JP2020012956A - Endless belt, fixing device, image forming apparatus, and method for manufacturing endless belt - Google Patents

Abstract

To provide an endless belt that can maintain a low slide resistance during rotation, a fixing device, an image forming apparatus, and a method for manufacturing the endless belt.SOLUTION: An endless belt 2 has rough surface parts 21A to 21E formed on an inner peripheral surface 2A, and thereby, when a lubricant is applied on the inner peripheral surface 2A, the lubricant can be held in recesses of the rough surface parts 21A to 21E, the lubricant is supplied from the recesses to projections during rotation, and a slide resistance can be reduced. Flat parts 22A to 22D are easily closely adhered to an object to be slid and do not easily pass the lubricant therethrough. Such flat parts 22A to 22D are arranged adjacent in a width direction to the rough surface parts 21A to 21E, and thereby the lubricant does not easily leak from the ends in the width direction when the endless belt 2 is repeatedly rotated, and a low slide resistance during the rotation of the endless belt 2 can be maintained.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an endless belt, a fixing device, an image forming apparatus, and a method for manufacturing an endless belt.

  In general, as a fixing device used in an image forming apparatus, a fixing device including an endless fixing member (fixing belt) and a pressure roller is known. In such a fixing device, a nip portion is formed by the fixing member and the pressure roller, and the toner is pressed and heated at the nip portion to fix the toner on the recording paper.

  As an endless belt used for such a fixing device, a belt having fine convex portions formed on an inner surface has been proposed (for example, see Patent Document 1). In the endless belt described in Patent Literature 1, the sliding resistance when sliding with the sliding member is reduced by forming the convex portion into a spherical surface.

  In order to further reduce the sliding resistance, a method of applying a lubricant to the inner surface of the endless belt can be considered. However, the applied lubricant may leak from the end in the width direction as the endless belt rotates. If the total amount decreases due to leakage of the lubricant, the sliding resistance increases. That is, it has been difficult to keep the sliding resistance reduced by the lubricant.

  SUMMARY OF THE INVENTION It is an object of the present invention to provide an endless belt, a fixing device, an image forming apparatus, and an endless belt manufacturing method that can keep the sliding resistance during rotation low.

  According to an aspect of the present invention, there is provided an endless belt used in a fixing device, wherein the belt has a rough surface extending in a circumferential direction and is arranged adjacent to the rough surface in a width direction. And a flat portion having a smaller surface roughness Rz than the rough surface portion is formed on an inner peripheral surface of the endless belt.

  According to the endless belt of the present invention, since the rough surface portion is formed on the inner peripheral surface, when the lubricant is applied to the inner peripheral surface, the lubricant can be held in the concave portion of the rough surface portion, Lubricant is supplied from the concave portion to the convex portion during rotation, so that sliding resistance can be reduced. In addition, the flat portion easily adheres to the sliding object, and the lubricant hardly passes through. By arranging such a flat portion so as to be adjacent to the rough surface portion in the width direction, it becomes difficult for the lubricant held on the rough surface portion to flow in the width direction, and when the endless belt repeatedly rotates. In addition, the lubricant hardly leaks from the width direction end. Therefore, the sliding resistance during rotation of the endless belt can be kept low.

FIG. 2 is a cross-sectional view illustrating the fixing device according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view schematically illustrating an image forming apparatus provided with the fixing device. FIG. 3 is a plan view illustrating an inner peripheral surface of an endless belt of the fixing device. It is a perspective view which shows the cylindrical metal mold | die for manufacturing the said endless belt. It is a perspective view showing signs that blast processing is given to a metallic mold base material in order to manufacture the above-mentioned cylindrical metallic mold. It is sectional drawing which shows a mode that the blast process was given to the said mold base material. It is sectional drawing which shows the mode that the said mold base material was polished. It is sectional drawing which shows a mode that the coating liquid was apply | coated to the said mold base material. It is sectional drawing which shows a mode that the resin film formed by the said coating liquid is released from a metal mold base material. FIG. 6 is a cross-sectional view illustrating a fixing device according to a second embodiment of the present disclosure. FIG. 9 is a cross-sectional view illustrating a fixing device according to a third embodiment of the present disclosure. FIG. 14 is a sectional view illustrating a fixing device according to a fourth embodiment of the present disclosure. FIG. 14 is a sectional view illustrating a fixing device according to a fifth embodiment of the present invention. FIG. 14 is a sectional view illustrating a fixing device according to a sixth embodiment of the present invention. It is sectional drawing which shows the outline of the test device for evaluating the performance of the said endless belt.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the second to sixth embodiments, the same components and components having the same functions as those described in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and description thereof is omitted.

[First Embodiment]
The fixing device 1 of this embodiment is provided in an image forming apparatus (see FIG. 2) 100. As shown in FIG. 1, an endless belt 2, a heating unit 3, a pressing roller 4, A nip forming member 5.

[Fixing device]
The endless belt 2 is a fixing belt formed of polyimide. The surface layer of the belt has a release layer such as a PFA or PTFE layer, and has a release property so that toner does not adhere. An elastic layer formed of a silicone rubber layer or the like may be provided between the base material of the belt and the PFA or PTFE layer. If there is no silicone rubber layer, the heat capacity will be small and the fixability will be improved. Gloss unevenness (Yuzu skin image) tends to remain. In order to improve this, it is preferable to provide a silicone rubber layer of 100 μm or more. Due to the deformation of the silicone rubber layer, minute unevenness is absorbed, and the yuzu skin image is improved.

  A support member (stay) 6 for supporting the nip forming member 5 is provided inside the endless belt 2 to prevent the nip forming member 5 from being bent by the pressure roller 4 and to be uniform in the axial direction. The nip width can be obtained.

  Further, the fixing device 1 includes a reflection member 8 between the heating unit 3 and the support member 6, and wasteful energy consumption due to the heating of the support member 6 by radiant heat from the heating unit 3 is suppressed. I have. Here, the same effect can be obtained by performing heat insulation or mirror finishing on the surface of the support member 6 instead of providing the reflection member 8.

  The heating means 3 may be a halogen heater as shown, but may be an IH, a resistance heating element, a carbon heater, or the like. The heating means 3 directly heats the endless belt 2 from the inner peripheral side. When the heating unit 3 is a halogen heater, the fixing device 1 may have a light shielding plate. The light-shielding plate shields the light emitted by the halogen heater so that the endless belt 2 is heated in a range corresponding to the recording paper size. The light-shielding plate has a light-passing portion corresponding to various recording paper sizes. For example, by rotating, an appropriate light-passing portion is positioned between the heating means 3 and the endless belt 2. I have.

  The pressure roller 4 has an elastic rubber layer 4B provided outside the cored bar 4A, and a release layer (PFA or PTFE layer) (not shown) provided on the surface of the elastic rubber layer 4B in order to obtain releasability. ing. The pressure roller 4 is rotated by a driving force transmitted from a driving source such as a motor provided in the image forming apparatus 100 shown in FIG. 2 via a gear. Further, the pressure roller 4 is pressed against the endless belt 2 by a spring or the like, and has a predetermined nip width by crushing and deforming the elastic rubber layer 4B.

  The pressure roller may be a hollow roller or may have a heating source such as a halogen heater. The elastic rubber layer may be solid rubber, but if there is no heater inside the pressure roller, sponge rubber may be used. The use of sponge rubber is more preferable because the heat insulating property is enhanced and the heat of the fixing sleeve is hardly deprived.

  The nip forming member 5 is arranged inside the endless belt 2, that is, on the opposite side of the pressure roller 4 with the endless belt 2 interposed therebetween. As a result, a nip portion N is formed by the endless belt 2 and the pressure roller 4 which are arranged to face each other. The recording paper onto which the toner image has been transferred passes through the nip N, and is heated and pressed, so that the toner image is fixed on the recording paper.

  In FIG. 1, the shape of the nip portion N is flat, but it may be concave or another shape. (If the shape of the nip portion is concave, the discharge direction of the leading end of the recording paper is closer to the pressure roller, and the separability is improved, so that the occurrence of jam is suppressed.)

  The nip forming member 5 is provided with a fabric impregnated with a lubricant, and supplies the lubricant to the inner peripheral surface 2 </ b> A of the endless belt 2. Incidentally, examples of the lubricant include silicone oil and grease.

  The endless belt 2 rotates as the pressure roller 4 rotates. In the embodiment shown in FIG. 1, the pressure roller 4 is rotated by a driving source, and the driving force is transmitted to the belt at the nip N, whereby the endless belt 2 is rotated. The endless belt 2 rotates while being sandwiched by the nip N, and the holding members are inserted and guided at both ends except the nip N to run. As described above, the endless belt 2 has the support member 6 disposed inside and is supported so as to have a substantially cylindrical shape as a whole.

  With the above configuration, it is possible to realize an inexpensive fixing device that warms up quickly.

[Image forming apparatus]
Next, the configuration of the image forming apparatus 100 using the above configuration will be described with reference to FIG.

  The image forming apparatus 100 shown in FIG. 2 is a color printer using a tandem system in which image forming units for forming a plurality of color images are arranged side by side along the belt extending direction. The present invention is not limited to this method, and can be applied not only to printers but also to copiers and facsimile machines.

  In FIG. 2, the image forming apparatus 100 includes photosensitive drums 20Y, 20C, and 20M as image carriers capable of forming images as images corresponding to colors separated into yellow, cyan, magenta, and black, respectively. A tandem structure in which 20 Bk are juxtaposed is adopted.

  In the image forming apparatus 100 having the configuration shown in FIG. 2, the visible image formed on each of the photosensitive drums 20Y, 20C, 20M, and 20Bk is moved in the direction of arrow A1 while facing each of the photosensitive drums 20Y, 20C, 20M, and 20Bk. The primary transfer process is performed on an intermediate transfer body (hereinafter, referred to as a transfer belt) 11 that uses an endless belt that can be moved to each other, and each image is superimposed and transferred. Thereafter, the secondary transfer process is performed on the recording paper S on which a recording sheet or the like is used, so that the recording paper S is collectively transferred.

  Image forming means for performing image forming processing according to the rotation of the photosensitive drums 20Y, 20C, 20M, and 20Bk is arranged around each of the photosensitive drums 20Y, 20C, 20M, and 20Bk. Here, a description will be given of the photosensitive drum 20Bk that performs black image formation. A charging device 30Bk that performs an image forming process along the rotation direction of the photosensitive drum 20Bk, a developing device 40Bk, a primary transfer roller 12Bk, And a cleaning device 50Bk. For writing performed after the charging, the optical writing device 60 is used.

  In the superimposition transfer onto the transfer belt 11, the visible images formed on the photosensitive drums 20Y, 20C, 20M, and 20Bk are transferred to the same position on the transfer belt 11 while the transfer belt 11 moves in the A1 direction. Is done. That is, the voltage is applied by the primary transfer rollers 12Y, 12C, 12M, and 12Bk disposed opposite to the photosensitive drums 20Y, 20C, 20M, and 20Bk with the transfer belt 11 interposed therebetween, so that the upstream side in the A1 direction is downstream. The timing is shifted toward.

  The photoconductor drums 20Y, 20C, 20M, and 20Bk are arranged in this order from the upstream side in the A1 direction. The photosensitive drums 20Y, 20C, 20M, and 20Bk are provided in image stations for forming yellow, cyan, magenta, and black images, respectively.

  The image forming apparatus 100 is disposed so as to face four image stations for performing image forming processing for each color, and above the photosensitive drums 20Y, 20C, 20M, and 20Bk, and includes a transfer belt 11 and a primary transfer roller 12Y. , 12C, 12M, and 12Bk, a secondary transfer roller 14 that is a transfer roller that is disposed opposite to the transfer belt 11, is a transfer roller that is driven by the transfer belt 11 and rotates. A cleaning device 13 for the intermediate transfer belt disposed opposite to the transfer belt 11 for cleaning the transfer belt 11, and an optical writing device as an optical writing device disposed below and below these four image stations. And a device 60.

  The optical writing device 60 includes a semiconductor laser as a light source, a coupling lens, an fθ lens, a toroidal lens, a turning mirror, a rotating polygon mirror as a deflecting unit, and the like. The optical writing device 60 writes the writing light Lb corresponding to each of the photosensitive drums 20Y, 20C, 20M, and 20Bk for each color (in FIG. 2, for convenience, only the black image station is assigned a code. However, the same applies to other image stations) to form electrostatic latent images on the photosensitive drums 20Y, 20C, 20M, and 20Bk.

  The image forming apparatus 100 includes a sheet feeding device 70 as a sheet cassette loaded with recording paper S conveyed between the photosensitive drums 20Y, 20C, 20M, and 20Bk and the transfer belt 11, and a sheet feeding device. The recording sheet S conveyed from the feeding device 70 is transferred to the transfer unit 11 between the transfer belt 11 and each of the photosensitive drums 20Y, 20C, 20M, and 20Bk at a predetermined timing corresponding to the timing of forming the toner image by the image station. , And a sensor (not shown) for detecting that the leading end of the recording paper S has reached the pair of registration rollers 81 are provided.

  The image forming apparatus 100 includes a fixing device 1 as a fixing unit for fixing the toner image on the recording sheet S to which the toner image has been transferred, and discharges the fixed recording sheet S to the outside of the main body of the image forming apparatus 100. A paper discharge roller 82, a paper discharge tray 83 which is disposed above the main body of the image forming apparatus 100, and on which recording paper S discharged by the paper discharge roller 82 to the outside of the main body of the image forming apparatus 100 is stacked; , Toner bottles 9Y, 9C, 9M, and 9Bk filled with toners of yellow, cyan, magenta, and black, respectively.

  The transfer belt unit 10 includes, in addition to the transfer belt 11, the primary transfer rollers 12Y, 12C, 12M, and 12Bk, a drive roller 15 around which the transfer belt 11 is wound and a driven roller 16.

  The driven roller 16 also has a function as a tension urging unit for the transfer belt 11. Therefore, the driven roller 16 is provided with an urging unit using a spring or the like. Such a transfer belt unit 10, the primary transfer rollers 12Y, 12C, 12M, and 12Bk, the secondary transfer roller 14, and the cleaning device 13 constitute a transfer device 10A.

  The sheet feeding device 70 is provided at a lower portion of the main body of the image forming apparatus 100, and has a feeding roller 84 as a sheet feeding roller that contacts the upper surface of the uppermost recording sheet S. By rotating the feed roller 84 in the counterclockwise direction, the uppermost recording sheet S is fed toward the registration roller pair 81.

  Although not shown in detail, the cleaning device 13 provided in the transfer device 10A includes a cleaning brush and a cleaning blade disposed so as to face and contact the transfer belt 11. The transfer belt 11 is cleaned by scraping off and removing foreign matters such as residual toner on the transfer belt 11 with a cleaning brush and a cleaning blade.

  The cleaning device 13 has a discharge unit (not shown) for carrying out and discarding the residual toner removed from the transfer belt 11.

  The image forming apparatus 100 further includes an operation panel (not shown) for operating the entire apparatus, and a control unit (not shown) for controlling the entire apparatus.

  When the number of sheets passed, the operation time, the number of revolutions of the endless belt 2, and the like become equal to or more than a predetermined value, the control unit displays on the operation panel that maintenance of the endless belt 2 is necessary (maintenance display), The panel functions as display means. That is, the control unit displays whether or not maintenance is required on the operation panel at predetermined operation intervals. When the maintenance is performed, the control unit stops the maintenance display and restarts counting the number of sheets passed, the operation time, the number of rotations of the endless belt 2, and the like.

[Endless belt]
Next, details of the endless belt 2 used in the fixing device 1 will be described with reference to FIG. On the inner peripheral surface 2A of the endless belt 2, a plurality of rough surface portions 21A to 21E extending along the circumferential direction and a plurality of flat portions 22A to 22D extending along the circumferential direction are formed. The circumferential direction of the endless belt 2 substantially coincides with the traveling direction when the endless belt 2 rotates as described above.

  Each of the plurality of flat portions 22A to 22D is disposed between the plurality of rough surface portions 21A to 21E, and the flat portions 22A to 22D and the rough surface portions 21A to 21E are alternately arranged. That is, the flat portions 22A to 22D are arranged so as to be adjacent to the rough surface portions 21A to 21E in the width direction. The width direction of the endless belt 2 is a direction along the inner peripheral surface 2A and substantially perpendicular to the circumferential direction.

  The surface roughness Rz of the rough surface portions 21A to 21E is preferably 1 μm or more and 10 μm or less, more preferably 3 μm or more and 6 μm or less. If the surface roughness Rz of the rough surface portions 21A to 21E is too small, the amount of the lubricant that can be held in the concave portions of the rough surface portions 21A to 21E decreases, and the lubricant runs short because the endless belt 2 repeats rotation. There is a possibility that the contact area with the nip forming member 5 increases and the coefficient of friction increases.

  On the other hand, if the surface roughness Rz of the rough surface portions 21A to 21E is too large, the convex portions of the rough surface portions 21A to 21E are worn away due to friction, or the lubricant held in the concave portions is hardly supplied to the convex portions. There is a possibility that it will become.

  The surface roughness Rz of the flat portions 22A to 22D is smaller than the surface roughness Rz of the rough surface portions 21A to 21E. The surface roughness Rz of the flat portions 22A to 22D is preferably 1 μm or less, more preferably 0.3 μm or less. If the surface roughness Rz of the flat portions 22A to 22D is too large, the flat portions 22A to 22D become difficult to adhere to the sliding object (stretched member), and the rough surface portion 21A extends over the flat portions 22A to 22D. There is a possibility that the lubricant may easily move between 21E and ２１21E.

  The widthwise dimension of the flat portions 22A to 22D is preferably 0.5 mm or more and 10 mm or less, more preferably 1 mm or more and 6 mm or less. If the widthwise dimensions of the flat portions 22A to 22D are too small, the lubricant may easily move between the rough surface portions 21A to 21E so as to straddle the flat portions 22A to 22D.

  On the other hand, if the widthwise dimensions of the flat portions 22A to 22D are too large, the area of the inner peripheral surface 2A of the endless belt 2 that has a larger friction coefficient than the roughened portions 21A to 21E and is difficult to hold the lubricant becomes larger. As a result, the sliding resistance may be increased.

  In the inner peripheral surface 2A, the total area of the rough surface portions 21A to 21E is larger than the total area of the flat portions 22A to 22D. Thereby, the sliding resistance can be reduced.

[Method for producing endless belt]
The above-mentioned endless belt 2 has a coating step of applying and dripping a coating liquid on an outer peripheral surface 201 of a cylindrical mold 200 as shown in FIG. 4, a drying step of removing a solvent of the coating liquid by heating, It is manufactured by sequentially performing a firing step of imidizing the polyimide precursor by heating and heating, and a releasing step of releasing the formed resin film from the cylindrical mold 200.

  First, details of the cylindrical mold 200 will be described. On the outer peripheral surface 201 of the cylindrical mold 200, a mold rough surface portion 202 extending along the circumferential direction, and a mold flat portion 203 arranged so as to be adjacent to the mold rough surface portion 202 in the axial direction are formed. Have been. In other words, the rough surface portions 21A to 21E are formed on the endless belt 2 by the mold rough surface portion 202, and the flat portions 22A to 22D are formed on the endless belt 2 by the mold flat portion 203.

  The surface roughness Rz of the mold rough surface portion 202 is preferably 1 μm or more and 10 μm or less, more preferably 3 μm or more and 6 μm or less. Further, the surface roughness Rz of the mold flat portion 203 is smaller than the surface roughness Rz of the mold rough surface portion 202. The surface roughness Rz of the mold flat portion 203 is preferably 1 μm or less, more preferably 0.3 μm or less. Further, the axial dimension of the mold flat portion 203 is preferably 0.5 mm or more and 10 mm or less, more preferably 1 mm or more and 6 mm or less. In the outer peripheral surface 201 of the cylindrical mold 200, it is preferable that the total area of the mold rough surface portion 202 is larger than the total area of the mold flat portion 203.

  In the endless belt 2 manufactured by the cylindrical mold 200, the surface roughness Rz of the rough surface portions 21A to 21E is substantially equal to the surface roughness Rz of the mold rough surface portion 202, and the surface roughness of the flat portions 22A to 22D. Rz becomes substantially equal to the surface roughness Rz of the mold flat portion 203.

  Here, a method of forming the mold rough surface portion 202 and the mold flat portion 203 on the outer peripheral surface 201 of the cylindrical mold 200 will be described. First, as shown in FIG. 5, the entire outer peripheral surface is roughened as shown in FIG. 6 by subjecting the cylindrical mold base material 300 to a blast treatment (the whole is referred to as a roughened area 301). The processing for roughening is not limited to the blast processing, but may be cutting, embossing, filing, or the like. If the surface is roughened by blasting, an independent uneven shape having no continuity in a certain direction can be formed.

  In the blasting process, blast particles such as alumina, zirconia, glass beads, steel, and iron powder are sprayed on the outer peripheral surface of the cylindrical mold substrate 300 by compressed air. The blast particles may be spherical particles or irregular particles.

  If spherical blast particles are used, a crater-shaped round concave portion is formed in the roughened region 301. As a result, when the mold rough surface portion 202 is transferred to the endless belt 2 to form the rough surface portions 21A to 21E as described later, a spherical convex portion can be formed, and it is difficult to wear and the frictional resistance is reduced. Low rough surface portions 21A to 21E can be provided. Note that “the convex portion has a spherical shape” means that the surface shape of the convex portion is a part of a spherical surface.

  The cylindrical mold substrate 300 may be plated with chromium, nickel, or the like. It is preferable that the timing of the plating process is before the roughening process so that the recess is not filled by the plating.

  The blasting may be performed while the cylindrical mold substrate 300 and the nozzle 400 for spraying the blast particles are relatively moved. For example, the nozzle 400 may be moved along the axial direction while rotating the cylindrical mold base material 300 about the rotation axis along the axial direction. In this manner, the nozzle 400 may be scanned with respect to the cylindrical mold substrate 300 to roughen the entire outer peripheral surface.

  Next, the outer peripheral surface of the cylindrical mold substrate 300 whose entire surface is roughened is polished along the circumferential direction. That is, as shown in FIG. 7, a flat region 302 is formed on the outer peripheral surface of the cylindrical mold substrate 300. The flat area 302 polished in this manner becomes the flat mold section 203 in the cylindrical mold 200, and the roughened area 301 that is not polished becomes the rough mold section 202. The polishing method may be mechanical polishing such as buff polishing or chemical polishing such as etching.

  As described above, the outer peripheral surface of the cylindrical mold base material 300 is polished after the surface roughening process, so that the mold flat portion 203 has the same height as the bottom of the concave portion of the mold rough surface portion 202. Can be formed. Therefore, in the endless belt 2 to be manufactured, the heights of the convex portions of the rough surface portions 21A to 21E and the flat portions 22A to 22D are substantially equal, and the convex portions and the flat portions 22A to 22D are substantially simultaneously. It can be brought into contact with a sliding object.

  Next, a method for preparing the coating liquid will be described. First, an appropriate amount of carbon black is dispersed in a solution containing a polyimide precursor (polyamic acid) to prepare a carbon black dispersion, and a carbon black dispersion (resin precursor solution) in which the amount of carbon black is appropriately adjusted. ) Is used as the coating liquid.

  In the application step, an appropriate amount of the application liquid 500 may be applied as shown in FIG. 8 so that the endless belt 2 obtained after firing has a desired thickness. In addition, a thin film may be formed in one cycle with the application step, the drying step, and the baking step as one cycle, and a desired film thickness may be obtained by repeating a plurality of cycles.

  In the application step, the application liquid 500 may be applied and drooled by an appropriate method such as centrifugal molding, roll coating, blade coating, ring coating, dipping, spray coating, dispenser coating, and die coating. At this time, it is preferable to employ a roll coat, a dispenser coat, a ring coat, and a die coat in order to impart slidability to the inner surface of the endless belt 2.

  In addition, the thickness of the endless belt 2 is preferably not less than 60 μm and less than 120 μm, and more preferably less than 100 μm. If the endless belt 2 is too thin, the mechanical strength is reduced, cracks and the like may occur, and the durability may be reduced. On the other hand, if the endless belt 2 is too thick, the toughness may be reduced and the durability may be reduced. The endless belt 2 preferably has a small thickness unevenness in order to improve running stability.

  In the drying step, heating may be performed at a temperature of about 80 to 150 ° C. for 10 to 60 minutes using a heating means such as a hot air dryer, an IH heater, and a far infrared heater. In the baking step, for example, using the same heating means, the temperature may be increased at a rate of about 2 to 5 ° C./min following the drying step, and the imidization may be performed at 300 to 400 ° C. Thus, a resin film 600 is formed.

  In the releasing step, the cylindrical mold 200 is cooled. Thereby, the resin film 600 is released from the cylindrical mold 200 as shown in FIG. The endless belt 2 is manufactured by laminating a silicone rubber layer, a fluororesin layer, or the like on the released resin film 600 and performing processing such as cutting an end.

  According to this embodiment, the following effects can be obtained. That is, since the roughened surface portions 21A to 21E are formed on the inner circumferential surface 2A of the endless belt 2, when the lubricant is applied to the inner circumferential surface 2A, the lubricant is held in the concave portions of the roughened surface portions 21A to 21E. The lubricant can be supplied from the concave portion to the convex portion during rotation, and the sliding resistance can be reduced.

  Further, the flat portions 22A to 22D are easily brought into close contact with the sliding object, and the lubricant hardly passes therethrough. By arranging such flat portions 22A to 22D so as to be adjacent to the rough surface portions 21A to 21E in the width direction, the lubricant held on the rough surface portions 21A to 21E does not easily flow in the width direction, When the endless belt 2 rotates repeatedly, the lubricant hardly leaks from the widthwise end. Therefore, the sliding resistance during rotation of the endless belt 2 can be kept low.

  Further, the outer peripheral surface of the cylindrical mold base material 300 is polished after the surface roughening process, and in the endless belt 2 to be manufactured, the convex portions of the rough surface portions 21A to 21E and the flat portions 22A to 22D slide substantially simultaneously. By being able to contact the moving object, it is possible to suppress the movement of the lubricant in the flat portions 22A to 22D while reducing the contact area in the rough surface portions 21A to 21E to reduce the sliding resistance.

[Second embodiment]
The fixing device 1B of the present embodiment is provided in the image forming apparatus 100, and as shown in FIG. 10, the same endless belt 2 as in the first embodiment, a driving roller 801, and a heating unit. , A pressure roller 803, and a pressure pad 804 as a nip forming member.

  The endless belt 2 is stretched around a pressure pad 804 and a driving roller 801 and a heating roller 802 as stretched members. The endless belt 2 runs (rotates) following the rotation of the drive roller 801. Inside the heating roller 802, a heat source 802A including a halogen heater or the like is provided. The heating roller 802 rotates following the endless belt 2.

  The pressure pad 804 is disposed at a position facing the pressure roller 803 via the endless belt 2, and forms a nip portion by pressing the pressure roller 803. The pressure pad 804 is formed such that a metal member such as stainless steel is used as a base material and the surface (sliding surface) is coated with a fluororesin so that sliding resistance is reduced.

  In the illustrated example, it is assumed that the lubricating oil 805 is stored on the upstream side and the downstream side of the pressure pad 804 inside the endless belt 2, but the inner peripheral surface 2 </ b> A of the endless belt 2 is located at other positions. May be supplied with a lubricant.

[Third embodiment]
The fixing device 1C according to the present embodiment is provided in the image forming apparatus 100. As shown in FIG. 11, an endless belt 2 similar to that of the first embodiment, a pressure roller 901 and a stay 902 are provided. , A folder 903, and a heating unit 904.

  The heating means 904 is formed of a heat-generating member such as a PTC element, and is provided on a flat base material 905. The base material 905 is held by a folder 903, and the folder 903 is supported by a stay 902. The surface of the base material 905 on which the heating means 904 is provided is covered with an insulating layer 906 made of, for example, heat-resistant glass. Instead of the insulating layer 906, a thin overcoat layer may be provided.

  The endless belt 2 is sandwiched between the insulating layer 906 of the base material 905 and the pressure roller 901 to form a nip portion. That is, the base material 905 functions as a nip forming member facing the pressure roller 901 via the endless belt 2. That is, in the fixing device 1C of the present embodiment, the nip forming member is provided with the heating means, and the endless belt 2 is heated at the nip portion. The lubricant is supplied to the inner peripheral surface 2A of the endless belt 2 as in the first embodiment.

[Fourth embodiment]
The fixing device 1D according to the present embodiment is provided in the image forming apparatus 100. As shown in FIG. 12, the same endless belt 2 as in the first embodiment, a pressure roller 901 and a stay 902 are provided. , A heating means 904, an auxiliary stay 907, a nip forming member 908, and a pressing roller 909.

  The nip forming member 908 is supported by the stay 902 and faces the pressure roller 901 via the endless belt 2 to form a nip portion. The auxiliary stay 907 is supported by the stay 902 on the opposite side of the nip forming member 908. The base 905 provided with the heating means 904 is supported by the auxiliary stay 907.

  The pressing roller 909 is disposed on the opposite side of the pressing roller 901 with respect to the stay 902, and sandwiches the endless belt 2 between the pressing roller 909 and the insulating layer 906 of the base material 905. That is, the endless belt 2 is heated while being sandwiched between the base material 905 and the pressing roller 909 on the side opposite to the pressing roller 901.

[Fifth Embodiment]
The fixing device 1E of the present embodiment is provided in the image forming apparatus 100. As shown in FIG. 13, an endless belt 2 similar to that of the first embodiment, a pressure roller 901 and a stay 902 are provided. , A heating means 904 </ b> B, an auxiliary stay 907, and a nip forming member 908.

  In the present embodiment, instead of the flat base material 905 as in the fourth embodiment, a base material 905B formed in an arc-shaped cross section in accordance with the curvature of the endless belt 2 is provided. The heating means 904B and the insulating layer 906B are also formed in an arc cross section corresponding to the shape of the base material 905B. Thereby, the insulating layer 906B of the base material 905B extends along the inner circumferential surface 2A of the endless belt 2, and the length of the contact portion in the circumferential direction is longer than that of the configuration using the flat base material. ing. Note that, also in the present embodiment, a pressing roller 909 may be provided.

[Sixth embodiment]
The fixing device 1F according to the present embodiment is provided in the image forming apparatus 100. As shown in FIG. 14, an endless belt 2 similar to that of the first embodiment, a pressure roller 901 and a stay 902 are provided. , A folder 903, a heating unit 904, a nip forming member 908, a second stay 910, and a heating belt 911, and a fixing belt and a heating belt are provided separately.

  The heating belt 911 has the same configuration as the endless belt 2, for example, and is arranged around the stay 902. Thus, the heat generated by the heating unit 904 is transmitted to the pressure roller 901 via the heating belt 911. Since the pressure roller 901 is in contact with the endless belt 2, the endless belt 2 is heated by the heating unit 904 via the heating belt 911 and the pressure roller 901.

  The nip forming member 908 is supported by the second stay 910, and the endless belt 2 is disposed around the nip forming member 908. Recording paper is passed through a nip formed by the pressure roller 901 and the nip forming member 908.

  According to the above-described second to sixth embodiments, similarly to the first embodiment, the roughened portions 21A to 21E and the flat portions 22A to 22D are formed on the inner peripheral surface 2A of the endless belt 2. Thus, the sliding resistance during rotation of the endless belt 2 can be kept low.

  The present invention is not limited to the above-described embodiment, but includes other configurations and the like that can achieve the object of the present invention, and includes the following modifications and the like.

  For example, in the above-described embodiment, five rough surface portions 21A to 21E are formed on the inner peripheral surface 2A of the endless belt 2 and four flat portions 22A to 22D are formed, but the rough surface portion and the flat portion are formed. The number may be set appropriately. Moreover, even if the number of flat parts is more than the number of rough surface parts, that is, the width direction edge may be a flat part on the inner peripheral surface of the endless belt.

  In addition, the best configuration and method for carrying out the present invention have been disclosed in the above description, but the present invention is not limited to this. That is, although the present invention has been particularly shown and described with particular reference to particular embodiments, the present invention will be understood by those skilled in the art without departing from the spirit and scope of the invention. The trader can make various modifications.

  Therefore, the description in which the shapes, materials, and the like disclosed above are limited is merely illustrative for facilitating the understanding of the present invention, and does not limit the present invention. A description of a part of a member excluding some or all of the restrictions such as the shape and the material is included in the present invention.

[Processing of cylindrical mold]
A glass substrate having an outer diameter of 120 mm and a length (axial dimension) of 450 mm was blasted using glass bead particles as blast particles to roughen the entire outer peripheral surface. Then, a flat portion was formed by polishing the blasted surface in a belt shape.

[Preparation of polyimide precursor coating liquid]
MA100 (manufactured by Mitsubishi Chemical Corporation), U Varnish S (manufactured by Ube Industries), and N-methyl-2-pyrrolidone were used as the constituent materials of the acidic carbon black dispersion, and these were rotated at a rotational speed of 1500 rpm by a ball mill. For about 10 minutes to obtain an acidic carbon black dispersion.

  Further, Ketjen Black EC300J, U Varnish S (manufactured by Ube Industries, Ltd.) and N-methyl-2-pyrrolidone were used as conductive carbon black dispersion constituent materials, and these were stirred for about 10 minutes by a ball mill. And a conductive carbon black dispersion.

  The coating liquid was obtained by mixing the acidic carbon black dispersion and the conductive carbon black dispersion, mixing and defoaming with a centrifugal stirring defoaming machine.

[Belt molding method]
The cylindrical mold subjected to the surface treatment as described above was used as a mold, and attached to a roll coat coating apparatus. Next, the coating liquid was poured into a pan, and the coating liquid was pumped up by an application roller to control the thickness of the coating liquid on the application roller. The coating liquid on the coating roller was uniformly transferred and coated on the outer peripheral surface of the cylindrical mold, and then charged into a hot-air circulating dryer while rotating the cylindrical mold, heated, and stopped. . After that, it was introduced into a heating furnace (firing furnace) capable of high-temperature processing and subjected to heat processing (firing). The polyimide resin (resin film) cured by imide curing by firing was released from the cylindrical mold while being pulled out from the mold, thereby forming an endless belt made of polyimide resin.

[Evaluation test]
The performance of the endless belt produced as described above was evaluated using a test apparatus 701 shown in FIG. The test apparatus 701 includes a drive roller 703, a nip forming member 704, tension rollers 705 and 706, and a pressure roller 707. The test was performed by stretching the endless belt 2 around the driving roller 703, the nip forming member 704, and the tension rollers 705 and 706.

  The nip forming member 704 is formed of a fluororesin, and has an inner peripheral surface subjected to embossing. The tension rollers 705 and 706 are rollers around which the endless belt 2 is stretched. The tension rollers 705 and 706 are disposed between the driving roller 703 and the nip forming member 704. Is given. The endless belt 2 was sandwiched between the nip forming member 704 and the pressure roller 707 facing the outer peripheral surface of the belt, and a fixed amount of lubricating oil was applied as a lubricant to the inner peripheral surface 2A.

  When the endless belt 2 is driven by rotating the drive roller 703, friction occurs between the inner peripheral surface 2A and the nip forming member 704. The motor torque required to drive the drive roller 703 was evaluated initially and after 100 hours of driving.

[Test results]
For the endless belts of Examples 1 to 9, Table 1 shows the surface roughness Rz and the width dimension in the rough surface portion and the surface roughness Rz and the width dimension in the flat portion. Table 1 also shows the results of the above evaluation tests.

  In all of Examples 1 to 9, the required increase in motor torque after driving for 100 hours was small, and good results were obtained. In particular, in Examples 1 to 4, good results were obtained.

DESCRIPTION OF SYMBOLS 1 Fixing apparatus 2 Endless belt 2A Inner peripheral surface 21A-21E Rough surface part 22A-22D Flat part 3 Heating means 4 Pressure roller 5 Nip forming member 6 Support member (stay)
705, 706 tension roller (tensile member)
DESCRIPTION OF SYMBOLS 100 Image forming apparatus 200 Cylindrical mold 201 Outer peripheral surface 202 Mold rough surface part 203 Mold flat part 300 Cylindrical mold base material 600 Resin film

JP-A-2004-109665

Claims (12)

An endless belt used for a fixing device,
A rough surface portion extending along the circumferential direction, and a flat portion that is arranged adjacent to the rough surface portion in the width direction and has a smaller surface roughness Rz than the rough surface portion are formed on the inner circumferential surface. Endless belt.   2. The endless belt according to claim 1, wherein the surface roughness Rz of the rough surface portion is 1 μm or more and 10 μm or less, and the surface roughness Rz of the flat portion is 1 μm or less. 3.   The method according to claim 1, wherein a total area of the rough surface portion is larger than a total area of the flat portion.   The endless belt according to any one of claims 1 to 3, wherein a width dimension of the flat portion is 0.5 mm or more and 10 mm or less. An endless belt according to any one of claims 1 to 4,
A pressure roller arranged to face the endless belt,
Heating means for heating the endless belt,
A nip forming member facing the pressure roller via the endless belt,
A stay that supports the nip forming member. An endless belt according to any one of claims 1 to 4,
A pressure roller arranged to face the endless belt,
Heating means for heating the endless belt,
A nip forming member facing the pressure roller via the endless belt,
The fixing device according to claim 1, wherein the endless belt is stretched between the nip forming member and at least one other stretched member.   An image forming apparatus comprising the fixing device according to claim 5. An endless belt manufacturing method for manufacturing an endless belt used in a fixing device,
A mold rough surface portion extending along the circumferential direction, and a mold flat portion that is disposed adjacent to the mold rough surface portion in the axial direction and has a smaller surface roughness Rz than the mold rough surface portion. For a cylindrical mold having a surface, a resin precursor solution is applied to the outer peripheral surface,
A method for producing an endless belt, wherein a resin film is formed by drying and baking the resin precursor solution.   9. The endless belt according to claim 8, wherein the surface roughness Rz of the mold rough surface portion is 1 μm or more and 10 μm or less, and the surface roughness Rz of the mold flat portion is 1 μm or less. Production method.   The method for producing an endless belt according to claim 8, wherein a total area of the mold rough surface portion is larger than a total area of the mold flat portion.   The method for producing an endless belt according to any one of claims 8 to 10, wherein an axial dimension of the flat mold portion is 0.5 mm or more and 10 mm or less.   After the outer peripheral surface of the cylindrical mold base material is roughened by blasting, the cylindrical mold having the rough mold portion and the flat mold portion is formed by polishing along the circumferential direction. The method for producing an endless belt according to any one of claims 8 to 11, wherein:

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