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

Abstract

To provide a fixing rotating body that offers excellent durability even in printing environments where high temperatures persist for extended periods. [Solution] A fixing rotating body comprising a resin-containing substrate, a heating layer on the substrate, and a resin layer on the side of the heating layer opposite to the side facing the substrate, wherein the heating layer contains silver particles and particles of metal A having a greater ionization tendency than silver between the silver particles.

Description

[Technical Field]

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

[0002] In electrophotographic image forming devices such as electrophotographic copiers and printers, the fixing device typically consists of a nip section formed by a heated fixing rotating body and a pressure roller in contact with it. The recording material carrying the unfixed toner image is transported and heated in this section to fix the toner image to the recording material.

[0003] A fixing device using electromagnetic induction heating has been developed and put into practical use. This device has a heating layer on the fixing rotating body, and this heating layer can be directly heated. Electromagnetic induction heating fixing devices have the advantage of a short warm-up time.

[0004] The heating layer is required to have conductivity and durability against repeated strain. For example, Patent Document 1 discloses a fixing member that forms a resin protective layer on top of a heating layer with a predetermined pattern formed of copper plating.

[0005] Patent documents 2, 3, and 4 disclose paints containing silver nanoparticles. These documents disclose a fixing member in which the paint containing silver nanoparticles is formed on a heating layer in a predetermined pattern, and fired (sintered) at a high temperature of about 300°C, causing the silver nanoparticles to coalesce, and further, the pores to coalesce as well, resulting in a fine-grained structure that is connected in both the circumferential and axial directions. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2021-004977 [Patent Document 2] Japanese Patent Publication No. 2024-063529 [Patent Document 3] Japanese Patent Publication No. 2024-063754 [Patent Document 4] Japanese Patent Publication No. 2024-063761 [Overview of the project] [Problems that the invention aims to solve]

[0007] The fixing rotating body ensures that the toner is properly fixed in the paper-feed section as the paper passes through. In the paper-feed section, the paper absorbs heat as it passes through. Therefore, continuous heating is necessary to maintain the fixing temperature.

[0008] On the other hand, in the non-paper-passing end of the fixing rotating body, the so-called non-paper-passing section, the temperature of the fixing material rises. In the non-paper-passing section, there is no heat exchange due to paper passage, so the temperature can rise higher than the fixing temperature, sometimes reaching nearly 240°C.

[0009] In particular, under special usage conditions such as continuous printing of small-sized paper, this phenomenon of prolonged high temperatures in the non-paper-feeding area is more likely to occur. Therefore, the present disclosure aims to provide a fixing rotating body that has excellent durability even in printing environments where high temperatures persist for extended periods. [Means for solving the problem]

[0010] This disclosure aims to provide a fixing rotating body that is highly durable even in printing environments where high temperatures persist for extended periods. This disclosure is also intended for fixing apparatuses and electrophotographic image forming apparatuses equipped with a fixing rotating body. [Effects of the Invention]

[0011] This disclosure provides a fixing rotating body that is highly durable even in printing environments where high temperatures persist for extended periods. Furthermore, this disclosure provides a fixing apparatus and an electrophotographic image forming apparatus equipped with the fixing rotating body. Finally, this disclosure provides a conductive member that suppresses resistance increases at high temperatures. [Brief explanation of the drawing]

[0012] [Figure 1] Cross-sectional view of the heat-generating layer with pores according to the present disclosure [Figure 2] Schematic diagram of an electrophotographic image forming apparatus according to an embodiment [Figure 3] Schematic diagram showing the cross-sectional configuration of a fixing device according to an embodiment [Figure 4] Schematic diagram showing the cross-sectional configuration of a fixing device according to an embodiment [Figure 5] Schematic diagram of the magnetic core and exciting coil of a fixing device according to an embodiment [Figure 6] Diagram showing the magnetic field formed when a current is passed through an exciting coil according to an embodiment [Figure 7] Cross-sectional configuration diagram of a rotating body for fixing according to an embodiment [Figure 8] Cross-sectional view (FIG. 8(a)) and binarized view (FIG. 8(b)) of the heat-generating layer of a rotating body for fixing according to an embodiment

Embodiments for Carrying Out the Invention

[0013] The present inventor attempted to apply silver nanoink capable of controlling fine line widths and spaces when forming the heat-generating layer, expecting an effect of reducing heat generation unevenness. The heat-generating layer formed of silver nanoink can form a thin layer, which is advantageous for bend resistance. Also, since pores on the order of sub-microns exist, there is an effect of improving adhesion due to the anchor effect when forming the protective layer, and there is also an effect of improving durability.

[0014] In this case, when silver nanoink is used for the heat-generating layer of the rotating body for fixing, it was also confirmed that a high-temperature state above the set value continues for a long time in the non-paper-passing portion, and the resistance of the heat-generating layer increases. This is presumably mainly because the heat-generating layer formed of silver nanoink is a polycrystal at the sub-micron level and has sub-micron pores, so the surface area of the crystal interface is large and oxidation is likely to occur. In particular, oxidation is thought to be promoted in a high-temperature environment of about 240°C.

[0015] Therefore, considering the relationship between metals and oxidation, we hypothesized that the corrosion reaction of metals was involved, and focused our investigation on the ionization tendency of metal elements. The electrochemical series, arranged in order of the likelihood of chemical reactions occurring, is as follows: Ionization series: Li>K>Ca>Na>Mg>AL>Zn>Fe>Ni >Sn>Pb>H2>Cu>Hg>Ag>Pt>Au Li (lithium) has the highest ionization tendency, while Au (gold) has the lowest ionization tendency.

[0016] In other words, gold (Au) is the least likely to ionize and therefore the least likely to react. This means that gold is the least likely to oxidize. In the electrochemical series, the further to the left you go, the stronger the ionization tendency, meaning that elements are more likely to become positive ions. In this study, we hypothesized that by mixing silver with metal A, which has a higher ionization tendency than silver, metal A would capture oxygen before the silver could oxidize, thus preventing the oxidation of silver.

[0017] When small-sized paper is continuously fixed in a fixing device, resistance increases in the non-paper-feeding section, and the amount of heat generated by electromagnetic induction becomes uneven. If large-sized paper is then fixed in a fixing device where the non-paper-feeding section has increased resistance and uneven heat generation, the fixing performance at the edges of the paper will decrease, resulting in image distortion. Based on the above, the following explanation will be provided.

[0018] The fixing rotating body having a heating layer according to this disclosure, and the fixing apparatus and image forming apparatus equipped with said fixing rotating body will be described in detail below based on their specific configurations.

[0019] Considering oxidation by focusing on the ionization tendency of metal elements specific to each metal and taking into account the electrochemical series which is arranged in order of the likelihood of chemical reactions, the substances that react more readily than silver are Hg (mercury), Cu (copper), Pb (lead), Sn (tin), Ni (nickel), Fe (iron), Zn (zinc), aluminum (Al), Mg (magnesium), Na (sodium), Ca (calcium), K (potassium), and Li (lithium).

[0020] The oxidation of silver is suppressed by the presence of metal A, which has a higher ionization tendency than silver, at the silver crystal interface. From the viewpoint of ionization tendency, stability, and safety, Al (aluminum), Ni (nickel), Fe (iron), and Cu (copper) are preferred as metal A. From the standpoint of conductivity, Cu (copper) is more preferable.

[0021] Figure 1 is a cross-sectional view of the heating layer relating to this disclosure. In the cross-section of the heating layer 20b, there is silver 221 shown in the white region, copper 222 shown in the gray region, and vacancies 223 shown in the black region. The silver 221 is an aggregate of multiple polycrystalline bodies, within which copper 222 is arranged as granular material. Furthermore, the copper 222 is arranged so as to be in contact with the interface of the silver 221. There are also vacancies 223 on the order of submicrons.

[0022] (Electrophotographic image forming apparatus) The electrophotographic image forming apparatus of this disclosure comprises the fixing apparatus of this disclosure. An electrophotographic image forming apparatus (hereinafter also simply referred to as "image forming apparatus") comprises an image carrier that holds 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.

[0023] Figure 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 (fixing device of this disclosure) according to an embodiment. A cassette 2 is retractably housed in the lower part of the printer 1. The cassette 2 stores sheets P as recording material. The sheets P in the cassette 2 are separated one by one by a separation roller 3 and fed to a registration roller 4.

[0024] Furthermore, a wide variety of sheets of different sizes and materials can be used as the recording material, sheet P, including ordinary paper and cardboard, plastic film, cloth, sheet materials with surface treatments such as coated paper, and specially shaped sheet materials such as envelopes and index paper.

[0025] Printer 1 includes an image forming unit 5, which is an image forming means in which image forming stations 5Y, 5M, 5C, and 5K corresponding to yellow, magenta, cyan, and black are arranged in a row. Image forming station 5Y is equipped with a photosensitive drum 6Y, which is an image carrier (electrophotographic photoreceptor) that holds a toner image, and is provided with a charging roller 7Y as a charging means to uniformly charge the surface of the photosensitive drum 6Y.

[0026] Furthermore, a scanner unit 8 is provided below the image forming unit 5. The scanner unit 8 irradiates a laser beam that is on / off modulated in response to a digital image signal input from an external device such as a computer (not shown) and generated by an image processing means, based on image information, to form an electrostatic latent image on the photosensitive drum 6Y. Furthermore, the image forming station 5Y includes a developing roller 9Y as a developing means for depositing toner onto the electrostatic latent image on the photosensitive drum 6Y and developing it as a toner image, and a primary transfer unit 11Y for transferring the toner image on the photosensitive drum 6Y to an intermediate transfer belt 10.

[0027] The toner image on the intermediate transfer belt 10, onto which the toner image has been transferred in the primary transfer unit 11Y, is then subjected to multiple transfers of toner images formed in a similar process at other image forming stations 5M, 5C, and 5K. This forms a full-color toner image on the intermediate transfer belt 10. This full-color toner image is then transferred to the sheet P by the secondary transfer unit 12, which acts as a transfer means. The primary transfer unit 11Y and the secondary transfer unit 12 are examples of transfer devices that fix the transferred toner image onto a recording material.

[0028] Subsequently, the toner image transferred onto the sheet P (recording material) passes through the fixing device 15 and is fixed as a fixed image. Furthermore, the sheet P passes through the discharge and transport unit 13 and is discharged and loaded into the loading unit 14. Note that the image forming unit 5 described above is just one example of an image forming means, and for example, a direct transfer method in which the toner image is directly transferred from the image carrier to the sheet P, or a monochrome method using only one color of toner may also be used.

[0029] (Fusing device) The fixing device of this disclosure comprises the fixing rotating body of this disclosure. The fixing device 15 of this embodiment is an induction heating type fixing device (image heating device) that generates heat for the fixing rotating body by electromagnetic induction. Figure 3 shows the cross-sectional configuration of the fixing device 15, and Figure 4 is a perspective view of the fixing device 15. Note that the housing and other parts of the fixing device 15 are omitted in Figures 3 and 4. In the following description, with respect to the members constituting the fixing device 15, the longitudinal direction X1 is the direction perpendicular to the transport direction of the recording material and the thickness direction of the recording material.

[0030] The fixing device 15 comprises a fixing rotating body 20, a film guide 25, a pressure roller 21, a pressure stay 22, a magnetic core 26, an excitation coil 27 (Figure 5), a thermistor 40, and a current sensor 30. The fixing device 15 heats the recording material on which the image has been formed and fixes the image to the recording material. The fixing rotating body 20 is the fixing rotating body of this disclosure, and the pressure roller 21 is the opposing member of this embodiment. The excitation coil 27 functions as a magnetic field generating means of this embodiment. Details of the fixing rotating body will be described later.

[0031] The fixing rotating body 20 has a heating layer 20b on a base material 20a. The heating layer 20b generates heat due to induced current. The heating layer 20b is formed as a heating pattern arranged in the longitudinal direction, with heating rings 201 (Figure 4) each electrically connected in the circumferential direction and electrically divided in the longitudinal direction X1 (the direction of rotation axis of the fixing rotating body 20).

[0032] In other words, the heating layer 20b is divided into multiple annular regions, each connected in the circumferential direction of the fixing rotating body 20, and these annular regions are not electrically connected to each other in the direction of the rotation axis of the fixing rotating body 20. Each heating ring 201, which is a component of the heating pattern, is formed with a substantially uniform width in the longitudinal direction X1.

[0033] In other words, the fixing rotating body of the present disclosure preferably has a heating layer which consists of a plurality of segments (e.g., heating rings) arranged in the longitudinal direction of the fixing rotating body and electrically isolated from one another, and each of the plurality of segments is formed continuously over the entire circumferential area of ​​the fixing rotating body.

[0034] The pressure roller 21, which serves as a counter body (pressure member) facing the fixing rotating body 20, comprises a core metal 21a and an elastic layer 21b that is molded and coated in a roller shape concentrically around the core metal, with a release layer 21c provided on the surface. The elastic layer 21b is preferably made of a material with good heat resistance, such as silicone rubber, fluororubber, or fluorosilicone rubber. The longitudinal ends of the core metal 21a are arranged to be freely rotatable between the chassis side sheet metal (not shown) of the device via conductive bearings.

[0035] Furthermore, as shown in Figure 4, by compressing the pressure springs 24a and 24b between the longitudinal ends of the pressure stay 22 and the spring receiving members 23a and 23b on the device chassis side, a downward force is applied to the pressure stay 22.

[0036] In this embodiment, the fixing device 15 applies a total pressure of approximately 100N to 300N (approximately 10kgf to approximately 30kgf). As a result, the lower surface of the film guide 25, which is made of heat-resistant resin PPS or the like, and the upper surface of the pressure roller 21 press against each other, sandwiching the fixing rotating body 20, which is a cylindrical rotating body, to form a fixing nip portion N of a predetermined width.

[0037] The film guide 25, together with the pressure roller 21, functions as a nip-forming member that forms a nip section for gripping and transporting the recording material carrying the toner image via the fixing rotating body 20. Here, PPS is polyphenylene sulfide.

[0038] The pressure roller 21 is driven to rotate clockwise by a driving means (not shown), and a counterclockwise rotational force acts on the fixing rotating body 20 due to the frictional force with the outer surface of the fixing rotating body 20. As a result, the fixing rotating body 20 rotates while sliding against the film guide 25.

[0039] Figure 5 is a schematic diagram of the magnetic core 26 and excitation coil 27 in Figure 3, with the fixing rotating body 20 shown by a dashed line to illustrate its positional relationship with the fixing rotating body 20. In an induction heating type fixing device that generates heat for the fixing rotating body 20 by electromagnetic induction, the induction heating device may include the magnetic core 26 and the excitation coil 27.

[0040] The excitation coil 27 is located inside the fixing rotating body 20. The excitation coil 27 has a helical portion in which the helical axis is approximately parallel to the direction along the rotation axis of the fixing rotating body 20, and forms an alternating magnetic field that causes the heating layer 20b to generate heat through electromagnetic induction. Approximately parallel means not that the two axes are perfectly parallel, but that a slight misalignment is allowed to the extent that the heating layer can generate heat through electromagnetic induction.

[0041] The magnetic core 26 is positioned within the helical section and extends in the direction of the rotation axis of the fixing rotating body 20, without forming a loop outside the fixing rotating body 20. The magnetic core 26 induces magnetic field lines of the alternating magnetic field.

[0042] In Figure 5, the magnetic core 26 is inserted through the hollow portion of the fixing rotating body 20, which is a cylindrical rotating body. The excitation coil 27 is wound helically around the outer circumference of the magnetic core 26 and extends in the longitudinal direction of the fixing rotating body 20. The magnetic core 26 is cylindrical in shape and is fixed by fixing means (not shown) so as to be located approximately in the center of the fixing rotating body 20 in a cross-section viewed in the longitudinal direction (see Figure 3).

[0043] The magnetic core 26, located inside the excitation coil 27, guides the magnetic field lines (magnetic flux) of the alternating magnetic field generated by the excitation coil 27 inward from the heating layer 20b of the fixing rotating body 20, forming a path for the magnetic field lines (magnetic path). The material of the magnetic core 26 is preferably a soft magnetic material with high magnetic permeability, selected from the group consisting of materials with low hysteresis loss and high relative permeability, such as sintered ferrite and ferrite resin.

[0044] The cross-sectional shape of the magnetic core 26 does not need to be circular, as long as it can be housed in the hollow part of the fixing rotating body 20. However, a shape that maximizes the cross-sectional area is preferable. In this embodiment, the diameter of the magnetic core 26 is 10 mm and its length in the longitudinal direction is 280 mm.

[0045] The excitation coil 27 is formed by winding a 1-2 mm diameter copper wire (single conductor) coated with heat-resistant polyamide-imide spirally around a magnetic core 26 20 times. The excitation coil 27 is wound around the magnetic core 26 in a direction intersecting the rotation axis direction of the fixing rotating body 20. Therefore, when a high-frequency alternating current is passed through this excitation coil 27, an alternating magnetic field is generated in a direction parallel to the rotation axis direction, and an induced current (circumferential current) flows through each heating ring 201 of the heating layer 20b of the fixing rotating body 20 according to the principle described later, causing heat generation.

[0046] As shown in Figures 3 and 4, the thermistor 40, which serves as a temperature sensing means for detecting the temperature of the fixing rotating body 20, is composed of a spring plate 40a and a thermistor element 40b. The spring plate 40a is a spring-elastic support member that extends toward the inner surface of the fixing rotating body 20. The thermistor element 40b, which serves as the temperature sensing element, is installed at the tip of the spring plate 40a. The surface of the thermistor element 40b is covered with a 50 μm thick polyimide tape to ensure electrical insulation.

[0047] The thermistor 40 is fixed to the film guide 25 at approximately the center of the fixing rotating body 20 in the longitudinal direction. The thermistor element 40b is pressed against the inner surface of the fixing rotating body 20 by the spring elasticity of the spring plate 40a and held in contact. The thermistor 40 may also be positioned on the outer circumference of the fixing rotating body 20.

[0048] The current sensor 30, which constitutes a continuity monitoring device that monitors the circumferential continuity of the heat-generating layer 20b, is positioned at the same location as the thermistor 40 in the longitudinal direction of the fixing device 15. In other words, the current sensor 30 monitors 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 rotating body 20. The current sensor 30 consists of an outer magnetic core 30a, an inner magnetic core 30b, and a detection coil 30c.

[0049] (Heating principle) The heating principle of the fixing rotating body 20 in the induction heating fixing device 15 will be explained. Figure 6 is a conceptual diagram showing the moment when the current in the excitation coil 27 is increasing in the direction of the arrow I0. The excitation coil 27 is inserted into the fixing rotating body 20 and functions as a magnetic field generating means that generates an alternating magnetic field in the direction of the rotation axis of the fixing rotating body 20 by passing an alternating current through it, thereby generating an induced current I in the circumferential direction of the fixing rotating body 20.

[0050] Furthermore, the magnetic core 26 functions as a component that guides the magnetic field lines B (solid lines in Figure 6) generated by the excitation coil 27 and forms a magnetic path. In general induction heating methods, magnetic field lines penetrate the heating layer and generate eddy currents, whereas in this embodiment, the magnetic field lines B are configured to loop on the outside of the fixing rotating body. That is, the heating layer 20b is mainly heated by the induced current induced by magnetic field lines that emerge from one longitudinal end of the magnetic core 26, pass outside the heating layer 20b, and return to the other longitudinal end of the magnetic core 26. This allows for efficient heating even if the thickness of the heating layer is as thin as 5 μm or less.

[0051] When an alternating magnetic field is formed by the excitation coil 27, an induced current I flows through each heating ring 201 of the heating layer 20b of the fixing rotating body 20, according to Faraday's law. Faraday's law states that "when the magnetic field in a circuit is changed, an induced electromotive force is generated that attempts to drive an electric current through the circuit, and this induced electromotive force is proportional to the time change of the magnetic flux perpendicular to the circuit."

[0052] Consider the induced current I flowing through the heating ring 201c, located in the central part of the longitudinal direction of the magnetic core 26 shown in Figure 6, when a high-frequency alternating current is passed through the excitation coil 27. When a high-frequency alternating current is passed through, an alternating magnetic field is formed inside the magnetic core 26. The induced electromotive force acting on the heating ring 201c at that time is proportional to the time change of the magnetic flux that vertically penetrates the inside of the heating ring 201c, according to the following equation 1.

number

[0053] This induced electromotive force V causes an induced current I, which is a circulating current around the heating ring 201c, to flow, and the Joule heat generated by the induced current I causes the heating ring 201c to heat up. However, if the heating ring 201c is broken, the induced current I does not flow, and the heating ring 201c does not heat up.

[0054] (1) Outline of the configuration of the fixing rotating body The fixing rotating body of this disclosure is A substrate containing resin, A heating layer is placed on the substrate, A resin layer is placed on the side of the heating layer opposite to the side facing the substrate. Equipped with, The heating layer is characterized by containing silver particles and particles of metal A, which has a greater ionization tendency than silver, between the silver particles. The details of the fixing rotating body of this embodiment will be described below with reference to the drawings. The fixing rotating body according to one aspect of the present disclosure may be a rotatable member such as an endless belt. The fixing rotating body comprises a resin-containing substrate, a heating layer on the substrate, and a resin layer on the surface of the heating layer opposite to the side facing the substrate.

[0055] Figure 7 is a circumferential cross-sectional view of the fixing rotating body. As shown in Figure 7, the fixing rotating body has a base material 20a, a heating layer 20b on the outer surface of the base material 20a, and a resin layer (protective layer) 20e on the outer surface of the heating layer. The resin layer includes, for example, a protective layer. The resin layer may also have an elastic layer 20c or a surface layer (release layer) 20d on the protective layer 20e as needed, and an adhesive layer 20f may be provided between the elastic layer 20c and the surface layer 20d.

[0056] (2) Base material The fixing rotating body of this disclosure comprises a base material containing resin. The material of the base material 20a is not particularly limited. The base material 20a contains resin (preferably heat-resistant resin). When the belt is used in an electromagnetic induction fixing device, it is preferable that the base material 20a is a layer that maintains high strength and shows little change in physical properties when the heating layer is heated. For this reason, it is preferable that the base material 20a contains a heat-resistant resin as its main component, and more preferably that it is composed of a heat-resistant resin. Fillers may be blended into the base material 20a to improve heat insulation and strength.

[0057] The shape of the base can be appropriately selected according to the shape of the fixing rotating body, and can be various shapes such as an endless belt shape, a hollow cylindrical shape, or a film shape. In the case of a fixing belt, the thickness of the base material 20a is preferably 10 to 100 μm, and more preferably 20 to 60 μm. By keeping the thickness of the base material 20a within the above range, a high level of both strength and flexibility can be achieved.

[0058] Furthermore, on the surface of the base material 20a opposite to the side facing the heat-generating layer 20b, a layer may be provided, for example, to prevent wear of the inner surface of the fixing belt when the inner surface of the fixing belt comes into contact with other components, or to improve sliding properties with other components.

[0059] Other components, such as sliding members, are arranged on the inner surface of the base material 20a, resulting in a large sliding load. Therefore, in order to ensure the durability of the base material, it is preferable that the base material be a solid layer. Furthermore, the outer surface of the substrate 20a may be subjected to surface roughening treatments such as blasting, or modification treatments such as ultraviolet light, plasma, or chemical etching, in order to improve adhesion and wettability with the heat-generating layer 20b.

[0060] (3) Heating layer The fixing rotating body of this disclosure comprises a heating layer on a substrate. The heating layer 20b is a layer that generates heat when energized. In the heating principle by induction heating using an excitation coil, when an alternating current is supplied to an excitation coil placed near the fixing rotating body, a magnetic field is induced, and this magnetic field generates a current in the heating layer 20b of the fixing rotating body, causing it to heat up by Joule heating. The heating layer extends in the circumferential direction on the outer surface of the substrate.

[0061] A paint containing silver nanoparticles is formed on a heating layer in a predetermined pattern and fired (sintered) at a high temperature of about 300°C. The silver nanoparticles coalesce, and further, the pores coalesce, resulting in a fine-grained structure of the fixing member that is connected in both the circumferential and axial directions. However, if the non-paper-passing portion of the heating layer of the fixing member remains at a high temperature above the fixing temperature for an extended period, the resistance of the heating layer increases, and uneven heating occurs.

[0062] The fixing rotating body of this disclosure has a heating layer containing silver particles and particles of metal A, which has a higher ionization tendency than silver, between the silver particles. It is believed that by mixing silver with metal A, which has a higher ionization tendency than silver, the metal A with the higher ionization tendency can capture oxygen before the silver oxidizes and its resistance increases, thereby preventing the oxidation of silver.

[0063] This would prevent temperature and resistance increases in the non-paper-feeding section when small-sized paper is continuously fixed in the fixing device. Furthermore, it was thought that unevenness would occur in the amount of heat generated due to electromagnetic induction. When fixing a large-sized sheet of paper to a fixing device where the non-paper-feeding section experiences increased resistance and uneven heat generation, this method also prevents the reduction in fixing performance at the edges of the paper and the resulting image distortion.

[0064] The silver in the heating layer has low volume resistivity and is resistant to oxidation. The silver content relative to the entire heating layer 20b is preferably 90.0% by mass or more, and more preferably 99.0% by mass or more. Furthermore, in the fixing rotating body of this disclosure, the content of metal A in the heating layer is preferably 0.3% by mass or more and 1.0% by mass or less.

[0065] This is calculated based on the results obtained from preliminary studies. First, to confirm the increase in resistance, two heating layers made using the same method were prepared and simultaneously heated in a standard oven at a constant temperature for a set time. After that, one heating layer was continued to be heated in the standard oven at a constant temperature. The other heating layer was heated in a heating oven with nitrogen purging to remove oxygen, in order to investigate the effect of oxidation by oxygen, and the change in resistance increase was observed.

[0066] Two heating layers were heated in a standard oven at 240°C for 140 hours, and the resistance of each layer was measured to determine the resistance increase rate. Then, one layer was removed and placed in a nitrogen-purging oven, where oxygen was removed under a nitrogen atmosphere. After heating at 240°C for 200 hours under a nitrogen atmosphere, the heating layer was removed, its resistance was measured, and the resistance increase rate was determined.

[0067] The first sheet was then heated in nitrogen at 240°C for 250 hours. After heating, the resistance was measured and the resistance increase rate was determined. The remaining sheet was then heated in a regular oven under normal air conditions at 240°C for 200 hours. After heating, the resistance was measured and the resistance increase rate was determined.

[0068] The heating layer set in the nitrogen-purged oven showed no change in heating resistance compared to when it was first placed in the nitrogen-purged oven. From 140 hours to 200 hours and then to 250 hours, the resistance remained almost constant, and the rate of resistance increase became constant.

[0069] Furthermore, the heating layer, which was heated in a standard oven at 240°C for 200 hours, maintained the same rate of resistance increase from 0 to 140 hours and continued to increase in resistance up to 200 hours. Based on this, and considering that the resistance increase rate stabilized at a constant value when switched to a nitrogen atmosphere, we concluded that the cause was likely the oxidation of silver. In other words, I thought that the silver wiring would oxidize and increase its resistance.

[0070] Therefore, we re-examined oxidation by focusing on the ionization tendency of metal elements, which is unique to metals. The electrochemical series, arranged in order of the likelihood of chemical reactions occurring, is as follows: Ionization series: Li>K>Ca>Na>Mg>AL>Zn>Fe>Ni >Sn>Pb>H2>Cu>Hg>Ag>Pt>Au

[0071] Li (lithium) has the highest ionization tendency, and Au (gold) has the lowest ionization tendency. In other words, Au (gold) is the least likely to become an ion and is the least likely to react. Furthermore, Au (gold) is the least likely to oxidize. In the electrochemical series, the further to the left you go, the higher the ionization tendency, meaning that elements are more likely to become positive ions.

[0072] In this study, oxidation is expected to be suppressed by the presence of metal A, which has a higher ionization tendency than silver, at the silver crystal interface. Therefore, for metal A, Al (aluminum), Ni (nickel), Fe (iron), and Cu (copper) are preferred from the viewpoint of ionization tendency, stability, and safety. Furthermore, Cu (copper) is considered more preferable from the viewpoint of conductivity, and this was investigated. Therefore, it was hypothesized that by mixing silver with metal A, which has a higher ionization tendency than silver, metal A, with its higher ionization tendency, could capture oxygen before the silver oxidizes, thus preventing the oxidation of silver.

[0073] Figure 1 is a cross-sectional view of the heating layer relating to this disclosure. The fixing rotating body of this disclosure preferably has voids in the heating layer, and preferably the silver particles are polycrystalline particles. The heating layer 20b contains silver 221 shown in white regions, copper 222 shown in gray regions, and voids 223 shown in black regions. The silver 221 is an aggregate of multiple polycrystalline particles, and copper 222 is arranged as granular material within it. Furthermore, the copper is arranged so as to be in contact with the silver at an interface. Submicron-sized voids 223 are also present. This arrangement improves adhesion due to the anchoring effect when forming the protective layer, and also improves durability.

[0074] In the fixing rotating body of this disclosure, metal A is preferably copper. When metal A is copper, the proportion of copper was determined based on the initial volume resistivity and the volume resistivity change rate after 200 hours at 240°C. The presence of metal A, the fact that metal A is copper, and the amount of metal A can be confirmed by XPS (X-ray photoelectron spectroscopy) or SEM-EDS (energy-dispersive spectroscopy using a scanning electron microscope). Further details will be described in the examples below. In this case, it was thought that preventing the resistance of the heating layer from rising due to prolonged high temperatures above the set value in the non-paper-feeding section would also prevent unevenness in the amount of heat generated by electromagnetic induction.

[0075] The fixing rotating body of this disclosure preferably has an average silver grain size of 500 nm or less. The fixing rotating body of this disclosure preferably has a heating layer thickness of 5 μm or less. In this disclosure, the thickness of the heating layer can be confirmed by scanning electron microscope (SEM) observation of the cross-section of the fixing rotating body. In this way, the fixing rotating body of this disclosure can be made to have excellent durability even in printing environments where high temperatures persist for a long time.

[0076] (4) Resin layer The fixing rotating body of this disclosure comprises a resin layer on the surface opposite to the side facing the substrate of the heating layer. In this disclosure, the portion including the protective layer 20e, elastic layer 20c, adhesive layer 20f, and surface layer 20d may be referred to as the resin layer. That is, it is preferable that the fixing rotating body comprises a resin layer including the protective layer 20e, elastic layer 20c, adhesive layer 20f, and surface layer 20d on the surface opposite to the side facing the substrate of the heating layer. The resin layer may consist of only one protective layer or only one surface layer. It is preferable that the resin layer includes a protective layer.

[0077] (5) Protective layer The fixing rotating body may have a protective layer on the surface opposite to the side facing the substrate of the heating layer. The protective layer 20e protects the heating layer 20b and has the functions of preventing oxidation of the heating layer 20b, ensuring insulation, and improving strength.

[0078] The material constituting the protective layer 20e is not particularly limited. Preferably, the protective layer 20e is a layer containing at least a resin. When the belt is used in an electromagnetic induction fixing device, similar to the base material 20a, it is preferable that the protective layer 20e is a layer that maintains high strength and shows little change in physical properties when the heating layer 20b is heated.

[0079] Therefore, the protective layer 20e is preferably made of a heat-resistant resin, more preferably contains a heat-resistant resin as its main component, and is preferably composed of a heat-resistant resin. The heat-resistant resin is, for example, a resin that does not melt or decompose at temperatures below 200°C (preferably below 250°C).

[0080] The resin constituting the protective layer 20e preferably contains at least one selected from the group consisting of polyimide (PI), polyamideimide (PAI), modified polyimide, and modified polyamideimide. The method for forming the substrate 20a and the protective layer 20e is not particularly limited. For example, an imide-based material can be coated in a liquid form called varnish using a known method and then fired to form a film.

[0081] The protective layer 20e may contain a thermally conductive filler from the viewpoint of heat transfer. By improving heat transfer, the heat generated in the heat-generating layer 20b can be efficiently transferred to the outer surface of the fixing rotating body.

[0082] 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 bending resistance of the heat-generating layer 20b, it is preferable that the thickness of the protective layer 20e be adjusted so that the heat-generating layer 20b is located on the neutral axis. The neutral axis can be calculated from the thickness and elastic modulus of the base material 20a and the thickness and elastic modulus of the protective layer 20e. By positioning the heat-generating layer 20b on the neutral axis, the stress on the heat-generating layer 20b is kept even when subjected to repeated bending, thereby suppressing the occurrence of cracks in the heat-generating layer 20b.

[0083] (6) Elastic layer The fixing rotating body may have an elastic layer 20c on the outer surface of the protective layer 20e. The elastic layer 20c is a layer that provides flexibility to the fixing rotating body in order to ensure a fixing nip in the fixing device. Furthermore, when the fixing rotating body is used as a heating element that comes into contact with toner on paper, the elastic layer 20c also functions as a layer that provides flexibility to the surface of the heating element so that it can conform to the irregularities of the paper.

[0084] 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 composed of a cured product obtained by curing a composition that includes at least rubber raw materials (base polymer, crosslinking agent, etc.) and a thermally conductive filler.

[0085] The thickness of the elastic layer can be, for example, 100-1000 μm or 200-500 μm. From the viewpoint of exhibiting the functions of the elastic layer 20c described above, the elastic layer 20c is preferably composed of a cured silicone rubber product containing thermally conductive particles, and more preferably composed of a cured product of an addition-curing type silicone rubber composition.

[0086] The silicone rubber composition may include, for example, thermally conductive particles, a base polymer, a crosslinking agent and a catalyst, and optionally, additives. Since silicone rubber compositions are often liquid, thermally conductive fillers are easily dispersed, and the elasticity of the elastic layer 20c to be produced can be easily adjusted by adjusting the degree of crosslinking according to the type and amount of thermally conductive filler added.

[0087] The matrix plays a role in providing elasticity to the elastic layer 20c. From the viewpoint of enabling the elastic layer 20c to exhibit the above-described function, the matrix preferably contains silicone rubber. Silicone rubber is preferable because it has high heat resistance that allows it to maintain flexibility even in environments where the non-paper-feeding region reaches high temperatures of about 240°C. The elastic layer 20c is formed by applying and heating a liquid silicone rubber composition using a known method.

[0088] (7) Adhesive layer The fixing rotating body may have an adhesive layer 20f on the outer surface of the elastic layer 20c for bonding the surface layer 20d, which will be described later. The adhesive layer 20f is a layer for bonding the elastic layer 20c and the surface layer 20d. The adhesive used for the adhesive layer 20f can be appropriately selected from known adhesives and is not particularly limited. However, from the viewpoint of ease of handling, it is preferable to use addition-curing silicone rubber that contains a self-adhesive component.

[0089] This adhesive contains, for example, a self-adhesive component, an organopolysiloxane having multiple unsaturated aliphatic groups of vinyl groups in its molecular chain, a hydrogen organopolysiloxane, and a platinum compound as a crosslinking catalyst. By curing the adhesive applied to the surface of the elastic layer 20c through an addition reaction, an adhesive layer 20f is formed that adheres the surface layer 20d to the elastic layer 20c.

[0090] The thickness of the adhesive layer 20f is preferably 20 μm or less. By making the thickness of the adhesive layer 20f 20 μm or less, when the fixing belt of this embodiment is placed in a heat fixing device as a heating belt, the thermal resistance can be easily set to a small value, and heat from the inner side can be efficiently transferred to the recording medium.

[0091] (8) Surface layer The fixing rotating body 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 surface of the fixing rotating body. For example, the resins exemplified below may be molded into a tube, or the surface layer 20d may be formed by coating with a resin dispersion. PFA is particularly preferred from the viewpoint of moldability and toner release properties. The thickness of the surface layer 20d is preferably 10 μm or more and 50 μm or less. Keeping the thickness of the surface layer 20d within this range makes it easier to maintain an appropriate surface hardness for the fixing rotating body.

[0092] As described above, according to one aspect of this disclosure, a fixing device is provided in which a fixing rotating body is arranged. Therefore, it is possible to provide a fixing device in which a fixing rotating body with high conductivity and excellent durability is arranged. Furthermore, this disclosure provides a conductive member having a base material and a heating layer on the base material. The base material and heating layer are as described above. Such a conductive member can suppress the increase in resistance at high temperatures. [Examples]

[0093] The present disclosure will be described in more detail below using examples, but the present disclosure is not limited to these examples. It is predicted that oxidation will be suppressed by the presence of metal A, which has a greater ionization tendency than silver, at the silver crystal interface. Therefore, from the viewpoint of ionization tendency, stability, and safety, Al (aluminum), Ni (nickel), Fe (iron), and Cu (copper) are preferred for metal A. Furthermore, from the viewpoint of conductivity, Cu (copper) was considered more preferable and an investigation was conducted.

[0094] The copper content was 0.3% by mass for Example 1, 1.0% by mass for Example 2, 0.1% by mass for Example 3, and 3.0% by mass for Example 4. For Comparative Example 1, a heating layer made only of silver without copper was processed and confirmed.

[0095] [Example 1] A release agent was applied to the surface of a cylindrical stainless steel mold with an outer diameter of 30 mm, and a coating film was formed by applying a commercially available polyimide precursor solution (U Varnish S, manufactured by Ube Industries, Ltd.) by immersion. Next, the coating film was dried at 140°C for 30 minutes to evaporate the solvent in the coating film, and then baked at 200°C for 30 minutes and 400°C for 30 minutes to imidize it, forming a polyimide film substrate with a thickness of 40 μm and a length of 300 mm.

[0096] On this polyimide film, a ring-shaped pattern with a width of 600 μm and a spacing of 200 μm was formed by inkjet using an ink mixture of silver nanoparticle-containing ink (DNS169I, manufactured by Daicel Corporation) and copper nanoparticle-containing ink (IJ-02, manufactured by Ishihara Sangyo Co., Ltd.) mixed in a mass ratio of 0.3% after firing. Then, firing was performed at 300°C for 30 minutes to form a heat-generating layer 20b with a thickness of 3 μm.

[0097] Next, a PAI solution (Biromax HR-16NN, manufactured by Toyobo Co., Ltd.) was applied to the entire surface of the heating layer 20b using a ring coat. It was then baked at 250°C for 60 minutes to form a protective layer 20e (resin layer) with a thickness of 50 μm.

[0098] Next, a primer (product name: DY39-051A / B, manufactured by Dow-Toray) was applied almost uniformly to the outer surface of the protective layer 20e to a dry mass of 40 mg. After the solvent was dried, the layer was baked in an electric furnace set to 160°C for 30 minutes.

[0099] On this primer, a 250 μm thick silicone rubber composition layer was formed using the ring-coating method. Primary crosslinking was performed at 160°C for 1 minute, followed by secondary crosslinking at 200°C for 30 minutes to form an elastic layer 20c. The following silicone rubber composition was used.

[0100] As an organopolysiloxane having alkenyl groups as component (a), a vinyl-modified polydimethylsiloxane (trade name: DMS-V41, manufactured by Gelest, number average molecular weight 68,000 (polystyrene equivalent), molar equivalent of vinyl groups 0.04 mmol / g) having at least two vinyl groups in one molecule was prepared.

[0101] Furthermore, as an organopolysiloxane having Si-H groups as component (b), 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 the mixture was thoroughly mixed to obtain an addition-curing type silicone rubber stock solution.

[0102] Furthermore, a trace amount of the addition hardening catalyst (platinum catalyst: platinum carbonylcyclovinyl methylsiloxane complex) and inhibitor were added as component (c) and thoroughly mixed. To this addition-curing silicone rubber stock, component (d), high-purity spherical alumina (product name: Alnabeads CB-A10S; manufactured by Showa Titanium Co., Ltd.) as a thermally conductive filler, was added and kneaded in a volume ratio of 45% based on the elastic layer. A composition of addition-curing silicone rubber with a durometer hardness of 10° in accordance with JIS K 6253A after curing was obtained.

[0103] Next, an addition-curing silicone rubber adhesive (product name: SE1819CV A / B, manufactured by Dow-Toray) for forming an adhesive layer 20f was applied almost uniformly to a thickness of approximately 20 μm onto the obtained elastic layer 20c. Then, a fluororesin tube (product name: NSE, manufactured by Gunze Corporation) with an inner diameter of 29 mm and a thickness of 30 μm was laminated onto this, expanding in diameter, to form a surface layer 20d.

[0104] Subsequently, the belt surface was uniformly rubbed over the fluororesin tube to remove excess adhesive from between the elastic layer 20c and the fluororesin tube, reducing the thickness to approximately 5 μm. Next, the adhesive was cured by heating at 200°C for 30 minutes, fixing the fluororesin tube onto the elastic layer 20c. Finally, both ends were cut to a length of 240 mm to obtain a fixing rotating body.

[0105] (Evaluation: High-temperature test) The fixing rotors obtained in Examples 1-4 and Comparative Example 1 were stored at atmospheric pressure at 240°C for 200 hours. This storage temperature was set based on the overheating temperature expected in the non-paper-feed section when the fixing rotor is actually incorporated into a fuser and used under special operating conditions (when printing small-sized paper continuously).

[0106] (Evaluation: Resistance measurement) Resistance values ​​were evaluated using contact resistance testing. The fabricated fixing rotating body was cut in half; one half was used for initial resistance evaluation, and the other half for evaluation after heating. For resistance measurement, the resin layer was peeled off with a cutter, and the resistance was measured using the four-terminal resistance testing method. Details of the resistance measurement are described below.

[0107] For resistance measurement, we used a HIOKI 3541 resistance meter and two FormFactor FPC-GS-500 probes. The mode was set to low power mode, and the probes were pressed against the heating layer with a distance of 20 mm between them to measure the resistance. The volume resistivity was converted from the width and thickness of the heating layer.

[0108] Similar measurements were performed before and after heating. The resistance value before heating was used as the initial value, and the rate of change in the volume resistivity value from the initial value was evaluated as follows: less than 10% was rated as A, less than 15% as B, and 20% or more as C. In this disclosure, when this evaluation is A or B, the fixing rotating body is evaluated as durable.

[0109] (Evaluation: Measurement of average silver particle size) Next, the number of silver particles and the average crystal grain size in the heating layer are determined as follows. First, an evaluation sample is prepared. One sample is taken from the fixing rotating body, measuring 5 mm in length, 5 mm in width, and with a thickness equal to the total thickness of the fixing rotating body, from the central part in the direction of the rotation axis of the fixing rotating body. The obtained sample is then polished using an ion beam on a cross section perpendicular to the circumferential direction of the fixing rotating body. At this time, the polishing position is adjusted so that the cross section perpendicular to the circumferential direction of the heating layer is exposed by the ion beam polishing.

[0110] For polishing the cross-section using an ion beam, an ion milling device (product name: IM4000, manufactured by Hitachi High-Technologies Corporation) is used. Polishing the cross-section using an ion beam prevents the detachment of fillers from the sample and the inclusion of abrasives, and also allows for the formation of a cross-section with fewer polishing marks.

[0111] Next, a 3nm thick thin film is formed on the processed cross-section using an osmium coater (product name: Tennant20) to impart conductivity. Furthermore, the cross-section of the heat-generating layer is observed using a scanning electron microscope (SEM) (product name: JSM-F100, manufactured by JEOL Ltd.), and cross-sectional images and EDS (Energy Dispersive X-ray Spectroscopy) images are obtained.

[0112] The observation area will be a 12.8 μm × 9.6 μm area, with the center of the heat-generating layer in the thickness direction aligned with the vertical center of the SEM image. The observation will be performed in backscattered electron imaging mode at 10,000x magnification. The backscattered electron imaging will be acquired under the following conditions: acceleration voltage: 5.0 kV, working distance: 10 mm. EDS images will also be acquired under these conditions.

[0113] Next, the obtained image is binarized using commercially available image software so that the crystalline particles of the silver-containing metal are white and the areas without crystalline particles are black. Specifically, the backscattered electron image is read using ImageProPlus, an image analysis software from MediaCybernetics, and the brightness distribution of this image is determined. Then, by setting the brightness range of the determined brightness distribution, binarization is performed to distinguish between the crystalline particles of the silver-containing metal and the areas without crystalline particles. The Otsu method is used as the binarization technique.

[0114] Then, lines separating the crystal grains, obtained from the contrast difference due to the difference in brightness or crystal orientation between crystal grains in the cross-sectional image of Figure 8(a), are added to the binarized image to obtain a binarized image in which each crystal grain is separated (Figure 8(b)).

[0115] In Figure 8(b), the areas that are blacked out represent voids and other structures contained in the heat-generating layer. The method for calculating the average grain size and number-average grain size from the binarized image of the heat-generating layer cross-section obtained in this way will now be explained.

[0116] Since digital image processing techniques are applied to these images, it is assumed that all images are in a common digital image format with pixels arranged in a grid. Furthermore, the binarized images are grayscale images containing only luminance information, and unless otherwise specified, all images obtained by performing image processing on these images are grayscale images in the same format.

[0117] First, the equivalent circular diameter of each crystal grain is calculated. The equivalent circular diameter of each crystal grain refers to the diameter of a circle with the same area as that crystal grain. Specifically, the number of pixels that make up each crystal grain is calculated, and the actual area of ​​the crystal grain is calculated by multiplying this number of pixels by the area of ​​one pixel.

[0118] In the SEM images used in this disclosure, the length of one side of a single pixel corresponds to 0.01 μm, therefore the number of pixels composed of each crystal grain is 0.01 × 0.01 μm. 2 Multiply by this. Furthermore, calculate the equivalent diameter of the circle by finding the diameter of the circle having this area.

[0119] The average grain size number and average grain size are calculated by dividing the sum of the equivalent circular diameters of each crystal grain obtained in this way by the total number of crystal grains. Here, a total of six samples are taken for measurement as follows: That is, one sample is taken from the central part in the direction of the rotation axis of the fixing rotating body as described above. In addition, when the length in the direction of the rotation axis of the fixing rotating body is L, one sample is taken from a point 0.1L away from the central part in the direction of the rotation axis. Samples are collected in the same manner from each sampling site, at points 120° and 240° away from the circumferential direction of the fixing rotating body, for a total of six samples.

[0120] The above procedure is repeated for six samples taken from any point on the fixing rotating body, and the average grain size and average crystal grain size are calculated for each sample. Furthermore, the arithmetic mean of these six average grain size and average crystal grain size is calculated to determine the average grain size and average crystal grain size of the silver crystals in the heating layer.

[0121] The number-average grain size of the silver in the heating layer of the resulting fixing rotating body was 199 nm, and the initial volume resistivity was 3.1 × 10⁻⁶. -8 It was Ω·m. Next, the volume resistivity was measured after heating in a 240°C oven for 200 hours. The resistance fluctuation was +8%. Based on the volume resistivity fluctuation, it was ranked as A.

[0122] [Example 2] The copper nanoparticle-containing ink was added at a mixing ratio of 1.0% by mass, and the mixture was fired at 300°C for 30 minutes in the same manner as in Example 1 to form a heat-generating layer 20b with a thickness of 3 μm, thereby obtaining a fixing rotating body. The number-average grain size of the silver in the heating layer of the resulting fixing rotating body was 121 nm, and the initial volume resistivity was 3.2 × 10⁻⁶. -8 It was Ω·m. Next, the volume resistivity was measured after heating in a 240°C oven for 200 hours. The resistance fluctuation was +9%. Based on the volume resistivity fluctuation, the rank is A.

[0123] [Example 3] The copper nanoparticle-containing ink was added at a ratio of 0.1% by mass, and the mixture was fired at 300°C for 30 minutes in the same manner as in Example 1 to form a heat-generating layer 20b with a thickness of 3 μm, thereby obtaining a fixing rotating body. The number-average grain size of the silver in the heating layer of the resulting fixing rotating body was 212 nm, and the initial volume resistivity was 3.0 × 10⁻⁶. -8 It was Ω·m. Next, the volume resistivity fluctuation rate was calculated after heating in a 240°C oven for 200 hours. The resistance fluctuation rate was +13%. Based on the volume resistivity fluctuation rate, the rank is B.

[0124] [Example 4] The copper nanoparticle-containing ink was mixed at a ratio of 3.0% by mass, and the mixture was fired at 300°C for 30 minutes in the same manner as in Example 1 to form a heat-generating layer 20b with a thickness of 3 μm, thereby obtaining a fixing rotating body. The number-average grain size of silver in the heating layer of the resulting fixing rotating body was 82 nm, and the initial volume resistivity was 4.4 × 10⁻⁶. -8 It was Ω·m. Next, the volume resistivity was measured after heating in a 240°C oven for 200 hours. The resistance fluctuation was +9%. The rank based on the volume resistivity fluctuation was A.

[0125] [Comparative Example 1] A ring-shaped pattern with a width of 600 μm and a spacing of 200 μm was formed on a polyimide film using an inkjet method with silver nanoparticle-containing ink (DNS169I, manufactured by Daicel Corporation). Then, the film was fired at 300°C for 30 minutes to form a heat-generating layer 20b with a thickness of 3 μm. A fixing rotating body was then obtained in the same manner as in Example 1.

[0126] The number-average grain size of the silver in the heating layer of the resulting fixing rotating body was 227 nm, and the initial volume resistivity was 3.0 × 10⁻⁶. -8 It was Ω·m. Next, the volume resistivity fluctuation rate was calculated after heating in a 240°C oven for 200 hours. The resistance fluctuation rate was +20%. Based on the volume resistivity fluctuation rate, the rank is C.

[0127] [Table 1]

[0128] From Comparative Example 1, the initial resistance of the silver-only wiring is 3.0 × 10⁻¹⁰. -8 The resistance is Ω·m. Examples 1-4 show that when copper is added to silver, the initial resistance is the same as or higher than that of silver alone in Comparative Example 1.

[0129]

Table 2

[0130] Taking the resistance before heating as the initial value, the variation in the volume resistivity value from the initial value was evaluated. When the variation was less than 10%, it was ranked as Rank A; when it was less than 15%, it was ranked as Rank B; and when it was 20% or more, it was ranked as Rank C. When copper was blended in Examples 1 to 4, the resistance variation rate was suppressed compared with Comparative Example 1. At this time, the resistance variation rate in Examples 1 to 4 was 15% or less, which was Rank B.

[0131] From Example 3, when the blending amount of copper was small, the volume resistivity variation rate became +13% and the resistance variation suppressing effect was inferior. Further, from Example 4, when the blending amount of copper was large, the volume resistivity variation rate became +9% and reached Rank B. However, the initial resistance was also 4.4×10 -8 Ω·m, and the resistivity was higher than the initial volume resistivity of 3.0×10 -8 Ω·m of pure silver in Comparative Example 1, and the heat generation efficiency was slightly inferior.

[0132] The disclosure of this embodiment includes the following configurations. (Configuration 1) A base material containing a resin, a heat generating layer on the base material, and a resin layer on the surface of the heat generating layer opposite to the side facing the base material are provided, The heat generating layer contains silver particles and particles of metal A having a greater tendency to ionize than silver between the silver particles, and is a rotating body for fixing. (Configuration 2) The rotating body for fixing according to Configuration 1, wherein the metal A is copper. (Configuration 3) The rotating body for fixing according to Configuration 1 or 2, wherein the content of the metal A in the heat generating layer is 0.3% by mass or more and 1.0% by mass or less. (Configuration 4) The rotating body for fixing according to any one of Configurations 1 to 3, wherein the average crystal grain diameter of the silver is 500 nm or less. (Composition 5) The fixing rotating body according to any one of configurations 1 to 4, wherein the heating layer has a plurality of segments arranged in the longitudinal direction of the fixing rotating body and electrically isolated from each other, and each of the plurality of segments is formed continuously over the entire circumferential area of ​​the fixing rotating body. (Composition 6) A fixing rotating body according to any one of configurations 1 to 5, wherein the thickness of the heating layer is 5 μm or less. (Composition 7) A fixing rotating body according to any one of configurations 1 to 6, having voids in the heating layer. (Composition 8) The fixing rotating body according to any one of configurations 1 to 7, wherein the silver particles are particles containing polycrystalline material. (Composition 9) A fixing device comprising a fixing rotating body described in any one of configurations 1 to 8. (Composition 10) An electrophotographic image forming apparatus comprising the fixing device described in configuration 9. [Industrial applicability]

[0133] As described above, this disclosure makes it possible to obtain a fixing rotating body with excellent durability even in special environments such as those in which small-sized paper is printed continuously. [Explanation of Symbols]

[0134] 1. Printer 2 cassettes 3 Separation rollers 4 Registration Roller 5 Image forming unit 5Y Yellow Image Forming Station 5M Magenta Image Forming Station 5C Cyan Image Forming Station 5K Black Image Forming Station 6Y Photosensitive Drum 7Y Electrostatic Roller 8 Scanner Units 9Y Developing Roller 10 Intermediate transfer belt 11Y Primary Transfer Section 12 Secondary transfer section 13 Discharge and Conveying Section 14 Loading section 15 Fixing device 20 Rotating body for fixing 20a base material 20b Heating layer 20c elastic layer 20d Surface layer (release layer) 20e Resin layer (protective layer) 20f adhesive layer 21 Pressure roller 21a Core metal 21b Elastic layer 21c Release layer 22 Pressurized stay 23a Device chassis side spring support member 23b Device chassis side spring support member 24a Compression spring 24b Compression spring 25 Film Guide 26 Magnetic Cores 27 Excitation coil 30 Current Sensor 30a outer magnetic core 30b Inner magnetic core 30c detection coil 40 Thermistors 40a Thermistor Spring Plate 40b Thermistor element 201 Heating Ring 201c heating ring 221 Silver 222 Copper 223 Cavity

Claims

1. A substrate containing resin, A heating layer is placed on the substrate, A resin layer is placed on the side of the heating layer opposite to the side facing the substrate. Equipped with, A fixing rotating body characterized in that the heating layer contains silver particles and particles of metal A having a greater ionization tendency than silver between the silver particles.

2. The fixing rotating body according to claim 1, wherein the metal A is copper.

3. The fixing rotating body according to claim 1, wherein the content of metal A in the heating layer is 0.3% by mass or more and 1.0% by mass or less.

4. The fixing rotating body according to claim 1, wherein the average crystal grain size of the silver is 500 nm or less.

5. The fixing rotating body according to claim 1, wherein the heating layer has a plurality of segments arranged in the longitudinal direction of the fixing rotating body and electrically isolated from each other, and each of the plurality of segments is formed continuously over the entire circumferential area of ​​the fixing rotating body.

6. The fixing rotating body according to claim 1, wherein the thickness of the heating layer is 5 μm or less.

7. The fixing rotating body according to claim 1, wherein the heating layer has voids.

8. The fixing rotating body according to claim 1, wherein the silver particles are particles containing polycrystalline material.

9. A fixing device comprising a fixing rotating body according to any one of claims 1 to 8.

10. An electrophotographic image forming apparatus comprising the fixing device described in claim 9.

Images