Electrophotographic belt and electrophotographic image forming apparatus

Abstract

To provide an electrophotographic belt with minimal toner color shift and fewer transfer defects. [Solution] An electrophotographic belt having a surface layer, wherein the surface layer contains (meth)acrylic resin, porous spherical particles, and conductive particles different from the porous spherical particles, the surface of the porous spherical particles at the outermost surface of the surface layer is covered with the (meth)acrylic resin and the conductive particles, the ten-point average roughness Rz (according to JIS B 0601-1994) of the outermost surface of the surface layer is 0.5 times or more and less than 2 times the average primary particle diameter of the porous spherical particles, and the average spacing S (according to JIS B 0601-1994) of the local peaks at the outermost surface of the surface layer is 4 times or more and less than 30 times the average primary particle diameter of the porous spherical particles.

Description

Technical Field

[0001] The present disclosure relates to an electrophotographic belt and an electrophotographic image forming apparatus including the electrophotographic belt.

Background Art

[0002] In electrophotographic image forming apparatuses, an endless 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. The surface layer of the electrophotographic belt is required to have a surface resistivity of a medium resistance region that is uniform in the plane in order to efficiently perform primary and secondary transfers of the toner image.

[0003] In addition, the electrophotographic belt is in contact with and slides on other members within the electrophotographic image forming apparatus. When the surface of the electrophotographic belt is excessively smooth, it may adhere to other members. For example, when a photosensitive drum or a cleaning blade adheres to the surface of the electrophotographic belt, the stable rotation of the electrophotographic belt may be inhibited.

[0004] A decrease in the rotational stability of the electrophotographic belt may cause, for example, the moving speed of the electrophotographic belt to become unstable, and misregistration (color misregistration) may occur during the transfer of the toner images of each color onto paper. Therefore, conventionally, in order to prevent the adhesion of other members to the surface of the electrophotographic belt, unevenness has been formed on the surface of the electrophotographic belt.

[0005] As a method for forming unevenness on the surface of the electrophotographic belt, in Patent Document 1, a method has been proposed in which the matrix resin of the outermost surface layer and particles having an average particle diameter of 0.5 μm or more and 20 μm or less and a hardness higher than that of the matrix resin are included, and a part of the particles is exposed to the outside in the outermost surface layer to roughen the surface.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

[0007] The belt disclosed in Patent Document 1 contains particles with an average particle size of 0.5 to 20 μm, which have a higher hardness than the matrix resin, and some of these particles are exposed to the outside. Therefore, when used as an electrophotographic belt, it can form irregularities on the surface, reducing the adhesion force with the photosensitive drum. As a result, even when printing multi-color characters, the amount of toner color shift is small, and good image quality can be obtained.

[0008] However, with the belt described in Patent Document 1, many localized toner defects (transfer blemishes) were observed when printing solid images. Transfer blemishes are image defects in which the uniformity of the image is reduced because toner is not transferred in certain areas when outputting an image of uniform density.

[0009] Therefore, at least one aspect of this disclosure aims to provide an electrophotographic belt with a small amount of toner color shift and few transfer defects. Furthermore, at least one aspect of this disclosure aims to provide an electrophotographic image forming apparatus capable of forming high-quality electrophotographic images. [Means for solving the problem]

[0010] At least one aspect of this disclosure is, An electrophotographic belt having a surface layer, The surface layer contains (meth)acrylic resin, porous spherical particles, and conductive particles different from the porous spherical particles. At the outermost surface of the surface layer, the surface of the porous spherical particles is coated with the (meth)acrylic resin and the conductive particles. The ten-point average roughness Rz (according to JIS B 0601-1994) of the outermost surface of the surface layer is 0.5 times or more and less than 2 times the average primary particle diameter of the porous spherical particles. This is an electrophotographic belt characterized in that the average spacing S (in accordance with JIS B 0601-1994) of the local peaks on the outermost surface of the surface layer is 4 times or more and less than 30 times the average primary particle diameter of the porous spherical particles. Furthermore, at least one aspect of this disclosure is an electrophotographic image forming apparatus comprising the above-mentioned electrophotographic belt as an intermediate transfer belt. [Effects of the Invention]

[0011] According to at least one aspect of this disclosure, an electrophotographic belt with a small amount of toner color shift and few transfer defects can be obtained. Furthermore, according to at least one aspect of this disclosure, an electrophotographic image forming apparatus capable of forming high-quality electrophotographic images can be obtained. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1(a) is a schematic diagram showing the surface configuration of an electrophotographic belt according to this disclosure, and Figure 1(b) is a cross-sectional view along the line A-A' in Figure 1(a). [Figure 2] Figure 2 is a schematic cross-sectional view of the injection molding apparatus used in the example. [Figure 3] Figures 3(a) to 3(d) are schematic cross-sectional views of the primary blow molding apparatus used in the embodiment. [Figure 4] Figure 4 is a schematic cross-sectional view of the secondary blow molding apparatus used in the embodiment. [Figure 5] Figure 5 is a schematic cross-sectional view showing an example of a full-color electrophotographic image forming apparatus utilizing an electrophotographic process. [Figure 6] Figure 6 is a schematic diagram of a jig used to evaluate the adhesion between an electrophotographic belt and other components. [Modes for carrying out the invention]

[0013] In the present disclosure, descriptions such as "XX or more and YY or less" and "XX to YY" representing numerical ranges mean numerical ranges including the lower limit and the upper limit which are endpoints, unless otherwise specified. Further, when numerical ranges are described stepwise, the upper and lower limits of each numerical range can be combined arbitrarily. Further, in the present disclosure, descriptions such as "at least one selected from the group consisting of XX, YY, and ZZ" mean 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.

[0014] 〔One embodiment〕 One embodiment relates to a belt for electrophotography. The electrophotographic belt of the present disclosure is an electrophotographic belt having a surface layer, where the surface layer contains a (meth)acrylic resin, porous spherical particles, and conductive particles different from the porous spherical particles, at the outermost surface of the surface layer, the surface of the porous spherical particles is coated with the (meth)acrylic resin and the conductive particles, the ten-point average roughness Rz (conforming to JIS B 0601-1994) of the outermost surface of the surface layer is 0.5 times or more and less than 2 times the average primary particle diameter of the porous spherical particles, and the average interval S (conforming to JIS B 0601-1994) between local peaks of the outermost surface of the surface layer is 4 times or more and less than 30 times the average primary particle diameter of the porous spherical particles.

[0015] Transfer blotch refers to an image defect in which the in-plane uniformity of an image deteriorates due to toner that is not transferred here and there when an image with a uniform density is output. Transfer blotch is considered to occur at locations where there is unevenness in the distribution of conductive particles that adjust the surface resistivity of the electrophotographic belt, resulting in locally increased resistance. That is, it is presumed that there are portions where the particles contained to form irregularities on the belt are exposed on the surface and no conductive particles are present in those portions.

[0016] Based on these considerations, the inventors conducted extensive research to obtain an electrophotographic belt that contains spherical particles in its outermost layer to form an uneven surface while minimizing unevenness in the distribution of conductive particles. As a result, they found that by using (meth)acrylic resin as the matrix resin for the surface layer and including porous spherical particles and conductive particles, it is possible to obtain an electrophotographic belt with an uneven surface and minimal unevenness in surface resistivity.

[0017] In the electrophotographic belt having the above configuration, the inventors speculate that the reason why surface irregularities can be formed on the surface and surface resistivity unevenness can be reduced is as follows. To form irregularities on the surface of an electrophotographic belt, a thin surface layer is preferable to the particle size of the spherical particles contained in the surface layer. However, in this case, the spherical particles cannot be sufficiently coated with (meth)acrylic resin, and some of the spherical particles may be exposed on the surface. Since the conductive particles contained in the surface layer exist dispersed in the (meth)acrylic resin, it is difficult for conductive particles to be present on the spherical particles exposed on the surface.

[0018] Furthermore, if the surface layer is made sufficiently thick relative to the particle size of the spherical particles contained in the surface layer, the spherical particles can be coated with (meth)acrylic resin and conductive particles, but it is difficult to form sufficient irregularities.

[0019] In contrast, by incorporating porous spherical particles into the surface layer, even if the surface layer is thinner than the particle size of the porous spherical particles, the (meth)acrylic resin can be more easily adsorbed onto the porous spherical particles, thus enabling coating. Furthermore, conductive particles dispersed in the (meth)acrylic resin are more likely to exist on the porous spherical particles, resulting in a state where conductive particles are evenly distributed across the entire surface of the electrophotographic belt.

[0020] As a result, it is believed that the uneven surface of the electrophotographic belt reduces the amount of toner color shift caused by contact with the photosensitive drum, while the even distribution of conductive particles improves the transfer quality. The following describes in detail an electrophotographic belt relating to one aspect of this disclosure. However, this disclosure is not limited to the following aspect.

[0021] <<Electrophotographic belt>> The electrophotographic belt relating to this disclosure has a surface layer. Figure 1(a) shows a perspective view of an electrophotographic belt 500 having an endless belt shape according to one embodiment of the present disclosure. An example of a layer configuration is a laminated structure in which the cross section along line A-A' in Figure 5(a) has a base layer 501 and a surface layer 502 covering the outer circumferential surface of the base layer, as shown in Figure 5(b). When a surface layer 502 is provided, the outer surface 500-1 of the surface layer 502 becomes the toner-carrying surface of the electrophotographic belt. Furthermore, the electrophotographic belt may have layers other than the base layer and the surface layer.

[0022] <base layer> The base layer consists of a resin composition (also referred to as a thermoplastic resin composition) containing a crystalline polyester as a binder and an ionic conductive agent. The thickness of the base layer according to this disclosure is not particularly limited. However, since it is arranged in a bent state within an electrophotographic image forming apparatus, it is preferable to have a thickness of 40 μm to 500 μm, and more preferably 50 μm to 100 μm, from the viewpoint of ensuring flexibility.

[0023] (Crystalline polyester) Crystalline polyesters can be obtained by polycondensation of dicarboxylic acids and diols, polycondensation of oxycarboxylic acids or lactones, or polycondensation using multiple such components. Further polyfunctional monomers may also be used in combination. Crystalline polyesters may be homopolyesters containing one ester bond or copolyesters (polymers) containing multiple ester bonds.

[0024] As crystalline polyesters, at least one selected from the group consisting of polyalkylene terephthalate and polyalkylene naphthalate, which have high crystallinity and excellent heat resistance, can be cited as a suitable example. Copolymers of polyalkylene naphthalate and polyalkylene isophthalate can also be suitably used.

[0025] In polyalkylene terephthalate, polyalkylene naphthalate, and polyalkylene isophthalate, the number of carbon atoms in the alkylene is preferably 2 to 16 from the viewpoint of high crystallinity and heat resistance. More specifically, as crystalline polyesters, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene isophthalate, and copolymers containing these are preferred. These can be used individually or in combination of two or more types.

[0026] The molecular weight of crystalline polyesters is not particularly limited, but for example, in the case of PET, the preferred weight-average molecular weight is between 50,000 and 80,000. In the case of PEN, the preferred weight-average molecular weight is between 20,000 and 80,000.

[0027] The content of crystalline polyester in the base layer is preferably 50.0% by mass or more, and more preferably 60.0% by mass or more, based on the total mass of the thermoplastic resin composition. Having a crystalline polyester content within the above range ensures a more reliable increase in the mechanical strength of the base layer.

[0028] (Ionic conductive agent) The base layer may contain a low-molecular-weight ionic conductive agent as a conductive agent to adjust the resistivity. For example, an ionic liquid may be included as the low-molecular-weight ionic conductive agent. An ionic liquid is a salt consisting of anions and cations that has a melting point below 100°C. Specific examples of ionic conductive agents include lithium bis(trifluoromethanesulfonyl)imide and lithium bis(fluorosulfonyl)imide, which are classified as ionic liquids.

[0029] When the base layer contains an ionic conductive agent, the content ratio of the ionic conductive agent is not particularly limited, based on the mass of the base layer, but is preferably, for example, 0.5% by mass or more and 8.0% by mass or less.

[0030] (Additives) Other components may be added to the thermoplastic resin composition as long as they do not impair the effects of the present disclosure. Examples of other components include fillers, antioxidants, UV absorbers, organic pigments, inorganic pigments, pH adjusters, crosslinking agents, compatibilizers, mold release agents, coupling agents, lubricants, etc. These additives may be used individually or in combination of two or more types. The amount of additive used can be set as appropriate and is not particularly limited.

[0031] <Surface layer> Electrophotographic belts have a surface layer on the outer periphery of the base layer for purposes such as reducing adhesion to contact members such as photosensitive drums and cleaning blades, and preventing blocking. The electrophotographic belt according to this disclosure has a surface layer that contains a (meth)acrylic resin as a binder, porous spherical particles, and conductive particles different from the porous spherical particles.

[0032] In the electrophotographic belt according to this disclosure, the thickness of the surface layer is preferably less than or equal to the average primary particle diameter of the porous spherical particles, for example, 1 μm to 5 μm is preferred. By doing so, an electrophotographic belt can be obtained in which the amount of toner color shift is smaller and the amount of transfer burrs is smaller.

[0033] ((meth)acrylic resin) As for the resin used in the surface layer, it is preferable that the curable composition contains at least a (meth)acrylic resin because it has excellent scratch resistance to the outer surface of the surface layer. The (meth)acrylic resin content in the surface layer is preferably 60.0% by mass or more and 85.0% by mass or less, and more preferably 65.0% by mass or more and 80.0% by mass or less, based on the mass of the surface layer.

[0034] (Conductive particles) In the electrophotographic belt according to this disclosure, it is preferable that the conductive particles are conductive metal oxides. When the electrophotographic belt is used, for example, as an intermediate transfer belt, semiconductivity is required in the surface layer. Therefore, it is preferable to use conductive particles such as conductive metal oxides as particles that impart conductivity. The fact that the conductive particles are conductive metal oxides can be confirmed by FE-SEM observation and EDX measurement of the conductive particles.

[0035] In the electrophotographic belt according to this disclosure, the average primary particle diameter (number-average particle size of the primary conductive particles) is preferably 0.01 μm or more and 0.04 μm or less, and more preferably 0.01 μm or more and 0.025 μm or less. By keeping the number-average particle size of the conductive particles within the above range, the formation of singularities (bumps) on the outer surface of the surface layer can be prevented.

[0036] Furthermore, the dispersion state in the curable composition (liquid) can be stabilized, and even when the curable composition is stored for a long period of time before being used to form a surface layer, a surface layer having a stable outer surface with dispersed conductive particles can be obtained. The conductive particles may be surface-treated to enhance their dispersion stability in organic solvents. In addition, two or more types of conductive metal oxide particles may be used in combination.

[0037] The conductive particles preferably include at least one particle selected from the group consisting of zinc antimonate particles and antimony-containing tin oxide particles. Commercially available conductive metal oxide particles such as Celnax® CX-Z410K (product name) and Celnax® CX-Z400K (product name) from Nissan Chemical Corporation, and SN-100P (product name) from Ishihara Sangyo Co., Ltd. can be used.

[0038] (Porous spherical particles) The porous spherical particles contained in the surface layer are micron-sized particles added to control the surface irregularities and the distribution of conductive particles in electrophotographic belts. Porous spherical particles have diverse chemical structures, crystalline structures, and crystallinity, and their shape and size are also distinctive depending on the manufacturing method.

[0039] The porous spherical particles used in this disclosure include, for example, silica particles, silicone particles, activated carbon, zeolite, and fine particles of thermosetting resin. These can be used individually or in combination of two or more types.

[0040] In the electrophotographic belt according to this disclosure, the surface of porous spherical particles at the outermost surface of the surface layer is coated with the (meth)acrylic resin and the conductive particles. This can be confirmed by FE-SEM observation and EDX measurement of the surface and cross-section of the surface layer.

[0041] There are no particular restrictions on shape or size, but it is preferable that the particles be spherical and of a size that can form irregularities on the surface. This is because, if the particles that form the irregularities are spherical, isotropy with respect to the dispersion and orientation state is easier to obtain compared to amorphous particles or fibrous materials, regardless of the manufacturing method of the electrophotographic belt, and irregularities can be easily formed on the surface.

[0042] The electrophotographic belt according to this disclosure preferably has an average primary particle diameter of porous spherical particles of 1.0 μm or more and 10 μm or less, more preferably 2.5 μm or more and 5 μm or less, and even more preferably 2.9 μm or more and 4.9 μm or less.

[0043] If the properties of the porous spherical particles are as described above, the (meth)acrylic resin containing conductive particles will adhere to the porous spherical particles more easily due to the anchoring effect, and the dispersion control of the conductive particles will be easier. In this way, the surface of the porous spherical particles can be coated with the (meth)acrylic resin and the conductive particles.

[0044] The electrophotographic belt according to this disclosure preferably uses porous spherical silica particles or porous spherical silicone particles because they offer excellent thermal stability, low surface energy, minimal particle aggregation, and easy dispersion control. The fact that the porous spherical particles are porous spherical silica particles or porous spherical silicone particles can be confirmed by FE-SEM observation and EDX measurement of the porous spherical particles.

[0045] The average primary particle diameter of porous spherical particles can be measured by the following method. For example, measurement samples are cut from any 20 locations on an electrophotographic belt, each measuring 5 mm in length, 5 mm in width, and with a thickness equal to the total thickness of the electrophotographic belt.

[0046] A portion of each obtained measurement sample cross-section is further cut using a microtome or similar device, and observed at 5000x magnification using an FE-SEM (product name: Sigma500VP, manufactured by Carl Zeiss Microscopy) to obtain photographs. Simultaneously, elemental analysis is performed using EDX (Energy Dispersive X-ray Spectroscopy) to identify the elements contained in the porous spherical particles. Furthermore, the diameter of the porous spherical particles in the belt thickness direction and in the direction perpendicular to the belt thickness direction is measured from the obtained photographs, and the average value is taken as the particle diameter of the porous spherical particles. For each of at least 50 porous spherical particles, the particle diameter can be similarly measured, and the average value of the top 10 particle diameters can be used as the average primary particle diameter of the porous spherical particles.

[0047] Furthermore, porous spherical particles have pores on their surface and inside, and the number and size of these pores are thought to correlate with their ability to adsorb other substances. DBP oil absorption is cited as an indicator of the ability to adsorb other substances, and in the electrophotographic belt according to this disclosure, the DBP oil absorption of the porous spherical particles is preferably 100 mL / 100 g or more and 200 mL / 100 g or less, and more preferably 142 mL / 100 g or more and 160 mL / 100 g or less. By doing so, an electrophotographic belt can be obtained in which the amount of toner color shift is smaller and the amount of transfer burrs is smaller.

[0048] (others) In the electrophotographic belt according to this disclosure, it is preferable that the ten-point average roughness Rz (in accordance with JIS B 0601-1994) of the outermost surface of the surface layer is 0.5 times or more and less than 2 times the average primary particle diameter of the porous spherical particles, and 0.7 times or more and 1.7 times the average primary particle diameter of the porous spherical particles. By doing so, an electrophotographic belt can be obtained in which the amount of toner color shift is smaller and the amount of transfer burrs is smaller.

[0049] In the electrophotographic belt according to this disclosure, the average spacing S (in accordance with JIS B 0601-1994) of the local peaks on the outermost surface of the surface layer is preferably 4 times or more and less than 30 times the average primary particle diameter of the porous spherical particles, preferably 6 times or more and 22 times or less the average primary particle diameter of the porous spherical particles, and more preferably 6.6 times or more and 21.7 times or less the average primary particle diameter of the porous spherical particles. By doing so, an electrophotographic belt can be obtained in which the amount of toner color shift is smaller and the amount of transfer burrs is smaller.

[0050] <<Manufacturing method for electrophotographic belts>> <Method for manufacturing the base layer> The cylindrical film base layer can be manufactured, for example, through the following steps (i) to (iii). Step (i): Obtain a test tube-shaped preform made of a resin mixture containing crystalline polyester and an ionic conductive agent. Step (ii): The preform is stretched in its longitudinal direction and gas is introduced into the preform to stretch and mold it in two axes, longitudinal and circumferential, to obtain a molded product (hereinafter also referred to as a "bottle") (biaxial stretch blow molding). next, Step (iii): Cut both ends of the bottle to obtain an endless cylindrical film.

[0051] In step (i), a resin mixture containing crystalline polyester and an ionic conductive agent is thermally melt-kneaded to prepare pellets. In the thermal melt-kneading of the thermoplastic resin composition, it is preferable to knead at the following temperature. That is, it is preferable to knead at a temperature higher than the melting point of the crystalline polyester contained in the resin mixture. There are no particular restrictions on the kneading method, and a single-screw extruder, twin-screw compounding extruder, Banbury mixer, roll, brabender, plastograph, kneader, etc. can be used.

[0052] A test tube-shaped preform is then molded using the resin mixture obtained in this way. There are no particular restrictions on the method of molding the preform; for example, the following method can be used. As shown in Figure 2, the molten resin mixture is injected into a preform molding die consisting of a cavity mold 203 and a core mold 207 using an injection molding apparatus 201, and the mixture is solidified in the preform molding die to form a preform 205 having a predetermined shape.

[0053] Furthermore, it is preferable to keep the temperature of the preform molding die into which the molten material is injected at, for example, 40°C or lower. The molten material injected into the die cools and solidifies within the die, but by cooling it quickly at this time, it is possible to prevent the crystallization of the crystalline polyester from progressing.

[0054] By suppressing the crystallization of crystalline polyester within the preform, the biaxial crystal orientation of the crystalline polyester during stretch blow molding in process (ii) can be controlled more precisely.

[0055] Next, in step (ii), the preform is subjected to biaxial stretch blow molding. First, as shown in Figure 3(a), the preform 205 is placed in the heating furnace 301 and heated to a temperature at which it can be stretched. The heating time at this time is preferably within 1 minute. By limiting the heating time to within 5 minutes, it is possible to prevent the crystallization of crystalline polyester from progressing within the preform during heating. The heated preform is transported in the direction of arrow 305.

[0056] Next, the blow mold 303, which has a cylindrical cavity 303-3 formed inside by combining the left mold 303-1 and the right mold 303-2, is lowered from directly above the heated preform 205 in the direction of arrow 307. Then, as shown in Figure 3(b), it is positioned at the opening of the blow mold 303.

[0057] Furthermore, it is preferable to place the heated preform into the mouth of the blow mold within a short time (for example, within 20 seconds) so that the temperature of the preform does not drop before the start of the next biaxial stretching process. This prevents the crystallization of crystalline polyester within the preform due to slow cooling. The heating temperature of the preform may be calculated, for example, by observing the endothermic peak and baseline shift during heating of the resin mixture, which is the constituent material of the preform, using a differential scanning calorimetry (DSC), or it may be determined from the glass transition temperature (Tg).

[0058] As shown in Figure 3(c), the heated preform 205, placed inside the blow mold 303, is stretched longitudinally by driving the stretching rod 309 in the direction of arrow 311. This stretching is called primary stretching. In addition, gas is introduced into the preform 205 from the opening (arrow 313) in sync with the driving of the stretching rod 309, causing the preform to expand circumferentially. This is called secondary stretching.

[0059] Examples of gases to be blown in include air, nitrogen, carbon dioxide, and argon. As a result, the preform 205 expands in the directions indicated by arrows 315 in Figure 3(c), adheres tightly to the inner wall of the cavity 303-3, and is cooled and solidified in that state. Next, the bottle-shaped molded product (hereinafter also referred to as the "blow bottle") is removed from the blow mold 303 by separating the left mold 303-1 and the right mold 303-2 of the blow mold 303.

[0060] Next, as shown in Figure 3(d), the portion of the blown bottle 317 on the mouth side and the portion of the upper end opposite to the mouth side are cut to obtain a biaxially oriented cylindrical film 319 which will serve as the base layer.

[0061] Furthermore, if necessary, heat treatment may be performed before cutting the blow bottle 317 to adjust the surface roughness of the outer surface of the blow bottle or to fine-tune the crystallinity of the crystalline polyester. Specifically, for example, as shown in Figure 4, the blow bottle 317 is placed inside a cylindrical mold 401, and then gas is filled into the blow bottle. Then, to prevent the gas inside the blow bottle from leaking out, the mold 401 is heated while rotating it with a roller-shaped heater 403 that is in contact with the outer surface of the mold 401, with outer molds attached to the top and bottom of the mold 401. The heating temperature is, for example, about 130 to 190°C, and the heating time is, for example, about 60 seconds so that the entire circumference of the blow bottle is heated uniformly. The electrophotographic belts described herein are not limited to intermediate transfer belts, but are also suitably used in, for example, transport transfer belts.

[0062] <Method for manufacturing the surface layer> The method for manufacturing the surface layer is not particularly limited, but it is preferable to include a step of applying a curable composition to the above-mentioned base layer and curing it to obtain the surface layer. [Step 1] A step of preparing a curable composition containing the following components (a) to (d); The method for producing the curable composition is not particularly limited, but since it contains porous spherical particles, conductive particles, and (meth)acrylic monomer, which is often highly viscous, it is preferable to produce it as described below. A slurry in which porous spherical particles are dispersed in a solvent, a slurry in which conductive particles are dispersed in a solvent, and a solution in which (meth)acrylic monomer components are dissolved in a solvent are prepared in advance. These are then placed in a container with a stirrer with a polymerization initiator and other components according to the formulation described later, and stirred for 30 minutes at room temperature, for example, to obtain the curable composition. The concentration of the slurry and solution can be set within a range that is easy to stir. The total amount of solvent is preferably, for example, 200 to 2000 parts by mass, or 500 to 1200 parts by mass, per 100 parts by mass of the total of (meth)acrylic monomer, porous spherical particles, and conductive particles.

[0063] ((meth)acrylic monomer) The curable composition used to form the surface layer preferably contains a monomer that forms a (meth)acrylic resin, such as a (meth)acrylic monomer. The (meth)acrylic monomer is not particularly limited, but polyfunctional (meth)acrylic monomers are preferred from the viewpoint of abrasion resistance and hardness. Suitable examples include pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, dipentaerythritol penta and hexa(meth)acrylate, and isocyanurate ethylene oxide-modified di and tri(meth)acrylate. The acrylic monomer is particularly preferably dipentaerythritol penta and hexa(meth)acrylate. It is also possible to use multiple acrylic monomers to adjust curing shrinkage and viscosity. In addition, commercially available products such as Aronix® M-305 (product name) from Toagosei Co., Ltd. can be used.

[0064] (solvent) From the viewpoint of stably dispersing or dissolving the (meth)acrylic monomer, conductive particles, and porous spherical particles mentioned above, the curable composition preferably contains a solvent. The solvent preferably contains at least one selected from the group consisting of 2-butanone and 4-methyl-2-pentanone.

[0065] Furthermore, it is possible to add multiple solvents other than those listed above to adjust the evaporation rate and viscosity. Specific examples include alcohols such as methanol, ethanol, isopropanol, butanol, and octanol; ketones such as acetone and cyclohexanone; esters such as ethyl acetate, butyl acetate, ethyl lactate, γ-butyrolactone, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate; ethers such as ethylene glycol monomethyl ether and diethylene glycol monobutyl ether; aromatic hydrocarbons such as benzene, toluene, and xylene; and amides such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

[0066] Among these, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, toluene, and xylene are preferred.

[0067] (Radical polymerization initiator) Examples of radical polymerization initiators include compounds that generate active radical species thermally (thermal polymerization initiators) and compounds that generate active radical species by radiation (light) irradiation (radiation (photo) polymerization initiators).

[0068] As a radiation (photopolymerization) initiator, there are no particular restrictions as long as it decomposes upon light irradiation to generate radicals and initiate polymerization. Examples include acetophenone, acetophenone benzyl ketal, 1-hydroxycyclohexylphenyl ketone, 2,2-dimethoxy-1,2-diphenylethane-1-one, xanthones, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3-methylacetophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-diaminobenzophenone, benzoin propyl ether, benzoin ethyl ether, benzyldimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one, 2-Hydro Examples include roxy-2-methyl-1-phenylpropan-1-one, thioxanthone, diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone).

[0069] The amount of radical polymerization initiator added is preferably 0.01 parts by mass to 10 parts by mass, and more preferably 0.1 parts by mass to 5 parts by mass, per 100 parts by mass of (meth)acrylic monomer component. If the amount added is 0.01 parts by mass or more, the cured product will not have sufficient hardness, which is insufficient. If it is 10 parts by mass or less, the cured product will harden sufficiently to the interior (lower layer).

[0070] (Other ingredients) The curable composition may contain other components as needed, provided they do not impair the effects of the present disclosure. For example, dispersants, polymerization inhibitors, polymerization initiators, leveling agents, wettability modifiers, surfactants, plasticizers, UV absorbers, antioxidants, antistatic agents, inorganic fillers, pigments, and the like may be added.

[0071] [Step 2] A step of forming a coating film of the curable composition on one surface of the base layer and drying the coating film; and a step of curing the dried coating film; For example, the base layer is fitted onto the outer circumference of a cylindrical mold, the ends are sealed, and the mold is immersed in a container filled with a curable composition. The mold is then 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 of the curable composition 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. For example, the lifting speed can be set to between 10 mm / second and 50 mm / second.

[0072] After the coating film is formed, it is dried and cured. In the drying process, the drying temperature, humidity, and drying time can be appropriately adjusted based on the type of solvent, solvent ratio, film thickness, etc. The drying temperature is preferably 20°C to 30°C. The relative humidity during drying is preferably 40% to 70%. The drying time is preferably 30 seconds to 300 seconds. Within the above range, the coating film can be reliably dried, and the reduction in the degree of curing due to residual solvent in the cured film during curing can be suppressed.

[0073] Subsequently, the dried coating is cured to obtain the surface layer. For example, curing can be done by UV irradiation. The cumulative light intensity can be set appropriately depending on the material used. For example, 300 mJ / cm². 2 More than 2000mJ / cm 2 The following is possible:

[0074] The content of porous spherical particles in the surface layer is preferably 0.5% by mass or more and 20.0% by mass or less, and more preferably 1.0% by mass or more and 15.0% by mass or less, based on the mass of the surface layer. Within the above range, irregularities can be formed on the surface and the porous spherical particles can be coated with (meth)acrylic resin. In this way, the surface of the porous spherical particles can be coated with (meth)acrylic resin and the conductive particles. Furthermore, the content of conductive particles in the surface layer can be adjusted within a range in which a desired resistance value can be obtained.

[0075] <Electrophotographic image forming apparatus> The electrophotographic image forming apparatus of this disclosure is equipped with the electrophotographic belt of this disclosure as an intermediate transfer belt. Below, an example of an electrophotographic image forming apparatus using the electrophotographic belt according to one embodiment of this disclosure as an intermediate transfer belt will be described. As shown in Figure 5, this electrophotographic image forming apparatus has a so-called tandem configuration in which multiple color electrophotographic stations are arranged in the rotational direction of the intermediate transfer belt. In the following description, the subscripts Y, M, C, and k are attached to the symbols of the yellow, magenta, cyan, and black color configurations, respectively, but the subscripts may be omitted for similar configurations.

[0076] In Figure 5, the photosensitive drums (photoreceptor, image carrier) 1Y, 1M, 1C, 1k are surrounded by charging devices 2Y, 2M, 2C, 2k, exposure devices 3Y, 3M, 3C, 3k, developing devices 4Y, 4M, 4C, 4k, and an intermediate transfer belt (intermediate transfer body) 6. The photosensitive drum 1 is driven to rotate at a predetermined peripheral speed (process speed) in the direction of arrow F (counterclockwise). The charging device 2 charges the peripheral surface of the photosensitive drum 1 to a predetermined polarity and potential (primary charging).

[0077] The laser beam scanner, acting as the exposure apparatus 3, outputs on / off modulated laser light corresponding to image information input from external devices such as an image scanner (not shown) or a computer, and scans and exposes the charged surface on the photosensitive drum 1. This scanning exposure forms an electrostatic latent image on the surface of the photosensitive drum 1 corresponding to the desired image information.

[0078] The developing devices 4Y, 4M, 4C, and 4k each contain toners for the respective color components: yellow (Y), magenta (M), cyan (C), and black (k). Based on the image information, the developing device 4 to be used is selected, and the developer (toner) is developed on one surface of the photosensitive drum, making the electrostatic latent image visible as a toner image. In this embodiment, an inversion development method is used in which toner is attached to the exposed area of ​​the electrostatic latent image and developed in this way. Furthermore, the electrophotographic image forming means is constructed by such a charging device, exposure device, and developing device.

[0079] Furthermore, the intermediate transfer belt 6 is composed of an electrophotographic belt having an endless shape. The intermediate transfer belt 6 is stretched by a plurality of rollers 20, 21, and 22 so that its outer surface contacts the surface of the photosensitive drum 1. In this embodiment, roller 20 is a tension roller that controls the tension of the intermediate transfer belt 6 to a constant level, roller 22 is a drive roller for the intermediate transfer belt 6, and roller 21 is an opposing roller for secondary transfer. The intermediate transfer belt 6 rotates in the direction of arrow G by the drive of roller 22. Primary transfer rollers 5Y, 5M, 5C, and 5k are positioned at the primary transfer positions opposite the photosensitive drum 1, with the intermediate transfer belt 6 in between.

[0080] The unfixed toner images of each color formed on the photosensitive drum 1 are sequentially electrostatically transferred onto the intermediate transfer belt 6 by applying a primary transfer bias with the opposite polarity to the charge polarity of the toner to the primary transfer roller 5 using a constant voltage source or constant current source (not shown). A full-color image is then obtained by superimposing the four unfixed toner images onto the intermediate transfer belt 6. The intermediate transfer belt 6 rotates while carrying the toner images transferred from the photosensitive drum 1 in this manner. After each rotation of the photosensitive drum 1 following the primary transfer, the surface of the photosensitive drum 1 is cleaned of any remaining toner by the cleaning device 11 (11Y, 11M, 11C, 11k), and the image formation process is repeated.

[0081] Furthermore, at the secondary transfer position of the intermediate transfer belt 6 facing the transport path of the recording material 7 as a transfer medium, a secondary transfer roller (transfer section) 9 is pressed against the toner image-carrying surface of the intermediate transfer belt 6. In addition, on the back side of the intermediate transfer belt 6 at the secondary transfer position, an opposing roller 21 is provided, which serves as the opposing electrode of the secondary transfer roller 9 and to which a bias is applied.

[0082] When transferring the toner image on the intermediate transfer belt 6 to the recording material 7, a bias of the same polarity as the toner is applied to the opposing roller 21 by the transfer bias application means 28, for example, -3000V to -1000V, causing a current of -50μA to -10μA to flow. The transfer voltage at this time is detected by the transfer voltage detection means 29. Furthermore, a cleaning device (blade cleaner) 12 is provided downstream of the secondary transfer position to remove toner remaining on the intermediate transfer belt 6 after secondary transfer.

[0083] The recording material 7 passes through the transport guide 8 and is transported in the direction of arrow H, and is introduced to the secondary transfer position. The recording material 7 introduced to the secondary transfer position is clamped and transported at the secondary transfer position, and at that time, a constant voltage bias (transfer bias) controlled to a predetermined value is applied to the opposing roller 21 of the secondary transfer roller 9 from the secondary transfer bias application means 28. By applying a transfer bias of the same polarity as the toner to the opposing roller 21, the four-color full-color image (toner image) superimposed on the intermediate transfer belt 6 at the transfer site is transferred to the recording material 7 all at once, forming a full-color unfixed toner image on the recording material. The recording material 7 that has received the toner image transfer is introduced to a fuser (not shown) and heated and fixed. [Examples]

[0084] The present disclosure will be specifically explained below with reference to examples and comparative examples, but the disclosure is not limited to these. The materials used in the manufacture of the electrophotographic belts in the examples and comparative examples are shown below.

[0085] [Table 1]

[0086] [Table 2]

[0087] (Methods for measuring and evaluating characteristic values) The methods for measuring and evaluating the characteristic values ​​of electrophotographic belts in the examples and comparative examples are as follows: [Evaluation 1] to [Evaluation 6]. [Evaluation 1] Evaluation of DBP oil absorption capacity (DBP absorption amount) of porous spherical particles The amount of DBP oil absorbed by the porous spherical particles contained in the fabricated electrophotographic belt was measured by the following method. 100 2mm x 2mm sample pieces cut from the electrophotographic belt were crushed and left to stand in a high-temperature chamber at 350°C for 48 hours to burn off the resin components, and the remaining porous spherical particles were extracted.

[0088] The amount of DBP absorbed by the extracted porous spherical particles was measured using an absorption meter (product name: S-500; manufactured by Asahi Research Institute Co., Ltd.). Specifically, 10 g of the collected porous spherical particles were placed in the measurement chamber, and the torque was measured with a DBP (dibutyl phthalate) dropping rate of 4 mL / min and a rotor rotation speed of 125 rpm. The DBP absorption amount can be defined by the DBP dropping volume and sample volume that resulted in a torque of 70% of the peak torque value.

[0089] If the required amount of porous spherical particles for measuring DBP oil absorption cannot be obtained from 100 sample pieces, the number of samples collected can be increased and the above procedure performed to obtain the necessary amount of porous spherical particles.

[0090] [Evaluation 2] Evaluation of the ten-point average roughness Rz and the average spacing S of local peaks on the surface of an electrophotographic belt. The roughness of the electrophotographic belt was measured using the following method. The roughness index conformed to JIS B 0601-1994. A surface roughness measuring instrument (product name: Surfcom 1500SD, manufactured by Tokyo Seimitsu Co., Ltd.) was used as the measuring device. The parameters for roughness measurement were a cutoff wavelength of 0.25 mm, a measurement length of 1.25 mm, and a measurement probe feed rate of 0.2 mm / second.

[0091] Here, the ten-point average roughness Rz and the average spacing S of local peaks on the surface of the electrophotographic belt were determined by scanning the measuring probe of the measuring device in a direction perpendicular to the circumferential direction of the electrophotographic belt. Measurements were taken at eight points per belt (two points in the width direction and four points in the circumferential direction), and the average value was calculated.

[0092] [Evaluation 3] Evaluation of coating of porous spherical particles with (meth)acrylic resin The presence or absence of porous spherical particles coated with (meth)acrylic resin was determined by the following method. First, measurement samples measuring 5 mm in length, 5 mm in width, and with a thickness equal to the total thickness of the electrophotographic belt were cut from 20 arbitrary locations on the obtained electrophotographic belt.

[0093] A portion of the cross-section of each obtained measurement sample was further cut using a microtome or similar device, and observed at 10,000x magnification using an FE-SEM (product name: Sigma500VP, manufactured by Carl Zeiss Microscopy). Visual confirmation was then performed from the resulting photographs to determine whether a coating layer was present on the outer surface of the porous spherical particles.

[0094] Simultaneously, elemental analysis was performed using EDX (Energy Dispersive X-ray Spectroscopy) to confirm whether elemental components of conductive particles were detected on the outer surface of the porous spherical particles. The above evaluation was performed for at least 50 porous spherical particles.

[0095] [Rating 4] Rank evaluation of the transcription software Transfer blemishes refer to image defects where toner is not transferred in certain areas when printing an image with uniform density, resulting in reduced uniformity within the image plane. Using a full-color electrophotographic system (product name: LBP-672C, manufactured by Canon Inc.), 150g of the toner to be evaluated was filled into a cyan cartridge, and the toner cartridge was left in a high-temperature, high-humidity environment (30°C / 80%RH) for 24 hours.

[0096] A toner cartridge that had been left in a full-color electrophotographic device for 24 hours, along with an electrophotographic belt, was installed, and 1,000 images with a 1.0% print ratio were printed on A4 paper in landscape orientation. After printing 1,000 pages, the toner load was 0.40 mg / cm². 2 The solid image is CS-680 (basis weight 68g / m²). 2 (Sold by Canon Marketing Japan Inc.)

[0097] This image was visually inspected, and the transfer blemishes were evaluated based on the following criteria. In this disclosure, areas where image uniformity is impaired were identified as transfer blemishes. S: No transfer defects are visible, whether under normal light or when exposed to strong light. A: Even under normal light or when held up to a strong light, almost no transfer defects are visible. B: Under normal light, the transfer granules are not visible, but they can be seen when exposed to strong light. C: Even under normal light, transfer defects can be seen. Here, "normal light" refers to the light from a typical fluorescent lamp shining on the surface, while "strong light" refers to the light from a typical fluorescent lamp shining on both the front and back surfaces. In this disclosure, a score of A or higher is considered to indicate a low amount of transfer burrs.

[0098] [Evaluation 5] Evaluation of adhesion to the photosensitive drum The adhesion between the photosensitive drum of a full-color electrophotographic system (product name: LBP-672C, manufactured by Canon Inc.) and the electrophotographic belt b3 was measured using a jig as shown in Figure 6. The electrophotographic belt b3 is tensioned by a drive roller b1 equipped with a motor and torque meter, a driven roller b4, and a tension roller b6 that applies tension to the electrophotographic belt b3. The photosensitive drum b2 and backup roller b5 are the photosensitive drum and transfer roller of the LBP-672C, respectively.

[0099] The electrophotographic belt is rotated at 180 mm / second with the photosensitive drum not in contact, and the torque value at that time is measured. This value is designated as "Tq1". Next, the maximum torque is measured when the photosensitive drum is in contact with the electrophotographic belt at 700 gf while the electrophotographic belt is rotating at 180 mm / second. This value is designated as "Tq2".

[0100] The difference between "Tq2" and "Tq1" was used as an indicator to evaluate the adhesion between the electrophotographic belt and the photosensitive drum. If the difference was less than 0.10 Nm, the evaluation rank was "○", and if it was 0.10 Nm or more, the evaluation rank was "×". Furthermore, when bringing the electrophotographic belt into contact with the photosensitive drum, the photosensitive drum should be fixed in place without rotating, and the contact surface of the photosensitive drum should always be in a brand-new condition.

[0101] [Evaluation 6] Evaluation of toner color shift amount A full-color electrophotographic system (product name: LBP-672C, manufactured by Canon Inc.) was fitted with an electrophotographic belt, and under high temperature and high humidity conditions (temperature 30°C, relative humidity 80%), blue text and line images using cyan and magenta developers, and green text and line images using cyan and yellow developers were printed onto A3-sized plain paper (product name: GF-C081A3, manufactured by Canon Inc.). The resulting images were then observed under a microscope, and the amount of color shift in the images was measured.

[0102] [Example 1] (Preparation of the base layer) A thermoplastic resin composition was prepared by hot-melt kneading a pre-blended sample of the crystalline polyester and ionic conductive agent shown in Table 1 at a weight ratio of crystalline polyester / ionic conductive agent = 96 / 4 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 270°C to 320°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 10 hours.

[0103] Next, the obtained thermoplastic resin composition was placed into an injection molding machine (product name: SE180D, manufactured by Sumitomo Heavy Industries, Ltd.). The cylinder temperature was set to 270-320°C, and the mixture was injection molded into a test tube-shaped mold that was temperature-controlled 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, a length of 150 mm, and a thickness of 2 mm.

[0104] Next, the preform was stretched in two axial directions, its longitudinal and circumferential, using a biaxial stretching apparatus. First, as shown in Figure 3(a), the preform 205 was placed in a heating furnace 301 equipped with a non-contact heater (not shown) for heating the preform 205, and the heater was used to heat the outer surface temperature of the preform to 120-160°C.

[0105] Next, the blow mold 303, maintained at a mold temperature of 30°C, was lowered in the direction of arrow 307 relative to the heated preform 205, and the heated preform 205 was positioned at the opening of the blow mold 303 (Figure 3(b)). Then, as shown in Figure 3(c), the stretching rod 309 was driven in the direction of arrow 311, and simultaneously with the start of the stretching rod's drive, air heated to 23°C was introduced into the preform 205 from the opening, as indicated by arrow 313 in Figure 3(c). In this way, the preform 205 was stretched in two axial directions and made to adhere closely to the inner wall of the blow mold. The driving speed of the stretching rod 309 was 2.0 m / sec, and the pressure of the air introduced into the blow bottle was 0.5 MPa.

[0106] Next, the left mold 303-1 and the right mold 303-2 of the blow mold 303 were separated, and the bottle-shaped molded product (blow bottle) 317 was removed from the blow mold 303. Next, the resulting blow bottle 317 was placed inside a nickel cylindrical mold 401, manufactured by electroforming, which was placed on a base 407 as shown in Figure 4, and the outer mold 405 was attached. An air pressure of 0.1 MPa was applied inside the blow bottle, and the pressure was adjusted so that no air leaked out to the outside, thereby ensuring that the outer surface of the blow bottle 317 was in close contact with the inner surface of the cylindrical mold. Furthermore, while rotating the nickel cylindrical mold 401 at a constant speed of 2 revolutions per second, the entire circumference of the blow bottle was uniformly heat-treated at 130-190°C for 60 seconds using a heating heater 403.

[0107] Subsequently, the nickel cylindrical mold was cooled to room temperature (25°C) by blowing air at a temperature of 25°C onto it, the air pressure applied inside the blow bottle 317 was released, and a blow bottle 317 with improved dimensions due to annealing was obtained. From the dimensions of the preform 205 and the blow bottle 317, the biaxial stretching ratios were 4.0 times for the transverse stretching ratio (circumferential direction) Lp and 3.8 times for the longitudinal stretching ratio (direction perpendicular to the circumferential direction) La.

[0108] Next, as shown in Figure 3(d), the mouth side and the opposite side of the blow bottle 317 were cut to create a base layer for an electrophotographic belt with a circumference of 628 mm, a width of 250 mm, and a thickness of 70 μm.

[0109] (Formulation of curable compositions) The surface layer materials listed in Table 2 were weighed in the ratio AN / Fi1 / SL / IRG = 74.0 / 5.0 / 20.0 / 1.0 (mass ratio on a solid content basis), and the solutions obtained by coarsely dispersing the materials excluding SL were dispersed using a high-pressure emulsifier / disperser (product name: NanoVeta, manufactured by Yoshida Machinery Industry Co., Ltd.). This dispersion treatment was continued until the 50% average particle size of the contained Fi1 was 3 μm. The resulting dispersion (curable composition) was used as the coating liquid for the surface layer.

[0110] (Formation of the surface layer) The base layer is fitted onto the outer circumference of a cylindrical mold (circumference 628 mm), the ends are sealed, and the mold is immersed in a container filled with the surface coating liquid. The mold is then pulled up so that the relative speed between the liquid level of the coating liquid and the electrophotographic belt base layer remains constant. In this way, a coating film made of a curable composition is formed on the surface of the electrophotographic belt base layer. The pulling speed (relative speed between the liquid level of the coating liquid and the electrophotographic belt base layer) and the solvent ratio of the curable composition can be adjusted according to the desired thickness of the surface layer.

[0111] In this embodiment, the lifting speed was set to 20 mm / second, and the surface layer thickness was adjusted to approximately 2.0 μm. In this embodiment, the coating direction refers to the direction opposite to the direction in which the electrophotographic belt base layer is lifted. That is, the point where the belt is first lifted from the coating solution is the upstream point. The electrophotographic belt 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 are adjusted as appropriate based on the solvent type, solvent ratio, and film thickness. Subsequently, a UV irradiation device (product name: UE06 / 81-3, manufactured by iGraphic Co., Ltd.) was used on the coating film to achieve 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.

[0112] 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 its cross-section with an electron microscope (product name: XL30-SFEG, manufactured by FEI). Destructive testing revealed that the surface layer thickness was 1.8 μm. Thus, an electrophotographic belt with a surface layer formed on the outer surface of the base layer was obtained. This electrophotographic belt was subjected to the above evaluations (1) to (6).

[0113] [Examples 2-5] An electrophotographic belt was prepared and evaluated in the same manner as in Example 1, except that the formulation of the coating solution was as shown in Table 3.

[0114] [Example 6] An electrophotographic belt was fabricated and evaluated in the same manner as in Example 1, except that the coating solution was formulated in the proportions listed in Table 3, the lifting speed was 30 mm / second, and the surface layer was thickened.

[0115] [Table 3]

[0116] [Comparative Examples 1-3] An electrophotographic belt was prepared and evaluated in the same manner as in Example 1, except that the formulation of the coating solution was as shown in Table 4.

[0117] [Comparative Example 4] An electrophotographic belt was fabricated and evaluated in the same manner as in Example 1, except that the coating solution was formulated in the proportions listed in Table 4, the lifting speed was 40 mm / second, and the surface layer was thickened.

[0118] [Table 4]

[0119] Table 5 shows the evaluation results of the electrophotographic belts for Examples 1 to 6. Table 6 shows the evaluation results of the electrophotographic belts for Comparative Examples 1 to 4.

[0120] [Table 5]

[0121] [Table 6]

[0122] In Comparative Example 1, non-porous particles were used instead of porous spherical particles. That is, the ratio of (meth)acrylic resin and conductive particles present on the outer surface of the spherical particles was small, and it is thought that the transfer voids deteriorated because localized high-resistance areas were created.

[0123] In Comparative Example 2, the excessive inclusion of porous spherical particles reduced the average spacing S of the local peaks on the outermost surface. As a result, the surface irregularities decreased, and the adhesion to the photosensitive drum increased, which is thought to have led to a larger amount of toner color shift.

[0124] In Comparative Example 3, non-porous particles were incorporated to increase the amount of conductive particles. However, the non-porous particles could not be sufficiently coated with (meth)acrylic resin, and the ratio of conductive particles on the outer surface of the non-porous particles was small, resulting in the formation of localized high-resistance areas, which is thought to have worsened the transfer lumps.

[0125] In Comparative Example 4, the surface layer is thickened. That is, the porous spherical particles are coated with (meth)acrylic resin, and the conductive particles are uniformly distributed. However, because the surface irregularities are reduced, the adhesion to the photosensitive drum is improved, and it is thought that the amount of toner color shift is increased.

[0126] This embodiment includes the following configuration. (Composition 1) An electrophotographic belt having a surface layer, The surface layer contains (meth)acrylic resin, porous spherical particles, and conductive particles different from the porous spherical particles. At the outermost surface of the surface layer, the surface of the porous spherical particles is coated with the (meth)acrylic resin and the conductive particles. The ten-point average roughness Rz (according to JIS B 0601-1994) of the outermost surface of the surface layer is 0.5 times or more and less than 2 times the average primary particle diameter of the porous spherical particles. An electrophotographic belt characterized in that the average spacing S (in accordance with JIS B 0601-1994) of the local peaks on the outermost surface of the surface layer is 4 times or more and less than 30 times the average primary particle diameter of the porous spherical particles. (Configuration 2) The electrophotographic belt according to configuration 1, wherein the average primary particle diameter of the porous spherical particles is 1.0 μm or more and 10 μm or less. (Composition 3) The electrophotographic belt according to configuration 1 or 2, wherein the DBP oil absorption capacity of the porous spherical particles is 100 mL / 100 g or more and 200 mL / 100 g or less. (Composition 4) An electrophotographic belt according to any one of configurations 1 to 3, wherein the porous spherical particles are porous spherical silica particles or porous spherical silicone particles. (Composition 5) An electrophotographic belt according to any one of configurations 1 to 4, wherein the average primary particle diameter of the conductive particles is 0.01 μm or more and 0.04 μm or less. (Composition 6) An electrophotographic belt according to any one of configurations 1 to 5, wherein the conductive particles are conductive metal oxides. (Composition 7) An electrophotographic belt according to any one of configurations 1 to 6, wherein the thickness of the surface layer is less than or equal to the average primary particle diameter of the porous spherical particles. (Composition 8) An electrophotographic image forming apparatus comprising an electrophotographic belt described in any one of configurations 1 to 7 as an intermediate transfer belt. [Explanation of Symbols]

[0127] 1 Photosensitive drum 2. Charging device 3. Exposure apparatus 4. Developing device 5. Primary transfer roller 6. Intermediate transfer belt 7. Recording materials 9. Secondary transfer roller 11. Cleaning device (drum cleaner) 12. Cleaning device (cleaning blade) 20 Tension Rollers 21 Opposing Roller 22 drive rollers 28 Transfer bias application means 29 Transfer voltage detection means 201 Injection molding equipment 203 Cavity Type 205 Preform 207 core type 301 Heating furnace Type 303 309 Stretching rod 317 Blow Bottle 319 Biaxially oriented cylindrical film 401 Cylindrical mold 403 Heater 405 External mold 407 Base 500 Electrophotographic Belts 501 Base layer 502 Surface layer b1 Drive roller b2 Photosensitive drum b3 Electrophotographic belt b4 Driven roller b5 Backup Roller b6 Tension Roller

Claims

1. An electrophotographic belt having a surface layer, The surface layer contains (meth)acrylic resin, porous spherical particles, and conductive particles different from the porous spherical particles. At the outermost surface of the surface layer, the surface of the porous spherical particles is coated with the (meth)acrylic resin and the conductive particles. The ten-point average roughness Rz of the outermost surface of the surface layer (according to JIS B 0601-1994) is 0.5 times or more and less than 2 times the average primary particle diameter of the porous spherical particles. An electrophotographic belt characterized in that the average spacing S of the local peaks on the outermost surface of the surface layer (according to JIS B 0601-1994) is 4 times or more and less than 30 times the average primary particle diameter of the porous spherical particles.

2. The electrophotographic belt according to claim 1, wherein the average primary particle diameter of the porous spherical particles is 1.0 μm or more and 10 μm or less.

3. The electrophotographic belt according to claim 1, wherein the DBP oil absorption capacity of the porous spherical particles is 100 mL / 100 g or more and 200 mL / 100 g or less.

4. The electrophotographic belt according to claim 1, wherein the porous spherical particles are porous spherical silica particles or porous spherical silicone particles.

5. The electrophotographic belt according to claim 1, wherein the average primary particle diameter of the conductive particles is 0.01 μm or more and 0.04 μm or less.

6. The electrophotographic belt according to claim 1, wherein the conductive particles are conductive metal oxides.

7. The electrophotographic belt according to claim 1, wherein the thickness of the surface layer is less than or equal to the average primary particle diameter of the porous spherical particles.

8. An electrophotographic image forming apparatus comprising an electrophotographic belt as described in any one of claims 1 to 7 as an intermediate transfer belt.

Images