JPH09106196A - Image forming device using intermediate transfer system, and intermediate transfer body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the intermediate transfer body, which is superior in cleaning performance and efficiency of transfer from itself to a transfer material and, specially, free from wormholes, superior in formability in manufacturing and proper in electrostatic friction chargeability to toner, and superior in toner peelability in secondary transfer and well adaptive to a transfer bias applied in transfer and has no wormhole due to abnormally charged toner, for the image forming device which uses the intermediate transfer system such as a transfer drum and a transfer belt. SOLUTION: The image forming device using the intermediate transfer system which transfers plural visible color developed images formed in order on an image carrier 1 with toner primarily, one over another, to the intermediate transfer body 6 traveling endlessly and then transfers the primary transferred image on the intermediate transfer body 6 to a transfer material secondarily uses the intermediate transfer body 6 which is so formed that its surface where the visible color developed images are formed consists of a mixture compound of fluororesin and resin A compatible with it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile, and particularly to a primary and secondary transfer step with an intermediate transfer member such as an intermediate transfer belt interposed. The present invention relates to an image forming apparatus using an accompanying intermediate transfer system.

[0002]

2. Description of the Related Art The transfer system of a full-color image forming apparatus is
(A) transfer drum system (transferring sequentially to a transfer material fixed on the transfer drum), and (b) intermediate transfer body double transfer system (intermediate transfer body, for example, toner images sequentially transferred onto a transfer belt. However, the method of (b) is advantageous in that it is paper-free and can copy the entire surface. Regarding the method (b) using a transfer drum and a belt-shaped intermediate transfer member, there is a troublesome problem of an abnormal image, so-called "insect-eaten print" (hereinafter, insect-eaten print). The insect worm is what is seen on the image as a state where the toner to be originally transferred is not pinpointly transferred and remains, and the toner is partly removed.

Generally, as an intermediate transfer material, a material such as a fluororesin having excellent releasability from a toner is used, but insect worms do not always disappear. As a typical conventional technique for improving insect biting, Japanese Patent Laid-Open No. 58-18796 is available.
Japanese Patent Application Laid-Open No. 2-19847, which supplies an organic fluorine compound to the surface of an intermediate transfer member, as described in JP-A-8-19847.
No. 6, in which a wettability control agent is added to the intermediate transfer material, and as described in JP-A-2-213881, lubricity of zinc stearate or the like on the surface of the intermediate transfer member. To form a protective film having the above-mentioned properties, as described in JP-A-3-242667, a silicone rubber used as an intermediate transfer material to control the surface roughness thereof, and described in JP-A-4-305666. As described above, the contact member of the intermediate transfer member is provided with a peripheral speed difference, and the surface of the intermediate transfer member is polished.
No. 4, which polishes the surface of the intermediate transfer member when toner filming occurs on the surface,
A method of polishing after detecting the surface roughness of an intermediate transfer member, as described in JP-A-5-313526.
As described in Japanese Patent No. 323802, the intermediate transfer member may be polished every fixed number of copies.

However, with these conventional techniques, it is difficult to maintain stable image quality over a long period of time. Further, when applying zinc stearate or the like or polishing the surface, a device such as a coating device, a polishing device, and a timing control device for the same is required, which complicates the device and increases the cost. Therefore, it has been proposed to use a fluorine-based resin having good surface releasability as the intermediate transfer material. (JP-A-7-92825)

However, although the above-mentioned fluorine-based resin is excellent in releasability, it has a great negative charge polarity, and thus has a great influence on the charge amount of the toner. Specifically, when the toner is negatively charged, a toner image is formed on the intermediate transfer member, and the charge polarity of the toner is reversed from negative to positive during the process of transferring onto the paper. This reverse polarity toner cannot be transferred to paper, which causes a problem of insect biting.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned prior art, and more specifically, in an image forming apparatus using an intermediate transfer system such as a transfer drum and a transfer belt, the intermediate transfer is performed. An object of the present invention is to provide a device which is excellent in body cleaning property and transfer efficiency from an intermediate transfer member to a transfer material and which does not particularly cause insect biting. Further, the object of the present invention is that the moldability during manufacturing is good, the triboelectric charging property against toner is appropriate, the releasability from the toner during secondary transfer is excellent, and the transfer bias applied during transfer is improved. The object of the present invention is to provide an intermediate transfer member which has good compatibility and does not cause insect biting due to abnormally charged toner.

[0007]

As a result of intensive studies on this point, we have improved the problems in the prior art by making at least the surface of the intermediate transfer member as follows. I found that I could achieve my purpose. That is, the above object of the present invention is: (1) "Primary transfer of a plurality of visible color developed images sequentially formed by toner on an intermediate transfer member, which is run endlessly, in succession. In an image forming apparatus using an intermediate transfer system in which a primary transfer image on the intermediate transfer member is secondarily transferred onto a transfer material all at once, at least a surface of the intermediate transfer member on which a visible color developed image is formed is fluorine. And an image forming apparatus using an intermediate transfer member composed of a mixture composition B of a resin A and a resin A that is compatible therewith.
(2) "Intermediate transfer member in which at least the surface of the intermediate transfer member on which a visible color developed image is formed is composed of a mixture composition B of a fluororesin and a resin A which is compatible with it", (3)
“The fluororesin is polyvinylidene fluoride and / or
Or vinylidene fluoride, tetrafluoroethylene,
Intermediate transfer member according to (2) above, which is a fluorine-based copolymer or terpolymer containing at least two or more compositions of hexafluoropropylene ", (4)" surface friction of the intermediate transfer member " (2) The coefficient is 0.4 or less
Intermediate transfer member of (5) “the volume resistance of the intermediate transfer member is
10 ⁸ to 10 ¹³ Ω · cm (2) Intermediate transfer member ”, (6)“ The intermediate transfer member has a laminated structure of two or more layers, and the surface resistance is 10 ⁹ to 10 ¹⁴ Ω / □. (2) the intermediate transfer member ", (7)" the intermediate transfer member (2) in which the absolute value of the triboelectric charge amount between the intermediate transfer member and the toner used is 0 to 40 [mu] c / g ", (8) "The intermediate transfer member of the above (2) in which the resin A is an acrylic resin or a polyether resin", (9) "The mixing ratio of the fluorine-based copolymer and the resin A is 8/2 to The intermediate transfer member of (5) above, which is 5/5 "
And (10) “The volume resistivity of the resin A is 10 ⁸ to 10
It is achieved by the intermediate transfer member of the above (2) which is ¹² Ω · cm.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An example of an image forming apparatus of the present invention using an intermediate transfer system will be specifically described below with reference to the drawings. FIG. 1 schematically shows a full-color electrophotographic apparatus as an example of the present invention using an intermediate transfer system. In FIG. 1, the latent image formed on the photoconductor (13) is first visualized in the developing unit (4) for the first color, and then in the contact portion with the intermediate transfer member (6). It is transferred to the intermediate transfer member. The transfer here is "primary transfer". For full color,
This process is repeated for three or four colors to form a full-color image on the intermediate transfer member. The image formed on the intermediate transfer member is
Next, in the area (11), it is collectively transferred onto the transfer material (paper). The transfer here is called "secondary transfer". The transfer material is
After that, a fixing process (not shown) is performed and a full-color image is output.

In the secondary transfer step of the above process, the formed image is transferred from the intermediate transfer member to the transfer material, but the transfer efficiency here is generally in order to obtain a sufficient image density. 90% or more is required. Further, even if 90% or more of the toner is transferred, the toner may remain on the intermediate transfer member without being pinpointly transferred. This is an abnormal image called a bug-eaten print.

In order to prevent this, as disclosed in the above-mentioned JP-A-2-213881, some of the prior arts have a mechanism (sweeper) for applying zinc stearate or the like to the surface of the intermediate transfer member. A brush 8) is provided. However, as mentioned above, this method is not a sufficient solution. As a result of intensive studies on this point, we have found that the problems in the prior art can be improved and the above-mentioned object can be achieved by forming at least the surface of the intermediate transfer member as follows, and arrived at the present invention. It is a thing.

Although the image forming apparatus including the belt-shaped intermediate transfer member has been described in the example of the embodiment of the present invention, the present invention is not limited to this and can be applied to a transfer drum. Examples of the fluorine-based resin used in the present invention include polyvinylidene fluoride (PVdF) and polytetrafluoroethylene (PTF).
E), tetrafluoroethylene-ethylene copolymer (E
TFE), polychlorotrifluoroethylene (PCTF
E), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV) and the like.

[0012] Of these, PVd
F and THV are particularly preferable. Further, in order to satisfactorily carry out the image forming process of the present invention using the intermediate transfer member, the friction coefficient is preferably 0.4 or less. If the coefficient of friction exceeds 0.4, the releasability is lowered and insect worming is likely to occur. In addition, the frictional load with the cleaning blade becomes large, resulting in defective cleaning. In order to make the friction coefficient within this range, in the present invention, a means of using a material having such characteristics or adjusting with an additive or the like is used.

Examples of the additives include silicon-based / fluorine-based low molecular weight additives represented by silicone oil and fluorine-based surfactants, silicon-based / fluorine-based resin particles, mica / graphite / nitride. Inorganic solid lubricants such as molybdenum sulfide, natural waxes such as montan wax, carnauba wax, hydrogenated castor oil, synthetic waxes such as fatty acid, fatty acid ester, fatty acid triglyceride, fatty alcohol, fatty acid monoamide, fatty acid bisamide, polyethylene wax, etc. Typical waxes such as polyolefin waxes such as polypropylene wax are listed.

Further, the intermediate transfer member in the present invention is 1
It preferably has a volume resistance value of 0 ⁸ to 10 ¹³ Ωcm. If the resistance value is less than this value, discharge of the transfer bias occurs between the contact members with the intermediate transfer member such as the photoconductor and the image is disturbed. Further, if it is more than this, the transfer cannot be performed unless the transfer bias is set to an abnormally high voltage. In addition, since electric charges remain and accumulate in the intermediate transfer member, an afterimage is generated. Therefore, it is necessary to adjust the resin material forming the intermediate transfer member to a desired resistance value with an inorganic or organic conductive material.

As the inorganic conductive material, conventionally known materials can be used, and examples thereof include carbon black, graphite, carbon fiber, metal powder, metal oxide powder, and conductive whiskers. Further, as the organic conductive material, polyethylene oxide, polypyrrole,
What is represented by a graded ammonium salt etc. can be used. The addition amount of these is adjusted so as to have the above resistance value. Further, these may be used in combination of not only one kind but also two or more kinds.

Further, the structure of the intermediate transfer member is not limited to a single layer, but may have a multi-layered structure if necessary. in this case,
The surface resistance value of the outermost surface layer is preferably 10 ⁹ to 10 ¹⁴ Ω / □. If the surface resistance value is less than this value, the image is disturbed as in the case of the volume resistance value, and if the surface resistance value is more than this value, an afterimage similarly occurs, which is not preferable.

At least the surface of the intermediate transfer member in the present invention is composed of polyvinylidene fluoride and / or a fluorine-based copolymer. The fluorine-based copolymer is composed of at least two kinds of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene, and the composition ratio thereof is appropriate depending on molding conditions and the like. The reason why the resin A is mixed with the fluorocopolymer in the present invention is as follows. That is, since only the fluorine-based copolymer has a strong negative polarity, for example, when a negatively charged toner is used, the toner is charged to the opposite polarity, and insect worming occurs. Therefore, by mixing the resin A, the mixed composition B
Adjust the triboelectric chargeability of.

For this mixed composition B, the materials and mixing amount are selected and adjusted so that the absolute value of the triboelectric charge amount of the toner used is 0 to 40 μc / g. The charge amount of the intermediate transfer member and the toner is a value measured by the following procedure.

FIG. 2 shows an apparatus for measuring this characteristic value. In FIG. 2, two metallic rollers (22) and (23) whose surfaces are covered with an intermediate transfer material (21) and which have different linear velocities and different rotation directions are adjacent to each other, and a predetermined amount of contact is made in the contact area. The toner is added and the rollers (22) and (23) are rotated to suck the toner using a suction jig, and the charge amount of the toner is measured by an electrometer. In addition, the weight of the suction toner at this time is measured to calculate the charge amount per unit weight. The specifications of the device are as follows. Metal roller diameter: ψ100 mm Linear velocity: Roller (22) to 100 mm / sec Roller (23) to 105 mm / sec Gap: 20 μm Rotation time: 30 sec

The resin A to be mixed is preferably, for example, an acrylic resin or a polyether resin in consideration of the triboelectric charging property. As the acrylic resin, acrylic acid ester polymer, methacrylic acid ester polymer and its copolymer resin, polymethyl methacrylate, 2-hydroxyethyl methacrylate, butyl methacrylate,
Examples thereof include 2-ethylhexyl methacrylate, allyl methacrylate, glycidyl methacrylate, copolymers thereof, modified resins using these, acrylic rubber and the like. As the polyether resin, polyethylene oxide, polypropylene oxide, polyether amide, polyether ester amide, chlorinated polyether, polyacetal, epichlorohydrin rubber,
Examples include polyether urethane rubber and the like.

The mixing ratio of the resin A and the fluororesin F is preferably F / A = 8/2 to 5/5. If the mixing ratio is out of this range and the amount of A is small, the triboelectrification property is not improved and the insects are eaten by the abnormally charged toner. Next, if the amount of A is too large, the friction coefficient becomes excessively large, or the releasability is deteriorated and insect worming occurs, which is not preferable.

Further, this resin A has a volume resistivity of 1
It is more preferable to use a material having a resistivity of 0 ⁸ to 10 ¹² Ω · cm. When such a material is used, it is not necessary to add another material for adjusting resistance, or good results can be obtained with a small amount of addition. Hereinafter, the present invention will be described more specifically and in detail with reference to Examples.

[0023]

【Example】

(Example 1) Vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer resin (THV500; Sumitomo 3M) 100 parts by weight Conductive whiskers (Dentol WK200B; Otsuka Chemical) 65 parts by weight Acrylic resin (PMMA; Wako Pure Chemical Industries, Ltd.) 43 parts by weight The mixture was extruded to obtain a seamless belt-shaped intermediate transfer member. (Example 2) Instead of the vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer resin of Example 1, polyvinylidene fluoride (KF85).
0; Kureha) was performed in the same manner as in Example 1 to obtain a seamless belt-shaped intermediate transfer member. (Example 3) In place of the vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer resin of Example 1, a tetrafluoroethylene-hexafluoropropylene copolymer (Neoflon FEP; Daikin Industries) was used. In the same manner as in 1, a seamless belt-shaped intermediate transfer member was obtained. (Example 4) A seamless belt-shaped intermediate transfer member was obtained in the same manner as in Example 1 except that 30 parts by weight of acrylic rubber (PA401; NOK) was used instead of the acrylic resin of Example 1. (Examples 5 to 8) The conductive whiskers in Example 1 were added in the same amount except that the addition amount was 50, 60, 70, and 80 parts by weight. (Example 9) Vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer resin (THV500; Sumitomo 3M) 100 parts by weight Conductive whiskers (Dentor WK200B; Otsuka Kagaku) 65 parts by weight The above mixture is extruded and seamless. A substrate of a belt-shaped intermediate transfer member was obtained. The following surface layer forming material was spray coated on the above substrate and dried at 150 ° C./10 minutes to obtain an intermediate transfer member. {Surface layer-forming component} Vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer resin / acrylic resin mixed paint (Novafusso PF250; Dainippon Color Materials Industry) 100 parts by weight (solid content) Conductive whiskers (Dentol WK200B) 25 Parts by Weight (Example 10) A seamless belt-shaped intermediate transfer member was obtained in the same manner as in Example 9 except that the following wetting agent was added to the surface layer forming component in Example 9. L-uraloyl-N-lysine (Famex L-12; Ajinomoto) 5 parts by weight (Examples 11 to 13) The conductive whiskers of the surface layer forming component in Example 10 were changed to 10, 20, and 30 parts by weight. In the same manner as in Example 10, a seamless belt-shaped intermediate transfer member was obtained. (Examples 14 to 17) The ratio of the fluororesin F to the acrylic resin A of Example 1 was F / A = 9/1, 8/2, 5/5, 4
A seamless belt-shaped intermediate transfer member was obtained by the same steps as in Example 1 except that the number was set to / 6. (Example 18) Vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer resin (THV500; Sumitomo 3M) 100 parts by weight Conductive whiskers (Dentol WK200B; Otsuka Chemical) 30 parts by weight Polyether ester amide (Pebax 6333; Toray) 30 parts by weight The above mixture was extruded to obtain a seamless belt-shaped intermediate transfer member. (Example 19) A seamless belt-shaped intermediate transfer member was obtained by the same steps as in Example 9 except that the following components were added to the surface layer forming components of Example 9. Aminosilane (KBM603; Shin-Etsu Chemical Co., Ltd.) 8 parts by weight (Example 20) A seamless belt-shaped intermediate transfer member was obtained in the same manner as in Example 19 except that the amount of aminosilane in Example 19 was 12 parts by weight. Comparative Example 1 A seamless belt-shaped intermediate transfer member of Comparative Example was obtained in the same manner as in Example 1 except that the acrylic resin was not used. Comparative Example 2 A seamless belt-shaped intermediate transfer member of Comparative Example was obtained in the same manner as in Example 2 except that the acrylic resin was not used.

The volume resistance and surface resistance of the intermediate transfer members of the above Examples and Comparative Examples were measured by Hiresta (manufactured by Mitsubishi Chemical). In addition, the friction coefficient is measured by the friction coefficient measuring device (Friction Abr
asion Analyzer DF.PM-SS; Kyowa Interface Chemistry). The triboelectrification with the toner was measured using the apparatus shown in FIG. 2 under the conditions described above.

Further, the above-mentioned intermediate transfer member was mounted on a Ricoh full-color copying machine (Pretail 550), and the image was observed and insect bite image evaluation (5 step evaluation, allowable level rank 3).
Above). Also, other abnormal images were checked. The sweeper brush 8 was not installed here. The insect-eating rank evaluation was performed based on the following. Rank 5: No insect eating occurs. Rank 4: There are a few small insect eaters that are hard to see with the naked eye. Rank 3: Many small insect bites that are hard to see with the naked eye are seen. Rank 2: Insect eaters of a size that can be clearly seen with the naked eye are seen. Rank 1: Many insect bites of a size that can be clearly seen with the naked eye are seen. A silicon resin coated carrier was used as the carrier, and the following negatively chargeable cyan toner was used as the toner. Epoxy resin 100 parts by weight Copper phthalocyanine 1.5 parts by weight Zinc salicylate derivative 1.5 parts by weight The above mixture melt-kneaded is ground and classified to about 7 μm.
With 100 parts by weight of this fine powder, 0.7 part by weight of hydrophobic silica was mixed with a mixer to obtain a toner. The results are shown in Tables 1 and 2 below.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

As is apparent from the concrete and detailed description including the above-mentioned embodiments, examples and Tables 1 and 2, according to the present invention, the moldability is good at the time of manufacture. , The frictional electrification property to the toner is proper, and during the secondary transfer,
Provided is an intermediate transfer member which is excellent in releasability from a toner, has good compatibility with a transfer bias applied at the time of transfer, and does not cause insect bites due to abnormally charged toner. The image forming apparatus of the present invention equipped with a transfer member has excellent cleaning properties and transfer efficiency to a transfer material, and a good image free from insects, such as a full-color image, can be obtained by this device. It has an excellent effect.

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[Procedure amendment]

[Submission date] February 2, 1996

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Added

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of an image forming apparatus using an intermediate transfer method of the present invention.

FIG. 2 is a diagram illustrating an apparatus for measuring a toner charging characteristic value by the intermediate transfer member of the present invention.

[Explanation of Codes] 4 Developing Section 6 Intermediate Transfer Belt 11 Area 13 Photoreceptor 21 Intermediate Transfer Material 22 SUS Roller 23 SUS Roller

Claims (10)

[Claims] 1. A plurality of visible color-developed images sequentially formed by toner on an image carrier are sequentially superimposed and primary-transferred onto an endlessly traveling intermediate transfer member, and the primary transfer on the intermediate transfer member is performed. In an image forming apparatus using an intermediate transfer method in which a transfer image is secondarily transferred onto a transfer material at a time, at least the surface of the intermediate transfer member on which a visible color development image is formed is compatible with a fluororesin. An image forming apparatus using an intermediate transfer member composed of a mixture composition B with a different resin A. 2. An intermediate transfer member, wherein at least the surface of the intermediate transfer member on which a visible color developed image is formed is composed of a mixture composition B of a fluororesin and a resin A compatible with it. 3. A fluorine-based copolymer or ternary copolymer having a composition of at least two or more of polyvinylidene fluoride and / or vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene. The intermediate transfer member according to claim 2, which is a united body. 4. The intermediate transfer member according to claim 2, wherein the surface friction coefficient of the intermediate transfer member is 0.4 or less. 5. The volume resistance of the intermediate transfer member is 10 ⁸ to 1
The intermediate transfer member according to claim 2, which has a resistance value of 0 ¹³ Ω · cm. 6. The intermediate transfer member according to claim 2, which has a laminated structure of two or more layers and has a surface resistance of 10 ⁹ to 10 ¹⁴ Ω / □. 7. The intermediate transfer member according to claim 2, wherein the absolute value of the triboelectric charge amount between the intermediate transfer member and the toner used is 0 to 40 μc / g. 8. The intermediate transfer member according to claim 2, wherein the resin A is an acrylic resin or a polyether resin. 9. The intermediate transfer member according to claim 2, wherein the mixing ratio of the fluorine-based copolymer and the resin A is 8/2 to 5/5. 10. The resin A has a volume resistivity of 10 ⁸ to 1
The intermediate transfer member according to claim 2, which has a resistivity of 0 ¹² Ω · cm.