JPH1048962A - Intermediate transfer body, image formation device, and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device using an intermediate transfer body which prevents any unoccupied image at the time of image transfer by using an endless belt whose surface coarsness is set to a specific range. SOLUTION: An endless belt whose surface coarseness is set in the range of Rz=4∼30μm is used. When the surface coarseness is in this range, an appropriate frictional force acts between the toner on an OPC and a belt surface in transferring so that the separation of toner is promoted and so the transfer is executed superiorly along with the action of the electric field. When the surface coarseness is smaller than this range (in a case of being smooth), the shearing force (frictional force) between an intermediate transfer body 29 and a photosensitive member is small in transferring (the primary transfer) a toner image formed on the photosensitive member on a belt so that the magnetic field does not provide superior transfer and causes an unoccupied image on the contrary, when the coarseness is larger than this range, the toner is buried in the recessed part of the belt surface so as not to transfer satisfactorily. The both of the front layer 22 and the basic layer 21 are continuously manufactured in the same equipment.

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 using an electrophotographic method, and more particularly, to a method in which a toner image formed on a first image carrier is temporarily transferred onto an intermediate transfer member and then transferred to a second image carrier. And an image forming apparatus such as a copying machine, a printer, a facsimile, etc., for obtaining an image formed product by further transferring the image on an image carrier.

[0002]

2. Description of the Related Art An image forming apparatus using an intermediate transfer member includes:
A color image forming apparatus or a multi-color image forming apparatus for sequentially transferring a plurality of component color images of the color image information or the multi-color image information and outputting an image formed by combining and reproducing the color image or the multi-color image; Alternatively, the present invention is effective as an image forming apparatus having a color image forming function and a multicolor image forming function, and can obtain an image without overlapping displacement (color displacement) of each component color image.

In a color electrophotographic apparatus having an image forming apparatus using the above-mentioned intermediate transfer member, a second image support is stuck or adsorbed on a transfer drum, which is a conventional technique, and a first image is stuck thereon. A color electrophotographic apparatus having an image forming apparatus for transferring an image from a support is disclosed in
It is superior to the transfer method as described in JP-A-3-301960 in the following points. That is, there is little color shift at the time of superimposing toner images of each color. Further, since the image can be transferred from the intermediate transfer body without requiring any processing and control (for example, gripping, sucking, giving a curvature, etc. to the gripper) on the second image support, the second image support can be used. A wide variety of image supports can be selected.

For example, it is possible to select from thin paper (40 g / m ² paper) to thick paper (200 g / m ² paper), and transfer is possible regardless of the width and width of the second image support. . Further, it is possible to deal with envelopes, postcards, label paper, and the like.

As the shape of the intermediate transfer member, a drum-shaped or belt-shaped one can be considered, but the advantages of adopting the belt-shaped intermediate transfer member are that the cost of the entire apparatus can be reduced, and the transfer member arrangement design. Is high. In this case, the belt is desirably in the form of an endless belt.

As described above, due to the advantages of using the intermediate transfer member, a color copying machine, a color printer, and the like using this image forming apparatus have already started operating in the market. However, there are the following problems when using the above-described conventional example, particularly when using an intermediate transfer member having an endless belt shape. That is, as a transfer method, first, transfer by pressing or the like can be considered. In this case, it is necessary to control the transferability and the releasability of the toner with respect to the intermediate transfer member to an appropriate area. )
In some cases, the toner was heated and melted for high efficiency including transfer to the toner. Therefore, for controlling the characteristics of the intermediate transfer member, the added materials, the manufacturing process, and the apparatus are complicated, and the cost is increased.

On the other hand, in the transfer method using electrostatic force, transfer is basically performed without relying on mechanical force. Therefore, the required characteristics of the intermediate transfer member mainly include electrical values such as resistance. Therefore, since heat resistance and the like are not particularly required, the apparatus configuration can be relatively simplified, which is advantageous.

However, even in such a system, the transfer efficiency of a belt whose surface roughness is not controlled can be improved even when a sufficient electric field is applied when a toner image formed on a photoreceptor is transferred to the belt surface (secondary transfer). In some cases, the primary transfer or the secondary transfer does not sufficiently transfer a portion other than the outline of the image, which is a so-called "void".

As a method for imparting an appropriate roughness to the surface, chemical etching or mechanical roughening (sand plasting or the like) is generally performed after molding. Due to various variations in molding such as etching means and blast pressure, there has been a problem in quality control.

It is also possible to control the surface roughness by "post-processing" such as heating and plasticizing and pressing against a mold or the like. The development of anisotropy of mechanical strength).

[0011]

SUMMARY OF THE INVENTION A first object of the present invention is to provide an image forming apparatus using an intermediate transfer member which does not cause a dropout during image transfer, and a second object is to provide a simple image forming apparatus. An object of the present invention is to provide a method for producing an intermediate transfer member that can control the surface roughness without impairing the physical properties of the material in the process.

[0012]

According to the present invention, there is provided an intermediate transfer member characterized in that the belt is an endless belt having a surface roughness in the range of Rz = 4 to 30 μm.

According to the present invention, there is provided an image forming apparatus for transferring an image formed on a first image carrier onto an intermediate transfer member and further transferring the image onto a second image carrier, wherein the intermediate transfer member is endless. The belt has a surface roughness of Rz = 4.
The image forming apparatus is characterized by being in the range of ３０30 μm.

According to the present invention, there is provided an image forming apparatus for transferring an image formed on a first image carrier onto an intermediate transfer member and further transferring the image onto a second image carrier. An endless belt having a surface layer containing at least a resin as a main component, which is formed by centrifugal molding with a rotor having an inner surface of Rz = 4 to 30 μm, and the surface roughness of the intermediate transfer member is set to Rz = 4 to 30 μm. And a method for manufacturing an image forming apparatus.

The numerical values of the surface roughness of the belt surface are as follows: measurement length = 2.5 mm, cutoff = 0.8 mm, measurement speed = 3
This is based on a measurement method under the condition of mm / sec. Hereinafter, the roughness value in the text is based on the present measurement method.

The intermediate transfer member is an endless belt having at least a surface layer mainly composed of a resin, and is manufactured by centrifugal molding with a rotor having an inner surface of Rz = 4 to 30 μm. The surface roughness of the transfer body is Rz
= 4 to 30 μm.

The intermediate transfer member of the present invention will be described in detail.

As the elastomer used for the base layer,
For example, styrene-butadiene rubber, high styrene rubber,
Examples include butadiene rubber, isoprene rubber, ethylene-propylene copolymer, nitrile butadiene rubber, chloroprene rubber, butyl rubber, silicone rubber, fluorine rubber, nitrile rubber, urethane rubber, acrylic rubber, epichlorohydrin rubber and norbornene rubber.

In practice, an intermediate transfer member requires electric resistance adjustment for controlling a transfer current. Any of commonly used conductive fillers can be used, but particularly preferred are furnace black, acetylene black,
Addition and kneading of carbon-based fillers such as Ketjen black, graphite, and carbon fibers, and metal oxide-based conductive fillers represented by tin oxide and zinc oxide impurity doping products. Done.

The base layer can be formed by extrusion molding,
Centrifugal molding and the like can be mentioned. The thickness of the base layer is preferably 0.5 mm or more.

As the surface material, resins are preferable in order to suppress the influence of color shift due to elongation and to have flexibility, but engineering plastics are preferable in terms of strength and dimensional stability. (However, the engineering plastics mentioned here include all resins according to commonly used definitions. Preferably, so-called five major engineering plastics having excellent mechanical properties, heat resistance, and durability (polyacetal, polyamide, Polycarbonate
Bonnet, polybutylene terephthalate, polyphenylene oxide) and super engineering plastics having excellent heat resistance and the like. ) Particularly preferred among engineering plastics are polyetherimide, polyethersulfone, polysulfone, and polyphenylsulfone which are excellent in long-term creep characteristics and dimensional stability.

The elastic modulus of the surface layer is 1500 N
/ Mm ² or more, and if it is less than this, minute deformation due to tension contributes to the positional deviation of the toner.

The thickness of the surface layer needs to be a thin layer for transmitting the flexibility of the base layer. Specifically, the thickness is preferably 1 mm or less, particularly 10 μm to 300 μm. In addition to rising, the film lacks flexibility and cannot be used as a belt material.

The method of adjusting the resistance is the same as that of the base layer, and the volume resistivity in the thickness direction of the formed multilayer endless belt is preferably in the range of 10 ⁵ to 10 ¹² Ω · cm. If the volume resistivity is smaller than this range, an excessive transfer current flows. Conversely, if the volume resistivity is large, a sufficient current cannot be obtained, and good transfer is not performed.

At the time of transfer, a transfer electric field is usually applied to apply an electrostatic force, and also to increase the fluidity of the toner so as to facilitate transfer, the difference in rotational speed between the photosensitive member and the intermediate transfer member (peripheral speed). Difference) may be set, but in many cases this alone is not sufficient.

Therefore, in the present invention, in order to enhance the transfer efficiency of the image (toner), the surface roughness of the intermediate transfer member is preferably set to a surface roughness of Rz = 4 to 30 μm, more preferably. Is preferably in the range of Rz = 5 to 9 μm. When the surface roughness is within this range, an appropriate frictional force acts between the toner on the OPC and the belt surface at the time of transfer, thereby facilitating the peeling of the toner image. Done. When the surface roughness is smaller than this range (when the surface is smooth), the toner image formed on the photosensitive member is transferred onto the belt (primary transfer) (primary transfer). Since the slip force (frictional force) is small, good transfer is not performed only by the electric field, which causes hollowing. When the roughness is larger than this range, the toner is buried in the concave portion of the belt surface. The transfer is not performed sufficiently.

As a method of forming the intermediate transfer member (multi-layer endless belt composed of a surface layer and a base layer) in the present invention, for example, a method of forming a surface layer by spraying or dipping after forming a base layer, or a method of forming each layer separately. Although it can be obtained by laminating with an adhesive or the like, a method of forming a surface layer in advance by a centrifugal molding method and subsequently forming a base layer by the same method is preferable for the following reasons.

That is, since both the surface layer and the base layer are continuously produced with the same equipment, the load on the equipment is small, and the number of steps for transferring between the apparatuses can be reduced. In addition, since the liquid base layer is injected and solidified after the surface layer is formed, an appropriate combination of materials does not require an adhesive or the like, and the thickness accuracy is easily obtained.

Further, the aforementioned surface roughness Rz = 4 to 30 μm
The most effective means for roughening the surface of the intermediate transfer member to a specific surface roughness in the range of from the viewpoint of quality stability and cost reduction is the rotor of the centrifugal molding machine. This is a method in which the inside is previously processed to an appropriate roughness by a method such as sandblasting or etching, and a surface layer material is charged and formed therein. If molding is performed by this method, the surface roughness of the intermediate transfer member can be adjusted even if the viscosity of the material used and the adhesion between the rotor and the material during molding (surface energy, centrifugal force, etc.) are optimized. If it becomes a replica of the rotor inner surface,
Since it is not necessary to control the surface roughness, it is possible to greatly reduce the number of steps in which the apparatus is simplified.

Further, since the dimensions (outer diameter, etc.) of the molded article are determined by the diameter of the rotor and the shrinkage of the material, the outer diameter is adjusted by polishing as compared with the case of molding by extrusion molding or the like. Since there is no need, cost can be reduced, and a uniform outer diameter can be obtained.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION

The image forming apparatus of the present invention is a color image forming apparatus utilizing an electrophotographic process as shown in FIG. An endless belt is used as an intermediate transfer member.
The first image carrier is a rotating drum type electrophotographic photosensitive member (hereinafter, referred to as a photosensitive drum) that is used repeatedly,
It is driven to rotate at a predetermined peripheral speed (process speed) in the clockwise direction indicated by the arrow. The photosensitive drum 1 is uniformly charged to a predetermined polarity and potential by a primary charger (corona discharger) in the course of rotation, and then is subjected to image exposure by an image exposure means (not shown) to form a target color image. An electrostatic latent image corresponding to a first color component image (for example, a magenta component image) is formed.

Next, the electrostatic latent image is developed by a first developing device (magenta developing device) by magenta toner of the first color. At this time, the developing units of the second to fourth developing units (for example, cyan, yellow, and black) are inactive and do not act on the photosensitive drum, and the magenta toner image of the first color is the second to fourth developing units. 4 is not affected by the developing unit.

The intermediate transfer member is driven to rotate in the counterclockwise direction indicated by the arrow at the same peripheral speed as the photosensitive drum. The intermediate transfer member has an endless belt shape, and includes an elastomeric elastic base layer and a resin layer formed on the outer peripheral surface thereof.

In FIG. 3, the primary transfer bias applied to the intermediate transfer member while the magenta toner image of the first color formed and carried on the photosensitive drum passes through the nip portion between the photosensitive drum and the intermediate transfer member. The intermediate transfer is sequentially performed on the outer peripheral surface of the intermediate transfer body by the electric field formed by the above. After the transfer of the first color magenta toner image corresponding to the intermediate transfer member, the surface of the photosensitive drum is cleaned by a cleaning device.

Similarly, a second color cyan toner image,
Yellow toner image of the third color, black toner image of the fourth color
The images are sequentially superimposed and transferred on the intermediate transfer member, and the target color is
A composite color image corresponding to the image is formed.

A primary transfer bias for sequentially superimposing transfer of the first to fourth color toner images from the photosensitive drum to the intermediate transfer member is applied from a bias power supply with a polarity (+) opposite to that of the toner. . The applied voltage is in the range of +2 kV to +5 kV.

The transfer roller is provided in parallel with the intermediate transfer member so as to bear in parallel and to contact the lower surface. In the step of sequentially transferring the toner images of the first to fourth colors from the photosensitive drum to the intermediate transfer member, the transfer roller can be separated from the intermediate transfer member.

Synthetic color superimposedly transferred on the intermediate transfer member
The transfer of the toner image to the transfer material, which is the second image carrier, is performed by bringing the transfer roller into contact with the intermediate transfer member and simultaneously transferring the intermediate transfer member and the transfer roller from the sheet cassette. A transfer material is fed to the contact nip at a predetermined timing, and at the same time, a secondary transfer bias is applied to a transfer roller from a bias power supply. With this secondary transfer bias, the second transfer bias
A synthetic color toner image is transferred to a transfer material as an image carrier. The transfer material having undergone the toner image transfer is introduced into a fixing device and fixed by heating. After the image transfer to the transfer material is completed, the transfer residual toner on the intermediate transfer member is cleaned by contacting the intermediate transfer member cleaner.

The production of the intermediate transfer member of the present invention is performed, for example, as follows.

The surface layer is prepared by dissolving polyphenylsulfone in a solvent so that the binder-polymer concentration becomes 20 wt%, adding a conductive carbon, dispersing the mixture using a paint shaker, and then centrifuging a machine. And dry-molding.

As an example of forming the base layer from polyurethane, as an example, a polyester-based polyol is heated, a conductive carbon is added, and the mixture is dispersed with a stirrer. After the surface layer is formed, the mixture is charged into a centrifugal molding machine after the surface layer is formed, and is heated and cured. Thereafter, aging is performed, and then the product is naturally cooled to room temperature, taken out of the molding machine and cut at the end to obtain an intermediate transfer member.

[0043]

【Example】

Example 1 (Formation of Surface Layer) The surface layer was prepared by dissolving 100 parts by weight of polyphenylsulfone in a solvent (dimethylacetamide) so that the binder polymer concentration became 20 wt%.
After adding 7 parts by weight of Bonn (trade name: Ketjen Black 600JD, manufactured by Ketjen Black International), the mixture was dispersed by a paint shaker for 30 minutes.
Dry molding was performed by a centrifugal molding machine at 800 RPM, 120 ° C. and 30 minutes.

The schematic diagram of the centrifugal molding machine is shown in FIG. Reference numeral 71 denotes a molding machine main body, and a rotor 72 for charging a molding material.
Is 140mm inside diameter, 250m depth (belt width)
m, and the surface roughness of the inner surface of the rotor is Rz = 4 to 6 μm.
And the material is hard chrome (plated). In addition, a heating means 73 using a steam is provided, and the temperature can be raised to a maximum of 180 ° C.

(Formation of Base Layer) The base layer was formed of polyurethane. 100 parts by weight of polyester-based polyol
Heat to 0 ° C., add 10 parts of conductive carbon (trade name: Ketjen Black 600JD, manufactured by Ketjen Black International), and disperse for 1 hour with a stirrer.
After adding 60 parts by weight of an MDI-based iso-shank heated to 0 ° C. and dispersing the mixture with a stirrer for 3 minutes, the mixture was charged into a centrifugal molding machine after forming the surface layer, and was then subjected to 2000 RPM, 120 ° C.,
Heat curing was performed under the conditions of 3 hours. Thereafter, aging was carried out at 80 ° C. for 1 hour, and the mixture was naturally cooled to room temperature, taken out of the molding machine and cut at the end to obtain an intermediate transfer member.

The resulting intermediate transfer member had a surface layer thickness of 150 μm.
m, base layer thickness 800 μm, volume resistivity after film formation 10 ⁸ Ω
Cm, and surface roughness of the surface layer (average value at 30 points): R _Z = 4.8 μm (minimum value 4.0 μm, maximum value 7.0 μm)
m).

The same method as in the present example, in which the surface layer was formed alone, had a volume resistivity of 10 ⁹ Ω · cm, and similarly, that of the base layer was 10 ⁸ Ω · cm.

(Evaluation of Intermediate Transfer Body) FIG. 3 is a schematic view of an image forming apparatus which is a transfer apparatus used for evaluation of image output and durability. FIG. 3 shows a color image forming apparatus (copier or laser beam printer) using an electrophotographic process. An endless belt 20 is used as an intermediate transfer member. Reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member (hereinafter, referred to as a photosensitive drum) which is repeatedly used as a first image carrier, and rotates at a predetermined peripheral speed (process speed) clockwise as indicated by an arrow. Driven.

In the course of rotation, the photosensitive drum 1 is uniformly charged to a predetermined polarity and potential by a primary charger (corona discharger) 2, and then subjected to image exposure means (not shown) for color separation and color image separation of the original image. Receiving image exposure 3 by an imaging exposure optical system, a scanning exposure system using a laser caster that outputs a laser beam modulated in accordance with a time-series electric digital pixel signal of image information, etc. As a result, an electrostatic latent image corresponding to the first color component image (eg, magenta component image) of the target color image is formed.

Next, the electrostatic latent image is transferred to the first developing device 41.
(Magenta developing device), the first color of magenta toner
Developed by M. At this time, the second to fourth developing devices 42,
The developing devices 43 and 44 (cyan, yellow and black) are inactive and do not act on the photosensitive drum 1, and the magenta toner image of the first color is subjected to the second to fourth developing devices 42. Not affected by ~ 44.

The intermediate transfer member 20 is rotated at the same peripheral speed as the photosensitive drum 1 in the counterclockwise direction indicated by the arrow.

The intermediate transfer member 20 is in the form of an endless belt, and as shown in FIG.
And a resin layer 22 formed on the outer peripheral surface thereof.

In FIG. 3, the magenta toner image of the first color formed and carried on the photosensitive drum 1 is applied to the intermediate transfer body 20 while passing through the nip between the photosensitive drum 1 and the intermediate transfer body 20. The intermediate transfer is sequentially performed on the outer peripheral surface of the intermediate transfer body 20 by the electric field formed by the primary transfer bias. After the transfer of the first color magenta toner image corresponding to the intermediate transfer member 20, the surface of the photosensitive drum 1 is cleaned by the cleaning device 14.

Similarly, a second color cyan toner image,
Yellow toner image of the third color, black toner image of the fourth color
The images are sequentially superimposed and transferred onto the intermediate transfer body 20 to form a composite color image corresponding to the target color image.

Reference numeral 25 denotes a transfer roller, which is provided in parallel with the intermediate transfer member 20 and in contact with the lower surface thereof.

First transfer from the photosensitive drum 1 to the intermediate transfer member 20
A primary transfer bias for sequentially superimposing transfer of the toner images of the colors to the fourth color is applied from a bias power supply 61 with a polarity (+) opposite to that of the toner. The applied voltage is +2 kV to +5 k
V range.

First transfer from the photosensitive drum 1 to the intermediate transfer member 20
In the sequential transfer execution process of the toner image of the color to the fourth color,
The transfer roller 25 can be separated from the intermediate transfer member.

The transfer of the composite toner image superimposed and transferred onto the intermediate transfer member 20 onto the transfer material 24 as the second image carrier is performed by the transfer roller 25 contacting the intermediate transfer member 20. At the same time, the transfer material 24 is fed from the paper supply cassette 9 to the contact nip between the intermediate transfer body 20 and the transfer roller 25 at a predetermined timing, and at the same time, the secondary transfer bias is applied from the bias power supply 29 to the transfer roller. Applied to line 25. With this secondary transfer bias, a synthetic color toner image is transferred from the intermediate transfer member 20 to the transfer material 24 as the second image carrier. The transfer material 24 to which the toner image has been transferred is introduced into the fixing device 51 and is fixed by heating. After the transfer of the image to the transfer material 24, the transfer residual toner on the intermediate transfer member 20 is cleaned by contacting the intermediate transfer member cleaner 35.

An intermediate transfer member was mounted on the apparatus, a tension of 50 N was applied, an image was output by a test pattern, and the occurrence of hollowing was examined on the tenth initial output sheet by a microscope at a magnification of 100 times. . As a result of the evaluation,
As shown in the enlarged photograph after transfer shown in FIG. 5, the hollow was not generated and was good.

Comparative Example 1 The surface roughness of the inner surface of the rotor during centrifugal molding was Rz = 1.
An intermediate transfer member was prepared using the same material and method as in Example 1 except that a μm-thick one was used. The obtained intermediate transfer member had a surface layer thickness of 140 μm, a base layer thickness of 850 μm, a volume resistivity after film formation of 10 ⁸ Ω · cm, and the surface roughness of the molded product was Rz =
It was 2.7 μm (minimum value 0.6 μm, maximum value 3.8 μm).

Using this intermediate transfer member, evaluation was performed in the same manner as in Example 1. As a result, as shown in the enlarged photograph after transfer shown in FIG. 4, the occurrence of voids was confirmed, and the image state was poor. .

Example 2 The surface layer was composed of 100 parts by weight of polysulfone and a binder polymer.
It is dissolved in a solvent (methylene chloride) so as to have a concentration of 20 wt%, and the conductive carbon (Ketjen Black 600J) is dissolved.
D) 8 parts by weight were added, and the mixture was dispersed for 30 minutes by a paint shaker.
Dry molding was performed at 20 ° C. for 30 minutes. Hollow centrifugal molding machine - motor - surface roughness of the inner surface is machined by a sand blast method in the range of R _Z = 25~30μm, the material is hard black - a beam (plating). Next, the surface layer and the base layer were formed by the same material and method as in Example 1 to obtain an intermediate transfer member. The obtained intermediate transfer member has a surface layer thickness of 180 μm,
The base layer thickness is 700 μm, and the volume resistance after film formation is 10 ⁸ Ω ·
cm and surface roughness of surface layer (average value of 30 points) are Rz
= 28 μm (minimum value 26.5 μm, maximum value 30.0 μm
m).

The same evaluation as in Example 1 was performed using this intermediate transfer member, and as a result, the transferred image was a good image without any voids.

Comparative Example 2 The base layer was made of polyurethane. 100 parts by weight of a polyester-based polyol is heated to 80 ° C., 10 parts of a conductive carbon (Ketjen Black 600 JD) is added, and the mixture is dispersed for 1 hour with a stirrer. 60 parts by weight, and dispersed for 3 minutes with a stirrer.
Heat curing was performed at a temperature of 3 ° C. for 3 hours. Then 80 ° C,
After aging for 1 hour, the mixture was naturally cooled to room temperature, taken out of the molding machine and cut at the end.

The surface layer was formed as follows using polysulfone as a binder. Polysulfone 100
Parts by weight, conductive carbon (Ketjen Black 600J
D) 8 parts by weight are heated and kneaded at 180 ° C. with a hot roll, dispersed and then molded by an extruder. The base and the base layer are heated and pressed at 150 ° C. and adhered. Polishing was performed with a par polisher to obtain an intermediate transfer member with a surface roughness of Rz = 35 μm. (However, since this method lacks uniformity, the dispersion is large and the maximum value is R _Z = 48 μm.
Rz = 30.5 μm at the minimum). The resulting intermediate transfer member had a surface layer thickness of 180 μm and a base layer thickness of 700 μm.
m, and the volume resistivity after film formation was 10 ⁸ Ω · cm.

As a result of evaluation using the intermediate transfer member in the same manner as in Example 1, toner was buried in a portion having a large roughness, a hollow portion and an untransferred portion occurred in a small portion, and the image state was poor. It was bad.

Example 3 100 parts by weight of polyethersulfone was dissolved in a solvent (dimethylacetamide) so that the binder polymer concentration became 20 wt%, and 10 parts by weight of a conductive carbon (Ketjen black 600 JD) was added. , Paint shaker
And then dispersed for 30 minutes using a centrifugal molding machine.
Dry molding was performed under the conditions of 0 RPM, 120 ° C. and 30 minutes, taken out after cooling, and cut to obtain a single-layer intermediate transfer member.
The surface roughness of the rotor inner surface of the centrifugal molding machine is Rz = 8 to 13.
It is processed by the sandblast method in the range of μm,
The material is hard nickel-phosphorus (plating). The resulting intermediate transfer member had a thickness of 170 μm and a volume resistance of 1 after film formation.
0 ⁸ Ω · cm and a surface roughness (average value of 30 points) Rz = 10 [mu] m (minimum 8.5 .mu.m, the maximum value 12.0μ
m).

Using this intermediate transfer member, the same evaluation as in Example 1 was carried out. As a result, the transferred image was good with no occurrence of voids.

Comparative Example 3 The surface roughness of the rotor inner surface of the centrifugal molding machine was Rz = 35-4.
An intermediate transfer member was prepared in the same manner as in Example 3 except that a material processed to a range of 5 μm by a sandblast method was used. The obtained intermediate transfer member has a thickness of 170 μm.
m, the volume resistivity after film formation is 10 ⁸ Ω · cm, and the surface roughness (average value at 30 points) is Rz = 40 μm (minimum value 3).
7 μm, maximum value 48.5 μm).

Using this intermediate transfer member, the same evaluation as in Example 1 was performed. As a result, the transferred image was disturbed and toner transfer residue often occurred because the surface roughness was too large.

[0071]

According to the image forming apparatus of the present invention, there is a remarkable effect that a clear image without a dropout can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of one example of an intermediate transfer member used in the present invention.

FIG. 2 is a schematic view of an example of a centrifugal molding machine used in the present invention.

FIG. 3 is a schematic view of an example of the color image forming apparatus of the present invention.

FIG. 4 is an example of occurrence of voids due to image evaluation.

FIG. 5 is a good transfer example obtained by image evaluation.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photosensitive drum 2 primary charger 3 image exposure 9 paper feed cassette 14 cleaning device 20 intermediate transfer member 21 base layer 22 surface layer 24 transfer material 29 bias power supply 35 intermediate transfer member cleaner 41 first developing device 42 second developing device Unit (cyan developing unit) 43 Third developing unit (yellow developing unit) 44 Fourth developing unit (black developing unit) 51 Fixing unit 61 Bias power supply 71 Centrifugal molding machine main body 72 Rotor 73 Heating fin

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masaaki Takenaka 1888-2 Kusazaki, Kusazaki-cho, Inashiki-gun, Ibaraki Pref. Canon Chemical Co., Ltd.

Claims (7)

[Claims] 1. A belt having a surface roughness Rz = 4-30.
An intermediate transfer member, which is an endless belt in a range of μm. 2. An image forming apparatus for transferring an image formed on a first image carrier onto an intermediate transfer member, and further transferring the image onto a second image carrier, wherein the intermediate transfer member is an endless belt. And the surface roughness of the belt surface is Rz = 4-30.
An image forming apparatus having a range of μm. 3. The image forming apparatus according to claim 1, wherein the intermediate transfer member is a multi-layer endless belt, and comprises at least an elastomer base layer and a surface layer mainly composed of resin. 4. The electrophotographic photoreceptor according to claim 2, wherein the main component of the surface layer is an engineering plastic. 5. The main component of the surface layer is polyetherimide,
The image forming apparatus according to claim 2, wherein the image forming apparatus is at least one selected from the group consisting of polyethersulfone, polysulfone, and polyphenylsulfone. 6. The image forming apparatus according to claim 1, wherein the electric resistance is adjusted by a conductive filler, and the volume resistivity measured in the thickness direction of the endless belt is 10 ⁵ to 10 ¹² (Ω · cm). . 7. An image forming apparatus for transferring an image formed on a first image carrier onto an intermediate transfer member and further transferring the image onto a second image carrier, wherein the intermediate transfer member includes at least resin. An endless belt having a surface layer as a main component, which is formed by centrifugal molding with a rotor having an inner surface of Rz = 4 to 30 μm, and the surface roughness of the intermediate transfer member is Rz.
= 4 to 30 μm.