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

Abstract

To provide a rotating body for fixing that is excellent in durability even when a heating layer is held by different materials.SOLUTION: A rotating body for fixing has a first resin layer that has an endless shape, at least one heating layer on an outer peripheral surface of the first resin layer, a second resin layer on an outer peripheral surface of the heating layer, an elastic layer on an outer peripheral surface of the second resin layer, and a surface layer on an outer peripheral surface of the elastic layer. The first resin layer and the second resin layer are different in modulus of elasticity by at least 10% at a specific temperature. A neutral axis in a thickness direction of the rotating body for fixing is located in the heating layer or the second resin layer in a central area and end areas. The end areas are areas from both ends in a width direction of the heating layer to a specific length toward the center in the width direction, and the central area is an area from the center to the specific length toward both ends.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present disclosure relates to a fixing rotatable member and a fixing device used in an electrophotographic image forming apparatus such as an electrophotographic copying machine, a printer, etc. The present disclosure also relates 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 fixes the toner image to the recording material by heating the recording material carrying an unfixed toner image while transporting it through a nip formed by a heated fixing rotor and a pressure roller in contact with the rotor.

[0003] A fixing device that includes a fixing rotor having a conductive layer and generates heat through electromagnetic induction heating is in practical use. The fixing device using the electromagnetic induction heating method can heat the fixing rotor in a short time. Patent Document 1 discloses a belt suitable for use in an electromagnetic induction heating system. The invention of Patent Document 1 aims to reduce the distortion of the metal layer when repeated bending deformation occurs in an endless belt provided with a metal layer functioning as a heat generating layer, and to prevent the metal layer from cracking or permanently deforming. It discloses that such a problem can be solved by an endless belt having a base layer made of synthetic resin, a metal layer laminated thereon, and a coating layer made of synthetic resin laminated thereon, in which the metal layer is formed in the vicinity of a neutral axis where no distortion occurs when the belt is bent. Here, it is described that the neutral axis is the intersection line between a surface where no distortion occurs when the fixing belt is bent and a cross section of the fixing belt (paragraph

[0033] ). In other words, the neutral axis can be defined as, for example, a position where tensile force and compressive force are balanced in a cross section along the circumferential direction of the belt when an endless belt is bent and a bending moment occurs. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-070191 A Summary of the Invention [Problem to be solved by the invention]

[0005] At least one aspect of the present disclosure is directed to providing a fixing rotatable body having excellent durability even when a heat generating layer is sandwiched between different materials. At least one aspect of the present disclosure is directed to providing a fixing device that contributes to the stable formation of high-quality electrophotographic images. Furthermore, at least one aspect of the present disclosure is directed to providing an electrophotographic image forming apparatus that can stably form high-quality electrophotographic images. [Means for solving the problem]

[0006] According to at least one aspect of the present disclosure, A first resin layer having an endless shape; at least one heat generating layer on an outer peripheral surface of the first resin layer; a second resin layer on an outer peripheral surface of the heat generating layer; an elastic layer on an outer peripheral surface of the second resin layer; and a surface layer on the outer peripheral surface of the elastic layer A fixing rotor having The first resin layer and the second resin layer are heated at a temperature Tc (wherein the temperature Tc is 160° C. or more and 200° C. or less). The elastic modulus differs by at least 10% at 20°C or less, and when the temperature of the outer surface of the fixing rotor in the central region is Tc and the temperature of the outer surface in the end region is Tc+50° C., a neutral axis in the thickness direction of the fixing rotor is located within the heat generating layer or the second resin layer in the central region and the end region, The central region and the end regions are When the number of heat generating layers is one, as observed in a cross section in the width direction perpendicular to the circumferential direction of the fixing rotor, the heat generating layer is 0. the end region is an area of ​​0.48×L1 from the center toward both ends, and the central region is an area of ​​0.48×L1 from the center toward both ends, where L1 is the length from one end of the single heating layer to the other end, When the number of heat generating layers is multiple, as observed in a cross section in the width direction perpendicular to the circumferential direction of the fixing rotor, the end region of the heat generating layer group consisting of the multiple heat generating layers is an area from both ends in the width direction to 0.02×L2 toward the center in the width direction, and the central region is an area of ​​0.48×L2 from the center toward both ends, where L2 is the length from one end to the other end of the heat generating layer group. According to at least one aspect of the present disclosure, there is provided a fixing device including the fixing rotator described above and an induction heating device for heating the fixing rotator by induction heating. According to at least one aspect of the present disclosure, there is provided an electrophotographic image forming apparatus comprising 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, wherein the fixing device is the fixing device described above. Effect of the Invention

[0007] According to at least one aspect of the present disclosure, even when the heat generating layer is sandwiched between different materials, a fixing rotator having excellent durability can be obtained. Also, according to at least one aspect of the present disclosure, a fixing device using the fixing rotator can be obtained. Furthermore, according to at least one aspect of the present disclosure, an electrophotographic image forming apparatus using the fixing device can be obtained. [Brief description of the drawings]

[0008] [Figure 1] Schematic diagram of an electrophotographic image forming apparatus according to an embodiment. [Diagram 2]FIG. 1 is a schematic diagram illustrating a cross-sectional configuration of a fixing device according to an embodiment. [Diagram 3] FIG. 1 is a perspective view illustrating a cross-sectional configuration of a fixing device according to an embodiment. [Figure 4] Schematic diagram of a magnetic core and an excitation coil of a fixing device according to an embodiment. [Diagram 5] FIG. 1 is a diagram showing a magnetic field formed when a current is passed through an excitation coil according to an embodiment. [Figure 6] Cross-sectional view of a fixing rotatable body according to an embodiment. [Figure 7] FIG. 1 is a diagram for explaining a method for calculating a neutral axis in a fixing rotating body according to an embodiment; [Figure 8] FIG. 1 is a diagram showing the temperature dependence of the elastic modulus of polyimide and polyamideimide according to an embodiment. [Figure 9] FIG. 1 is a schematic diagram illustrating a cross-sectional configuration of a fixing rotator according to an embodiment in a longitudinal direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In the present disclosure, the description of "XX or more and YY or less" or "XX to YY" expressing a numerical range means a numerical range including the lower and upper 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 arbitrarily combined. In addition, in the present disclosure, a description such as "at least one selected from the group consisting of XX, YY, and ZZ" means 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.

[0010] The present inventors have been studying a fixing rotor for use in an electromagnetic induction heating system, which has a base layer containing polyimide (PI), a heat generating layer (conductive layer) on the base layer, and a protective layer containing polyamideimide (PAI) that protects the heat generating layer. The base layer containing PI is excellent in heat resistance and durability. However, the base layer containing PI needs to be baked at high temperatures and takes a long time to manufacture. On the other hand, the protective layer containing PAI can be formed at a lower temperature and in a shorter time than PI. However, PAI is slightly inferior in strength to PI. Therefore, PI is applied to the base layer, which requires high strength to slide against other members, and PAI is applied to the protective layer. In the course of examining such fixing rotors, it was found that cracks and breaks (hereinafter referred to as "cracks, etc.") occurred in the heat generating layer after long-term use. The occurrence of cracks, etc. in the heat generating layer is believed to be due to the difference in material between the base layer and the protective layer. That is, PI and PAI have different temperature dependences of elastic modulus, and PAI has a large decrease in elastic modulus in a high temperature environment (e.g., 160°C to 200°C) compared to PI. Therefore, when the fixing rotating body having the above configuration is bent, tensile stress acts on the heat generating layer, resulting in cracks and the like.

[0011] Therefore, the present inventors have studied, based on the invention described in Patent Document 1, specifically, positioning the neutral axis in the thickness direction of the fixing rotor in the heat generating layer by adjusting the thicknesses of the base layer and the protective layer. However, even in the fixing rotor obtained in this way, cracks and the like sometimes occur in the heat generating layer located near the end portion in the longitudinal direction perpendicular to the circumferential direction of the fixing rotor. In particular, when the heat generating layer is composed of a plurality of heat generating rings arranged in the longitudinal direction of the base layer and extending in the circumferential direction of the base layer, cracks or the like may occur in the heat generating rings located near the ends, causing a decrease in the electrical conductivity of the heat generating rings. The decrease in electrical conductivity of the heat generating rings located in the end regions may cause a decrease in the temperature of the outer surface of the end regions of the fixing rotor.

[0012] The present inventors therefore investigated the cause of the occurrence of cracks and the like in the heat generating layer located in the end region, and concluded that when the fixing rotor was used for a long period of time, the temperature in the end region in the longitudinal direction of the fixing rotor rose higher than that in the central region, causing the position of the neutral axis in the end region to change from the position of the neutral axis in the central region, and tensile stress was applied to the heat generating layer located in the end region. Based on these considerations and after further investigation, it was found that a fixing rotating body having the configuration described below can generate heat stably over the entire longitudinal area of ​​the heat generating layer without causing cracks or the like in the heat generating layer, even when the temperature in the end area becomes higher than that in the central area.

[0013] <Configuration> A first resin layer having an endless shape; at least one heat generating layer on an outer peripheral surface of the first resin layer; a second resin layer on an outer peripheral surface of the heat generating layer; an elastic layer on an outer peripheral surface of the second resin layer; and a surface layer on the outer peripheral surface of the elastic layer A fixing rotor having The first resin layer and the second resin layer have a modulus of elasticity that differs by at least 10% at a temperature Tc (wherein the temperature Tc is 160° C. or more and 200° C. or less), and when the temperature of the outer surface of the fixing rotor in the central region is Tc and the temperature of the outer surface in the end region is Tc+50° C., a neutral axis in the thickness direction of the fixing rotor is located within the heat generating layer or the second resin layer in the central region and the end region, The central region and the end regions are The number of the heat generating layers observed in a cross section in a width direction perpendicular to the circumferential direction of the fixing rotor. When there is one heating layer, the width of the heating layer is 0. the end region is an area of ​​0.48×L1 from the center toward both ends, and the central region is an area of ​​0.48×L1 from the center toward both ends, where L1 is the length from one end of the single heating layer to the other end, A fixing rotor, in which, when observed in a cross section in the width direction perpendicular to the circumferential direction of the fixing rotor, there are multiple heat generating layers, the end regions of the heat generating layer group consisting of the multiple heat generating layers are from both ends in the width direction to 0.02×L2 toward the center in the width direction, and the central region is an area of ​​0.48×L2 from the center toward both ends, where L2 is the length from one end to the other end of the heat generating layer group.

[0014] The fixing rotary member, and the fixing device and electrophotographic image forming apparatus made using 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 are to be changed as appropriate depending on the configuration of the member 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 the following description, components having the same function are given the same numbers in the drawings, and their description may be omitted.

[0015] (1) Outline of the configuration of the fixing rotor The fixing rotor will be described in detail with reference to the drawings. The fixing rotatable member according to one aspect of the present disclosure may be, for example, a rotatable member having an endless belt shape.

[0016] The fixing rotor has a first resin layer having an endless shape, at least one heat generating layer on the outer peripheral surface of the first resin layer, a second resin layer on the outer peripheral surface of the heat generating layer, an elastic layer on the outer peripheral surface of the second resin layer, and a surface layer on the outer peripheral surface of the elastic layer, i.e., the heat generating layer is sandwiched between the first resin layer and the second resin layer.

[0017] The fixing rotor has a base layer, a heat generating layer (conductive layer) on the outer peripheral surface of the base layer, a protective layer on the outer peripheral surface of the heat generating layer, an elastic layer on the outer peripheral surface of the protective layer, and a surface layer on the outer peripheral surface of the elastic layer. That is, the first resin layer is the base layer, and the second resin layer is the protective layer. The first resin layer and the second resin layer have elastic moduli that differ by at least 10% at a temperature Tc (wherein the temperature Tc is 160°C or higher and 200°C or lower). The structure of each layer will be described in detail below.

[0018] (2) First resin layer The first resin layer is not particularly limited as long as it is a layer that contains at least a resin. The first resin layer is a base layer. When the fixing rotator is used in an electromagnetic induction type fixing device, the first resin layer is preferably a layer that exhibits little change in physical properties and maintains high strength when the heat generating layer generates heat. For this reason, the first resin layer preferably contains a heat-resistant resin as a main component, and is preferably made of a heat-resistant resin. The heat-resistant resin is, for example, a resin that does not melt or decompose at a temperature of less than 250°C (preferably less than 300°C).

[0019] The resin contained in the first resin layer (preferably the resin constituting the first resin layer) 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. Among these, polyimide is particularly preferable. In the present disclosure, the main component means the component contained in the largest amount among the components constituting the object (here, the first resin layer). The modified polyimide and modified polyamideimide include siloxane-modified, carbonate-modified, fluorine-modified, urethane-modified, triazine-modified, and phenol-modified. The resin can be identified by, for example, NMR, GC-MASS, Fourier transform infrared spectroscopy (FT-IR), or the like.

[0020] The first resin layer can be formed, for example, by the following method. A release treatment is applied to the surface of a mold having a predetermined diameter, and a solution containing a resin is applied to form a coating film. The coating film thus formed is dried to form a first resin layer. For example, when polyimide is used as the resin, a commercially available polyimide precursor solution or the like can be applied to the surface of the mold by immersion to form a coating film. After the coating film is formed, it is baked and imidized to form a polyimide coating. The formed polyimide coating becomes the first resin layer.

[0021] The first resin layer may contain a filler to improve heat insulation and strength. The first resin layer has an endless belt shape. The thickness of the first resin layer is determined by the setting of the neutral axis described later, and is preferably 10 to 100 μm, and more preferably 20 to 60 μm. By setting the thickness of the first resin layer within the above range, it is possible to achieve both high levels of strength and flexibility.

[0022] In addition, on the surface of the first resin layer opposite the side facing the heat generating layer, for example, a layer for preventing wear of the inner surface of the fixing belt when the inner surface of the fixing belt comes into contact with other members, or a layer for improving sliding properties with other members may be provided. The outer peripheral surface of the first resin layer 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.

[0023] (3) Heating layer The heat generating layer is a layer that generates heat when the fixing rotatable body is energized and is sandwiched between the first resin layer and the second resin layer. 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, which generates a current in the heat generation layer of the fixing rotor, which generates heat by Joule heat. In other words, the heat generation layer is a conductive layer.

[0024] The material of the heat generating layer is preferably one that has a low volume resistivity and is not easily oxidized. Examples include gold, silver, copper, and aluminum. The heat generating layer preferably contains silver. The heat generating layer may contain metals other than those mentioned above to the extent that the effect of the present disclosure is not impaired.

[0025] The maximum thickness of the heat generating layer is preferably 5 μm or less. By making the maximum thickness of the heat generating layer 5 μm or less, the heat capacity of the heat generating layer can be sufficiently reduced, and the time until the heat generating layer reaches a desired temperature by electromagnetic induction can be shortened.

[0026] As shown in FIG. 2, 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. Thus, even if the fixing rotor is repeatedly bent over a long period of time, the bending resistance of the fixing rotor can be improved and fatigue failure can be prevented by setting the maximum thickness of the heat generating layer to 5 μm or less. This is because, when the heat generating layer is pressed and deformed to fit the shape of the curved surface of the film guide 25, the internal stress acting on the heat generating layer becomes smaller as the heat generating layer becomes thinner.

[0027] The maximum thickness of the heat generating layer is more preferably 3 μm or less. The lower limit of the thickness of the heat generating layer is not particularly limited, but from the viewpoint of maintaining durability, it is preferably 1 μm or more. Therefore, the maximum thickness of the heat generating layer is preferably 1 to 5 μm, and particularly preferably 1 to 3 μm.

[0028] The maximum thickness of the heat generating layer in the fixing rotor can be measured, for example, by the following method. Six samples, each 5 mm long, 5 mm wide, and the full thickness of the fixing rotor, are taken from any location on the fixing rotor. The circumferential cross sections of the fixing rotor are exposed using a cross-section polisher (product name: SM09010, manufactured by JEOL Ltd.) for the six samples obtained. Next, the cross section of the exposed heat generating layer was observed with a scanning electron microscope (SEM) (product name: JSM-F100, manufactured by JEOL Ltd.) at an acceleration voltage of 3 kV, a working distance of 2.9 mm, and a magnification of 10,000 times to obtain an image with a width of 13 μm and a height of 10 μm. Parallel lines were drawn on the heat generating layer in the obtained image at the point closest to the first resin layer and the point closest to the second resin layer on the opposite side, and the distance between the parallel lines was defined as the maximum thickness in the image, and the arithmetic average value of the maximum thicknesses of the six samples was defined as the maximum thickness of the heat generating layer. The parallel lines were drawn based on the surface of the first resin layer opposite the heat generating layer in the observation area.

[0029] The heat generating layer extends in the circumferential direction of the outer peripheral surface of the first resin layer. The heat generating layer may be configured in a predetermined pattern as long as it is capable of generating heat when energized. In particular, as shown in FIG. 3, a configuration in which a plurality of ring-shaped heat generating rings 201 are formed in a state in which they are electrically divided in the direction of the rotation axis of the fixing rotor is preferable. In other words, the heat generating layer may be configured with a plurality of heat generating rings 201 arranged adjacent to each other and spaced apart from each other.

[0030] The ring-shaped heat generating rings 201 are preferably formed at substantially regular intervals along the rotation axis direction of the fixing rotor. For example, an ink containing silver nanoparticles can be applied in a pattern on the outer circumferential surface of the substrate using an inkjet method to form a ring-shaped coating film containing silver nanoparticles, and the coating film can be baked to form a heat generating layer made of heat generating rings containing silver.

[0031] When the heat generating layer is composed of a plurality of heat generating rings, the width of the heat generating ring is preferably 100 μm or more, more preferably 200 μm or more, from the viewpoints of manufacturability and heat generation. From the viewpoints of uneven heat generation and safety, the width is preferably 1000 μm or less, more preferably 700 μm or less. The width of the ring is, for example, preferably 100 to 1000 μm, more preferably 200 to 700 μm.

[0032] From the viewpoints of manufacturability and heat generation, the distance between the rings of the heat generation layer is preferably 50 μm or more, and more preferably 100 μm or more. From the viewpoint of uneven heat generation, the distance is preferably 400 μm or less, and more preferably 300 μm or less. The distance between the rings is, for example, preferably 50 to 300 μm, and more preferably 100 to 300 μm.

[0033] The heat generating layer may be formed as a heat generating layer group consisting of a plurality of heat generating layers. The heat generating layer group is, for example, composed of a plurality of heat generating layers formed at intervals on the outer peripheral surface of the first resin layer. In other words, there may be an area on the outer peripheral surface of the first resin layer where no heat generating layer is formed.

[0034] (4) Second resin layer The second resin layer is present on the outer peripheral surface of the heat generating layer. The second resin layer is a protective layer. The second resin layer protects the heat generating layer and has the functions of preventing oxidation of the heat generating layer, ensuring insulation, and improving strength.

[0035] The resin constituting the second resin layer is preferably a resin that exhibits little change in physical properties when the heat generating layer is heated and can maintain high strength. For this reason, the second resin layer preferably contains a heat-resistant resin as a 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 a temperature of less than 250°C (preferably less than 300°C).

[0036] The resin constituting the second resin layer 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. Among these, polyamideimide is particularly preferable. The modification is the same as that described for the first resin layer. The type of resin can be identified, for example, by the method described above.

[0037] The second resin layer can be formed, for example, by the following method. A solution containing a resin is applied to the outer peripheral surface of the heat generating layer to form a coating film. The formed coating film is then baked to form the second resin layer. For example, when polyamideimide is used as the resin, a commercially available polyamideimide solution can be applied to the heat generating layer to form a coating film. The method of applying the solution is not particularly limited, and for example, ring coating can be used. The thickness of the second resin layer does not have to be constant, and may be changed locally. For example, in a direction perpendicular to the circumferential direction of the fixing rotor and along the heat generating layer, the second resin layer may be thicker at the ends and thinner at the center than at the ends. The thickness of the resin layer can be changed, for example, by controlling the total liquid amount and moving speed of the ring coat.

[0038] The second resin layer may contain a thermally conductive filler from the viewpoint of heat transfer, which allows the heat generated in the heat generating layer to be efficiently transferred to the outer surface of the fixing rotor. The thickness of the second resin layer is determined by setting the neutral axis, which will be described later, and is preferably from 10 to 100 μm, and more preferably from 20 to 80 μm.

[0039] Next, the neutral axis in the thickness direction of the fixing rotor will be described. The neutral axis is the position where tensile stress and compressive stress are balanced in the cross section when a bending moment is applied to the member. The position of the neutral axis is determined by the thickness and elastic modulus of each layer that constitutes the member.

[0040] Consider a belt-shaped member consisting of n layers as shown in Fig. 7. Taking the surface of this belt-shaped member as a reference, the distance in the thickness direction is y, the cross-sectional area of ​​the i-th layer from the surface is Ai, the width of this layer is bi, and the elastic modulus is Ei. The distance y0 from the surface of the belt-shaped member to the neutral axis is defined by the following formula (1). TIFF2025073874000002.tif9153

[0041] Here, considering per unit width (b=1), the cross-sectional area Ai of the i-th layer from the surface = the thickness of the i-th layer from the surface. In other words, dAi = dyi, and the distance y0 from the surface of the belt-shaped member to the neutral axis is expressed by the following formula (2). TIFF2025073874000003.tif9153

[0042] As described above, the fixing rotor is pressurized, deformed, and subjected to stress at the nip N every time it is rotated. If tensile stress or compressive stress continues to be applied due to long-term use, etc., the occurrence of The heating layer is prone to cracks and permanent deformation, which increases the resistance of the heating layer and makes it impossible to effectively generate heat through electromagnetic induction heating.

[0043] By controlling the neutral axis of the fixing rotor in the thickness direction to be located within the heat generating layer, the tensile stress and compressive stress in the heat generating layer are balanced, and the tensile and compressive stresses applied to the heat generating layer are minimized. As a result, phenomena that lead to increased resistance, such as cracks and permanent deformation, are less likely to occur, improving the durability of the fixing rotor.

[0044] In addition, the above-mentioned cracks and permanent deformation are particularly likely to occur when the heating layer is subjected to tensile stress. Therefore, even if the neutral axis is not located within the heating layer, by making the stress applied to the heating layer compressive, it is possible to suppress the deterioration of durability compared to when tensile stress is applied. Specifically, by positioning the neutral axis within the second resin layer on the outer peripheral surface of the heating layer, the stress applied to the heating layer can be made compressive, thereby improving durability compared to when tensile stress is applied.

[0045] Here, when the fixing rotor is in use, the temperature of the outer surface differs between the central region, which is the paper passing portion through which the recording material passes, and the end regions, which are non-paper passing portions through which the recording material does not pass. When the recording material passes through the fixing device, the temperature of the outer surface of the central region becomes about 160 to 200°C because heat is taken away by the passing recording material. On the other hand, the temperature of the end regions is maintained because the recording material does not pass through them, and the temperature of the outer surface becomes about 50°C higher than that of the central region. Therefore, when the first resin layer and the second resin layer are formed using resins with different temperature dependences of elastic modulus, even if the neutral axis is located within the heating layer or the second resin layer in the central region, the position of the neutral axis may change in the end regions where the outer surface temperature is about 50°C higher than Tc, and tensile stress may be applied to the heating layer.

[0046] The temperature dependency of the elastic modulus and the neutral axis will be described below. Fig. 8 is a diagram showing the temperature dependence of the elastic modulus of polyimide and polyamideimide. The temperature dependence of the elastic modulus of polyimide and polyamideimide is different, and polyamideimide has a lower elastic modulus in the high temperature region. Moreover, the difference between the elastic modulus of both becomes larger as the temperature rises.

[0047] For example, when different materials are used, such as polyimide for the first resin layer and polyamideimide for the second resin layer, the elastic modulus of the first resin layer and the second resin layer differs between the central region and the end region of the fixing rotor. Therefore, even if the neutral axis is controlled to be located within the heat generating layer or the second resin layer in the central region, the position of the neutral axis changes in the end region where the temperature of the outer surface is high.

[0048] The fixing rotor has an elastic layer and a surface layer, which will be described later, but the elastic layer and the surface layer usually have a low elastic modulus and hardly affect the position of the neutral axis. That is, the position of the neutral axis in the thickness direction of the fixing rotor can be controlled by the materials and thicknesses of the first resin layer, the heat generation layer, and the second resin layer. A method for controlling the position of the neutral axis in the thickness direction of the fixing rotor will be described below.

[0049] For example, consider a case in which the heat generating layer is made of silver having a thickness of 2.5 μm and an elastic modulus of 10 GPa, the first resin layer contains polyimide, and the second resin layer contains polyamideimide. When a 40 μm thick polyimide is used as the first resin layer, the elastic modulus at 180°C, which corresponds to the temperature of the outer surface of the central region of the fixing rotor during use, is 5.4 GPa. On the other hand, the polyamideimide contained in the second resin layer has an elastic modulus of 4.6 GPa at 180°C. In this case, calculations based on the above formula (2) show that by setting the thickness of the second resin layer to 47 μm, the neutral axis in the thickness direction can be positioned within the heat generating layer.

[0050] However, as described above, the central region of the fixing rotor is always in contact with the paper passing through it, and heat is transferred to the paper. On the other hand, in the end region, the frequency of contact with the paper may be lower than in the central region. In the end region, where the frequency of contact with the paper is lower than in the central region, heat accumulates, and the temperature of the outer surface may rise to, for example, about 230°C. At a temperature of 230°C, the elastic modulus of polyimide is 4.5 GPa, while the elastic modulus of polyamideimide is 2.9 GPa. As a result, the value of y0 calculated by the above formula (2) becomes larger. That is, the neutral axis in the end region is located closer to the inner surface (first resin layer side) of the heat generating layer than the neutral axis in the central region. As a result, the heat generating layer located in the end region is subjected to tensile stress, which makes it more likely to crack.

[0051] Calculating based on the above formula (2), by setting the thickness of the second resin layer (layer containing polyamideimide) in the end region to 62 μm, the neutral axis in the end region can be positioned within the heat generating layer. In other words, by configuring the second resin layer to have different thicknesses in the central region and the end region, the neutral axis can be positioned within the heat generating layer. As a result, it is possible to improve the durability of the fixing rotor as a whole.

[0052] As described above, the first resin layer and the second resin layer have a modulus of elasticity that differs by at least 10% at the temperature Tc. The temperature Tc is in the range of 160°C to 200°C, and corresponds to the temperature of the outer surface of the central region when the fixing rotor is in use. The temperature Tc may be, for example, in the range of 165°C to 195°C, or in the range of 170°C to 190°C. The modulus of elasticity of the first resin layer and the second resin layer differs by at least 10% at the temperature Tc as a prerequisite for the need to consider the position of the neutral axis in the thickness direction of the fixing rotor. The difference in elastic modulus between the first resin layer and the second resin layer at temperature Tc is preferably 10 to 30%, and the difference in elastic modulus between the first resin layer and the second resin layer at temperature Tc+50° C. is preferably 20 to 50%.

[0053] The inventors have discovered that even when the elastic modulus at temperature Tc of the first resin layer and the second resin layer is different, the durability of the fixing rotor can be maintained by positioning the neutral axis as follows. In other words, when the temperature of the outer surface in the central region of the fixing rotor is Tc and the temperature of the outer surface in the end region is Tc+50°C, the neutral axis in the thickness direction of the fixing rotor is positioned within the heating layer or the second resin layer in the central region and end region, thereby maintaining the durability of the fixing rotor.

[0054] 9A is a cross-sectional view showing an example of a fixing rotor in which the number of heat generating layers 20b observed in a cross section in the width direction perpendicular to the circumferential direction of the fixing rotor is one. The heat generating layer 20b is sandwiched between the first resin layer 20a and the second resin layer 20e. When the length from one end of the heat generating layer to the other end is L1, the regions from both ends of the heat generating layer in the width direction to 0.02×L1 toward the center in the width direction are the end regions. Also, the region from the center toward both ends that is 0.48×L1 is the central region. The central region corresponds to the above-mentioned paper passing portion, and the end region corresponds to the above-mentioned non-paper passing portion.

[0055] As described above, the heat generating layer may be formed as a heat generating layer group consisting of a plurality of heat generating layers. Fig. 9B is a cross-sectional configuration diagram showing an example of a fixing rotor in which a heat generating layer 20b is formed as a heat generating layer group consisting of a plurality of heat generating layers in a cross section in the width direction perpendicular to the circumferential direction of the fixing rotor. The heat generating layer group is sandwiched between a first resin layer 20a and a second resin layer 20e. In this embodiment, when the length from one end to the other end of the heat generating layer group consisting of a plurality of heat generating layers is L2, from both ends of the heat generating layer group in the width direction toward the center in the width direction, The area up to 0.02×L2 is defined as the edge area, and the area from the center to both ends that is 0.48×L2 is defined as the central area.

[0056] As described above, the position of the neutral axis in the thickness direction can be controlled by the material and thickness of each layer. For example, by changing the thickness of a specific layer between the central region and the end region, the neutral axis can be controlled to be located in the heat generating layer or the second resin layer in the central region and the end region. Whether the neutral axis in the thickness direction of the fixing rotor is located in the heat generating layer or the second resin layer can be confirmed by the method described later.

[0057] The average thickness of the second resin layer in the central region is A0, the average thickness of the first resin layer is B0, and the average thickness of the second resin layer in the end region is A1, and the average thickness of the first resin layer is B1. The temperature of the outer surface of the fixing rotor in the central region is Tc, and the temperature of the outer surface in the end region is Te. Tc is in the range of 160°C to 200°C, and Te is Tc + 50°C. The elastic modulus of the second resin layer at temperature Tc is EA(Tc), the elastic modulus of the first resin layer is EB(Tc), and the elastic modulus of the second resin layer at temperature Te is EA(Te), and the elastic modulus of the first resin layer is EB(Te). In this case, it is preferable that the fixing rotor satisfies the following formulas (3) to (6). A0≧EB(Tc) / EA(Tc)×B0 Equation (3) A1≧EB(Te) / EA(Te)×B1 Equation (4) A0×EA(Tc)≦1.2×B0×EB(Tc) Formula (5) A1×EA(Te)≦1.2×B1×EB(Te) Formula (6)

[0058] Satisfying the above formula (3) indicates that in the central region, the stresses received by the first resin layer and the second resin layer are balanced, the neutral axis is located within the sandwiched heating layer, and the stress on the heating layer is minimized, or the neutral axis is located within the second resin layer, and the heating layer is subjected to compressive stress. Satisfying the above formula (4) indicates that in the end region, the stresses received by the first resin layer and the second resin layer are balanced, the neutral axis is located within the sandwiched heating layer, and the stress on the heating layer is minimized, or the neutral axis is located within the second resin layer, and the heating layer is subjected to compressive stress. Therefore, by satisfying the above formulas (3) and (4), the neutral axis in the thickness direction of the fixing rotor in the central region and the end region can be positioned within the heat generating layer or the second resin layer, thereby improving the durability of the fixing rotor.

[0059] On the other hand, if the second resin layer is too thick, the compressive stress on the heat generating layer becomes too large, and the durability is likely to decrease. Therefore, it is preferable that the fixing rotor satisfies the following formulas (5) and (6). A0×EA(Tc)≦1.2×B0×EB(Tc) Formula (5) A1×EA(Te)≦1.2×B1×EB(Te) Formula (6)

[0060] Satisfying the above formula (5) means that the neutral axis located in the second resin layer in the central region is not too far from the first resin layer, and the compressive stress applied to the heat generating layer is not too large. Satisfying the above formula (6) means that the neutral axis located in the second resin layer in the end region is not too far from the first resin layer, and the compressive stress applied to the heat generating layer is not too large. In other words, satisfying formulas (5) and (6) indicates that the thickness of the second resin layer is appropriate in the central region and end region. As a result, the compressive stress applied to the heat generating layer is not too large, and durability can be improved.

[0061] EB(Tc) is not particularly limited, but is preferably 4.0 to 10.0 GPa. EA(Tc) is not particularly limited, but is preferably 4.0 to 10.0 GPa. It is preferable that EB(Tc) is greater than EA(Tc). EB(Te) is not particularly limited, but is preferably 3.0 to 9.0 GPa. Also, EA(Te) is not particularly limited, but is preferably 3.0 to 9.0 GPa. EB(Te) is preferably larger than EA(Te).

[0062] The average thickness A0 of the second resin layer in the central region is not particularly limited, but is preferably 20 to 80 μm, and more preferably 30 to 70 μm, and the average thickness B0 of the first resin layer in the central region is not particularly limited, but is preferably 10 to 70 μm, and more preferably 20 to 60 μm. The average thickness A1 of the second resin layer in the edge region is not particularly limited, but is preferably 10 to 100 μm, and more preferably 40 to 100 μm, and the average thickness B1 of the first resin layer in the edge region is not particularly limited, but is preferably 10 to 70 μm, and more preferably 20 to 60 μm.

[0063] The combined thickness of the first resin layer, the heat generating layer, and the second resin layer is preferably 150 μm or less, more preferably 100 μm or less, in the central region, and preferably 200 μm or less, more preferably 150 μm or less, in the edge regions.

[0064] FIG. 6 is a cross-sectional view of the fixing rotor in the circumferential direction. The fixing rotor has a first resin layer 20a, a heat generating layer 20b on the outer surface of the first resin layer 20a, and a protective layer 20e on the outer surface of the heat generating layer. The first resin layer 20a is the first resin layer described above, the heat generating layer 20b is the heat generating layer described above, and the protective layer 20e is the second resin layer described above. Furthermore, the fixing rotor has an elastic layer 20c on the outer peripheral surface of the second resin layer 20e and a surface layer (release layer) 20d on the outer peripheral surface of the elastic layer. Also, an adhesive layer 20f can be provided between the elastic layer 20c and the surface layer 20d, if necessary.

[0065] (5) Elastic layer The fixing rotator has an elastic layer 20c on the outer surface of the second resin layer 20e. The elastic layer 20c is a layer for imparting flexibility to the fixing rotor in order to secure a fixing nip in the fixing device. When the fixing rotor is used as a heating member that comes into contact with the toner on the paper, the elastic layer 20c also functions as a layer for imparting flexibility so that the surface of the heating member 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 the raw materials of the rubber (base polymer, crosslinking agent, etc.) and the thermally conductive filler.

[0066] The elastic layer 20c preferably contains silicone rubber. From the viewpoint of realizing the above-mentioned functions of the elastic layer 20c, the elastic layer 20c is preferably made of a silicone rubber cured product containing thermally conductive particles, and more preferably made of a cured product of an 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. Since the silicone rubber composition is often liquid, the thermally conductive filler is 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 the thermally conductive filler.

[0067] The matrix has a function of providing elasticity to the elastic layer 20c. From the viewpoint of providing the above-mentioned function of the elastic layer 20c, the matrix preferably contains silicone rubber. Silicone rubber is preferable because it has high heat resistance that allows it to maintain flexibility even in a high-temperature environment of about 230°C such as the non-paper passing area. Examples of silicone rubber include A cured product of an addition curing type liquid silicone rubber composition 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.

[0068] The liquid silicone rubber composition generally contains the following components (a) to (d): Component (a): an organopolysiloxane having an unsaturated aliphatic group; Component (b): an organopolysiloxane having active hydrogen bonded to silicon; Component (c): catalyst; Component (d): Thermally conductive filler Each component will be described below.

[0069] 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 structural formulas (1) and (2). [ka]

[0070] In structural formula (1), m 1 is an integer equal to or greater than 0, and n 1 R indicates an integer of 3 or more. 1 each independently represents a monovalent unsubstituted or substituted hydrocarbon group not containing an unsaturated aliphatic group; R 1 At least one of R represents a methyl group. 2 each independently represents an unsaturated aliphatic group. [ka]

[0071] In structural formula (2), n 2 indicates a positive integer. 3 each independently represents a monovalent unsubstituted or substituted hydrocarbon group not containing an unsaturated aliphatic group; R 3 At least one of R represents a methyl group. 4 each independently represents an unsaturated aliphatic group.

[0072] In structural formulas (1) and (2), R 1 and R 3 Examples of the monovalent unsubstituted or substituted hydrocarbon group not containing an unsaturated aliphatic group that can be represented by include the following groups. Unsubstituted hydrocarbon groups Alkyl groups (for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, etc.), aryl groups (for example, phenyl, etc.). Substituted hydrocarbon groups Substituted alkyl groups (eg, chloromethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, 3-cyanopropyl, 3-methoxypropyl, and the like).

[0073] The organopolysiloxanes represented by structural formulas (1) and (2) have at least one methyl group directly bonded to the silicon atom forming the chain structure. R 1 and R 3 It is preferable that 50% or more of each group are methyl groups, and all of R 1 and R 3 More preferably, is a methyl group.

[0074] In addition, in the structural formulas (1) and (2), R 2 and R 4 Examples of the unsaturated aliphatic group which may be represented include the following groups: Vinyl group, allyl group, 3-butenyl group, 4-pentenyl group, 5-hexenyl group, etc. Among these groups, R 2 and R 4 is preferably a vinyl group.

[0075] From the viewpoint of moldability, the viscosity (kinetic viscosity) of component (a) is 1000 to 50000 mm 2 / s. The viscosity is preferably 1000mm 2 If the hardness is lower than 50,000 mm / s, it becomes difficult to adjust the hardness required for the elastic layer 20c. 2 If the viscosity is higher than 1 / s, the viscosity of the composition becomes too high and coating becomes difficult. Viscosity (kinetic viscosity) can be measured using a capillary viscometer, rotational viscometer, or the like in accordance with JIS Z 8803:2011.

[0076] The blending amount of component (a) is preferably 55% by volume or more from the viewpoint of durability and 65% by volume or less from the viewpoint of heat conductivity, based on the liquid silicone rubber composition used to form the elastic layer 20c.

[0077] Ingredient (b) The organopolysiloxane having active silicon-bonded hydrogens functions as a crosslinker that reacts with the unsaturated aliphatic groups of component (a) in the presence 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), it is preferable to use one having an average of 3 or more hydrogen atoms bonded to silicon atoms in one molecule.

[0078] Specific examples of component (b) include the linear organopolysiloxane shown in the following structural formula (3) and the cyclic organopolysiloxane shown in the following structural formula (4). [ka]

[0079] In structural formula (3), m 2is an integer equal to or greater than 0, and n 3 R indicates an integer of 3 or more. 5 each independently represents a monovalent unsubstituted or substituted hydrocarbon group that does not contain an unsaturated aliphatic group. [ka]

[0080] In structural formula (4), m 3 is an integer equal to or greater than 0, and n 4 R indicates an integer of 3 or more. 6 each independently represents a monovalent unsubstituted or substituted hydrocarbon group that does not contain an unsaturated aliphatic group.

[0081] R in structural 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 It is preferable that 50% or more of each group are methyl groups, and all of R 5 and R 6 More preferably, is a methyl group.

[0082] Ingredient (c) The catalyst used in forming the silicone rubber may be, for example, a hydrosilylation catalyst for promoting the curing reaction. As the hydrosilylation catalyst, for example, a known substance such as a platinum compound or a rhodium compound may be used. The amount of the catalyst to be added may be appropriately set and is not particularly limited.

[0083] Ingredient (d) Examples of the thermally conductive filler include metals, metal compounds, carbon fibers, etc. 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 (polyacrylonitrile) carbon fiber, pitch-based carbon fiber, etc.

[0084] These fillers can be used alone or in combination of two or more kinds. The average particle size of the filler is preferably 1 to 50 μm from the viewpoints of handling and dispersibility. The shape of the filler may be spherical, pulverized, needle-like, plate-like, or whisker-like. In particular, from the viewpoint of dispersibility, the filler is preferably spherical. Furthermore, at least one of a reinforcing filler, a heat-resistant filler, and a coloring filler may be added.

[0085] (6) Adhesive layer The fixing rotating body may have an adhesive layer 20f on the outer surface of the elastic layer 20c for adhering the surface layer 20d described later. The adhesive layer 20f is a layer for adhering 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 an addition curing type silicone rubber containing a self-adhesive component. This adhesive may contain, for example, a self-adhesive component, an organopolysiloxane having a plurality of unsaturated aliphatic groups, typically vinyl groups, in the molecular chain, a hydrogen organopolysiloxane, and a platinum compound as a crosslinking catalyst. The adhesive is then cured by an addition reaction to form an adhesive layer 20f that bonds the surface layer 20d to the elastic layer 20c.

[0086] Examples of the self-adhesive component include the following: A silane having at least one functional group, 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 (Si-H 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 1 to 4, preferably 1 to 2, aromatic rings such as phenylene structures having a valence of 1 to 4, preferably valence of 2 to 4, in one molecule, and at least 1, preferably 2 to 4, functional groups capable of contributing to a hydrosilylation addition reaction (e.g., alkenyl groups, (meth)acryloxy groups) in one molecule.

[0087] The above-mentioned self-adhesive components may be used alone or in combination of two or more. In addition, from the viewpoint of viscosity adjustment and heat resistance, a filler component may be added to the adhesive within the scope of the present invention. Examples of the filler component include the following. Silica, alumina, iron oxide, cerium oxide, cerium hydroxide, carbon black, etc.

[0088] The amount of each component contained in the adhesive is not particularly limited and can be set appropriately. Such addition curing type silicone rubber adhesives are commercially available and can be easily obtained. 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 small, and the heat from the inner surface side can be efficiently transferred to the recording medium.

[0089] (7) Surface layer The fixing rotor has a surface layer 20d on the outer circumferential surface of the elastic layer. The surface layer 20d preferably contains a fluororesin in order to function as a release layer that prevents toner from adhering to the outer surface of the fixing rotor. The surface layer 20d may be formed, for example, by molding the resin exemplified below into a tube shape, or by coating the resin dispersion liquid. Tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), etc. Among the resin materials exemplified above, PFA is particularly preferably used from the viewpoints of moldability and toner releasability.

[0090] The thickness of the surface layer 20d is preferably 10 to 50 μm. By setting the thickness of the surface layer 20d within this range, it is easy to maintain an appropriate surface hardness of the fixing rotor.

[0091] (Electrophotographic image forming apparatus) An electrophotographic image forming apparatus (hereinafter also simply referred to as an "image forming apparatus") includes an image carrier that carries a toner image, a transfer device that transfers the toner image onto a recording material, and a fixing device that fixes the transferred toner image onto the recording material. FIG. 1 is a cross-sectional view showing the overall configuration of a color laser beam printer (hereinafter, printer) 1 as an example of an image forming apparatus equipped with a fixing device (image heating device) 15 according to the embodiment. A cassette 2 is housed in a removable manner in the lower portion of the printer 1. 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. In addition, 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, sheet materials with surface treatments such as plastic film, cloth, and coated paper, and sheet materials of special shapes such as envelopes and index paper.

[0092] The printer 1 is provided with an image forming unit 5 as an image forming means in which image forming units 5Y, 5M, 5C, and 5K corresponding to the respective colors of yellow, magenta, cyan, and black are arranged in a horizontal row. The image forming unit 5Y is provided with a photosensitive drum 6Y which is an image carrier (electrophotographic photosensitive member) that carries a toner image, and a charging roller 7Y which serves as a charging means for uniformly charging the surface of the photosensitive drum 6Y.

[0093] Furthermore, a scanner unit 8 is disposed below the image forming section 5. The scanner unit 8 irradiates a laser beam that is on / off modulated in response to 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, thereby forming an electrostatic latent image on the photosensitive drum 6Y.

[0094] Furthermore, the image forming unit 5Y includes a developing roller 9Y as a developing means that adheres toner to the electrostatic latent image on the photosensitive drum 6Y to develop it into a toner image, and a primary transfer unit 11Y that transfers the toner image on the photosensitive drum 6Y to the intermediate transfer belt 10. Toner images formed by similar processes in other image forming units 5M, 5C, and 5K are superimposed and transferred onto the toner image on intermediate transfer belt 10 transferred by 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 by secondary transfer unit 12 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.

[0095] 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 conveying section 13 and is discharged and stacked on a stacking section 14. 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 the fixing device, the fixing device may be, for example, a direct transfer 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 device that uses toner of only one color.

[0096] (Fixing device) The fixing device 15 is an induction heating type fixing device (image heating device) that heats a fixing rotator by electromagnetic induction. That is, the fixing device includes a fixing rotator and an induction heating device for heating the fixing rotator by induction heating. The fixing rotator described above can be used as the fixing rotator. Fig. 2 shows a cross-sectional configuration of fixing device 15, and Fig. 3 is a perspective view of fixing device 15. The housing of fixing device 15 and the like are omitted in Fig. 2 and Fig. 3. In the following description, with regard to the members constituting 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, that is, the direction of the rotation axis of fixing rotor 20.

[0097] 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 exciting coil 27, 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 onto the recording material. The fixing rotor 20 is the rotor of this embodiment, and the pressure roller 21 is the opposing member of this embodiment. The exciting coil 27 functions as a magnetic field generating means in this embodiment. The fixing rotor will be described in detail later.

[0098] The fixing rotatable member 20 has a first resin layer, at least one heat generating layer, a second resin layer, an elastic layer, and a surface layer. The heat generating layer 20b can generate heat, for example, by induced current. That is, the heat generating layer 20b is a conductive layer. The heat generating layer 20b is formed in a ring shape by electrically connecting each other in the circumferential direction, and is formed as a heat generating pattern in which heat generating rings 201 (FIG. 3) are arranged in the longitudinal direction, the heat generating rings 201 being 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 each of which is connected in the circumferential direction of the fixing rotor 20 and is not electrically connected to one another 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. As described above, the heat generating layer may be formed as a heat generating layer group consisting of a plurality of heat generating layers. The heat generating layer group is composed of a plurality of heat generating layers formed at intervals on the outer peripheral surface of the first resin layer, for example.

[0099] The pressure roller 21, which serves as an opposing body (pressure member) facing the fixing rotor 20, includes a core metal 21a and an elastic layer 21b molded and coated concentrically around the core metal in a roller shape, with a release layer 21c provided on the surface layer. The elastic layer 21b is preferably made of a material having excellent heat resistance, such as silicone rubber, fluororubber, or fluorosilicone rubber. Both ends of the core metal 21a in the longitudinal direction are rotatably held between metal plates on the chassis side (not shown) of the device via conductive bearings.

[0100] In addition, as shown in FIG. 3, pressure springs 24a and 24b are respectively compressed between both longitudinal ends of the pressure stay 22 and spring receiving 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 about 100N to 300N (about 10kgf to about 30kgf) is applied. As a result, as shown in Fig. 2, the lower surface of the film guide 25 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 portion N of a predetermined width.

[0101] That is, the film guide 25 functions as a nip portion forming member that, together with the pressure roller 21, forms a nip portion for nipping and conveying the recording material carrying the toner image via the fixing rotor 20. The pressure roller 21 is driven to rotate in a clockwise direction 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 against the film guide 25.

[0102] 4 is a schematic diagram of the magnetic core 26 and the excitation coil 27 shown in FIG. 2, 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 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 helical portion whose helical axis is substantially 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. "Substantially parallel" does not mean that the two axes are completely parallel, but rather that a slight misalignment is allowed to the extent that the heat generating layer can generate heat through electromagnetic induction. The magnetic core 26 is disposed in the spiral portion and extends in the direction of the rotation axis of the fixing rotor 20. Therefore, no loop is formed outside the fixing rotor 20. The magnetic core 26 induces the magnetic field lines of the alternating magnetic field.

[0103] 4, 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 in a spiral shape 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. 2).

[0104] The magnetic core 26 provided inside the excitation coil 27 has a role of guiding the magnetic field lines (magnetic flux) of the alternating magnetic field generated by the excitation coil 27 to the inside of the heat generating layer 20b of the fixing rotor 20, and forming a path (magnetic path) of the magnetic field lines. The material of the magnetic core 26 is a ferromagnetic material. As the ferromagnetic material, a material with small hysteresis loss and high relative permeability is preferable, and for example, at least one soft magnetic material with high permeability selected from the group consisting of sintered ferrite, ferrite resin, etc. is preferable.

[0105] The cross-sectional shape of the magnetic core 26 may be any shape that can be housed in the hollow portion of the fixing rotor 20. The cross-sectional shape of the magnetic core 26 does not need to be circular, but it is preferable that the cross-sectional area is as large as possible. In this embodiment, the diameter of the magnetic core 26 is 10 mm, and the length in the longitudinal direction is 280 mm.

[0106] The exciting coil 27 can be formed, for example, by winding a copper wire (single conductor) with a diameter of 1 to 2 mm coated with heat-resistant polyamideimide in a double spiral shape around the magnetic core 26. The exciting coil 27 is wound around the outer periphery of 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 exciting 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 later, causing the heat generating ring 201 to generate heat.

[0107] 2 and 3, the thermistor 40 as a 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 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 a 50 μm thick polyimide tape to ensure electrical insulation.

[0108] The thermistor 40 is fixed to the film guide 25 and installed at a position approximately at 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 of the fixing rotor 20. The thermistor 40 may be disposed on the outer periphery of the fixing rotor 20.

[0109] The current sensor 30 constituting the continuity monitoring device that monitors the circumferential continuity of the heat generating layer 20b is disposed at the same position as the thermistor 40 in the longitudinal direction of the fixing device 15. In other words, what is monitored by the current sensor 30 is the continuity state of the heat generating ring 201 at the position where the thermistor element 40b is in contact, among the multiple heat generating rings 201 constituting the heat generating pattern of the fixing rotor 20.

[0110] (Heating principle) The heating principle of the fixing rotatable body 20 in the fixing device 15 of the induction heating type will be described. 5 is a conceptual diagram showing the moment when the current increases in the direction of the arrow I0 in the exciting coil 27. The exciting coil 27 is wound around the outer periphery of the magnetic core 26 inserted in the fixing rotor 20. By passing an alternating current through the fixing rotor 20, an alternating magnetic field is formed in the direction of the rotation axis of the fixing rotor 20, and the fixing rotor 20 functions as a magnetic field generating means for generating an induced current I in the circumferential direction of the fixing rotor 20. Further, the magnetic core 26 functions as a member that induces magnetic lines of force B (dotted lines in FIG. 5) generated by the exciting coil 27 and forms a magnetic path.

[0111] In a typical induction heating type fixing device, magnetic lines of force penetrate the heat generating layer to generate eddy currents. In contrast, in this embodiment, the magnetic lines of force B are configured to loop outside the fixing rotor. That is, the heat generating layer 20b is mainly heated by the induced current induced by the magnetic lines of force that leave 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. In this way, heat can be generated efficiently even if the heat generating layer is thin, for example, 5 μm or less.

[0112] When an alternating magnetic field is generated 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 is generated that tries to pass a current through the circuit, and the induced electromotive force is proportional to the time change in the magnetic flux that perpendicularly penetrates the circuit."

[0113] Consider the induced current I that flows through heat-generating ring 201c located at the center in the longitudinal direction of magnetic core 26 shown in Fig. 5 when a high-frequency alternating current is passed through excitation coil 27. When a high-frequency alternating current is passed, an alternating magnetic field is formed inside magnetic core 26. In this case, the induced electromotive force acting on heat-generating ring 201c is proportional to the time change in magnetic flux that perpendicularly penetrates the inside of heat-generating ring 201c, according to the following formula 1.

number

[0114] 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 disconnected, the induced current I does not flow, and the heat-generating ring 201c does not generate heat. EXAMPLES

[0115] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples.

[0116] [Example 1] A release treatment was applied to the surface of a cylindrical stainless steel mold having an outer diameter of 30 mm, and a commercially available polyimide precursor solution (product name: 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 in the coating film, and then baked at 200°C for 30 minutes and at 400°C for 30 minutes to imidize the film, forming a first resin layer (base layer) having a thickness of 30 μm and a length of 300 mm. Next, a silver nanoparticle-containing ink (DNS163 Using a 300-μm thick inkjet printer (manufactured by Daicel Corporation), multiple ring-shaped patterns were formed by an inkjet method so that the width in the longitudinal direction was 300 μm and the interval in the longitudinal direction was 200 μm, and all around the circumference of the base layer. After that, it was baked at a temperature of 300° C. for 30 minutes, and the thickness was 2.5 μm and the width was The heat generating layer was formed of multiple heat generating rings extending in the circumferential direction of the base layer, and had a thickness of 300 μm. Therefore, in the fixing belt according to this embodiment, the end regions were the regions extending from both ends of the heat generating layer to the center in the longitudinal direction by 4.4 mm.

[0117] Next, a PAI solution (Viromax HR-16NN, Toyobo Co., Ltd.) was applied to the entire surface of the heat generating layer using a ring coat. The thickness of the center and edges was changed by controlling the amount of liquid sent and the moving speed of the ring coat. It was baked at 230°C for 30 minutes to form a second resin layer with a thickness of 35 μm in the center region and 47 μm in the edge region. Next, a primer (product name: DY39-051A / B, manufactured by Dow Toray) was applied approximately uniformly to the outer peripheral surface of the second resin layer to a dry weight of 20 mg, and after the solvent was dried, the primer was baked for 30 minutes in an electric furnace set at 160°C. On this primer, a silicone rubber composition layer having a thickness of 200 μm was formed by ring coating, and the layer was subjected to primary crosslinking at 160° C. for 1 minute, and then secondary crosslinking at 200° C. for 30 minutes to form an elastic layer 20c.

[0118] The silicone rubber composition used was as follows: As component (a), an organopolysiloxane having an alkenyl group was prepared, which was a vinylated polydimethylsiloxane having at least two vinyl groups per molecule (product name: DMS-V41, manufactured by Gelest, number average molecular weight 68,000 (polystyrene equivalent), molar equivalent of vinyl group 0.04 mmol / g).

[0119] Also, as the organopolysiloxane having Si-H groups as component (b), a methylhydrogenpolysiloxane having at least two Si-H groups per molecule (product name: HMS-301, manufactured by Gelest, number average molecular weight 1300 (polystyrene equivalent), molar equivalent of Si-H groups 3.60 mmol / g) 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.

[0120] Further, a trace amount of a catalyst for addition curing reaction (platinum catalyst: platinum carbonylcyclovinylmethylsiloxane complex) and an inhibitor (component (c)) were added and thoroughly mixed. High-purity spherical alumina (product name: Alnabeads CB-A10S; manufactured by Showa Titanium Co., Ltd.) was mixed and kneaded as component (d) heat-conductive filler to a volume ratio of 45% based on the elastic layer into the addition-curing silicone rubber stock solution, and an addition-curing silicone rubber composition having a JIS K 6253A durometer hardness of 10° after curing was obtained.

[0121] Next, an addition-curing silicone rubber adhesive (product name: SE1819CV A / B, manufactured by Dow Toray Industries, Inc.) for forming the adhesive layer 20f was applied uniformly to a thickness of about 20 μm on the obtained 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 50 μm for forming the surface layer 20d was laminated on top of this while expanding its diameter. After that, the belt surface was uniformly pressed from above the fluororesin tube to press out excess adhesive between the elastic layer 20c and the fluororesin tube to a thickness of 5 μm. Next, the adhesive was cured by heating at 200° C. for 30 minutes to fix the fluororesin tube on the elastic layer 20c, and finally both ends were cut to a length of 240 mm to obtain a fixing belt.

[0122] [Examples 2-3, Comparative Examples 1-2] Fixing belts according to Examples 2 and 3 and Comparative Examples 1 and 2 were produced in the same manner as in Example 1, except that the thicknesses of the first resin layer and the second resin layer were changed to the levels shown in Table 1.

[0123] (Evaluation: thickness and elasticity of each layer) The cross section of the fixing belts produced in Examples 1 to 3 and Comparative Examples 1 and 2 was observed in the circumferential direction, and the thickness of each layer was measured. Six samples, each measuring 5 mm in length, 5 mm in width, and the total thickness of the fixing rotor, were taken from the fixing belt, one each from six arbitrary positions on the fixing belt. The obtained samples were polished using an ion milling device (product name: IM4000, manufactured by Hitachi High-Technologies Corporation) to expose arbitrary cross sections.

[0124] Next, the cross section of the fixing rotor in the thickness direction was observed with a scanning electron microscope (SEM) (product name: FE-SEM JSM-F100, manufactured by JEOL Ltd.) to obtain a cross-sectional image. The conditions were a backscattered electron image mode of 200 to 5000 times magnification, and the backscattered electron image acquisition conditions were an acceleration voltage of 3.0 kV and a working distance of 3 mm. From the cross-sectional images thus obtained, the thickness of each layer was measured, and the average value of the six samples was taken as the average thickness.

[0125] In addition, for the sample whose cross section was exposed by the above-mentioned method, the elastic modulus of each layer was measured using a scanning probe microscope (SPM) (product name: Dimension ICON, manufactured by Bruker Corporation). Specifically, for the sample whose cross section was exposed using the method described above, the elastic modulus was calculated from the elastic modulus mapping image obtained by measuring under the following measurement conditions: spring constant 0.315 N / m, indentation load 200 pN, pixel count 512 × 512, field of view: 1.2 μm × 1.2 μm.

[0126] (Evaluation: Confirmation of neutral axis in thickness direction of fixing rotor) The position of the neutral axis in the thickness direction of the fixing rotor was confirmed by the following method. The thickness and elastic modulus of each layer were calculated using the above-mentioned method, and the distance from the surface of the fixing rotor to the neutral axis was calculated from each obtained value using equation (2). The position of the neutral axis was identified from the obtained distance and the thickness of each layer from the outer surface of the fixing rotor.

[0127] (Evaluation: durability test) The fixing rotors prepared in Examples 1 to 3 and Comparative Examples 1 and 2 were attached to a fixing device and rotated while paper was passed through, and the degree of increase in resistance due to continuous rotation was confirmed. The electrical resistance value was calculated from the current value that flowed when a voltage of 1 V was applied to the excitation coil. The number of sheets of paper passed until the resistance value reached 105% or more, with the initial resistance value being taken as the standard (100%), was defined as the number of sheets of paper that could be passed until the resistance value reached 105% or more. The durability of the fixing rotor was evaluated according to the following criteria. <Evaluation criteria> A: Durability is over 300,000 sheets B: Durability is between 200,000 and 300,000 sheets C: Durability is less than 200,000 sheets

[0128] The materials, physical properties and evaluation results of the fixing rotor are shown in Tables 1 and 2. [Table 1] In Table 1, "k sheets" in the durability evaluation means "x 1000 sheets." For example, 300k sheets means 300 x 1000 = 300,000 sheets. [Table 2]

[0129] From the results in Table 1, it can be seen that Examples 1 to 3, in which the position of the neutral axis was set in consideration of the temperatures in the central region and the end region, are superior in durability to Comparative Examples 1 and 2. [Industrial Applicability]

[0130] As described above, the present disclosure provides a durable heat generating device even when the heat generating layer is sandwiched between different materials. The present invention can be used for a fixing rotatable body having excellent durability. The present invention can also be used for a fixing device in which a fixing rotatable body having excellent durability is disposed. Furthermore, the present invention can be used for an electrophotographic image forming apparatus using the fixing device.

[0131] The present disclosure relates to the following configurations. (Configuration 1) A first resin layer having an endless shape; at least one heat generating layer on an outer peripheral surface of the first resin layer; a second resin layer on an outer peripheral surface of the heat generating layer; an elastic layer on an outer peripheral surface of the second resin layer; and a surface layer on the outer peripheral surface of the elastic layer A fixing rotor having The first resin layer and the second resin layer have a modulus of elasticity that differs by at least 10% at a temperature Tc (wherein the temperature Tc is 160° C. or more and 200° C. or less), and when the temperature of the outer surface of the fixing rotor in the central region is Tc and the temperature of the outer surface in the end region is Tc+50° C., a neutral axis in the thickness direction of the fixing rotor is located within the heat generating layer or the second resin layer in the central region and the end region, The central region and the end regions are When the number of heat generating layers is one, as observed in a cross section in the width direction perpendicular to the circumferential direction of the fixing rotor, the heat generating layer is 0. the end region is an area of ​​0.48×L1 from the center toward both ends, and the central region is an area of ​​0.48×L1 from the center toward both ends, where L1 is the length from one end of the single heating layer to the other end, A fixing rotor, characterized in that when the number of heat generating layers is multiple, as observed in a cross section in the width direction perpendicular to the circumferential direction of the fixing rotor, the end region of a heat generating layer group consisting of the multiple heat generating layers is a region from both ends in the width direction to 0.02 x L2 toward the center in the width direction, and the central region is a region of 0.48 x L2 from the center toward both ends, wherein L2 is the length from one end to the other end of the heat generating layer group. (Configuration 2) In the central region, the average thickness of the second resin layer is A0, and the average thickness of the first resin layer is B0; In the end region, the average thickness of the second resin layer is A1, and the average thickness of the first resin layer is B1, The elastic modulus of the second resin layer at the temperature Tc is defined as EA(Tc), and the elastic modulus of the first resin layer is defined as EB(Tc), When the temperature of the outer surface in the end region is Te, the elastic modulus of the second resin layer at the temperature Te is EA(Te), and the elastic modulus of the first resin layer is EB(Te), The fixing rotatable member according to configuration 1, wherein A0, B0, A1, B1, EA(Tc), EB(Tc), EA(Tc) and EB(Tc) satisfy the following formulae (3) to (6). A0≧EB(Tc) / EA(Tc)×B0 Equation (3) A1≧EB(Te) / EA(Te)×B1 Equation (4) A0×EA(Tc)≦1.2×B0×EB(Tc) Formula (5) A1×EA(Te)≦1.2×B1×EB(Te) Formula (6) (Configuration 3) The EB(Tc) is greater than the EA(Tc), 3. The fixing rotator according to claim 1, wherein the EB(Te) is greater than the EA(Te). (Configuration 4) The first resin layer includes at least one selected from the group consisting of polyimide, polyamideimide, modified polyimide, and modified polyamideimide. The fixing rotatable member according to any one of configurations 1 to 3. (Configuration 5) 5. The fixing rotatable member according to any one of configurations 1 to 4, wherein the second resin layer contains at least one selected from the group consisting of polyimide, polyamideimide, modified polyimide, and modified polyamideimide. (Configuration 6) 4. The fixing rotatable member according to any one of configurations 1 to 3, wherein the first resin layer contains polyimide, and the second resin layer contains polyamideimide. (Configuration 7) 7. The fixing rotating member according to any one of configurations 1 to 6, wherein the elastic layer contains silicone rubber, and the surface layer contains a fluorine resin. (Configuration 8) A fixing rotating body according to any one of configurations 1 to 7, and an induction heating device for heating the fixing rotatable body by induction heating. (Configuration 9) 1. An electrophotographic image forming apparatus, comprising: an image carrier that carries a toner image; a transfer device for transferring the toner image onto a recording material; a fixing device for fixing 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 configuration 8. [Explanation of symbols]

[0132] 1 image forming apparatus, 15 fixing device, 20 fixing rotor, 20a first resin layer, 20b Heat generating layer, 20c elastic layer, 20d surface layer, 20e second resin layer, 20f adhesive layer, 21 pressure roller, 28 first resin layer, 29 second resin layer, 31 heat generating layer, 201 heat generating ring

Claims

1. A first resin layer having an endless shape; at least one heat generating layer on an outer peripheral surface of the first resin layer; a second resin layer on an outer peripheral surface of the heat generating layer; an elastic layer on an outer peripheral surface of the second resin layer; and a surface layer on the outer peripheral surface of the elastic layer A fixing rotor having The first resin layer and the second resin layer have a modulus of elasticity that differs by at least 10% at a temperature Tc (wherein the temperature Tc is 160° C. or higher and 200° C. or lower); and when the temperature of the outer surface of the fixing rotor in the central region is Tc and the temperature of the outer surface in the end region is Tc+50° C., a neutral axis in the thickness direction of the fixing rotor is located within the heat generating layer or the second resin layer in the central region and the end region, The central region and the end regions are When the number of heat generating layers is one, as observed in a cross section in the width direction perpendicular to the circumferential direction of the fixing rotor, the thickness of the heat generating layer is 0.5 mm from both ends of the heat generating layer in the width direction toward the center in the width direction. the end regions are regions of 0.02×L1 from the center toward both ends, and the central region is a region of 0.48×L1 from the center toward both ends, where L1 is the length from one end of the single heat generating layer to the other end, A fixing rotor, characterized in that when the number of heat generating layers is multiple, as observed in a cross section in the width direction perpendicular to the circumferential direction of the fixing rotor, the end region of a heat generating layer group consisting of the multiple heat generating layers is a region from both ends in the width direction to a center in the width direction of 0.02 x L2, and the central region is a region from the center to both ends of 0.48 x L2, wherein L2 is the length from one end to the other end of the heat generating layer group.

2. In the central region, the average thickness of the second resin layer is A0, and the average thickness of the first resin layer is B0, The average thickness of the second resin layer in the end region is A1, and the average thickness of the first resin layer is B1, The elastic modulus of the second resin layer at the temperature Tc is defined as EA(Tc), and the elastic modulus of the first resin layer is defined as EB(Tc), When the temperature of the outer surface in the end region is Te, the elastic modulus of the second resin layer at the temperature Te is EA(Te), and the elastic modulus of the first resin layer is EB(Te), 2. The fixing rotating member according to claim 1, wherein A0, B0, A1, B1, EA(Tc), EB(Tc), EA(Tc) and EB(Tc) satisfy the following formulas (3) to (6). A0≧EB(Tc) / EA(Tc)×B0 Formula (3) A1≧EB(Te) / EA(Te)×B1 Formula (4) A0×EA(Tc)≦1.2×BO×EB(Tc) Formula (5) A1×EA(Te)≦1.2×B1×EB(Te) Formula (6)

3. the EB(Tc) is greater than the EA(Tc); The fixing rotator according to claim 2 , wherein the EB(Te) is greater than the EA(Te).

4. The first resin layer includes at least one selected from the group consisting of polyimide, polyamideimide, modified polyimide, and modified polyamideimide. The fixing rotating member according to any one of claims 1 to 3.

5. The second resin layer is made of polyimide, polyamideimide, modified polyimide, or modified polyamide.

4. The fixing rotatable member according to claim 1, further comprising at least one selected from the group consisting of diimides.

6. 4. The fixing rotator according to claim 1, wherein the first resin layer contains polyimide, and the second resin layer contains polyamideimide.

7. 4. The fixing rotating member according to claim 1, wherein the elastic layer contains silicone rubber, and the surface layer contains a fluorine resin.

8. A fixing rotating body according to any one of claims 1 to 3, and an induction heating device for heating the fixing rotatable body by induction heating.

9. 1. An electrophotographic image forming apparatus, comprising: an image carrier that carries a toner image; a transfer device for transferring the toner image onto a recording material; a fixing device for fixing 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 claim 8.

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