Electrophotographic photoreceptor, process cartridge and electrophotographic device

Abstract

To provide an electrophotographic photoreceptor that achieves suppression of both toner slipping and toner fusion in a high temperature and high humidity environment.SOLUTION: On a photoreceptor having wrinkles in an outer surface, square observation areas of one side 300 μm are placed which take, as center points, 76 intersections of 19 line segments dividing the outer surface into 20 equal parts in an axial direction and four line segments dividing the outer surface into four equal parts in a circumferential direction, and when a line passing through the center point and parallel to the circumferential direction is a first reference line L1, and reference lines obtained by rotating the L1 by 0.1° are L2-L1800, a linear shape part parallel to any one of L1-L150 and L1651-L1800 and having a length of 50 μm or more is present in a convex part of the wrinkle. Each of L1-L1800 intersects with the convex part at a plurality of portions, and at least two of the portions have intersection angles different from each other. When frequency analysis is performed on height information on the wrinkle to obtain a two-dimensional power spectrum, a one-dimensional radial distribution function has at least one maximum value. When an angle distribution is calculated from the spectrum at a frequency of the maximum value, a power value has a specific relationship.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an electrophotographic photoreceptor, a process cartridge having the electrophotographic photoreceptor, and an electrophotographic apparatus.

Background Art

[0002] As an electrophotographic photoreceptor mounted in a process cartridge and an electrophotographic apparatus, an electrophotographic photoreceptor containing an organic photoconductive substance (charge generating substance) is used. In recent years, longer-life electrophotographic apparatuses have been demanded, and therefore, it has been desired to provide an electrophotographic photoreceptor with improved image quality and abrasion resistance (mechanical durability).

[0003] As a method for improving the abrasion resistance of an electrophotographic photoreceptor (hereinafter, also simply referred to as "photoreceptor"), a technique has been proposed in which a radical polymerizable resin is used on the surface of the photoreceptor, and the surface layer of the photoreceptor is made into a cured layer to increase the mechanical strength of the surface layer.

[0004] An electrophotographic photoreceptor is generally used in an electrophotographic image forming process including a charging step, an exposure step, a developing step, a transfer step, and a cleaning step. Among them, the cleaning step for removing residual toner on the electrophotographic photoreceptor after the transfer step is an important step for obtaining a clear image. As this cleaning method, a method of pressing a rubber-like cleaning blade against the electrophotographic photoreceptor to scrape off the toner is common.

[0005] However, in the above cleaning method, since the frictional force between the cleaning blade and the electrophotographic photoreceptor is large, vibration of the cleaning blade occurs, and image defects due to cleaning are likely to occur. This problem of the cleaning blade becomes more prominent as the mechanical strength of the surface layer of the electrophotographic photoreceptor increases, that is, as the circumferential surface of the electrophotographic photoreceptor is less likely to wear. That is, this problem occurs by making the surface layer of the electrophotographic photoreceptor a hardened layer and increasing the mechanical strength of the surface layer as described above. In addition, the surface layer of the organic electrophotographic photoreceptor is generally formed by the dip coating method in many cases. However, the surface of the surface layer formed by the dip coating method (that is, the circumferential surface of the electrophotographic photoreceptor) becomes very smooth. Therefore, the contact area between the cleaning blade and the circumferential surface of the electrophotographic photoreceptor increases, the frictional resistance between the cleaning blade and the circumferential surface of the electrophotographic photoreceptor increases, and the above problem becomes prominent.

[0006] As a method for overcoming the above problems, a method has been proposed in which an uneven shape is provided on the surface of the photoreceptor to reduce the contact area between the outer surface of the electrophotographic photoreceptor and the cleaning blade, reduce the frictional force, and improve the cleaning property.

[0007] Patent Document 1 describes a technique of a photoreceptor having a groove shape along the circumferential direction of the outer circumferential surface of the photoreceptor. Further, Patent Document 2 describes a technique of transferring a circular uneven shape of a mold member to the surface of the photoreceptor.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] In recent years, due to the increasing demand for high-precision and high-quality images, spherical toner with a small particle size has become the mainstream. Spherical toner with a small particle size has a large adhesion force to the surface of the photoreceptor, and it is likely that the removal of residual toner such as transferred residual toner adhering to the surface is insufficient. In order to solve this problem, if an uneven shape is provided on the surface of the photoreceptor to reduce the frictional force, the contact pressure of the cleaning blade can be increased, and the cleaning performance for small particle size toner can be improved.

[0010] However, in an environment of high temperature and high humidity, due to the deformation of the cleaning blade and material characteristics, the frictional force with the photoreceptor tends to increase. Also, if the toner is repeatedly compressed in the concave portions on the surface of the photoreceptor, the toner may aggregate and cause toner fusion on the surface of the photoreceptor, easily generating image defects (for example, white spots in a solid image) starting from the fused toner.

[0011] In the technology disclosed in Patent Document 1, in an environment of high temperature and high humidity, the frictional force between the cleaning blade and the photoreceptor becomes high, and there may be a cleaning failure where the toner partially slips through the groove-shaped portion of the photoreceptor. Also, in the technology disclosed in Patent Document 2, in an environment of high temperature and high humidity, toner fusion may occur in the circular concave portions on the surface of the photoreceptor, generating white spot images.

[0012] Therefore, an object of the present invention is to provide an electrophotographic photoreceptor that can achieve both suppression of toner slipping through and suppression of toner fusion even in an environment of high temperature and high humidity.

Means for Solving the Problem

[0013] The above object is achieved by the following present invention. That is, the electrophotographic photoreceptor according to the present invention is an electrophotographic photoreceptor having a support and a photosensitive layer, the outer surface of the electrophotographic photoreceptor has wrinkles, On the outer surface, observation regions are provided, each being a square with a side length of 300 μm and having as its center point one of 76 intersection points of 19 line segments that divide the electrophotographic photoreceptor into 20 equal parts in the axial direction and 4 line segments that divide it into 4 equal parts in the circumferential direction. The orientation of the observation region is such that one side of the square forming the observation region is parallel to the circumferential direction of the electrophotographic photoreceptor. A line parallel to the circumferential direction of the electrophotographic photoreceptor passing through the center point of the observation region is defined as the first reference line L1. When 1799 reference lines obtained by rotating the first reference line by 0.1° around the center point are denoted as L2 to L1800 respectively, In the convex portion of the wrinkle, there is a linear portion, and the linear portion is a linear portion that is parallel to either reference lines L1 to L150 or reference lines L1651 to L1800 and has a length of 50 μm or more. Each of the reference lines L1 to L1800 intersects the convex portion of the wrinkle at a plurality of locations, and at least two selected from the plurality of locations have different intersection angles with each other. In the observation region, when frequency analysis is performed on the height information of the wrinkle and a two-dimensional power spectrum F(r, θ) is obtained with the frequency component as r and the angular component as θ, the one-dimensional radial distribution function p(r) obtained by integrating the two-dimensional power spectrum F(r, θ) in the θ direction has at least one maximum value. Regarding the frequency rp at which the one-dimensional radial distribution function p(r) takes the maximum value, when the angular distribution q(θ) is calculated from the two-dimensional power spectrum F(r, θ), the maximum value of the power value in the range of θ = 0° to 15° and the range of 165° to 180° is 1.15 times or more the average value of the power value in the range of θ = 16° to 164°.

Advantages of the Invention

[0014] According to the present invention, it is possible to provide an electrophotographic photoreceptor that achieves both suppression of toner leakage and suppression of toner fusion even in an environment of high temperature and high humidity.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0016] Hereinafter, the present invention will be described in detail by giving preferred embodiments. As a result of investigations by the present inventors, when cleaning is performed by increasing the contact pressure of the cleaning blade in a high-temperature and high-humidity environment, it has been found that toner passes through the contact portion between the groove shape and the cleaning blade in a photoreceptor provided with groove shapes connected in the circumferential direction of the photoreceptor. Further, in a photoreceptor provided with groove shapes orthogonal to the circumferential direction of the photoreceptor, it has been found that toner is repeatedly compressed in the groove shapes during cleaning, aggregated, and likely to cause toner fusion, and image defects starting from the fused toner are likely to occur.

[0017] As a result of intensive investigations, it has been found that by providing a predetermined wrinkle shape described below on the outer surface of the electrophotographic photoreceptor, it is possible to highly achieve both suppression of toner leakage and toner fusion. Specifically, the outer surface of the electrophotographic photoreceptor according to the present invention has wrinkles. On the outer surface, 76 intersection points of 19 line segments that divide the electrophotographic photoreceptor into 20 equal parts in the axial direction and 4 line segments that divide it into 4 equal parts in the circumferential direction are each used as the center point, and observation regions in the shape of squares with a side length of 300 μm are placed. The orientation of the observation region is such that one side of the square forming the observation region is parallel to the circumferential direction of the electrophotographic photoreceptor. A line parallel to the circumferential direction of the electrophotographic photoreceptor passing through the center point of the observation region is defined as the first reference line L1. When 1799 reference lines obtained by rotating the first reference line by 0.1° around the center point are respectively designated as L2 to L1800, linear-shaped portions exist on the convex portions of the wrinkles. The linear-shaped portions are linear-shaped portions that are parallel to any one of the reference lines L1 to L150 and L1651 to L1800 and have a length of 50 μm or more. Each of the reference lines L1 to L1800 intersects the convex portions of the wrinkles at a plurality of locations, and at least two selected from the plurality of locations have different intersection angles. In the observation region, when the height information of the wrinkles is subjected to frequency analysis and a two-dimensional power spectrum F(r, θ) is obtained with the frequency component as r and the angular component as θ, the one-dimensional radial distribution function p(r) obtained by integrating the two-dimensional power spectrum F(r, θ) in the θ direction has at least one maximum value. For the frequency rp at which the one-dimensional radial distribution function p(r) takes the maximum value, when the angular distribution q(θ) is calculated from the two-dimensional power spectrum F(r, θ), the maximum values of the power values in the ranges of θ = 0° to 15° and 165° to 180° are power values that are 1.15 times or more the average value of the power values in the range of θ = 16° to 164°.

[0018] The shape of the wrinkles on the outer surface of the electrophotographic photoreceptor according to the present invention will be specifically described. The wrinkles of the present invention have a fineness equal to or greater than a certain level and have a predetermined number or more of convex portions within a certain range. Specifically, first, 76 intersection points of 19 line segments that divide the electrophotographic photoreceptor into 20 equal parts in the axial direction and 4 line segments that divide it into 4 equal parts in the circumferential direction on the outer peripheral surface of the photoreceptor are each used as the center point, and an observation region in the shape of a square with a side length of 300 μm is placed in a direction where one side is parallel to the circumferential direction of the photoreceptor. Subsequently, a line parallel to the circumferential direction of the photoreceptor passing through the center point of the observation region is defined as the first reference line L1. Also, with the center point as the center, 1799 reference lines obtained by rotating the first reference line every 0.1° are respectively designated as L2 to L1800. At this time, the wrinkles on the outer surface of the electrophotographic photoreceptor have a sufficient number of convex portions to intersect each of the reference lines L1 to L1800 at a plurality of locations.

[0019] Moreover, the wrinkles on the outer surface of the electrophotographic photoreceptor according to the present invention have a complex shape, and the ridge lines of the convex portions face various directions. Specifically, for each of the reference lines L1 to L1800, at least two selected from a plurality of locations where the convex portions of the wrinkles intersect have different intersection angles with each other.

[0020] Furthermore, there are portions on the ridge lines of the convex portions of the wrinkles that have a linear shape portion with a length of 50 μm or more parallel to any one of the reference lines L1 to L150 and the reference lines L1651 to L1800. It is more preferable that there are portions having a linear shape portion with a length of 100 μm or more.

[0021] FIG. 1 is a diagram showing an example of the concavo-convex shape of the wrinkles of the electrophotographic photoreceptor according to the present invention. FIG. 1(A) is a top view of the outer surface of the electrophotographic photoreceptor, and FIG. 1(B) is a graph showing the height information obtained from the surface observation on the outer surface of the electrophotographic photoreceptor.

[0022] The wrinkles on the outer surface of the electrophotographic photoreceptor according to the present invention are stripe-shaped uneven shapes observable on the outer surface of the electrophotographic photoreceptor as shown in FIG. 1(A). The stripe shape is not distributed in a single direction, but is composed of curved portions, straight portions, interrupted portions, branched portions, etc., and a plurality of them exist in an observation region in the shape of a square with one side being 300 μm.

[0023] Also, as shown by 1a and 1b in FIG. 1(A), the ridge line of the wrinkle refers to a straight line or a curve formed by connecting the convex portions in the stripe-shaped uneven shape when observing the outer surface of the electrophotographic photoreceptor.

[0024] The method for specifying the convex portions and obtaining the ridge lines by surface observation on the outer surface of the electrophotographic photoreceptor is not particularly limited. For example, it can be specified by image-analyzing the height information obtained by measurement using a confocal laser microscope. An example of plotting the height information thus obtained against the positions on a straight line placed on the outer surface of the electrophotographic photoreceptor is shown in FIG. 1(B). By specifying the apexes of the convex shapes indicated by 1c in FIG. 1(B), the ridge lines of the curved wrinkles as shown by 1a in FIG. 1(A) and the ridge lines of the straight wrinkles as shown by 1b can be obtained.

[0025] A method for determining whether a wrinkle has a linear portion with a length of 50 μm or more will be described with reference to FIGS. 8(A) to 8(C). As shown in FIG. 8(A), on one of the two sides perpendicular to the circumferential direction on the side of the square that is the above-mentioned observation region, one of the two sides is defined as side A and the opposite side is defined as side B. Next, the intersection point between side A and the ridge line of the wrinkle is obtained. As shown in FIG. 8(C), with the intersection point as starting point A, follow the ridge line in the direction of side B from starting point A, and detect an end point B at a distance of 50 μm in a straight-line distance. Provide two line segments a and b at a position 2 μm away in parallel with the geometric straight line A connecting starting point A and end point B. If the ridge line connecting starting point A and end point B is within the range of line segments a and b, the ridge line is regarded as having a linear portion of 50 μm represented by the geometric straight line A. Subsequently, when searching for a linear portion continuously, as shown in FIG. 8(B), provide a straight line at a position 5 μm away in parallel with side A, and with the intersection point between the straight line and the wrinkle as starting point A, search for a linear portion of 50 μm in the same manner as above. Thereafter, shift the straight line by 5 μm each time, and repeatedly search for the linear portion up to side B. When searching for a linear portion of 100 μm or more, it is the same as above except that the straight-line distance from starting point A to end point B is changed from 50 μm to 100 μm.

[0026] Next, a method for determining whether the linear portion is parallel to reference lines L1 to L150 and reference lines L1651 to L1800 will be described. If the angular deviation between the linear portion and the reference line is within 0.05°, the linear portion and the reference line are regarded as parallel. Specific examples are shown in FIGS. 9(A) to 9(D). In FIG. 9(A), since the angle of the linear portion with respect to the first reference line L1 is 0.03°, it is parallel to the reference line L1. In FIG. 9(B), since the angle of the linear portion with respect to the first reference line L1 is 0.05°, it is parallel to the reference lines L1 and L2. In FIG. 9(C), since the angle of the linear portion with respect to the first reference line L1 is 14.95°, it is parallel to the reference line L150. In FIG. 9(D), since the angle of the linear portion with respect to the first reference line L1 is 164.95°, it is parallel to the reference line L1651. Thus, if the linear portion is 50 μm or more and the angular deviation between the linear portion and the reference lines L1 to L150 and the reference lines L1651 to L1800 is within 0.05°, it can be regarded as parallel, and the requirements of the present invention are satisfied.

[0027] In the present invention, the ridge line of the wrinkle has a plurality of curvatures within the ridge line. The curvature is a quantity representing the degree of bending of a curve. When approximating the vicinity of an arbitrary point on the curve with a circle, the curvature χ is obtained as the reciprocal of the radius R of the circle, as shown by the mathematical formula (I).

Number

[0028] Furthermore, the electrophotographic photoreceptor according to the present invention satisfies the following conditions. That is, in the above observation region, when frequency analyzing the height information of the wrinkle and obtaining a two-dimensional power spectrum F(r,θ) with the frequency component as r and the angular component as θ, the one-dimensional radial distribution function p(r) obtained by integrating the two-dimensional power spectrum F(r,θ) in the θ direction has at least one maximum value. For the frequency rp when the one-dimensional radial distribution function p(r) takes the maximum value, when calculating the angular distribution q(θ) from the two-dimensional power spectrum F(r,θ), the maximum value of the power value in the range of θ = 0° to 15° and the range of 165° to 180° is 1.15 times or more the average value of the power value in the range of θ = 16° to 164°.

[0029] As a result of investigations by the present inventors, as shown in Fig. 1(A), it has been found that when the outer surface of the electrophotographic photoreceptor has wrinkles and the concavo-convex shape of the wrinkles has a predetermined periodicity, the effects of the present invention can be obtained highly.

[0030] The method for obtaining the periodicity of the concavo-convex shape of the wrinkle is not particularly limited. For example, after obtaining height information from surface observation on the outer surface of the electrophotographic photoreceptor, a method of analyzing the obtained result using two-dimensional Fourier transform can be mentioned.

[0031] Specifically, when obtaining the height information of wrinkles with the number of data N1×N2, if the height at an arbitrary point (n,m) in the plane is denoted as hn,m, the two-dimensional power spectrum P(k,l) obtained by discrete Fourier transform is given by the following mathematical formula (II).

Equation

Equation

[0032] Furthermore, the two-dimensional power spectrum P(k,l) obtained by the mathematical formula (II) is converted from the rectangular coordinate system (k,l) to the polar coordinate system (r,θ), and is represented by the two-dimensional power spectrum F(r,θ). Here, r and θ satisfy the following mathematical formulas (IV) and (V), respectively.

Equation

Equation

[0033] In the present invention, in an observation region of a square with a side length of 300 μm, the height information obtained by measuring at regular intervals of 0.25 μm or less in two directions parallel to each side of the square is used for analysis.

[0034] FIG. 2 is a diagram showing an example of the results obtained by numerical analysis of the electrophotographic photoreceptor according to the present invention. FIG. 2(A) is a diagram showing the two-dimensional power spectrum F(r,θ) obtained by frequency analysis of the wrinkles on the outer surface of the electrophotographic photoreceptor. Further, FIG. 2(B) is a diagram showing the one-dimensional radial distribution function obtained by integrating the obtained two-dimensional power spectrum F(r,θ) in the θ direction. Further, FIG. 2(C) is a diagram showing the variation in power values in the entire θ range when the angular distribution q(θ) is calculated from the two-dimensional power spectrum F(r,θ) for the frequency rp at which the one-dimensional radial distribution function p(r) takes a maximum value.

[0035] As shown in FIG. 2(B), in the electrophotographic photoreceptor according to the present invention, the radial distribution function p(r) obtained by one-dimensionally converting the two-dimensional power spectrum F(r,θ) in the radial direction has at least one maximum value. This means that the unevenness of the plurality of wrinkles on the outer surface of the electrophotographic photoreceptor is distributed at regular intervals.

[0036] Further, as shown in FIG. 2(C), when calculating the angular distribution q(θ) of F(rp,θ) for the frequency rp at which the radial distribution function p(r) becomes maximum, the maximum values of the power values in the ranges of θ = 0° to 15° and 165° to 180° are 1.15 times or more the average value of the power values in the range of θ = 16° to 164°. This means that in the above observation region, there are more components extending in the circumferential direction among the ridge lines of the plurality of wrinkles on the outer surface of the electrophotographic photoreceptor than the components in other directions. The ratio of the power values is preferably 1.15 times or more and 1.35 times or less. If the ratio of the power values exceeds 1.35 times, the circumferential component becomes too large, and it becomes difficult to obtain the cleaning effect obtained by the ridge lines of the convex portions of the plurality of wrinkles facing various directions.

[0037] Regarding the detailed mechanism of action by which the present invention exhibits its effects, it is estimated as follows. First, it is speculated that the wrinkles have a predetermined number of protrusions or more within a certain range, thereby reducing the contact area when the cleaning blade contacts the electrophotographic photosensitive member, thereby reducing frictional force. Furthermore, it is speculated that the ridges of the wrinkles' protrusions face in various directions, which prevents toner from slipping through the recesses as the electrophotographic photosensitive member rotates. Furthermore, even among the ridges facing in various directions, there are a certain number of wrinkles extending in the circumferential direction, which allows the pressure applied to the toner by the cleaning blade to escape and be dispersed by the circumferential wrinkles. Therefore, it is speculated that excessive pressure is not continuously applied to the toner, thereby preventing toner melting.

[0038] The frequency rp at which the radial distribution function p(r) above takes a maximum value is 0.04 μm -1 More than 0.25μm -1 If the frequency rp is within the range below, it is easy to suppress the toner from passing through. Furthermore, the frequency rp when the radial distribution function p(r) takes a maximum value is 0.10 μm. -1 More than 0.25μm -1 It is more preferable that the ratio is less than or equal to the above.

[0039] The arithmetic mean roughness Ra of the wrinkles in the observation area is preferably 0.03 μm or more and 0.25 μm or less, since this makes it easier to prevent toner from slipping through, and more preferably 0.03 μm or more and 0.12 μm or less.

[0040] [Electrophotographic photoreceptor] The method for producing the electrophotographic photoreceptor of the present invention includes a method in which a coating liquid for each layer described below is prepared, and the layers are coated in the desired order and dried. In this case, the coating liquid can be applied by dip coating, spray coating, inkjet coating, roll coating, die coating, blade coating, curtain coating, wire bar coating, ring coating, etc. Among these, dip coating is preferred from the viewpoints of efficiency and productivity. The support and each layer will be described below.

[0041] <Support> In the present invention, the electrophotographic photoreceptor has a support. In the present invention, the support is preferably a conductive support having conductivity. Further, examples of the shape of the support include a cylindrical shape, a belt shape, and a sheet shape. Among these, a cylindrical support is preferable. Further, an electrochemical treatment such as anodization, a blasting treatment, a cutting treatment, or the like may be performed on the surface of the support. Examples of the material of the support include metal, resin, glass, and the like. Examples of the metal include aluminum, iron, nickel, copper, gold, stainless steel, and alloys thereof. Among these, an aluminum support using aluminum is preferable. Further, conductivity may be imparted to the resin or glass by a treatment such as mixing or coating with a conductive material.

[0042] <Conductive layer> In the present invention, a conductive layer may be provided on the support. By providing the conductive layer, it is possible to conceal scratches and unevenness on the support surface and to control light reflection on the support surface. The conductive layer preferably contains conductive particles and a resin.

[0043] Examples of the material of the conductive particles include metal oxides, metals, carbon black, and the like. Examples of the metal oxide include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, magnesium oxide, antimony oxide, bismuth oxide, and the like. Examples of the metal include aluminum, nickel, iron, chromium, copper, zinc, silver, and the like. Among these, it is preferable to use a metal oxide as the conductive particles, and more preferably, titanium oxide, tin oxide, or zinc oxide. When a metal oxide is used as the conductive particle, the surface of the metal oxide may be treated with a silane coupling agent or the like, or the metal oxide may be doped with an element such as phosphorus or aluminum or an oxide thereof. Further, the conductive particles may have a laminated structure having core material particles and a coating layer covering the particles. Examples of the core material particles include titanium oxide, barium sulfate, zinc oxide, and the like. Examples of the coating layer include metal oxides such as tin oxide. When a metal oxide is used as the conductive particles, the volume average particle diameter thereof is preferably 1 nm or more and 500 nm or less, and more preferably 3 nm or more and 400 nm or less.

[0044] Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, alkyd resin, and the like. Further, the conductive layer may further contain a concealer such as silicone oil, resin particles, titanium oxide, or the like.

[0045] The average film thickness of the conductive layer is preferably 1 μm or more and 50 μm or less, and particularly preferably 3 μm or more and 40 μm or less. The conductive layer can be formed by preparing a coating liquid for the conductive layer containing each of the above materials and a solvent, forming this coating film, and drying it. Examples of the solvent used in the coating liquid include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents, and the like. Examples of the dispersion method for dispersing the conductive particles in the coating liquid for the conductive layer include a method using a paint shaker, a sand mill, a ball mill, and a liquid collision type high-speed disperser.

[0046] <Undercoat layer> In the present invention, an undercoat layer may be provided on the support or the conductive layer. By providing the undercoat layer, the interlayer adhesion function can be enhanced and a charge injection blocking function can be imparted. The undercoat layer preferably contains a resin. Further, an undercoat layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group. Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, polyvinyl phenol resin, alkyd resin, polyvinyl alcohol resin, polyethylene oxide resin, polypropylene oxide resin, polyamide resin, polyamic acid resin, polyimide resin, polyamideimide resin, and cellulose resin. Examples of the polymerizable functional group of the monomer having a polymerizable functional group include isocyanate group, blocked isocyanate group, methylol group, alkylated methylol group, epoxy group, metal alkoxide group, hydroxyl group, amino group, carboxyl group, thiol group, carboxylic anhydride group, and carbon-carbon double bond group.

[0047] Further, the undercoat layer may further contain an electron transport material, a metal oxide, a metal, a conductive polymer, etc. for the purpose of enhancing electrical properties. Among these, it is preferable to use an electron transport material and a metal oxide. Examples of the electron transport material include quinone compounds, imide compounds, benzimidazole compounds, cyclopentadienylidene compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, halogenated aryl compounds, silole compounds, boron-containing compounds, etc. As the electron transport material, an electron transport material having a polymerizable functional group may be used and copolymerized with the monomer having the above-mentioned polymerizable functional group to form the undercoat layer as a cured film. Examples of the metal oxide include indium tin oxide, tin oxide, indium oxide, titanium oxide, zinc oxide, aluminum oxide, silicon dioxide, etc. Examples of the metal include gold, silver, aluminum, etc. Further, the undercoat layer may further contain an additive.

[0048] The average film thickness of the undercoat layer is preferably 0.1 μm or more and 50 μm or less, more preferably 0.2 μm or more and 40 μm or less, and particularly preferably 0.3 μm or more and 30 μm or less. The undercoat layer can be formed by preparing an undercoat layer coating solution containing each of the above materials and a solvent, forming this coating film, and drying and / or curing it. Examples of the solvent used in the coating solution include alcohol solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents, and the like.

[0049] <Photosensitive layer> The photosensitive layer of the electrophotographic photoreceptor is mainly classified into (1) a laminated photosensitive layer and (2) a single-layer photosensitive layer. (1) The laminated photosensitive layer has a charge generation layer containing a charge generating substance and a charge transport layer containing a charge transport substance. (2) The single-layer photosensitive layer has a photosensitive layer containing both a charge generating substance and a charge transport substance. The present invention is preferably used in the manufacture of a photoreceptor having a laminated photosensitive layer.

[0050] (1) Laminated photosensitive layer The laminated photosensitive layer has a charge generation layer and a charge transport layer.

[0051] (1-1) Charge generation layer The charge generation layer preferably contains a charge generating substance and a resin. Examples of the charge generating substance include azo pigments, perylene pigments, polycyclic quinone pigments, indigo pigments, phthalocyanine pigments, and the like. Among these, azo pigments and phthalocyanine pigments are preferred. Among the phthalocyanine pigments, oxytitanium phthalocyanine pigments, chlorogallium phthalocyanine pigments, and hydroxygallium phthalocyanine pigments are preferred. The content of the charge generating substance in the charge generation layer is preferably 40% by mass or more and 85% by mass or less, more preferably 60% by mass or more and 80% by mass or less, based on the total mass of the charge generation layer. Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, polyvinyl butyral resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, polyvinyl alcohol resin, cellulose resin, polystyrene resin, polyvinyl acetate resin, polyvinyl chloride resin, etc. Among these, polyvinyl butyral resin is more preferable.

[0052] Further, the charge generation layer may further contain additives such as an antioxidant and an ultraviolet absorber. Specifically, examples include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, etc. The average film thickness of the charge generation layer is preferably 0.1 μm or more and 1 μm or less, and more preferably 0.15 μm or more and 0.4 μm or less. The charge generation layer can be formed by preparing a coating solution for the charge generation layer containing each of the above materials and a solvent, forming this coating film, and drying it. Examples of the solvent used in the coating solution include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents, etc.

[0053] (1-2) Charge transport layer The charge transport layer preferably contains a charge transport material and a resin. Examples of the charge transport material include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and resins having groups derived from these substances. Among these, triarylamine compounds and benzidine compounds are preferable, and the compound represented by formula (1) is preferably used.

Chemical formula

[0054] Examples of the structure represented by formula (1) are shown in formulas (1-1) to (1-10). Among these, the structures represented by formulas (1-1) to (1-6) are more preferable.

Chem.

Chem.

Chem.

Chem.

Chem.

Chem.

Chem.

Chem.

Chem.

Chem.

[0055] As the resin, a thermoplastic resin is used, and examples thereof include a polyester resin, a polycarbonate resin, an acrylic resin, and a polystyrene resin. Among these, a polycarbonate resin and a polyester resin are preferable. As the polyester resin, a polyarylate resin is particularly preferable.

[0056] The content of the charge transport material in the charge transport layer is preferably 25% by mass or more and 70% by mass or less, and more preferably 30% by mass or more and 55% by mass or less with respect to the total mass of the charge transport layer. The content ratio (mass ratio) of the charge transport material to the resin is preferably 4:10 to 20:10, and more preferably 5:10 to 12:10.

[0057] Further, the charge transport layer may contain additives such as an antioxidant, an ultraviolet absorber, a plasticizer, a leveling agent, a lubricity-imparting agent, and an abrasion resistance improver. Specifically, examples include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, fluororesin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, and boron nitride particles.

[0058] The average film thickness of the charge transport layer is preferably 5 μm or more and 50 μm or less, more preferably 8 μm or more and 40 μm or less, and particularly preferably 10 μm or more and 30 μm or less.

[0059] (2) Single-layer photosensitive layer The single-layer photosensitive layer can be formed by preparing a coating solution for the photosensitive layer containing a charge generating substance, a charge transporting substance, a resin, and a solvent, forming this coating film, and drying it. Examples of the charge generating substance, the charge transporting substance, and the resin are the same as those exemplified in the above “(1) Laminated photosensitive layer”.

[0060] <Protective layer> In the present invention, a protective layer is provided on the photosensitive layer. The protective layer is formed as a cured film by polymerizing a composition containing a compound having a polymerizable functional group. The protective layer preferably further contains conductive particles and / or a charge transporting substance and a resin. Examples of the conductive particles include particles of metal oxides such as titanium oxide, zinc oxide, tin oxide, and indium oxide. Examples of the charge transporting substance include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and resins having groups derived from these substances. Among these, triarylamine compounds and benzidine compounds are preferred. Examples of the resin include polyester resin, acrylic resin, phenoxy resin, polycarbonate resin, polystyrene resin, phenol resin, melamine resin, epoxy resin, etc. Among them, polycarbonate resin, polyester resin, and acrylic resin are preferable.

[0061] In addition, the protective layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group. Examples of the polymerizable functional group of the monomer having a polymerizable functional group include acryloyloxy group, methacryloyloxy group, etc. As the monomer having a polymerizable functional group, a material having a charge transport ability may be used. As the charge transport structure, a triarylamine structure is preferable in terms of charge transport. As the polymerizable functional group of the material having a charge transport ability, an acryloyloxy group and a methacryloyloxy group are preferable. The number of polymerizable functional groups of the monomer having a polymerizable functional group may be one or more. Among them, it is particularly preferable to polymerize a composition containing both a compound having a plurality of polymerizable functional groups and a compound having one polymerizable functional group to form a cured film, because the strain generated by the polymerization of the plurality of functional groups is easily eliminated.

[0062] Examples of the compound having one polymerizable functional group are shown in (2-1) to (2-6).

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0063] Examples of the compound having the plurality of polymerizable functional groups are shown in (3-1) to (3-7).

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0064] The protective layer may contain additives such as an antioxidant, an ultraviolet absorber, a plasticizer, a leveling agent, a lubricity imparting agent, and an abrasion resistance improving agent. Specifically, a hindered phenol compound, a hindered amine compound, a sulfur compound, a phosphorus compound, a benzophenone compound, a siloxane-modified resin, a silicone oil, fluororesin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, boron nitride particles, etc. can be mentioned.

[0065] The average film thickness of the protective layer is preferably 0.2 μm or more and 1.5 μm or less in order to form the wrinkle shape finely and uniformly, and more preferably 0.2 μm or more and 0.8 μm or less. The protective layer can be formed by preparing a coating liquid for the protective layer containing each of the above materials and a solvent, forming this coating film, and drying and / or curing it. Examples of the solvent used in the coating liquid include alcohol solvents, ketone solvents, ether solvents, sulfoxide solvents, ester solvents, and aromatic hydrocarbon solvents.

[0066] <Method for forming wrinkles on the outer surface of the electrophotographic photoreceptor> A method for forming wrinkles on the outer surface of the electrophotographic photoreceptor of the present invention will be described below. In the case of a laminated photosensitive layer, a protective layer, which is a crosslinkable cured film, is formed on a charge transport layer mainly composed of a thermoplastic resin, or in the case of a single-layer photosensitive layer, on a single-layer photosensitive layer mainly composed of a thermoplastic resin. At this time, the surface of the charge transport layer or the single-layer photosensitive layer before forming the protective layer is rubbed in the circumferential direction of the photoreceptor by applying abrasive paper, a wipe, or a non-woven fabric. Next, after forming a protective layer on the charge transport layer or the single-layer photosensitive layer that has been rubbed, a heat treatment is performed to generate a fine wrinkle shape. Therefore, when forming a wrinkle shape by this method, the outer surface of the electrophotographic photoreceptor is always the surface of the protective layer provided directly above the photosensitive layer.

[0067] As a mechanism for forming the wrinkle shape, during the heat treatment, due to the difference in the amount of deformation between the protective layer and the charge transport layer or the single-layer photosensitive layer, a compressive stress is applied in the surface direction, and the protective layer buckles, so it is considered that a wrinkle shape is formed on the outer surface of the photoreceptor. If a heat treatment is performed to form a wrinkle shape without performing the rubbing treatment, the entire surface of the photoreceptor tends to buckle uniformly. Therefore, as shown in the example of FIG. 3, the ridge lines of the wrinkles are formed randomly and isotropically. On the other hand, if the surface of the single-layer photosensitive layer or the charge transport layer before forming the protective layer is rubbed in the circumferential direction and the heat treatment is performed in a state where fine scratches are present in the circumferential direction, the protective layer is likely to buckle in the circumferential direction, and it is considered that the wrinkles are formed in a shape where the ridge lines of the wrinkles extend in the circumferential direction.

[0068] When rubbing the surface of the single-layer photosensitive layer or the charge transport layer, it is preferable to form shallow scratches so that the surface at the time of forming the protective layer becomes flat. The rubbing member may be appropriately selected according to the hardness of the surface layer. For example, when rubbing the single-layer photosensitive layer or the charge transport layer, it is preferable to rub with a soft non-woven fabric or the like. When increasing the pressing pressure, rubbing time, or number of times of the non-woven fabric, the wrinkle shape is likely to be formed along the circumferential direction, and a ridge line of the wrinkle having a linear shape portion of 100 μm or more parallel to any of the reference lines L1 to L150 and the reference lines L1651 to L1800 is likely to be formed. If the scratch on the surface of the single-layer photosensitive layer or charge transport layer is too deep, the surface of the protective layer will be concave at the time of forming the protective layer before wrinkle formation, and the uneven shape of the wrinkles will change greatly and the periodicity will not be uniform.

[0069] Although an example of applying a rubbing treatment to the single-layer photosensitive layer or charge transport layer before forming the protective layer has been described, a fine wrinkle shape can also be generated by applying a rubbing treatment after forming the protective layer on the charge transport layer or the single-layer photosensitive layer. Even when the surface of the protective layer is rubbed to cause scratches, the rubbing member and rubbing conditions may be appropriately set so that the scratches become shallow.

[0070] The heating temperature for generating wrinkles is preferably a temperature exceeding the boiling point of the residual solvent contained in the photosensitive layer. Furthermore, although it depends on the boiling point of the solvent used, a temperature of 140°C or higher and 230°C or lower is more preferable. When the heating temperature is set to a temperature exceeding the boiling point of the residual solvent, the residual solvent in the photosensitive layer rapidly evaporates, and that portion is likely to become the starting point of buckling due to compressive stress, and a fine and uniform wrinkle shape is easily formed.

[0071] The photosensitive layer is formed by applying this coating solution for the photosensitive layer to form a coating film for the photosensitive layer, and heating and drying the film. Examples of the solvent for the photosensitive layer coating solution include alcohol solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents. Specifically, toluene, xylene (including at least one selected from the group of o-xylene, m-xylene, and p-xylene), methyl benzoate, cyclohexanone, diethylene glycol monoethyl ether acetate, tetrahydrofuran, and dimethoxymethane can be mentioned. Since it is easy to leave an appropriate amount of residual solvent in the photosensitive layer before heating for wrinkle formation, it is preferable to combine a solvent with a boiling point of 140°C or higher and a solvent with a boiling point of 140°C or lower. For the measurement of the amount of residual solvent, known methods can be used, for example, gas chromatography can be used.

[0072] The coating solution for the protective layer contains a compound having a chain polymerizable functional group. The protective layer is formed as a film cured by applying this coating liquid for the protective layer onto the photosensitive layer and polymerizing a compound having a polymerizable functional group.

[0073] Examples of the reaction for polymerizing a composition containing a monomer having a polymerizable functional group include methods of polymerizing using heat, light (such as ultraviolet rays), or radiation (such as electron beams). Among these, radiation is preferable, and among radiation, electron beams are more preferable. The irradiation of electron beams is preferably performed in a low-oxygen atmosphere in order to prevent the deactivation of the radicalization of the polymerizable functional group. Also, in order to sufficiently advance the polymerization and form a cured film in a short time, it is necessary to raise the temperature to a certain extent. In order to prevent the deactivation of radicalization and polymerize promptly, it is preferable to perform heating in a low-oxygen atmosphere. The heating temperature is preferably implemented at a temperature not exceeding the residual solvent in the photosensitive layer, specifically, preferably 90°C or higher and 130°C or lower.

[0074] [Process Cartridge, Electrophotographic Apparatus] The process cartridge of the present invention integrally supports at least one means selected from the group consisting of the electrophotographic photoreceptor described so far, a charging means, a developing means, and a cleaning means, and is detachable from the electrophotographic apparatus main body. Further, the electrophotographic apparatus of the present invention is characterized by having at least one means selected from the group consisting of the electrophotographic photoreceptor described so far, a charging means, an exposure means, a developing means, and a transfer means.

[0075] FIG. 4 shows an example of the schematic configuration of an electrophotographic apparatus having a process cartridge equipped with an electrophotographic photoreceptor. The cylindrical electrophotographic photoreceptor 1 is rotationally driven about the axis 2 at a predetermined peripheral speed in the direction of the arrow. The surface of the electrophotographic photoreceptor 1 is charged to a predetermined positive or negative potential by the charging means 3. In FIG. 4, a roller charging method using a roller type charging member is shown, but charging methods such as a corona charging method, a proximity charging method, and an injection charging method may be employed. Exposure light 4 is irradiated from an exposure means (not shown) onto the charged surface of the electrophotographic photoreceptor 1, and an electrostatic latent image corresponding to the target image information is formed. The electrostatic latent image formed on the surface of the electrophotographic photoreceptor 1 is developed with toner housed in the developing means 5, and a toner image is formed on the surface of the electrophotographic photoreceptor 1. The toner image formed on the surface of the electrophotographic photoreceptor 1 is transferred to a transfer material 7 by the transfer means 6. The transfer material 7 onto which the toner image has been transferred is conveyed to the fixing means 8, undergoes a fixing process for the toner image, and is printed out outside the electrophotographic apparatus. The electrophotographic apparatus may have a cleaning means 9 for removing deposits such as toner remaining on the surface of the electrophotographic photoreceptor 1 after transfer. Further, instead of separately providing a cleaning means, a so-called cleanerless system for removing the above-mentioned deposits with a developing means or the like may be used. The electrophotographic apparatus may have a discharging mechanism for discharging the surface of the electrophotographic photoreceptor 1 by pre-exposure light 10 from a pre-exposure means (not shown). Further, guide means 12 such as rails may be provided for attaching and detaching the process cartridge 11 of the present invention to and from the electrophotographic apparatus main body.

[0076] The electrophotographic photoreceptor of the present invention can be used in a laser beam printer, an LED printer, a copying machine, a facsimile machine, and a multifunction machine thereof.

Example

[0077] Hereinafter, the present invention will be described in more detail using examples and comparative examples. The present invention is not limited in any way by the following examples as long as the gist thereof is not exceeded. In the description of the following examples, "parts" means mass basis unless otherwise specified.

[0078] <Manufacture of electrophotographic photoreceptor> 〔Example 1〕 An aluminum cylinder (JIS-A3003, aluminum alloy) with a diameter of 24 mm and a length of 257.5 mm was used as a support (conductive support).

[0079] Next, the following materials were prepared. · 214 parts of titanium dioxide (TiO2) particles (average primary particle diameter 230 nm) coated with oxygen-deficient tin oxide (SnO2) as metal oxide particles · 132 parts of a phenol resin (monomer / oligomer of phenol resin) (trade name: Pryophen J-325, manufactured by DIC Corporation, resin solid content: 60% by mass) as a binder · 98 parts of 1-methoxy-2-propanol as a solvent These were put into a sand mill using 450 parts of glass beads with a diameter of 0.8 mm, and dispersion treatment was carried out under the conditions of a rotation speed of 2000 rpm, a dispersion treatment time of 4.5 hours, and a set temperature of cooling water of 18 °C to obtain a dispersion. The glass beads were removed from this dispersion with a mesh (mesh opening: 150 μm). To the obtained dispersion, silicone resin particles (trade name: Tospearl 120, manufactured by Momentive Performance Materials Inc., average particle diameter 2 μm) as a surface roughness imparting material were added. The addition amount of the silicone resin particles was made 10% by mass based on the total mass of the metal oxide particles and the binder in the dispersion after removing the glass beads. Also, silicone oil (trade name: SH28PA, manufactured by Toray Dow Corning Co., Ltd.) as a leveling agent was added to the dispersion so as to be 0.01% by mass based on the total mass of the metal oxide particles and the binder in the dispersion. Next, a mixed solvent of methanol and 1-methoxy-2-propanol (mass ratio 1:1) was added to the dispersion so that the total mass of the metal oxide particles, the binder, and the surface roughness imparting material in the dispersion (that is, the mass of the solid content) was 67% by mass based on the mass of the dispersion. Then, by stirring, a coating liquid for the conductive layer was prepared. This coating liquid for the conductive layer was dip-coated on the support and heated at 140 °C for 1 hour to form a conductive layer with a film thickness of 30 μm.

[0080] Next, the following materials were prepared. · 4 parts of an electron transport substance (Formula E-1) · Block isocyanate (trade name: Duranate SBN-70D, manufactured by Asahi Kasei Chemicals Corporation) 5.5 parts · Polyvinyl butyral resin (Esrec KS-5Z, manufactured by Sekisui Chemical Co., Ltd.) 0.3 part · Zinc(II) hexanoate as a catalyst (manufactured by Mitsuwa Chemical Co., Ltd.) 0.05 part These were dissolved in a mixed solvent of 50 parts of tetrahydrofuran and 50 parts of 1-methoxy-2-propanol to prepare a coating solution for the undercoat layer. This coating solution for the undercoat layer was dip-coated onto the conductive layer and heated at 170 °C for 30 minutes to form an undercoat layer with a film thickness of 0.7 μm.

Chemical formula

[0081] Next, 10 parts of crystalline hydroxygallium phthalocyanine having peaks at positions of 7.5° and 28.4° and 5 parts of polyvinyl butyral resin (trade name: Esrec BX-1, manufactured by Sekisui Chemical Co., Ltd.) were prepared from a chart obtained by CuKα characteristic X-ray diffraction. These were added to 200 parts of cyclohexanone and dispersed for 6 hours using a sand mill apparatus with glass beads having a diameter of 0.9 mm. 150 parts of cyclohexanone and 350 parts of ethyl acetate were further added thereto for dilution to obtain a coating solution for the charge generation layer. The obtained coating solution was dip-coated onto the undercoat layer and dried at 95 °C for 10 minutes to form a charge generation layer with a film thickness of 0.20 μm.

[0082] Note that the X-ray diffraction measurement was performed under the following conditions. [Powder X-ray diffraction measurement] Measuring instrument used: RINT-TTRII X-ray diffractometer, manufactured by Rigaku Corporation X-ray tube: Cu Tube voltage: 50 KV Tube current: 300 mA Scanning method: 2θ / θ scan Scanning speed: 4.0° / min Sampling interval: 0.02° Start angle (2θ): 5.0° Stop angle (2θ): 40.0° Attachment: Standard sample holder Filter: Not used Incident monochromator: Used Counter monochromator: Not used Divergence slit: Open Divergence vertical limiting slit: 10.00 mm Scattering slit: Open Receiving slit: Open Flat monochromator: Used Counter: Scintillation counter

[0083] Next, the following materials were prepared. · 5 parts of a charge transport material (hole transport material) represented by the above structural formula (1-2) · 5 parts of a charge transport material (hole transport material) represented by the above structural formula (1-3) · 10 parts of polycarbonate (trade name: Iupilon Z400, manufactured by Mitsubishi Engineering Plastics Corporation) · 0.02 part of a polycarbonate resin having copolymerized units of the following structural formula (C-4) and the following structural formula (C-5) (x / y = 0.95 / 0.05: viscosity average molecular weight = 20,000) These were dissolved in a mixed solvent of 60 parts of toluene / 20 parts of methyl benzoate / 20 parts of dimethoxymethane to prepare a coating solution for the charge transport layer. This coating solution for the charge transport layer was dip-coated on the charge generation layer to form a coating film for the charge transport layer, and this coating film was dried at 120 °C for 30 minutes to form a charge transport layer with a film thickness of 16 μm.

Chemical formula

Chemical formula

[0084] <Friction treatment method 1> Next, a Trecie MK sheet (manufactured by Toray Industries, Inc.) was used as the non-woven fabric for rubbing. The non-woven fabric was stretched so as not to sag, and the surface of the support formed up to the charge transport layer was pushed in by 3 mm from the position where it just made contact, and the support was rotated at 60 rpm for 1 second and rubbed in the circumferential direction. Next, the following materials were prepared. · 8 parts of the compound represented by the above structural formula (2-2) · 16 parts of the compound represented by the above structural formula (3-1) · 0.1 part of a siloxane-modified acrylic compound (Simac US270, manufactured by Toagosei Co., Ltd.) These were mixed in 58 parts of cyclohexane and 25 parts of 1-propanol and stirred. In this way, a coating solution for the protective layer was prepared. This coating solution for the protective layer was dip-coated on the rubbed charge transport layer to form a coating film for the protective layer, and the obtained coating film was dried at 40°C for 5 minutes. Then, in a nitrogen atmosphere, while rotating the support (the irradiated object) at a speed of 300 rpm under the conditions of an acceleration voltage of 70 kV and a beam current of 5.0 mA, the coating film was irradiated with an electron beam for 1.6 seconds. The dose at the outermost surface layer position was 15 kGy. Then, in a nitrogen atmosphere, the temperature was raised from 25°C to 100°C over 20 seconds for the first heating to form a cured film with a film thickness of 0.8 μm. The oxygen concentration from the electron beam irradiation to the subsequent first heat treatment was 10 ppm or less. Next, in the air, it was naturally cooled until the temperature of the coating film reached 25°C, and the second heating was performed at 160°C for 15 minutes in the air to form a protective layer having a wrinkled shape on the surface. In this way, a cylindrical (drum-shaped) electrophotographic photoreceptor having the protective layer of Example 1 was produced.

[0085] 〔Examples 2 to 4, 7 to 13〕 Electrophotographic photoreceptors of Examples 2 to 4, 7 to 13 were produced in the same manner as in Example 1 except that the types of the respective compounds in the formation of the charge transport layer, the types of the respective compounds in the formation of the protective layer, and the rubbing conditions of the photosensitive layer were changed as shown in Table 1. The rubbing conditions 2 to 7 are shown below.

[0086] <Rubbing Condition 2> The support was moved at 20 mm / s in the generatrix direction, and rubbing was performed in the same manner as in Rubbing Condition 1, but in a direction inclined 15° with respect to the circumferential direction.

[0087] <Rubbing Condition 3> While moving the support at 20 mm / s in the direction opposite to Rubbing Condition 2, rubbing was performed in the same manner as in Rubbing Condition 2, but in a direction inclined 15° in the direction opposite to Rubbing Condition 2 with respect to the circumferential direction.

[0088] <Rubbing Condition 4> Rubbing was performed in the circumferential direction in the same manner as in Rubbing Condition 1, except that the pushing-in amount was changed to 6 mm.

[0089] <Rubbing Condition 5> The support was moved at 20 mm / s in the generatrix direction, and rubbing was performed in the same manner as in Rubbing Condition 4, but in a direction inclined 15° with respect to the circumferential direction.

[0090] <Rubbing Condition 6> While moving the support at 20 mm / s in the direction opposite to Rubbing Condition 5, rubbing was performed in the same manner as in Rubbing Condition 5, but in a direction inclined 15° in the direction opposite to Rubbing Condition 5 with respect to the circumferential direction.

[0091] <Rubbing Condition 7> Rubbing was performed in the circumferential direction in the same manner as in Rubbing Condition 1, except that the pushing-in amount was changed to 6 mm and the rotation time was changed to 3 seconds.

[0092] [Example 5] The types of each compound in the formation of the charge transport layer and the types of each compound in the formation of the protective layer were changed as shown in Table 1. Also, an electrophotographic photoreceptor of Example 5 was produced in the same manner as in Example 1, except that the solvent of the coating solution for the charge transport layer was changed to 60 parts of toluene / 30 parts of cyclohexanone / 10 parts of tetrahydrofuran, and the drying of the coating film was changed to drying at 110 °C for 30 minutes.

[0093] [Example 6] Without performing rubbing on the surface of the photosensitive layer, an electrophotographic photosensitive member before the rubbing treatment was produced in the same manner as in Example 1 up to the first heat treatment for forming the protective layer. Thereafter, rubbing was carried out under the following rubbing condition 8, and then second heating was performed at 160 °C for 15 minutes in the atmosphere to form a protective layer having a wrinkle shape on the surface, thereby producing the electrophotographic photosensitive member of Example 6.

[0094] <Rubbing condition 8> As the polishing sheet for rubbing, a lapping film sheet (count: 10000, abrasive grain: WA, manufactured by Sankyo Rikagaku Co., Ltd.) was used. The sheet was stretched so as not to be wrinkled, and the surface of the support formed up to the protective layer was pressed 2 mm from the position where it just made contact, and the support was rotated once at 60 rpm and rubbed in the circumferential direction.

[0095] [Comparative Example 1] An electrophotographic photosensitive member of Comparative Example 1 was produced in the same manner as in Example 1 except that the types of the respective compounds in the formation of the charge transport layer, the types of the respective compounds in the formation of the protective layer, and the rubbing conditions of the photosensitive layer were changed as shown in Table 1. The rubbing condition 9 carried out in Comparative Example 1 is shown below.

[0096] <Rubbing condition 9> While moving the support in the generatrix direction at 72 mm / s, in the same manner as in Rubbing condition 1, rubbing was carried out in a direction inclined 45° with respect to the circumferential direction.

[0097] [Comparative Example 2] An electrophotographic photosensitive member of Comparative Example 2 was produced in the same manner as in Example 1 except that the types of the respective compounds in the formation of the charge transport layer and the types of the respective compounds in the formation of the protective layer were changed as shown in Table 1 and rubbing treatment was not carried out.

[0098] [Comparative Example 3] The types of the respective compounds in the formation of the charge transport layer and the types of the respective compounds in the formation of the protective layer were changed as shown in Table 1, and in the formation of the protective layer, without performing the second heat treatment, an electrophotographic photosensitive member without wrinkles was prepared. The outer surface of the electrophotographic photosensitive member was polished under the following conditions using the polishing machine shown in Fig. 5. Feed speed of the polishing sheet: 400 mm / min Rotation speed of the electrophotographic photoreceptor: 240 rpm Polishing abrasive grains: Silicon carbide Average particle size of the polishing abrasive grains: 3 μm Polishing time: 20 seconds As the polishing sheet, a sheet-like substrate was provided with a layer 2-2 in which polishing abrasive grains were dispersed in a binder resin. While feeding this polishing sheet parallel to the surface of the sheet and rotating the electrophotographic photoreceptor 2-1, the upper and lower mechanism 2-4 pressed it perpendicular to the surface of the polishing sheet for 20 seconds to roughen the outer surface of the electrophotographic photoreceptor. As a result, an electrophotographic photoreceptor according to Comparative Example 3 having a plurality of groove shapes extending in the circumferential direction of the electrophotographic photoreceptor and parallel to each other as shown in FIG. 6 was produced on the outer surface.

[0099] [Comparative Example 4] The types of each compound in the formation of the charge transport layer and the types of each compound in the formation of the protective layer were changed as shown in Table 1, and in the formation of the protective layer, an electrophotographic photoreceptor without wrinkles was prepared without performing the second heat treatment. Then, the same roughening treatment as in Comparative Example 3 was performed. Next, the electrophotographic photoreceptor 2-1 was fixed, the polishing sheet was fed parallel to the axial direction of the electrophotographic photoreceptor 2-1, and the outer surface of the electrophotographic photoreceptor 2-1 was roughened. This roughening treatment was repeated by changing the angle in the rotation direction of the electrophotographic photoreceptor 2-1. As a result, an electrophotographic photoreceptor according to Comparative Example 4 having a groove shape formed in a lattice pattern on the outer surface of the electrophotographic photoreceptor as shown in FIG. 7 was produced.

[0100] [Evaluation] Using the electrophotographic photoreceptors produced in Examples 1 to 13 and the electrophotographic photoreceptors produced in Comparative Examples 1 to 4, the surface shape of the wrinkles on the outer surface of the electrophotographic photoreceptor was evaluated under the following conditions.

[0101] [Surface shape analysis 1] Regarding 76 observation regions, each with a center point at the intersection of 19 line segments that divide the electrophotographic photoreceptor axially into 20 equal parts and 4 line segments that divide it circumferentially into 4 equal parts on the outer surface of the electrophotographic photoreceptor, the surface shape was magnified and observed with a laser microscope (VK-X200 manufactured by Keyence Corporation) for a square observation region with a side length of 300 μm. Subsequently, for the obtained image including the concavo-convex shape of the wrinkles, a first reference line L1 parallel to the circumferential direction of the electrophotographic photoreceptor was provided passing through the center point of the observation region. Further, reference lines L1 to L1800 obtained by rotating the first reference line every 0.1° around the center point of the observation region were provided. Thereafter, verification was performed for the following Conditions 1, 2, and 3, and when all the observation regions satisfied the conditions, it was determined as A, and when any one of the conditions was not satisfied in all the observation regions, it was determined as B. Condition 1: Each of the reference lines L1 to L1800 intersects the convex portions of the wrinkles at a plurality of locations, and at least two selected from the plurality of intersection locations have different intersection angles from each other. Condition 2: There exists a location where the convex portion of the wrinkle has a 50-μm linear shape portion parallel to any of the reference lines L1 to L150 and the reference lines L1651 to L1800. Condition 3: There exists a location where the convex portion of the wrinkle has a 100-μm linear shape portion parallel to any of the reference lines L1 to L150 and the reference lines L1651 to L1800. The results are shown in Table 2.

[0102] [Surface Shape Analysis 2] The arithmetic mean roughness Ra of the wrinkles in the square observation region with a side length of 300 μm obtained in the above Surface Shape Analysis 1 was determined. Ra was taken as the Ra on the reference line L900. The results of the average value of Ra determined for all the observation regions are shown in Table 2.

[0103] [Surface Shape Analysis 3] The height information of the wrinkles obtained in the above Surface Shape Analysis 2 was frequency-analyzed to obtain a two-dimensional power spectrum F(r,θ). Next, a radial distribution function p(r) obtained by one-dimensionally converting the two-dimensional power spectrum F(r,θ) in the radial direction was calculated, and the frequency rp at which p(r) becomes maximum was determined. Furthermore, for the frequency rp at which p(r) reaches its maximum, the angular distribution q(θ) of F(rp,θ) was obtained, and the ratio of the maximum value of the power values in the ranges of θ = 0° to 15° and 165° to 180° to the average value of the power values in the range of θ = 16° to 164° was determined. Table 2 shows the average value results obtained for all observation regions. For the positions of the peaks of the power values of each example, Examples 1 to 6, 8, 10, and 11 had power value peaks at 0° and 180°. Examples 9 and 13 had power value peaks at 15°. Examples 7 and 12 had peaks at 165°. Comparative Example 1 had a power value peak at 45°. Comparative Example 2 had no distinct power value peak.

[0104] [Cleaning Performance Evaluation] As the electrophotographic apparatus, a modified model of a laser beam printer manufactured by Hewlett-Packard Company, with the product name HP LaserJet Enterprise Color M553dn, was used. As the modification points, first, the contact pressure of the cleaning blade against the electrophotographic photoreceptor was changed to 120% of the product conditions. Also, the apparatus was modified so that the applied voltage to the charging roller could be adjusted and measured, and the image exposure light amount could be adjusted and measured. The photoreceptors of Examples 1 to 13 and Comparative Examples 1 to 4 were installed in the cyan color cartridge of the image forming apparatus. Subsequently, in a high-temperature and high-humidity environment of 30°C and 80% RH, 100 sheets of A4-sized plain paper with an image output of 5% print ratio were output. As the charging conditions, the dark potential was -500V, and as the exposure conditions, the image exposure light amount was adjusted to 0.25 μJ / cm 2 . Subsequently, 10 solid white images were continuously printed out, and then the evaluation was performed using the halftone image immediately after 10 solid black images were output. Specifically, the streaks in the halftone image caused by toner leakage due to poor cleaning were visually counted and evaluated according to the following criteria. A: There are no streaks in terms of image quality, and the image quality is good. B: Extremely minor streaks occur. C: Minor streaks occur. D: Streaks occur in a part of the image. E: Streaks occur throughout the image. The results are shown in Table 2.

[0105] [Toner Fixing Evaluation] Following the above cleaning performance evaluation, a continuous output test of 10,000 sheets was conducted using A4 paper and a 2-dot line / 200-dot space horizontal line image in a high-temperature and high-humidity environment of 30°C and 80% RH. Following the continuous output test, a solid black image was output. The output image was visually inspected, and the number of white spots within the distance of one circumference of the electrophotographic photoreceptor was confirmed. The evaluation criteria for white spots due to toner fixing are as follows. A: No white spots. B: One white spot. C: Two to four white spots D: Five or more white spots The results are shown in Table 2.

[0106]

Table 1

[0107]

Table 2

Explanation of Symbols

[0108] 1 Electrophotographic photoreceptor 2 Axis 3 Charging means 4 Exposure light 5 Developing means 6 Transfer means 7 Transfer material 8 Fixing means 9 Cleaning means 10 Pre-exposure light 11 Process cartridge 12 Guide means

Claims

1. An electrophotographic photoreceptor having a support and a photosensitive layer, wherein the outer surface of the electrophotographic photoreceptor has wrinkles, on the outer surface, observation regions which are squares with a side length of 300 μm are placed with 76 intersection points of 19 line segments that divide the electrophotographic photoreceptor into 20 equal parts in the axial direction and 4 line segments that divide it into 4 equal parts in the circumferential direction as the center points respectively, and the orientation of the observation region is such that one side of the square forming the observation region is parallel to the circumferential direction of the electrophotographic photoreceptor, a line parallel to the circumferential direction of the electrophotographic photoreceptor passing through the center point of the observation region is defined as the first reference line L1, when 1799 reference lines obtained by rotating the first reference line by 0.1° around the center point are defined as L2 to L1800 respectively, there are linear-shaped portions on the convex portions of the wrinkles, the linear-shaped portions are linear-shaped portions parallel to any one of the reference lines L1 to L150 and the reference lines L1651 to L1800 and having a length of 50 μm or more, each of the reference lines L1 to L1800 intersects the convex portions of the wrinkles at a plurality of locations, and at least two selected from the plurality of locations have different intersection angles from each other, in the observation region, when the height information of the wrinkles is subjected to frequency analysis and a two-dimensional power spectrum F(r, θ) is obtained with the frequency component as r and the angular component as θ, the one-dimensional radial distribution function p(r) obtained by integrating the two-dimensional power spectrum F(r, θ) in the θ direction has at least one maximum value, for the frequency rp when the one-dimensional radial distribution function p(r) takes the maximum value, when the angular distribution q(θ) is calculated from the two-dimensional power spectrum F(r, θ), the maximum power values in the ranges of θ = 0° to 15° and 165° to 180° are 1.15 times or more the average power value in the range of θ = 16° to 164°, characterized in that it is an electrophotographic photoreceptor.

2. The frequency rp is 0.04 μm －１ or more and 0.25 μm －１ or less, and the electrophotographic photoreceptor according to claim 1

3. The electrophotographic photoreceptor according to claim 1 or 2, wherein the arithmetic mean roughness Ra of the wrinkles in the observation region is 0.03 μm or more and 0.25 μm or less.

4. The electrophotographic photoreceptor according to any one of claims 1 to 3, wherein in the observation region, the convex portions of the wrinkles have linear-shaped portions parallel to any one of the reference lines L1 to L150 and the reference lines L1651 to L1800 and having a length of 100 μm or more.

5. A process cartridge integrally supporting at least one means selected from the group consisting of the electrophotographic photoreceptor according to any one of claims 1 to 4, a charging means, a developing means, and a cleaning means, and being detachable from an electrophotographic apparatus main body.

6. An electrophotographic apparatus having at least one means selected from the group consisting of the electrophotographic photoreceptor according to any one of claims 1 to 4, a charging means, an exposure means, a developing means, and a transfer means.

Images