JPH07295411A - Image heating film and manufacture thereof, and image heating device - Google Patents

Abstract

PURPOSE:To enable an adequate image heating to be carried out so that its heat loss is prevented, and also its heating can be stabilized, and its mold release property is improved by providing a low thermal conductive resin layer on one surface of a metal film and a mold release property resin layer on the other surface. CONSTITUTION:The film for image heating is provided with a low thermal conductive resin layer 2b on one surface of a metal film 1 and a mold release property resin layer 2a on the other surface. The surface of the metal film 1 is covered with resin by means of dipping or spray coating. The metal film 1 close to a paper-leaf body is made to generate heat directly and easily conductive to the paper-leaf body via a thin mold release property resin layer 2a, and thermally insulated so that the generated heat does not come to the film inner side. Since the resin layers 2a and 2b on the inner surface of a fixing film smoothen film movement, the friction between the film and the guide member can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image heating apparatus for generating eddy currents by utilizing electromagnetic induction to heat them, and more particularly to an unfixed image heating apparatus used in an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus. The present invention relates to an image heating film used in an image heating device suitable for a fixing device for fixing an image, and a manufacturing method thereof.

[0002]

2. Description of the Related Art As an image heating apparatus represented by a heat fixing apparatus, a contact heating method such as a heat roller method or a film heating method has been widely used.

In such an apparatus, a toner image is heated through a roller or a film by passing an electric current through a halogen lamp and a heating resistor to generate heat.

Japanese Patent Publication No. 5-9027 proposes that eddy current is generated in the fixing roller by magnetic flux and heat is generated by Joule heat.

By utilizing the generation of the eddy current as described above, the heat generation position can be brought closer to the toner, and the efficiency of energy consumption can be improved as compared with the heat roller using the halogen lamp.

[0006]

However, according to this method, since a fixing roller having a large heat capacity is heated, even a highly efficient fixing roller cannot be used for quick start. In Japanese Patent Publication No. 5-9027, when an eddy current is generated in a cylindrical body to generate Joule heat,
If the temperature of the exciting coil and the exciting iron core rises and the amount of magnetic flux decreases, heat generation becomes unstable, and if the temperature rises too much, there is a problem that the exciting coil deteriorates. The heat efficiency was not sufficient due to the heat radiation of.

Further, Japanese Patent Publication No. 5-9027 does not describe any measures against toner offset.

[0008]

In order to solve the above problems, the image heating film of the present invention has a low thermal conductive resin layer on one surface of the metal film and a releasable resin layer on the other surface. It is a feature.

The method for producing an image heating film of the present invention is characterized in that the surface of the metal film is coated with a resin by dipping or spray coating.

Furthermore, the image heating apparatus of the present invention uses an image heating film provided with a metal film, an exciting coil provided on one side of the image heating film, and a magnetic flux generated by the exciting coil. In the image heating device for heating the image heating film and heating the unfixed toner image carried on the recording material by the heat of the image heating film, the image heating film is the exciting coil of the metal film. It is characterized by having a low thermal conductive resin layer on the side surface and a releasable resin layer on the other surface.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 8 shows a cross section of an electrophotographic printer using the present invention.

Reference numeral 3 denotes a photoconductor drum formed of an organic photoconductor or an amorphous silicon photoconductor, 4 is a charging roller for uniformly charging the photoconductor drum 3, and 8 is an image signal generator (not shown). Is a laser optical box for converting the signal of (1) into on / off of laser light to form an electrostatic latent image on the photosensitive drum 3. Reference numeral 6 is a laser beam, and 7 is a mirror.
The electrostatic latent image on the photosensitive drum 3 is visualized by selectively adhering toner by the developing device 5. On the other hand, a paper sheet (not shown), which is a recording material sent from the paper feed cassette 11 by the paper feed roller 10, is transferred to the transfer roller 9 and the photoconductor drum 3 so as to be synchronized with the electrostatic latent image on the photoconductor drum 3. Sent between and. The transfer roller 9 transfers the toner image on the photosensitive drum 3 onto the paper sheet by supplying an electric charge having a polarity opposite to that of the toner from the back surface of the paper sheet. In this way, the paper sheet on which the unfixed toner image is placed is subjected to heat and pressure by the fixing device 13 which is an image heating device, is permanently fixed on the paper sheet, and is discharged to the paper discharge tray. . Cleaner 1 for toner and paper dust remaining on the photoconductor drum.
The photoconductor drum is repeatedly removed by the process after charging.

Next, the fixing device of this embodiment will be described with reference to FIG.

FIG. 6 is a sectional view of the fixing device.

The fixing film 15, which is a cylindrical image heating film, rotates in the direction of the arrow, and the film guide 16 serves to pressurize the nip portion and stabilize the transport of the film.

Further, the film guide 16 also has a function of supporting the high magnetic permeability core 17 and the coil 18. The high magnetic permeability core 17 is made of a material such as ferrite or permalloy that is used for the core of a transformer, and more preferably 1
It is preferable to use ferrite, which has little loss even at 00 kHz or more.

An exciting circuit 19 is connected to the coil 18, and this circuit (not shown) has a frequency of 20 kHz to 500 kHz.
The high frequency z is generated by the switching power supply.

Reference numeral 20 denotes a pressure roller for pressing the film guide 16 via the fixing film 15, and a paper sheet 21 having unfixed toner 22 placed on the nip N formed by the pressure roller 20 and the fixing film 15. Heat fixing is carried out by passing it through.

Next, the principle of heating the fixing device will be described with reference to FIG.
The magnetic flux generated by the current applied to the exciting coil by the exciting circuit 19 is guided to the high permeability core 17 to generate the magnetic flux 23 and the eddy current 24 in the metal film layer 1 of the fixing film 15 in the nip N. The eddy current 24 and the specific resistance of the metal film 1 generate heat. This heat causes paper leaf 2
The toner is melted and then cooled to form a permanently fixed image.

With such a constitution, the fixing film used in this embodiment has the sectional constitution shown in FIG.

Reference numeral 1 denotes a metal film which is a base layer of the fixing film 15, and it is preferable to use a ferromagnetic metal such as nickel, iron or stainless steel.

Reference numeral 2a is a resin layer having good releasability and heat resistance, such as silicone resin, fluororesin, silicone rubber, or fluororubber, which is provided on the surface of the film.

Reference numeral 2b is a resin layer having good heat resistance such as a fluororesin, a polyimide resin, a polyamide resin, a PPS resin, a PEEK resin, a liquid crystal polymer and a phenol resin.

On the metal film 1 of the fixing film 15,
A non-magnetic metal may be used, but more preferably a metal such as nickel, iron, magnetic stainless steel, or the like, which has good absorption of magnetic flux. The thickness is thicker than the skin depth expressed by the following formula and is 200
It is preferable that the thickness is less than μm.

The skin depth σ (m) is the frequency f of the exciting circuit.
(Hz), permeability μ and specific resistance ρ (Ωm)

[0027]

[Outer 1] Is expressed as

This shows the depth of absorption of electromagnetic waves used for electromagnetic induction. At deeper points, the intensity of electromagnetic waves is 1 / e or less, and conversely, most energy reaches this depth. Is absorbed in.

If the thickness exceeds 200 μm, the hardness of the metal becomes conspicuous and it becomes difficult to drive the film. In addition, the heat capacity also becomes large, and it becomes impossible to rapidly raise the temperature from room temperature to enable fixing in a few seconds.

As the resin layer 2a, one having a good releasability of 5 μm or more and 25 μm or less is used.

If the thickness is 25 μm or more, the heat conduction is deteriorated, the strength of the coating film is lowered, and it is not advantageous in spite of the problems that it cannot be made in a single process and a large amount of material is required. On the other hand, when the thickness is 5 μm or less, problems such as formation of a part having poor releasability due to unevenness of the coating film and insufficient durability occur.

The resin layer 2b preferably has a low thermal conductivity of 10 μm or more and 1 mm or less. If it is less than 10 μm, the heat insulating effect cannot be obtained, and the durability is insufficient. When it exceeds 1 mm, it goes away from the high magnetic permeability core 17 and the magnetic flux is not sufficiently absorbed by the metal film layer 1. Since the heat insulating property affects the thickness of the resin, it is possible to use the same resin on both the inside and outside of the metal film by changing the thickness.

As described above, in this embodiment, the metal film 1 close to the paper sheet is directly heated and the thin releasable resin layer 2 is used.
It is intended to facilitate transfer to the paper sheet via a and to insulate the generated heat so as not to go to the inside of the film.

As a result, in this embodiment, the resin layer on the inner surface of the fixing film makes the movement of the film smooth,
Friction of the film with the guide member can be reduced.

Further, in this embodiment, heat can be prevented from being transferred from the inner surface of the film to the coil for generating the alternating magnetic field, and the decrease of magnetic flux and the deterioration of the coil due to the temperature rise can be prevented.

Further, in the present embodiment, the heat-resistant resin layer on the outer surface of the metal film can provide releasability from the toner and prevent offset of the toner.

On the other hand, in terms of efficiency, in this embodiment, since the metal film itself generates heat, there is no energy conversion loss or heat conduction loss, and the generated heat is directed toward the outer surface due to the thermal gradient. Most of the heat generated and generated flows to the paper sheet, which is efficient.

Next, a method of manufacturing the fixing film will be described.

The fixing film used in the above-mentioned examples is manufactured as follows.

FIG. 4 illustrates the steps for forming the resin layer on the metal.

The metal film 1 is made by an electroforming method or a rolling method. Since oil and dust are usually attached to the surface of the metal film 1, first, cleaning (28) is performed. Then, in order to obtain the adhesive strength between the heat resistant resin 2 and the metal film 1, an adhesive layer of polyamide imide or PPS, which is usually called primer treatment (29), is applied. This is dried (30)
Then, a heat resistant resin such as a fluororesin or a silicone resin is applied (31). After drying (32) to remove the solvent, baking (33) is performed at a temperature at which the heat-resistant resin is not crosslinked or melted to form a coating film, which is gradually cooled (34) and taken out.

Next, the coating of resin will be described.

FIG. 2 shows a method used when the inner surface and the outer surface of the metal film 1 can be coated with the same heat-resistant resin. Both the primer treatment and the coating of the heat-resistant paint are carried out by dipping the solution layer.

By using this method, the resin layer can be easily formed without the need for masking.

In FIG. 3, the same paint is applied simultaneously using the spray guns 25a and 25b. Also in this case, the resin layer can be easily formed without the need for masking.

In the case of a material having good heat resistance, rubbing resistance and releasability such as fluororesin, it is possible to form the inner surface and the outer surface with the same material by changing the thickness of the inner surface and the outer surface. Becomes

On the contrary, FIG. 5 shows a method of forming the inner surface and the outer surface with different resins. In FIG. 5A, a plurality of metal films 1 are passed through the support rods 26, and the spray gun 25 is reciprocated as shown by the arrow without masking for coating. This makes it possible to form a heat-resistant resin layer having good releasability on the outer surface. On the other hand, in FIG. 5B, a resin having good slidability and poor thermal conductivity is applied to the inner surface by using a spray gun 25. Thus, by using different resins for the inner surface and the outer surface, the material most suitable for the purpose can be used, and it has become possible to extend the life of the fixing device and improve the thermal efficiency. For example, fluororesin, silicone resin, etc. with good releasability are used for the outer surface, and polyimide, polyamide imide, etc. for the inner surface are high heat resistant and high strength, poor thermal conductivity, and a resin that can be formed smoothly Good to use.

As described above, in this embodiment, the surface of the metal film is coated with the heat resistant resin by dipping or spray coating. However, since the film does not have a flange portion or a squeezing portion at both ends like a roller, It is possible to paint without masking, or it is possible to line up the films and paint without masking. In particular, when the same resin can be used on both the inner and outer surfaces, it is possible to coat at the same time, so there is no need for masking and the coating time can be shortened.

The method shown in FIGS. 3 and 5 can be used not only for heat resistant resin coating but also for primer treatment. In addition, the primer treatment was to apply an adhesive, but it is also possible to obtain adhesive strength with the metal surface by the anchoring effect of the heat-resistant resin itself without roughening the metal surface by etching and using the adhesive. is there.

The method of applying the heat-resistant resin is not limited to the dip method and the spray method, and any similar method can be applied to the present invention.

FIG. 9, FIG. 10 and FIG. 11 show another embodiment of the present invention. FIG. 11 shows a state in which the fixing film of this embodiment is incorporated in a fixing device. Both ends of the fixing film are brought into contact with the rotation regulating plates 37 during movement, whereby the deviation of the fixing film is regulated. Therefore, in the fixing film of this embodiment, resin is applied to both end surfaces of the fixing film 15 to form the ribs 35, as shown in FIG.
The end surface of the film 15 is reinforced, and when the end surface of the film 15 rubs against the rotation restricting means, it rubs against the restricting plate to abrade the restricting plate and contaminate the inside of the machine or the image with abrasion powder or the film. It is prevented that the rubbing force on 15 is increased and damage is caused. The ribs 35 may be coated with resin only on the ends by the dipping method shown in FIG. Alternatively, as shown in FIG. 10, a ring made of a resin having good slidability and having a groove 36 may be attached in advance by adhesion.

In the above description, the endless cylindrical film is used, but a roll-up type film can also be used.

[0053]

As described above, according to the present invention,
Heat loss can be prevented, heat generation can be stabilized, and releasability can be improved, so that good image heating can be performed.

Further, according to the present invention, the image heating member coated with the resin can be obtained very easily.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a fixing film used in the present invention.

FIG. 2 is a diagram showing a dip coating process of a fixing film used in the present invention.

FIG. 3 is a diagram showing a spray coating process of a fixing film according to the present invention.

FIG. 4 is a flowchart for manufacturing a fixing film according to the present invention.

FIG. 5 is a diagram showing another coating process of the fixing film according to the present invention.

FIG. 6 is a sectional view of a fixing device using a fixing film according to the present invention.

FIG. 7 is a diagram showing a heat generation mechanism of the fixing device according to the present invention.

FIG. 8 is a sectional view of an electrophotographic printer using a fixing device according to the present invention.

FIG. 9 is a structural diagram of another fixing film according to the present invention.

FIG. 10 is a view showing still another fixing film according to the present invention.

FIG. 11 is a perspective view of a fixing device using another fixing film according to the present invention.

[Explanation of reference numerals] 1 metal film 2, 2a, 2b heat resistant resin layer 15 fixing film 16 film guide 17 high magnetic permeability core 18 coil 19 exciting circuit 20 pressure roller 21 paper leaf 22 toner 23 solution tank 24 heat resistant resin solution 25 Spray gun

Claims (7)

[Claims] 1. An image heating film comprising a metal film having a low thermal conductivity resin layer on one surface and a releasing resin layer on the other surface. 2. The image heating film according to claim 1, wherein the fixing metal film has a cylindrical shape. 3. The image heating film according to claim 1, wherein the image heating film has a reinforcing resin at an end thereof. 4. A method for producing an image heating film, which comprises coating the surface of a metal film with a resin by dipping or spray coating. 5. The method for manufacturing an image heating film according to claim 4, wherein the resin coating is performed on both surfaces of the metal film. 6. The metal film is subjected to a primer treatment before coating with the resin.
Of the method for producing a film for image heating of. 7. An image heating film having a metal film, an exciting coil provided on one surface side of the image heating film, and a magnetic flux generated by the exciting coil to heat the image heating film. In the image heating device for heating the unfixed toner image carried on the recording material by the heat of the image heating film, the image heating film has a low thermal conductive resin on a surface of the metal film on the side of the exciting coil. An image heating apparatus comprising a layer and a releasable resin layer on the other surface.