Electrophotographic belt, fixing device, and image forming apparatus

Abstract

To provide an electro-photographic belt and a fixing belt the metal layers of which are hardly separable and the inner layers are hardly shaved, even when having been stored in a hot and humid environment.SOLUTION: An electro-photographic belt comprises an endless shaped base that includes at least one of polyimide and polyamide imide, a metal layer that is provided on the outer circumferential face of the base, and a surface layer that is provided on the outer circumferential face of the metal layer, and further includes an inner surface layer that is provided in contact with the inner circumferential face of the base, the water vapor permeation of the inner surface layer being 10 g / (m2 day) or less.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This disclosure relates to an electrophotographic belt, a fixing device, and an image forming apparatus used in electrophotographic image forming apparatus such as a copier or printer. [Background technology]

[0002] Generally, in a thermal fixing device used in an image forming apparatus (hereinafter also simply referred to as a "fixing device"), a pair of heated rollers, a belt, or other rotating fixing members are pressed together. A recording medium containing an image formed by unfixed toner is then introduced into the pressure-contact area formed between these rotating bodies, heated, the toner melts, and the image is fixed to the recording medium.

[0003] Components for a fixing device include fixing members and pressure members. The rotating body that comes into contact with the unfixed toner image held on the recording medium is called the fixing member, and is referred to as a fixing roller, fixing belt, etc., depending on its form. On the other hand, the rotating body that does not come into contact with the unfixed toner image and is located on the opposite side of the recording medium is called a pressure member, and is referred to as a pressure roller, pressure belt, etc., depending on its form.

[0004] Patent Document 1 discloses a technique for preventing the delamination of the polyimide resin substrate layer and the metal layer when a fixing belt having an annular polyimide resin substrate layer and a metal layer provided on its outer surface is stored in a high-temperature, high-humidity environment. Patent Document 2 discloses a technique for suppressing the delamination of the resin substrate layer and the metal layer when a fixing belt having an annular resin substrate layer and a metal layer provided on the outer surface of the resin substrate layer is repeatedly fixed after being stored for a long period in a high-temperature, high-humidity environment, and used in an electromagnetic induction heating fixing device. Patent Documents 1 and 2 disclose that the problem of delamination of the resin substrate layer and the metal layer is caused by moisture at the interface between the resin substrate layer and the metal layer.

[0005] Furthermore, in response to the above-mentioned problems, Patent Document 1 describes that by lowering the imidization rate of the outer surface of the polyimide resin substrate layer compared to the central part in the thickness direction, the wettability of the outer surface of the polyimide resin substrate layer with the plating solution is increased, and the adhesion between the polyimide resin substrate layer and the metal layer is improved even under high temperature and high humidity conditions (paragraph

[0019] ). Furthermore, Patent Document 2 describes that, in order to address the above-mentioned problems, by suppressing the water absorption rate of the resin substrate layer to 3% or less, the amount of moisture interposed at the interface between the resin substrate layer and the metal layer is reduced even when the fixing belt is stored in a high-temperature, high-humidity environment, thereby suppressing the peeling of the resin substrate layer and the metal layer (paragraphs

[0021] -

[0022] ). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2021-71678 [Patent Document 2] Japanese Patent Publication No. 2021-71679 [Overview of the project] [Problems that the invention aims to solve]

[0007] Patent documents 1 and 2 disclose measures to deal with moisture that has entered, but they do not disclose measures to prevent the moisture that causes the problem from entering in the first place. In the case of fixing belts using a base material (polyimide resin) that has been given new functions by mixing in fillers, it may not be possible to suppress water absorption by methods such as controlling the imidization rate of the polyimide resin alone. One aspect of this disclosure aims to provide an electrophotographic belt and a fixing belt in which the metal layer is less likely to peel off from the substrate and the inner layer is less likely to be abraded, even after being stored in a high-temperature, high-humidity environment. Furthermore, other embodiments of this disclosure aim to provide a fixing apparatus that contributes to the formation of high-quality electrophotographic images. [Means for solving the problem]

[0008] According to one aspect of this disclosure, An endless substrate comprising at least one of polyimide and polyamideimide, A metal layer provided on the outer surface of the base material, An electrophotographic belt comprising a surface layer provided on the outer circumferential surface of the metal layer, The substrate further comprises an inner layer provided in contact with the inner circumferential surface, The water vapor permeability of the inner layer is 10 g / (m³). 2 An electrophotographic belt is provided that is less than or equal to (day).

[0009] According to another aspect of this disclosure, a fixing belt for electrophotography is provided, wherein the thickness of the inner layer is 10 μm or more and 20 μm or less. According to other aspects of this disclosure, a fixing device having the fixing belt described above is provided. Furthermore, according to another aspect of the present disclosure, an image forming apparatus is provided, comprising: a photoreceptor; a charging device for charging the photoreceptor; an exposure device for exposing the charged photoreceptor to light to form an electrostatic latent image; a developing device for developing the electrostatic latent image formed on the photoreceptor with toner to form a toner image; a transfer device for transferring the toner image formed on the photoreceptor to a recording medium; and the fixing device, wherein the fixing device is a fixing device for heating an unfixed toner image on a recording medium with a fixing belt to fix it on the recording medium, and the fixing belt is the fixing belt described above. [Effects of the Invention]

[0010] The cause of delamination between the substrate and the metal layer is that moisture in the atmosphere permeates the substrate and reaches the interface between the substrate and the metal layer. According to one aspect of this disclosure, an electrophotographic belt and a fixing belt are provided in which the metal layer is less likely to peel off from the substrate and the inner layer is less likely to be abraded even when used for a long period of time in a high temperature and high humidity environment. According to another aspect of this disclosure, a fixing device and an image forming device are provided in which high-quality electrophotographic images can be formed and which have excellent paper feed durability.

Brief Description of Drawings

[0011] [Figure 1] It is a schematic diagram of an image forming apparatus in an embodiment. [Figure 2] It is a schematic diagram of a fixing device in an embodiment. [Figure 3] It is a schematic diagram of a fixing film in an embodiment.

Modes for Carrying Out the Invention

[0012] Hereinafter, an endless belt-shaped electrophotographic belt according to at least one embodiment of the present disclosure will be described in detail. Note that the technical scope of the present disclosure is not limited to the following description. The electrophotographic belt is used as a fixing belt, for example, in the image forming apparatus shown in FIG. 1. FIG. 1 is a cross-sectional view of a color electrophotographic printer, which is an example of the image forming apparatus of the present embodiment, and is a cross-sectional view along the sheet conveyance direction. In the present embodiment, the color electrophotographic printer is simply referred to as a "printer".

[0013] The printer shown in FIG. 1 includes image forming units 10 for each color of Y (yellow), M (magenta), C (cyan), and Bk (black). The photosensitive drum (photoconductor) 11 is pre-charged by a charger 12. Thereafter, the photosensitive drum 11 is exposed by a laser scanner 13 to form an electrostatic latent image. The electrostatic latent image becomes a toner image by a developing device 14. The toner image on the photosensitive drum 11 is sequentially transferred to, for example, an intermediate transfer belt 31, which is an image carrier, by a primary transfer blade 17. After the transfer, the toner remaining on the photosensitive drum 11 is removed by a cleaner 15. As a result, the surface of the photosensitive drum 11 becomes clean and is prepared for the next image formation.

[0014] On one hand, the recording material P is fed one by one from the paper feed cassette 20 or the multi-feed tray 25 and sent into the resist roller pair 23. The resist roller pair 23 once receives the recording material P and straightens it when the sheet is skewed. Then, the resist roller pair 23 feeds the recording material P between the intermediate transfer belt 31 and the secondary transfer roller 35 in synchronization with the toner image on the intermediate transfer belt 31. The color toner image on the intermediate transfer belt is transferred to the recording material P by, for example, the secondary transfer roller 35 which is a transfer member. After that, the toner image on the sheet is fixed to the sheet by heating and pressurizing the sheet with the fixing device 40.

[0015] Next, the fixing device 40 used in this embodiment will be described. The fixing device 40 is an electromagnetic induction type fixing device including the fixing belt according to the above embodiment. As shown in FIG. 2, a pressure roller (pressure member) 44 is arranged to press a part of the endless fixing belt 41, and a fixing nip portion N is formed between the fixing belt 41 and the pressure roller 44 from the viewpoint of performing fixing efficiently.

[0016] An opposing member 43 is arranged at a position inside the fixing belt 41 facing the pressure roller 44. The opposing member 43 is made of metal, heat-resistant resin, heat-resistant rubber, etc., and has a pad 43b that locally increases pressure by contacting the inner peripheral surface of the fixing belt 41 and a support 43a that supports the pad 43b. An electromagnetic induction heating device 42 incorporating an electromagnetic induction coil (excitation coil) 42a is provided at a position facing the pressure roller 44 around the fixing belt 41. The electromagnetic induction heating device (electromagnetic induction device) 42 applies an alternating current to the electromagnetic induction coil, changes the generated magnetic field with an excitation circuit, and generates eddy currents in the metal layer inside the fixing belt 41. Then, these eddy currents are converted into heat (Joule heat) by the electrical resistance of the metal layer, and as a result, the surface of the fixing belt 41 generates heat.

[0017] The position of the electromagnetic induction heating device 42 is not limited to the position shown in Figure 2. For example, it may be installed upstream of the contact area of ​​the fixing belt 41 in the rotational direction 45, or it may be installed inside the fixing belt 41. The pressure roller 44 is driven to rotate in the rotational direction 45 at a predetermined peripheral speed by a driving means (not shown). This rotational drive of the pressure roller 44 causes a rotational force to act on the cylindrical fixing film 41 due to the pressure friction force at the fixing nip portion N between the pressure roller 44 and the fixing film 41. The fixing film 41 then slides in close contact with the downward surface of the pad 43b and enters a state of driven rotation in the same direction as the rotational direction 45. The opposing member 43 also serves as a rotation guide member for the cylindrical fixing film 41.

[0018] The pressure roller 44 is driven to rotate, causing the cylindrical fixing film 41 to rotate along with it. The electromagnetic induction heating device 42 rapidly heats the surface of the fixing belt 41 to a predetermined temperature, creating a temperature-controlled state. In this state, a recording material P carrying an unfixed toner image T is introduced between the fixing film 41 and the pressure roller 44 in the fixing nip section N. The toner image-carrying side of the recording material P then adheres closely to the outer surface of the fixing film 41 in the fixing nip section N, and the fixing nip section T is clamped and conveyed together with the fixing film 41. During this clamping and conveying process, the recording material P is heated by the heat generated by the fixing film 41 due to the eddy currents described above, and the unfixed toner image T on the recording material P is heated and pressurized, melting and fixing it onto the recording material P. The recording material P that has passed through the fixing nip section N is separated from the outer surface of the fixing film 41 by curvature and discharged and conveyed.

[0019] Next, we will describe the fixing belt in detail. As shown in Figure 3, the fixing belt 41 of this disclosure has an inner surface layer 41a on its innermost circumferential surface, and comprises a base layer 41b, a metal layer 41c, an elastic layer 41d, and a surface layer 41e in that order. In addition, adhesive layers (not shown) may be used to bond the metal layer 41c and the elastic layer 41d, and the elastic layer 41d and the surface layer 41e, in order to improve adhesion.

[0020] (1) Inner layer 41a The material of the inner layer 41a should be as impermeable to moisture as possible, and the fixing belt 41 needs to be heat-resistant because it generates heat due to electromagnetic induction. As a means of evaluating whether or not moisture permeates, the method for determining the water vapor permeability of plastic films and sheets (JIS K-7129-1) is specified as follows: WVTRs(g / (m 2 *day) = WVTRstd × TR / TS × AR / AS WVTRs: Water vapor transmission rate of the test specimen g / (m³) 2 ·day) WVTRstd: Water vapor transmission rate of standard test specimen g / (m³) 2 ·day) TR: For a standard test specimen, the time (s) required for the relative humidity in the low-humidity chamber to increase from the initial level to the final level. TS: For each test specimen, the time (s) required for the relative humidity in the low-humidity chamber to increase from the initial level to the final level. AR: Permeation area of ​​standard test specimen (m²) 2 ) AS: Permeation area of ​​the test specimen (m²) 2 ) Here, a standard test specimen refers to a sample with a known water vapor transmission rate.

[0021] Furthermore, although JIS K-7129-1 does not specify thickness, it is preferable to measure the actual thickness used, as thickness affects water vapor transmission. Water vapor transmission rate is 10 g / m³ 2 Heat-resistant resins or metals are used as materials that meet the following conditions and are heat-resistant. Furthermore, to improve adhesion with the substrate 41b, a primer or adhesive (not shown) may be applied to the inner surface of the substrate 41b.

[0022] Examples of heat-resistant resins include tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polyether ether ketone resin (PEEK), polyvinylidene chloride resin, and high-density polyethylene resin (high-density PE). Among these, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) is particularly preferred. As a metal, stainless steel is preferred due to its excellent strength, flexibility, and rust resistance, as well as the fact that it does not generate heat due to eddy currents when used with induction heating (IH). Furthermore, from the viewpoint of strength, flexibility, and heat capacity, the thickness is preferably 10 μm to 20 μm.

[0023] (2) Base material 41b The base layer 41b is made of at least one of polyimide and polyamideimide, from the viewpoint of having excellent heat resistance, strength, flexibility, and heat capacity. In particular, it is preferable to include at least one of aromatic polyimide resin and polyamideimide resin. The thickness of the base material is not particularly limited, but from the viewpoint of ensuring the flexibility of the electrophotographic belt, it is preferable to have a thickness of, for example, 20 μm to 100 μm. The outer surface of the substrate 41b may be subjected to a surface treatment to provide adhesion to the metal layer 41c. The surface treatment can be one or more types of physical treatments such as blasting, lapping, and polishing, or chemical treatments such as oxidation, coupling agent treatment, and primer treatment.

[0024] (3) Metal layer 41c The metal layer 41c is a heating layer that generates heat through eddy currents produced within the layer when a magnetic field is applied, and is composed of a metal that exhibits electromagnetic induction. Examples of metals that exhibit electromagnetic induction include single metals such as nickel, iron, copper, gold, silver, aluminum, chromium, tin, and zinc, or alloys containing two or more metals. Considering cost, heat generation performance, and workability, copper, nickel, aluminum, iron, and chromium are suitable, and among these, copper or alloys mainly composed of copper are particularly preferred.

[0025] The optimal thickness of the metal layer 41c varies depending on the material of the metal. For example, when copper is used for the metal layer 41c, from the viewpoint of efficiently generating heat, the thickness of the metal layer 41c is preferably 3 μm to 50 μm, more preferably 3 μm to 30 μm, and even more preferably 5 μm to 20 μm. Furthermore, while electroplating is preferred as the method for forming the metal layer 41c, when using a substrate 41b made of resin, it is difficult to perform electroplating directly, so it is necessary to form an undercoat metal layer (not shown) on the outer surface of the substrate layer 41b.

[0026] Furthermore, to improve the film strength of the metal layer 41c, suppress cracking due to repeated deformation and oxidative degradation due to repeated heating over long periods, and maintain the heat generation characteristics, a metal protective layer (not shown) in contact with the metal layer 41c may be provided. Specifically, it is often composed of copper or nickel, and in particular, it is preferable to include nickel (or a nickel alloy), which is an oxide-resistant metal, from the viewpoint of suppressing the occurrence of cracks due to repeated deformation and oxidative degradation due to repeated heating.

[0027] (4) Elastic layer 41d The material of the elastic layer is not particularly limited, and known materials used as elastic layers for fixing members such as fixing rotating bodies can be used. It is preferable that the elastic layer contains silicone rubber, which has excellent heat resistance. Furthermore, addition-curing type liquid silicone rubber is preferably used as the raw material for the silicone rubber. The thickness of the elastic layer can be appropriately designed considering the surface hardness of the fixing belt 41 and the width of the fixing nip portion to be formed. The thickness of the elastic layer is preferably 100 μm to 500 μm, and more preferably 200 μm to 400 μm. By setting the thickness of the elastic layer within this range, a sufficient width of the fixing nip portion can be ensured when the fixing belt 41 is assembled into the fixing device.

[0028] The elastic layer may contain fillers. Fillers are added to control thermal conductivity, heat resistance, and elastic modulus. Specifically, the following are examples: silicon carbide (SiC), silicon nitride (Si3N4), silica (SiO2), boron nitride (BN), aluminum nitride (AlN), alumina (Al2O3), iron oxide (Fe2O3), zinc oxide (ZnO), magnesium oxide (MgO), titanium dioxide (TiO2), copper (Cu), aluminum (Al), silver (Ag), iron (Fe), nickel (Ni), carbon black (C), carbon fiber (C), carbon nanotubes (C), etc. Furthermore, the material constituting the elastic layer may contain a reaction control agent (inhibitor) called an inhibitor to control the reaction initiation time. Known substances such as methyl vinyltetrasiloxane, acetylene alcohols, siloxane-modified acetylene alcohol, and hydroperoxides can be used as reaction control agents.

[0029] (5) Surface layer 41e The surface layer 41e contains tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) and perfluoropolyether (PFPE). A fluororesin material with a thickness of 100 μm or less, preferably 10 to 70 μm, can be used. Examples of fluororesin materials include polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), and PFA. [Examples]

[0030] Next, the method for manufacturing the fixing member used in this embodiment will be described. In this embodiment, a fixing belt as shown in Figure 3 was manufactured using the following manufacturing method consisting of steps 1 to 7.

[0031] (Process 1) A stainless steel mold with an inner diameter of 25 mm and a width of 400 mm was prepared. A polyimide precursor coating (product name: YUPIA-AT, UBE Corporation) was applied to the mold, and then it was baked at 390°C for 60 minutes. By peeling the polyimide coating from the surface of the stainless steel mold, an endless belt-shaped polyimide resin substrate with an inner diameter of 25 mm, a film thickness of 60 μm, and a length of 390 mm was obtained.

[0032] (Process 2) A liquid silicone rubber primer was applied to the inner surface of a polyimide resin substrate and allowed to dry. After drying, an addition-curing silicone rubber adhesive (product name: SE1819CV, an equal mixture of "liquid A" and "liquid B" from Toray Dow Corning) was applied almost uniformly to a thickness of approximately 20 μm. A fluororesin tube (PFA, 5 μm thick, melting point 306°C, product name: NSE, Gunze Corporation), whose outer surface had been hydrophilically treated by laser etching, was placed over the inner surface of the substrate, and excess adhesive was scraped out from between the polyimide resin substrate and the fluororesin tube by uniformly working the belt surface from above the fluororesin tube. Then, it was cured in an electric furnace set to a temperature of 200°C for 10 minutes. This resulted in a polyimide resin substrate with a PFA inner layer.

[0033] (Step 3) The outer surface of a polyimide resin substrate was blast-treated (specifically, by sandblasting with alumina abrasive particles, cutting, sanding, etc.), and then immersed in a sodium hydroxide aqueous solution adjusted to pH 11 at a temperature of 5°C for 5 minutes.

[0034] (Step 4) On the outer surface of a polyimide resin substrate, an electroless nickel plating layer with a thickness of 0.3 μm was sequentially formed as a base metal layer, an electrolytic copper plating layer with a thickness of 10 μm was formed as a metal heating layer, and a nickel layer with a thickness of 10 μm was formed as a metal protective layer.

[0035] (Step 5) As a raw material for forming the elastic layer, an addition-curing liquid silicone rubber containing a filler (product name: DY35-1355, manufactured by Toray Dow Corning Co., Ltd.) was prepared. After applying it to the outer surface of the substrate using the ring coating method, the layer of addition-curing silicone rubber composition was crosslinked by heating at 200°C for 1 hour to form an elastic layer with a thickness of 300 μm.

[0036] (Step 6) A substrate with an elastic layer formed on it was rotated circumferentially at a speed of 20 mm / second, and ultraviolet light was irradiated onto the surface of the elastic layer in an atmospheric environment using an ultraviolet lamp positioned 10 mm away from the surface of the elastic layer. A low-pressure mercury ultraviolet lamp (product name: GLQ500US / 11, manufactured by Toshiba Lighting & Technology Corporation) was used as the ultraviolet lamp, and the integrated light amount at a wavelength of 185 nm on the irradiated surface was 800 mJ / cm². 2 The irradiation was applied in such a manner that it resulted in the following: Next, an addition-curing silicone rubber adhesive (product name: SE1819CV, a mixture of equal parts of "liquid A" and "liquid B" manufactured by Toray Dow Corning) was applied to the surface of the elastic layer in a nearly uniform manner to a thickness of approximately 20 μm.

[0037] (Step 7) A fluororesin tube (PFA-1, 20 μm thick, melting point 306°C, product name: NSE, Gunze Corporation) with a hydrophilic inner surface treated by laser etching was placed over the belt, and the belt surface was uniformly rubbed from above the fluororesin tube to remove excess adhesive from between the elastic layer and the fluororesin tube. Then, the base layer, which was covered with an elastic layer and a surface layer, was placed in an electric furnace set to a temperature of 200°C, heated for 1 hour to cure the adhesive, and the fluororesin tube was bonded onto the elastic layer. The ends were then cut to obtain a fixing belt with a width of 350 mm.

[0038] [Example 2] In step 2 of Example 1, a fixing belt was obtained in the same manner as in Example 1, except that a fluororesin tube with a thickness of 10 μm was used as the outer surface of which had been hydrophilically treated.

[0039] [Example 3] In step 2 of Example 1, a fixing belt was obtained in the same manner as in Example 1, except that a fluororesin tube with a thickness of 20 μm was used as the outer surface of which had been treated to be hydrophilic.

[0040] [Example 4] In step 2 of Example 1, a fixing belt was obtained in the same manner as in Example 1, except that a fluororesin tube with a thickness of 50 μm was used as the outer surface of which had been treated to be hydrophilic.

[0041] [Example 5] By the method described below, a polyimide resin substrate having a stainless steel (SUS) cylindrical body (metal inner layer) instead of a PFA inner layer was obtained as an inner layer that can withstand the firing temperature of polyimide.

[0042] (Process 1) A stainless steel cylinder with an inner diameter of 25 mm, a width of 390 mm, and a thickness of 20 μm was prepared. A stainless steel mold with an outer diameter of 25 mm and a width of 450 mm was fitted inside this cylinder, and a polyimide precursor coating was applied to the surface of the cylinder to create a film, which was then baked at a temperature of 390°C for 60 minutes. By removing the stainless steel mold from the stainless steel cylinder, a polyimide resin substrate having an endless belt-shaped metal inner layer was obtained. The various sizes of this polyimide resin substrate having a metal inner layer are as follows. Inner diameter 25 mm, film thickness (sum of the thickness of the polyimide resin substrate and the metal inner layer) 60 μm, length 390 mm. The fixing belt was obtained using the same method as in step 3 and subsequent steps of Example 1.

[0043] [Example 6] An anchoring belt was obtained in the same manner as in Example 1, except that in step 2 of Example 1, a polyetheretherketone resin tube (PEEK, seamless belt, Gunze Corporation, 10 μm thickness) with a hydrophilic outer surface was used instead of a fluororesin tube with a hydrophilic outer surface.

[0044] [Example 7] An anchoring belt was obtained in the same manner as in Example 1, except that in step 2 of Example 1, a high-density polyethylene resin tube with a hydrophilic outer surface (Ube Film Co., Ltd., 10 μm thickness) was used instead of a fluororesin tube with a hydrophilic outer surface.

[0045] [Comparative Example 1] An image fixing belt was obtained in the same manner as in Example 1, except that Step 2 was not carried out.

[0046] [Comparative Example 2] In Step 2 of Example 1, an image fixing belt was obtained in the same manner as in Example 1, except that a polyethersulfone resin tube (PES, Sumikaexcel, manufactured by Sumitomo Chemical Co., Ltd., 20 μm thick) having a hydrophilic outer surface was used instead of the fluororesin tube (PFA, 10 μm thick).

[0047] (Method for measuring water vapor transmission rate) The water vapor transmission rate of each image fixing belt was measured according to the method described above. For each measurement sample, the water vapor transmission rate of the base material was measured by cutting the base material at the stage of Step 1 of Example 1, the PFA inner layer was measured by cutting the image fixing belt at the stage of Step 2 of Example 1, and the metal inner layer was measured by cutting the belt of Step 1 of Example 2. The cut size was a square with a side length of 7 cm in each case.

[0048] The following were used as standard test pieces. Known sample: polystyrene film Water vapor permeability: 30 g / (m 2 ·day) Thickness: 25 μm Also, when measuring the water vapor permeability for comparison of the sheet functions, in the present disclosure, the comparison is made while the thicknesses of the base material and the inner layer are different. This is because peeling between the base material and the metal layer affects the amount of moisture reaching between the base material and the metal layer, and thus correct evaluation cannot be made if the thicknesses are made uniform for measurement.

[0049] (Image formation evaluation) The image fixing belts of each example were stored in an environment at a temperature of 95 °C and a relative humidity of 100% for 96 hours. After storage, the image fixing belts were attached to the fixing device of the image forming apparatus described above. The outer peripheral temperature of the image fixing belt in the region contacting the recording material was controlled to be 130 °C. Using this image forming apparatus, image formation evaluation was carried out using GF-C081 (manufactured by Nippon Paper Industries Co., Ltd.) as the A4 paper recording material.

[0050] <Image Formation Evaluation 1> In Image Formation Evaluation 1, ten halftone images with an image density of 50% were printed. The printed images were visually inspected for poor image quality, the presence or absence of paper wrinkles, and the presence or absence of delamination at the interface between the substrate layer and the metal layer of the fixing belt. The criteria for judgment were as follows: A: When none of the following occur: delamination at the interface, poor image quality, or paper creasing. B: If one or more of the following occur: delamination at the interface, poor image quality, or paper wrinkles

[0051] <Image Formation Evaluation 2> In image formation evaluation 2, the lifetime of the inner layer was evaluated. The following evaluations were performed based on the number of prints in which the inner layer was scraped away, exposing the substrate. A: The number of printed pages exceeded 700,000, causing the inner layer to wear away and the substrate to be exposed. B: The number of printed sheets was between 500,000 and 700,000, and the inner layer was worn away, exposing the substrate. C: The number of printed pages was less than 500,000, and the inner layer was worn away, exposing the substrate.

[0052] <Image Formation Evaluation 3> In Image Formation Evaluation 3, the time it takes for the surface of the fixing belt to reach 160°C after power-on was defined as the "rise time," and it was evaluated as follows by comparing it with the rise time when using a fixing belt made by a conventional method (Comparative Example 1). A: If the startup time is within +5 seconds B: If the startup time exceeds +5 seconds but is within +10 seconds. Table 1 shows the evaluation results for this example and the comparative example.

[0053] [Table 1]

[0054] From the above results, it can be seen that the fixing belt of this embodiment suppresses peeling at the interface, suppresses the occurrence of poor image quality or paper wrinkles, and also suppresses other adverse effects compared to the fixing belt of the comparative example. [Explanation of Symbols]

[0055] 10: Image forming unit 11: Photosensitive drum (photoconductor) 12: Charger (charging device) 13: Laser scanner (exposure device) 14: Developing machine (developing device) 15: Cleaner 17: Primary transfer blade 20: Paper feed cassette 25: Multi-purpose paper tray 23: Resistola vs. 31: Intermediate transfer belt 35: Secondary transfer roller 40: Fuser (fusing device) 41: Fixing belt 41a: Inner layer 41b: Base material 41c: Metal layer 41d: Elastic layer 41e: Surface layer 42: Electromagnetic induction heating device 42a: Electromagnetic induction coil 43: Opposing member 43a: Support 43b: Pad 44: Pressure roller 45: Fixing belt / pressure roller rotation direction N: Fixing nip section P: Recording material T: Toner

Claims

1. An endless substrate comprising at least one of polyimide and polyamideimide, A metal layer provided on the outer surface of the base material, An electrophotographic belt comprising a surface layer provided on the outer circumferential surface of the metal layer, The substrate further comprises an inner layer provided in contact with the inner circumferential surface, The water vapor permeability of the inner layer is 10 g / (m²). ２ An electrophotographic belt characterized by being less than or equal to (day).

2. The electrophotographic belt according to claim 1, wherein the thickness of the inner surface layer is 10 μm or more and 20 μm or less.

3. The electrophotographic belt according to claim 1, wherein the inner layer comprises at least one selected from the group consisting of PFA, PEEK, and high-density PE.

4. The electrophotographic belt according to claim 1, wherein the electrophotographic belt is a fixing belt.

5. A fixing device that brings an unfixed toner image on a recording medium into contact with a fixing belt, and heats the unfixed toner image with the fixing belt to fix it onto the recording medium, The fixing belt is an electrophotographic belt according to any one of claims 1 to 4. A fixing device characterized by the following features.

6. Photoreceptor and A charging device for charging the photoreceptor, An exposure apparatus that exposes a charged photoreceptor to form an electrostatic latent image, A developing apparatus that develops an electrostatic latent image formed on a photoreceptor with toner to form a toner image, A transfer device for transferring the toner image formed on the photoreceptor to a recording medium, The fixing device according to claim 5, An image forming apparatus characterized by having the following features.

Images