JP2001290404A - Cleaning blade, cleaning device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning blade which is prevented from being turned up even when a doctor type blade is used under high temperature environment in the case of removing residual toner on the surface of a photoreceptor, and to provide a cleaning device and an image forming device provided with the blade. SOLUTION: After toner image formed on a photoreceptor drum 1 is successively electrostatically transferred to an intermediate transfer body 5, is is transferred to paper P and fixed simultaneously in this image forming device, which is provided with the cleaning blade 17 removing the toner remaining on the surface of the drum 1 after transferring the toner image. The blade 17 is supported to press-contact with the surface of the drum 1, and is formed of urethane rubber whose peak temperature at tangent loss tanδ(=G"/G') when a complex elastic modulus showing the delay of distortion at the time of giving sine-wave vibration is set as G=G'+iG' is >=10 deg.C and <=30 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning blade, a cleaning device, and a cleaning device for removing a toner remaining on the surface of a toner image carrier after transferring a toner image on the toner image carrier to a transfer object. To an image forming apparatus such as an electrophotographic copying machine and a printer to which the invention is applied.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus widely used, for example, forms an electrostatic latent image on a photoreceptor, develops it with dry toner to form a toner image, and then electrostatically forms the toner image. The image is transferred to a recording medium, and is fixed on the recording medium by applying pressure and heat to form an image. In such an image forming apparatus, the toner remaining on the surface of the photoconductor must be removed after the toner image on the photoconductor is transferred to a recording medium.

[0003] To remove the toner remaining on the photoreceptor surface,
There are fur brushes, electrostatic brushes, magnetic brushes, webs, blades, and the like, but cleaning blades having urethane rubber at the tip are predominant in terms of space, cost, performance, and the like. Cleaning blades include
Further, there are a doctor type and a wiper type, and these failure modes include abrasion, chipping of a rubber tip, rubber curling, and wiping of a toner image due to creep.

[0004] The wiper type blade is resistant to sudden turning of the rubber, but is inferior to the doctor type in the performance of toner removal itself. In order to make the cleaning performance of the wiper type blade equal to that of the doctor type, the pressure must be increased. Therefore, an increase in the torque causes an increase in the load on the motor and wear on the surface of the photoreceptor. Further, in the wiper type, paper components adhering to the surface of the photoreceptor cannot be removed, causing image deletion or the like. For these reasons, doctor-type blades have become mainstream.

[0005]

However, the conventional doctor-type blade as described above has the following problems. Doctor-type blades
If the temperature of the environment in which it is used rises, or the temperature of the surface of the photoconductor rises by warming the photoconductor to prevent image deletion, or the temperature around the cleaning blade rises due to the image forming system, Rubber turning will occur.

Further, as an image forming method capable of achieving high image quality, an image forming apparatus of a transfer fixing method has been widely studied. This transfer fixing method is an image forming apparatus that has been widely used in the past, that is, an image forming technique in which a toner image is electrostatically transferred to a recording medium on a photosensitive member and then fixed, and the image density unevenness and transfer are reduced. This is a technique for improving the resolution and the poor dot reproducibility due to scattering of toner in an area.

In this transfer fixing method, a toner image formed on a photoreceptor is transferred to an intermediate transfer member electrostatically, or by adhesion, or both, and then the intermediate transfer member on which the toner image is placed Heat and pressure are applied in a state where the recording medium and the recording medium are in close contact with each other. Then, the toner image is melted on the surface and inside of the recording medium, and after the toner is aggregated to some extent, the recording medium is peeled off from the intermediate transfer body to obtain a fixed image on the recording medium surface.

In this transfer fixing method, since the intermediate transfer member is in contact with the surface of the photoreceptor, after the toner image on the intermediate transfer member is fixed on a recording medium, the temperature of the intermediate transfer member is reduced to a normal value.
Since the temperature cannot be reduced as compared with the case where the intermediate transfer body is used only for transfer, the temperature of the photoconductor may be increased. For this reason, there is a possibility that the cleaning blade for removing the residual toner on the surface of the photoconductor may be turned. If such rubber turning occurs, it can only be dealt with by a specialized maintenance worker, and the image forming apparatus cannot be used.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to remove a residual toner from the surface of a toner image carrier by using a doctor type cleaning blade in a high temperature environment. An object of the present invention is to provide a cleaning blade, a cleaning device, and an image forming apparatus using the same, which can prevent the occurrence of blade turning even when used.

[0010]

According to a first aspect of the present invention, there is provided a toner image bearing member having a surface in contact with a toner image bearing member, the surface of which is pressed against the toner image bearing member. A cleaning blade that removes the residual toner on the surface of the cleaning blade, where G = G ′ + iG ″, where G = G ′ + iG ”, where the complex elastic modulus showing the delay of the distortion when sine wave vibration is applied is
Provided is a cleaning blade, characterized in that at least a portion pressed against the toner image carrier is made of a urethane material having a peak temperature of tangent loss tan δ (= G ″ / G ′) of 10 ° C. or more and 30 ° C. or less. .

According to a second aspect of the present invention, there is provided a toner image carrier having a surface on which a toner image is carried,
A cleaning device for removing toner remaining on the surface of the toner image carrier after the toner image is transferred to a transfer-receiving member, comprising a cleaning blade arranged to be in pressure contact with the surface of the toner image carrier. When the complex elastic modulus indicating the delay of the strain when the sinusoidal vibration is applied is G = G ′ + iG ″, at least a portion of the cleaning blade pressed against the toner image carrier has a tangent loss tanδ. Provided is a cleaning device comprising a urethane material having a peak temperature of (= G ″ / G ′) of 10 ° C. or more and 30 ° C. or less.

According to a third aspect of the present invention, there is provided an image carrier on which a latent image is formed on the surface due to a difference in electrostatic potential, a developing device for visualizing the latent image by attaching toner, and on the image carrier. A transfer device for transferring the toner image to a recording medium or an intermediate transfer member, and removing the toner remaining on the surface of the image carrier after the toner image is transferred.
And a cleaning device according to (1).

According to a fourth aspect of the present invention, there is provided an image carrier having a surface on which a latent image is formed due to a difference in electrostatic potential; a developing device for visualizing the latent image by attaching toner; An intermediate transfer member on which the toner image formed on the intermediate transfer member is transferred; a transfer device for transferring the toner image on the intermediate transfer member onto a recording medium; and a transfer device on the surface of the intermediate transfer member after the toner image is transferred. An image forming apparatus comprising: the cleaning device according to claim 2 that removes the removed toner.

The present inventors have found that while the conventional urethane blade normally satisfies the clean nig performance at normal temperature or low temperature, it causes the blade to be turned up at high temperature. Think of it as change,
We focused on the peak temperature of the tangent loss tan δ, which represents the temperature characteristics of the polymer material. Therefore, various urethane materials were prototyped, and a dynamic viscoelasticity measuring device (for example, Orientec Co., Ltd. Leo Vibron Model DDV-01FP) was used.
The peak temperature of tan δ was measured at an excitation frequency of 10 Hz.

The dynamic viscoelasticity measuring device applies a small vibration to a polymer material in a sine wave, measures a delay of a strain with respect to an external force, and simultaneously measures an elastic property and a viscous property. The loss tan δ is obtained by dividing the imaginary part of the complex elastic modulus G = G ′ + iG ″, which is the proportionality constant of the delay, by the real part.
When the temperature around the toner image carrier was increased and the experiment was repeated, it was found that if the peak temperature of the tangent loss tan δ (= G ″ / G ′) was equal to or higher than a certain value, the occurrence of turning over could be prevented.

In the cleaning blade according to the first aspect of the present invention, at least a portion pressed against the toner image carrier has a peak temperature of tan δ of 10 ° C. or more and 30 ° C.
It is made of the following urethane material, and even if the temperature of the surface of the toner image carrier increases due to long-term use, it is possible to suppress the occurrence of blade turning and so-called chattering in which the blade tip shakes. For this reason, it is possible to prevent the toner remaining on the surface of the toner image carrier from being wiped off, and to maintain good cleaning performance.

In the cleaning device according to the second aspect of the present invention, the cleaning blade is disposed so as to be in pressure contact with the surface of the toner image carrier, and at least a portion of the cleaning blade that is in pressure contact with the toner image carrier is tan.
Since the peak temperature of δ is formed of a urethane material having a peak temperature of 10 ° C. or more and 30 ° C. or less, even if the temperature of the surface of the toner image carrier increases during driving of the apparatus, it suppresses the occurrence of blade turning and chattering. be able to. For this reason, it is possible to prevent the occurrence of defective cleaning such as wiping of the toner remaining on the surface of the toner image carrier.

In the image forming apparatus according to the present invention, the toner remaining on the surface of the image carrier after the toner image formed on the image carrier is transferred to a recording medium or an intermediate transfer member. Since the cleaning device according to the second aspect of the present invention is provided, even if the temperature of the surface of the image carrier rises during the operation of the device, it is possible to suppress the occurrence of turning over the blade and chattering. For this reason, it is possible to prevent the toner from being left unwiped and to maintain good cleaning performance.

In the image forming apparatus according to the present invention, after the toner image transferred on the intermediate transfer member is transferred to a recording medium, the toner remaining on the surface of the intermediate transfer member is removed. Since the cleaning device according to the second aspect is provided, even if the temperature of the surface of the intermediate transfer member increases during the operation of the device, it is possible to suppress the occurrence of turning over the blade and chattering. For this reason, it is possible to prevent the toner from being left unwiped and to maintain good cleaning performance.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an image forming apparatus according to an embodiment of the present invention. The image forming apparatus includes an endless belt-shaped intermediate transfer member 5 whose peripheral surface is rotatably supported, and is provided at a position facing the intermediate transfer member 5 for each color of cyan, magenta, yellow, and black. Four independent image forming units 10C, 10M, 10Y, and 10K are provided.
Each image forming unit 10C, 10M, 10Y, 10K
Has a photosensitive drum 1 on the surface of which an electrostatic latent image is formed, and a charging device 2 around each photosensitive drum 1 for charging the surface of the photosensitive drum almost uniformly, An optical scanning device 3 for writing an electrostatic latent image by irradiating a laser beam on the surface of the body drum, and a developing device 4 for selectively transferring toner to a latent image formed on the photosensitive drum to form a toner image; ,
The image forming apparatus includes a transfer charger 6 that primarily transfers a toner image on the photosensitive drum 1 to the intermediate transfer body 5 and a cleaning device 7 that removes toner remaining on the surface of the photosensitive drum 1.

The intermediate transfer member 5 includes a belt driving roll 1
1, a support roll 12, a heating roll 8, a paper peeling roll 13, and a cleaning roll 14, and the rotation of the belt drive roll 11 causes the intermediate transfer body 5 to move in the direction of the arrow shown in the figure. It has become.

A pressure roll 9 is disposed at a position facing the heating roll 8 via the intermediate transfer member 5.
Further, the heating roll 8 in the circumferential direction of the intermediate transfer body 5
A cooling device 15 for cooling the toner image on the intermediate transfer member is provided along the back surface side of the intermediate transfer member 5.

The photosensitive drum 1 has an S surface on the drum surface.
Those having various inorganic photoreceptor layers such as e, a-Si, a-SiC and CdS, and those having various organic photoreceptor layers can be used.

The intermediate transfer member 5 uses a belt-shaped member having a three-layer structure of a base layer and an adhesive layer or a primer layer and a surface layer. The base material of the belt considered as the intermediate transfer member is polyimide, polyetheretherketone (PEEK),
Polyarylene sulfide (PAS), polyimide amide,
Polyether sulfone (PES), polyether nitrile
(PEN), thermoplastic polyimide, etc., but polyimide is often used due to requirements of heat resistance and mechanical strength. In this embodiment, the carbon black-added thickness of 40 μm is used.
In order to electrostatically transfer the toner image from the photosensitive drum 1 to the intermediate transfer member 5 without disturbing the image using a polyimide film having a thickness of 100 μm to 100 μm, the volume resistivity of the base layer is changed by changing the addition amount of carbon black. From 10 ⁸ Ωcm to 10
^It was adjusted to ¹² Ωcm.

The surface layer has a volume resistivity of 10 ¹² Ωcm to 10 ¹⁵ Ωcm in order to electrostatically transfer the toner image from the photosensitive drum 1 to the intermediate transfer member 5 without image disturbance. . Further, when fixing is performed simultaneously with the transfer from the intermediate transfer body 5 to the paper, the adhesion between the intermediate transfer body and the paper is improved with the toner image interposed therebetween, and the rubber hardness is taken into consideration in consideration of the releasing property and heat resistance of the toner. 10 to 70 degrees, thickness 10μm
To 100 μm of silicone rubber was coated on the surface of the intermediate transfer member.

The cleaning device 7 is an embodiment of the second aspect of the present invention, and includes a cleaning blade 17 pressed against the photosensitive drum 1. This cleaning blade 17 is also one embodiment of the invention described in claim 1. When the cleaning blade 17 is pressed against the surface of the photosensitive drum 1, toner remaining on the surface of the photosensitive drum is scraped off.
The cleaning blade 17 has a tangent loss tan δ (=
G ″ / G ′) is formed of urethane rubber having a peak temperature of 10 ° C. or more and 30 ° C. or less, and is fixedly supported by the cleaning device main body by a metal supporting member.

The heating roll 8 and the pressure roll 9 may be a metal roll or a metal roll provided with a heat-resistant elastic layer such as silicone rubber on the metal roll.
A heat source is disposed inside the heating roll 8, and its heating temperature is set and controlled so that the toner temperature in the heating area is equal to or higher than the toner melting temperature (Tm). A heat source is also arranged inside the pressure roll 9. Further, the heating temperature is set so that the photosensitive drum 1 and the toner image and the paper P are sufficiently adhered to each other in the heating area, so that partial floating does not occur, and wrinkles and deviations do not occur on the paper P. You. The nip pressure is 1 × 10 ⁵ P for the toner used this time.
The range of a to 1 × 10 ⁶ Pa was appropriate.

In the present embodiment, the heating roll 8 and the pressure roll 9 are each formed by laminating a silicone rubber having a hardness of 55 to a thickness of 3 mm on a hollow aluminum roll. A halogen lamp was used. The nip pressure was set to 5.5 × 10 ⁵ Pa. In addition, in the above configuration, the pressure roll 9 is disposed so as to face the heating roll 8, but the heating roll 8 and the pressure roll 9 may be disposed in reverse. The presence or absence of a heat source inside the pressure roll 9 can also be set as appropriate.

The color toner is composed of a thermoplastic binder containing dyes such as yellow, magenta and cyan.
Known materials can be used. The amount of each color toner on the paper is approximately 0.4 mg depending on the content of the dye.
/ Cm ² to 0.7 mg / cm ² , the exposure conditions or development conditions are set. In the present embodiment, each color is set to 0.65 mg / cm ² .

Next, the operation of the image forming apparatus will be described. Four image forming units 10C, 10M, 10Y, and 10K are arranged around the intermediate transfer body 5,
In each image forming unit, the photosensitive drum 1 is almost uniformly charged by the charging device 2 and then exposed by the optical scanning device 3 which is turned on / off by the light beam pulse width modulation device based on the density signal, and is electrostatically charged. A latent image is formed. The electrostatic latent image on each photoconductor drum 1 is developed by a developing device 4 containing cyan, magenta, yellow, and black toners. Photoconductor drum 1
Formed on top. These color toner images are sequentially transferred onto the intermediate transfer body 5 by the transfer charger 6 in a superimposed manner, and a toner image in which a plurality of colors are superimposed on the intermediate transfer body 5 is formed. The plurality of color toner images formed on the intermediate transfer member 5 are heated and melted when the intermediate transfer member 5 passes through a position where the intermediate transfer member 5 contacts the heating roll 8.

On the other hand, the pressure roll 9
Is pressed against the heating roll 8. Thereafter, the intermediate transfer body 5 holding the plurality of color toner images and the paper P are moved between the heating roll 8 and the pressure roll 9 at the same time, and are pressed and heated. The toner heated above the melting temperature softens and melts, and permeates the paper P.

The sheet P in which the toner image has penetrated is cooled by the cooling device 15 before reaching the sheet peeling roll 13. This toner image is coagulated and solidified by being cooled below the melting temperature, and a strong adhesive force is generated between the toner image and the paper P. Therefore, at the position where the sheet peeling roll 13 having a small radius of curvature is disposed, the sheet P is separated from the intermediate transfer body 5 together with the toner by the stiffness of the sheet itself, and a color image is formed.

The temperature of the surface of the intermediate transfer member after the sheet P is peeled is in the range of 60 ° C. to 90 ° C. The surface of the intermediate transfer member after the sheet P has been peeled off is cleaned by the cleaning roll 14 on the downstream side in the circumferential direction, and the process starts again to transfer the toner image from the photosensitive drum 1. The surface of the cleaning roll 14 is covered with a thermoplastic resin, and is heated by an internal heat source to cause the surface of the cleaning roll to exhibit adhesiveness.
This removes toner and the like remaining on the surface of the device.

Accordingly, in the toner image transfer step, the temperature of the surface of the intermediate transfer member 5 is not sufficiently lowered, and the temperature of the surface of the photosensitive drum 1 is reduced from 45 ° C. to 55 ° C.
The cleaning blade 17 is always in contact with the surface of the photosensitive drum 1, and when the temperature of the photosensitive drum 1 increases, the temperature of the cleaning blade 17 also increases. Therefore, there is a concern that the viscoelasticity of the blade rubber is changed and cleaning failure occurs.

For this reason, the present inventor has proceeded with experiments focusing on tangent loss tan δ, which is an index of viscoelasticity of rubber. Here, the devices and conditions used for the evaluation are shown. Evaluation machine Acolor935 remodeling machine Toner Acolor935 toner Photoconductor drum Photoconductor drum for Acolor935 Speed 260mm / sec Surface temperature of photoconductor drum 50 ± 3 ℃

The photosensitive drum 1 used here is an organic photosensitive member in which an undercoat layer, a charge generation layer and a charge transport layer are sequentially coated on an aluminum substrate, and the surface protective layer is mainly made of polycarbonate. . The surface roughness is Ra 0.0
03 μm to 0.005 μm.

Further, the toner includes a binder resin of a polyester resin, toner particles containing a colorant, and titanium oxide for improving developability, transportability, transferability, storability, electrical resistance, and cleaning properties. And additives such as silicon oxide and aliphatic alcohol wax.

The cleaning blade is made of urethane material.
A prototype was produced by changing the peak value of tan δ. The cleaning blade is as follows. Rubber hardness 68Hs-79Hs (Jis A) Thickness 2mm Protrusion 10mm Load 196mN / cm Setting angle 10-20 °

The set angle was adjusted such that when a load of 196 mN / cm was applied to cleaning blades having different rubber hardnesses, the angle between the tip and the surface of the photosensitive drum was 9 ± 2 °. Under the above conditions, various tanδ
For each cleaning blade, cleaning maintainability was evaluated. In the above evaluation machine, first, an on-surface heating element is mounted inside the photosensitive drum, and the surface temperature is set to 50 ° C. ± 2.
Control to ° C. Development and transfer are performed with the original blank.
A small amount of toner, which is called fog toner, is applied on the photosensitive drum, and the toner is rotated continuously for 30 minutes, and the state of the turning of the cleaning blade, that is, the occurrence of unwiped toner is examined. Further, since the performance of the cleaning blade must be exhibited even when the temperature of the blade is low, the same test was performed when the apparatus was started after the non-use state continued, that is, when the area around the photosensitive drum was not warmed. The results are shown in FIG.

Near the cleaning blade when the apparatus is started,
The temperature around the photosensitive drum was about 16 ° C. FIG. 2 shows the same cleaning blade at a high temperature (50 ° C. ± 2).
° C) and when the apparatus is started (at low temperature), and plotted at the same position. The upper part shows the result at the time of high temperature, and the lower part shows the result at the time of starting the apparatus (low temperature). The criteria are
○ indicates a case where cleaning failure does not occur for 30 minutes. X indicates a case where cleaning failure such as turning up, chattering, or residual toner wiping occurred within 25 minutes, and △ indicates a case where the cleaning occurred between 25 minutes and 30 minutes.

As a result, the cleaning performance at high temperatures is as follows:
It was found that the peak temperature of Tan δ should be 10 ° C or higher, and the cleaning performance at the time of starting the apparatus (at a low temperature) should be 30 ° C or lower. Then, when the actual running test was performed twice using a cleaning blade having a rubber hardness of 79 Hs and a peak temperature of Tan δ of 20 ° C., no cleaning failure occurred up to a sheet running number of 70,000.

The cleaning blade of the present embodiment is particularly limited by the type of the surface layer of the photoreceptor, the difference between the roll type and the belt type, and the types of the binder resin, colorant and additives of the toner. is not. If the surface roughness of the photoreceptor is rough, the cleaning blade is slippery and the blade is not easily turned up.However, the surface roughness of the organic photoreceptor currently used is Ra0.01μm, suitable for most photoreceptors. It is considered possible.

The above image forming apparatus is a system in which the toner image on the intermediate transfer member is transferred to a sheet and is fixed at the same time. As the cleaning means for removing the residual toner on the body, the same cleaning means as the cleaning blade 17 can be used.

[0044]

As described above, according to the present invention, a doctor type cleaning blade for removing residual toner on the surface of a toner image carrier, a cleaning apparatus using the same, or an image forming apparatus such as a printer or a copier is provided. In the above, even if the surface temperature of the toner image carrier increases due to prevention of image flow on the toner image carrier and restrictions on the system, it is possible to prevent the occurrence of cleaning defects such as blade turning and chattering for a long time. .

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a view showing a result of investigation of occurrence of cleaning failure using a cleaning blade having a different peak temperature of Tan δ.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor drum 2 Charging device 3 Optical scanning device 4 Developing device 5 Intermediate transfer body 6 Transfer charger 7 Cleaning device 8 Heating roll 9 Pressure roll 10 Image forming unit 11 Belt drive roll 12 Support roll 13 Paper peeling roll 14 Cleaning roll 15 Cooling device 17 Cleaning blade

Claims (4)

[Claims] 1. A cleaning blade which is pressed against a toner image carrier having a toner image carried on a surface thereof and removes toner remaining on the surface of the toner image carrier, wherein a distortion caused by applying a sinusoidal vibration is provided. When the complex elastic modulus showing the delay of G is G = G ′ + iG ″, at least the portion that is pressed against the toner image carrier has a peak temperature of tangent loss tanδ (= G ″ / G ′) of 10 ° C. or more. A cleaning blade made of a urethane material having a temperature of 30 ° C. or lower. 2. A toner image carrier having a surface on which a toner image is carried, which is disposed so as to remove toner remaining on the surface of the toner image carrier after the toner image is transferred to a transfer-receiving body. A cleaning device having a cleaning blade disposed so as to be in pressure contact with the surface of the toner image bearing member, wherein a complex elastic modulus indicating a delay of strain when sine wave vibration is applied is represented by G = G ′ + iG ″. In this case, at least a portion of the cleaning blade that is in pressure contact with the toner image carrier has a tangent loss tan δ (= G ″ /
A cleaning device comprising a urethane material having a peak temperature G ′) of 10 ° C. or more and 30 ° C. or less. 3. An image carrier on which a latent image is formed on the surface due to a difference in electrostatic potential, a developing device for visualizing the latent image by attaching toner, and a recording medium or a toner image on the image carrier. 3. An image, comprising: a transfer device that transfers the toner image to an intermediate transfer member; and the cleaning device according to claim 2, which removes toner remaining on the surface of the image carrier after the toner image is transferred. Forming equipment. 4. An image carrier on which a latent image is formed on the surface due to a difference in electrostatic potential, a developing device for visualizing the latent image by attaching toner, and a toner image formed on the image carrier. An intermediate transfer member to be transferred, a transfer device that transfers a toner image on the intermediate transfer member to a recording medium, and removing the toner remaining on the surface of the intermediate transfer member after the toner image is transferred. An image forming apparatus, comprising: the cleaning device according to claim 2.