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

Abstract

To provide a rotating body for fixing that is excellent in durability even in a particular printing environment such as where small-sized papers are continuously printed.SOLUTION: A rotating body for fixing has a cylindrical base material, a conductive layer on an outer peripheral surface of the base material, and a resin layer that covers the conductive layer. The base material has at least one solid layer. The conductive layer extends in a circumferential direction of the base material, and the conductive layer has at least one hole in a cross-sectional view in a direction along the circumferential direction of the base material. The resin layer has at least one continuous hole starting from a surface of the resin layer facing the conductive layer and reaching the other surface of the resin layer.SELECTED DRAWING: Figure 5

Description

Technical Field

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

Background Art

[0002] A fixing device mounted on an electrophotographic image forming apparatus such as an electrophotographic copying machine or a printer generally heats a recording material carrying an unfixed toner image in a nip portion formed by a rotator for fixing to be heated and a pressure roller contacting therewith to fix the toner image on the recording material while conveying the recording material.

[0003] A fixing device using an electromagnetic induction heating method having a conductive layer on a rotator for fixing and capable of directly generating heat in the conductive layer has been developed and put into practical use. The fixing device using the electromagnetic induction heating method has an advantage of a short warm-up time. For example, Patent Document 1 discloses a fixing member having a conductive layer formed by copper plating.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] At least one aspect of the present disclosure is directed to providing a rotator for fixing having excellent durability even in a special printing environment such as continuously printing small-sized paper. Further, at least one aspect of the present disclosure is directed to providing a fixing device contributing to stable provision of high-quality electrophotographic images. Furthermore, at least one aspect of the present disclosure is directed to providing an electrophotographic image forming apparatus capable of stably forming high-quality electrophotographic images.

Means for Solving the Problem

[0006] According to one aspect of the present disclosure, a fixing rotating body, the fixing rotating body includes a cylindrical base material, a conductive layer on the outer peripheral surface of the base material, and a resin layer covering the conductive layer, the base material has at least one solid layer, the conductive layer extends in the circumferential direction of the base material, and the conductive layer has at least one hole in a cross-sectional view in a direction along the circumferential direction of the base material, a fixing rotating body having at least one communication hole extending from the surface of the resin layer on the conductive layer side to the other surface of the resin layer is provided.

[0007] Also, according to at least one aspect of the present disclosure, the above fixing rotating body, a fixing device including an induction heating device that generates heat for the fixing rotating body by induction heating is provided.

[0008] Furthermore, according to at least one aspect of the present disclosure, an electrophotographic image forming apparatus, the electrophotographic image forming apparatus, an image carrier that supports a toner image, a transfer device that transfers the toner image to a recording material, a fixing device that fixes the transferred toner image to the recording material, is provided, an electrophotographic image forming apparatus in which the fixing device is the above fixing device is provided.

Advantages of the Invention

[0009] According to at least one aspect of the present disclosure, a fixing rotating body excellent in durability is provided. Also, according to at least one aspect of the present disclosure, a fixing device that contributes to stable provision of high-quality electrophotographic images can be obtained. Furthermore, according to at least one aspect of the present disclosure, an electrophotographic image forming apparatus capable of stably forming high-quality electrophotographic images can be obtained.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0011] In the present disclosure, the description of "XX or more and YY or less" or "XX to YY" representing a numerical range means a numerical range including the lower limit and the upper limit which are the endpoints, unless otherwise specified. When the numerical ranges are described stepwise, the upper limit and the lower limit of each numerical range can be arbitrarily combined. Further, in the present disclosure, a description such as "at least one selected from the group consisting of XX, YY, and ZZ" means any one of XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, or a combination of XX, YY, and ZZ.

[0012] The inventors expected the effect of reducing heat generation unevenness, and tried to apply a nano ink capable of controlling fine line widths and spaces when forming the conductive layer. There are holes in the conductive layer formed with the nano ink. The presence of the holes improves the durability due to the effect of improving adhesion by the anchor effect and the effect of improving mechanical strength such as suppressing buckling by the damper effect when forming the resin layer covering the conductive layer.

[0013] On the other hand, in the fixing member, when sheets of different sizes are inserted, there is a phenomenon that the member temperature rises at the end where the sheet does not pass, that is, the non-paper-passing part. Since the fixing member surely fixes the toner in the paper-passing part where the paper passes, it is heated to maintain the fixing temperature at any time. Since the paper-passing part requires continuous heating as the paper passes while taking heat away, on the other hand, in the non-paper-passing part, since there is no heat transfer due to paper passing, the member temperature may become higher than the set temperature. This phenomenon is likely to occur especially in a special usage environment such as continuously printing small-sized sheets.

[0014] The inventors have found that when using a fixing member using a conductive layer having pores as a heating layer, when a high-temperature state above the set temperature continues for a long time in the non-paper-passing part, fine convex shapes (blisters) are formed on the fixing member. With such convex shapes, image defects such as image dropout are likely to occur during fixing. The formation of such convex shapes is considered to be caused by the remaining air in the pores inside the heating layer expanding and the interface between the conductive layer and the resin layer peeling off. It was considered that this was due to the remaining air in the pores inside the heating layer expanding and the interface between the conductive layer and the resin layer peeling off.

[0015] Therefore, as a result of the inventors' study, it has been found that the rotating body for fixing of the present disclosure contributes to the solution of the above problems. Hereinafter, the rotating body for fixing of the present disclosure, a fixing device and an electrophotographic image forming device made using the same will be described in detail based on the following specific configurations.

[0016] (Electrophotographic image forming device) An electrophotographic image forming device (hereinafter, also simply referred to as "image forming device") includes 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. FIG. 2 is a cross-sectional view showing the overall configuration of a color laser beam printer (hereinafter referred to as a printer) 1, which is an example of an image forming apparatus equipped with a fixing device (image heating device) 15 according to an embodiment. A cassette 2 is retractably housed in the lower part of the printer 1. The cassette 2 stacks and houses a sheet P as a recording material. The sheet P in the cassette 2 is fed to a registration roller 4 in a state of being separated one by one by a separation roller 3. Note that as the sheet P as a recording material, various sheets with different sizes and materials can be used, such as paper such as plain paper and cardboard, plastic film, cloth, sheet materials with surface treatment such as coated paper, and special-shaped sheet materials such as envelopes and index paper.

[0017] The printer 1 includes an image forming unit 5 as an image forming means in which image forming stations 5Y, 5M, 5C, and 5K corresponding to yellow, magenta, cyan, and black colors are arranged side by side in a horizontal row. The image forming station 5Y is provided with a photosensitive drum 6Y which is an image carrier (electrophotographic photosensitive member) for carrying a toner image, and a charging roller 7Y as a charging means for uniformly charging the surface of the photosensitive drum 6Y.

[0018] Furthermore, a scanner unit 8 is disposed below the image forming unit 5. The scanner unit 8 irradiates a laser beam that is on / off modulated corresponding to a digital image signal input from an external device such as a computer (not shown) based on image information and generated by image processing means, to form an electrostatic latent image on the photosensitive drum 6Y. Further, the image forming station 5Y includes a developing roller 9Y as a developing means for attaching toner to the electrostatic latent image on the photosensitive drum 6Y to develop it as a toner image (toner picture), and a primary transfer portion 11Y for transferring the toner image on the photosensitive drum 6Y to an intermediate transfer belt 10.

[0019] On the toner image on the intermediate transfer belt 10 where the toner image is transferred by the primary transfer unit 11Y, toner images formed by the same process at other image forming stations 5M, 5C, and 5K are multi-transferred. As a result, a full-color toner image is formed on the intermediate transfer belt 10. This full-color toner image is transferred to the sheet P by the secondary transfer unit 12 as a transfer means. The primary transfer unit 11Y and the secondary transfer unit 12 are examples of a fixing device that fixes the transferred toner image to a recording material. Thereafter, the toner image transferred onto the sheet P (on the recording material) passes through the fixing device 15 and is fixed as a fixed image. Further, the sheet P passes through the discharge conveyance unit 13 and is discharged and stacked on the stacking unit 14.

[0020] Note that the above 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 fixing device of a direct transfer method that directly transfers a toner image from an image carrier to the sheet P. Further, the image forming apparatus may use a monochrome configuration that uses only one color of toner.

[0021] (Fixing device) The fixing device 15 of the present embodiment is an induction heating type fixing device (image heating device) that generates heat for the fixing rotating body by electromagnetic induction. That is, the fixing device 15 includes a fixing rotating body and an induction heating device that generates heat for the fixing rotating body by induction heating. FIG. 3 shows a cross-sectional configuration of the fixing device 15, and FIG. 4 is a perspective view of the fixing device 15. Note that the housing and the like of the fixing device 15 are omitted in FIGS. 3 and 4. In the following description, regarding the members constituting the fixing device 15, the longitudinal direction X1 is a direction orthogonal to the conveyance direction of the recording material and the thickness direction of the recording material.

[0022] The fixing device 15 includes a rotary fixing member 20, a film guide 25, a pressure roller 21, a pressure stay 22, a magnetic core 26, an exciting coil 27 (Fig. 5), a thermistor 40, and a current sensor 30. The fixing device 15 heats the recording material on which an image is formed to fix the image on the recording material. The rotary fixing member 20 is the rotary member of the present embodiment, and the pressure roller 21 is the opposing member of the present embodiment. Further, the exciting coil 27 functions as the magnetic field generating means of the present embodiment. Details of the rotary fixing member will be described later.

[0023] The rotary fixing member 20 has a conductive layer 20b serving as a heat generating layer on a base material. The conductive layer (heat generating layer) 20b can generate heat by, for example, induced current. The conductive layer 20b is formed in a ring shape with each being electrically connected in the circumferential direction, and a heat generating ring 201 (Fig. 4) that is electrically divided in the longitudinal direction X1 (the rotation axis direction of the rotary fixing member 20) is formed as a heat generating pattern arranged in the longitudinal direction. That is, the conductive layer 20b is a plurality of annular regions each connected in the circumferential direction of the rotary fixing member 20, and is divided into a plurality of annular regions that are not electrically connected to each other in the rotation axis direction of the rotary fixing member 20. Each heat generating ring 201, which is a component of the heat generating pattern, is formed with a uniform width in the longitudinal direction X1.

[0024] The pressure roller 21 as an opposing member (pressure member) facing the rotary fixing member 20 includes a core metal 21a and an elastic layer 21b integrally formed in a roller shape concentrically around the core metal, and a release layer 21c is provided on the surface layer. The elastic layer 21b is preferably made of a material with good heat resistance such as silicone rubber, fluororubber, or fluorosilicone rubber. Both ends of the core metal 21a in the longitudinal direction are rotatably held and disposed between side chassis sheet metals (not shown) of the apparatus via conductive bearings.

[0025] Further, as shown in Fig. 4, by respectively providing compression springs 24a and 24b between both ends in the longitudinal direction of the pressure stay 22 and spring receiving members 23a and 23b on the apparatus chassis side, a pressing force is applied to the pressure stay 22. Note that in the fixing device 15 of the present embodiment, a pressing force of approximately 100 N to 300 N (approximately 10 kgf to approximately 30 kgf) is applied. As a result, the lower surface of the film guide 25 made of a heat-resistant resin such as PPS and the upper surface of the pressure roller 21 are pressed against each other with the fixing rotating body 20, which is a cylindrical rotating body, interposed therebetween to form a fixing nip portion N with a predetermined width. The film guide 25 functions as a nip portion forming member that forms a nip portion for sandwiching and conveying a recording material carrying a toner image via the fixing rotating body 20 together with the pressure roller 21. Here, PPS is polyphenylene sulfide.

[0026] The pressure roller 21 is rotationally driven clockwise by a driving means (not shown), and a counterclockwise rotational force acts on the fixing rotating body 20 due to the frictional force with the outer surface of the fixing rotating body 20. As a result, the fixing rotating body 20 rotates while sliding on the film guide 25.

[0027] FIG. 5 is a schematic diagram of the magnetic core 26 and the exciting coil 27 in FIG. 3, and the fixing rotating body 20 is shown by a dashed line to explain the positional relationship with the fixing rotating body 20. In an induction heating type fixing device that generates heat in the fixing rotating body 20 by electromagnetic induction, the induction heating device may include a magnetic core 26 and an exciting coil 27. The exciting coil 27 is disposed inside the fixing rotating body 20. The exciting coil 27 has a helical shape portion whose helical axis is substantially parallel to the direction along the rotation axis of the fixing rotating body 20, and forms an alternating magnetic field that causes the conductive layer 20b to generate heat by electromagnetic induction. Substantially parallel means not only a state where the two axes are completely parallel, but also allowing a slight deviation to the extent that the conductive layer can generate heat by electromagnetic induction. The magnetic core 26 is disposed inside the helical shape portion, extends in the rotation axis direction of the fixing rotating body 20, and does not form a loop outside the fixing rotating body 20. The magnetic core 26 induces the magnetic field lines of the alternating magnetic field.

[0028] In Fig. 5, the magnetic core 26 is inserted into the hollow portion of the fixing rotator 20 which is a cylindrical rotating body. Further, the exciting coil 27 is wound around the outer periphery of the magnetic core 26 in a spiral shape and extends in the longitudinal direction of the fixing rotator 20. The magnetic core 26 has a cylindrical shape and is fixed by fixing means (not shown) so as to be located substantially at the center of the fixing rotator 20 in a cross section viewed in the longitudinal direction (see Fig. 3).

[0029] The magnetic core 26 provided inside the exciting coil 27 serves to guide the magnetic force lines (magnetic flux) of the alternating magnetic field generated by the exciting coil 27 to the inside of the conductive layer 20b of the fixing rotator 20 and form a path (magnetic circuit) for the magnetic force lines. The material of the magnetic core 26 is a ferromagnetic material. The material of the ferromagnetic magnetic core 26 is preferably at least one high-permeability soft magnetic material selected from the group consisting of materials with low hysteresis loss and high relative permeability, such as sintered ferrite, ferrite resin, etc.

[0030] The cross-sectional shape of the magnetic core 26 only needs to be a shape that can be accommodated in the hollow portion of the fixing rotator 20, and although it does not need to be circular, a shape with as large a cross-sectional area as possible is preferred. In this embodiment, the diameter of the magnetic core 26 is 10 mm and the length in the longitudinal direction is 280 mm.

[0031] The exciting coil 27 is formed by winding a copper wire (single conductor) with a diameter of 1 - 2 mm coated with heat-resistant polyamideimide around the magnetic core 26 in a spiral shape for 20 turns. The exciting coil 27 is wound around the magnetic core 26 in a direction intersecting the rotation axis direction of the fixing rotator 20. Therefore, when a high-frequency alternating current is passed through this exciting coil 27, an alternating magnetic field is generated in a direction parallel to the rotation axis direction, and an induced current (eddy current) flows through each heating ring 201 of the conductive layer 20b of the fixing rotator 20 to generate heat by the principle described later.

[0032] As shown in FIGS. 3 and 4, the thermistor 40 as a temperature detecting means for detecting the temperature of the fixing rotator 20 is composed of a spring plate 40a and a thermistor element 40b. The spring plate 40a is a support member having spring elasticity extending toward the inner surface of the fixing rotator 20. The thermistor element 40b as a temperature detecting 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.

[0033] The thermistor 40 is fixedly installed on the film guide 25 at a position approximately at the center of the fixing rotator 20 in the longitudinal direction. Then, the thermistor element 40b is pressed against the inner surface of the fixing rotator 20 by the spring elasticity of the spring plate 40a and held in a contact state. Note that the thermistor 40 may be arranged on the outer peripheral side of the fixing rotator 20.

[0034] The current sensor 30 that constitutes a conduction monitoring device for monitoring the circumferential conduction of the conductive layer 20b is arranged at the same position as the thermistor 40 in the longitudinal direction of the fixing device 15. That is, what the current sensor 30 monitors is the conduction of the heating ring 201 at the position where the thermistor element 40b is in contact among the plurality of heating rings 201 that constitute the heat generation pattern of the fixing rotator 20. state.

[0035] (Heating principle) The heating principle of the fixing rotator 20 in the induction heating type fixing device 15 will be described. FIG. 6 is a conceptual diagram showing an instant when the current is increasing in the exciting coil 27 in the direction of arrow I0. The exciting coil 27 is inserted into the fixing rotator 20 and functions as a magnetic field generating means that forms an alternating magnetic field in the rotational axis direction of the fixing rotator 20 by flowing an alternating current, thereby generating an induced current I in the circumferential direction of the fixing rotator 20. Further, the magnetic core 26 guides the magnetic flux lines B (dotted lines in the figure) generated by the exciting coil 27 and functions as a member that forms a magnetic path. In a general induction heating method, magnetic flux lines penetrate through a conductive layer to generate eddy currents, whereas in this embodiment, the magnetic flux lines B loop outside the fixing rotator. That is, the conductive layer 20b mainly generates heat by the induced current induced by the magnetic flux lines that emerge from one longitudinal end of the magnetic core 26, pass outside the conductive layer 20b, and return to the other longitudinal end of the magnetic core 26. By doing so, even if the thickness of the conductive layer is as thin as, for example, 5 μm or less, heat can be efficiently generated.

[0036] When an alternating magnetic field is formed by the exciting coil 27, an induced current I that follows Faraday's law flows through each heating ring 201 of the conductive layer 20b of the fixing rotator 20. Faraday's law states that "when the magnetic field in a circuit is changed, an induced electromotive force that attempts to flow an electric current is generated in the circuit, and the induced electromotive force is proportional to the time change of the magnetic flux that perpendicularly penetrates the circuit."

[0037] Regarding the heating ring 201c located at the central portion in the longitudinal direction of the magnetic core 26 shown in FIG. 6, consider the induced current I flowing through the heating ring 201c when a high-frequency alternating current is passed through the exciting coil 27. When a high-frequency alternating current is passed, an alternating magnetic field is formed inside the magnetic core 26. At that time, the induced electromotive force acting on the heating ring 201c is proportional to the time change of the magnetic flux that perpendicularly penetrates the inside of the heating ring 201c according to the following mathematical formula.

Equation

[0038] Due to this induced electromotive force V, an induced current I, which is a circulating current that circulates through the heating ring 201c, flows, and the heating ring 201c generates heat due to the Joule heat generated along with the induced current I. However, when the heating ring 201c is disconnected, the induced current I does not flow, and the heating ring 201c does not generate heat.

[0039] (1) Schematic configuration of the fixing rotator The details of the fixing rotator of the present embodiment will be described with reference to the drawings. The fixing rotator according to one aspect of the present disclosure can be a rotatable member having, for example, an endless belt shape. FIG. 7 is a cross-sectional view in the circumferential direction of the fixing rotator. As shown in FIG. 7, the fixing rotator includes a cylindrical base material 20a, a conductive layer 20b on the outer peripheral surface of the base material 20a, and a resin layer 20e that covers the conductive layer. An elastic layer 20c or a surface layer (release layer) 20d can be provided on the resin layer 20e as needed, and an adhesive layer 20f can also be provided between the elastic layer 20c and the surface layer 20d.

[0040] (2) Base material The material of the base material 20a is not particularly limited, but the base material 20a preferably contains a resin. When the belt is used in a fixing device using an electromagnetic induction method, the base material 20a is preferably a layer that has little change in physical properties and maintains high strength in a state where the conductive layer generates heat. For this reason, the base material 20a preferably contains a heat-resistant resin as a main component and is preferably composed of a heat-resistant resin.

[0041] The base material 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 that is most contained among the components constituting the object (here, the base material). In addition, the modifications in the modified polyimide and modified polyamideimide include siloxane modification, carbonate modification, fluorine modification, urethane modification, triazine modification, phenol modification, and the like.

[0042] A filler may be incorporated into the base material 20a to improve heat insulation and strength. The shape of the base material can be appropriately selected according to the shape of the fixing rotating body, and can be various shapes such as an endless belt shape, a hollow cylindrical shape, a film shape, and the like.

[0043] In the case of the fixing belt, the thickness of the base material 20a is preferably, for example, 10 to 100 μm, and more preferably 20 to 60 μm. By setting the thickness of the base material 20a within the above range, high levels of both strength and flexibility can be achieved simultaneously. Also, on the surface of the base material 20a on the side opposite to the side facing the conductive layer 20b, for example, a layer for preventing wear of the inner peripheral surface of the fixing belt when the inner peripheral surface of the fixing belt comes into contact with other members, or a layer for improving the slidability with other members can be provided.

[0044] In the fixing device, other members such as sliding members are arranged on the inner surface of the base material 20a, and the sliding load is large. Therefore, in order to ensure the durability of the base material, the base material 20a has at least one solid layer. By having at least one solid layer in the base material 20a, the durability of the base material is improved. It is preferable that the base material 20a is a solid layer. It is also one of the preferred embodiments that the solid layer is located on the inner peripheral surface of the base material. The solid layer is a layer that substantially does not contain pores in the layer. "Substantially does not contain pores" means that pores are not intentionally provided, but the presence of pores inevitably mixed in such as scratches, cracks, and chips in the material is allowed. The presence or absence of pores can be observed by observing the cross-section of the base material. The cross-section observation of the base material can be performed in the same manner as the cross-section observation of the resin layer described later. Making the solid layer on the base material 20a can be achieved by using a cylindrical base material formed in a state substantially free of voids. For example, in thermosetting resins such as polyimide and polyamideimide, when the solvent in the coating film volatilizes during molding, it may boil suddenly due to a rapid temperature rise and form voids. Therefore, when volatilizing the solvent in the coating film, it is preferable to set the processing temperature and processing time so that the solvent does not boil suddenly. The solid layer preferably contains a resin. As the resin that the solid layer can contain, the resin that the base material can contain can be used.

[0045] The outer peripheral surface of the base material 20a may be subjected to roughening treatment such as blasting or modification treatment such as ultraviolet rays, plasma, and chemical etching in order to improve the adhesion and wettability with the conductive layer 20b.

[0046] (3) Conductive layer The conductive layer 20b is a layer that generates heat when energized. In the heat generation principle by induction heating using an exciting coil, when an alternating current is supplied to the exciting coil arranged near the fixing rotating body, a magnetic field is induced, and a current is generated in the conductive layer 20b of the fixing rotating body by the magnetic field, and heat is generated by Joule heat. The conductive layer is preferably an electromagnetic induction heating layer.

[0047] As the material of the conductive layer 20b, silver with a low volume resistivity and difficult to oxidize is preferable. That is, the conductive layer 20b preferably contains silver. The conductive layer 20b may contain a metal other than silver to such an extent that the effects of the present disclosure are not impaired. When silver constitutes the conductive layer, the purity of silver constituting the conductive layer is preferably 90% by mass or more, more preferably 99% by mass or more, and particularly preferably 99.9% by mass or more. The upper limit is not particularly limited, and examples include 90 to 100% by mass, 99 to 100% by mass, and 99.9 to 100% by mass.

[0048] In the fixing rotating body, the analysis of the material of the conductive layer, specifically, for example, when the conductive layer contains silver, the purity of silver, etc. can be carried out by the following procedure. Six samples, each with a length of 5 mm, a width of 5 mm, and a thickness equal to the total thickness of the fixing rotating body, are taken from any location on the fixing rotating body. For the six obtained samples, the cross-section in the circumferential direction of the fixing rotating body is exposed using a cross-section polisher (product name: SM09010, manufactured by JEOL Ltd.).

[0049] Subsequently, the exposed cross-section of the conductive layer is observed using a scanning electron microscope (SEM) (product name: JSM-F100, manufactured by JEOL Ltd.), and energy-dispersive X-ray spectroscopy (EDS) analysis of the silver crystal particles in the observation image is performed. The observation conditions are 20,000 times magnification, secondary electron image acquisition mode, and the EDS analysis conditions are an acceleration voltage of 5.0 kV and a working distance of 10 mm. The spatial range for performing the EDS analysis is specified by area, and it is adjusted to select only the silver crystal particles in the observation image. One image is acquired for each sample, and three EDS analyses are performed within one image. By analyzing the purity at a total of 18 locations for the six samples and calculating the arithmetic mean value, the purity of the silver constituting the conductive layer can be obtained.

[0050] The thickness of the conductive layer 20b is preferably 5 μm or less. This is because by setting the thickness to 5 μm or less, the fixing rotating body can be given appropriate flexibility and the heat capacity can be reduced. Furthermore, by setting the thickness to 5 μm or less, the bending resistance performance of the fixing rotating body can be further improved. As shown in Figure 3, the fixing rotating body 20 is rotationally driven while being pressed by the film guide 25 and the pressure roller 21. Each time it makes one rotation, the fixing rotating body 20 is pressurized and deformed at the nip portion N and receives stress. Even when such repeated bending is applied to the fixing rotating body over a long period, by setting the thickness of the conductive layer to 5 μm or less, the conductive layer 20b can be made less likely to cause fatigue failure. This is because when the conductive layer 20b is pressed and deformed along the curved surface shape of the film guide 25, the internal stress acting on the conductive layer 20b becomes smaller as the conductive layer 20b becomes thinner.

[0051] The conductive layer 20b extends in the circumferential direction of the outer peripheral surface of the base material 20a. The conductive layer 20b only needs to be capable of generating heat when energized and may be configured in a predetermined pattern. In particular, as shown in FIG. 4, it is preferable that a plurality of conductive layers 20b formed in a ring shape in the circumferential direction of the fixing rotator are formed in a state of being electrically divided in the rotational axis direction. By adopting such a configuration, it is possible to suppress a local temperature rise when a crack occurs in the conductive layer 20b. On the other hand, when the conductive layer is configured in the above-described pattern, the surface area of the conductive layer 20b will increase. At this time, if the conductive layer is formed of copper, it will be more easily oxidized. However, when silver is used as the material of the conductive layer, oxidation of the conductive layer due to an increase in surface area caused by configuring the conductive layer in a pattern as described above can be prevented.

[0052] The width of the ring of the conductive layer 20b is preferably 100 μm or more, more preferably 200 μm or more, from the viewpoints of manufacturability and heat generation. From the viewpoint of heat generation unevenness, etc., it is preferably 500 μm or less, more preferably 400 μm or less. Examples of the ring width include 100 to 500 μm and 200 to 400 μm.

[0053] The interval between the rings of the conductive layer 20b is preferably 50 μm or more, more preferably 100 μm or more, from the viewpoints of manufacturability and heat generation. From the viewpoint of heat generation unevenness, it is preferably 400 μm or less, more preferably 300 μm or less. Examples of the interval between the rings include 50 to 300 μm and 100 to 300 μm.

[0054] The conductive layer 20b has at least one hole in a cross-sectional view in the direction along the circumferential direction of the base material 20a. The presence of holes in the conductive layer 20b improves the durability due to the effect of improving adhesion by the anchor effect and the effect of improving mechanical strength such as suppressing buckling by the damper effect when forming the resin layer 20e covering the conductive layer 20b.

[0055] The size and number of pores in the conductive layer can be expressed as the porosity. Here, the porosity in the conductive layer is determined as follows.

[0056] (Preparation of Evaluation Sample) First, an evaluation sample is prepared. From the fixing rotator, for example, a sample with a length of 5 mm, a width of 5 mm, and a thickness equal to the total thickness of the fixing rotator is taken one from an arbitrary location on the fixing rotator. For the obtained sample, the circumferential cross-section of the fixing rotator is polished using an ion beam. At this time, the processing position is adjusted so that the circumferential cross-section of the conductive layer is exposed by the polishing process of the ion beam. The method of polishing the cross-section by the ion beam is not particularly limited, but in the present disclosure, a cross-section polisher is used. In the polishing process of the cross-section by the ion beam, the dropout of the filler from the sample and the mixing of the abrasive can be prevented, and a cross-section with few polishing marks can be formed.

[0057] (Observation of Cross-Section of Conductive Layer and Image Processing) The cross-section of the conductive layer obtained by the above method is observed by a scanning electron microscope (SEM) (trade name: JSM-F100, manufactured by JEOL Ltd.), and a cross-sectional image (SEM image) is acquired. The observation conditions are in the backscattered electron image mode at 20,000 times magnification, and the backscattered electron image acquisition conditions are an acceleration voltage of 3.0 kV and a working distance of 3 mm. For the SEM image obtained above, binarization processing is performed so that the crystal particle portion is displayed in white and the portion other than the crystal particles is displayed in black. As a binarization method, for example, the Otsu method can be used. Specifically, first, the backscattered electron image is read by image analysis software (ImageProPlus, manufactured by MediaCybernetics), the image is cut out in a range of 0.5 μm × 0.5 μm at an arbitrary location, and the luminance distribution of this image is obtained. Next, by setting the luminance range of the obtained luminance distribution, binarization for discriminating the crystal particle portion and the portion other than the crystal particles can be performed.

[0058] (Calculation of Porosity) In the binary image obtained by the above procedure, each particle of the metal crystal is represented as a white region. By calculating the area occupied by each of these crystal particles within the image, the porosity can be calculated. Specifically, in the above binary image, the number of pixels constituted by crystal particles is calculated, and the sum total of the number of pixels is computed. By multiplying the sum total of the number of pixels by the area of one pixel (0.15 × 0.15 = 0.0 225 μm 2 ), the area occupied by the crystal particles can be calculated. Since the porosity indicates the ratio of the space not occupied by crystal particles in the conductive layer, it is determined as follows using the area occupied by the crystal particles obtained above. Porosity = {Area of the binary image (0.5 × 0.5 (μm )) - Area occupied by crystal particles (μm 2 ))} ÷ Area of the binary image (0.5 × 0.5 (μm 2 )) × 100 2 The above porosity is determined for 20 arbitrary locations of the binary image of the cross-section of the conductive layer, and the average porosity obtained by finding the arithmetic mean value is taken as the porosity of the conductive layer.

[0059] The porosity of the conductive layer 20b is not particularly limited, but from the viewpoint of achieving good conductivity and durability, it is preferably 10 to 50 area%, and more preferably 17 to 40 area%.

[0060] The method of providing pores in the conductive layer 20b is not particularly limited. For example, after forming a pattern on the conductive layer 20b by a photolithography process, pores are formed by chemical solution etching, or pores are formed using a laser or a focused ion beam. In the present disclosure, in particular, pore formation using a silver nanoparticle material will be described.

[0061] ​First, a paint containing silver nanoparticles with a particle size of about 10 to 50 nm is formed into a film. As a result, the particles are stacked as shown in FIG. 8A. Due to the instability of the surface energy of the nanoparticles, the particles fuse together even at a low firing temperature of about 100 °C, and the film is formed in a state having nano-sized pores as shown in FIG. 8B. The conductive layer 20b is preferably a sintered body of silver nanoparticles.

[0062] Furthermore, the laminate formed with silver nanoparticles is fired (sintered) at a high temperature of about 300 °C. The firing temperature is preferably 280 to 450 °C, 300 to 400 °C. When fired, the nanoparticles further combine with each other, and the pores also combine with each other to minimize the surface energy and grow until they penetrate in the thickness direction as shown in FIG. 8C. As a result, the porosity tends to increase.

[0063] The volume resistivity of the conductive layer is not particularly limited, but for example, 5.0×10 -8 Ω·m or less can be mentioned, and it is preferably 4.0×10 -8 Ω·m or less. By being in this range, the conductivity of the fixing rotator can be made better. The lower limit of the volume resistivity of the conductive layer is not particularly limited, but for example, 1.0×10 -7 ~5.0×10 -8 Ω·m, 5.0×10 -7 ~4.0×10 -8 Ω·m can be mentioned. The volume resistivity can be adjusted by adjusting the porosity of the conductive layer. For example, by increasing the value of the porosity, the volume resistivity of the conductive layer can be increased. Also, by decreasing the value of the porosity, the volume resistivity of the conductive layer can be decreased. Further, when silver nanoink is used as the metal species, the porosity can be adjusted by the firing temperature of the conductive layer. The higher the firing temperature, the larger the porosity can be.

[0064] The volume resistivity of the conductive layer can be measured by resistance measurement (JIS KJ7194) using the four-probe method. In the present disclosure, the volume resistivity is measured using a low-resistance resistivity meter (Loresta-GX MCP-T700, manufactured by Nitto Seiko Analytic).

[0065] (4) Resin layer The fixing rotator has a resin layer 20e that covers the conductive layer 20b. The resin layer 20e protects the conductive layer 20b and has functions of ensuring insulation of the conductive layer 20b and improving strength.

[0066] The resin used for the resin layer 20e is not particularly limited. However, similar to the base material 20a, a resin with little change in physical properties and maintaining high strength in a state where the conductive layer 20b generates heat is preferred. For this reason, the resin layer 20e 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 200°C (preferably less than 250°C).

[0067] The resin layer 20e preferably contains at least one selected from the group consisting of polyimide (PI), polyamideimide (PAI), modified polyimide, and modified polyamideimide. More preferably, it is at least one selected from the group consisting of polyimide and polyamideimide. The modification is the same as that described for the base material 20a.

[0068] The resin layer 20e may contain a heat-conductive filler from the viewpoint of heat transfer. By improving the heat transfer property, the heat generated in the conductive layer 20b can be efficiently transmitted to the outer surface of the fixing rotator.

[0069] The thickness of the resin layer 20e is preferably 10 to 100 μm, and more preferably 20 to 60 μm. From the viewpoint of the bending resistance of the conductive layer 20b, the thickness of the resin layer 20e is preferably substantially equal to the thickness of the base material 20a. By making the thickness of the resin layer 20e substantially equal to the thickness of the base material 20a, when repeatedly bent at the nip portion, the stress applied to the conductive layer 20b can be made in a state without bias. This is because the generation of cracks in the conductive layer 20b can be further suppressed.

[0070] The resin layer 20e has at least one through-hole extending from the surface of the resin layer on the conductive layer side to the other surface of the resin layer. Here, the other surface of the resin layer can also be said to be the surface on the side opposite to the surface facing the base material among the surfaces of the resin layer. As described above, in a special usage environment, the temperature of the end portion of the fixing rotator may be maintained at a temperature higher than the set temperature in the non-paper-passing portion. When the conductive layer has pores, depending on the reaching temperature, the air remaining in the pores expands, and an event of delamination occurring between the conductive layer and the resin layer covering the conductive layer has been observed. When delamination occurs, it irreversibly remains on the fixing rotator as a convex shape (blister), and defects occur in the subsequent fixing image. Therefore, by providing at least one through-hole in the resin layer 20e, even if the air remaining in the pores in the conductive layer expands, the expanded air can move to the outer peripheral surface side of the fixing rotator, and delamination can be suppressed. As a result, even in a special usage environment, blisters do not occur in the overheated portion, and it becomes possible to suppress the occurrence of image defects over a long period.

[0071] Examples of the method for providing the above through-hole in the resin layer include the following method. When the resin layer contains at least one selected from the group consisting of polyimide (PI), polyamideimide (PAI), modified polyimide, and modified polyamideimide, a mixed solvent containing an ether-based solvent and an amide-based solvent having a lower boiling point than this ether-based solvent is used as the solvent used in the polyimide precursor solution for forming the resin layer. By using solvents with different boiling points in this way, the resin layer is likely to have through-holes. By adjusting the types and ratios of the amide-based solvent and the ether-based solvent in the mixed solvent, drying conditions, etc., the resin layer is likely to have through-holes. In the present invention, investigations were conducted using a commercially available polyimide precursor solution using a mixed solvent.

[0072] The structure of the through-hole possessed by the resin layer can be confirmed by the following method. First, cut the resin layer covering the conductive layer and observe the cross-section with a scanning electron microscope (SEM) (Figure 1). While cutting the obtained cross-section, for example, with a FIB (focused ion beam), observe multiple cross-sections and synthesize the obtained two-dimensional cross-sectional images to obtain a three-dimensional cross-sectional image of the resin layer. In the examples of the present disclosure, specifically, a three-dimensional cross-sectional image was obtained using a FIB-SEM AmberX manufactured by TESCAN. For the obtained image, extract the resin part and the pore part to obtain the distribution state of the pores. Specifically, use the analysis mode XPoreNetworkModelingExtension of the image analysis software AVIZO manufactured by Thermo Fisher Scientific to confirm the presence or absence of through-holes. Load the obtained three-dimensional cross-sectional image, cut out the image with a width of 100 μm and a depth direction of 50 μm over the entire thickness of the resin layer as the analysis processing range, and perform quantitative analysis on the pores in this image. Model the distribution state of the pores into a three-dimensional structure and analyze the connection between the pores. By confirming the distribution form and the presence or absence of connection between the pores, it is possible to visually determine the presence or absence of through-holes from the surface of the resin layer 20e on the conductive layer side to the other surface of the resin layer for the resin layer 20e.

[0073] (5) Elastic layer The fixing rotating body may have an elastic layer 20c on the outer surface of the resin layer 20e. The elastic layer 20c is a layer for imparting flexibility to the fixing rotating body in order to secure a fixing nip in the fixing device. When the fixing rotating body is used as a heating member in contact with the toner on the paper, the elastic layer 20c also functions as a layer for imparting flexibility such 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 composed of a cured product obtained by curing a composition containing at least a raw material of rubber (base polymer, crosslinking agent, etc.) and a thermally conductive filler. Further, from the viewpoint of allowing the air remaining in the pores in the conductive layer to permeate to the outer peripheral surface side of the fixing rotating body when the air expands, it is preferable to select a rubber having a high gas permeability.

[0074] From the viewpoint of exhibiting the functions of the elastic layer 20c described above, the elastic layer 20c is preferably composed of a silicone rubber cured product containing thermally conductive particles, and more preferably composed of a cured product of an addition-curable silicone rubber composition. Since the cured product of the silicone rubber composition has a high gas permeability, it is easy to suppress delamination for the above reasons. The silicone rubber composition can contain, for example, thermally conductive particles, a base polymer, a crosslinking agent and a catalyst, and, if necessary, additives. Since the silicone rubber composition is often in a liquid state, the thermally conductive filler is easily dispersed, and it is easy to adjust the elasticity of the elastic layer 20c to be produced by adjusting the degree of crosslinking according to the type and addition amount of the thermally conductive filler.

[0075] The matrix is responsible for the function of exhibiting elasticity in the elastic layer 20c. From the viewpoint of exhibiting the functions of the elastic layer 20c described above, the matrix preferably includes silicone rubber. Silicone rubber has high heat resistance that can maintain flexibility even in an environment where the temperature reaches about 240°C in the non-paper-passing area, which is preferable. As the silicone rubber, for example, a cured product of an addition-curable liquid silicone rubber composition described later can be used. The elastic layer 20c can be formed by applying and heating a liquid silicone rubber composition by a known method.

[0076] The liquid silicone rubber composition usually 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): a catalyst; Component (d): a thermal conductivity filler Hereinafter, each component will be described.

[0077] Component (a) The organopolysiloxane having an unsaturated aliphatic group is an organopolysiloxane having an unsaturated aliphatic group such as a vinyl group, and examples thereof include those represented by the following formulas (1) and (2).

Chemical formula

[0078] In formula (1), m 1 represents an integer of 0 or more, and n 1 represents an integer of 3 or more. Also, in formula (1), R 1 each independently represents a monovalent unsubstituted or substituted hydrocarbon group not containing an unsaturated aliphatic group, provided that at least one of R 1 represents a methyl group, and R 2 each independently represents an unsaturated aliphatic group.

Chemical formula

[0079] In formula (2), n 2 represents a positive integer, and R 3 each independently represents a monovalent unsubstituted or substituted hydrocarbon group not containing an unsaturated aliphatic group, provided that at least one of R 3 represents a methyl group, and R 4 each independently represents an unsaturated aliphatic group.

[0080] In formulas (1) and (2), examples of the monovalent unsubstituted or substituted hydrocarbon group not containing an unsaturated aliphatic group that R 1 and R 3 can represent include, for example, the following groups. · Unsubstituted hydrocarbon group An alkyl group (e.g., methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group). An aryl group (e.g., phenyl group). · Substituted hydrocarbon group Substituted alkyl group (e.g., chloromethyl group, 3-chloropropyl group, 3,3,3-trifluoropropyl group, 3-cyanopropyl group, 3-methoxypropyl group).

[0081] The organopolysiloxanes represented by formulas (1) and (2) have at least one methyl group directly bonded to the silicon atoms forming the chain structure. However, since they are easy to synthesize and handle, it is preferable that 50% or more of each of R 1 and R 3 is a methyl group, and it is more preferable that all of R 1 and R 3 are methyl groups.

[0082] Also, as the unsaturated aliphatic groups that R 2 and R 4 in formulas (1) and (2) can represent, for example, the following groups can be mentioned. That is, as the unsaturated aliphatic group, a vinyl group, an allyl group, a 3-butenyl group, a 4-pentenyl group, a 5-hexenyl group, etc. can be mentioned. Among these groups, since they are easy to synthesize and handle, inexpensive, and the cross-linking reaction can be easily carried out, it is preferable that both R 2 and R 4 are vinyl groups.

[0083] As component (a), from the viewpoint of moldability, the viscosity is preferably 1000 mm 2 / s or more and 50000 mm 2 / s or less. If it is lower than 1000 mm 2 / s, it becomes difficult to adjust to the hardness required for the elastic layer 20c, and if it is higher than 50000 mm 2 / s, the viscosity of the composition becomes too high and coating becomes difficult. The viscosity (kinematic viscosity) can be measured using a capillary viscometer, a rotational viscometer, etc. based on JIS Z 8803:2011.

[0084] The blending amount of component (a) is preferably 55% by volume or more and 65% by volume or less from the viewpoint of durability and from the viewpoint of heat conductivity, based on the liquid silicone rubber composition used for forming the elastic layer 20c.

[0085] Component (b) The organopolysiloxane having active hydrogen bonded to silicon reacts with the unsaturated aliphatic group of component (a) by the action of a catalyst and functions as a crosslinking agent for forming a cured silicone rubber. As component (b), any organopolysiloxane having an Si-H bond can be used. In particular, from the viewpoint of reactivity with the unsaturated aliphatic group of component (a), those having an average of 3 or more hydrogen atoms bonded to silicon atoms in one molecule are preferably used.

[0086] Specific examples of component (b) include, for example, the linear organopolysiloxane represented by the following formula (3) and the cyclic organopolysiloxane represented by the following formula (4).

Chemical formula

[0087] In formula (3), m 2 represents an integer of 0 or more, n 3 represents an integer of 3 or more, and R 5 each independently represents a monovalent unsubstituted or substituted hydrocarbon group not containing an unsaturated aliphatic group.

Chemical formula

[0088] In formula (4), m 3 represents an integer of 0 or more, n 4 represents an integer of 3 or more, and R 6 each independently represents a monovalent unsubstituted or substituted hydrocarbon group not containing an unsaturated aliphatic group.

[0089] R in formulas (3) and (4) 5and R 6 Examples of the monovalent unsubstituted or substituted hydrocarbon group that does not contain an unsaturated aliphatic group that can be represented by [are, for example, R in the above-described formula (1). 1 The same groups as those of [can be mentioned. Among these, since synthesis and handling are easy and excellent heat resistance can be easily obtained, R 5 and R 6 It is preferable that 50% or more of each is a methyl group, and it is more preferable that all of R 5 and R 6 are methyl groups.

[0090] Component (c) Examples of the catalyst used for forming the silicone rubber include, for example, a hydrosilylation catalyst for promoting the curing reaction. As the hydrosilylation catalyst, for example, known substances such as platinum compounds and rhodium compounds can be used. The blending amount of the catalyst can be set as appropriate and is not particularly limited.

[0091] Component (d) Examples of the thermally conductive filler include metals, metal compounds, and carbon fibers. A highly thermally conductive filler is more preferable, and specific examples thereof include the following materials. Metal silicon (Si), silicon carbide (SiC), silicon nitride (Si3N4), boron nitride (BN), aluminum nitride (AlN), alumina (Al2O3), zinc oxide (ZnO), magnesium oxide (MgO), silica (SiO2), copper (Cu), aluminum (Al), silver (Ag), iron (Fe), nickel (Ni), vapor-grown carbon fiber, PAN-based (polyacrylonitrile) carbon fiber, pitch-based carbon fiber.

[0092] These fillers can be used alone or in combination of two or more. The average particle size of the filler is preferably 1 μm or more and 50 μm or less from the viewpoints of handling and dispersibility. As for the shape of the filler, spherical, pulverized, acicular, plate-like, and whisker-like shapes are used. In particular, from the viewpoint of dispersibility, spherical fillers are preferred. Furthermore, at least one of a reinforcing filler, a heat-resistant filler, and a coloring filler may be added.

[0093] (6) Adhesive layer The fixing rotator may have an adhesive layer 20f for adhering the surface layer 20d described later to the outer surface of the elastic layer 20c. 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 ones and is not particularly limited. However, from the viewpoint of allowing the air remaining in the pores in the conductive layer to permeate to the outer peripheral surface side of the fixing rotator when the air expands, it is preferable to select an adhesive with a high gas permeability. Also, from the viewpoints of ease of handling and ease of gas permeation, it is preferable to use an addition-curing type silicone rubber containing a self-adhesive component. This adhesive can contain, for example, a self-adhesive component, an organopolysiloxane having a plurality of unsaturated aliphatic groups represented by vinyl groups in the molecular chain, a hydrogen organopolysiloxane, and a platinum compound as a crosslinking catalyst. By curing the adhesive applied to the surface of the elastic layer 20c by an addition reaction, an adhesive layer 20f for adhering the surface layer 20d to the elastic layer 20c can be formed.

[0094] Examples of the above self-adhesive component can include the following. · A silane having at least one, preferably two or more functional groups selected from the group consisting of alkenyl groups such as vinyl groups, (meth)acryloxy groups, hydrosilyl groups (SiH groups), epoxy groups, alkoxysilyl groups, carbonyl groups, and phenyl groups. · An organosilicon compound such as a cyclic or linear siloxane having 2 to 30, preferably 4 to 20 silicon atoms. · A non-silicon-based (i.e., not containing a silicon atom in the molecule) organic compound that may contain an oxygen atom in the molecule. However, it contains 1 to 4, preferably 1 to 2, aromatic rings such as a phenylene structure with a valence of 1 or more and 4 or less, preferably 2 or more and 4 or less, in one molecule. And it contains at least 1, preferably 2 to 4, functional groups (e.g., alkenyl group, (meth)acryloxy group) that can contribute to the hydrosilylation addition reaction in one molecule.

[0095] The above self-adhesive component may be used alone or in combination of two or more. Also, in the adhesive, from the viewpoints of viscosity adjustment and heat resistance ensuring, a filler component can be added within the scope conforming to the gist of the present disclosure. Examples of the filler component include the following. · Silica, alumina, iron oxide, cerium oxide, cerium hydroxide, carbon black, etc.

[0096] The blending amount of each component contained in the adhesive is not particularly limited and can be set as appropriate. Such an addition-curing type silicone rubber adhesive is also commercially available and can be easily obtained. It is preferable that the thickness of the adhesive layer 20f is 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 aspect is used as a heating belt in a heat fixing device, the thermal resistance can be easily set small, and the heat from the inner surface side can be efficiently transmitted to the recording medium.

[0097] (7) Surface layer The fixing rotating body may have a surface layer 20d. The surface layer 20d preferably contains a fluororesin in order to exhibit the function as a release layer for preventing the adhesion of toner to the outer surface of the fixing rotating body. From the viewpoint of allowing the air remaining in the pores in the conductive layer to permeate to the outer peripheral surface side of the fixing rotating body when the air expands, it is preferable to select a material with a high gas permeability. For the formation of the surface layer 20d, for example, a resin formed into a tube shape as exemplified below may be used, or a resin dispersion may be coated to form the surface layer 20d. · 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, toner releasability, and gas permeability.

[0098] The thickness of the surface layer 20d is preferably 10 μm or more and 50 μm or less. By setting the thickness of the surface layer 20d within this range, it is easy to maintain an appropriate surface hardness of the fixing rotator.

[0099] As described above, according to one aspect of the present disclosure, a fixing device in which a fixing rotator is disposed is provided. Therefore, it is possible to provide a fixing device in which a fixing rotator having excellent durability is disposed.

Examples

[0100] Hereinafter, the present disclosure will be described in more detail using examples, but the present disclosure is not limited to these examples.

[0101] [Example 1] A release treatment was performed on the surface of a cylindrical stainless steel mold having an outer diameter of 30 mm, and a commercially available polyimide precursor solution (U varnish S, manufactured by Ube Industries, Ltd.) was applied by an immersion method to form a coating film. Next, this coating film was dried at 140 ° C. for 30 minutes to volatilize the solvent in the coating film, and then fired at 200 ° C. for 30 minutes and 400 ° C. for 30 minutes for imidization to form a polyimide film (base material 20a) having a film thickness of 40 μm and a length of 300 mm. Next, a ring pattern was formed on this polyimide film by an inkjet method using silver nanoparticle-containing ink (DNS169I, manufactured by Daicel Corporation) so as to have a width of 300 μm and an interval of 200 μm. Then, firing was performed at 300 ° C. for 30 minutes to form a conductive layer 20b having a film thickness of 2 μm.

[0102] Next, a commercially available polyimide precursor solution (U Imide BP-BM, manufactured by Unitika Ltd.) was spin-coated over the entire surface of the conductive layer 20b, and then baked at 200°C for 30 minutes and at 400°C for 30 minutes to imidize it, thereby forming a resin layer 20e with a film thickness of 50 μm. Next, a primer (trade name: DY39-051A / B, manufactured by Dow Corning Toray Co., Ltd.) was applied approximately uniformly to the outer peripheral surface of the resin layer 20e so that the dry weight was 20 mg. After drying the solvent, baking treatment was performed in an electric furnace set at 160°C for 30 minutes. On this primer, a silicone rubber composition layer with a thickness of 250 μm was formed by the spin coating method. After primary crosslinking at 160°C for 1 minute, secondary crosslinking was performed at 200°C for 30 minutes to form an elastic layer 20c.

[0103] The following silicone rubber composition was used. As the organopolysiloxane having an alkenyl group as component (a), vinylated polydimethylsiloxane (trade name: DMS-V41, manufactured by Gelest Inc., number average molecular weight 68000 (polystyrene conversion), molar equivalent of vinyl group 0.04 mmol / g) having at least 2 or more vinyl groups in one molecule was prepared. Also, as the organopolysiloxane having an Si-H group as component (b), methylhydrogenpolysiloxane (trade name: HMS-301, manufactured by Gelest Inc., number average molecular weight 1300 (polystyrene conversion), molar equivalent of Si-H group 3.60 mmol / g) having at least 2 or more Si-H groups in one molecule was prepared. 0.5 part by weight of component (b) was added to 100 parts by weight of component (a) and mixed well to obtain an addition-curable silicone rubber stock solution. Furthermore, a catalytic amount of a trace amount of a catalyst for addition-curing reaction (platinum catalyst: platinum carbonyl cyclovinylmethylsiloxane complex) and an inhibitor were added and mixed well. To this addition-curing type silicone rubber stock solution, high-purity spherical alumina (product name: ARNA BEADS CB-A10S; manufactured by Showa Titanium Co., Ltd.) was blended and kneaded as the component (d) heat conductive filler so as to have a volume ratio of 45% based on the elastic layer, thereby obtaining an addition-curing type silicone rubber composition having a JIS K 6253A compliant durometer hardness of 10° after curing.

[0104] Next, an addition-curing type silicone rubber adhesive (product name: SE1819CV A / B, manufactured by Dow Corning Toray Co., Ltd.) for forming the adhesive layer 20f was applied substantially uniformly onto the obtained elastic layer 20c so as to have a thickness of approximately 20 μm. A fluororesin tube (product name: NSE, manufactured by Gunze, Ltd.) having an inner diameter of 29 mm and a thickness of 50 μm for forming the surface layer 20d was laminated while expanding its diameter. Thereafter, by uniformly handling the belt surface from above the fluororesin tube, the excess adhesive was squeezed out from between the elastic layer 20c and the fluororesin tube so as to be thinned to about 5 μm. Next, it was heated at 200° C. for 30 minutes to cure the adhesive, thereby fixing the fluororesin tube onto the elastic layer 20c. Finally, both ends were cut so as to have a length of 240 mm, thereby obtaining a rotating body for fixing.

[0105] [Example 2] A rotating body for fixing was produced in the same manner as in Example 1 except that the firing temperature of the conductive layer 20b was 250° C.

[0106] [Example 3] A rotating body for fixing was produced in the same manner as in Example 1 except that the firing temperature of the conductive layer 20b was 200° C.

[0107] [Example 4] The base material 20a and the conductive layer 20b were prepared in the same manner as in Example 1. Next, polyethylene glycol dimethyl ether having a weight average molecular weight of 500 was blended in a commercially available polyimide precursor solution (U varnish S, manufactured by Ube Industries, Ltd.) at a ratio of 66 parts by weight with respect to 100 parts by weight of the resin component in the polyimide resin precursor solution, and stirred to obtain a uniform resin solution. After the obtained resin solution was uniformly coated on the conductive layer 20b by ring coating, it was completely dried at 180 °C for 20 minutes to form a film made of a polyimide resin precursor having a microphase separation structure of polyethylene glycol dimethyl ether. Next, it was pressurized to 25 MPa in an atmosphere of 100 °C. Then, while maintaining the pressure, carbon dioxide was injected and exhausted at a gas flow rate of about 5 L / min for 2 hours to extract polyethylene glycol dimethyl ether. Next, it was preheated at 250 °C for 24 hours to extract and remove polyethylene glycol dimethyl ether. Furthermore, it was baked at 400 °C for 2 hours under a vacuum of 1.3 Pa for imidization to form a resin layer 20e with a film thickness of 50 μm. Next, after forming the elastic layer 20c, the adhesive layer 20f, and the surface layer 20d in the same manner as in Example 1, finally, both ends were cut so that the length became 240 mm to obtain a fixing rotator.

[0108] [Example 5] A fixing rotator was produced in the same manner as in Example 1, except that the material of the base material 20a was a polyamideimide solution (VYLOMAX HR-16NN, manufactured by Toyobo Co., Ltd.), which was uniformly coated on the entire surface by ring coating and then baked at 200 °C for 30 minutes to form a base material 20a with a film thickness of 60 μm.

[0109] [Comparative Example 1] A fixing rotator was produced in the same manner as in Example 1, except that the resin layer 20e was formed using a polyimide precursor solution (U Varnish S, manufactured by Ube Industries, Ltd.).

[0110] [Comparative Example 2] A fixing rotator was produced in the same manner as in Comparative Example 1, except that the thickness of the resin layer 20e was formed to be 40 μm.

[0111] [Comparative Example 3] A fixing rotator was produced in the same manner as in Example 3, except that the resin layer 20e was formed using a polyimide precursor solution (U Varnish S, manufactured by Ube Industries, Ltd.).

[0112] [Comparative Example 4] The base material 20a was formed using a polyimide precursor solution (U-imide BP-BM, manufactured by Unitika Ltd.), and a fixing rotator was produced in the same manner as in Comparative Example 1 except that the thickness of the base material 20a and the thickness of the resin layer 20e were changed to the values described in Table 1.

[0113] [Comparative Example 5] The material of the base material 20a was formed using a polyimide precursor solution (U-imide BP-BM, manufactured by Unitika Ltd.), and a fixing rotator was produced in the same manner as in Example 1 except that the thickness of the base material 20a was changed to the value described in Table 1.

[0114] (Evaluation: Cross-sectional Observation) For Examples 1 to 5 and Comparative Examples 1 to 5, the cross-section of the conductive layer 20b was observed by the above-described method, and the porosity was calculated. The results are shown in Table 1.

[0115] (Evaluation: Presence or Absence of Communication Holes) For Examples 1 to 5 and Comparative Examples 1 to 5, the cross-sections of the base material 20a and the resin layer 20e were observed by the above-described method, and the presence or absence of voids in the base material 20a and the presence or absence of communication holes in the resin layer 20e were confirmed. When the base material 20a substantially contained no voids, it was determined as "Yes" for the solid layer, and when the base material 20a substantially contained voids, it was determined as "No" for the solid layer. The evaluation results are shown in Table 1.

[0116] (Evaluation: High-temperature Storage) To confirm the effects of the present disclosure, the fixing rotators obtained in Examples 1 to 5 and Comparative Examples 1 to 5 were stored at 240°C for 10 hours. The storage temperature was set from the over-temperature that is assumed in the non-paper-passing part under a special use environment (when continuously printing small sizes) when the fixing rotator is actually incorporated into a fixing device and used. After high-temperature storage, the surface of each fixing rotator was visually observed, and the number of defective portions (blister portions) deformed into a convex shape was counted.

[0117] (Evaluation: Actual Machine Durability Test) Regarding the fixing rotors of Examples 1 to 5 and Comparative Examples 1 to 5, after the high-temperature storage, each fixing rotor was incorporated into a fixing device, and this fixing device was mounted on a laser printer to check for the presence or absence of image defects. As the laser printer, Satera LBP961Ci (trade name) manufactured by Canon Marketing Japan was used. The case where no image defect occurred was designated as "A", and the case where image defects occurred or member breakage might occur was designated as "B".

Table 1

[0118] From the results in Table 1, in the heating rotor having pores in the conductive layer, even if overheating points occur in a special use environment, by having a resin layer with through-holes that covers the conductive layer, deformation of the member can be suppressed and the occurrence of image defects can be suppressed. Even if overheating points occur in a special use environment in the heating rotor having pores in the conductive layer, by having a resin layer with through-holes that covers the conductive layer, deformation of the member can be suppressed and the occurrence of image defects can be suppressed.

[0119] The present disclosure relates to the following configurations. (Configuration 1) A fixing rotor, The fixing rotor includes a cylindrical base material, a conductive layer on the outer peripheral surface of the base material, and a resin layer that covers the conductive layer, The base material has at least one solid layer, The conductive layer extends in the circumferential direction of the base material, and the conductive layer has at least one pore in a cross-sectional view in a direction along the circumferential direction of the base material, The resin layer has at least one through-hole extending from the surface of the resin layer on the conductive layer side to the other surface of the resin layer. The fixing rotor is characterized by this. (Configuration 2) The fixing rotor according to Configuration 1, wherein the conductive layer is an electromagnetic induction heating layer. (Configuration 3) The fixing rotor according to Configuration 1 or 2, wherein the conductive layer is a sintered body of silver nanoparticles. (Configuration 4) The fixing rotor according to any one of Configurations 1 to 3, wherein the porosity of the conductive layer is 10 to 50 area%. (Configuration 5) The volume resistivity of the conductive layer is 4.0×10 -8 Ω·m or less, and the rotating body for fixing according to any one of Configurations 1 to 4. (Configuration 6) The rotating body for fixing according to any one of Configurations 1 to 5, and an induction heating device that generates heat for the rotating body for fixing by induction heating, and a fixing device characterized by comprising the same. (Configuration 7) An electrophotographic image forming apparatus, wherein the electrophotographic image forming apparatus includes an image carrier that supports a toner image, a transfer device that transfers the toner image to a recording material, a fixing device that fixes the transferred toner image to the recording material, and is provided with and the fixing device is the fixing device according to Configuration 6, and an electrophotographic image forming apparatus characterized by this.

Industrial Applicability

[0120] As described above, according to the present disclosure, a rotating body for fixing excellent in durability can be obtained even in a special environment such as continuously printing small-sized paper.

Explanation of Signs

[0121] 1 Image forming apparatus, 15 Fixing device, 20 Rotating body for fixing, 20a Base material, 20b Conductive layer, 20c Elastic layer, 20d Surface layer, 20e Resin layer, 20f Adhesive layer, 21 Pressing roller

Claims

1. A rotating body for fixing, The rotating body for fixing has a cylindrical base material, a conductive layer on the outer peripheral surface of the base material, and a resin layer covering the conductive layer, The base material has at least one solid layer, The conductive layer extends in the circumferential direction of the base material, and the conductive layer has at least one hole in a cross-sectional view in a direction along the circumferential direction of the base material, The resin layer has at least one communication hole extending from the surface of the resin layer on the conductive layer side to the other surface of the resin layer. The rotating body for fixing is characterized by this.

2. The rotating body for fixing according to claim 1, wherein the conductive layer is an electromagnetic induction heating layer.

3. The rotating body for fixing according to claim 1, wherein the conductive layer is a sintered body of silver nanoparticles.

4. The rotating body for fixing according to claim 1, wherein the porosity of the conductive layer is 10 to 50 area%.

5. The volume resistivity of the conductive layer is 4.0×10 －８ Ω·m or less. The rotating body for fixing according to claim 1.

6. A fixing device comprising the rotating body for fixing according to any one of claims 1 to 5, and an induction heating device for generating heat by induction heating of the rotating body for fixing.

7. An electrophotographic image forming apparatus, The electrophotographic image forming apparatus, has an image carrier for carrying a toner image, a transfer device for transferring the toner image to a recording material, a fixing device for fixing the transferred toner image to the recording material, and is provided with, The fixing device is the fixing device according to claim 6. The electrophotographic image forming apparatus is characterized by this.

Images