JP2001092268A - Image-forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image-forming device capable of forming a high-quality image even though a releasing agent holds and contacts on the intermediate transfer body. SOLUTION: This device is provided with a photoreceptor on which a toner image is formed, a circularly moving intermediate transfer body 2 to which the toner image on the photoreceptor is transferred at a prescribed primary transfer position and which carries the toner image transferred at the primary transfer position and feeds it to a prescribed secondary transfer position, and a transfer part transferring the toner image carried on the intermediate transfer body to a recording medium at the secondary transfer position. The intermediate transfer body 2 has a surface where plural projecting parts (c) are dispersed and holds the releasing agent S at a part (h) other than the plural projecting parts (c) on the surface.

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, such as a copying machine or a printer, for forming an image with toner using an electrophotographic method, and more particularly to an image forming apparatus which is transferred at a predetermined primary transfer position. The present invention relates to an image forming apparatus having an intermediate transfer body that carries a toner image transferred at a position and conveys the toner image to a predetermined secondary transfer position.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus using an electrophotographic method, such as a copying machine, a printer, and a facsimile, has a photoconductor on which a toner image is formed, and a transfer for transferring the toner image onto a recording medium such as recording paper. And a fixing unit for fixing the toner image on the recording medium. In this image forming apparatus,
First, the surface of a photoconductive photoconductor made of an inorganic or organic material is uniformly charged, and the charged photoconductor is irradiated with a laser beam that modulates an image signal to partially expose the photoconductor surface. By removing the charge, an electrostatic latent image is formed. By supplying toner charged to the same polarity as the charged photoconductor on the photoconductor on which the electrostatic latent image is formed, the electrostatic latent image is developed and a toner image is formed on the photoconductor. It is formed. The toner image is electrostatically transferred to a recording medium such as recording paper by a transfer unit directly or via an intermediate transfer body that moves cyclically while being supported by a plurality of rolls. The toner image on the recording medium is fixed on the recording medium by the fixing unit, and the image formation is completed.

In such an image forming apparatus, a dry toner is used as the toner supplied onto the photoconductor, and a toner image developed by the toner is transferred directly from the photoconductor to a recording medium electrostatically. The method is widely adopted. However, the transfer efficiency of the toner image depends on the electric field Et applied to the laminated toner forming the toner image, and the electric field Et depends on the thickness of the toner layer and the thickness unevenness of the recording medium represented by paper. And unevenness in electrical properties. Therefore, in the transfer using such an electrostatic transfer method, it is difficult to transfer the toner image uniformly and efficiently onto the recording medium, and the finally formed image tends to have uneven density. In addition, the resolution and dot reproducibility of the image tend to deteriorate due to scattering of the powder toner at the time of transfer.

On the other hand, when a color image is formed, an intermediate transfer member is often used in an image forming apparatus, and a multi-toner image in which toner images of respective colors are superimposed is carried on the intermediate transfer member. When the toner image on the photoreceptor is electrostatically transferred onto the intermediate transfer member that is controlled so as not to have the thickness unevenness and the electric property unevenness, the toner image transferred onto the intermediate transfer member has unevenness. No uniform toner image is obtained. However, when the toner image on the intermediate transfer body is electrostatically transferred to the recording medium, the electric field Et is still nonuniform, and it is difficult to transfer the toner image uniformly and efficiently onto the recording medium. is there. Therefore, in such an electrostatic transfer method, a part of the toner constituting the multi-toned image that is superimposed on the intermediate transfer member is likely to remain on the intermediate transfer member, and the color image transferred to the recording medium is The color balance is liable to be degraded and the quality is deviated. In addition, due to unevenness of the surface of the paper as the recording medium, the paper and the intermediate transfer member do not completely adhere to each other, and a non-uniform gap is generated, and the electric field Et is disturbed. The quality of the image on the recording medium also deteriorates due to the scattering of the toner.

To cope with such a problem that the image quality is deteriorated, Japanese Patent Publication No. 46-41679 discloses that a toner image formed on a photoreceptor is adhesively transferred to an intermediate transfer member, A fusion heat transfer technique for transferring toner while melting it on a recording medium is disclosed. Since this technique transfers a toner image to a recording medium in a non-electrostatic manner, the quality of an image hardly deteriorates during the transfer.

[0006] For example, in Japanese Patent Application Laid-Open No. 2-108072, toner images of respective colors are electrostatically superimposed and transferred onto an intermediate transfer member, and a multi-toner image thus superimposed and transferred onto the intermediate transfer member is further transferred. A technique is disclosed in which a fused multiple toner image is transferred to a recording medium after fusing to obtain a color copy. This technique also non-electrostatically transfers a toner image to a recording medium, so that the image quality hardly deteriorates as described above during the transfer. The transfer in this technique also serves as fixing, and such a fixing method performed together with the transfer is called a transfer fixing method.

An image forming apparatus using this transfer fixing method is disclosed in US Pat. No. 2,990,278 and Japanese Patent Laid-Open No. 5-19.
642, JP-A-5-107950 and JP-A-5-249798, by heating and pressurizing a toner sandwiched between the intermediate transfer body and the recording medium while keeping the intermediate transfer body and the recording medium in close contact with each other, A technique is disclosed in which the recording medium is separated from the intermediate transfer member after cooling until the cohesive force between the heated and pressurized toner becomes larger than the adhesive force between the toner and the intermediate transfer member. With this technique, the transfer efficiency of the toner from the intermediate transfer body to the recording medium is improved, and a high-quality image with good color balance, high gloss, and excellent toner transparency can be obtained.

However, in order to effectively use this technique, it is necessary that the surface layer of the intermediate transfer member has excellent heat release and toner releasability. As a material suitable for the surface layer of such an intermediate transfer member, a fluorine-based resin obtained by dispersing a fluorine-based resin in a fluorine-based resin or fluororubber as used in a conventional fixing device. Materials, and silicone-based materials such as silicone-based resin and silicone-based rubber.

However, an intermediate transfer member using a fluorine-based material as the surface material has low adhesion to a recording medium, and the toner sandwiched between the intermediate transfer member and the recording medium is cooled before the toner is sufficiently cooled. The intermediate transfer member and the recording medium are peeled off, and offset and gloss unevenness occur in the image on the recording medium obtained after the transfer. In order to prevent such a separation between the intermediate transfer member and the recording medium, another contact means is required, and the image forming apparatus becomes complicated and large. Further, since the intermediate transfer body using the fluorine-based material as a surface material has a hard surface, if the height at which the toner constituting the toner image is stacked differs greatly from place to place, the image around the highly stacked toner may be removed. Is not transferred to the recording medium, so-called transfer omission occurs. In addition, the gloss of an image formed by transferring and fixing the toner image differs depending on the height of the toner layer of the toner image, and thus the image tends to have uneven gloss. Further, in the case of an image in which thin lines are close to each other, the thin lines are crushed to be in a state of being stuck in some places. The difficulty of the intermediate transfer body using such a fluorine-based material as the surface material is as follows.
This is particularly noticeable when a multi-toner image of a color image is transferred and fixed. Further, the fluorine-based material is inferior to the silicone-based material in the toner releasability. From these facts, it can be understood that a silicone material is suitable as the surface material of the intermediate transfer member.

[0010]

However, an intermediate transfer member using a silicone-based material as a surface material has a short so-called mold release life, which is represented by the number of prints that can maintain the toner releasability. The inventor of the present invention makes a recording paper adhere to a toner image carried on the surface of an intermediate transfer body using such a surface material, heats and pressurizes the toner of the toner image, and heats and pressurizes the toner. The recording medium was once cooled to below the melting point of the toner, and then the recording paper was peeled off from the intermediate transfer member. An intermediate transfer member using such a silicone-based material as a surface material has a short separation time of about 5,000 prints. It is evaluated as having a mold life.

In order to extend the release life, it is conceivable to supply a release agent such as silicone oil or silicone wax onto the surface of the intermediate transfer member, as in a conventional fixing device.

However, in general, the intermediate transfer member is in contact with the surface of the photoreceptor, and when a release agent such as silicone oil or silicone wax is applied to the surface of the intermediate transfer member, the silicone oil or silicone wax on the intermediate transfer member is removed. The toner adheres to the surface of the photoreceptor, and at the time of development, the toner adheres to the portion of the surface of the photoreceptor where the electrostatic latent image is not formed due to the adhesiveness of the silicone oil or silicone wax. May be disturbed.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an image forming apparatus which forms a high quality image while carrying a release agent on an intermediate transfer member.

[0014]

In order to achieve the above object, an image forming apparatus according to the present invention comprises: an image carrier on which a toner image is formed;
An intermediate transfer member that carries the toner image transferred at the next transfer position and is transferred at the primary transfer position and conveys the toner image to a predetermined secondary transfer position; and the secondary transfer of the toner image carried on the intermediate transfer member The intermediate transfer body has a surface on which a plurality of protrusions are dispersed, and a release agent on a portion of the surface other than the plurality of protrusions. Is held.

In the image forming apparatus according to the present invention, the intermediate transfer member may be configured such that the plurality of protrusions on the surface on which the plurality of protrusions are formed is 5% or more and 20% or less of the total area of the surface. Preferably occupy the area of

In the image forming apparatus of the present invention, the intermediate transfer body is brought into close proximity to or in contact with the intermediate transfer body, and the circulating movement of the intermediate transfer body is located downstream of the secondary transfer position and upstream of the primary transfer position. It is preferable to have a release agent supply unit for supplying the release agent.

The image forming apparatus having the release agent supply unit is located near or in contact with the intermediate transfer body, and is located on the downstream side of the release agent supply unit and the primary transfer position in the circulating movement of the intermediate transfer body. It is preferable to have one or more release agent wiping portions located on the upstream side of the intermediate transfer member for wiping the release agent from the plurality of convex portions of the intermediate transfer member.

In the image forming apparatus having the release agent wiping section, when the release agent wiping section wipes off the release agent from the plurality of convex portions, the intermediate transfer body is provided with the image carrier and the release section. It is preferable to circulate one or more times in a state separated from the mold supply section.

[0019]

Embodiments of the present invention will be described below.

FIG. 1 is a schematic view of an image forming apparatus according to the present embodiment.

An image forming apparatus 10 according to the embodiment shown in FIG.
Is a high-speed / multiple-sheet output machine having four photoconductors for each color in the apparatus corresponding to the image carrier according to the present invention. The four photoconductors are a photoconductor 1Y for Y (yellow), a photoconductor 1M for M (magenta), and a photoconductor 1M for C (cyan).
It consists of a photoconductor 1K for C and K (black). Further, the image forming apparatus 10 includes a light beam scanning unit 9 that forms an electrostatic latent image by exposing the surface of each of the photoconductors with a laser, and a developing unit 5 that supplies a Y toner to the photoconductor 1Y.
A developing unit 5M for supplying M toner to the photoconductor 1M, a developing unit 5C for supplying C toner to the photoconductor 1C, and a developing unit 5K for supplying K toner to the photoconductor 1K;
A primary transfer section 3 which is a transfer electrode for transferring a Y toner image on Y to an intermediate transfer body 2 described later at a primary transfer position for Y toner
Y, a primary transfer portion 3M which is a transfer electrode for transferring the M toner image on the photosensitive member 1M to the intermediate transfer member 2 at the primary transfer position for the M toner, and a C toner image on the photosensitive member 1C for the C toner. A primary transfer portion 3C, which is a transfer electrode for transferring to the intermediate transfer member 2 at the primary transfer position, a corotron for transferring the K toner image on the photoreceptor 1K to the intermediate transfer member 2 at the primary transfer position for K toner, etc. And a primary transfer portion 3K which is a transfer electrode of
While being sandwiched between the respective primary transfer positions by the photoreceptor and the four primary transfer portions, the toner moves so as to circulate in the direction of arrow A, and the toner transferred at each of the primary transfer positions is transferred to each of the primary transfer positions. An endless belt-shaped intermediate transfer body 2 is transported from the transfer position to a predetermined secondary transfer position. At the secondary transfer position, the intermediate transfer body 2 is installed on the surface of the intermediate transfer body 2 on which the toner image is carried. A pressure roll 4_1, which is a roll for pressing the recording paper P, which is a transfer medium for the toner image, against the intermediate transfer body 2, and is arranged to face the pressure roll 4_1 with the intermediate transfer body 2 interposed therebetween. 2 and the heating roller 4_2, which is a roll for heating the toner sandwiched between the recording paper P and the intermediate transfer body 2 and the recording paper P, a driving roll 6_1 for supporting and driving the intermediate transfer body 2, and an intermediate transfer body 2. Intermediate transfer member 2 A mold release that includes tension rolls 6_2 and 6_3 that guide circulation, and a paper peeling roll 6_4 that peels off the recording paper P that is in close contact with the intermediate transfer body 2 at the secondary transfer position, and that supplies a release agent onto the intermediate transfer body 2. Agent supply section 7
_1 and a release agent wiping unit 7_2 for wiping the release agent from the intermediate transfer body 2 at the secondary transfer position.
And a cooling unit 8 for cooling the toner sandwiched between the recording paper P together with the intermediate transfer body 2 and the recording paper P. Note that the pressure roll 4_1 and the heating roll 4_2 can be arranged in reverse, and the pressure roll 4_2 may be a heating roll having a heat source inside.

In FIG. 1, the photosensitive member 1Y rotates clockwise, and its surface is uniformly charged by a charging unit (not shown). The charged photoreceptor 1Y is irradiated with a laser beam by the light beam scanning unit 9 in accordance with an external density signal to form an electrostatic latent image. The electrostatic latent image is toner-developed with the toner supplied by the developing device 5Y, so that a toner image of the first color Y is formed as a so-called digital image representing the density by area modulation, for example.
This toner image reaches the primary transfer position of the Y toner image adjacent to the primary transfer portion 3Y with the intermediate transfer member 2 interposed therebetween by the rotation of the photoconductor 1Y, and the Y toner image on the photoconductor 1Y At the position, when a voltage having the same polarity as the polarity of the Y toner image is applied to the primary transfer portion 3Y, it is electrostatically attracted to the intermediate transfer body 2 and rotates in a counterclockwise direction indicated by an arrow A in the figure. Is primarily transferred to the intermediate transfer member 2.

Hereinafter, similarly to the toner image of the first color Y,
When the toner image of the second color M, the toner image of the third color C, and the toner image of the fourth color K are formed on the photoconductor 1M, the photoconductor 1C, and the photoconductor 1K, respectively, From a predetermined time interval. These toner images of the second to fourth colors are respectively transferred onto the intermediate transfer member 2 so as to be accurately superimposed on the toner image of the first color in order, and the first color thus transferred is thus transferred. Multiple toner images are formed by superimposing the toner images of the fourth to fourth colors. The multicolor toner image on the intermediate transfer body 2 is conveyed to the secondary transfer position where the secondary transfer roll 4_1 is installed by circulation of the intermediate transfer body 2.

Between the intermediate transfer member 2 and the pressure roll 4_1 at the secondary transfer position, the recording paper P stored in a recording paper tray (not shown) overlaps with the multiple toner image on the intermediate transfer member 2. The paper is fed at a predetermined timing. The intermediate transfer member 2 is
The toner of the multi-toner image on the intermediate transfer member 2 is preliminarily heated to a temperature higher than the melting temperature of the toner and softened within the predetermined width along the circumferential surface of the heating roll 4_2 by a predetermined width in the circumferential direction. Melts. The softened and fused toner sandwiched between the intermediate transfer body 2 and the recording paper P is secondarily transferred by permeating the recording paper P while applying pressure by the pressure roll 4_1 and the heating roll 4_2. The secondary transfer of this multiple toner image to the recording paper P also serves as fixing. The recording paper P onto which the multiple toner images have been transferred is conveyed to the cooling unit 8 while keeping the recording paper P in close contact with the intermediate transfer body 2. Recording paper P by cooling unit 8
The toner of the multiple toner image transferred above is cooled and agglomerated and solidified. In this way, the toner of the multiple toner image is coagulated and solidified, so that the toner is strongly fixed to the recording paper P. The recording paper P on which the toner of the multi-toner image is fixed in this manner is separated from the intermediate transfer body 2 by the stiffness of the recording paper P itself on the paper separation roll 6_4. On the recording paper P thus peeled, a permanent image on which the multiple toner image is fixed is formed, and the image formation by the image forming apparatus of the present embodiment is completed.

In this image forming process, when the recording paper P is peeled off from the intermediate transfer member 2, the surface of the intermediate transfer member 2 is used in order to prevent multiple toners from remaining on the intermediate transfer member 2. The release agent is supplied by the release agent supply unit 7_1. However, if the intermediate transfer member 2 has a conventional flat surface, the release agent supplied onto the intermediate transfer member 2 is transferred to the photosensitive members 1Y, 1M, 1 at the primary transfer position.
C, 1K, and hinders formation of a toner image on the photoconductor.

The intermediate transfer member 2 has a structure shown in FIG. 2 so as to prevent such a release agent from transferring to the photosensitive member.

FIG. 2 is a sectional view of the intermediate transfer member of the image forming apparatus according to the present embodiment.

The intermediate transfer member 2 shown in FIG.
Layer 2_1 and base layer 2_1 serving as base materials for belt
It has a two-layer structure with the surface layer 2_2 formed thereon. The surface layer 2_2 has a plurality of protrusions c dispersed on the surface. The intermediate transfer member holds the release agent S at a portion h other than the plurality of protrusions c on the surface on which the plurality of protrusions c are dispersed. For example, as shown in the drawing, the convex portion c may have a substantially trapezoidal shape when viewed from a cross section cut in a direction perpendicular to the surface of the intermediate transfer body 2.

The release agent is supplied to the surface of the intermediate transfer member 2 by:
The recording paper peeling roll 6_4 in the image forming apparatus 10
As seen from the side, the release is performed by the release agent supply unit 7_1 disposed downstream and in the direction in which the intermediate transfer body 2 circulates. The release agent supply unit 7_1 is disposed upstream in the direction in which the intermediate transfer body 2 circulates when viewed from the primary transfer position. The details of the supply of the release agent by the release agent supply unit 7_1 will be described later. At the stage when the release agent is supplied by the release agent supply unit 7_1, the release agent is accumulated and held in portions h of the intermediate transfer body 2 other than the plurality of convex portions c, and the plurality of convex portions are held. It adheres on the part c.

A release agent wiping unit 7_2 is disposed on the downstream side in the direction in which the intermediate transfer body 2 circulates when viewed from the release agent supply unit 7_1 and on the upstream side when viewed from the primary transfer position. The release agent adhered on the plurality of convex portions c is wiped off by the release agent wiping portion 7_2. However,
The release agent S held in the portion h of the intermediate transfer member 2 other than the plurality of convex portions c remains without being wiped off by the release agent wiping portion 7_2. It is preferable that a plurality of the release agent wiping portions 7_2 be more than one because the wiping ability is improved.

The CM which is present on the downstream side in the direction in which the intermediate transfer body 2 circulates when viewed from the release agent wiping section 7_2.
At each primary transfer position where the toner of each color of YK is transferred, the plurality of convex portions c of the intermediate transfer member 2 are in contact with the photosensitive member 1. However, since the release agent on the plurality of convex portions c is wiped off by the release agent wiping portion 7_2, the release agent does not move to the photoconductor 1.

As described above, the image forming apparatus 1 of the present embodiment
In the case of 0, since the intermediate transfer body 2 holds the release agent, the toner of the multiple toner image is easily separated from the intermediate transfer body 2 during the above-described secondary transfer and fixing, and the multiple toner image has high transfer efficiency. The image is transferred to the recording paper P. This intermediate transfer member is
Since the release agent is supplied from the release agent supply unit 7_1 as needed, the intermediate transfer body 2 has a long release life. In the intermediate transfer body 2, the above-mentioned convex portions c are dispersed on the surface, and the release agent on the convex portions c is wiped off to remove
At the time of the next transfer, since the release agent does not exist on the convex portion c, the toner image on the photoconductor is not disturbed by contaminating the photoconductor 1 with the release agent. From these facts, the image forming apparatus 100 including the intermediate transfer body 2 having such a plurality of convex portions
Forms a high quality image.

However, it should be noted here that a plurality of convex portions c on the surface of the intermediate transfer member 2 form a concave portion on the surface of the toner image in the image on the recording paper P.

In general, it is known that a set of lines arranged at a density of at least 150 lines / inch is not visually recognized. The line density of 150 lines / inch or more is determined by the distance between the convex portions c on the intermediate transfer body 2, that is, the recording paper P
The distance between the concave portions on the image of (1) corresponds to 170 μm or less. As a result of the actual sensory evaluation, the interval between these convex portions c that is not bothersome even when visually recognized is 20
It has been found that the interval is 0 μm or less. Further, as a result of the sensory evaluation, it has been found that the size of the protrusion c that is not noticeable even when visually recognized is a size of about 100 μm or less in diameter. The interval between the protrusions c is 30μ
m or a diameter of the convex portion c of 10 μm is not preferable because controllability of the excimer laser and uniformity of the mold surface are impaired in forming the mold roll. From these circumstances, the interval between the convex portions c is preferably in the range of 30 μm or more and 200 μm or less, and the size of the convex portion c is preferably in the range of 10 μm or more and 100 μm or less in diameter. .

The height of the convex portion c depends on the particle size of the toner, but if the height of the convex portion c exceeds 9 μm, the photosensitive member 1
The transfer efficiency of the toner image from the toner to the intermediate transfer member 2 becomes 80% or less, and unevenness occurs partially. Also, the height of the convex part c is 4
If it is smaller than μm, the surface of the photoconductor 1 may come into contact with the surface between the convex portions c of the intermediate transfer member 2. From these circumstances, the height of the protrusion c is 4 μm or more and 9 μm
It is preferably within the following range.

If the ratio of the convex portion c to the total area of the surface of the intermediate transfer member 2 is too large, the concave portion on the recording paper P is conspicuous, and if the area of the convex portion is too small. There is a possibility that the surface of the photoconductor 1 comes into contact with a portion h other than the convex portion c on the surface of the intermediate transfer member 2. For this reason, the plurality of protrusions c on the surface of the intermediate transfer member 2 account for 5% of the total area of the surface on which the plurality of protrusions c are dispersed.
Preferably, it occupies an area of at least 20%.

Next, a release agent supply section and a release agent wiping section used in the image forming apparatus of this embodiment will be described with reference to FIGS.

FIG. 3 is a schematic view of three types of release agent application sections.

FIG. 3A shows the first release agent supply section 27. As shown in the figure, the first release agent supply unit 27 immerses a part of the surface member 21_1 of the application roll 21 in the release agent reservoir 22 and rotates it in the direction of arrow B in the same figure. The amount of the release agent in the surface member 21_1 and on the surface member 21_1 is adjusted and averaged by the measuring blade 23, and is applied to the surface of the intermediate transfer body 2 moving in the direction of arrow A in FIG.

FIG. 3B shows the second release agent supply section 37. As shown in the drawing, the second release agent supply unit 37 rotates a part of the supply member 24 while immersing the supply member 24 in the release agent pool 22, and furthermore, the measuring blade 23 supplies the release agent on the supply member 24. The amount is adjusted, and while applying the surface member 21_1 of the application roll 21 to the supply member 24, the application roll 21 is rotated in the direction of arrow B in FIG.
Is applied to the surface of the intermediate transfer body 2 moving in the direction of.

FIG. 3C shows the third release agent supply section 47. As shown in FIG. 3, the third release agent supply unit 47 immerses a part of the web 25 in the release agent reservoir 22 and places the surface member 21 of the application roll 21 on the web 25 sucked up by the release agent.
_1 is rotated in the direction of the arrow B in FIG.
1 and the amount of silicone oil on the surface member 21_1 is adjusted and averaged, and is applied to the surface of the intermediate transfer body 2 moving in the direction of arrow A in FIG.

The surface member 2 for these release agent supply sections
Examples of 1_1 include a nonwoven fabric, a silicone sponge, and the like, and a brush made of propylpyrene fibers can also be used.

The release agent supply section 7_1 continuously supplies the release agent to the surface of the intermediate transfer member 2 in accordance with the release property of the material on the surface of the intermediate transfer member 2 and the type of the release agent. May be performed intermittently or intermittently. In response to the supply of the release agent, the release agent wiping unit 7_2 also comes into contact with the surface of the intermediate transfer body 2 to wipe off the release agent. The agent may be wiped off.

FIG. 4 is a schematic view of two types of release agent wiping portions.

As shown in FIGS. 4A and 4B, the release agent wiping unit has a release agent wiping roll 31 that comes into contact with the intermediate transfer member 2. The first release agent wiping unit 57 shown in FIG. 4A has a release agent wiping roll 31 and a contact roll 32 that comes into contact with the release agent wiping roll, and is a belt-shaped intermediate transfer. The body 2 passes between these rolls. The intermediate transfer body 2 contacts the release agent wiping roll 31 with a large contact area along the peripheral surface of the release agent wiping roll 31, and a plurality of convex portions c on the surface of the intermediate transfer body 2.
The upper release agent is wiped off. Further, the second release agent wiping unit 67 shown in FIG.
1 and two tension rolls 33_1 and 33_2, and the belt-shaped intermediate transfer member 2 is provided with two tension rolls 33_1 and 3_2.
3_2, these two tension rolls 3
The release agent wiping roll 31 is arranged along the peripheral surface of the release agent wiping roll 31 disposed at an intermediate position between 3_1 and 33_2.
This is to wipe off the release agent on the plurality of projections c on the surface of the intermediate transfer member 2 while contacting the release agent with a large contact area. Examples of the release agent wiping roll 31 include a paper tube roll, a nonwoven fabric roll, and a low-hardness silicone rubber roll.

In the image forming apparatus 10, when the release agent wiping unit 7_2 wipes the release agent from the plurality of projections c, the intermediate transfer body 2 moves the photosensitive member 1 and the release agent supply unit 7_
Circulate one or more times while being kept away from one. The image forming apparatus 10 can form a high-quality image without separating the photoconductor 1 and the release agent supply unit 7_1 from the surface of the intermediate transfer body 2. However, as described above, the photoconductor 1 and the release agent supply unit 7_1 are once separated from the surface of the intermediate transfer member 2, and a sufficient time is required to separate the upper surfaces of the plurality of convex portions c on the surface of the intermediate transfer member 2. By wiping off the mold, a higher quality image is formed.

When a plurality of release agent wiping devices are provided, the release agent can be more efficiently wiped off, and the photosensitive member 1 and the release agent supply section 7_1 are separated from the surface of the intermediate transfer member 2. In addition, the time for keeping the photoconductor 1 and the release agent supply unit 7_1 apart from the surface of the intermediate transfer body 2 can be shortened.

By employing a belt-shaped wiping member instead of the release agent wiping roll 31,
It is also effective to increase the contact area between the intermediate transfer body 2 and the wiping member.

When the release agent is semi-solid such as wax, a scraping member such as a blade may be used instead of the release agent wiping roll 31.

The material of the belt base material constituting the base layer 2_1 of the intermediate transfer member 2 is polyimide, polyetheretherketone PEEK, polyarylene sulfide (PAS), polyimideamide, polyethersulfone (PES), polyether Nitrile (PEN), thermoplastic polyimide and the like can be mentioned, but polyimide is often used due to the requirement of heat resistance and mechanical strength. By adding conductive fine particles such as carbon black to the material of the belt base material, the volume resistivity of the base layer 2_1 is adjusted, and the electrostatic transfer from the photoconductor 1 to the intermediate transfer body 2 is performed. Done without disturbing the image. The volume resistivity of the base layer 2_1 is 10 ⁸ Ωcm or more and 10 ¹¹
It is preferably Ωcm or less.

As a material of the surface layer 2_2, silicone rubber having good adhesion to the recording paper P, excellent elasticity and heat resistance, and also excellent in releasing property by itself can be used. The volume resistivity of the surface layer 2_2 is 10 ¹² Ωcm or more and 10 ¹⁶ Ωc in order to perform electrostatic transfer of the toner image from the photosensitive member 1 to the intermediate transfer member 2 without disturbing the image.
m or less.

The release agent applied on the surface layer 2_2 of the intermediate transfer member may be silicone oil, silicone wax, fluorine oil, fluorine wax, or polypropylene which is usually added to toner of a copying machine or a printer. Wax and polyester wax. Further, modified products such as silicone oil and fluorine wax may be used as a release agent.

In the image forming apparatus 10 according to the present embodiment, such a release agent can be supplied by the release agent supply unit 7_1, so that the material of the surface layer 2_2 of the intermediate transfer body 2 is slightly released from the toner. Silicone resin, fluororubber, fluororesin, or the like, whose moldability is deteriorated, can be used.

The photoconductors 1Y, 1M, 1C, and 1K include
In addition to various inorganic photoconductors such as Se, a-Si, a-SiC, and CdS, various organic photoconductors can be used.

As a material of the color toner, a known material composed of a thermoplastic binder containing a dye such as yellow, magenta, and cyan can be used.

Pressure roll 4_1 and heating roll 4_2
For example, a metal roll or a metal roll having a heat-resistant elastic layer such as silicone rubber on the metal roll can be used. A heat source is disposed inside the heating roll 4_2, and a heating temperature of the heat source is set such that a toner temperature in a heating area where the toner is heated is equal to or higher than a toner melting temperature.
Controlled. The width of the heating area is set so that the photosensitive member 1 and the toner image and the recording paper P are sufficiently adhered to each other in the heating area so that partial floating does not occur, and wrinkling and displacement of the recording paper do not occur. Is set. As a heat source inside the heating roll 4_2, a halogen lamp or the like is used.

The cooling section 8 may cool not only from the intermediate transfer body 2 side but also from the recording paper P side. Further, the cooling unit 8 may be one that cools from both sides, and shows a high cooling capacity.

Next, a description will be given of an apparatus for manufacturing the intermediate transfer body 2 having the convex portions c uniformly formed on the surface.

FIG. 5 is a schematic view of an intermediate transfer body manufacturing apparatus for manufacturing an intermediate transfer body having a convex portion on the surface.
FIG. 3A is a sectional view of a mold roll (A) and a partial sectional view of a mold roll (B).

As shown in FIG. 5, the intermediate transfer body manufacturing apparatus 20 includes a counter roll 12, a mold roll 13, a drive roll 14, and driven rolls 15_1 and 15_2.
And a scraper 16. During the operation of the intermediate transfer body manufacturing apparatus 20, a belt substrate 2_1 'serving as the base layer 2_1 of the intermediate transfer body 2 is stretched on these rolls. This belt base material 2_1 ′ is
4 and circularly moves in the direction of the arrow in FIG. Here, the counter roll 12 and the mold roll 13 are in contact with each other, and the belt base material 2_1 'is sandwiched between these two rolls at a portion where the two rolls are in contact with each other. The belt base 2_1 ′ contacts the mold roll 13 over a wide area along the peripheral surface of the mold roll 13, and one of the portions of the belt base 2_1 ′ that contacts the mold roll 13 is a counter roll 1
2, the other part of which is driven by drive roll 1
Pulled by four. The mold roll 13, the counter roll 12, and the drive roll 14 have a heat source therein, and these three rolls are heated by the respective heat sources.
For example, the mold roll 13 is heated to 130 ° C., the counter roll 12 is heated to 70 ° C., and the drive roll 14 is heated to 7 ° C.
Heat to 0 ° C. The belt base material 2_1 '
While being heated while being in contact with the two rolls and moving in a circular manner while being heated in this manner, the temperature of the belt base material 2_1 ′ becomes constantly stable. When the temperature of the belt base 2_1 'is stabilized, the silicone rubber 17 is supplied at a position on the driven roll 15_1 of the belt base 2_1', and the supplied silicone rubber 17 is controlled to a predetermined thickness by the scraper 16. Belt base material 2
_1 ′ is coated. The silicone rubber 17 coated on the belt substrate 2_1 'is
Conveyed toward the mold roll 13 together with 1 '.

As shown in FIG. 6A, the mold roll 13
Has a surface layer 13_2 obtained by coating polyimide on an aluminum pipe 13_1 and thermally cross-linking it. The entire surface of the surface layer is subjected to an excimer laser treatment at a desired size, depth, and interval to form a concave portion h 'as shown in FIG.

The silicone rubber 17 coated on the belt base 2_1 ′ is cross-linked while passing over the mold roll 13 while being pressed against the mold roll 13 by the tension of the belt base 2_1 ′, and its surface is The above-mentioned convex portion c is formed by the concave portion h ′ on the surface of the mold roll. Secondary vulcanization is performed on the silicone rubber 17 on which the convex portion c is formed as described above, and the intermediate transfer body 2 is formed.

In addition to this intermediate transfer member manufacturing method,
There are various methods for providing irregularities on the surface of rubber. One of those methods is to make the silicone rubber spray coating rough by changing the coating conditions such as temperature, humidity, distance from spray gun, etc., or the viscosity of the silicone rubber, etc. There is a way. However, with this method, the surface of the undulations remains smooth even though the undulations appear,
It is difficult to perform appropriate wiping, such as applying a release agent to the undulation and leaving the applied release agent in the depression of the undulation and removing it from the projection of the undulation.

Further, there is a method of performing a blast treatment of applying sand or steel particles to the surface layer 2_2 of the intermediate transfer member 2. However, with this method, if the processing is weak,
Since the area of the concave portion is small, an appropriate amount of the release agent cannot be held in the concave portion. If the treatment is too strong, the tip of the convex portion becomes thin, and the shape of the convex portion causes the release agent wiping device to release. The wiping amount of the release agent changes depending on the pressure for wiping the release agent, and it becomes difficult to control the amount of the release agent held on the surface.

In addition to these methods, there is a method of polishing the surface of the surface layer 2_2 of the intermediate transfer member 2. However, the surface polished by this method has irregularities like peaks and valleys in the mountain range, and the amount of the release agent that is wiped off by the pressure to wipe off the release agent with the release agent wiper also changes. This makes it difficult to control the amount of the release agent held on the surface.

Unlike the intermediate transfer member manufactured by these methods, the plurality of convex portions c on the surface of the intermediate transfer member 2 of the present embodiment manufactured by the above-described intermediate transfer member manufacturing method are, for example, as described above. And has a shape of a predetermined size with a substantially trapezoidal cross section. For this reason, in the intermediate transfer body 2, the amount of the release agent held on the surface of the intermediate transfer body 2 can be easily controlled, and the part of the surface of the intermediate transfer body 2 that comes into contact with the photoconductor 1 can be released. It is easy to wipe off the agent.

[0067]

Embodiments of the present invention will be described below.

In the image forming apparatus of this embodiment, an 80 μm thick polyimide film to which carbon black was added was used as the base layer 2_1 of the intermediate transfer member 2. The base layer 2_1 was adjusted so that the volume resistivity was within the range of 10 ⁸ Ωcm to 10 ¹¹ Ωcm by changing the amount of carbon black added. The surface layer 2_2 is formed by coating a silicone-based rubber having a rubber hardness of 40 degrees and a thickness of 50 μm on the base layer 2_1 and has a volume resistivity of 1.
The adjustment was made so as to fall within the range of 0 ¹² Ωcm to 10 ¹⁶ Ωcm.

As the pressure roll 4_1 and the heating roll 4_2, a hollow aluminum roll made of a silicone rubber having a hardness of 55 and a thickness of 3 mm was used, and a halogen lamp was used as a heat source inside the heating roll 4_2. . The nip pressure between the pressure roll 4_1 and the heating roll 4_2 is appropriately in the range of 1 × 10 ⁵ Pa to 1 × 10 ⁶ Pa, and is set to 5.5 × 10 ⁵ Pa here.

The exposure conditions of the light beam scanning unit 9 and the developing conditions of the developing units 5Y, 5M, 5C and 5K are set such that the amount of toner on the recording paper of each color is 0.65 mg / color for each color depending on the content of the dye. cm ² .

Example 1 Example 1 was performed under the following conditions.

Surface material of intermediate transfer member: KE1330 (manufactured by Shin-Etsu Chemical Co., Ltd.) Height of convex portion on intermediate transfer member surface: 7 μm Size of convex portion on intermediate transfer member surface: diameter of 30 μm Surface of intermediate transfer member -The area ratio of the convex portion to the surface of the intermediate transfer member: 5%-Release agent: dimethyl silicone oil KF96 (50cs) (manufactured by Shin-Etsu Chemical Co., Ltd.) The first release agent supply section 27 and the first release agent wiping section 57 were used. The release agent supply roll 21 of the first release agent supply unit 27 has a surface member 21_1 made of non-woven fabric, and the release agent wiper roll of the first release agent wiper 57 is used. 3
1, a paper tube roll was employed. The release agent was supplied once per 500 prints. During the supply of the release agent, the photosensitive member 1 was separated from the intermediate transfer member 2 while the intermediate transfer member 2 was rotated once.

As a result of forming an image under such conditions and visually determining the quality of the formed image, it is found that the toner releasability of the intermediate transfer body 2 is maintained for 100,000 or more prints. understood.

<Example 2> Example 2 was performed under the following conditions.

· Surface material of intermediate transfer member: KE1330 (manufactured by Shin-Etsu Chemical Co., Ltd.) · Height of convex portion on surface of intermediate transfer member: 4 µm · Size of convex portion on surface of intermediate transfer member: diameter of 80 µm · Surface of intermediate transfer member The distance between the convex portions: 160 μm. The area ratio of the convex portions to the surface of the intermediate transfer member: 20%. The release agent: dimethyl silicone oil KF96 (100 cs) (manufactured by Shin-Etsu Chemical Co., Ltd.). The first release agent supply section 27 and the first release agent wiping section 57 were used. The first release agent supply roll 27 of the first release agent supply unit 27 has a surface member 21_1 made of silicone sponge, and the first release agent wiping unit 57 has a surface release member 21_1. The roll 31 was a nonwoven fabric roll. The release agent was supplied once per 100 prints. During the supply of the release agent, the photosensitive member 1 was separated from the intermediate transfer member 2 while the intermediate transfer member 2 was rotated three times.

As a result of forming an image under such conditions and visually determining the quality of the formed image, it is found that the toner releasability of the intermediate transfer body 2 is maintained for 100,000 or more prints. understood.

Example 3 Example 3 was performed under the following conditions.

・ Surface material of intermediate transfer member: KE1330 (manufactured by Shin-Etsu Chemical Co., Ltd.) ・ Height of convex portion on intermediate transfer member surface: 4 μm ・ Size of convex portion on intermediate transfer member surface: 60 μm diameter ・ Intermediate transfer member surface -The area ratio of the convex portion to the surface of the intermediate transfer member: 12.6%-Release agent: dimethyl silicone oil KF96 (100 cs) (manufactured by Shin-Etsu Chemical Co., Ltd.) The first release agent supply section 27 and the first release agent wiping section 57 were used. The surface member 21_1 of the release agent supply roll 21 of the first release agent supply unit 27 is made of a brush made of propylpyrene fiber, and the first release agent wiping unit is used. 57
As the release agent wiping roll 31, a roll of low-hardness silicone rubber was used. Supply of release agent is print 20
The test was performed once for 0 sheets. When the release agent is supplied, while the intermediate transfer body 2 rotates twice in a cyclic manner, the photosensitive member 1
Was separated from the intermediate transfer member 2.

As a result of forming an image under such conditions and visually determining the quality of the formed image, it is found that the toner releasability of the intermediate transfer body 2 is maintained for 100,000 or more prints. understood.

Example 4 Example 4 was performed under the following conditions.

Surface material of intermediate transfer member: KE1330 (manufactured by Shin-Etsu Chemical Co., Ltd.) Height of convex portion on intermediate transfer member surface: 7 μm Size of convex portion on intermediate transfer member surface: diameter of 30 μm Surface of intermediate transfer member Spacing between the convex portions: 120 μm Area ratio of the convex portion to the surface of the intermediate transfer member: 5% As a release agent, a wax which is usually used in a toner in a copying machine or the like was used. For example, a particle size of 1μ
m or less was used.

In the fourth embodiment, the first release agent supply section 27 and the first release agent wiping section 57 were used.
The surface member 21_1 of the release agent supply roll 21 of the first release agent supply unit 27 is made of a brush made of propylpyrene fiber, and the first release agent wiping unit is used. As the release agent wiper roll 57, a roll of low-hardness silicone rubber was used. The release agent was supplied once every 150 prints. During the supply of the release agent, the photosensitive member 1 was separated from the intermediate transfer member 2 while the intermediate transfer member 2 was rotated once.

As a result of forming an image under such conditions and visually determining the quality of the formed image, the toner releasability of the intermediate transfer body 2 is maintained for 100,000 or more prints. understood.

In the first to fourth embodiments, the second release agent supply section 27 is replaced with the second release agent supply section 27.
The same results as those of these examples were obtained by using the release agent supply section 37 of the above. Further, in the first to third embodiments, even when the third release agent supply unit 47 is used instead of the first release agent supply unit 27, the same results as those of these embodiments are obtained. Was done. Further, in these Examples 1 to 4, even when the second release agent wiping section 67 is used instead of the first release agent wiping section 57, the same results as those of these examples are obtained. Is considered to be obtained.

As described above, the image forming apparatus 1 of the present embodiment
0 indicates that the toner release life of the intermediate transfer body 2 is increased by supplying a release agent to the intermediate transfer body 2 without deteriorating the image quality under various conditions as shown in these examples. Can be extended.

[0086]

As described above, according to the present invention,
An image forming apparatus that forms a high-quality image while carrying a release agent on an intermediate transfer member is provided.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an image forming apparatus according to an embodiment.

FIG. 2 is a cross-sectional view of an intermediate transfer member of the image forming apparatus according to the exemplary embodiment.

FIG. 3 is a schematic view of three types of release agent application sections.

FIG. 4 is a schematic view of two types of release agent wiping units.

FIG. 5 is a schematic view of an intermediate transfer body manufacturing apparatus for manufacturing an intermediate transfer body provided with a convex portion on the surface.

FIG. 6 is a sectional view of a mold roll (A) and a partial sectional view of a mold roll (B).

[Explanation of symbols]

 1Y Y photoreceptor 1M M photoreceptor 1C C photoreceptor 1KK photoreceptor 2 Intermediate transfer body 2_1 Base layer 2_1 'Belt base 2_2 Surface layer 3Y, 3M, 3C, 3K Primary transfer unit 4_1 Pressure roll 4_2 Heating roll 5Y, 5M, 5C, 5K Developing unit 6_1 Driving roll 6_2, 6_3 Tension roll 6_4 Paper peeling roll 7_1 Release agent supply unit 7_2 Release agent wiping unit 8 Cooling unit 9 Light beam scanning unit 10 Image Forming device 12 Counter roll 13 Mold roll 13_1 Aluminum pipe 13_2 Surface layer 14 Drive roll 15_1, 15_2 Follower roll 16 Scraper 17 Silicone rubber 20 Intermediate transfer body manufacturing device 21 Coating roll 21_1 Surface member 22 Release agent reservoir 23 Measuring blade 24 Supply member 25 Web 27 First release Supply unit 31 Release agent wiping roll 32 Contact roll 33_1, 33_2 Tension roll 37 Second release agent supply unit 47 Third release agent supply unit 57 First release agent wiping unit 67 Second release Agent wiping part c Convex part P Recording paper S Release agent

Claims (5)

[Claims] An image carrier on which a toner image is formed; and a toner image on the image carrier that circulates and is transferred at a predetermined primary transfer position, and the toner image transferred at the primary transfer position is transferred to the image carrier. An intermediate transfer body that carries and conveys the toner image carried on the intermediate transfer body to a predetermined secondary transfer position; and a transfer unit that transfers a toner image carried on the intermediate transfer body to a recording medium at the secondary transfer position. Has a surface in which a plurality of convex portions are dispersed,
An image forming apparatus for holding a release agent in a portion of the surface other than the plurality of convex portions. 2. The intermediate transfer member according to claim 1, wherein the plurality of protrusions on the surface on which the plurality of protrusions are formed occupy an area of 5% or more and 20% or less of a total area of the surface. The image forming apparatus according to claim 1, wherein: 3. The image forming apparatus according to claim 2, wherein
A release agent supply unit for supplying a release agent, which is located downstream of the secondary transfer position and upstream of the primary transfer position in the circulating movement of the intermediate transfer body. Item 1
The image forming apparatus as described in the above. 4. The image forming apparatus according to claim 1, further comprising:
One for wiping the release agent from the plurality of projections of the intermediate transfer member, located on the downstream side of the release agent supply unit and the upstream side of the primary transfer position in the circulating movement of the intermediate transfer member 4. The image forming apparatus according to claim 3, further comprising the release agent wiping unit. 5. When the release agent wiping unit wipes the release agent from the plurality of projections, the intermediate transfer body is once separated from the image carrier and the release agent supply unit. The image forming apparatus according to claim 4, wherein the image forming apparatus circulates.