JP2006091531A - Fixing device, belt tubular body and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device which forms high-quality fixed images, while suppressing wrinkles in paper and image defects, such as image shifts and image stain. <P>SOLUTION: The fixing device 60 for fixing a toner image carried on a recording material is equipped with a fixing roll 61, an endless belt 62 which moves as in contact with the fixing roll 61 and which is composed of a single layer prepared by compounding 100 parts by weight of a fluorocarbon resin, such as polytetrafluoroethylene resin and 10 to 40 parts by weight of a reinforcing filler, such as acicular whiskers. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fixing device and the like, and more particularly to a fixing device used in an image forming apparatus using an electrophotographic system.

  In an image forming apparatus such as a copying machine or a printer using an electrophotographic method, for example, a photosensitive member (photosensitive drum) formed in a drum shape is uniformly charged, and the photosensitive drum is controlled based on image information. An electrostatic latent image is formed on the photosensitive drum by exposure with the exposed light. The electrostatic latent image is converted into a visible image (toner image) with toner, and the toner image is transferred onto the recording paper from the photosensitive drum, and then the toner image is fixed on the recording paper with a fixing device.

  A fixing device used in such an image forming apparatus includes a heat source inside a cylindrical metal core, and is formed by laminating a heat-resistant elastic layer on the metal core and a release layer on the outer peripheral surface thereof. The fixing roll is placed in pressure contact with the fixing roll, and is formed by laminating a heat-resistant elastic body layer on the core metal and a release layer made of a heat-resistant resin film or a heat-resistant rubber film on the outer peripheral surface. And a pressure roll. Then, the recording paper carrying the unfixed toner image is passed between the fixing roll and the pressure roll, and the unfixed toner image is heated and pressed to thereby form the toner image on the recording paper. It has become established. Such a fixing device is called a roll nip method and is generally widely used.

In recent years, with the progress of high productivity and colorization in image forming apparatuses, it has been required that fixing apparatuses also support high speed. At that time, in the roll nip type fixing device, it is necessary to set the nip width widely in proportion to the fixing speed so that a sufficient amount of heat can be supplied to the toner and the recording paper. In response to such a request, the present applicant has proposed a technique related to a fixing device that can cope with the speeding up of the image forming apparatus (see, for example, Patent Document 1).
That is, the fixing device described in Patent Document 1 is disposed in a non-rotating state inside a rotatable fixing roll whose surface is elastically deformed, an endless belt that can run while being in contact with the fixing roll, and the endless belt. The endless belt is pressed against the fixing roll so that a contact surface with the fixing roll is formed, and the sheet can be passed between the endless belt and the fixing roll. In addition, a belt nip is provided on the surface of the fixing roll, and the exit side of the sheet is locally elastically deformed on the surface of the fixing roll.

  In such a fixing device described in Patent Document 1 (referred to as “belt nip method”), a pressure pad is used instead of the pressure roll in the conventional roll nip type fixing device, and the endless belt is pressed against the fixing roll. Yes. By adopting such a configuration, the width of the belt nip formed by the fixing roll and the endless belt can be easily made larger than the width of the conventional roll nip between the fixing roll and the pressure roll. In addition, since a uniform and high nip pressure can be applied to the nip portion, it is possible to cope with a high speed, and it is easy to downsize the apparatus.

  Further, since the heat capacity of the endless belt pressed against the fixing roll is small, and the pressure pad is arranged in a non-rotating state, a configuration in which the heat transmitted from the fixing roll is hardly dissipated to the outside is realized. Therefore, even when rotation of the fixing roll is started, the amount of heat taken from the fixing roll to the endless belt side is small, the thermal efficiency at the time of melting the toner can be increased, and the temperature drop at the belt nip is also small. There is also an advantage that the fixing property of the toner is improved.

  In such a belt nip type fixing device, it is indispensable to prevent a slip between the fixing roll and the recording paper and a slip between the recording paper and the endless belt in order to ensure an excellent fixed image and fixability. . For this reason, a method is adopted in which a release layer made of a fluororesin is provided on the surface of the base material layer of the endless belt made of polyimide resin or the like to improve the releasability from the toner image. Furthermore, as a method of reducing the friction coefficient μc between the endless belt and the pressure pad as compared with the friction coefficient μa between the fixing roll and the recording paper or the friction coefficient μb between the recording paper and the endless belt, for example, a fluororesin is formed on the pressure pad. A method has been reported in which a low-friction film made of a glass fiber sheet impregnated with bismuth is provided, and a modified silicone oil is interposed as a lubricant between the low-friction film and the endless belt (see Patent Document 2).

  On the other hand, the endless belt needs to have predetermined strength and elasticity. In particular, since the end portion of the endless belt rotates while being rubbed in contact with the pressure pad which is a non-rotating portion, sufficient flexibility and toughness are required. For this reason, the structure of the endless belt is composed of an inner layer in which an insulating inorganic filler is blended with a heat-resistant resin such as polyimide, an intermediate layer in which a conductive filler is blended in an adhesive resin, and an outer layer in which a conductive filler is blended in a fluororesin A method of forming a multilayer structure consisting of the above has been reported (see Patent Document 3).

Japanese Patent No. 3298354 (page 4-7) JP-A-10-213984 Japanese Patent No. 3351057

  By the way, as described above, the endless belt used in the belt nip type fixing device is usually a separation layer provided on the side of the endless belt that is in pressure contact with the base material layer made of a heat-resistant resin such as polyimide. The mold layer is configured to improve the releasability from the toner image. On the other hand, the side of the endless belt opposite to the side pressed against the fixing roll presses a pressure pad provided with a low friction film on the surface of a base material made of a heat resistant resin such as polyimide.

  However, the surface of the substrate made of polyimide resin or the like constituting the endless belt has a higher coefficient of friction than the surface of the release layer made of fluororesin, and therefore, the sliding resistance between the endless belt and the pressure pad is high. There's a problem. For this reason, for example, as described in Patent Document 2, when a low friction film impregnated with a fluororesin is provided on the surface of the pressure pad, this sliding resistance is reduced to some extent. Further improvement is necessary to increase the speed.

Further, the endless belt usually has a two-layer structure of a base material made of a heat resistant resin such as polyimide and a release layer provided on the endless belt on the side pressed against the fixing roll. Furthermore, as described in Patent Document 3, a multi-layered endless belt composed of an inner layer / intermediate layer / outer layer has also been reported in order to increase rigidity while ensuring flexibility and toughness of the endless belt. .
However, when the structure of the endless belt is such a multilayer structure, there are problems that many steps are required in the production thereof and productivity is lowered.

The present invention has been made to solve the technical problems as described above.
That is, an object of the present invention is to provide a fixing device that forms a high-quality fixed image while suppressing the occurrence of image defects such as the occurrence of paper wrinkles, image displacement, and image smearing.
Another object of the present invention is to provide a belt tubular body for a fixing device that is reduced in manufacturing cost and improved in production efficiency.
Furthermore, another object of the present invention is to provide an image forming apparatus that forms a high-quality fixed image.

  That is, according to the present invention, there is provided a fixing device for fixing a toner image carried on a recording material, which moves while in contact with a rotating member, and contains a fluororesin and a reinforcing filler. And a belt member composed of a single layer.

Here, the belt member preferably has a thickness of 80 μm to 500 μm. The arithmetic average roughness of the belt member surface is preferably 10 μm or less.
Furthermore, the fixing device preferably includes a heating member that heats the rotating member or the belt member.

Next, according to the present invention, a belt tubular body used in a fixing device for fixing a toner image carried on a recording material, comprising a single layer formed by blending a fluororesin and a reinforcing filler. A belt tubular body is provided.
Here, the fluororesin constituting the belt tubular body is preferably a polytetrafluoroethylene resin or a tetrafluoroethylene-perfluoroalkyl vinyl ether resin. The reinforcing filler is preferably an acicular filler, a layered filler, or a fibrous filler.
The blending amount of the fluororesin and the reinforcing filler forming such a single layer is preferably 100 parts by weight of the fluororesin and 10 to 40 parts by weight of the reinforcing filler with respect to the fluororesin.

  Furthermore, according to the present invention, a toner image forming unit that forms a toner image, a transfer unit that transfers a toner image formed by the toner image forming unit onto a recording material, and a toner image that is transferred onto the recording material are recorded. A fixing means for fixing to the material, the fixing means being disposed inside the belt member, the belt member movable while being in contact with the rotation member, and pressing the belt member against the rotation member. And a pressure member that forms a nip portion through which the recording material passes between the rotating member and the belt member, and the belt member is an image composed of a single layer formed by blending a fluororesin and a reinforcing filler. A forming apparatus is provided.

  Thus, according to the present invention, it is possible to obtain a fixing device that forms a high-quality fixed image while suppressing the occurrence of image defects such as the occurrence of paper wrinkles, image displacement, and image smearing.

The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described below in detail with reference to the accompanying drawings. The present invention is not limited to the present embodiment.
(First embodiment)
FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus to which the exemplary embodiment is applied. FIG. 1 shows an intermediate transfer type image forming apparatus generally called a tandem type. The image forming apparatus shown in FIG. 1 includes a plurality of image forming units 1Y, 1M, 1C, and 1K on which toner images of respective color components are formed by an electrophotographic method, and the image forming units 1Y, 1M, 1C, and 1K. The primary transfer unit 10 that sequentially transfers (primary transfer) the formed color component toner images to the intermediate transfer belt 15 and the superimposed toner image transferred onto the intermediate transfer belt 15 onto a sheet P that is a recording material (recording sheet). A secondary transfer unit 20 that performs batch transfer (secondary transfer) and a fixing device 60 that fixes the secondary transferred image on the paper P are provided. Moreover, it has the control part 40 which controls operation | movement of each apparatus (each part).

  In the present embodiment, each of the image forming units 1Y, 1M, 1C, and 1K includes a charger 12 that charges the photosensitive drum 11 around the photosensitive drum 11 that rotates in the direction of arrow A, and a photosensitive drum. A laser exposure unit 13 for writing an electrostatic latent image on the image 11 (in FIG. 1, the exposure beam is indicated by a symbol Bm), and each color component toner is accommodated so that the electrostatic latent image on the photosensitive drum 11 can be transferred with the toner. A developing device 14 for visualizing, a primary transfer roll 16 for transferring each color component toner image formed on the photosensitive drum 11 to the intermediate transfer belt 15 in the primary transfer unit 10, and residual toner on the photosensitive drum 11. The drum cleaner 17 from which the toner is removed and the electrophotographic device such as the like are sequentially arranged. These image forming units 1Y, 1M, 1C, and 1K are arranged substantially linearly in the order of yellow (Y), magenta (M), cyan (C), and black (K) from the upstream side of the intermediate transfer belt 15. Has been.

The intermediate transfer belt 15 as an intermediate transfer member is constituted by a film-like endless belt in which an appropriate amount of an antistatic agent such as carbon black is contained in a resin such as polyimide or polyamide. The volume resistivity is 10 ⁶ Ωcm to 10 ¹⁴ Ωcm, and the thickness is, for example, about 0.1 mm. The intermediate transfer belt 15 is circulated and driven (rotated) at a predetermined speed in the direction B shown in FIG. 1 by various rolls. As these various rolls, a drive roll 31 that is driven by a motor (not shown) having excellent constant speed and rotates the intermediate transfer belt 15, and extends substantially linearly along the arrangement direction of the photosensitive drums 11. A support roll 32 that supports the intermediate transfer belt 15, a tension roll 33 that functions as a correction roll that applies a constant tension to the intermediate transfer belt 15 and prevents the intermediate transfer belt 15 from meandering, and the secondary transfer unit 20. A backup roll 25 provided; and a cleaning backup roll 34 provided in a cleaning unit that scrapes off residual toner on the intermediate transfer belt 15.

The primary transfer unit 10 includes a primary transfer roll 16 that is disposed to face the photosensitive drum 11 with the intermediate transfer belt 15 interposed therebetween. The primary transfer roll 16 includes a shaft and a sponge layer as an elastic layer fixed around the shaft. The shaft is, for example, a cylindrical bar made of a metal such as iron or SUS. The sponge layer is made of, for example, a blend rubber of acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), and ethylene-propylene-diene rubber (EPDM) containing a conductive agent such as carbon black, and has a volume resistivity. Is a sponge-like cylindrical roll of 10 ⁷ Ωcm to 10 ⁹ Ωcm. The primary transfer roll 16 is disposed in pressure contact with the photosensitive drum 11 with the intermediate transfer belt 15 interposed therebetween. Further, the primary transfer roll 16 has a polarity opposite to the toner charging polarity (negative polarity; the same applies hereinafter). A voltage (primary transfer bias) is applied. As a result, the toner images on the respective photosensitive drums 11 are sequentially electrostatically attracted to the intermediate transfer belt 15 so as to form superimposed toner images on the intermediate transfer belt 15.

The secondary transfer unit 20 includes a secondary transfer roll 22 disposed on the toner image carrying surface side of the intermediate transfer belt 15 and a backup roll 25. The backup roll 25 includes an inner layer portion made of EPDM rubber and a tubular surface layer made of a blend rubber of EPDM and NBR in which carbon is dispersed. The surface resistivity is 10 ⁷ Ω / □ to 10 ¹⁰ Ω / □, and the hardness is set to 70 ° (Asker C), for example. The backup roll 25 is disposed on the back side of the intermediate transfer belt 15 to form a counter electrode of the secondary transfer roll 22, and a metal power supply roll 26 to which a secondary transfer bias is stably applied is disposed in contact with the backup roll 25. ing.

On the other hand, the secondary transfer roll 22 includes a shaft and a sponge layer as an elastic layer fixed around the shaft. The shaft is, for example, a cylindrical bar made of a metal such as iron or SUS. The sponge layer is a sponge-like cylindrical roll formed of a blend rubber of NBR, SBR, and EPDM blended with a conductive agent such as carbon black and having a volume resistivity of 10 ⁷ Ωcm to 10 ⁹ Ωcm. The secondary transfer roll 22 is placed in pressure contact with the backup roll 25 with the intermediate transfer belt 15 interposed therebetween. Further, the secondary transfer roll 22 is grounded and a secondary transfer bias is formed between the secondary transfer roll 22 and the backup roll 25. The toner image is secondarily transferred onto the paper P conveyed to the next transfer unit 20.

  Further, on the downstream side of the secondary transfer portion 20 of the intermediate transfer belt 15, an intermediate transfer belt that removes residual toner and paper dust on the intermediate transfer belt 15 after the secondary transfer and cleans the surface of the intermediate transfer belt 15. A cleaner 35 is provided so as to be able to contact and separate. On the other hand, on the upstream side of the yellow image forming unit 1Y, a reference sensor (home position sensor) 42 that generates a reference signal for taking an image forming timing in each of the image forming units 1Y, 1M, 1C, and 1K is disposed. ing. Further, an image density sensor 43 for adjusting image quality is disposed on the downstream side of the black image forming unit 1K. The reference sensor 42 recognizes a predetermined mark provided on the back side of the intermediate transfer belt 15 and generates a reference signal. Each image forming unit is instructed by an instruction from the control unit 40 based on the recognition of the reference signal. 1Y, 1M, 1C, and 1K are configured to start image formation.

  Furthermore, in the image forming apparatus according to the present embodiment, as a paper transport system, a paper tray 50 that stores paper P, and a pick-up roll 51 that picks up and transports the paper P collected on the paper tray 50 at a predetermined timing; The transfer roll 52 that transports the paper P fed by the pickup roll 51, the transport chute 53 that feeds the paper P transported by the transport roll 52 to the secondary transfer unit 20, and the secondary transfer by the secondary transfer roll 22. A conveyance belt 55 that conveys the sheet P conveyed after the transfer to the fixing device 60 and a fixing entrance guide 56 that guides the sheet P to the fixing device 60 are provided.

Next, a basic image forming process of the image forming apparatus according to the present embodiment will be described.
In the image forming apparatus as shown in FIG. 1, image data output from an image reading device (IIT) (not shown), a personal computer (PC) (not shown), or the like is received by an image processing device (IPS) (see FIG. 1). The image forming operation is performed by the image forming units 1Y, 1M, 1C, and 1K. In IPS, the input reflectance data is subjected to predetermined image processing such as shading correction, position shift correction, brightness / color space conversion, gamma correction, frame deletion, color editing, moving editing, and other various image editing. Is done. The image data that has undergone image processing is converted into color material gradation data of four colors, Y, M, C, and K, and is output to the laser exposure unit 13.

  The laser exposure unit 13 irradiates, for example, the photosensitive drum 11 of each of the image forming units 1Y, 1M, 1C, and 1K with an exposure beam Bm emitted from a semiconductor laser in accordance with the input color material gradation data. ing. In each of the photosensitive drums 11 of the image forming units 1Y, 1M, 1C, and 1K, the surface is charged by the charger 12, and then the surface is scanned and exposed by the laser exposure unit 13 to form an electrostatic latent image. The formed electrostatic latent images are developed as toner images of respective colors Y, M, C, and K by the respective image forming units 1Y, 1M, 1C, and 1K.

  The toner images formed on the photosensitive drums 11 of the image forming units 1Y, 1M, 1C, and 1K are transferred onto the intermediate transfer belt 15 in the primary transfer unit 10 where the photosensitive drums 11 and the intermediate transfer belt 15 come into contact with each other. Transcribed. More specifically, in the primary transfer unit 10, a voltage (primary transfer bias) having a polarity opposite to the charging polarity (negative polarity) of the toner is applied to the base material of the intermediate transfer belt 15 by the primary transfer roll 16. Primary transfer is performed by sequentially superposing the toner images on the surface of the intermediate transfer belt 15.

  After the toner images are sequentially primary transferred onto the surface of the intermediate transfer belt 15, the intermediate transfer belt 15 moves and the toner image is conveyed to the secondary transfer unit 20. When the toner image is transported to the secondary transfer unit 20, in the paper transport system, the pick-up roll 51 rotates in accordance with the timing at which the toner image is transported to the secondary transfer unit 20, and the paper of a predetermined size is transferred from the paper tray 50. P is supplied. The paper P supplied by the pickup roll 51 is transported by the transport roll 52 and reaches the secondary transfer unit 20 via the transport chute 53. Before reaching the secondary transfer unit 20, the paper P is temporarily stopped, and a registration roll (not shown) rotates in accordance with the movement timing of the intermediate transfer belt 15 on which the toner image is carried. And the position of the toner image are aligned.

  In the secondary transfer unit 20, the secondary transfer roll 22 is pressed against the backup roll 25 via the intermediate transfer belt 15. At this time, the sheet P conveyed at the same timing is sandwiched between the intermediate transfer belt 15 and the secondary transfer roll 22. At this time, when a voltage (secondary transfer bias) having the same polarity as the toner charging polarity (negative polarity) is applied from the power supply roll 26, a transfer electric field is formed between the secondary transfer roll 22 and the backup roll 25. Is done. The unfixed toner image carried on the intermediate transfer belt 15 is collectively electrostatically transferred onto the paper P in the secondary transfer unit 20 pressed by the secondary transfer roll 22 and the backup roll 25. .

Thereafter, the sheet P on which the toner image has been electrostatically transferred is transported as it is while being peeled off from the intermediate transfer belt 15 by the secondary transfer roll 22, and transported downstream of the secondary transfer roll 22 in the sheet transport direction. It is conveyed to the belt 55. The conveyance belt 55 conveys the paper P to the fixing device 60 in accordance with the optimum conveyance speed in the fixing device 60. The unfixed toner image on the paper P conveyed to the fixing device 60 is fixed on the paper P by being subjected to a fixing process by heat and pressure by the fixing device 60. Then, the paper P on which the fixed image is formed is conveyed to a paper discharge placement unit provided in a discharge unit of the image forming apparatus.
On the other hand, after the transfer onto the paper P is completed, the residual toner remaining on the intermediate transfer belt 15 is conveyed to the cleaning unit as the intermediate transfer belt 15 rotates, and the cleaning backup roll 34 and the intermediate transfer belt cleaner 35 are transferred. Is removed from the intermediate transfer belt 15.

Next, the fixing device 60 used in the image forming apparatus of the present embodiment will be described.
FIG. 2 is a cross-sectional side view illustrating the configuration of the fixing device 60 to which the exemplary embodiment is applied. The fixing device 60 includes a fixing roll 61 as an example of a rotating member, an endless belt 62 as an example of a belt member, and a pressure pad as an example of a pressure member pressed from the fixing roll 61 via the endless belt 62. 64 constitutes a main part.

The fixing roll 61 is a cylindrical roll configured by laminating a heat-resistant elastic body layer 612 and a release layer 613 around a metal core (cylindrical cored bar) 611, and is rotatably supported. It rotates at a predetermined surface speed (for example, 194 mm / sec). The fixing roll 61 of the present embodiment is formed of a so-called straight roll whose outer diameter is uniform in the axial direction.
Inside the fixing roll 61, for example, a halogen heater 66 having a rating of 600 W is disposed as a heat source. On the other hand, a temperature sensor 69 is disposed in contact with the surface of the fixing roll 61. The control unit 40 of the image forming apparatus controls the lighting of the halogen heater 66 based on the temperature measurement value by the temperature sensor 69 so that the surface temperature of the fixing roll 61 maintains a predetermined set temperature (for example, 175 ° C.). It is adjusted to.

  The endless belt 62 is a seamless endless belt whose original shape is formed in a cylindrical shape so that a defect due to the seam does not occur in the output image. The endless belt 62 includes a pressure pad 64 and a belt guide member 63 arranged inside the endless belt 62, and edge guide members 80 (see FIG. 3 in the subsequent stage) arranged at both ends of the endless belt 62. It is supported rotatably. And it arrange | positions so that it may press-contact with the fixing roll 61 in the nip part N, and it follows the fixing roll 61 and rotates (for example, 194 mm / sec).

Here, FIG. 3 is a diagram illustrating a configuration in which the endless belt 62 is supported. FIG. 3 shows one end region of the fixing device 60 viewed from the downstream side in the transport direction of the paper P.
As shown in FIG. 3, edge guide members 80 are disposed at both ends of the holder 65 disposed inside the endless belt 62. The edge guide member 80 is provided in a cylindrical shape in which notches are formed in a portion corresponding to the nip portion N and the vicinity thereof, that is, a belt traveling guide portion 801 having a C-shaped cross section, and an outer side of the belt traveling guide portion 801. A flange portion 802 formed with an outer diameter larger than the outer diameter of the endless belt 62, and a holding portion for positioning and fixing the edge guide member 80 to the main body of the fixing device 60 provided further outside the flange portion 802. 803.

  At both ends of the endless belt 62, the inner peripheral surfaces of both ends are supported by the outer peripheral surface of the belt traveling guide portion 801 except for the nip portion N and the vicinity thereof, and the endless belt 62 is supported by the outer periphery of the belt traveling guide portion 801. Rotate along the surface. Accordingly, the belt traveling guide portion 801 is formed of a material having a small friction coefficient so that the endless belt 62 can smoothly rotate, and further has a low thermal conductivity so that it is difficult to remove heat from the endless belt 62. It is made of material.

  Further, the flange portion 802 is disposed such that inner surfaces of both flange portions 802 disposed so as to face each other at both end portions of the holder 65 have an interval substantially matching the width of the endless belt 62. When the endless belt 62 rotates, the end of the endless belt 62 abuts against the inner surface of the flange portion 802, so that the movement of the endless belt 62 in the width direction (belt walk) is limited. . As described above, the endless belt 62 is supported by the edge guide member 80 so that the deviation is regulated.

Further, the endless belt 62 is supported by the pressure pad 64 and the belt guide member 63 in the longitudinal region excluding both ends of the endless belt 62 (see also FIG. 2). In the region excluding both ends of the endless belt 62, the inner peripheral surface of the endless belt 62 rotates while sliding on the pressure pad 64 and the belt guide member 63.
The belt guide member 63 is attached to a holder 65 disposed inside the endless belt 62 along the longitudinal direction. The belt guide member 63 is formed with a plurality of ribs in the rotational direction of the endless belt 62 so as to minimize the contact area with the inner peripheral surface of the endless belt 62. Further, the belt guide member 63 is made of a material having a low coefficient of friction so that the endless belt 62 can smoothly rotate, and a material having a low thermal conductivity so that it is difficult to remove heat from the endless belt 62. Is formed. Specifically, a heat resistant resin such as tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) or polyphenylene sulfide (PPS) is used.

  Next, the pressure pad 64 is supported by a metal holder 65 inside the endless belt 62. Then, it is arranged in a state of being pressed against the fixing roll 61 via the endless belt 62, and forms a nip portion N with the fixing roll 61. In the pressure pad 64, a pre-nip member 64 a for securing a wide nip portion N is disposed on the inlet side (upstream side) of the nip portion N. Further, on the outlet side (downstream side) of the nip portion N, the surface of the fixing roll 61 is locally pressed to smooth the surface of the toner image and impart image gloss, and the surface of the fixing roll 61 is distorted (dented). ), And a peeling nip member 64b for forming a down curl on the paper P is disposed.

Further, the pressure pad 64 is provided with a low friction sheet 68 as an example of a rubbing member on the surface in contact with the endless belt 62 in order to reduce the sliding resistance between the inner peripheral surface of the endless belt 62 and the pressure pad 64. It has been.
The low friction sheet 68 is fixed to the holder 65 at the upstream end of the nip portion N by a low friction sheet fixing member 68a. And it is arrange | positioned over the whole region of the nip part N in the state clamped between the pressure pad 64 and the inner peripheral surface of the endless belt 62 along the rotation direction of the endless belt 62. The downstream side of the nip portion N of the low friction sheet 68 is not fixed and set to a free end (free) state so that the low friction sheet 68 is not distorted. The low friction sheet 68 has a sliding resistance between the inner peripheral surface of the endless belt 62 and the pressure pad 64 under a state in which a pressing force is applied between the pressure pad 64 and the fixing roll 61 at the nip portion N. (Friction resistance) is reduced.

  In such a configuration, the fixing roll 61 is connected to a drive motor (not shown) and rotates in the direction of arrow C, and the endless belt 62 rotates in the same direction as the fixing roll 61 following this rotation. The sheet P on which the toner image is electrostatically transferred in the secondary transfer unit 20 of the image forming apparatus shown in FIG. 1 is guided by the fixing inlet guide 56 and conveyed to the nip N. When the paper P passes through the nip portion N, the toner image on the paper P is fixed by the pressure acting on the nip portion N and the heat supplied from the fixing roll 61. In the fixing device 60 of the present embodiment, since the nip portion N can be configured widely by the concave pre-nip member 64a that substantially follows the outer peripheral surface of the fixing roll 61, stable fixing performance can be ensured.

  In the vicinity of the downstream side of the nip portion N, the paper P peeled off from the fixing roll 61 by the peeling nip member 64b is completely separated from the fixing roll 61 and guided to the paper discharge path toward the discharge portion of the image forming apparatus. A peeling assisting member 70 is provided for this purpose. The peeling auxiliary member 70 is held by a baffle holder 72 in a state in which the peeling baffle 71 is close to the fixing roll 61 in a direction (counter direction) opposite to the rotation direction of the fixing roll 61.

Next, each member constituting the fixing device 60 will be described.
First, in the fixing roll 61, the core 611 is made of a metal or alloy having high thermal conductivity such as iron, aluminum (for example, A-5052 material), SUS, copper, ceramics, FRM, and the outer diameter is 30 mm, for example. It is composed of a cylindrical body having a wall thickness of 1.8 mm and a length of 360 mm.
The heat-resistant elastic body layer 612 is composed of an elastic body having high heat resistance, and it is particularly preferable to use an elastic body such as rubber or elastomer having a rubber hardness of about 15 ° to 45 ° (JIS-A). Specifically, silicone rubber, fluorine rubber, or the like can be used. Of these, silicone rubber is preferred because it has a low surface tension and is excellent in elasticity. Examples of such silicone rubbers include RTV silicone rubber and HTV silicone rubber. Specifically, polydimethyl silicone rubber (MQ), methyl vinyl silicone rubber (VMQ), and methyl phenyl silicone rubber (PMQ). And fluorosilicone rubber (FVMQ). In fixing device 60 of the present embodiment, HTV silicone rubber having a rubber hardness of 35 ° (JIS-A) is coated on core 611 with a thickness of 600 μm. The thickness of the heat-resistant elastic body layer 612 is usually 3 mm or less, preferably in the range of 0.1 mm to 1.5 mm. There is no restriction | limiting in particular as a method to form in the surface of the core 611 of the heat resistant elastic body layer 612, For example, a well-known coating method, a shaping | molding, etc. are employable.

In the present embodiment, since the release layer 613 is formed on the outer peripheral surface of the heat resistant elastic body layer 612, offset of the toner image can be effectively prevented, and the fixing device 60 is operated in a stable state. be able to. The material of the release layer 613 is not particularly limited as long as it shows an appropriate release property for the toner image, and examples thereof include fluorine rubber, silicone rubber, and fluorine resin. Among these materials, a fluororesin is preferable.
The fluororesin is not particularly limited. For example, polytetrafluoroethylene (PTFE); tetrafluoroethylene-perfluoromethyl vinyl ether copolymer (MFA), tetrafluoroethylene-perfluoroethyl vinyl ether copolymer (EFA), And tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) such as tetrafluoroethylene-perfluoropropyl vinyl ether copolymer. Further, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluoride ethylene (PCTFE), polyvinyl fluoride (PVF) Etc. Among these, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoromethyl vinyl ether copolymer (MFA), and tetrafluoroethylene-perfluoroethyl vinyl ether copolymer are particularly preferred in terms of heat resistance, mechanical properties, and the like. A tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) such as a combination (EFA) is preferably used.
The thickness of the release layer 613 is usually in the range of 10 μm to 50 μm, preferably 15 μm to 30 μm. There is no restriction | limiting in particular as a method of forming the release layer 613, For example, the coating method etc. which were mentioned above are mentioned. Moreover, the method of coat | covering the tube formed by extrusion molding is mentioned. In fixing device 60 of the present embodiment, PFA having a thickness of 30 μm is coated.

Next, the endless belt 62 will be described.
In the fixing device 60 to which this exemplary embodiment is applied, the endless belt 62 is configured by a single layer formed by blending a fluororesin and a reinforcing filler. Moreover, it is preferable that the part which comprises a single layer matrix is substantially comprised only with a fluororesin. In this embodiment, by using a single layer endless belt 62 formed by blending a fluororesin and a reinforcing filler, the sliding resistance between the pressure pad 64 or the low friction sheet 68 and the inner surface of the endless belt 62 is reduced. It can be greatly reduced. In addition, by making the structure of the endless belt 62 as a single layer, compared with the conventional case of having a two-layer structure of a base material layer such as polyimide resin and a release layer, for example, a simple method using an extrusion molding machine or the like Thus, the endless belt 62 can be manufactured, and the manufacturing cost can be reduced.

  Examples of the fluororesin used for the endless belt 62 include polytetrafluoroethylene (PTFE); tetrafluoroethylene-perfluoromethyl vinyl ether copolymer (MFA), tetrafluoroethylene-perfluoroethyl vinyl ether copolymer (EFA). And tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) such as tetrafluoroethylene-perfluoropropyl vinyl ether copolymer. Further, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluoride ethylene (PCTFE), polyvinyl fluoride (PVF) Etc.

Among these fluororesins, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoromethyl vinyl ether copolymer (MFA), tetrafluoroethylene-perfluoroethyl, especially from the viewpoint of heat resistance, mechanical properties, etc. A tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) such as a vinyl ether copolymer (EFA) or a tetrafluoroethylene-hexafluoropropylene copolymer (FEP) is preferably used.
Furthermore, polytetrafluoroethylene (PTFE) and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) are particularly preferable from the viewpoints of releasability and low friction. These fluororesins are used individually or in combination of 2 or more types as appropriate.

  The reinforcing filler used for the endless belt 62 is conventionally known as a filler for polymer materials, and can increase the mechanical strength of the endless belt 62 by blending with the above-described fluororesin. Those having particularly reinforcing ability are mentioned. Although it does not specifically limit as a reinforcing filler, For example, a needle-like (whisker) filler, a layered filler, and a fibrous filler are mentioned. These fillers are considered to have an anchor effect that is difficult to be detached from the fluororesin forming the matrix by being blended with the fluororesin.

  Specific examples of the reinforcing filler include acicular (whisker) fillers such as potassium titanate, aluminum borate, silicon carbide, silicon nitride, calcium carbonate, basic magnesium sulfate, and zinc oxide. Among these, potassium titanate, aluminum borate, and zinc oxide are preferable from the viewpoint of dispersibility in a fluororesin. Among needle-like (whisker) fillers, zinc oxide is known as a tetrapot-like whisker and is commercially available under the trade name Panatetra (manufactured by Matsushita Amtec Corporation).

  Examples of the layered filler include silicates, phosphates such as zirconium phosphate, titanates such as potassium titanate, tungstates such as sodium tungstate, uranates such as sodium uranate, and vanadine. Examples thereof include vanadate such as potassium acid, molybdate such as magnesium molybdate, niobate such as potassium niobate, graphite and the like. Among these, layered silicate is preferable. The layered silicate is mainly formed of a tetrahedral sheet of silicon oxide and an octahedral sheet of metal hydroxide, and examples thereof include smectite group clay and swellable mica. Specific examples of the smectite group clay include, for example, montmorillonite, beidellite, nontronite, saponite, iron saponite, hectorite, soconite, stevensite, bentonite, and the like, or a substitution product, a derivative thereof, or a mixture thereof. Examples of the swellable mica include lithium-type teniolite, sodium-type teniolite, lithium-type tetrasilicon mica, sodium-type tetrasilicon mica, etc., or their substitutes, derivatives, or mixtures thereof.

  Examples of the fibrous filler include inorganic short fibers such as carbon fibers, glass fibers, silicon carbide fibers, potassium titanate fibers, and graphite fibers; and organic short fibers such as aramid fibers.

  The blending amount of the reinforcing filler used for the endless belt 62 is not particularly limited, but is usually 10 to 40 parts by weight, preferably 15 to 35 parts by weight with respect to 100 parts by weight of the fluororesin. Part. If the blending amount of the reinforcing filler is excessively small, the strength of the endless belt 62 tends to decrease. If the compounding amount of the reinforcing filler is excessively large, the releasability of the endless belt 62 is lowered and the surface friction coefficient tends to increase.

The thickness of the endless belt 62 is not particularly limited, but is usually 80 μm to 500 μm, and preferably 120 μm to 200 μm. If the endless belt 62 is too thin, the strength tends to decrease. If the endless belt 62 is excessively thick, the heat capacity of the endless belt 62 increases, and as a result, power consumption for securing the amount of heat supplied for fixing tends to increase. Further, the peripheral length and width of the endless belt 62 are not particularly limited and are appropriately selected.
Further, the surface of the endless belt 62 is preferably smooth, and specifically, the arithmetic average roughness (Ra) (JIS B0601-1994) is 10.0 μm or less, preferably 5 μm or less. If the arithmetic average roughness (Ra) on the surface of the endless belt 62 is excessively large, image defects may occur, which is not preferable.

  The manufacturing method of the endless belt 62 is not particularly limited. For example, a pellet is prepared by mixing a fluororesin and a reinforcing filler in a molten state in advance, and the prepared pellet is put into an extruder and is set at a predetermined temperature. After being kneaded and extruded into a tube shape having a predetermined thickness, it can be manufactured by cutting into a predetermined width.

As described above, the pressure pad 64 disposed inside the endless belt 62 includes the pre-nip member 64a and the peeling nip member 64b, and presses the fixing roll 61 with a load of, for example, 35 kgf by a spring or an elastic body. Is supported by the holder 65. An elastic body such as silicone rubber or fluororubber, a leaf spring, or the like can be used for the prenip member 64 a, and the surface on the fixing roll 61 side is formed with a concave curved surface that substantially follows the outer peripheral surface of the fixing roll 61. In the fixing device 60 of the present embodiment, silicone rubber having a width of 10 mm, a thickness of 5 mm, and a length of 320 mm is used. The hardness of the pressure pad 64 is not particularly limited, and usually the JIS-A hardness is in the range of 10 ° to 40 °.
The peeling nip member 64b is formed of a heat-resistant resin such as PPS, polyimide, polyester, or polyamide, or a metal such as iron, aluminum, or SUS. As the shape of the peeling nip member 64b, the outer surface shape in the nip portion N is formed as a convex curved surface having a constant radius of curvature.
In the fixing device 60 of the present embodiment, the endless belt 62 is wrapped around the fixing roll 61 by the pressure pad 64 at a winding angle of about 40 ° to form a nip portion N having a width of about 8 mm.

  Further, the holder 65 is provided with a lubricant application member 67 along the longitudinal direction of the fixing device 60. The lubricant application member 67 is disposed so as to contact the inner peripheral surface of the endless belt 62 and supplies an appropriate amount of lubricant. As a result, the lubricant is supplied to the sliding portion between the endless belt 62 and the low friction sheet 68, and the sliding resistance between the endless belt 62 and the pressure pad 64 via the low friction sheet 68 is further reduced. 62 is smoothly rotated. Further, it has an effect of suppressing wear on the inner peripheral surface of the endless belt 62 and the surface of the low friction sheet 68.

  As the lubricant, a lubricant that has durability against long-term use under a fixing temperature environment and can maintain wettability with the inner peripheral surface of the endless belt 62 is suitable. For example, liquid oil such as silicone oil or fluorine oil, synthetic lubricating oil grease in which a solid substance and a liquid are mixed, or a combination thereof can be used. Silicone oils include dimethyl silicone oil, dimethyl silicone oil with organometallic salt addition, dimethyl silicone oil with hindered amine addition, dimethyl silicone oil with organometallic salt and hindered amine addition, methylphenyl silicone oil, amino-modified silicone oil, amino-modified silicone-added amino-modified silicone. Oil, hindered amine-added amino-modified silicone oil, carboxy-modified silicone oil, silanol-modified silicone oil, sulfonic acid-modified silicone oil, and the like can also be used. Moreover, as fluoro oil, perfluoropolyether oil and modified perfluoropolyether oil can be used. In the fixing device 60 according to the present embodiment, methylphenyl silicone oil having a viscosity of 400 cs (manufactured by Shin-Etsu Chemical Co., Ltd .: KF54) is used.

  The endless belt 62 has an elastic modulus set to 2,500 MPa to 11,000 MPa. Thus, by setting the elastic modulus, the heat-resistant elastic body layer 612 of the fixing roll 61 can be formed into a concavely curved shape to the extent that the occurrence of paper wrinkles is suppressed. In addition, autonomous adjustment is performed on the paper P such that the speed of the paper P continuously changes in the width direction due to the microscopic slip between the paper P and the outer peripheral surface of the endless belt 62 described above. As a result, the elongation of the paper P can be suppressed to the extent possible. When the elastic modulus of the endless belt 62 is lower than a predetermined value, the heat-resistant elastic body layer 612 of the fixing roll 61 is pressed so as to have a concavely curved shape so that the generation of paper wrinkles is suppressed. I can't. On the other hand, when the elastic modulus is higher than a predetermined value, the contact pressure of the endless belt 62 with respect to the fixing roll 61 becomes too high, so that a part of the paper P is easily stretched. There may be a case where the discontinuity of the speed of the paper P cannot be recovered only by microscopic slip with the outer peripheral surface.

(Second Embodiment)
In the first embodiment described above, an image forming apparatus in which a fixing roll 61 having a heat source is used as a heating unit and a fixing device 60 using an endless belt 62 with a pressure pad 64 pressed as a pressing unit is mounted. Explained. In the second embodiment, the fixing device is mounted on the image forming apparatus shown in FIG. 1, and a fixing belt with a heat source pressed is used as a heating unit, and a fixing roll is used as a pressing unit. The apparatus will be described. In addition, the same code | symbol is used about the structure similar to 1st Embodiment, and the detailed description is abbreviate | omitted here.

FIG. 4 is a side sectional view showing the configuration of the fixing device 90 to which the second exemplary embodiment is applied. As shown in FIG. 4, in the fixing device 90 of the present embodiment, a fixing belt 92 as an example of a belt member is disposed on the toner image carrying surface side of the paper P. Inside the fixing belt 92, a ceramic heater 82, which is a resistance heating element as an example of a heat source held by the holder 65, is disposed, and heat is supplied from the ceramic heater 82 to the nip portion N. .
The ceramic heater 82 has a substantially flat surface on the pressure roll 91 side. Then, it is arranged in a state of being pressed against the pressure roll 91 via the fixing belt 92 and forms a nip portion N. Therefore, the ceramic heater 82 also functions as a pressure member. The sheet P that has passed through the nip portion N is peeled off from the fixing belt 92 by the change in the curvature of the fixing belt 92 in the exit region (peeling nip portion) of the nip portion N.
Further, in order to reduce the sliding resistance between the inner peripheral surface of the fixing belt 92 and the ceramic heater 82 between the inner peripheral surface of the fixing belt 92 and the ceramic heater 82, a low friction sheet 68 as an example of a rubbing member. Is arranged. The low friction sheet 68 may be configured separately from the ceramic heater 82 or may be configured integrally with the ceramic heater 82.

On the other hand, the pressure roll 91 is disposed so as to face the fixing belt 92, and is configured to rotate in the direction of arrow D by a drive motor (not shown), and the rotation of the fixing belt 92 is driven by this rotation. The pressure roll 91 includes a core (cylindrical core metal) 911, a heat-resistant elastic body layer 912 coated on the outer peripheral surface of the core 911, and a release layer 913 made of heat-resistant resin or heat-resistant rubber. Has been configured.
Further, in the fixing device 90 of the present embodiment, the fixing belt 92 is an endless belt whose original shape is formed in a cylindrical shape, and is composed of a single layer formed by blending a fluororesin and a reinforcing filler.
Further, as an auxiliary means for peeling, a peeling auxiliary member 70 can be disposed on the downstream side of the nip portion N of the fixing belt 92. The peeling auxiliary member 70 is held by a baffle holder 72 in a state where the peeling baffle 71 is close to the fixing belt 92 in a direction (counter direction) opposite to the rotation direction of the fixing belt 92.

  The paper P on which the toner image has been electrostatically transferred in the secondary transfer unit 20 of the image forming apparatus shown in FIG. 1 is guided to the nip N of the fixing device 90 by the fixing inlet guide 56. When the paper P passes through the nip portion N, the toner image on the paper P is fixed by the pressure acting on the nip portion N and the heat supplied from the ceramic heater 82 on the fixing belt 92 side. Also in the fixing device 90 of the present embodiment, since the nip portion N can be configured widely between the pressure roll 91 and the ceramic heater 82, stable fixing performance can be ensured.

Here, in the fixing device 90 of the present embodiment, the fixing belt 92 includes a fluororesin such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and 100 wt. On the other hand, it is comprised from the single layer which mix | blends 10-40 weight part of reinforcing fillers which are acicular (whisker) fillers, such as potassium titanate and zinc oxide. By forming the fixing belt 92 in this manner, the sliding resistance between the ceramic heater 82 or the low friction sheet 68 and the inner surface of the fixing belt 92 can be greatly reduced as in the first embodiment. In addition, since the fixing belt 92 has a single layer structure, the fixing belt 92 can be manufactured by a simple method using, for example, an extrusion molding machine. As a result, it is possible to suppress the occurrence of paper wrinkles on the paper P and the occurrence of image defects such as image displacement.
Since the pressing force of the ceramic heater 82 may be set constant in the axial direction, complicated adjustment is not required when setting the ceramic heater 82, and productivity can be improved and manufacturing cost can be reduced.

Hereinafter, the present embodiment will be described more specifically based on examples. Note that this embodiment is not limited to the examples.
1. Image Quality Evaluation Using an image forming apparatus (manufactured by Fuji Xerox Co., Ltd .: Color Printer DocuPrint C1616) having a fixing device having the same configuration as the fixing device 60 described in the first embodiment, a full-color pattern image is printed on J paper. The image quality was evaluated according to the following criteria.
(Image quality evaluation criteria)
○: Image quality defect does not occur.
(Triangle | delta): Although the image quality defect exists slightly, there is no problem practically.
X: An image quality defect having a practical problem occurs.

2. Driving torque The measurement gear of a direct torque meter (manufactured by Fuji Xerox Co., Ltd.) was fitted to the gear portion of the fixing roll, and the torque required for the initial driving and the temporal driving of the fixing roll was measured (unit: Nm). When the driving torque exceeds 1.0 Nm, a load is applied to the driving gear of the fixing roll as a driving source, which causes a problem in practical use. In particular, as a phenomenon indicating a malfunction, a paper flaw occurs on a sheet from which an image is obtained, or abnormal gear noise occurs.

The specifications of each component of the fixing device used for the evaluation are as follows.
The fixing roll has an elastic surface of a 600 μm-thick silicone HTV rubber (rubber hardness 33 degrees: JIS-A) on the outer peripheral surface of a cylindrical iron core having an outer diameter of 24.5 mm, a wall thickness of 1.5 mm, and a length of 260 mm. A layer of 25 μm thick tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) tube is coated as a release layer on the surface of the elastic layer, and finished to a surface close to a mirror state. .
Inside the core of the fixing roll, a halogen lamp (600w) is disposed as a heating source. The surface temperature of the fixing roll was controlled to 175 ° C. by a temperature sensor and a temperature controller which are temperature sensitive elements arranged in contact with the surface of the heated fixing roll.

  The pressure pad for pressing the endless belt is provided with a low friction sheet on a support made of silicone rubber having a width of 10 mm, a thickness of 5 mm, and a length of 340 mm. The surface of the low friction sheet is perfluoropolyether oil as a lubricant. (Daikin Industries, Ltd. product: S100) is supplied. Further, ribs in the belt rotation direction are provided on the surface of the belt guide member disposed on the support so as to reduce the contact area with the inner peripheral surface of the endless belt. The pressure pad presses the fixing roll with a load of 10 kg by a compression coil spring through an endless belt.

  The winding angle of the endless belt around the fixing roll was about 40 °, and the width of the nip portion was about 10 mm. The driving force transmitted from the motor to the fixing roll rotated the fixing roll and the endless belt at a speed of 104 mm / sec.

Example 1
100 parts by weight of fluororesin (Daikin Kogyo Co., Ltd .: Neoflon AP230) and 30 parts by weight of conductive potassium titanate whisker (Otsuka Chemical Co., Ltd .: Tismo) as a reinforcing filler are dispersed and mixed in advance. A pellet was prepared. Next, this mixed pellet was extruded using an extruder at a temperature of 380 ° C. so as to form a tube shape having a thickness of 120 μm and a circumferential length of 94 mm. Subsequently, it was trimmed to a length of 255 mm to prepare a single-layer endless belt made of a fluororesin and potassium titanate whiskers. The arithmetic average roughness Ra (JIS B0601-1994) of the endless belt surface was 1.8 μm.

  Next, the fixing device used for the endless belt prepared as described above is incorporated into an image forming apparatus (manufactured by Fuji Xerox Co., Ltd .: Color Printer DocuPrint C1616), and a running test is performed up to 200,000 sheets. The driving torque, the image quality of the print, and the endless belt running state were confirmed after printing 10,000 sheets. As a result, there was no change in the driving torque between the initial stage and time, and the image quality was very good. Further, the endless belt was not buckled, and the surface wear and the like were at a level that is practically acceptable. The results are shown in Table 1.

(Example 2)
An endless belt was prepared under the same conditions as in Example 1 except that 10 parts by weight of conductive potassium titanate whisker (manufactured by Otsuka Chemical Co., Ltd .: Tismo) was blended as the reinforcing filler. The thickness of the endless belt was 110 μm, and the arithmetic average roughness (Ra) of the surface was 1.3 μm.
Next, in the same manner as in Example 1, the fixing device used for the endless belt prepared in this way is incorporated into an image forming apparatus (manufactured by Fuji Xerox Co., Ltd .: color printer DocuPrint C1616), and a running test up to 200,000 sheets is performed. Then, the driving torque, the print image quality, and the endless belt running state at the time of printing at the initial stage and over time (after printing 200,000 sheets) were confirmed. As a result, there was no change in the driving torque between the initial stage and time, and the image quality was very good. Further, the endless belt was not buckled, and the surface wear and the like were at a level where there was no practical problem. The results are shown in Table 1.

(Example 3)
An endless belt was prepared under the same conditions as in Example 1 except that 35 parts by weight of conductive potassium titanate whisker (manufactured by Otsuka Chemical Co., Ltd .: Tismo) was added as a reinforcing filler. The thickness of the endless belt was 200 μm, and the arithmetic average roughness (Ra) of the surface was 1.9 μm.
Next, in the same manner as in Example 1, the fixing device used for the endless belt prepared in this way is incorporated into an image forming apparatus (manufactured by Fuji Xerox Co., Ltd .: color printer DocuPrint C1616), and a running test up to 200,000 sheets is performed. Then, the driving torque, the print image quality, and the endless belt running state at the time of printing at the initial stage and over time (after printing 200,000 sheets) were confirmed. As a result, there was no change in the driving torque between the initial stage and time, and the image quality was very good. Further, the endless belt was not buckled, and the surface wear and the like were at a level that is practically acceptable. The results are shown in Table 1.

Example 4
An endless belt was prepared under the same conditions as in Example 1 except that 30 parts by weight of zinc oxide whisker (manufactured by Matsushita Amtec Co., Ltd .: Panatetra) was blended as a reinforcing filler. The thickness of the endless belt was 130 μm, and the arithmetic average roughness (Ra) of the surface was 1.5 μm.
Next, in the same manner as in Example 1, the fixing device used for the endless belt prepared in this way is incorporated into an image forming apparatus (manufactured by Fuji Xerox Co., Ltd .: color printer DocuPrint C1616), and a running test up to 200,000 sheets is performed. Then, the driving torque, the print image quality, and the endless belt running state at the time of printing at the initial stage and over time (after printing 200,000 sheets) were confirmed. As a result, there was no change in the driving torque between the initial stage and time, and the image quality was very good. Further, the endless belt was not buckled, and the surface wear and the like were at a level that is practically acceptable. The results are shown in Table 1.

(Comparative example)
A varnish containing a polyimide resin prepared in advance is coated on a mold and baked. Next, a fluororesin (PFA) is coated on the varnish, and then the PFA resin is baked to form a polyimide resin base layer and fluorine. A two-layer belt tubular body with a release layer made of resin and having a thickness of 30 μm was prepared. The belt tubular body thus prepared has a thickness of 120 μm and a cross-sectional diameter (φ) of 30 mm.
Next, in the same manner as in Example 1, the fixing device used for the two-layered belt tubular body prepared in this way is incorporated into an image forming apparatus (manufactured by Fuji Xerox Co., Ltd .: color printer DocuPrint C1616), and up to 200,000 sheets. The running test was conducted, and the driving torque, the image quality of the print, and the endless belt running state were confirmed at the initial time and after printing (after printing 200,000 sheets). As a result, the torque was a value with no problem at the beginning, but when the effect of the lubricant was reduced over time, the torque increased because the polyimide resin was originally used for the base material layer with a high friction coefficient, Paper defects and image quality defects occurred. The results are shown in Table 1.

  As described above, in the fixing device 60 of the present embodiment, the endless belt 62 is composed of a single layer formed by blending a fluororesin and a reinforcing filler, so that the pressure pad 64 or the low friction sheet is formed. The sliding resistance between 68 and the inner surface of the endless belt 62 can be greatly reduced. In addition, by making the structure of the endless belt 62 as a single layer, compared with the conventional case of having a two-layer structure of a base material layer such as polyimide resin and a release layer, for example, a simple method using an extrusion molding machine or the like Thus, the endless belt 62 can be manufactured, and the manufacturing cost can be reduced.

  As an application example of the present invention, application to an image forming apparatus such as a copying machine or a printer using an electrophotographic system, for example, application to a fixing apparatus that fixes an unfixed toner image carried on a recording paper (paper). is there. In addition, there is application to an image forming apparatus such as a copying machine or a printer using an inkjet method, for example, application to a fixing device that dries an undried ink image carried on a recording paper (paper).

1 is a schematic configuration diagram illustrating an image forming apparatus to which the exemplary embodiment is applied. 1 is a side cross-sectional view illustrating a configuration of a fixing device to which a first exemplary embodiment is applied. It is a figure explaining the structure by which an endless belt is supported. FIG. 4 is a side sectional view showing a configuration of a fixing device to which a second embodiment is applied.

Explanation of symbols

1Y, 1M, 1C, 1K ... image forming unit, 11 ... photosensitive drum, 12 ... charger, 13 ... laser exposure device, 14 ... developer, 15 ... intermediate transfer belt, 16 ... primary transfer roll, 17 ... drum cleaner , 20 ... secondary transfer part, 60, 90, 100 ... fixing device, 61 ... fixing roll, 62 ... endless belt, 63 ... belt guide member, 64 ... pressure pad, 64a ... pre-nip member, 64b ... peeling nip member, 65 DESCRIPTION OF SYMBOLS ... Holder, 66 ... Halogen heater, 67 ... Lubricant application member, 68 ... Low friction sheet, 69 ... Temperature sensor, 70 ... Peeling auxiliary member, 82 ... Ceramic heater, 91 ... Pressure roll, 92 ... Fixing belt

Claims (9)

A fixing device for fixing a toner image carried on a recording material,
A rotating member;
A fixing device comprising: a belt member configured to move in contact with the rotating member and configured by a single layer formed by blending a fluororesin and a reinforcing filler.   The fixing device according to claim 1, wherein the belt member has a thickness of 80 μm to 500 μm.   The fixing device according to claim 1, wherein an arithmetic average roughness of the surface of the belt member is 10 μm or less.   The fixing device according to claim 1, further comprising a heating member that heats the rotating member or the belt member. A belt tubular body used in a fixing device for fixing a toner image carried on a recording material,
A belt tubular body comprising a single layer formed by blending a fluororesin and a reinforcing filler.   The belt tubular body according to claim 5, wherein the fluororesin is a polytetrafluoroethylene resin or a tetrafluoroethylene-perfluoroalkyl vinyl ether resin.   The belt tubular body according to claim 5, wherein the reinforcing filler is a needle-like filler, a layer-like filler, or a fibrous filler.   The belt tubular body according to claim 5, wherein 100 parts by weight of the fluororesin and 10 to 40 parts by weight of the reinforcing filler are blended with the fluororesin. Toner image forming means for forming a toner image;
Transfer means for transferring the toner image formed by the toner image forming means onto a recording material;
Fixing means for fixing the toner image transferred onto the recording material to the recording material,
The fixing means is
A rotating member;
A belt member movable while contacting the rotating member;
A pressure member that is disposed inside the belt member and that presses the belt member against the rotating member to form a nip portion through which the recording material passes between the rotating member and the belt member;
The image forming apparatus according to claim 1, wherein the belt member includes a single layer formed by blending a fluororesin and a reinforcing filler.

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