JP3278310B2 - Method of manufacturing intermediate transfer body and image forming apparatus using intermediate transfer body manufactured by this manufacturing method - Google Patents

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 the method.

[0002]

2. Description of the Related Art An image forming apparatus using an intermediate transfer member includes:
A color image forming apparatus, a multi-color image forming apparatus, or a color image forming apparatus that sequentially transfers a plurality of component color images of color image information or multi-color image information and outputs an image formed product by combining and reproducing a color image or a multi-color image. The image forming apparatus is effective as an image forming apparatus having a forming function and a multicolor image forming function, and can obtain an image without overlapping deviation (color deviation) 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 a first image carrier (hereinafter referred to as a first image carrier) is attached thereto. Color electrophotographic apparatus having an image forming apparatus for transferring an image from above (photoreceptor)
It is superior to the transfer method as described in JP-A-301960 in the following points. That is, there is little color shift at the time of superimposing the toner images of each color. In addition, the second image carrier can be selected in various ways. For example,
From thin paper (40 g / m ² paper) to thick paper (200 g / m ²
Paper). Transfer is possible regardless of the width of the second image carrier or the length of the second image carrier. Further, it can be applied to envelopes, postcards, label paper, and the like.

In addition, since the intermediate transfer member is excellent in rigidity, it is difficult for dimensional accuracy such as dents and strain deformation to 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 advantages of using the intermediate transfer member, a color copying machine, a color printer, and the like using this image forming apparatus have begun to move in the market.

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

[0007]

However, on the other hand, thickness unevenness of the coating layer in the coating process, poor adhesion to the elastic layer, unevenness of electric resistance and surface roughness, and the like were apt to occur. Furthermore, unevenness in electric resistance due to uneven heating in the drying step of the coating layer, cracking and peeling of the coating, and the like were easily generated.

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

Further, when the intermediate transfer member is repeatedly used, so-called filming, in which toner which cannot be completely removed by the cleaner is deposited on the surface of the intermediate transfer member, may occur. When the filming occurred, it was difficult for the toner to be transferred from the first image carrier to the intermediate transfer member, and a white image was formed in a spot-like manner.

Several materials have been proposed for the intermediate transfer material (for example, see Japanese Unexamined Patent Publication No.
No. 81786, JP-A-4-88385, JP-A-3-242667, JP-A-5-333725, etc.) are still insufficient.

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

[0012]

According to a method of manufacturing an intermediate transfer member of the present invention, a coating layer is formed by coating a coating material for a coating layer on an elastic layer. The solubility index SP1 of the coalescence and the solubility index SP2 of the solvent used for the coating material for the coating layer in the above-mentioned relationship are in a relationship of | SP1−SP2 | ≦ 4.

Further, an image forming apparatus according to the present invention includes an intermediate transfer member manufactured by the above-described 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 roller 20 having a medium resistance 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 carrier, and rotates at a predetermined peripheral speed (process speed) in a clockwise direction indicated by an arrow. 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 exposed to an image exposure means (not shown) for color separation and formation of a color original image. An image exposure optical system, a scanning exposure system using a laser scanner that outputs a laser beam modulated according to a time-series electric digital pixel signal of image information, etc.)
, An electrostatic latent image corresponding to a first color component image (for example, a magenta component image) of a target color image is formed.

Next, the electrostatic latent image is transferred to the first developing device 41.
(Magenta developing device) is developed with magenta toner M as the first color. At this time, the second to fourth developing devices 42,
43, 44 (Cyan, Yellow, Black developing units)
Is turned off and does not act on the photosensitive drum 1,
The first color magenta toner image is not affected by the second to fourth developing units 42 to 44.

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

The first first member formed and supported on the photosensitive drum 1
In the process in which the magenta toner image of the color passes through the nip portion between the photosensitive drum 1 and the intermediate transfer body 20, an outer peripheral surface of the intermediate transfer body 20 is generated by an electric field formed by a primary transfer bias applied to the intermediate transfer body 20. The intermediate transfer is sequentially performed.

After the transfer of the first color magenta toner image onto the intermediate transfer member 20, the surface of the photosensitive drum 1 is cleaned by the cleaning device 14.

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

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

First transfer from the photosensitive drum 1 to the intermediate transfer member 20
The primary transfer bias for the sequential superimposed transfer of the toner images of the fourth to fourth colors has a polarity (+) opposite to that of the toner and a bias power source 6
Applied from 1. The applied voltage is, for example, +2 kV to +
The range is 5 kV.

First transfer from the photosensitive drum 1 to the intermediate transfer member 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 toner images of the fourth to fourth colors.

The transfer of the composite color toner image superimposedly transferred on the intermediate transfer member 20 to the transfer material 24 as the second image carrier is performed while the transfer roller 25 is in contact with the intermediate transfer member 20 and A transfer material 24 such as paper is fed from the paper cassette 9 to a contact nip between the intermediate transfer body 20 and the transfer roller 25 at a predetermined timing, and at the same time, a secondary transfer bias is applied to the transfer roller 25 from a bias power supply 29. . With this secondary transfer bias, the composite color toner image is transferred from the intermediate transfer member 20 to the transfer material 24 as the second image carrier. The transfer material 24 to which the toner image has been transferred is introduced into the fixing device 15 and is fixed by heating.

After the transfer of the image to the transfer material 24, the transfer residual toner on the intermediate transfer member 20 is cleaned by contacting the intermediate transfer member 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 core metal 100 as a support. Alternatively, FIG.
The second coating layer 1 is further provided outside the coating layer 102 as shown in FIG.
03. The coating layer may be 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 coating layer may be laminated on the front and back of the elastic layer with the elastic layer interposed therebetween.

The elastic layer contains a high polymer such as rubber, elastomer or resin. The elastic layer is melt molded,
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, silicon rubber, and fluoro rubber , Nitrile rubber, urethane rubber, acrylic rubber, epichlorohydrin rubber, norbonene rubber and the like. or,
As resins, 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-acrylate copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene- Octyl acrylate copolymer, styrene-phenyl acrylate copolymer, etc.), styrene-methacrylate copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate) Copolymer and styrene-methacrylic acid Cycloalkenyl copolymer), styrene -α
Styrene resins (monopolymers or copolymers containing styrene or styrene substituents) such as methyl chloroacrylate copolymer, styrene-acrylonitrile-acrylate copolymer, vinyl chloride resin, styrene-vinyl acetate copolymer Polymer, rosin-modified maleic resin, phenol resin, epoxy resin, polyester resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin,
Examples thereof include a polyurethane resin, a silicone resin, a ketone resin, an ethylene-ethyl acrylate copolymer, a xylene resin, and a polyvinyl butyral resin.

For the coating layers 102 and 103, for example, a resistance controlling agent, a release agent, a binder resin, a viscosity controlling agent, a coloring agent, and the like are appropriately selected, and these components are dispersed and suspended in a solvent to obtain a coating for the coating layer. Thereafter, 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; ,
Amides such as N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, tetrahydrofuran, dioxane, diethyl ether, ethers such as ethylene glycol monomethyl ether, methyl acetate,
Ester such as ethyl acetate, isobutyl acetate, isopropyl acetate, chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, aliphatic halogenated hydrocarbons such as trichloroethylene benzene, ethylbenzene, toluene, xylene, ligroin, monochlorobenzene, Aromatic hydrocarbons such as dichlorobenzene, aliphatic hydrocarbons such as n-pentane, n-hexane, and n-octane, and water can be used.

In the present invention, the solubility index SP1 of the high molecular 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 having this relationship have a high affinity, and the coating layer is not simply carried on the elastic layer, but the components of the coating layer penetrate to the inside of the elastic layer and the elastic layer and the coating layer form The boundaries are not clear. By forming such a layer configuration, the coating layer has a high film strength and is uniform.

As a result, when a DC bias is applied to the conductive support of the intermediate transfer member, a 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 polymer and the solubility index SP2 of the solvent may be within the range of the above-mentioned equation, and does not depend on the magnitude of SP1 and SP2.

The solubility index (SP value) is a characteristic value serving as a measure of the miscibility. When the molecular aggregation energy is E and the molecular volume is V, the solubility index δ is given by the following equation. δ = (E / V) ^1/2 Solubility Index (SP value) is one of the indexes expressing the intermolecular force of a substance, and it is Journally Apply Poly.
mer Science, 19, 1163 (1975)
According to the literature, it is shown as the sum of the respective forces (energy) of dispersive force, polar effect, and hydrogen bond.

The thickness of the elastic layer is preferably 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, more preferably 2 mm or less, and particularly 20 μm to 1 mm. Preferably, there is.

As the conductive support, for example, metals and alloys such as aluminum, iron, copper and stainless steel, conductive resins in which carbon and metal particles are dispersed, and the like can be used. A belt-shaped thing is preferable.

The volume resistivity of the intermediate transfer member is 10 ¹ to 10 ¹³
Ω · cm, particularly preferably 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 as appropriate within a range that does not hinder the performance. Examples of the conductivity control substance include a conductive particle-dispersed resin and a conductive resin. As the conductive particle dispersed resin,
Examples thereof include particles obtained by dispersing conductive particles such as carbon, aluminum and nickel in a resin such as urethane, polyester, vinyl acetate-vinyl chloride copolymer or polymethyl methacrylate. Examples include quaternary ammonium salt-containing polymethyl methacrylate, polyvinylaniline, polyvinylpyrrole, polydiacetylene, and polyethyleneimine. Among these, a conductive particle-dispersed resin is preferred from the viewpoint of controlling the conductivity. In addition, as the conductivity control substance,
Examples include a conductive metal oxide, a surfactant having antistatic properties, and fine metal 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 carrier used in the image forming apparatus of the present invention, a roller-shaped or belt-shaped photoreceptor can be used, and the roller-shaped one has higher transfer efficiency and image superposition (registration). ) Can be minimized, which is preferable in the present invention. It is presumed that this has a favorable effect because the rigid intermediate transfer member and the rigid photosensitive drum are in contact with each other.

As the photosensitive layer of the photoreceptor, an OPC (containing organic photoconductor) photosensitive layer, in particular, a layer having a fluororesin particle on the outermost layer, reduces friction with the intermediate transfer member. It has advantages such as high durability, improved transfer efficiency, and prevention of partial transfer failure.

[0041]

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

Example 1 182 mm in diameter and 320 in length
A rubber compound having the following composition was transfer-molded on a surface of an aluminum cylindrical roller having a thickness of 5 mm and a thickness of 5 mm using a mold to obtain a roller (A) having an elastic layer having a thickness of 1 mm.

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

Next, in order to obtain a coating layer thereon, a coating material for a coating layer was obtained based on the following composition. At this time, isobutyl acetate and methyl propyl ketone were used as solvents.

Paint 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 for the coating layer was produced as follows.
First, the above-mentioned components containing only 50 parts of a solvent were put together with 200 parts of glass beads in a 500 ml stainless steel container, sealed tightly, and mixed and dispersed with a paint shaker for about 10 hours. Thereafter, a solvent was added to a predetermined amount, and the dispersion was strengthened using a high-pressure liquid collision homogenizer (trade name: Nanomizer) to obtain a coating material for a coating layer.

The roller (A) is mounted on a work rotatable at 50 to 1000 revolutions / minute, and the above coating composition is sprayed onto the surface of the rotating roller (A) with a spray gun (pressure: 0.5 to 5 kg / min). (It can be changed to cm ² ) to form a coating layer having a thickness of 85 μm on the surface of the roller (A). Then, at 80 ° C for 2 hours,
By heating at 00 ° C. for 1 hour, the residual solvent was removed to obtain an intermediate transfer member having a tough coating layer on the surface of the roller (A). SBR which is the high molecular polymer used at this time
The solubility indices of rubber and isobutyl acetate and methyl propyl ketone used as solvents are 8.7 and 8.
3, 8.7.

The intermediate transfer member was mounted on the full-color electrophotographic apparatus shown in FIG.
Using an OPC photosensitive drum having a polycarbonate surface layer in which 0 parts are dispersed, a full-color image copying test was repeatedly performed.

The transfer efficiency from the photosensitive drum as the first image carrier to the intermediate transfer member (hereinafter referred to as primary transfer efficiency) is 9
3%, from the intermediate transfer member to the second image bearing member of 80 g /
The transfer efficiency to paper of cm ² (hereinafter referred to as secondary transfer efficiency) was 90%. The full-color copy image had characters and fine lines without any voids, and the solid image had a uniform image quality. Even after the durability test of 10,000 sheets, the same image quality as in the initial stage was obtained, and the secondary transfer efficiency was 91%, which was hardly reduced. Microscopic observation of the surface of the intermediate transfer member after 10,000 copies did not show any filming with the toner.

Next, a full-length halftone image having an image density of 0.6 to 0.8 was copied to check the uniformity of the image quality. However, the image was excellent without partial density unevenness or white spots. .

Further, the intermediate transfer body using 10,000 sheets was repeatedly rotated only by performing charge and discharge without developing the toner up to 50,000 sheets without idling, and its durability was confirmed. The surface of the intermediate transfer body was conspicuous. No scraping or peeling between the elastic layer and the coating layer occurred.

The image forming conditions of this embodiment will be described below.

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

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

Paint for coating layer 60 parts acrylic-modified polyurethane 20 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. . The belt was subjected to a durability test of 10,000 sheets using the full-color electrophotographic apparatus shown in FIG. As a result, there was no occurrence of filming, the halftone was uniform in terms of image quality, 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 a 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 idle rotation of 50,000 sheets was performed without supplying toner. OP for photosensitive drum
C photosensitive drum having no surface layer containing fluorine resin particles was used.

Thereafter, a graphic image and a halftone image were printed. The graphic image had sharp fine lines and excellent sharpness, and there was no hollow image. or,
The halftone image was a uniform good image without partial image density unevenness or poor white transfer failure.

Comparative Example 1 Highly conductive carbon black 6
Parts of methyl silicone rubber (solubility index: 7.
5) was used as an elastic layer, and a coating material for a coating layer containing the following coating material was applied by dip coating on the elastic layer to obtain an intermediate transfer member.

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

Paint for coating layer 100 parts of alkoxymethyl nylon resin 60 parts of conductive tin oxide 10 parts of colloidal silica 150 parts of ethanol (solubility index 12.7) 150 parts

The halftone image in the initial stage was uniform and had no unevenness in density, but after 10,000 copies, a small white spot-like transfer was considered to be caused by partial electric resistance unevenness over the entire halftone image. Missing had occurred. Further, on the surface of the intermediate transfer member, the toner that could not be completely cleaned was partially fixed to a thin layer, and further, adhesion of the toner presumed to be an early 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 are both high. Paper and O
Regardless of the type of the HP sheet, a uniform image free from image defects such as image dropout can be obtained. Good properties are maintained even after durability. Filming due to toner adhesion to the intermediate transfer member does not occur.

[Brief description of the 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 blank image.

[Explanation of symbols]

 Reference Signs List 1 photosensitive drum 20 intermediate transfer member 100 support member 101 elastic layer 102, 103 coating layer

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Atsushi Tanaka 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Tsunetori Ashibe 3-30-2 Shimomaruko, Ota-ku, Tokyo (56) References JP-A-3-243973 (JP, A) JP-A-3-293385 (JP, A) JP-A-5-46035 (JP, A) JP-A-5-173434 ( JP, A) JP-A-5-32263 (JP, A) JP-A-3-2344092 (JP, A) JP-A-6-95415 (JP, A) JP-A-6-250460 (JP, A) Paint handbook Editorial Committee, Paint Handbook, Japan, Nikkan Kogyo Shimbun, February 25, 1971, 4th edition, page 813 (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/01 114 G03G 15 / 16 G03G 7/00

Claims (6)

(57) [Claims] 1. A method for producing an intermediate transfer member, wherein a coating material for a coating layer is applied to an elastic layer to form a coating layer, wherein the solubility index SP1 of a polymer contained in the elastic layer and the coating layer And the solubility index SP2 of the solvent used in the paint for
A method for producing an intermediate transfer member, wherein a relationship of P1−SP2 | ≦ 4 is satisfied. 2. The method according to claim 1, wherein the coating layer contains a conductivity controlling substance. 3. An image forming apparatus having an intermediate transfer body produced by the method according to claim 1 or 2, and the image bearing member for transferring an image on the intermediate transfer body. 4. The image forming apparatus according to claim 3, wherein the intermediate transfer member and the image carrier are both roller-shaped. 5. The image forming apparatus according to claim 3, wherein the intermediate transfer member has a belt shape, and the image carrier has a roller shape. 6. The electrophotographic photosensitive member according to claim 3 , wherein said image bearing member has an outermost layer containing fluororesin particles.
6. The image forming apparatus according to any one of 5 .