JPH0934270A - 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 specifying the swelling rate of a release layer to a liquid toner to a specific value. SOLUTION: The swelling rate of the release layer of the intermediate transfer medium provided with the release layer on the surface to the liquid toner is specified to 5 to 40%. The retransfer from the intermediate transfer medium onto the material to be transferred is inferior if the swelling rate is below 5%. The retransfer from the intermediate transfer medium to the material to be transferred is good and the glossiness of printed images is not good if the swelling rate exceeds 40%. The release layer may be formed of any materials, insofar as the materials satisfy the prescribed swelling rate to the liquid toner. The release layer consisting of a straight silicone resin is used more preferably in terms of durability, film formability and the glossiness of printed images.

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 bearing member with liquid toner, and electrostatically transfers the visualized image developed by this development to an intermediate transfer member. 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 description that a material such as silicone coat or fluorine coat may be used, and there is no description about swelling property of the surface layer.

Further, JP-A-3-243973 (Prior Art 2) discloses an intermediate transfer member having an elastic layer having a smooth surface and having a property of absorbing a solvent in a liquid toner. However, there is no description about the absorption rate of the solvent.
Further, as the effect of absorbing the solvent, the reason why the image is not crushed is mentioned.

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]

The requirements for the intermediate transfer member used in the above-described image forming method include the following items.

(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 and has gloss (3) At the time of transfer, No image deterioration (4) Durability of the intermediate transfer body

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

For example, it is difficult to obtain an image having glossiness and sufficient durability cannot be obtained only by using a material such as silicone coat or fluorine coat as in Conventional Example 1. In Conventional Example 2, when the elastic layer is made of conductive silicone rubber, there is a problem that the visible image on the intermediate transfer member is disturbed because the elastic layer swells with the solvent used for the liquid toner.

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

The present invention was devised 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. Being re-transferred onto the material efficiently and glossy, during transfer,
An object of the present invention is to provide an intermediate transfer member that satisfies the four requirements of no image deterioration 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 a 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. In an intermediate transfer member having a release layer on the surface used in an image forming method for retransferring an image onto a transfer material, the swelling ratio of the release layer with respect to liquid toner is 5% or more and 40% or less. And an intermediate transfer member characterized by the above.

Hereinafter, the present invention will be described in detail.

The release layer of the present invention is characterized in that the swelling ratio with respect to the liquid toner is 5% or more and 40% or less, preferably 5% or more and 20% or less.

If the swelling ratio is less than 5%, retransfer from the intermediate transfer member onto the transfer material will be defective. The reason for this is that, when considering the retransfer mechanism from the intermediate transfer body to the transfer material, a thin liquid film layer exuded from the intermediate transfer body layer swollen with the liquid toner is present between the toner image and the intermediate transfer body. It shows that the separation between the formed toner image and the intermediate transfer body occurs in this liquid film layer in order to obtain good retransfer.

On the other hand, when the swelling ratio exceeds 40%, the retransfer property from the intermediate transfer member to the transfer material is good, but the glossiness of the printed image is insufficient. Therefore, in order to obtain a glossy printed image, the swelling ratio of the release layer to the liquid toner needs to be 40% or less.

The liquid toner used here is generally one in which colorant particles composed of a resin, a colorant, etc. are dispersed in a hydrocarbon type insulating solvent in an amount of 0.1 to 20 wt%. As the hydrocarbon solvent, for example, “Isopar” E, G, H, M, “Cristol” 52,352
Petroleum hydrocarbon solvent such as.

The swelling ratio of the release layer of the present invention with respect to the liquid toner is measured by cutting out a sample of the release layer which has been solidified and cured in a Teflon cup into 2 × 4 cm square pieces, and immersing the sample in the liquid toner for one day. , Take out the sample, wipe the liquid toner adhering to the surface with a cloth like gauze, calculate the amount of liquid toner contained in the release layer from the weight difference before and after, and divide by the original weight of the release layer, Calculate the swelling rate.

The release 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 it is preferable to use a release layer made of straight silicone resin for durability and production. It is preferable in terms of film properties and gloss of printed images. 2 as a straight silicone resin layer
Organic per 1 silicon atom (Si) constituting a silicone molecule with a known DT resin having a functional (D unit) or trifunctional (T unit) siloxane unit of 10 mol% or more, preferably as a main skeleton. The ratio of the group (R) is R
A phenyl-based silicone resin, a methyl-based silicone resin, a methylphenyl-based silicone resin, etc. having an / Si ratio of 1.2 to 1.6 are used, but the invention is not limited thereto. Further, the curing mechanism is not limited to the heat curing type and the room temperature curing type.

Examples of such straight silicone resin include SR-2411 and S manufactured by Dow Corning Toray.
R-2306, SR-2316, DC-1-2577,
Examples include SR-2410, but are not limited thereto.

It is also possible to reinforce the silicone resin with an additive such as silica.

The thickness of the release layer is preferably 0.2 μm or more and 5 μm or less, more preferably 0.5 μm.
It is 3 μm or less. If it is less than 0.2 μm, retransfer from the intermediate transfer member to the transfer target is not sufficient, and it is 5 μm.
If it exceeds the above range, a problem occurs in the color superimposing property in the process of superimposing the four colors on the intermediate body and retransferring the paper to the paper in one transfer.

The intermediate transfer member of the present invention is provided with a release layer on the surface thereof, and a conductor layer is usually provided below the release layer with or without an adhesive layer. The structure may be in the form of a belt in which at least a conductor layer and a release layer are sequentially laminated on a substrate such as aluminum, iron, or a plastic film, or at least on a drum such as aluminum or iron, It may have a drum shape in which a conductor layer and a release layer are sequentially laminated. Further, an adhesive layer may be provided between the conductor layer and the substrate or between the conductor layer and the drum.

Examples of the conductor layer include conductive elastic bodies such as fluororubber, silicone rubber, acrylic rubber, neoprene rubber, urethane rubber, etc., which are electrically conductive. A rubber layer is preferred. That is, the conductive fluororubber layer is used as a conductive elastic layer, but when a heat roller including a heat source is used when transferring from an intermediate transfer member to a transfer material, A conductive fluororubber layer is most preferable because it is required to have heat resistance as the conductive elastic layer and further it is required not to swell in the hydrocarbon solvent used for the liquid toner.

Specific examples of the conductive fluororubber layer used in the intermediate transfer member of the present invention include vinylidene fluoride-hexafluoropropene type, vinylidene fluoride-chlorotrifluoroethylene type, vinylidene fluoride-penta. Fluoropropene-based, tetrafluoroethylene-propylene-based, fluorine-containing silicon-based, fluorine-containing nitroso-based, fluorine-containing triazine-based, and fluorine-containing phosphazene-based dispersions of carbon black are used to impart conductivity. To be

As the carbon black dispersed in the fluororubber, any known carbon black can be used, but it is preferable to use Ketjen black in order to impart good conductivity. The amount of carbon black dispersed is preferably 2% by weight or more and 10% by weight or less. If it is less than 2% by weight, the conductivity becomes insufficient, and 10
When the content exceeds the weight%, there arises a problem that the smoothness of the surface of the conductive fluororubber layer is lost.

The conductive fluororubber layer preferably has a volume resistivity of 10 8 (Ω · cm) or less.
It is more preferably 5 (Ω · cm) or less. When the volume resistivity exceeds 10 8 (Ω · cm), an image is formed by superimposing multiple colors on the intermediate transfer member, and a visible image on the intermediate transfer member is transferred by one transfer. In the case of re-transferring the image onto the intermediate transfer member, when the image on the photosensitive member is transferred onto the already transferred image on the intermediate transfer member, the problem that the transferability is lowered easily occurs.

The hardness of the conductive fluororubber layer is preferably Shore A20 or more and Shore D50 or less. More preferably, it is Shore A 20 or more and Shore A 80 or less. When the Shore A is less than 20, there is a problem that the image is disturbed when a visible image is transferred from the electrostatic latent image carrier (photoreceptor) to the intermediate transfer member. Also, Shore D50
When it exceeds the value, when transferring from the intermediate transfer member to the transfer target,
If the material to be transferred is a material such as paper having a poor surface smoothness, the problem of a poor transfer rate is likely to occur.

The thickness of the conductive fluororubber layer is 5
It is preferably 0 μm or more and 5,000 μm or less.
It is more preferably 500 μm or more and 3,000 μm or less. When it exceeds 5,000 μm, there is a problem that the image is disturbed when a visible image is transferred from the electrostatic latent image carrier (photoreceptor) to the intermediate transfer member. Further, when it is less than 50 μm, when transferring from an intermediate transfer member to a transfer material, a problem such as poor transfer rate is likely to occur when the transfer material is a material such as paper having poor surface smoothness. .

It is also possible to replace the lower side (substrate, drum side) of the conductive fluororubber layer with a layer made of another material. For example, a non-conductive fluororubber layer, a butyl rubber layer, a polyurethane rubber layer, a neoprene rubber layer, etc. which have a function as a cushion layer can be used. The thickness that can be replaced with another material such as a cushion layer is 40 to 4,000 μm.

When a conductive fluororubber layer is used as the conductor layer, an adhesive layer is preferably provided in order to bond the release layer (silicone resin layer) and the conductive fluororubber layer. If there is no adhesive layer, the silicone resin layer and the conductive fluororubber layer are not sufficiently adhered to each other, so that the durability or printing durability is not good and a practical intermediate transfer member cannot be obtained.

As the adhesive layer, there can be used a primer or the like which is usually used for adhesion of silicone rubber, but it is preferable to contain at least one selected from the group of aminosilane coupling agents and titanic acid ester coupling agents. .

As the aminosilane coupling agent,
3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyldiethylmethylsilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, p-aminophenyltrimethoxysilane, etc. However, the present invention is not limited to these. Among these, particularly preferred are
3-aminopropyltriethoxysilane and N- (2-aminoethyl) -3-aminopropyltrimethoxysilane.

Examples of titanate ester coupling agents include tetramethyl titanate, tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate,
Tetrabutyl titanate, tetra (2-ethyl) titanate
Examples include, but are not limited to, hexyl, tetrastearyl titanate, tetraphenyl titanate, tetratolyl titanate, tetraxyl titanate, and the like. Among these, particularly preferable are tetraisopropyl titanate and tetrabutyl titanate.

It is also possible to mix known silane coupling agents other than the above. Specific examples thereof include allyldimethylsilane, benzyldimethylsilane, 2- (bicycloheptyl) methyldichlorosilane, and 2-acetoxyethyltrichlorosilane, but are not limited thereto.

In this case, the content ratio of the aminosilane coupling agent and / or the titanic acid ester coupling agent is preferably 10 to 100% by weight, more preferably 20 to 100% by weight, further preferably 40 to 10% by weight.
0% by weight. If the content ratio of the aminosilane-based coupling agent and / or the titanate ester-based coupling agent is too low, the good characteristics of the aminosilane-based coupling agent and / or the titanate-ester-based coupling agent may be lost.

If desired, these coupling agents may be diluted with a solvent such as methanol, ethanol, propanol, butanol, hexane, benzene, toluene, xylene, methylene chloride, chloroform, carbon tetrachloride and the like.

The thickness of the adhesive layer is 0.2 μm or more and 5
μm or less is preferable. If it is less than 0.2 μm, the adhesiveness is insufficient, and if it exceeds 5 μm, cohesive failure occurs inside the adhesive layer, resulting in poor adhesiveness. Furthermore, since the thickness of the dielectric layer (silicone resin layer + adhesive layer) becomes thicker,
Poor color stackability.

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 carrier with liquid toner, and electrostatically transfers the visualized image developed by this development to the intermediate transfer member. After that, it is used in the image forming method of re-transferring the visible image on the intermediate transfer member onto the transfer material. This image forming method is used, for example, in a copying machine or a laser beam printer.

The intermediate transfer member of the present invention is, among other things, an image forming method in which the transfer material is brought into close contact with the intermediate transfer member by a pressure roller when the transferred image is retransferred onto the transfer material. It is preferably used. Examples of the pressure roller used here include a metal roller, and a roller in which the surface of the metal roller is covered with a highly heat-resistant rubber such as silicone rubber or fluororubber in order to enhance the adhesion with the intermediate transfer member. In particular, it is preferable that the pressure roller is a heat roller containing a heat source and used in the image forming method. As such a pressure roller, one having a cylindrical structure and including a heat source such as a ceramic heater or a halogen lamp can be mentioned.

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 an image onto a transfer material is preferable.

The material to be transferred referred to in the present invention is as follows.
Any kind of paper, plastic film, metal, cloth, board, etc. can be used as long as it can be printed normally.

[0044]

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) A layer obtained by vulcanizing and adhering conductive fluororubber having a Shore A hardness of 80 and a thickness of 1000 µm is provided on an aluminum plate having a thickness of 225 µm, and an adhesive layer made of 3-aminopropyltriethoxysilane is provided thereon. Was set to 1 μm.
Further, a release layer further containing 10 mol% or more of siloxane units of D units and T units and having an R / Si ratio of 1.
2μ of a resin type silicone layer (SR-2411: manufactured by Toray Dow Corning) in the range of 2 to 1.6
By providing m, an intermediate transfer member was formed.

As the liquid toner, a pigment, an ethylene-vinyl acetate copolymer resin, cobalt naphthenate, and Isopar H are wet-dispersed in a ball mill at a ratio of 3: 3: 1: 93, and the swelling ratio of the release layer is determined. When measured, it was 8%. Using such an intermediate transfer member, using a Se drum as a photosensitive member, developing with a liquid developer, an image is sequentially formed on the intermediate transfer member attached on the drum in the order of yellow, red, indigo, and black, A full-color image is formed on the intermediate transfer member, and the full-color image is applied to the mirror-coated paper with a linear pressure of 20 kg,
Further, when the transfer was performed under the condition that the temperature of the pressure roller was 200 ° C., the transfer rate from the intermediate transfer body to the paper was almost 100%, and a good glossy printed matter could be obtained.
Further, 2,000 sheets were continuously printed, but a printed matter equivalent to the first sheet was obtained, and the intermediate transfer body could be used without any defect.

(Example 2) A layer obtained by vulcanizing and adhering conductive fluororubber having a Shore A hardness of 50 and a thickness of 500 µm is provided on an aluminum plate having a thickness of 150 µm, and an adhesive layer made of 3-aminopropyltriethoxysilane is provided thereon. Was set to 1 μm. Further, as a release layer, 10 mol% or more of D units and T units of siloxane units having intermediate properties between silicone resin and silicone rubber are contained therein, and the R / Si ratio is 1.2 to 1.6. 1 of a resin type silicone layer (SR-2316: manufactured by Toray Dow Corning) in the range of
An intermediate transfer member was formed by providing a thickness of μm.

When the swelling ratio of the release layer was measured in the same manner as in Example 1, it was 15%. Using such an intermediate transfer member, using a Se drum as a photosensitive member, developing with a liquid developer, yellow, red, indigo,
Images are sequentially formed in the order of black ink, and a full-color image is formed on the intermediate transfer body.
When a linear pressure of g was applied and the transfer was carried out under the condition that the temperature of the pressure roller was 200 ° C., the transfer rate from the intermediate transfer member to the paper was almost 100% and a very glossy and good printed matter was obtained. did it. Further, 2,000 sheets were continuously printed, but a printed matter equivalent to the first sheet was obtained, and the intermediate transfer body could be used without any defect.

(Comparative Example 1) An electrically conductive fluororubber having a Shore A hardness of 80 and a thickness of 1000 μm was vulcanized and adhered on an aluminum plate having a thickness of 250 μm, and an adhesive layer made of 3-aminopropyltriethoxysilane was provided thereon. Was set to 1 μm.
Further, a room temperature curing type deoxime type silicone rubber layer having a thickness of 2 μm was provided thereon as a release layer to form an intermediate transfer member.

When the swelling ratio of the release layer was measured in the same manner as in Example 1, it was 200%. Using such an intermediate transfer member, a printing test was conducted in the same manner as in Example 1. As a result, the transfer rate from the intermediate transfer member to the paper was 100%, and the image was not disturbed, but the glossiness was the same as that of the above-mentioned Example. It was inferior to 1 and 2.

(Comparative Example 2) A layer obtained by vulcanizing and adhering conductive fluororubber having a Shore A hardness of 50 and a thickness of 500 μm is provided on an aluminum plate having a thickness of 150 μm, and an adhesive layer made of 3-aminopropyltriethoxysilane is provided thereon. Was set to 1 μm. Further, a room temperature-curable deacetic acid type silicone rubber layer was provided thereon as a release layer in an amount of 5 μm to form an intermediate transfer member.

When the swelling ratio of the release layer was measured in the same manner as in Example 1, it was 200%. Using such an intermediate transfer member, a printing test was conducted in the same manner as in Example 2. As a result, the transfer rate from the intermediate transfer member to the paper was up to 70%, and satisfactory results were not obtained in terms of image and glossiness. It was

[0053]

As described above, the intermediate transfer member of the present invention has excellent transferability and durability, and has excellent gloss in full-color printing, and the image forming method using this intermediate transfer member is high. It is possible to obtain a high quality image with good reproducibility.

Claims (4)

[Claims] 1. An electrostatic latent image on an electrostatic latent image carrier is a liquid toner.
It is used in an image forming method in which the developed image is developed by electrostatically, the developed image is electrostatically transferred to an intermediate transfer body, and then the developed image on the intermediate transfer body is retransferred onto a transfer material. An intermediate transfer member having a release layer on the surface thereof, wherein the swelling ratio of the release layer with respect to the liquid toner is 5% or more and 40% or less. 2. The intermediate transfer member according to claim 1, wherein the release layer is made of a straight silicone resin. 3. The intermediate transfer member according to claim 1, wherein a release layer, an adhesive layer and a conductive fluororubber layer are provided in this order from the outer surface side. 4. 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 image forming method for retransferring a visible image on a body to a transfer material, wherein the intermediate transfer body according to any one of claims 1 to 3 is used as the intermediate transfer body.