Electrophotographic component and electrophotographic image forming apparatus

Abstract

To provide an electrophotographic component that has low adhesion to the photosensitive drum, reduces exposure blur, and offers excellent toner cleaning performance over the long term. [Solution] An electrophotographic member having a plurality of recesses on its outer surface, wherein, with respect to the shape of the plurality of recesses, in each recess, the maximum width of the recess is WL (μm), the minimum width of the recess is WS (μm), and the maximum depth of the recess is DM (μm), and in the plurality of recesses, the arithmetic mean of WS / WL is (WS / WL)Ave, the arithmetic mean of WL is WLAve (μm), and the arithmetic mean of DM is DMAve (μm), and (WS / WL)Ave, WLAve, and DMAve satisfy predetermined formulas (1) to (4), and the proportion of the area occupied by the recesses on the outer surface is 20.0 to 50.0 area %.

Description

Technical Field

[0001] The present disclosure relates to electrophotographic members such as a conveyance transfer belt and an intermediate transfer belt, and an electrophotographic image forming apparatus, which are used in electrophotographic image forming apparatuses such as copiers and printers.

Background Art

[0002] In electrophotographic image forming apparatuses, electrophotographic members such as electrophotographic belts are used as conveyance transfer belts for conveying transfer materials and intermediate transfer belts for temporarily transferring and holding toner images. 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, and even when the number of durable sheets increases, electrophotographic members with excellent toner cleaning characteristics have been required. In addition, if there is adhesion between the electrophotographic belt and the photosensitive drum, the frictional force between the electrophotographic belt and the photosensitive drum may affect the running stability of the photosensitive drum, and defects may occur in the formed toner image. Therefore, it is necessary to aim at excellent toner cleaning characteristics for a long period of time and maintain the running stability of the drum by reducing the surface friction of the electrophotographic belt.

[0003] Patent Document 1 discloses that an electrophotographic belt has a surface layer, and the surface layer contains a heteroaggregate including inorganic oxide particles having a predetermined particle diameter and conductive metal oxide particles having a predetermined particle diameter different from the inorganic oxide particles, and the ten-point average roughness of the surface of the surface layer is within a predetermined range. Specifically, aggregation formation occurs with particles having different polarities of charged charges, the belt surface is roughened, and the surface friction of the belt is reduced. As a result, the adhesion between the electrophotographic belt and the photosensitive drum is reduced, and the drum tack performance is also problem-free. In addition, in the examples of Patent Document 1, a method of recovering residual toner by applying a bias and collecting it on the cleaning blade of the photosensitive drum is described as a belt cleaning method.

[0004] Patent Document 2 discloses an intermediate transfer body having a resin layer as its outermost layer, in which recesses composed of curved inner walls are scattered on the surface. Specifically, the exposed particle portions on the surface are removed, and the areas where the particles are missing are made into a surface recessed shape. This configuration improves the transfer performance of the intermediate transfer belt. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2014-146024 [Patent Document 2] Japanese Patent Publication No. 2012-203133 [Overview of the project] [Problems that the invention aims to solve]

[0006] The inventors' investigations revealed that both the electrophotographic belt described in Patent Document 1 and the intermediate transfer body described in Patent Document 2 have problems in configurations where a cleaning blade is used to clean the belt. The inventors have found that the surface roughening method for reducing friction described in Patent Document 1 may affect cleaning with a cleaning blade. For example, roughening may cause the cleaning blade to be unable to follow certain areas, potentially allowing external additives or toners to pass through and resulting in poor cleaning. Additionally, roughening may create minute protrusions, leading to blade wear and ultimately rendering cleaning impossible. .

[0007] As described in Patent Document 2, if the concave shape is created by particle omission, there is a possibility that toner of a similar size may get trapped in the concave area. In particular, if the size of the concave area is large, there is a possibility that the toner will get stuck in the concave area. There is a concern that the toner that gets stuck in the concave area cannot be scraped off by the cleaning blade, resulting in poor cleaning.

[0008] As described above, in configurations using a cleaning blade, protrusions and depressions on the belt surface can pose a problem. However, when the surface of the electrophotographic belt is smoothed, another problem arises: the adhesion between the photosensitive drum and the electrophotographic belt increases, and the frictional force due to the difference in peripheral speed between the photosensitive drum and the electrophotographic belt increases. On the other hand, since toner acts as a lubricant between the photosensitive drum and the electrophotographic belt, the frictional force changes depending on whether toner is present or not, and the rotational speed of the photosensitive drum changes. When the adhesion between the photosensitive drum and the electrophotographic belt is high, the change in the rotational speed of the photosensitive drum becomes large, and as a result, the exposure to the drum is blurred, and there is a higher possibility that streaky image defects (exposure blur) will occur at the leading edge of the image.

[0009] This disclosure provides an electrophotographic component for use in an electrophotographic image forming apparatus equipped with a cleaning blade, which exhibits low adhesion to the photosensitive drum, reduced exposure blurring, and excellent toner cleaning performance over a long period of time. Furthermore, this disclosure provides an electrophotographic image forming apparatus equipped with the electrophotographic component of this disclosure as an intermediate transfer belt. [Means for solving the problem]

[0010] According to one aspect of this disclosure, An electrophotographic member having a plurality of recesses on its outer surface, With respect to the shape of the multiple recesses, if in each recess the maximum width of the recess is WL (μm), the minimum width of the recess is WS (μm), and the maximum depth of the recess is DM (μm), and in the multiple recesses the arithmetic mean of WS / WL is (WS / WL)Ave, the arithmetic mean of WL is WLAve (μm), and the arithmetic mean of DM is DMAve (μm), then (WS / WL)Ave, WLAve, and DMAve satisfy the following equations (1) to (4). (WS / WL)Ave≧0.6 (1) 0.5 μm ≤ WLAve ≤ 4.0 μm (2) 0.00 < (DMAve / WLAve) ≤ 0.30 (3) DMAve ≥ 0.10 μm (4) An electrophotographic component is provided, wherein the area occupied by the recess on the outer surface is 20.0 to 50.0 area %.

[0011] Furthermore, according to other aspects of this disclosure, An electrophotographic image forming apparatus is provided, which includes the electrophotographic component of this disclosure as an intermediate transfer belt. [Effects of the Invention]

[0012] According to one aspect of this disclosure, an electrophotographic component is provided for use in an electrophotographic image forming apparatus equipped with a cleaning blade, which has low adhesion to the photosensitive drum, reduces exposure blurring, and exhibits excellent toner cleaning performance over a long period of time. According to another aspect of this disclosure, an electrophotographic image forming apparatus is provided which is equipped with the electrophotographic component of this disclosure as an intermediate transfer belt. [Brief explanation of the drawing]

[0013] [Figure 1] Schematic diagram showing the configuration of the outer surface of an electrophotographic belt. [Figure 2] Schematic diagram showing a cross-section of an electrophotographic belt in a direction perpendicular to the circumferential direction. [Figure 3] Schematic diagram showing a method for measuring the shape of electrophotographic components. [Figure 4]Schematic diagram showing an example of the configuration of an image forming apparatus using an intermediate transfer method [Figure 5] Schematic diagram showing an example of a method for manufacturing an electrophotographic belt using an extension blow molding machine [Figure 6] Schematic diagram showing the configuration of an evaluation jig for the adhesion between an electrophotographic belt and a photosensitive drum [Figure 7] Explanatory diagram of a method for measuring a concave shape

Embodiments for Carrying Out the Invention

[0014] In the present disclosure, the description of "XX or more and YY or less" or "XX to YY" representing a numerical range means a numerical range including the lower limit and the upper limit which are the endpoints, unless otherwise specified. When numerical ranges are described stepwise, the upper and lower limits of each numerical range can be arbitrarily combined. Further, in the present disclosure, a description such as "at least one selected from the group consisting of XX, YY, and ZZ" means any one of 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 when XX is a group, a plurality may be selected from XX, and the same applies to YY and ZZ.

[0015] The present inventors have conducted studies to obtain an electrophotographic member having excellent toner cleaning performance over a long period and a sufficiently low frictional force with a photosensitive drum. For this purpose, regarding the shape of the concave portion of the electrophotographic member, a concave shape that achieves both low frictional properties due to a reduced contact area with the photosensitive drum and the persistence of stable toner cleaning performance that allows the toner to be sufficiently cleaned was examined. Based on the results, the present inventors have come to the idea that by making the shape of the concave portion a predetermined shape, it is possible to achieve both reduction of friction between the electrophotographic member and the photosensitive drum and excellent toner cleaning performance of the electrophotographic member over a long period.

[0016] That is, the present disclosure is An electrophotographic member having a plurality of concave portions on an outer surface, With respect to the shape of the multiple recesses, if in each recess the maximum width of the recess is WL (μm), the minimum width of the recess is WS (μm), and the maximum depth of the recess is DM (μm), and in the multiple recesses the arithmetic mean of WS / WL is (WS / WL)Ave, the arithmetic mean of WL is WLAve (μm), and the arithmetic mean of DM is DMAve (μm), then (WS / WL)Ave, WLAve, and DMAve satisfy the following equations (1) to (4). (WS / WL)Ave≧0.6 (1) 0.5 μm ≤ WLAve ≤ 4.0 μm (2) 0.00 < (DMAve / WLAve) ≤ 0.30 (3) DMAve ≥ 0.10 μm (4) This invention relates to an electrophotographic component in which the area occupied by the recess on the outer surface is 20.0 to 50.0 area %.

[0017] The following describes in detail an electrophotographic belt as an electrophotographic component according to one aspect of this disclosure. However, this disclosure is not limited to the following aspect.

[0018] <Electrophotographic belt> The electrophotographic belt 5 has a plurality of recesses on its outer surface. The form of the electrophotographic belt 5 is not particularly limited, but for example, the electrophotographic belt 5 may have a base layer, or an elastic layer on the base layer. The electrophotographic belt 5 may also have a surface layer. That is, the outer surface of the electrophotographic belt 5 may be the outer surface of the surface layer. The surface layer may be formed on the base layer, or the surface layer may be formed on the elastic layer.

[0019] 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.

[0020] As a method for processing 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.

[0021] The details of a method for forming recesses on the outer surface of an electrophotographic component will be explained using an electrophotographic component having a surface layer as an example. One method for forming recesses is to use a coating liquid for the surface layer that has been prepared to create recesses in the surface layer. The recesses can be obtained 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 having recesses. 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.

[0022] Although the detailed mechanism is not understood, it is presumed that hydrocarbon oil dissolved in the solvent in the coating liquid remains on the surface of the coating film as the solvent evaporates, and that the removal of the hydrocarbon oil after the coating film has hardened forms depressions. The size of the recesses (diameters such as WL and WS, and depths indicated by DM, as described later) and the ratio of the area occupied by the recesses vary depending on the type and content of the hydrocarbon oil. Therefore, the hydrocarbon oil content should be adjusted according to the desired size and area ratio. The hydrocarbon oil content in the coating solution is not particularly limited, but it 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. A higher hydrocarbon oil content tends to result in larger recesses, while a lower hydrocarbon oil content tends to result in smaller recesses. Within the above range, the shape of the recesses is more favorable. Since hydrocarbon oils are preferably liquid in the coating environment, i.e., in the range of room temperature (23-30°C), it is preferable that the melting point of the hydrocarbon oil is below room temperature (for example, below 30°C or below, or below 23°C).

[0023] Examples of hydrocarbon oils include olefinic and paraffinic compounds. Specifically, olefinic hydrocarbons that can be used include linear unsaturated hydrocarbons such as hexene, octene, decene, dodecene, and tetradecene; branched unsaturated hydrocarbons such as diisobutylene and triisobutylene; and cyclic unsaturated hydrocarbons such as cyclohexene and dicyclopentene. Paraffin-based oils include linear saturated hydrocarbons such as hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, and octadecane, as well as isohexane, isohepran, isooctane, isohexane, isododecane, isotridecane, isotetradecane, isopentadecane, isohexadecane, isoheptadecane, isooctadecane, and isoeicosane. Branched saturated hydrocarbons and cyclic saturated hydrocarbons such as cyclohexane can be used. Furthermore, a mixture of multiple hydrocarbon oils with different numbers of carbon atoms may be used. As the hydrocarbon oil, hydrocarbon compounds that are generally commercially available as liquid paraffins can also be used. The number of carbon atoms in the hydrocarbon oil may be, for example, 8 to 35, 8 to 18, preferably 10 to 18, more preferably 14 to 18, and even more preferably 15 to 18. Alternatively, the number of carbon atoms in the hydrocarbon oil may be 25 to 35.

[0024] Furthermore, by adding an emulsifier along with the hydrocarbon oil, it is possible to control the diameters such as WL and WS described later, the depth indicated by DM, and the proportion of the area occupied by the recesses. In other words, it is preferable that the coating liquid contains an emulsifier. The shape of the depressions formed on the coating surface changes depending on the combination of emulsifier and hydrocarbon oil, as well as the amount of emulsifier. For example, increasing the amount of emulsifier tends to decrease WL, WS, and DM, and the proportion of the area occupied by depressions tends to increase. Conversely, decreasing the amount of emulsifier tends to increase WL, WS, and DM, and the proportion of the area occupied by depressions tends to decrease. Furthermore, even if hydrocarbon oil alone cannot form depressions, adding an emulsifier makes it easier to form them.

[0025] The HLB (hydrophilic-lipophilic balance) value of the emulsifier is preferably between 4 and 9. Emulsifiers with an HLB value of 4 or less are highly lipophilic. Therefore, adding an emulsifier increases the compatibility between hydrocarbon oil and resin-based paints. As a result, it is thought that oil droplet shapes cannot be formed on the surface, and depressions are less likely to form after the paint film hardens. Consequently, it becomes more difficult to suppress the occurrence of exposure blur. On the other hand, emulsifiers with an HLB value greater than 9 are highly hydrophilic. Therefore, they have low compatibility with resin-based paints, and it is thought that the surfactant effect with hydrocarbon oil is difficult to obtain. As a result, the effect of deforming the depression shape that is expected from an emulsifier is reduced, and they are not preferred as emulsifiers to be added.

[0026] Examples of such emulsifiers include stearate esters such as polyglyceryl-4 stearate, polyglyceryl-4 tristearate, polyglyceryl-6 tristearate, polyglyceryl-6 pentastearate, polyglyceryl-2 isostearate, polyglyceryl-4 isostearate, polyglyceryl-2 isostearate, and polyglyceryl-10 pentaisostearate, as well as oleic acid esters such as polyglyceryl-2 oleate, polyglyceryl-4 oleate, and polyglyceryl-6 pentaoleate. The amount of emulsifier in the coating liquid is not particularly limited, but is preferably 5.0 to 50.0 parts by mass, more preferably 5.0 to 30.0 parts by mass, and particularly preferably 10.0 to 30.0 parts by mass per 100 parts by mass of hydrocarbon oil. Within this range, the shape of the recesses becomes more favorable.

[0027] The coating solution can suitably use known materials such as antioxidants, UV absorbers, and leveling agents. In particular, the coating liquid preferably contains a leveling agent. This makes it easier for the parts of the coating film obtained by the coating liquid, other than the recesses, to become flat. The amount of leveling agent in the coating liquid is not particularly limited, but if the coating liquid contains resin, it may be 0.1 to 0.5 parts by mass per 100 parts by mass of resin.

[0028] Furthermore, while a method using a coating liquid to form recesses on the outer surface of an electrophotographic component has been described, other methods may also be used, such as imprinting to create a recessed shape on the surface.

[0029] The thickness of the electrophotographic belt 5 is preferably 10 μm or more and 500 μm or less, and preferably 30 μm or more and 15 A thickness of 0 μm or less is particularly preferred.

[0030] The electrophotographic component may be used as an electrophotographic belt, or it may be used by winding it around a drum or roll, or by covering it. Furthermore, the electrophotographic component may be used as an intermediate transfer body. That is, for example, the electrophotographic component may be an intermediate transfer belt. The shape of the electrophotographic component is not particularly limited, but an endless belt shape is preferred.

[0031] Figure 1 is a schematic diagram showing the configuration of the outer surface of an electrophotographic belt. Multiple recesses 201 are provided on the outer surface of the electrophotographic belt 5. This reduces the contact area between the photosensitive drum and the electrophotographic belt 5, thereby reducing friction. As a result, the adhesion to the photosensitive drum is reduced, which improves drum tack. In Figure 1, the recesses 201 are arranged irregularly. Figure 2B shows a cross-sectional view of the electrophotographic belt 5 in a direction perpendicular to the circumferential direction. Figure 2B is a cross-sectional view of the dotted line in Figure 2A. In Figure 2B, W represents the width of the recess and D represents the depth of the recess.

[0032] The recesses 201 will now be described. Multiple recesses 201 are provided on the electrophotographic belt 5. The recesses 201 are irregularly arranged on the outer surface of the electrophotographic belt 5. The shape of the recess 201 is defined by the following parameters. For the shapes of multiple recesses 201 observed from the outer surface side of the electrophotographic member at a magnification of 150x using a laser microscope, the maximum width of each recess is defined as WL (μm), the minimum width as WS (μm), and the maximum depth as DM (μm). Regarding WL, WS, and DM, the electrophotographic belt 5 is observed from the outer surface side using a laser microscope (Keyence Corporation, VK-X200) with a 150x objective lens. The WL, WS, and DM of each recess observed within the field of view of the outer surface of the observed electrophotographic belt 5 are measured.

[0033] The specific measurement method will be explained using Figures 3 and 7. While the measurement method in this embodiment is described below as an example, the measurement method for each recess is not limited to this example. 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 portion, this flat portion is set as the reference plane. There are areas in the cross-sectional profile where depressions are formed relative to this reference plane. These areas are defined as depressions. Specifically, as shown in Figure 7, areas with a depth of 0.01 μm or more relative to the reference plane are defined as depressions, and the region of these depressions is defined as the entire area below the reference plane.

[0034] First, the center of the recessed edge shape (hereinafter also referred to as the recessed shape) observed within the field of view is determined. The center of the smallest circumscribed circle among the circumscribed circles circumscribed around the recessed shape is determined as the center of the recessed shape (Figure 3 (2)). Of the width passing through that center, the longest width to the edge of the recessed shape is defined as WL, and the shortest width is defined as WS (Figure 3 (3)). Next, the cross-sectional profile is measured in the direction passing through the center of the recessed shape and along WL (Figure 3 (4)). Then, the depth between the deepest point in the cross-sectional profile and the flat portion is defined as DM (Figure 3 (5)). Here, the flat portion refers to the part of the outer surface of the electrophotographic member other than the part with the recess.

[0035] The WL, WS, and DM of the observed recesses can be measured. Measure the WL, WS, and DM for all recesses within the field of view, and record the number of recesses and the WL, WS, and DM for each recess. Also, record the aspect ratio (WS / WL) for each recess. Regarding the location for shape measurement, a total of 18 measurements are taken: 3 points in the width direction and 6 points in the circumferential direction of the electrophotographic belt. Width direction measurements are taken at positions of 0 mm and ±100 mm relative to 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. In this disclosure, the sign indicates the coating direction of the coating liquid, with the upstream side of the coating direction being positive and the downstream side being negative. That is, +100mm means 100mm upstream from the center in the width direction of the electrophotographic belt in the coating liquid application direction. Furthermore, the circumferential direction is evaluated at intervals of 1 / 6 of the circumferential length.

[0036] Measurements are taken at each of the above measurement points for each recess, and the arithmetic mean of all results is calculated to determine WLAve, (WS / WL)Ave, and DMAve, respectively. That is, for multiple recesses, the arithmetic mean of WS / WL is (WS / WL)Ave, the arithmetic mean of WL is WLAve(μm), and the arithmetic mean of DM is DMAve(μm). The following relationships are preferred for WLAve, (WS / WL)Ave, and DMAve. If the size of the recess is too small, it will be difficult to reduce frictional force and the recess will not be effective, while if it is too large, the risk of toner seeping through will increase. Therefore, WLAve satisfies the following equation (2). Furthermore, it is preferable that WLAve satisfies the following equation (2-1). 0.5 μm ≤ WLAve ≤ 4.0 μm (2) 1.5 μm ≤ WLAve ≤ 3.5 μm (2-1)

[0037] Furthermore, if the depth of the recess is too deep relative to its size, and the recess is too steep, toner may get trapped inside, potentially causing the cleaning blade to slip past it. This can lead to poor cleaning. On the other hand, if the recess is too shallow, it loses its effectiveness. Therefore, WLAve and DMAve satisfy the following equations (3) to (4). 0.00 < (DMAve / WLAve) ≤ 0.30 (3) DMAve ≥ 0.10 μm (4)

[0038] WLAve and DMAve preferably satisfy the following formula (3-1), more preferably satisfy the following formula (3-2), and even more preferably satisfy the following formula (3-3). 0.00<(DMAve / WLAve)≦0.24 (3-1) 0.10≦(DMAve / WLAve)≦0.24 (3-2) 0.17≦(DMAve / WLAve)≦0.24 (3-3) Furthermore, if the width of the recess is large, it is preferable that the depth of the recess is also large. From this viewpoint, it is also preferable that WLAve and DMAve satisfy the following formula (3-4). 0.10≦(DMAve / WLAve)≦0.30 (3-4)

[0039] The DMAve / WLAve values ​​can be changed, for example, by altering the depth and width of the depressions by increasing or decreasing the amount of hydrocarbon oil. They can also be changed by the type of hydrocarbon oil used. Furthermore, when using emulsifiers, the depth and width of the depressions can be similarly altered by increasing or decreasing the amount of emulsifier used or by the type of emulsifier used.

[0040] DMAve preferably satisfies the following formula (4-1), and more preferably satisfies the following formula (4-2). 1.20μm≧DMAve≧0.10μm (4-1) 0.70μm≧DMAve≧0.10μm (4-2)

[0041] Furthermore, according to the electrophotographic belt of this disclosure, even when the cleaning blade is in a steady state, pressure release can be performed only in the recessed area, reducing blade wear and extending its lifespan. However, if the recessed area extends diagonally with respect to the rotational direction of the electrophotographic belt, the pressure release area of ​​the blade moves laterally relative to the blade as it passes through the recessed area. As a result, the release area extends over a wide area, making cleaning performance unstable. By reducing the number of recesses that can be oblique to the direction of rotation of the belt, and thereby reducing the amount of relative lateral movement, cleaning performance becomes more stable. In other words, it is preferable for the recess shape to be close to a circular shape. Therefore, (WS / WL)Ave satisfies the following equation (1). Furthermore, it is preferable for (WS / WL)Ave to satisfy the following equation (1-1), more preferably the following equation (1-2), and even more preferably the following equation (1-3). (WS / WL)Ave≧0.6 (1) 1.0 ≥ (WS / WL) Ave ≥ 0.6 (1-1) 1.0 ≥ (WS / WL) Ave ≥ 0.8 (1-2) 1.0 ≥ (WS / WL) Ave ≥ 0.9 (1-3)

[0042] Furthermore, the percentage of the area occupied by recesses on the outer surface of the electrophotographic component will also be explained. This percentage is the arithmetic mean of the percentage of the area occupied by recesses at each measurement point within the total measurement area. The percentage of the area occupied by recesses at each measurement point is calculated using the total area of ​​recesses in the field of view and the area of ​​the overall field of view. Since the overall field of view is rectangular, the area of ​​the overall field of view is the area of ​​the rectangle. If the recess shape is circular or elliptical, the area of ​​each recess can be calculated as WS × WL × π / 4. The sum of the areas of recesses in the field of view is taken as the total area of ​​recesses in the field of view. The calculated area percentage of recesses needs to be such that the recesses are distributed fairly uniformly on the outer surface of the electrophotographic material in order to produce the desired effect of the recesses. On the other hand, if there are too many recesses, the pressure release will be too great, making cleaning unstable. Therefore, the percentage of the area occupied by recesses on the outer surface should be between 20.0 and 50.0 area%, and preferably between 26.0 and 45.0 area%.

[0043] <Electrophotographic image forming apparatus> Figure 4 shows an example of an image forming apparatus that incorporates an electrophotographic component based on this disclosure as an intermediate transfer belt, and is configured as an electrophotographic apparatus. In other words, the electrophotographic image forming apparatus of the present disclosure comprises the electrophotographic member of the present disclosure as an intermediate transfer belt.

[0044] 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.

[0045] 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 (image exposure). 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 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 4k is equipped with a developing roller 41k, which is a developer material carrier that develops the latent image on the photosensitive drum 1k, a developing container 42k that holds the toner supplied to the developing roller 41k, and a developing blade 43k that regulates the amount of toner on the developing roller 41k and applies an electric charge.

[0046] The electrophotographic belt 5 is configured as an endless belt and is provided in common to each color image forming station, and includes a secondary transfer opposing roller 92, a tension roller 6 and a drive. The electrophotographic belt 5 is stretched across roller 7 and rotated in the direction of the arrow in the diagram by drive roller 7. In the section between tension roller 6 and drive roller 7, the electrophotographic belt 5 sequentially contacts the surfaces of photosensitive drums 1c, 1m, 1y, and 1k, and is pressurized toward the photosensitive drums 1c, 1m, 1y, and 1k by primary transfer rollers 8c, 8m, 8y, and 8k, respectively. As a result, the toner images formed on the surfaces of photosensitive drums 1c, 1m, 1y, and 1k are transferred to the surface of the electrophotographic belt 5, which is the intermediate transfer body.

[0047] The transfer of the toner image from the photosensitive drum to the intermediate transfer body is called primary transfer, and the location where the primary transfer takes place from the photosensitive drum 1 to the electrophotographic belt 5 is called the primary transfer section. Furthermore, to improve the transferability of the primary transfer, a speed difference (peripheral speed difference) is provided between the peripheral speed of the photosensitive drum 1 and the peripheral speed of the electrophotographic belt 5. In this embodiment, the peripheral speed difference is provided by making the peripheral speed of the photosensitive drum 1 smaller than the peripheral speed of the electrophotographic belt 5. However, the inventors' studies have shown that the effect of improving the primary transferability does not change significantly even if the other way around is done. In other words, the peripheral speed difference may be provided by making the peripheral speed of the electrophotographic belt 5 smaller than the peripheral speed of the photosensitive drum 1. To achieve good primary transfer of the toner image, the absolute value of this peripheral speed difference (|{(peripheral speed of the electrophotographic belt - peripheral speed of the photosensitive drum) / peripheral speed of the electrophotographic belt}| × 100[%]) should be, for example, 10% or less, preferably 5% or less, and more preferably 3% or less. In this example, this peripheral speed difference was set to 1.5%, and while the peripheral speed of the electrophotographic belt 5 was 210 mm / sec, the peripheral speed of the photosensitive drum 1 was set to the smaller side, 206.85 mm / sec.

[0048] 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.

[0049] 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.

[0050] 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 member that extends in a direction substantially perpendicular to the direction of movement of the electrophotographic belt 5. It is preferable for the electrophotographic image forming apparatus to be equipped with a cleaning member for the electrophotographic member. Furthermore, it is preferable for the electrophotographic image forming apparatus to be equipped with a blade member as the cleaning member. An example of a blade member is the cleaning blade 11. 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.

[0051] 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.

[0052] The operation of the image forming apparatus has been described above, but now we will explain the issues arising from the surface condition of the electrophotographic belt. First, we will explain the image defects caused by exposure that occur when the contact between the photosensitive drum 1 and the electrophotographic belt 5 is high. As mentioned above, when there is a speed difference (peripheral speed difference) between the peripheral speed of the photosensitive drum 1 and the peripheral speed of the electrophotographic belt 5, a frictional force is generated based on the difference in the coefficient of friction between the two. This frictional force changes depending on whether or not there is toner acting as a lubricant between the photosensitive drum 1 and the electrophotographic belt 5, causing the rotational speed of the photosensitive drum 1 to fluctuate. This can cause blurring of the image exposure to the photosensitive drum 1, resulting in streaky image defects (exposure blur) at the leading edge of the image. This exposure blur is likely to occur when there is a sudden change between the photosensitive drum 1 and the electrophotographic belt 5, from a state with no toner to a state with toner. In other words, exposure blur is likely to occur when the area on the electrophotographic belt 5 entering the primary transfer section changes from a non-image area to an image area in the direction of movement of the surface of the electrophotographic belt 5, relative to the image area set for each recording medium S. Typically, exposure blur is more likely to occur when the area on the electrophotographic belt 5 entering the primary transfer section changes from a non-image area downstream (towards the leading edge) in the direction of movement of the surface of the electrophotographic belt 5 to an image area.

[0053] Secondly, I will explain cleaning failures, where the cleaning blade is unable to clean up residual toner. There are several possible reasons for cleaning failures. One issue is that the cleaning blade may change in condition due to wear or other factors, resulting in insufficient scraping performance. For example, if there are protrusions on the surface of the electrophotographic belt, the cleaning blade may wear down due to contact with these protrusions. From this perspective, it is preferable that the outer surface of the electrophotographic component does not have protrusions. In other words, it is preferable that the parts of the outer surface of the electrophotographic component other than the recesses be flat. Another issue is that the cleaning blade's ability to follow the surface is insufficient, preventing proper toner cleaning and causing the toner to pass through. For example, when toner gets into a recess on the outer surface of the electrophotographic belt, the cleaning blade may not be able to reach it, or it may not be able to scrape off the toner, causing the toner to remain in the recess and pass through. In either case, if there are recesses or protrusions on the outer surface of the electrophotographic belt, the toner may not be able to be cleaned.

[0054] As described above, our investigations have shown that the surface condition of the electrophotographic belt can lead to image defects in the image forming apparatus. Therefore, it is necessary to determine whether the electrophotographic belt can be used as an intermediate transfer belt. For this reason, in the following examples, we use it as an intermediate transfer belt for evaluation. [Examples]

[0055] Examples and comparative examples are shown below to illustrate the present disclosure in detail, but the present disclosure is not limited to these.

[0056] (Example 1) [Base layer manufacturing] First, a thermoplastic resin composition was prepared by hot-melt kneading the following base material in a ratio of 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 pelletized and dried at a temperature of 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.) (Manufactured by Kogyo Co., Ltd.) CB: Carbon Black (Product Name: MA-100, manufactured by Mitsubishi Chemical Corporation)

[0057] 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.

[0058] Next, the preform described above was biaxially stretched using the biaxial stretching apparatus (stretch blow molding machine) shown in Figure 5. Before biaxial stretching, the preform 104 was placed in a heating apparatus 107 equipped with a non-contact type heater (not shown) for heating the outer and inner walls of the preform 104, and the heating heater 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.

[0059] [Formulation of coating solution] In this embodiment, recesses are irregularly arranged on the outer surface of the electrophotographic belt 5. The surface layer materials used in the examples and comparative examples are indicated by the following abbreviations. AN: Dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (product name: Aronics M-402, manufactured by Toagosei Co., Ltd.) IRG: Photoinitiator (product name: Omnirad907, manufactured by IGM Resins BV) R: Leveling agent (Product name: Cymac US270, 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) CH1:n-Hexadecane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) CH2: Liquid paraffin (product name: Moresco White P-350P, manufactured by Moresco Co., Ltd.) CH3: n-tetradecane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) D1: Emulsifier (Product name: SY Glister PO-5S, manufactured by Sakamoto Pharmaceutical Co., Ltd. (HLB 4.7)) D2: Emulsifier (Product name: SY Glister MO-3S, manufactured by Sakamoto Pharmaceutical Co., Ltd. (HLB 8.8)) MIBK: Solvent (Trade name: Methyl isobutyl ketone, manufactured by Kishida Chemical Co., Ltd.)

[0060] The surface layer materials were weighed in the ratio AN / IRG / R / CH1 / SL / MIBK = 100 / 8.4 / 0.3 / 5.0 / 50.0 / 236.3 (mass ratio), and the materials excluding SL were mixed and stirred to obtain a resin liquid. While stirring this resin liquid, SL was added and stirred further to obtain coating liquid 1 for surface layer formation. In the above ratios, only SL is shown as the mass ratio on a solid content basis. The same applies to other examples and comparative examples below.

[0061] [Formation of surface layer and recess] 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 container was pulled out while maintaining a constant relative speed between the liquid level of the curable composition and the base layer, thereby allowing the coating liquid to penetrate the base layer surface. A coating film was formed. The lifting 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 lifting speed was set to 10-50 mm / second and adjusted so that the film thickness of the surface layer was 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.

[0062] 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.

[0063] An intermediate transfer belt 1 having multiple recesses was obtained by wiping off the coating with a nonwoven fabric impregnated with MEK (methyl ethyl ketone). The recesses of this intermediate transfer belt 1 were irregularly arranged. The size of the recesses was evaluated as described above.

[0064] Furthermore, the thickness of the surface layer was determined by destructive testing, which involved cutting an intermediate transfer 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. The characteristics and performance evaluation methods for the intermediate transfer belt 1 fabricated in this embodiment are as follows: [Evaluation 1] to [Evaluation 3].

[0065] [Evaluation 1] Evaluation of the shape of the recesses on the surface of the intermediate transfer belt The shape of the recesses on the outer surface of the intermediate transfer belt was evaluated as described above. The electrophotographic belt was observed from the outer surface side using a laser microscope (Keyence Corporation, VK-X200) with a 150x objective lens. The maximum width WL, minimum width WS, maximum depth DM, and area ratio of each recess observed within the field of view of the outer surface of the electrophotographic belt were measured. Details of the measurement method are omitted here as they were described above.

[0066] [Evaluation 2] Tack characteristics and image characteristics evaluation Next, we will describe the measurement of tack between the photosensitive drum 1 and the electrophotographic belt 5. The adhesion between the photosensitive drum of a full-color electrophotographic system (product name: LBP-5200, manufactured by Canon Inc.) and the electrophotographic belt 5 was measured using a jig as shown in Figure 6. The electrophotographic belt 5 was tensioned by a drive roller b1 equipped with a motor and torque meter, a driven roller b4, and a tension roller b3 that applied tension to the electrophotographic belt 5. The photosensitive drum b2 and backup roller b5 were the photosensitive drum and transfer roller of the LBP-5200, respectively.

[0067] First, rotate the electrophotographic belt 5 at 180 mm / second without contacting the photosensitive drum, and measure the torque value at that time. Let this value be "Tq1". Next, the maximum torque is measured when the electrophotographic belt 5 is rotated at 180 mm / second and the photosensitive drum is brought into contact with it at 700 gf. This value is denoted as "Tq2". The difference between "Tq2" and "Tq1" is then used as an index to evaluate the adhesion between the electrophotographic belt 5 and the photosensitive drum 1. Hereafter, this difference will be referred to as the tack value.

[0068] Exposure blur, one of the image defects mentioned earlier, is caused by a rapid change in the frictional force between the electrophotographic belt 5 and the photosensitive drum 1 before and after the toner is introduced. Therefore, exposure blur is more likely to occur when the frictional force between the photosensitive drum 1 and the electrophotographic belt 5 is greater. In other words, exposure blur is more likely to occur when the tack value, which indicates higher adhesion, is higher. Based on the inventors' findings, when the tack value is 0.5 [N·m] or higher, the evaluation rank of exposure blur becomes "C", indicating a clear presence of exposure blur. When the tack value is 0.3 [N·m] or higher and less than 0.5 [N·m], the evaluation rank of exposure blur becomes "B", indicating exposure blur. The blur becomes minimal. When the tack value is less than 0.3 [N·m], the exposure blur evaluation rank becomes "A", indicating that the exposure blur is very minimal. The final performance of the electrophotographic belt, which acts as an intermediate transfer medium in an image forming apparatus, is determined by the image rank for exposure blur. On the other hand, the tack value is also measured and evaluated as a reference value for the performance of the electrophotographic belt alone. The exposure blur evaluation rank of the electrophotographic belt in this embodiment was also "A". Furthermore, when bringing the electrophotographic belt and the photosensitive drum into contact during this measurement, the photosensitive drum was kept stationary and not rotated, and the contact surface of the photosensitive drum was always in a brand-new condition.

[0069] [Evaluation 3] 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.

[0070] 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 after processing 100,000 sheets and 200,000 sheets. Based on these evaluation results, the electrophotographic belts were ranked according to the following criteria.

[0071] 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 100,000-sheet paper feeding process, but toner cleaning failures occurred during the 200,000-sheet paper feeding process. Rank C: A toner cleaning failure occurred during the 100,000-sheet paper feeding process.

[0072] 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.

[0073] (Example 2) An intermediate transfer belt 2 was prepared in the same manner as in Example 1, except that the mixing ratio of the surface layer material was set to AN / IRG / R / CH1 / D1 / SL / MIBK = 100 / 8.4 / 0.3 / 5.0 / 1.0 / 50.0 / 235.3 (mass ratio), and then subjected to evaluation.

[0074] (Example 3) The mixing ratio of the surface layer material is AN / IRG / R / CH1 / D2 / SL / MIBK=100 An intermediate transfer belt 3 was prepared in the same manner as in Example 1, except that the mass ratios were set to / 8.4 / 0.3 / 5.0 / 1.0 / 50.0 / 235.3, and then subjected to evaluation.

[0075] (Example 4) An intermediate transfer belt 4 was prepared in the same manner as in Example 1, except that the mixing ratio of the surface layer material was set to AN / IRG / R / CH1 / D2 / SL / MIBK = 100 / 8.4 / 0.3 / 5.0 / 2.0 / 50.0 / 234.3 (mass ratio), and then subjected to evaluation.

[0076] (Example 5) An intermediate transfer belt 5 was prepared in the same manner as in Example 1, except that the mixing ratio of the surface layer material was set to AN / IRG / R / CH1 / SL / MIBK = 100 / 8.4 / 0.3 / 10.0 / 50.0 / 231.3 (mass ratio), and then subjected to evaluation.

[0077] (Example 6) An intermediate transfer belt 6 was prepared in the same manner as in Example 1, except that the mixing ratio of the surface layer material was set to AN / IRG / R / CH1 / SL / MIBK = 100 / 8.4 / 0.3 / 7.5 / 50.0 / 233.8 (mass ratio), and then subjected to evaluation.

[0078] (Example 7) An intermediate transfer belt 7 was prepared in the same manner as in Example 1, except that the mixing ratio of the surface layer material was set to AN / IRG / R / CH2 / D2 / SL / MIBK = 100 / 8.4 / 0.3 / 15.0 / 1.0 / 50.0 / 225.3 (mass ratio), and then subjected to evaluation.

[0079] (Example 8) An intermediate transfer belt 8 was prepared in the same manner as in Example 1, except that the mixing ratio of the surface layer material was set to AN / IRG / R / CH3 / D2 / SL / MIBK = 100 / 8.4 / 0.3 / 5.0 / 1.0 / 50.0 / 235.3 (mass ratio), and then subjected to evaluation.

[0080] (Comparative Example 1) An intermediate transfer belt 9 was prepared in the same manner as in Example 1, except that the mixing ratio of the surface layer material was set to AN / IRG / R / SL / MIBK = 100 / 8.4 / 0.3 / 50.0 / 241.3 (mass ratio), and then subjected to evaluation.

[0081] (Comparative Example 2) An intermediate transfer belt 10 was prepared in the same manner as in Example 1, except that the mixing ratio of the surface layer material was set to AN / IRG / R / CH1 / SL / MIBK = 100 / 8.4 / 0.3 / 20.0 / 50.0 / 221.3 (mass ratio), and then subjected to evaluation.

[0082] (Comparative Example 3) An intermediate transfer belt 11 was prepared in the same manner as in Example 1, except that the mixing ratio of the surface layer material was set to AN / IRG / R / CH1 / D1 / SL / MIBK = 100 / 8.4 / 0.3 / 5.0 / 5.0 / 50.0 / 231.3 (mass ratio), and then subjected to evaluation.

[0083] (Comparative Example 4) An intermediate transfer belt 12 was prepared in the same manner as in Example 1, except that the mixing ratio of the surface layer material was set to AN / IRG / R / CH2 / SL / MIBK = 100 / 8.4 / 0.3 / 20.0 / 50.0 / 221.3 (mass ratio), and then subjected to evaluation.

[0084] (Comparative Example 5) The surface layer material is AN / IRG / R / PTFE / SL / MIBK = 100 / 8.4 / 0. Solutions were prepared by weighing the materials in the ratios of 3 / 20.0 / 50.0 / 221.3 (by mass) and performing a coarse dispersion treatment on the materials excluding SL. The resulting solutions were 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. Here, PTFE refers to fluororesin (polytetrafluoroethylene) particles. Furthermore, while stirring the SL, the liquid from the dispersion treatment was added dropwise to obtain a coating liquid 13 for forming the surface layer. Then, in the same manner as in Example 1, a coating film consisting of the coating liquid 13 was formed on the base layer surface and the coating film was cured.

[0085] The fluororesin particles exposed on the outer surface of the obtained intermediate transfer belt were removed by rubbing it with a woven fabric (product name: Bencot AZ-8, manufacturer: Asahi Kasei Fibers Corporation). As a result, an intermediate transfer belt 13 was obtained with the fluororesin particles removed and recesses scattered on the outer surface. The intermediate transfer belt 13 was also subjected to the same evaluation as in Example 1.

[0086] Table 1 summarizes some of the mixing ratios for coating solutions 1 to 13 related to the above examples and comparative examples. [Table 1]

[0087] The evaluation results for intermediate transfer belts 1-13 are summarized in Table 2. [Table 2]

[0088] Products with a rank of C in the performance evaluation were deemed unacceptable and unusable. In Comparative Example 1, no recesses were present on the outer surface of the resulting electrophotographic component. Comparative Example 1 had a high tack value, and its exposure blur rank in image evaluation was C. Comparative Example 5 is an example where a depression was formed due to particle loss, and it does not satisfy equation (3). Toner got into the depression, resulting in a cleaning performance rank of C.

[0089] This disclosure includes the following components: [Configuration 1] An electrophotographic member having a plurality of recesses on its outer surface, With respect to the shape of the multiple recesses, if in each recess the maximum width of the recess is WL (μm), the minimum width of the recess is WS (μm), and the maximum depth of the recess is DM (μm), and in the multiple recesses the arithmetic mean of WS / WL is (WS / WL)Ave, the arithmetic mean of WL is WLAve (μm), and the arithmetic mean of DM is DMAve (μm), then (WS / WL)Ave, WLAve, and DMAve satisfy the following equations (1) to (4). (WS / WL)Ave≧0.6 (1) 0.5 μm ≤ WLAve ≤ 4.0 μm (2) 0.00 < (DMAve / WLAve) ≤ 0.30 (3) DMAve ≥ 0.10 μm (4) An electrophotographic component characterized in that the area occupied by the recess on the outer surface is 20.0 to 50.0 area %. [Configuration 2] The electrophotographic member according to configuration 1, wherein the area ratio of the recess on the outer surface is 26.0 to 45.0 area %. [Configuration 3] The WLAve and DMAve satisfy the following equation (3-4): 0.10≦(DMAve / WLAve)≦0.30 (3-4) The electrophotographic component described in configuration 1 or 2. [Structure 4] The WLAve mentioned above satisfies the following equation (2-1): 1.5 μm ≤ WLAve ≤ 3.5 μm (2-1) An electrophotographic component as described in any of configurations 1 to 3. [Composition 5] An electrophotographic image forming apparatus characterized by comprising an electrophotographic member described in any of configurations 1 to 4 as an intermediate transfer belt. [Composition 6] The electrophotographic image forming apparatus according to configuration 5, further comprising a blade member as a cleaning member for the electrophotographic member. [Explanation of Symbols]

[0090] 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 sensing circuit, 11 Cleaning blade, 12 Feeding roller, 13 Conveyor roller, 14 Toner recovery blade, 15 Fuser, 20 Paper feed cassette, 21 Paper output tray, 41 Developer roller, 42 Developer container, 43 Developer blade, 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 concentration detection sensor, 201 recess, S recording medium

Claims

1. An electrophotographic member having a plurality of recesses on its outer surface, With respect to the shape of the plurality of recesses, in each recess, let the maximum width of the recess be WL (μm), the minimum width of the recess be WS (μm), and the maximum depth of the recess be DM (μm). In the plurality of recesses, let the arithmetic mean of WS / WL be (WS / WL)Ave, the arithmetic mean of WL be WLAve (μm), and the arithmetic mean of DM be DMAve (μm). Then (WS / WL)Ave, WLAve, and DMAve satisfy the following equations (1) to (4). (WS / WL)Ave≧0.6 (1) 0.5μm≦WLAve≦4.0μm (2) 0.00<(DMAve / WLAve)≦0.30 (3) DMAve≧0.10μm (4) An electrophotographic component characterized in that the area occupied by the recess on the outer surface is 20.0 to 50.0 area %.

2. The electrophotographic member according to claim 1, wherein the proportion of the area occupied by the recess on the outer surface is 26.0 to 45.0 area %.

3. The WLAve and DMAve satisfy the following formula (3-4): 0.10≦(DMAve / WLAve)≦0.30 (3-4) The electrophotographic member according to claim 1.

4. The WLAve satisfies the following equation (2-1): 1.5μm≦WLAve≦3.5μm (2-1) The electrophotographic member according to claim 1.

5. An electrophotographic image forming apparatus characterized by comprising an electrophotographic member according to any one of claims 1 to 4 as an intermediate transfer belt.

6. The electrophotographic image forming apparatus according to claim 5, further comprising a blade member as a cleaning member for the electrophotographic member.

Images