JP2008224835A - Image fixing components, fixing unit, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide fixing components hardly damaging the paper edge when passing a thick paper. <P>SOLUTION: This fixing unit 60 has a fixing roll 61 and an endless belt 62 in pressure contact with the fixing roll 61 and forming a contact area N to pass the paper P. The releasing layer 613 on the surface of the fixing roll 61 contains a fluorine resin which has a 260°C or higher melting temperature when measured by using the differential scanning calorimetry method specified in JIS K7121 being a tetrafluoroethylene-perfluoro alkyl vinyl ether binary copolymer (PFA), and the content of the perfluoro alkyl vinyl ether is 2-6 mol%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fixing member and the like, and more particularly to a fixing member and the like used for a fixing device.

  A fixing device provided in an image forming apparatus such as a copying machine, a laser printer, or a facsimile using an electrophotographic method has a fixing roll having a heating source therein and a pressure roll disposed opposite to the fixing roll. ing. The recording material on which the unfixed toner image is formed is sandwiched between the fixing roll and the pressure roll, and the toner image is fixed on the recording material by heating and pressing.

  Also, as the color, speed, and miniaturization of the image forming apparatus progresses, an endless belt is used instead of the pressure roll, and the recording material is pressed against the fixing roll using a pressure pad from the inside of the endless belt. A fixing device that forms a contact portion is used (see Patent Document 1).

  On the other hand, a fixing film made of a heat resistant film is used in place of the fixing roll, and a resistance heating layer is provided on a substrate made of alumina or the like, and heat is applied to an unfixed image through the heat resistant fixing film while pressing with a pressure roll. Is used to fix the unfixed toner image on the recording material (see Patent Document 2).

  In these fixing devices, the fixing member that comes into contact with the toner image has an elastic layer made of silicone rubber or the like provided on a heat-resistant substrate, and a release layer that covers the elastic layer with a fluororesin tube or the like. In many cases (see Patent Document 3).

  In addition, since the fluororesin has a small friction coefficient, image misalignment and paper wrinkling may occur during paper feeding. In order to prevent this and improve the paper transportability, a method of increasing the friction coefficient of the pressure roll has been reported (see Patent Document 4 and Patent Document 5).

Japanese Patent No. 3298354 Japanese Patent Laid-Open No. 02-157878 Japanese Patent No. 3735991 Japanese Patent No. 2654905 Japanese Patent No. 2944457

  By the way, in the release layer formed on the surface of the fixing member, in particular, when a thick paper is passed, a paper rush damage caused by the leading edge and the trailing edge of the paper is likely to occur. For this reason, there is a problem in that if the paper is passed after the paper entry damage has occurred, the damage is transferred to the image.

  An object of the present invention is to provide a fixing member and the like that are less likely to cause paper entry scratches when passing thick paper.

The invention according to claim 1 has a base, an elastic layer formed on the base, and a release layer formed on the elastic layer, and the release layer is made of perfluoroalkyl vinyl ether. A fixing member comprising a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer having a composition of 2 mol% to 6 mol%.
The invention according to claim 2 is the fixing member according to claim 1, wherein the perfluoroalkyl vinyl ether is perfluoroethyl vinyl ether or perfluoropropyl vinyl ether.
According to a third aspect of the present invention, the release layer conforms to the frictional wear test method B method defined in JIS K7218, and the maximum coefficient of friction measured on a recording paper at 170 ° C. within 1 second ( The melting temperature measured using the differential scanning calorimetry (DSC) measurement method defined in JIS K7121 is 260 ° C. or higher, and μ) is 0.5 or higher. It is a fixing member.
The invention according to claim 4 is the fixing member according to claim 1, wherein the release layer has a thickness of 10 μm to 50 μm.
According to a fifth aspect of the present invention, there is provided a fixing rotator having a release layer on a surface thereof, and a contact portion provided opposite to the fixing rotator and through which the recording material passes while being pressed against the fixing rotator. A pressure rotator to be formed, and the release layer of the fixing rotator is a binary copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether, and the composition of the perfluoroalkyl vinyl ether A fluororesin having a melting temperature of 260 ° C. or higher measured by a differential scanning calorimetry (DSC) method defined in JIS K7121 Device.
According to a sixth aspect of the present invention, the fixing rotator is formed by bonding a base made of a predetermined material, an elastic layer provided on the base, and a tube of the fluororesin on the elastic layer. The fixing device according to claim 5, further comprising a three-layer structure including the release layer.
According to a seventh aspect of the present invention, there is provided toner image forming means for forming a toner image, transfer means for transferring the toner image onto a recording material, and the toner image transferred onto the recording material on the recording material. Fixing means for fixing, and the fixing means has on its surface a release layer containing a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer whose composition of perfluoroalkyl vinyl ether is 2 mol% to 6 mol%. An image forming apparatus comprising: a fixing rotator provided; and a pressurizing rotator that presses against the fixing rotator and forms a contact portion through which the recording material passes.

According to the first aspect of the present invention, even when a fixing member having a release layer is used, when a thick paper sheet is passed through, a paper rush damage hardly occurs and a high-quality image is obtained.
According to the second aspect of the present invention, the paper entry damage is further reduced as compared with the case where the present configuration is not provided.
According to the invention which concerns on Claim 3, compared with the case where it does not have this structure, the balance of the friction coefficient of a mold release layer and melting temperature is suitable.
According to the fourth aspect of the present invention, the durability is improved and the image is stabilized as compared with the case where the present configuration is not provided.
According to the fifth aspect of the present invention, there is obtained a fixing device in which even when a fixing rotator having a release layer is used, paper entry scratches are hardly transferred to an image.
According to the sixth aspect of the present invention, the releasability of the toner image is improved as compared with the case where this configuration is not provided.
According to the seventh aspect of the present invention, a high-quality image is obtained even when a fixing rotator having a release layer is used.

  Hereinafter, the best mode (embodiment) for carrying out the present invention will be described. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary. Also, the drawings used are used to describe the present embodiment and do not represent the actual size.

  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 that form toner images of respective color components by electrophotography as toner image forming means. Next, as transfer means, a primary transfer unit 10 that sequentially transfers (primary transfer) each color component toner image formed by each of the image forming units 1Y, 1M, 1C, and 1K to the intermediate transfer belt 15, and the intermediate transfer belt 15. A secondary transfer unit 20 that collectively transfers (secondary transfer) the transferred superimposed toner image onto a sheet P that is a recording material (recording sheet). Further, a fixing device 60 that fixes the second-transferred image on the paper P is provided as a fixing unit. Moreover, it has the control part 40 which controls operation | movement of each apparatus (each part).

  As shown in FIG. 1, in this embodiment, the electrophotographic devices are sequentially arranged. That is, each of the image forming units 1Y, 1M, 1C, and 1K has a charger 12 that charges the photosensitive drum 11 around the photosensitive drum 11 that rotates in the direction of arrow A, and a static on the photosensitive drum 11. A laser exposure device 13 for writing an electrostatic latent image (in FIG. 1, an exposure beam is indicated by a symbol Bm) and development for accommodating each color component toner and making the electrostatic latent image on the photosensitive drum 11 visible with toner. A container 14 is disposed. Also, a primary transfer roll 16 that transfers each color component toner image formed on the photosensitive drum 11 to the intermediate transfer belt 15 in the primary transfer unit 10, a drum cleaner 17 that removes residual toner on the photosensitive drum 11, and Is disposed. 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. To do.

  The intermediate transfer belt 15 is circulated and rotated (rotated) at a predetermined speed in the direction of arrow 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 predetermined tension to the intermediate transfer belt 15 and prevents meandering of the intermediate transfer belt 15, 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. A voltage (primary transfer bias) having a polarity opposite to the charging polarity of the toner (negative polarity; the same applies hereinafter) is applied to the primary transfer roll 16. As a result, the toner images on the respective photosensitive drums 11 are sequentially electrostatically attracted to the intermediate transfer belt 15 to form toner images superimposed on the intermediate transfer belt 15.

  The secondary transfer unit 20 includes a secondary transfer roll 22 disposed on the toner image holding surface side of the intermediate transfer belt 15 and a backup roll 25. The backup roll 25 is arranged 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 arranged in contact.

  The secondary transfer roll 22 is placed in pressure contact with the backup roll 25 with the intermediate transfer belt 15 interposed therebetween, and further, the secondary transfer roll 22 is grounded to form a secondary transfer bias with the backup roll 25, so that the secondary transfer is performed. The toner image is secondarily transferred onto the paper P conveyed to the 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 for generating a reference signal for taking an image forming timing in each of the image forming units 1Y, 1M, 1C, 1K is disposed. . 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. In response to an instruction from the control unit 40 based on the recognition of the reference signal, each image forming unit 1Y, 1M, 1C and 1K start image formation.

  Further, in the image forming apparatus according to the present embodiment, as a paper transport system, a paper tray 50 that stores paper P, a pickup roll 51 that takes out and transports the paper P accumulated in the paper tray 50 at a predetermined timing, The pickup roll 51 transports the paper P that is fed, 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 roll 22 for secondary transfer. A conveyance belt 55 that conveys the sheet P to be fixed to the fixing device 60, and a fixing inlet guide 56 that guides the sheet P to the fixing device 60.

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 by an image reading device (IIT) (not shown), a personal computer (PC) (not shown), or the like is an image processing device (IPS) (not shown). The image forming operation is executed by the image forming units 1Y, 1M, 1C, and 1K. In the IPS, input image 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. The image data subjected to the 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 device 13 irradiates, for example, an exposure beam Bm emitted from a semiconductor laser to the photosensitive drums 11 of the image forming units 1Y, 1M, 1C, and 1K according to the input color material gradation data. In each photosensitive drum 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 device 13 to form an electrostatic latent image. The formed electrostatic latent image is developed as a toner image of each color of Y, M, C, and K by each of the 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. To do. More specifically, in the primary transfer unit 10, a voltage (primary transfer bias) having a polarity opposite to the charging polarity (minus 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 superimposing the toner images on the surface of the intermediate transfer belt 15.

  After the toner image is sequentially primary transferred onto the surface of the intermediate transfer belt 15, the intermediate transfer belt 15 moves and conveys the toner image to the secondary transfer unit 20. When the toner image is transported to the secondary transfer unit 20, in the paper transport system, the pickup roll 51 rotates in accordance with the timing of transporting the toner image to the secondary transfer unit 20, and the paper P of a predetermined size is supplied from the paper tray 50. To do. 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 holding the toner image. The position is aligned with the position of the toner image.

  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, a voltage (secondary transfer bias) having the same polarity as the toner charging polarity (minus polarity) is applied from the power supply roll 26, and a transfer electric field is formed between the secondary transfer roll 22 and the backup roll 25. The unfixed toner image held 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 conveyed as it is while being peeled off from the intermediate transfer belt 15 by the secondary transfer roll 22, and is conveyed to a conveyance belt 55 provided downstream of the secondary transfer roll 22 in the sheet conveyance direction. And carry. The transport belt 55 transports the paper P to the fixing device 60 in accordance with the optimal transport 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 mounting portion (not shown) provided in the discharge portion of the image forming apparatus.
On the other hand, after the transfer to 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. To remove from the intermediate transfer belt 15.

(First embodiment)
Next, the fixing device 60 used in the image forming apparatus of the present embodiment will be described.
FIG. 2 is a side sectional view showing a configuration of the fixing device 60 to which the first exemplary embodiment is applied. The fixing device 60 includes a fixing roll 61 as an example of a fixing rotator that is a fixing member, an endless belt 62 as an example of a pressurizing rotator that rotates while being pressed against the fixing roll 61, and an endless belt 62. The pressure member 64 pressed from the fixing roll 61 constitutes a main part.

The fixing roll 61 as a fixing member is a cylindrical roll having a three-layer structure in which an elastic layer 612 and a release layer 613 are laminated around a metal core (cylindrical cored bar) 611 as a base. The fixing roll 61 is rotatably supported and rotates at a predetermined surface speed (for example, 194 mm / sec). The fixing roll 61 of this embodiment is formed of a straight roll having an outer diameter that is uniform in the axial direction.
Inside the fixing roll 61, for example, a halogen heater 66 rated at 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 (see FIG. 1) of the image forming apparatus controls the lighting of the halogen heater 66 based on the temperature measurement value by the temperature sensor 69, and the surface temperature of the fixing roll 61 is a predetermined set temperature (for example, 175 ° C.). ) To maintain.

The endless belt 62 which is a rotating body for pressurization 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 is rotatably supported by a pressure member 64 and a belt guide member 63 disposed inside the endless belt 62, and edge guide members (not shown) disposed at both ends of the endless belt 62. To do. And it arrange | positions so that it may press-contact with the fixing roll 61, and may form the contact part N through which the paper P which is a recording material passes, and it rotates (for example, 194 mm / sec) following the fixing roll 61. Further, a low friction sheet 68 is disposed between the inner peripheral surface of the endless belt 62 and the pressure member 64 in order to reduce the sliding resistance between the inner peripheral surface of the endless belt 62 and the pressure member 64.
Note that the peeling assisting member 70 disposed in the vicinity of the downstream side of the contact portion N is held by the baffle holder 72 so that the peeling baffle 71 faces the rotation direction of the fixing roll 61.

Next, each member constituting the fixing device 60 will be described.
The core 611 that is the base of the fixing roll 61 is formed of, for example, a metal such as iron, aluminum (for example, A-5052 material), SUS, or copper; an alloy, ceramic, or FRM. In the present embodiment, the core 611 is, for example, a cylindrical body having an outer diameter of 30 mm, a wall thickness of 1.8 mm, and a length of 360 mm.

The elastic layer 612 is made of a heat resistant elastic material. In the present embodiment, it is preferable to use an elastic material such as rubber having a durometer hardness (JIS K6253) of about A15 to A45. If the durometer hardness is excessively low, deformation of the release layer 613 becomes too large when a constant stress is applied, and there is a tendency that permanent deformation tends to occur. On the other hand, if the durometer hardness is excessively high, the toner may not be sufficiently wrapped at the time of contact, and the image tends to be distorted.
The thickness of the elastic layer 612 is usually 3 mm or less, preferably in the range of 0.1 mm to 1.5 mm. If the thickness of the elastic layer 612 is excessively small, uneven fixing tends to occur. On the other hand, if the thickness of the elastic layer 612 is excessively large, the heat capacity of the entire fixing roll 61 tends to increase and the warm-up time tends to be long.
There is no restriction | limiting in particular as a method of forming the elastic layer 612 in the surface of the core 611, For example, a well-known coating method, a shaping | molding, etc. are employable.

  Examples of the elastic material constituting the elastic layer 612 include silicone rubber and fluororubber. Among these, silicone rubber is preferable in that it has a durometer hardness of A60 or less and is excellent in compression set (JIS K6262) characteristics. Examples of such silicone rubber include RTV silicone rubber, HTV silicone rubber, and the like. Specifically, polydimethyl silicone rubber (MQ), methyl vinyl silicone rubber (VMQ), and methyl phenyl silicone rubber (PMQ). And fluorosilicone rubber (FVMQ).

Next, the release layer 613 is formed using a material that exhibits appropriate release properties for the toner image. In this embodiment, the material constituting the release layer 613 is a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether, and the composition of the perfluoroalkyl vinyl ether is 2 mol% to 6 mol%, preferably The fluororesin which is 3 mol%-5 mol% is contained.
Here, examples of the perfluoroalkyl vinyl ether include perfluoromethyl vinyl ether, perfluoroethyl vinyl ether, perfluoropropyl vinyl ether, and perfluorobutyl vinyl ether. Among these, perfluoroethyl vinyl ether and perfluoropropyl vinyl ether are preferable, and perfluoroethyl vinyl ether is more preferable.
The copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether is preferably a binary copolymer (PFA) of tetrafluoroethylene and perfluoroalkyl vinyl ether.

  In the present embodiment, the release layer 613 contains a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) having a composition of perfluoroalkyl vinyl ether of 2 mol% to 6 mol%, so that the release layer 613 is released at the fixing temperature. The coefficient of friction (μ) on the surface of the mold layer 613 increases to such an extent that a minute slip of the paper P at the contact portion N can be prevented. As a result, when the thick paper is passed through the contact portion N, the front end portion and the rear end portion of the paper P do not cause a paper rush damage on the surface of the fixing roll 61. High-quality images can be obtained without transferring the scratches.

When the composition of perfluoroalkyl vinyl ether in the copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether is less than 2 mol%, the coefficient of friction (μ) on the surface of the release layer 613 decreases, and the leading edge and rear edge of the paper P Since the paper entry scratch caused by the edge is transferred to the image, a high-quality image cannot be obtained.
When the composition of perfluoroalkyl vinyl ether in the copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether exceeds 6 mol%, the friction coefficient (μ) on the surface of the release layer 613 increases, but the melting of the fluororesin The temperature drops. For this reason, the strength as a fixing member is lowered, and permanent deformation tends to remain on the surface, which is not preferable.

  Here, in the present embodiment, the friction coefficient (μ) of the release layer 613 is measured within 170 seconds at 170 ° C. with respect to the paper P in accordance with the friction wear test method B method defined in JIS K7218. It is preferable that the maximum friction coefficient (μ) is 0.5 or more. If the coefficient of friction (μ) is excessively small, there is a tendency for paper rush damage to occur at the leading edge and the trailing edge of the paper P passed through the contact portion N as described above.

  Moreover, in this Embodiment, it is preferable that the material which comprises the mold release layer 613 is 260 degreeC or more of melting temperature measured using the differential scanning calorific value (DSC) measuring method prescribed | regulated to JISK7121. However, the melting temperature is usually 330 ° C. or lower. When the melting temperature measured using the differential scanning calorimetry (DSC) measuring method of the release layer 613 is excessively low, the release layer 613 at the time of fixing tends to be gradually melted and permanent deformation tends to occur.

  Thus, in this Embodiment, when the mold release layer 613 contains the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) whose composition of perfluoroalkyl vinyl ether is 2 mol%-6 mol%, The balance between the friction coefficient (μ) of the surface of the fixing roll 61 at the contact portion N and the melting temperature is maintained in a favorable range.

That is, conventionally, it has been considered that the cause of the paper rush damage on the surface of the fixing roll 61 is that the paper P slightly slips at the contact portion N. For this reason, in order to increase the friction coefficient of the release layer 613, for example, it has been attempted to use a fluororesin tube in which particles of heat-resistant resin such as fluororubber or polyphenylene sulfide are mixed. However, when such a fluororesin tube is used, although the scratch resistance of the release layer 613 is improved, the toner release property is lowered, and thus a new problem that the toner remains in the release layer 613 arises.
On the other hand, in the present embodiment, when passing thick paper through the contact portion N, there is no paper entry damage caused by the leading edge and the trailing edge of the paper P on the surface of the fixing roll 61, and the paper is then passed. Even if it is done, the paper entry scratches are not transferred and a high-quality image can be obtained.

  The release layer 613 has a thickness of usually 10 μm to 50 μm, preferably 15 μm to 30 μm. When the thickness of the release layer 613 is excessively small, the durability tends to decrease. If the thickness of the release layer 613 is excessively large, the softness of the elastic layer 613 cannot be transmitted at the time of fixing, and the toner image cannot be sufficiently wrapped, so that the image tends to be distorted.

In the present embodiment, the release layer 613 is provided on the condition that the friction coefficient (μ) and the melting temperature are within the above-described ranges (friction coefficient (μ)> 0.5, melting temperature> 260 ° C.). In addition to the above-mentioned copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether (composition 2 mol% to 6 mol%), 613 can contain other fluororesins.
Examples of such fluororesins include polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), and polyvinylidene fluoride (PVDF). , Polychlorotrifluoroethylene (PCTFE), polyvinyl fluoride (PVF), and the like.

  In the present embodiment, the method for forming the release layer 613 is not particularly limited, and examples thereof include a known coating method. Moreover, Preferably, the method of coat | covering the fluororesin tube formed by extrusion molding is mentioned. In this case, it is desirable that a fluororesin having a slightly smaller diameter than the fixing roll 61 is previously melt-extruded and coated on the fixing roll 61 at an expansion rate of 1% to 5%. If the expansion rate is too small, the fluororesin tube tends to be wrinkled. If the expansion rate is excessively large, the fluororesin tube is difficult to extend and tends to be permanently deformed.

  Next, the endless belt 62 is an endless belt whose original shape is formed in a cylindrical shape, and includes a base layer and a surface layer that covers the surface or both surfaces of the base layer on the fixing roll 61 side. The base layer is formed of a polymer such as polyimide, polyamide or polyimide amide; a metal such as SUS, nickel or copper. The thickness of the base layer is usually about 30 μm to 200 μm. The surface layer covering the surface of the base layer is formed of, for example, a fluororesin such as PFA, PTFE, FEP, etc., and the thickness is usually about 5 to 100 μm, preferably about 10 to 30 μm.

  In this embodiment, the pressure member 64 disposed inside the endless belt 62 is composed of a rubber pad 64a and a metal pad 64b, and presses the fixing roll 61 with a load of 35 kgf, for example, by a spring or an elastic body. To the holder 65. For the rubber pad 64a, an elastic body such as silicone rubber or fluorine rubber, a leaf spring, or the like is used. The surface of the rubber pad 64 a 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 present embodiment, silicone rubber having a width of 10 mm, a thickness of 5 mm, and a length of 320 mm is used for the rubber pad 64a. The durometer hardness (JIS K6253) of the rubber pad 64a is usually A30 or less. If the durometer hardness of the rubber pad 64a is excessively large, the toner cannot be sufficiently wrapped during fixing, and the image tends to be distorted.

The metal pad 64b is formed of a metal such as iron, aluminum, or SUS. The shape of the metal pad 64b is formed as a convex curved surface having an outer surface shape at the contact portion N having a constant radius of curvature. The metal pad 64b may be formed using a heat-resistant resin such as PPS, polyimide, polyester, polyamide.
In the fixing device 60 of the present embodiment, the endless belt 62 is covered by the pressure member 64 around the fixing roll 61 at a winding angle of about 40 °, and forms a contact portion N having a width of about 8 mm.

  The holder 65 is provided with an oil holding member 67 along the longitudinal direction of the fixing device 60. The oil holding member 67 is disposed so as to be in contact with the inner peripheral surface of the endless belt 62 and supplies an appropriate amount of lubricant. As the lubricant, 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, and a combination thereof are used.

(Second Embodiment)
FIG. 3 is a side sectional view showing a configuration of a fixing device 90 to which the second exemplary embodiment is applied. In the second embodiment, a fixing device using a fixing belt as a fixing rotator as a fixing member and using a pressure roll as a pressing rotator will be described.
As shown in FIG. 3, in the fixing device 90 according to the second embodiment, a fixing belt 92 as an example of a fixing rotator as a fixing member is disposed on the toner image holding 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 provided, and heat is supplied from the ceramic heater 82 to the contact portion N.

The ceramic heater 82 is formed so that the surface on the side of the pressure roll 91 is substantially flat and is pressed against the pressure roll 91 via the fixing belt 92 to form the contact portion N. Here, the ceramic heater 82 also functions as a pressure member.
A belt guide member 63 is provided inside the fixing belt 92 in order to prevent the fixing belt 92 from buckling.

The paper P that has passed through the contact portion N is peeled off from the fixing belt 92 due to a change in the curvature of the fixing belt 92 in the exit region (peeling contact portion) of the contact portion N.
Further, as a peeling auxiliary means, a peeling auxiliary member 70 is disposed on the downstream side of the contact portion N of the fixing belt 92. The peeling assisting member 70 is held by the 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. Further, a low friction sheet 68 is disposed between the inner peripheral surface of the fixing belt 92 and the ceramic heater 82 in order to reduce the sliding resistance between the inner peripheral surface of the fixing belt 92 and the ceramic heater 82.

  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 is formed by laminating a core (cylindrical cored bar) 911, a heat-resistant elastic body layer 912 coated on the outer peripheral surface of the core 911, and a surface layer 913 made of heat-resistant resin or rubber. Configure.

Here, the heat-resistant elastic layer 912 is required to have a low hardness so that the contact portion N can be easily formed. Examples of the material of the heat resistant elastic layer 912 include silicone rubber. In particular, foamed silicone rubber and balloon-mixed silicone rubber are preferable because they have high heat insulation properties and further shorten the warm-up time.
The surface layer 913 is formed by covering the fluororesin tube as described above.

  In the secondary transfer section 20 (see FIG. 1) of the image forming apparatus shown in FIG. 1, the sheet P on which the toner image has been electrostatically transferred is guided to the contact section N of the fixing apparatus 90 by the fixing inlet guide 56. When the paper P passes through the contact portion N, the toner image on the paper P is fixed by the pressure acting on the contact portion N and the heat supplied from the ceramic heater 82 on the fixing belt 92 side.

In the fixing device 90 according to the second embodiment, a fixing belt 92 as an example of a fixing rotating body serving as a fixing member is an endless belt whose original shape is formed in a cylindrical shape.
Here, the fixing belt 92 has a three-layer structure of a base made of a predetermined material, an elastic layer provided on the base, and a release layer formed by bonding a fluororesin tube on the elastic layer. .

The substrate is particularly required to have heat resistance and strength. For example, a heat resistant resin such as polyimide, polyamideimide, or polybenzimidazole, or a metal such as SUS is used.
As described in the elastic layer 612 (see FIG. 2) of the fixing roll 61 in the first embodiment, the elastic layer formed on the substrate is a rubber having a durometer hardness (JIS K6253) of about A15 to A45. It is formed using an elastic material.

In the second embodiment, the release layer of the fixing belt 92 is tetrafluoroethylene and perfluoroalkyl as described in the release layer 613 (see FIG. 2) of the fixing roll 61 in the first embodiment. It is a copolymer with vinyl ether, and contains a fluororesin having a composition of perfluoroalkyl vinyl ether of 2 mol% to 6 mol%, preferably 3 mol% to 5 mol%.
Further, the friction coefficient (μ) of the release layer of the fixing belt 92 is the maximum friction coefficient measured on the paper P at 170 ° C. within 1 second in accordance with the friction wear test method B method defined in JIS K7218. (Μ) is preferably 0.5 or more.
Further, the material constituting the release layer of the fixing belt 92 preferably has a melting temperature of 260 ° C. or higher measured using a differential scanning calorimetry (DSC) measuring method specified in JIS K7121.

  Hereinafter, the present invention will be described more specifically based on examples and comparative examples. In addition, this invention is not limited to a following example, unless the summary is exceeded.

(1) Production and Evaluation of Fixing Rotor As shown in the first embodiment, fixing rotor is evaluated using a fixing device having a fixing roll, an endless belt, and a pressure member provided inside the endless belt. Use to do.
In the image quality evaluation, the fixing rolls produced in the following examples and comparative examples are applied to an image forming apparatus (manufactured by Fuji Xerox Co., Ltd .: color printer DocuCenter Color 400), and the paper is passed under the following conditions. Do.

(2) Evaluation test of paper entry scratch A4 size mirror coat platinum (256 g / m ² , manufactured by Fuji Xerox Office Supply Co., Ltd.) is used as the paper. First, only one sheet is passed through an image forming apparatus (Fuji Xerox Co., Ltd .: color printer DocuCenter Color 400) so that the long side axis of the A4 sheet coincides with the sheet conveyance direction. Thereafter, a solid black image is output using A3 size digital coated paper (Fuji Xerox Office Supply Co., Ltd.).

The solid black image is evaluated based on the following criteria.
○: No paper entry flaw on the fixing roll can be confirmed.
Δ: Almost no paper entry scratches can be confirmed.
X: A paper entry scratch can be confirmed.

(3) Measurement of physical properties of release layer The fluororesin tubes used for the fixing rolls prepared in the examples and comparative examples were cut out, and the fluororesin tetrafluoroethylene and perfluoro constituting the fluororesin tube were prepared by ¹⁹ F-NMR. The composition (unit: mol%) of the alkyl vinyl ether is measured. The results are shown in Table 1.

(4) Measurement of coefficient of friction The coefficient of friction of the fluororesin tube surface used as the release layer of the fixing roll is measured by a test method based on the friction and wear test method B based on JIS K 7218. As a measuring device, a friction player (FPR-2100 type, manufactured by Reska Co., Ltd.) is used.
A test piece of a fluororesin tube is prepared by attaching a fluororesin tube before molding a fixing roll on an aluminum plate with a heat resistant tape. Next, a sheet of paper (C2 paper, manufactured by Fuji Xerox Office Supply Co., Ltd.) was prepared on the tip of an aluminum square bar test piece having a square shape with a side of 2.5 mm on one side, and this was heated to While maintaining at 170 ° C., the test piece is pressed against a fluororesin tube test piece under the conditions of a load of 1.0 kgf, a rotation radius of 25 mm, and a rotation speed of 150 mm / sec. The results are shown in Table 1.

(5) Measurement of melting temperature The melting temperature of the fluororesin constituting the fluororesin tube is measured using a differential scanning calorimeter (DSC-60, manufactured by Shimadzu Corporation) based on JIS K7121. The measurement conditions are a temperature increase rate of 10 ° C./min from room temperature. The results are shown in Table 1 (unit: ° C).

[Example 1]
A fixing roll is prepared as follows.
As the core as a base, an aluminum (A-5052 material) cylindrical body having an outer diameter (φ) of 30 mm, a thickness of 1.8 mm, and a length of 360 mm is used. The elastic layer is formed on the surface of the metal core using liquid silicone rubber (DY35-4039A / B, manufactured by Toray Dow Corning Co., Ltd.). The release layer uses pellets of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) having a perfluoroethyl vinyl ether (PEVE) content of 4.9 mol% (manufactured by Mitsui DuPont Fluorochemical Co., Ltd.), It is formed on the surface of the elastic layer.

First, using an extrusion molding machine, PFA pellets are extruded at a temperature of 300 ° C. to produce a fluororesin tube having a thickness of 30 μm. Next, the inner surface of the fluororesin tube is bonded. Subsequently, the bonded fluororesin tube is placed on the inner surface of the mold having the same diameter as the fixing roll, and the core metal is fixed on the same diameter as the mold.
Next, liquid silicone rubber is injected between the fluororesin tube and the core metal to a thickness of 0.6 mm, and then the entire mold is heated at 100 ° C. for 30 minutes to vulcanize the liquid silicone rubber. At the same time, vulcanization adhesion between the metal core and the fluororesin tube is performed. Thereafter, the entire mold is cooled, the core metal to which the fluororesin tube is vulcanized and bonded is extracted from the mold, and further subjected to secondary vulcanization at 200 ° C. for 4 hours to produce a fixing roll.
The prepared fixing roll is evaluated for the presence or absence of paper rush according to the aforementioned paper rush test. The results are shown in Table 1.

[Example 2]
A fixing roll was prepared in the same manner as in Example 1 except that a PVE amount of 5.8 mol% (manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) was used as the PFA pellet used for the release layer. Evaluate the presence or absence of paper entry scratches according to the paper entry damage evaluation test. The results are shown in Table 1.

Example 3
A fixing roll was prepared in the same manner as in Example 1 except that a PVE pellet having a PEVE amount of 3.0 mol% (manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) was used as the PFA pellet used for the release layer. Evaluate the presence or absence of paper entry scratches according to the paper entry damage evaluation test. The results are shown in Table 1.

[Comparative Example 1]
The same operation as in Example 1 was performed except that PFA pellets used for the release layer had a perfluoropropyl vinyl ether (PPVE) content of 1.6 mol% (P-66P, manufactured by Asahi Glass Co., Ltd.). A fixing roll is produced, and the presence or absence of paper rush damage is evaluated in accordance with the paper rush damage evaluation test described above. The results are shown in Table 1.

[Comparative Example 2]
A fixing roll was prepared by performing the same operation as in Example 1 except that PFE pellets used for the release layer had a PEVE amount of 6.4 mol% (Mitsui DuPont Fluorochemical Co., Ltd.). Evaluate the presence or absence of paper entry scratches according to the paper entry damage evaluation test. The results are shown in Table 1.

From the results shown in Table 1, when a fixing roll that forms a release layer using a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) having a perfluoroalkyl vinyl ether content of 2 mol% to 6 mol% is used. (Examples 1 to 3) It can be seen that even if thick paper is passed through, paper entry scratches are less likely to occur, and the scratches are not transferred to the image even during subsequent paper passing.
On the other hand, when the amount of perfluoroalkyl vinyl ether is less than 2 mol% (Comparative Example 1), it can be seen that the coefficient of friction on the surface of the release layer is reduced, and a paper rush is likely to occur. When the amount of perfluoroalkyl vinyl ether exceeds 6 mol% (Comparative Example 2), the friction coefficient on the surface of the release layer increases, but the melting temperature of the fluororesin constituting the release layer decreases. It can be seen that a paper rush damage is likely to occur.

  As described above in detail, by using the fixing member to which the present embodiment is applied, even when the thick paper is passed, the paper entry scratch is hardly generated, and the scratch is transferred to the image even after the paper is passed. A fixing device that does not occur can be obtained.

1 is a schematic configuration diagram illustrating an image forming apparatus according to an exemplary embodiment. 1 is a side cross-sectional view illustrating a configuration of a fixing device to which a first exemplary embodiment is applied. 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 ... developing device, 15 ... intermediate transfer belt, 16 ... primary transfer roll, 17 ... drum cleaner , 20 ... secondary transfer section, 60, 90 ... fixing device, 61 ... fixing roll, 62 ... endless belt, 63 ... belt guide member, 64 ... pressure member, 64a ... rubber pad, 64b ... metal pad, 65 ... holder, 66 DESCRIPTION OF SYMBOLS ... Halogen heater, 67 ... Oil holding member, 68 ... Low friction sheet, 69 ... Temperature sensor, 70 ... Peeling auxiliary member, 82 ... Ceramic heater, 91 ... Pressure roll, 92 ... Fixing belt, 612 ... Elastic layer, 613 ... Release layer

Claims (7)

A substrate;
An elastic layer formed on the substrate;
A release layer formed on the elastic layer,
The fixing member, wherein the release layer contains a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer having a composition of perfluoroalkyl vinyl ether of 2 mol% to 6 mol%.   The fixing member according to claim 1, wherein the perfluoroalkyl vinyl ether is perfluoroethyl vinyl ether or perfluoropropyl vinyl ether.   The release layer conforms to the friction and wear test method B defined in JIS K7218, and the maximum friction coefficient (μ) measured within 1 second at 170 ° C. with respect to the recording paper is 0.5 or more. 2. The fixing member according to claim 1, wherein the fixing temperature is 260 ° C. or higher measured using a differential scanning calorimetry (DSC) measurement method defined in JIS K7121.   The fixing member according to claim 1, wherein a thickness of the release layer is 10 μm to 50 μm. A fixing rotor having a release layer on the surface;
A pressurizing rotator provided opposite to the fixing rotator and forming a contact portion through which a recording material passes by being pressed against the fixing rotator,
The release layer of the fixing rotator is a binary copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether, and the composition of the perfluoroalkyl vinyl ether is 2 mol% to 6 mol%, and A fixing device comprising a fluororesin having a melting temperature of 260 ° C. or higher measured using a differential scanning calorimetry (DSC) method defined in JIS K7121.   The fixing rotator includes a base made of a predetermined material, an elastic layer provided on the base, and the release layer formed by bonding the fluororesin tube on the elastic layer. The fixing device according to claim 5, wherein the fixing device has a three-layer structure. Toner image forming means for forming a toner image;
Transfer means for transferring the toner image onto a recording material;
Fixing means for fixing the toner image transferred onto the recording material on the recording material,
The fixing means is
A fixing rotator having a release layer containing a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer having a composition of 2 to 6 mol% perfluoroalkyl vinyl ether on the surface;
An image forming apparatus comprising: a pressurizing rotator that presses against the fixing rotator and forms a contact portion through which the recording material passes.

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