JP3273400B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrophotographic system, and more particularly, to a method in which a toner image formed on a first image carrier is temporarily transferred onto an intermediate transfer member and then transferred to a second image carrier.
And an image forming apparatus such as a copying machine, a printer, a facsimile, etc., for obtaining an image formed product by further transferring the image on an image carrier.

[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.

FIG. 1 schematically shows an example of an image forming apparatus which is a transfer apparatus using an intermediate transfer body having a roller shape.

FIG. 1 shows a color image forming apparatus (copier or laser beam printer) using an electrophotographic process. Medium resistance elastic roller 2 as intermediate transfer member
0 is used.

Reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member (hereinafter, referred to as a photosensitive drum) which is used repeatedly 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 / combination of a color original image. An image exposure optical system, a scanning exposure system using a laser scanner that outputs a laser beam modulated in accordance with a time-series electric digital pixel signal of image information, etc.) to receive a first image of a target color image. An electrostatic latent image corresponding to a color component image (for example, a magenta component 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 4
2, 43, and 44 (developing units for cyan, yellow, and black) are turned off and do not act on the photosensitive drum 1, and the magenta toner image of the first color is used for the second to fourth magenta toner images.
Of the 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 is made of a pipe-shaped metal core 21.
And an elastic layer 22 formed on the outer peripheral surface thereof.

[0010] The first type 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 and in contact with the lower surface thereof.

The first transfer from the photosensitive drum 1 to the intermediate transfer body 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 superimposed and 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 The transfer material 24 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 the 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 image transfer to the transfer material 24 is completed, the transfer residual toner on the intermediate transfer member 20 is cleaned by contacting the intermediate transfer member cleaner 35.

A color electrophotographic apparatus having an image forming apparatus using the above-mentioned intermediate transfer member is a conventional technique, in which a second image carrier is stuck or adsorbed on a transfer drum, and the first image carrier is stuck thereon. A color electrophotographic apparatus having an image forming apparatus for transferring an image from a carrier, for example,
It is superior to the transfer method as described in JP-A-3-301960 in the following points. That is, there is little color shift at the time of superimposing the toner images of each color. Next, as shown in FIG. 1, the image from the intermediate transfer body is not required for the second image carrier without any processing or control (for example, gripping by a gripper, adsorbing, giving a curvature, etc.). Can be transferred, so that the second image carrier can be variously selected. For example, thin paper (40 g / m
^It is possible to select from thick paper (200 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.

Further, since the rigidity of the intermediate transfer member is excellent, it is difficult for the 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 the image forming apparatus have already started operating in the market.

However, these color electrophotographic apparatuses are:
At present, the device does not function sufficiently as a device that makes full use of the above-mentioned advantages and that is truly expected and satisfactory to users. That is, when the image forming apparatus using the intermediate transfer member is repeatedly used in various environments, the following problems still remain.

(1) The transfer efficiency from a first image carrier, for example, a photosensitive drum to an intermediate transfer member, and the transfer efficiency from the intermediate transfer member to a second image carrier, for example, paper or an OHP sheet, are sufficiently high. It has not become something. Therefore, a cleaning device to be provided in the photosensitive drum and the intermediate transfer member is indispensable, and a load on the device is increased to clean a large amount of transfer residual toner, and the cleaning device becomes considerably complicated in structure and expensive. It has become something.

(2) An image transferred to the intermediate transfer member and a part of the image transferred to the second image carrier are not transferred as shown in FIG. May be. This is caused by the fact that the transfer efficiency has not reached 100% as described in (1). As the cause, the material used for the intermediate transfer member, the surface properties, the resistance, or the magnitude and timing of the applied bias at the time of transfer, or the mechanical configuration of the image forming apparatus are considered to act in combination, The main cause is unknown. However, it is known that it deteriorates as the durability of the intermediate transfer member advances or as the environment becomes lower in temperature and humidity.

(3) The surface properties and resistance of the intermediate transfer member may change as the intermediate transfer member is repeatedly used and the durability is advanced. In extreme cases, abrasion occurs on the surface of the intermediate transfer member, and it becomes impossible to maintain good transfer efficiency and a uniform image obtained at the beginning.

(4) As shown in FIG. 1, the intermediate transfer member 20 is provided with an intermediate transfer member cleaner 35. This is an apparatus for removing untransferred toner from the intermediate transfer member before the next series of transfer steps starts. There are various cleaning methods such as blade cleaning, fur brush cleaning, or a combination thereof, but toner is transferred to the surface of the intermediate transfer member 20.
When the cycle of demolding is repeated thousands or tens of thousands of times,
The toner that has not been completely removed by the cleaner 35 gradually accumulates on the surface of the intermediate transfer body 20, so that so-called filming is formed. When this happens, the first
In this case, the transferability of the toner from the image carrier is deteriorated, resulting in an image having a spot-like white spot due to poor transfer of the filmed portion, resulting in lower image quality or lowering the overall transfer efficiency.

(5) To express the function of the intermediate transfer member,
In many cases, the elastic layer is made of rubber, elastomer, resin, or the like, and a coating layer or the like is used as an upper layer as necessary. For example, JP-A-4-81786, JP-A-4-88385, JP-A-3-242667, and JP-A-5-333725 have already disclosed some preferable materials and compositions.
From low-temperature and low-humidity environments to high-temperature and high-humidity environments, resistance has been found to be widely stable and usable.

[0027]

SUMMARY OF THE INVENTION However, the present invention proposes an image forming apparatus using an intermediate transfer member which solves the above-mentioned problem.

Accordingly, an object of the present invention is to provide an image forming apparatus having extremely high transfer efficiency from the first image bearing member to the intermediate transfer member and very high transfer efficiency from the intermediate transfer member to the second image bearing member. Is what you do.

Another object is that the uniform and uniform image quality without transfer failure of a minute portion of an image, that is, without a so-called hollow image, depends on the type of paper or OHP sheet as the second image carrier. An object of the present invention is to provide an image forming apparatus which can be obtained without using the above.

Another object of the present invention is to provide an image forming apparatus capable of maintaining the same characteristics as those in the initial stage without any change even under severe durability such as repeated use of an intermediate transfer member.

Another object of the present invention is to provide an image forming apparatus which does not cause filming due to toner adhesion to the surface of the intermediate transfer member.

[0032]

That is, the present invention provides an image forming method in which an image formed on a first image carrier is transferred onto an intermediate transfer member and then further transferred onto a second image carrier. In the apparatus, the intermediate transfer member may include an elastic layer and an upper layer.
Having a coating layer formed by coating , the coating layer contains polyurethane, and the resistance control agent is 1.0 to
200% by weight, the polyurethane comprises a polymer of an isocyanate compound and a polyol compound, and the molar ratio of isocyanate groups to hydroxyl groups in the polymer raw material is 0.8 %.
≦ NCO group / OH group ≦ 1.3 .

Hereinafter, the present invention will be described in detail.

When the polyurethane of the present invention forms a coating layer on the intermediate transfer member, it is relatively smooth without depending on the coating method, for example, spray coating, dip coating, roll coater coating and the like. And a smooth surface can be formed.

When the value of NCO group / OH group is also within the range of the present invention, the polyurethane-coated surface obtained after polymerization has appropriate hardness and abrasion resistance.

Because of these features, the toner adhering to the surface of the coating can be easily removed, and its characteristics hardly deteriorate even after repeated use due to durability. Also, the cleaner 35 provided in the intermediate transfer member can be of a relatively simple configuration.

As a compound for obtaining the polyurethane of the present invention, a polymer can be obtained by appropriately combining an isocyanate compound and a polyester polyol compound or a polyether polyol compound as a polyol compound as appropriate. It is a polymer obtained from an isocyanate compound and a polyester polyol compound.

In the present invention, when the polyester polyol compound is used, the mechanical strength and the mechanical strength of the obtained polyurethane are higher than when the polyether polyol compound is used.
For example, it has high tensile strength and elongation, and when used as a coating layer, has excellent adhesion and durability to a lower elastic layer. However, when a desired resistance is controlled by adding and mixing a conductive agent at the stage of obtaining a polymer, the environmental stability of electric resistance is slightly better when a polyether polyol compound is used.

When the molar ratio of NCO group / OH group is lower than 0.5, the solvent resistance and hardness of the coating layer are reduced, and the surface is liable to be scraped and the transfer efficiency is likely to be reduced as the coating layer is durable.
In addition, the releasability of the toner is reduced, and filming is liable to occur. If the molar ratio of NCO groups / OH groups is higher than 1.5, the adhesion between the polyurethane coating layer and the lower elastic layer is reduced.

In the present invention , preferred NCO groups / O
Range of molar ratio of H group , 0.8 ≦ NCO group / OH group ≦ 1.
It needs to be 3.

As the polyester polyol compound among the polyol compounds for obtaining the polyurethane of the present invention, a condensation polyester polyol compound is mainly used, and examples thereof include ethylene adipate having 50 to 150 hydroxyl groups, diethylene adipate, and butylene adipate. In addition, there are lactone-based polyester polyol compounds and polycarbonate diol compounds.

Examples of the polyether polyol compound include poly (oxypropylene) glycol, poly (oxypropylene) poly (oxyethylene) glycol,
Poly (oxyalkylene) such as poly (oxybutylene) glycol and poly (oxytetramethylene) glycol
Glycols, poly (oxypropylene) triol,
Poly (oxypropylene) polyols with poly (oxyalkylene) triols such as poly (oxypropylene) poly (oxyethylene) triol, poly (oxybutylene) triol, ethylenediamine, pentaerythritol, sorbitol, sucrose, starch, etc. as initiators (Oxyalkylene) such as poly (oxypropylene) poly (oxyethylene) polyol
Polyols and the like.

As the isocyanate compound, tolylene diisocyanate, meta-xylylene diisocyanate,
Aromatic isocyanate compounds such as diphenylmethane diisocyanate and polymethylene polyphenylisocyanate; hydrogenated products of the above isocyanates; aliphatic isocyanate compounds such as hexamethylene diisocyanate; Examples include amines, tertiary alcohols, amides, lactams, heterocyclic compounds, blocked isocyanate compounds blocked with sulfites, and the like.

Examples of catalysts for promoting the formation of polymers include naphthenates such as magnesium naphthenate and cobalt naphthenate; tin compounds such as dibutyltin dilaurate, dimethyltin dilaurate and stannous chloride; triethylenediamine; Morpholine, N, N,
An amine compound such as N ', N'-tetramethylpolymethylenediamine may be added. The addition amount of the catalyst is 0.05 to 5% by weight based on the polymer.

As a method for obtaining the polyurethane coating layer of the present invention, a polymer of a polyol compound and an isocyanate compound may be dissolved in an appropriate solvent and coated and dried. Or a prepolymer of a polyol compound and an isocyanate compound, which has been partially reacted with a polyol compound and an isocyanate compound, may be diluted with an appropriate solvent, followed by coating and reaction-curing to form.

As the coating method, a spray coating method,
A dip coating method, a roll coater coating method, or the like can be used.

In order to control the electric resistance of the polyurethane coating layer of the present invention, it is necessary to add an electron conductor or an ionic conductor as a resistance control agent.

Examples of preferred electron conductors include conductive metal oxides, graphite, and metals (copper, aluminum,
Nickel and silver) and conductive polymers (polyaniline,
Polypyrrole, polythiophene, polyacetylene, polypyridine, polyacene, polyazulene, polydiphenylbenzidine, polyvinylcarbazole, poly-3-alkylthiophene, and the like. Of these, metals, polyaniline, polypyrrole and polythiophene are particularly preferred. Examples of preferred ionic conductors include metal salts and ammonium salts. Examples of the metal salt include salts of metals of Group I or Group II, and among them, salts of Li, Na and K having a relatively small cation radius are particularly preferable. Examples of the anions constituting these metal salts include halogen ions (F, Cl, Br and I, etc.), thiocyanate ions, perchlorate ions, trifluoromethanesulfonate ions, and fluoroborate ions.
Of these, particularly preferred are thiocyanate, perchlorate, trifluoromethanesulfonate and fluoroborate. As the ammonium salt, carboxylic acids (adipic acid, phthalic acid,
Ammonium salts of acids such as azelaic acid), phosphoric acid, boric acid, sulfonic acids (such as arylsulfonic acids) and borofluoric acid. Among these ammonium salts, ammonium carboxylate, ammonium phosphate and ammonium borate are particularly preferred. The electron conductor and the ionic conductor may be used as a mixture.

When these resistance control agents are used as a coating layer and are added to a coating, it is necessary to add 1.0% by weight to 200% by weight based on the resin solid content in the coating.
There is . If the amount is less than 1.0% by weight, the electric resistance cannot be controlled stably, and a surface having a uniform resistance cannot be formed. If it exceeds 200% by weight, it is difficult to form a tough continuous film. In extreme cases, a stable film cannot be formed, and a film in which independent particles are weakly bonded to each other results.

The intermediate transfer member used in the present invention has a roller shape having at least an elastic layer made of rubber, elastomer, or resin on a rigid cylindrical conductive support.
Further, various shapes such as a roller shape having one or more coating layers on the elastic layer or a belt shape as shown in FIG. 5 can be selected as needed for various purposes. The example is shown in FIGS.

Considering the prevention of color misregistration in image superposition and the durability due to repeated use, a more preferred embodiment of the present invention is a roller shape.

In each of the figures, reference numeral 100 denotes a rigid cylindrical conductive support, 101 denotes an elastic layer, 102 and 103 denote coating layers, and 104 denotes an intermediate transfer belt.

As the cylindrical conductive support, a metal or alloy such as aluminum, iron, copper and stainless steel, a conductive resin in which carbon, metal particles and the like are dispersed, or the like can be used. Such a cylinder, a cylinder having a shaft penetrating the center of the cylinder, a cylinder having a reinforced interior, and the like can be given.

The rubber, elastomer and resin used for the elastic layer and the coating layer of the intermediate transfer member used in the present invention include:
For example, as elastomers and rubbers, styrene-butadiene rubber, high styrene rubber, butadiene rubber, isoprene rubber, ethylene-propylene copolymer, nitrile butadiene rubber, chloroprene rubber, butyl rubber, silicon rubber, fluorine rubber, nitrile rubber, urethane rubber ,
Acrylic rubber, epichlorohydrin rubber, norbornene rubber and the like can be mentioned. 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-acrylic acid Ester copolymers (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, styrene-phenyl methacrylate copolymer, etc.), styrene-α-methyl methyl acrylate copolymer, styrene-acrylonitrile-acrylate copolymer, etc. Styrene resin (homopolymer or copolymer containing styrene or styrene substituent), vinyl chloride resin, styrene-vinyl acetate copolymer, rosin-modified maleic resin, phenol resin, epoxy resin, polyester resin, low molecular weight Examples include polyethylene, low molecular weight polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, and polyvinyl butyral resin.

The thickness of the elastic layer is 0.5 mm or more,
mm or more, particularly preferably 1 mm 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 upper layer or to the surface of the photoreceptor, specifically 3 mm or less, more preferably 2 mm or less, and particularly 5 μm. It is preferably about 1 mm.

The volume resistivity of the intermediate transfer member used in the present invention is preferably from 10 ¹ to 10 ¹³ Ω · cm, and particularly preferably from 10 ² to 10 ¹⁰ Ω · cm. The volume resistivity of at least the surface layer is preferably within these ranges.

The intermediate transfer member of the present invention is manufactured, for example, as follows.

First, a metal roll as a cylindrical conductive support is prepared. An elastic layer is provided by molding rubber, elastomer resin, or the like on a metal roll by melt molding, injection molding, dip coating, spray coating, or the like.

Next, as described above, the coating layer is provided by forming the material of the coating layer on the elastic layer by melt molding, injection molding, dip coating or spray coating.

[0060]

The present invention will be described below in detail with reference to examples. (Examples 1 and 2 , Comparative Examples 1 to 3 ) An elastic layer was formed by transfer molding a rubber compound having the following composition on a surface of an aluminum cylindrical roller having a diameter of 182 mm, a length of 320 mm, and a thickness of 5 mm using a mold. The obtained roller (1) was obtained. Rubber compounding NBR rubber 100 parts (parts by weight, the same applies hereinafter) Zinc oxide 2 parts Conductive carbon black 10 parts Paraffinic oil 30 parts Vulcanizing agent (sulfur) 2 parts Vulcanization accelerator (dibenzothiazyl disulfide, MBTS) 3 parts Next, in order to obtain a coating layer as an upper layer, a coating material for a coating layer was prepared based on the following formulation and production method.

A molecular weight of about 32 obtained by condensing adipic acid, diethylene glycol and trimethylolpropane.
00 polyester polyol compound (hydroxyl value: 18
0 mgKOH / g), 100 parts of dibutyltin laurate, and 48 parts of conductive tin oxide in toluene 9
The mixture was dispersed and dissolved in 5 parts, and mixed with shaking for about 1 hour using a paint shaker. Polymeric MDI (amount in NCO: 38% by weight) was added to the mixture so that the molar ratio of NCO group / OH group was 0.2, 0.6, 0.9, 1.1 and 1.8, respectively. 70 parts were added and mixed and dispersed by a homomixer to obtain a coating material for a coating layer.

A coating layer having a thickness of about 50 to 200 μm is formed on the surface of the roller (1) by spray coating with the above coating material, and then dried and cured at 120 ° C. for 40 minutes to obtain the intermediate transfer body (1) of the present invention. Was.

The intermediate transfer member (1) was mounted on the full-color electrophotographic apparatus shown in FIG. 1, and a full-color image copying test was repeatedly performed using an OPC photosensitive drum having a photosensitive layer on an aluminum cylinder as a photosensitive member. . Table 1 shows the results.

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

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

[0066] (Example 3) Example 1, except that changing the paint coating layer as follows was conducted an endurance test in the same manner as in Example 1. In terms of image quality, a good full-color image was obtained, which was the same as the initial one even after 10,000 sheets. Table 1 shows the results.

Poly (oxypropylene) 100 parts of a polyether polyol compound (hydroxyl value: 148 mg KOH / g) composed of poly (oxyethylene) glycol and poly (oxypropylene) triol, 0.02 part of dibutyltin laurate, conductive oxidation 60 parts of titanium was dispersed and dissolved in 100 parts of toluene, and then hydrogenated MDI (molecular weight 2) was added thereto.
62) 31.2 g (in terms of NCO: 32% by weight) was added and mixed and dispersed with a homomixer to obtain a coating material for a coating layer.

Example 4 The coating material for the coating layer used in Example 2 was applied to the surface of an endless polytetrafluoroethylene belt to obtain a belt-shaped intermediate transfer member. Using the full-color electrophotographic apparatus shown in FIG. 5, the belt was subjected to an endurance test of 10,000 sheets. Table 1 shows the results.

(Comparative Example 4 ) A durability test was carried out in the same manner as in Example 1 except that an intermediate transfer member (having only an elastic layer) which was not formed with a coating layer was used in Example 2 , but about 3000 Filming gradually occurs on the surface of the intermediate transfer member from the sheet, and after 10,000 sheets, a fine streak appears on the image as if it were raining, adversely affecting the filming, and the image quality is not practical. Met.
In addition, the image quality was initially an ignorable minute hollow image, which was negligible, but after 10,000 copies, the defective image was clearly missing the center of the character. Table 1 shows the results.

[0070]

[Table 1]

[0071]

As described above, according to the image forming apparatus of the present invention, the transfer efficiency from the first image bearing member to the intermediate transfer member and from the intermediate transfer member to the second image bearing member are both high. Regardless of the type of paper or OHP sheet, it is possible to obtain a homogeneous image free from image defects such as image dropout. Good properties are maintained even after durability. Further, 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 of the present invention.

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

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

FIG. 4 is a schematic sectional view of one example of an intermediate transfer member of the present invention.

FIG. 5 is a schematic sectional view of an electrophotographic apparatus having an intermediate transfer member of the present invention.

FIG. 6 is an example of a missing image.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Atsushi Tanaka 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Tsunetori Ashbe 3-30-2 Shimomaruko, Ota-ku, Tokyo (56) References JP-A-4-296540 (JP, A) JP-A-3-38663 (JP, A) JP-A-5-278045 (JP, A) JP-A-4-226308 ( JP, A) (58) Fields surveyed (Int. Cl. ⁷ , DB name) G03G 15/01-15/01 117 G03G 15/16-15/16 103

Claims (6)

(57) [Claims] 1. An image forming apparatus for transferring an image formed on a first image carrier onto an intermediate transfer member and further transferring the image onto a second image carrier, wherein the intermediate transfer member has an elasticity.
A layer and the coating layer <br/> formed by coating as the upper layer, the coating layer contains polyurethane and resistance
The polyurethane comprises a polymer of an isocyanate compound and a polyol compound, and the molar ratio of isocyanate groups to hydroxyl groups in the polymer raw material is 0.8 ≦ NCO group / OH group. ≤ 1.3 . 2. The image forming apparatus according to claim 1, wherein the polyurethane is a polymer obtained by a polymerization reaction between an isocyanate compound and a polyester polyol compound. 3. The image forming apparatus according to claim 1, wherein the intermediate transfer member is a roller having an elastic layer. 4. The image forming apparatus according to claim 1, wherein said intermediate transfer member is a roller having an elastic layer and a coating layer. 5. The apparatus according to claim 1, wherein the intermediate transfer member is a belt.
The image forming apparatus as described in the above. 6. The image forming apparatus according to claim 1, wherein the first image carrier is a photosensitive drum having a photosensitive layer on a conductive rigid roller, and the intermediate transfer body is a rigid roller having an elastic layer. .