JPH0934274A - Intermediate transfer medium and image forming method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To have a sensible image to be efficiently transferred onto an intermediate transfer medium and to have the sensible image on the intermediate transfer medium efficiently retransferred onto a material to be transferred by providing the intermediate transfer medium with a silicone rubber layer having the swelling rate to a liquid toner dispersing medium to a specific value or below. SOLUTION: The intermediate transfer medium is constituted by successively laminating a conductive silicone rubber layer and the silicone rubber layer on a substrate, such as, for example, aluminum, iron or plastic film. The thickness of the conductive silicone layer is preferably 50 to 5000μm. The swelling rate of the silicone rubber layer to the liquid toner is <=50%, preferably <=30% and more preferably <=20%. A solvent is liable to penetrate the conductive silicone rubber layer of the lower layer through the silicone rubber layer and the swelling of the conductive silicone rubber layer is liable to be induced if the swelling rate exceeds 50%. The thickness of the low-swelling silicone rubber layer is preferably >=0.2 to <=5μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention develops an electrostatic latent image on an electrostatic latent image carrier with liquid toner, and electrostatically transfers the visualized image developed by this development to an intermediate transfer body. The present invention relates to an intermediate transfer member used in an image forming method for subsequently retransferring a visible image on the intermediate transfer member onto a transfer target material. For example, it is used in an image forming method used in a copying machine or a laser beam printer. It relates to an intermediate transfer member.

[0002]

2. Description of the Related Art The following intermediate transfer members are used in the above-described image forming method.

For example, JP-A-3-154085 (Prior Art 1) discloses an intermediate transfer member having an elastic layer having a smooth surface and a thin dielectric layer and a conductor layer for supporting the dielectric. It is disclosed. However, regarding the material of the intermediate transfer member, there is only a description that a material such as silicone coat or fluorine coat may be used, and there is no description about the material of the elastic layer and the swelling property of the surface layer.

Further, Japanese Patent Application Laid-Open No. 3-243973 (conventional example 2) discloses an intermediate transfer member in which a thin insulating dielectric layer is provided on an elastic layer having a property of absorbing a solvent in a liquid toner. It has been disclosed, and specifically, an intermediate in which a conductive silicone rubber is coated with an insulating silicone rubber is mentioned. As this effect, it is mentioned that the solvent in the toner image is positively absorbed by the intermediate transfer member to eliminate the crushing of the image. However, there is no description about the solvent absorption rate of the insulating dielectric layer, and the thickness of the insulating dielectric layer is described as about 5 to 30 μm.

Further, Japanese Patent Application Laid-Open No. 1-273075 (conventional example 3) discloses an intermediate transfer member in which a dielectric layer is formed on a conductive base material. Specifically, the intermediate transfer member is formed by providing a dielectric layer made of a polytetrafluoroethylene layer on a conductive base material made of urethane rubber.

[0006]

After the electrostatic latent image on the electrostatic latent image carrier is developed with liquid toner and the developed image visualized by this development is electrostatically transferred to the intermediate transfer body. The following items are necessary requirements for the intermediate transfer member used in the image forming method of re-transferring the visible image on the intermediate transfer member onto the transfer material. (1) The visible image is efficiently transferred to the intermediate transfer member. (2) The visible image on the intermediate transfer member is efficiently retransferred onto the transfer material. (3) No image deterioration occurs during transfer. (4) The intermediate transfer member has durability.

However, none of the above-mentioned conventional examples 1 to 3 satisfy the above conditions (1) to (4).

For example, in Conventional Example 1, since there is no specific description of the material of the intermediate transfer member, no knowledge can be obtained regarding durability and image deterioration during transfer.

In Conventional Example 2, there is a problem that the image formed on the intermediate transfer member is disturbed because the conductive silicone rubber layer used for the elastic layer of the intermediate transfer member is swollen by the solvent used for the liquid toner. Overlay multiple colors on the intermediate transfer body and
In the process of retransferring to paper by one transfer or the process of retransferring images on the intermediate transfer body to paper in order of yellow, magenta, cyan, black, for example, swelling of the intermediate transfer body causes There are problems such as difficult alignment. In addition, the thickness of the insulating dielectric layer is 5 μm.
When the size is made larger, a problem occurs in the color superimposing property in a process in which multiple colors are superposed on the intermediate transfer member and retransferred to paper in one transfer. Furthermore, when the conductive silicone rubber layer swells with an insulating solvent such as that used for liquid toner, the conductivity of the conductive silicone rubber layer decreases sharply, and the transfer of the toner image from the photoconductor to the intermediate transfer body occurs. There was also the problem of becoming difficult.

In the conventional example 3, since polyurethane rubber is used for the elastic layer, the heat resistance of the polyurethane rubber is insufficient when the method of re-transferring onto the transfer material with a heat roller is used. was there.

The present invention was conceived in view of the above-mentioned drawbacks, and an object thereof is to efficiently transfer a visible image to an intermediate transfer member, and to transfer the visible image on the intermediate transfer member to a transfer target. An object of the present invention is to provide an intermediate transfer member that satisfies the four requirements of being efficiently retransferred onto a material, no deterioration of an image during transfer, and durability of the intermediate transfer member.

[0012]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
The electrostatic latent image on the electrostatic latent image carrier is developed with liquid toner, the developed image visualized by this development is electrostatically transferred to the intermediate transfer body, and then the developed image on the intermediate transfer body. An intermediate transfer member used in an image forming method for retransferring
This is achieved by an intermediate transfer member characterized in that a silicone rubber layer having a swelling ratio of 50% or less in a liquid toner dispersion medium is provided on a conductive silicone rubber layer.

Hereinafter, the present invention will be described in detail.

The intermediate transfer member of the present invention is in the form of a belt in which a conductive silicone rubber layer and a silicone rubber layer are sequentially laminated on a substrate of aluminum, iron, plastic film or the like, or a drum of aluminum, iron or the like. It is used in the form of a drum in which a conductive silicone rubber layer and a silicone rubber layer are sequentially laminated. Further, an adhesive layer may be provided between the conductive silicone rubber layer and the substrate or between the conductive silicone rubber layer and the drum.

The conductive silicone rubber layer used in the intermediate transfer member of the present invention has a volume resistivity of 10 8 (Ω · c).
It is preferably m) or less, and more preferably 10 6 (Ω · cm) or less in volume resistivity. Here, when the volume resistivity exceeds 10 8 (Ω · cm), four colors are overlaid on the intermediate transfer body and the transferred image is transferred to the printing material at one time, and the transferred image on the intermediate transfer body is already transferred. When an attempt is made to transfer the visible image on the photoconductor onto the surface of the photoconductor, there arises a problem that the transferability is lowered.

Examples of such conductive silicone rubber layers include deoxime type silicone, deacetic acid type silicone, deacetone type silicone, deamidating type silicone, dealcohol type silicone, dehydroxyamine type silicone, dehydrogenation type silicone. Room temperature or heat curable silicones such as silicones and addition reaction type silicones, heat vulcanizable silicones such as methyl vinyl silicone, methylphenyl vinyl silicone, fluorosilicone, etc. in which carbon black, metal, metal oxide, etc. are dispersed. Used.

As the carbon black dispersed in the above silicone rubber, usual carbon black can be used, but in order to impart conductivity, it is preferable to use Ketjen black. The dispersion amount of carbon black is preferably 2% by weight or more and 10% by weight or less. If it is less than 2% by weight, the conductivity is insufficient, and if it exceeds 10% by weight, the smoothness of the surface of the conductive layer is lost.

The thickness of the conductive silicone layer is preferably 50 μm or more and 5,000 μm or less. More preferably 500 μm or more and 3,000 μm
It is the following.

If it exceeds 5000 μm, there arises a problem that the image is disturbed when a visible image is transferred from the photosensitive member to the intermediate transfer member. Further, if it is less than 50 μm, when transferring from the intermediate transfer member to the transfer target, the transfer rate becomes poor when the transfer target has poor surface smoothness such as paper.

Further, in order to prevent contact between the conductive silicone layer and the hydrocarbon solvent used for the liquid toner and prevent swelling of the conductive silicone layer, a low swelling silicone rubber layer is formed on the conductive silicone layer. Need to be coated.

The swelling ratio of the silicone rubber layer with respect to the liquid toner is 50% or less, preferably 30% or less, more preferably 20% or less. Swelling rate is 50%
If it exceeds, the solvent penetrates through the silicone rubber layer and the conductive silicone rubber layer as the lower layer is likely to swell. When the conductive silicone rubber layer swells, the visible image on the intermediate transfer body is disturbed, or multiple colors are superimposed on the intermediate transfer body and retransferred to paper in one transfer or an image on the intermediate transfer body. For example, in the process of retransferring to the paper in the order of yellow, magenta, cyan, and black, there is a problem that the alignment becomes difficult. Furthermore, when the conductive silicone rubber layer is swollen by an insulating solvent such as used for liquid toner, the conductivity of the conductive silicone rubber layer is drastically reduced and the transfer of the toner image from the photoconductor to the intermediate transfer body is prevented. There was also the problem of becoming difficult.

As the liquid toner used here, for example, colored particles composed of a resin, a colorant, etc. dispersed in a hydrocarbon-based insulating solvent in an amount of 0.1 to 20 wt% can be used. As the hydrocarbon solvent, for example, “Isopar” E, G, H, M, “Cristol” 52, 35
Examples include petroleum hydrocarbon solvents such as 2.

The swelling ratio was measured by measuring a sample obtained by solidifying and curing silicone rubber in a Teflon cup and measuring 2 × 4 cm.
The sample is cut into a corner, soaked in liquid toner for one day and then taken out, the weight is measured, and the swelling rate is calculated by dividing the sample by the original weight. Swelling rate (%) = {(weight after penetration−weight before penetration) / weight before penetration} × 100

The low swelling silicone rubber layer of the present invention may be made of any material as long as it satisfies a predetermined swelling rate with respect to the liquid toner, but durability, film-forming property and glossiness of printed image Therefore, it is preferable to use a polyorganosiloxane (silicone resin) containing a trifunctional or tetrafunctional siloxane unit in the molecule. As the silicone resin, for example, a known phenyl-based silicone resin,
Methyl-based silicone resin, methylphenyl-based silicone resin and the like are used, but not limited thereto.

The thickness of the low swelling silicone rubber layer is
It is preferably 0.2 μm or more and less than 5 μm. More preferably, it is 0.5 μm or more and less than 3 μm. 0.2
If it is less than μm, the solvent shielding effect becomes insufficient and the conductive silicone rubber layer may swell. When the thickness is 5 μm or more, the multiple colors are overlaid on the intermediate transfer member to
In the process of re-transferring onto paper by one transfer, there is a problem in color overlay.

The low swelling silicone rubber of the present invention has good adhesiveness because it is coated on a conductive silicone rubber having a high affinity, and since it is low swelling, the strain applied to the interface by swelling is low. A small and highly durable intermediate transfer member can be provided.

Next, an image forming method using the intermediate transfer member of the present invention will be described.

The intermediate transfer member of the present invention develops the electrostatic latent image on the electrostatic latent image bearing member with liquid toner, and electrostatically transfers the visualized image developed by this development to the intermediate transfer member. After that, it is used in an image forming method in which the visible image on the intermediate transfer member is retransferred onto the transfer material. This image forming method is used, for example, in a copying machine or a laser beam printer. Further, the intermediate transfer member of the present invention, when re-transferring the visible image on the intermediate transfer member to the transfer material, the transfer material is brought into close contact with the intermediate transfer member with a pressure roller to form the visible image on the transfer material. It is preferably used in the image forming method of retransferring to. As the pressure roller used here, a metal roller or a roller in which the surface of the metal roller is covered with a rubber having a high heat resistance such as silicone rubber or fluororubber in order to enhance the adhesion with the intermediate transfer member is used.

Further, it is preferable that the pressure roller is a heat roller containing a heat source and is used in the image forming method. As such a pressure roller, one having a cylindrical structure and containing a heat source such as a ceramic heater or a halogen lamp is used.

Further, the image forming method is a color image forming method, in which multiple colors are superposed on the intermediate transfer member to form a color image, and a visible image on the intermediate transfer member is formed by one transfer. An image forming method of re-transferring onto a transfer material is preferable.

The transfer material referred to in the present invention may be of any type as long as it is capable of ordinary printing, such as paper, plastic film, metal, cloth and board.

[0032]

EXAMPLES Next, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples.

Example 1 Methyl vinyl silicone in which 5% by weight of carbon black was dispersed was vulcanized and molded on an aluminum plate having a thickness of 0.2 mm to give a thickness of 1 mm and Shore A50,
A conductive silicone rubber elastic layer having a volume resistivity value of 5 × 10 ⁵ Ω · cm was formed.

A deoxime type silicone resin "SR-2411" (manufactured by Toray Dow Corning Silicone Co., Ltd.) having a swelling ratio of 15% with respect to a liquid toner using "Isopar H" is applied to this and a thickness of 2 .mu.m is applied. An intermediate transfer member was formed by providing a low swelling silicone layer.

Using a Se drum as a photosensitive member, developing with a liquid developer, yellow on an intermediate transfer member stuck on the drum,
An image is sequentially formed in the order of red, indigo, and black, and a full-color image is formed on the intermediate transfer body. The full-color image is applied with a linear pressure of 20 kg on the art paper, and the temperature of the pressure roller is 1
When the transfer was carried out under the condition of 50 ° C., a good printed matter could be obtained by transferring from the intermediate transfer member to the paper at a transfer rate of almost 100%.

Even after printing 2000 sheets in the above printing process, a good printed matter could be obtained with a transfer rate of almost 100% as in the initial performance.

(Example 2) Deoxime type silicone in which 7% by weight of carbon black was dispersed was applied on a 0.2 mm thick aluminum plate by a bar coater to give a thickness of 0.1 mm.
A conductive silicone rubber elastic layer having a Shore A55 and a volume resistivity of 2 × 10 ³ Ω · cm was formed.

To this, a dealcohol type silicone rubber "SR-2316" (manufactured by Toray Dow Corning Silicone Co., Ltd.) having a swelling ratio of 30% with respect to a liquid toner using "ISOPER M" is applied, and a thickness of 3 .mu.m is applied. An intermediate transfer member was formed by providing a low swelling silicone layer.

Using a Se drum as a photosensitive member, developing with a liquid developer, yellow on an intermediate transfer member attached on the drum,
An image is sequentially formed in the order of red, indigo, and black, and a full-color image is formed on the intermediate transfer body. The full-color image is applied with a linear pressure of 20 kg on the art paper, and the temperature of the pressure roller is 1
When the transfer was carried out under the condition of 50 ° C., a good printed matter could be obtained by transferring from the intermediate transfer member to the paper at a transfer rate of almost 100%.

Even after printing 2000 sheets in the above printing process, a good printed matter could be obtained with a transfer rate of almost 100%, similar to the initial performance.

(Comparative Example 1) Methyl vinyl silicone in which 5% by weight of carbon black was dispersed was vulcanized and molded on an aluminum plate having a thickness of 0.2 mm to give a thickness of 1 mm and Shore A50,
A conductive silicone rubber elastic layer having a volume resistivity value of 5 × 10 ⁵ Ω · cm was formed.

A deoxime type silicone rubber "PRX-305" (manufactured by Toray Dow Corning Silicone Co., Ltd.) having a swelling ratio of 100% with respect to a liquid toner using "Isopar H" is applied to this and a thickness of 2 μm is applied. An intermediate transfer member was formed by providing a silicone layer.

Using a Se drum as a photosensitive member, developing with a liquid developer, yellow on an intermediate transfer member attached on the drum,
An image is sequentially formed in the order of red, indigo, and black, and a full-color image is formed on the intermediate transfer body. The full-color image is applied with a linear pressure of 20 kg on the art paper, and the temperature of the pressure roller is 1
When transferred under the condition of 50 ° C., color misregistration occurred from the first sheet. Further, the conductivity of the conductive silicone rubber was lowered due to the swelling, so that transfer failure from the photosensitive member to the intermediate transfer member occurred from the second sheet.

[0044]

As described above, since the intermediate transfer member of the present invention has excellent durability and transferability, an image forming method using this intermediate transfer member produces a high quality image. It can be obtained with good reproducibility.

Claims (4)

[Claims] 1. An electrostatic latent image on an electrostatic latent image carrier is developed with liquid toner, the developed image visualized by this development is electrostatically transferred to an intermediate transfer body, and then the intermediate transfer is carried out. An intermediate transfer member used in an image forming method for retransferring a visible image on a body to a transfer material, the silicone rubber having a swelling ratio of 50% or less with respect to a liquid toner dispersion medium on a conductive silicone rubber layer. An intermediate transfer member, which is provided with a layer. 2. The intermediate transfer member according to claim 1, wherein the silicone rubber layer having a swelling ratio of 50% or less has a thickness of 0.2 μm or more and less than 5 μm. 3. The conductive silicone rubber layer has a thickness of 50 μm.
The intermediate transfer member according to claim 1, wherein the intermediate transfer member has a thickness of 5,000 μm or less. 4. An electrostatic latent image on an electrostatic latent image carrier is developed with liquid toner, and the developed image visualized by this development is electrostatically transferred to an intermediate transfer body, and then the intermediate transfer body. An image forming method for retransferring the above-mentioned visible image onto a transfer material, wherein the intermediate transfer member according to any one of claims 1 to 3 is used as the intermediate transfer member.