JP4093697B2 - Release sheet - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a release sheet for peeling a sheet from a fixing member such as a fixing roller or a fixing belt installed in an electrophotographic apparatus such as a copying machine or a laser beam printer.
[0002]
[Prior art]
An electrophotographic apparatus such as a copying machine or a laser beam printer is provided with a heat fixing device for developing an electrostatic latent image formed on a photosensitive drum on a sheet using a developer such as toner and fixing the image thereafter. It has been. The heat fixing device has a fixing member such as a fixing roller and a fixing belt for fixing the toner on the sheet by heating and melting the developer and pressurizing the developer.
2. Description of the Related Art Conventionally, a separation claw is provided on a fixing member and a pressure roller that presses the sheet against the fixing member in order to prevent the sheet from being wound around the roller and hindering smooth operation. This separation claw prevents the paper from being wound around the roller or the like by scooping up the end of the paper while sliding the tip thereof on the outer peripheral surface of the roller or the like.
The width of the contact portion of the separation claw with the roller or the like is about 1 to 10 mm, and 4 to 16 pieces are arranged for one roller or the like. Since the separation claw is locally in contact with the roller or the like, the roller or the like is inevitably partially worn and a good image cannot be obtained. In addition, since the paper is locally contacted with the paper, it is easy to scrape off the developer transferred to the paper, and the paper may be easily soiled due to the scraped developer adhering to the separation claw. There was a problem.
For such a problem, for example, Japanese Patent Application Laid-Open No. 59-188681 proposes a paper peeling device capable of making line contact with a roller.
[0003]
[Problems to be solved by the invention]
However, the paper peeling device described in JP-A-59-188681 is for fixing and supporting a plastic plate made of fluororesin or the like having a thickness of 0.05 mm or more on a metal base plate, and slightly protruding from the metal base plate. The tip of the plastic plate is in line contact with the fixing roller. For this reason, there is a problem that the tip of the plastic plate is turned up by plastic deformation and the paper peeling performance is lowered.
[0004]
In particular, developers used in recent electrophotographic apparatuses have improved the color developability, and the binder resin, which is one of the components of the toner, has also moved to a highly transparent polyester system. Since the toner having toner has very high adhesiveness, in the paper peeling apparatus described in JP-A-59-188681, the toner adheres to the metal base plate or the joint between the metal base plate and the plastic plate. There's a problem.
[0005]
The present invention has been made to cope with such a problem, and can sufficiently make a line contact with a roller, and does not damage a fixing member such as a roller at the contact portion, and has excellent paper peeling performance for a long time. It aims at providing the release sheet which can be maintained.
[0006]
[Means for Solving the Problems]
Release sheet of the present invention, peeling the sheet from the fixing roller of an electrophotographic apparatus using a toner having a polyester-based binder resin, a metal thin plate having a thickness of 50 ~ 300 mu m, contact with the fixing roller of the sheet metal corner portion in contact with the fixing roller by rounding the corners of the sites have rounded, the site of to the back surface of the end surface as to contact with the fixing roller from the surface of the thin metal plate, a thickness of 5 ~ 50 mu fluororesin film having a thickness of 10 ~ 200 mu m via a silicone adhesive of m is characterized by comprising affixed.
Here, the contact with the fixing member means that one side of the release sheet is in line contact with the axial direction of the fixing member, and the proximity means that the paper can be prevented from being wrapped around the fixing member. It means that one side of the release sheet is disposed close to the fixing member.
The fixing member has various shapes such as a roller shape, a film shape, or a belt shape that can come into contact with the paper in a process of fixing the developer on the unfixed paper on the paper by pressurizing simultaneously with heating. Refers to a member. For example, a fixing roller or a pressure roller.
[0007]
The fluororesin film is composed of a polytetrafluoroethylene polymer (hereinafter abbreviated as PTFE), a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (hereinafter abbreviated as PFA), a tetrafluoroethylene-hexafluoropropylene copolymer. The film is made of at least one resin selected from a polymer (hereinafter abbreviated as FEP) and a tetrafluoroethylene-ethylene copolymer (hereinafter abbreviated as ETFE).
[0008]
The surface of the fluororesin film attached to the metal plate is surface-treated.
In addition, the silicone-based pressure-sensitive adhesive for attaching the fluororesin film and the metal plate contains dimethylpolysiloxane raw rubber.
[0009]
By sticking a fluororesin film to a metal plate, particularly a metal thin plate having a thickness of 300 μm or less in contact with or close to the roller, the tip of the metal thin plate is not turned over by plastic deformation. Moreover, since excellent adhesiveness is obtained by using a predetermined silicone-based pressure-sensitive adhesive and performing a surface treatment such as an etching treatment, the durability is excellent.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An example of the release sheet will be described with reference to FIGS. FIG. 1 is a schematic view of a heat roller type fixing device using a release sheet, and FIG. 2 is a partially enlarged perspective view of the release sheet.
The fixing device has a built-in heater 5a, the fixing roller 5 that rotates in the direction of arrow A, the pressure roller 6 that contacts the fixing roller 5 and rotates in the direction of arrow B, and the fixing roller 5 and the pressure roller are in contact with each other. And the release sheet 1 disposed in the vicinity of the nip portion 7 formed in this manner. The release sheet 1 is provided at a position in contact with or close to the fixing roller 5 so that the paper 8 that has passed through the nip portion 7 can be released from the fixing roller 5.
As shown in FIG. 2, the release sheet 1 has a fluororesin film 4 attached to the surface of the metal plate 2 via a metal plate 2 and a silicone-based adhesive 3. The fluororesin film 4 is affixed to a site including a site 1 a where the release sheet 1 is in contact with or close to the fixing roller 5.
Further, the release sheet 1 has a contact width (L) that is substantially the same length as the axial length of the roller. Since the contact width is large, the contact pressure per unit area to the roller is reduced, and local wear on the roller surface can be prevented. Note that the length substantially the same as the axial length of the roller means a length to the extent that the above-mentioned effect is obtained. Specifically, it is at least about half of the axial length of the roller, and the axial length of the roller. Same or slightly longer.
[0011]
As a material of the metal plate 2, iron, aluminum, copper, stainless steel or the like can be used. The plate thickness is preferably in the range of 50 to 300 μm. If it is less than 50 μm, it may not be possible to apply a pressure contact force to the roller to secure the peeling force. If it exceeds 300 μm, the paper to be peeled may hit the leading edge of the release sheet, which may cause jamming. There is.
[0012]
The thickness of the fluororesin film 4 is preferably in the range of 10 to 200 μm, more preferably 40 to 80 μm. If the thickness is less than 10 μm, the metal sheet may be exposed due to the possibility of tearing due to friction with the developer or slight wear. Moreover, it becomes easy to wrinkle in the sticking process to a metal thin plate, and handling becomes difficult. When the thickness exceeds 200 μm, the paper peelability decreases.
[0013]
The material of the fluororesin film 4 is PTFE, PFA, FEP, ETFE, polychlorotrifluoroethylene, chlorotrifluoroethylene-ethylene copolymer, polyvinylidene fluoride, polyvinyl fluoride, tetrafluoroethylene-hexafluoropropylene-per A film made of a known fluororesin of a fluoroalkyl vinyl ether copolymer can be used.
[0014]
Among the fluororesin films described above, a film made of PTFE, PFA, FEP, and ETFE is excellent in non-adhesiveness to the developer, and also has sufficient heat resistance, so it is suitable for the release sheet according to the present invention. It is. In addition, by forming the fluororesin film from a fluororesin blended with carbon fine powders such as ketjen black and acetylene black, it is possible to prevent a decrease in paper peelability due to static electricity.
[0015]
The fluororesin film is preferably subjected to a surface treatment on the surface attached to the metal plate. Here, the surface treatment is a treatment for enhancing the adhesion effect when the fluororesin film is adhered to the metal plate via a silicone-based pressure-sensitive adhesive material described later. Examples thereof include corona discharge treatment, sputter etching treatment, plasma etching treatment, TOS treatment with metallic sodium, and ultraviolet irradiation treatment.
[0016]
Examples of the silicone pressure-sensitive adhesive used in the present invention include a pressure-sensitive adhesive obtained by condensing a copolymer composed of SiO ₂ units and (CH ₃ ) ₃ SiO units and diorganopolysiloxane raw rubber. By using this silicone-based pressure-sensitive adhesive, the fluororesin film can be firmly bonded to the metal plate, and particularly important, the adhesive effect can be maintained even at the fixing temperature. Further, the pressure-sensitive adhesive layer can be thinned, and the pressure-sensitive adhesive layer does not increase the thickness of the release sheet so as to impair the release function. The thickness of the silicone-based pressure-sensitive adhesive layer should be in the range of 5 to 50 μm. If it is thinner than 5 μm, sufficient adhesive effect cannot be obtained, and if it is thicker than 50 μm, the thickness of the release sheet becomes relatively thick. This is not preferable because the paper peelability is lowered.
[0017]
The release sheet according to the present invention can be used to release a sheet from a fixing member such as a fixing roller or a fixing belt installed in an electrophotographic apparatus.
[0018]
【Example】
Example 1
A metal thin plate made of stainless steel (SUS304CSP) having a thickness of 100 μm was cut into a contact width (L) of 300 mm in length and 40 mm in width to prepare a metal thin plate as a release sheet substrate. The burrs generated on the cut surface of the release sheet substrate were carefully removed, and the corners that would be in contact with the roller were rounded to a radius of curvature of about R0.01 mm to R0.03 mm.
A PTFE film having a thickness of 50 μm (Bearly FL3090 manufactured by NTN Precision Resin Co., Ltd.) was prepared as a fluororesin film, and an etching process was performed in which the surface to be attached to the metal thin plate was immersed in an ammonia solution of metal sodium.
A silicone-based pressure-sensitive adhesive solution containing dimethylpolysiloxane raw rubber (KR101 manufactured by Shin-Etsu Chemical Co., Ltd.) was uniformly applied to the etched surface of the fluororesin film and dried by heating at 120 to 200 ° C. Thereafter, it was naturally cooled to room temperature to form a silicone adhesive layer having a thickness of about 30 μm.
[0019]
Lay the fluororesin film on the smooth plate so that it does not become wrinkled with the surface having the adhesive layer facing up, and then thoroughly degrease the chamfered metal sheet with petroleum benzine, then in the center of the fluororesin film The roller contact part which rounded the corner | angular part of a metal thin plate was arrange | positioned. The film was affixed to the surface of the thin metal plate with this roller contact portion as a boundary. In this way, a release sheet was formed by adhering the fluororesin film to the roller contact portion and the back surface with a silicone-based adhesive. The total thickness of the release sheet is 230 μm.
[0020]
This release sheet is set in the fixing section of a heat roller type test copying machine (fixing temperature 190 ° C, A4 copying speed 57 sheets / min), and a line chart with an image ratio of 30% is used as the original and A4 plain paper is used. A copy test with 5,000 continuous paper passes was performed up to 30,000. The test machine was stopped every 5,000 sheets, and the copied paper was visually checked for image degradation. Further, the release sheet was removed from the fixing portion, and the wear of the fluororesin, the presence or absence of toner adhesion, and the wear state of the fixing roller were confirmed.
As a result of the test, the image of the release sheet of Example 1 was not reduced until the end of the 30,000 sheet passing test, and the fluororesin film confirmed after the end of the sheet passing test was not damaged. Further, no toner adhered to the release sheet, and further no wear of the fixing roller was observed.
[0021]
Comparative Example 1
The same thin metal plate as in Example 1 was prepared, and a 50 μm thick PTFE film (Bearly FL3090 manufactured by NTN Precision Resin Co., Ltd.) was applied to this thin metal plate from one side of the thin metal plate so that one end thereof was a free end. It was fixed and supported by projecting a length of mm.
This release sheet was set in the test copying machine used in Example 1, and the same copying test by continuous paper passing as in Example 1 was performed.
As a result of the test, it was confirmed that the paper peeling device of Comparative Example 1 was adhered to the metal thin plate after 10,000 sheets were confirmed. However, since no image degradation was observed on the paper after copying, the test was continued. After 15,000 sheets, deformation of the plastic plate and image degradation on the paper after copying were observed. For this reason, subsequent tests were discontinued.
[0022]
Comparative Example 2
A release sheet identical to that of Example 1 was prepared except that the fluororesin film was replaced with a PTFE film with an acrylic adhesive (Nitoflon adhesive tape manufactured by Nitto Denko Corporation).
This release sheet was set in the test copying machine used in Example 1, and the same copying test by continuous paper passing as in Example 1 was performed.
As a result of the test, the image of the release sheet of Comparative Example 2 was not deteriorated until 5,000 sheets were passed, but jamming occurred until about 9,000 sheets were passed. When the release sheet was confirmed, the fluororesin film was peeled off from the metal thin plate, and the toner entered the gap where the metal thin plate and the film were peeled off.
[0023]
【The invention's effect】
The release sheet of the present invention has an excellent paper releasability because a fluororesin film is affixed via a silicone-based adhesive to a portion of a metal plate that is in contact with or close to a fixing member such as a fixing roller or a fixing belt. And a release sheet having both high temperature durability and non-toner adhesion.
[0024]
Further, since the fluororesin film is selected from predetermined fluororesins, non-toner adhesion is further improved.
[0025]
Since the adhesive surface of the fluororesin film is etched, the adhesion between the fluororesin film and the silicone pressure-sensitive adhesive is improved. As a result, the fluororesin film becomes difficult to peel off from the metal plate.
[0026]
Since the silicone-based pressure-sensitive adhesive contains dimethylpolysiloxane raw rubber, the fluororesin film can be firmly adhered to the metal thin plate, and a release sheet is obtained in which the fluororesin film does not peel even when continuously exposed to a high temperature such as a fixing temperature.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a fixing device using a release sheet.
FIG. 2 is a partially enlarged perspective view of a release sheet.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Release sheet 2 Metal plate 3 Silicone adhesive 4 Fluororesin film 5 Fixing roller 6 Pressure roller 7 Nip part 8 Paper

Claims (1)

In release sheet for peeling the sheet from the fixing roller of an electrophotographic apparatus using a toner having a polyester binder resin, made of a metal thin plate having a thickness of 50 ~ 300 μ m,
The release sheet corner portion in contact with the fixing roller by rounding the corners of the site in contact with the fixing roller of the sheet metal are rounded, the end face in contact with the fixing roller from the surface of the thin metal plate Dimethylpolysiloxane raw rubber is included in the part up to the back as shown Fluororesin film of the unfilled polytetrafluoroethylene polymer having a thickness of 5 ~ 50 μ ~ 10 thick through the silicone adhesive of m 200 mu m is affixed,
Attaching surface to the thin metal plate of the fluororesin film, release sheet, wherein a surface treatment is applied.

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