Image forming apparatus

Abstract

To provide an image formation device that can achieve both a prolonged life of a photoreceptor drum and a stable image characteristic over a long period.SOLUTION: A photoreceptor drum 10 contains an organic compound particle in a charge transport layer of a surface. In an arrangement of a cleaning blade 261 relative to the photoreceptor drum 10, when a contact point of the photoreceptor drum 10 with a tip of the cleaning blade 261 is P1, in the case where an angle formed with a tangent line L1 at the contat point P1 and a principal plane 261a including the contact point P1 in the cleaning blade 261 and extending to a rotation direction downstream side of the photoreceptor drum 10 from the contact point P1 is a blade angle (A), a vertically upper part from a cylinder center axis of the photoreceptor drum 10 is 0°, and a center angle of the contact point P1 when the rotation direction of the photoreceptor drum 10 is positive is a blade position (B), the blade angle (A) is 5°or more and less than 20°, and the blade position (B) is 5°or more and less than 30°.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to an electrophotographic image forming apparatus.

Background Art

[0002] In recent years, organic photoreceptors have been widely used in the photosensitive layers of electrophotographic photoreceptor drums (hereinafter simply referred to as photoreceptor drums). With the increase in the contact charging method by roller charging and the long life of copiers, it is essential to increase the mechanical strength of the surface of the photoreceptor drum and reduce the wear amount on the surface.

[0003] Regarding the problem of wear on the surface of such a photoreceptor drum, adding inorganic compound particles such as silica particles or alumina particles as fillers to the surface layer of the photoreceptor drum has been considered. That is, it is considered that the printing durability of the photoreceptor drum can be improved and a long life can be achieved by dispersing the filler in the surface layer. However, this method has become a hindrance due to problems caused by contact with peripheral members (such as poor cleaning in contact with the cleaning blade), and there are currently significant practical problems (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When inorganic compound particles are incorporated into the surface layer of a photoconductor drum, it is difficult to achieve both improved wear resistance and stable image formation over the long term. Increasing the strength of the surface layer of the photoconductor drum by incorporating inorganic compound particles to extend its lifespan makes it more difficult to refresh the surface of the photoconductor drum as wear resistance increases. As a result, when printing multiple copies of the same pattern, waste toner accumulates at the cleaning blade location in the printed area, and the toner fuses to the surface of the photoconductor drum in the accumulated area, causing a difference in the surface potential of the photoconductor drum. When printing a full-page half-image under these conditions, problems such as variations in image density occur.

[0006] This disclosure has been made in view of the above-mentioned problems, and aims to provide an image forming apparatus that can achieve both a longer lifespan for the photoreceptor drum and stable image characteristics over a long period of time. [Means for solving the problem]

[0007] To solve the above problems, the present invention provides an image forming apparatus comprising a photoreceptor drum and a cleaning blade positioned in contact with the surface of the photoreceptor drum, wherein the photoreceptor drum has a charge generating layer and a charge transport layer laminated in that order on a conductive support, and the charge transport layer contains a binder resin, a charge transport substance and inorganic compound particles, and in the arrangement of the cleaning blade with respect to the photoreceptor drum, when the contact point between the photoreceptor drum and the tip of the cleaning blade is defined as P1, the angle between the tangent L1 at this contact point P1 and the main surface of the cleaning blade that includes the contact point P1 and extends downstream from the contact point P1 in the rotational direction of the photoreceptor drum is defined as the blade angle (A), and when the vertically upward direction from the cylindrical central axis of the photoreceptor drum is defined as 0° and the rotational direction of the photoreceptor drum is defined as positive, the blade angle (A) is 5° or more and less than 20°, and the blade position (B) is 5° or more and less than 30°.

[0008] According to the above configuration, when inorganic compound particles are included as fillers in the charge transport layer to increase the mechanical strength of the photoreceptor drum surface, it is possible to achieve both a longer lifespan for the photoreceptor drum and stable image characteristics over a long period by appropriately adjusting the installation conditions of the cleaning blade (blade angle (A) and blade position (B)).

[0009] Furthermore, the image forming apparatus described above can be configured such that the blade angle (A) is 5° or more and less than 15°, and the blade position (B) is 5° or more and less than 20°.

[0010] Furthermore, the image forming apparatus described above can be configured such that the Young's modulus of the photosensitive layer is 4.6 to 5.5 GPa.

[0011] Furthermore, the image forming apparatus described above can be configured such that the ten-point average roughness Rz of the surface of the photoreceptor drum is 0.1 μm or more and 0.4 μm or less.

[0012] Furthermore, the image forming apparatus described above can be configured such that the standard deviation of the ten-point average roughness Rz in the circumferential direction at the center of the rotation axis of the photoreceptor drum is 0.010 or more and 0.100 or less.

[0013] Furthermore, the image forming apparatus can be configured to perform reverse rotation control, which reverses the rotation of the photoreceptor drum when not forming an image.

[0014] Furthermore, the image forming apparatus described above can be configured such that the water contact angle on the surface of the photoreceptor drum is 85° or greater.

[0015] Furthermore, the image forming apparatus described above can be configured such that the relationship 1 ≤ RzB / RzA ≤ 1.7 is satisfied when RzA and RzB are the ten-point average roughness of the central and edge portions of the charged region in the rotation axis direction of the photoreceptor drum, respectively.

[0016] Further, the image forming apparatus can be configured such that the elastic deformation work rate of the photosensitive layer, which is measured by applying a maximum pushing load of 30 mN for 5 seconds in an environment of a temperature of 25°C and a relative humidity of 50%, is 41% or more and 50% or less.

[0017] Further, the image forming apparatus can be configured to use a developer containing toner containing fatty acid metal salt particles.

Advantages of the Invention

[0018] The image forming apparatus of the present disclosure can achieve both a long life of the photosensitive drum and stable image characteristics over a long period by incorporating inorganic compound particles in the charge transport layer and appropriately adjusting the installation conditions of the cleaning blade.

Brief Description of the Drawings

[0019] [Figure 1] FIG. 1 is a schematic cross-sectional view schematically showing the configuration of the photosensitive drum 10 of the present disclosure. [Figure 2] FIG. 22 is an explanatory diagram showing the basic configuration of the image forming section in the image forming apparatus of the present disclosure. [Figure 3] FIG. 25 is a diagram for explaining the blade angle (A) and the blade position (B), and is a cross-sectional view in a plane orthogonal to the rotation axis of the photosensitive drum.

Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0021] <Configuration of the electrophotographic photosensitive drum> FIG. 1 is a schematic cross-sectional view schematically showing the configuration of the photosensitive drum 10 of the present disclosure.

[0022] The photosensitive drum 10 has an undercoat layer 12 provided on a conductive support 11, and a charge generation layer 13 and a charge transport layer 14 are provided thereon. Note that the photosensitive drum 10 is formed as a laminated photosensitive drum in which the undercoat layer 12, the charge generation layer 13, and the charge transport layer 14 are laminated in this order outward on a cylindrically formed conductive support 11. However, FIG. 1 shows an enlarged partial cross section along the circumferential direction.

[0023] The charge generation layer 13 and the charge transport layer 14 form a photosensitive layer in the photosensitive drum 10. The charge generation layer 13 contains a charge generating substance 131. The charge transport layer 14 contains a binder resin 141, a charge transport substance 142, and inorganic compound particles 143. In the photosensitive drum 10, since the conductive support 11, the undercoat layer 12, and the charge generation layer 13 can utilize known configurations, detailed descriptions thereof are omitted here.

[0024] The charge transport layer 14 is obtained by containing the charge transport substance 142 and the inorganic compound particles 143 in the binder resin 141, and the charge transport substance 142 has the ability to receive and transport the charges generated by the charge generating substance 131.

[0025] As the binder resin 141, polycarbonate resins and polyarylate resins well-known in the art, which are excellent in compatibility with the charge transport substance 142 and also excellent in electrical insulation, transparency, electrical properties, film properties, abrasion resistance, etc., are preferably used.

[0026] The charge transport material 142 can be any compound capable of transporting the charge generated in the charge generation layer 13, and various known compounds can be cited. For example, the charge transport material 142 can be carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolon derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, polycyclic aromatic compounds, indole derivatives, pyrazoline derivatives, oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, triarylmethane derivatives, phenylenediamine derivatives, stilbene derivatives, enamine derivatives, and aromatic amine derivatives. Furthermore, polymers having groups derived from these compounds in their main chain or side chains, such as poly-N-vinylcarbazole, poly-1-vinylpyrene, and poly-9-vinylanthracene, can also be listed as charge transport materials 142. These charge transport materials 142 can be used individually or in combination of two or more. Among these, the stilbene derivative, compound (1) represented by the following structural formula, is preferred in terms of electrical properties and light resistance. The stilbene derivative of compound (1) is preferred because it absorbs light in the wavelength range of 300 to 480 nm and has a wide absorption range as a charge transport material 142.

[0027] [ka]

[0028] In compound (1), R1, R2, R5, and R6 may be the same or different and represent an alkyl group, an alkoxy group, an aryl group, or an aralkyl group. m, n, p, and q may be the same or different and represent integers from 0 to 3. R3 and R4 may be the same or different and represent a hydrogen atom or an alkyl group. Such stilbene compounds can be synthesized by the method described in Japanese Patent No. 3272257. Preferred structures of the charge transport material 142 include the following compounds (1a) to (1c).

[0029] [ka]

[0030] [ka]

[0031] [ka]

[0032] The inorganic compound particles 143 are fine particles used to improve the abrasion resistance (print resistance) of the surface of the photoreceptor drum 10, and silica particles or alumina particles are preferably used. The content of inorganic compound particles 143 in the charge transport layer 14 is preferably 5.0 to 20.0% by weight, and more preferably 7.0 to 18.0% by weight, relative to the total solid content of the charge transport layer 14. If the content of inorganic compound particles 143 is less than 5.0% by weight, the effect on print resistance is insufficient, and if it exceeds 20.0% by weight, the electrical properties of the photoreceptor drum 10 may deteriorate.

[0033] The thickness of the charge transport layer 14 is preferably 15 μm to 45 μm, and more preferably 25 to 40 μm. If the thickness is less than 15 μm, the print resistance is insufficient, and if it exceeds 45 μm, the electrical characteristics of the photoreceptor drum 10 may deteriorate.

[0034] <Surface roughness and its variation in the charge transport layer> When silica particles are included as inorganic compound particles 143 in the charge transport layer 14, generally, the larger the particle size of the silica particles, the better the wear resistance of the charge transport layer 14. On the other hand, if the particle size of the silica particles is large, it can cause chipping of the edges of the cleaning blade. Therefore, by appropriately agglomerating relatively small silica particles, larger particles can be created, improving wear resistance while suppressing chipping of the cleaning blade. In other words, when the cleaning blade chips, the smaller silica particles peel off, making it less likely for the cleaning blade to be partially damaged.

[0035] The surface roughness of the charge transport layer 14 serves as an indicator of the aggregation state (dispersion state of silica particles) of silica particles in the charge transport layer 14. The ten-point average roughness Rz, as defined in JIS-B-0601 (1994), is the difference in μm between the average elevation of the top five peaks and the average elevation of the bottom five valleys, measured in a straight line parallel to the average line and not crossing the cross-sectional curve, and perpendicular to the average line, in a portion extracted by a standard length from the cross-sectional curve of the outermost surface layer (charge transport layer 14) of the photoreceptor drum 10.

[0036] The surface of the charge transport layer 14 preferably has a ten-point average roughness Rz of 0.08 to 1.2 μm, more preferably 0.1 to 0.5 μm, and even more preferably 0.1 to 0.4 μm.

[0037] A ten-point average roughness Rz of the charge transport layer 14 of less than 0.08 μm means that the particle size of the silica particles is small or that the silica content is low, and under these conditions, improvement in the mechanical strength of the charge transport layer 14 due to the silica particles may not be expected. On the other hand, if the ten-point average roughness Rz of the charge transport layer 14 exceeds 1.2 μm, the dispersion state of the silica particles in the charge transport layer 14 becomes insufficient, and stress cracks may easily occur on the surface of the photoreceptor drum 10 (i.e., the charge transport layer 14) due to prolonged friction with the cleaning blade.

[0038] Furthermore, the surface roughness of the charge transport layer 14 does not have to be constant along the rotation axis of the photoreceptor drum 10, but it is preferable that the variation in the ten-point average roughness Rz between the center and the edges is within a predetermined range. The coating liquid for the charge transport layer containing silica particles has high viscosity, making it difficult to form a uniform film, and the surface roughness tends to be greater at the edges compared to the center along the rotation axis of the photoreceptor drum 10.

[0039] If there are variations in surface roughness along the rotation axis of the photoreceptor drum 10, the load from the cleaning blade is more likely to be applied to points with greater surface roughness, making it easier for stress cracks to occur starting from those points. Therefore, it is necessary to minimize variations in the surface roughness of the photoreceptor drum 10 (controlling it within a predetermined range).

[0040] Specifically, when the ten-point average roughness of the 4 mm wide areas in the central part A and the edge B of the charged region in the charge transport layer 14 is RzA and RzB, 1 ≤ RzB / RzA ≤ 1.7 It is preferable that the relationship is satisfied. 1 ≤ RzB / RzA ≤ 1.3 It is preferable to satisfy the relationship.

[0041] <Toner> The toner used in the image forming apparatus of this disclosure preferably contains fatty acid metal salt particles in addition to inorganic compound particles 143 as an external additive. When the toner is externally additiveed with inorganic compound particles 143 such as silica particles, that is, when the surface layer of the toner contains silica particles, the mechanical strength of the toner can be increased against excessive electrical fatigue and chemical fatigue. On the other hand, externally adding inorganic compound particles 143 to the toner increases friction between the cleaning blade and the surface of the photoreceptor drum 10, which can lead to image defects due to stress cracks. By externally adding fatty acid metal salts together with silica particles to the toner, the load on stress cracks can be reduced.

[0042] Fatty acid metal salts enhance the lubricity of the photoreceptor drum 10 surface, but to achieve this effect, it is important to have the fatty acid metal salts present in the nip area between the photoreceptor drum 10 and the cleaning blade. Therefore, the fatty acid metal salts adhere relatively weakly to the toner, and their content in the toner is controlled. This allows for the supply of an appropriate amount of fatty acid metal salts between the photoreceptor drum 10 and the cleaning blade.

[0043] Examples of fatty acid metal salts used in fatty acid metal salt particles include zinc stearate, magnesium stearate, lithium stearate, calcium stearate, and aluminum stearate. Among these, zinc stearate and magnesium stearate are preferred, and zinc stearate is particularly preferred, due to their high effectiveness in improving the lubricity of the photoreceptor drum surface 10.

[0044] <Image forming apparatus> Figure 2 is an explanatory diagram showing the basic configuration of the image forming section in the image forming apparatus of the present disclosure. In the image forming section shown in Figure 2, a charging unit 21, an exposure unit 22, a developing unit 23, a transfer roller 24, a static elimination lamp 25, and a cleaning unit 26 are arranged around the photoreceptor drum 10 along the rotation direction of the photoreceptor drum 10 (direction of arrow R in the figure).

[0045] The charging unit 21 charges the surface of the photoreceptor drum 10 to a predetermined potential; for example, a scorotron charger is used. An output voltage (charging bias) from a charging bias power supply (not shown) is applied to the charging unit 21. The exposure unit 22 exposes the uniformly charged surface of the photoreceptor drum 10 by irradiating it with light corresponding to the image data output from an image processing unit (not shown). As a result, an electrostatic latent image corresponding to the image data is formed on the surface of the photoreceptor drum 10.

[0046] The developing unit 23 visualizes the electrostatic latent image formed on the photoreceptor drum 10 using toner, and includes a developing roller 231 positioned opposite the photoreceptor drum 10. An output voltage (developing bias) from a developing bias power supply (not shown) is applied to the developing roller 231.

[0047] The transfer roller 24 has a paper transport path (not shown in Figure 2) between it and the photoreceptor drum 10, allowing it to transport the incoming paper while pressing it against the photoreceptor drum 10. Furthermore, an output voltage (transfer bias) from a transfer bias power supply (not shown) is applied to the transfer roller 24, transferring the toner image on the photoreceptor drum 10 to the paper. The paper with the transferred toner image is then transported to a fuser unit (not shown) where the transferred toner image is fixed.

[0048] The static elimination lamp 25 irradiates the surface of the photoreceptor drum 10 with static elimination light to remove residual charge from the surface of the photoreceptor drum 10. The cleaning unit 26 removes residual toner from the surface of the photoreceptor drum 10 using a cleaning blade 261. The cleaning unit 26 also has a waste toner transport section that transports the residual toner (waste toner) removed by the cleaning blade 261.

[0049] As shown in Figure 2, in the image forming apparatus of this disclosure, the cleaning unit 26 is positioned above the photoreceptor drum 10. That is, the cleaning blade 261 is also positioned so as to contact the top of the photoreceptor drum 10. By positioning the cleaning blade 261 above the photoreceptor drum 10 in this way, the waste toner scraped off by the cleaning unit 26 is more likely to spread appropriately along the rotation axis of the photoreceptor drum 10, reducing accumulation only in the printed area. As a result, even when printing multiple copies of the same pattern, waste toner accumulation at the position corresponding to the printed area is suppressed, and image unevenness due to uneven distribution of accumulated toner can be suppressed. [Examples]

[0050] Examples 1 to 25 as image forming apparatus according to this disclosure, and comparative examples 1 to 6 for comparison were prepared and evaluation tests were conducted.

[0051] [Example 1] The photosensitive drum 10 shown in Figure 1 was created as follows.

[0052] Three parts by weight of titanium dioxide (manufactured by Ishihara Sangyo Co., Ltd., product name: Tybake TTO-D-1) and two parts by weight of copolymerized polyamide (nylon) (manufactured by Toray Industries, Inc., product name: Amiran CM8000) were added to 25 parts by weight of methyl alcohol and dispersed in a paint shaker for 8 hours to prepare 3 liters of a coating solution for the undercoat layer.

[0053] The conductive support 11 was immersed in the obtained undercoating solution and then removed. The resulting coating was then allowed to air dry to form an undercoating layer 12 with a thickness of 1 μm on the conductive support 11. In this procedure, the conductive support 11 used was a drum-shaped aluminum support with a diameter of 30 mm and a length of 255 mm.

[0054] Oxotitanylphthalocyanine (compound (2) represented by the structural formula below), to be used as charge generating material 131 in charge generating layer 13, was prepared as follows. First, 29.2 g of diiminoisoindoline and 200 ml of sulfolane were mixed, and then 17.0 g of titanium tetraisopropoxide was added, and the mixture was reacted at 140°C for 2 hours under a nitrogen atmosphere. After the resulting reaction mixture was allowed to cool, the precipitate was collected by filtration, washed sequentially with chloroform and 2% hydrochloric acid aqueous solution, and then sequentially with water and methanol, and dried to obtain 25.5 g of blue-violet crystals. Chemical analysis of the obtained compound confirmed that it was oxotitanylphthalocyanine, compound (2) (yield 88.5%).

[0055] [ka]

[0056] One part by weight of the obtained titanyl phthalocyanine and one part by weight of butyral resin (manufactured by Sekisui Chemical Co., Ltd., trade name: BM-2) were added to 98 parts by weight of methyl ethyl ketone and dispersed in a paint shaker for 2 hours to prepare 3 liters of coating solution for the charge generation layer.

[0057] The obtained charge generation layer coating solution was applied onto the base layer 12 using the same immersion method as in the case of base layer formation, and the resulting coating film was allowed to air dry to form a charge generation layer 13 with a thickness of 0.3 μm. The formation steps for the base layer 12 and the charge generation layer 13 were the same in all the examples and comparative examples described later.

[0058] Next, 70.0 g of silica particles (manufactured by Nippon Aerosil Co., Ltd., trade name: AEROSIL® R972, number mean primary particle size 16 nm, dimethyldichlorosilane surface treatment) as inorganic compound particles 143 were suspended in 390 g of tetrahydrofuran, 2 mm diameter glass beads were added, and the mixture was stirred in a ball mill for 15 hours, followed by dispersion in a paint shaker for 20 minutes, after which the glass beads were removed. To this, 210 g of compound (1) as charge transport material 142, 375 g of polycarbonate (manufactured by Teijin Chemicals Limited, trade name: TS2040) as binder resin 141, and 2400 g of tetrahydrofuran were further added and mixed. The resulting mixture was dispersed in 10 passes using a particle dispersion device (manufactured by Microfluidix, model: M-110P) and allowed to rest at 20°C for 24 hours to prepare the coating solution for the charge transport layer.

[0059] The obtained charge transport layer coating solution was applied onto the charge generation layer 13 using the same immersion method as in the case of forming the undercoat layer. The resulting coating film was dried at 120°C for 1 hour to form a charge transport layer 14 with a thickness of 32 μm.

[0060] In the photoreceptor drum 10 obtained as described above, the ten-point average roughness RzA in the center was 0.18 μm, the ten-point average roughness RzB at the edges was 0.2 μm, the value of RzB / RzA was 1.11, and the standard deviation of the circumferential ten-point average roughness Rz (standard deviation at the center of the rotation axis direction of the photoreceptor drum 10) was 0.015. The water contact angle on the surface of the photoreceptor drum 10 was 87°. The Young's modulus of the photosensitive layer (charge generation layer 13 and charge transport layer 14) was 4.8 GPa. The Young's modulus of the photosensitive layer was measured by applying a maximum pressing load of 30 mN to the surface of the photosensitive layer for 5 seconds under conditions of 25°C and 50% relative humidity, and the elastic deformation power at this time was 47%. The method for measuring Young's modulus was the same in other examples and comparative examples.

[0061] The photoreceptor drum 10 obtained in this manner was installed in a unit of a digital copier (manufactured by Sharp Corporation, model: MX-M3531) that had been modified for testing, and an evaluation test was conducted.

[0062] Specifically, a photoreceptor drum 10 was installed in this copier, and durability tests and image characteristics were evaluated. In the evaluation tests, under an environment of 20°C / 50% RR, the potential conditions were set so that the dark area potential (V0) and bright area potential (VL) of the photoreceptor drum 10 were V0 = -650 (V) and VH = -300 (V), respectively, and the initial potential of each photoreceptor drum 10 being evaluated was adjusted. The cleaning blade 261 was set to a blade angle (A) of 16° and a blade position (B) of 22°. The linear pressure of the blade was set to 200 mN / cm.

[0063] Figure 3 is a diagram illustrating the blade angle (A) and blade position (B), and is a cross-sectional view of the photoreceptor drum 10 in a plane perpendicular to the rotation axis. The blade angle (A) refers to the angle formed by the tangent line L1 at the point of contact P1 between the photoreceptor drum 10 and the main surface 261a of the cleaning blade 261, which includes the point of contact P1 and extends downstream from the point of contact P1 in the rotation direction of the photoreceptor drum 10. The blade position (B) refers to the center angle of the point of contact P1 in the cross-sectional view of Figure 3, where vertically upward from the cylindrical central axis of the photoreceptor drum 10 is defined as 0°, and the rotation direction of the photoreceptor drum 10 is defined as positive.

[0064] [Example 2] For the cleaning blade 261, the blade angle (A) was set to 12° and the blade position (B) to 10°. All other settings were the same as in Example 1.

[0065] [Example 3] For the cleaning blade 261, the blade angle (A) was set to 6°. All other settings were the same as in Example 1.

[0066] [Example 4] For the cleaning blade 261, the blade angle (A) was set to 18°. All other settings were the same as in Example 1.

[0067] [Example 5] For the cleaning blade 261, the blade position (B) was set to 5°. All other settings were the same as in Example 1.

[0068] [Example 6] For the cleaning blade 261, the blade position (B) was set to 28°. All other settings were the same as in Example 1.

[0069] [Example 7] In the preparation of the photoreceptor drum 10, the charge transport layer 14 was formed as follows. First, alumina microparticles (average particle size 31 nm) were used as inorganic compound particles 143. 210 g of compound (1) as charge transport material 142, 375 g of polycarbonate (Teijin Chemicals Limited, product name: TS2040) as binder resin 141, and 2400 g of tetrahydrofuran were added to 550 g of alumina microparticle slurry (15% solid content, THF solvent, manufactured by CI Chemicals Co., Ltd.) and mixed. The resulting mixture was subjected to a 10-pass dispersion treatment using a particle dispersion device (Microfluidix Corporation, model: M-110P) and left to rest at 20°C for 24 hours to prepare the coating solution for the charge transport layer. The procedure for forming the charge transport layer 14 using the coating solution for the charge transport layer was the same as in Example 1.

[0070] In the photoreceptor drum 10 obtained as described above, the ten-point average roughness RzA in the central part was 0.23 μm, the ten-point average roughness RzB at the edges was 0.25 μm, the RzB / RzA value was 1.09, and the standard deviation of the circumferential ten-point average roughness Rz was 0.015. The water contact angle on the surface of the photoreceptor drum 10 was 89°. Furthermore, the Young's modulus of the photosensitive layer (charge generation layer 13 and charge transport layer 14) was 5.0 GPa, and the elastic deformation power during Young's modulus measurement (measurement conditions were the same as in Example 1) was 50%.

[0071] Furthermore, the cleaning blade 261 was set to have a blade angle (A) of 16° and a blade position (B) of 22°, similar to Example 1.

[0072] [Example 8] In preparing the photoreceptor drum 10, the procedure was the same as in Example 1, except that the binder resin 141 used was changed to 375g of polycarbonate (manufactured by Teijin Chemicals Limited, product name: TS2020) to prepare the coating solution for the charge transport layer.

[0073] In the obtained photoreceptor drum 10, the ten-point average roughness RzA in the central part was 0.28 μm, the ten-point average roughness RzB at the edges was 0.3 μm, the RzB / RzA value was 1.07, and the standard deviation of the circumferential ten-point average roughness Rz was 0.015. The water contact angle on the surface of the photoreceptor drum 10 was 87°. Furthermore, the Young's modulus of the photosensitive layer (charge generation layer 13 and charge transport layer 14) was 4.6 GPa, and the elastic deformation power during Young's modulus measurement (measurement conditions were the same as in Example 1) was 47%.

[0074] Furthermore, the cleaning blade 261 was set to have a blade angle (A) of 12° and a blade position (B) of 10°, similar to Example 2.

[0075] [Example 9] In the preparation of the photoreceptor drum 10, the charge transport layer 14 was formed as follows. First, 130.0 g of silica particles (manufactured by Nippon Aerosil Co., Ltd., trade name: AEROSIL® R972, number mean primary particle size 16 nm, dimethyldichlorosilane surface treatment) as inorganic compound particles 143 were suspended in 720 g of tetrahydrofuran, 2 mm diameter glass beads were added, and the mixture was stirred in a ball mill for 15 hours, followed by dispersion in a paint shaker for 20 minutes, after which the glass beads were removed. To this, 210 g of compound (1) as charge transport material 142, 375 g of polyarylate (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name: E2700) as binder resin 141, and 2300 g of tetrahydrofuran were further added and mixed. The resulting mixture was dispersed in 10 passes using a particle dispersion device (manufactured by Microfluidix, Inc., model: M-110P) and allowed to rest at 20°C for 24 hours to prepare the coating solution for the charge transport layer. The procedure for forming the charge transport layer 14 using the coating solution for the charge transport layer was the same as in Example 1.

[0076] In the photoreceptor drum 10 obtained as described above, the ten-point average roughness RzA in the central part was 0.14 μm, the ten-point average roughness RzB at the edges was 0.15 μm, the RzB / RzA value was 1.07, and the standard deviation of the circumferential ten-point average roughness Rz was 0.015. The water contact angle on the surface of the photoreceptor drum 10 was 87°. Furthermore, the Young's modulus of the photosensitive layer (charge generation layer 13 and charge transport layer 14) was 5.4 GPa, and the elastic deformation power at the time of Young's modulus measurement (measurement conditions were the same as in Example 1) was 47%.

[0077] Furthermore, the cleaning blade 261 was set to have a blade angle (A) of 12° and a blade position (B) of 10°, similar to Example 2.

[0078] [Example 10] In preparing the photoreceptor drum 10, the procedure was the same as in Example 1, except that the number of dispersion treatments using a particle dispersion device (Microfluidix, Inc., Model: M-110P) was changed to 12 passes to prepare the coating solution for the charge transport layer.

[0079] In the obtained photoreceptor drum 10, the ten-point average roughness RzA in the central part was 0.11 μm, the ten-point average roughness RzB at the edges was 0.12 μm, the RzB / RzA value was 1.09, and the standard deviation of the circumferential ten-point average roughness Rz was 0.015. The water contact angle on the surface of the photoreceptor drum 10, the Young's modulus of the photosensitive layer, and the elastic deformation power were the same as in Example 1.

[0080] Furthermore, the cleaning blade 261 was set to have a blade angle (A) of 12° and a blade position (B) of 10°, similar to Example 2.

[0081] [Example 11] In preparing the photoreceptor drum 10, the procedure was the same as in Example 1, except that the number of dispersion treatments using a particle dispersion device (Microfluidix, Inc., Model: M-110P) was changed to 8 passes to prepare the coating solution for the charge transport layer.

[0082] In the obtained photoreceptor drum 10, the ten-point average roughness RzA in the central part was 0.44 μm, the ten-point average roughness RzB at the edges was 0.45 μm, the RzB / RzA value was 1.02, and the standard deviation of the circumferential ten-point average roughness Rz was 0.015. The water contact angle, Young's modulus of the photosensitive layer, and elastic deformation power of the surface of the photoreceptor drum 10 were the same as in Example 1.

[0083] Furthermore, the cleaning blade 261 was set to have a blade angle (A) of 12° and a blade position (B) of 10°, similar to Example 2.

[0084] [Example 12] In preparing the photoreceptor drum 10, the procedure was the same as in Example 1, except that the number of dispersion treatments using a particle dispersion device (Microfluidix, Inc., Model: M-110P) was changed to 15 passes to prepare the coating solution for the charge transport layer.

[0085] In the obtained photoreceptor drum 10, the ten-point average roughness RzA in the central part was 0.08 μm, the ten-point average roughness RzB at the edges was 0.08 μm, the RzB / RzA value was 1.00, and the standard deviation of the circumferential ten-point average roughness Rz was 0.015. The water contact angle, Young's modulus of the photosensitive layer, and elastic deformation power of the surface of the photoreceptor drum 10 were the same as in Example 1.

[0086] Furthermore, the cleaning blade 261 was set to have a blade angle (A) of 12° and a blade position (B) of 10°, similar to Example 2.

[0087] [Example 13] In preparing the photoreceptor drum 10, the procedure was the same as in Example 1, except that the number of dispersion treatments using a particle dispersion device (Microfluidix, Inc., Model: M-110P) was changed to 3 passes to prepare the coating solution for the charge transport layer.

[0088] In the obtained photoreceptor drum 10, the ten-point average roughness RzA in the central part was 1.1 μm, the ten-point average roughness RzB at the edges was 1.1 μm, the RzB / RzA value was 1.00, and the standard deviation of the circumferential ten-point average roughness Rz was 0.015. The water contact angle on the surface of the photoreceptor drum 10, the Young's modulus of the photosensitive layer, and the elastic deformation power were the same as in Example 1.

[0089] Furthermore, the cleaning blade 261 was set to have a blade angle (A) of 12° and a blade position (B) of 10°, similar to Example 2.

[0090] [Example 14] In preparing the photoreceptor drum 10, the procedure was the same as in Example 1, except that the stirring time using a ball mill was changed to 2 hours to prepare the coating solution for the charge transport layer.

[0091] In the obtained photoreceptor drum 10, the ten-point average roughness RzA in the central part was 0.18 μm, the ten-point average roughness RzB at the edges was 0.2 μm, the RzB / RzA value was 1.11, and the standard deviation of the circumferential ten-point average roughness Rz was 0.11. The water contact angle on the surface of the photoreceptor drum 10, the Young's modulus of the photosensitive layer, and the elastic deformation power were the same as in Example 1.

[0092] Furthermore, the cleaning blade 261 was set to have a blade angle (A) of 12° and a blade position (B) of 10°, similar to Example 2.

[0093] [Example 15] The creation of the photoreceptor drum 10 and the setting of the cleaning blade 261 were the same as in Example 1.

[0094] In the evaluation test of the photoreceptor drum 10, the only difference from Example 1 was that control was performed to rotate the photoreceptor drum 10 in reverse after the completion of the image forming process.

[0095] [Example 16] In preparing the photoreceptor drum 10, the procedure was the same as in Example 1, except that the inorganic compound particles 143 were replaced with 70.0 g of silica particles (manufactured by Nippon Aerosil Co., Ltd., product name: AEROSIL® NX130, number mean primary particle diameter 16 nm, HMDS surface treatment) to prepare the coating solution for the charge transport layer.

[0096] The characteristics of the obtained photoreceptor drum 10 were the same as in Example 1, except that the water contact angle on the surface of the photoreceptor drum 10 was 83°.

[0097] Furthermore, the cleaning blade 261 was set to have a blade angle (A) of 12° and a blade position (B) of 10°, similar to Example 2.

[0098] [Example 17] In preparing the photoreceptor drum 10, the procedure was the same as in Example 1, except that the amount of tetrahydrofuran was changed from 2400g to 2450g to prepare the coating solution for the charge transport layer.

[0099] In the obtained photoreceptor drum 10, the ten-point average roughness RzA in the central part was 0.15 μm, the ten-point average roughness RzB at the edges was 0.25 μm, the RzB / RzA value was 1.67, and the standard deviation of the circumferential ten-point average roughness Rz was 0.015. The water contact angle on the surface of the photoreceptor drum 10, the Young's modulus of the photosensitive layer, and the elastic deformation power were the same as in Example 1.

[0100] Furthermore, the cleaning blade 261 was set to have a blade angle (A) of 12° and a blade position (B) of 10°, similar to Example 2.

[0101] [Example 18] In preparing the photoreceptor drum 10, the procedure was the same as in Example 1, except that the amount of tetrahydrofuran was changed from 2400g to 2500g to prepare the coating solution for the charge transport layer.

[0102] In the obtained photoreceptor drum 10, the ten-point average roughness RzA in the central part was 0.15 μm, the ten-point average roughness RzB at the edges was 0.28 μm, the RzB / RzA value was 1.87, and the standard deviation of the circumferential ten-point average roughness Rz was 0.015. The water contact angle on the surface of the photoreceptor drum 10, the Young's modulus of the photosensitive layer, and the elastic deformation power were the same as in Example 1.

[0103] Furthermore, the cleaning blade 261 was set to have a blade angle (A) of 12° and a blade position (B) of 10°, similar to Example 2.

[0104] [Example 19] In preparing the photoreceptor drum 10, the preparation of the coating solution for the charge transport layer was the same as in Example 1, except that the amount of compound (1), which is the charge transport material 142, was changed to 220 g, and the amount of polycarbonate (manufactured by Teijin Chemicals Limited, product name: TS2040), which is one of the materials for the binder resin 141, was changed to 365 g.

[0105] In the obtained photoreceptor drum 10, the ten-point average roughness RzA in the central part was 0.2 μm, the ten-point average roughness RzB at the edges was 0.2 μm, the RzB / RzA value was 1.00, and the standard deviation of the circumferential ten-point average roughness Rz was 0.015. The water contact angle and Young's modulus of the photosensitive layer on the surface of the photoreceptor drum 10 were the same as in Example 1, but the elastic deformation power was 41%.

[0106] Furthermore, the cleaning blade 261 was set to have a blade angle (A) of 12° and a blade position (B) of 10°, similar to Example 2.

[0107] [Example 20] In preparing the photoreceptor drum 10, the preparation of the coating solution for the charge transport layer was the same as in Example 1, except that the amount of compound (1), which is the charge transport material 142, was changed to 200 g, and the amount of polycarbonate (manufactured by Teijin Chemicals Limited, product name: TS2040), which is one of the materials of the binder resin 141, was changed to 385 g.

[0108] In the obtained photoreceptor drum 10, the ten-point average roughness RzA in the central part was 0.2 μm, the ten-point average roughness RzB at the edges was 0.2 μm, the RzB / RzA value was 1.00, and the standard deviation of the circumferential ten-point average roughness Rz was 0.015. The water contact angle and Young's modulus of the photosensitive layer on the surface of the photoreceptor drum 10 were the same as in Example 1, but the elastic deformation power was 50%.

[0109] Furthermore, the cleaning blade 261 was set to have a blade angle (A) of 12° and a blade position (B) of 10°, similar to Example 2.

[0110] [Example 21] In preparing the photoreceptor drum 10, the preparation of the coating solution for the charge transport layer was the same as in Example 1, except that the amount of compound (1), which is the charge transport material 142, was changed to 230 g, and the amount of polycarbonate (manufactured by Teijin Chemicals Limited, product name: TS2040), which is one of the materials for the binder resin 141, was changed to 355 g.

[0111] In the obtained photoreceptor drum 10, the ten-point average roughness RzA in the central part was 0.2 μm, the ten-point average roughness RzB at the edges was 0.2 μm, the RzB / RzA value was 1.00, and the standard deviation of the circumferential ten-point average roughness Rz was 0.015. The water contact angle and Young's modulus of the photosensitive layer on the surface of the photoreceptor drum 10 were the same as in Example 1, but the elastic deformation power was 40%.

[0112] Furthermore, the cleaning blade 261 was set to have a blade angle (A) of 12° and a blade position (B) of 10°, similar to Example 2.

[0113] [Example 22] In preparing the photoreceptor drum 10, the preparation of the coating solution for the charge transport layer was the same as in Example 1, except that the amount of compound (1), which is the charge transport material 142, was changed to 190 g, and the amount of polycarbonate (manufactured by Teijin Chemicals Limited, product name: TS2040), which is one of the materials for the binder resin 141, was changed to 395 g.

[0114] In the obtained photoreceptor drum 10, the ten-point average roughness RzA in the central part was 0.2 μm, the ten-point average roughness RzB at the edges was 0.2 μm, the RzB / RzA value was 1.00, and the standard deviation of the circumferential ten-point average roughness Rz was 0.015. The water contact angle and Young's modulus of the photosensitive layer on the surface of the photoreceptor drum 10 were the same as in Example 1, but the elastic deformation power was 55%.

[0115] Furthermore, the cleaning blade 261 was set to have a blade angle (A) of 12° and a blade position (B) of 10°, similar to Example 2.

[0116] [Example 23] In the preparation of the photoreceptor drum 10, the charge transport layer 14 was formed as follows. First, 70.0 g of silica particles (manufactured by Nippon Aerosil Co., Ltd., trade name: AEROSIL® R972, number mean primary particle size 16 nm, dimethyldichlorosilane surface treatment) as inorganic compound particles 143 were suspended in 390 g of tetrahydrofuran, glass beads with a diameter of 2 mm were added, and the mixture was stirred in a ball mill for 15 hours, followed by dispersion in a paint shaker for 20 minutes, after which the glass beads were removed. To this, 240 g of compound (1) as charge transport material 142, 345 g of polycarbonate (manufactured by Teijin Chemicals Limited, trade name: TS2020) and 2300 g of tetrahydrofuran were added and mixed as binder resin 141.

[0117] The obtained mixture was subjected to a 10-pass dispersion treatment using a particle dispersion device (Microfluidix, Inc., Model: M-110P) and allowed to rest at 20°C for 24 hours to prepare the coating solution for the charge transport layer. The procedure for forming the charge transport layer 14 using the coating solution for the charge transport layer was the same as in Example 1.

[0118] In the photoreceptor drum 10 obtained as described above, the ten-point average roughness RzA in the central part was 0.18 μm, the ten-point average roughness RzB at the edges was 0.2 μm, the RzB / RzA value was 1.11, and the standard deviation of the circumferential ten-point average roughness Rz was 0.015. The water contact angle on the surface of the photoreceptor drum 10 was 87°. Furthermore, the Young's modulus of the photosensitive layer was 4.4 GPa, and the elastic deformation power was 47%.

[0119] Furthermore, the cleaning blade 261 was set to have a blade angle (A) of 12° and a blade position (B) of 10°, similar to Example 2.

[0120] [Example 24] In the preparation of the photoreceptor drum 10, the charge transport layer 14 was formed as follows. First, 70.0 g of silica particles (manufactured by Nippon Aerosil Co., Ltd., trade name: AEROSIL® R972, number mean primary particle size 16 nm, dimethyldichlorosilane surface treatment) as inorganic compound particles 143 were suspended in 390 g of tetrahydrofuran, glass beads with a diameter of 2 mm were added, and the mixture was stirred in a ball mill for 15 hours, followed by dispersion in a paint shaker for 20 minutes, after which the glass beads were removed. To this, 180 g of compound (1) as charge transport material 142, 405 g of polyarylate (manufactured by Mitsubishi Chemical Corporation, trade name: E2700) as binder resin 141, and 2500 g of tetrahydrofuran were further added and mixed.

[0121] The obtained mixture was subjected to a 10-pass dispersion treatment using a particle dispersion device (Microfluidix, Inc., Model: M-110P) and allowed to rest at 20°C for 24 hours to prepare the coating solution for the charge transport layer. The procedure for forming the charge transport layer 14 using the coating solution for the charge transport layer was the same as in Example 1.

[0122] In the photoreceptor drum 10 obtained as described above, the ten-point average roughness RzA in the central part was 0.018 μm, the ten-point average roughness RzB at the edges was 0.2 μm, the RzB / RzA value was 1.11, and the standard deviation of the circumferential ten-point average roughness Rz was 0.015. The water contact angle on the surface of the photoreceptor drum 10 was 87°. Furthermore, the Young's modulus of the photosensitive layer was 5.6 GPa, and the elastic deformation power was 47%.

[0123] Furthermore, the cleaning blade 261 was set to have a blade angle (A) of 12° and a blade position (B) of 10°, similar to Example 2.

[0124] [Example 25] The preparation of the photoreceptor drum 10 and the setting of the cleaning blade 261 were the same as in Example 1, but the toner used in the evaluation test was different from that of the other examples (and comparative examples). Specifically, in Example 25, a toner containing fatty acid metal salt particles was used as the toner used in the evaluation test. The method for producing a developer containing this toner is shown below.

[0125] (Manufacturing Example 1: Preparation of Amorphous Polyester Resin A) In a 5 L reaction vessel, 440 g (2.7 mol) of terephthalic acid, 235 g (1.4 mol) of isophthalic acid, 7 g (0.05 mol) of adipic acid, 554 g (8.9 mol) of ethylene glycol, and 0.5 g of tetrabutoxytitanate as a polymerization catalyst were added. The mixture was reacted at 210 °C under a nitrogen atmosphere for 5 hours while distilling off the water and ethylene glycol produced, and then reacted under reduced pressure of 5-20 mmHg for 1 hour.

[0126] Next, 103 g (0.54 mol) of trimellitic anhydride was added and reacted under atmospheric pressure for 1 hour. After that, the reaction was carried out under reduced pressure of 20-40 mmHg, and the resin was removed at the predetermined softening point. The recovered ethylene glycol amounted to 219 g (3.5 mol). After the obtained resin was cooled to room temperature, it was pulverized into particles. This was designated as amorphous polyester resin A.

[0127] Amorphous polyester resin A had a glass transition temperature (Tg) of 56°C, a softening temperature (Tm) of 135°C, an SP value of 11.0, an acid value of 37 mgKOH / g, and a hydroxyl value of 50 mgKOH / g.

[0128] (Manufacturing Example 2: Preparation of Crystalline Polyester Resin B) In a 5 L reaction vessel, 132 g (1.12 mol) of 1,6-hexanediol, 230 g (1.0 mol) of 1,10-decanedicarboxylic acid, and 3 g of tetrabutoxytitanate as a polymerization catalyst were added and the reaction was carried out at 210 °C under atmospheric pressure for 5 hours while distilling off the water produced. The reaction was then continued under reduced pressure of 5-20 mmHg, and the resin was removed when the acid value fell to 2 mg KOH / g or less. After the obtained resin was cooled to room temperature, it was pulverized into particles. This was designated as crystalline polyester resin B.

[0129] Crystalline polyester resin B had a melting point Tmp of 80°C, a softening point Tm of 88°C (Tm / Tmp = 1.1), and an SP value of 9.5.

[0130] (Manufacturing Example 3: Preparation of Large-Particle Silica S1) A silica sol was prepared by the sol-gel method, and the obtained silica sol was hydrophobicated with hexamethyldisilazane (HMDS) to obtain large-particle silica S1 with a number-average primary particle size of 100 nm.

[0131] (Manufacturing Example 4: Preparation of Resin-Coated Carrier) 0.375 parts by mass of coating resin 1 (silicone-based, manufactured by Shin-Etsu Chemical Co., Ltd., product name: room temperature drying methyl resin KR-240) and 0.375 parts by mass of coating resin 2 (manufactured by Shin-Etsu Chemical Co., Ltd., product name: room temperature drying methyl resin KR-251) were dissolved in 12 parts by mass of toluene. Further, 0.0375 parts by mass of conductive particles (conductive carbon black, manufactured by Cabot Corporation, product name: VULCAN XC-72) and 0.0225 parts by mass of a coupling agent (manufactured by Toray Dow Corning Ltd., product name: AY43-059) were added or dispersed to prepare 12.8 g of coating resin solution.

[0132] Using an immersion method, 12.8 parts by mass of coating resin liquid was used to coat the surface of 100 parts by mass of ferrite carrier core material with a volume-average particle size of 40 μm. Subsequently, a curing process was carried out at a curing temperature of 200°C for a curing time of 1 hour, and the resin-coated carrier was prepared by passing it through a sieve with a mesh size of 150 μm.

[0133] (Toner preparation) [Material mixing, kneading, grinding, and classification processes] Binding resin 1: Amorphous polyester resin A (manufactured according to manufacturing example 1)...80% by mass Binding resin 2: Crystalline polyester resin B (manufactured in manufacturing example 2)...8% by mass Coloring agent: Coloring agent (CIPigment Blue 15:3, manufactured by DIC Corporation)...6% by mass Release agent: Monoester wax (manufactured by NOF Corporation, product name: WEP-3)...5% by mass Charge control agent: Salicylic acid compound (Orient Chemical Industry Co., Ltd., product name: Bontron E-84)...1% by mass The above materials were pre-mixed for 5 minutes using an air-flow mixer (Henschel mixer, manufactured by Mitsui Mining Co., Ltd. (now Nippon Coke Industries Co., Ltd.), model: FM20C), and then melt-kneaded using an open-roll continuous kneader (manufactured by Mitsui Mining Co., Ltd. (now Nippon Coke Industries Co., Ltd.), model: MOS320-1800) to obtain a molten kneaded product.

[0134] The open roll settings were as follows: heating roll supply temperature 130°C, discharge temperature 100°C; cooling roll supply temperature 40°C, discharge temperature 25°C. Both the heating and cooling rolls used had a diameter of 320 mm and an effective length of 1550 mm, with a roll gap of 0.3 mm on both the supply and discharge sides. The heating roll rotation speed was set to 75 rpm, the cooling roll rotation speed to 65 rpm, and the toner material supply rate to 5.0 kg / h.

[0135] The obtained molten mixture was cooled with a cooling belt and then coarsely ground using a speed mill with a φ2 mm screen. The obtained coarsely ground material was finely ground using a jet-type pulverizer (manufactured by Nippon Pneumatic Mfg. Co., Ltd., model: IDS-2) to obtain finely ground material [fine grinding step]. Next, the obtained finely ground material was classified using an elbow jet classifier (manufactured by Nippon Steel Mining Co., Ltd., model: EJ-LABO) to obtain toner matrix particles [classification step]. The number-average primary particle diameter of the obtained toner matrix particles was 6.7 μm, and the ultrafine powder content was 5% by mass.

[0136] [External addition process] 100 parts by mass of the obtained toner matrix particles, 1.0 part by mass of large particle size silica S1 (manufactured in Manufacturing Example 3) as large particle size silica, and 1.0 part by mass of small particle size silica particles (manufactured by Nippon Aerosil Co., Ltd., product name: AEROSIL® R976, number average primary particle size 7 nm, dimethyldichlorosilane surface treatment) were put into an airflow mixer (Henschel mixer, manufactured by Mitsui Mining Co., Ltd. (now Nippon Coke Industries Co., Ltd.), model: FM20C), the tip speed of the stirring blades was set to 40 m / sec, and the mixture was stirred for 4 minutes.

[0137] Next, 0.2 parts by mass of zinc stearate nanoparticles (number average primary particle size 0.7 μm, manufactured by NOF Corporation, product name: Nissan Electrol® MZ-2) as aliphatic metal salt particles were added to an air mixer, the tip speed of the stirring blades was set to 40 m / sec, and the mixture was stirred for 2 minutes to obtain an external toner.

[0138] The amount of ultrafine powder in the obtained externally added toner was 20%, and the amount of ultrafine powder in the toner after the external additive adhesion strength test was 5%. Furthermore, zinc stearate microparticles had a non-adhesion rate of 60% and a strong adhesion rate of 10%, while silica (sum of large-diameter silica and small-diameter silica) had a non-adhesion rate of 3% and a strong adhesion rate of 65%.

[0139] [Developer manufacturing process] The obtained external toner and the resin-coated carrier (manufactured in Manufacturing Example 4) were mixed so that the concentration of the external toner relative to the total amount of the two-component developer was 7% by mass, thereby obtaining a two-component developer with a toner concentration of 7%.

[0140] Furthermore, the developers used in the evaluation tests of Examples 1-24 and Comparative Examples 1-6 were manufactured in the same manner as described above, except that aliphatic metal salt particles were not added to the toner.

[0141] [Comparative Example 1] For the cleaning blade 261, the blade angle (A) was set to 4°. All other settings were the same as in Example 2.

[0142] [Comparative Example 2] For the cleaning blade 261, the blade angle (A) was set to 22°. All other settings were the same as in Example 2.

[0143] [Comparative Example 3] For the cleaning blade 261, the blade position (B) was set to 0°. All other settings were the same as in Example 2.

[0144] [Comparative Example 4] For the cleaning blade 261, the blade position (B) was set to 35°. All other settings were the same as in Example 2.

[0145] [Comparative Example 5] In the preparation of the photoreceptor drum 10, the charge transport layer 14 was formed as follows. Inorganic compound particles 143 were not used. Instead, 210 g of compound (1) as the charge transport material 142, 375 g of polycarbonate (manufactured by Teijin Chemicals Ltd., product name: TS2040) as the binder resin 141, and 2550 g of tetrahydrofuran were added. After stirring and mixing in a ball mill for 15 hours, the mixture was allowed to settle at 20°C for 24 hours to prepare the coating solution for the charge transport layer. The procedure for forming the charge transport layer 14 using the coating solution for the charge transport layer was the same as in Example 1.

[0146] In the photoreceptor drum 10 obtained as described above, the ten-point average roughness RzA in the central part was 0.08 μm, the ten-point average roughness RzB at the edges was 0.09 μm, the RzB / RzA value was 1.13, and the standard deviation of the circumferential ten-point average roughness Rz was 0.015. The water contact angle on the surface of the photoreceptor drum 10 was 87°. Furthermore, the Young's modulus of the photosensitive layer was 4.8 GPa, and the elastic deformation power was 47%.

[0147] Furthermore, the cleaning blade 261 was set to have a blade angle (A) of 16° and a blade position (B) of 22°, similar to Example 1.

[0148] [Comparative Example 6] In the preparation of the photoreceptor drum 10, the charge transport layer 14 was formed as follows. In Comparative Example 6, fluororesin microparticles (PTFE) were used instead of inorganic compound particles 143 as filler species to be contained in the charge transport layer 14. 4.8 g of tetrafluoroethylene resin microparticles (Lubron L-2: manufactured by Daikin Industries, Ltd.) having a number-average primary particle size of approximately 0.2 μm were heat-treated in an oven at 150°C for 30 min. These fluororesin microparticles, along with 0.34 g of a fluorine-based dispersant (GF-400: manufactured by Toagosei Co., Ltd.) and 25.5 g of tetrohydrofuran, were placed in a polypropylene container and mixed, and stirred for 30 hours using a stirrer (Shibata Scientific Co., Ltd., model: M-103) and stirring blades.

[0149] To this, 15.3 g of compound (1) as charge transport material 142, 27.6 g of polycarbonate resin (TS2050: manufactured by Teijin Chemicals Ltd.) as binder resin 141, 0.0031 g of silicone oil, and 126.5 g of tetrohydrofuran were mixed to prepare a suspension with a solid content of 24% by mass. Subsequently, the suspension was passed through a wet emulsification and dispersion apparatus (M-110P: manufactured by Microfluidizer Co., Ltd.) five times under a set pressure of 100 MPa. This prepared 200 g of coating solution for the charge transport layer.

[0150] Next, the charge transport layer coating solution was applied to the surface of the charge generation layer 13 by immersion coating. Specifically, the obtained charge transport layer coating solution was filled into a coating tank, and the conductive support 11, on which the pre-prepared undercoat layer 12 and charge generation layer 13 had been formed, was immersed in the coating solution and then removed. After that, the charge transport layer coating solution was dried at 130°C for 90 minutes. This formed a charge transport layer 14 with a thickness of 32 μm on the charge generation layer 13.

[0151] In the photoreceptor drum 10 obtained as described above, the ten-point average roughness RzA in the central part was 0.12 μm, the ten-point average roughness RzB at the edges was 0.14 μm, the RzB / RzA value was 1.17, and the standard deviation of the circumferential ten-point average roughness Rz was 0.015. The water contact angle on the surface of the photoreceptor drum 10 was 87°. Furthermore, the Young's modulus of the photosensitive layer was 4.8 GPa, and the elastic deformation power was 47%.

[0152] Furthermore, the cleaning blade 261 was set to have a blade angle (A) of 16° and a blade position (B) of 22°, similar to Example 1.

[0153] Tables 1 and 2 below show a list of the characteristics of the photoreceptor drum 10 and the setting conditions of the cleaning blade 261 in the evaluation tests for Examples 1 to 25 and Comparative Examples 1 to 6 described above.

[0154] [Table 1]

[0155] [Table 2]

[0156] <Rating> Each of the photoreceptor drums 10 from Examples 1-25 and Comparative Examples 1-6 was installed in a digital copier unit (Sharp Corporation, model: MX-M3531) modified for testing, and durability tests (print resistance tests) were conducted under normal temperature / humidity conditions (temperature 25°C / relative humidity 50%) to evaluate image uniformity, cleanability, blade reversal, and print resistance.

[0157] [Image unevenness] After outputting 3000 consecutive pattern images having a printed area A and a non-printed area B, one full-screen halftone image was output. For this halftone image, the reflectance density (D1) of the area corresponding to printed area A and the reflectance density (D0) of the area corresponding to non-printed area B were measured, and the density difference ΔD (D1-D0) was calculated. Based on the calculated density difference ΔD, the degree of image density unevenness was evaluated in four stages: ◎ (Excellent), ○ (Good), △ (Acceptable), and × (Unacceptable). The evaluation criteria are shown below.

[0158] (Judgment criteria) ◎: ΔD is less than 0.1 ○: ΔD is 0.1 or greater and less than 0.3 △: ΔD is 0.3 or greater and less than 0.5 ×: ΔD is 0.5 or greater [Cleaning properties] To confirm the level of cleaning defects occurring in the photoreceptor drum 10 after the print durability test, the photoreceptor drum 10, which had formed 350,000 images, was set in a digital copier, one 100% density untransferred image was printed on A4 paper, the image forming apparatus was forcibly stopped immediately afterward, and the surface of the photoreceptor drum 10 was visually observed to evaluate the degree of cleaning defects based on the following evaluation criteria.

[0159] (Judgment criteria) ◎: No cleaning defects were found. ○: There are 1-2 streaks in the sub-scanning direction due to poor cleaning (this level of streaking is not a problem for use with multifunction devices or printers that do not require high image quality). △: Due to a cleaning error, there are approximately 3-5 streaks in the sub-scanning direction (this level of streaking is acceptable for inexpensive multifunction printers or printers). ×: Due to poor cleaning, there are numerous streaks in the sub-scanning direction (a level that causes problems in actual use).

[0160] [Blade Reversal] We checked whether blade reversal would occur before 350,000 sheets of printing were completed. Blade reversal refers to the phenomenon in which the tip of the cleaning blade 261 bends backward in the direction of rotation of the photoreceptor drum 10, due to increased friction at the contact point between the cleaning blade 261 and the photoreceptor drum 10.

[0161] [Print durability] A print durability test was conducted by printing on 350,000 sheets of recording paper. The thickness (film thickness) of the photosensitive layer (charge generation layer 13 and charge transport layer 14) was measured using a film thickness measuring device (Filmetrics, model: F-20-EXR) at the start of the print durability test and after 350,000 images had been formed.

[0162] The film thickness at the start of the print durability test and the film thickness after 350,000 image formations were used to determine the film wear amount (μm / 100KTurn) per 100,000 rotations of the photoreceptor drum 10. The print durability was then evaluated based on the obtained film wear amount according to the following criteria. A higher film wear amount was considered to indicate poorer print durability.

[0163] (Judgment criteria) ◎: Film peeling amount < 1.00 (A level at which it can be used without problems even in multifunction devices or printers that require a long lifespan). ○: 1.00 ≤ film wear amount < 1.10 (This level is sufficient for use in multifunction devices or printers that do not require a long lifespan). △: 1.10 ≤ film wear amount < 1.20 (This level is sufficient for use with inexpensive multifunction printers or printers). Although the amount of material removed is large ×: Film peeling amount ≥ 1.20 (a level that poses a problem in practical use).

[0164] (Overall assessment) ◎: All items received an ◎ rating, indicating excellent performance. ○: While some items receive a ○ rating, all items receive a ○ rating or higher, and it can be used without problems unless it is a high-resolution multifunction printer or printer. △: The device has a △ rating in at least one category, but all categories have a △ rating or higher, and an inexpensive multifunction printer or printer can be used without problems. ×: One of the items has an "×" rating and is unusable.

[0165] Tables 3 and 4 below show a summary of the evaluation results for Examples 1 to 25 and Comparative Examples 1 to 6.

[0166] [Table 3]

[0167] [Table 4]

[0168] <Consideration> [Regarding blade angle (A) and blade position (B)] Regarding the blade angle (A), it is preferable to set it to 5° or more and less than 20°, as seen in Examples 1, 3, and 4 and Comparative Examples 1 and 2. If the blade angle (A) is less than 5° (in Comparative Example 1: cleaning performance evaluation is ×), the scraping force of the cleaning blade 261 decreases, making it easier for cleaning defects (slippage) to occur as toner passes through the cleaning blade 261. Also, if the blade angle (A) is 20° or more (in Comparative Example 2: blade reversal occurs), the frictional force between the photoreceptor drum 10 and the cleaning blade 261 increases, making blade reversal more likely.

[0169] Furthermore, the blade angle (A) is a factor that greatly affects cleaning performance. Comparing Examples 1, 3, and 4, the cleaning performance of Examples 1 and 4 was rated as excellent (◎), while that of Example 3 was rated as fair (△). In Example 2, although the blade position (B) setting differs from Examples 1, 3, and 4 and Comparative Examples 1 and 2, the optimal result was obtained with a blade angle (A) of 12°. Therefore, it is more preferable for the blade angle (A) to be between 10° and 20°.

[0170] Furthermore, regarding the blade position (B), it is preferable to set it to 5° or more and less than 30°, as seen in Examples 1, 5, and 6 and Comparative Examples 3 and 4. If the blade position (B) is less than 5° (in Comparative Example 3: blade reversal occurs), waste toner excessively accumulates or packs in the cleaning section, and the toner excessively enters the gap between the cleaning blade 261 and the surface of the photoreceptor drum 10, reducing lubrication and making blade reversal more likely. Also, if the blade position (B) is 30° or more (in Comparative Example 4: image unevenness evaluation is ×), image unevenness occurs due to toner accumulation on the printed area.

[0171] Furthermore, the blade position (B) is a factor that has a significant impact on image uniformity. Comparing Examples 1, 5, and 6, Example 1 received a ○ rating for image uniformity, Example 5 received a ◎ rating for image uniformity, and Example 6 received a △ rating for cleaning performance. Therefore, it is more preferable for the blade position (B) to be between 5° and 20°.

[0172] [Regarding Young's modulus and elastic deformation power] Based on Examples 2, 8, 9, 23, and 24, the Young's modulus of the photoreceptor drum 10 is preferably in the range of 4.6 to 5.5 Gpa. In the photoreceptor drum 10, a low Young's modulus reduces print durability, while a high Young's modulus reduces cleaning performance. Specifically, a low Young's modulus indicates low rigidity of the photoreceptor drum 10, leading to increased film abrasion and reduced print durability. Conversely, if the Young's modulus is too high, the rigidity of the photoreceptor drum 10 is too high, resulting in almost no film abrasion and reduced cleaning performance.

[0173] Furthermore, regarding the elastic deformation power (measured by applying a maximum pressing load of 30 mN to the surface of the photoreceptor drum 10 for 5 seconds under conditions of 25°C and 50% relative humidity), it is preferable that it be in the range of 41% to 50% based on Examples 2, 19 to 22.

[0174] When the elastic deformation power of the photoreceptor drum 10 is low, it becomes plastic, making it difficult to remove deposits such as discharge products attached to the outermost surface. This is thought to be because when the outermost layer becomes plastic, it becomes difficult to elastically deform, resulting in a low contact area with the cleaning blade 261, which is used as a cleaning means, and thus making it difficult to achieve cleaning performance. On the other hand, if the elastic deformation power is too high, the photoreceptor drum 10 is easily deformed, leading to the problem of excessive film abrasion.

[0175] [Regarding the average roughness of the photosensitive drum surface at 10 points] Based on Examples 2, 10 to 13, the ten-point average roughness Rz of the surface of the photoreceptor drum 10 is preferably 0.08 μm or more and 1.2 μm or less, more preferably 0.1 μm or more and 0.5 μm or less, and even more preferably 0.1 μm or more and 0.4 μm or less.

[0176] When the ten-point average roughness Rz is small (for example, less than 0.08 μm), it means that the particle size of the silica particles is small or that the silica content is low, and under these conditions, improvement in the mechanical strength of the charge transport layer by the silica particles may not be expected. On the other hand, when the ten-point average roughness Rz is large (for example, greater than 1.2 μm), the dispersion state of the silica particles in the charge transport layer becomes insufficient, the frictional force with the cleaning blade 261 increases, and the cleaning blade 261 is excessively worn down, reducing cleaning performance and making cleaning failures more likely (in the worst case, the friction between the cleaning blade 261 and the surface of the photoreceptor drum 10 increases, causing stress cracks).

[0177] Furthermore, the ratio of the ten-point average roughness RzA at the center to the ten-point average roughness RzB at the edges (RzB / RzA) is preferably 1 ≤ RzB / RzA ≤ 1.7, and preferably 1 ≤ RzB / RzA ≤ 1.3.

[0178] If the surface roughness of the photosensitive drum 10 is uneven (i.e., the RzB / RzA value is large), waste toner tends to accumulate unevenly in the areas of the photosensitive layer with greater surface roughness, which can cause image unevenness.

[0179] Furthermore, the standard deviation of the ten-point average roughness Rz in the circumferential direction of the photoreceptor drum 10 is preferably 0.010 or more and 0.100 or less, as seen in Examples 2 and 14.

[0180] A large standard deviation of the circumferential average roughness Rz indicates that the circumferential average roughness Rz is non-uniform. When the circumferential average roughness Rz is not uniform (0.010 or higher), the deformation of the cleaning blade 261 as it passes is released, which suppresses the vibration of the cleaning blade 261 associated with the release, and further uniformizes the behavior of the cleaning blade 261. This improves the uniformity of the abrasion state between the cleaning blade 261 and the photoreceptor drum 10. However, if the standard deviation of the circumferential average roughness Rz is too large (0.100 or higher), the frictional force between the photoreceptor drum 10 and the cleaning blade 261 increases, reducing print durability.

[0181] [Regarding the water contact angle on the surface of the photoreceptor drum] Based on Examples 2 and 14, it is preferable that the water contact angle on the surface of the photoreceptor drum 10 be 85° or higher. If the water contact angle is 84° or lower, the release properties of the toner on the photoreceptor drum 10 will be poor during cleaning, resulting in reduced cleaning performance.

[0182] [Regarding reverse rotation control of the photosensitive drum] By performing reverse rotation control to rotate the photoreceptor drum 10 in the reverse direction after the image formation process is completed (i.e., when not forming an image), the contact area between the photoreceptor drum 10 and the cleaning blade 261 can be moved to the upstream side in the forward rotation direction of the photoreceptor drum 10. This reverse rotation control is particularly effective in improving image uniformity (from Examples 1 and 15).

[0183] By performing reverse rotation control, the contact area between the photoreceptor drum 10 and the cleaning blade 261 can be moved to the upstream side in the forward rotation direction of the photoreceptor drum 10. This loosens and makes it easier to collect waste toner accumulated in the contact area, thereby suppressing image unevenness. Furthermore, since the pressure between the photoreceptor drum 10 and the cleaning blade 261 is released during reverse rotation control, it is thought that this also has the effect of improving print durability.

[0184] [Regarding the use of toner containing fatty acid metal salt particles] By using a toner containing fatty acid metal salt particles in the developer, the lubricity of the photoreceptor drum 10 surface can be improved. A comparison of Examples 1 and 25 shows that this reverse rotation control improves the evaluation of image uniformity and print durability. In other words, by improving the lubricity of the photoreceptor drum 10 surface, toner fusion on the surface of the photoreceptor drum 10 becomes less likely, and image uniformity is less likely to occur. In addition, by reducing friction between the photoreceptor drum 10 and the cleaning blade 261, print durability is improved.

[0185] The embodiments disclosed herein are illustrative in all respects and are not intended to be restrictive. Therefore, the technical scope of this disclosure is not construed solely by the embodiments described above, but is defined by the claims. This includes all modifications within the meaning and scope of the equivalents of the claims. [Explanation of symbols]

[0186] 10 Photoconductor drum 11 Conductive support 12. Lower layer 13 Charge generation layer 131 Charge-generating materials 14 Charge transport layer 141 Binder resin 142 Charge transport materials 143 Inorganic compound particles 21 Charging Units 22 Exposure Unit 23 Developing Unit 231 Developing Roller 24 Transfer Rollers 25 Static Elimination Lamp 26 Cleaning Unit 261 Cleaning Blade

Claims

1. An image forming apparatus comprising a photoreceptor drum and a cleaning blade positioned in contact with the surface of the photoreceptor drum, The photoreceptor drum has a charge generation layer and a charge transport layer, which form the photosensitive layer, laminated in this order on a conductive support, and the charge transport layer contains a binder resin, a charge transport substance, and inorganic compound particles. The ten-point average roughness RzA of the central part of the surface of the photoreceptor drum in the direction of rotation is 0.1 μm or more and 0.18 μm or less. When RzB is the ten-point average roughness of the edge of the charged region in the rotation axis direction of the photoreceptor drum, 1 ≤ RzB / RzA ≤ 1.3 And, The standard deviation of the ten-point mean roughness Rz in the circumferential direction at the center of the rotation axis of the photoreceptor drum is 0.010 or more and 0.100 or less. In the arrangement of the cleaning blade with respect to the photoreceptor drum, when the contact point between the photoreceptor drum and the tip of the cleaning blade is defined as P1, the angle between the tangent L1 at this contact point P1 and the main surface of the cleaning blade that includes the contact point P1 and extends downstream from the contact point P1 in the rotational direction of the photoreceptor drum is defined as the blade angle (A), and when the vertically upward direction from the cylindrical central axis of the photoreceptor drum is defined as 0° and the rotational direction of the photoreceptor drum is defined as positive, the central angle of the contact point P1 is defined as the blade position (B). An image forming apparatus characterized in that the blade angle (A) is 5° or more and less than 15°, and the blade position (B) is 5° or more and less than 20°.

2. An image forming apparatus according to claim 1, An image forming apparatus characterized in that the Young's modulus of the photosensitive layer is 4.6 to 5.5 GPa.

3. An image forming apparatus according to claim 1, An image forming apparatus characterized by performing reverse rotation control to rotate the photoreceptor drum in the reverse direction when not forming an image.

4. An image forming apparatus according to claim 1, An image forming apparatus characterized in that the water contact angle on the surface of the photoreceptor drum is 85° or more.

5. An image forming apparatus according to claim 1, An image forming apparatus characterized in that the elastic deformation power of the photosensitive layer, measured by applying a maximum indentation load of 30 mN for 5 seconds in an environment with a temperature of 25°C and a relative humidity of 50%, is 41% or more and 50% or less.

6. An image forming apparatus according to claim 1, An image forming apparatus characterized by using a developer containing a toner that contains fatty acid metal salt particles.

Images