JP2002266846A - Pressure roller, heating system, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure roller, a heating system using the pressure roller, and an image forming device having the heating system as a heat fixing apparatus, in which the pressure roller is low in heat conductivity to remove a not so much amount of heat from a heating means, a surface of the pressure roller is smooth and not hardly generate dirt by toner at a time of pressurization, and charging up of the surface is suppressed even if a high resistance paper passes on the roller. SOLUTION: In this pressure roller, an elastic body layer is disposed around a core metal, and a mold-released layer is disposed as an outermost layer. The elastic body layer is foamed rubber elastomer (sponge rubber), and the mold-released layer is a fluororesin tube, and a conductive layer is disposed between the elastic body layer and the mold-released layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure roller, a heating device using the pressure roller, and an image forming apparatus.

[0002]

2. Description of the Related Art A heating device is used for fixing an unfixed image on a recording material used in an image forming apparatus, and an image for heating a recording material to improve surface properties such as gloss. Conventionally, it has been widely used as a heating device or a heat treatment device for drying or laminating a material to be heated.

Hereinafter, a conventional heating device will be described with reference to a heating and fixing device provided in an image forming apparatus such as an electrophotographic copying machine and a printer.

A heat fixing device provided in an image forming apparatus forms and supports a recording material (transfer sheet, electrostatic recording paper, electrofax paper, printing paper, etc.) by a transfer method or a direct method in the image forming apparatus. Unfixed image corresponding to target image information
(Toner image) is thermally fixed on the surface of the recording material as a permanently fixed image. As a heat fixing device, as in a heat roller system or a film heating system, a heating unit and a pressing unit are pressed against each other to form a pressure nip (fixing nip), and an image is fixed to the pressure nip. 2. Description of the Related Art A contact-heating-type apparatus for fixing an unfixed image on a surface of a recording material by heat and pressure by introducing a recording material to be pinched and transporting the recording material is widely used. Hereinafter, these heating devices will be described.

A) Heat Roller Fixing Method A heat fixing device of the heat roller fixing method is a parallel pressing roller in which a heating roller (fixing roller) as a heating means and an elastic pressure roller as a pressing means pressed against the heating roller are used. The roller pair is rotated as a basic structure, and a recording material to be image-fixed is introduced into a pressure contact nip formed between the roller pair, nipped and conveyed, and the heat of the heating roller is applied to the pressure contact nip. The pressure is used to fix an unfixed image on the surface of the recording material by heat and pressure.

B) Film heating system A heating fixing device of a film heating system is disclosed in Japanese Patent Application Laid-Open No. 63-313182.
JP, JP-A-2-57878, JP-A-4-44075-44083
And JP-A-4-204980-204984. The heat fixing device of the film heating type has a heating element as a heating means and a heat-resistant film (fixing film), and presses the heat-resistant film against the heating element with an elastic pressure roller as a pressure means, thereby forming a pressure nip portion. The heat-resistant film is brought into close contact with the heating body in the press-contact nip portion and slid and conveyed, and a recording material to be image-fixed is introduced between the heat-resistant film in the press-contact nip portion and the elastic pressure roller. The unfixed image is conveyed together with the heat-resistant film, and the unfixed image is hot-press fixed on the surface of the recording material by the heat from the heating body applied via the heat-resistant film and the pressing force of the press-contact nip portion. The recording material is separated from the heat-resistant film after passing through the pressure nip.

The film heating type heating apparatus can use a linear heating element having a low heat capacity as a heating element and a thin film having a low heat capacity as a heat-resistant film, thereby saving power and shortening a wait time (quick time). Startability) is possible.

[0008] In a film heating type heating device, an endless film is used as a heat-resistant film.
As a rotation driving method of this film, a driving roller is provided on the inner peripheral surface side of the film, and the film is driven to rotate while applying tension to the film, and a rotating body for pressing as a pressing means by loosely removing the film from the film guide There is a method in which the film is driven to be driven by the rotating body for pressing by driving the rotating body. However, since the number of parts is small, the latter rotating body driving method for the pressing is often adopted.

As in the heat roller type or film heating type heat fixing device described above, a heating means and a pressure roller are opposed to each other to form a pressure nip portion as a heated material heating portion, and the pressure nip portion is formed in the pressure nip portion. In a heating device that heats and pressurizes the material to be heated by introducing and transporting the material to be heated, the pressure roller has elasticity in order to increase the speed of the device and reduce the wait time. By increasing the width of the pressure contact nip formed between the heating means and its elastic deformation, take time to give sufficient heat to the material to be heated, and improve the efficiency of applying heat to the material to be heated. Is also good. However, simply increasing the width of the press-contact nip may increase the size of the heating device itself and increase power consumption at the same time. Therefore, in order to reduce the size, cost, and power consumption of the device, it is desired to further improve the thermal efficiency of the device.

From the viewpoint of improving the thermal efficiency of the apparatus, the amount of heat taken from the heating means to the pressure means cannot be ignored.
As means for reducing the heat capacity of the pressurizing means, for example,
No. 114281 discloses that a pressurizing rotary body having excellent heat insulating properties can be obtained by a manufacturing method excellent in mass productivity by including a hollow filler in an elastic layer of a pressing roller as a pressing means. Is disclosed. However, this pressurizing rotator uses an inorganic filler containing air inside such as hollow silica, alumina, glass, and glass fiber as a hollow filler, but the inside of such an inorganic system is hollow. When the filler is used, since the filler is hard, the elastic layer of the pressure roller becomes hard, and a large pressing force may be required to increase the fixing nip width.

In recent years, in the heating apparatus of the electrophotographic image forming apparatus, the size of the apparatus has been reduced, and the diameter of a pressure roller used therein has also been reduced. Therefore, in order to secure a nip width at the time of fixing when the diameter of the pressure roller is reduced, the elastic layer covering the outer periphery of the core of the pressure roller tends to have a low hardness.

For example, as disclosed in Japanese Patent Publication No. 4-77315, a foamed elastic body (sponge rubber) is
For example, many using foamed silicone rubber have been put to practical use. However, when the foaming agent mixed in the silicone rubber foams by heating, the foaming pressure breaks the silicone rubber wall to expose the foam cell, or the silicone rubber wall separating the foam cell from the atmosphere. It can become very thin, forming a virtual recess.
Also, when silicone rubber is foamed in a mold,
Since the foaming pressure goes in an irregular direction, irregular foaming stress is likely to be generated in the rubber, and when the silicone rubber is removed from the mold after foaming, the irregular foaming stress is released and the rubber surface becomes uneven. Sometimes. When a roller having an elastic layer made of foamed silicone rubber having irregularities on its surface is used as a pressure roller, the molten toner offset to a heating roller or a heating film is transferred to an exposed foam cell or a depression of the pressure roller. Then, the pressure roller may be stained.

Further, a foamed elastic body (sponge elastic body) formed by foaming silicone rubber is formed on a cored bar, and PFA (tetrafluoroethylene / perfluoroalkyl ether copolymer) and PTFE (PTFE) are formed on the outer peripheral surface thereof. When a heat-resistant release layer of a fluororesin such as polytetrafluoroethylene) is formed by coating, a coating agent may enter the exposed foam cells and the concave portions, and it is difficult to form a uniform release layer having a smooth surface.

Further, when the release layer is formed by covering the fluororesin tube, the fluororesin tube becomes uneven in accordance with a foam cell in a pressurized state. The pressure roller may be stained with certain toner.

Therefore, in order to solve the unevenness during pressurization,
There is a method in which a foamed cell is filled with a silicone adhesive to smooth the surface, and then covered with a fluororesin tube.
Such a roller generally has an insulating foamed rubber, an insulating silicone adhesive, and an insulating fluororesin tube sequentially on a cored bar. When a high-resistance sheet left in a low-humidity environment is passed, the surface potential of the pressure roller is charged up to more than ten kV due to frictional charging, which disturbs an image or causes a clearly visible offset. Sometimes.

As a solution to this, it is conceivable to make the fluororesin tube on the surface conductive. However, when the fluororesin tube is made conductive, the releasability of the fluororesin tube is reduced, and the pressure roller may be contaminated with toner on the back of the paper even though the roller surface is smooth when pressed. .

It is also conceivable to make the foamed rubber conductive. However, in general, carbon is often dispersed in the conductive treatment, and dispersing carbon increases the thermal conductivity, which may cause a problem in heat insulation.

Therefore, as a countermeasure against the offset, it is required to cope with a method other than the above.

[0019]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a low-heat conductive material which does not deprive much heat from the heating means, has a smooth surface when pressurized, does not easily cause toner contamination, and has a high resistance paper. And a heating device using the pressure roller, and an image forming apparatus including the heating device as a heating and fixing device. .

[0020]

The above objects can be achieved by the present invention described below. (1) A pressure roller having an elastic layer and a release layer as an outermost layer around a cored bar, wherein the elastic layer is a foamed elastic body (sponge rubber), and the release layer is A pressure roller, which is a fluororesin tube and has at least a conductive layer between the elastic layer and the release layer. (2) The pressure roller according to (1), wherein the conductive layer is a silicone adhesive layer. (3) Heating means for heating the sheet-like material to be heated, and a pressure roller disposed opposite to the heating means and pressed against the heating means, wherein the heating means and the pressure roller A heating device for heating a material to be heated by introducing the material to be heated into a press-contact nip portion formed and nipping and transporting the material, wherein the pressure roller is the pressure roller of (1) or (2). A heating device, characterized in that: (4) means for forming and carrying an unfixed image on a recording material;
An image forming apparatus comprising: a heat fixing device that heats and fixes an unfixed image onto a recording material, wherein the heat fixing device is the heating device according to (3).

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The pressure roller of the present invention comprises an elastic layer made of an insulating foamed elastic body (sponge rubber) and covered with an insulating fluororesin tube as a release layer. A conductive layer, preferably a silicone adhesive layer is provided between the mold layer and the mold layer.

In the present invention, since the elastic layer of the pressure roller is made of insulating foamed elastic material (sponge rubber), it is not necessary to put a filler for controlling the resistance value into the elastic layer. It can be softer than the one you put. Further, low thermal conductivity which is preferable for the elastic layer, specifically 0.146 W / m
-It is advantageous in realizing a thermal conductivity of K or less.

Further, by providing a conductive layer, preferably a silicone adhesive layer, between the foamed elastic body and the fluororesin tube, the triboelectric charge of the insulating fluororesin tube is released to this conductive layer, and the friction of the insulating fluororesin tube is reduced. Charging can be suppressed. If the conductive layer also serves as the adhesive layer,
This is preferable because irregularities on the surface of the foamed elastic layer can be filled. Further, even if an adhesive layer is separately provided, irregularities on the surface of the foamed elastic body layer can be filled, and the same effect can be obtained.
From the viewpoint of reducing the diameter of the pressure roller and productivity, it is preferable to provide a conductive adhesive layer in which the conductive layer also serves as the adhesive layer.

Therefore, in the present invention, the fluororesin tube provided on the surface layer does not need to be filled with a filler for controlling the resistance value and the like, and a pure fluororesin layer can be formed, so that the releasability is excellent. The toner hardly adheres.

That is, the pressure roller according to the present invention, having the above-described configuration, has an excellent effect of being excellent in heat insulating properties and less likely to cause offset and toner contamination.

The heating device using the pressure roller according to the present invention can be reduced in size and speed, has low power consumption, is hardly contaminated with offset or toner, and does not cause image disturbance.

Further, the image forming apparatus using the heating device of the present invention as the heat fixing device has no image deterioration, consumes low power, has a short first printout, and has good fixability.

Hereinafter, the image forming apparatus, the heating device (heating fixing device), and the pressure roller of the present invention will be described.

(1) Example of Image Forming Apparatus FIG. 1 is a schematic structural view of an example of the image forming apparatus of the present invention. The image forming apparatus of this embodiment is a laser beam printer using a transfer type electrophotographic process.

Reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member (hereinafter, referred to as a photosensitive drum) as an image bearing member.
At a predetermined peripheral speed (process speed) in the clockwise direction. The photosensitive drum 1 has a configuration in which a photosensitive material layer of OPC, amorphous Se, amorphous Si, or the like is formed on the outer peripheral surface of a cylinder (drum) -shaped conductive substrate made of aluminum, nickel, or the like.

The photosensitive drum 1 is uniformly charged to a predetermined polarity and potential by a charging roller 2 as charging means during the rotation process. Scanning of the uniformly charged surface of the rotating photosensitive drum 1 by a laser beam modulated (ON / OFF controlled) corresponding to a time-series electric digital pixel signal of target image information output from the laser beam scanner 3. By performing the exposure L, an electrostatic latent image of target image information is formed on the rotating photosensitive drum surface.

The formed latent image is developed by the developing device 4 with the toner T and visualized. As a development method, a jumping development method, a two-component development method, an FEED development method, or the like is used, and a combination of image exposure and reversal development is often used.

On the other hand, the transfer material P as a recording material stored in the paper feed cassette 9 is fed out one by one by driving the paper feed roller 8, and passes through a sheet path having a guide 10 and a registration roller 11. The sheet is fed at a predetermined control timing to a transfer nip portion which is a press contact portion between the transfer roller 1 and the transfer roller 5. Then, the toner image on the photosensitive drum 1 surface side is sequentially transferred to the surface of the fed transfer material P.

The transfer material exiting the transfer nip is sequentially separated from the surface of the rotating photosensitive drum 1 and introduced into a heating and fixing device 6 as a heating device by a transport device 12 to undergo a heat fixing process of a toner image. The heat fixing device 6 will be described in detail in the following section (2).

The transfer material having exited from the heat fixing device 6 is printed out on a paper discharge tray 16 through a sheet path having a conveying roller 13, a guide 14, and a paper discharge roller 15.

After the transfer material is separated, the surface of the rotating photosensitive drum is cleaned by the cleaning device 7 to remove adhered contaminants such as untransferred toner, and is repeatedly used for image formation.

(2) Heat Fixing Device 6 FIG. 2 is a schematic structural model diagram of the heating fixing device 6 as the heating device used in this embodiment. The heat fixing device 6 of the present example is disclosed in JP-A-4-44075-44083 and JP-A-4-2049.
This is a heating device of a so-called tensionless type film heating system / pressing rotating body (pressing roller) driving system described in JP-A-80-204984 and the like.

Reference numeral 21 denotes a film guide member (stay) having a substantially semi-arc-shaped cross section and a trough shape having a length in a direction perpendicular to the paper surface. Reference numeral 22 denotes a substantially central portion of the lower surface of the film guide member 21 along the length. The horizontal heating element 23 accommodated and held in the formed groove is an endless belt-shaped (cylindrical) heat-resistant film loosely fitted to the film guide member 21 with the heating element. These 21 to 23 are heating means side members.

Reference numeral 24 denotes a heating element 22 with a film 23 interposed therebetween.
Is an elastic pressure roller as pressure means pressed against the lower surface of the roller. N is a pressing nip portion (fixing nip portion) formed between the heating member 22 and the heating member 22 by elastic deformation of the elastic layer 24b of the pressure roller 24 pressed against the heating member 22 with the film 23 interposed therebetween. The driving force of the driving source M is transmitted to the pressure roller 24 via a power transmission mechanism such as a gear (not shown), and is driven to rotate at a predetermined peripheral speed in a counterclockwise direction indicated by an arrow b.

The film guide member 21 is made of, for example, PP
It is a molded article of a heat resistant resin such as S (polyphenylene sulfide) resin or liquid crystal polymer.

The heating element 22 of this embodiment is made of
A thin plate-shaped heater substrate 22a, a linear or thin band-shaped conductive heating element (resistance heating element) 22b such as Ag / Pb formed along its length on the surface side (film sliding surface side),
Thin surface protection layer 22c such as a glass layer, heater substrate 22a
Is a ceramic heater having a low heat capacity as a whole, including a temperature detecting element 22d such as a thermistor disposed on the back side of the ceramic heater. The temperature of the ceramic heater 22 is quickly raised by supplying power to the energizing heating element 22b, and the temperature is adjusted to a predetermined fixing temperature by a power control system including a temperature detecting element 22d.

The heat-resistant film 23 has a total thickness of not more than 100 μm, preferably not more than 60 μm and not more than 20 μm in order to reduce the heat capacity and improve the quick start of the apparatus.
m, PTFE (polytetrafluoroethylene) resin / PFA with heat resistance, release property, strength, durability, etc.
Single-layer film of ((tetrafluoroethylene / perfluoroalkyl ether copolymer) resin / PPS (polyphenylene sulfide) resin, or polyimide
Coating PTFE, PFA, FEP (tetrafluoroethylene / hexafluoropropylene copolymer), etc. as a release layer on the surface of a base film such as polyamideimide, PEEK (polyetheretherketone) resin, PES (polyethersulfone) resin And the like.

The pressure roller 24 is of the present invention,
A core metal 24a of iron or aluminum, an elastic layer 24b made of a foamed elastic body, an adhesive layer (conductive layer) 24c provided with conductivity, and a release layer 24 made of a fluororesin tube.
d. The pressure roller 24 will be described in detail in the next section (3).

At least when the pressure roller 24 is driven to rotate at the time of image formation, the frictional force between the pressure roller 24 and the outer surface of the film 23 at the pressure contact nip N is increased by the rotation of the pressure roller 24. With film 2
3, the inner surface of the film slides in the press-contact nip portion N in close contact with the lower surface, which is the surface of the heating element 22, and the outer periphery of the film guide member 21 rotates in a predetermined direction in the clockwise direction indicated by an arrow a. The rotation is performed without wrinkles at a speed substantially equal to the peripheral speed of the transfer material P carrying the unfixed toner image T conveyed from the image transfer unit side. In this case, a lubricant such as heat-resistant grease may be interposed between the inner surface of the film 23 and the lower surface of the heating element on which the film 23 slides in order to reduce the sliding resistance.

When the film 23 is rotated by the rotation of the pressure roller 24, and the temperature of the heating body 22 is raised to a predetermined fixing temperature and the temperature is controlled, the pressure roller 24 of the pressure contact nip N and the film 23 are rotated. A transfer material P having a non-fixed toner image T as a material to be heated is introduced with the toner image carrying surface side of the film 23 side, adheres tightly to the outer surface of the film at the press-contact nip N, and The heat of the heating element 22 is applied through the film 23 while the press-contact nip N is being conveyed to the transfer material P, and the unfixed toner image T is transferred to the transfer material P by the pressure of the press-contact nip N. Heat and pressure fixed on the surface. The transfer material P that has passed through the pressure nip N is separated from the outer surface of the film 23 and transported.

The apparatus 6 of the film heating type as in this example 6
In this case, the heating element 22 having a small heat capacity and a rapid temperature rise can be used, and the time required for the heating element 22 to reach a predetermined temperature can be greatly reduced. Since the film heating type device 6 can easily start up to a high temperature even from room temperature,
There is no need to perform standby temperature control when the apparatus is in a standby state during non-printing, and power can be saved.

Further, since substantially no tension acts on the rotating film 23 except for the press-contact nip portion N, the moving force of the rotating film 23 along the length of the film guide member 21 is small. Therefore, it is sufficient to provide a flange member that simply receives the end of the film 23 as the film-side movement restricting means, and there is an advantage that the apparatus can be simplified.

(3) Pressure Roller 24 As described above, the pressure roller 24 serving as the pressure rotating body in the heat fixing device 6 is composed of a core metal 24a such as iron or aluminum and an elastic body made of an insulating foamed elastic body. A layer 24b;
It comprises a conductive layer 24c and a release layer 24d formed of an outermost insulating fluororesin tube. The conductive layer 24c of this example is
It has a function as an adhesive layer for bonding the elastic layer 24b and the release layer 24d. In the present invention, the conductive layer may not be the adhesive layer. In that case, the adhesive layer may be formed between the conductive layer and the elastic layer, and between the conductive layer and the release layer.

The elastic layer 24b is an insulator, and preferably has a volume resistance of 10 ¹⁰ Ω · cm or more. In the present invention, the elastic layer 24b does not need to be made conductive, and it is not necessary to disperse carbon or the like in the elastic layer 24b, so that good heat insulating properties can be obtained.

For the volume resistance value, a sheet made of an elastic layer was prepared, which was then measured with a high resistance meter, for example, Mitsubishi Chemical.
It is measured with Hiresta-UP MCP-HT450 manufactured by KK

The thermal conductivity of the elastic layer 24b of the pressure roller 24 is preferably 0.146 W / m · K or less. By setting the thermal conductivity in such a range, the amount of heat taken by the pressure roller 24 from the heating body 22 during the operation of the heat fixing device 6 can be reduced. For this reason, the temperature rise on the surface of the film 23 can be improved, and a quick start of the heat fixing device 6 is enabled.
When the thermal conductivity is lower than 0.048 W / m · K, the temperature rise speed of the pressure roller 24 is increased and the fixability is improved. And the heat resistance of the pressure roller is required.

The thermal conductivity of the elastic layer was measured using a surface thermal conductivity meter.
(Trade name: QTM-500, manufactured by Kyoto Electronics Co., Ltd.) and measured.

The elastic layer 24 used for the pressure roller 24
The thickness of b is not particularly limited as long as the pressure-contact nip portion N having a desired width can be formed.
It is preferred that

The elastic material used for the elastic layer 24b is not particularly limited, and a known material may be used.
V silicone rubber and millable LTV silicone rubber.

The foaming agent for making such an elastic body into a foamed elastic body is not particularly limited. For example, ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, nitroso compounds, azo compounds, sulfonyl hydrazides and the like can be mentioned.

The amount of the foaming agent may be determined as appropriate.
Usually, 3 to 5 parts by mass is used for 100 parts by mass of the elastic body.

The vulcanization system for crosslinking the elastic body is not particularly limited, but it is preferable to use a peroxide vulcanization system.

The vulcanizing agent in the case of the peroxide vulcanizing system is not particularly restricted but includes, for example, dicumyl peroxide,
Organic peroxides such as di-tert-butyl peroxide.

The amount of the vulcanizing agent may be appropriately determined,
Usually, 1 to 5 parts by mass is used for 100 parts by mass of the elastic body.

Usually, foaming and vulcanization are performed simultaneously, and usually, heating may be performed at 100 to 200 ° C. for about 0.5 to 2 hours.

Such an elastic layer may be formed by a known method. For example, elastic body and vulcanizing material (peroxide)
Extrusion molding and foaming agent, and heating and foaming, vulcanization and curing, or in a mold, elastic body and vulcanizing material (peroxide)
And a method of heating and foaming and vulcanizing and curing the mixture.

The foamed elastic body (sponge rubber) may have a closed-cell structure, an open-cell structure, or may contain both.

The elastic layer is preferably made of an insulating foamed elastic body and does not contain a filler or the like, but may contain a coloring agent or the like if necessary.

The release layer 24d is also an insulator, and preferably has a volume resistance of 10 ¹⁰ Ω · cm or more. In the present invention, the release layer 24d does not need to be made conductive, so that adhesion of dirt due to toner or the like can be prevented.

The ten-point average surface roughness (R) of the outermost release layer
z) is preferably 3 μm or less because sufficient smoothness can be obtained.

The insulating fluororesin tube used for the release layer 24d is not particularly limited as long as it does not contain a filler such as a reinforcing agent or a resistance control agent and can maintain the releasability of the fluororesin itself. What is necessary is just to use a thing, for example, PFA, PTFE, FEP, etc. are mentioned.

The thickness of the release layer 24d is not particularly limited as long as it can impart sufficient releasability to the pressure roller 24 and does not impair the thermal conductivity.
It is preferably 0 μm.

In the present invention, a fluororesin tube is coated and adhered to the elastic layer. The coating and bonding may be performed, for example, by applying an adhesive on the elastic layer, coating the fluororesin tube, and then vulcanizing and curing the adhesive.

The conductive layer 24c only needs to have conductivity, and the lower the volume resistance is, the more preferable.
If it is less than 0 ⁷ Ω · cm, the charging of the insulating fluororesin tube of the release layer can be sufficiently suppressed.

It is preferable that the conductive layer 24c be capable of adhering the elastic layer and the fluororesin. In this case, the unevenness of the foamed sponge rubber can be filled with the conductive adhesive 24c, so that the surface of the release layer 24b does not become uneven even at the press-contact nip portion N.

It should be noted that even if the conductive layer 24c cannot bond the elastic layer and the fluororesin, the elastic layer and the conductive layer,
The same effect can be obtained by providing an adhesive layer between the conductive layer and the release layer, and the surface of the release layer 24b can be made not uneven at the press-contact nip portion N.

The conductive adhesive used for the conductive layer 24c is not particularly limited, and a known adhesive may be used.
Examples include silicone rubber such as LTV and RTV.

As described above, the conductive layer may be formed by applying a conductive adhesive on the elastic layer, covering the fluororesin tube, and vulcanizing and curing the adhesive. Vulcanization may be performed by a known method, but is usually performed at 150 to 250 ° C. for 2 to 4 times.
The heating may be performed for about an hour. Further, vulcanization may be performed in two stages.

The conductive layer which does not bond the elastic layer and the fluororesin includes, for example, fluororubber as a rubber to which a conductive filler such as carbon black is added, and fluororesin as the resin.

In the case of a resin to which a conductive filler such as carbon black is added, examples of the resin include PFA, FEP, and PTFE.

Examples of the conductive filler include metal oxides such as ZnO in addition to carbon black.

The amount of the conductive filler is not particularly limited, but is preferably 5 to 10% by mass.

In the case of such a conductive layer, in the case of rubber, an insulating adhesive layer is applied on the elastic layer, a conductive rubber layer is applied thereon, and a PFA tube coated with a primer is coated on the inner surface. Is formed.

In the case of conductive resin, PF
When molding the A tube, the conductive tube and the insulating tube are molded in two colors. The two-color tube can be formed, for example, by covering an elastic layer coated with an insulating adhesive layer.

The thickness of the conductive layer 24c is not particularly limited, but may be in the range of 10 to 70 μm in view of the compatibility between the thermal conductivity point and the surface properties.
It is preferred that If the conductive layer is not an adhesive layer,
The thickness of the conductive layer is preferably 10 μm or more, and an arbitrary thickness in a form suitable for workability may be selected.

When the conductive layer 24c cannot bond the elastic layer and the fluororesin, an adhesive layer is usually provided between the elastic layer and the conductive layer.

The adhesive used for the adhesive layer is not particularly limited, and any known adhesive may be used, and examples thereof include silicone rubber such as LTV and RTV.

The adhesive layer may be formed by applying an adhesive on the elastic layer, coating a fluorine resin tube having a conductive layer formed on the inside in advance, and vulcanizing and curing the adhesive. Vulcanization may be performed by a known method, usually 150 to 2
What is necessary is just to heat at 50 degreeC for about 2 to 4 hours. Further, vulcanization may be performed in two stages.

The core metal is not particularly limited, but is made of, for example, a metal or alloy such as aluminum, copper alloy or stainless steel, iron plated with chromium or nickel, or a synthetic resin. In addition, the cored bar generally has a cylindrical shaft, but may have a columnar shape. The diameter may be appropriately determined, but is usually 4 mm or more and 30 mm or less.

The hardness of the pressure roller of the present invention (ASKER-
C hardness meter, load 6N (600g)) is preferably 35 to 60 ° in order to secure a nip of 5 to 10 mm with a load of 0.5 to 3 N at a total pressure.

(4) Another Embodiment of the Present Invention FIG. 3 is a schematic sectional view showing the structure of another pressure roller. The conductive adhesive layer 100 between the foamed elastic layer 24a of the pressure roller 24 and the insulating fluororesin tube 24d is made of a conductive adhesive 100 including a micro balloon 101 in a silicone adhesive. Other parts are shown in Fig. 2.
Is the same as

FIGS. 4A to 4D show examples of the configuration of a film heating type heating device (heating fixing device).

FIG. 4A shows an endless belt between three substantially parallel members of a heating body 22 held by a heating body holder / film guide member 25, a film driving roller 26, and a tension roller 27. A heat-resistant film 23 is stretched and stretched, and the heating element 22 is sandwiched between the films 23.
And a pressure roller 24 to form a pressure contact nip N, and the film 23 is driven to rotate by a drive roller 26. The pressure roller 24 rotates following the rotation of the film 23. Reference numeral 27 denotes a drive source of the film drive roller 26.
A transfer material P as a material to be heated is introduced into the pressure nip N to heat and fix the toner image.

FIG. 4B shows a heat-resistant film in the form of an endless belt between a heating element 22 held by a heating element holder / film guide member 25 and a film drive roller 26 which are substantially parallel to each other. 23, the film 23 is heated and pressed against the pressure roller 24 to form a pressure contact nip N.
6 is driven to rotate. The pressure roller 24 rotates following the rotation of the film 23.

In FIG. 9C, a rolled long end film is used as the heat-resistant film 23, which is fed from a pay-out shaft 28 to the heating holder / film guide member 2.
5, the heating body 22 and the pressure roller 24 are pressed against each other through the winding shaft 29 through the lower surface of the heating body 22 held by the heating member 22 to form a pressure contact nip portion N. Is wound up by the winding shaft 29 and travels at a predetermined speed.

In the device having the above configuration,
If the pressure roller 24 as the pressure means is of the present invention, the same operation and effect as described above can be obtained.

The heating element 22 on the side of the heating means is not limited to the above-described ceramic heater, and other heating elements such as an electromagnetic (magnetic) induction heating method can be appropriately adopted.

FIG. 9D shows an example of the electromagnetic induction heating system. Reference numeral 30 denotes a magnetic metal member that generates electromagnetic induction heat, and 31 denotes a magnetic metal member 30 that generates electromagnetic induction heat as a heater due to a high-frequency magnetic field generated by energizing an exciting coil 31 serving as a magnetic field generating means. Through the film 23, the transfer material P is applied to the transfer material P as a material to be heated, which is introduced into the press nip N. Film 2
The member 3 itself may be made of an electromagnetic induction heating member.

FIGS. 5A and 5B show examples of the configuration of a heating device (heating fixing device) of a heat roller type.

In FIG. 5A, reference numeral 32 denotes a heating roller (fixing roller) as a heating means, which is a hollow metal roller made of iron, aluminum or the like having a release layer made of a fluororesin or the like on the outer peripheral surface. Halogen heater 33 as heat source
Is built in. This is brought into pressure contact with the heating roller 24 to form a pressure contact nip portion (not shown). A transfer material P as a material to be heated is introduced into the press-contact nip portion to heat and fix the toner image.

In FIG. 5B, the heating roller 32 is heated by an electromagnetic induction heating method. Heating roller 3
2 is made of a ferromagnetic material. Heating is performed by applying a high-frequency AC current to an exciting coil 35 wound around an exciting core 34 to generate a magnetic field, and to generate an eddy current in the heating roller 32.
In other words, the heating roller eddy current is generated by the magnetic flux, and the heating roller 32 itself generates heat by the Joule heat. Reference numeral 36 denotes an auxiliary core disposed to face the excitation core 34 with a heating roller therebetween to form a closed magnetic path.

In the above-described heating apparatus of the heat roller type, if the pressing roller 24 as the pressing means is of the present invention, the same operation and effect as described above can be obtained.

The present invention is effective for a heating device for introducing a material to be heated into a press-contact nip portion between a heating means and a pressurizing means, nipping and transporting the same, and performing a heat treatment. Not only as a heating and fixing device, but also, for example, a device for modifying a surface property (such as gloss) by heating a recording material carrying an image, a device for temporarily attaching, a sheet-like material to be fed and dried. -Can be widely used as a heating device such as a device for laminating.

[0099]

<Example 1> An aluminum material having a diameter of 13 was used for a metal core 24a, and a foamed elastic material layer 2 was formed outside the metal core 24a.
4b was formed as follows.

100 parts by weight of a high-temperature-curable silicone rubber (HCR) (trade name: KE520U, Shin-Etsu Chemical Co., Ltd.), and 3 parts of peroxide vulcanizing agent (trade name: C-2, Shin-Etsu Chemical Co., Ltd.) Parts by weight, foaming agent (trade name: KEP-13, manufactured by Shin-Etsu Chemical Co., Ltd.)
Was used in an amount of 3 parts by weight. Then, this mixture was co-extruded into a cored bar, foamed and vulcanized and cured in the batch furnace for 1 hour at about 180 ° C. in the batch furnace.

The foamed elastic material layer 24 thus formed
b has a volume resistivity of 10 ¹⁴ Ω · cm and a thermal conductivity of 0.0
97 W / m · K.

Next, the elastic layer 24b was polished to a thickness of 3 mm.

On the polished foamed elastic layer 24b,
Conductive silicone adhesive (trade name: XE-B6367,
(Manufactured by Toshiba Silicone Co., Ltd.) was applied over the entire area of the roller, and allowed to stand for several hours in order to apply.

Then, a 30 μm-thick PFA tube (product name: 450HPJ, manufactured by Gunze Co.) was coated with an insulating material.
After vulcanizing and curing the silicone adhesive at 170 ° C. × 2 hours, secondary vulcanization was performed at 200 ° C. × 4 hours.

The volume resistance of this PFA tube (release layer) was 10 ¹⁷ Ω · cm.

The thickness of the conductive layer (conductive adhesive layer) obtained by curing the conductive silicone adhesive was 50 μm, and the volume resistance was 10 ⁴ Ω · cm.

The elastic roller produced in this manner was used as the pressure roller 24 of the above-described film heating type heat fixing device 6 shown in FIG. Roller hardness is about 44 ° (ASKE
The RC hardness tester had a load of 6 N (600 g).

As the film 23 of the heat fixing device 6, a polyimide seamless tube having a thickness of 50 μm is used.
A PTFE layer having a thickness of 0 μm was used.

Further, a total pressure of 120 N is applied to the entire nip.
(12Kg) pressure. The nip width at this time was about 6.5 mm.

A power of 500 W is supplied to the heating element 22.
The process speed was 96 mm / sec. And
The time required for the heater temperature to reach 190 ° C., the fixability after the transfer material P is passed after 5 seconds, the generation of an offset image when 100 sheets of continuous halftone are passed, and the pressure roller Of the toner was evaluated.

The fixing property was determined by Lap, which is LBP manufactured by Canon Inc.
5 as an unfixed image with ser Shot LBP-350
The solid black image of mm square was printed on Fox River 24 lb paper, and after passing through the heat fixing device 6 under the above conditions, the solid black image was printed with a nonwoven fabric at 10 N / m ² (10 g / c).
The density before and after rubbing with a pressure of m ² ) is measured by a reflection type Macbeth reflection densitometer (RD914: DIVISION OF K).
OLLMORGEN INSTRUMENT CO. ) Was evaluated. Table 1 shows the evaluation results. Each symbol in the fixing property, occurrence of offset, and roller contamination in Table 1 indicates the following evaluation.

(Fixability) ○: good ×: bad (offset) ：: no occurrence ×: occurrence (roller dirt) ○: no dirt ×: dirt <Example 2> Core metal 24a as in Example 1 A foamed elastic layer 24b was formed on the outside of the substrate and polished.

On this polished foamed elastic layer 24b,
An insulating silicone adhesive (trade name: CY52-238, manufactured by Toray Dow Corning Silicone Co., Ltd.) was applied over the entire area of the roller, and allowed to stand for several hours to spread.

Thereafter, a two-layer PF having a total thickness of 50 μm was used.
After covering the A tube and vulcanizing and curing the silicone adhesive at 170 ° C. for 2 hours, secondary vulcanization was performed at 200 ° C. for 4 hours. The layer structure of the two-layered PFA tube used was that the lower layer 25 μm was made conductive by dispersing carbon black in the PFA tube, and the upper layer 2
5μm is insulated PFA tube (Product name: 450HPJ,
Gunze). This tube forming method is formed by co-extrusion. The lower layer was added in an amount of 10% by mass of carbon black. The upper layer of the PFA tube is a release layer, and the lower layer is a conductive layer.

The volume resistance of the release layer was 10 ¹⁸ Ω · cm. The volume resistance of the conductive layer was approximately 10 ⁴ Ω · cm.

The elastic roller manufactured in this manner is used as the pressure roller 24 of the above-described heat fixing device 6 of the film heating system shown in FIG. The fixability of the image to the roller, the presence or absence of occurrence of a fixing offset, and the contamination of the roller with toner were evaluated. Table 1 shows the evaluation results. Roller hardness is about 48 °
(ASKER-C hardness tester, load 6N (600 g)).

<Comparative Example 1> In Example 1, the elastic layer was formed of solid silicone rubber having a thickness of 3 mm (trade name: DY3
5-561A / B, manufactured by Toray Dow Corning Silicone Co., Ltd.), and the release layer is a 30 μm-thick fluororubber latex layer (trade name: GLS213, manufactured by Daikin)
And After forming the elastic layer, the adhesive layer was applied and dried, and a release layer was coated thereon and heated and cured at about 300 ° C. for 40 minutes to prepare a roller. Using this as a pressure roller, the rise time of the heating device, the fixability of the image to the transfer material P, the presence or absence of a fixing offset, and the contamination of the roller with toner were evaluated. Table 1 shows the evaluation results. At this time, an adhesive (trade name: GLP104, manufactured by Daikin) was used to bond the elastic layer and the release layer.

Comparative Example 2 In Example 1, the elastic layer was a foamed elastic layer formed by foaming a 3 mm-thick silicone rubber (trade name: KE904FU, manufactured by Shin-Etsu Chemical Co., Ltd.). The release layer was a layer composed of a 30 μm-thick PFA tube (trade name: 450HPJ, manufactured by Gunze), and a thin insulating primer (trade name: CY52-) was formed on the inner surface of the PFA tube without providing a conductive adhesive layer. 238, manufactured by Toray Dow Corning Silicone Co., Ltd.) was applied in a thickness of 4 μm and adhered to the foamed elastic layer, except that an elastic roller was produced in the same manner as in Example 1 and heated using a pressure roller. The rise time of the apparatus, the fixability of the image to the transfer material P, the presence or absence of a fixing offset, and the contamination of the roller with toner were evaluated. Table 1 shows the evaluation results.

Comparative Example 3 In Example 1, the elastic layer was a foamed elastic layer formed by foaming 3 mm thick silicone rubber (trade name: KE904FU, manufactured by Shin-Etsu Chemical Co., Ltd.). The release layer is a layer composed of a 30 μm-thick PFA tube (trade name: 450HPJ, manufactured by Gunze), and an insulating silicone adhesive (trade name: CY) is placed on the foamed elastic layer.
53-228, manufactured by Toray Dow Corning Silicone Co., Ltd.)
Was applied in a thickness of 50 μm to adhere the PFA tube and the foamed elastic layer, and an elastic roller was produced in the same manner as in Example 1, and this was used as a pressure roller to increase the rise time of the heating device and Then, the fixability of the image to the transfer material P, the presence or absence of occurrence of a fixing offset, and the contamination of the roller with toner were evaluated. Table 1 shows the evaluation results.

[0120]

[Table 1]

From Table 1, it can be seen that in Examples 1 and 2 of the present invention, as compared with Comparative Example 1, the elastic heater layer 24b is formed of a foamed elastic material layer, so that the fixing heater 22 rises faster and can be completed in a shorter time. It can be seen that good fixability can be obtained even when the transfer paper comes to the fixing nip. This is considered to be because the thermal conductivity is reduced by using the foamed elastic material layer, and the amount of heat taken by the pressure roller when the heater is started is reduced, so that the time required for fixing with a constant power is shortened. .

Further, the first and second embodiments of the present invention are similar to the second comparative example.
As compared with, the fixing property is almost the same, but the offset property and the roller contamination are remarkably good. In the roller of Comparative Example 2, the surface of the PFA tube is
In addition to offsetting due to the loss of adhesion of the toner to the transfer paper due to charging to V, the PFA tube becomes the foam cell diameter at the time of pressurization. Entering and accumulating dirt.
In contrast, the rollers of Examples 1 and 2 provided with the conductive layer reduced the charging potential of the surface of the PFA tube to −hundreds of volts due to frictional charging. It is kept and there is no offset, and since the cells of the foamed elastic layer are filled with a thick silicone adhesive, the roller surface layer cannot be uneven at the nip even during pressurization. However, the roller is not contaminated with toner.

In Comparative Example 3, the roller surface is not uneven at the nip portion and the roller is not easily stained. However, since the surface of the PFA tube is charged to −10 kV by frictional charging, the toner is applied to the transfer paper. Loss of strength and offset.

Examples 1 and 2 of the present invention are much better overall than Comparative Examples 1 to 3.

[0125]

As described above, the pressure roller of the present invention
Low thermal conductivity, excellent surface properties during nip, and hardly charge up the surface. The heating device of the present invention provided with such a pressure roller can efficiently use the heat from the heating means, provide less contamination of the roller with toner, and provide a good image with less image disturbance. can do.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus of the present invention.

FIG. 2 is a schematic structural diagram of the heat fixing device of FIG. 1;

FIG. 3 is a schematic diagram of another example of a pressure roller according to the present invention.

FIGS. 4A to 4D are schematic views of another example of the configuration of the film heating type heat fixing device of the present invention.

FIGS. 5A and 5B are schematic diagrams of examples of configurations of heat and the roller-type heat fixing of the present invention, respectively.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image carrier (photosensitive drum) 2 Charging roller 3 Drum 4 Developing device 5 Transfer roller 6 Heat fixing device 7 Cleaning device 8 Feed roller 9 Feed cassette 10 Guide 11 Registration roller 12 Transport device 13 Transport roller 14 Guide 15 Discharge Roller 16 Discharge tray 21 Film guide member 22 Heating element (ceramic heater) 22a Heater substrate 22b Electric heating element (resistance heating element) 22c Surface protection layer 22d Temperature sensor 23 Heat resistant film 24 Pressure roller 24a Core 24b Elastic layer 24c Conductive layer (adhesive layer) 24d Release layer 25 Heater holder / film guide member 26 Film drive roller 27 Tension roller 28 Feeding shaft 29 Winding shaft 30 Magnetic metal member that generates electromagnetic induction heat 31 Exciting coil 32 Heat roller (fixing) Laura) 33 c Genhita 34 exciting iron core 35 excitation coil 36 auxiliary core 100 conductive silicone adhesive layer 101 resin microballoons T toner P transfer material N press nip M drive source

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Hikaru Nagata 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Masato Yoshioka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon In-house F term (reference) 2H033 AA01 AA09 AA30 AA32 BA25 BB18 BB29 BB30 BB33 BE03 BE06 3J103 AA02 AA15 BA02 BA41 EA06 FA01 FA07 GA02 GA52 GA57 GA58 HA03 HA04 HA12 HA20 HA43 HA53 HA60 3K058 AA73 BA18 DA01 3

Claims (8)

[Claims] 1. A pressure roller having an elastic layer around a cored bar and a release layer as an outermost layer, wherein the elastic layer is a foamed elastic body (sponge rubber), A pressure roller, wherein the layer is a fluororesin tube, and has at least a conductive layer between the elastic layer and the release layer. 2. The pressure roller according to claim 1, wherein the conductive layer is a silicone adhesive layer. 3. The conductive layer has a volume resistivity of 10 ⁷ Ω · cm.
The pressure roller according to claim 1, wherein: 4. The elastic body layer has a volume resistance of 10 ¹⁰ Ω ·
The pressure roller according to any one of claims 1 to 3, wherein the pressure roller is not less than cm. 5. The volume resistance value of the release layer is 10 ¹⁰ Ω · cm.
The pressure roller according to any one of claims 1 to 4, which is as described above. 6. The thermal conductivity of the elastic layer is 0.146 W.
The pressure roller according to any one of claims 1 to 5, wherein the pressure roller is equal to or less than / m · K. 7. A heating means for heating a sheet-like material to be heated, and a pressure roller disposed opposite to the heating means and pressed against the heating means, wherein the heating means and the pressure roller 7. A heating device for heating a material to be heated by introducing the material to be heated into a press-contact nip portion formed by the method described above, and nipping and transporting the material. A heating device comprising a pressure roller. 8. An image forming apparatus comprising: means for forming and carrying an unfixed image on a recording material; and a heat fixing device for heating and fixing the unfixed image to the recording material, wherein the heat fixing device is provided. An image forming apparatus, which is the heating apparatus according to claim 7.