JP2001312159A - Intermediate transfer member and image forming apparatus - Google Patents

Abstract

(57) [Summary] [Problem] Regardless of the surface properties of transfer paper, white spots, hollow spots,
Provided are an intermediate transfer member capable of performing transfer without occurrence of character collapse, color misregistration, and the like, and an image forming apparatus capable of printing a high-quality full-color image using the intermediate transfer member. According to the present invention, a step of forming a toner image on a first image carrier and performing a primary transfer of the toner image to an intermediate transfer body is performed once or a plurality of times, and then the process is performed on the intermediate transfer body. Intermediate transfer type image forming apparatus for secondary transfer of the toner image to the second image carrier 22, and an intermediate transfer body used in the image forming apparatus, the intermediate transfer body has at least an elastic layer, the toner The surface micro hardness of the toner carrying surface that carries the image has a peak value of the surface micro hardness in the range of 30 to 70 degrees as measured by a micro rubber hardness meter, and from the time when the peak value of the surface micro hardness is shown. The difference ΔD between the surface micro hardness after 3 seconds and the peak value of the surface micro hardness is 5 degrees or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus applied to a copying machine, a printer, a facsimile, a plotter, and the like, and more particularly, to an intermediate transfer member used in an image forming apparatus using an intermediate transfer method. And an image forming apparatus capable of forming a multi-color image or a full-color image using the intermediate transfer member.

[0002]

2. Description of the Related Art In a conventional image forming apparatus, a toner image formed on a photoreceptor as an image carrier is transferred to a transfer material.
After that, the toner image on the transfer material is heated and
There is known one that performs fixing by pressing. Further, as a conventional image forming apparatus for forming a full-color image, in a state where a transfer material is held on a transfer material carrier such as a transfer drum, yellow, magenta, cyan,
There is known a method in which each color of black is sequentially transferred to a transfer material, and thereafter, the transfer material peeled off from the transfer material carrier is heated and pressed by a fixing device and fixed to obtain a full-color image. On the other hand, instead of transferring the toner image to the transfer material on the transfer material carrier, for example, as disclosed in JP-A-5-11562, yellow developed on the photoreceptor,
Each color of magenta, cyan, and black is sequentially superimposed on the intermediate transfer member (hereinafter, referred to as primary transfer), and the four color toner images formed on the intermediate transfer member are collectively transferred to a transfer material (hereinafter, secondary transfer) After that, the image forming apparatus which is fixed by the fixing device has started to operate in the market. The feature of the above-described color image forming apparatus is that it is not necessary to hold the transfer material on the transfer material carrier unlike the conventional image forming apparatus, and therefore, the thin paper (40 g / m ² ), the thick paper (200 g / m ² ), and the postcard are used. ,
An image can be transferred to various types of transfer materials such as an envelope, and the transfer material has the advantage of high versatility.

[0003]

Although an image forming apparatus using an intermediate transfer member has the above-mentioned advantages, it still has the following problems to be solved. In recent years, color copiers,
As the operation rate of an electrophotographic color image forming apparatus such as a color laser printer increases in the market, there is an increasing demand from users for higher image quality. However, it has been found that a resin intermediate transfer belt used in a conventional intermediate transfer body has a high surface hardness, and so-called "missing" in which only an outline portion is transferred when a toner image is transferred is likely to occur. This “hollow-out” phenomenon appears as an insect-eating state as shown in FIG. 6 and is a phenomenon that is noticeable in a character image and a vertical line image. In addition, since the transfer efficiency of a resin-made intermediate transfer belt is not sufficiently high, the transfer residual toner in secondary transfer is large, and a load is imposed on the cleaning of the intermediate transfer member, and the size of the cleaning device is increased.

To solve these problems, Japanese Patent Laid-Open No.
Japanese Patent Application Laid-Open No. 0-198182 proposes an intermediate transfer belt in which the resistance value, the Young's modulus in the circumferential direction, and the micro hardness of the surface of the image carrier are specified.
However, this prior art does not consider the Young's modulus in the axial direction (perpendicular to the belt rotation direction),
There was a problem that color shift in the axial direction occurred due to the axial extension of the intermediate transfer belt. In addition, only the micro-hardness of the image carrier surface is determined by the transfer omission corresponding to the unevenness of the transfer paper surface described later or the primary transfer white omission during continuous printing due to the deformation of the intermediate transfer belt surface generated during the secondary transfer described later. May occur.

In recent years, from the viewpoint of environmental protection, there has been a movement to actively use recycled paper having many fine irregularities on the surface. Further, transfer papers having an uneven pattern on the surface have come to be used due to the variety of market demands. An example of the transfer paper having many irregularities is “Sazanami” (trade name (Japanese paper for full-color printing: manufactured by Japan Business Supply Co., Ltd.)). When using transfer paper having such a low surface smoothness, as shown in FIG.
It has been found that, due to its own hardness, it is not possible to follow the irregularities on the surface of the transfer paper 22, and there is a problem that transfer omission occurs corresponding to the irregularities.

To solve this problem, Japanese Patent Laid-Open No.
Japanese Patent No. 240027 proposes preventing the transfer omission corresponding to the above-mentioned unevenness by increasing the hardness of the secondary transfer roller. However, this method has not completely solved transfer omission due to surface irregularities, and because the hardness of the secondary transfer roller is high and the roller contact force is set high, banding due to vibration at the time of roller contact is performed. In some cases. further,
Hollow-out may also occur due to the height of the contact pressure. Also, as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 10-198182, when the intermediate transfer belt has elasticity, if the return time from the deformed state in the thickness direction to the original shape is long, the secondary transfer As shown in FIG. 8, during the continuous printing, the transfer from the image carrier 1 to the intermediate transfer belt 10 cannot be performed at the time of the first transfer after the second page after continuous printing. It has also been found that toner is generated, and a phenomenon such as transfer omission or density reduction corresponding to the distortion occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and solves the above-mentioned problems of the prior art. Occurrence of white spots, hollow spots, character collapse, color misregistration, etc., regardless of the surface properties of the transfer paper. It is an object of the present invention to provide an intermediate transfer member capable of performing untransferred transfer, and an image forming apparatus capable of printing a high-quality full-color image using the intermediate transfer member.

[0008]

In order to achieve the above object, the invention according to claim 1 includes a step of forming a toner image on a first image carrier and performing a primary transfer of the toner image to an intermediate transfer member. The intermediate transfer member used in an intermediate transfer type image forming apparatus for performing a secondary transfer of a toner image on the intermediate transfer member to a second image carrier after performing one or more times, wherein at least the elastic layer And the surface micro hardness of the toner carrying surface for carrying the toner image is 3 measured by a micro rubber hardness meter (for example, MD-1 manufactured by Kobunshi Keiki Co., Ltd.).
The peak value of the surface microhardness is in the range of 0 to 70 degrees, and the difference ΔD between the surface microhardness and the peak value of the surface microhardness three seconds after the peak value of the surface microhardness is exhibited. Is 5 degrees or less.

According to a second aspect of the present invention, after the step of forming a toner image on a first image carrier and performing a primary transfer of the toner image to an intermediate transfer member is performed once or a plurality of times, the intermediate transfer member is formed. The intermediate transfer member used in an intermediate transfer type image forming apparatus for secondary transferring an upper toner image to a second image carrier, the intermediate transfer member having at least a surface coating layer and an elastic layer, wherein the surface coating layer Contains fine particles having a particle size of 1 μm or less, and the surface micro hardness of the toner carrying surface for carrying the toner image is from 30 to 30 as measured by a micro rubber hardness meter (for example, MD-1 manufactured by Kobunshi Keiki Co., Ltd.). The peak value of the surface microhardness is in the range of 70 degrees, and the difference Δ between the surface microhardness and the peak value of the surface microhardness three seconds after the point at which the peak value of the surface microhardness was exhibited.
D is not more than 5 degrees.

[0010] The third aspect of the present invention is the first or second aspect.
The above described intermediate transfer body is characterized by comprising an intermediate transfer drum having a structure in which an elastic layer is provided on a conductive cylindrical substrate. According to a fourth aspect of the present invention, in the intermediate transfer body according to the first or second aspect, the intermediate transfer belt comprises an intermediate transfer belt having a structure in which an elastic layer is provided on an endless core layer. Furthermore, the invention according to claim 5 provides:
The intermediate transfer member according to any one of claims 1 to 4, wherein the elastic layer has a JIS-A hardness of 30 to 70 degrees. Further, the invention according to claim 6 is the intermediate transfer member according to claim 4 or 5, wherein the core layer has a film shape, and the core layer has a tensile modulus of 1 × 10 ² MPa or more and 3 ×. It is characterized in that it is 10 ⁵ MPa or less. According to a seventh aspect of the present invention, in the intermediate transfer member according to the fourth or fifth aspect, the core layer is a fiber, and the tensile elastic modulus of the core layer is 1 ×.
It is characterized in that it is not less than 10 ² MPa and not more than 3 × 10 ⁵ MPa. Further, the invention according to claim 8 is an intermediate transfer member according to any one of claims 2 to 7,
The fine particles having a particle size of 1 μm or less are fluorine resin fine particles.

According to a ninth aspect of the present invention, there is provided a first image carrier, a charging means for charging the first image carrier to a predetermined potential, and an electrostatic charge on the charged first image carrier. Exposure means for forming a latent image, developing means for visualizing the electrostatic latent image formed on the first image carrier with toner of a plurality of colors, and a toner image on the first image carrier in order. Image having primary transfer means for transferring onto an intermediate transfer member and secondary transfer means for contacting the back surface of a second image carrier and transferring a toner image on the intermediate transfer member to the second image carrier In the forming apparatus, the intermediate transfer member according to any one of claims 1 to 8 is used as the intermediate transfer member. According to a tenth aspect of the present invention, in the image forming apparatus of the ninth aspect, the toner used in the developing unit has a volume average particle diameter in a range of 4 to 10 μm.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction, operation and operation of the present invention will be described below in detail with reference to the illustrated embodiments. FIG. 1 is a schematic configuration diagram of a color image forming apparatus according to an embodiment of the present invention, in which an intermediate transfer member is an intermediate transfer belt, but an intermediate transfer drum is used instead of the intermediate transfer belt. It can also be. In FIG. 1, reference numeral 1 denotes a first image carrier that rotates in the direction of the arrow in the figure. The first image carrier is a photoconductive photoconductor formed in a drum shape. 1, a photoconductor cleaning unit 2, a charger 4, an exposure unit 5, an intermediate transfer belt 10,
Developing means and the like are arranged. The developing means comprises four developing devices, a yellow developing device 6, a magenta developing device 7, a cyan developing device 8, and a black developing device 9, and each developing device is selectively operated. And, when forming a full-color image,
A visible image of each color is formed on the photoreceptor 1 in the order of the yellow developing device 6, the magenta developing device 7, the cyan developing device 8, and the black developing device 9, and the visible images of each color are sequentially superimposed on the intermediate transfer belt 10. A full-color image is formed by being transferred together. Reference numeral 3 denotes a cleaning blade of the photoconductor cleaning unit 2.

The intermediate transfer belt 10 includes a driving roller 13,
Primary transfer bias roller 11 and driven roller 12
a and 12b, and is rotatably driven in the direction of the arrow in the figure by a drive motor (not shown). The primary transfer bias roller 11 is pressed in the direction of the photoconductor 1 by a pressure spring 27. The intermediate transfer belt 10 is adjusted to have a volume resistivity of 10 ⁸ to 10 ¹² Ωcm and a surface resistivity of 10 ⁸ to 10 ¹⁵ Ωcm. If the volume resistivity and the surface resistivity of the intermediate transfer belt 10 exceed the above ranges, the bias required for the transfer increases, which undesirably increases the power supply cost. In addition, the charge potential of the intermediate transfer belt 10 becomes high in the transfer step, the transfer material peeling step, and the like, and self-discharge becomes difficult. Also,
When the volume resistivity and the surface resistivity are below the above ranges, the decay of the charging potential is accelerated, which is advantageous for static elimination by self-discharge, but the current at the time of transfer flows in the surface direction, and toner scattering occurs. . Therefore, the volume resistivity and the surface resistivity of the intermediate transfer belt 10 in the present invention must be within the above ranges. The intermediate transfer belt 1
The measurement of the volume resistivity and the surface resistivity of 0 is performed by using an HRS probe (inner electrode diameter: 5.9 mm, ring electrode inner diameter: 11 m) with a high resistivity meter (Mitsubishi Chemical Corporation: Hiresta IP).
m) and connect 100 V to the front and back of the intermediate transfer belt 10.
(Surface resistivity is 500 V). The value after 10 seconds from the application of the voltage was used.

Reference numeral 19 denotes a belt cleaning unit which can be brought into contact with and separated from the intermediate transfer belt 10.
And a contact / separation mechanism 26 for contacting / separating the yellow image of the first color.
While the third and fourth colors are being transferred by the belt, they are separated from the surface of the intermediate transfer belt 10 by the contact / separation mechanism 26, and when the secondary transfer is performed, they are pressed against each other at a predetermined timing to clean the remaining toner. A belt position detection mark 23 is provided at an end of the intermediate transfer belt 10, and by starting an image forming process of each color at a timing when the mark is detected by the mark sensor 24, an accurate color overlap of each color image is performed. It becomes possible.

Reference numeral 15 denotes a secondary transfer unit, which comprises a secondary transfer bias roller 14, and a contact / separation mechanism 16 for bringing the secondary transfer bias roller 14 into and out of contact with the intermediate transfer belt 10. . The secondary transfer bias roller 14 is configured by coating a metal core such as stainless steel (SUS) with an elastic body such as urethane adjusted to a resistance value of 10 ⁶ to 10 ¹⁰ Ω by a conductive material. ing. Here, if the resistance value of the secondary transfer bias roller 14 exceeds the above range, the current hardly flows, so that it is necessary to apply a higher voltage to obtain the necessary transfer property, and the power supply cost increases. Invite. In addition, since a high voltage is applied, a discharge occurs in a gap before and after the transfer portion nip, and white spots are generated on the halftone image due to the discharge. Conversely, if the resistance value of the secondary transfer bias roller 14 falls below the above range, transferability between a multi-color image portion (for example, a three-color superimposed image) and a single-color image portion existing on the same image becomes incompatible. This is because the resistance value of the secondary transfer bias roller 14 is low, so that a sufficient current flows to transfer a single-color image portion at a relatively low voltage, but it is most suitable for a single-color image portion to transfer a multi-color image portion. Since a voltage value higher than the required voltage is required, if the voltage is set to a value at which the multi-color image portion can be transferred, the transfer current becomes excessive for a single-color image, resulting in a reduction in transfer efficiency.

The resistance value of the secondary transfer bias roller 14 is measured by using a secondary transfer bias roller 1 on a conductive metal plate.
4 is installed and flows when a voltage of 1000 V is applied between the metal core and the metal plate in a state where a load of 4.9 N on one side (a total of 9.8 N on both sides) is applied to both ends of the metal core. It was calculated from the current value. A driving force is applied to the secondary transfer bias roller 14 by a driving gear (not shown), and its peripheral speed is adjusted to be substantially the same as the peripheral speed of the intermediate transfer belt 10.

The secondary transfer bias roller 14 is normally separated from the surface of the intermediate transfer belt 10, but transfers the four-color superimposed image formed on the surface of the intermediate transfer belt 10 to a transfer material serving as a second image carrier. The transfer to the transfer material 22 is performed by applying a predetermined bias voltage from the high-voltage power supply 100 by being pressed by the contact / separation mechanism 16 in a timely manner when performing the batch transfer to the transfer material 22. The transfer material 22 is fed by the feed roller 25 and the registration roller 21 at the timing when the leading end of the four-color superimposed image on the surface of the intermediate transfer belt 10 reaches the secondary transfer position. The four-color superimposed image transferred to the transfer material 22 is fixed by the fixing unit 17 and then discharged to a discharge tray (not shown).

When forming a full-color image, first, the photosensitive member 1
Is uniformly charged by the charger 4 and then exposed to light (optical writing device comprising a laser light source, an optical deflector and an imaging optical system, or light comprising an LED array and an imaging optical element). An image is written by exposing the electrostatic latent image on the photoreceptor 1 to a one-component developer composed of yellow toner by a yellow developing device 6. And becomes a yellow image (yellow toner image). The belt transfer roller 11 applies a transfer bias from a high-voltage power supply (not shown) to contact the back surface of the intermediate transfer belt 10 to apply a charge, thereby transferring the yellow image on the photoconductor 1 to the intermediate transfer belt 10.
Transfer to After the transfer of the yellow image, the photoconductor 1 is cleaned by the photoconductor cleaning unit 2.

Next, the photoreceptor 1 is uniformly charged by the charger 4 and then exposed by the exposure means 5 to form an electrostatic latent image, thereby writing an image. The electrostatic latent image is visualized by a magenta developing device 7 with a one-component developer composed of magenta toner to form a magenta image (magenta toner image). A transfer bias is applied to the belt transfer roller 11 from a high-voltage power supply, and the magenta image on the photoconductor 1 is transferred onto the intermediate transfer belt 10 by superimposing the yellow image on the intermediate transfer belt 10 by applying a charge by contacting the back surface of the intermediate transfer belt 10. Let it. After the transfer of the magenta image, the photosensitive member 1
Is cleaned by the photoconductor cleaning unit 2.

Next, the photoreceptor 1 is uniformly charged by the charger 4 and then exposed by the exposing means 5 to form an electrostatic latent image, thereby writing an image. The electrostatic latent image is visualized by a cyan developing device 8 with a one-component developer composed of cyan toner to be a cyan image (cyan toner image). The belt transfer roller 11 is applied with a transfer bias from a high-voltage power supply and contacts the back surface of the intermediate transfer belt 10 to apply a charge, thereby superimposing a cyan image on the photoconductor 1 on the intermediate transfer belt 10 with a yellow image and a magenta image. Transfer together. After the transfer of the cyan image, the photoconductor 1 is cleaned by the photoconductor cleaning unit 2.

Further, the photoreceptor 1 is uniformly charged by the charger 4 and is then exposed by the exposing means 5 to form an electrostatic latent image, thereby writing an image. The electro-latent image is visualized by a black developing device 9 with a one-component developer composed of black toner to become a black image (black toner image). The belt transfer roller 11 is applied with a transfer bias from a high-voltage power supply and contacts the back surface of the intermediate transfer belt 10 to apply a charge, thereby converting the black image on the photoconductor 1 to the intermediate transfer belt 10 as a yellow image, a magenta image, and a cyan image. The image is superimposed and transferred. After the transfer of the black image, the photoconductor 1 is cleaned by the photoconductor cleaning unit 2.

A full-color image (four-color superimposed image) on the intermediate transfer belt 10 is collectively transferred by a secondary transfer bias roller 14 to a transfer material 22 fed from a feeder by a feed roller 25 and a registration roller 21. The image that has been secondarily transferred and transferred from the intermediate transfer belt 10 to the transfer material 22 is fixed by the fixing unit 17, and the fixed transfer material 22 is discharged to a discharge unit (not shown).

The color image forming apparatus of this embodiment is
A single-color mode for forming an image of any one of yellow, magenta, cyan, and black;
A two-color mode in which images of two colors of cyan and black are superimposed and a three-color mode in which images of three colors of yellow, magenta, cyan, and black are superimposed, and four colors as described above A full-color mode for forming a superimposed image is provided, and these modes can be designated by an operation unit (not shown).

When one of the single-color mode, the two-color mode, and the three-color mode is designated, an image of each color of yellow, magenta, cyan, and black is formed on the photosensitive member 1 in the above-described full-color mode. Instead of transferring the image to the intermediate transfer belt 10, a single-color image corresponding to the single-color mode is formed on the photoconductor 1, and
0, an operation of forming a two-color image according to the two-color mode on the photoconductor 1 and transferring it to the intermediate transfer belt 10, or an operation of transferring the three-color image according to the three-color mode to the photoconductor 1. An operation of forming a single color image, a two-color superimposed image, or a three-color superimposed image on the intermediate transfer belt 10 is performed.
The sheet is transferred onto the transfer material 22 and fixed by the fixing unit 17 and then discharged.

Here, when the image forming operation for forming the superimposed images of a plurality of colors on the transfer material 22 is continuously performed by the number of sheets set by the operation unit, the rear end of the transfer material 22 can sufficiently move the secondary transfer bias roller 14. High-voltage power supply 1
00, the transfer bias voltage applied to the secondary transfer bias roller 14 is turned off.
The secondary transfer bias roller 14 transfers the toner image of the next page above.
The secondary transfer bias roller 14 is separated from the intermediate transfer belt 10 by the contact / separation mechanism 16 so as not to adhere to the intermediate transfer belt 10.

In the image forming apparatus according to the present invention, the toner particle diameter of the toner used in each of the developing units 6 to 9 is desirably in the range of 4 to 10 μm in volume average particle diameter. In the case of the particle size, it causes background contamination during development, deteriorates fluidity, and is liable to agglomerate. Conversely, if the particle size is larger than the above range, it is not possible to obtain a high-definition image due to toner scattering or deterioration of resolution. Therefore, in this embodiment, a toner having a volume average particle diameter of 7.5 μm was used.

The intermediate transfer member used in the image forming apparatus according to the present invention has at least an elastic layer. As the material of the elastic layer of the intermediate transfer member, rubber, elastomer, resin and the like can be used. For example, as rubber and elastomer, natural rubber, epichlorohydrin rubber, acrylic rubber, silicone rubber, fluorine rubber, polysulfide rubber,
Polynorbornene rubber, isoprene rubber, styrene-butadiene rubber, butadiene rubber, butyl rubber, ethylene-propylene rubber, ethylene-propylene copolymer,
Chloroprene rubber, chlorosulfonated polyethylene, chlorinated polyethylene, acrylonitrile butadiene rubber,
One type from urethane rubber, syndiotactic 1,2-polybutadiene, hydrogenated nitrile rubber, and thermoplastic elastomer (for example, polystyrene, polyolefin, polyvinyl chloride, polyurethane, polyamide, polyester, and fluororesin) Alternatively, two or more types can be used.

As the resin, phenol resin, epoxy resin, polyester resin, polyester polyurethane resin, polyethylene, polypropylene, polybutadiene, polyvinylidene chloride, ionomer resin, polyurethane resin, silicone resin, fluorine resin, ketone resin,
Polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-butadiene copolymer, styrene
Vinyl chloride copolymer, styrene-vinyl acetate copolymer,
Styrene-maleic acid copolymer, styrene-acrylate copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-
Butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-phenyl acrylate copolymer, etc.), styrene-methacrylate copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate) Styrene-based resins such as styrene or styrene-phenyl methacrylate copolymer), styrene-α-methyl methacrylate copolymer, and styrene acrylonitrile-acrylate copolymer. Polymer or copolymer),
Methyl methacrylate resin, butyl methacrylate resin, ethyl acrylate resin, butyl acrylate resin, modified acrylic resin (silicone modified acrylic resin, vinyl chloride resin modified acrylic resin, acrylic urethane resin, etc.),
Vinyl chloride resin, styrene-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer, rosin-modified maleic acid resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral resin, polyamide resin, modified polyphenylene oxide resin, etc. , One or more types can be used.

Further, in order to adjust the resistance of the intermediate transfer member, various conductive agents can be added to the above-mentioned rubber, elastomer and resin. Examples of the conductive agent include carbon, metal powders such as aluminum and nickel, metal oxides such as titanium oxide, quaternary ammonium salt-containing polymethyl methacrylate, polyvinylaniline, polyvinylpyrrole, polydiacetylene, polyethyleneimine, and boron-containing polymer compounds. And one or two or more of conductive polymer compounds such as polypyrrole.

When the intermediate transfer drum 29 as shown in FIG. 2 is used as the intermediate transfer member used in the image forming apparatus according to the present invention, the cylindrical conductive base 30 constituting the intermediate transfer drum 29 is made of iron. A metal or alloy such as stainless steel, aluminum, copper, or a conductive resin containing carbon or the like can be used. As a method for manufacturing the same, rubber,
The elastic layer 31 is formed by injection molding, melt molding, or spray coating of an elastomer or resin.

Next, when the intermediate transfer belt 10 is used as the intermediate transfer member used in the image forming apparatus according to the present invention as in the embodiment of FIG. 1, a core layer 32 is provided in order to prevent elongation thereof. Is preferred. In this case, a structure in which the core layer 32 is embedded in the elastic layer 31 as shown in FIG. 3 or a structure in which the elastic layer 31 is laminated on the core layer 32 as shown in FIG. The layer 31 is reinforced to have a belt shape.

It is important that the material of the core layer 32 is a material that is not easily stretched and does not hinder the smooth rotation of the intermediate transfer belt, and the preferable range of the tensile elastic modulus is 1 × 10 ² MPa or more. × 10 ⁵ MPa or less. If the tensile elasticity is lower than this value, the belt expands and contracts when the intermediate transfer belt is driven to rotate, which causes color shift in the primary transfer portion during full-color image formation.
Further, even during monochromatic printing, the above-described expansion and contraction causes an error in the image length in the rotation direction of the intermediate transfer belt. On the other hand, if it is larger than the above range, the intermediate transfer belt hardly elongates, so that the close contact with the drive roller 13 is not sufficient, and color misregistration due to slipping at the drive roller 13 is likely to occur. To prevent this, the intermediate transfer belt 10
It is necessary to increase the strength of the rollers for supporting the intermediate transfer belt 10 such as the driven rollers 12a and 12b and the frame for supporting the rollers. It is not preferable in terms of cost and cost.

The core layer 32 is preferably made of resin in the form of a film or fiber. Examples of the core layer 32 in which the resin is formed into a film shape include known thermoplastic resins, thermoplastic elastomers and thermosetting resins, and specifically, polycarbonate resins, polyester resins, polyamide resins, and polyimide resins. , Polyurethane resin, polyether resin, polyvinyl resin,
Resins such as a polyvinylidene-based resin, a polyetheretherketone resin, and a polysulfone resin can be used. In this case, the resin core layer 32 may be formed by laminating a plurality of the above-described resins, or may be used in combination with a fiber layer described later.

The core layer 32 using fibers can be formed using a known woven fabric or nonwoven fabric.
Natural fibers such as hemp, wool, silk and cotton, regenerated fibers such as viscose, polyester, nylon (nylon 6, 66, 46)
Woven fabric of synthetic fibers such as vinylon, vinylidene chloride, polyolefins (polyethylene, polypropylene, etc.), semi-synthetic fibers such as acetate, semi-synthetic fibers such as acetate, aramid fibers, polyvinyl alcohol fibers, and polyacrylonitrile fibers. Or non-woven fabric can be used. In this case, the fabric structure of the woven fabric can be appropriately selected from plain weave, oblique weave, satin weave, and a combination thereof, but in particular, from the viewpoint of robustness, economy, etc. A cloth is preferably used.

The fiber core layer 32 using the above-mentioned fibers is a core layer 32 having a multi-layer structure in which a plurality of the woven fabrics or non-woven fabrics are laminated.
In this case, the thickness of the fiber core layer 32 may be set to 0.1.
The range is preferably from 01 to 1.5 mm, particularly from 0.05 to 1.5 mm.
More preferably, it is in the range of 0.5 mm. When the thickness of the fiber core layer 32 is less than 0.01 mm, the function of the fiber core layer 32 for preventing elongation becomes poor, and deformation such as elongation occurs. Become. On the other hand, if it exceeds 1.5 mm, the flexibility of the belt is impaired, and the rotation of the belt cannot be smoothly performed.

Further, in both the intermediate transfer drum and the intermediate transfer belt, contamination (bleed) of the photosensitive member, prevention of toner adhesion (filming),
It is preferable to form the surface coating layer 33 made of various resins for the purpose of controlling the charge of the toner, adjusting the surface resistance, controlling the friction coefficient, and the like. The resin for forming the surface coating layer 33 can be appropriately selected from known materials and used, and specifically, a fluororesin, a urethane resin, a polycarbonate resin, a polyvinyl acetal resin, an acrylic resin, a silicone resin, a polyester resin Resin, amino resin,
Epoxy resin, polyamide resin, phenol resin, alkyd resin, melamine resin, ketone resin, ionomer resin, polybutadiene resin, chlorinated polyethylene, vinylidene chloride resin, acrylic / urethane resin, acrylic
Silicone resin, ethylene / vinyl acetate resin, vinyl chloride / vinyl acetate resin, styrene / acrylic resin, styrene / butadiene resin, styrene / maleic acid resin, ethylene / acrylic resin, etc. can be used, and one or more of these can be used. They can be used in combination.

In the present invention, the surface coating layer 33 contains fine particles having a diameter of 1 μm or less. Examples of the fine particles include carbon, metal powder, metal oxide powder, conductive agents such as ionic substances, and polytetrafluoroethylene to reduce the friction coefficient, and fine particles of a fluororesin such as polyvinylidene fluoride, molybdenum sulfide, and graphite. It is possible to add a fine powder of an inorganic substance or the like. In particular, when the purpose is to reduce the toner adhesion on the surface and prevent the hollow phenomenon, it is preferable to contain fine particles of a fluororesin. Here, the diameter of the fine particles is 1 μm.
If it exceeds 300, it becomes difficult for a part of the particles to protrude to the surface, and the occurrence of voids is observed from the beginning. In addition, in the case of durability, toner adhesion (filming) proceeds, which causes image unevenness. On the other hand, when the resin particles exceed 1 μm, the surface micro hardness of the surface of the intermediate transfer member is increased, and the surface micro hardness is varied, thereby impairing the effect of the present invention. Therefore, the surface coating layer 3
The diameter of the fine particles contained in 3 is preferably 1 μm or less.

On the other hand, the thickness of the surface coating layer 33 is 0.5 to
250 μm, particularly preferably in the range of 1 to 100 μm. If the thickness is less than 0.5 μm, the effect of the surface coating layer cannot be sufficiently obtained, or the elastic layer 31 is exposed at a portion where the surface coating layer is not formed. But sometimes 2
If it exceeds 50 μm, the surface micro hardness becomes too high, and the effect of the present invention cannot be sufficiently obtained. That is, the flexibility of the surface coating layer 33 becomes poor, so that it may not be possible to follow the elastic deformation of the elastic layer 31, and this is not preferable in terms of cost.

[0039]

Next, specific embodiments of the present invention will be described.

(Embodiment 1) In this embodiment, NBR rubber and EPD are used as materials for forming the elastic layer 31 of the intermediate transfer member.
A rubber compound obtained by kneading 75 parts by weight and 25 parts by weight of M rubber was used. 20 parts by weight of carbon black was added as a conductive agent. After covering the outer periphery of the cylindrical mold with the rubber compound tube, an endless core layer 32 made of plain woven polyester yarn having a diameter of 100 μm coated with an adhesive is further covered, and the rubber compound is further laminated and added. Sulfurization was performed. After vulcanization is completed, polyurethane 10 is added to the surface in MEK (methyl ethyl ketone).
A coating obtained by kneading 0 parts by weight and 60 parts by weight of PTFE fine powder is spray-coated, a drying process for removing a solution is performed, and a surface coating layer 33 is formed. Then, the surface coating layer 33 is removed from the mold to obtain an intermediate transfer belt. Was. The particle size of the PTFE fine powder was 0.2 μm.

FIG. 5 is a graph plotting the surface microhardness over time. As shown in FIG. 5, when the peak value of the surface micro hardness of the intermediate transfer belt and the value after 3 seconds from the peak (hereinafter, 3 seconds value) were measured, the peak value was 55 degrees and the 3 seconds value was: The value was 54 degrees. The reason why the 3-second value was measured was that it was found from the peak value of the surface microhardness that the subsequent fluctuation in hardness was balanced within approximately 3 seconds. Therefore, there is no meaning even if it is within 3 seconds or 3 seconds or more.
The JIS-A hardness of the elastic layer 31 was 48 degrees.
Further, the tensile modulus of the core layer 32 is 5 × 10
It was ² MPa. In addition, the measurement of the surface micro hardness is based on M
The measurement was performed using ICRO DUROMETER MD-1 (manufactured by Kobunshi Keiki Co., Ltd.). The above-described intermediate transfer belt is mounted on a color image forming apparatus having the configuration shown in FIG. 1, and a full-color image is formed using 80 g / cm paper and "Sazanami" (Japanese paper for full-color printing: manufactured by Japan Business Supply Co., Ltd.) as transfer paper. After printing, "missing", "transfer of uneven paper", "white at primary transfer", "color shift",
Each evaluation of "image elongation" was performed by the following evaluation method. Also,
The measurement results and evaluation results of the intermediate transfer belt are shown in Table 1 below.

{Evaluation of hollow area} [｝]: No hollow area is observed even by visual observation and loupe (15 times). [○]: Although no void was seen visually, the loupe (15
), A minute hollow is observed. [△]: A fine hollow is visually observed, but there is no practical problem. [X]: Remarkable hollowing is observed.

<< Evaluation of transfer omission of uneven paper >> [◎]: Not observed at all. [O]: Very slightly observed in the recess. [△]: A level slightly observed in the concave portion, but having no practical problem. [X]: Remarkable omission is observed.

{Evaluation of white spots during primary transfer} [転 写]: Not observed at all. [O]: Very slightly observed. [△]: Slightly observed, but not practically problematic. [X]: Remarkable omission is observed.

{Evaluation of color misregistration} Observation was made visually and with a loupe (30 times). [◎]: No color shift is observed. [○]: Not observed visually, but very slightly (50 μm or less) observed with a loupe. [△]: Slight (100 μm or less) observed with a loupe, but at a level that does not pose any practical problems. [X]: Color shift is visually observed.

{Evaluation of Image Elongation} Glass Scale (No.
1972: manufactured by PEAK). Judgment was made based on the magnification ratio with the theoretical value in the A3 vertical direction. [◎]: No elongation (magnification ratio of 0.1% or less). [O]: Elongation occurs very slightly (magnification ratio of 0.3% or less). [△]: Slight elongation occurs, but practically no problem (magnification ratio of 0.5% or less). [X]: Remarkable elongation occurred.

(Embodiment 2) In this embodiment, the surface coating layer 3
Particle size of PTFE fine powder added to paint No. 3 is 0.9 μm
Other than the above, it is the same as the first embodiment. When the peak value and the 3-second value of the surface micro hardness of the intermediate transfer belt were measured, the peak value was 58 degrees and the 3-second value was 55 degrees. Table 1 below shows the measurement results and the evaluation results of the intermediate transfer belt.

Embodiment 3 In this embodiment, as the material of the core layer 32, polyvinyldene fluoride (PVDF) is manufactured by extrusion molding to a thickness of 100 μm and used. Polyurethane rubber adjusted to JIS-A) was laminated by dipping to a thickness of 300 μm. When the peak value and the 3-second value of the surface micro hardness of the intermediate transfer belt were measured, the peak value was 52 degrees and the 3-second value was 50 degrees. Also,
The JIS-A hardness of the elastic layer 31 was 63 degrees. The tensile modulus of the core layer 32 is 1.2 × 10 ² MP.
a. Table 1 below shows the measurement results and the evaluation results of the intermediate transfer belt.

(Embodiment 4) In this embodiment, NBR rubber and EPDM are used as the material for the elastic layer 31 of the intermediate transfer member.
It is the same as Example 1 except that a rubber compound obtained by kneading 25 parts by weight and 75 parts by weight of rubber was used. When the peak value and the 3-second value of the surface micro hardness of the intermediate transfer belt were measured, the peak value was 68 degrees and the 3-second value was 65 degrees. The JI of the elastic layer 31
The SA hardness was 63 degrees. Table 1 below shows the measurement results and the evaluation results of the intermediate transfer belt.

(Embodiment 5) In this embodiment, polyisoprene (I) is used as a material for forming the elastic layer 31 of the intermediate transfer member.
R) and 40 parts by weight of polybutadiene (BR),
Same as Example 1 except that a rubber compound kneaded with 60 parts by weight was used. When the peak value and the 3 second value of the surface micro hardness of the intermediate transfer belt were measured,
Peak value: 32 degrees, value for 3 seconds: 30 degrees.
The JIS-A hardness of the elastic layer 31 was 30 degrees.
Table 1 below shows the measurement results and the evaluation results of the intermediate transfer belt.

COMPARATIVE EXAMPLE 1 In this comparative example, an elastic layer 31 was formed using chloroprene rubber adjusted to a hardness of 65 degrees (JIS-A), and PTFE was coated on 100 parts by weight of an acrylic-modified polyurethane solvent on the surface. Example 1 is the same as Example 1 except that a paint containing 60 parts by weight of fine powder and 15 parts by weight of carbon black added was spray-coated. When the peak value and the 3-second value of the surface micro hardness of the intermediate transfer belt were measured, the peak value was 69 degrees and the 3-second value was 62 degrees. Table 1 below shows the measurement results and the evaluation results of the intermediate transfer belt.

(Comparative Example 2) In this comparative example, a paint obtained by kneading 100 parts by weight of polyurethane and 60 parts by weight of PTFE fine powder in MEK (methyl ethyl ketone) was spray-coated on the surface of the elastic layer 31 of Example 4. The intermediate transfer belt on which the surface coating layer 33 was formed through a drying process for removing the solution was obtained. The particle size of the PTFE fine powder was 1.2 μm. When the peak value and the 3-second value of the surface micro hardness of the intermediate transfer belt were measured, the peak value was 72 degrees and the 3-second value was 70 degrees. Table 1 below shows the measurement results and the evaluation results of the intermediate transfer belt.

Comparative Example 3 This comparative example is the same as Example 3 except that polyvinyldene fluoride (PVDF) was manufactured to have a thickness of 60 μm by extrusion and used as the material of the core layer 32. The tensile elastic modulus of the core layer 32 is 8 ×
It was 10 MPa. Table 1 below shows the measurement results and the evaluation results of the intermediate transfer belt. Table 1 below shows that
It is a list of the measurement result and evaluation result of Examples 1-5 and Comparative Examples 1-3.

[0054]

[Table 1]

The embodiments described above are described to facilitate understanding of the present invention, and do not limit the present invention. For example, in the above-described embodiment, the description has been made using the photosensitive drum as the first image carrier, but the present invention is not limited to this, and is applicable to all image carriers such as a photosensitive belt. It is. further,
Although the transfer roller was used as the primary transfer means and the secondary transfer means, the transfer belt, the transfer brush, the transfer blade,
The present invention can be applied to an image forming apparatus using a contact transfer method such as a transfer plate.

[0056]

As described above, according to the first aspect of the present invention, the step of forming a toner image on the first image bearing member and firstly transferring the toner image to the intermediate transfer member is performed one or more times. After performing, the intermediate transfer body used in an intermediate transfer type image forming apparatus for secondary transfer of the toner image on the intermediate transfer body to a second image carrier, having at least an elastic layer, The surface microhardness of the toner carrying surface for carrying the toner image has a peak value of the surface microhardness in a range of 30 to 70 degrees as measured by a micro rubber hardness meter (for example, MD-1 manufactured by Kobunshi Keiki Co., Ltd.). And the difference ΔD between the surface microhardness 3 seconds after the peak of the surface microhardness and the peak value of the surface microhardness is set to 5 degrees or less, so that the secondary transfer portion While deformed Transfer member surface becomes possible to return to the shape before deformation before reaching the primary transfer portion, it is possible to prevent white spots during primary transfer caused by the deformation of the intermediate transfer member surface.

According to the second aspect of the present invention, after the step of forming a toner image on the first image bearing member and firstly transferring the toner image to the intermediate transfer member is performed once or plural times, the intermediate transfer member The intermediate transfer member used in the intermediate transfer type image forming apparatus for secondary transfer of the upper toner image to a second image carrier, having at least a surface coating layer and an elastic layer,
The surface coating layer contains fine particles having a particle diameter of 1 μm or less, and the surface micro hardness of the toner carrying surface for carrying the toner image is measured by a micro rubber hardness meter (for example, MD-1 manufactured by Kobunshi Keiki Co., Ltd.). The peak value of the surface microhardness is in the range of 30 to 70 degrees in the measurement, and the difference between the surface microhardness and the peak value of the surface microhardness three seconds after the peak value of the surface microhardness is shown. Δ
By setting D at 5 degrees or less, it is possible to prevent hollowing out, and it is possible for the surface of the intermediate transfer member deformed in the secondary transfer portion to return to the shape before deformation before reaching the primary transfer portion. Thus, white spots at the time of primary transfer caused by deformation of the surface of the intermediate transfer member can be prevented.

According to the third aspect of the present invention, in the intermediate transfer body according to the first or second aspect, the intermediate transfer drum has a structure in which an elastic layer is provided on a conductive cylindrical base, so that color shift in the axial direction is achieved. And a high-quality full-color image free from the occurrence of image defects can be obtained. Further, in the invention according to claim 4, in the intermediate transfer body according to claim 1 or 2, the intermediate transfer belt includes an intermediate transfer belt having a structure in which an elastic layer is provided on an endless core layer, so that color shift does not occur. A high-quality full-color image can be obtained. Further, in the invention according to claim 5, in the intermediate transfer member according to any one of claims 1 to 4, the JIS-A hardness of the elastic layer is set to be 30 degrees to 70 degrees, It is possible to obtain a high-quality full-color image in which no character collapse occurs and no void occurs.

According to a sixth aspect of the present invention, in the intermediate transfer member according to the fourth or fifth aspect, the core layer has a film shape, and the core layer has a tensile elasticity of 1 × 1.
By setting the pressure to 0 ² MPa or more and 3 × 10 ⁵ MPa or less, a high-quality full-color image free from color misregistration due to elongation of the intermediate transfer belt and belt slippage during driving can be obtained. Further, in the invention according to claim 7, in the intermediate transfer member according to claim 4 or 5, the core layer is a fiber, and the core layer has a tensile modulus of 1 × 10 ^2.
By setting it to not less than MPa and not more than 3 × 10 ⁵ MPa,
A high-quality full-color image free from color misregistration due to the extension of the intermediate transfer belt and belt slippage during driving can be obtained. Further, in the invention according to claim 8, in the intermediate transfer member according to any one of claims 2 to 7, the fine particles having a particle size of 1 μm or less are made of fluororesin fine particles, so that the hollow particles do not cause hollowing. High quality full-color images can be obtained.

According to the ninth aspect of the present invention, the first image carrier, charging means for charging the first image carrier to a predetermined potential, and electrostatic charging on the charged first image carrier. Exposure means for forming a latent image, developing means for visualizing the electrostatic latent image formed on the first image carrier with toner of a plurality of colors, and a toner image on the first image carrier in order. Image having primary transfer means for transferring onto an intermediate transfer member and secondary transfer means for contacting the back surface of a second image carrier and transferring a toner image on the intermediate transfer member to the second image carrier In the forming apparatus, by using the intermediate transfer member according to any one of claims 1 to 8 as the intermediate transfer member, irrespective of the surface properties of the transfer paper, white spots, hollow spots, character collapse, High quality full-color images can be transferred without color shift It is possible. According to a tenth aspect of the present invention, in the image forming apparatus according to the ninth aspect,
10. The toner according to claim 9, wherein a volume average particle diameter of the toner used in the developing unit is in a range of 4 to 10 μm.
In addition to the effects described above, it is possible to prevent the occurrence of background contamination, toner scattering, and the like, and to obtain a high-definition and high-quality full-color image.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a color image forming apparatus showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram of an intermediate transfer drum.

FIG. 3 is an explanatory diagram of an intermediate transfer belt having a structure in which a core layer is embedded in an elastic layer.

FIG. 4 is an explanatory diagram of an intermediate transfer belt having a structure in which an elastic layer is laminated on a core layer.

FIG. 5 is a graph illustrating a peak value and a 3-second value of surface micro hardness.

FIG. 6 is an explanatory diagram for explaining a hollow defect phenomenon.

FIG. 7 is an explanatory diagram of a state where transfer of uneven paper occurs.

FIG. 8 is an explanatory diagram of a state of occurrence of primary transfer omission due to deformation of the surface of the intermediate transfer member.

[Explanation of symbols]

 1: Photoconductor (first image carrier) 2: Photoconductor cleaning unit 3: Cleaning blade 4: Charger 5: Exposure means 6: Yellow developing device 7: Magenta developing device 8: Cyan developing device 9: Black developing device 10: Intermediate transfer belt (intermediate transfer body) 11: Primary transfer bias roller (primary transfer means) 12a, 12b: driven roller 13: drive roller 14: secondary transfer bias roller (secondary transfer means) 15: secondary transfer unit 16: Contact / separation mechanism 17: Fixing means 19: Belt cleaning unit 21: Registration roller 22: Transfer material (second image carrier) 23: Belt position detection mark 24: Mark sensor 25: Feed roller 26: Contact / separation mechanism 27: Press spring 29: Intermediate transfer drum (intermediate transfer body) 30: Conductive substrate 31: Elastic layer 32: Core layer 33: Surface coating 100: high-voltage power supply

Claims (10)

[Claims] After performing a step of forming a toner image on a first image carrier and performing a primary transfer of the toner image to an intermediate transfer member once or a plurality of times, the toner image on the intermediate transfer member is transferred to a first image carrier. The intermediate transfer member used in an image forming apparatus of an intermediate transfer system for secondary transfer to a second image carrier, wherein the intermediate transfer member has at least an elastic layer, and a surface micro hardness of a toner carrying surface for carrying the toner image is micro The surface micro hardness has a peak value in the range of 30 to 70 degrees as measured by a rubber hardness meter, and the surface micro hardness and the surface micro hardness 3 seconds after the peak value of the surface micro hardness is shown. An intermediate transfer member, wherein a difference ΔD from a peak value is 5 degrees or less. 2. After performing a step of forming a toner image on a first image carrier and performing a primary transfer of the toner image to an intermediate transfer body once or a plurality of times, the toner image on the intermediate transfer body is subjected to a second process. The intermediate transfer member used in an intermediate transfer type image forming apparatus that performs secondary transfer to a second image carrier, wherein the intermediate transfer member has at least a surface coating layer and an elastic layer, and the surface coating layer has a particle size of 1 μm or less. The surface micro-hardness of the toner carrying surface containing fine particles and carrying the toner image has a peak value of the surface micro-hardness in a range of 30 to 70 degrees as measured by a micro rubber hardness meter, and An intermediate transfer member, wherein the difference ΔD between the surface microhardness 3 seconds after the point when the hardness peak value is shown and the peak value of the surface microhardness is 5 degrees or less. 3. The intermediate transfer member according to claim 1, further comprising an intermediate transfer drum having a structure in which an elastic layer is provided on a conductive cylindrical substrate. 4. The intermediate transfer member according to claim 1, further comprising an intermediate transfer belt having a structure in which an elastic layer is provided on an endless core layer. 5. The intermediate transfer member according to claim 1, wherein the elastic layer has a JIS-A hardness of 30 to 70 degrees. 6. The intermediate transfer member according to claim 4, wherein said core layer is in the form of a film, and said core layer has a tensile modulus of 1 × 10 ² MPa or more and 3 × 10 ⁵ MPa or less. An intermediate transfer member characterized by the following. 7. The intermediate transfer member according to claim 4, wherein the core layer is a fiber, and the core layer has a tensile modulus of 1 × 10 ² MPa or more and 3 × 10 ⁵ MPa or less. An intermediate transfer member, characterized in that: 8. The intermediate transfer member according to claim 2, wherein the fine particles having a particle diameter of 1 μm or less are fluororesin fine particles. 9. A first image bearing member, charging means for charging the first image bearing member to a predetermined potential, and exposure for forming an electrostatic latent image on the charged first image bearing member. Means, developing means for visualizing the electrostatic latent image formed on the first image carrier with toner of a plurality of colors, and sequentially transferring the toner image on the first image carrier onto the intermediate transfer body An image forming apparatus, comprising: a primary transfer unit that performs a transfer operation; and a secondary transfer unit that contacts a back surface of a second image carrier and transfers a toner image on the intermediate transfer member to the second image carrier. An image forming apparatus using the intermediate transfer member according to claim 1 as a transfer member. 10. The image forming apparatus according to claim 9, wherein the toner used in said developing means has a volume average particle diameter in a range of 4 to 10 μm.