JPH08179584A - Manufature of intermediate transfer body and image forming device using the manufactured intermediate transfer body - Google Patents

Abstract

PURPOSE: To provide the manufacturing method of an intermediate transfer body, capable of manufacturing the intermediate transfer body enhanced in the affinity of an elastic layer and a covering layer and further, being homogeneous, without causing filiming and to provide an image forming device using the intermediate transfer body manufactured by this method. CONSTITUTION: In the method of manufacturing the intermediate transfer body 20 of coating the elastic layer 101 with paint for the covering layer to form the covering layer 102, the solubility index SP1 of a high polymer contained in the elastic layer 101 and the solubility index SP2 of a solvent used for the paint for the covering layer are in the relation of |SP1-SP2|<=4. The image forming device is provided with the intermediate transfer body 20 manufactured in this method and an image carrier 1 for transferring an image to the intermediate transfer body 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an intermediate transfer member used in an electrophotographic image forming apparatus and an image forming apparatus using the intermediate transfer member manufactured by this manufacturing method.

[0002]

2. Description of the Related Art An image forming apparatus using an intermediate transfer member is
A color image forming apparatus, a multicolor image forming apparatus, or a color image that outputs an image formed product in which a plurality of component color images of color image information and multicolor image information are sequentially transferred in layers It is effective as an image forming apparatus having a forming function and a multicolor image forming function, and it is possible to obtain an image with no misregistration (color misregistration) of each component color image.

In a color electrophotographic apparatus having an image forming apparatus using an intermediate transfer member, a second image carrier is stuck or adsorbed on a transfer drum which is a conventional technique, and the first image carrier ( A color electrophotographic apparatus having an image forming apparatus for transferring an image onto a photoconductor, for example, JP-A-63-63
It is superior to the transfer method as described in JP-A-301960 in the following points. That is, there is little color shift when the toner images of the respective colors are superposed. In addition, the second image carrier can be selected in various ways. For example,
Thin paper (40 g / m ² paper) to thick paper (200 g / m ²⁾
Paper) can be selected. Transfer is possible regardless of the width of the second image carrier or the length of the second image carrier. Furthermore, it is possible to handle envelopes, postcards, label paper, and the like.

Further, since the intermediate transfer member is excellent in rigidity, it is unlikely that dimensional accuracy such as dents and strain deformations will occur due to repeated use, so that the frequency of replacement of the intermediate transfer member can be reduced.

As described above, due to the advantage of using the intermediate transfer member, color copiers, color printers and the like using this image forming apparatus have already started to move in the market.

In most cases, the intermediate transfer member is rarely used as a single layer, and is used in a multilayer structure in which the functions of each layer are separated, such as an elastic layer and a surface layer, and an elastic layer and a multilayer coating layer. Is common. At this time, as a method for forming the coating layer on the elastic layer, there are melt molding, injection molding, dip coating, spray coating and the like. When it is desired to form a coating layer having a thickness of 1 mm or less on the elastic layer, dip coating or spray coating is preferable. In the above-mentioned coating method, a coating material for coating is prepared in advance and applied to the intermediate transfer member having the elastic layer. Such a coating method enables continuous production of the intermediate transfer member. It can be produced at a relatively low cost. There are advantages such as not requiring a mold or a large molding device.

[0007]

However, on the other hand, unevenness in the thickness of the coating layer in the coating process, poor adhesion with the elastic layer, unevenness in electric resistance and surface roughness, etc. are likely to occur. Furthermore, uneven electric resistance, cracks and peeling of the coating due to uneven heating in the drying step of the coating layer are likely to occur.

When these defects occur, the transfer efficiency decreases due to partial electric resistance unevenness, and the characters 110 shown in FIG.
The image having the hollow portion 110a as described above, the coating layer floats from the elastic layer when repeatedly used, and the portion is not energized, resulting in image defects such as a ring-shaped or dot-shaped white image dropout.

Further, when the intermediate transfer body is repeatedly used, there is a case where so-called filming occurs in which toner which cannot be completely removed by a cleaner is accumulated on the surface of the intermediate transfer body. When filming occurs, it becomes difficult for the toner to be transferred from the first image bearing member to the intermediate transfer member, and a speckled white image is formed.

Several proposals have hitherto been made as materials used for the intermediate transfer material (see, for example, Japanese Patent Laid-Open No. Hei 4-
No. 81786, JP-A-4-88385, JP-A-3-242667, JP-A-5-333725).

The present invention has been made in view of the above-mentioned achievements, and is an intermediate transfer member capable of producing an intermediate transfer member which enhances the affinity between the elastic layer and the coating layer and is uniform and free from filming. An object of the present invention is to provide a manufacturing method and an image forming apparatus using the intermediate transfer member manufactured by this manufacturing method.

[0012]

The method for producing an intermediate transfer member of the present invention comprises coating a coating material for a coating layer on an elastic layer to form a coating layer. The solubility index SP1 of the coalescence and the solubility index SP2 of the solvent used for the coating material for the previous coating layer have a relationship of | SP1-SP2 | ≦ 4.

The image forming apparatus of the present invention has an intermediate transfer member manufactured by the above manufacturing method and an image carrier for transferring an image to the intermediate transfer member.

The intermediate transfer member according to the present invention is used in a color image forming apparatus (copier or laser beam printer) utilizing an electrophotographic process as shown in FIG. In the image forming apparatus of FIG. 1, a medium resistance roller 20 is used as an intermediate transfer member.

Reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) which is repeatedly used as a first image bearing member, and rotates in a clockwise direction indicated by an arrow at a predetermined peripheral speed (process speed). Driven.

In the course of rotation, the photosensitive drum 1 is uniformly charged to a predetermined polarity and potential by a primary charger (corona discharger) 2, and then an image exposing means (not shown) for color separation / combination of color original images. (Image exposure optical system, scanning exposure system with a laser scanner that outputs a laser beam modulated in accordance with time series electric digital pixel signals of image information, etc.)
By receiving the image exposure 3 by, the electrostatic latent image corresponding to the first color component image (for example, magenta component image) of the target color image is formed.

Then, the electrostatic latent image is transferred to the first developing device 41.
It is developed by the magenta toner M which is the first color by the (magenta developing device). At this time, the second to fourth developing devices 42,
43, 44 (cyan, yellow, black developing devices)
Is activated-off and does not affect the photosensitive drum 1,
The magenta toner image of the first color is not affected by the second to fourth developing units 42 to 44.

The intermediate transfer member 20 is rotationally driven in the counterclockwise direction indicated by the arrow at the same peripheral speed as the photosensitive drum 1. The intermediate transfer body 20 is a pipe-shaped core metal 100 that is a support.
And the elastic layer 101 formed on the outer peripheral surface thereof and the coating layer 1
02 and.

The above-mentioned first formed and carried on the photosensitive drum 1.
While the color magenta toner image passes through the nip portion between the photosensitive drum 1 and the intermediate transfer body 20, the outer peripheral surface of the intermediate transfer body 20 is formed by the electric field formed by the primary transfer bias applied to the intermediate transfer body 20. Are sequentially transferred to the intermediate transfer.

The surface of the photosensitive drum 1 on which the transfer of the magenta toner image of the first color onto the intermediate transfer member 20 is completed is cleaned by the cleaning device 14.

Similarly, the second color cyan toner image,
The yellow toner image of the third color and the black toner image of the fourth color are sequentially superimposed and transferred onto the intermediate transfer body 20, and a composite color toner image corresponding to the target color image is formed.

Reference numeral 25 is a transfer roller, which is arranged in parallel with the intermediate transfer member 20 so as to be in contact with the lower surface of the intermediate transfer member 20.

First from the photosensitive drum 1 to the intermediate transfer member 20
~ The primary transfer bias for the sequential superposition transfer of the toner image of the fourth color is the bias power source 6 with the polarity (+) opposite to that of the toner.
It is applied from 1. The applied voltage is, for example, +2 kV to +
It is in the range of 5 kV.

First from the photosensitive drum 1 to the intermediate transfer body 20
The transfer roller 25 and the intermediate transfer member cleaner 35 can be separated from the intermediate transfer member 20 in the process of sequentially transferring the fourth color toner image.

The transfer of the composite color toner image superposedly transferred onto the intermediate transfer member 20 onto the transfer material 24 which is the second image carrier is performed while the transfer roller 25 is brought into contact with the intermediate transfer member 20 and is supplied. The transfer material 24 such as paper is fed from the paper cassette 9 to the contact nip between the intermediate transfer body 20 and the transfer roller 25 at a predetermined timing, and at the same time, the secondary transfer bias is applied from the bias power source 29 to the transfer roller 25. . The secondary transfer bias causes the synthetic color toner image to be transferred from the intermediate transfer member 20 to the transfer material 24 which is the second image carrier. The transfer material 24 that has received the toner image transfer is introduced into the fixing device 15 and is heated and fixed.

After the transfer of the image to the transfer material 24 is completed, the transfer residual toner on the intermediate transfer body 20 is cleaned by contact with the intermediate transfer body cleaner 35.

As shown in FIG. 2, the intermediate transfer member according to the present invention has at least an elastic layer 101 and a coating layer 102 on the outer peripheral surface of a cored bar 100 as a support. Alternatively, FIG.
As shown in FIG.
Has 03. The coating layer may have a plurality of layers.
Further, the intermediate transfer member may be formed by laminating the elastic layer and the coating layer without using the support. In this case, a cover layer may be laminated on the front and back of the elastic layer with the elastic layer sandwiched in the middle.

The elastic layer contains a polymer such as rubber, elastomer or resin. The elastic layer is melt-formed,
It is provided by injection molding, dip coating or spray coating. Preferred high molecular polymers contained in the elastic layer include, for example, styrene-butadiene rubber, high styrene rubber, butadiene rubber, isoprene rubber, ethylene-propylene copolymer, nitrile butadiene rubber, chloroprene rubber, butyl rubber, silicone rubber, fluororubber. , Nitrile rubber, urethane rubber, acrylic rubber, epichlorohydrin rubber, norbornene rubber and the like. or,
Examples of the resins include polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate. Copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene- Octyl acrylate copolymer and styrene-phenyl acrylate copolymer), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate) Copolymer and styrene-methacrylic acid copolymer Cycloalkenyl copolymer), styrene -α
-Methyl chloroacrylate copolymer, styrene resin such as styrene-acrylonitrile-acrylic acid ester copolymer (a homopolymer or copolymer containing styrene or a styrene substituent), vinyl chloride resin, styrene-vinyl acetate copolymer Polymer, rosin-modified maleic acid resin, phenol resin, epoxy resin, polyester resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin,
Polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral resin, etc. are mentioned.

For the coating layers 102 and 103, for example, a resistance adjusting agent, a release agent, a binder resin, a viscosity adjusting agent, a coloring agent, etc. are appropriately selected, and these components are dispersed and suspended in a solvent to prepare a coating layer coating material. After that, it is formed on the elastic layer 101 by dip coating, spray coating, blade coating, roller coating, curtain coating, or the like.

Examples of the solvent for the coating material for the coating layer include alcohols such as methanol, ethanol and isopropanol, ketones such as acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl propyl ketone and microhexanone, N, N-dimethylformamide, N. ,
Amides such as N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, tetrahydrofuran, dioxane, diethyl ether, ethers such as ethylene glycol monomethyl ether, methyl acetate,
Esters such as ethyl acetate, isobutyl acetate, isopropyl acetate, aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, trichloroethylene benzene, ethylbenzene, toluene, xylene, ligroin, monochlorobenzene, Aromatic n-pentane such as dichlorobenzene, aliphatic hydrocarbons such as n-hexane and n-octane, and water can be used.

In the present invention, the solubility index SP1 of the high molecular weight polymer contained in the elastic layer and the solubility index SP2 of the solvent used for coating the coating layer adjacent to the elastic layer are | SP1.
-SP2 | ≤4. The elastic layer and the coating layer in this relationship have a high affinity, and the coating layer is not simply supported on the elastic layer, but the coating layer component penetrates into the elastic layer to form the elastic layer and the coating layer. The boundary is not clear. By forming such a layer structure, the coating layer becomes homogeneous with high film strength.

As a result, when a DC bias is applied to the conductive support of the intermediate transfer member, uniform electric resistance can be obtained over the entire surface of the intermediate transfer member, and the transfer efficiency can be further improved.

The relationship between the solubility index SP1 of the high molecular polymer and the solubility index SP2 of the solvent may be within the range of the above-mentioned formula, and does not depend on the magnitude of SP1 and SP2.

The solubility index (SP value) is a characteristic value which is a measure of the mixing property, and the solubility index δ is given by the following equation, where E is the molecular cohesive energy and V is the molecular volume. δ = (E / V) ^1/2 solubility index (SP value) is one of the indices expressing the intermolecular force of a substance, and is a Journal Apply Poly
mer Science, 19, 1163 (1975)
According to the literature, it is shown as the sum of each force (energy) of dispersive force, polar effect, and hydrogen bond.

The elastic layer preferably has a thickness of 0.5 to 10 mm. The thickness of the coating layer is preferably a thin layer for transmitting the flexibility of the lower elastic layer to the surface of the photoreceptor, specifically 3 mm or less, further 2 mm or less, and particularly 20 μm to 1 mm. Preferably there is.

As the conductive support, for example, a metal or alloy such as aluminum, iron, copper and stainless steel, a conductive resin in which carbon or metal particles are dispersed, or the like can be used. A belt shape is preferable.

The volume resistivity of the intermediate transfer member is 10 ¹ to 10 ¹³
Ω · cm is preferable, and particularly 10 ² to 10 ¹⁰
It is preferably Ω · cm. In order to control the resistance as described above, a conductive substance can be added to the elastic layer or the coating layer at appropriate times within a range that does not impair the performance. Examples of the conductivity control substance include a conductive particle dispersed resin and a conductive resin. As the conductive particle dispersed resin,
For example, conductive particles of carbon, aluminum, nickel, etc. may be dispersed in a resin such as urethane, polyester, vinyl acetate-vinyl chloride copolymer or polymethylmethacrylate, and the conductive resin may be, for example, 4 Examples thereof include primary ammonium salt-containing polymethylmethacrylate, polyvinylaniline, polyvinylpyrrole, polydiacetylene and polyethyleneimine. Among these, the conductive particle-dispersed resin is preferable from the viewpoint of controlling the conductivity. In addition, as the conductivity control substance,
Examples thereof include conductive metal oxides, antistatic surfactants, and metal fine particles.

The image forming apparatus shown in FIG. 4 uses a belt-shaped intermediate transfer member 104 as an intermediate transfer member.

As the first image bearing member used in the image forming apparatus of the present invention, a roller-shaped or belt-shaped photosensitive member can be used. The roller-shaped photosensitive member has higher transfer efficiency and image superposition (registration). It is preferable in the present invention that the deviation of () can be suppressed to a minimum. This is presumed to have a favorable effect because the rigid intermediate transfer member and the rigid photosensitive drum come into contact with each other.

As the photosensitive layer of the photosensitive member, an OPC (organic photoconductor-containing) photosensitive layer, in particular, one having a layer containing fluororesin particles on the outermost side thereof reduces friction with the intermediate transfer member. The advantages are that high durability is obtained, transfer efficiency is improved, and partial transfer failure is prevented.

[0041]

The present invention will be described in detail with reference to the following examples.
In addition, "part" shown below means a "polymerization part."

(Example 1) Diameter 182 mm, length 320
A roller (A) having an elastic layer with a thickness of 1 mm was obtained by transfer molding a rubber compound having the following composition using a metal mold on the surface of an aluminum cylindrical roller having a thickness of 5 mm and a thickness of 5 mm.

Rubber compounded SBR rubber 100 parts Sulfur 4 parts Vulcanization accelerator 1.2 parts (N-microhexyl-2-benzothiazole sulfenamide CBS) Paraffin oil 35 parts Conductive tin oxide 40 parts Zinc oxide 5 parts

Next, in order to obtain a coating layer as the upper layer, a coating material for coating layer was obtained based on the following formulation. Isobutyl acetate and methyl propyl ketone were used as the solvent at this time.

Coating material for coating layer Urethane modified polyester resin 100 parts Medium resistance conductive carbon black 15 parts PVDF fine powder (average particle size 1.0 μm) 30 parts Curing agent (MDI) 4 parts Solvent (isobutyl acetate / methyl propyl ketone = 1: 1) 100 copies

The coating material for coating layer was produced as follows.
First, the above components containing only 50 parts of a solvent were put together with 200 parts of glass beads in a 500 ml stainless container, which was tightly stoppered and mixed and dispersed by a paint shaker for about 10 hours. After that, a solvent was added up to a predetermined amount and dispersion strengthening was performed using a high-pressure liquid collision type homogenizer (trade name Nanomizer) to obtain a coating layer coating material.

The above roller (A) is attached to a work which can rotate up to 50 to 1000 revolutions / minute, and the above coating material for coating is sprayed on the surface of the rotating roller (A) (pressure is 0.5 to 5 Kg / min). thereby forming a coating layer of 85μm thickness to rollers (a) surface was spray applied by variably) to cm ^2. Then, at 80 ° C for 2 hours, then 1 hour
By performing a heat treatment at 00 ° C. for 1 hour, the residual solvent was removed to obtain an intermediate transfer member having a tough coating layer on the roller (A) surface. The high polymer SBR used at this time
The solubility indexes of the rubber, and isobutyl acetate and methyl propyl ketone used as the solvent are 8.7 and 8.
It was 3, 8.7.

This intermediate transfer member was mounted in the full-color electrophotographic apparatus shown in FIG. 1, and the fluororesin particles 2 were used as a photosensitive member.
Using an OPC photosensitive drum having a polycarbonate surface layer in which 0 part was dispersed, a full color image copying test was repeatedly performed.

The transfer efficiency from the photosensitive drum, which is the first image carrier, to the intermediate transfer member (hereinafter referred to as the primary transfer efficiency) is 9
3%, from the intermediate transfer member to the second image bearing member 80 g /
The transfer efficiency of cm ² to paper (hereinafter referred to as secondary transfer efficiency) was 90%. In addition, the full-color copied image had characters and fine lines without voids, and the solid image had a uniform image quality. After the durability test of 10,000 sheets, the same image quality as that at the initial stage was obtained, and the secondary transfer efficiency was 91%, which was almost unchanged. When the surface of the intermediate transfer body after 10,000 sheets were observed under a microscope, there was no filming due to the toner.

Next, a full-tone halftone image having an image density of 0.6 to 0.8 was copied to check the homogeneity of the image quality, but it was good with no partial density unevenness or a blank image. .

Furthermore, the durability of the intermediate transfer member, which was used 10,000 sheets, was confirmed by repeating charge-discharge only without developing the toner up to 50,000 sheets, and the durability was confirmed. Scraping and peeling between the elastic layer and the coating layer did not occur at all.

The image forming conditions of this embodiment are shown below.

Photoconductor: OPC photosensitive drum Surface potential: -700V Color developer: Nonmagnetic-component toner (for all four colors) Primary transfer voltage: + 900V Secondary transfer voltage: + 3400V Process speed: 120mm / s Development bias: -500V

Example 2 A durability test was conducted in the same manner as in Example 1 except that the coating composition for the coating layer was changed as follows. In terms of image quality, a good full-color copied image which is the same as the initial one was obtained even after 20,000 sheets.

Coating layer coating acrylic modified polyurethane 60 parts conductive titanium oxide 20 parts conductive tin oxide 25 parts curing agent (isocyanate compound) 20 parts acetone (solvent) 100 parts The solubility index of acetone was 9.9.

Example 3 The coating material for the coating layer used in Example 1 was applied to the surface of an endless polytetrafluoroethylene belt (solubility index 6.2) to obtain a belt-shaped intermediate transfer member. . This belt was subjected to 10,000 sheets of durability test using the full-color electrophotographic apparatus shown in FIG. As a result, no filming occurred, the image quality was uniform in the halftone, and the characters were good with no voids.

Example 4 An intermediate transfer member was obtained in the same manner as in Example 1, except that fluorocarbon rubber (solubility index 7.3) in which conductive carbon was dispersed was used for the elastic layer. This intermediate transfer member was mounted on the apparatus shown in FIG. 1, and idling was performed for 50,000 sheets without supplying toner. OP as a photosensitive drum
A C photosensitive drum having no surface layer containing fluororesin particles was used.

After that, a graphic image and a halftone image were printed. The graphic image had fine fine lines and excellent sharpness, and there was no hollow image. or,
The halftone image was a uniform and good image without any partial image density unevenness or transfer defects such as white defects.

Comparative Example 1 Highly conductive carbon black 6
Part dispersed methyl silicone rubber (solubility index 7.
5) was used as an elastic layer, and the coating material for the coating layer having the following coating composition was applied onto the elastic layer by dip coating to obtain an intermediate transfer member.

Using this intermediate transfer member, a repeated print test was carried out on 10,000 sheets of cyan only in the same manner as in Example 1.

Coating layer coating Alkoxymethyl nylon resin 100 parts Conductive tin oxide 60 parts Colloidal silica 10 parts Ethanol (solubility index 12.7) 150 parts

The halftone image in the initial stage was uniform and had no density unevenness, but after 10,000 sheets, the transfer of minute white spots, which seems to be caused by partial unevenness of the electric resistance, was observed on the entire halftone image. The omission occurred. Further, on the surface of the intermediate transfer member, the toner that could not be cleaned was partially adhered to the thin layer, and the adhesion of the toner, which is presumed to be the initial stage of filming, was also recognized.

[0063]

As described above, according to the intermediate transfer member of the present invention, the transfer efficiency from the first image carrier to the intermediate transfer member and from the intermediate transfer member to the second image carrier is high. Paper or O
It is possible to obtain a uniform image without image defects such as hollow images, regardless of the type of HP sheet. Good characteristics are maintained even after endurance. Filming due to toner adhesion to the intermediate transfer member does not occur.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an electrophotographic apparatus having an intermediate transfer member according to the present invention.

FIG. 2 is a schematic sectional view of an example of an intermediate transfer member according to the present invention.

FIG. 3 is a schematic sectional view of an example of an intermediate transfer member according to the present invention.

FIG. 4 is a schematic sectional view of an electrophotographic apparatus having an intermediate transfer member according to the present invention.

FIG. 5 is an example of a hollow image.

[Explanation of symbols]

 1 Photosensitive Drum 20 Intermediate Transfer Body 100 Support 101 Elastic Layers 102, 103 Covering Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsushi Tanaka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Tsunenori Ashibe 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (5)

[Claims] 1. A method for producing an intermediate transfer member, comprising applying a coating material for a coating layer to an elastic layer to form the coating layer, wherein the solubility index SP1 of the high molecular polymer contained in the elastic layer and the coating layer are used. Solubility index SP2 of solvent used for paint
A method of manufacturing an intermediate transfer member, wherein P1-SP2 | ≦ 4. 2. An image forming apparatus having an intermediate transfer member manufactured by the manufacturing method according to claim 1, and an image carrier for transferring an image to the intermediate transfer member. 3. The image forming apparatus according to claim 2, wherein both the intermediate transfer member and the image carrier are roller-shaped. 4. The image forming apparatus according to claim 2, wherein the intermediate transfer member has a belt shape, and the image carrier has a roller shape. 5. The image forming apparatus according to claim 2, wherein the image carrier is an electrophotographic photoreceptor having an outermost layer containing fluororesin particles.