer of 0 or 1 or greater.

[0436] ft represents an integer from 1 to 7.

[0437] fx represents an integer greater than or equal to 1.

[0438] In the general formulas (FA) and (FB), as the expression R F1 、R F2 、R F3 and R F4 The group is preferably a hydrogen atom, a methyl group, an ethyl group, a propyl group, etc., more preferably a hydrogen atom, a methyl group, and further preferably a methyl group.

[0439] In the general formulas (FA) and (FB), as the representation of X F1 and Y F1 The alkylene chain (unsubstituted alkylene chain, halogen-substituted alkylene chain) is preferably a linear or branched alkylene chain having 1 to 10 carbon atoms.

[0440] Represents Y F1 -(C fx H 2fx-1 It is preferable that fx in (OH))- represents an integer of 1-10.

[0441] It is preferred that fp, fq, fr and fs each independently represent 0 or an integer of 1 to 10.

[0442] For example, fn is preferably 1 or more and 60 or less.

[0443] In a fluoroalkyl-containing polymer having a structural unit represented by the general formula (FA) and a structural unit represented by the general formula (FB), the ratio of the structural unit represented by the general formula (FA) to the structural unit represented by the general formula (FB), i.e., fl:fm, is preferably in the range of 1:9 to 9:1, and more preferably in the range of 3:7 to 7:3.

[0444] The fluoroalkyl-containing polymer may be a polymer obtained by polymerizing a structural unit represented by the general formula (FC) in addition to the structural unit represented by the general formula (FA) and the structural unit represented by the general formula (FB). In this case, the content ratio of the structural unit represented by the general formula (FC) to the total content of the structural units represented by the general formulas (FA) and (FB) (i.e., fl + fm) (fl + fm:fz) is preferably in the range of 10:0 to 7:3, and more preferably in the range of 9:1 to 7:3.

[0445] (FC)

[0446]

[0447] In the general formula (FC), R F5 and R F6 Each independently represents a hydrogen atom or an alkyl group. fz represents an integer greater than or equal to 1.

[0448] In the general formula (FC), R F5 and R F6 The group is preferably a hydrogen atom, a methyl group, an ethyl group, a propyl group, etc., more preferably a hydrogen atom, a methyl group, and further preferably a methyl group.

[0449] Commercially available products of fluoroalkyl-containing polymers include, for example, GF300 and GF400 (manufactured by Toagosei Co., Ltd.), Surflon (registered trademark) series (manufactured by AGC Seimi Chemical Co., Ltd.), Ftergent series (manufactured by NOES Co., Ltd.), PF series (manufactured by Kitamura Chemical Co., Ltd.), MEGAFACE (registered trademark) series (manufactured by DIC), and FC series (manufactured by 3M).

[0450] Weight average molecular weight Mw

[0451] From the viewpoint of improving the dispersibility of the fluorinated resin particles, the weight average molecular weight Mw of the fluoroalkyl group-containing polymer is preferably from 20,000 to 200,000, more preferably from 50,000 to 200,000.

[0452] The weight-average molecular weight of the fluoroalkyl group-containing polymer is a value measured by gel permeation chromatography (GPC). Molecular weight measurement by GPC is performed, for example, using a Tosoh GPC HLC-8120 as the measuring apparatus and a Tosoh TSKgel GMHHR-M + TSKgel GMHHR-M column (7.8 mm I.D., 30 cm) in chloroform. Calculation is performed based on the measurement results using a molecular weight calibration curve prepared using monodisperse polystyrene standard samples.

[0453] ·content

[0454] The content of the fluorine-containing dispersant is, for example, preferably from 0.5% by mass to 10% by mass, and more preferably from 1% by mass to 7% by mass, based on the fluorine-containing resin particles.

[0455] ·Surface adhesion method of fluorinated dispersants

[0456] The method for making the fluorine-containing dispersant adhere to the surface of the fluorine-containing resin particles is not particularly limited, and examples thereof include the following (1) to (3).

[0457] (1) A method of preparing a dispersion of fluorine-containing resin particles by mixing fluorine-containing resin particles and a fluorine-containing dispersant in a dispersion solvent.

[0458] (2) A method in which fluorine-containing resin particles and a fluorine-containing dispersant are mixed using a dry powder mixer to allow the fluorine-containing dispersant to adhere to the fluorine-containing resin particles.

[0459] (3) A method in which a fluorine-containing dispersant dissolved in a solvent is added dropwise while the fluorine-containing resin particles are stirred, and the solvent is then removed.

[0460] Charge transport layer

[0461] The charge transport layer is, for example, a layer containing a charge transport material and a binder resin. The charge transport layer may also be a layer containing a polymer charge transport material.

[0462] Examples of charge transport materials include electron-transporting compounds such as quinone compounds such as p-benzoquinone, chloranil, bromoquinone, and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds; cyanovinyl compounds; and vinyl compounds. Other examples of charge transport materials include hole-transporting compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted vinyl compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These charge transport materials may be used alone or in combinations of two or more, but are not limited thereto.

[0463] Among these compounds, from the aspect of charge mobility, triarylamine compounds and benzidine compounds can be cited as preferred charge transport materials. Among them, as the triarylamine compound, a charge transport material represented by the following formula (CT1) as an example of a triarylamine compound is preferred (hereinafter also referred to as "butadiene-based charge transport material"). In addition, as the benzidine compound, a charge transport material represented by the following general formula (CT2) is preferred (hereinafter also referred to as "benzidine-based charge transport material").

[0464] Butadiene-based charge transport materials

[0465] The butadiene-based charge transport material is described below. The butadiene-based charge transport material is represented by the following general formula (CT1).

[0466]

[0467] In the general formula (CT1), R C11 、R C12 、R C13 、R C14 、R C15 and RC16 Each of the substituents independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an aryl group having 6 to 30 carbon atoms. Two adjacent substituents may be bonded to form a hydrocarbon ring structure. n and m independently represent 0, 1, or 2.

[0468] In the general formula (CT1), R C11 、R C12 、R C13 、R C14 、R C15 and R C16 Examples of the halogen atom represented by include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. Among these, the halogen atom is preferably a fluorine atom or a chlorine atom, and more preferably a chlorine atom.

[0469] In the general formula (CT1), R C11 、R C12 、R C13 、R C14 、R C15 and R C16 Examples of the alkyl group represented include linear or branched alkyl groups having 1 to 20 (preferably 1 to 6, more preferably 1 to 4) carbon atoms.

[0470] Specific examples of the linear alkyl group include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, and n-eicosyl.

[0471] Specific examples of the branched alkyl group include isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, tert-pentyl, isohexyl, sec-hexyl, tert-hexyl, isoheptyl, sec-heptyl, tert-heptyl, isooctyl, sec-octyl, tert-octyl, isononyl, sec-nonyl, tert-nonyl, isodecyl, sec-decyl, tert-decyl, isoundecyl, sec-undecyl, tert-undecyl, neoundecyl, isododecyl, sec-dodecyl, tert-dodecyl, neododecyl, isotridecyl, sec-tridecyl, tert-tridecyl, neotridecyl, isotetradecyl, sec-tetradecyl alkyl, tert-tetradecyl, neotetradecyl, 1-isobutyl-4-ethyloctyl, isopentadecyl, secondary pentadecyl, tert-pentadecyl, neopentadecyl, isohexadecyl, secondary hexadecyl, tert-hexadecyl, neohexadecyl, 1-methylpentadecyl, isoheptadecyl, secondary hexadecyl, tert-hexadecyl, neohexadecyl, isooctadecyl, secondary octadecyl, tert-octadecyl, neooctadecyl, isonadecyl, secondary nonadecyl, tert-nonadecyl, neononadecyl, 1-methyloctyl, isoeicosyl, secondary eicosyl, tert-eicosyl, neoeicosyl, etc.

[0472] Among these, the alkyl group is preferably a lower alkyl group such as a methyl group, an ethyl group, or an isopropyl group.

[0473] In the general formula (CT1), R C11 、R C12 、R C13 、R C14 、R C15 and R C16 Examples of the alkoxy group represented include linear or branched alkoxy groups having 1 to 20 (preferably 1 to 6, more preferably 1 to 4) carbon atoms.

[0474] Specific examples of the linear alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentoxy group, an n-hexyloxy group, an n-heptyloxy group, an n-octyloxy group, an n-nonyloxy group, an n-decyloxy group, an n-undecyloxy group, an n-dodecyloxy group, an n-tridecyloxy group, an n-tetradecyloxy group, an n-pentadecyloxy group, an n-hexadecyloxy group, an n-heptadecyloxy group, an n-octadecyloxy group, an n-nonadecyloxy group, and an n-eicosyloxy group.

[0475] Specific examples of the branched alkoxy group include isopropoxy, isobutoxy, sec-butoxy, tert-butoxy, isopentyloxy, neopentyloxy, tert-pentyloxy, isohexyloxy, sec-hexyloxy, tert-hexyloxy, isoheptyloxy, sec-heptyloxy, tert-heptyloxy, isooctyloxy, sec-octyloxy, tert-octyloxy, isononyloxy, sec-nonyloxy, tert-nonyloxy, isodecyloxy, sec-decyloxy, tert-decyloxy, isoundecyloxy, sec-undecyloxy, tert-undecyloxy, neoundecyloxy, isododecyloxy, sec-dodecyloxy, tert-dodecyloxy, neododecyloxy, isotridecyloxy, sec-tridecyloxy, tert-tridecyloxy, neotridecyloxy, isotetradecyloxy, sec-tetradecyloxy, tert-tetradecyloxy, neotetradecyloxy, 1-isobutyl-4-ethyloctyloxy, isopentadecyloxy, secondary pentadecyloxy, tert-pentadecyloxy, neopentadecyloxy, isohexadecyloxy, secondary hexadecyloxy, tert-hexadecyloxy, neohexadecyloxy, 1-methylpentadecyloxy, isoheptadecyloxy, secondary hexadecyloxy, tert-hexadecyloxy, neohexadecyloxy, isooctadecyloxy, secondary octadecyloxy, tert-octadecyloxy, neooctadecyloxy, isonadecyloxy, secondary nonadecyloxy, tert-nonadecyloxy, neononadecyloxy, 1-methyloctyloxy, isoeicosyloxy, secondary eicosyloxy, tert-eicosyloxy, neoeicosyloxy and the like.

[0476] Among these, the alkoxy group is preferably a methoxy group.

[0477] In the general formula (CT1), R C11 、R C12 、R C13 、R C14 、R C15 and R C16 Examples of the aryl group represented by include aryl groups having 6 to 30 carbon atoms (preferably 6 to 20, more preferably 6 to 16).

[0478] Specific examples of the aryl group include phenyl, naphthyl, phenanthrenyl, and biphenylyl.

[0479] Among these, as the aryl group, phenyl and naphthyl are preferred.

[0480] It should be noted that in the general formula (CT1), R C11 、R C12 、R C13 、R C14 、R C15 and R C1 Each of the substituents described above also includes groups further having substituents. Examples of the substituents include the atoms and groups exemplified above (e.g., halogen atoms, alkyl groups, alkoxy groups, aryl groups, etc.).

[0481] In the general formula (CT1), R C11 、R C12 、R C13 、R C14 、R C15 and R C16 Two adjacent substituents (such as R C11 and R C12 Each other, R C13 and R C14 Each other, R C15 and R C16 The group linking the substituents in the hydrocarbon ring structure in which the substituents are linked to each other) includes a single bond, 2,2'-methylene, 2,2'-ethylene, 2,2'-1,2-vinylene, etc. Among them, a single bond and 2,2'-methylene are preferred.

[0482] Here, specific examples of the hydrocarbon ring structure include a cycloalkane structure, a cycloalkene structure, and a cycloalkane polyene structure.

[0483] In the general formula (CT1), n ​​and m are preferably 1.

[0484] In the general formula (CT1), from the viewpoint of forming a photosensitive layer (charge transport layer) with high charge transport capability, R C11 、R C12 、R C13 、R C14 、R C15 and R C16 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an alkoxy group having 1 to 20 carbon atoms, m and n represent 1 or 2, and R is more preferably C11 、R C12 、R C13 、R C14 、R C15 and R C16 represents a hydrogen atom, and m and n represent 1.

[0485] That is, the butadiene-based charge transport material (CT1) is more preferably a charge transport material represented by the following structural formula (CT1A) (exemplary compound (CT1-3)).

[0486]

[0487] Specific examples of butadiene-based charge transport materials (CT1) are shown below, but are not limited thereto. It should be noted that, hereinafter, the exemplified compound numbers are referred to as exemplified compounds (CT1-numbers). Specifically, for example, exemplified compound 15 is referred to as "exemplified compound (CT1-15)."

[0488] No. m n <![CDATA[R C11 ]]> <![CDATA[R C12 ]]> <![CDATA[R C13 ]]> <![CDATA[R C14 ]]> <![CDATA[R C15 ]]> <![CDATA[R C16 ]]> CT1-1 1 1 <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> H H CT1-2 2 2 H H H H <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> CT1-3 1 1 H H H H H H CT1-4 2 2 H H H H H H CT1-5 1 1 <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> H H H CT1-6 0 1 H H H H H H CT1-7 0 1 <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> CT1-8 0 1 <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> H H <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> CT1-9 0 1 H H <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> H H CT1-10 0 1 H H <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> H H CT1-11 0 1 <![CDATA[4-CH3]]> H H H <![CDATA[4-CH3]]> H CT1-12 0 1 <![CDATA[4-OCH3]]> H H H <![CDATA[4-OCH3]]> H CT1-13 0 1 H H <![CDATA[4-OCH3]]> <![CDATA[4-OCH3]]> H H CT1-14 0 1 <![CDATA[4-OCH3]]> H <![CDATA[4-OCH3]]> H <![CDATA[4-OCH3]]> <![CDATA[4-OCH3]]> CT1-15 0 1 <![CDATA[3-CH3]]> H <![CDATA[3-CH3]]> H <![CDATA[3-CH3]]> H CT1-16 1 1 <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> CT1-17 1 1 <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> H H <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> CT1-18 1 1 H H <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> H H CT1-19 1 1 H H <![CDATA[3-CH 3 ]]> <![CDATA[3-CH3]]> H H CT1-20 1 1 <![CDATA[4-CH3]]> H H H <![CDATA[4-CH3]]> H CT1-21 1 1 <![CDATA[4-OCH3]]> H H H <![CDATA[4-OCH3]]> H CT1-22 1 1 H H <![CDATA[4-OCH3]]> <![CDATA[4-OCH3]]> H H CT1-23 1 1 <![CDATA[4-OCH3]]> H <![CDATA[4-OCH3]]> H <![CDATA[4-OCH3]]> <![CDATA[4-OCH3]]> CT1-24 1 1 <![CDATA[3-CH3]]> H <![CDATA[3-CH3]]> H <![CDATA[3-CH3]]> H

[0489] It should be noted that the abbreviations in the above-mentioned exemplary compounds have the following meanings: In addition, the number preceding the substituent indicates the substitution position on the benzene ring.

[0490] -CH3: methyl

[0491] -OCH3: methoxy

[0492] The butadiene-based charge transport material (CT1) may be used alone or in combination of two or more.

[0493] Benzidine-based charge transport materials

[0494] As the benzidine compound, from the viewpoint of charge mobility, preferably, there is mentioned a benzidine charge transport material (CT2) represented by the following general formula (CT2).

[0495] In particular, from the perspective of charge mobility, it is preferred to use a butadiene-based charge transport material (CT1) and a benzidine-based charge transport material (CT2) in combination as the charge transport material. It should be noted that from the perspective of charge transport performance, the mass ratio (content of butadiene-based charge transport material (CT1) / content of benzidine-based charge transport material (CT2)) when the butadiene-based charge transport material (CT1) and the benzidine-based charge transport material (CT2)) are preferably 1 / 9 or more and 5 / 5 or less, and more preferably 1 / 9 or more and 4 / 6 or less.

[0496] The benzidine-based charge transport material is described below. The benzidine-based charge transport material is represented by the following general formula (CT2).

[0497]

[0498] In the general formula (CT2), R C21 、R C22 and R C23 Each independently represents a hydrogen atom, a halogen atom, a hydroxyl group, a formyl group, an alkyl group, an alkoxy group, or an aryl group.

[0499] In the general formula (CT2), R C21 、R C22 and R C23 Examples of the halogen atom represented by include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. Among these, the halogen atom is preferably a fluorine atom or a chlorine atom, and more preferably a chlorine atom.

[0500] In the general formula (CT2), R C21 、R C22 , and RC23 Examples of the alkyl group include linear or branched alkyl groups having 1 to 10 (preferably 1 to 6, more preferably 1 to 4) carbon atoms.

[0501] Specific examples of the linear alkyl group include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl.

[0502] Specific examples of the branched alkyl group include isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, tert-pentyl, isohexyl, sec-hexyl, tert-hexyl, isoheptyl, sec-heptyl, tert-heptyl, isooctyl, sec-octyl, tert-octyl, isononyl, sec-nonyl, tert-nonyl, isodecyl, sec-decyl, and tert-decyl.

[0503] Among these, the alkyl group is preferably a lower alkyl group such as a methyl group, an ethyl group, or an isopropyl group.

[0504] In the general formula (CT2), R C21 、R C22 and R C23 Examples of the alkoxy group represented include linear or branched alkoxy groups having 1 to 10 (preferably 1 to 6, more preferably 1 to 4) carbon atoms.

[0505] Specific examples of the linear alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentoxy group, an n-hexyloxy group, an n-heptyloxy group, an n-octyloxy group, an n-nonyloxy group, and an n-decyloxy group.

[0506] Specific examples of the branched alkoxy group include isopropoxy, isobutoxy, sec-butoxy, tert-butoxy, isopentyloxy, neopentyloxy, tert-pentyloxy, isohexyloxy, sec-hexyloxy, tert-hexyloxy, isoheptyloxy, sec-heptyloxy, tert-heptyloxy, isooctyloxy, sec-octyloxy, tert-octyloxy, isononyloxy, sec-nonyloxy, tert-nonyloxy, isodecyloxy, sec-decyloxy, and tert-decyloxy.

[0507] Among these, the alkoxy group is preferably a methoxy group.

[0508] In the general formula (CT2), R C21 、R C22 and R C23 The aryl group represented by can be exemplified by an aryl group having 6 or more and 10 or less carbon atoms (preferably 6 or more and 9 or less, more preferably 6 or more and 8 or less). Specific examples of the aryl group include phenyl and naphthyl. Among these, phenyl is preferred as the aryl group.

[0509] It should be noted that in the general formula (CT2), R C21 、R C22 and RC23 Each of the substituents described above also includes groups further having a substituent. Examples of the substituent include the atoms and groups exemplified above (e.g., a halogen atom, an alkyl group, an alkoxy group, an aryl group, etc.).

[0510] In the general formula (CT2), from the viewpoint of forming a photosensitive layer (charge transport layer) with high charge transport capability, R C21 、R C22 and R C23 Each independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and more preferably R C21 、R C22 and R C23 represents a hydrogen atom, R C22 It represents an alkyl group having 1 to 10 carbon atoms (particularly a methyl group).

[0511] Specifically, the benzidine-based charge transport material (CT2) is particularly preferably a charge transport material represented by the following structural formula (CT2A) (exemplary compound (CT2-2)).

[0512]

[0513] Specific examples of charge transport materials represented by general formula (CT2) are shown below, but are not limited thereto. It should be noted that, hereinafter, the following exemplary compound numbers are referred to as exemplary compounds (CT2-numbers). Specifically, for example, exemplary compound 15 is referred to as "exemplary compound (CT2-15)" below.

[0514] No <![CDATA[D C21 ]]> <![CDATA[R C22 ]]> <![CDATA[R C23 ]]> CT2-1 H H H CT2-2 H <![CDATA[3-CH3]]> H CT2-3 H <![CDATA[4-CH3]]> H CT2-4 H <![CDATA[3-C2H5]]> H CT2-5 H <![CDATA[4-C2H5]]> H CT2-6 H <![CDATA[3-OCH3]]> H CT2-7 H <![CDATA[4-OCH3]]> H CT2-8 H <![CDATA[3-OC2H5]]> H CT2-9 H <![CDATA[4-OC2H5]]> H CT2-10 <![CDATA[3-CH3]]> <![CDATA[3-CH3]]> H CT2-11 <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> H CT2-12 <![CDATA[3-C2H5]]> <![CDATA[3-C2H5]]> H CT2-13 <![CDATA[4-C2H5]]> <![CDATA[4-C2H5]]> H CT2-14 H H <![CDATA[2-CH3]]> CT2-15 H H <![CDATA[3-CH3]]> CT2-16 H <![CDATA[3-CH3]]> <![CDATA[2-CH3]]> CT2-17 H <![CDATA[3-CH3]]> <![CDATA[3-CH3]]> CT2-18 H <![CDATA[4-CH3]]> <![CDATA[2-CH3]]> CT2-19 H <![CDATA[4-CH3]]> <![CDATA[3-CH3]]> CT2-20 <![CDATA[3-CH3]]> <![CDATA[3-CH3]]> <![CDATA[2-CH3]]> CT2-21 <![CDATA[3-CH3]]> <![CDATA[3-CH3]]> <![CDATA[3-CH3]]> CT2-22 <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> <![CDATA[2-CH3]]> CT2-23 <![CDATA[4-CH3]]> <![CDATA[4-CH3]]> <![CDATA[3-CH3]]>

[0515] It should be noted that the abbreviations in the above-mentioned exemplary compounds have the following meanings: In addition, the number preceding the substituent indicates the substitution position on the benzene ring.

[0516] -CH3: methyl

[0517] -C2H5: ethyl

[0518] -OCH3: methoxy

[0519] -OC2H5: ethoxy

[0520] The benzidine-based charge transport material (CT2) may be used alone or in combination of two or more.

[0521] As polymeric charge transport materials, known materials having charge transport properties, such as poly-N-vinylcarbazole and polysilane, are used. Polyester-based polymeric charge transport materials disclosed in Japanese Patent Application Laid-Open Nos. 8-176293 and 8-208820 are particularly preferred. It should be noted that polymeric charge transport materials can be used alone or in combination with a binder resin.

[0522] The adhesive resin used in the charge transport layer can include polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-modified alkyd resin, phenol-formaldehyde resin, styrene-modified alkyd resin, poly-N-vinyl carbazole, polysilane, etc. Among these, as the adhesive resin, polycarbonate resin or polyarylate resin is preferred. The adhesive resin can be used alone or in combination of two or more.

[0523] The mixing ratio of the charge transport material to the binder resin is preferably 10:1 or more and 1:5 or less in terms of mass ratio.

[0524] When a large number of fluororesin particles having carboxyl groups are used together with a polycarbonate resin, the dispersibility of the fluororesin particles tends to decrease. In particular, when a polycarbonate resin containing a structural unit represented by the following general formula (PCA) and a structural unit represented by the following general formula (PCB) is used, in which the number of carbonate groups (-OC(=O)O-) per unit mole is increased, the dispersibility of the fluororesin particles tends to decrease. Therefore, when a polycarbonate resin containing a structural unit represented by the following general formula (PCA) and a structural unit represented by the following general formula (PCB) is used, it is preferred to use a polycarbonate resin containing a structural unit represented by the following general formula (PCA) and a structural unit represented by the following general formula (PCB), wherein the number of carboxyl groups per 10 6 Fluorine-containing resin particles having 0 to 30 carbon atoms.

[0525]

[0526] In the general formula (PCA) and (PCB), R P1 、R P2 、R P3 and R P4 Each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, or an aryl group having 6 to 12 carbon atoms. P1 represents a phenylene group, a biphenylene group, a naphthylene group, an alkylene group, or a cycloalkylene group.

[0527] In the general formula (PCA) and (PCB), as R P1 、R P2 、R P3 and R P4 Examples of the alkyl group include linear or branched alkyl groups having 1 to 6 carbon atoms (preferably 1 to 3 carbon atoms).

[0528] Specific examples of the linear alkyl group include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, and an n-hexyl group.

[0529] Specific examples of the branched alkyl group include isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, tert-pentyl, isohexyl, sec-hexyl, and tert-hexyl.

[0530] Among these, the alkyl group is preferably a lower alkyl group such as a methyl group or an ethyl group.

[0531] In the general formula (PCA) and (PCB), as R P1 、R P2 、R P3 and R P4 Examples of the cycloalkyl group include cyclopentyl, cyclohexyl and cycloheptyl.

[0532] In the general formula (PCA) and (PCB), as R P1 、R P2 、R P3 and R P4 Examples of the aryl group include phenyl, naphthyl, and biphenyl.

[0533] In the general formula (PCA) and (PCB), as X P1 Examples of the alkylene group include linear or branched alkylene groups having 1 to 12 carbon atoms (preferably 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms).

[0534] Specific examples of the linear alkylene group include methylene, ethylene, n-propylene, n-butylene, n-pentylene, n-hexylene, n-heptylene, n-octylene, n-nonylene, n-decylene, n-undecylene, and n-dodecylene.

[0535] Specific examples of the branched alkylene group include isopropylene, isobutylene, sec-butylene, tert-butylene, isopentylene, neopentylene, tert-pentylene, isohexylene, sec-hexylene, tert-hexylene, isoheptylene, sec-heptylene, tert-octylene, isooctylene, sec-octylene, tert-octylene, isononylene, sec-nonylene, tert-nonylene, isodecylene, sec-decylene, tert-decylene, isoundecylene, sec-undecylene, tert-undecylene, neoundecylene, isododecylene, sec-dodecylene, tert-dodecylene, and neododecylene.

[0536] Among these, the alkylene group is preferably a lower alkyl group such as a methylene group, an ethylene group, or a butylene group.

[0537] In the general formula (PCA) and (PCB), as X P1 Examples of the cycloalkylene group represented by include cycloalkylene groups having 3 to 12 carbon atoms (preferably 3 to 10 carbon atoms, more preferably 5 to 8 carbon atoms).

[0538] Specific examples of the cycloalkylene group include cyclopropylene, cyclopentylene, cyclohexylene, cyclooctylene, and cyclododecylene.

[0539] Among these, the cycloalkylene group is preferably a cyclohexylene group.

[0540] It should be noted that in the general formulas (PCA) and (PCB), R P1 、R P2 、R P3 、R P4 and X P1 Each of the above-mentioned substituents also includes groups further having substituents. Examples of such substituents include halogen atoms (e.g., fluorine atoms, chlorine atoms), alkyl groups (e.g., alkyl groups having 1 to 6 carbon atoms), cycloalkyl groups (e.g., cycloalkyl groups having 5 to 7 carbon atoms), alkoxy groups (e.g., alkoxy groups having 1 to 4 carbon atoms), and aryl groups (e.g., phenyl groups, naphthyl groups, and biphenyl groups).

[0541] In the general formula (PCA), R P1 and R P2 Each independently represents preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R P1 and R P2 More preferably, it represents a hydrogen atom.

[0542] In the general formula (PCB), R P3 and R P4 Each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, X P1 Preferably it represents an alkylene group or a cycloalkylene group.

[0543] Specific examples of BP polycarbonate resins include, but are not limited to, the following: In the exemplified compounds, pm and pn represent copolymerization ratios.

[0544] (PC-1)

[0545]

[0546] (PC-2)

[0547]

[0548] (PC-3)

[0549]

[0550] Here, in the P polycarbonate resin, the content (copolymerization ratio) of the structural unit represented by the general formula (PCA) can be in the range of 5 mol% to 95 mol% relative to all the structural units constituting the polycarbonate resin. From the perspective of suppressing the concentration unevenness of the granular image, it is preferably in the range of 5 mol% to 50 mol%, and more preferably in the range of 15 mol% to 30 mol%.

[0551] Specifically, in the above-mentioned exemplary compounds of the BP polycarbonate resin, pm and pn represent the copolymerization ratio (molar ratio), and pm:pn is in the range of 95:5 to 5:95, 50:50 to 5:95, and more preferably 15:85 to 30:70.

[0552] The mixing ratio of the charge transport material to the binder resin is preferably 10:1 to 1:5 in terms of mass ratio.

[0553] The charge transport layer may further contain other known additives.

[0554] The charge transport layer can be formed by any known method without particular limitation. For example, a charge transport layer can be formed by forming a coating film of a charge transport layer-forming coating solution prepared by adding the above-mentioned components to a solvent, drying the coating film, and heating the coating film as needed.

[0555] Examples of solvents used to prepare the charge transport layer coating solution include common organic solvents such as aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene; ketones such as acetone and 2-butanone; halogenated aliphatic hydrocarbons such as dichloromethane, chloroform, and vinyl chloride; and cyclic or linear ethers such as tetrahydrofuran and diethyl ether. These solvents may be used alone or in combination of two or more.

[0556] Examples of the coating method for coating the charge transport layer-forming coating liquid on the charge generating layer include common methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0557] The film thickness of the charge transport layer is set, for example, preferably within a range of 5 μm to 50 μm, more preferably within a range of 10 μm to 30 μm.

[0558] Surface protection layer

[0559] The surface protection layer is provided on the photosensitive layer as needed.

[0560] The surface protective layer is provided for the purpose of, for example, preventing chemical changes in the photosensitive layer during charging or further improving the mechanical strength of the photosensitive layer.

[0561] Examples of the surface protective layer composed of a cured film include the layer shown in the following (1) or (2).

[0562] (1) A layer composed of a cured film of a composition comprising a reactive group-containing charge transport material having a reactive group and a charge transport skeleton in the same molecule (i.e., a layer comprising a polymer or a crosslinked product of the reactive group-containing charge transport material)

[0563] (2) A layer composed of a cured film of a composition comprising a non-reactive charge transport material and a reactive group-containing non-charge transport material having no charge transport skeleton but having a reactive group (i.e., a layer comprising a non-reactive charge transport material and a polymer or crosslinked product of the reactive group-containing non-charge transport material)

[0564] Examples of the reactive group of the reactive group-containing charge transport material include chain polymerizable groups, epoxy groups, -OH, -OR [wherein R represents an alkyl group], -NH2, -SH, -COOH, -SiR Q1 3-Qn (OR Q2 ) Qn [Among them, R Q1 represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, R Q2 represents a hydrogen atom, an alkyl group, a trialkylsilyl group, and Qn represents an integer of 1 to 3] and other known reactive groups.

[0565] The chain polymerizable group is not particularly limited as long as it is a functional group capable of free radical polymerization, and is, for example, a functional group having at least a carbon double bond. Specifically, examples include groups containing at least one selected from a vinyl group, a vinyl ether group, a vinyl sulfide group, a styryl (vinylphenyl) group, an acryloyl group, a methacryloyl group, and derivatives thereof. Among them, due to its excellent reactivity, the chain polymerizable group is preferably a group containing at least one selected from a vinyl group, a styryl (vinylphenyl) group, an acryloyl group, a methacryloyl group, and derivatives thereof.

[0566] The charge transport skeleton of the reactive group-containing charge transport material is not particularly limited as long as it has a known structure in electrophotographic photoreceptors. Examples thereof include structures in which the skeleton is derived from a nitrogen-containing hole transport compound such as a triarylamine compound, a benzidine compound, or a hydrazone compound, and is conjugated with a nitrogen atom. Among these, a triarylamine skeleton is preferred.

[0567] The reactive group-containing charge transport material, non-reactive charge transport material, and reactive group-containing non-charge transport material having a reactive group and a charge transport skeleton may be selected from known materials.

[0568] The surface protection layer may contain other known additives.

[0569] The formation of the surface protective layer is not particularly limited and can be carried out by a known formation method. For example, it can be carried out as follows: a coating film of a surface protective layer-forming coating liquid is formed by adding the above-mentioned components to a solvent, the coating film is dried, and a curing treatment such as heating is performed as needed to form the surface protective layer.

[0570] Examples of solvents used to prepare the coating solution for forming the surface protective layer include aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; ether solvents such as tetrahydrofuran and dioxane; cellosolve solvents such as ethylene glycol monomethyl ether; and alcohol solvents such as isopropyl alcohol and butanol. These solvents may be used alone or in combination of two or more.

[0571] In addition, the coating liquid for forming a surface protective layer may be a solvent-free coating liquid.

[0572] Examples of methods for applying the coating liquid for forming a surface protective layer onto a photosensitive layer (e.g., a charge transport layer) include common methods such as dip coating, extrusion coating, wire rod coating, spray coating, blade coating, knife coating, and curtain coating.

[0573] The film thickness of the surface protection layer is set, for example, preferably within a range of 1 μm to 20 μm, more preferably within a range of 2 μm to 10 μm.

[0574] -Image forming apparatus and process cartridge-

[0575] The description of the image forming apparatus and the process cartridge is the same as that of the first embodiment and is therefore omitted. In addition, the charging device, exposure device, developing device, transfer device, and intermediate transfer member of the image forming apparatus are also the same as those of the first embodiment and are therefore omitted.

[0576] -Cleaning device-

[0577] The cleaning device 13 supported by the process cartridge is a cleaning blade type device including a cleaning blade 131 .

[0578] It should be noted that, in addition to the cleaning blade method, a brush cleaning method and a simultaneous development and cleaning method may also be used.

[0579] Example

[0580] The following describes examples of the first embodiment, but the present invention is not limited to these examples. It should be noted that in the following description, "parts" and "%" are based on mass unless otherwise specified.

[0581] <Production of Fluorine-Containing Resin Particles>

[0582] (Production of fluorine-containing resin particles (1))

[0583] Fluorine-containing resin particles (1) were produced as follows.

[0584] An autoclave was charged with 3 liters of deionized water, 3.0 g of ammonium perfluorooctanoate, and 110 g of paraffin wax (manufactured by Nippon Oil Corporation) as an emulsion stabilizer. The atmosphere was purged three times with nitrogen and twice with TFE (tetrafluoroethylene) to remove oxygen. The internal pressure was then brought to 1.0 MPa using TFE, and the reaction was maintained at an internal temperature of 70°C while stirring at 250 rpm. Next, 150 cc of ethane at atmospheric pressure was added as a chain transfer agent, and 20 ml of an aqueous solution containing 300 mg of ammonium persulfate was added as a polymerization initiator to initiate the reaction. During the reaction, the temperature within the system was maintained at 70°C, and TFE was continuously supplied to maintain the internal pressure of the autoclave at 1.0 ± 0.05 MPa. After the initiator was added, the TFE supply and stirring were stopped when 1000 g of TFE had been consumed, terminating the reaction. The particles were then separated by centrifugation, and 400 parts by mass of methanol was collected and washed with a stirrer at 250 rpm for 10 minutes while irradiating with ultrasound. The supernatant was filtered. This operation was repeated three times, and the filtrate was dried at 60 degrees Celsius under reduced pressure for 17 hours.

[0585] Through the above steps, fluorine-containing resin particles (1) are produced.

[0586] <Example 1>

[0587] (Production of Photoreceptor)

[0588] Using the obtained fluorine-containing resin particles, a photoreceptor was produced as follows.

[0589] Zinc oxide (average particle size 70 nm: manufactured by TAYCA; specific surface area 15 m 2 100 parts of 1,2-dimethylbenzene (1,2-dihydrogen 2-nitropropene) and 500 parts of tetrahydrofuran were stirred and mixed. 1.4 parts of a silane coupling agent (KBE503, manufactured by Shin-Etsu Chemical Co., Ltd.) was added and stirred for 2 hours. The toluene was then removed by distillation under reduced pressure, and the mixture was calcined at 120°C for 3 hours to obtain silane coupling agent-surface-treated zinc oxide.

[0590] 110 parts of the surface-treated zinc oxide and 500 parts of tetrahydrofuran were stirred and mixed, and a solution of 0.6 parts of alizarin dissolved in 50 parts of tetrahydrofuran was added, followed by stirring at 50°C for 5 hours. The alizarin-bearing zinc oxide was then filtered out by vacuum filtration and further dried at 60°C under reduced pressure to obtain alizarin-bearing zinc oxide.

[0591] 60 parts of the alizarin-attached zinc oxide, 13.5 parts of a curing agent (blocked isocyanate Sumidur 3175, manufactured by Sumitomo-Bayer Urethane Co., Ltd.), 15 parts of a butyral resin (S-LECBM-1, manufactured by Sekisui Chemical Co., Ltd.), and 85 parts of methyl ethyl ketone were mixed to obtain a mixed solution. 38 parts of the mixed solution was mixed with 25 parts of methyl ethyl ketone and the mixture was stirred for 2 hours. The glass beads were dispersed using a sand mill for 2 hours to obtain a dispersion.

[0592] To the resulting dispersion, 0.005 parts of dioctyltin dilaurate as a catalyst and 30 parts of silicone resin particles (TOSPEARL 145, Momentive Performance Materials Japan) were added to obtain a primer coating solution. This coating solution was applied to a cylindrical aluminum substrate by dip coating and dried and cured at 170°C for 30 minutes to obtain a 24 μm thick primer layer.

[0593] Next, 1 part of hydroxygallium phthalocyanine (which exhibits strong diffraction peaks at Bragg angles (2θ±0.2°) of 7.5°, 9.9°, 12.5°, 16.3°, 18.6°, 25.1°, and 28.3° in its X-ray diffraction spectrum) was mixed with 1 part of polyvinyl butyral (S-LECBM-5, manufactured by Sekisui Chemical Co., Ltd.) and 80 parts of n-butyl acetate. The mixture was dispersed with glass beads using a paint shaker for one hour to prepare a coating solution for a charge generation layer. The resulting coating solution was then dip-coated onto the conductive substrate having the undercoat layer formed thereon and then heat-dried at 130°C for 10 minutes to form a charge generation layer having a thickness of 0.15 μm.

[0594] 45 parts of a benzidine compound represented by the following formula (CTM1) as a charge transport material and 55 parts of a polymer compound (viscosity-average molecular weight: 40,000) having a repeating unit represented by the following formula (PCZ1) as a binder resin were dissolved in 350 parts of toluene and 150 parts of tetrahydrofuran, 8.0 parts of fluorine-containing resin particles (1) and 0.4 parts of a fluorine-containing graft polymer (product name: GF400, manufactured by Toagosei Co., Ltd.) were added, and the mixture was treated five times using a high-pressure homogenizer to prepare a coating liquid for a charge transport layer.

[0595] The obtained coating liquid was applied to the charge generating layer by dip coating, and heated at 120° C. for 30 minutes while blowing air at a wind speed of 1.5 m / s to form a charge transport layer with a film thickness of 31 μm.

[0596]

[0597] After the above steps, a photoreceptor is produced.

[0598] (Processing Box Production)

[0599] The prepared photoreceptor was installed in a process cartridge equipped with a cleaning member of an image forming apparatus (DocuPrint CP500d, manufactured by Fuji Xerox Co., Ltd.) to obtain a process cartridge. A total of five process cartridges were prepared, each having a cleaning member contact pressure on the photoreceptor as shown in Table 2.

[0600] <Examples 2 to 18, Comparative Examples 1 to 4>

[0601] Photoreceptors and process cartridges were prepared in the same manner as in Example 1, except that the type, amount, and area occupied by the fluorine-containing resin particles, the amount of the fluorine-containing graft polymer, the heating conditions for the charge transport layer coating liquid, and the contact pressure of the cleaning member on the photoreceptor were changed as shown in Tables 2 and 3. It should be noted that only one process cartridge was prepared for each example.

[0602] <Evaluation>

[0603] (Image quality evaluation)

[0604] The processing boxes obtained in each example were packaged separately (factory status), set in a vibration tester (G-9223LS manufactured by Zhenyan Co., Ltd.), and all vibration conditions (i) to (iii) shown in the following Table 1 were applied (* in Table 1 means that after scanning from 3 Hz to 100 Hz at a rate of 0.3 Hz / second, the frequency was changed from 100 Hz to 3 Hz at a rate of 0.3 Hz / second). The processing box was installed in an image forming device (DocuPrint CP500d, manufactured by Fuji Xerox Co., Ltd.), and a 30% concentration halftone image was output to A4 paper (P paper, manufactured by Fuji Xerox) under an environment of 22°C and 55% RH for image formation. The images formed on the 1st and 15th sheets were visually evaluated. After that, after being placed for 24 hours, the image formed on the 1st sheet was visually evaluated. The judgment criteria are as follows.

[0605] -Judgment Criteria-

[0606] A: No streaks were generated.

[0607] B: Faint streaks can be seen when looking closely.

[0608] C: Although the presence of streaky images can be faintly confirmed in the halftone image, there is no practical problem.

[0609] D: The presence of a streak-like image can be confirmed in the halftone image, but it is not detected in the text image.

[0610] E: The presence of a streak-like image can be clearly recognized in the halftone image, and the presence of streaks is also faintly recognized in the text image.

[0611] F: The presence of stripes is clearly recognized in the halftone image and text image.

[0612] (Residual Potential Evaluation)

[0613] The photoreceptor obtained in each example was rotated at 100 rpm and charged to -700 V using a scorotron charger. After charging for 0.05 seconds, the photoreceptor was irradiated with 2.0 mJ / m² of a semiconductor laser having a wavelength of 780 nm. 2 Then, 20 mJ / m was irradiated to the photoreceptor 0.1 seconds after the discharge. 2 Then, the potential V on the surface of the photoreceptor was measured 100 msec after the start of the static elimination, and this was taken as the residual potential value.

[0614] The residual potential was evaluated according to the following criteria.

[0615] A: -50V or above

[0616] B: less than -50V and above -100V

[0617] C: less than -100V

[0618] The following describes the records in Tables 2 and 3.

[0619] The “heating conditions” refer to the conditions for heating the coating film of the charge transport layer coating liquid when forming the charge transport layer.

[0620] The “fluorine atom concentration ratio” represents the multiple of the fluorine atom concentration measured at the surface of the charge transport layer relative to the fluorine atom concentration measured at a depth of 1 μm from the surface of the charge transport layer.

[0621] The “charge transport material concentration ratio” refers to the multiple of the charge transport material concentration measured at the surface of the charge transport layer relative to the charge transport material concentration measured at the center of the thickness of the charge transport layer.

[0622]

[0623]

[0624]

[0625] The above results indicate that the photoreceptor of this embodiment can suppress the occurrence of streak-like image defects and residual potential caused by friction between the photoreceptor and its contact member due to vibration.

[0626] The second embodiment will be described in detail below with reference to Examples, but the present embodiment is not limited to these Examples. It should be noted that in the following description, "parts" and "%" are based on mass unless otherwise specified.

[0627] -Production of electrophotographic photoreceptors-

[0628] [Example 19]

[0629] (Formation of Primer Layer)

[0630] 100 parts by mass of zinc oxide particles (trade name: MZ 300, manufactured by TAYCA Co., Ltd., volume average primary particle size: 35 nm), 10 parts by mass of a 10% toluene solution of N-2-(aminoethyl)-3-aminopropyltriethoxysilane as a silane coupling agent, and 200 parts by mass of toluene were mixed and stirred, then refluxed for 2 hours. The toluene was then distilled off under reduced pressure at 10 mmHg, and the resulting mixture was calcined at 135°C for 2 hours to surface-treat the zinc oxide with the silane coupling agent.

[0631] 33 parts by mass of surface-treated zinc oxide particles, 6 parts by mass of blocked isocyanate (trade name: Sumidur 3175, manufactured by Sumitomo-Bayer Urethane Co., Ltd.), 1 part by mass of a compound represented by the following general formula (AK-1), and 25 parts by mass of methyl ethyl ketone were mixed for 30 minutes. Subsequently, 5 parts by mass of a butyral resin (trade name: S-LECBM-1, manufactured by Sekisui Chemical Co., Ltd.), 3 parts by mass of silicone beads (trade name: TOSPEARL 120, manufactured by Momentive Performance Materials), and 0.01 part by mass of Toray Dow Corning silicone oil (trade name: SH29PA, manufactured by Dow Corning) as a leveling agent were added, and the mixture was dispersed using a sand mill for 1.8 hours (i.e., the dispersion time was set to 1.8 hours) to obtain a coating liquid for forming an undercoat layer.

[0632]

[0633] The obtained coating liquid for forming an undercoat layer was applied to an aluminum substrate (conductive substrate) having a diameter of 47 mm, a length of 357 mm, and a thickness of 1 mm by dip coating, and dried and cured at 180° C. for 30 minutes to obtain an undercoat layer having a film thickness of 25 μm.

[0634] (Formation of Charge Generation Layer)

[0635] The hydroxygallium phthalocyanine pigment as the charge generating material is a V-type hydroxygallium phthalocyanine pigment having diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.3°, 16.0°, 24.9°, and 28.0° in an X-ray diffraction spectrum using Cukα characteristic X-rays (maximum peak wavelength in the spectral absorption spectrum in the wavelength region of 600 nm to 900 nm = 820 nm, average particle size = 0.12 μm, maximum particle size = 0.2 μm, specific surface area value = 60 m 2 / g)", a mixture of vinyl chloride-vinyl acetate copolymer resin (trade name: VMCH, manufactured by NUC Co., Ltd.) as a binder resin and n-butyl acetate was added at a filling rate of 50%. The glass beads were placed in a 100 mL glass bottle and dispersed using a paint shaker for 2.5 hours to obtain a coating solution for a charge generation layer. The mixture of the hydroxygallium phthalocyanine pigment and the vinyl chloride-vinyl acetate copolymer resin was prepared such that the hydroxygallium phthalocyanine pigment content was 55.0% by volume and the solid content of the dispersion was 6.0% by mass. The specific gravity of the hydroxygallium phthalocyanine pigment was 1.606 g / cm 3 The specific gravity of vinyl chloride-vinyl acetate copolymer resin is 1.35g / cm 3 The content rate is calculated.

[0636] The obtained coating liquid for forming a charge generating layer was dip-coated on the undercoat layer and dried at 100° C. for 5 minutes to form a charge generating layer having a film thickness of 0.20 μm.

[0637] (Formation of Charge Transport Layer)

[0638] 8.0 parts by mass of the exemplary compound (CT1-1) as a hole transport material represented by the above general formula (1) and 32.0 parts by mass of a benzidine-based charge transport material (CT2-1) as a charge transport material, 60.0 parts by mass of a BP polycarbonate resin (pm:pn=25:75, viscosity-average molecular weight: 50,000) represented by the above general formula (PC-1) as a binder resin, 8 parts by mass of polytetrafluoroethylene (PTFE) as fluorine-containing resin particles, 0.2 parts by mass of "GF400 (manufactured by Toagosei Co., Ltd., a surfactant containing at least a methacrylate having a fluoroalkyl group as a polymerization component)" as a fluorine-containing dispersant, and 3.2 parts by mass of a hindered phenol-based antioxidant (molecular weight 775) as an antioxidant (8.0% by mass relative to 100% by mass of the total amount of the charge transport material) were added to 340.0 parts by mass of tetrahydrofuran and dissolved, and the mixture was treated 10 times with a high-pressure homogenizer to obtain a coating liquid for forming a charge transport layer. The obtained coating liquid for forming a charge transport layer was dip-coated on the charge generating layer.

[0639] During dip coating, the temperature of the coating liquid is set to 31°C, the rising speed of the coating liquid is 800 mm / min, the rising speed of the coated material (forming a substrate to the charge generating layer) is 300 mm / min, and the relative speed difference between the coating liquid and the coated material is 500 mm / min. Drying is performed at 150°C for 40 minutes to form a charge transport layer with a film thickness of 40 μm, which is used as an electronic photographic photosensitive body.

[0640] Table 4 shows the number of carboxyl groups in the fluorine-containing resin particles and the amount of triethylamine (boiling point 89° C.) as a basic compound, as measured by the above-mentioned method.

[0641] [Examples 20 to 29, Comparative Example 7]

[0642] Electrophotographic photoreceptors for each example were prepared in the same manner as in Example 19, except that the type and amount of fluorine-containing resin particles, the state of the outermost surface layer (N1 to N3, N2 / N1, S1, S2, S2 / S1, N3 / N1, D1, D2, and D2 / D1), the relative speed difference between the charge transport layer-forming coating liquid and the coated material (forming the substrate up to the charge generating layer), and the type and amount of the charge transport material were changed to the specifications shown in Tables 4 and 5. When two or more charge transport materials are used, the amount of charge transport material shown in Table 4 refers to the total amount of each charge transport material.

[0643] [Comparative Examples 5-6]

[0644] In Example 19, electrophotographic photoreceptors of various examples were prepared in the same manner as in Example 19, except that the coating liquid temperature was set to 15°C during formation of the charge transport layer. The types and amounts of fluorine-containing resin particles, the state of the outermost surface layer (N1 to N3, N2 / N1, S1, S2, S2 / S1, N3 / N1, D1, D2, and D2 / D1), the number of treatments in the high-pressure homogenizer, and the types and amounts of the charge transport materials were changed to the specifications shown in Tables 4 and 5. When two or more charge transport materials are used, the amounts of the charge transport materials shown in Table 4 refer to the total amounts of the individual charge transport materials.

[0645]

[0646] -Sensitivity Evaluation-

[0647] The sensitivity of the electrophotographic photoreceptor of each example was evaluated as the half-exposure when the electrophotographic photoreceptor was charged to +800 V. Specifically, the electrophotographic photoreceptor of each example was first charged to +800 V using an electrostatic paper tester (electrostatic analyzer EPA-8100, manufactured by Kawaguchi Electric Co., Ltd.) in an environment of 20°C and 40% relative humidity. The light from a tungsten lamp was then monochromated at 800 nm using a monochromator and the wavelength was set at 1 μW / cm. 2 The light intensity was adjusted in a certain way and irradiated onto the surface of the electrophotographic photoreceptor. The surface potential Vo (V) of the electrophotographic photoreceptor immediately after charging was measured. The half-exposure dose (μJ / cm 2 The obtained half-exposure values ​​were classified according to the following criteria. The results are shown in Table 5. If the sensitivity decreases, the image quality will decrease, resulting in image defects.

[0648] G1: Half-exposure: 0.10 μJ / cm 2 the following.

[0649] G2: Half-reduction exposure exceeds 0.10 μJ / cm 2 and 0.13 μJ / cm 2 the following.

[0650] G3: Half-reduction exposure exceeds 0.13 μJ / cm 2 and 0.15 μJ / cm 2 the following.

[0651] G4: Half-reduction exposure exceeds 0.15 μJ / cm 2 and 0.18 μJ / cm 2 the following.

[0652] G5: Half-reduction exposure exceeds 0.18 μJ / cm 2 .

[0653] -Evaluation of wear resistance-

[0654] The electrophotographic photoreceptors of each example were loaded into the black process cartridge of a DocuCentre-V C7776 color copier manufactured by Fuji Xerox Co., Ltd. A running test was then conducted in an environment with a temperature of 20°C and a humidity of 40%, where 100,000 sheets (100 kPV) of halftone images (i.e., an image density of 50%) were output. The amount of wear on the outermost surface of the electrophotographic photoreceptors was then measured using an eddy-current film thickness meter, based on the difference between the film thickness measured before and after the run. The results are shown in Table 5.

[0655] -Quantitative evaluation of dot-shaped image defects-

[0656] When the carbon fibers penetrate through the layers and reach the conductive matrix, current flows and dot-shaped image defects occur. This phenomenon is utilized to evaluate the suppression of leakage current.

[0657] The electrophotographic photoreceptor of each example was mounted in the black DocuCentre-V C7776. Then, using a developer containing 10 mg (0.1% by mass) of carbon fiber (MLD-30, manufactured by Toray Industries, Ltd.) mixed with the developer, 10 black images with a 15% image density were continuously output on A4 white paper. The number of dot-like image defects on the tenth sheet of paper was visually counted, and the results are shown in Table 5.

[0658] -Evaluation of charging performance-

[0659] The charging properties of the electrophotographic photoreceptor of each example were evaluated as follows.

[0660] The surface potential after charging was set to -700 V using an evaluation image forming apparatus. Then, 70,000 A4 sheets of a full-surface halftone image with a 30% image density were printed under a high-temperature, high-humidity environment (28°C, 85% RH). The surface potential was then measured using a surface potentiometer and evaluated according to the following criteria.

[0661] G1: Surface potential is above -700V and below -690V

[0662] G2: Surface potential is above -690V and less than -675V

[0663] G3: Surface potential is -675V or higher and less than -660V (a level that poses no practical problem)

[0664] G4: Surface potential is above -660V and below -640V

[0665] G5: Surface potential is -640V or above

[0666]

[0667] As shown in Table 5, the electrophotographic photoreceptors of Examples exhibit superior sensitivity and wear resistance compared to the electrophotographic photoreceptors of Comparative Examples. Furthermore, the electrophotographic photoreceptors of Examples exhibit significantly less leakage current than the electrophotographic photoreceptors of Comparative Examples, which can be caused by the incorporation of needle-shaped foreign matter, such as carbon fibers, into the developer.

[0668] Explanation of symbols

[0669] 1,101 Basecoat

[0670] 2,102 Charge generation layer

[0671] 3,103 Charge transport layer

[0672] 4,104 Conductive substrate

[0673] 7A, 7, 107A, 107B Electrophotographic photoreceptors

[0674] 8 Charging device

[0675] 9 Exposure device

[0676] 11 Development device

[0677] 13 Cleaning device

[0678] 14 Lubricant

[0679] 40 transfer device

[0680] 50 intermediate transfer body

[0681] 100 Image forming device

[0682] 120 Image forming device

[0683] 131 Cleaning Scraper

[0684] 132 Fibrous member (rolled)

[0685] 133 Fibrous member (flat brush shape)

[0686] 300 Processing Box

[0687] 105 photosensitive layer

[0688] 106 Surface protection layer.

Claims

1. An electrophotographic photoreceptor comprising a conductive substrate and a photosensitive layer, The outermost surface layer of the electrophotographic photoreceptor contains fluorine-containing resin particles, (1) the fluorine atom concentration at the surface of the outermost surface layer is 1.5 to 5.0 times the fluorine atom concentration at a depth of 1 μm from the surface of the outermost surface layer; or (2) the ratio N2 / N1 of the number density N1 of the aggregates of the fluorine-containing resin particles in the first region of the outermost layer from the surface to 1 / 2 of the layer thickness to the number density N2 of the aggregates of the fluorine-containing resin particles in the second region of the outermost layer from 1 / 2 of the layer thickness to the bottom surface of the outermost layer is less than 0.95, The ratio S2 / S1 of the area ratio S1 of the fluorine-containing resin particles in the first region from the surface to 1 / 2 of the layer thickness of the outermost layer to the area ratio S2 of the fluorine-containing resin particles in the second region from 1 / 2 of the layer thickness to the bottom surface of the outermost layer is within the range of 1±0.1, The aggregate of fluorine-containing resin particles is a group of primary particles of fluorine-containing resin particles with an inter-particle distance of 1 μm or less, wherein: When no particles exist within 1 μm around a primary particle, one primary particle is counted as one aggregate. Primary particles constituting the aggregate exist within a region of 1 μm from each other, and the aggregate is in any of the following states: contact with each other, adjacent to each other without contact, or a combination of the two. The photosensitive layer includes a charge generating layer and a charge transporting layer, or is a single-layer photosensitive layer containing a charge generating material and a charge transporting material to integrate their functions. When the photosensitive layer is a single-layer photosensitive layer, the single-layer photosensitive layer is regarded as either the charge generating layer or the charge transporting layer. The concentration of the charge transport material at the surface of the charge transport layer is 0.4 times or more and 0.6 times or less of the concentration of the charge transport material at the center of the thickness of the charge transport layer, The fluorine-containing resin particles occupy an area of ​​not less than 0.33% and not more than 1.1% of the surface area of ​​the outermost layer.

2. The electrophotographic photoreceptor according to claim 1, wherein The fluorine-containing resin particles occupy an area of ​​not less than 0.36% and not more than 0.95% of the surface area of ​​the outermost layer.

3. The electrophotographic photoreceptor according to claim 1 or 2, wherein The photosensitive layer has a charge generating layer and a charge transporting layer, The outermost surface layer is the charge transport layer.

4. The electrophotographic photoreceptor according to claim 3, wherein The concentration of the charge transport material at the surface of the charge transport layer is 0.45 times or more and 0.56 times or less of the concentration of the charge transport material at the center of the thickness of the charge transport layer.

5. The electrophotographic photoreceptor according to claim 1, wherein The ratio N2 / N1 is not less than 0.1 and not more than 0.

8.

6. The electrophotographic photoreceptor according to claim 1 or 5, wherein The ratio N3 / N1 of the number density N1 of the agglomerates of the fluorine-containing resin particles in the first region from the surface of the outermost surface layer to 1 / 2 of the layer thickness to the number density N3 of the agglomerates of the fluorine-containing resin particles in the third region from 9 / 10 of the layer thickness from the surface of the outermost surface layer to the bottom of the outermost surface layer is less than 0.

9.

7. The electrophotographic photoreceptor according to claim 6, wherein The ratio N3 / N1 is 0.7 or less.

8. The electrophotographic photoreceptor according to claim 1, wherein The ratio D2 / D1 of the average diameter D1 of the agglomerates of the fluorine-containing resin particles in the first region of the outermost surface layer from the surface to 1 / 2 of the layer thickness to the average diameter D2 of the agglomerates of the fluorine-containing resin particles in the second region of the outermost surface layer from 1 / 2 of the layer thickness to the bottom surface of the outermost surface layer is 2 or more.

9. The electrophotographic photoreceptor according to claim 8, wherein The ratio D2 / D1 is 3 or more and 30 or less.

10. The electrophotographic photoreceptor according to claim 1, wherein The number density N1 of the aggregates of the fluorine-containing resin particles in the first region of the outermost surface layer from the surface to 1 / 2 of the layer thickness is 5 particles / 100 μm 2 More than 50 / 100μm 2 the following.

11. The electrophotographic photoreceptor according to claim 1, wherein The number of carboxyl groups in the fluorine-containing resin particles is relative to 10 6 The number of carbon atoms is 0 to 30 both inclusive, and the amount of the basic compound in the fluorine-containing resin particles is 0 ppm to 3 ppm both inclusive.

12. The electrophotographic photoreceptor according to claim 11, wherein The number of carboxyl groups is relative to every 10 6 The number of carbon atoms is 0 to 20, and the amount of the basic compound is 0 ppm to 3 ppm.

13. A process cartridge comprising the electrophotographic photoreceptor according to any one of claims 1 to 12, It is configured to be attached to and detached from the image forming apparatus.

14. A process cartridge comprising the electrophotographic photoreceptor according to any one of claims 1 to 4, the process cartridge being configured to be attached to and detached from an image forming apparatus. The process cartridge includes a cleaning member configured to come into contact with the electrophotographic photoreceptor to clean the electrophotographic photoreceptor. The contact pressure of the cleaning member with respect to the electrophotographic photoreceptor is 1.0 g / mm or more and 4.0 g / mm or less.

15. An image forming apparatus comprising: The electrophotographic photoreceptor according to any one of claims 1 to 12; a charging mechanism configured to charge the surface of the electrophotographic photoreceptor; an electrostatic latent image forming mechanism configured to form an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing mechanism configured to develop the electrostatic latent image formed on the surface of the electrophotographic photoreceptor using a developer containing a toner to form a toner image; and The transfer mechanism is configured to transfer the toner image to a surface of a recording medium.

16. An image forming apparatus comprising: The electrophotographic photoreceptor according to any one of claims 1 to 4; a charging mechanism configured to charge the surface of the electrophotographic photoreceptor; an electrostatic latent image forming mechanism configured to form an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing mechanism configured to develop the electrostatic latent image formed on the surface of the electrophotographic photoreceptor using a developer containing a toner to form a toner image; a transfer mechanism configured to transfer the toner image to a surface of a recording medium; and a cleaning mechanism configured to clean the surface of the electrophotographic photoreceptor by bringing a cleaning member into contact with the surface of the electrophotographic photoreceptor; The contact pressure of the cleaning member with respect to the electrophotographic photoreceptor is 1.0 g / mm or more and 4.0 g / mm or less.

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