Rotating body for electrophotography and electrophotographic image forming apparatus

Abstract

To provide a rotating body for electrophotography that exhibits minimal fluctuations in reflected light intensity when rotated and maintains excellent toner cleaning characteristics over the long term. [Solution] An electrophotographic rotating body having a surface layer, wherein the outer surface of the surface layer has a plurality of grooves and a predetermined plurality of recesses that extend substantially in the rotational direction of the electrophotographic rotating body and are regularly arranged in a direction perpendicular to the substantially rotational direction, the average spacing between the plurality of grooves is 2.0 to 10.0 μm, the recesses exist by cutting out a part of the wall that sandwiches the grooves when the electrophotographic rotating body is viewed from the outer surface side, when a circle is drawn based on the arc shape of the wall cut out by the recesses, the average diameter of the circle is 0.5 to 4.5 μm, the average value of the nearest distance between the centers of the plurality of circles drawn is within a predetermined range, and assuming that there is no cutout by the recesses, the wall extends in a predetermined direction.

Description

Technical Field

[0001] The present disclosure relates to a rotating body for electrophotography such as a conveyance transfer belt or an intermediate transfer belt used in an electrophotographic image forming apparatus such as a copying machine or a printer, and an electrophotographic image forming apparatus.

Background Art

[0002] In an electrophotographic image forming apparatus, an electrophotographic belt is used as a conveyance transfer belt for conveying a transfer material or an intermediate transfer belt for temporarily transferring and holding a toner image. There is an image forming apparatus that cleans transfer residual toner that could not be transferred to the electrophotographic belt using a cleaning blade made of an elastic member such as urethane rubber. In recent years, in order to compete with other printing methods, there has been a tendency to require higher durability of electrophotographic image forming apparatuses from the perspective of cost reduction. Even when the number of durable sheets increases, electrophotographic members with excellent toner cleaning characteristics have been required. Patent Document 1 discloses a technique for suppressing wear of a belt and a cleaning blade and stably removing transfer residual toner over a long period by having an intermediate transfer body in an image forming apparatus with a layer having a plurality of grooves formed along a predetermined direction and the average interval between adjacent grooves being within a predetermined range.

[0003] In addition, in an electrophotographic image forming apparatus, in order to achieve high color reproducibility, a correction toner image is formed on an intermediate transfer belt, the correction image is detected by an optical sensor, and image forming conditions are controlled based on the detection result. At that time, the optical sensor detects the correction image using reflected light from a portion without toner and reflected light from the toner. When light is irradiated from a light source of an optical sensor onto the surface of an intermediate transfer body having regular grooves on its surface like the intermediate transfer body described in Patent Document 1, diffraction occurs in the reflected light due to the grooves. Then, when diffracted light is generated, there has been a problem that the amount of reflected light greatly fluctuates when the intermediate transfer body moves in the circumferential direction, and the detection accuracy of the correction image by the optical sensor decreases. On the other hand, Patent Document 2 describes how the intensity of diffracted light is reduced by providing grooves with regularly changing spacing between them on the surface of the intermediate transfer body, thereby suppressing fluctuations in sensor output within one circumference of the intermediate transfer body and improving the detection accuracy of the corrected image by the optical sensor. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2019-191511 [Patent Document 2] Japanese Patent Publication No. 2021-001954 [Overview of the project] [Problems that the invention aims to solve]

[0005] Patent Document 2 describes how the detection accuracy of the corrected image by the optical sensor is improved by regularly changing the spacing between the grooves. On the other hand, even in electrophotographic rotating bodies where the spacing between grooves is constant, there is a need to reduce the intensity of diffracted light and improve the detection accuracy of the corrected image by the optical sensor. The inventors conducted further studies with reference to Patent Document 2. In the process, they recognized that when the average spacing of the grooves becomes 10.0 μm or less, the effect of diffracted light becomes significant, and the detection accuracy of the corrected image by the optical sensor decreases.

[0006] The object of this disclosure is to provide an electrophotographic rotating body having a surface layer, in which the surface layer has grooves and the average groove spacing is 10.0 μm or less, the variation in the amount of reflected light when rotated is small, and the toner cleaning characteristics are excellent over a long period of time. Another object of this disclosure is to provide an electrophotographic image forming apparatus having the electrophotographic rotating body. It is to provide. [Means for solving the problem]

[0007] According to one aspect of this disclosure, A rotating body for electrophotography having a surface layer, On the outer surface of the surface layer, A plurality of grooves extending substantially in the rotational direction of the electrophotographic rotating body and formed to be regularly arranged in a direction perpendicular to the substantially rotational direction, Multiple irregularly occurring depressions, It exists, The average spacing between these multiple grooves is 2.0 to 10.0 μm. The recess exists such that, when the electrophotographic rotating body is viewed from the outer surface side, a portion of the wall flanking the groove is cut out in an arc shape. When drawing a circle based on the arc shape of the wall cut out by the recess, The average diameter of the circle is 0.5 to 4.5 μm. The average of the nearest distances between the centers of the multiple circles drawn is greater than the average diameter of the circles, and is 10.0 μm or less. Assuming there is no notch due to the recess, the wall extends substantially in the direction of rotation of the electrophotographic rotating body so as to maintain a constant width of the groove.

[0008] Furthermore, according to other aspects of this disclosure, An image carrier that holds the toner image, A movable intermediate transfer body onto which the toner image is transferred from the image carrier, An electrophotographic image forming apparatus having an optical sensor that irradiates light onto the intermediate transfer body and detects reflected light, On the outer surface of the intermediate transfer body, A plurality of grooves extending in the direction of movement of the intermediate transfer body and formed to be regularly arranged in a direction perpendicular to the direction of movement of the intermediate transfer body, Multiple irregularly occurring depressions, It exists, The average spacing between these multiple grooves is 2.0 to 10.0 μm. The recess exists such that, when the intermediate transfer body is viewed from the outer surface side, a portion of the wall flanking the groove is cut out so that it forms an arc shape. When drawing a circle based on the arc shape of the wall cut out by the recess, The average diameter of the circle is 0.5 to 4.5 μm. The average value of the minimum distances between the centers of the plurality of circles to be drawn is greater than the average diameter of the circles and is 10.0 μm or less, When it is assumed that there is no notch due to the recess, there is provided an electrophotographic image forming apparatus in which the wall extends in the moving direction of the intermediate transfer member so as to keep the width of the groove constant.

Advantages of the Invention

[0009] According to one aspect of the present disclosure, in a rotating body for electrophotography having a surface layer, even when the surface layer has grooves and the average interval of the grooves is 10.0 μm or less, there is provided a rotating body for electrophotography in which the variation in the amount of reflected light when rotationally driven is small and the toner cleaning characteristics are excellent over a long period. Further, according to another aspect of the present disclosure, there is provided an electrophotographic image forming apparatus having the rotating body for electrophotography.

Brief Description of the Drawings

[0010] [Figure 1] Schematic view showing the configuration of the outer surface of the electrophotographic belt [Figure 2] Schematic view showing a cross section in a direction orthogonal to the circumferential direction of the electrophotographic belt [Figure 3] Schematic view showing a cross section in a direction orthogonal to the circumferential direction of the electrophotographic belt [Figure 4] Schematic view showing an example of the configuration of an image forming apparatus of an intermediate transfer system [Figure 5] Schematic view showing an example of the configuration of a density detection sensor [Figure 6] Schematic view showing an example of the output variation of the density detection sensor [Figure 7] Explanatory view of the evaluation result of the angular distribution characteristics of reflected light in an electrophotographic belt having grooves [Figure 8] Schematic view showing an example of a method for manufacturing an electrophotographic belt using an extrusion blow molding machine [Figure 9] Schematic view showing the configuration of an imprint processing apparatus for forming grooves on the surface of an electrophotographic belt [Figure 10] Schematic view showing the configuration of a convex pattern of a cylindrical mold [Figure 11]Diagram illustrating the method for measuring depressions. [Figure 12] Diagram illustrating the method for measuring groove shape or concave shape of depressions. [Figure 13] Schematic diagram showing a method for measuring the shape of electrophotographic components. [Modes for carrying out the invention]

[0011] In this disclosure, descriptions of numerical ranges such as "XX or greater and YY or less" or "XX to YY" mean a numerical range that includes the lower and upper limits, unless otherwise specified. When numerical ranges are described in steps, the upper and lower limits of each numerical range can be any combination. In addition, in this disclosure, a description such as "at least one selected from the group consisting of XX, YY, and ZZ" means any of the following: XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, or a combination of XX, YY, and ZZ. Note that if XX is a group, multiple values ​​may be selected from XX, and the same applies to YY and ZZ.

[0012] The inventors of this invention conducted research to obtain a rotating electrophotographic body that exhibits excellent toner cleaning characteristics over the long term and small fluctuations in reflected light intensity when rotated. As a result, they confirmed that by cutting out a portion of the wall flanking the regularly arranged grooves in an arc shape with irregularly arranged indentations, thereby disrupting the regular shape of the grooves, the peak intensity of the diffracted light was weakened. Based on these results, the inventors concluded that by disrupting the regular shape of the grooves, it is possible to reduce fluctuations in the amount of reflected light in the rotational direction of the electrophotographic rotating body.

[0013] In other words, this disclosure is, A rotating body for electrophotography having a surface layer, On the outer surface of the surface layer, A plurality of grooves extending substantially in the rotational direction of the electrophotographic rotating body and formed to be regularly arranged in a direction perpendicular to the substantially rotational direction, Multiple irregularly occurring depressions, It exists, The average spacing between these multiple grooves is 2.0 to 10.0 μm. The recess exists such that, when the electrophotographic rotating body is viewed from the outer surface side, a portion of the wall flanking the groove is cut out in an arc shape. When drawing a circle based on the arc shape of the wall cut out by the recess, The average diameter of the circle is 0.5 to 4.5 μm. The average of the nearest distances between the centers of the multiple circles drawn is greater than the average diameter of the circles, and is 10.0 μm or less. The present invention relates to an electrophotographic rotating body, wherein, assuming the absence of a notch due to the recess, the wall extends substantially in the rotational direction of the electrophotographic rotating body so as to maintain a constant width of the groove.

[0014] The following describes in detail an electrophotographic belt as a rotating body for electrophotography according to one aspect of this disclosure. However, this disclosure is not limited to the following aspect.

[0015] Figure 1 is a schematic diagram showing the configuration of the outer surface of the electrophotographic belt.

[0016] <Electrophotographic belt> In the electrophotographic belt 5 having a surface layer, there are multiple grooves 200 and depressions 201 on the outer surface of the surface layer. The grooves 200 are provided so as to extend in the circumferential direction (rotational direction) of the electrophotographic belt 5. In Figure 1, the grooves 200 are arranged regularly with a constant width and spacing. Specifically, there are multiple grooves 200 on the outer surface of the surface layer that are formed to be regularly arranged in a direction perpendicular to the rotational direction. The surface layer also has walls 202 that sandwich the grooves 200. In addition, in Figure 1, the part of the outer surface of the surface layer other than the grooves 200 and depressions 201 is flat.

[0017] On the other hand, the multiple depressions 201 are arranged irregularly. Specifically, there are multiple irregularly occurring depressions 201 on the outer surface of the surface layer. When the electrophotographic belt is viewed from the outer surface side, the depressions 201 cause a portion of the wall 202 that sandwiches the groove 200 to be cut out in an arc shape. As a result, the regular shape of the groove is disrupted. Furthermore, assuming there is no notch by the recess 201, the wall 202 extends in the circumferential direction of the electrophotographic belt so as to maintain a constant width of the groove 200. Assuming there is no notch by the recess 201 means, for example, that the shape of the groove 200 in the portion of the groove 200 that extends in the circumferential direction of the electrophotographic belt that is not notched by the recess 201 is assumed to extend in the circumferential direction of the electrophotographic belt 5 and that the recess 201 does not exist.

[0018] Figure 2 shows a cross-sectional view of the portion of the electrophotographic belt 5 that does not include the depression 201 in a direction perpendicular to the circumferential direction (dashed line A in (B) in Figure 1). In Figure 2, W represents the width of the groove, H represents the depth of the groove, and P represents the spacing between the grooves. Next, Figure 3 shows a cross-sectional view of the portion of the electrophotographic belt 5 that includes the depression 201 in a direction perpendicular to the circumferential direction (dashed line B in (B) in Figure 1). The depression 201 disrupts the regular shape of the groove, and there are parts where the opening width widens. Also, in Figure 3, there are depressions 201A that are not in contact with the groove. Thus, irregular concave shapes exist on the outer surface of the surface layer due to the depression 201.

[0019] Multiple grooves 200 are provided on the electrophotographic belt 5. The average spacing between the multiple grooves 200 is 2.0 to 10.0 μm, from the viewpoint of enabling stable toner cleaning. Preferably, the average spacing between the multiple grooves 200 is 3.0 to 10.0 μm, and more preferably 5.0 to 10.0 μm. If the average spacing is wider than 10.0 μm, the area of ​​the cleaning blade in contact with the non-grooved portion increases, resulting in greater friction between the cleaning blade and the electrophotographic belt. Consequently, when the electrophotographic belt is used over a long period, the cleaning blade is more likely to wear down, leading to a decrease in cleaning performance. Furthermore, if the average spacing is narrower than 2.0 μm, the area with grooves in the surface layer increases excessively. As a result, toner is more likely to be placed on the grooves, and the decrease in the transferability of the toner on the grooves becomes apparent, which is undesirable.

[0020] The average width (W) of the groove 200 is preferably 0.1 to 3.0 μm, more preferably 0.2 to 2.0 μm, and particularly preferably 0.5 to 2.0 μm. An average width of 0.1 μm or more is preferable because it reduces the possibility of the groove disappearing due to wear on the electrophotographic belt surface. An average width of 3.0 μm or less is preferable because it makes it less likely for the toner to get stuck in the groove, reducing the transferability of the toner and making it less likely for the deterioration of image quality to become apparent.

[0021] The average depth (H) of the groove 200 is preferably 0.1 to 5.0 μm, and more preferably 0.2 to 2.0 μm. A depth of 0.1 μm or more is preferable because it reduces the possibility of the groove disappearing due to wear on the electrophotographic belt surface. A depth of 5.0 μm or less is preferable because it tends to improve the durability of the electrophotographic belt.

[0022] The average spacing, average width, and average depth of the 200 grooves are measured by observing the grooves at 150x magnification using a laser microscope (product name: VK-X200, manufactured by Keyence Corporation). First, a reference plane of the electrophotographic belt is defined in the cross-sectional profile obtained using a laser microscope. Since the surface of an electrophotographic belt typically has a flat portion, this flat portion is set as the reference plane. There are areas on the cross-sectional profile where grooves are formed relative to this reference plane. These areas are defined as grooves. Specifically, as shown in Figure 12, among the portions with a depth of 0.01 μm or more relative to the reference plane, portions that extend in the approximate circumferential direction of the electrophotographic belt and are regularly arranged in a direction perpendicular to this approximate circumferential direction are defined as grooves, and the region of these grooves is defined as the entire portion below the reference plane. The groove shape is the shape of the boundary between the groove and the non-groove portion.

[0023] Measurements are taken at a total of 18 points: 3 points in the width direction and 6 points in the circumferential direction (rotation direction) of the electrophotographic belt. Width direction measurements are taken at 0mm and ±100mm from the center of the electrophotographic belt's width direction. The sign indicates the measurement position relative to the reference position. That is, the -100mm position is point-symmetric to the +100mm position with respect to the 0mm position. Circumferential measurements are taken at intervals of 1 / 6 of the circumferential length. From the cross-sectional profile, at least 10 groove shapes are measured at each measurement point. Then, the arithmetic mean values ​​of the width, depth, and spacing measured from all groove shapes at a total of 18 measurement points are used as the average groove width, average groove depth, and average spacing between multiple grooves, respectively.

[0024] In Figure 1, the multiple grooves 200 extend in the circumferential direction of the electrophotographic belt and are formed to be regularly aligned in a direction perpendicular to the circumferential direction; however, the disclosure is not limited to this embodiment. For example, the direction in which the multiple grooves extend may be the substantially circumferential direction (substantially rotational direction) of the electrophotographic belt. Also, when the direction in which the multiple grooves extend is designated as the first direction, the multiple grooves may be formed to be regularly aligned in a direction perpendicular to the first direction. Furthermore, assuming there is no notch by the recess 201, the wall 202 may extend in the substantially circumferential direction of the electrophotographic belt so as to maintain a constant width for the grooves 200. In this disclosure, the substantially circumferential direction (substantially rotational direction) is not particularly limited as long as the toner cleaning characteristics are exhibited. For example, if the direction in which the multiple grooves extend is defined as the first direction, the multiple grooves can be said to extend substantially in the circumferential direction if the angle between the first direction and the circumferential direction is 0° to 10°. The angle between the first direction and the circumferential direction is preferably 0° to 5°, and more preferably 0° to 1°.

[0025] Next, the indentations 201 will be described. Multiple indentations 201 are provided on the electrophotographic belt 5. The indentations 201 are irregularly arranged on the surface of the electrophotographic belt 5. Specifically, there are multiple irregularly arranged indentations 201 on the outer surface of the surface layer. The indentations 201 reduce the intensity of diffracted light originating from the regularly arranged grooves 200 by cutting out a portion of the wall between the grooves so that it forms an arc shape when the electrophotographic belt 5 is viewed from the outer surface side. There may also be indentations 201A on the outer surface of the surface layer that are not in contact with the grooves. The average diameter of the circle drawn based on the arc shape of the wall cut out by the recess (hereinafter also referred to as the average diameter of the recess) is 0.5 to 4.5 μm, from the viewpoint of enabling stable detection of reflected light amount by the optical sensor. If the average diameter of the recess is less than 0.5 μm, the diffracted light cannot be sufficiently reduced. If the average diameter of the recess exceeds 4.5 μm, the toner will get into the recess. The indentation can become embedded, reducing the transferability of the toner. The average diameter of the indentation is preferably 1.0 to 4.5 μm, and more preferably 2.0 to 4.5 μm. The method for adjusting the average diameter of the indentation will be described later.

[0026] When circles are drawn based on the arc shape of the wall cut out by recess 201, the average of the closest proximity distances between the centers of the multiple circles drawn is greater than the average diameter of the circles and less than or equal to 10.0 μm, from the viewpoint of enabling stable detection of reflected light amount by the optical sensor. The closest proximity distance between the centers of the multiple circles referred to here is the minimum value obtained by calculating the distance from the center of one of the circles drawn when circles are drawn based on the arc shape of the wall cut out by recess 201 to the centers of the surrounding circles. Hereafter, the closest proximity distance between the centers of the multiple circles will also be referred to as the closest proximity distance between recesses. The method for adjusting the average value of the closest proximity distance between recesses will be described later.

[0027] When the nearest distance between two depressions is equal to the average diameter of the circles, the circles are in contact with each other. As a result, the depressions impart a regular shape, and the diffracted light cannot be sufficiently reduced. Furthermore, when the nearest distance exceeds 10 μm, the number of depressions is small, and the intensity of the diffracted light cannot be sufficiently reduced. The average of the closest proximity distances between the centers of multiple circles is preferably greater than the average diameter of the circles and 9.0 μm or less, more preferably greater than the average diameter of the circles and 7.0 μm or less, and even more preferably greater than the average diameter of the circles and 6.0 μm or less. The average of the closest distances between the centers of multiple circles is preferably 1.5 times or more the average diameter of the circles, and more preferably 2.0 times or more the average diameter of the circles.

[0028] The average diameter of depression 201 and the average closest distance between depressions are measured by observing the depressions using a laser microscope (product name: VK-X200, manufactured by Keyence Corporation) with a 150x objective lens. In this observation, shape image data is acquired, and the major axis, minor axis, and centroid (geometric center) of each individual depression within the observation field are evaluated. I will now explain the specific measurement method.

[0029] First, a reference plane for the electrophotographic belt is defined in the cross-sectional profile obtained using a laser microscope. Since the surface of an electrophotographic belt typically has a flat area, this flat area is set as the reference plane. There are areas on the cross-sectional profile where depressions are formed relative to this reference plane. These areas are defined as depressions. Specifically, as shown in Figure 12, areas with a depth of 0.01 μm or more relative to the reference plane, excluding grooves, are defined as depressions, and the region of these depressions is defined as the entire area below the reference plane. The concave shape of the depression is the shape of the boundary between this depression and the area outside the depression.

[0030] For each depression, first determine its centroid. The centroid is defined as the center of the smallest circumscribed circle that circumscribes the concave shape of the depression (Figure 13 (2)). Of the width passing through this centroid, the longest width to the edge of the concave shape is defined as the major axis (WL), and the shortest width is defined as the minor axis (WS) (Figure 13 (3)). The square root of the product of the major axis and the minor axis is defined as the diameter of the depression. Calculate the diameters of all depressions within the field of view, and calculate the arithmetic mean of all the diameters to determine the average diameter of the depressions. In addition, calculate the distance between the centroids of the depressions surrounding each depression, and define the smallest distance as the nearest tangent distance for each depression. Finally, measure the nearest tangent distance between all depressions within the field of view and calculate the arithmetic mean.

[0031] The electrophotographic belt 5 is not particularly limited as long as it has a surface layer. For example, the electrophotographic belt may have a base layer, or an elastic layer on the base layer. The surface layer may be formed on the base layer, or the surface layer may be formed on the elastic layer. As a method for processing the base layer, known methods for processing thermoplastic resins or thermosetting resins can be used. As a method for processing thermoplastic resins, for example, the base layer can be obtained by pelletizing the resin composition and molding it using known molding methods such as continuous melt extrusion molding, injection molding, stretch blow molding, or inflation molding. The method for processing the elastic layer can be the same as the method for processing the base layer.

[0032] As for the processing method of the surface layer, the surface layer can be obtained by forming it on the base layer or elastic layer using known molding methods such as dip coating, spray coating, flow coating, shower coating, roll coating, spin coating, or ring coating. For forming grooves in the surface layer, known processing methods such as cutting, etching, or imprinting can be used. From the viewpoint of groove reproducibility and processing cost, imprinting is preferred. Imprinting can be used as a processing method for forming depressions. By adding a convex shape for forming grooves and depressions to the imprinting mold, grooves and depressions can be processed simultaneously. By changing the convex shape at this time, the average diameter of the depressions and the average value of the nearest distance between depressions can be changed. Alternatively, imprinting may be performed using a mold for forming depressions after the grooves have been formed. As another method, the above surface layer processing method may be performed using a coating liquid for the surface layer that has been prepared to create depressions in the surface layer.

[0033] One method of using a coating solution for a surface layer that is prepared to create depressions in the surface layer is to use a coating solution that contains hydrocarbon oil. The depressions can be created by using a coating solution obtained by adding hydrocarbon oil to a resin-based paint containing, for example, acrylate or methacrylate. For example, a base layer is obtained by the method described above. Then, the coating solution is applied to the base layer and the solvent is evaporated. After that, the hydrocarbon oil is removed by wiping off the resulting coating film. This makes it possible to obtain a surface layer with depressions formed therein. Resin-based coatings may contain, for example, a resin, or a polymerizable monomer for forming a resin. When a resin-based coating contains a polymerizable monomer, the polymerizable monomer may be polymerized on the base layer by UV irradiation or other means at least before and after the evaporation of the solvent. Hereinafter, at least one selected from the group consisting of resin and polymerizable monomer for forming a resin will be referred to as the resin component.

[0034] Although the detailed mechanism is not understood, it is presumed that hydrocarbon oil dissolved in the solvent in the coating solution remains on the coating surface as the solvent evaporates, and that the depressions are formed when the hydrocarbon oil is removed after the coating hardens. The hydrocarbon oil content in the coating solution is not particularly limited, but is preferably 3.0 to 18.0 parts by mass, more preferably 4.0 to 15.0 parts by mass, even more preferably 4.0 to 11.0 parts by mass, and particularly preferably 4.0 to 6.0 parts by mass per 100 parts by mass of resin component. The size of the depressions (circle diameter and depth) and the distance between depressions (number of depressions) change depending on the hydrocarbon oil content, so the hydrocarbon oil content should be adjusted according to the desired size. However, within the above range, it is easier to set the average diameter of the depressions and the average nearest distance between depressions within a suitable range.

[0035] The hydrocarbon oil is not particularly limited, but it is preferably liquid at room temperature (23-30°C). That is, the melting point of the hydrocarbon oil is preferably 30°C or lower, and more preferably 23°C or lower. Examples of hydrocarbon oils include aliphatic compounds having 8 to 18 carbon atoms (preferably 10 to 18, more preferably 14 to 18). The aliphatic compound is not particularly limited and may be linear, branched, or alicyclic. Preferably, the aliphatic compound is a chain-type saturated hydrocarbon compound.

[0036] The thickness of the electrophotographic belt 5 is preferably 10 μm or more and 500 μm or less, and particularly preferably 30 μm or more and 150 μm or less.

[0037] The electrophotographic rotating body may be used as an electrophotographic belt, or it may be used by winding it around or covering a drum or roll used as an electrophotographic component. That is, for example, the electrophotographic rotating body may be an electrophotographic belt. The electrophotographic belt may also be used as an intermediate transfer body. That is, for example, the electrophotographic rotating body may be an intermediate transfer belt. The shape of the electrophotographic belt is not particularly limited, but an endless belt shape is preferred.

[0038] <Electrophotographic image forming apparatus> Figure 4 shows an example of an image forming apparatus that incorporates an electrophotographic belt based on this disclosure as an intermediate transfer body, and is configured as an electrophotographic apparatus.

[0039] The electrophotographic image forming apparatus comprises an image carrier that holds a toner image, a movable intermediate transfer body onto which the toner image is transferred from the image carrier, and an optical sensor that irradiates light onto the intermediate transfer body and detects the reflected light. The electrophotographic image forming apparatus has, for example, an electrophotographic rotating body as an intermediate transfer body. In this case, the rotation direction of the electrophotographic rotating body corresponds to the movement direction of the intermediate transfer body. That is, on the outer surface of the intermediate transfer body, Multiple grooves are formed to extend in the direction of movement of the intermediate transfer body and to be regularly arranged in a direction perpendicular to the direction of movement of the intermediate transfer body, There are multiple irregularly placed depressions, The average spacing between the multiple grooves is 2.0 to 10.0 μm. The depression exists when the intermediate transfer body is viewed from the outer surface side, with a portion of the wall surrounding the groove cut out in an arc shape. When drawing a circle based on the arc shape of the wall cut out by the recess, The average diameter of the circles is 0.5 to 4.5 μm. The average of the nearest distances between the centers of the multiple circles drawn is greater than the average diameter of the circles, and less than or equal to 10.0 μm. Assuming there are no notches due to depressions, the walls extend in the direction of movement of the intermediate transfer body so as to maintain a constant width of the groove.

[0040] The image forming apparatus uses four toners, represented by C (cyan), M (magenta), Y (yellow), and K (black), to form color images on a recording medium S such as paper supplied from a paper feed cassette 20. The image forming apparatus has image forming stations for each color arranged in a roughly horizontal direction. Each of these image forming stations is equipped with a photosensitive drum 1c, 1m, 1y, and 1k. Here, the subscripts "c," "m," "y," or "k" are added to the reference symbols to indicate which color image forming station the component with the reference symbol belongs to.

[0041] The image forming apparatus is equipped with a laser scanner 3, which is a laser optical unit. From this unit, laser beams 3c, 3m, 3y, and 3k corresponding to the image signals of each color are emitted towards the respective photosensitive drums 1c, 1m, 1y, and 1k. Since all image forming stations have the same structure, the image forming station for the K color will be described here. The photosensitive drum 1k is surrounded by a conductive roller 2k, which is a contact charging device, a developer unit 4k, a conductive roller 8k which is a primary transfer roller, and a toner recovery blade 14k used for cleaning the photosensitive drum 1k. The developer unit 4k contains a developing roller 41k, which is a developer material carrier that develops the latent image on the photosensitive drum 1k, and a toner supply to the developing roller 41k. The device includes a developing container 42k for holding toner and a developing blade 43k for regulating the amount of toner on the developing roller 41 and applying an electric charge.

[0042] The electrophotographic belt 5 is configured as an endless belt and is provided in common to each color image forming station. It is stretched over the secondary transfer opposing roller 92, tension roller 6, and drive roller 7, and is rotated in the direction of the arrow shown by the drive roller 7. In the section between the tension roller 6 and the drive roller 7, the electrophotographic belt 5 sequentially contacts the surfaces of the photosensitive drums 1c, 1m, 1y, and 1k, and is pressurized towards the photosensitive drums 1c, 1m, 1y, and 1k by the primary transfer rollers 8c, 8m, 8y, and 8k, respectively. As a result, the toner images formed on the surfaces of the photosensitive drums 1c, 1m, 1y, and 1k are transferred to the surface of the electrophotographic belt 5, which is an intermediate transfer body. A secondary transfer roller 9 is provided opposite the opposing roller 92, and the electrophotographic belt 5 is pressed towards the opposing roller 92 by the secondary transfer roller 9. A secondary transfer voltage is applied to the secondary transfer roller 9 from the power supply via a current detection circuit 10. The secondary transfer section is formed by the secondary transfer roller 9 and the opposing roller 92.

[0043] The recording medium S passes through the feeding roller 12 and the transport roller 13, and at the position of the opposing roller 92, it passes through the nip between the electrophotographic belt 5 and the secondary transfer roller 9, thereby transferring the toner image held on the outer surface of the electrophotographic belt 5. As a result, an image is formed on the surface of the recording medium S. The recording medium S onto which the toner image has been transferred passes through a fuser 15 consisting of a pair of rollers, a heating roller 151 and a pressure roller 152, thereby fixing the image, and the recording medium is discharged into the output tray 21.

[0044] A cleaning blade 11 is provided at the position of the tension roller 6, which contacts the outer surface of the electrophotographic belt 5. Toner that remains on the outer surface of the electrophotographic belt 5 without being transferred to the recording medium S is scraped off and removed by the cleaning blade 11. The cleaning blade 11 is a component that extends in a direction substantially perpendicular to the direction of movement of the electrophotographic belt 5. There are no particular restrictions on the cleaning blade 11 as long as it is suitable for toner cleaning, but examples include urethane rubber, acrylic rubber, nitrile rubber, and EPDM rubber, and urethane rubber is preferred from the viewpoint of toner cleaning.

[0045] The color of printed materials changes depending on the operating environment and other conditions of the image forming apparatus. Therefore, it is necessary to measure the density as needed and provide feedback to the control mechanism inside the unit. The toner image for density correction is transferred to the surface of the electrophotographic belt 5 and then transported to the position of the drive roller 7 as the electrophotographic belt 5 rotates. The toner density is detected by a density detection sensor 160 located on the opposite side of the electrophotographic belt 5 from the drive roller 7.

[0046] Figure 5 is a schematic diagram of the density detection sensor (optical sensor) 160. The density detection sensor 160 consists of a light-emitting element 161, a specular reflection light-receiving element 163, and a diffuse reflection light-receiving element 162. The light-emitting element 161 emits infrared light, and this light is reflected from the surface of the toner image T. The specular reflection light-receiving element 163 is positioned in the specular reflection direction relative to the position of the toner image T and detects the specularly reflected light at the position of the toner image T. The diffuse reflection light-receiving element 162 is positioned in a position other than the specular reflection direction relative to the toner image T and detects the diffusely reflected light at the position of the toner image T. The voltage values ​​detected by each are called the specular reflection output and the diffuse reflection output.

[0047] Figure 6A is a schematic diagram illustrating the specular reflection output fluctuation 401 and diffuse reflection output fluctuation 402 with respect to image density, and the sensor output fluctuation 403 calculated from these. If the amount of toner is low, the reflection from the surface of the electrophotographic belt 5, which has a smooth mirror surface, is increased. To detect light, the specular reflection output increases. As the amount of toner increases, the specular reflection output decreases. When the amount of toner increases and the number of toner layers exceeds one, the specular reflection component from the electrophotographic belt 5 surface is almost eliminated. However, since the specular reflection output includes both specular and diffuse reflection components, the specular reflection output does not decrease monotonically in areas of high density. On the other hand, diffuse reflection output increases monotonically with increasing toner volume. However, the amount of change is smaller compared to specular reflection output. By removing the diffuse reflection component obtained from the diffuse reflection output (hereinafter referred to as sensor output) from the specular reflection output, a sensor output fluctuation 403 correlated with image density can be obtained.

[0048] Figure 6B is an overview diagram illustrating the background output 404 at multiple locations on the electrophotographic belt 5, and the patch output 405 at those locations. Background output refers to the sensor output when there is no toner, and patch output refers to the sensor output when there is toner. As shown in Figure 6B, the background output 404 fluctuates at the position of the electrophotographic belt 5. Specifically, the specular reflection output changes because the reflectivity and surface shape differ locally at the position of the electrophotographic belt 5. As a result, the background output 404, which is the sensor output, fluctuates. The patch outputs 405 all detect toner images formed with the same halftone density. And, like the background output 404, they fluctuate at the same position. Therefore, if image density control is performed using the patch output 405 itself, the accuracy of image density control will decrease due to the fluctuation of the background output 404. For this reason, it is preferable that the specular reflection output, which is the main component of the background output, is uniform.

[0049] Fluctuations in specular reflection output occur due to the following reasons. Specifically, the reflection characteristics from the surface of the electrophotographic belt 5 differ depending on the position of the electrophotographic belt 5 (in the circumferential and widthwise directions). With each rotation of the electrophotographic belt 5, the position of the electrophotographic belt 5 shifts slightly relative to the position where the light-emitting element 161 is irradiated, due to tolerances in the outer diameter of the drive roller 7, tolerances in the circumference of the electrophotographic belt 5, and movement of the electrophotographic belt 5 in the widthwise direction. This results in differences in the amount of reflected light with each rotation of the electrophotographic belt 5. Furthermore, variations in the reflection characteristics from the surface of the electrophotographic belt 5 occur because the intensity of diffracted light and the reflection angle differ depending on the position of the electrophotographic belt 5 (in the circumferential and widthwise directions), due to variations in the groove shape (groove spacing and depth) of the surface.

[0050] Figure 7 shows the results of measuring the angular distribution characteristics of reflected light from an electrophotographic belt with grooves spaced 3.5 μm apart, 1.5 μm wide, and 0.5 μm deep on its surface. This evaluation measured the angular distribution characteristics of reflected light when irradiated with light of wavelength λ 622 nm at an incident angle of -20°, and normalized the distribution by the peak value. The peak at +20° originates from specular reflection, while the peaks at +10° and +30° are peaks due to first-order diffracted light. The generation of diffracted light can reduce the amount of reflected light received by the specular reflection photodetector 163, or the diffracted light may unintentionally mix into the diffuse reflection photodetector 162. Therefore, it is necessary to suppress the intensity of diffracted light as much as possible. The electrophotographic belt of this disclosure can suppress the intensity of diffracted light. [Examples]

[0051] Examples and comparative examples are shown below to illustrate the present disclosure in detail, but the present disclosure is not limited to these.

[0052] (Example 1) [Base layer manufacturing] First, a thermoplastic resin composition was prepared by hot-melt kneading the following base material in the ratio PEN / PEEA / CB = 84 / 15 / 1 (mass ratio) using a twin-screw extruder (product name: TEX30α, manufactured by Japan Steel Works, Ltd.). The hot-melt kneading temperature was adjusted to be within the range of 260°C to 280°C, and the hot-melt kneading time was 3 to 5 minutes. The obtained thermoplastic resin composition was then processed. The material was pelletized and dried at 140°C for 6 hours. ·Base material PEN: Polyethylene naphthalate (Product name: TN-8050SC, manufactured by Teijin Chemicals Ltd.) PEEA: Polyether ester amide (Product name: Perestat NC6321, manufactured by Sanyo Chemical Industries, Ltd.) CB: Carbon Black (Product Name: MA-100, manufactured by Mitsubishi Chemical Corporation)

[0053] Next, the dried pelletized thermoplastic resin composition was placed into an injection molding machine (product name: SE180D, manufactured by Sumitomo Heavy Industries, Ltd.). Then, with the cylinder temperature set to 295°C, the mixture was injection molded into a mold heated to 30°C to produce a preform. The resulting preform had the shape of a test tube with an outer diameter of 50 mm, an inner diameter of 46 mm, and a length of 100 mm.

[0054] Next, the preform described above was biaxially stretched using the biaxial stretching apparatus (stretch blow molding machine) shown in Figure 8. Before biaxial stretching, the preform 104 was placed in a heating device 107 equipped with a non-contact type heater (not shown) for heating the outer and inner walls of the preform 104, and the heating device was used to heat the outer surface temperature of the preform to 150°C. Next, the heated preform 104 was placed in a blow mold 108, which was maintained at a mold temperature of 30°C, and stretched axially using a stretching rod 109. At the same time, air heated to 23°C was introduced into the preform from the blow air injection section 110 to stretch the preform 104 radially. In this way, a bottle-shaped molded product 112 was obtained. Next, the body of the obtained bottle-shaped molded product 112 was cut to obtain a seamless electrophotographic belt base layer. The thickness of this electrophotographic belt base layer was 70.2 μm, the circumference was 712.2 mm, and the width was 244.0 mm.

[0055] [Formulation of coating solution] In this embodiment, in order to suppress the influence of diffracted light caused by grooves formed regularly on the outer surface of the electrophotographic belt 5 on the output of the density detection sensor 160, depressions are irregularly arranged on the outer surface of the electrophotographic belt 5. In this embodiment, depressions are obtained by using a coating solution containing a UV-curable acrylate with added hydrocarbon oil. Although the detailed mechanism is not known, it is presumed that the hydrocarbon oil dissolved in the solvent in the coating solution remains on the surface of the coating film as the solvent evaporates, and that the circular depressions are formed when the hydrocarbon oil is removed after the coating film has hardened.

[0056] Since hydrocarbon oils are preferably liquid in the coating environment, i.e., at room temperature (23-30°C), it is best to use one with a melting point below room temperature. In this example, hexadecane with a melting point of 18°C ​​was used. The following surface layer materials were weighed in the ratio AN / PTFE / GF / SL / IRG / HD = 64 / 19 / 1 / 12 / 1 / 3 (SL is the mass ratio based on solid content only), and a solution was prepared by coarsely dispersing the materials excluding SL. The obtained solution was then dispersed using a high-pressure emulsification disperser (product name: NanoVeta, manufactured by Yoshida Machinery Industry Co., Ltd.). This dispersion treatment was continued until the 50% average particle size of the PTFE contained in the solution reached 200 nm. Furthermore, while stirring the SL, the liquid from the dispersion treatment was added dropwise, and finally, MEK (methyl ethyl ketone) was added as a diluent at a ratio of 30 parts by mass per 100 parts by mass of the liquid to obtain a coating solution for surface layer formation. The PTFE particle size in the coating solution was measured using a concentrated particle size analyzer (product name FPAR-1000, manufactured by Otsuka Electronics Co., Ltd.) based on dynamic light scattering (DLS) technology (ISO-DIS22412).

[0057] AN: Dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (product name: Aronics M-402, manufactured by Toagosei Co., Ltd.) PTFE: PTFE particles (product name: LeBron L-5, manufactured by Daikin Industries, Ltd.) GF:PTFE particle dispersant (product name: GF-400, manufactured by Toagosei Co., Ltd.) SL: Zinc antimonate particle slurry (Product name: Celnax CX-Z400K, manufactured by Nissan Chemical Corporation, 40% by mass as zinc antimonate particle component) IRG: Photoinitiator (product name: Omnirad907, manufactured by IGM Resins BV) HD: Hexadecane (manufactured by Fujifilm Wako Pure Chemical Corporation)

[0058] [Formation of surface layer and depressions] The base layer obtained by blow molding was fitted onto the outer circumference of a cylindrical mold (circumference 712 mm), and the ends were sealed. The mold was then immersed in a container filled with a coating liquid for surface layer formation, and the mold was pulled up while maintaining a constant relative speed between the liquid level of the curable composition and the base layer, thereby forming a coating film on the surface of the base layer. The pulling speed (relative speed between the liquid level of the curable composition and the base layer) and the solvent ratio of the curable composition can be adjusted according to the desired film thickness. In this example, the pulling speed was set to 10-50 mm / second, and the film thickness of the surface layer was adjusted to 3 μm. In this embodiment, the coating direction refers to the direction opposite to the direction in which the base layer is lifted. That is, the point where the material is first lifted from the coating solution is the upstream end in the coating direction.

[0059] The base layer coated with the coating solution was removed from the cylindrical mold and dried for 1 minute in a 23°C environment under exhaust gas. The drying temperature and drying time were adjusted as appropriate based on the solvent type, solvent ratio, and film thickness. Subsequently, the coating film was subjected to UV irradiation using a UV irradiator (product name: UE06 / 81-3, manufactured by iGraphic Co., Ltd.) with an integrated light intensity of 600 mJ / cm². 2 The coating was cured by irradiating it with ultraviolet light until it reached the desired state.

[0060] By wiping the coating with a nonwoven fabric impregnated with MEK, a surface layer with irregularly occurring depressions was formed on the surface. The size of the depressions and the closest distance between them were measured by observing the depressions using a laser microscope (product name: VK-X200, manufactured by Keyence Corporation) with a 150x objective lens. In this observation, shape image data was acquired, and the major axis, minor axis, and centroid (geometric center) of each individual depression within the observation field were evaluated. The specific measurement method will now be explained. For each depression, the center of gravity is first determined. The center of the smallest circumscribed circle that circumscribes the concave shape of the depression was defined as the center of the circumscribed circle. Of the width passing through this center of gravity, the longest width to the edge of the concave shape was defined as the major axis, and the shortest width was defined as the minor axis. The square root of the product of the major axis and the minor axis was defined as the diameter of the depression. The diameters of all depressions within the field of view were calculated, and the arithmetic mean of all the diameters of the depressions was calculated and used as the average diameter of the depressions. In addition, the distance between the centers of gravity of the depressions surrounding each depression was calculated, and the smallest of these was defined as the nearest neighbor distance for each depression. Finally, the nearest neighbor distances between all the depressions within the field of view were measured, and the arithmetic mean was calculated. The average diameter d of the depressions obtained using this evaluation method was 1.8 μm, and the average nearest-neighbor distance D was 6.2 μm.

[0061] Furthermore, the thickness of the surface layer was determined by destructive testing, which involved cutting an electrophotographic belt prepared separately under the same conditions and observing the cross-section with an electron microscope (product name: XL30-SFEG, manufactured by FEI). The results of the destructive testing showed that the thickness of the surface layer was 3.0 μm.

[0062] [Formation of grooves] Grooves were formed in the surface layer using the imprint processing apparatus shown in Figure 9. The imprint processing apparatus consists of a cylindrical mold 81 and a cylindrical belt holder 90. The cylindrical mold 81 can apply pressure to the cylindrical belt holder 90 while keeping their respective axes parallel. At this time, the cylindrical mold 81 and the cylindrical belt holder 90 rotate synchronously without slipping. In this embodiment, the cylindrical mold 81 is electroless nickel-plated. The mold is made of carbon steel with a special coating, and has a diameter of 50 mm and a length of 250 mm. Fine convex shapes are formed on the surface of the cylindrical mold 81, and these convex patterns are formed in a spiral shape with an angle of 0.1° with respect to the circumferential direction of the cylindrical mold.

[0063] The convex pattern of the cylindrical mold used in this embodiment has the shape shown in Figure 10, with dimensions H=3.5μm, Wb=1.8μm, Wt=0.8μm, and P=3.8μm. A cartridge heater is embedded inside the cylindrical mold 81, allowing it to be heated.

[0064] A base layer 60 with a surface layer formed on it was pre-fitted onto the outer circumference of the cylindrical belt-holding mold 90 (circumference 712 mm). This was rotated together with the cylindrical mold 81 at a peripheral speed of 1 mm / sec (in opposite directions of rotation), and while maintaining the parallel axis lines of their respective bodies, the cylindrical mold 81 heated to 130°C was brought into contact with the belt-holding mold 90, and the load was increased at a rate of 1.0 kN / s until it reached 8.0 kN. Then, while maintaining the load at 8.0 kN, the cylindrical belt-holding mold 90 and the cylindrical mold 81 were rotated, and at the moment when the portion of the cylindrical belt-holding mold 90 that began to contact the cylindrical mold 81 had passed one full rotation of the cylindrical belt-holding mold 90, the load on the cylindrical mold 81 was reduced at a rate of 1.0 kN / s to release the cylindrical mold 81. This transferred the convex pattern of the cylindrical mold 81 to the surface layer, forming grooves. The characteristics and performance evaluation methods for the electrophotographic belt fabricated in this embodiment are as follows: [Evaluation 1] to [Evaluation 4].

[0065] [Evaluation 1] Evaluation of groove and recess shapes on the surface of the electrophotographic belt The grooves and depressions on the outer surface of the electrophotographic belt were observed at 150x magnification using a laser microscope (product name: VK-X200, manufactured by Keyence Corporation), and the spacing, width, and depth of the grooves, the diameter of the depressions, and the nearest neighbor distance were measured. For measuring the shape, a total of 18 points were used: 3 points in the width direction of the electrophotographic belt and 6 points in the circumferential direction (rotation direction). Measurements in the width direction were taken at 0 mm and ±100 mm from the center of the electrophotographic belt in the width direction. The sign indicates the application direction of the coating liquid relative to the reference position, with the upstream side of the application direction being positive and the downstream side being negative. That is, for example, +100 mm means 100 mm upstream from the center of the electrophotographic belt in the width direction in the application direction of the coating liquid. Measurements in the circumferential direction were taken at intervals of 1 / 6 of the circumferential length. The observation position in the circumferential direction was based on the starting position of the electrophotographic belt processing, and the direction of groove processing was considered the positive direction for evaluation.

[0066] The groove spacing, width, and depth were measured from the cross-sectional profile, with at least 10 groove shapes measured at each measurement point. The arithmetic mean values ​​of the width, depth, and spacing measured from all groove shapes at a total of 18 measurement points were used as the average groove width, average groove depth, and average groove spacing, respectively. The average groove width, average groove depth, and average groove spacing were W=1.0μm, H=0.5μm, and P=3.8μm, respectively.

[0067] The size of the grooves and the nearest neighbor distance of the electrophotographic belts with grooves added by imprint processing were evaluated using the following method. For grooves that did not intersect with the grooves, the evaluation was performed in the same manner as before imprint processing. For grooves that did intersect with the grooves, see the explanation in Figures 11A and 11B. As shown in Figure 11A, when the edge of the depression 201 intersects with only one of the first edge portion 200-1 and the second edge portion 200-2 that constitute the groove 200, the evaluation was performed as follows: The centroid was defined as the center of a circle passing through three points: the two points where the edge of the groove 200 and the edge of the depression 201 intersect, and the point on the edge of the depression 201 that is furthest from the line constituting the edge of the groove 200. The diameter of this circle was then evaluated as the diameter of the depression. Furthermore, as shown in Figure 11B, when the edge of the depression 201 intersects with both the first edge portion 200-1 and the second edge portion 200-2 that constitute the groove 200, the evaluation was performed as follows: Of the edges of the depression 201, the point furthest from the line constituting the first edge portion 201-1 and the second edge portion 20 The centroid was defined as the center of a circle passing through three points: the point furthest from the line constituting 0-2, the point furthest from the line, and two points where the first edge 200-1 and the second edge 200-2 constituting the groove 200 intersect with the edge of the depression. The diameter of this circle was then evaluated as the diameter of the depression. The average diameter d of the depressions and the average nearest-neighbor distance D were d = 1.8 μm and D = 6.2 μm, respectively, and it was confirmed that they did not change before and after the imprinting process.

[0068] [Evaluation 2] Evaluation of reflected light angle characteristics To understand the generation of diffracted light from the surface of the electrophotographic belt, the angular distribution characteristics of the reflected light from the electrophotographic belt were measured. The angular distribution characteristics of the reflected light were evaluated using the following procedure. Using a Synopsys Mini-Diff V1, the angular distribution characteristics of reflected light were measured when light with a wavelength λ of 622 nm was irradiated at an incident angle of -20°, and the distribution was normalized by the peak value. In this evaluation, the peak intensity of the first-order diffracted light was measured, focusing on specular reflection at a reflection angle of +20°, and ranked according to the following criteria. Rank A: Peak intensity of primary diffraction light is 0.10 or less. Rank B: The peak intensity of the primary diffraction light is greater than 0.10 and less than or equal to 0.20. Rank C: The peak intensity of the primary diffraction light is greater than 0.20.

[0069] When the reflected light angle characteristics of the electrophotographic belt of Example 1 were evaluated using the evaluation method described above, the peak intensity of the primary diffracted light was 0.15. From this, the electrophotographic belt of Example 1 was determined to be rank B.

[0070] [Evaluation 3] Sensing evaluation Using an electrophotographic image forming apparatus with the configuration shown in Figure 4, an electrophotographic belt was mounted as an intermediate transfer body, and the specular reflection output per rotation of the electrophotographic belt was measured in 1 mm increments. The arithmetic mean V_ave, maximum value V_max, minimum value V_min, and deflection rate were evaluated using the following formula (1). Volatility (%) = {(V_max - V_min) / V_ave} × 100 (1)

[0071] In this evaluation, a concentration detection sensor 160, whose schematic configuration is shown in Figure 5, was used. The specific configuration of the concentration detection sensor 160 is as follows. An LED with a wavelength λ = 840 nm was used as the light-emitting element 161. The light-emitting element 161, the specular reflecting light sensor as the specular reflecting light-receiving element 163, and the diffuse reflecting light sensor as the diffuse reflecting light-receiving element 162 were arranged in a line along the width direction of the electrophotographic belt. The surface of the electrophotographic belt 5 was illuminated from an incident angle θi = -20° within a circular area with a diameter of approximately 2 mm (hereinafter referred to as the "spot diameter"). The "spot diameter" is the size of the detection range of the optical sensor on the electrophotographic belt 5, and here it indicates the size of the detection range in the belt width direction. Furthermore, in this evaluation, when the direction normal to the electrophotographic belt 5 and toward the density detection sensor 160 is taken as 0°, the specular reflecting light-receiving element 163 is configured to receive reflected light from the electrophotographic belt 5 and the toner image T at an angle of +20°, and the diffuse reflecting light-receiving element 162 is configured to receive reflected light from the electrophotographic belt 5 and the toner image T at an angle of 0°.

[0072] The density detection sensor 160 is positioned at a location within ±100 mm of the widthwise center of the electrophotographic belt 5. Furthermore, since the specular reflection output changes depending on the conditions of grooves and depressions on the electrophotographic belt surface, the light intensity output was adjusted so that the specular reflection output was 3.0V at the starting point of the measurement before this evaluation was performed. The deflection rates calculated using the above method were ranked according to the following criteria. Rank A: Fluctuation rate is 5% or less Rank B: Fluctuation rate greater than 5% and less than or equal to 10% Rank C: Fluctuation rate is greater than 10%

[0073] Using the evaluation method described above, the sensing evaluation of the electrophotographic belt in this embodiment 1 was performed, and the deflection rate was found to be 8%, resulting in a rank of B.

[0074] [Evaluation 4] Evaluation of toner cleaning performance Using the electrophotographic image forming apparatus configured as shown in Figure 4, an electrophotographic belt was attached as an intermediate transfer body, and blade cleaning was performed while printing an image to evaluate the toner cleaning performance. This evaluation was conducted under conditions of 15°C and 10% relative humidity, using OCE Corporation's Extra (basis weight 80g / m²) as the recording medium S. 2 Using JIS A4 size paper, the printer performed intermittent printing of two sheets at a time, feeding paper up to a maximum of 200,000 sheets until toner cleaning occurred. The printer was evaluated based on whether or not toner leaked through the cleaning blade. Specifically, first, with the secondary transfer voltage turned off (0V), a red image (Y toner and M toner) was recorded across the entire A4 size by irradiating the photosensitive drum at 1y and 1m with laser beams at 3y and 3m. Then, the secondary transfer voltage was set to an appropriate value, and three blank sheets of paper were fed through continuously.

[0075] Since no secondary transfer voltage is applied, the Y toner and M toner transferred from the photosensitive drums 1y and 1m to the entire surface of the electrophotographic belt 5 enter the cleaning blade 11 with almost no transfer to the recording medium S in the secondary transfer section. If the toner that enters enters is removed from the electrophotographic belt 5, the next three sheets of paper passed through will be output as completely blank. On the other hand, if the toner is not removed, the remaining toner that has passed through the cleaning blade 11 will be transferred to the recording medium S in the secondary transfer section. In other words, it will be transferred onto the blank paper and output as a toner cleaning failure image on the recording medium S. The above evaluations were conducted at the points of 50,000 sheets, 100,000 sheets, 150,000 sheets, and 200,000 sheets being processed. Based on these evaluation results, the electrophotographic belts were ranked according to the following criteria.

[0076] When streaks parallel to the transport direction of the recording medium S were visually confirmed to be present on the white areas of the recording medium S, it was determined that a toner cleaning failure had occurred. Rank A: No toner cleaning failures occurred during the 200,000-sheet paper feeding process. Rank B: No toner cleaning failures occurred during the 150,000-sheet paper feeding process, but toner cleaning failures occurred during the 200,000-sheet paper feeding process. Rank C: No toner cleaning failures occurred during the 100,000-sheet paper feeding process, but toner cleaning failures occurred during the 150,000-sheet paper feeding process. Rank D: No toner cleaning failures occurred during the 50,000-sheet paper feeding process, but toner cleaning failures occurred during the 100,000-sheet paper feeding process. Rank E: A toner cleaning failure occurred during the 50,000-sheet paper feeding process.

[0077] Using the evaluation method described above, the toner cleaning characteristics of the electrophotographic belt in this embodiment 1 were evaluated, and no toner cleaning defects occurred during the 200,000-sheet paper feeding process, resulting in the determination that it is an electrophotographic belt of rank A.

[0078] (Comparative Example 1) In preparing the surface layer material, an electrophotographic belt was fabricated in the same manner as in Example 1, except that the coating solution was prepared without using hexadecane. It was confirmed that only grooves were formed on the surface, with no depressions. The evaluation results are shown in Table 1.

[0079] (Example 2) The process is the same as in Example 1, except that the groove spacing P in the convex pattern of the cylindrical mold is set to 10 μm. An electrophotographic belt was fabricated and subjected to evaluation. The evaluation results are shown in Table 1.

[0080] (Comparative Example 2) An electrophotographic belt was prepared in the same manner as in Example 2, except that the coating solution used in Comparative Example 1 was used, and then subjected to evaluation. The evaluation results are shown in Table 1.

[0081] (Example 3) An electrophotographic belt was prepared and evaluated in the same manner as in Example 1, except that the mixing ratio of the coating solution was changed to AN / PTFE / GF / SL / IRG / HD = 62 / 19 / 1 / 11 / 1 / 6 (SL is the mass ratio on a solid content basis). The evaluation results are shown in Table 1.

[0082] (Example 4) An electrophotographic belt was fabricated in the same manner as in Example 3, except that the coating solution used in Example 3 was used, and then subjected to evaluation. The evaluation results are shown in Table 1.

[0083] (Example 5) An electrophotographic belt was prepared and evaluated in the same manner as in Example 1, except that the mixing ratio of the coating solution was changed to AN / PTFE / GF / SL / IRG / HD = 65 / 20 / 1 / 12 / 1 / 1 (SL was the mass ratio on a solid content basis). The evaluation results are shown in Table 1.

[0084] (Comparative Example 3) An electrophotographic belt was prepared in the same manner as in Example 1, except that the mixing ratio of the coating solution was changed to AN / PTFE / GF / SL / IRG / HD = 65.8 / 19.8 / 1.0 / 11.9 / 1.0 / 0.5 (SL is the mass ratio on a solid content basis), and was subjected to evaluation. The evaluation results are shown in Table 1.

[0085] (Comparative Example 4) An electrophotographic belt was fabricated in the same manner as in Comparative Example 1, except that groove formation by imprinting was not performed, and then subjected to evaluation. The evaluation results are shown in Table 1. [Table 1] In the table, the content indicates the content of hydrocarbon oil per 100 parts by mass of resin component in the coating solution.

[0086] As shown in Table 1, in Examples 1 to 5, the depressions cut out a portion of the wall surrounding the groove in an arc shape, disrupting the regularity of the groove shape and thus weakening the peak intensity of the diffracted light. As a result, the deflection of the specular reflection output was small, and the sensing characteristics were excellent. On the other hand, in Comparative Examples 1 and 2, the electrophotographic belt lacked depressions, resulting in a large peak intensity of diffracted light, which led to a large deflection rate in the specular reflection output. Consequently, the sensing characteristics were inferior. Furthermore, in Comparative Example 3, although a portion of the wall flanking the groove is cut out in an arc shape by the depressions, the average value of the closest proximity distance between the depressions is large. In other words, because there are few depressions, the peak intensity of the diffracted light cannot be sufficiently weakened. As a result, the deflection rate of the specular reflection output is large, and the sensing characteristics are inferior.

[0087] This disclosure includes the following components: [Configuration 1] A rotating body for electrophotography having a surface layer, On the outer surface of the surface layer, A plurality of grooves extending substantially in the rotational direction of the electrophotographic rotating body and formed to be regularly arranged in a direction perpendicular to the substantially rotational direction, Multiple irregularly occurring depressions, It exists, The average spacing between these multiple grooves is 2.0 to 10.0 μm. The recess exists such that, when the electrophotographic rotating body is viewed from the outer surface side, a portion of the wall flanking the groove is cut out in an arc shape. When drawing a circle based on the arc shape of the wall cut out by the recess, The average diameter of the circle is 0.5 to 4.5 μm. The average of the nearest distances between the centers of the multiple circles drawn is greater than the average diameter of the circles, and is 10.0 μm or less. An electrophotographic rotating body characterized in that, assuming there is no notch due to the recess, the wall extends substantially in the direction of rotation of the electrophotographic rotating body so as to maintain a constant width of the groove. [Configuration 2] The electrophotographic rotating body according to configuration 1, wherein the average width of the grooves is 0.5 to 2.0 μm. [Configuration 3] The electrophotographic rotating body according to configuration 1 or 2, wherein the electrophotographic rotating body is an electrophotographic belt. [Structure 4] The electrophotographic rotating body is an intermediate transfer belt, as described in any of configurations 1 to 3. [Composition 5] An image carrier that holds the toner image, A movable intermediate transfer body onto which the toner image is transferred from the image carrier, An electrophotographic image forming apparatus having an optical sensor that irradiates light onto the intermediate transfer body and detects reflected light, On the outer surface of the intermediate transfer body, A plurality of grooves extending in the direction of movement of the intermediate transfer body and formed to be regularly arranged in a direction perpendicular to the direction of movement of the intermediate transfer body, Multiple irregularly occurring depressions, It exists, The average spacing between these multiple grooves is 2.0 to 10.0 μm. The recess exists such that, when the intermediate transfer body is viewed from the outer surface side, a portion of the wall flanking the groove is cut out so that it forms an arc shape. When drawing a circle based on the arc shape of the wall cut out by the recess, The average diameter of the circle is 0.5 to 4.5 μm. The average of the nearest distances between the centers of the multiple circles drawn is greater than the average diameter of the circles, and is 10.0 μm or less. An electrophotographic image forming apparatus characterized in that, assuming there is no notch due to the recess, the wall extends in the direction of movement of the intermediate transfer body so as to maintain a constant width of the groove. [Composition 6] The electrophotographic image forming apparatus according to configuration 5, wherein the average value of the groove width is 0.5 to 2.0 μm. [Explanation of Symbols]

[0088] 1 Photosensitive drum, 2 Conductive roller, 3 Laser scanner, 4 Developer, 5 Electrophotographic belt, 6 Tension roller, 7 Drive roller, 8 Primary transfer roller, 9 Secondary transfer roller, 10 Current detection circuit, 11 Cleaning blade, 12 Feeding roller, 13 Transport roller, 14 Toner recovery blade, 15 Fuser, 20 Paper feed cassette, 21 Paper output tray, 41 Developer roller, 42 Developer container, 43 Developer blade, 60 Base layer, 81 Cylindrical mold, 90 Cylindrical belt holding mold, 92 Secondary transfer opposing roller, 104 Preform, 107 Heating device, 108 Blow mold, 109 Stretching rod, 110 Blow air injection section, 112 Bottle-shaped molded product, 151 Heating roller, 152 Pressure roller, 160 Density detection sensor, 161 Light-emitting element, 162 Irradiation light-receiving element, 163 Specular reflection light-receiving element, 200 groove, 201 recess, 202 wall, S recording medium, T toner image

Claims

1. A rotating body for electrophotography having a surface layer, On the outer surface of the surface layer, A plurality of grooves extending substantially in the rotational direction of the electrophotographic rotating body and formed to be regularly arranged in a direction perpendicular to the substantially rotational direction, Multiple irregularly occurring depressions, It exists, The average spacing between the multiple grooves is 2.0 to 10.0 μm. The recess exists such that, when the electrophotographic rotating body is viewed from the outer surface side, a portion of the wall flanking the groove is cut out in an arc shape. When drawing a circle based on the arc shape of the wall cut out by the recess, The average diameter of the circle is 0.5 to 4.5 μm. The average of the nearest distances between the centers of the multiple circles drawn is greater than the average diameter of the circles, and less than or equal to 10.0 μm. An electrophotographic rotating body characterized in that, assuming there is no notch due to the recess, the wall extends substantially in the direction of rotation of the electrophotographic rotating body so as to maintain a constant width of the groove.

2. The electrophotographic rotating body according to claim 1, wherein the average value of the width of the grooves is 0.5 to 2.0 μm.

3. The electrophotographic rotating body according to claim 1 or 2, wherein the electrophotographic rotating body is an electrophotographic belt.

4. The electrophotographic rotating body according to claim 1 or 2, wherein the electrophotographic rotating body is an intermediate transfer belt.

5. An image carrier that holds the toner image, A movable intermediate transfer body onto which the toner image is transferred from the image carrier, An electrophotographic image forming apparatus having an optical sensor that irradiates light onto the intermediate transfer body and detects reflected light, On the outer surface of the intermediate transfer body, A plurality of grooves extending in the direction of movement of the intermediate transfer body and formed to be regularly arranged in a direction perpendicular to the direction of movement of the intermediate transfer body, Multiple irregularly occurring depressions, It exists, The average spacing between the multiple grooves is 2.0 to 10.0 μm. The recess exists such that, when the intermediate transfer body is viewed from the outer surface side, a portion of the wall flanking the groove is cut out so that it forms an arc shape. When drawing a circle based on the arc shape of the wall cut out by the recess, The average diameter of the circle is 0.5 to 4.5 μm. The average of the nearest distances between the centers of the multiple circles drawn is greater than the average diameter of the circles, and less than or equal to 10.0 μm. An electrophotographic image forming apparatus characterized in that, assuming there is no notch due to the recess, the wall extends in the direction of movement of the intermediate transfer body so as to maintain a constant width of the groove.

6. The electrophotographic image forming apparatus according to claim 5, wherein the average value of the width of the grooves is 0.5 to 2.0 μm.

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