Fixing device

Abstract

To provide a fixing device that prevents shaving of a slide sheet to reduce shortening of the life of the slide sheet.SOLUTION: A fixing device comprises: a first rotating body; a second rotating body; a pressure member that urges the first rotating body against the second rotating body inside the first rotating body; and a fixing slide sheet that is interposed between the pressure member and the first rotating body and slides with the first rotating body. The fixing slide sheet includes resin. When the Vickers hardness of an inner peripheral surface of the first rotating body is defined as HVA, and the Vickers harness of a surface of the fixing slide sheet facing the first rotating body as HVB, HVA>HVB is established. The fixing slide sheet is provided with a plurality of convex parts in a circumferential direction periodically on the surface facing the inner peripheral surface of the first rotating body. The arithmetic average roughness Ra of the inner peripheral surface of the first rotating body is 0.10 μm or more and 0.25 or less. The width of in the circumferential direction of the convex parts on the fixing slide sheet is larger than the average interval Rsm of irregularities on the inner peripheral surface of the first rotating body.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to a fixing device used in an image forming apparatus. [Background technology]

[0002] In image forming apparatuses such as electrophotographic apparatuses and electrostatic recording apparatuses, an unfixed toner image is formed on a recording material (sheet), and then the toner image is heated and pressed by a fixing device to fix the image. The fixing device employs a roller fixing method in which a pressure roller is pressed against a fixing roller having an internal heater to form a fixing nip and fix the image. In order to achieve high gloss images and high speed image formation, it is preferable to lengthen the time the recording material passes through the fixing nip and melt the toner sufficiently. In the case of the roller fixing method, the roller diameter must be increased to achieve this, which leads to a larger fixing device.

[0003] Patent Document 1 discloses a belt fixing method as a fixing method that can obtain a sufficient nip width (length in the sheet conveying direction) while suppressing the size of the fixing device. The belt fixing method is configured to provide a fixing belt and a pressure belt that face each other, and fix the sheet while sandwiching and conveying it between these two belts. This provides a sufficient nip width compared to the conventional method. In the belt fixing method, a pressure applying member is required to obtain sufficient pressure at the fixing nip. In order to obtain a wide fixing nip without increasing the size of the fixing device, it is effective to use a pad-shaped pressure applying member (hereinafter, simply referred to as a "pad"). However, the pad rubs against the inner peripheral surface of the belt, and it is required to reduce the sliding resistance between the inner peripheral surface of the belt and the pad.

[0004] Patent Document 2 discloses a fixing device in which a low-friction sheet is interposed between the inner circumferential surface of the belt and a pad, and the low-friction sheet is provided with embossed irregularities to reduce the contact area between the low-friction sheet and the endless belt, thereby preventing wear and reducing sliding resistance. Patent Document 3 discloses a fixing device in which the roughness of the sliding pad is reduced to reduce sliding resistance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2004-341346 A [Patent Document 2] JP 2002-148970 A [Patent Document 3] JP 2007-079034 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, depending on the combination of the roughened inner peripheral surface of the fixing belt and the surface shape of the sliding sheet, the sliding sheet may be gradually worn away, shortening the life of the fixing device. At least one aspect of the present disclosure is directed to providing a fixing device with even greater durability. [Means for solving the problem]

[0007] According to at least one aspect of the present disclosure, a first rotating body having a surface layer, a base layer, and an inner sliding layer; a second rotating body having a surface layer and a base layer; a pressure member disposed inside the first rotor and configured to bias the first rotor against the second rotor; a fixing sliding sheet interposed between the pressing member and the first rotating body and sliding against the first rotating body; A fixing device comprising: The fixing sliding sheet contains a resin, a Vickers hardness measured on an inner peripheral surface of the first rotating body is defined as HVA, and a Vickers hardness measured on a surface of the fixing sliding sheet facing the first rotating body is defined as HVB, HVA>HVB, the fixing sliding sheet has a plurality of convex portions periodically provided in a circumferential direction on a surface facing the inner circumferential surface of the first rotating body, The arithmetic mean roughness Ra of the inner peripheral surface of the first rotating body is 0.10 μm or more and 0.25 μm or less, There is provided a fixing device in which the circumferential width W of the protrusions of the fixing sliding sheet is larger than the average interval Rsm of the protrusions and recesses on the inner circumferential surface of the first rotating body. Effect of the Invention

[0008] According to at least one aspect of the present disclosure, a fixing device with even higher durability can be obtained. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view of an image forming apparatus according to the present disclosure. [Diagram 2] 2 is a schematic cross-sectional view of a fixing device according to the present disclosure. [Diagram 3] 2 is a schematic diagram of a fixing belt according to the present disclosure. [Figure 4] FIG. 2 is a schematic diagram of a ring coating apparatus according to the present disclosure. [Diagram 5] FIG. 2 is a schematic diagram of a drying device for an inner surface sliding layer in the present disclosure. [Figure 6] FIG. 2 is a schematic cross-sectional view of an inner sliding layer and a fixing sliding sheet in the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] In this disclosure, unless otherwise specified, the description of "XX-YY" representing a numerical range means a numerical range including the lower and upper limits which are the endpoints, and when a numerical range is described in stages, any combination of the upper and lower limits of each numerical range is also disclosed.

[0011] The present inventors have conducted extensive research in order to obtain a fixing device with even higher durability, and have found that a fixing device having the following configuration can achieve the above object well. <Configuration> a first rotating body having a surface layer, a base layer, and an inner sliding layer; a second rotating body having a surface layer and a base layer; a pressure member disposed inside the first rotor and configured to bias the first rotor against the second rotor; a fixing sliding sheet interposed between the pressing member and the first rotating body and sliding against the first rotating body; A fixing device comprising: The fixing sliding sheet contains a resin, a Vickers hardness measured on an inner peripheral surface of the first rotating body is defined as HVA, and a Vickers hardness measured on a surface of the fixing sliding sheet facing the first rotating body is defined as HVB, HVA>HVB, the fixing sliding sheet has a plurality of convex portions periodically provided in a circumferential direction on a surface facing the inner circumferential surface of the first rotating body, The arithmetic mean roughness Ra of the inner peripheral surface of the first rotating body is 0.10 μm or more and 0.25 μm or less, A fixing device in which a circumferential width W of the protrusions of the fixing sliding sheet is larger than an average interval Rsm of the protrusions and recesses on the inner circumferential surface of the first rotating body.

[0012] The reason why the fixing device having the above configuration exhibits even higher durability is believed to be as follows. That is, the circumferential width W of the convex portions of the fixing sliding sheet is larger than the average interval Rsm of the concave and convex portions of the inner circumferential surface of the first rotating body. This makes it possible to prevent the convex portions of the fixing sliding sheet from entering the concave portions of the inner circumferential surface of the first rotating body in the circumferential direction. As a result, it is possible to prevent the convex portions of the fixing sliding sheet from being scraped and worn by the relatively hard inner circumferential surface of the first rotating body.

[0013] Hereinafter, a fixing device and an image forming apparatus according to an embodiment of the present disclosure will be described with reference to specific examples. Note that the scope of the present disclosure is not limited to the embodiments, and modifications that do not depart from the spirit of the present disclosure are also included in the present disclosure.

[0014] (1) Image forming device 1 is a schematic diagram of an image forming apparatus 1 according to the present embodiment, and is a cross-sectional view taken along a conveying direction D of a sheet S. The image forming apparatus 1 is an intermediate transfer inline type four-color full-color electrophotographic printer (hereinafter referred to as a printer). The image forming apparatus 1 can form an image on a sheet S corresponding to image data (electrical image information) input from an external host device 33 connected to a printer control unit (hereinafter referred to as a CPU) 10 via an interface 32, and output an image formed thereon. The CPU 10 is a control means for controlling the overall operation of the image forming apparatus 1, and transmits and receives various electrical information signals to and from an external host device 33 and a printer operation unit 34. It also processes electrical information signals input from various process devices and sensors, processes command signals to various process devices, controls a predetermined initial sequence, and controls a predetermined image formation sequence. The external host device 33 is a personal computer, a network, an image reader, a facsimile, etc.

[0015] First to fourth image forming units U (UY, UM, UC, UK) are arranged side by side from left to right in the drawing inside the image forming apparatus 1. The image forming units U have the same configuration as each other in terms of the image forming mechanism, except that the colors of the toner, which is the developer contained in each developing device 5, are different: yellow (Y), magenta (M), cyan (C), and black (K). Each image forming unit U has an electrophotographic photosensitive drum (hereinafter simply referred to as drum) 2 as a first image carrier, and a charging roller 3, a laser scanner 4, a developing device 5, a primary transfer roller 6, etc. as process means acting on the drum 2. The drum 2 of each image forming unit U is rotated at a predetermined speed in the counterclockwise direction of the arrow. A Y toner image corresponding to the Y component image of the full color image to be formed is formed on the drum 2 of the first image forming unit UY. An M toner image corresponding to the M component image is formed on the drum 2 of the second image forming unit UM. A C toner image corresponding to the C component image is formed on the drum 2 of the third image forming unit UC. A K toner image corresponding to the K component image is formed on the drum 2 of the fourth image forming unit UK. The process and principle of forming the toner images on the drum 2 of each image forming unit U are well known, so a description thereof will be omitted. An intermediate transfer belt unit (hereinafter simply referred to as unit) 7 is disposed below each image forming section U. This unit 7 has a flexible endless intermediate transfer belt (hereinafter simply referred to as belt) 8 serving as a second image carrier. The belt 8 is stretched around three rollers: a drive roller 11, a tension roller 12, and a secondary transfer opposing roller 13. When the drive roller 11 is driven, the belt 8 is circulated in the clockwise direction indicated by the arrow at a speed corresponding to the rotation speed of the drum 2. A secondary transfer roller 14 abuts against the secondary transfer opposing roller 13 with a predetermined pressing force via the belt 8. The abutting portion between the belt 8 and the secondary transfer roller 14 is the secondary transfer nip portion. The primary transfer roller 6 of each image forming station U is disposed inside the belt 8 and contacts the lower surface of the drum 2 via the belt 8. In each image forming station U, the contact portion between the drum 2 and the belt 8 is the primary transfer nip portion. A predetermined primary transfer bias is applied to the primary transfer roller 6 at a predetermined control timing. The Y color toner, M color toner, C color toner, and K color toner formed on the drum 2 of each image forming unit U are sequentially superimposed and primarily transferred to the surface of the circulating belt 8 at each primary transfer nip portion. As a result, an unfixed full-color toner image of four colors superimposed is synthesized and formed on the belt 8, and is transported to the secondary transfer nip portion.

[0016] Meanwhile, sheets (recording materials) S such as paper stored in the first cassette 15 or the second cassette 16 are separated and fed one by one by the operation of a feeding mechanism (not shown) and sent to a pair of registration rollers 18 through a conveying path 17. The pair of registration rollers 18 temporarily receives the sheet S, and straightens it out if it is skewed. The pair of registration rollers 18 then conveys the sheet S to the secondary transfer nip in synchronization with the toner image on the belt 8. While the sheet S is being nipped and conveyed in the secondary transfer nip portion, a predetermined secondary transfer bias is applied to the secondary transfer roller 14. As a result, the full-color toner images on the belt 8 side are secondary-transferred to the sheet S in a batch in sequence. Then, the sheet S leaving the secondary transfer nip portion is separated from the surface of the belt 8, passes through a conveying path 19, and is introduced into an image fixing device (hereinafter, referred to as a fixing device) 100 as an image processing device. The sheet S is heated and pressurized in the fixing device 100, and the unfixed toner image is fixed as a fixed image. The sheet S leaving the fixing device 100 is conveyed by a pair of discharge rollers 30 to a discharge tray 31 and discharged as a full-color image formed product.

[0017] (2) Fixing device 2 is a schematic cross-sectional view of the main parts of the fixing device according to this embodiment. Here, the term "longitudinal" or "longitudinal direction" for the fixing device or the members constituting the fixing device means a direction parallel to a direction perpendicular to the recording material conveying direction in the plane of the recording material conveying path. The term "front" for the fixing device means the surface on which the recording material is introduced. The term "left" or "right" for the fixing device means the left or right when viewed from the front of the device. The term "belt width" means the belt dimension in a direction perpendicular to the recording material conveying direction (=the dimension in the belt longitudinal direction). The term "recording material width" means the recording material dimension in a direction perpendicular to the recording material conveying direction on the recording material surface. Additionally, the terms "upstream" or "downstream" mean the upstream or downstream with respect to the recording material conveying direction.

[0018] This fixing device includes a fixing belt (fixing means) 20 as a first endless belt (first rotating body), and a pressure belt (pressure means) 21 as a second endless belt (second rotating body).

[0019] The fixing belt 20 has, for example, an inner diameter of 80 mm, a base layer made of nickel with a thickness of 40 μm, an inner sliding layer made of polyimide with a thickness of 15 μm on the inner surface, and an elastic layer with a thickness of 350 μm on the outer periphery of the base layer. A known elastic material can be used as the material of the elastic layer, for example, silicone rubber, fluororubber, etc. In one preferred embodiment, the material of the elastic layer can be silicone rubber. Furthermore, the hardness of the layer can be 20 degrees as measured by a hardness meter conforming to Japanese Industrial Standards (JIS) K6301:1995 (old JIS K6301) (hereinafter, JIS-A hardness), and the thermal conductivity can be 0.8 W / m·K. The thickness of the elastic layer is preferably 100 μm or more in order to prevent uneven gloss caused by the heating surface being unable to follow the unevenness of the recording material or the unevenness of the toner layer when printing an image. If the thickness of the elastic layer is 100 μm or more, the elastic member can function, and the pressure distribution during fixing becomes substantially uniform, so that the unfixed toner of the secondary color can be sufficiently heated and fixed, particularly during full-color image fixing, and unevenness in the gloss of the fixed image can be suppressed. In addition, the toner is sufficiently melted, which improves the color mixing of the toner and allows a high-definition full-color image to be obtained, so this is preferable. There is no particular upper limit on the thickness of the elastic layer, and it is not necessary to make it excessively thick, but it is sufficient to set the appropriate range based on the thermal conductivity and hardness of the material. This deformation of the elastic layer prevents the sheet from wrapping around the fixing belt 20, and provides good separation performance from the belt. Furthermore, on the outer periphery of the elastic layer, a fluororesin (e.g., perfluoroalkoxyalkane (PFA) or polytetrafluoroethylene (PTFE)) surface layer is provided as a surface release layer with a thickness of, for example, 30 μm.

[0020] The pressure belt 21 can be configured in the same manner as the fixing belt, for example, with an inner diameter of 80 mm, a base layer of nickel with a thickness of 40 μm, an inner sliding layer formed of polyimide (PI) with a thickness of 15 μm on the inner surface, and an elastic layer with a thickness of 350 μm provided on the outer periphery of the base layer. A PFA tube, which is a fluororesin surface layer, is provided as a surface release layer with a thickness of, for example, 30 μm on the outer periphery of the elastic layer.

[0021] The fixing belt 20 is stretched by a heating roller 22 and a fixing roller 23, which serve as belt suspension members. The heating roller 22 and the fixing roller 23 are supported by bearings between the left and right side plates (not shown) of the device so as to be freely rotatable. The heating roller 22 is, for example, a hollow iron roller having an outer diameter of 20 mm, an inner diameter of 18 mm, and a thickness of 1 mm, and has a halogen heater 22a disposed therein as a heating means. The heating roller 22 also functions as a tension roller that applies tension to the fixing belt 20.

[0022] The fixing roller 23 may be, for example, an elastic roller having an outer diameter of 20 mm and an elastic layer provided around a core metal made of an iron alloy having a diameter of 18 mm. The fixing roller 23 is driven as a driving roller by inputting a driving force from a driving source (motor) M via a driving gear train (not shown), and is rotated at a predetermined speed in the clockwise direction of the arrow. By using such an elastic roller for the fixing roller 23, the driving force input to the fixing roller 23 can be transmitted well to the fixing belt 20, and a fixing nip can be formed to ensure separation of the recording material from the fixing belt 20. The elastic layer may include, for example, silicone rubber, and has, for example, a JIS-A hardness of 15 degrees and a thermal conductivity of, for example, 0.8 W / m·K. By providing such an elastic layer, the warm-up time can be shortened. When the fixing roller 23 is rotated, the fixing belt 20 rotates together with the fixing roller 23 due to friction between the silicone rubber surface of the fixing roller 23 and the polyimide layer on the inner surface of the fixing belt 20 .

[0023] The pressure belt 21 is stretched by a tension roller 25 and a pressure roller 26, which serve as belt suspension members. The tension roller 25 and the pressure roller 26 are supported by bearings between the left and right side plates (not shown) of the device so as to be freely rotatable. The tension roller 25 is, for example, an iron alloy core having an outer diameter of 20 mm and a diameter of 16 mm, and is provided with a silicone sponge layer to reduce the thermal conductivity and to reduce the heat conduction from the pressure belt 21. The pressure roller 26 is, for example, a rigid roller with low sliding properties that is made of an iron alloy, has an outer diameter of 20 mm, an inner diameter of 16 mm, and a thickness of 2 mm.

[0024] Here, in order to form a fixing nip N as an image heating nip between the fixing belt 20 and the pressure belt 21, the pressure roller 26 is pressed toward the fixing roller 23 with a predetermined pressure force in the direction of arrow F by a pressure mechanism (not shown) at both left and right ends of the rotating shaft.

[0025] Also, in order to obtain a wide fixing nip N without increasing the size of the fixing device, a pressure pad (pressure member) is adopted. That is, a fixing pad 24 is a first pressure pad that presses (urges) the fixing belt 20 toward the pressure belt 21, and a pressure pad 27 is a second pressure pad that presses (urges) the pressure belt 21 toward the fixing belt 20. The fixing pad 24 and the pressure pad 27 are supported and disposed between the left and right side plates (not shown) of the device. The pressure pad 27 is pressed toward the fixing pad 24 with a predetermined pressure in the direction of arrow G by a pressure mechanism (not shown). A fixing sliding sheet 24a is interposed between the fixing pad 24 and the fixing belt 20, and a pressure sliding sheet 27a is interposed between the pressure pad 27 and the pressure belt 21. The fixing sliding sheet 24a and the pressure sliding sheet 27a contain resin. In this embodiment, the fixing sliding sheet 24a and the pressure sliding sheet 27a are formed by coating the surface of a polyimide (PI) sheet with polytetrafluoroethylene (PTFE) to form a plurality of convex portions periodically in the circumferential direction. The convex portions are, for example, embossed cylindrical shapes with a vertex of 200 μm in diameter and 10 μm in height, which are given by press processing. As the coating material on the surface (sliding surface) of the fixing sliding sheet 24a, in addition to polytetrafluoroethylene (PTFE), at least one selected from the group consisting of polytetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-ethylene copolymer (ETFE) is preferably used. The surface of the fixing sliding sheet 24a facing the inner peripheral surface of the fixing belt 20 has convex portions periodically formed in the circumferential direction. As illustrated in FIG. 6, when the width of the convex portions of the fixing sliding sheet 24a in the circumferential direction is W, W is preferably 20 μm or more and 3000 μm or less. The width W is more preferably 50 to 1000 μm, and further preferably 100 to 500 μm. In this embodiment, the shape of the convex portions of the fixing sliding sheet 24a is a cylindrical embossed shape, but the shape of the convex portions is not limited to this shape. The shape of the convex portions may be a triangular pyramid with a square apex and a flat surface, or a square prism. In addition, "periodic" means that the convex portions are repeatedly formed in the circumferential direction at a predetermined interval, and when the circumferential distance of the gap between the convex portions is G, the above W+G is one period and this is repeated in the circumferential direction. The gap G is preferably from 10 to 1000 μm, more preferably from 20 to 500 μm, and particularly preferably from 100 to 400 μm. It is preferable to apply a lubricant to the fixing sliding sheet 24a, specifically, silicone oil or the like can be given as an example of the lubricant to be applied.

[0026] When the Vickers hardness of the inner circumferential surface of the fixing belt 20 is HVA and the Vickers hardness of the surface of the fixing sliding sheet 24a facing the fixing belt 20 is HVB, HVA>HVB. At this time, the difference between HVA and HVB is not particularly limited, but is preferably greater than 0 and less than 37.82, particularly 3.78. In addition, it is preferable that the Vickers hardness HVA is greater than 9.45HV and less than 94.55HV, particularly 34.98HV or more and less than 77.31HV. Furthermore, it is preferable that the Vickers hardness HVB is 9.45HV or more and less than 56.73HV, particularly 33.09HV or more and less than 56.73HV. In the present disclosure, the Vickers hardness is a value measured by a method conforming to ISO6507-1 using a micro Vickers hardness tester. The test temperature for measuring the Vickers hardness is 23°C ± 5°C. The Vickers hardness can be measured, for example, by contacting a diamond Vickers indenter with the measurement object itself, specifically, the inner circumferential surface of the first rotor or the surface of the fixed sliding sheet facing the inner circumferential surface of the first rotor. Then, the Vickers indenter can be pressed in the thickness direction. Alternatively, a measurement sample having the entire thickness of each is cut out from the first rotor and / or the fixed sliding sheet. Then, the Vickers indenter made of diamond may be contacted with the inner circumferential surface of the first rotor or the surface of the fixed sliding sheet facing the inner circumferential surface of the first rotor in the obtained measurement sample, and pressed in the thickness direction of the sample.

[0027] In the fixing belt according to one embodiment of the present disclosure, an additive (filler) with a certain particle size is added to the inner sliding layer to impart a certain roughness to the inner circumferential surface of the fixing belt 20. The type of additive, the particle size, and the method of adding the additive to the inner sliding layer will be described later. The arithmetic mean roughness Ra of the inner circumferential surface of the fixing belt 20 is 0.10 μm or more and 0.25 μm or less. In addition, the arithmetic mean roughness Ra of the inner circumferential surface of the fixing belt 20 is preferably 0.15 μm or more and 0.20 μm or less. Furthermore, as shown in FIG. 6, when the average interval of the irregularities on the inner peripheral surface of the fixing belt 20 is Rsm, the circumferential width W of the protrusions of the fixing sliding sheet 24a is larger than Rsm. The inner peripheral surface of the fixing belt 20 refers to the surface opposite to the side facing the base layer of the inner sliding layer 20b. The average interval Rsm of the irregularities refers to the circumferential width of the recesses. This can prevent the protrusions of the fixing sliding sheet 24a from entering the recesses on the circumferential surface of the inner sliding layer, and can prevent the protrusions of the fixing sliding sheet 24a from being scraped off by the irregularities on the inner peripheral surface of the fixing belt. In this case, Rsm is preferably 10 μm or more and 1000 μm or less. The arithmetic mean roughness Ra and the average interval Rsm of the irregularities on the inner peripheral surface are parameters specified in the Japanese Industrial Standards (JIS) B0601:2013. The average spacing Rsm of irregularities in the present disclosure corresponds to the "average length of roughness curve elements" in JIS B0601:2013. Ra and Rsm can be measured using a surface roughness meter conforming to JIS B0601:2013. In addition, when measuring Ra and Rsm, the measurement length and evaluation length in the circumferential direction of the inner peripheral surface of the fixing belt may be determined based on Tables 1 and 3 of Japanese Industrial Standards (JIS) B0633:2001.

[0028] 6, when the height of the protrusions of the fixing sliding sheet 24a is T and the maximum height roughness of the cross-sectional curve of the inner circumferential surface of the fixing belt is Rz, it is preferable that T>Rz. In the fixing device according to one embodiment of the present disclosure, it is preferable that, for example, T=10 μm and Rz=0.3 μm. The maximum height roughness Rz referred to here is that specified in the Japanese Industrial Standards (JIS) B0601:2013. Rz can also be measured using a surface roughness meter that complies with the Japanese Industrial Standards (JIS) B0601:2013. In addition, when measuring Rz, the measurement length and evaluation length in the circumferential direction of the inner peripheral surface of the fixing belt may also be determined based on Table 2 of the Japanese Industrial Standards (JIS) B0633:2001.

[0029] The control circuit unit 100 drives the motor M at least when image formation is being performed. This causes the fixing roller 23 to rotate, and the fixing belt 20 to rotate in the same direction as the fixing roller 23. The peripheral speed of the fixing belt 20 is set to be slightly slower than the conveying speed of the sheet S conveyed from the image forming unit side in order to form a loop in the recording material. The pressure belt 21 rotates following the rotation of the fixing belt 20. Here, the most downstream portion of the fixing nip is configured to sandwich the fixing belt 20 and the pressure belt 21 between the roller pairs 23 and 26, thereby preventing the belts from slipping. The most downstream portion of the fixing nip is the portion where the pressure distribution (recording material conveying direction) in the fixing nip is maximum.

[0030] Furthermore, the control circuit unit 100 supplies power from the power supply circuit 101 to the halogen heater 22a. This heats the heating roller 22. The rotating fixing belt 20 is then heated by this heating roller 22. The surface temperature of the fixing belt 20 is detected by a temperature detection element TH such as a thermistor. A signal relating to the temperature of the fixing belt 20 detected by this temperature detection element TH is input to the control circuit unit 100. The control circuit unit 100 controls the power supplied from the power supply circuit 101 to the halogen heater 22a so that the temperature information input from the temperature detection element TH is maintained at a predetermined fixing temperature, thereby adjusting the temperature of the fixing belt 20 to the predetermined fixing temperature.

[0031] When the fixing belt 20 has risen to a predetermined fixing temperature and is in a state where the temperature is adjusted, a recording material S having an unfixed toner image T is conveyed to the fixing nip N between the fixing belt 20 and the pressure belt 21. The recording material S is introduced with the surface carrying the unfixed toner image T facing the fixing belt 20. Then, as the recording material S is nipped and conveyed while being in close contact with the outer circumferential surface of the fixing belt 20, heat is applied from the fixing belt 20, and the unfixed toner image T of the recording material S is fixed to the surface of the recording material S by receiving a pressure force. Since the fixing roller 23 in the fixing belt 20 is an elastic roller having a rubber layer, and the pressure roller 26 in the pressure belt 21 is a rigid roller made of an iron alloy, the fixing roller 23 is significantly deformed at the exit of the fixing nip between the fixing belt 20 and the pressure belt 21. As a result, the fixing belt 20 is also significantly deformed, and the recording material S carrying the toner image is separated from the fixing belt 20 by its own stiffness.

[0032] (3) Fixing belt and pressure belt FIG. 3 is a schematic diagram of the fixing belt 20 obtained in this embodiment. 20c is a cylindrical substrate, 20b is an inner sliding layer disposed on the inner circumferential surface of the cylindrical substrate 20c, and is disposed via an adhesive layer. 20a is a needle-shaped anisotropic filler (additive) blended in the inner sliding layer, and is disposed along the longitudinal direction of the fixing belt. 20d is a silicone rubber elastic layer that covers the outer circumferential surface of the cylindrical substrate 20c, and is disposed via a primer layer (not shown). 20e is a fluororesin tube as a fluororesin surface layer, and is disposed on the silicone rubber elastic layer 20d via a silicone rubber adhesive layer (not shown). The fixing belt 20 and the pressure belt 21 have the same configuration, so a description of the configuration of the pressure belt will be omitted.

[0033] (4) Cylindrical base Since the fixing belt is required to have heat resistance, it is preferable to use a cylindrical substrate 20c that is heat-resistant and flex-resistant. For example, as the metal substrate, a metal material such as nickel electroforming or stainless steel can be used as described in JP-A-2002-258648, WO05 / 054960, JP-A-2005-120825, etc.

[0034] (5) Inner sliding layer The inner surface sliding layer 20b preferably contains a resin having high durability and high heat resistance, such as polyimide (PI), polyamide-imide (PAI), polyether-ether-ketone (PEEK), etc. In particular, polyimide is preferable in terms of ease of manufacture, heat resistance, elasticity, strength, etc. In order to improve the sliding performance, it is preferable to add particles of graphite, molybdenum disulfide, fluororesin, etc. as additives so that unevenness can be generated on the inner sliding layer 20b. Mica is preferable in terms of ease of manufacture, heat resistance, lubricity, etc.

[0035] (5-1) Polyimide precursor solution The inner surface sliding layer 20b is formed by applying a polyimide precursor solution obtained by reacting an aromatic tetracarboxylic dianhydride or a derivative thereof with an aromatic diamine in an organic polar solvent in approximately equimolar amounts, to the inner surface of the cylindrical substrate 20c, drying, heating, and causing a dehydration ring-closing reaction. Representative examples of aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, etc. These aromatic tetracarboxylic dianhydrides can be used alone or in combination of two or more kinds. Representative examples of aromatic diamines include 4,4'-diaminodiphenyl ether, paraphenylenediamine, benzidine, etc. These aromatic diamines can be used alone or in combination of two or more kinds. Examples of the organic polar solvent include dimethylacetamide (DMAC), dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), phenol, O-, M-, and P-cresol.

[0036] (5-2) Additives The particle size of the additive (sometimes called a filler) must be selected in order to generate irregularities on the inner sliding layer. From the viewpoint of cell formation, a particle size of less than 4.5 μm is preferable for an inner sliding layer thickness of 8 to 20 μm. Furthermore, the additive added to the inner sliding layer of the fixing belt preferably has a volume particle size D50 of 1.0 to 3.5 μm and an aspect ratio of 1 to 50. The volume particle size D50 is measured by a laser diffraction scattering type particle size distribution measuring device. In addition, in the present disclosure, the aspect ratio is the ratio of the major axis to the minor axis of the additive (major axis / minor axis). The major axis and minor axis of each particle were measured for 1000 or more powder particles observed by a scanning electron microscope (SEM), and the major axis / minor axis was calculated, and the aspect ratio was calculated by arithmetic averaging. In order to generate lubricity in the inner sliding layer, it is necessary to select a material with lubricating ability. In addition, it is necessary to select a material with appropriate hardness because it is required to be wear-resistant and not induce wear of the sliding-related parts when it is detached from the inner sliding layer. Taking these conditions into consideration, polytetrafluoroethylene (PTFE), graphite, molybdenum disulfide, mica, etc. are suitable as additives. The amount of the additive is not particularly limited as long as it satisfies the generation of unevenness on the inner sliding layer as intended by the present disclosure. Specifically, the amount of the additive is 1 part per 100 parts of the polyimide precursor solution.

[0037] (5-3) Formation of inner sliding layer Possible coating methods include a ring coating method. Fig. 4 is a schematic diagram of a coating device for the ring coating method. Support pillars 201 and 202 are formed on a base 41. The coating head 42 is fixed onto the support pillar 201, and is connected to a coating liquid supply device (not shown). A work hand 45 that holds the cylindrical base body 20c is formed on the support 202 in the work moving device 56. The work moving device 46 can be moved up and down by a motor provided on the support 202, and the work hand 45 formed on the work moving device 46 can also be moved up and down by the movement of the work moving device 46. A slit (not shown) perpendicular to the axis of the cylinder is formed around the outer periphery of the coating head 42, and the polyimide precursor solution containing additives is uniformly supplied from the slit. The cylindrical substrate 20c is then moved along the outer periphery of the coating head 42, and the inner surface of the cylindrical substrate 20c is coated. In this device, the thickness of the inner surface sliding layer is determined by the amount of coating, and any amount of coating (film thickness) can be obtained by changing the clearance, the supply speed of the polyimide precursor solution, and the movement speed of the workpiece moving device 46.

[0038] After coating, the cylindrical substrate 20c with the inner surface coated is placed in the heating and drying furnace 50 of FIG. 5 to be dried. In the heating and drying furnace 50, high-temperature oil heated to 120 to 200°C is passed from an oil inlet 51 through a heating cylinder 52 and discharged from an oil outlet 53, so that the temperature inside the heating and drying furnace 50 is set to 100 to 180°C. The cylindrical substrate 20c with the inner surface coated is placed in the furnace to volatilize the organic polar solvent contained in the polyimide precursor solution. By reducing the organic polar solvent contained in the polyimide precursor solution from about 90% by volume to less than about 30% by volume, the viscosity of the polyimide precursor solution is increased, and the polyimide precursor solution is prevented from flowing out from the inner surface of the cylindrical substrate 20c. Since the organic polar solvent contained in the polyimide precursor solution is volatilized in the heating and drying furnace 50, the concentration of the organic polar solvent volatilized inside the drying furnace differs between the top and bottom of the drying furnace. Therefore, by increasing the speed of the exhaust air flowing from the intake port 54 to the inside for ventilation, the organic polar solvent inside is exhausted from the exhaust port 55, thereby reducing the difference between the upper and lower vapor concentrations of the organic polar solvent inside the drying furnace. After the organic polar solvent contained in the polyimide precursor solution is reduced to less than about 30% by volume, the cylindrical substrate 20c is left to dry for 30 minutes in a hot air circulating oven at 200°C, for example. Then, the cylindrical substrate 20c is left to bake for 20 to 120 minutes in a hot air circulating oven at 200°C to 300°C, which is a temperature range that does not reduce the fatigue strength of the cylindrical substrate 20c. This allows the inner surface sliding layer 20b of polyimide resin with filler dispersed therein to be formed by a dehydration ring-closing reaction.

[0039] (6) Silicone rubber elastic layer The silicone rubber elastic layer 20d functions as an elastic layer supported by a fixing member to apply uniform pressure to the unevenness of the toner image and the paper during fixing. In order to realize such a function, it is preferable to use an addition reaction crosslinking type liquid silicone rubber as the material for the silicone rubber elastic layer 20d, because it is easy to process, can be processed with high dimensional accuracy, and does not generate reaction by-products during heat curing. In addition, it is preferable to use an addition reaction crosslinking type liquid silicone rubber, because the elasticity can be adjusted by adjusting the degree of crosslinking according to the type and amount of filler contained in the silicone rubber elastic layer 20d, which will be described later. In general, addition reaction crosslinking type liquid silicone rubber contains an organopolysiloxane having an unsaturated aliphatic group, an organopolysiloxane having active hydrogen bonded to silicon, and a platinum compound as a crosslinking catalyst. Organopolysiloxanes having active hydrogen bonded to silicon react with organopolysiloxane components having unsaturated aliphatic groups (alkenyl groups) under the catalytic action of platinum compounds to form crosslinked structures.

[0040] The silicone rubber elastic layer 20d may contain a filler for the purpose of improving the thermal conductivity of the fixing belt 20, reinforcing the fixing belt 20, and improving the heat resistance. In particular, for the purpose of improving thermal conductivity, highly thermally conductive inorganic substances, particularly metals and metal compounds, are preferred as the filler. Specific examples of high thermal conductive fillers include 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), and nickel (Ni). These may be used alone or in combination of two or more. The average particle size of the highly thermally conductive filler is preferably 1 μm or more and 50 μm or less from the viewpoints of handling and dispersibility. The shape may be spherical, pulverized, plate-like, whisker-like, etc., but spherical is preferred from the viewpoint of dispersibility.

[0041] In terms of contribution to the surface hardness of the fixing belt and efficiency of heat conduction to unfixed toner during fixing, the thickness of the silicone rubber elastic layer is preferably 100 μm to 500 μm, more preferably 200 μm to 400 μm.

[0042] (7) Fluorine resin surface layer The fluororesin surface layer may be, for example, a tubular resin such as tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA), polytetrafluoroethylene (PTFE), or tetrafluoroethylene-hexafluoropropylene copolymer (FEP). Among the materials listed above, PFA is preferred from the viewpoints of moldability and toner releasability. The thickness of the fluororesin release layer is preferably 50 μm or less, because this maintains the elasticity of the silicone rubber elastic layer underneath when laminated, and prevents the surface hardness as a fixing member from becoming too high. The inner surface of the fluororesin tube can be previously treated with sodium, excimer laser, ammonia, or the like to improve the adhesiveness. In this embodiment, a PFA tube having a thickness of 30 μm obtained by extrusion molding was used. The inner surface of the tube was treated with ammonia to improve wettability with the adhesive described below.

[0043] The silicone rubber adhesive layer (not shown) that fixes the PFA tube 20e as a fluororesin surface layer to the silicone rubber elastic layer 20d is made of a cured product of an addition-curing type silicone rubber adhesive applied to the surface of the silicone rubber elastic layer 20d. The addition-curing type silicone rubber adhesive contains an addition-curing type silicone rubber blended with a self-adhesive component represented by a silane having a functional group such as an acryloxy group, a hydrosilyl group (SiH group), an epoxy group, or an alkoxysilyl group.

[0044] The addition-curing silicone rubber adhesive is cured and bonded by heating for a predetermined period of time using a heating means such as an electric furnace, and both ends are cut to the desired length to obtain a fixing belt as the fixing member of this embodiment. EXAMPLES

[0045] The fixing device according to the present disclosure will be described in more detail below with reference to examples and comparative examples, but the present disclosure is not limited to these examples. In addition, "parts" indicates "parts by mass." Example 1 A method for producing the fixing belt used in this embodiment will be described in detail. First, the additives will be described. In this embodiment, mica MK-100 (trade name, Katakura Co-op Agri Co., Ltd.) was used as the filler. MK-100 has an aspect ratio of 30 to 50, and a volume particle size D50 of 4.5 μm. The amount of mica added was 1 part per 100 parts of the polyimide precursor solution. The polyimide precursor solution used was Upia (registered trademark)-ST (U-Varnish-S) (trade name, manufactured by UBE Co., Ltd.). The solvent in the polyimide precursor solution used was NMP. A coating liquid was prepared by dispersing mica in the polyimide precursor solution with three rolls. The prepared coating liquid was applied to the inner surface of the cylindrical substrate 20c by the ring coating method so that the coating thickness was 77 μm. At this time, the clearance was set to 100 μm, the supply speed of the polyimide precursor solution was set to 5 mm / s, and the movement speed of the workpiece moving device 46 was set to 100 mm / s. The cylindrical substrate 20c was a nickel electroformed product having an inner diameter of Φ80 mm and a thickness of 40 μm.

[0046] After coating, the cylindrical substrate 20c with the inner surface coated is placed in the heating and drying furnace 50 of FIG. 5 to be dried. The heating and drying furnace 50 is set to 180°C for high-temperature oil. In this case, the temperature inside the drying furnace is 160 to 140°C. NMP, which is an organic polar solvent contained in the polyimide precursor solution, is volatilized, and the NMP contained in the polyimide precursor solution is reduced from about 90% by volume to less than about 30% by volume. Since NMP is volatilized inside the heating and drying furnace 50, the concentration of NMP volatilized inside the drying furnace differs between the top and bottom of the drying furnace. By increasing the wind speed of the exhaust air flowing from the intake port 54 to the inside for ventilation, the NMP inside is exhausted from the exhaust port 55, and the difference between the top and bottom of the NMP vapor concentration inside the drying furnace is reduced. In Example 1, the ventilation wind speed flowing inside the heating and drying furnace is set to 1.0 m / s, and the drying is performed for 300 seconds. The dried cylindrical substrate 20c is baked in a hot air circulation furnace at 270°C for 60 minutes. As a result, the filler was dispersed on the inner surface of the cylindrical substrate 20c, and an inner surface sliding layer 20b made of polyimide and having a thickness of 15 μm was formed.

[0047] A hydrosilyl silicone primer (product name: DY39-051 A / B, manufactured by Dow Corning Toray Co., Ltd.) was applied to the surface of the cylindrical substrate 20c, and the primer was heated and cured at 200°C for 5 minutes. An addition reaction crosslinking type liquid silicone rubber containing alumina as a highly thermally conductive filler was applied to the outer peripheral surface of the substrate 20c to a thickness of 300 μm, and the primer was heated and cured at 200°C for 30 minutes to form a silicone rubber elastic layer 20d. At this time, the thermal conductivity of the silicone rubber elastic layer 20d was 0.8 W / mK. Furthermore, the outer peripheral surface of the substrate 20c was covered with a fluororesin surface layer 20e (a 20 μm thick PFA tube extruded into a cylindrical shape) via a silicone adhesive (product name: SE1819 CV A / B, manufactured by Dow Corning Toray Co., Ltd.), and the primer was heated and cured at 200°C for 2 minutes. The PFA tube was formed by extrusion molding using fluororesin pellets (product name: Teflon (registered trademark) PFA959HPPlus, manufactured by Mitsui DuPont Fluorochemicals Co., Ltd.).

[0048] FIG. 6 shows a cross-sectional view of the inner sliding layer 20a of the fixing belt 20 and the fixing sliding sheet 24a. The manufactured fixing belt 20 was measured using a surface roughness meter (product name: SE-600, Kosaka Manufacturing Co., Ltd.) to find that the arithmetic mean roughness Ra of the inner peripheral surface was 0.15 μm, and the mean interval Rsm of the irregularities on the inner peripheral surface was 100 μm. The maximum height roughness Rz of the surface roughness of the inner sliding layer 20a of the fixing belt 20 was 0.3 mm, and the height T of the protrusions of the fixing sliding sheet 24a was 10 μm. The Vickers hardness HVA of the inner sliding layer 20a of the fixing belt 20 was measured using a micro Vickers hardness meter (product name: HMV, Shimadzu Corporation) to find that it was 60.51 HV.

[0049] The fixing sliding sheet 24a was made of a material in which the surface of a polyimide (PI) sheet was coated with polytetrafluoroethylene (PTFE) (product name: PJ-BN910, manufactured by Mitsui-Chemours Fluoroproducts), and a cylindrical embossed shape with a diameter of 200 μm and a height of 10 μm was given by press processing. That is, in FIG. 6, the circumferential width W of the convex portion of the fixing sliding sheet 24a was 200 μm, and the convex portion height T was 10 μm. The Vickers hardness HVB of the surface of the fixing sliding sheet 24a facing the fixing belt 20 was 56.73 HV. A lubricant (product name: KF96, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the fixing sliding sheet 24a.

[0050] Example 2 The amount of mica added used in Example 1 was changed to 0.7 parts, and the fixing belt 20 was produced in the same manner as in Example 1. The arithmetic mean roughness Ra of the inner circumferential surface of the fixing belt 20 was 0.1 μm, and the average spacing Rsm of the irregularities on the inner circumferential surface was 100 μm.

[0051] Example 3 The amount of mica added used in Example 1 was changed to 1.3 parts, and the fixing belt 20 was produced in the same manner as in Example 1. The arithmetic mean roughness Ra of the inner circumferential surface of the fixing belt 20 was 0.25 μm, and the mean spacing Rsm of the irregularities on the inner circumferential surface was 100 μm.

[0052] Example 4 The mica used in Example 1 was pulverized by a jet mill to a volume particle size D50 of 3.0 μm and an addition amount of 1.5 parts, and the fixing belt 20 was produced in the same manner as in Example 1. The arithmetic mean roughness Ra of the inner peripheral surface of the fixing belt 20 was 0.15 μm, and the average interval Rsm of the irregularities on the inner peripheral surface was 150 μm.

[0053] Example 5 The embossed shape of the fixing sliding sheet 24a in Example 1 was changed to a cylindrical shape with a diameter of 200 μm and a height of 0.2 μm, and the fixing belt 20 was produced in the same manner as in Example 1. The height T of the convex portion of the fixing sliding sheet 24a was 0.2 μm.

[0054] Comparative Example 1 The amount of mica added used in Example 1 was changed to 0.3 parts, and the fixing belt 20 was produced in the same manner as in Example 1. The arithmetic mean roughness Ra of the inner peripheral surface of the fixing belt 20 was 0.09 μm, and the average spacing Rsm of the irregularities on the inner peripheral surface was 100 μm.

[0055] Comparative Example 2 The amount of mica added used in Example 1 was changed to 1.5 parts, and the fixing belt 20 was produced in the same manner as in Example 1. The arithmetic mean roughness Ra of the inner circumferential surface of the fixing belt 20 was 0.26 μm, and the average spacing Rsm of the irregularities on the inner circumferential surface was 100 μm.

[0056] Comparative Example 3 The fixing belt 20 was produced in the same manner as in Example 1, except that the fixing sliding sheet 24a in Example 1 was changed to a glass cloth instead of an embossed sheet. The glass cloth had a surface layer coated with PTFE. The Vickers hardness HVB of the glass cloth was 122.92 HV.

[0057] Comparative Example 4 The embossed shape of the fixing sliding sheet 24a in Example 1 was changed to a cylindrical shape with a diameter of 90 μm, and the fixing belt 20 was produced in the same manner as in Example 1. That is, the circumferential width W of the convex portion of the fixing sliding sheet in FIG. 6 was 90 μm.

[0058] Comparative Example 5 The mica used in Example 1 was changed to one having an aspect ratio of 50 to 150, and the fixing belt 20 was produced in the same manner as in Example 1. The arithmetic mean roughness Ra of the inner peripheral surface of the fixing belt 20 was 0.15 μm, and the average length Rsm of the roughness curve elements was 200 μm.

[0059] Using the fixing belts 20 of Examples 1 to 4 and Comparative Examples 1 to 5, an evaluation was carried out by a paper passing test. The evaluation was carried out in a H / H environment (temperature 30° C., humidity 80%) using plain paper (basis weight 70 g / m 2 ) and evaluated the lifespan in terms of abrasion of the inner peripheral surface of the fixing belt 20. Table 1 shows the results of paper passing durability in the fixing devices of Examples 1 to 4 and Comparative Examples 1 to 5. The lifespan was ranked as follows (K=1000). Rank A: 700K or more Rank B: 600K to less than 700K Rank C: 500K to less than 600K Rank D: Less than 500K

[0060] [Table 1]

[0061] In Examples 1 to 5, the wear of the embossed shape of the fixing sliding sheet 24a was suppressed, and the lubricant of the fixing sliding sheet 24a and the inner sliding layer 20b of the fixing belt 20 flowed out over time, causing the fixing belt 20 to reach the end of its life. In Comparative Example 1, the inner surface sliding layer 20b had small roughness and lost its ability to retain the lubricant, so that the life of the comparative example expired earlier than that of the examples. In Comparative Example 2, the roughness of the inner sliding layer 20b was large, so that abrasion powder was generated from the inner sliding layer 20b, which mixed with the lubricant and accelerated the viscosity increase of the lubricant, and the life was reached after 300K sheets. In Comparative Example 3, the inner surface sliding layer 20b was rapidly worn away by the fixing sliding sheet 24a made of glass, and the life of the sensor reached the end at 200K. In Comparative Example 4, the embossed portion of the fixing sliding sheet 24a entered the recesses in the rough surface of the inner sliding layer 20b and was scraped off, so that the lubricant could no longer be retained, and the life ended at 600K. In Comparative Example 5, similarly to Comparative Example 4, the embossed portion of the fixing sliding sheet 24a was scraped off, the lubricant could no longer be retained, and the life of the sheet came to an end at 600K. In the embodiment, it was confirmed that the abrasion of the fixing sliding sheet 24a and the abrasion of the inner sliding layer 20b, which are rate-determining factors of the life, were suppressed. In this embodiment, the fixing belt 20 and the fixing sliding sheet 24a are limited, but the present invention can also be applied to the pressure belt 21 and the pressure sliding sheet 27a, and is not limited to the scope of this embodiment.

[0062] The present disclosure includes the following configurations. [Configuration 1] a first rotating body having a surface layer, a base layer, and an inner sliding layer; a second rotating body having a surface layer and a base layer; a pressure member disposed inside the first rotor and configured to bias the first rotor against the second rotor; a fixing sliding sheet interposed between the pressing member and the first rotating body and sliding against the first rotating body; A fixing device comprising: The fixing sliding sheet contains a resin, a Vickers hardness measured on an inner peripheral surface of the first rotating body is defined as HVA, and a Vickers hardness measured on a surface of the fixing sliding sheet facing the first rotating body is defined as HVB, HVA>HVB, the fixing sliding sheet has a plurality of convex portions periodically provided in a circumferential direction on a surface facing the inner circumferential surface of the first rotating body, The arithmetic mean roughness Ra of the inner peripheral surface of the first rotating body is 0.10 μm or more and 0.25 μm or less, The fixing device is characterized in that the circumferential width W of the protrusions of the fixing sliding sheet is larger than the average interval Rsm of the protrusions and recesses on the inner circumferential surface of the first rotating body. [Configuration 2] The fixing device according to [Configuration 1], wherein the width W in the circumferential direction of the protrusions of the fixing sliding sheet is 20 μm or more and 3000 μm or less. [Configuration 3] The fixing device according to [Configuration 1] or [Configuration 2], wherein the average interval Rsm is 10 μm or more and 1000 μm or less. [Configuration 4] The fixing device according to any one of [Configuration 1] to [Configuration 3], wherein the HVA is greater than 9.45 HV and is equal to or less than 94.55 HV, and the HVB is equal to or greater than 9.45 HV and is equal to or less than 56.73 HV. [Configuration 5] The fixing device according to any one of [Configuration 1] to [Configuration 4], wherein T>Rz is satisfied when the height of the convex portion of the fixing sliding sheet is T and the maximum height roughness of the cross-sectional curve of the inner circumferential surface of the first rotating body is Rz. [Configuration 6] The fixing device according to any one of [Configuration 1] to [Configuration 5], wherein the fixing sliding sheet has a layer that constitutes a surface facing the inner circumferential surface of the first rotating body, and the layer contains at least one selected from the group consisting of polytetrafluoroethylene, polytetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and tetrafluoroethylene-ethylene copolymer. [Configuration 7] The fixing device according to any one of [Configuration 1] to [Configuration 6], wherein the inner surface sliding layer of the first rotating body includes at least one selected from the group consisting of polyamideimide and polyimide. [Configuration 8] The fixing device according to any one of [Configuration 1] to [Configuration 7], wherein a lubricant is applied to the surface of the fixing sliding sheet facing the inner circumferential surface of the first rotating body. [Configuration 9] The fixing device according to any one of [Configuration 1] to [Configuration 8], wherein a filler having a volume particle size D50 of 1.0 to 3.5 μm and an aspect ratio of 1 to 50 is added to the inner sliding layer of the first rotating body. [Explanation of symbols]

[0063] 20 Fixing belt 20a Additives 20b Inner sliding layer 20c cylindrical base 20d (silicone rubber) elastic layer 20e (fluororesin) surface layer 21 Pressure Belt 24 Fixing Pad 24a Fixing sliding sheet 27 Pressure Pad 27a Pressure sliding sheet

Claims

1. a first rotating body having a surface layer, a base layer, and an inner surface sliding layer; a second rotating body having a surface layer and a base layer; a pressure member disposed inside the first rotor and biasing the first rotor against the second rotor; a fixing sliding sheet interposed between the pressing member and the first rotating body and sliding against the first rotating body; A fixing device comprising: The fixing sliding sheet contains a resin, a Vickers hardness measured on an inner peripheral surface of the first rotating body is defined as HVA, and a Vickers hardness measured on a surface of the fixing sliding sheet facing the first rotating body is defined as HVB, HVA>HVB, the fixing sliding sheet has a plurality of convex portions periodically provided in a circumferential direction on a surface facing the inner circumferential surface of the first rotating body, The arithmetic mean roughness Ra of the inner circumferential surface of the first rotating body is 0.10 μm or more and 0.25 μm or less, a circumferential width W of the protrusions of the fixing sliding sheet is larger than an average interval Rsm of the protrusions on the inner circumferential surface of the first rotating body.

2. 2. The fixing device according to claim 1, wherein the width W in the circumferential direction of the protrusions of the fixing sliding sheet is 20 [mu]m or more and 3000 [mu]m or less.

3. The fixing device according to claim 1 , wherein the average distance Rsm is equal to or greater than 10 μm and equal to or less than 1000 μm.

4. 2. The fixing device according to claim 1, wherein the HVA is greater than 9.45 HV and is equal to or less than 94.55 HV, and the HVB is equal to or greater than 9.45 HV and is equal to or less than 56.73 HV.

5. 2. The fixing device according to claim 1, wherein T>Rz is satisfied, where T is the height of the protrusions of the fixing sliding sheet and Rz is the maximum height roughness of the cross-sectional curve of the inner circumferential surface of the first rotating body.

6. 2. The fixing device according to claim 1, wherein the fixing sliding sheet has a layer that constitutes a surface facing the inner circumferential surface of the first rotating body, and the layer includes at least one selected from the group consisting of polytetrafluoroethylene, polytetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and tetrafluoroethylene-ethylene copolymer.

7. The fixing device according to claim 1 , wherein the inner surface sliding layer of the first rotating member includes at least one selected from the group consisting of polyamideimide and polyimide.

8. 2. The fixing device according to claim 1, wherein a lubricant is applied to a surface of the fixing sliding sheet facing the inner circumferential surface of the first rotating body.

9. 2. The fixing device according to claim 1, wherein a filler having a volume particle size D50 of 1.0 to 3.5 μm and an aspect ratio of 1 to 50 is added to the inner sliding layer of the first rotating body.

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