JP2006098815A - Transfer device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transfer device in which uneven spreading of a release agent spread on a transfer belt is prevented and the removability of affixes, such as toner and paper dust is improved, and with which transferability can be kept proper. <P>SOLUTION: The transfer device 8 for transferring a toner image formed on a peripheral surface of a photoreceptor 2 onto transfer paper has a rotating endless transfer belt 11 disposed facing the photoreceptor 2, wherein a release agent is spread on a surface of the transfer belt 11 by a release agent spreader 26 for facilitate removal of extraneous matters. The release agent is zinc stearate particles surface-treated with silica fine particles, and preferably, the release agent contain 3-20 pts.wt. of the silica fine particles with respect to 100 pts.wt. of the zinc stearate particles. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a transfer device that is used in an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine using an electrophotographic method, and that transfers a toner image formed on a photoreceptor onto a transfer sheet. In particular, the present invention relates to a transfer apparatus in which a release agent is applied to the surface of the transfer belt so as to promote the peeling of deposits from the transfer belt.

In an image forming apparatus using a general electrophotographic method, the surface of the photosensitive member is uniformly charged, and an electrostatic latent image corresponding to the original image is formed on the surface of the photosensitive member by image exposure. The image is formed into a toner image by a developing device, the toner image is transferred onto the transfer paper from the surface of the photoreceptor, and the transferred toner image is fixed by heat, pressure, or the like, thereby forming an image.
In such an image forming apparatus, various belt members are used in a toner image transfer process. For example, in a system in which a toner image is directly transferred from a photoconductor to a transfer paper, the toner image is transferred to the transfer paper from a photoconductor through an intermediate transfer body or a transfer belt for holding and transporting the transfer paper on which the toner image is transferred. In the secondary transfer method, a transfer belt for intermediate transfer of a toner image formed on the peripheral surface of the photoreceptor is used.

In the former direct transfer system, a transfer roller is arranged facing the photoconductor, and a transfer bias voltage is applied between the photoconductor and the transfer roller so that the roller is held at a potential having a polarity opposite to that of the toner image. In some cases, the transfer paper is applied between the photoconductor and the transfer roller in this state, and the toner image is transferred to the surface of the transfer paper by an electric field formed between the transfer roller and the photoconductor. At this time, the transfer paper is conveyed by the transfer belt.
On the other hand, the latter intermediate transfer method is generally used in full-color image forming apparatuses that form a full-color image by superimposing a plurality of color toner images. The read original image is divided into a plurality of color components, and each color component is separated. Is formed on the peripheral surface of the photosensitive drum, and the toner images of the respective color components are transferred onto the surface of the transfer belt in a stacked state, and further transferred onto a transfer sheet.

  In the transfer apparatus using the transfer belt as described above, there are problems such as deposits such as residual toner and paper dust on the transfer belt surface after transfer, and the transfer belt surface deteriorates to cause transfer failure. It was. In addition, in a transfer belt used for intermediate transfer, particularly when a large amount of toner is handled as in the case of forming a full-color image, the toner image primarily transferred onto the transfer belt is not completely transferred to the transfer paper. There is a problem that the transferability may be lowered due to the residual. Therefore, in a conventional transfer apparatus, an apparatus provided with a cleaning unit has been used to remove deposits on the transfer belt surface. Examples of the cleaning means include a blade system and a fur brush system, but all of them are mechanically pressed against the transfer belt and scraped off. However, it was difficult to clean it to a sufficient state.

In order to solve such problems, Patent Document 1 (Japanese Patent Laid-Open No. 10-31376) proposes a transfer device using a lubricant such as zinc stearate. This transfer apparatus has a transfer roller, but a lubricant such as solid zinc stearate is applied to the transfer roller, and a coating layer of zinc stearate is formed on the surface, thereby forming toner, paper powder, etc. The adhered matter is made difficult to adhere to the transfer roller, and when adhered, it can be easily cleaned.
However, when the solid lubricant is applied directly to the transfer roller, the contact pressure between the transfer roller and the lubricant becomes non-uniform, resulting in uneven application. -Like images are generated.

Therefore, in Patent Document 2 (Japanese Patent Laid-Open No. 7-271262) and Patent Document 3 (Japanese Patent Laid-Open No. 2003-337480), a lubricant imparting agent such as solidified zinc stearate is indirectly used as an intermediate transfer member. An apparatus for applying has been proposed.
In Patent Document 2, the solidified lubricity-imparting agent is scraped off by a rotationally-driving application brush attached to the transfer belt so as to be able to come into contact with and separated from the transfer belt, and the lubricity-imparting agent adhering to the application brush in powder form is applied to the transfer belt. The structure to perform is disclosed.
In Patent Document 3, the solidified lubricity-imparting agent is disposed at a position where it is rubbed with a cleaning brush, and the lubricity-imparting agent is applied to the intermediate transfer member by rotation of the cleaning brush. It is disclosed. In this way, coating unevenness is prevented by using a finely divided coating agent.

JP-A-10-31376 Japanese Patent Laid-Open No. 7-271262 JP 2003-337480 A

However, since the zinc stearate particles have high cohesiveness, it is inevitable that coating unevenness occurs, and the surface of the photoreceptor is contaminated by this coating unevenness, and streaky images are generated on the image. There is a problem that zinc aggregates adhere to the photoreceptor, drum leaks occur, and black spots occur.
Accordingly, in view of the problems of the prior art, the present invention prevents uneven application of the release agent applied to the transfer belt, improves the releasability of deposits such as toner and paper powder, and keeps the transfer property good. It is an object of the present invention to provide a transfer device that can perform the transfer.

Therefore, in order to solve this problem, the present invention provides:
A transfer device for transferring a toner image formed on a peripheral surface of a photoconductor to a transfer paper, the transfer device comprising an endless transfer belt that is rotationally driven and arranged to face the photoconductor, and the surface of the transfer belt In a transfer device in which a release agent is applied to promote the peeling of the deposit,
The release agent is zinc stearate particles surface-treated with silica fine particles.

  Thus, by using a mold release agent in which zinc stearate particles are surface-treated with silica fine particles, the cohesiveness of zinc stearate can be reduced and the flowability of the mold release agent can be improved. Even when this release agent is applied to the transfer belt, coating unevenness hardly occurs on the belt, and the release agent is uniformly dispersed. This makes it difficult to adhere deposits such as toner and paper dust, and even if the deposits adhere, it is easily removed because it has good releasability, improving cleaning properties and improving transfer efficiency. Further, when the release agent is applied to the intermediate transfer belt, the binding force of the toner image transferred onto the transfer belt to the belt can be reduced, and the toner image can be reliably transferred onto the transfer paper. Therefore, the transfer efficiency of the toner becomes good and the occurrence of image defects such as voids can be prevented.

Further, the transfer device transfers a toner image formed on the peripheral surface of the photosensitive member to a transfer paper, the transfer device including an endless transfer belt that is rotationally driven and is disposed to face the photosensitive member, and the transfer belt. A release agent coating device for applying a release agent to the surface, and the release agent applied to the transfer belt surface by the release agent coating device promotes peeling of deposits on the transfer belt surface. In the transfer device,
The release agent application device has a release agent storage portion that stores the release agent, and a release agent application brush that applies the release agent to the transfer belt surface from the release agent storage portion,
The release agent is zinc stearate particles surface-treated with silica fine particles.
In the conventional release agent coating apparatus, due to the cohesiveness of zinc stearate, there is a problem that uneven coating occurs when the release agent stored in the form of particles (powder) is applied to the transfer belt. The release agent was dispersed in a solvent or solidified and stored in the apparatus. However, the surface treatment was performed with silica fine particles as in the present invention to suppress the cohesive force of the zinc stearate particles. It becomes possible to store in the state of, and handling becomes easy.

The mold release agent may include 3 to 20 parts by weight of the silica fine particles with respect to 100 parts by weight of the zinc stearate particles.
This is because when the silica fine particles are 3 parts by weight or less, the cohesive force of the zinc stearate is large and sufficient fluidity cannot be secured, resulting in coating unevenness, while the silica fine particles are 20 parts by weight or more. In this case, a large amount of silica fine particles that cannot be completely adhered to the surface of the zinc stearate are generated, and the fine particles are adhered to other members such as a photoconductor. It is preferable. The mold release agent can be easily produced by, for example, adding zinc stearate particles and silica fine particles to a stirrer such as a Henschel mixer, and adjusting the rotation time, time, and the like, and stirring and mixing. .

  As described above, according to the present invention, by using a release agent in which zinc stearate particles are surface-treated with silica fine particles, the cohesiveness of zinc stearate is reduced, and the release agent is uniformly applied on the transfer belt. Therefore, deposits such as toner and paper powder are difficult to adhere and transfer efficiency is improved. Further, when the release agent is applied to the intermediate transfer belt, the binding force of the toner image transferred onto the transfer belt to the belt can be reduced, and the toner image can be reliably transferred onto the transfer paper. Therefore, the transfer efficiency of the toner becomes good and the occurrence of image defects such as voids can be prevented.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.
The transfer device in this embodiment can be applied to an image forming apparatus such as a copying machine, a printer, a facsimile, or a complex machine using an electrophotographic system.

  FIG. 1 is a schematic sectional view of an image forming unit in a full-color copying machine in which an embodiment of the present invention is employed. The image forming unit 1 includes a photosensitive drum 2 on which an electrostatic latent image is formed on a peripheral surface, and further includes a main charging device 3 and developing devices 4, 5, 6, and the like arranged around the photosensitive drum 2. 7 and a transfer device 8 and a cleaning device 9. The main charging device 3 is a device for charging the surface of the photosensitive drum 2, and is disposed above the photosensitive drum 2. Developing devices 4, 5, 6, and 7 that form toner images on the photosensitive drum 2 from the left side to the lower side of the photosensitive drum 2 with a predetermined gap from the main charging device 3 are disposed. Each of the developing devices 4, 5, 6, and 7 stores cyan, magenta, yellow, and black toners, respectively, and visualizes the electrostatic latent image formed on the photosensitive drum 2 with each color toner. . The transfer device 8 is a device for transferring the toner image on the photoconductive drum 2 onto transfer paper (recording paper), and is disposed obliquely to the lower right of the photoconductive drum 2. The cleaning device 9 is a device for removing residual toner and the like on the surface of the photosensitive drum 2, and is disposed on the upper right side of the photosensitive drum 2.

  An exposure device 10 for forming an electrostatic latent image on the peripheral surface of the photosensitive drum 2 is provided obliquely above and to the left of the photosensitive drum 2. The exposure device 10 includes a laser unit (not shown) and a mirror that deflects laser light from the laser unit to the circumferential surface of the photosensitive drum 2, and the circumferential surface of the photosensitive drum 2 based on an image data signal obtained from the color imaging device. An electrostatic latent image is formed on the surface. The laser beam irradiated from the exposure device 2 passes between the main charging device 3 and the developing device 4 and is irradiated onto the peripheral surface of the photosensitive drum 2.

As shown in the figure, the transfer device 8 includes a drive roller 14 to which a driving force of a drive motor 15 is transmitted via a drive belt 16, a secondary transfer upper roller 18, a drive roller 14 and a secondary transfer upper roller. A transfer belt 11 stretched between 18, a primary transfer upper roller 12 that presses the outer peripheral surface of the transfer belt 11 against the peripheral surface of the photosensitive drum 2, a primary transfer lower roller 13, And a tension roller 17 disposed on the peripheral surface side.
A release agent described later is applied to the surface of the transfer belt 11.
The primary transfer upper roller 12 and the primary transfer lower roller 13 are disposed between the driving roller 14 and the secondary transfer upper roller 18 at positions facing the photosensitive drum 2 with the transfer belt 11 interposed therebetween. Yes. The primary transfer upper roller 12, together with the primary transfer lower roller 13, is between a pressure contact position where the transfer belt 11 is pressed against the circumferential surface of the photosensitive drum 2 and a separation position where the transfer belt 11 is separated from the circumferential surface of the photosensitive drum 2. It is possible to move with.

  Further, the transfer device 8 is provided with a cleaning device 20 for cleaning the surface of the transfer belt 11. The cleaning device 20 is disposed between the primary transfer lower roller 13 and the secondary transfer upper roller 18. The cleaning roller 21 is in contact with the inner peripheral surface of the transfer belt 11. The transfer belt 11 is attached to the cleaning roller 21. And a toner collecting section 24 having a spiral 23 for sending the toner scraped off by the cleaning blade 22 to a collecting tank.

Further, the transfer device 8 is disposed at a position facing the secondary transfer upper roller 18 with the transfer belt 11 interposed therebetween, and a toner image is transferred onto the transfer paper by applying a voltage having a reverse polarity to the toner on the surface of the transfer belt 11. A secondary transfer lower roller 19 is provided. The secondary transfer lower roller 19 is rotatably supported, and when transferring a toner image, a transfer bias voltage having a polarity opposite to that of the toner is applied to the secondary transfer lower roller to transfer the toner image onto a transfer sheet. . The secondary transfer lower roller 19 and the cleaning device 20 are configured to abut on the transfer belt 11 only during the secondary transfer operation.
On the right side of the secondary transfer upper roller 18 and the second transfer lower roller 19 of the transfer device 8, a registration roller 25 is provided for transporting the transfer paper to a predetermined position. The transfer paper is conveyed between the secondary transfer upper roller 18 and the second transfer lower roller 19 through the registration roller 25.
A fixing device (not shown) is disposed on the left side of the secondary transfer upper roller 18 and the secondary transfer lower roller 19 of the transfer device 8, and the transfer paper is heated and pressed by the fixing device to transfer the transfer paper. The toner image is fixed on the paper.

In the image forming process in the image forming apparatus as described above, first, an image of a document placed on a document table is irradiated with light, and light reflected from the surface of the document is read by a color image sensor such as a CCD sensor. The document image is decomposed into an image of a plurality of color components constituting a full color image by an image processing unit. Then, an electrostatic latent image for each color component is formed on the circumferential surface of the photosensitive drum 2 by the main charging device 3 and the exposure device 10 arranged around the photosensitive drum 2, and the corresponding developing devices 4, 5, The toner image is visualized by either one of 6 and 7. Further, a voltage for transferring the toner on the circumferential surface of the photosensitive member 2 is applied to the primary transfer lower roller 13 to transfer the toner image onto the surface of the transfer belt 11. This primary transfer operation is performed for each color component to form a color toner image in which the toner images of the respective color components are laminated on the surface of the transfer belt 11.
When the primary transfer process from the photosensitive drum 2 to the transfer belt 11 is completed, the transfer paper is transported between the transfer belt 11 and the secondary transfer rollers 18 and 19 via the registration roller pair 25 to perform secondary transfer. By applying a predetermined transfer bias voltage to the lower roller 19, a full color toner image can be transferred onto the transfer paper.

Here, the configuration of the transfer belt 11 will be described. The transfer belt 11 is an endless belt provided to face the photoconductor 2 and is formed of a resin belt or a rubber belt. A granular release agent is applied to the outer peripheral surface of the transfer belt 11 by a release agent application device 26. The release agent application device 26 stores a release agent application brush 28 that is pressed against the drive roller 14 via the transfer belt 11 and a granular release agent. The release agent application brush 28 is supplied with a release agent. It comprises a release agent storage unit 27 for supply.
The release agent coating device 26 applies the release agent to the surface of the transfer belt 11 at a constant cycle, and the release agent is used when the toner adhering to the transfer belt 11 is transferred to the transfer paper surface. It weakens the binding force of the toner to the transfer belt 11, prevents image defects such as voids in the toner image formed on the transfer paper, and improves the releasability of foreign matters such as residual toner and paper dust, thereby making it easy to clean. It has the function to improve. The release agent application brush 28 can be projected and retracted with respect to the transfer belt 11, and is configured to be pressed against the drive roller 14 and apply the release agent to the transfer belt 11 as necessary. . Further, a release agent application blade (not shown) is disposed around the transfer belt 11 and downstream of the release agent application brush 28, and the release agent applied on the belt is leveled by the blade. You may do it.

  The release agent application device 26 controls the release agent application brush 28 to contact the transfer belt 11 and apply the release agent to the belt surface every time image formation is completed. Further, the number of times of transfer of the toner image to the surface of the transfer belt 11 may be counted, and the release agent may be controlled to be applied to the surface of the transfer belt 11 when the number of times of transfer reaches a predetermined number. These controls may be performed in combination.

The release agent is obtained by surface-treating silica fine particles on zinc stearate particles.
The releasing agent is preferably configured so that the zinc fine particles are contained in an amount of 3 to 20 parts by weight with respect to 100 parts by weight of the zinc stearate particles. By making the compounding ratio of the silica fine particles within this range, the fluidity of the release agent can be secured by suppressing the cohesive force of the zinc stearate particles, and the release agent can be uniformly applied to the transfer belt. In addition, excessive silica fine particles that do not adhere to the surface of the zinc stearate particles are hardly generated, and it is possible to prevent other members such as a photoreceptor from being adversely affected.

The mold release agent can be produced by charging the zinc stearate particles and the silica fine particles into a mixer in predetermined amounts, and stirring and mixing them. As the mixer, for example, a Henschel mixer or the like can be used, and the silica fine particles can be adhered to the surface of zinc stearate in a good state by appropriately adjusting the shape of the stirring blade, the peripheral speed, the mixing time, and the like.
The zinc stearate particles preferably have a volume average particle diameter of about 1 μm to 5 μm, and more preferably about 1 μm to 3 μm. By setting the particle size as described above, electrostatic adhesion of the toner particles to the transfer belt 11 is not hindered. Therefore, the toner image transferred to the transfer belt 11 is not disturbed, and the toner is transferred during the secondary transfer of the toner image. Particle releasability can be improved, and paper dust and transfer residual toner adhering to the transfer belt 11 during cleaning of the transfer belt 11 can be satisfactorily cleaned.

Silica fine powder produced by a conventionally known dry method or wet method can be used as the silica fine particles. In particular, in this example, silica fine particles produced by a dry method are preferable because of high fluidity. The dry method is a method of producing silica fine particles by vapor phase oxidation of a silicon halogen compound, and examples thereof include a method of obtaining silicon tetrachloride by thermal decomposition oxidation reaction in a gas phase. The wet method is a method in which silica is precipitated by neutralization with an acid or alkali metal salt of an aqueous solution of sodium silicate and a decomposition reaction. For example, decomposition of silicon sodium with an acid or the like is raised. As the silica fine particles, silicates such as silicon dioxide, aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, and zinc silicate can be applied.
The silica fine particles produced by the method as described above preferably remove coarse particles by classification. When sieving is performed, only silica fine particles having a primary particle diameter of about 10 to 15 nm are collected and used. good.

  In this embodiment, the transfer device for secondary transfer of the toner image to the transfer paper from the photosensitive member via the intermediate transfer member is described as an example. However, the present invention is not limited to this configuration. The toner image can be directly transferred onto a transfer sheet. In this method, a transfer roller is arranged facing the photoconductor drum, and a transfer bias voltage is applied between the photoconductor drum and the transfer roller so that the roller is held at a potential opposite to that of the toner image. In this state, the transfer paper is passed between the photosensitive drum and the transfer roller, and the toner image is transferred to the transfer paper surface by the electric field formed between the transfer roller and the photosensitive drum. At this time, the transfer paper is conveyed by the transfer belt. That is, a transfer belt stretched endlessly between a plurality of rollers is positioned between the photosensitive drum and the transfer roller, and the transfer paper is conveyed by the transfer belt. A release agent application device using the release agent described above may be provided along the peripheral surface of the transfer belt, and the release agent may be applied to the transfer belt surface.

Next, using the image forming apparatus according to Example 1 described above, the results of performing the respective evaluation tests with different release agents applied on the transfer belt 11 by the release agent application device 26 are as follows. Shown in
The mold release agent used in Example 1 was charged with 100 parts by weight of zinc stearate particles (volume average particle diameter 2 μm) and 8 parts by weight of silica fine particles (primary particle diameter 12 nm) in a Henschel mixer and mixed and stirred. Thus, a release agent composed of zinc stearate particles surface-treated with silica fine particles was obtained. The release agent is stored in the release agent storage portion 28 and applied to the transfer belt 11 when the image is formed by the release agent application brush 27. In the initial state and after the image formation of 3000 transfer sheets, The streaky image generated on the transfer paper, the leak point generated on the photosensitive drum 2, and the adhesion of foreign matter on the transfer belt 11 were evaluated.
In Comparative Example 1, when zinc stearate particles not subjected to surface treatment were used as a release agent, and the release agent was applied onto a transfer belt, in Comparative Example 2, solid zinc stearate as a release agent In Comparative Example 3, the case where the release agent was not applied to the transfer belt 11 was evaluated in the same manner as in Example 1 above.

As is apparent from Table 1 above, in Example 1, the image on the transfer paper is free from streaks, the image quality is improved, the leak on the photosensitive drum is not generated, and the image on the transfer belt is not generated. Almost no foreign matter was found.
On the other hand, in Comparative Example 1, there was almost no foreign matter adhering to the transfer belt, but a streak-like image was generated on the transfer paper, and a leak was also generated on the photosensitive drum. This is presumably because zinc stearate aggregated and the aggregate adhered to the photoreceptor.
In Comparative Example 2, there was almost no foreign matter adhering to the transfer belt, and no leak occurred on the photosensitive drum, but a streak-like image was generated on the transfer paper. This is presumably because the contact pressure between the solid release agent and the transfer belt was non-uniform, resulting in uneven application of the release agent, and the surface of the photoreceptor was contaminated by the uneven application.
Further, in Comparative Example 3, no streaks on the transfer paper and no leakage to the photosensitive drum occurred, but foreign matter adhered to the transfer belt. This is presumably because the transfer belt was poorly peelable and foreign matter such as paper dust and residual toner adhered.
From the above evaluation results, it is clear that by using a release agent obtained by surface-treating zinc stearate particles with silica fine particles, deposits such as toner and paper powder are difficult to adhere and transfer efficiency is improved. Become.

  The transfer device of the present invention can be applied to all developing devices in an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine using electrophotography.

1 is a schematic cross-sectional view of an image forming unit including a transfer device according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image formation part 2 Photosensitive drum 8 Transfer device 11 Transfer belt 12 Primary transfer upper roller 13 Primary transfer lower roller 18 Secondary transfer upper roller 19 Secondary transfer lower roller 20 Cleaning device 26 Release agent coating device 27 Release Agent application brush 28 Release agent storage

Claims (3)

A transfer device for transferring a toner image formed on a peripheral surface of a photoconductor to a transfer paper, the transfer device comprising an endless transfer belt that is rotationally driven and arranged to face the photoconductor, and the surface of the transfer belt In a transfer device in which a release agent is applied to promote the peeling of the deposit,
The transfer device, wherein the release agent is zinc stearate particles surface-treated with silica fine particles. A transfer device for transferring a toner image formed on a peripheral surface of a photoconductor to a transfer paper, the transfer device having an endless transfer belt that is rotationally driven and arranged on the photoconductor, and a surface of the transfer belt. A release agent application device for applying a release agent, and the release agent applied to the transfer belt surface by the release agent application device promotes the peeling of the deposit on the transfer belt surface. In
The release agent application device has a release agent storage portion that stores the release agent, and a release agent application brush that applies the release agent to the transfer belt surface from the release agent storage portion,
The transfer device, wherein the release agent is zinc stearate particles surface-treated with silica fine particles. 3. The transfer device according to claim 1, wherein the release agent contains 3 to 20 parts by weight of the silica fine particles with respect to 100 parts by weight of the zinc stearate particles.

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