JPH034281A - Fixing device - Google Patents

Abstract

PURPOSE:To reduce offset of toner to a fixing rotational body and to obtain high cleaning effect by using a conductive cleaning member, which cleans a fixing rotational body, and grounding the conductive member. CONSTITUTION:A cleaner 36 comes into contact with a fixing roller 21 by means of a pressure roller 37, and cleans the fixing roller with a fibrous web 38; at least a web surface which abuts on the roller is nickel-plated. In the web 38, heat resistant nonwoven fabric is nickel-plated in the electroless plating method, and the fibrous surface of the web is coated with nickel approximate mudegrees in thickness so that its weight comes to 3g per m<2> of the web. The grounding of a metallic takeup roller 117 electrically grounds the web 38. In this manner, offset to the fixing roller 21 can be reduced, and high cleaning effect can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application of the Invention] The present invention relates to a fixing device having a cleaning member for cleaning a fixing rotating body.

[Prior art]

FIG. 2 shows an electrophotographic image forming apparatus equipped with a fixing device.

The apparatus main body 10 from one side of the apparatus main body 100 (right side in FIG. 1)
A transfer material conveyance system I is provided over approximately the center of the recording material conveyance system I, and a transfer material conveyance system I is provided approximately in the center of the apparatus main body 100, close to the transfer drum 9 constituting the recording material conveyance system I. An image forming section (2), a developing means (i.e., a rotary developing device (2)) disposed adjacent to the latent image forming section (2), and the rotary developing device (2).
and a developer replenishing means, that is, a developer replenishing device 2, which is disposed adjacent to the developer replenishing means. The recording material conveyance system I described above is
A recording material supply tray 10 is detachably attached to an opening formed on one side (right side in FIG. 1) of the apparatus main body 100.
1,102, and the tray 101. Paper feeding rollers 103 and 104 disposed substantially directly above the paper feeding rollers 103 . 104 and provided with paper feed rollers 6, and paper feed guides 5a and 5b provided with paper feed rollers 6, and paper feed guides 5a and 5b provided near the paper feed guide 5b and abutting rollers near the outer peripheral surface from the upstream side to the downstream side in the rotational direction. A contact roller 8, a gripper 7, a recording material separation charger 14, and a separation claw 15 are provided, and a transfer charger 10 and a recording material separation charger 13 are provided on the inner circumferential side.
a transfer drum 9 that is rotatable in the direction of the arrow in FIG. The apparatus includes a discharge tray 10 that is detachably attached to the apparatus main body 100 and extends outside the apparatus main body 100, and a fixing device 17 that is adjacent to the discharge tray 10.

The latent image forming section (2) includes an image carrier, that is, a photosensitive drum 3, which is disposed so that its outer circumferential surface is in contact with the outer circumferential surface of the transfer drum 9, and is rotatable in the direction of the arrow in FIG. 2; A static eliminating charger 11 is disposed near the outer peripheral surface of the drum 3 from the upstream side to the downstream side in the rotational direction of the photosensitive drum 3.
, a cleaning means 12, a charger 4, an image exposure means such as a laser beam scanner, and an image exposure reflection means such as a polygon mirror for forming an electrostatic latent image on the outer peripheral surface of the photosensitive drum 3. ing. The rotary developing device m includes a rotatable housing (hereinafter referred to as a "rotating body") l.
and visualize (that is, develop) the electrostatic latent image formed on the outer circumferential surface of the photoreceptor drum 3 at a position opposite to the outer circumferential surface of the photoreceptor drum 3 mounted in the rotating body l. The magenta developer IM looks like this.

It has a cyan developer IC, a yellow developer IY, and a black developer IBK. The developer replenishing device 2 includes:
A yellow hopper 2Y, a magenta hopper 2M, and a cyan hopper 2C are arranged adjacent to each other and hold developer for each color separately supplied from the outside.

The black hopper 28 is equipped with and.

First, the entire sequence of the image forming apparatus having the above-described configuration will be briefly described using a full color mode as an example. When the photoreceptor drum 3 described above rotates in the direction of the arrow in FIG. 1, the photoreceptor on the photoreceptor drum 3 is uniformly charged by the primary charger 4. - When the photoreceptor is uniformly charged by the charger 4, image exposure is performed with the laser beam E modulated by the magenta image signal of the original (not shown), and the electrostatic charge is generated on the photoreceptor drum 3. A latent image is formed and the rotating body! As the magenta developer IM is rotated, the electrostatic latent image is developed by the magenta developer IM, which has been placed in advance at the development position.

On the other hand, paper feed guide 5a, paper feed roller 6, paper feed guide 5b
The recording material conveyed via the is held by the gripper 7 at a predetermined timing, and is electrostatically transferred to the transfer drum 9 by the contact roller 8 and the electrode facing the corresponding contact layer roller 8. Can be wrapped around.

The transfer drum 9 rotates in the direction of the arrow in FIG. The image is transferred by the transfer charger 10 at the portion where the outer circumferential surface is in contact with the image. The transfer drum 9 continues to rotate and prepares for transfer of the next color (cyan in FIG. 2).

On the other hand, the photoreceptor drum 3 is neutralized by the defrosting charger 11, cleaned by the cleaning means z2, and then charged again by the primary charger 4, and is then charged by the next cyan image signal as described above. The rotary developing device fiffil rotates while an electrostatic latent image is formed on the photoreceptor drum 3 by the cyan image signal by the image exposure, and the cyan developing device The cyan color is fixed at the development position and a predetermined cyan development is performed.Subsequently, the above-mentioned process is also carried out for yellow and black colors respectively, and when the transfer of the four colors is completed, the image is formed on the recording material. The four-color sequential images are for each charger 1.
The charge is removed by 3.degree. 14, the transfer material is no longer gripped by the gripper 7, and the recording material is separated from the transfer drum 9 by the separating claw 15 and sent to the conveyor belt 16. Thereafter, the sheet is sent by an entrance guide 19 between fixing rollers of a heat fixing device to be described later, is heated and fixed, and is further discharged to the outside of the main body by a sheet discharge roller 20 which is a sheet discharge guide member.

In this way, a series of full-color print sequences are completed, and a desired full-color print image is formed.

Next, toner used in this electrophotographic apparatus will be explained.

Toner for color electrophotographic equipment must have good melting properties and color mixing properties when heat is applied, and must have a low softening point (
In addition, it is preferable to use a sharp melt toner having a low melt viscosity. That is, by using such a sharp melt toner, it is possible to widen the color reproduction range of a copy and obtain a color copy that is faithful to the original image.

Such a sharp melt toner is produced by melt-kneading, pulverizing, and classifying, for example, a polyester resin, a styrene-acrylic resin, a colorant (dye, sublimable dye), a charge control agent, and the like. If necessary, an external addition step of adding various external additives to the toner may be added.

In consideration of fixability and sharp melting properties, color toners using polyester resin as a binder resin are particularly preferred.

A sharp-melt polyester resin is a high molecular compound having an ester bond in the main chain of the molecule, which is synthesized from a diol compound and a dicarboxylic acid.

The softening point of the sharp melt polyester resin used in the Figure 2 Examples is 60-150°C, preferably 80-150°C.
20℃ is good.

The softening characteristics of this sharp melt toner are shown in FIG.

Using a flow tester CFT-500 type (manufactured by Shimadzu Corporation), the diameter of the die (nozzle) is 0.5 mm and the thickness is 1.0 m.
Add an extrusion load of 50 kg as m and initial setting temperature is 80°C.
After a preheating time of 300 seconds, the toner plunger drop amount vs. temperature curve (hereinafter referred to as the softening S-curve) drawn when the humidity is raised at a constant rate of 5°C/min is determined.The sample toner is 1. ~3 g of purified fine powder is used, and the plunger cross-sectional area is 1.0 ctd.

The softening S-shaped curve becomes a curve as shown in FIG. As the temperature rises at a constant rate, the toner is gradually heated and begins to flow out (plunger descends A4B). When the temperature is further increased, the molten toner largely flows out, B-4C-+D) and the plunger stops descending (D-4E).

The height H of the S-curve indicates the total outflow amount, and the temperature T0 corresponding to the 0 point of H/2 indicates the softening point of the toner.

Such sharp melt resins have a melt viscosity of 10
When the temperature when the 'cp is shown T H, and the temperature when the 5X10' cp is shown is T2, T =90~150℃ΔT
It refers to a resin that satisfies the condition of l=lT+ -T21=5 to 30°C.

Sharp-melt resins having these temperature-melt viscosity characteristics are characterized by an extremely sharp decrease in viscosity when heated. Such a viscosity reduction causes proper mixing of the uppermost toner layer and the lowermost toner layer, and also rapidly increases the transparency of the toner layer itself, resulting in good subtractive mixing.

Such sharp melt color toner has a high affinity and is easily offset to the fixing roller.

Referring to FIG. 3, the fixing device 17 will be explained in detail.

Reference numeral 21 denotes a fixing roller, which is formed by coating the outer layer of an aluminum core 22 with HTV silicone rubber (high temperature vulcanization type silicone rubber) 23 to a predetermined thickness.

Furthermore, the outer layer is coated with LTV silicone rubber (low temperature vulcanization type silicone rubber) 24 to a thickness of 200 μm. A pressure roller 25 is provided below the fixing roller 21, and is made by coating the outer layer of an aluminum core 26 with HTV silicone rubber 27 to a predetermined thickness.
Furthermore, a resin coating 27' is applied to the surface layer.

Further, a halogen heater 28 serving as a heat source is disposed within the fixing roller 21 and the pressure roller 25.

A thermistor 29 is brought into contact with the pressure roller 25, and the thermistor 29 controls whether the supply of current to the halogen heater 28 is turned on or off.

In this way, the temperature of the fixing roller 21 and the temperature of the pressure roller 25 are adjusted to a predetermined temperature (for example, 17
It is maintained at a temperature of 0°C. These fixing roller 21 and pressure roller 25 are rotated in the direction of the arrow in the figure by a drive device (not shown).

On the other hand, in order to improve the releasability of toner from the fixing roller 21, a release agent application device 32 is provided at a predetermined location of the fixing device. This mold release agent application device 32 applies silicone oil 33 in an oil tank to a group of rollers 34. 35
The composition is configured to be applied to the fixing roller 21 by the following steps.

Furthermore, a cleaning device 36 is provided at a predetermined location of the fixing device to clean the toner offset onto the fixing roller 21. This cleaning device 1136 is made of a fibrous cleaning web made of Nomex (trade name) that is brought into contact with the fixing roller 21 by a pressing roller 37, and cleans the fixing roller 21.

To further explain the operation explained with reference to FIG. 2, the recording material 30 on which the toner image 31 has been transferred is conveyed on the conveyor belt 16, passes through the population guide 19, and passes between the fixing roller 21° and the nip of the pressure roller 25. The toner image 31 enters the recording material 30 and is fixed on the recording material 30 by the heat and pressure applied.

Thereafter, the recording material 30 is guided by a paper discharge guide 38 and sent out of the machine by a paper discharge roller 20 that is a paper discharge guide member.

[Problems solved by the invention]

Conventionally, the above-described copying operation has caused the following problems.

In other words, by rotating rollers made of the materials mentioned above for each roller of the fixing device, the fixing roller whose surface is made of silicone rubber has a strong positive effect, and the pressure roller whose surface is made of fluorine resin has a strong negative effect. is charged with electricity.

Here, when the negatively charged toner transferred onto the recording material is layered for each color and the fixing roller enters between the pressure rollers, a problem arises in that the toner image is disturbed due to its charging characteristics.

This is because the toner on the surface layer is electrically unstable because the toner is stacked, and before it is heated and fixed, it electrically flies to the fixing roller side, resulting in an image that looks like it's flying off or smeared. This results in an image that is fixed in a more disordered state than immediately after being transferred.

Furthermore, if this electrostatic force is strong, the toner will adhere to the fixing roller even after fixing, resulting in a so-called offset state.

[Means to solve problems]

The present invention, which solves the above problems, includes a fixing rotor whose surface is made of silicone rubber and comes into contact with the unfixed toner image, and a pressurizing rotor whose surface is made of fluororesin and comes into pressure contact with the fixing rotor. In a fixing device which fixes an unfixed toner image by sandwiching and conveying a support supporting a negatively charged unfixed toner image between the pair of rotating bodies, a cleaning member for cleaning the fixing rotating body is provided. , the cleaning member is electrically conductive, and the electrically conductive cleaning member is grounded, and
A fixing device having a fixing rotary body for fixing a toner image and a web for cleaning the fixing rotary body, wherein at least the side surface of the web that contacts the fixing rotary body is electrically conductive; This web is characterized by being grounded.

〔Example〕

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

FIG. 1 is a block diagram of a fixing device according to an embodiment of the present invention.

1 except for the cleaning device 36, which is almost the same as FIG. 3, and therefore will not be described. This cleaning device 36
The fixing roller 21 is cleaned by a web 38, which is a cleaning member that is brought into contact with the fixing roller 21 by a pressing roller 37, and has a fibrous cleaning web nickel-plated at least on the roller contacting surface side. This nickel-plated web 38 is made by plating the conventional heat-resistant nonwoven fabric Nomex (trade name) with nickel, a substance with higher surface energy than Nomex, using an electroless plating method, and the surface of the fibers of the web has a thickness of about μ. Web lrr? It is coated with nickel so that it weighs 3g per piece.

Additionally, the nickel-plated web is electrically grounded by grounding the metal take-up roller.

The nickel-plated web 38 constructed in this way is sent in the direction of arrow C in the figure by a feed roller 114 and is wound up by a take-up roller 117.

Here, we will explain how to make a nickel-plated web.

Conventional non-woven fibers made of Nomex (trade name) are degreased with a solvent and then chemically etched. This degreasing and chemical etching is performed by conventionally known methods to clean and roughen the fiber surface.

Further, platinum is applied as a reducing agent, and then the fiber is passed through a dipping seed at a constant speed through a nickel plating layer temperature for electroless plating, so that nickel metal is electrolessly plated on the fiber. The amount of nickel deposited on the fiber is
During the above process, all the conditions are operated, but in particular, it greatly depends on the bath concentration of the electroless nickel plating bath and the speed at which the Nomex fiber passes through the bath.

Naturally, the higher the bath concentration, the greater the amount of nickel metal deposited per 1 rrr of Nomex fibers, and the faster the passing speed of the fibers in the bath, the smaller the amount of nickel metal deposited.

The Nomex fibers on which nickel is electrolessly plated are then washed with water, dried, and completed as a cleaning web.

In the embodiment of the present invention, 3 g of nickel is deposited per 1 d by appropriately adjusting the bath concentration and the speed at which the fibers pass through the bath.

Next, the function of the fixing device will be explained.

The recording material 30 carrying the unfixed toner image 31 is conveyed by an unillustrated device in the direction of arrow a in FIG. The unfixed toner is passed between the pressure roller 25 and carried on the recording material 30 by heat controlled to a predetermined temperature, which is supplied from the halogen heater 28 via the fixing roller 21 and the pressure roller 25, respectively. Image 31 is recording material 3
Fixed on 0. At this time, the surface of the fixing roller is neutralized by the nickel-plated web, and the fixing roller becomes electrically charged to almost zero. Even if negatively charged toner enters such a fixing roller for fixing, there is no electrostatic force on the fixing roller, and the toner will not scatter or be disturbed. Furthermore, phenomena such as offset are less likely to occur.

Furthermore, even if the fixing roller is used for a long period of time, the surface releasability deteriorates and the toner begins to offset slightly.
This time, the nickel-plated web has a cleaning function and cleans the surface of the fixing roller.

The nickel-plated web 38 is pressed by the pressure roller 37 and moved to the take-up roller 36 at a predetermined speed (for example,
5 mm per 100 sheets of recording material. Then, the nickel plated web 38 is attached to the fixing roller 2.
! As it rotates, it is rubbed against the surface of the fixing roller 21, thereby cleaning the surface of the fixing roller.

In this case, since the nickel plated web 38 is fibrous, it is in good contact with the fixing roller 21, unlike a smooth and hard cleaning member such as a metal roller. That is, as shown in FIG. 2, the toner 31 that is offset in some places on the surface of the fixing roller 21 is adsorbed between the fibers 122 of the web 38, so that the toner does not accumulate locally and the fixing roller 21 and nickel plated web 38
The contact condition will be good. Since the web 38 is fibrous, it is highly effective in wiping off toner from the roller.

(FIG. 5) In addition, the nickel contained on the side of the nickel-plated web 38 that contacts the fixing roller 21 absorbs the toner on the fixing roller 21 because metals such as nickel have high surface energy and high affinity with toner. As a result, the cleaning ability of the cleaning device 36 to remove toner from the fixing roller 21 is significantly improved compared to conventional webs.

Therefore, although toner strongly adheres to the surface of the fixing roller 21 due to a decrease in the releasability of the surface of the fixing roller 21, such toner can also be easily removed.

Therefore, the winding speed of the nickel-plated web 38 according to the present invention is different from that in the case of a web made only of Nomex fibers, which was wound 75 mm per 10 sheets of recording material and was wound at a high speed so as to always clean a new surface of the web. On the other hand, for the nickel-plated web, the feed speed was slowed down to 1/15. Even in this case, as described above, since the toner cleaning ability is high, the nickel-plated web can have a long service life until the fixing roller offsets.

With the above configuration, the effect of static elimination on the surface of the fixing roller by the nickel-plated web causes the negatively charged toner to be drawn toward the fixing roller, preventing it from scattering or being disturbed, and preventing static electricity from moving toward the roller. Since the force is small, offset is less likely to occur.

Also, since the nickel web is also a cleaning member,
Due to the durability of the fixing roller, even if the surface releasability deteriorates and toner offset occurs, the nickel-plated web's adhesive leaning effect cleans the offset toner on the roller, allowing the fixing roller to be used for a long period of time. I can do things.

With this embodiment, the phenomenon that conventionally occurs when the toner layer on the recording material is thick, such as the toner scattering or being disturbed, does not occur at all, and also, conventionally, offset occurs at 20,000 sheets. In contrast, it has become possible to extend the life of the roller by offset up to 10,000 sheets.

Conventionally, as a countermeasure against toner offset caused by electrostatic force, the surface condition of the fixing roller is electrically checked by grounding the core bar of the fixing roller with a static eliminating brush or by grounding the core bar of the roller. Although there are known methods to reduce the charge to zero, in the present invention, since the surface is directly neutralized, the static elimination effect is large.

In addition, compared to the method disclosed in Utility Model Application Publication No. 59-48555, in which the opposite surface of a web roller is made conductive with metal and grounded to eliminate static electricity from the roller surface, it is far more effective in removing static electricity. big. In contrast to the method disclosed in Japanese Patent Laid-Open No. 62-273592, in which static electricity is removed from the roller surface by mixing some conductive fibers into an oil coating member, the static electricity removal is very unstable, the present invention is very stable. Static electricity can be removed. In particular, the present invention has metal on the entire surface of the cleaning member, and the surface of the cleaning member directly removes static electricity and cleans the roller surface, which is particularly effective.

〔effect〕

As described above, according to the present invention, a stable and high static elimination effect can be obtained, the offset of toner to the fixing rotor can be greatly reduced, and a high cleaning effect can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a fixing device according to an embodiment of the present invention, and FIG.
FIG. 3 is a sectional view showing a conventional image forming apparatus, FIG. 3 is a sectional view showing a conventional fixing device, FIG. 4 is a diagram illustrating the softening characteristics of color toner, and FIG. 5 is a cleaning example of an embodiment of the present invention. It is a figure showing an effect. In the figure, 17...Fixing device 21...Fixing roller 25...Pressure roller 36...Cleaning device 38...Web ridge Ihi, Se, Taka

Claims (3)

[Claims] (1) It has a fixing rotor whose surface is made of silicone rubber and comes into contact with the unfixed toner image, and a pressurizing rotor whose surface is made of fluororesin and comes into pressure contact with the fixing rotor; A fixing device that fixes an unfixed toner image by nipping and conveying a supporting material that supports a negatively charged unfixed toner image, the fixing device includes a cleaning member that cleans the fixing rotary body, the cleaning member A fixing device having electrical conductivity, the electrically conductive cleaning member being grounded. (2) In a fixing device having a fixing rotary body for fixing a toner image and a web for cleaning the fixing rotary body, the web has at least an electrically conductive side surface that comes into contact with the fixing rotary body. 1. A fixing device comprising: said web being grounded; (3) The fixing device according to claim 1, wherein the web is an insulating material plated with metal.