JP2013164556A - Supply member, fixing device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a supply member that suppresses a reduction in releasability on the surface of a fixing member, a fixing device, and an image forming apparatus.SOLUTION: A feed roll 61 is arranged to contact opposite to a fixing belt 92 having a metal plating layer containing PTFE particles as a fluorine resin formed on the surface thereof; and accordingly, a layer containing PTFE as a fluorine resin is formed on the surface of the feed roll 61.

Description

  The present invention relates to a supply member, a fixing device, and an image forming apparatus.

  As a conventional thermo-compression fixing device, a fixing member in which a fluororesin is dispersed in a metal layer as a surface layer material is known (for example, Patent Document 1).

  A fixing device disclosed in Patent Document 1 includes a fixing member in which a fluororesin such as PTFE particles (tetrafluoroethylene resin particles) as a surface layer material is dispersed in a metal layer such as a nickel plating layer to form a release layer, and a fixing member A pressure member that follows and pressurizes the recording medium. The recording medium on which the unfixed toner image is held is passed through a nip region constituted by the fixing member and the pressure member, and is heated by the fixing unit when passing through the nip region. The toner image is fixed on the recording medium by pressing the unfixed toner image in a molten state against the recording medium with a nip pressure.

JP 2005-302691 A

  An object of the present invention is to provide a supply member, a fixing device, and an image forming apparatus that suppress a decrease in releasability on the surface of a fixing member.

  In order to achieve the above object, according to the present invention, the following supply member, fixing device, and image forming apparatus using the same are provided.

[1] A supply member for supplying a fluororesin by contacting the metal plating layer of the fixing member having a fluororesin-containing layer formed on the surface and a metal plating layer containing the fluororesin formed on the surface.

[2] a fixing member having a metal plating layer containing a fluororesin formed on the surface;
A supply member configured to supply a fluororesin to the metal plating layer of the fixing member by contacting the metal plating layer of the fixing member by forming a layer containing a fluororesin on the surface;
A fixing device that is disposed to face the fixing member and pressurizes the fixing member.

[3] a latent image carrier;
Latent image forming means for forming a latent image on the surface of the latent image holder;
Developing means for developing the latent image with a developer to form a developer image;
Transfer means for transferring the developer image to a recording medium;
An image forming apparatus comprising the fixing device according to [2].

  According to the first aspect of the present invention, it is possible to suppress a decrease in releasability on the surface of the fixing member as compared with the case where this configuration is not provided.

  According to the second and third aspects of the invention, compared to the case where the supply member is used as a pressure member, it is possible to suppress a decrease in the releasability of the fixing member surface over a long period of time.

It is explanatory drawing which shows the image forming apparatus which concerns on embodiment of this invention. 1 is a cross-sectional view of a fixing device used in an image forming apparatus.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is an explanatory diagram showing an image forming apparatus according to an embodiment of the present invention.

  FIG. 1 shows an image forming apparatus 100 of an intermediate transfer type generally called a tandem type. An image forming apparatus 100 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 as a developer by an electrophotographic method, and image forming units 1Y, 1M, and 1K. A primary transfer unit 10 that sequentially transfers (primary transfer) each color component toner image formed by 1C and 1K to the intermediate transfer belt 15, and a superimposed toner image transferred on the intermediate transfer belt 15 by a recording material (recording paper). A secondary transfer unit 20 that batch-transfers (secondary transfer) to a certain sheet P and a fixing device 60 that fixes the second-transferred image on the sheet 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 device 13 for writing an electrostatic latent image on the photoconductor 11 (in FIG. 1, the exposure beam is indicated by a symbol Bm); 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. An electrophotographic device such as a drum cleaner 17 is removed in order. 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. It 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 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. 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 receiving a fixing process with 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.

(Configuration of fixing device)
FIG. 2 is a cross-sectional view of a fixing device used in the image forming apparatus shown in FIG.

  As shown in FIG. 2, the fixing device 60 is formed on a contact surface between the fixing belt 92 as a fixing member for fixing the unfixed toner on the paper P and the fixing belt 92 provided facing the fixing belt 92. A pressure roll 91 as a pressure member that pressurizes the paper P in the nip region N, and a supply roll 61 as a supply member that is provided opposite to the fixing belt 92 and supplies the fluororesin to the fixing belt 92. Has been.

  The fixing belt 92 is an endless belt using a metal such as stainless steel, and has a nickel plating layer containing a fluorine resin such as PTFE particles on the surface thereof, and is disposed on the toner image holding surface side of the paper P. When the fixing belt 92 rotates, the end portion of the fixing belt 92 contacts an inner surface of an edge guide (not shown), so that the movement of the fixing belt 92 in the width direction (belt walk) is restricted. .

  Inside the fixing belt 92, a ceramic heater 82 which is a resistance heating element as an example of a heating unit is disposed. The ceramic heater 82 is formed so that the surface on the pressure roll 91 side is substantially flat and is pressed against the pressure roll 91 via the fixing belt 92, and forms a nip region N. The ceramic heater 82 supplies heat to the nip region N.

  The ceramic heater 82 also functions as a member that applies pressure to the paper P by being pressed by the opposing pressure roll 91. The sheet P that has passed through the nip region N is peeled off from the fixing belt 92 because the curvature of the fixing belt 92 changes in the exit region (peeling nipping portion) of the nip region N.

  A sliding 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 sliding sheet 68 may be configured separately from the ceramic heater 82 or may be configured integrally.

  The pressure roll 91 is disposed so as to face the fixing belt 92, and is rotated in the direction of arrow D by a driving motor (not shown), and the fixing belt 92 is rotated following the 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 a heat-resistant resin coating or a heat-resistant rubber coating. Each layer is made semiconductive by adding carbon black or the like as a countermeasure against toner offset as necessary.

  The supply roll 61 has a surface layer 62 containing PTFE in a cylindrical body made of metal such as aluminum, and the surface layer 62 is disposed to face the fixing belt 92 and is driven by the fixing belt 92 by contacting the surface layer 62. And the PTFE particles are supplied to the surface of the fixing belt 92. The supply roll 61 may be configured not to follow the fixing belt 92 and supply PTFE particles by friction generated by the surface of the fixing belt 92 and the surface of the supply roll 61. Further, the supply roll 61 may be replaced with a member having a shape other than the cylindrical shape, for example, a cubic shape, as long as it has PTFE on the surface and is in contact with the surface of the fixing belt 92.

  Further, as an auxiliary means for toner separation of the fixing belt 92, a peeling member 70 is disposed on the downstream side of the nip region N of the fixing belt 92. The peeling member 70 is held by the 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.

  In the above configuration, every time the paper P passes through the nip region N, the fixing operation of the unfixed toner image, that is, heating and pressurization by the fixing belt 92 and the pressure roll 91 is performed. The PTFE particles contained in the plating layer are selectively worn by the fixing operation.

  On the other hand, the fixing belt 92 is in contact with the supply roll 61, whereby the nickel plating layer on the surface of the fixing belt 92 is supplied with PTFE particles from the surface of the supply roll 61. With the above operation, the fixing device 60 can suppress a decrease in the content of PTFE particles contained in the nickel plating layer on the surface of the fixing belt 92 due to the fixing operation. A decrease in moldability can be suppressed.

  Further, since the fixing belt 92 has a nickel plating layer mainly composed of a metal having high heat conductivity on the surface, the fixing belt 92 can improve thermal efficiency as a fixing member.

Example 1
(Fixing belt manufacturing method)
(Preparation of base material)
First, a stainless steel plate (SUS304, thickness 0.2 mm) was formed into a cylindrical container shape having a depth of about 10 mm by pressing and deep drawing. Thereafter, it was molded into a cylindrical shape having an opening and a bottom by rotary plastic processing (spindle processing). The opening and bottom were cut and removed to obtain an endless belt (seamless belt) having an inner diameter of 30 mm, a length of 370 mm, and a thickness of 40 μm.

(Preparation of surface layer)
On the surface of the endless belt obtained as described above, an electroless nickel plating layer (thickness: 10 μm) having a PTFE particle content of about 30 vol% is formed, and heat treatment is performed at 320 ° C. for 1 h in the atmosphere to fix the fixing belt 92. It was.

(Preparation of facing member)
A cylindrical body made of aluminum (A-5052 material, outer diameter φ20 mm, wall thickness 2 mm) was used as a core, and the surface thereof was coated with PTFE so as to face the surface of the fixing belt as shown in FIG.

(Create supply roll)
A cylindrical body made of aluminum (A-5052 material, outer diameter φ10 mm, wall thickness 2 mm) was used as a core metal, and the surface was coated with PTFE to form a supply roll.

(Fixing thermal efficiency evaluation)
The fixing thermal efficiency was evaluated by the following crease evaluation. Note that the crease evaluation is one of the evaluation indexes for the fixability of the fixed image and the fixability of the image.

  The image forming apparatus (Docu Center IV C3370) manufactured by Fuji Xerox Co., Ltd. is modified to obtain the image forming apparatus 100 and the fixing apparatus 60 shown in FIG. The image was set in the apparatus 60, and a fixed image having a predetermined image pattern was obtained on the paper P.

Next, after the paper P on which the fixed image is formed is bent once, it is rolled on the bent portion at a constant speed with a roll having an overload of about 500 g (outer diameter 600 mm, made of brass). The crease was rubbed lightly, and the missing state of the fixed image was evaluated in the following three stages using a limit sample, and the fixing time required to become G11 was measured.
G11: A crease is formed, but the image is not missing or is low. G12: A white faint crease is observed, and the image is partially missing.
G13: White band-like folds are conspicuous, and more than half of the image is missing

  Here, in the fixed image when the fixing temperature was set to 150 ° C., the fixing time during which the above-described white image width was within the allowable range was evaluated, and it was G11 at 5 msec. The above evaluation results are shown in Table 1.

  The fixing thermal efficiency is “◎” when the fixing time at which the fixing temperature is 150 ° C. and the crease is G11 is 7 msec or less, “◯” when it is 15 msec or less, and “x” when it is 15 msec or more.

(Evaluation of toner releasability)
Evaluation of the toner releasability of the fixing belt 92 was performed by applying a waste to the image passing portion of the fixing belt 92 after the fixing operation, cleaning the surface of the fixing belt 92, and evaluating the degree of contamination of the waste.

The dirt grade was ranked according to the grade sample.
G21: No dirt is confirmed by visual observation. G22: If attention is paid, some dirt is visually observed.
G23: Dirt is observed visually.
G24: There is much dirt.
G25: There is very much dirt.
Represents.

  The above evaluation was carried out at an initial stage after printing 15,000 sheets of A4 paper (15 kPV) and after printing 100,000 sheets of A4 paper (100 kPV), and the toner releasability and durability of the toner releasability were evaluated. . The initial toner releasability is “◯” when the stain grade is G21, and “x” otherwise. Further, the durability of the toner releasability was evaluated as “◯” when the stain grade maintained G21, and “X” when it was not maintained.

  As a result, when the supply roll 61 was provided, the fixing belt 92 was not visually contaminated from the initial stage until 100 kPV later (G21 was maintained).

(Comparative Example 1)
Comparative Example 1 was performed under the same conditions as in the example except that the supply roll 61 was not provided.

(Comparative Example 2)
Comparative Example 2 was performed under the same conditions as in the example except that the supply roll 61 was not provided and that the surface layer of the fixing belt 92 was PFA having a thickness of 20 μm.

(Comparative Example 3)
In Comparative Example 3, the surface layer of the fixing belt 92 of Comparative Example 2 was used as PFA having a thickness of 10 μm.

1Y, 1M, 1C, 1K Image forming unit 10 Primary transfer unit 11 Photosensitive drum 12 Charger 13 Laser exposure unit 14 Developer 15 Intermediate transfer belt 16 Primary transfer roll 17 Drum cleaner 20 Secondary transfer unit 22 Secondary transfer roll 25 Backup roll 26 Power supply roll 31 Drive roll 32 Support roll 33 Tension roll 34 Cleaning backup roll 35 Intermediate transfer belt cleaner 40 Control unit 42 Reference sensor 43 Image density sensor 50 Paper tray 51 Pickup roll 52 Transport roll 53 Transport chute 55 Transport belt 56 Fixing Entrance guide 60 Fixing device 61 Supply roll 62 Surface layer 68 Sliding sheet 70 Peeling member 71 Peeling baffle 72 Holder 82 Ceramic heater 91 Pressure roll 92 Fixing belt 100 Image forming device 911 Core 9 2 heat-resistant elastic layer 913 release layer

Claims (3)

  A supply member for supplying a fluororesin by contacting the metal plating layer of the fixing member having a fluororesin-containing layer formed on the surface and a metal plating layer containing the fluororesin formed on the surface. A fixing member having a metal plating layer containing a fluororesin formed on the surface;
A supply member configured to supply a fluororesin to the metal plating layer of the fixing member by contacting the metal plating layer of the fixing member by forming a layer containing a fluororesin on the surface;
A fixing device that is disposed to face the fixing member and pressurizes the fixing member. A latent image carrier,
Latent image forming means for forming a latent image on the surface of the latent image holder;
Developing means for developing the latent image with a developer to form a developer image;
Transfer means for transferring the developer image to a recording medium;
An image forming apparatus comprising the fixing device according to claim 2.

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