JP2002244517A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of attaining excellent cleaning ability even in the case of combining and using soft toner with hard toner in spite of using a high-hardness blade realizing the prolongation of a life, preventing failure that a stripe image is formed because a drum is damaged, attaining more excellent durability, made good in profitability and stably forming a high-quality image over a long term. SOLUTION: This image forming device is provided with a carrier for carrying an image or transfer material and a cleaning device for removing toner powder on the carrier with the blade arranged to abut on the surface of the carrier. The blade is made of material whose hardness (JIS-A) is >=70 and a solid lubricant incorporating resin layer is formed only on its side abutting on the carrier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus for forming an image on an image carrier using an electrophotographic method, and for carrying the image after the image formation. On body or transfer material (especially intermediate transfer body etc.)
The present invention relates to an image forming apparatus having a configuration in which a residual toner remaining on a carrier for carrying the toner is collected by a bleed-type cleaning device in contact with the carrier.

[0002]

2. Description of the Related Art Conventionally, a full-color image forming apparatus using an electrophotographic system includes a plurality of image forming units using an electrophotographic system, and each image forming unit performs a static operation on an image carrier such as a photosensitive drum. Each of the latent images is developed with a different color toner (developer) to form a visible toner image.
These toner images are successively superimposed and transferred onto the same recording material (paper or the like) on a transfer material such as a transfer belt.
A multi-transfer type image forming apparatus for fixing and forming a color image, or using an intermediate transfer body, on the intermediate transfer body, once on the image carrier formed by each image forming unit as described above An image is formed by superimposing each color toner image, and finally,
There are various proposals, such as an image forming apparatus having an intermediate structure for performing batch transfer onto a transfer material.

In these apparatuses, in order to stably obtain a high-quality image, after the image is formed, the residual toner that has not been transferred onto the image carrier or the intermediate transfer body is collected by a cleaning device. Have been done. As the cleaning device, a device having a cleaning blade made of an elastic material such as urethane rubber is usually used, and the blade is brought into contact with an image carrier or an intermediate transfer member to scrape off residual toner and collect the toner. I have.

On the other hand, as a toner used for image formation, in recent years when color image forming apparatuses have become widespread, in order to achieve both black-and-white image formation and color image formation,
When the color toner is soft and the black toner is hard, it is becoming common to use the toner with different softening points. Here, the softening point of the toner is determined by a conventionally known measuring method. The temperature at which the apparent melt viscosity shows 10 Pa · s is represented by T1,
The temperature when the apparent melt viscosity is 50 Pa · s is defined as T2
The one satisfying the following conditions is called a sharp melt toner. T1 = 90 to 150 ° C. | ΔT | = | T1−T2 | = 5 to 20 ° C. On the other hand, a toner having a higher T1 temperature or ΔT temperature than a sharp melt toner satisfying the above conditions is regarded as a hard toner. Calling. Examples of the sharp melt toner satisfying the above conditions include those using a polyester resin or the like as a binder resin constituting the toner.

[0005] In the case where a toner obtained by combining a soft color toner and a hard black toner as described above is used for image formation, the blade of the cleaning device is conventionally provided with a toner for only a color application, ie, a softening toner. Urethane rubber blades having the same low hardness as those used for image forming apparatuses with low toner have been used. This is, for example, when cleaning residual toner on the image carrier,
For a soft toner having a low softening point, that is, a soft toner that is difficult to clean, good cleaning can be performed by keeping the hardness of the cleaning blade low and widening the blade nip with the image carrier. Originally, a cleaning blade having a high rebound resilience is preferable, but a blade having a high resilience cannot be produced if the hardness is high. Therefore, from the viewpoint of satisfactorily cleaning a soft color toner, a blade having a low resilience is used. -ing

However, the use of a low-hardness forming material for the cleaning blade has gained momentum,
This means that the life of the cleaning blade must be short.

On the other hand, conventionally, when a hard toner is used, rubber having high hardness has been used for the cleaning blade. This is because a hard toner has good cleaning properties, so that even if the blade has low rebound resilience, good cleaning can be performed as compared with a case where a soft toner is used. ,
Taking advantage of the long life, for example, a rubber having a high hardness of 70 degrees or more but a low rebound resilience has been used. From the viewpoint of extending the life of the cleaning blade, the use of a urethane rubber blade having a hardness of 70 degrees or more is more sensitive than the use of a urethane rubber blade having a hardness of less than 70 degrees. This is preferable because the loss due to friction with the body drum is small and the blade is not easily chipped.

Under the circumstances described above, in an image forming apparatus using a combination of the above-described soft color toner having a low softening point (color toner) and a hard black toner for black and white having a high softening point, first of all, , Using low-hardness rubber to prioritize the cleaning properties of color toners,
In addition, in order to improve the slipperiness with the photosensitive drum or the like, a coating with nylon is performed so that the life of the cleaning blade is short. For example, a cleaning blade made of a relatively low-hardness urethane rubber having a hardness of 61 degrees and a rebound resilience of 9 and the surface of which is coated with nylon as described later has been used. in this case,
The service life was as short as 62 km with respect to the photosensitive drum traveling distance and blade replacement. This is because, as described above, this is performed from the viewpoint of placing importance on the cleaning property rather than extending the life of the cleaning blade.

[0009]

In view of the above situation, in recent years, by using a lactone-based material in the formulation of urethane rubber blade material, a blade having high hardness and high rebound resilience has been provided. Has become possible. In this case, in order to prolong the life of the cleaning blade, it is necessary to increase the hardness of the material to be used. In particular, as described above, there is a demand to use a material having a hardness of 70 degrees or more. Is made. However, according to the study of the present inventors, when a blade having such a high hardness is used, if both sides of the blade are nylon-coated for the purpose of improving the slipperiness as in the past, the blade becomes too hard, It was found that the drum was damaged. If the drum is damaged,
For example, in particular, when a halftone image is formed, the image becomes flawed in the traveling direction, which causes a problem that a high-quality image cannot be formed.

Therefore, an object of the present invention is to provide a good cleaning property even when a soft toner and a hard toner are used in combination, in spite of using a high-hardness blade capable of extending the life. Can be achieved, and
An image that can achieve higher durability, is more economical, and can stably form high-quality images for a long period of time without causing problems such as scratches on the drum and streaking. An object of the present invention is to provide a forming apparatus.

[0011]

The above objects can be achieved by the present invention described below. That is, the present invention
In an image forming apparatus having a carrier for carrying an image or a transfer material, and a cleaning device for removing toner powder on the carrier by a blade disposed in contact with the surface of the carrier, the blade is , Hardness (JIS-
A) The image forming apparatus is characterized in that A) is made of a material having a temperature of 70 ° or more, and a solid lubricant-containing resin layer is formed only on the side that comes into contact with the carrier.

[0012] In a preferred embodiment of the present invention, the solid lubricant-containing resin layer is formed by coating a coating liquid in which fluorinated graphite particles are dispersed in a binder resin on at least the surface of the blade contacting the carrier. And those formed by applying to portions that come into contact with the substrate. In this case, it is preferable to use nylon as the binder resin. In a preferred embodiment of the present invention, the image forming apparatus is a color image forming apparatus that forms a color image using a plurality of color toners including a color toner and a black toner. Further, there is a mode in which the toner used at that time uses a color toner having a lower softening point and a black toner uses a toner having a higher softening point. The cleaning device may be one for removing residual toner on the image carrier, or one for removing residual toner on the intermediate transfer member.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to preferred embodiments of the present invention. The present inventors have conducted intensive studies to solve the above-mentioned problems of the prior art, and as a result, in order to prolong the life of the cleaning blade, when the hardness of the material used is increased to 70 degrees or more, the slipperiness is reduced. Applying the resin coating to improve the cleaning blade not only on the entire surface of the blade as in the past but only on the surface in contact with the carrier such as the photoconductor drum can extend the life of the cleaning blade, The present invention has been found that it is possible to prevent the body from being damaged, so that a streak image as in the related art is not generated, and it is effective to achieve a longer life. That is, by using a high-hardness rubber having a high rebound resilience having a hardness of 70 degrees or more, the original life of the cleaning blade can be extended, and a resin layer containing a solid lubricant dispersed therein can be formed only on one surface of the blade. If
A sufficient effect is obtained to improve the slipperiness with the carrier, and the contact with the photosensitive drum, etc., which comes into pressure contact as compared with the conventional case where both sides are coated with nylon, can be softened. It has been found that the cleaning blade can be made to last longer in a good state because the image quality is not impaired due to the suppression of image sticking.

An image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a part of a cleaning device as an example of the image forming apparatus of the present invention. That is, FIG. 1 shows the cleaning device (cleaning unit 4a) in a state in which the cleaning device is in contact with a photosensitive drum as an image carrier. In FIG. 1, reference numeral 4a1 denotes a cleaning blade made of urethane rubber having a hardness of 70 or more, which is an elastic blade having a thickness of 2 mm and a free length (that is, the length of the blade; the length of the rubber 4a1 protruding from the sheet metal 4a2) of 8 mm. The blade is pressed against the photosensitive drum 3a with a load of 1200 g by a spring (not shown). The urethane rubber blade is attached to the mounting plate 4a with an adhesive.
2 attached. Therefore, when exchanging the cleaning blade, the sheet metal 4a2 is removed and exchanged.

Further, as shown in FIG. 1, the mounting plate 4a2 to which the elastic blade 4a1 having the above structure is adhered is mounted on a U-shaped plate 4a3, and the plate 4a3 further includes a cleaning unit. It is attached to the frame 4a4. As shown in FIG. 1, the mounting metal plate 4a3 is urged by a spring (not shown) in the direction of arrow 4a5 in the figure, and is brought into contact with the photosensitive drum at a pressure of 1200 g as described above. I have.

The cleaning blade 4a1 has a U-shaped sheet metal 4a3 attached to the cleaning unit frame 4a4.
Since it is attached by the shaft 4a6 at the center in the thrust direction, that is, at the center of the cleaning unit, it is attached to the photosensitive drum 3a so as to be equalizable. This structure is adopted because the axis of the photosensitive drum 3a does not completely coincide with the parallelism of the mounting of the cleaning unit 4a, so that the contact state of the tip of the blade 4a1 with the photosensitive drum is improved. It is to be able to maintain.

The blade 4a1 itself has a so-called reciprocating mechanism (not shown) that moves to the rear in FIG. The so-called untransferred toner scraped off by the cleaning blade having the above-described configuration is sent to the back in the figure by the screw 4a6 in the cleaner unit 4a and collected.

Further, the configuration of the cleaning blade will be described in detail with reference to FIG. FIG. 4 is a schematic diagram for explaining a cleaning blade constituting the image forming apparatus of the present invention, and FIG. 5 is a schematic diagram for explaining a conventional cleaning blade. Conventionally, as shown in FIG. 5, so-called nylon coats 4a51 and 4a52 are applied to both surfaces of the blade 4a1 made of an elastic material such as urethane rubber, which is in contact with the carrier. For the configuration of such a nylon coat, for example,
JP-A-5-66698, JP-A-6-11856, JP-A-6-195010, JP-A-6-34
No. 2,253, JP-A-2000-147977, and the like. For example, on a base material made of urethane rubber, first, an alcohol-soluble nylon is applied as an adhesive layer, and then, on a dispersion liquid in which fluorinated graphite powder is dispersed in a liquid material made of a binder resin such as nylon. The nylon blades 4a51 and 4a52 are formed on both sides of the cleaning blade by immersing the tip of the cleaning blade in contact with the carrier, dipping and drying, heating and curing the cleaning blade (see FIG. 1). (See FIG. 5).

When the nylon coat layer is formed on the surface of the cleaning blade as described above, the sliding property with the photosensitive drum is improved. In particular, when a toner having a low softening point, which is generally used for the color toner described above, is used for image formation, the binder resin constituting the toner is applied to the photosensitive drum, so that the residual The frictional force with the cleaning blade for scraping off the toner increases, and the cleaning blade is turned up. For this reason, especially in an image forming apparatus using a color toner, a nylon coat for the cleaning blade is indispensable.

In the present invention, a material having a hardness of 70 or more measured in accordance with JIS-A is used as the base material of the cleaning blade, and as shown in FIG. It is characterized in that a lubricant-containing resin layer 4a31 is formed. As the solid lubricant, fluorinated graphite can be used as in the conventional case. Examples of the fluorinated graphite that can be used include, for example, Cefbon DM (manufactured by Central Glass Co., Ltd.) of the (C ₂ F) _n type, and (CF) _n
Molds Cefbon CMA, Cefbon CMF (manufactured by Central Glass), Fluorocarbon # 2065, # 1030, # 1
000 (manufactured by Asahi Glass Company), CF-100 (manufactured by Nippon Carbon), and (CF) _n type fluorocarbon # 2028, # 2010 (manufactured by Asahi Glass Company) with a different fluorination ratio,-(CH ₂ C
PVDF represented by F ₂ ) _n − (polyvinylidene fluoride,
Examples thereof include those obtained by treating the above fluorinated graphite with a base such as an amine to remove fluorine on the surface, and the like, but are not limited thereto. In addition, the average particle size of the fluorinated graphite used in the present invention is 20 to prevent the toner cleaning performance from being impaired.
It is preferable to use those having a diameter of not more than μm, particularly in the range of 1 μm to 8 μm.

The binder resin necessary to hold these solid lubricants on the surface of the cleaning blade includes:
It is preferable to use nylon as in the conventional case. As the nylon used at this time, a solid lubricant such as fluorinated graphite can be held in a uniform state on the surface of the cleaning blade, and the cleaning blade is pressed against the surface of a carrier such as a photosensitive drum and transferred. When the residual toner is scraped off, the solid lubricant does not fall off and the resin layer does not peel off, and further, the coating property that the solid lubricant-containing resin layer can be easily formed on a part of the cleaning blade Any good one may be used. For example, this coating agent is preferably soluble in a solvent from the viewpoint of simplicity of production, and commercially available platamide M
1276, M995 (Plate Bonn), CM40
00 (manufactured by Toray Industries) or crosslinkable torenzin F3
0, MF30, EF30T (manufactured by Teikoku Chemical Industry Co., Ltd.) and the like are preferably used.

The thickness of the solid lubricant-containing resin layer formed of the above-mentioned material is 10 to 35 μm, preferably 1 to 35 μm.
It is about 7 μm ± 3 μm. This is because, if the thickness of the resin layer is too small, the purpose of imparting the sliding property to the cleaning blade by the solid lubricant cannot be achieved. In particular, in a nylon coat to which 15% by weight of a fluorinated graphite as a solid lubricant is added, the thickness is preferably 10 μm or more. The content of the fluorinated graphite in the binder resin is limited to about 20% by weight in view of the ability to form a film, and from this point, the nylon coat is made thinner and worse. It is not possible to add a large amount of fluorinated graphite in order to ensure slipperiness.
It cannot be smaller than μm. On the other hand, the thickness of the resin layer is 35 μm
Exceeding the range is not preferred because the coating becomes unstable, causing cracks, poor drying and the like.

As disclosed in the above-mentioned publications and the like, it is conventionally known to coat the surface of a cleaning blade with nylon. However, although there is a description that one side of the cleaning blade can be coated on the manufacturing method, the rebound resilience is increased by using a hard material having a hardness of 70 degrees or more as in the configuration of the cleaning blade used in the present invention. In a system in which the life of the cleaning blade can be sufficiently extended, it is not known to apply a coating to only one surface of the cleaning blade when the cleaning blade is coated with nylon. Further, with the above configuration, the blade can be prevented from being too hard. As a result, even when a soft toner using a binder resin having a low softening point, which is particularly necessary for forming a color image, is used, the transfer residual toner can be used. No remarkable effect that good cleaning can be performed and the life of the cleaning blade can be prolonged is not known. In particular, the cause of the streak image is that the nylon coat formed on the surface of the hard cleaning blade having a hardness of 70 degrees or more is too hard, and when this comes into contact, the carrier is damaged and the image quality is deteriorated. By making the portion on one side of the cleaning blade, the contact between the carrier and the cleaning blade can be softened, and the effect of solving the above problem is novel.

The above-mentioned effects are particularly obtained by using toners of a plurality of colors, which will be described later, for example, Y (yellow), M
When used in a four-drum type image forming apparatus having (magenta), C (cyan) and Bk (black) image forming units, a remarkable effect is obtained. Of course, the effect is not limited to this, and the above-described effect can be obtained with a conventionally known image forming apparatus such as a one-drum type having one image forming unit. However, the effect of the present invention is better with a four-drum type image forming apparatus. large. This is because the frictional force between the photosensitive drum and the cleaning blade tends to increase in the four-drum type image forming apparatus,
This is because the blade life tends to be shortened.

That is, in the four-drum type image forming apparatus, for example, when a character original of only black is used, Y, M,
Since a white image is formed in each image forming section C, the frictional force of the cleaning blade with the photosensitive drum increases. On the other hand, if the surface of the cleaning blade is coated with nylon, the sliding property of the cleaning blade with respect to the carrier such as the photosensitive drum can be improved, so that an increase in frictional force can be avoided. According to the study of the present inventors, the cleaning property of the cleaning blade can be improved even by a single-side coating on the side contacting the carrier, and the increase in frictional force can be sufficiently suppressed. In this case, the cleaning blade does not become too hard unlike the case where both sides are coated while the nylon coat is being applied, so that the carrier is not damaged. On the other hand, there is an idea that both sides are coated with nylon at a medium hardness, for example, a hardness of about 67 degrees. But,
According to the study of the present inventors, in such a configuration, it is difficult to achieve both long life and suppression of generation of scratches generated on the carrier,
From the viewpoint of prolonging the service life, it has been found that the configuration of the present invention in which a material having a hardness of 70 degrees or more is used, and a single-sided coating for forming the solid lubricant-containing resin layer only on the side in contact with the carrier is optimal. Was.

Next, an image forming apparatus of the present invention having the cleaning blade having the above-described configuration will be described. First, a multi-transfer type image forming apparatus will be described. However, the image forming apparatus is the same as the conventional multi-transfer type image forming apparatus except that the above-described cleaning blade is used.
FIG. 2 shows an example of a conventionally known four-drum image forming apparatus of the multiple transfer system. In such an apparatus, for example, four image forming units of Y, M, C, and Bk (black) are provided, and in these image forming units, the electrostatic latent images on the photosensitive drums are respectively formed of toners having different colors. (Developer) to form toner images as visible images, transfer these toner images sequentially onto the same transfer material (paper, etc.), and then fix to form a color image Is done.

In FIG. 2, 3a, 3b, 3c and 3d
Shows four photoreceptor drums, which are rotatable, and have their chargers 2a, 2b,
2c and 2d, potential sensors 113a, 113b, 11
3c and 113d, developing units 1a, 1b, 1c and 1d,
Transfer chargers 24a, 24b, 24c and 24d are provided, and each constitutes an image forming unit. Further, cleaners 4a, 4b, 4c and 4d are provided in contact with the respective photosensitive drums 3a, 3b, 3c and 3d. In the image forming apparatus of the present invention, these cleaners are A cleaning device having a configuration as shown in FIG. 1 is used. At this time, all four are shown in FIG.
Although it is preferable to use the cleaning device having the configuration described in (1), it is preferable to use the cleaning device at least in the image forming portion cleaner for the color toner in which a binder resin having a low softening point is generally used. A light source device (not shown) and a polygon mirror 117 are further provided above the image forming unit.

In the above-mentioned image forming apparatus, an image is formed as follows. Photoconductor drums 3a, 3b, 3c and 3d as image carriers are provided with chargers 2a, 2d,
After being charged to a predetermined potential at b, 2c and 2d, laser light emitted from the light source device is scanned by rotating the polygon mirror 117, and the light beam of the scanning light is deflected by the reflection mirror, and fθ (not shown) Photosensitive drum 3 by lens
By condensing and exposing on the generating lines a, 3b, 3c and 3d, an electrostatic latent image corresponding to the image signal is formed on the photosensitive drums 3a, 3b, 3c and 3d.

In the developing devices 1a, 1b, 1c and 1d, a two-component developer composed of a carrier and a toner is stored as a developer. In the apparatus shown in FIG. , Cyan, magenta, yellow, and black toners are filled by a supply unit (not shown) in a predetermined amount. The carrier constituting the developer is a magnetic material made of ferrite or the like, and has a particle size of about 35 microns.

In the present invention, the toner constituting the developer includes, for example, a binder resin composed of a low-melting polyester having excellent sharp-melt properties, a toner particle composed of a colorant of each color, and a toner. In order to impart electric charge and fluidity to the toner particles, it is preferable to use one comprising about 1% by weight of alumina externally attached to the surface of the toner particles and 0.3% by weight of titanium oxide as an external additive.

In the developing units 1a, 1b, 1c and 1d described above, the respective photosensitive drums 3a, 3b, 3c
And the electrostatic latent images on 3d are developed and visualized as cyan, magenta, yellow, and black toner images. The recording material P is a recording material cassette 1
The transfer belt 65 is supplied to the transfer belt 1 via the registration roller 12 through the transfer path 65 by a plurality of transfer rollers, and is conveyed by the transfer belt 1 to face the photosensitive drums 3a, 3b, 3c and 3d. Are sequentially sent to the transferred transfer unit.

The transfer belt 1 is made of a dielectric resin sheet such as polyimide, polyethylene terephthalate (PET), polyvinylidene fluoride and polyurethane.
An endless shape or a seamless belt having no seams is used. The volume resistance of such a transfer belt is generally 10 ¹³ to 10 ¹⁸ Ωcm. In the apparatus shown in FIG. 2, a polyimide resin sheet was used.

Now, the driving roller 13 and the stretching roller 15
The transfer belt 1 supported by is rotated by the driving of the drive roller 13 and when it is confirmed that the transfer belt 1 is at a predetermined position, the recording material P is sent out from the registration roller 12 to the transfer belt 1, and the recording material P is The first image forming unit Pa is transported toward the transfer unit. In synchronization with this, the photosensitive drum is uniformly negatively charged by the primary charger. Further, the image writing signal is turned on, and an image is formed on the photosensitive drum 3a of the first image forming unit (hereinafter, first station) Pa at a certain timing based on the signal.

In the developing section 9, the developing sleeve rotates, the developer is supplied to the photosensitive drum, and a developing bias is applied. In the apparatus shown in FIG. 2, when the primary charge is about -700 V, the developing bias is AC 2 kV _pp , D
C-550V. In this case, the absolute value 150 V of the difference between the primary charging and the developing bias is called a buoy-back, but is a so-called fogging potential.

The laser irradiation on the photosensitive drum is performed by a digital signal. At 00h, the laser is almost off, and no toner is loaded on the photosensitive drum. When a high signal of FFh is applied to the laser, the laser is fully lit at this time, the potential of the photosensitive drum approaches 0 V, and so-called solid development in which a large amount of toner is applied.
In the middle, for example, at 20h or 30h, the laser is turned on at a medium level, and the toner is thinly loaded on the photosensitive drum.

Subsequently, the transfer charger 24a applies an electric field or electric charge at a transfer portion below the photosensitive drum 3a, so that the first color toner image formed on the photosensitive drum 3a is formed on the recording material P. Transcribed above. By this transfer, the recording material P is firmly held on the transfer belt 1 by electrostatic attraction, and is conveyed to the second image forming unit (hereinafter, second station) Pb and thereafter. Further, instead of electrostatically adsorbing the recording material P onto the transfer belt 1 at the same time as the transfer, an adsorption charger 5 may be provided before the transfer. As the attraction charger, a non-contact charger such as a corona discharge or a contact charger using a charging member such as a blade, a roller, or a brush is used.

Similarly, a non-contact charger such as a corona discharge or a contact charger using a transfer charger such as a blade, a roller, or a brush is used as the transfer charger 24. The non-contact charging device has problems such as generation of ozone, and susceptibility to fluctuations in the temperature and humidity environment of the atmosphere due to charging through air, resulting in unstable image formation. On the other hand, the contact charger has advantages such as ozonelessness, resistance to environmental changes in temperature and humidity, and high image quality. In addition, static elimination needles 7a, 7b, 7c and 7d may be provided in order to stabilize transferability. These static elimination needles are in non-contact with the transfer belt 1, but play a role of discharging a part of the transfer current to escape. With this configuration, it is possible to prevent the toner image from being disturbed due to the peeling discharge when the photosensitive drum and the recording paper are peeled.

Image formation and transfer in the second to fourth image forming units (second to fourth stations) Pb to Pd are performed in the same manner as in the first station Pa. Next, the recording material P to which the four color toner images have been transferred is separated from the end of the transfer belt 1 by removing the charge by the separation charger 32 at the downstream portion of the transfer belt 1 in the transport direction and attenuating the electrostatic attraction force. . In particular, in a low humidity environment, the recording material also dries and the electric resistance increases, so that the electrostatic attraction force with the transfer belt increases, and a separate charger is required. Usually, a non-contact charging device is used for the separation charging device because the recording material P is charged in a state where the toner image is not fixed. The detached recording material P is supported by the guide member 64, and further transported to the fixing device 9 by the transport unit 62.

The fixing device 9 includes a fixing roller 51, a pressure roller 52, heat-resistant cleaning members 54 and 55 for cleaning them, roller heaters 56 and 57 installed in the rollers 51 and 52, and a fixing roller. An application roller 50 for applying a release agent oil such as dimethyl silicone oil to 51, an oil storage tray 53 for storing the oil, and a thermistor 58 for detecting the temperature of the surface of the pressure roller 52 and controlling the fixing temperature. It is composed of
In the fixing device shown in FIG. 2, by a conventionally known measuring method,
About 20 mg of oil is applied from the application roller 50 per A4 sheet.

The recording material P to which the four color toner images have been transferred is
By the fixing by the fixing device 9, the color mixture of the toner image and the fixation to the recording material P are performed, a full-color copy image is formed, and the image is discharged to the paper discharge tray 63.

The photoreceptor drums 3a, 3b, to which the transfer has been completed,
3c and 3d clean and remove the transfer residual toner by the respective photosensitive drum cleaners 4a, 4b, 4c and 4d, and then prepare for the next process of forming an electrostatic latent image. The toner and other stains remaining on the transfer belt 1 are removed by a cleaning blade 8a made of urethane rubber which is in contact with the transfer belt 1, and is collected in a collection container 8b. Further, the transfer belt 1 after the cleaning is used to remove the residual charges on the surface thereof by the charge removing rollers 21 and 22 to prepare for the next transfer step.

It is known that the transfer charging means 24 stabilizes an image when the current contributing at the time of transfer is fixed at an appropriate current. Therefore, it is general to perform constant current control so that a constant current can be obtained even when the volume resistance value changes depending on the type (thickness, material, etc.) of the recording material, moisture absorption conditions, and the like.

In the single-sided printing process, the recording material cassette 1
The toner image is transferred and fixed to the recording material P conveyed from 0, and is immediately discharged to the discharge tray 63. On the other hand, in the double-sided printing process, the recording material P, which has been fixed in the single-sided printing process, is sent to the conveyance path 67 without being discharged, switched back, sent to the double-sided conveyance path 66, and then transferred again via the conveyance path 65. It is transported on the belt 1. At this time, the surface of the recording material P on which the toner image has been fixed is placed in contact with the transfer belt 1, and thereafter, the toner image is transferred and fixed to the back surface of the recording material P and discharged in the same manner as in the single-sided printing process. . Since the recording material P comes into contact with the fixing roller 51 on which the fixing oil is applied at the time of fixing on one side, the fixing oil adheres to the surface of the recording material P. For this reason, the fixing oil is transferred to the transfer belt 1 from the recording material P placed on the transfer belt 1 during the transfer to the back surface, and the fixing oil adheres to the transfer belt 1. When paper is used as the recording material, the fixing oil adhering to the white background where there is no toner image on the paper is almost absorbed into the paper, and the amount of oil remaining on the paper surface is small. However, in a portion where the toner image is present, a part of the adhered oil is absorbed by the toner image, but most of the oil remains on the surface of the toner image. Accordingly, the area occupied by the toner image is high, and the higher the density of the image, the more the amount of oil adhering to the transfer belt 1 tends to increase.

Next, using an intermediate transfer member, which is another embodiment of the image forming apparatus of the present invention, the image transfer member once formed on each image forming portion as described above is formed on the intermediate transfer member. An image forming apparatus of the present invention having an intermediate structure for forming an image in which toner images of the respective colors are superimposed and transferring the toner images collectively to a transfer material will be described with reference to FIG. The device shown in FIG. 3 has intermediate configurations, for example, Y, M, C and Bk.
This is an example of a four-drum image forming apparatus capable of forming an image of four colors (black).

In the image forming apparatus having the intermediate structure shown in FIG. 3, the intermediate transfer member 140 as a carrier is made of a polyimide resin like the transfer belt 1 in the multiple transfer type image forming apparatus shown in FIG. An endless belt body made of a material such as the one described above is configured to rotate in the direction of the arrow in the figure. In the same manner as described above, each photosensitive drum 3
a, 3b, 3c and 3d, the four color toner images formed on the primary transfer charging units 24a, 24b, 24c and 24
d, the images are sequentially transferred onto the intermediate transfer member 140 in a superimposed manner, and then the secondary transfer position 70 is
Transported to The recording material P conveyed from the recording material cassette 10 is sent to the secondary transfer position 70 in synchronization with the movement of the toner image on the intermediate transfer member, and contacts the recording material P with the toner image at the same time as the secondary transfer. A transfer bias is applied to the charging unit 80 to transfer the toner image to the recording material P. As the secondary transfer charging unit 80, a transfer roller made of conductive or semiconductive rubber was used. After the transfer, the toner image on the recording material P is fixed on the recording material P via the transport unit 62 and the fixing device 9. At the time of double-sided printing, the recording material P on which one side has been fixed is sent again to the secondary transfer position 70 via the conveyance paths 67 and 66, and the toner image is transferred to the back surface of the recording material.

In this configuration, the secondary transfer means 80
Since the recording material P is in contact with the recording material P to which the fixing oil has adhered, the fixing oil adheres to the surface of the secondary transfer unit 80. Further, the fog toner on the intermediate transfer member is transferred to the secondary transfer unit 80 because the secondary transfer unit 80 contacts the intermediate transfer member 140. Therefore, in order to remove oil and fogging toner attached to the secondary transfer means, the cleaning blade 8
1 is in contact.

Further, in order to remove the transfer residual toner remaining on the intermediate transfer member 140 after the secondary transfer, the intermediate transfer member 14 is removed.
The cleaning blade 90 is in contact with 0. In an apparatus having such an intermediate structure, it is necessary to reliably clean the intermediate belt between the images. In particular, in the transfer belt in the multiplex type image forming apparatus described above, an appropriate transfer belt cleaning is necessary. On the contrary, it is necessary to more reliably clean the belt or the transfer means. This is because, in the image forming apparatus having the intermediate structure, if the toner of the previous image remains on the transfer belt 140 or the transfer unit 80 during the next image formation, the next image becomes dirty. On the other hand, in the multiplex type image forming apparatus, the performance of the multiplex type image forming apparatus is not strictly required as compared with the intermediate type.

In the cleaning of the transfer belt 140 and / or the transfer means 80 as an intermediate transfer body of such an intermediate, strict contact conditions are particularly required. More specifically, since the pressure of the cleaning blade on the intermediate body is high and the contact angle θ is steep (for example, the contact angle θ with the transfer belt 140 is 35 degrees), the cleaning blade for the intermediate body and the intermediate body The frictional force between the belt and the belt easily rises. In the present invention, such a cleaning blade has a hardness of 70 used in the present invention described above.
As described above, a cleaning blade using an elastic material having high hardness and high rebound resilience and having a solid lubricant-containing resin layer formed on one surface thereof is employed. As a result, the contact between the intermediate transfer member and the cleaning blade is soft, even though the material is of high hardness, so that the frictional force is reduced and the intermediate transfer member is not damaged, so that the cleaning is performed in a good condition. Can be.

As described above, the image forming apparatus of the present invention includes a blade-type cleaning device for supporting an image or a transfer material on a carrier and removing transfer toner powder remaining on the carrier. The blade has a hardness of 70 degrees (JIS-A) or more,
Further, by using a blade having a solid lubricant-containing resin layer formed only on the surface on the side of the carrier, even in the case of using a soft toner having a low softening point, cleaning can be performed in a good state and an image can be formed. A cleaning device that achieves a longer life without loss of quality is obtained.

[0050]

The present invention will be described below in more detail with reference to examples and conventional examples. <Embodiment 1> Embodiment 1 provides an image forming apparatus of the multiple transfer system shown in FIG. 2 having a cleaning blade having the structure shown in FIG. The cleaning blade used in the present embodiment uses a base rubber made of urethane rubber having a hardness of 78 degrees and a rebound resilience of 39, and a solid lubricant is applied only to the surface used by the base rubber, that is, the surface in contact with the photosensitive drum. The containing resin layer was formed. The formation of the solid lubricant-containing resin layer was performed as follows. First, alcohol-soluble nylon (a commercially available product) was applied to the surface of the base rubber that was in contact with the photosensitive drum to form an adhesive layer. A dispersion of 15% by weight of fluorinated graphite powder Cefbon-DM (trade name, manufactured by Central Glass Co., Ltd., average particle size: 3 μm) is applied to liquid nylon platamide M995 (trade name) prepared in advance. Then, by drying, heating and curing, a cleaning blade for an image carrier of this embodiment having a nylon coat layer formed on one surface was formed. As a coating method at this time, a spray method was used.

The cleaning blade of the present embodiment obtained above is used as a cleaning blade for an image carrier of a multi-transfer type full-color image forming apparatus shown in FIG. 2, and a polyester resin is used for each color pigment in the apparatus. An image was formed using a sharp-melt toner colored by the above method, and a durability test was performed. As a result, the life was extended to 100 km or more. Here, the term "life" refers to a point in time when the edge of the blade is chipped and the toner slips out of the edge.
On the other hand, when the photoreceptor drum was observed after the durability test, it was found that there was almost no scratch and no streak image was generated as in the related art. This is because the original life of the cleaning blade has been extended by using high rebound resilience and high hardness rubber.In addition, the nylon blade has only one side, so the cleaning blade hits the drum. It is considered that the drum was softened, and as a result, the drum was not damaged and the drum lasted longer.

On the other hand, lowering the hardness of the rubber, which is the base material, tends to cause chipping of the blade edge.
This leads to a shorter life of the cleaning blade.
In the cleaning blade of the present embodiment having the above configuration,
Long life with high rebound resilience while keeping base rubber hardness as high as 78.Nylon coating on one side makes it softer than nylon coating on both sides. However, an effect is obtained in which the image carrier of the contacting partner is not damaged while maintaining good cleaning properties.

<Comparative Example 1> An adhesive layer was formed on both surfaces of a base rubber made of urethane rubber having a blade hardness of 62 degrees and a rebound resilience of 9, using the same material as in Example 1. Using the same dispersion as used, dipping was applied, and similarly, drying, heating and curing were performed to apply nylon coat on both surfaces. Using the obtained cleaning blade, a durability test was performed in the same manner as in Example 1. As a result, the life was about 60 km. At this time, chipping of the blade edge occurred, and cleaning failure occurred.

<Embodiment 2> In the same multi-transfer type image forming apparatus as used in Embodiment 1, in the measurement of the softening point of the toner described above, a soft color toner of T1 = 110 ° C. and ΔT = 15 ° C. And a hard black toner having T1 = 160 ° C. and ΔT = 25 ° C. were used in combination. In the present embodiment, a cleaning blade for a photosensitive drum having a nylon coating on one surface was used in the same manner as in Embodiment 1, using a urethane base rubber having a hardness of 82 degrees and a rebound resilience of 35. A durability test was performed in the same manner as in Example 1. As a result, in the present example, the black color, which is advantageous in cleaning property, was also obtained while maintaining the cleaning property of a soft color toner having a low softening point. The cleaning of the toner can be performed, and the life is 100% as in the first embodiment.
km or more, and good cleaning properties and a long service life could be achieved.

<Embodiment 3 and Comparative Example 2> This embodiment is directed to a cleaning blade for an intermediate transfer member of a four-drum image forming apparatus having an intermediate structure shown in FIG. A cleaning blade is applied. That is, in the present embodiment, the intermediate transfer member 140 made of an endless belt made of a polyimide resin was used as the intermediate transfer member as the carrier. In this embodiment, in order to remove the transfer residual toner remaining on the intermediate transfer member 140, the one in which the cleaning blade 90 is in contact with the intermediate transfer member 140 is used. In the present embodiment, a high hardness and high rebound resilience base rubber, the same as that used in the first embodiment, was used as the cleaning blade, and a blade coated on one side with nylon was used.

On the other hand, a cleaning blade having the same low hardness and low rebound resilience as that used in the cleaning blade for the photosensitive drum in Comparative Example 1 and having nylon coating on both surfaces was used. Comparative Example 2 was a cleaning blade for an intermediate transfer member of the apparatus shown in FIG.

Each of the cleaning blades obtained above was cleaned in the same manner as in Example 1 with an image apparatus in which the cleaning blade was applied to an intermediate transfer member. Then, under the same conditions as in Examples 1 and 2, an image endurance test was performed, respectively. As a result, compared to the apparatus of Comparative Example 2 in which cleaning is performed using a low-hardness, low-rebound resilience base rubber and a blade coated on both sides with nylon,
In the apparatus of Example 3, the life was doubled or more, the chipping of the blade edge and the rubbing of the toner, that is, the image contamination did not occur, and it was possible to perform the cleaning satisfactorily for a long period of time.

<Example 4> Further, a cleaning blade similar to that used in Example 2 was used as a cleaning blade for an intermediate transfer member of a four-drum image forming apparatus having an intermediate structure similar to that used in Example 3. When a durability test was performed using the same toner as used in Example 2, good results were obtained as in Example 3.

[0059]

As described above, according to the present invention, according to the present invention, an image provided with a blade type cleaning device for removing residual toner powder on a carrier for carrying an image or a transfer material on the carrier. Regardless of whether a sharp melt toner is used in the forming apparatus or a combination of toners having different softening points is used, the life of the cleaning blade can be prolonged, and the partner with which the cleaning blade comes into contact can be obtained. Image formation that does not damage the image carrier or the intermediate transfer member, and does not cause deterioration in image quality such as streak images, and is economical, and can stably form high-quality images over a long period of time. An apparatus is provided.

[Brief description of the drawings]

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

FIG. 2 is an overall sectional view of an example of the image forming apparatus of the present invention.

FIG. 3 is a partial cross-sectional view of another example of the image forming apparatus of the present invention.

FIG. 4 is a schematic view showing a cleaning blade used in a cleaning device used in the present invention.

FIG. 5 is a schematic view showing a cleaning blade used in a conventional image forming apparatus, in which nylon coating is applied to both sides of the cleaning blade.

[Explanation of symbols]

 1: Transfer belt 4a1: Cleaning blade 8a: Cleaning blade 9: Fixing device 24a, 24b, 24c, 24d: Transfer charging unit 64: Guide member 140: Intermediate transfer member 80: Secondary transfer unit 81: Cleaning blade 90: Cleaning blade

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G03G 15/01 C10N 20:06 Z 15/16 40:06 // C10N 20:06 50:02 40:06 50:08 50:02 G03G 21/00 318 50:08 9/08 361 F term (reference) 2H005 AA21 EA03 2H030 AB02 AD01 AD03 BB02 BB42 BB44 2H032 BA05 BA09 BA18 BA30 2H034 AA07 BF01 BF03 BF05 BF06 4H104 AA05A CE13CEA EA08 QA08A

Claims (7)

[Claims] 1. An image forming apparatus comprising: a carrier for carrying an image or a transfer material; and a cleaning device for removing toner powder on the carrier by a blade disposed in contact with the surface of the carrier. In the above blade,
An image forming apparatus comprising a material having a hardness (JIS-A) of 70 degrees or more, and a solid lubricant-containing resin layer formed only on a side in contact with a carrier. 2. A solid lubricant-containing resin layer is provided with a coating liquid in which fluorinated graphite particles are dispersed in a binder resin, at least at a portion of the blade contacting the carrier, at least in a portion contacting the carrier. The image forming apparatus according to claim 1, wherein the image forming apparatus is formed by coating. 3. The image forming apparatus according to claim 2, wherein the binder resin is nylon. 4. The image forming apparatus according to claim 1, wherein the image forming apparatus is a color image forming apparatus that forms a color image using a plurality of color toners including a color toner and a black toner. 5. The image forming apparatus according to claim 4, wherein the toner is a combination of a color toner having a low softening point and a black toner having a high softening point. 6. The image forming apparatus according to claim 1, wherein the cleaning device is a cleaning device for an image carrier. 7. The image forming apparatus according to claim 1, wherein the cleaning device is a cleaning device for an intermediate transfer member.