JPH0954505A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the defective images by transfer defects and pinhole leakage and to prevent the contamination of a photoreceptor even if the barrier property of a second layer is low by using the same binder as the binder of a second layer of an intermediate transfer medium for the binder of a first layer existing between this second layer and an elastic layer, thereby obviating the peeling of the second layer from the elastic layer in spite of repetitive use. SOLUTION: The intermediate transfer medium has at least the first layer 192 and the second layer 103 in this order on the elastic layer 101. The binder of the second layer 103 is made the same as the binder of the first layer 102. The same binders are satisfactory, insofar as these binders are the same system in the classification of resins and rubber. The resin systems include, for example, urethane, epoxy resins, silicone resins, unsatd. polyester, fluororesins, etc. In the case of, for example, the urethane system, the binders having urethane bonds which are the characteristics of the urethane system in the respective molecules of the first layer 102 and the second layer 103 may be regarded the same.

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 method, 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. The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile that obtains 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 or a multi-color image forming apparatus or a multi-color image forming apparatus that sequentially outputs a plurality of component color images of the color image information or the multi-color image information and outputs an image formed by combining and reproducing the color image or the 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 is a schematic view showing an example of an image forming apparatus which is a transfer apparatus using an intermediate transfer member having a roller shape.

FIG. 1 shows a color image forming apparatus (copier or laser beam printer) using an electrophotographic process. An elastic roller 20 having a medium and low resistance as an intermediate transfer member.
Are using.

Reference numeral 1 denotes a rotary drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) that is repeatedly used as a first image bearing member, and has a predetermined peripheral speed (process speed) in a clockwise direction indicated by an arrow. It is driven to rotate.

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 image exposing means (color separation of color original image The first exposure of the target color image by receiving the image exposure 3 by the imaging exposure optical system, the scanning exposure system by the laser scanner which outputs the laser beam modulated corresponding to the time series electric digital pixel signal of the image information). An electrostatic latent image corresponding to the color component image (for example, 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 42
The developing units 43 and 44 (cyan, yellow, and black) are not operated and do not act on the photosensitive drum 1, and the magenta toner image of the first color is the second to fourth 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 of this embodiment comprises a pipe-shaped core 21 and an elastic layer 22 formed on the outer peripheral surface thereof.

The above-mentioned first formed and carried 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.

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

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

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
It is applied from 1. The applied voltage is, for example, +2 kV to +
The range is 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 step of sequentially transferring the toner images of the fourth to fourth colors.

The transfer of the composite color toner image superimposed and transferred onto the intermediate transfer member 20 onto a transfer material 24 as a second image carrier is performed while the transfer roller 25 is brought into contact with the intermediate transfer member 20 and supplied. The transfer material 2 is transferred from the paper cassette 9 to the contact nip between the intermediate transfer body 20 and the transfer roller 25 at a predetermined timing.
4 is fed, and at the same time, a secondary transfer bias is applied to the transfer roller 25 from the bias power supply 29. 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 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 is completed, the transfer residual toner on the intermediate transfer body 20 is cleaned by contact with the intermediate transfer body cleaner 35.

In a color electrophotographic apparatus having an image forming apparatus using the above-mentioned intermediate transfer member, a second image carrier is attached or adsorbed on a transfer drum which is a conventional technique,
A color electrophotographic apparatus having an image forming apparatus for transferring an image thereon from a first image support is disclosed in
It has the following advantages over the transfer method as described in JP-A-301960. 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 is transferred from the intermediate transfer member without requiring any processing or control (eg, gripping by a gripper, adsorbing, giving a curvature, etc.) to the second image carrier. Therefore, a wide variety of second image carriers can be selected.

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 or width 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 the dimensional accuracy such as dents, strains, and deformations is changed due to repeated use, so that the frequency of replacement of the intermediate transfer member can be increased.

As described above, due to the advantage of using the intermediate transfer member, a color copying machine, a color printer or the like using this image forming apparatus has already started to operate in the market.

[0022]

However, when the image forming apparatus using the intermediate transfer member is actually repeatedly used, it still has the following problems to be overcome.

In order to enhance the transfer efficiency from the first image carrier, for example, the photosensitive drum to the intermediate transfer member, and the transfer efficiency from the intermediate transfer member to the second image carrier, such as paper or OHP sheet, the surface layer When a mixture of a large amount of highly lubricating powder is used as the binder of the surface layer of the intermediate transfer body using only the combination of the elastic layer and the elastic layer, even if the binder with high adhesiveness is used, the outermost surface is high in the first place. Due to the lubricity, the adhesion between the outermost layer and the elastic layer may not be good. Therefore, although it has a durability of about 30,000 to 40,000 sheets even in this state, the surface layer may be peeled or cracked from the elastic layer when the durability is further extended (for example, about 60,000 sheets). , The conductivity of the peeled part becomes insufficient when transferred, and unevenness of the image occurs due to insufficient transfer, or the cracked part does not transfer sufficiently and the surface condition of the cracked image is transferred as it is. There was something that happened. As a result, the intermediate transfer body must be replaced every 30,000 to 40,000 sheets, which may increase the running cost.

When a large amount of highly lubricating powder is mixed in the outermost layer binder, the adhesiveness between the binder and the highly lubricating powder may become insufficient, and therefore the elasticity of the surface layer may be reduced. The barrier property to the layer bleeding material may decrease, and the barrier property is maintained in a high temperature and high humidity environment for about 1 to 2 weeks, but if it is for a long period of 1 month or more, the interface between the binder and the highly lubricating powder In some cases, the bleeding material from the elastic layer may pass through the surface of the elastic layer to contaminate the photoconductor or the like and produce an image defect.

Furthermore, in order to increase the transfer efficiency from the first image carrier, for example, the photosensitive drum to the intermediate transfer member, and the transfer efficiency from the intermediate transfer member to the second image carrier, such as paper or OHP sheet. There is a method of setting the transfer bias high, but when the transfer bias is increased, when a conductive path leading to the back electrode of the photoconductor is formed due to foreign substances such as dents or metal powder mixed in the photoconductor, Similarly, when the surface layer is peeled off or cracked from the elastic layer due to long-term durability, an excessive current flows from the intermediate transfer member, and the voltage applied to the intermediate transfer member drops. In some cases, a poorly transferred portion was formed over the entire contact area, resulting in a defective image. Further, excessive current to the back electrode of the photoconductor may cause malfunction or damage of the electric control system of the electrophotographic apparatus.

The present invention proposes an image forming apparatus using an intermediate transfer member that solves the above problems.

That is, by using an intermediate transfer member having at least the first layer and the second layer in this order on the elastic layer and mixing a large amount of highly lubricating powder in the second layer, Even if the image is repeatedly output for a certain period, the second layer does not peel off or crack from the elastic layer, uniform conductivity and transfer property are obtained, and even when a bleeding substance is generated from the elastic layer, the photosensitive member is A transfer bias for increasing the transfer efficiency when transferring from the first image carrier to the intermediate transfer medium and when transferring from the intermediate transfer medium to the second image carrier without causing contamination and image defects. The present invention provides an image forming apparatus in which leakage does not occur even when is set high.

[0028]

SUMMARY OF THE INVENTION The above-mentioned problem is solved by an image forming apparatus 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. The intermediate transfer member has at least a first layer and a second layer in this order on the elastic layer, and the binder of the second layer is the same as the binder of the first layer. It was solved by the image forming apparatus.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, by using the same binder as the binder used in the second layer in the first layer between the second layer and the elastic layer, Even if a large amount of highly lubricious filler is mixed, since the binder in the second layer and the binder used in the first layer are the same resin, the adhesiveness between the second layer and the first layer is second. Is higher than the adhesiveness between the elastic layer and the elastic layer, and the first layer does not need to have releasability for the adhesion between the elastic layer and the first layer. In other words, the adhesion between the first layer and the elastic layer becomes good. As a result, even when the adhesion between the second layer and the elastic layer is not good, the first layer acts as an intermediary between the second layer and the elastic layer, so that high adhesion can be realized and repeated use is possible. When this happens, the second layer does not peel off or crack from the elastic layer, preventing transfer failure due to insufficient conduction in the peeled portion when transferring, and furthermore, providing high lubricity to the second layer. It is not necessary to mix the highly lubricating powder with the first layer even if a large amount of the above filler is mixed, so that it is not necessary to mix the highly lubricating powder with the first layer. No bleeding of the bleeding material is prevented, and contamination of the photoconductor can be prevented. Furthermore,
By providing the first layer between the elastic layer and the second layer, it is possible to prevent the cross current from flowing due to insufficient adhesion at the interface between the second layer and the elastic layer by improving the adhesion. Even if the drum has a pinhole or the like, an excessive current flows through the hole (hereinafter referred to as a pinhole leak), and a defective image is prevented by forming a portion that is not sufficiently transferred at the time of transfer.

As the binder used in the second layer and the first layer, for example, polyurethane resin, polystyrene, chloropolystyrene, poly-α-methylstyrene,
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-phenyl methacrylate copolymer, etc.), Styrene-α-chloromethyl acrylate copolymer, styrene-acrylonitrile-acrylic acid ester copolymer and other styrenic resins (styrene or styrene-substituted homopolymers or copolymers), vinyl chloride resin, styrene- Vinyl acetate copolymer, rosin-modified maleic acid resin, pheno Le resins, epoxy resins, polyester resins, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resins, silicone resins, ketone resins,
Ethylene-ethyl acrylate copolymer, xylene resin, fluororesin, polycarbonate, polyamide resin,
Examples thereof include polyvinyl butyral resins and resins such as copolymers and mixtures thereof. Further, urethane rubber, styrene-butadiene rubber, high styrene rubber, butadiene rubber, isoprene rubber, ethylene-propylene copolymer,
Examples thereof also include rubbers such as nitrile butadiene rubber, chloroprene rubber, butyl rubber, silicone rubber, fluorine rubber, nitrile rubber, acrylic rubber, epichlorohydrin rubber and norbornene rubber. Among these,
Urethane resins, rubbers, and elastomers are preferable because they have excellent durability.

The same binder used in the first layer and the second layer of the present invention may be the same type in terms of resin and rubber classification, and examples of the resin type include urethane type, epoxy resin type and silicon resin. System, unsaturated polyester system, fluororesin system, polyamide system, polyethylene system, polypropylene system, vinyl chloride system, vinylidene chloride system, polystyrene system, methacrylic resin system, polycarbonate system, polyacetal system and the like. If
If the urethane bond, which is a characteristic of the urethane type, is included in the molecules of the first layer and the second layer, they can be regarded as the same. Examples of the rubber type include urethane rubber type, styrene-butadiene rubber type, high styrene rubber type, butadiene rubber type, isoprene rubber type, ethylene type.
Propylene copolymer system, nitrile butadiene rubber system, chloroprene rubber system, butyl rubber system, silicone rubber system,
Examples thereof include fluororubber-based, nitrile rubber-based, acrylic rubber-based, epichlorohydrin rubber-based, norbornene rubber-based and the like. As described above, if the listed resins and rubbers are the same in classification, they can be regarded as the same binder and the effect of the present invention can be obtained, but more preferably, they are used in the first layer and the second layer. In the binder in which the main chains in the binder molecule each have the same structure and the binder has a side chain different from the main chain, the first layer and the second layer
When the weight ratio of the main chain of each layer is 20% or more of the total molecular weight, it can be regarded as the same binder and higher adhesiveness can be realized.

More preferably, it is desirable that the binders used in the first layer and the second layer have the same molecular structure, and this is also regarded as the same binder, whereby higher adhesiveness is realized. can do. In this case, since the binders have only to have the same structure, they have the same structure even if the average molecular weights are different, and therefore they are regarded as the same binder. Furthermore, in a polyaddition reaction type binder such as polyurethane, the reaction between the isocyanate and the polyol may be different between the first layer and the second layer. In this case also, the isocyanate and the polyol having the same structure are used. If so, they can be regarded as the same binder. In this way, the unreacted part remains depending on the polymerization conditions, and even if it is different between the first layer and the second layer, if the finally used polymer has the same structure, it should be regarded as the same binder. You can

In addition, for a binder having a complicated composition such as rubber, the vulcanization aid may be slightly changed,
If the base rubbers have the same structure, they can also be regarded as the same binder.

In the present invention, the elongation of the binder is 150% or more and the tensile strength is 3 to improve the adhesion.
00kgf / cm ² or more and 100% tensile stress is 25
It is preferably 0 kgf / cm ² or less, more preferably 250% or more in elongation and 400 kgf in tensile strength.
/ Cm ² or more and 100% tensile stress is 200 kgf /
cm ² or less, particularly preferably, elongation is 350% or more, tensile strength is 450 kgf / cm ² or more, and 100
The% tensile stress is 150 kgf / cm ² or less.

The elongation, tensile strength and 100% tensile stress are measured values according to JIS K6301.

Further, between the first layer and the elastic layer or between the first and second layers.
A surface treatment agent such as a primer may be applied between the layers in order to further improve the adhesiveness.

Examples of the surface treatment agent include those using a silane compound, those using a titanate compound, those using an isocyanate resin, those using an epoxy resin, and those using a thermoplastic resin. Not a thing.

Further, in order to further improve the bleeding prevention effect from the elastic layer, a bleeding prevention layer may be provided between the first layer and the elastic layer or between the first and second layers.

Examples of the bleed preventive layer include resins having a high barrier property, such as nylon, vinylidene chloride, polyethylene terephthalate, polyvinyl alcohol, ethylene vinyl alcohol, but not limited to these.

In order to further improve the leak prevention effect, a leak prevention layer may be provided between the first layer and the elastic layer or between the first and second layers.

As the leak prevention layer, a resin having a high leak resistance such as nylon, polystyrene, polyethylene,
Examples thereof include, but are not limited to, vinylidene chloride, polyethylene terephthalate, polyvinyl alcohol and ethylene vinyl alcohol.

A surface protective layer may be provided on the second layer in order to protect the second layer from abrasion, cracks and the like.

As the surface protective layer, a resin having high abrasion resistance,
For example, there are polyurethane, nylon, polycarbonate, acrylic, polystyrene, polyethylene, vinylidene chloride, polyethylene terephthalate, etc., but not limited thereto.

The binder, surface treatment agent, bleed prevention layer, leak prevention layer, and surface protection layer can be applied by a spray coating method, a dipping method, a roll coating method, a brush coating method, or a powder coating method. There are things by body painting method. In addition, the binder, surface treatment agent, bleed prevention layer, leak prevention layer, and surface protection layer used in the first layer and the second layer may be provided with conductivity, and there is no risk of leakage. When the second layer is used or in the case of an intermediate transfer body to which a low voltage is applied, conductivity is imparted to the binder, surface treatment agent, bleed prevention layer, leak prevention layer and surface protection layer used in the first layer. There is no problem doing it. However, in a more preferable aspect, it is important for the first layer to have appropriate conductivity in order to maintain the resistance of the entire intermediate transfer member at a medium resistance. First
The preferable range of the surface resistance of the layer is 10 ⁰ to 10 ¹²
Ω / □, and this range can be obtained, for example, by adding the following conductive agent.

Examples of the method of imparting conductivity include conductive fillers and additives. Specifically, examples of the conductive filler include carbon, conductive titanium oxide, aluminum, and nickel, and examples of the additive include a surfactant and a perchlorate.

The conductive agent used for these is not limited to the above.

The highly lubricious powder used in the present invention is not particularly limited as long as it can impart lubricity to the surface of the intermediate transfer member, and various materials can be used.

The following method can be used to determine the lubricity of the powder used in the present invention.

20 parts by weight of the powder to be tested, 100 parts by weight of polyester polyurethane prepolymer (100% solid content) and 100 parts by weight of a suitable solvent were mixed and stirred, and 5 parts by weight of a curing agent were added and mixed, and then on a PET plate. Spray coating on
A test sample is prepared by drying and curing.
At this time, care should be taken to adjust the viscosity of the coating with a mixed solvent of toluene and MEK to obtain a uniform coating surface.
On the other hand, a comparative painted sample is prepared in the same manner except that the powder to be tested is not added. Next, the surface measurement device HEID
ON 14-DR (manufactured by Shinto Scientific Co., Ltd.) is used to measure the slip resistance of both. The measurement method is as follows: An unpainted PET plate is fixed as a measurement object to a flat indenter specified by ASTM D1894, and 100 m under a vertical load of 200 gf.
m / min. The coating sample is moved horizontally at the speed of.
If the slip resistance of the test sample is 80% or less of the comparative sample, it can be determined that the test powder is a highly lubricating powder.

Therefore, examples of the highly lubricating powder include the followings, but are not necessarily limited to these. Tetrafluoroethylene resin, trifluoroethylene chloride resin, tetrafluoroethylene hexafluoropropylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluorodichloroethylene resin and their copolymers, fluorocarbon , Silicone compounds such as silicone resin, silicone rubber, silicone elastomer, polyethylene, polypropylene, polystyrene, acrylic resin, nylon resin,
Phenolic resin, epoxy resin, and these compounds,
One or more kinds are appropriately selected from a mixture, an inorganic material such as silica and alumina, and the like, and a tetrafluoroethylene resin and a tetrafluoroethylene hexafluoropropylene resin are particularly preferable. Further, the shape and particle size of the highly lubricious powder are not particularly limited, and any shape can be used, and the particle size is not limited, but in consideration of dispersibility and surface property, it is 0.
The range of 02 to 50 μm is preferable. Further, if necessary, surface treatment may be carried out within a range not impairing lubricity, and a dispersant may be used within a range not giving a problem to various characteristics.

The intermediate transfer member used in the present invention has, for example, an elastic layer made of rubber, elastomer or resin on a cylindrical conductive support, and further has two or more coating layers on the elastic layer. A roller shape or a belt shape as shown in FIG. 2 and various modes can be selected depending on the purpose and need. Examples of the configuration are shown in FIGS.

Considering the color misregistration in the superposition of images and the durability due to repeated use, a roller shape is a more preferable embodiment of the present invention. In FIG. 3, 100
Is a rigid cylindrical conductive support, 101 is an elastic layer, 1
Reference numeral 02 represents the first layer, and 103 represents the second layer. FIG. 4 shows an example of an intermediate transfer belt, 101 is an elastic layer, 102 is a first layer, and 103 is a second layer. Further, reference numeral 104 in FIG. 2 denotes an intermediate transfer belt. Also in these examples the first
The layer of is composed of one layer, but further layers are stacked in addition to the first layer.
It is of course possible to have more layers.

As the cylindrical conductive support, a metal or alloy such as aluminum, iron, copper and stainless, a conductive resin having carbon or metal particles dispersed therein, or the like can be used, and the shape thereof is as described above. Such a cylindrical shape, a shape in which a shaft penetrates through the center of the cylinder, a shape in which the inside of the cylinder is reinforced, and the like can be mentioned.

As the rubber or elastomer used in the elastic layer of the intermediate transfer member used in the present invention, for example, styrene-
Butadiene rubber, high styrene rubber, butadiene rubber,
Isoprene rubber, ethylene-propylene copolymer, nitrile butadiene rubber, chloroprene rubber, butyl rubber,
Examples include silicone rubber, fluorine rubber, nitrile rubber, urethane rubber, acrylic rubber, epichlorohydrin rubber, norbornene rubber, and the like.

The thickness of the elastic layer is 0.5 mm or more, and further 1
mm or more, particularly preferably 1 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 the surface of the photoreceptor, specifically, 3 mm or less, further 2 mm or less, and particularly It is preferably 20 μm to 1 mm.

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

[0057]

Embodiments will be described below. [Example 1] (Preparation of compound for elastic layer) EPDM 100 parts by weight, zinc oxide 5 parts by weight, higher fatty acid 1 part by weight, conductive carbon black 5 parts by weight, paraffin oil 10 parts by weight, sulfur 2 parts by weight, vulcanization Accelerator MBT 1 part by weight, vulcanization accelerator TMTD 1.5 parts by weight, and vulcanization accelerator ZnM
While cooling 1.5 parts by weight of DC with two rolls, 20
Mix for minutes to make a compound.

(Preparation of coating material for the first layer (hereinafter referred to as the first layer)) 100 parts by weight of polyurethane elastomer (the same product as the coating material for the second layer) and 1000 parts by weight of DMF were mixed to prepare the coating material for the first layer A paint was prepared. The surface resistance of this layer is 10
It was ¹¹ Ω / □.

(Preparation of coating material for second layer (hereinafter referred to as second layer)) 100 parts by weight of polyurethane elastomer, 40 parts by weight of conductive titanium oxide, 12 parts by weight of dispersion aid, tetrafluoroethylene resin powder (particles) 400 parts by weight (diameter 0.3 μm) and 1200 parts by weight of DMF were mixed to prepare a coating material for the second layer.

(Evaluation of Polyurethane Elastomer) Only the polyurethane elastomer solution used in this example was dried,
The elastomer obtained by curing has an elongation of 500%, a tensile strength of 450 kgf / cm ² , and a 100% tensile stress of 10%.
It was 0 kgf / cm ² .

(Preparation and evaluation of intermediate transfer member) Diameter 182 m
A rubber roller having an elastic layer was obtained by first transfer molding and vulcanizing an elastic layer compound on the surface of an aluminum cylindrical roller having a length of m, a length of 320 mm and a thickness of 5 mm using a mold. Next, the first layer paint is spray-coated on the first layer to form a first layer, and then the second layer paint is spray-coated on the second layer to form an elastic layer and a second layer. An intermediate transfer member having a three-layer structure having the first layer using the same binder as the binder for the second layer paint was obtained. This intermediate transfer member is placed at a temperature of 23 ° C. and a humidity of 65.
%, The transfer surface of the intermediate transfer member is placed in contact with a 350 mm × 200 mm aluminum plate in an environment of 1%, and a voltage of 1 kV is applied by a high voltage power supply between the aluminum roller and the aluminum plate on the inner surface of the intermediate transfer member. The potential difference before and after the 1 kΩ resistor connected in series with was measured and converted to a current value, and the resistance value of the intermediate transfer member was calculated from the applied voltage (1 kV) and this current value. It was 10 ⁷ Ω.

This intermediate transfer member was mounted on the full-color electrophotographic apparatus shown in FIG. 1, and the transfer efficiency was measured for a single cyan color using an organic photosensitive drum as a photosensitive member. here,
As the organic photosensitive drum, one having an undercoat layer, a charge generation layer, and a charge transport layer on an aluminum roller was used. The primary transfer efficiency from the photosensitive drum, which is the first image carrier, to the intermediate transfer member is 94%, and the secondary transfer efficiency from the intermediate transfer member to the 80 g / m ² paper, which is the second image carrier, is 92%. %, And a high lubricity powder was mixed in a large amount, resulting in good transfer efficiency. In this specification, the primary transfer efficiency and the secondary transfer efficiency are values obtained by the following equations.

[0063]

The method for measuring the density of each image is as follows.

First, an adhesive tape was attached to each image and peeled off to collect the toner corresponding to the image. Next, there were prepared a sample in which the adhesive tape carrying the toner was attached to white paper and a reference sample in which the adhesive tape not bearing the toner was attached to white paper.
The density of each image was determined by measuring the density of these samples with the reflection densitometer.

Next, a full-color image print test was repeated by using an organic photosensitive drum as a photosensitive member.
The full-color print image had a uniform image quality in the solid image. Even after the endurance test of 60,000 sheets, even though a large amount of highly lubricating powder was mixed in the second layer, the effect of the first layer showed no cracking or floating on the surface of the intermediate transfer member. Similar image quality was obtained. After the durability test, the intermediate transfer member was mounted on the full-color electrophotographic apparatus shown in FIG. 1 and the organic drum as a photosensitive member had a diameter of 0.
When a transfer was performed by applying a primary transfer voltage of +5 kV using a 5 mm hole in which the substrate was visible, a pinhole leak did not occur and a stable image was obtained.

After this test, a 1 cm square incision was made on the surface of the intermediate transfer member by a cutter, and a gum tape was attached on it, and then peeled off. The surface layer (second layer) was not peeled off. It was found that one layer provided sufficient adhesion.

An organic photoconductor drum was brought into contact with the intermediate transfer member, left for 1 month in an environment of 40 ° C. and 95% RH, and the contact surface of the organic photoconductor drum was observed. No cloudiness or cracks were observed, and full-color image printing was performed using this organic photoconductor drum. A uniform image quality was obtained in a solid image, and bleeding from the elastic layer due to the use of the first layer It turns out that the barrier property is high.

[Example 2] (Preparation of compound for elastic layer) The same as Example 1.

(Preparation of coating material for the first layer) 100 parts by weight of polyurethane elastomer (the same product as the coating material for the second layer), 30 parts by weight of conductive aluminum borate whiskers, and DM
1000 parts by weight of F was mixed to prepare a coating material for the first layer. The surface resistance of this layer was 10 ⁸ Ω / □.

(Preparation of Second Layer Coating Material) 100 parts by weight of polyurethane elastomer, 12 parts by weight of dispersion aid, 400 parts by weight of tetrafluoroethylene resin powder (particle size 0.3 μm), and 1200 parts by weight of DMF are mixed. Then, a second layer coating material was prepared.

(Evaluation of Polyurethane Elastomer) Same as Example 1 (Preparation and Evaluation of Intermediate Transfer Body) Diameter 182 mm, Length 32
A rubber roller having an elastic layer was obtained by first transfer molding and vulcanizing an elastic layer compound on the surface of an aluminum cylindrical roller having a thickness of 0 mm and a thickness of 5 mm using a mold. Next, the first layer coating material is spray coated onto the first layer to form a first layer, and then the second layer coating material is spray coated onto the second layer to form an elastic layer and a second layer.
An intermediate transfer member having a three-layer structure having the first layer using the same binder as the binder for the second layer coating between the layers was obtained.
When the resistance value of this intermediate transfer member was measured by the same method as in Example 1, it was 2.0 × 10 ⁷ Ω, and although the second layer contained no conductive agent, the first layer contained no conductive agent. Since it was contained, the resistance value was almost the same as in Example 1.

This intermediate transfer member was mounted on the full-color electrophotographic apparatus shown in FIG. 1, and the transfer efficiency was measured for a single cyan color using an organic photosensitive drum as a photosensitive member. The primary transfer efficiency from the photosensitive drum, which is the first image carrier, to the intermediate transfer member is 94%, and the secondary transfer efficiency from the intermediate transfer member to the 80 g / m ² paper, which is the second image carrier, is 92%. ．
5%. Next, a full-color image print test was repeated by using an organic photosensitive drum as a photoconductor. The full-color print image had a uniform image quality in the solid image. Also, after the durability test of 60,000 sheets, the second
Despite mixing a large amount of highly lubricating powder in the layer
Due to the effect of the layers, no cracks or floating were observed on the surface of the intermediate transfer member, and the image quality similar to the initial one was obtained. After the durability test, the intermediate transfer member was mounted on the full-color electrophotographic apparatus shown in FIG. 1, and an organic drum as a photosensitive member was used with a hole having a diameter of 0.5 mm drilled until the base material was visible. When transferred by applying a primary transfer voltage of +5 kV, the second layer does not contain a conductive agent, so even if the first layer contains a conductive agent, pinhole leakage does not occur and a stable image is obtained. Was given.

After this test, a 1 cm square incision was made on the surface of the intermediate transfer member by a cutter, and a gum tape was attached on it, and when it was peeled off, the surface layer (second layer) did not peel off. It was found that one layer provided sufficient adhesion.

An organic photoconductor drum was brought into contact with the intermediate transfer member, allowed to stand for 1 month in an environment of 40 ° C. and 95% RH, and the contact surface of the organic photoconductor drum was observed. No cloudiness or cracks were observed, and full-color image printing was performed using this organic photoconductor drum. A uniform image quality was obtained in a solid image, and bleeding from the elastic layer due to the use of the first layer It turns out that the barrier property is high.

[Example 3] (Preparation of compound for elastic layer) The same as Example 1.

(Preparation of coating material for the first layer) 100 parts by weight of polyurethane elastomer (the same product as the coating material for the second layer), 30 parts by weight of conductive aluminum borate whiskers, and D
1000 parts by weight of MF was mixed to prepare a coating material for the first layer.

(Preparation of coating material for the second layer) 100 parts by weight of polyurethane elastomer, 12 parts by weight of dispersion aid, 400 parts by weight of tetrafluoroethylene resin powder (particle size 0.3 μm), and 1200 parts by weight of DMF are mixed. Then, a second layer coating material was prepared.

(Preparation of coating material for surface treatment of elastic layer) γ- (2
-Aminoethyl) aminopropylmethyldimethoxysilane 50 parts by weight, methanol 20 parts by weight, and toluene 1
50 parts by weight were mixed to prepare a coating material for elastic layer surface treatment.

(Evaluation of Polyurethane Elastomer) Same as in Example 1.

(Preparation and evaluation of intermediate transfer member) Diameter 182 m
First, a rubber roller having an elastic layer was obtained by transfer-molding and vulcanizing an elastic layer compound on a surface of an aluminum cylindrical roller having a length of m, a length of 320 mm and a thickness of 5 mm using a mold. Next, after the surface treatment is performed by spray-coating with the elastic layer surface-treating paint, the first layer paint is spray-applied thereon to form the first layer, and then the second layer is further formed thereon. When the second layer is formed by spray coating with the layer coating material, the surface of the elastic layer has a silane compound as a surface treatment agent, and the elastic layer and the second layer
An intermediate transfer member having a four-layer structure having a first layer using the same binder as the binder for the second layer coating between the layers was obtained.
When the resistance value of this intermediate transfer member was measured by the same method as in Example 1, it was 5.0 × 10 ⁷ Ω, and the resistance value was slightly increased due to the presence of the silane compound on the surface of the elastic layer.

This intermediate transfer member was mounted on the full-color electrophotographic apparatus shown in FIG. 1, and the transfer efficiency was measured for a single cyan color using an organic photosensitive drum as a photosensitive member. The primary transfer efficiency from the photosensitive drum, which is the first image carrier, to the intermediate transfer member is 93.5%, and the secondary transfer efficiency from the intermediate transfer member to 80 g / m ² paper, which is the second image carrier, is Is 9
It was 3%. Next, a full-color image print test was repeated by using an organic photosensitive drum as a photoconductor. The full-color print image had a uniform image quality in the solid image. Also, after the durability test of 70,000 sheets, the second
Despite mixing a large amount of highly lubricating powder in the layer
Due to the effect of the layer and the silane-based compound, no crack or floating was observed on the surface of the intermediate transfer member, and the image quality similar to the initial stage was obtained. After the durability test, the intermediate transfer member was mounted on the full-color electrophotographic apparatus shown in FIG. 1, and an organic drum as a photosensitive member was used with a hole having a diameter of 0.5 mm drilled until the base material was visible. When the transfer was performed by applying a primary transfer voltage of +5 kV, the second layer contained no conductive agent.
Even if the first layer contained a conductive agent, pinhole leak did not occur and a stable image was obtained.

After this test, a 1 cm square incision was made on the surface of the intermediate transfer member by a cutter, and a gum tape was attached on it, and when it was peeled off, the surface layer (second layer) was not peeled off. It was found that one layer and the silane-based compound were in close contact.

An organic photoconductor drum was brought into contact with the intermediate transfer member, left for 1 month in an environment of 40 ° C. and 95% RH, and the contact surface of the organic photoconductor drum was observed. No cloudiness or cracks were observed, and full-color image printing was performed using this organic photoconductor drum. A uniform image quality was obtained in a solid image, and bleeding from the elastic layer due to the use of the first layer It turns out that the barrier property is high.

[Example 4] (Preparation of compound for elastic layer) The same as Example 1.

(Preparation of coating material for first layer) 100 parts by weight of polyurethane elastomer (same product as coating material for second layer), 30 parts by weight of conductive aluminum borate whiskers, and D
1000 parts by weight of MF was mixed to prepare a coating material for the first layer.

(Preparation of coating material for the second layer) 100 parts by weight of polyurethane elastomer, 12 parts by weight of dispersion aid, 400 parts by weight of tetrafluoroethylene resin powder (particle size 0.3 μm), and 1200 parts by weight of DMF are mixed. Then, a second layer coating material was prepared.

(Preparation of coating material for elastic layer bleed material barrier layer) 100 parts by weight of methylolated nylon, 4 parts of methanol
A nylon coating material was prepared by mixing 20 parts by weight and 150 parts by weight of toluene.

(Evaluation of Polyurethane Elastomer) Same as in Example 1.

(Preparation and evaluation of intermediate transfer member) Diameter 182 m
A rubber roller having an elastic layer was obtained by first transfer molding and vulcanizing an elastic layer compound on the surface of an aluminum cylindrical roller having a length of m, a length of 320 mm and a thickness of 5 mm using a mold. Next, after performing a barrier treatment by spray-coating the elastic layer bleeding material with a barrier-layer coating, spray-coating with the first-layer coating onto this to form a first layer, and further onto this By spray coating with the second layer coating to form the second layer, there is a nylon resin as a barrier layer on the surface of the elastic layer, and a binder for the second layer coating is provided between the elastic layer and the second layer. A four-layered intermediate transfer member having the first layer was obtained using the same binder. When the resistance value of this intermediate transfer member was measured by the same method as in Example 1, it was 1.2 × 10 ⁷ Ω.

This intermediate transfer member was mounted on the full-color electrophotographic apparatus shown in FIG. 1, and the transfer efficiency was measured for a single cyan color using an organic photosensitive drum as a photosensitive member. The primary transfer efficiency from the photosensitive drum, which is the first image carrier, to the intermediate transfer member is 94%, and the secondary transfer efficiency from the intermediate transfer member to the 80 g / m ² paper, which is the second image carrier, is 92%. ．
7%. Next, a full-color image print test was repeated by using an organic photosensitive drum as a photoconductor. The full-color print image had a uniform image quality in the solid image. Also, after the durability test of 60,000 sheets, the second
Despite mixing a large amount of highly lubricating powder in the layer
Due to the effect of the layers, no cracks or floating were observed on the surface of the intermediate transfer member, and the image quality similar to the initial one was obtained. After the durability test, the intermediate transfer member was mounted on the full-color electrophotographic apparatus shown in FIG. 1, and an organic drum as a photosensitive member was used with a hole having a diameter of 0.5 mm drilled until the base material was visible. When transferred by applying a primary transfer voltage of +5 kV, the second layer does not contain a conductive agent, so even if the first layer contains a conductive agent, pinhole leakage does not occur and a stable image is obtained. Was given.

After this test, a 1 cm square incision was made on the surface of the intermediate transfer member by a cutter, gum tape was attached on the cut, and then peeled off. As a result, the surface layer (second layer) was not peeled off. It was found that one layer and the silane-based compound were in close contact.

Further, the organic photosensitive drum was brought into contact with the intermediate transfer member, left for 2 days in an environment of 70 ° C., and the contact surface of the organic photosensitive drum was observed. As a result, the surface was fogged and cracked. No such defects were observed, and a full-color image print was performed using this organic photoconductor drum. A uniform image quality was obtained in a solid image, and a barrier against bleeding from the elastic layer by using the first layer and the barrier layer. It turned out that it has high quality.

Comparative Example 1 (Preparation of Compound for Elastic Layer) Same as in Example 1.

(Preparation of paint) The same as the preparation of the paint for the second layer in Example 1.

(Preparation and Evaluation of Intermediate Transfer Member) Example 1 except that there is no first layer between the second layer and the elastic layer of Example 1.
An intermediate transfer member having a two-layer structure was obtained by the same preparation method as described above.

When the resistance value of this intermediate transfer member was measured by the same method as in Example 1, it was 6.5 because it did not have the first layer.
It was × 10 ⁶ Ω.

This intermediate transfer member was mounted on the full-color electrophotographic apparatus shown in FIG. 1, and the transfer efficiency was measured for a single cyan color using an organic photosensitive drum as a photosensitive member. The primary transfer efficiency from the photosensitive drum, which is the first image carrier, to the intermediate transfer member is 94%, and the secondary transfer efficiency from the intermediate transfer member to the 80 g / m ² paper, which is the second image carrier, is 92%. %
Was the same as in Example 1. Next, a full-color image print test was repeated by using an organic photosensitive drum as a photoconductor. Initially, the full-color print image had a uniform image quality in a solid image. However, when the second layer after the endurance test of 60,000 sheets was observed, cracks and floating of the second layer were observed on the surface of the intermediate transfer member due to the mixing of a large amount of highly lubricating powder. As a result, uneven transfer occurred, and the intermediate transfer member had no durability. After the durability test, the intermediate transfer member was mounted on the full-color electrophotographic apparatus shown in FIG. 1, and an organic drum as a photosensitive member was used with a hole having a diameter of 0.5 mm drilled until the base material was visible. When the transfer was performed by applying a primary transfer voltage of +5 kV, a pinhole leak due to the floating of the second layer occurred.

After this endurance test, a 1 cm square incision was made on the surface of the intermediate transfer member by a cutter, a gum tape was attached on the cut, and then peeled off, and the surface layer was peeled off and adhesion was insufficient. I found out.

An organic photoconductor drum was brought into contact with the intermediate transfer member, left for 1 month in an environment of 40 ° C. and 95% RH, and the contact surface of the organic photoconductor drum was observed. Cracks were observed, and full-color image printing was performed using this organic photoconductor drum.However, horizontal streak unevenness due to cracks occurred in solid images, and the barrier property against bleeding from the elastic layer was low. found.

[0101]

As described above, according to the present invention, the same binder as the second layer is used as the binder of the first layer intermediate between the second layer and the elastic layer of the intermediate transfer member. Even when the second layer is repeatedly used for a long period of time, the second layer is not peeled off from the elastic layer, and it is possible to prevent a transfer failure due to insufficient conduction of the peeled portion at the time of transfer. Furthermore, even when the second layer is repeatedly used for a long period of time, the second layer does not peel off from the elastic layer, so that a defective image due to pinhole leakage due to the peeling can be prevented, and further, the first layer is provided. As a result, even if the barrier property of the second layer is low, it is possible to prevent contamination of the photoconductor.

Therefore, when the image forming apparatus having the intermediate transfer member is actually repeatedly used, a uniform image can always be obtained, the life of the intermediate transfer member can be extended, and the running cost can be reduced. be able to.

[Brief description of drawings]

FIG. 1 is a schematic view of a color image output apparatus using a roller-shaped intermediate transfer member.

FIG. 2 is a schematic diagram of a color image output device using an intermediate transfer belt.

FIG. 3 is a schematic sectional view of a roller-shaped intermediate transfer member.

FIG. 4 is a schematic sectional view of a belt-shaped intermediate transfer member.

[Explanation of symbols]

 1 Photosensitive Drum 2 Primary Charger 3 Image Exposure 9 Paper Feed Cassette 14 Photosensitive Drum Cleaning Device 15 Fixing Device 20 Intermediate Transfer Body 21 Core Bar 22 Elastic Layer 24 Transfer Material 25 Transfer Roller 29 Bias Power Supply 35 Intermediate Transfer Body Cleaner 41 Magenta Color developing device 42 Cyan color developing device 43 Yellow color developing device 44 Black color developing device 61 Bias power supply 100 Core metal 101 Elastic layer 102 Covering layer 103 Covering layer 104 Belt-shaped intermediate transfer member

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Atsushi Tanaka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Hiroyuki Kobayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. Within the corporation

Claims (8)

[Claims] 1. An image forming apparatus for transferring an image formed on a first image bearing member onto an intermediate transferring member and then further transferring it onto a second image bearing member, wherein the intermediate transferring member is at least An image forming apparatus having a first layer and a second layer in this order on an elastic layer, and the binder of the second layer is the same as the binder of the first layer. 2. The image forming apparatus according to claim 1, wherein the second layer of the intermediate transfer member contains the highly lubricating powder in an amount of 20 to 80% by weight based on the total solid content of the second layer. 3. The binder used for the first layer and the second layer of the intermediate transfer member has an elongation of 150% or more, a tensile strength of 300 kgf / cm ² or more, and a 100% tensile stress of 250 kgf / cm ^2. The image forming apparatus according to claim 1, wherein: 4. The image forming apparatus according to claim 1, wherein the first layer of the intermediate transfer member contains a conductive agent. 5. The image forming apparatus according to claim 2, wherein the second layer of the intermediate transfer member is a surface layer. 6. The first image carrier is a photosensitive drum having a photosensitive layer on a conductive rigid roller, and the intermediate transfer member is an elastic layer, a first layer and a second layer on at least the rigid roller. The image forming apparatus according to claim 1, wherein the image forming apparatus has the layers of 1. 7. The intermediate transfer member is a belt.
The image forming apparatus as described in the above. 8. The image forming apparatus according to claim 1, wherein the first image carrier is an organic photoconductor.