Rotating body for fixing, fixing device, and electrophotographic image forming apparatus

Abstract

To provide a rotating body for fixing excellent in durability even in such a printing environment in which a high temperature state of the rotating body for fixing continues for a long time.SOLUTION: A rotating body for fixing comprises: a base material containing resin; a heat generating layer containing silver on the base material; and a protective layer containing resin on a surface of the heat generating layer on the opposite side of a side facing the base material. The heat generating layer extends in a circumferential direction of an outer peripheral surface of the base material. The heat generating layer is a layer including a porous portion. At least one of the base material and the protective layer includes particles having an effect of preventing oxidation of the heat generating layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a fixing rotor and fixing device used in a fixing device of an electrophotographic image forming apparatus such as an electrophotographic copying machine or printer, and to an electrophotographic image forming apparatus. [Background technology]

[0002] A fixing device installed in an electrophotographic image forming apparatus such as an electrophotographic copier or printer generally heats a recording material carrying an unfixed toner image while transporting the recording material in a nip formed by a heated fixing rotor and a pressure roller in contact with the heated rotor, thereby fixing the toner image to the recording material.

[0003] An electromagnetic induction heating type fixing device has been developed and put into practical use. The fixing device has a heating layer on the fixing rotor, and this heating layer can generate heat directly. The advantage of the electromagnetic induction heating type fixing device is that it has a short warm-up time. The heat generating layer is required to have electrical conductivity and durability against repeated strain under heating. For example, Patent Document 1 discloses a fixing member having a first metal layer containing Cu as a heat generating layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-051136 Summary of the Invention [Problem to be solved by the invention]

[0005] The inventors attempted to apply silver nanoink, which allows for fine control of line width and spacing, when forming the heat-generating layer, in the hope of minimizing uneven heat generation. Heat-generating layers formed with silver nanoink can be formed into thin layers, which is advantageous for flex resistance. Furthermore, the heat-generating layer contains submicron-sized pores. Therefore, the pores exert a damping effect against compressive stress caused by pressure and heat application, suppressing buckling and other problems. As a result, improved durability can also be expected.

[0006] Meanwhile, in the fixing rotor, there is a phenomenon in which the temperature of the components rises at the end where paper does not pass, the so-called non-paper passing area. The fixing rotor is constantly heated to maintain the fixing temperature in the paper passing area where paper passes, in order to reliably fix the toner. In the paper passing area, the paper absorbs heat as it passes, so continuous heating is required. Meanwhile, in the non-paper passing area, there is no exchange of heat due to the passage of paper, so the component temperature can rise above the set temperature. This phenomenon is particularly likely to occur in special usage environments, such as when printing small-size paper continuously.

[0007] The inventors discovered that when a fixing rotor using silver nanoink to produce a heat-generating layer is used, if the non-paper-passing area remains at a high temperature above the set value for a long period of time, the resistance of the heat-generating layer increases. When this increase in resistance occurs in the non-paper-passing area for small-sized paper, uneven heat generation due to electromagnetic induction occurs, and when fixing paper larger than the small-sized paper, fixation at the edge of the paper decreases.

[0008] The present disclosure is directed to providing a fixing rotor that is highly durable even in a printing environment where the fixing rotor is kept at a high temperature for a long period of time, and a fixing device and an electrophotographic image forming apparatus that include the fixing rotor. [Means for solving the problem]

[0009] The present disclosure provides: A fixing rotor, The fixing rotor is a substrate including a resin; a heat generating layer containing silver on the substrate; a protective layer containing a resin on a surface of the heat generating layer opposite to the surface facing the substrate, the heat generating layer extends in the circumferential direction of the outer peripheral surface of the base material, the heat generating layer is a layer having a porous portion, The present invention relates to a fixing rotor, wherein at least one of the substrate and the protective layer contains particles that have the effect of preventing oxidation of the heat generating layer.

[0010] The present disclosure also provides an electrophotographic image forming apparatus, The electrophotographic image forming apparatus comprises: an image carrier that carries a toner image; a transfer device that transfers the toner image onto a recording material; a fixing device that fixes the transferred toner image onto the recording material; Equipped with The present invention relates to an electrophotographic image forming apparatus, wherein the fixing device is the fixing device described above. [Effects of the Invention]

[0011] According to the present disclosure, a fixing rotator having excellent durability even in a printing environment where the fixing rotator is kept at a high temperature for a long period of time is provided, and a fixing device and an electrophotographic image forming apparatus including the fixing rotator are also provided. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view of a heat generating layer formed from silver nanoink according to an embodiment. [Figure 2] Schematic diagram of an electrophotographic image forming apparatus according to an embodiment. [Figure 3] 1 is a schematic diagram illustrating a cross-sectional configuration of a fixing device according to an embodiment; [Figure 4] 1 is a schematic diagram illustrating a cross-sectional configuration of a fixing device according to an embodiment; [Figure 5] Schematic diagram of a magnetic core and an excitation coil of a fixing device according to an embodiment. [Figure 6]1 is a diagram showing a magnetic field formed when a current is passed through an excitation coil according to an embodiment; [Figure 7] Cross-sectional view of a fixing rotor according to an embodiment. [Figure 8] Schematic diagram showing the film formation mechanism of silver nanoink that forms the heat generating layer of the fixing rotor according to the embodiment. [Figure 9] Cross-sectional image and binarized image of the heat generating layer of the fixing rotator according to the embodiment DETAILED DESCRIPTION OF THE INVENTION

[0013] In the present disclosure, expressions such as "XX or more and YY or less" or "XX to YY" representing a numerical range mean a numerical range including the upper and lower limits, which are the endpoints, unless otherwise specified. When a numerical range is described in stages, the upper and lower limits of each numerical range can be combined arbitrarily. Furthermore, in the present disclosure, expressions such as "at least one selected from the group consisting of XX, YY, and ZZ" mean any 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] A fixing rotator having a heat generating layer according to the present disclosure, and a fixing device and an image forming apparatus including the fixing rotator will be described in detail below based on specific configurations. As mentioned above, when using a fixing rotor in which silver nano ink is used to manufacture the heat generating layer, if the temperature in the non-paper passing area remains higher than the set temperature for a long period of time, the resistance of the heat generating layer may increase. be. Figure 1 shows a cross-sectional view of a heat-generating layer formed using silver nanoink. 200a indicates crystals, 200b indicates pores, and 200c indicates the substrate or protective layer. The heat-generating layer formed using silver nanoink has pores 200b, and is characterized by a significantly larger grain boundary area compared to bulk silver. This means that the area over which the silver reacts with oxygen in the air is larger, making it more susceptible to oxidation than bulk silver and resulting in increased resistance.

[0015] The inventors have discovered that by incorporating particles that have the effect of preventing oxidation of the heat-generating layer into at least one of the resin-containing substrate and the resin-containing protective layer, it is possible to suppress an increase in the resistance of the heat-generating layer even when high-temperature conditions continue for a long period of time. The reason why the increase in resistance of the heating layer can be suppressed by incorporating particles having an anti-oxidation effect into at least one of the resin-containing substrate and the resin-containing protective layer is thought to be as follows: When at least one of the substrate and the protective layer contains particles having an anti-oxidation effect, oxygen in the air is trapped by the particles having an anti-oxidation effect before it reaches the heating layer. This reduces the amount of oxygen that reaches the heating layer. As a result, it is thought that oxidation of the heating layer is suppressed even at high temperatures, and an increase in resistance can be suppressed.

[0016] A fixing rotating member having a heat generating layer, and a fixing device and an electrophotographic image forming apparatus including the same will be described in detail below based on specific configurations. However, the dimensions, materials, shapes, and relative positions of the components described in this embodiment may be changed as appropriate depending on the configuration of the components to which the disclosure is applied and various conditions. In other words, the scope of this disclosure is not intended to be limited to the following embodiment. In addition, in the following description, components having the same function are denoted by the same numbers in the drawings, and their description may be omitted.

[0017] (Electrophotographic image forming apparatus) An electrophotographic image forming apparatus (hereinafter simply referred to as an "image forming apparatus") comprises an image carrier that carries a toner image, a transfer device that transfers the toner image to a recording material, and a fixing device that fixes the transferred toner image to the recording material. 2 is a cross-sectional view showing the overall configuration of a color laser beam printer (hereinafter referred to as printer) 1 as an example of an image forming apparatus equipped with a fixing device (image heating device) 15 according to this embodiment. A cassette 2 is housed in the lower part of the printer 1 so that it can be pulled out. The cassette 2 stores a stack of sheets P as recording materials. The sheets P in the cassette 2 are separated one by one by a separation roller 3 and then fed to a registration roller 4. As the recording material, sheet P, a variety of sheets of different sizes and materials can be used, including paper such as plain paper and cardboard, surface-treated sheet materials such as plastic film, cloth, and coated paper, and specially shaped sheet materials such as envelopes and index paper.

[0018] The printer 1 is equipped with an image forming unit 5 as an image forming means in which image forming units 5Y, 5M, 5C, and 5K corresponding to the colors yellow, magenta, cyan, and black are arranged side by side in a horizontal row. The image forming unit 5Y is equipped with a photosensitive drum 6Y which is an image carrier (electrophotographic photosensitive member), and a charging roller 7Y which serves as charging means for uniformly charging the surface of the photosensitive drum 6Y.

[0019] Furthermore, a scanner unit 8 is disposed below the image forming section 5. The scanner unit 8 forms an electrostatic latent image on the photosensitive drum 6Y by irradiating a laser beam that is on / off modulated in accordance with a digital image signal that is input from an external device such as a computer (not shown) based on image information and generated by an image processing means. Furthermore, the image forming section 5Y develops an electrostatic latent image on the photosensitive drum 6Y as a toner image by attaching toner to the electrostatic latent image on the photosensitive drum 6Y. and a primary transfer section 11Y that transfers the toner image on the photosensitive drum 6Y onto the intermediate transfer belt 10.

[0020] Toner images formed by similar processes at other image forming units 5M, 5C, and 5K are superimposed and transferred onto the toner image on intermediate transfer belt 10 transferred at primary transfer unit 11Y. As a result, a full-color toner image is formed on intermediate transfer belt 10. This full-color toner image is transferred onto sheet P at secondary transfer unit 12, which serves as a transfer means. Primary transfer unit 11Y and secondary transfer unit 12 are examples of fixing devices that fix the transferred toner images onto the recording material. Thereafter, the toner image transferred onto the sheet P (on the recording material) passes through a fixing device 15 and is fixed as a fixed image. The sheet P then passes through a discharge conveyance section 13 and is discharged and stacked on a stacking section 14.

[0021] The image forming unit 5 is an example of an image forming means. Although the primary transfer unit 11Y and the secondary transfer unit 12 are exemplified as fixing devices, the fixing device may be, for example, a direct transfer type fixing device that directly transfers a toner image from an image carrier to a sheet P. The image forming device may also be configured as a monochrome type that uses toner of only one color.

[0022] (fixing device) The fixing device 15 of this embodiment is an induction heating type fixing device (image heating device) that heats a fixing rotor by electromagnetic induction. That is, the fixing device includes a fixing rotor and an induction heating device that heats the fixing rotor by induction heating. FIG. 3 shows a cross-sectional configuration of the fixing device 15, and FIG. 4 is a perspective view of the fixing device 15. Note that the housing of the fixing device 15 and other components are omitted from FIGS. 3 and 4. In the following description, with respect to the components that make up the fixing device 15, the longitudinal direction X1 is the direction perpendicular to the conveyance direction of the recording material and the thickness direction of the recording material, i.e., the direction of the rotation axis of the fixing rotor 20.

[0023] The fixing device 15 includes a fixing rotor 20, a film guide 25, a pressure roller 21, a pressure stay 22, a magnetic core 26, an excitation coil, a thermistor 40, and a current sensor 30. The fixing device 15 heats the recording material on which an image has been formed, and fixes the image to the recording material. The fixing rotor 20 is the fixing rotor of this embodiment, and the pressure roller 21 is the opposing member of this embodiment. The excitation coil also functions as a magnetic field generating means of this embodiment. Details of the fixing rotor will be described later.

[0024] The fixing rotor 20 includes a substrate 20a, a heat generating layer 20b on the substrate 20a, and a protective layer 20e containing a resin on the surface of the heat generating layer opposite to the side facing the substrate. The heat generating layer 20b can generate heat by, for example, an induced current. The heat generating layer 20b can be formed as a heat generating pattern in which heat generating rings 201 (FIG. 4) are arranged in the longitudinal direction, and the heat generating rings 201 are electrically connected in the circumferential direction and formed in a ring shape, and are electrically divided in the longitudinal direction X1 (the direction of the rotation axis of the fixing rotor 20). In other words, the heat generating layer 20b can be configured to be divided into a plurality of annular regions that are each connected in the circumferential direction of the fixing rotor 20 and are not electrically connected to each other in the direction of the rotation axis of the fixing rotor 20. Each of the heat generating rings 201, which is a component of the heat generating pattern, is preferably formed with a uniform width in the longitudinal direction X1.

[0025] The pressure roller 21, which serves as an opposing body (pressure member) facing the fixing rotor 20, comprises a core metal 21a and an elastic layer 21b that is molded concentrically around the core metal to form a roller-like covering, with a release layer 21c provided on the surface. The elastic layer 21b is preferably made of a highly heat-resistant material such as silicone rubber, fluorine rubber, or fluorosilicone rubber. Both longitudinal ends of the core metal 21a are rotatably held between metal plates on the chassis side (not shown) of the device via conductive bearings. They are arranged in a manner similar to that shown in the figure.

[0026] As shown in FIG. 4, pressure springs 24a and 24b are respectively compressed between both longitudinal ends of the pressure stay 22 and spring bearing members 23a and 23b on the device chassis side, thereby applying a downward force to the pressure stay 22. In the fixing device 15 of this embodiment, a total pressure of approximately 100N to 300N (approximately 10kgf to 30kgf) is applied. As a result, the lower surface of the film guide 25, which is made of a heat-resistant resin such as polyphenylene sulfide (PPS), and the upper surface of the pressure roller 21 are pressed against each other with the fixing rotor 20, which is a cylindrical rotor, sandwiched therebetween, forming a fixing nip N of a predetermined width. The film guide 25 functions as a nip forming member that, together with the pressure roller 21, forms a nip that sandwiches and conveys the recording material carrying the toner image via the fixing rotor 20.

[0027] The pressure roller 21 is driven to rotate clockwise by a driving means (not shown), and exerts a counterclockwise rotational force on the fixing rotor 20 due to friction with the outer surface of the fixing rotor 20. As a result, the fixing rotor 20 rotates while sliding on the film guide 25.

[0028] 5 is a schematic diagram of the magnetic core 26 and the excitation coil of FIG. 3, and the fixing rotor 20 is indicated by a dashed line to explain the positional relationship with the fixing rotor 20. An induction heating device in an induction heating type fixing device that heats the fixing rotor 20 by electromagnetic induction may include the magnetic core 26 and the excitation coil 27. The exciting coil 27 is disposed inside the fixing rotor 20. The exciting coil 27 has a spiral-shaped portion whose spiral axis is approximately parallel to the direction along the rotation axis of the fixing rotor 20, and forms an alternating magnetic field that causes the heat-generating layer 20b to generate heat through electromagnetic induction. "Approximately parallel" does not mean that the two axes are completely parallel, but rather that a slight misalignment is allowed to allow the heat-generating layer to generate heat through electromagnetic induction. The magnetic core 26 is disposed in the spiral portion, extends in the direction of the rotation axis of the fixing rotor 20, and does not form a loop outside the fixing rotor 20. The magnetic core 26 guides the magnetic field lines of the alternating magnetic field.

[0029] 5, the magnetic core 26 is inserted into the hollow portion of the fixing rotor 20, which is a cylindrical rotor. The exciting coil 27 is wound spirally around the outer periphery of the magnetic core 26 and extends in the longitudinal direction of the fixing rotor 20. The magnetic core 26 has a cylindrical shape and is fixed by a fixing means (not shown) so as to be located approximately in the center of the fixing rotor 20 in a cross section viewed in the longitudinal direction (see FIG. 3).

[0030] The magnetic core 26 provided inside the excitation coil 27 has the role of guiding the magnetic field lines (magnetic flux) of the alternating magnetic field generated by the excitation coil 27 inward from the heat generating layer 20b of the fixing rotor 20, and forming a path (magnetic path) for the magnetic field lines. The material of the magnetic core 26 is preferably a material with low hysteresis loss and high relative permeability, such as at least one high-permeability soft magnetic material selected from the group consisting of sintered ferrite, ferrite resin, etc.

[0031] The cross-sectional shape of the magnetic core 26 need not be circular as long as it can be accommodated in the hollow portion of the fixing rotor 20, but a shape that allows the cross-sectional area to be as large as possible is preferable. The diameter of the magnetic core 26 is preferably 5 to 20 mm, and more preferably 8 to 12 mm. In the fixing device used in the examples of the present disclosure, the diameter of the magnetic core 26 was 10 mm, and the longitudinal length was 280 mm.

[0032] The exciting coil 27 is made of a copper wire (single conductor) with a diameter of 1 to 2 mm covered with heat-resistant polyamideimide, wound around the magnetic core 26 in a number of turns, preferably 5 to 40 turns, more preferably 10 to 30 turns. The excitation coil 27 is wound in a spiral shape. In the fixing device used in the examples of the present disclosure, the excitation coil 27 is wound in a spiral shape with 20 turns. The excitation coil 27 is wound around the magnetic core 26 in a direction intersecting the rotation axis direction of the fixing rotor 20. Therefore, when a high-frequency alternating current is applied to the excitation coil 27, an alternating magnetic field is generated in a direction parallel to the rotation axis direction, and an induced current (circulating current) flows in each heat-generating ring 201 of the heat-generating layer 20b of the fixing rotor 20 according to a principle described below, generating heat.

[0033] As shown in FIGS. 3 and 4, the thermistor 40 serving as temperature detection means for detecting the temperature of the fixing rotor 20 is composed of a spring plate 40a and a thermistor element 40b. The spring plate 40a is a support member having spring elasticity that extends toward the inner surface of the fixing rotor 20. The thermistor element 40b serving as a temperature detection element is installed at the tip of the spring plate 40a. The surface of the thermistor element 40b is covered with an insulator such as polyimide tape to ensure electrical insulation. The thickness of the insulator is preferably 10 to 100 μm, more preferably 25 to 75 μm. In the fixing device used in the examples of the present disclosure, a polyimide tape with a thickness of 50 μm was used.

[0034] The thermistor 40 is fixed to the film guide 25 and installed at approximately the center of the fixing rotor 20 in the longitudinal direction. The thermistor element 40b is pressed against the inner surface of the fixing rotor 20 by the spring elasticity of the spring plate 40a, and is maintained in contact with the inner surface. The thermistor 40 may also be arranged on the outer periphery of the fixing rotor 20.

[0035] The current sensor 30, which constitutes a continuity monitoring device that monitors the circumferential continuity of the heat-generating layer 20b, is disposed in the same position as the thermistor 40 in the longitudinal direction of the fixing device 15. That is, what is monitored by the current sensor 30 is the continuity state of the heat-generating ring 201 that is in contact with the thermistor element 40b, among the multiple heat-generating rings 201 that constitute the heat-generating pattern of the fixing rotor 20. The current sensor 30 is composed of an outer magnetic core 30a, an inner magnetic core 30b, and a detection coil 30c.

[0036] (Heating principle) The heating principle of the fixing rotor 20 in the induction heating type fixing device 15 will now be described. Fig. 6 is a conceptual diagram showing the moment when current increases in the direction of the arrow I0 in the excitation coil 27. The excitation coil 27 is inserted into the fixing rotor 20 and functions as a magnetic field generating means that generates an induced current I in the circumferential direction of the fixing rotor 20 by passing an alternating current through it. Furthermore, the magnetic core 26 functions as a component that induces magnetic field lines B (dotted lines in the figure) generated by the excitation coil 27 and forms a magnetic path. While in a typical induction heating method, magnetic field lines penetrate the heat-generating layer to generate eddy currents, in this embodiment, the magnetic field lines B loop around the outside of the fixing rotor. That is, the heat-generating layer 20b is primarily heated by the induced current induced by the magnetic field lines that emerge from one longitudinal end of the magnetic core 26, pass outside the heat-generating layer 20b, and return to the other longitudinal end of the magnetic core 26. This allows for efficient heat generation even when the heat-generating layer is thin, for example, 5 μm or less.

[0037] When an alternating magnetic field is formed by the excitation coil 27, an induced current I according to Faraday's law flows in each heat-generating ring 201 of the heat-generating layer 20b of the fixing rotor 20. Faraday's law states that "when the magnetic field in a circuit is changed, an induced electromotive force that tries to cause a current to flow in the circuit is generated, and the induced electromotive force is proportional to the time change in the magnetic flux that penetrates the circuit perpendicularly."

[0038] Consider the induced current I that flows through the heat-generating ring 201c located at the center in the longitudinal direction of the magnetic core 26 shown in FIG. 6 when a high-frequency alternating current is passed through the exciting coil 27. When a high-frequency alternating current is passed through the magnetic core 26, an alternating magnetic field is formed inside the magnetic core 26. At this time, the induced electromotive force acting on the heat-generating ring 201c is expressed as follows in Equation 1: It is proportional to the time change of the magnetic flux that penetrates vertically inside the heat ring 201c.

number

[0039] This induced electromotive force V causes an induced current I, which is a circular current that circulates around the heat-generating ring 201c, to flow, and the heat-generating ring 201c generates heat due to Joule heat generated by the induced current I. However, if the heat-generating ring 201c is broken, the induced current I does not flow, and the heat-generating ring 201c does not generate heat.

[0040] (1) Outline of the fixing rotor The fixing rotor of this embodiment will be described in detail with reference to the drawings. The fixing rotor according to one aspect of the present disclosure may be a rotatable member, such as an endless belt. 7 is a circumferential cross-sectional view of the fixing rotor of this embodiment. The fixing rotor has a substrate 20a, a heat-generating layer 20b on the substrate 20a, and a protective layer 20e on the surface of the heat-generating layer 20b opposite the side facing the substrate 20a. If necessary, an elastic layer 20c and a surface layer (release layer) 20d may be provided on the protective layer 20e. An adhesive layer 20f may also be provided between the elastic layer 20c and the surface layer 20d.

[0041] (2) Base material The material of the substrate 20a is not particularly limited as long as it is a layer containing a resin. That is, the substrate 20a contains a resin. When the belt is used in an electromagnetic induction type fixing device, the substrate 20a is preferably a layer that changes little in physical properties and maintains high strength when the heat-generating layer generates heat. For this reason, the substrate 20a preferably contains a heat-resistant resin as a main component, and is preferably made of a heat-resistant resin. The heat-resistant resin is a resin that does not melt or decompose at temperatures below 200°C (preferably below 250°C), for example.

[0042] The resin contained in the substrate 20a (preferably the resin constituting the substrate) is preferably at least one selected from the group consisting of polyimide (PI), polyamideimide (PAI), modified polyimide, and modified polyamideimide. More preferably, it is at least one selected from the group consisting of polyimide and polyamideimide. Among these, polyimide is particularly preferred. In the present disclosure, the term "main component" refers to the component that is contained in the largest amount by mass among the components constituting the object (here, the substrate). The modified polyimide and modified polyamideimide may be modified by siloxane, carbonate, fluorine, urethane, triazine, or phenol. The resin content in the substrate is not particularly limited, but is preferably 90 to 100% by mass, and more preferably 95 to 100% by mass.

[0043] In the fixing rotating member, the material of the substrate 20a can be analyzed by the following procedure. A sample measuring 10 mm square and the entire thickness is cut out from the fixing rotor, and if the sample contains an elastic layer or surface layer, it is removed with a razor or solvent, etc. The material of the obtained sample is confirmed by performing attenuated total reflection (ATR) measurement using an infrared spectrometer (FT-IR) (for example, Frontier FT IR, product name, manufactured by PerkinElmer). The material of the protective layer, which will be described later, is also analyzed in the same manner as above.

[0044] The substrate 20a preferably contains particles that have the effect of preventing oxidation of the heat generating layer, as will be described later. The substrate 20a may contain a filler to improve heat insulation and strength.

[0045] The shape of the substrate can be appropriately selected depending on the shape of the fixing rotary member, and can be various shapes such as an endless belt, a hollow cylinder, or a film. In the case of a fixing belt, the thickness of the substrate 20a is preferably, for example, 10 to 100 μm, and more preferably 20 to 60 μm. By setting the thickness of the substrate 20a within the above range, it is possible to achieve both high levels of strength and flexibility.

[0046] In addition, on the surface of the substrate 20a opposite to the side facing the heat generating layer 20b (the inner surface of the substrate), for example, a layer for preventing wear of the inner surface of the fixing rotor when the inner surface of the fixing rotor comes into contact with other members, or a layer for improving sliding properties with other members may be provided. Other members, such as sliding members, are disposed on the inner surface of the substrate 20a, and the sliding load is large. Therefore, from the viewpoint of easily ensuring the durability of the substrate, the substrate is preferably a solid layer. It is also preferable that the solid layer is located on the inner peripheral surface of the substrate.

[0047] The solid layer is a layer that does not substantially contain voids within the layer. "Substantially does not contain voids" means that voids are not intentionally provided, but the presence of voids that are inevitably mixed in due to scratches, cracks, chips, etc. is allowed. The presence or absence of voids can be observed by observing the cross section of the substrate. The cross section of the substrate can be observed in the same manner as the cross section observation of the protective layer described below. The substrate 20a can have a solid layer by using a cylindrical substrate that is molded without substantial voids. For example, in the case of thermosetting resins such as polyimide and polyamideimide, when the solvent in the coating film evaporates during molding, the sudden temperature rise can cause bumping, forming voids. Therefore, when volatilizing the solvent in the coating film, it is preferable to select a treatment temperature and treatment time that will prevent bumping. The solid layer preferably contains a resin, and the resin that the substrate may contain can be used as the resin that the solid layer may contain.

[0048] The outer peripheral surface of the base material 20a may be subjected to a roughening treatment such as blasting, or a modification treatment such as ultraviolet light, plasma, or chemical etching in order to improve adhesion and wettability with the heat generating layer 20b.

[0049] The process for obtaining the substrate is not particularly limited. For example, the substrate can be obtained by applying a substrate material containing a resin to the surface of a mold having a desired shape, such as a cylindrical shape, and heating it as necessary.

[0050] (3) Heat generating layer The heat-generating layer 20b is a layer that generates heat when current is applied. In the principle of heat generation by induction heating using an excitation coil, when an alternating current is supplied to an excitation coil arranged near the fixing rotor, a magnetic field is induced, and this magnetic field generates a current in the heat-generating layer 20b of the fixing rotor, which generates heat due to Joule heat. The heat-generating layer extends in the circumferential direction of the outer circumferential surface of the substrate.

[0051] The heat generating layer 20b contains silver. Silver has a low volume resistivity and is resistant to oxidation. The silver content of the entire heat generating layer 20b is preferably 90.0 mass % or more, more preferably 99.0 mass % or more, and particularly preferably 99.9 mass % or more. There is no particular upper limit, but examples include 99.999 mass % or less, and 99.99 mass % or less. That is, the heat generating layer The silver content relative to the total may be 90.0 to 99.999 mass%, 99.0 to 99.999 mass%, or 99.9 to 99.99 mass%.

[0052] The volume resistivity of the heat generating layer 20b is not particularly limited, but is preferably 1.0×10 -8 ~8.0×10 -8 Ω m, 2.0×10 -8 ~7.0×10 -8 Ω m, 2.0×10 -8 ~6.0×10 -8 When the resistivity is within the above range, the heat generating layer generates heat more easily. The volume resistivity of the heat generating layer can be adjusted by the firing temperature. The volume resistivity of the heat generating layer is measured using the following procedure. First, the resin layer of the fixing rotor is peeled off using a cutter. Then, measurements are performed using the following four-terminal resistance measurement method. Measurements are performed using a Hioki 3541 resistance meter and two FormFactor FPC-GS-500 probes. The resistance meter is set to low power mode, and the probes are pressed against the heating layer so that the distance between each sense probe is 20 mm, and the resistance value is measured. The measured resistance value is converted to volume resistivity using the width and film thickness of the heating layer. The width and film thickness of the heating layer are measured using a scanning electron microscope.

[0053] The silver contained in the heat-generating layer preferably has a crystalline structure. The number-average crystal grain size of the silver is preferably 500 nm or less, more preferably 250 nm or less, even more preferably 220 nm or less, particularly preferably 170 nm or less, and even more preferably 140 nm or less. When the number-average crystal grain size is within the above range, the heat-generating layer 20b can form numerous stable crystal interfaces even when the fixing rotor 20 is pressurized and deformed in the nip portion N and repeatedly subjected to stress. Therefore, the occurrence of cracks at the crystal interfaces is easily suppressed. The lower limit of the number average crystal grain size is not particularly limited, but examples include 10 to 500 nm, 10 to 250 nm, 10 to 220 nm, 10 to 170 nm, and 10 to 140 nm. The number average crystal grain size can be adjusted by adjusting the formation temperature of the heat generating layer. Specifically, increasing the formation temperature of the heat generating layer increases the number average grain size, and decreasing the formation temperature of the heat generating layer decreases the number average grain size. The method for measuring the number average crystal grain size will be described later.

[0054] The heat generating layer is a layer with a porous portion. Specifically, the heat generating layer has pores. The heat generating layer preferably has pores when observed in a circumferential cross section. More specifically, at least one pore is present in a circumferential cross section of the heat generating layer. When the heat generating layer is a layer with a porous portion, pores exist in the porous portion, and the damping effect reduces the difference between the compressive modulus of the heat generating layer 20b in the compression direction and the compressive modulus of the resin constituting the substrate and resin layer. If the difference in compressive modulus between the resin constituting the substrate or resin layer and the heat generating layer is small, excessive stress can be suppressed at the interface between the heat generating layer and the resin constituting the substrate or resin layer when the edge of the paper, or the so-called paper edge, is subjected to localized compressive deformation. From the standpoint of conductivity and durability, it is preferable to adjust the amount and size of the pores.

[0055] There are no particular limitations on the method for providing pores in the heat generating layer 20b. For example, after forming a pattern on the heat generating layer 20b using a photolithography process, holes can be formed by chemical etching, or holes can be formed using a laser or focused ion beam. This disclosure particularly describes the formation of pores using a silver nanoparticle material. When a silver nanoparticle material is used, the number-average crystal grain size of silver nanoparticles is smaller than that of bulk silver, so the grain boundary area tends to be larger than that of bulk silver. This makes it easier to suppress cracking at the crystal interface.

[0056] The heat-generating layer is preferably a fired (sintered) body of silver nanoparticles, and more preferably a fired body of a coating film of silver nanoink. When a coating containing silver nanoparticles with a particle size of approximately 10 to 50 nm is formed, the particles are layered as shown in Figure 8A. Due to the unstable surface energy of nanoparticles, the particles fuse together even when fired at a low temperature of approximately 100°C, and a film with nano-sized pores can be formed as shown in Figure 8B, resulting in a layer with porous portions. The size and number of pores can be expressed as the porosity.

[0057] Specifically, the proportion of pores in the cross section of the heat generating layer (hereinafter also referred to as porosity), measured by observing a cross section of the heat generating layer sampled from the fixing rotor and cut in the thickness direction, is preferably 15 to 50 area %, more preferably 15 to 45 area %, even more preferably 17 to 40 area %, particularly preferably 17 to 27 area %, and even more preferably 17 to 23 area %. The porosity can be increased by increasing the temperature at which the silver nanoink is baked to obtain the heat-generating layer, and the porosity can be decreased by decreasing the temperature at which the silver nanoink is baked to obtain the heat-generating layer.

[0058] The method for obtaining the heat generating layer is not particularly limited, but for example, it can be obtained by applying silver nanoink to the outer peripheral surface of the substrate and baking (sintering). The baking temperature is not particularly limited, but is preferably 150 to 450°C, and more preferably 250 to 350°C. The baking time is also not particularly limited, and can be, for example, 10 to 120 minutes.

[0059] The number average crystal grain size and porosity of silver in the heat generating layer are determined as follows. First, a sample for evaluation is prepared. A sample measuring 5 mm in length, 5 mm in width, and the entire thickness of the fixing rotor is taken from the center of the fixing rotor in the direction of its rotation axis. The resulting sample's circumferential cross section is polished using an ion beam. The polishing position is adjusted so that the circumferential cross section of the heating layer is exposed by the ion beam polishing. An ion milling device (product name: IM4000, manufactured by Hitachi High-Technologies Corporation) is used for cross-section polishing using an ion beam. Cross-section polishing using an ion beam can prevent filler from falling off from the sample and abrasive contamination, and can also form a cross-section with fewer polishing marks.

[0060] Next, a beaker containing a Nital solution containing 3 wt% nitric acid in ethanol is prepared. The sample, which has been subjected to cross-section processing using the ion beam, is immersed in the Nital solution and shaken for 12 seconds. The sample is then transferred to a beaker containing 100 wt% ethanol and subjected to ultrasonic cleaning for 60 seconds. An AS ONE VS-100III ultrasonic cleaner is used for ultrasonic cleaning. This process makes it easier to highlight particle boundaries when acquiring SEM images. Next, an osmium coater (trade name: Tennant 20) was used to form a 3 nm-thick thin film on the cross section of the ultrasonically treated sample to impart conductivity. The cross section of the heat-generating layer was then observed using a scanning electron microscope (SEM) (trade name: JSM-F100, manufactured by JEOL Ltd.), and cross-sectional images and EDS (Energy Dispersive X-ray Spectroscopy) images were obtained. The observation area was a 12.8 μm × 9.6 μm area, with the center of the heat-generating layer's thickness aligned with the vertical center of the SEM image. The observation conditions were a 10,000x backscattered electron image mode, and the backscattered electron image acquisition conditions were an accelerating voltage of 5.0 kV and a working distance of 10 mm.

[0061] Next, the obtained image is binarized using commercially available image software so that the crystal grains of the metal containing silver become white and the areas other than the crystal grains become black. Specifically, the backscattered electron image is read using ImageProPlus, an image analysis software manufactured by Media Cybernetics, and the brightness distribution of this image is calculated. Next, by setting the brightness range of the calculated brightness distribution, binarization is performed to distinguish between the crystal grains of the silver-containing metal and the areas other than the crystal grains. The binarization method used is the Otsu method.

[0062] Then, lines separating the crystal grains, which are obtained from the contrast difference due to the difference in brightness between the crystal grains or the difference in crystal orientation in the cross-sectional image of FIG. 9A, are added to the binarized image, and each crystal grain is separated. A binarized image is obtained (Figure 9B).

[0063] The black areas in Figure 9B represent pores in the heat-generating layer and materials of layers other than the heat-generating layer. Examples of materials other than the heat-generating layer include materials for the base material and protective layer, more specifically, polyimide and polyamideimide. Also included are particles that prevent oxidation of the heat-generating layer. The blackened areas can be confirmed as materials for layers other than the heat-generating layer by using EDS images and the proportions of elements in the blackened areas. For example, in the blackened areas, areas where the element C is present at 5% or more can be determined to be resins such as polyimide or polyamide-imide. For example, areas where the element Fe is present at 5% or more can be determined to be particles that prevent oxidation of the heat-generating layer. Of the blackened areas, areas excluding materials from layers other than the heat-generating layer are determined to be voids.

[0064] We will now explain how to calculate the number average crystal grain size from the binarized images of the cross section of the heating layer obtained in this way. Because digital image processing technology is applied to these images, it is assumed that all images are in a general digital image format with pixels arranged in a grid pattern. Furthermore, the binarized images are grayscale images containing only brightness information, and the images obtained by subsequently performing image processing on these images are all grayscale images in the same format unless otherwise noted.

[0065] First, calculate the circle-equivalent diameter of each silver crystal particle. The circle-equivalent diameter of each crystal particle refers to the diameter of a circle having the same area as the crystal particle. Specifically, calculate the number of pixels that make up each crystal particle, and multiply this number of pixels by the area of ​​one pixel to calculate the actual area of ​​the crystal particle. In the SEM images used in this disclosure, the length of one side of one pixel corresponds to 0.01 μm, so the number of pixels constituting each crystal grain is 0.01 × 0.01 μm 2 Furthermore, the diameter of a circle having this area is calculated to calculate the equivalent circle diameter. The total of the equivalent circle diameters of the crystal grains thus obtained is divided by the total number of crystal grains to calculate the number average crystal grain size.

[0066] The above procedure was repeated for six samples taken from the fixing rotor, and the average crystal grain size for each sample was calculated. The arithmetic mean of these six average crystal grain sizes was then calculated to calculate the number-average crystal grain size of the silver crystals in the heating layer. The six samples are collected as follows: As described above, one sample is collected from the center of the fixing rotor in the axial direction. Furthermore, when the length of the fixing rotor in the axial direction is L, one sample is collected from a portion 0.1 L away from the center in the axial direction. Similarly, samples are collected at portions 120° and 240° away from each of the collection points in the circumferential direction of the fixing rotor, for a total of six samples.

[0067] Next, a method for calculating the porosity from the binarized image of the cross section of the heating layer obtained by the above-mentioned procedure will be described. An image measuring 2.0 μm x 2.0 μm is cut out at the position of the heating layer in the binarized image obtained using the above procedure. Four images are cut out from one SEM image. The position from which the image is cut out is such that the center of the heating layer in the thickness direction is the center of the cut-out image in the vertical direction. The four images are also cut out so that the spacing between them is the same in the direction perpendicular to the thickness direction of the heating layer. Specifically, the images are cut out so that the spacing between adjacent images is 0.96 μm. The above operation is performed on six SEM images to obtain cross-sectional images at 24 locations.

[0068] Each particle of the metal crystal containing silver is shown as a white area, and the area occupied by each of these crystal particles in the image is calculated. Specifically, the number of pixels constituting each crystal particle is calculated, and the number of pixels is calculated. Calculate the total number of pixels. Add this total number of pixels to the area of ​​one pixel, 0.01 x 0.01 μm 2 By multiplying this by , the area occupied by the crystal grains can be calculated. As mentioned above, the blackened areas are voids and materials of layers other than the heat generating layer. Therefore, the area of ​​the blackened areas occupied by materials of layers other than the heat generating layer is calculated. Specifically, the number of pixels constituting each material of layers other than the heat generating layer is calculated, and the total number of pixels is calculated. This total number of pixels is multiplied by the area of ​​one pixel, 0.01 x 0.01 μm. 2 By multiplying this by , the area occupied by the material of the layers other than the heat generating layer can be calculated.

[0069] Since the porosity indicates the proportion of space not occupied by crystal particles or materials of layers other than the heat-generating layer, it is calculated as follows using the area occupied by the crystal particles and the area occupied by materials other than the heat-generating layer calculated above. Porosity (%)={2.0×2.0(μm 2 )-area occupied by crystal grains (μm 2 ) - Area occupied by materials of layers other than the heating layer (μm 2 )}÷{2.0×2.0(μm 2 )}×100 The above porosity calculation is performed for 24 locations within a range of 2.0 μm×2.0 μm in size on the cross-sectional image of the heat generating layer, and the average porosity obtained by arithmetically averaging is taken as the porosity of the heat generating layer.

[0070] The thickness of the heat generating layer 20b is preferably 5 μm or less. This is because a thickness of 5 μm or less provides the fixing rotor with adequate flexibility and reduces its heat capacity. Furthermore, a thickness of 5 μm or less further improves the bending resistance of the fixing rotor. As shown in FIG. 3, the fixing rotor 20 is rotated while being pressed by the film guide 25 and the pressure roller 21. With each rotation, the fixing rotor 20 is pressurized and deformed at the nip N, and is subjected to stress. It is preferable to design the heat-generating layer 20b of the fixing rotor 20 so that it will not break due to fatigue even if the fixing rotor is subjected to this repeated bending over the life of the fixing device. Reducing the thickness of the heat-generating layer 20b significantly improves the resistance of the heat-generating layer 20b to fatigue failure. This is because, when the heat-generating layer 20b is pressed and deformed to fit the curved surface of the film guide 25, the thinner the heat-generating layer 20b, the smaller the internal stress acting on the heat-generating layer 20b. For the above reasons, from the viewpoint of further improving resistance to a decrease in heat capacity and fatigue fracture, the thickness of the heat generating layer 20b is preferably 5 μm or less. Examples of the thickness of the heat generating layer 20b include 1 to 5 μm, 2 to 5 μm, and 2 to 4 μm.

[0071] The heat generating layer 20b extends in the circumferential direction of the outer peripheral surface of the base material 20a. The heat generating layer 20b may be configured in a predetermined pattern as long as it is capable of generating heat when energized. In particular, as shown in FIG. 4, a configuration in which a plurality of ring-shaped heat generating layers 20b are formed around the circumferential direction of the fixing rotor and electrically separated in the direction of the rotation axis is preferred. This configuration can suppress localized temperature increases if cracks occur in the heat generating layer 20b. It is preferred that the width of the ring shape in the direction of the rotor axis is approximately constant. On the other hand, such a pattern configuration increases the surface area of ​​the heat generating layer 20b, making it more susceptible to deterioration due to oxidation. In the fixing rotating body of the present disclosure, at least one of the base material and the protective layer contains particles that have the effect of preventing oxidation of the heat generating layer, so deterioration due to oxidation can be prevented even in such a case.

[0072] The ring width of the heat generating layer 20b is preferably 100 μm or more, more preferably 200 μm or more, and even more preferably 300 μm or more, from the viewpoints of manufacturability and heat generation. From the viewpoint of uneven heat generation, the ring width is preferably 1000 μm or less, more preferably 900 μm or less, and even more preferably 700 μm or less. Examples of the ring width include 100 to 1000 μm, 200 to 900 μm, and 300 to 700 μm.

[0073] The interval between the rings of the heat generating layer 20b is set to 50 μm or more from the viewpoint of manufacturability and heat generation. From the viewpoint of uneven heat generation, the spacing is preferably 400 μm or less, more preferably 300 μm or less. The spacing between the rings is, for example, 50 to 400 μm, or 100 to 300 μm.

[0074] (4) Resin layer In the present disclosure, the portion including the protective layer 20e, the elastic layer 20c, the adhesive layer 20f, and the surface layer 20d may be referred to as a resin layer. The fixing rotor always includes the protective layer among the resin layers, but may or may not include other resin layers. For example, the fixing rotor may include the protective layer among the resin layers and one surface layer.

[0075] (5) Protective layer The fixing rotor has a protective layer on the surface opposite to the side of the heat generating layer facing the substrate. The protective layer 20e protects the heat generating layer 20b and has the functions of ensuring insulation and improving the strength of the heat generating layer 20b. As long as the protective layer 20e contains a resin, other materials are not particularly limited. When the belt is used in an electromagnetic induction type fixing device, it is preferable that the protective layer 20e, like the base material 20a, be a layer that changes little in physical properties when the heat-generating layer 20b generates heat and maintains high strength. For this reason, the protective layer 20e preferably contains a heat-resistant resin, more preferably contains a heat-resistant resin as a main component, and further preferably is made of a heat-resistant resin. The heat-resistant resin is a resin that does not melt or decompose at temperatures below 200°C (preferably below 250°C), for example.

[0076] The resin contained in the protective layer 20e preferably contains at least one selected from the group consisting of polyimide (PI), polyamideimide (PAI), modified polyimide, and modified polyamideimide. More preferably, it is at least one selected from the group consisting of polyimide and polyamideimide. The modification is the same as that described for the substrate 20a. Among these, polyimide is particularly preferable. Note that the term "main component" refers to the component that is contained in the largest amount among the components that make up the object (here, the protective layer). The resin content in the protective layer is not particularly limited, but is preferably 90 to 100% by mass, and more preferably 95 to 100% by mass.

[0077] There are no particular limitations on the method for forming the base material 20a and the protective layer 20e. For example, an imide-based material can be formed into a film by coating it in a liquid form called varnish using a known method and baking it. The firing conditions are not particularly limited, and for example, the firing temperature may be 200 to 400° C., preferably 200 to 300° C., and more preferably 200 to 250° C. The firing time may be 15 to 60 minutes, and preferably 15 to 30 minutes.

[0078] The protective layer 20e may contain a filler to improve thermal insulation and strength, and as mentioned above, it is preferable that it contains particles that have the effect of preventing oxidation of the heat-generating layer to improve durability. A protective layer containing particles that have the effect of preventing oxidation of the heat-generating layer in this manner can be formed, for example, by pre-dispersing particles that have the effect of preventing oxidation of the heat-generating layer in the varnish to be applied. The coating method may be dipping, spraying, flow coating, ring coating, contact coating with a sponge, etc. In the present disclosure, a coating method using ring coating or the like will be explained.

[0079] The method for forming a protective layer containing particles that have the effect of preventing oxidation of the heat generating layer 20b on the heat generating layer 20b is specifically, for example, as follows: A PAI solution (Viromax HR-16N) containing particles that have the effect of preventing oxidation of the heat generating layer is applied to the heat generating layer 20b. The entire surface is coated with a ring coat of fluorine-containing fluorine-containing resin (N, manufactured by Toyobo Co., Ltd.). By baking at 250° C. for 60 minutes, a protective layer 20e containing particles having the effect of preventing oxidation can be formed.

[0080] Particles that have the effect of preventing oxidation of the heat generating layer are not particularly limited, but examples thereof include particles that can capture oxygen. That is, it is preferable that the particles exhibit the effect of preventing oxidation of the heat generating layer by capturing oxygen. The manner in which oxygen is captured is not particularly limited, but for example, the particles themselves may be oxidized by oxygen, thereby capturing oxygen, or the particles may capture oxygen by adsorbing oxygen. Among these, it is preferable that the particles themselves are oxidized to exhibit the effect of preventing oxidation of the heat generating layer. The oxidation may be a one-stage reaction or a multi-stage reaction of two or more stages. In other words, the particles themselves may be oxidized, and then further oxidized to exhibit the effect of preventing oxidation of the heat generating layer.

[0081] The particles having the effect of preventing oxidation of the heat-generating layer preferably contain at least one element selected from the group consisting of Groups 3 to 16 of the IUPAC periodic table, and more preferably contain at least one element selected from the group consisting of Group 4 elements such as Ti, Zr, Hf, and Rf, Group 8 elements such as Fe, Ru, Os, and Hs, Group 10 elements such as Ni, Pd, Pt, and Ds, Group 11 elements such as Cu, Ag, Au, and Rg, and Group 12 elements such as Zn, Cd, Hg, and Cn. The form in which the particles contain the element is not particularly limited, but examples thereof include a simple substance of the element and an oxide containing the element.

[0082] The particles having the effect of preventing oxidation of the heat generating layer preferably contain at least one element selected from the group consisting of Ni, Ti, Fe, Cu, and Zn, more preferably Fe, and even more preferably at least one element selected from the group consisting of simple Fe, FeO, and Fe3O4.

[0083] The number average particle size of the particles that have the effect of preventing oxidation of the heat generating layer is preferably from 0.01 μm to 50 μm, more preferably from 0.1 μm to 30 μm, from the viewpoints of handling and dispersibility, and even more preferably from 0.2 μm to 10 μm, from the viewpoints of sustained prevention of oxidation of the heat generating layer and easier prevention of destruction of the protective layer due to local stress during use.

[0084] The shape of the particles that have the effect of preventing oxidation of the heat generating layer is not particularly limited, but examples thereof include spherical, pulverized, needle-like, plate-like, and whisker-like shapes. The content of particles in a layer containing particles that have the effect of preventing oxidation of the heat-generating layer is not particularly limited. For example, when the protective layer contains such particles, the proportion of the particles relative to the total content of the resin and the particles in the protective layer is preferably 0.1 to 20.0 area %, more preferably 0.5 to 15.0 area %. From the viewpoint of avoiding damage to the protective layer due to local stress during handling and use, a proportion of 0.8 to 10.0 area % is even more preferable. The proportion of particles can be adjusted by changing the proportion of resin and particles in the material forming the protective layer. When the base material contains the particles, the ratio of the particles to the total content of the resin and the resin in the base material can be set within the above range for the same reasons as above.

[0085] The material evaluation, number average particle size evaluation, and ratio calculation of the particles having the effect of preventing oxidation of the heat generating layer are performed using the sample used in the above-mentioned porosity evaluation. The material properties of particles having an anti-oxidation effect are evaluated as follows. In the area corresponding to the protective layer, a backscattered electron image of the SEM is acquired with a field of view of 12.8 μm × 9.6 μm. The conditions for acquiring the backscattered electron image are: acceleration voltage: 5.0 kV, working The scanning distance is set to 10 mm. An EDS (Energy Dispersive X-ray Spectroscopy) spectrum is acquired with the acceleration voltage changed to 10.0 kV. If the protective layer contains particles that prevent oxidation of the heat-generating layer, an SEM image can be acquired in which the particles that prevent oxidation of the heat-generating layer appear as islands floating in the sea due to differences in electron reflectivity. An electron beam is incident on the part of the particle that prevents oxidation of the heat-generating layer, which corresponds to the island, and the material is determined from the ratio of elements displayed on the SEM software.

[0086] The number average particle size of particles having the effect of preventing oxidation of the heat generating layer was evaluated as follows. A backscattered electron image of the protective layer is obtained by SEM with a field of view of 12.8 μm×9.6 μm under the following conditions: acceleration voltage: 5.0 kV, working distance: 4 mm. Next, the obtained image is subjected to a ternary processing using commercially available image software, so that the parts corresponding to the resin in the protective layer are colored gray, the particles that prevent oxidation of the heat-generating layer are colored white, and the rest of the image is colored black. Specifically, the backscattered electron image is read using ImageProPlus, an image analysis software manufactured by Media Cybernetics, and the brightness distribution of this image is determined. Next, by setting the brightness range of the obtained brightness distribution, a ternary processing is performed that distinguishes between the parts corresponding to the resin in the protective layer, the particles that prevent oxidation of the heat-generating layer, and the rest of the image.

[0087] This section explains how to calculate the number-average particle size of particles that have the effect of preventing oxidation of the heating layer from the ternary image of the cross section of the heating layer obtained in this way. Because digital image processing technology is applied to these images, it is assumed that all images are in a general digital image format with pixels arranged in a grid pattern. Furthermore, the ternary images are grayscale images containing only brightness information, and the images obtained by subsequently performing image processing on these images are all grayscale images in the same format unless otherwise noted.

[0088] First, calculate the circle-equivalent diameter of the particles that have the effect of preventing oxidation of the heat-generating layer. The circle-equivalent diameter of each particle refers to the diameter of a circle with the same area as the particle. Specifically, calculate the number of pixels that make up each crystal particle, and multiply this number of pixels by the area of ​​one pixel to calculate the actual area of ​​the crystal particle. In the SEM images used in this disclosure, the length of one side of one pixel corresponds to 0.01 μm, so the number of pixels constituting the particles that have the effect of preventing oxidation is 0.01 × 0.01 μm. 2 Furthermore, the diameter of a circle having this area is calculated to calculate the equivalent circle diameter. The total of the equivalent circle diameters of the particles thus obtained is divided by the total number of particles to calculate the number average particle size. The above procedure is repeated for six samples taken from the fixing rotor, and the number average particle size of each sample is calculated. The arithmetic mean of these six number average particle sizes is then calculated to determine the number average particle size of particles that have the effect of preventing oxidation of the heating layer. The six samples are taken in the same manner as for calculating the number average crystal particle size of silver crystals.

[0089] In a layer containing particles that have the effect of preventing oxidation of the heat generating layer, the ratio of the particles to the total content of the resin and the particles is calculated as follows. An image measuring 2.0 μm x 2.0 μm is cut out from the ternary image acquired to determine the number average particle size of the particles having the above-mentioned oxidation prevention effect. Four images are cut out from one SEM image. The image is cut out so that the center in the thickness direction of the heat generating layer is the center in the vertical direction of the cut out image. In addition, the four images are cut out so that the spacing between them is the same in the direction perpendicular to the thickness direction of the heat generating layer. Specifically, the images are cut out so that the spacing between adjacent images is 0.96 μm. The above operation is performed on six SEM images, and cross-sectional images at 24 locations are obtained.

[0090] The resin portion of the protective layer is displayed as a gray area, and the area it occupies in these images is calculated. Specifically, the number of pixels that make up the resin is calculated, and the sum of the number of pixels is calculated. The area of ​​one pixel, 0.01 x 0.01 μm, is then multiplied by the sum of the number of pixels. 2 By multiplying this by , the area occupied by the resin of the protective layer can be calculated. Similarly, particles that have the effect of preventing oxidation are displayed as white areas, and the area they occupy in the image is calculated. Specifically, the number of pixels that make up each particle is calculated, and the sum of the number of pixels is calculated. This sum is multiplied by the area of ​​one pixel, 0.01 x 0.01 μm. 2 By multiplying this by , the area occupied by particles that have the effect of preventing oxidation of the heat generating layer can be calculated. The proportion of particles having the effect of preventing oxidation of the heat generating layer is calculated as follows using the area occupied by the resin portion and the area occupied by the particles calculated above. Particle ratio = {area occupied by particles that have the effect of preventing oxidation of the heating layer (μm 2 )}÷{area occupied by particles that have the effect of preventing oxidation of the heat generating layer (μm 2 ) + area occupied by resin (μm 2 )}×100 The percentage of particles that have the effect of preventing oxidation of the heat-generating layer is calculated for 24 locations within a 2.0 μm x 2.0 μm area of ​​the cross-sectional image of the protective layer, and the average value obtained by arithmetic averaging is used as the percentage of particles that have the effect of preventing oxidation of the heat-generating layer.

[0091] The above-described measurement method was described for the case where the protective layer contains particles that have the effect of preventing oxidation of the heat-generating layer, but the measurement is also performed in the same way when the base material contains particles that have the effect of preventing oxidation of the heat-generating layer.

[0092] The thickness of the protective layer 20e is preferably 10 to 100 μm, and more preferably 20 to 60 μm. From the viewpoint of the flex resistance of the heat generating layer 20b, the thickness of the protective layer 20e is preferably adjusted so that the heat generating layer 20b is positioned on the neutral axis. The neutral axis can be calculated from the thickness and elastic modulus of the substrate 20a and the thickness and elastic modulus of the protective layer 20e. By positioning the heat generating layer 20b on the neutral axis, even when the heat generating layer 20b is repeatedly flexed, the stress applied to the heat generating layer 20b is balanced, thereby suppressing the occurrence of cracks in the heat generating layer 20b.

[0093] (6) Elastic layer The fixing rotor may have an elastic layer 20c on the outer peripheral surface of the protective layer 20e. The elastic layer 20c is a layer that imparts flexibility to the fixing rotor to ensure a fixing nip in the fixing device. When the fixing rotor is used as a heating member that comes into contact with toner on paper, the elastic layer 20c also functions as a layer that imparts flexibility to the surface of the heating member so that it can follow the unevenness of the paper. The elastic layer 20c includes, for example, rubber as a matrix and particles dispersed in the rubber. More specifically, the elastic layer 20c preferably includes rubber and a thermally conductive filler, and is preferably made of a cured product obtained by curing a composition including at least rubber raw materials (base polymer, crosslinking agent, etc.) and the thermally conductive filler. The thickness of the elastic layer is, for example, 100 to 1000 μm, or 200 to 500 μm.

[0094] From the viewpoint of realizing the above-mentioned functions of the elastic layer 20c, the elastic layer 20c is preferably made of a cured silicone rubber containing thermally conductive particles, and more preferably made of a cured addition-curing type silicone rubber composition. The silicone rubber composition may contain, for example, thermally conductive particles, a base polymer, a crosslinking agent, a catalyst, and, if necessary, additives. Because the silicone rubber composition is often liquid, the thermally conductive filler is easily dispersed therein, and the elasticity of the elastic layer 20c to be produced can be easily adjusted by adjusting the degree of crosslinking depending on the type and amount of the thermally conductive filler.

[0095] The matrix has a function of imparting elasticity to the elastic layer 20c. From the viewpoint of imparting the above-described function of the elastic layer 20c, the matrix preferably contains silicone rubber. Silicone rubber is preferable because it has high heat resistance and can maintain flexibility even in environments where temperatures reach as high as 240°C in the non-paper passing area. As the silicone rubber, for example, a cured product of an addition-curing liquid silicone rubber composition, which will be described later, can be used. The elastic layer 20c can be formed by applying and heating the liquid silicone rubber composition by a known method.

[0096] The liquid silicone rubber composition typically contains the following components (a) to (d): Component (a): organopolysiloxane having an unsaturated aliphatic group; Component (b): an organopolysiloxane having silicon-bonded active hydrogen; Component (c): catalyst; Component (d): Thermally conductive filler Each component will be described below.

[0097] Component (a) The organopolysiloxane having an unsaturated aliphatic group is an organopolysiloxane having an unsaturated aliphatic group such as a vinyl group, and examples thereof include those represented by the following formulas (1) and (2). [ka]

[0098] In formula (1), m 1 represents an integer of 0 or more (preferably 500 to 1100), and n 1 represents an integer of 3 or more (preferably 10 to 40). 1 each independently represents a monovalent unsubstituted or substituted hydrocarbon group that does not contain an unsaturated aliphatic group, provided that R 1 At least one of R represents a methyl group. 2 each independently represents an unsaturated aliphatic group. [ka]

[0099] In formula (2), n 2 represents a positive integer (preferably 500 to 1100), and R 3 each independently represents a monovalent unsubstituted or substituted hydrocarbon group that does not contain an unsaturated aliphatic group, provided that R 3 At least one of R represents a methyl group. 4 each independently represents an unsaturated aliphatic group.

[0100] In formulas (1) and (2), R 1 and R 3 Examples of the monovalent unsubstituted or substituted hydrocarbon group containing no unsaturated aliphatic group that can be represented by include the following groups: Unsubstituted hydrocarbon groups Alkyl groups (e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl). Aryl groups (for example, phenyl groups). Substituted hydrocarbon groups Substituted alkyl groups (e.g., chloromethyl, 3-chloropropyl, 3,3,3-trifluoromethyl) (fluoropropyl group, 3-cyanopropyl group, 3-methoxypropyl group).

[0101] The organopolysiloxanes represented by formulas (1) and (2) have at least one methyl group directly bonded to the silicon atom that forms the chain structure. 1 and R 3 Preferably, 50% or more of each group is a methyl group, and all of the R 1 and R 3 is more preferably a methyl group.

[0102] In addition, in formulas (1) and (2), R 2 and R 4 Examples of unsaturated aliphatic groups that can be represented by include the following groups. That is, examples of unsaturated aliphatic groups include vinyl groups, allyl groups, 3-butenyl groups, 4-pentenyl groups, and 5-hexenyl groups. Among these groups, R 2 and R 4 is preferably a vinyl group.

[0103] From the viewpoint of moldability, the viscosity of component (a) is 1000mm 2 / s or more 50000mm 2 / s or less is preferable, and 3000 mm 2 / s or more 20000mm 2 / s or less is more preferable. 2 / s or more, it is easy to adjust the hardness required for the elastic layer 20c, 2If the viscosity is less than 1 / s, the viscosity of the composition will not be too high, making it easy to apply. The viscosity (kinematic viscosity) can be measured using a capillary viscometer, a rotational viscometer, or the like, in accordance with JIS Z 8803:2011.

[0104] The blending amount of component (a) is preferably 55% by volume or more based on the liquid silicone rubber composition used to form the elastic layer 20c from the viewpoint of durability, and 65% by volume or less from the viewpoint of heat conductivity.

[0105] Ingredient (b) The organopolysiloxane having silicon-bonded active hydrogen atoms functions as a crosslinker that reacts with the unsaturated aliphatic groups of component (a) under the action of a catalyst to form a cured silicone rubber. Any organopolysiloxane having a Si-H bond can be used as component (b). In particular, from the viewpoint of reactivity with the unsaturated aliphatic group of component (a), those having an average of three or more hydrogen atoms bonded to silicon atoms per molecule are preferably used.

[0106] Specific examples of component (b) include the linear organopolysiloxane shown in formula (3) below and the cyclic organopolysiloxane shown in formula (4) below. [ka]

[0107] In formula (3), m 2 represents an integer of 0 or more (preferably 10 to 30), and n 3 represents an integer of 3 or more (preferably 5 to 20), and R 5 each independently represents a monovalent unsubstituted or substituted hydrocarbon group that does not contain an unsaturated aliphatic group. [ka]

[0108] In formula (4), m 3 represents an integer of 0 or more (preferably 10 to 30), and n4 represents an integer of 3 or more (preferably 5 to 20), and R 6 each independently represents a monovalent unsubstituted or substituted hydrocarbon group that does not contain an unsaturated aliphatic group.

[0109] R in formulas (3) and (4) 5 and R 6 Examples of the monovalent unsubstituted or substituted hydrocarbon group not containing an unsaturated aliphatic group that can be represented by R 1 Among these, R 5 and R 6 Preferably, 50% or more of each group is a methyl group, and all of the R 5 and R 6 is more preferably a methyl group. The content of component (b) is preferably 0.1 to 5.0 parts by mass, more preferably 0.2 to 3.0 parts by mass, per 100 parts by mass of component (a).

[0110] Ingredient (c) Examples of catalysts used in forming silicone rubber include hydrosilylation catalysts for accelerating the curing reaction. Known substances such as platinum compounds and rhodium compounds can be used as the hydrosilylation catalyst. The amount of catalyst used can be appropriately determined and is not particularly limited.

[0111] Ingredient (d) Examples of the thermally conductive filler include metals, metal compounds, and carbon fibers. Highly thermally conductive fillers are more preferred, and specific examples thereof include the following materials: Silicon metal (Si), silicon carbide (SiC), silicon nitride (Si3N4), boron nitride (BN), aluminum nitride (AlN), alumina (Al2O3), zinc oxide (ZnO), magnesium oxide (MgO), silica (SiO2), copper (Cu), aluminum (Al), silver (Ag), iron (Fe), nickel (Ni), vapor grown carbon fiber, PAN-based (polyacrylonitrile) carbon fiber, pitch-based carbon fiber.

[0112] These fillers can be used alone or in combination of two or more. From the viewpoint of handling and dispersibility, the average particle size of the filler is preferably from 1 μm to 50 μm, more preferably from 3 μm to 30 μm, where the average particle size refers to the volume average particle size. The filler may be spherical, pulverized, needle-like, plate-like, or whisker-like in shape. From the viewpoint of dispersibility, spherical fillers are particularly preferred. Furthermore, at least one filler selected from the group consisting of reinforcing fillers, heat-resistant fillers, and colored fillers may be added. The content of the filler in the elastic layer is preferably 20 to 80% by volume, and more preferably 30 to 60%, based on the elastic layer, from the viewpoint of hardness and thermal conductivity of the elastic layer.

[0113] (7) Adhesive layer The fixing rotor may have an adhesive layer 20f on the outer peripheral surface of the elastic layer 20c for adhering a surface layer 20d (described later). The adhesive layer 20f adheres the elastic layer 20c and the surface layer 20d. The adhesive used for the adhesive layer 20f is not particularly limited and can be appropriately selected from known adhesives. However, from the viewpoint of ease of handling, it is preferable to use an addition-curing type silicone rubber containing a self-adhesive component. This adhesive may contain, for example, a self-adhesive component, an organopolysiloxane having multiple unsaturated aliphatic groups, typically vinyl groups, in the molecular chain, a hydrogen organopolysiloxane, and a platinum compound as a crosslinking catalyst. The adhesive applied to the surface of the elastic layer 20c is cured by an addition reaction to form an adhesive layer 20f that bonds the surface layer 20d to the elastic layer 20c.

[0114] Examples of the self-adhesive component include the following: A silane having at least one, preferably two or more functional groups selected from the group consisting of an alkenyl group such as a vinyl group, a (meth)acryloxy group, a hydrosilyl group (SiH group), an epoxy group, an alkoxysilyl group, a carbonyl group, and a phenyl group. · Organosilicon compounds such as cyclic or linear siloxanes having 2 to 30 silicon atoms, preferably 4 to 20 silicon atoms. A non-silicon-based (i.e., silicon-free) organic compound that may contain oxygen atoms in the molecule, provided that it contains one to four, preferably one to two, aromatic rings such as monovalent to tetravalent, preferably divalent to tetravalent, phenylene structures per molecule, and at least one, preferably two to four, functional groups capable of participating in a hydrosilylation addition reaction (e.g., alkenyl group, (meth)acryloxy group) per molecule.

[0115] The above self-adhesive components may be used alone or in combination of two or more. Furthermore, in order to adjust viscosity and ensure heat resistance, a filler component may be added to the adhesive within the scope of the present disclosure. Examples of such filler components include the following: Silica, alumina, iron oxide, cerium oxide, cerium hydroxide, carbon black, etc.

[0116] The blending amounts of each component contained in the adhesive are not particularly limited and can be set as appropriate. Such addition-curing silicone rubber adhesives are commercially available and easily available. The thickness of the adhesive layer 20f is preferably 20 μm or less. By setting the thickness of the adhesive layer 20f to 20 μm or less, when the fixing belt according to this embodiment is used as a heating belt in a thermal fixing device, the thermal resistance can be easily set low and heat from the inner surface side can be efficiently transferred to a recording medium. The thickness of the adhesive layer 20f can be, for example, 1 to 20 μm, or 2 to 10 μm.

[0117] (8) Surface layer The fixing rotor may have a surface layer 20d. The surface layer 20d preferably contains a fluororesin to function as a release layer that prevents toner from adhering to the outer circumferential surface of the fixing rotor. The surface layer 20d may be formed, for example, by molding one of the resins listed below into a tube shape, or by coating the surface layer 20d with a resin dispersion. Tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), etc. Among the resin materials exemplified above, PFA is particularly suitable from the viewpoint of moldability and toner releasability.

[0118] The thickness of the surface layer 20d is preferably 10 μm to 50 μm, inclusive. By keeping the thickness of the surface layer 20d within this range, it is easy to maintain an appropriate surface hardness of the fixing rotor. [Example]

[0119] The present disclosure will be described in more detail below using examples, but the present disclosure is not limited to these examples.

[0120] [Example 1] A cylindrical stainless steel mold with an outer diameter of 30 mm was subjected to a release treatment, and a commercially available polyimide precursor solution (U Varnish S, manufactured by Ube Industries, Ltd.) was applied by immersion to form a coating film. The coating film was then dried at 140°C for 30 minutes to volatilize the solvent, followed by baking at 200°C for 30 minutes and 400°C for 30 minutes to imidize the film, forming a polyimide film substrate with a thickness of 40 μm and a length of 300 mm. Next, a ring-shaped pattern with a width of 600 μm and intervals of 200 μm was formed on the polyimide film using a dispenser with a silver nanoparticle-containing ink (DNS351S, manufactured by Daicel Corporation). After that, the film was baked at 300° C. for 30 minutes to form a heat generating layer 20b with a thickness of 2.5 μm.

[0121] Next, a solution prepared by dispersing 0.84 vol% of Fe3O4 (KN-320, Toda Kogyo Co., Ltd.) in PAI (polyamideimide, trade name: Viromax HR-16NN, manufactured by Toyobo Co., Ltd.) based on the solid content of the PAI solution was ring-coated onto the entire surface of the heat-generating layer 20b. This was then baked at 250°C for 60 minutes to form a 50 μm-thick protective layer 20e. Next, a primer (product name: DY39-051A / B, manufactured by Dow-Toray Industries, Inc.) was applied approximately uniformly to the outer surface of the protective layer 20e so that the dry weight was 40 mg, and after the solvent was dried, the primer was baked for 30 minutes in an electric furnace set to 160°C. A silicone rubber composition layer having a thickness of 250 μm was formed on this primer by ring coating, and was subjected to primary crosslinking at 160° C. for 1 minute, followed by secondary crosslinking at 200° C. for 30 minutes to form the elastic layer 20c.

[0122] The following silicone rubber compositions were used: As component (a), an organopolysiloxane having an alkenyl group, a vinylated polydimethylsiloxane having at least two vinyl groups per molecule (trade name: DMS-V41, manufactured by Gelest, number average molecular weight 68,000 (polystyrene equivalent), molar equivalent of vinyl group 0.04 mmol / g) was prepared. Furthermore, as component (b), an organopolysiloxane having Si-H groups, a methylhydrogenpolysiloxane (trade name: HMS-301, manufactured by Gelest, number average molecular weight 1300 (polystyrene equivalent), molar equivalent of Si-H groups 3.60 mmol / g) having at least two Si-H groups per molecule was prepared. 0.5 parts by mass of component (b) was added to 100 parts by mass of component (a) and thoroughly mixed to obtain an addition-curing silicone rubber stock solution. Furthermore, a catalytic amount of an addition curing reaction catalyst (platinum catalyst: platinum carbonylcyclovinylmethylsiloxane complex) and an inhibitor were added as component (c) and mixed thoroughly. High-purity spherical alumina (product name: Alnabeads CB-A10S, manufactured by Showa Titanium Co., Ltd.) was mixed as component (d), a thermally conductive filler, into this addition-cure silicone rubber stock solution at a volume ratio of 45% based on the elastic layer, and then kneaded to obtain an addition-cure silicone rubber composition with a JIS K 6253A durometer hardness of 10° after curing.

[0123] Next, an addition-curing silicone rubber adhesive (product name: SE1819CV A / B, manufactured by Dow-Toray Industries, Inc.) for forming adhesive layer 20f was applied uniformly to a thickness of approximately 20 μm onto the resulting elastic layer 20c. A fluororesin tube (product name: NSE, manufactured by Gunze Co., Ltd.) with an inner diameter of 29 mm and a thickness of 30 μm for forming surface layer 20d was laminated on top of this while expanding its diameter. Then, by evenly pressing the belt surface from above the fluororesin tube, excess adhesive is removed. The adhesive was squeezed out from between the elastic layer 20c and the fluororesin tube so that the thickness of the adhesive layer 20f was reduced to about 5 μm. Next, the adhesive was cured by heating at 200°C for 30 minutes, and the fluororesin tube was fixed onto the adhesive layer 20f. Finally, both ends were cut to a length of 240 mm, and a fixing rotor was obtained.

[0124] The heat generating layer in the obtained fixing rotor had a porous portion, and the number average crystal grain size of silver in the heat generating layer was 180 nm, and the porosity was 40 area %. The number average grain size of the particles contained in the protective layer, which had the effect of preventing oxidation of the heat generating layer, was 0.27 μm. The volume resistivity of the heat generating layer was 2.8 × 10 -8 The resistance was Ω·m.

[0125] [Example 2] A fixing rotor was produced in the same manner as in Example 1, except that the heat generating layer was formed at 250° C. for 30 minutes. The heat generating layer in the obtained fixing rotor had a porous portion, and the number average crystal grain size of silver in the heat generating layer was 160 nm, and the porosity was 25 area %. The number average grain size of the particles contained in the protective layer, which had the effect of preventing oxidation of the heat generating layer, was 0.27 μm. The volume resistivity of the heat generating layer was 4.7 × 10 -8 The resistance was Ω·m.

[0126] [Example 3] A fixing rotor was produced in the same manner as in Example 1, except that the heat generating layer was formed at 200° C. for 30 minutes. The heat generating layer in the obtained fixing rotor had a porous portion, and the number average crystal grain size of silver in the heat generating layer was 120 nm, and the porosity was 17 area %. The number average grain size of the particles contained in the protective layer, which had the effect of preventing oxidation of the heat generating layer, was 0.27 μm. The volume resistivity of the heat generating layer was 5.7 × 10 -8 The resistance was Ω·m.

[0127] [Example 4] A solution prepared by dispersing 0.84 vol% of FeO in PAI (Vylomax HR-16NN, manufactured by Toyobo Co., Ltd.) in a ratio of 0.84 vol% to the solid content of the PAI solution was applied to the entire surface of the heat generating layer 20b by ring coating. The FeO used was FEO16PB manufactured by Kojundo Chemical Laboratory Co., Ltd., which was ground in a mortar and then classified. Aside from that, a fixing rotor was prepared in the same manner as in Example 1. The heat generating layer in the obtained fixing rotor had a porous portion, and the number average crystal grain size of silver in the heat generating layer was 180 nm, and the porosity was 40 area %. The number average grain size of the particles contained in the protective layer, which had the effect of preventing oxidation of the heat generating layer, was 1.0 μm. The volume resistivity of the heat generating layer was 2.8 × 10 -8 The resistance was Ω·m.

[0128] [Example 5] The entire surface of the heat generating layer 20b was coated with a solution prepared by dispersing 0.52 vol% of Fe in PAI (Viromax HR-16NN, manufactured by Toyobo Co., Ltd.) with respect to the solid content of the PAI solution using a ring coat. The Fe used was FEE14PB manufactured by Kojundo Chemical Laboratory Co., Ltd., which was ground in a mortar and then classified. Otherwise, the fixing rotor was prepared in the same manner as in Example 1. The heat generating layer in the obtained fixing rotor had a porous portion, and the average crystal grain size of the silver in the heat generating layer was 180 nm, and the porosity was 40 area %. The number average grain size of the particles contained in the protective layer, which had the effect of preventing oxidation of the heat generating layer, was 1.0 μm. The volume resistivity of the heat generating layer was 2.8 × 10 -8 The resistance was Ω·m.

[0129] [Example 6] The entire surface of the heat generating layer 20b was ring-coated with a solution of PI (polyimide, product name: U Varnish S, manufactured by Ube Industries) in which 0.84 vol% of Fe3O4 (KN-320, manufactured by Toda Kogyo Co., Ltd.) was dispersed relative to the solid content of the PI solution. This coating was then dried at 140°C for 30 minutes. The coating was dried to volatilize the solvent in the coating, and then baked at 200°C for 30 minutes and 400°C for 30 minutes to imidize the coating, thereby forming a protective layer 20e with a thickness of 40 μm. Otherwise, the fixing rotor was produced in the same manner as in Example 1. The heat generating layer in the obtained fixing rotor had a porous portion, and the number average crystal grain size of silver in the heat generating layer was 200 nm, and the porosity was 45 area %. The number average grain size of the particles contained in the protective layer, which had the effect of preventing oxidation of the heat generating layer, was 0.27 μm. The volume resistivity of the heat generating layer was 2.8 × 10 -8 The resistance was Ω·m.

[0130] [Example 7] A cylindrical stainless steel mold with an outer diameter of 30 mm was treated with a release agent, and a solution of commercially available polyimide precursor solution (U Varnish S, manufactured by Ube Industries) containing 0.80 vol% FeO (KN-320, manufactured by Toda Kogyo Co., Ltd.) dispersed in the solution was applied by immersion to form a coating. The coating was then dried at 140°C for 30 minutes to volatilize the solvent, followed by baking at 200°C for 30 minutes and 400°C for 30 minutes to imidize the coating, forming a polyimide film substrate with a thickness of 40 μm and a length of 300 mm. The fixing rotor was otherwise prepared in the same manner as in Example 1. The heat generating layer in the obtained fixing rotor had a porous portion, and the number average crystal grain size of silver in the heat generating layer was 180 nm, and the porosity was 40 area %. The number average grain size of the particles contained in the protective layer, which had the effect of preventing oxidation of the heat generating layer, was 0.27 μm. The volume resistivity of the heat generating layer was 2.8 × 10 -8 The resistance was Ω·m.

[0131] [Example 8] A cylindrical stainless steel mold with an outer diameter of 30 mm was treated with a release agent, and a solution of commercially available polyimide precursor solution (U Varnish S, manufactured by Ube Industries, Ltd.) dispersed with 9.89 vol% CB (EC-300J, manufactured by Lion Corporation) based on the solid content of the PI solution was applied by immersion to form a coating. The coating was then dried at 140°C for 30 minutes to volatilize the solvent, followed by baking at 200°C for 30 minutes and 400°C for 30 minutes to imidize the coating, forming a polyimide film substrate with a thickness of 40 μm and a length of 300 mm. A fixing rotor was prepared in the same manner as in Example 1. The heat generating layer in the obtained fixing rotor had a porous portion, and the number average crystal grain size of silver in the heat generating layer was 180 nm, and the porosity was 40 area %. The number average grain size of the particles contained in the protective layer, which had the effect of preventing oxidation of the heat generating layer, was 0.27 μm. The volume resistivity of the heat generating layer was 2.8 × 10 -8 The resistance was Ω·m.

[0132] [Example 9] A fixing rotor was prepared in the same manner as in Example 1, except that a solution prepared by dispersing 15.7 vol% of Fe3O4 (KN-320, Toda Kogyo Co., Ltd.) in PAI (Viromax HR-16NN, manufactured by Toyobo Co., Ltd.) relative to the solid content of the PAI solution was ring-coated onto the entire surface of the heat-generating layer 20b. The heat generating layer in the obtained fixing rotor had a porous portion, and the number average crystal grain size of silver in the heat generating layer was 180 nm, and the porosity was 40 area %. The number average grain size of the particles contained in the protective layer, which had the effect of preventing oxidation of the heat generating layer, was 0.27 μm. The volume resistivity of the heat generating layer was 2.8 × 10 -8 The resistance was Ω·m.

[0133] [Comparative Example 1] A fixing rotor was produced in the same manner as in Example 1, except that the PAI solution applied to the entire surface of the heat generating layer 20b did not contain particles that have the effect of preventing oxidation of the heat generating layer. The heat generating layer had a porous portion, and the volume resistivity of the heat generating layer was 2.8 × 10 -8 The resistance was Ω·m.

[0134] Comparative Example 2 A fixing rotor was prepared in the same manner as in Example 2, except that the PAI solution applied to the entire surface of the heat generating layer 20b did not contain particles that have the effect of preventing oxidation of the heat generating layer. The heat generating layer had a porous portion, and the volume resistivity of the heat generating layer was 4.7 × 10 -8 The resistance was Ω·m.

[0135] Comparative Example 3 A fixing rotor was prepared in the same manner as in Example 3, except that the PAI solution applied to the entire surface of the heat generating layer 20b did not contain particles that have the effect of preventing oxidation of the heat generating layer. The heat generating layer had a porous portion, and the volume resistivity of the heat generating layer was 5.7 × 10 -8 The resistance was Ω·m.

[0136] (Evaluation: High temperature test) The fixing rotors obtained in Examples 1 to 9 and Comparative Examples 1 to 3 were cut in half as described below, and one half was stored at atmospheric pressure at 240°C for 60 hours. This storage temperature was set based on the expected overheating temperature in the non-paper passing area under a special usage environment (when small-sized paper is continuously printed) when the fixing rotor is actually incorporated into a fixing device and used.

[0137] (Evaluation: Resistance measurement) The resistance value was evaluated using a contact resistance measurement. The prepared fixing rotor was cut in half, with one half used for initial resistance evaluation and the other half used for evaluation after the high-temperature test as described above. When measuring the resistance, the resin layer was peeled off using a cutter and measurements were carried out using the four-terminal resistance measurement method. Details of the resistance measurement are described below. Resistance measurements were made using a Hioki 3541 resistance meter and two FormFactor FPC-GS-500 probes. The resistance meter was set to low power mode, and the probes were pressed against the heating layer so that the distance between each sense probe was 20 mm, and the resistance value was measured. The measured resistance value was converted to volume resistivity using the width and film thickness of the heating layer. The width and film thickness of the heating layer were measured using a scanning electron microscope. Similar measurements were carried out before and after the high-temperature test, and the value before the high-temperature test was taken as the initial value, and the rate of variation of the volume resistivity from the initial value was evaluated. A sample with a variation rate of volume resistivity exceeding 5% was rated B, and a sample with a variation rate of 5% or less was rated A. [Table 1] [Industrial Applicability]

[0138] As described above, the present disclosure makes it possible to obtain a fixing rotor that is excellent in durability even in a printing environment in which the fixing rotor is kept in a high temperature state for a long period of time.

[0139] The present disclosure includes the following configurations. [1] A fixing rotor, The fixing rotor is a substrate including a resin; a heat generating layer containing silver on the substrate; a protective layer containing a resin on a surface of the heat generating layer opposite to the surface facing the substrate, the heat generating layer extends in the circumferential direction of the outer peripheral surface of the base material, the heat generating layer is a layer having a porous portion, At least one of the base material and the protective layer contains particles that have the effect of preventing oxidation of the heat generating layer. [2] The fixing rotating member according to [1], wherein the protective layer contains at least one selected from the group consisting of polyimide and polyamideimide. [3] The fixing rotor according to [1] or [2], wherein the particles themselves are oxidized to exhibit an effect of preventing oxidation of the heat generating layer. [4] The fixing rotor according to any one of [1] to [3], wherein the particles contain at least one element selected from the group consisting of elements of Groups 3 to 16 of the IUPAC periodic table. [5] The fixing rotor according to any one of [1] to [4], wherein the particles contain at least one element selected from the group consisting of Ni, Ti, Fe, Cu, and Zn. [6] The fixing rotator according to any one of [1] to [5], wherein the particles contain at least one selected from the group consisting of simple Fe, FeO, and Fe3O4. [7] A fixing rotor according to any one of [1] to [6], wherein the proportion of voids in the cross section of the heat generating layer, measured by observing a cross section of the heat generating layer sampled from the fixing rotor and cut in the thickness direction, is 15 to 50 area %. [8] The fixing rotating member according to any one of [1] to [7], wherein the ratio of the particles to the total content of the resin and the particles in the layer containing the particles is 0.1 to 20.0 area %. [9] A fixing rotor according to any one of [1] to [8], a fixing device comprising: an induction heating device for generating heat from the fixing rotor by induction heating;

[10] An electrophotographic image forming apparatus, The electrophotographic image forming apparatus comprises: an image carrier that carries a toner image; a transfer device that transfers the toner image onto a recording material; a fixing device that fixes the transferred toner image onto the recording material; Equipped with [9] An electrophotographic image forming apparatus, wherein the fixing device is the fixing device according to [9]. [Explanation of symbols]

[0140] 1 printer, 15 fixing device, 20 fixing rotor, 20a substrate, 20b heat generating layer, 20c elastic layer, 20d surface layer, 20e protective layer, 20f adhesive layer, 21 pressure roller

Claims

1. A fixing rotor, The fixing rotor is a substrate including a resin; a heat generating layer containing silver on the substrate; a protective layer containing a resin on a surface of the heat generating layer opposite to the surface facing the substrate, the heat generating layer extends in the circumferential direction of the outer peripheral surface of the base material, the heat generating layer is a layer having a porous portion, At least one of the base material and the protective layer contains particles that have the effect of preventing oxidation of the heat generating layer.

2. The fixing rotating member according to claim 1 , wherein the protective layer includes at least one selected from the group consisting of polyimide and polyamideimide.

3. 2. The fixing rotator according to claim 1, wherein the particles themselves are oxidized, thereby exerting an effect of preventing oxidation of the heat generating layer.

4. 2. The fixing rotor according to claim 1, wherein the particles contain at least one element selected from the group consisting of elements of Groups 3 to 16 on the IUPAC periodic table.

5. 2. The fixing rotor according to claim 1, wherein the particles contain at least one element selected from the group consisting of Ni, Ti, Fe, Cu, and Zn elements.

6. The particles are composed of elemental Fe, FeO and Fe ３ O ４ The fixing rotating member according to claim 1 , comprising at least one selected from the group consisting of:

7. 2. The fixing rotor according to claim 1, wherein the ratio of pores in a cross section of the heat generating layer, measured by observing a cross section of the heat generating layer sampled from the fixing rotor and cut in the thickness direction, is 15 to 50 area %.

8. 2. The fixing rotating member according to claim 1, wherein the ratio of the particles to the total content of the resin and the particles in the particle-containing layer is 0.1 to 20.0 area %.

9. The fixing rotating body according to any one of claims 1 to 8, a fixing device comprising: an induction heating device for generating heat from the fixing rotor by induction heating;

10. An electrophotographic image forming apparatus, The electrophotographic image forming apparatus comprises: an image carrier that carries a toner image; a transfer device that transfers the toner image onto a recording material; a fixing device that fixes the transferred toner image onto the recording material; Equipped with 10. An electrophotographic image forming apparatus, wherein the fixing device is the fixing device according to claim 9.

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