JPH07210019A - Fixing method - Google Patents

Abstract

PURPOSE:To prevent an offset phenomenon from occurring without using oil coating by imparting heat energy to an unfixed image on a recording material by the heat generation part of a film and cooling the recording material and the film by a cooling part in a state where they are not separated. CONSTITUTION:By a modulation magnetic field generated from a modulation magnetic field generation means 16, an eddy current is generated in an electrical conductive layer 33. Then, heat is generated from the layer 33 by Joule heat by the eddy current. The generated heat is transmitted to the recording material 24 and the unfixed toner image through a mold-released layer 35 and the unfixed toner image is fixed on the recording material 24 by receiving the heat and pressure at a nip part. The toner image softened because the heat is added at the nip part is closely brought into contact with the film 7 and carried toward a downstream side. Then, they are cooled by a cooling means 8 and the temperature of toner on the recording material 24 is lowered. Besides, the toner is solidified and hardened again. Then, the attaching force thereof with respect to the film 7 is weakened and the film 7 and the recording material 24 are separated at the position of a roller 19. Then, the toner on the recording material 24 is prevented from being offset to the film 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing method for an image forming apparatus such as a copying machine, a laser beam printer, a facsimile, a microfilm reader printer, and a recording machine.

More specifically, a recording material (electrofax sheet, electrostatic recording sheet, transfer sheet) is formed by using a toner made of a heat-meltable resin or the like by an appropriate image forming process means such as electrophotography, electrostatic recording, porcelain recording and the like. The unfixed toner image corresponding to the target image information is formed and carried on the surface of the material sheet, printing paper, etc. by the direct method or the indirect (transfer) method, and the unfixed toner image is carried by the image. The present invention relates to a fixing method for an image forming apparatus in which a heat fixing process is performed as a permanently fixed image on a recording material surface.

The present invention particularly relates to a fixing method for a color image forming apparatus.

[0004]

2. Description of the Related Art An example of a conventional fixing device for a color image forming apparatus is shown in FIG.

111 is a core metal, 112 is an elastic layer, 113 is a fixing roller, 113 'is a pressure roller, 114 is a heater,
115 is an oil applying device, 116 is a cleaning means,
117 is a temperature detector, 118 is a separation claw, 119 is a recording material, 120 is a developer (toner), and 121 is an inlet guide.

The unfixed developer transferred onto the recording material receives heat energy and pressure when it is nipped and conveyed by the fixing roller and the pressure roller, and is fixed on the recording material.

Oil (silicon oil or the like) is applied to the roller by the oil applying device, and the roller is cleaned by the cleaning means such as offset toner.

However, the above conventional example has the following drawbacks.

(1) In the conventional fixing device, oil must be applied to the roller in order to prevent the offset phenomenon. In particular, in the case of melting and mixing a plurality of colors of developer, the heat and pressure applied to the developer in the fixing device must be sufficiently high, which inevitably causes an offset phenomenon and avoids oil application to the roller. I couldn't do it.

When an OHP sheet or the like is used as the recording material, when the image after fixing is projected on a screen or the like by transmitted light, the developer on the recording material is fixed in order to be projected as a color image. It needs to be sufficiently melted so as not to scatter light after that, and therefore, sufficient heat and pressure need to be applied to the developer in the fixing device, which inevitably causes the offset phenomenon and oil coating on the roller. I couldn't avoid it.

When oil is applied to the roller surface in order to prevent the offset phenomenon, there is a problem that the oil adheres to the recording material and the image after fixing.

Further, since both the fixing roller and the pressure roller are heated to a predetermined temperature, power consumption is large and the time required for heating is long.

Further, instead of using such a fixing roller, there is a method of fixing using a film having a heat generating function. That is, one side of the moving film and the unfixed image bearing surface of the recording material are brought into close contact with each other, and the film is conveyed together with the film.
The heat generating part of the film, which is provided on the upstream side of the film moving direction, gives thermal energy to the unfixed image on the recording material, and the recording material and the film are separated downstream of the heat generating part in the film moving direction to obtain a fixed image. Is the way. This fixing method consumes less power, and since the film reaches a predetermined temperature instantly, there is an advantage that a copy can be taken immediately after the switch is turned on. However, when a developer that easily causes offset is used, a part of the developer may be offset to the film when the recording material and the film are separated.

[0014]

The problem to be solved is the occurrence of offset of the developer to the improved film.

[0015]

SUMMARY OF THE INVENTION According to the present invention, one side of a moving film and an unfixed image bearing surface of a recording material are brought into close contact with each other and are conveyed together with the film. The heat generating section applies heat energy to the unfixed image on the recording material, separates the recording material and the film downstream of the heat generating section in the film moving direction, and separates the recording material and the film between the heat generating section and the separating section. The fixing method includes a cooling unit that cools in a separated state.

In the fixing method according to the present invention, in the heat generating portion of the film, the softened developer is cooled in the cooling portion and the temperature thereof is lowered so that the developer is solidified and hardened, and the releasability from the film is enhanced, and the film is separated in the separating portion. After the fixing, the image is separated and the offset phenomenon of the developer on the film can be prevented.

That is, since the fixing film used in the present invention is of a type in which the film itself generates heat, the strength of the film is required in order to realize a high process speed of, for example, 120 mm / sec or more. Even when the thickness is set thick, the surface temperature of the film in the heat generating portion can be easily set to the required temperature. However, on the other hand, as the process speed becomes faster, the time required from the heat generating part to the fixing part becomes shorter, and it is effective to provide the cooling part in order to prevent the offset phenomenon of the toner to the film. Especially by using a substantially spherical developer,
Since the adhesive force between the film and the developer is weak, it becomes easier to prevent the offset phenomenon.

FIG. 1 is a schematic view of the structure of a fixing device used in the fixing method of the present invention.

FIG. 2 shows an example of an image forming apparatus using the fixing method of the present invention.

In this example, a color image forming apparatus using an intermediate transfer member is used.

In FIG. 2, reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) which is repeatedly used as a first image bearing member, and has a predetermined circumference in a clockwise direction indicated by an arrow. It is driven to rotate at a speed (process speed).

In the course of rotation, the photosensitive drum 1 is uniformly charged to a predetermined polarity and potential by a primary charger (corona discharger) 2 and then image exposure means (not shown) (color separation of color original image). The first exposure of the target color image by receiving the image exposure 3 by the imaging exposure optical system, the scanning exposure system by the laser scanner which outputs the laser beam modulated corresponding to the time series electric digital pixel signal of the image information). An electrostatic latent image corresponding to the color component image (for example, magenta component image) is formed.

Then, the electrostatic latent image is magenta toner M of the first color by the first developing device 41 (magenta developing device).
It is developed with (colored charged particles). At this time, the second to fourth developing units 42, 43, 44 (cyan, yellow, and black developing units) are in the operation-off state and do not act on the photosensitive drum 1, and the magenta toner of the first color The image is not affected by the second to fourth developing units 42 to 44.

Reference numeral 20 is an intermediate transfer roller as an intermediate transfer member.

The intermediate transfer roller 20 of this embodiment comprises a pipe-shaped core metal 21 and an elastic layer 2 of medium resistance formed on the outer peripheral surface thereof.
It consists of two.

The elastic layer 22 of medium resistance is made of silicone rubber.
Teflon rubber, chloroprene rubber, urethane rubber, EP
Carbon or metal oxide such as zinc oxide is mixed and dispersed in elastic material such as DM to adjust the electric resistance value (volume resistivity) to a medium resistance of 10 ⁵ to 10 ¹¹ Ω · cm, which is solid or foamed. It is a fleshy layer.

The image forming apparatus of this embodiment repeatedly uses an A3 size recording material 24 such as paper or film, and the circumference of the intermediate transfer roller 20 is 565 mm (slightly larger than the length of the A3 size recording material 24. Roller outer diameter 180m
m). The elastic layer 22 has a wall thickness of 8 mm and an Asker C hardness of 20 ° to 40 °.

The intermediate transfer roller 20 is disposed in contact with the lower surface of the photosensitive drum 1 by bearing in parallel with the photosensitive drum 1, and at the same peripheral speed as the photosensitive drum 1 in the counterclockwise direction indicated by the arrow. Rotate to.

The intermediate transfer roller 20 is held in pressure contact with the photosensitive drum 1 with a predetermined pressing force, and a transfer nip portion as a transfer portion is provided between the photosensitive drum 1 and the intermediate transfer roller 20. n are formed.

As the toner used in this embodiment, as an example, a non-magnetic one-component toner having a volume average particle diameter of about 10 μm is used, and a negative polarity toner having an intrinsic charge amount of about −25 μc / g is used. ing.

During the process in which the magenta toner image of the first color formed and held on the surface of the photosensitive drum 1 passes through the transfer nip portion N, the core metal of the intermediate transfer roller 20 is provided with the first magenta toner image for the intermediate transfer roller. A transfer bias having a polarity (plus) opposite to the toner charging polarity (minus in this example) is applied from the bias power source 61, and is intermediately transferred to the outer surface of the intermediate transfer roller 20 by the electric field formed in the transfer nip area. . In this example, the applied voltage is +2 kV to +5 kV.

The surface of the photosensitive drum on which the transfer of the magenta toner image of the first color onto the intermediate transfer roller 20 is completed is cleaned by the cleaning device 14.

Similarly, the following: Charge on the rotating photosensitive drum 1 → image exposure 3 corresponding to a second color component image (for example, a cyan component image) → development with the cyan toner C of the second developing device 42 (cyan developing device) → the formed second color Transfer of a certain toner image to the intermediate transfer roller 20 → cleaning of the photosensitive drum 1 surface by the cleaning device 14 ,. Charging of the rotating photosensitive drum 1 → image exposure 3 corresponding to a third color component image (eg, yellow component image) → third
Development with the yellow toner Y of the developing device 43 (yellow developing device) → transfer of the formed yellow toner image of the third color to the intermediate transfer roller 20 → cleaning of the photosensitive drum 1 surface with the cleaning device 14. Charge on the rotating photosensitive drum 1 → image exposure 3 corresponding to a fourth color component image (for example, a black (black) component image) → developing with the black toner B of the fourth developing device 44 (black developing device) → the formed first image Intermediate transfer roller 2 for black toner image of four colors
0 transfer → cleaning of the surface of the photosensitive drum 1 by the cleaning device 14, and the above-described image forming / transfer cycles are sequentially executed, whereby the above four toner images are formed on the outer surface of the rotary intermediate transfer roller 20. (Magenta cyan
The yellow and black toner images are sequentially superimposed and transferred to form a composite color toner (mirror image) corresponding to the target color image.

Reference numeral 25 denotes a transfer roller which is disposed in contact with the lower surface of the intermediate transfer roller 20 so as to bear in parallel with the intermediate transfer roller 20, and is arranged at the same peripheral speed as the intermediate transfer roller 20 in a clockwise direction indicated by an arrow. Rotate to.

The transfer roller 25 includes a core metal roller 26,
The elastic layer 27 is formed on the outer periphery of the elastic layer 27. In this example, an elastic body having a medium resistance is used.

In the process of sequentially transferring the toner images of the first to fourth colors from the photosensitive drum 1 to the intermediate transfer roller 20, the core metal 26 of the transfer roller 25 receives toner from the second bias power source 29 for the transfer roller. Bias voltage of the same polarity (-) is applied. This bias voltage generates an electric field that repels the toner image from the transfer roller 25 to the intermediate transfer roller 20, and prevents transfer of the toner image on the intermediate transfer roller 20 side to the transfer roller 25.

When the toner image on the photosensitive drum 1 is transferred to the intermediate transfer roller 20, the electric potential of the non-image portion is different from the electric potential of the toner image portion. Since the potential difference between the non-image portion is larger than the potential difference between the photosensitive drum and the toner image portion, the transfer current flows more than the non-image portion.

This tendency remarkably occurs when the resistance value of the intermediate transfer roller 20 is low. For example, when the electric pole value to the non-image portion is more than twice the current value to the toner image portion, the non-image portion is The electric field of influences the toner image, and the toner image causes “splitting” in the periphery. That is, the low resistance roller 20 is not suitable for an intermediate transfer member.

On the other hand, in the case of a high resistance roller, the electric field that can be formed by the bias power source 61 becomes too small, and the intermediate transfer itself is damaged.

Therefore, a roller having a medium resistance in the range of 10 ⁵ to 10 ¹¹ Ω · cm, preferably 10 ⁷ to 10 ¹⁰ Ω · cm is suitable for the intermediate transfer member. If the elastic body 22 having a volume resistance value in this range is used, by applying +2 to +5 KV to the core metal 21, the above-mentioned appropriate transfer current value can be set.

The transfer of the toner images of the first to fourth colors, which are sequentially superimposed and transferred from the photosensitive drum 1 side to the intermediate transfer roller 20 side, to the recording material 24 is performed from the paper feed cassette 9 side to the intermediate transfer roller 20. The recording material 24 separated and conveyed by the paper feed roller 10 one by one to the pressure contact nip portion n with the roller 25 is fed at a predetermined timing via the register roller 11 and the transfer guide 12, and the core metal of the transfer roller 25 is also fed. The bias power source for 26 is switched from the second bias power source 29 to the first bias power source 28, and a transfer bias having a polarity (+) opposite to that of the toner is applied to the core metal 26. This transfer bias has an absolute value larger than that of the bias of the opposite polarity (+) to the toner applied from the bias power source 61 to the cored bar 21 of the intermediate transfer roller 20. The toner image on the roller 20 side is transferred to the recording material 24 side fed to the pressure contact nip portion n between the intermediate transfer roller 20 and the transfer roller 25. The recording material 24 that has received the toner image transfer is the fixing device 15
Be introduced to.

When the recording material 24 passes through the pressure contact nip portion n, the core metal 21 and the transfer roller 25 of the intermediate transfer roller 20.
The second bias power source 6 applies the bias of the same polarity (-) as that of the toner to the core metal 26 of
It is switched to 2, 29.

By this bias switching, the transfer residual toner on the surface of the intermediate transfer roller 20 is returned to the photosensitive drum 1 surface side and is collected by the cleaning device 14, so that the intermediate transfer roller 20 is cleaned.

The toner adhering to the surface of the transfer roller 25 is also returned to the surface of the intermediate transfer roller 20, and further returned to the surface of the photosensitive drum 1 and collected by the cleaning device 14, so that the transfer roller 25 is also cleaned.

As described above, the intermediate transfer roller 20 includes the elastic layer 2
Since 2 is a medium resistance, by applying a bias (cleaning bias) having the same polarity as the toner, the transfer residual toner can be sufficiently returned and transferred to the photosensitive drum 1 surface side to be in a cleaning state, and a special cleaning device can be provided. It is not necessary and the device configuration can be simplified.

A schematic configuration diagram of the fixing device 15 of FIG. 2 is shown in FIG.

Reference numeral 7 is a heat-resistant endless film, and 8 is a cooling means arranged in contact with the inner surface of the endless film for cooling the film. In the present embodiment, an aluminum (A1) member with a radiation fin is provided. Is used. 13 is a fixing entrance guide, 18 is a transport guide for bringing the film and recording material into close contact, and 19 is a roller. In this embodiment, a metal roller such as Fe is used.

Reference numeral 30 denotes a roller, which in this embodiment has an elastic layer on the cored bar and drives the film. In addition, the roller 30 applies tension to the film by a spring 31 so that the film does not sag due to thermal expansion of the film.
The frictional force between the film and the film is obtained to prevent slippage.

Reference numeral 51 is a core bar, and 52 is an elastic layer. In this embodiment, a conductive silicon sponge obtained by mixing a conductive additive such as carbon with silicon rubber and foaming is used.
53 is a release layer, which is about 50 μm thick PFA or PT
A fluororesin tube such as FE is used.

The pressure roller 54 is constituted by 51, 52 and 53.
Are configured. The pressure roller 54 is brought into contact with the film 7 with a predetermined pressure, and at the nip portion formed by the film 7 and the pressure roller 54, the recording material 24
And a heating unit for applying heat and pressure to the unfixed toner image on the recording material.

A pressing member 17 prevents the film 7 from separating from the recording material 24.

The structure of the film 7 is shown in FIG. The film 7 has a four-layer structure.

A release layer 35 is provided on the surface of the film 7 in contact with the unfixed toner image on the recording material 24. In this embodiment, a fluorine resin such as PTEE or PFA having a thickness of about 20 μm is used as the elastic layer 32. It has a coat on it. Elastic layer 32 is about 1
Silicon rubber having a thickness of 00 to 200 μm is used. Three
3 is a conductive layer, and in this embodiment, Ni having a thickness of about 50 μm
The electroformed belt of is used.

Reference numeral 34 is an insulating layer, which prevents electric charges from escaping from the roller 19 or the like.

In FIG. 1, reference numeral 16 is a modulating magnetic field generating means, and an eddy current is generated in the conductive layer 33 by the modulating magnetic field generated by the modulating magnetic field generating means, and the conductive layer is heated by Joule heat due to this eddy current. . The generated heat is transferred to the recording material 24 and the unfixed toner image through the release layer, and is fixed on the recording material 24 by receiving heat and pressure in the nip portion.

The softened toner image to which heat is applied at the nip portion adheres to the film and is conveyed to the downstream side. The toner on the recording material is cooled by the cooling means 8, the temperature of the toner is lowered, and the toner solidifies and cures again.

For this reason, the adhesive force with the film is reduced,
It is possible to prevent the toner on the recording material from being offset to the film by separating the film from the recording material at the position of the roller 19.

The fixing method according to the present invention can be applied to various toner images, but is particularly effective for toner images formed with spherical or near spherical toner.

FIG. 4 shows a state in which the film 7 is pressed against the toner image formed on the recording material 24 formed of the non-spherical toner formed by the crushing method.

Since the pressure is strongly applied to the portion of the toner image near the portion A, the toner is melted and softened well. However, since the pressure is not applied well in the area B after the toner and the like, the degree of softening and melting of the toner is lower than that in the area A.

Therefore, when a toner particle such as a pulverized toner having a non-spherical shape is used, since the contact area between the toner and the film is large, the adhesive force to the film is large and the fixing is insufficient. Part of toner adheres to the film and becomes offset.

On the other hand, since the substantially spherical polymerized toner as shown in FIG. 5 is used, the contact area between the toner and the elastic layer is small and the adhesive force is small.

For this reason, the toner such as the B portion which is not sufficiently fixed does not adhere to the elastic layer which is the surface layer of the film 7 and is not offset.

As a suitable toner used in the present invention, the value of the shape factor SF-I measured by an image analyzer is 100 to 150, particularly preferably 100 to 125, and the optimum range is 100 to 110. . Furthermore, a toner containing a low softening point substance in an amount of 5 to 30% by weight is preferably used.

SF-indicating the shape factor used in the present invention
With I, 100 toner images were randomly sampled using (FE-SEMS-800 manufactured by Hitachi, Ltd.), and the image information was introduced into an image analysis device (Luxex3) manufactured by Nicolet Co. through an interface for analysis. In the present invention, the value calculated by the following formula is defined as the shape factor SF-I.

[0066]

[Outer 1] A toner shape having a large toner shape factor SF-I value gradually approaches an irregular shape from a spherical shape, and at the same time, a decrease in transfer efficiency is recognized. In the present invention, since the intermediate transfer member is provided in order to handle various materials, the transfer step is performed substantially twice, so that the transfer efficiency is remarkably reduced and the toner utilization efficiency is reduced, which is a problem. Furthermore, in recent digital full-color copying machines and printers, color image originals are color-separated in advance using B (blue), G (green), and R (let) filters.
~ 70μm dot latent image is formed Y (yellow) · M
It is necessary to reproduce a multicolor image faithful to the original by using the subtractive color mixing action by using the respective toners of (magenta), C (cyan) and B (black). At this time, on the photoconductor or the intermediate transfer body. For the Y, M, C, B toner, the original or CRT
The toner used in the present invention is required to have an extremely high transfer property because a large amount of toner is applied in accordance with the color information of 1. In order to realize it, the shape factor SF-I of the toner is 100.
The most preferable is a substantially spherical toner having a particle size of 110 to 110, and in order to faithfully develop finer latent image dots for higher image quality, the toner also has a smaller particle diameter, specifically, a weight average diameter of 4 μm. A toner having a number variation coefficient of 8 μm and a number variation coefficient of 35% or less is most preferable as the toner used in the present invention. In the case of a toner having a weight average diameter of less than 4 μm, a large amount of transfer residual toner is generated on the photosensitive member or the intermediate transfer member due to poor transfer efficiency, which causes uneven image unevenness due to fog and transfer failure. It is not preferable for the toner used in. Further, when the weight average diameter of the toner exceeds 8 μm, fusion to the member is apt to occur, and when the number variation coefficient of the toner exceeds 35%, this tendency becomes more serious and becomes a problem.

The particle size of the toner is measured as follows.

A Coulter Counter TA-II type (manufactured by Coulter) is used as a measuring device, and an interface (manufactured by Nikkaki) and a CX-1 personal computer (manufactured by Canon) for outputting number average distribution and volume average distribution are used. Connect and use 1st class sodium chloride electrolyte
% NaCl aqueous solution is prepared.

The measuring method is as follows:
To 150 ml, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant, and 0.5 to 50 mg of a measurement sample (toner) is further added.

The electrolytic solution in which the sample was suspended was subjected to a dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and the Coulter counter TA-II type used the 2.00 to 50.80 μm with a 100 μm aperture as an aperture. The particle size distribution of the particles is measured to obtain a weight average distribution and a number average distribution.

As the low softening point substance used in the present invention, a compound having a main component maximum peak value measured according to ASTM D3418-8 of 40 to 90 ° C. is preferable. If the maximum peak is less than 40 ° C., the self-aggregating force of the low softening point substance is weakened, and as a result, the high temperature offset property is weakened, which is not preferable for a full color toner. On the other hand, when the maximum peak exceeds 90 ° C., the fixing temperature becomes high, and it becomes difficult to appropriately smooth the surface of the fixed image, which is not preferable in terms of color mixing. Further, when the toner is obtained by the direct polymerization method, since the granulation / polymerization is carried out in an aqueous system, if the temperature of the maximum peak value is high, the low softening point substance mainly precipitates during granulation, which disturbs the suspension system. Not preferable.

In measuring the temperature of the maximum peak value of the present invention,
For example, Perkin Elmer DSC-7 is used. The melting point of indium and zinc is used to correct the temperature of the device detection unit, and the heat of fusion of indium is used to correct the amount of heat. An aluminum pan was used as a sample and an empty pan was set as a control, and the temperature rising rate was 10 ° C./min. Was measured.

Specifically, paraffin wax, polyolefin wax, Fisher Tropics wax,
Amide wax, higher fatty acid, ester wax and their derivatives or their graft / block compounds can be used. Particularly preferred in the present invention is an ester wax having at least one long-chain ester moiety having 10 or more carbon atoms represented by the following general structural formula, which has an effect on high-temperature offset property without impairing transparency of OHP. preferable.

The composition examples of the toner used in the present invention are as follows.

The cyan toner was prepared as follows.

In a 21-liter four-necked flask equipped with a high-speed stirring device, 710 parts by weight of ion-exchanged water and 450 parts by weight of 0.1 mol / 1-Na ₃ PO ₄ aqueous solution were added to adjust the rotation speed to 12,000 rotations. And heated to 65 ° C. 68 parts by weight of a 1.0 mol / 1-CaCl ₂ aqueous solution was gradually added to prepare a dispersion medium system containing a microscopically difficult aqueous solution dispersant Ca ₃ (PO ₄ ) ₂ . On the other hand, the dispersoid system comprises styrene monomer 165 parts by weight n-butyl acrylate monomer 35 parts by weight C.I. I. Pigment Blue 15: 3 14 parts by weight Saturated polyester 10 parts by weight {Teriphthalic acid-propylene oxide modified bisphenol A acid value 15, peak molecular weight; 6000} Metallic salicylate compound 2 parts by weight The following compound (maximum peak value 59.4 ° C.) 60 Parts by weight

[0077]

[Outside 2]

The above mixture was dispersed for 3 hours using an attritor, and then 10 parts by weight of 2,2'-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator was added to the dispersion medium. 15 while throwing in and maintaining the number of rotations
Granulated for minutes. After that, the stirrer was changed from the high speed stirrer to the propeller stirrer and the internal temperature was raised to 80 ° C., and the polymerization was continued at 50 rpm for 10 hours. After the polymerization is completed, the slurry is cooled,
Dilute hydrochloric acid was added to remove the dispersant.

By further washing and drying, the weight average diameter of the cyan toner measured by a Coulter counter is 6.
The number variation coefficient is 27% at 2 μm and SF-I is 10
It was 4.

Similarly, yellow toner, magenta toner and black toner having SF-I of 104 were manufactured. In addition, as a yellow toner as a colorant, C.I.
I. Pigment Yellow 17 and magenta toner include C.I. I. As the pigment red 122 and the black toner, carbon black was used.

Using the four-color toner thus manufactured, a multicolor color image was formed using the image forming apparatus of FIG. 2 equipped with the fixing device shown in FIG. As a result, the toner offset did not occur on the film 7 of the fixing device (the film surface temperature of the heat generating portion was 180 ° C.) even when 150,000 or more copies were formed.

Other toners were prepared as follows.

Styrene-n-butyl acrylate copolymer 200 parts by weight C.I. I. Pigment Blue 15: 3 14 parts by weight Saturated polyester 10 parts by weight {Terephthalic acid-propylene oxide-modified bisphenol A acid value; 15, peak molecular weight; 6000} Metal salicylate compound 2 parts by weight The above compound 15 parts by weight The above composition is used as an extruder. After sufficiently kneading, the mixture was crushed against a target using a jet stream, and further, using a classifier using the Counder effect, a cyan toner of a pulverization method having a weight average diameter of 8.2 μm and a number variation coefficient of 32% was obtained. Commercially available calcium phosphate was externally added to this toner using a Henschel mixer, and the obtained toner was further dispersed in water using a homomixer, and the water temperature was gradually raised to heat treatment at 80 ° C. for 3 hours. After that, dilute hydrochloric acid was added to sufficiently dissolve and remove the calcium phosphate on the toner surface. Subsequently, the toner was manufactured by washing and drying. The shape factor SF-I of this toner was 125. Similarly, SF-I is 1
Twenty-five yellow, magenta and black toners were produced. As the colorant, yellow toner is C.I. I. Pigment Yellow 17 and C.I. as magenta toner. I. As the pigment red 122 and the black toner, carbon black was used.

Similarly, the formation coefficient SF-I is
All produced 150 cyan, yellow, magenta and black toners.

The SF-I manufactured in this way has 1.
A 25-color four-color toner and a 1.50 four-color toner were used to form a multi-color image using the image forming apparatus of FIG. 2 equipped with the fixing device shown in FIG. The surface temperature of the heat generating film of the fixing device is 180 ° C. As a result, S
When FI used 125 toner, toner offset did not occur on the film up to 100,000 copies.
Also, when SF-I toner of 150 is used, it is 5
The toner did not offset on the film up to 10,000 copies.

6 to 8 are schematic structural views of other fixing devices used in the present invention.

In this embodiment, unlike the case of FIG.
Heat is generated by energizing the electric resistance layer provided in the.

In this embodiment, the film 7 is formed by depositing AgP on a heat-resistant film 105 such as polyimide having a thickness of about 10 μm.
Electrical resistance layer 1 with a thickness of about 20 μm, such as d (silver palladium)
04 is provided, and as the protective layer 107 of the electric resistance layer, about 20
It is formed of a heat-resistant resin such as polyimide or polyamide-imide having a thickness of μm, and an elastic layer 106 is provided as a surface layer. As the elastic layer, LTV silicone rubber added with a fluorosurfactant having a thickness of about 100 to 200 μm is used.

On the inner surface of the film 7, both ends of the film are not covered with the heat resistant film, and the electric resistance layer 1
04 is exposed.

A voltage is applied to this portion from a power source (not shown) through the contact 102, a current flows through the electric resistance layer between the contacts 102, and Joule heat is generated to generate heat.

The pressing member 100 has a surface in contact with the film 7 in order to prevent the film from being scraped due to friction.
1 is provided with a release layer 103, and PTFE, PFA
Fluorine resin etc. are coated. Cross-sectional views of the film 7 and the pressing member 100 are shown in FIGS. 7 and 8. A nip portion is formed by the pressing member 100 and the pressure roller 54,
By applying heat and pressure in the nip portion, the unfixed toner on the recording material is softened and melted, and fixed on the recording material. After that, the toner that has been cooled in the cooling unit and softened is solidified when the temperature drops, and the film 7 and the recording material are separated in the separating unit, thereby forming an oilless fixing device without offset.

In this embodiment, the modulating magnetic field generating means used in FIG. 1 is not required, so that the size and cost can be reduced.

[0093]

As described above, according to the present invention,
It is possible to provide a fixing device that prevents the offset phenomenon without the use of oil coating, and there is no oil adhesion to the image after fixing, miniaturization, low cost, no need for regular maintenance, oil leakage and oil stains. There is an effect that can provide a fixing device not.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a fixing device used in the present invention.

FIG. 2 is a schematic configuration diagram of an image forming apparatus including the fixing device of FIG.

FIG. 3 is a schematic configuration diagram of a film in the fixing device of FIG.

FIG. 4 is an explanatory diagram of a cause of an offset.

FIG. 5 is an explanatory diagram of a cause of no offset.

FIG. 6 is a schematic configuration diagram of another fixing device used in the present invention.

FIG. 7 is a schematic configuration diagram of a film of the fixing device shown in FIG.

FIG. 8 is a schematic configuration diagram of a film of the fixing device shown in FIG.

FIG. 9 is a schematic configuration diagram of a conventional fixing device.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Katsuhiko Nishimura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hiromichi Yamada 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Masami Takeda 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Satoshi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Takashi Shibuya 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yasuo Yoda 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masahide Hirai 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Tatsuya Nakamura 3-30-2 Shimomaruko, Ota-ku, Tokyo Down in the Corporation

Claims (13)

[Claims] 1. A heat-generating portion of the film, which is provided on the upstream side in the moving direction of the film, is brought into contact with the unfixed image-bearing surface of the recording material and brought into close contact with the surface of the recording material that bears the unfixed image on the recording material. A cooling unit that applies heat energy to the unfixed image, separates the recording material and the film downstream of the heat generating portion in the film moving direction, and cools the recording material and the film in the unseparated state between the heat generating portion and the separating portion. And a fixing method. 2. The fixing method according to claim 1, wherein the heat generating portion of the film generates heat by the modulation magnetic field means. 3. The fixing method according to claim 1, wherein the heat generating portion of the film generates heat when energized. 4. The fixing method according to claim 1, wherein the film is an endless belt. 5. The unfixed image has a shape factor SF-I of 10.
The fixing method according to claim 1, wherein the fixing method is formed with a toner having a size of 0 to 150. 6. An unfixed image has a shape factor SF-I of 10.
The fixing method according to any one of claims 1 to 4, wherein the fixing method is formed with a toner of 0 to 125. 7. An unfixed image has a shape factor SF-I of 100.
The fixing method according to any one of claims 1 to 4, wherein the fixing method is formed of a toner having a size of 110 to 110. 8. The unfixed image contains a low softening point substance,
The fixing method according to claim 1, wherein the fixing method is formed of a toner having a shape factor SF-I of 100 to 110. 9. The content of the low softening point substance is 5 to 30% by weight.
The fixing method according to claim 8, wherein 10. A film having a heat generating portion, which is arranged so as to move in close contact with the recording material, and for cooling the recording material and the film between the heat generating portion and the separating portion between the film and the recording material. A fixing device comprising: 11. The fixing device according to claim 10, wherein the heat generating portion of the film generates heat by the modulation magnetic field means. 12. The fixing device according to claim 10, wherein the heat generating portion of the film generates heat when energized. 13. The fixing device according to claim 10, wherein the film is an endless belt.