JP2008233511A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that suppresses image defects due to toner scattering or transfer failure even in repeated image output for a long period of time and provides a superior output image. <P>SOLUTION: The image forming apparatus is equipped with an image holder, a charging means to charge the image holder, an exposure means to form an electrostatic latent image on the charged image holder, a developing means to develop the electrostatic latent image to form a toner image, a primary transfer means to transfer the toner image onto an intermediate transfer body, and a secondary transfer means to transfer the toner image once transferred onto the intermediate transfer body to an image output medium. The apparatus satisfies all of the following expressions (1): 0≤Log(R)-Log(6.0×10<SP>11</SP>×tanδ), (2): 9.2≤Log(R)≤10.0, and (3): 1.0×10<SP>-3</SP>≤tanδ≤10.0×10<SP>-3</SP>, wherein Log(R) represents a common logarithm (logΩ/square) of the surface resistivity of the intermediate transfer body and tanδ represents the dielectric loss tangent of the toner at 1 kHz. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus using an electrophotographic system such as an electrophotographic copying machine, a laser printer, and a facsimile.

  In an electrophotographic image forming apparatus, a latent image carrier made of an inorganic or organic photoconductive material is charged to a uniform potential, and an optical image signal is exposed by a laser, a light emitting diode, or the like. After forming the image, the electrostatic latent image is developed with charged toner to form a visualized toner image. Then, the toner image is electrostatically transferred to an image output medium such as paper or OHP directly through an intermediate transfer member, and is further fixed to the image output medium by overheating or pressurizing, so that a desired image is obtained. Output image.

  In recent years, many tandem-type full-color image forming apparatuses capable of arranging a plurality of electrophotographic photosensitive members as image carriers in the process direction and forming each color of an image at once have been put into practical use. In such a tandem type image forming apparatus, a belt-shaped intermediate transfer body having a high degree of freedom in the configuration of the apparatus for transferring each color at once, so-called an intermediate transfer belt, is often used.

The material of the intermediate transfer belt is a semiconductive endless material made of a thermoplastic resin such as polycarbonate resin, polyvinylidene fluoride resin, polyalkylene phthalate resin, polycarbonate / polyalkylene phthalate blend material, ethylene tetrafluoroethylene copolymer, etc. A belt or the like is used.
In recent years, an intermediate transfer belt in which a polyimide resin is a main component and conductive particles such as carbon black are dispersed has been put into practical use. An intermediate transfer belt mainly composed of a polyimide resin is particularly suitably used for the above-described tandem-type full-color image forming apparatus because of its high mechanical strength, high elastic modulus, and excellent creep resistance.

  Further, the intermediate transfer belt is required to have not only mechanical strength but also stability over time of electric resistance. Among these, the surface resistivity of the intermediate transfer belt is extremely important because it retains the toner image transferred from the image carrier and transfers the toner image to the image output medium without causing toner scattering. . That is, when the surface resistivity of the intermediate transfer belt decreases due to aging, etc., not only the toner image on the intermediate transfer belt is disturbed, but also in the transfer to the image output medium, the toner scatters around the image and the image quality deteriorates. End up. Therefore, in order to prevent toner scattering, it is necessary to maintain the surface resistivity of the intermediate transfer belt within a predetermined range.

On the other hand, in the toner in the image forming apparatus, after being charged to a predetermined charge amount by stirring, the electrostatic latent image on the image holding member is visualized in the development process, and is transferred onto the intermediate transfer belt in the transfer process. Further, it is required to maintain a predetermined charge amount until it is transferred to the image output medium. That is, when the charge holding capability of the toner is not sufficient, the charge of the toner changes on the intermediate transfer belt and the output image deteriorates. As a technique for preventing such a change in toner charge amount, for example, Patent Document 1 discloses a technique for controlling the surface resistivity of the intermediate transfer belt and the volume resistance of the external additive of the toner within predetermined ranges. Is disclosed.
Japanese Patent Laid-Open No. 10-207245

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of suppressing an image defect due to toner scattering and transfer failure even during long-term repeated image output and obtaining a good output image.

  As a result of intensive studies to achieve the above object, the present inventor can solve the above problems by controlling the surface resistivity of the intermediate transfer member and the dielectric loss tangent of the toner at 1 kHz to a predetermined relationship. As a result, the present invention has been completed.

That is, the image forming apparatus of the present invention includes an image carrier, a charging unit that charges the image carrier, an exposure unit that forms an electrostatic latent image on the image carrier charged by the charging unit, Developing means for developing the electrostatic latent image on the image carrier with toner to form a toner image, primary transfer means for transferring the toner image to the intermediate transfer body, and toner image transferred to the intermediate transfer body And a secondary transfer unit that transfers the image to the image output medium, and satisfies all of the following formulas (1), (2), and (3).
0 ≦ Log (R) −Log (6.0 × 10 ¹¹ × tan δ) (1)
9.2 ≦ Log (R) ≦ 10.0 (2)
1.0 × 10 ⁻³ ≦ tan δ ≦ 10.0 × 10 ⁻³ (3)
[In the above formulas (1) to (3), Log (R) represents a common logarithm value (logΩ / □) of the surface resistivity of the intermediate transfer member, and tan δ represents a dielectric loss tangent of the toner at 1 kHz. ]

In the present invention, the intermediate transfer member is preferably an intermediate transfer belt.
The toner preferably contains carbon black.
Furthermore, it is a preferable aspect that the process speed is 50 mm / sec or more and 500 mm / sec or less.

The reason why the above effect can be obtained by the image forming apparatus of the present invention is not necessarily clear, but the present inventor presumes as follows.
When the surface resistivity of the intermediate transfer belt (intermediate transfer member) is high, the surface of the intermediate transfer belt is altered by the peeling discharge generated between the intermediate transfer belt and the image output medium, and the surface of the intermediate transfer belt can be output repeatedly for a long time. The resistivity decreases. When the surface resistivity of the intermediate transfer belt decreases, the transfer electric field circulates around the toner in the transfer process. Therefore, the distribution of the transfer electric field is disturbed to cause toner scattering and the output image is deteriorated.
On the other hand, since toner is generally charged particles, its charged state is affected by an external electric field. The susceptibility to the influence of an external electric field can be expressed by the dielectric property of the toner, particularly the magnitude of the dielectric loss tangent (tan δ). The larger the dielectric loss tangent of the toner, the more the charged state of the toner is affected by the external electric field. Easy to receive. In the transfer process, a transfer electric field is applied to the toner. Here, when the dielectric loss tangent of the toner is large, the charge amount of the toner is changed (decreased) by the transfer electric field, and the toner is scattered. Furthermore, the toner charge amount distribution is further disturbed by the transfer electric field that wraps around the toner, and as a result, the toner scattering is further deteriorated.

  Here, by controlling the toner so that the dielectric loss tangent of the toner is not increased, the influence of the transfer electric field on the toner charge amount can be reduced. Furthermore, the transfer electric field that wraps around the toner is hardly affected. Therefore, even when the surface resistivity of the intermediate transfer belt is relatively low, the toner does not scatter and a good output image is obtained. It is thought that can be obtained. Considering this point, when the relationship between the surface resistivity of the intermediate transfer belt and the electrostatic tangent of the toner is experimentally examined for the output image, the above formulas (1), (2), and ( By satisfying all the conditions represented by 3), an image forming apparatus capable of obtaining a good output image can be obtained by suppressing image scattering due to toner scattering and transfer failure even in long-term repeated image output. I found out that

  According to the present invention, it is possible to provide an image forming apparatus capable of obtaining a satisfactory output image by suppressing image scattering due to toner scattering and transfer failure even in long-term repeated image output.

Hereinafter, the image forming apparatus of the present invention will be described in detail.
The present invention is particularly limited as long as it is an image forming apparatus using an intermediate transfer system having an image carrier, a charging unit, an exposure unit, a developing unit, a primary transfer unit, and a secondary transfer unit and using an intermediate transfer unit. It is not a thing. The image forming apparatus of the present invention is, for example, a monocolor image forming apparatus having only a single color toner in the developing device, or a tandem system in which a plurality of image holding bodies each having a developing device for each color are arranged in series in the process direction Or a full color image forming apparatus or the like.
In the image forming apparatus of the present invention, it is preferable that an intermediate transfer belt is provided as an intermediate transfer member from the viewpoint of the degree of freedom of arrangement of the image carrier and each means and the speed of image output.

In the present invention, the common logarithm Log (R) (logΩ / □) of the surface resistivity of the intermediate transfer member and the dielectric loss tangent tan δ at 1 kHz of the toner are represented by the following equations (1), (2), and (3): ) Must be satisfied.
0 ≦ Log (R) −Log (6.0 × 10 ¹¹ × tan δ) (1)
9.2 ≦ Log (R) ≦ 10.0 (2)
1.0 × 10 ⁻³ ≦ tan δ ≦ 10.0 × 10 ⁻³ (3)

First, in the present invention, the relationship between the common logarithm Log (R) of the surface resistivity of the intermediate transfer member and the dielectric loss tangent tan δ needs to satisfy the above formula (1).
By satisfying the above formula (1), it is possible to maintain the charging characteristics of the toner and suppress the change in the surface resistance of the intermediate transfer member over a long period of use, and provide a good output image over a long period of time.

Further, the common logarithm value Log (R) of the surface resistivity of the intermediate transfer member is required to be 9.2 logΩ / □ or more and 10.0 logΩ / □ or less, and the ability of the intermediate transfer member to hold toner and image output From the viewpoint of preventing a decrease in surface resistivity due to peeling discharge generated between the medium and the medium, it is preferably 9.3 logΩ / □ or more and 9.6 logΩ / □ or less.
When Log (R) is less than 9.2 logΩ / □, the toner image transferred onto the intermediate transfer member cannot be held, and the image is disturbed. Further, if it exceeds 10.0 log Ω / □, the surface of the intermediate transfer member is altered by peeling discharge generated between the image output medium and the surface resistivity is lowered, so that toner scattering occurs in the transfer process. The output image will be deteriorated.

Further, the dielectric loss tangent tan δ at 1 kHz of the toner needs to be 1.0 × 10 ⁻³ or more and 10.0 × 10 ⁻³ or less, and from the viewpoint of further improving the toner charge retention, 1.0 × It is preferably 10 ⁻³ or more and 7.0 × 10 ⁻³ or less.
If tan δ is less than 1.0 × 10 ^−3, it is necessary to disperse the colorant very finely in the toner, and it takes a lot of time and cost, making it difficult to manufacture, and 10.0 × 10 ^If it exceeds ^-3 , the toner chargeability will be lowered, resulting in a transfer failure and deterioration of the output image.

The “dielectric loss tangent (tan δ)” in the present invention is represented by the ratio of the real part ε ′ to the imaginary part ε ″ in the complex permittivity ε = ε′−iε ″ (i is an imaginary unit), and the dielectric tangent. (Tan δ) = ε ″ / ε ′. For example, the dielectric loss tangent (tan δ) is obtained by subjecting 5 g of toner to be measured to pellet molding (diameter 50 mm) using a pressure molding machine, and an LCR meter (LCR meter 6440A type: (Toyo Technica Co., Ltd.) can be obtained by measuring under the conditions of a frequency of 1 kHz and a voltage of 5V.
Further, the surface resistivity of the intermediate transfer member (intermediate transfer belt) in the present invention is determined by using JIS K6911 (1995) using a circular electrode (for example, Hirester IP “HR Probe”: manufactured by Mitsubishi Yuka Co., Ltd.). be able to.

The image forming apparatus of the present invention will be described below with reference to FIG. Here, FIG. 1 is a schematic view showing an example of the configuration of a full-color image forming apparatus provided with an intermediate transfer belt as an intermediate transfer member.
In FIG. 1, charging devices (charging means) 102a to 102d, image exposure devices (exposure means) 114a to 114d, around an image holding body 101a to 101d made of an electrophotographic photosensitive member, sequentially along the rotation direction. Developing devices (developing units) 103a to 103d, primary transfer rolls (primary transfer units) 105a to 105d, and image carrier cleaning devices 104a to 104d are arranged. An intermediate transfer belt (intermediate transfer member) 107 that moves in the direction of the arrow between the image carriers 101a to 101d and the primary transfer rolls 105a to 105d while contacting the surfaces of the image carriers 101a to 101d is tensioned. It is stretched by rolls 106a to 106d, a backup roll 108, and a drive roll 112.

  Further, an intermediate transfer belt cleaning device 111 is disposed so as to contact the intermediate transfer belt 107. Further, a secondary transfer roll (secondary transfer means) 109 is disposed at a position facing the backup roll 108 via the intermediate transfer belt 107, and the intermediate transfer belt 107 and the secondary transfer belt 107 are in contact with the surface of the intermediate transfer belt 107. The image output medium 113 moves in the direction of the arrow between the transfer roll 109 and then passes through the fixing device 110.

  A portion where the primary transfer rolls 105a to 105d are pressed against the image carriers 101a to 101d via the intermediate transfer belt 107 serves as a primary transfer unit, and the primary transfer rollers 105a to 105d are primary between the image carriers 101a to 101d and the primary transfer rollers 105a to 105d. A transfer voltage is applied. Further, a portion where the secondary transfer roll 109 is pressed against the backup roll 108 via the intermediate transfer belt 107 becomes a secondary transfer portion, and a secondary transfer voltage is applied between the secondary transfer roll 109 and the backup roll 108. The

  In the full-color image forming apparatus shown in FIG. 1, after the surface of the image carrier 101a rotating in the direction of the arrow is uniformly charged by the charging device 102a, the first color electrostatic latent image is captured by the image exposure device 114a such as laser light. An image is formed. The formed electrostatic latent image is visualized as a toner image by the developing device 103a containing toner corresponding to the color. The toner image is primary transferred electrostatically onto the intermediate transfer belt 107 by the primary transfer roll 105a when passing through the primary transfer portion. Thereafter, in the same manner, the toner images of the second color, the third color, and the fourth color are primarily transferred onto the intermediate transfer belt 107 holding the toner image of the first color so that they are sequentially superimposed, and finally the full color. Multiple toner images are obtained. The developing devices 103a to 103d accommodate toners (for example, yellow, magenta, cyan, and black) corresponding to the electrostatic latent images of the respective colors.

  The multiple toner images formed on the intermediate transfer belt 107 are electrostatically collectively transferred to the image output medium 113 when passing through the secondary transfer portion. The image output medium 113 to which the toner image has been transferred is conveyed to the fixing device 110, subjected to a fixing process, and then discharged outside the apparatus.

Residual toner is removed from the image carriers 101a to 101d after the primary transfer by the image carrier cleaning devices 104a to 104d.
Further, the intermediate transfer belt 107 after the secondary transfer has the residual toner removed by the intermediate transfer belt cleaning device 111 to prepare for the next image creation process.

  Note that the image forming apparatus of the present invention may include a static eliminator in order to remove residual potential remaining on the surfaces of the image carriers 101a to 101d after the primary transfer.

In the image forming apparatus of the present invention, the process speed is preferably 50 mm / s or more and 500 mm / s or less, and preferably 50 mm / s or more and 400 mm / s or less.
Within this range, the prevention of output image degradation caused by a decrease in the surface resistivity of the intermediate transfer member due to the peeling discharge between the surface of the intermediate transfer member and the image output medium, and image output speed should be suitably achieved. Is possible.
The process speed represents the distance that the surface of the intermediate transfer member rubs against the image carrier per unit time.

The intermediate transfer belt used in the image forming apparatus of the present invention will be described in detail.
The intermediate transfer belt in the present invention may be a single layer or a multilayer structure. However, in the case of a multilayer structure, there is a problem that the surface layer is worn over time due to peeling between layers, and further from the viewpoint of productivity and manufacturing cost. Even if it sees, the thing of a single layer structure is used preferably.

Examples of the material of the intermediate transfer belt having a single layer structure include polycarbonate resin, polyvinylidene fluoride resin, polyalkylene phthalate resin, polycarbonate / polyalkylene phthalate blend material, thermoplastic resin such as ethylene tetrafluoroethylene copolymer, A material obtained by dissolving or dispersing a conductive agent in a thermosetting resin such as polyimide, a copolymer of polyimide and polyamide, or the like is used.
Examples of the conductive agent include conductive particles such as carbon black, graphite, aluminum, nickel, copper, tin oxide, zinc oxide, titanium oxide, and potassium titanate, and organic conductive substances such as polyaniline and polythiophene. .
Among them, an intermediate transfer belt (main component means that the polyimide resin content in the intermediate transfer belt exceeds 50% by mass) containing polyimide resin and conductive particles such as carbon black are dispersed ( The polyimide belt is suitably used hereinafter because it is excellent in mechanical strength, high elastic modulus, and excellent creep resistance.

  The film thickness of the intermediate transfer belt is preferably 30 to 200 μm, more preferably 40 to 150 μm, from the viewpoint of maintaining the shape such as dimensional accuracy even in repeated image output.

  As a method for producing an intermediate transfer belt mainly composed of a polyimide resin and dispersed with conductive particles such as carbon black, a polyimide precursor solution is applied in an axial direction to the outer peripheral surface or inner peripheral surface of a cylindrical molded tube, After forming a polyimide precursor coating film, a method of forming a polyimide film by imide conversion by heating and baking is suitably used. The method of application is not limited as long as the polyimide precursor solution is applied in a direction parallel to the axis of the cylindrical molded tube. Specifically, the cylindrical molded tube is immersed in the polyimide precursor solution. Examples include a dip coating method for pulling up, or a method in which a polyimide precursor solution is poured axially into the inner peripheral surface of a cylindrical molded tube.

  In addition, prior to the application to the cylindrical tube, the polyimide precursor solution has conductive particles such as carbon black dispersed therein. As a dispersion method, known methods such as a jet mill, a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker can be used.

Here, in the case of an intermediate transfer belt containing polyimide as a main component and conductive particles such as carbon black dispersed, in order to satisfy the formula (2), the above-described dispersion method is used, and a polyimide precursor solution. It is important to adjust the dispersion state of the conductive particles therein.
That is, when the conductive particles are excessively finely dispersed, the ratio of the conductive particles forming the conductive path on the surface of the intermediate transfer belt obtained by imide conversion is significantly reduced, so that the surface resistivity is increased. It becomes difficult to satisfy the formula (2). Also, in a state where the dispersion state is poor and a large amount of conductive particles are aggregated, conversely, the conductive particles aggregated on the surface of the intermediate transfer belt form a large number of conductive paths. It becomes difficult to satisfy Expression (2). Furthermore, when the dispersion state of the conductive particles is remarkably bad, a large number of conductive paths are formed not only on the surface of the intermediate transfer belt but also in the inside thereof. Since in-plane unevenness deteriorates, it becomes impossible to maintain good transferability.

As described above, in order to control the surface resistivity of an intermediate transfer member such as an intermediate transfer belt so as to satisfy the formula (2), a conductive agent-containing layer (surface) that constitutes a surface onto which a toner image is transferred A method of adjusting the dispersion state of the conductive particles in the layer) is used.
Moreover, as another method, the method of surface-treating the surface of the electroconductive particle in a electrically conductive agent content layer (surface layer) and adjusting a conductive state is mentioned. Examples of the surface treatment agent include a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, and a surfactant.

The toner used in the image forming apparatus according to the present invention includes, for example, a binder resin and a colorant.
Examples of the binder resin include homopolymers and copolymers such as styrenes, monoolefins, vinyl esters, α-methylene aliphatic monocarboxylic acid esters, vinyl ethers, and vinyl ketones. Typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer. Examples thereof include coalescence, polyethylene, and polypropylene. Furthermore, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax, and the like can be given.

Coloring agents include magnetic powders such as magnetite and ferrite, carbon black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, and lamp black. Rose Bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3 is a typical example.
As the colorant for the toner in the present invention, carbon black is preferably used from the viewpoint of easy control of the dielectric loss tangent (tan δ).

The toner may be internally added or externally added with known additives such as a charge control agent, a release agent, and other inorganic particles.
Typical examples of the release agent include low molecular polyethylene, low molecular polypropylene, Fischer-Tropsch wax, montan wax, carnauba wax, rice wax, and candelilla wax.
Known charge control agents can be used, but charge control agents such as azo-based metal complex compounds, metal complex compounds of salicylic acid, and resin types containing polar groups can be used.
As other inorganic particles, small-diameter inorganic particles having an average primary particle size of 40 nm or less are used for the purpose of powder flowability, charge control, etc., and if necessary, larger diameters are used to reduce adhesion. These inorganic or organic particles may be used in combination. As these other inorganic particles, known ones can be used.
In addition, the surface treatment of the small-diameter inorganic particles is effective because the dispersibility becomes high and the effect of increasing the powder fluidity increases.

As a method for producing the toner used in the present invention, a polymerization method such as an emulsion polymerization aggregation method or a dissolution suspension method is preferably used because high shape controllability can be obtained. In addition, a manufacturing method may be performed in which the toner obtained by these methods is used as a core, and agglomerated particles are further adhered and heat-fused to have a core-shell structure.
In addition, when adding an external additive, it can manufacture by mixing a toner and an external additive with a Henschel mixer or a V blender. Further, when the toner is manufactured by a wet method, it can be externally added by a wet method.

The dielectric loss tangent (tan δ) of the toner used in the present invention needs to satisfy the above formula (3). In order to adjust the dielectric loss tangent (tan δ) of the toner, it is important to control the dispersion state of the colorant such as carbon black in the toner.
That is, when the dispersion state of the colorant in the toner is poor, the dielectric loss tangent (tan δ) increases. When the dispersion state in the toner is good, the dielectric loss tangent (tan δ) decreases.
Here, as a method for dispersing the colorant, known methods such as a jet mill, a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker can be used. Since it is excellent, it is particularly preferably used.

The primary transfer roll used in the image forming apparatus of the present invention may be either a single layer or a multilayer. For example, in the case of a single layer structure, it is composed of a roll in which an appropriate amount of conductive particles such as carbon black is blended in foamed or non-foamed silicone rubber, urethane rubber, EPDM or the like. The resistance value is preferably in the range of 10 ⁵ to 10 ¹⁰ Ω. A voltage of 1.0 to 5.5 kV is applied to the primary transfer roll, and the toner is transferred by an electric field generated between the primary transfer roll and the image carrier.

The layer structure of the secondary transfer roll used in the image forming apparatus of the present invention is not particularly limited. For example, in the case of a three-layer structure, the layer structure includes a core layer, an intermediate layer, and a coating layer covering the surface. Become. The core layer is a foamed material such as silicone rubber, urethane rubber, EPDM or the like in which conductive particles are dispersed, and the intermediate layer is composed of these non-foamed materials. Examples of the material for the coating layer include tetrafluoroethylene-hexafluoropropylene copolymer and perfluoroalkoxy resin. The volume resistivity of the secondary transfer roll is preferably 10 ⁷ Ωcm or less. It is also possible to have a two-layer structure excluding the intermediate layer.

The backup roll used in the image forming apparatus of the present invention forms the counter electrode of the secondary transfer roll. The layer structure of the backup roll may be either a single layer or a multilayer. For example, in the case of a single layer structure, it is composed of a roll in which an appropriate amount of conductive particles such as carbon black is blended in silicone rubber, urethane rubber, EPDM or the like. In the case of a two-layer structure, it is composed of a roll in which the outer peripheral surface of the elastic layer composed of the rubber material as described above is covered with a high resistance layer. The surface resistivity of the backup roll is preferably in the range of 10 ⁷ to 10 ¹¹ Ω / □.

  In the image forming apparatus of the present invention, a voltage of 1 to 6 kV is usually applied between the shafts of the backup roll and the secondary transfer roll. Moreover, it can replace with the voltage application to the shaft of a backup roll, and can also apply a voltage between the electroconductive electrode member which the backup roll pressed, and the secondary transfer roll. Examples of the electrode member include a metal roll, a conductive rubber roll, a conductive brush, a metal plate, and a conductive resin plate.

As the image carrier used in the image forming apparatus of the present invention, conventionally known electrophotographic photosensitive members can be widely applied. As the electrophotographic photoreceptor, an inorganic photoreceptor having a photosensitive layer made of an inorganic material, an organic photoreceptor having a photosensitive layer made of an organic material, or the like can be used. In organic photoreceptors, a function-separated organic photoreceptor in which a charge generation layer that generates charges upon exposure and a charge transport layer that transports charges are stacked, and a layer that has the same function to generate charges and to transport charges Is preferably used. In addition, as the inorganic photoconductor, a photoconductive layer composed of amorphous silicon is preferably used.
Further, the shape of the electrophotographic photosensitive member is not particularly limited, and may be, for example, a cylindrical drum shape, a sheet shape, or a plate shape.

The charging device (charging means) used in the image forming apparatus of the present invention is not particularly limited. For example, a contact type charger or corona using a conductive or semiconductive roller, brush, film, rubber blade or the like. Conventionally known chargers such as a scorotron charger and a corotron charger using discharge can be widely applied. Among these, a contact charger that generates less ozone and can perform efficient charging is preferable.
The charging means normally applies a direct current to the electrophotographic photosensitive member, but an alternating current may be further superimposed and applied.

  The image exposure apparatus (exposure means) used in the image forming apparatus of the present invention is not particularly limited. For example, a light source such as a semiconductor laser light, LED light, or liquid crystal shutter light on the surface of the electrophotographic photosensitive member, or these Conventionally known exposure apparatuses such as an optical system apparatus that can perform exposure in a desired image form from a light source through a polygon mirror can be widely applied.

  The developing device (developing means) used in the image forming apparatus of the present invention can be appropriately selected according to the purpose. For example, a one-component developer or a two-component developer is used as a brush, a roller, or the like. Examples include known developing devices that are used in contact or non-contact for development.

  The fixing device (fixing means) used in the image forming apparatus of the present invention is not particularly limited. For example, conventionally known fixing devices such as a heat roller fixing device, a pressure roller fixing device, and a flash fixing device are widely applied. Can do.

  As described above, the image forming apparatus using the intermediate transfer belt has been described as an example of the image forming apparatus of the present invention. However, the image forming apparatus is not limited to this example, and the image using the intermediate transfer drum as the intermediate transfer member. It may be a forming device.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples.

[Preparation of intermediate transfer belt]
(Preparation of intermediate transfer belt 1)
To 100 parts by mass of an NMP solution of polyamic acid consisting of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 4,4′-diaminodiphenyl ether (solid content after imide conversion is 18% by mass) 9 parts by mass of carbon black (Special Black 4: manufactured by Degussa) was added and dispersed at a pressure of 180 MPa using a jet mill disperser (Geanus PY [minimum cross-sectional area of collision part 0.032 mm ² ]: manufactured by Genus). The unit part was passed twice to disperse and mix.

  An NMP solution of polyamic acid composed of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 4,4′-diaminodiphenyl ether (solid state after imide conversion) with respect to 100 parts by mass of the obtained dispersion. A carbon black-dispersed polyimide precursor solution was prepared by adding 70 parts by mass of a fraction (18% by mass) and mixing and stirring using a planetary mixer (Aiko mixer manufactured by Aikosha Seisakusho).

Using the obtained carbon black-dispersed polyimide precursor solution, a polyimide precursor coating film was produced by a push-up annular coating method as shown in FIG.
An aluminum cylinder having an outer diameter of 364.5 mm and a length of 650 mm was prepared as a cylindrical molded tube. The aluminum cylinder is an aluminum tube having an outer diameter of 377 mm and a length of 700 mm, heated at 350 ° C. for 10 minutes and naturally cooled, then the surface is cut to an outer diameter of 364.5 m, The surface is roughened to Ra: 1.5 μm by blasting with spherical glass particles. A silicone mold release agent (trade name: KS700, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the surface of this aluminum cylinder, and baked at 300 ° C. for 1 hour to produce a cylindrical molded tube 201.

On the other hand, an annular body 205 having an outer diameter of 445 mm, a minimum inner diameter of 366 mm, and a height of 50 mm was manufactured. The inner wall is inclined.
The cylindrical forming tube 201 (aluminum cylindrical body) was passed through an annular coating tank 203 having an inner diameter of 370 mm and a height of 150 mm, to which a polyethylene annular sealing material 206 having a center hole having an inner diameter of 360 mm was attached. And the said carbon black dispersion | distribution polyimide precursor solution 202 was put into the cyclic | annular application | coating tank 203, the cyclic | annular body 205 was arrange | positioned, the cylindrical shaping | molding pipe | tube 201 was raised at 1.0 m / min, and it apply | coated. As a result, a polyimide precursor coating 204 having a wet film thickness of about 420 μm was formed on the surface of the cylindrical tube 201.

Next, the cylindrical molded tube 201 on which the polyimide precursor coating film 204 was formed was horizontal and heated and dried at 170 ° C. for 60 minutes while rotating at 6 rpm. Then, it heated at 360 degreeC for 30 minutes, imide conversion was carried out, and the polyimide resin film in which carbon black was disperse | distributed was formed.
Thereafter, when the temperature of the cylindrical molded tube 201 was cooled to room temperature, the polyimide resin film A was peeled from the cylindrical molded tube 201.

The obtained polyimide resin film A was cut into a width of 369 mm, and the intermediate transfer belt 1 was obtained.
The average film thickness of the intermediate transfer belt 1 was measured and found to be 75 μm.
Here, the film thickness was measured using an eddy current film thickness measuring instrument (Isoscope MP30, manufactured by Fisher Instruments, probe: EAT3.3). Measurement points were placed every 30 mm in both the width direction and the circumferential direction of the belt, and the average value of all points was taken as the average film thickness of the belt. Further, the difference between the maximum value and the minimum value of the film thickness in one measurement point row in the belt width direction is defined as the displacement in the width direction, and the largest of all the displacements in the width direction is the width direction representative of the belt. The film thickness was changed.

The average surface resistivity of the obtained intermediate transfer belt 1 was measured and found to be 9.23 LogΩ / □.
Here, the average surface resistivity was measured by placing measurement points every 50 mm in both the width direction and the circumferential direction of the belt, and the average value of all points was defined as the average surface resistivity. Further, the surface resistivity was measured according to JIS K6991 using a Hiresta IP and HR probe manufactured by Mitsubishi Yuka Co., Ltd.

(Preparation of intermediate transfer belt 2)
In the production of the intermediate transfer belt 1, dispersion was performed using a jet mill disperser (Geanus PY [minimum cross-sectional area of collision part 0.032 mm ² ]: manufactured by Genus Co., Ltd.), the pressure was 200 MPa, and the number of passes of the dispersion unit part was 2. The intermediate transfer belt 2 was obtained in the same manner as in the production of the intermediate transfer belt 1 except that the rotation was performed.
When the average film thickness of the obtained intermediate transfer belt 2 was measured, it was 77 μm. Moreover, when the average surface resistivity was measured, it was 9.45 LogΩ / □.

(Preparation of intermediate transfer belt 3)
In the production of the intermediate transfer belt 1, dispersion was performed using a jet mill disperser (Geanus PY [minimum cross-sectional area of collision part: 0.032 mm ² ]: manufactured by Genus Co., Ltd.), the pressure was 200 MPa, and the number of passes through the dispersion unit was 3. The intermediate transfer belt 3 was obtained in the same manner as in the production of the intermediate transfer belt 1 except that the rotation was performed.
The average film thickness of the obtained intermediate transfer belt 3 was measured and found to be 73 μm. Moreover, when the average surface resistivity was measured, it was 9.67 LogΩ / □.

(Preparation of intermediate transfer belt 4)
In the production of the intermediate transfer belt 1, dispersion was performed using a jet mill disperser (Geanus PY [minimum cross-sectional area of collision part: 0.032 mm ² ]: manufactured by Genus Co., Ltd.), the pressure was 200 MPa, and the number of passes through the dispersion unit was 4. The intermediate transfer belt 4 was obtained in the same manner as the production of the intermediate transfer belt 1 except that the number of rotations was changed.
The average film thickness of the obtained intermediate transfer belt 4 was measured and found to be 75 μm. Further, the average surface resistivity was measured and found to be 9.92 LogΩ / □.

(Preparation of intermediate transfer belt 5)
In the production of the intermediate transfer belt 1, dispersion is performed using a jet mill disperser (Geanus PY [minimum cross-sectional area of collision part: 0.032 mm ² ]: manufactured by Genus Co., Ltd.), the pressure is 160 MPa, and the number of passes through the dispersion unit is 2. The intermediate transfer belt 5 was obtained in the same manner as the production of the intermediate transfer belt 1 except that the number of rotations was changed.
The average film thickness of the obtained intermediate transfer belt 5 was measured and found to be 76 μm. Further, the average surface resistivity was measured and found to be 9.18 LogΩ / □.

(Preparation of intermediate transfer belt 6)
In the production of the intermediate transfer belt 1, dispersion was performed using a jet mill disperser (Geanus PY [minimum cross-sectional area of collision part: 0.032 mm ² ]: manufactured by Genus Co., Ltd.), the pressure was 150 MPa, and the number of passes through the dispersion unit was 2. The intermediate transfer belt 6 was obtained in the same manner as the production of the intermediate transfer belt 1 except that the rotation was performed.
The average film thickness of the obtained intermediate transfer belt 6 was measured and found to be 77 μm. Further, the average surface resistivity was measured and found to be 9.02 LogΩ / □.

(Preparation of intermediate transfer belt 7)
In the production of the intermediate transfer belt 1, dispersion was performed using a jet mill disperser (Geanus PY [minimum cross-sectional area of collision part: 0.032 mm ² ]: manufactured by Genus Co., Ltd.), the pressure was 200 MPa, and the number of passes through the dispersion unit was 5. The intermediate transfer belt 7 was obtained in the same manner as in the production of the intermediate transfer belt 1 except that the rotation was performed.
The average film thickness of the obtained intermediate transfer belt 7 was measured and found to be 74 μm. Further, the average surface resistivity was measured and found to be 10.40 LogΩ / □.

(Preparation of intermediate transfer belt 8)
In the production of the intermediate transfer belt 1, dispersion was performed using a jet mill disperser (Geanus PY [minimum cross-sectional area of collision part: 0.032 mm ² ]: manufactured by Genus Co., Ltd.), the pressure was 200 MPa, and the number of passes through the dispersion unit was 8. The intermediate transfer belt 8 was obtained in the same manner as in the production of the intermediate transfer belt 1 except that the rotation was performed.
The average film thickness of the obtained intermediate transfer belt 8 was measured and found to be 72 μm. The average surface resistivity was measured and found to be 11.53 LogΩ / □.

(Preparation of intermediate transfer belt 9)
In the production of the intermediate transfer belt 1, dispersion was performed using a jet mill disperser (Geanus PY [minimum cross-sectional area of collision part: 0.032 mm ² ]: manufactured by Genus Co., Ltd.), the pressure was 220 MPa, and the number of passes through the dispersion unit was 8. The intermediate transfer belt 9 was obtained in the same manner as in the production of the intermediate transfer belt 1 except that the rotation was performed.
The average film thickness of the obtained intermediate transfer belt 9 was measured and found to be 78 μm. Further, the average surface resistivity was measured and found to be 12.01 LogΩ / □.

[Production of toner]
(Preparation of Colorant Dispersion 1)
Carbon black (conductive particles) pigment (Mogal L: Cabot Corporation) 40 parts by mass Anionic surfactant (Neogen RK: Daiichi Kogyo Seiyaku Co., Ltd.) 6 parts by mass ion-exchanged water 54 parts by mass After mixing and mixing and dispersing with Ultratarax T50 (manufactured by IKA) for 10 minutes, the mixture was dispersed and dispersed for 100 minutes with a rotary rotor type dispersing machine Cavitron CD1010 (manufactured by Taihei Koki Co., Ltd.) to obtain a colorant dispersion 1. When the particle size of carbon black in the obtained dispersion was measured using Microtrac UPA (manufactured by HONEYWELL), the D50 particle size was 116 nm.

(Preparation of colorant dispersion 2)
In the preparation of the colorant dispersion 1, the colorant was prepared in the same manner as in the preparation of the colorant dispersion 1, except that the mixing and dispersing time in the rotary rotor type disperser Cavitron CD1010 (manufactured by Taihei Koki Co., Ltd.) was 120 minutes. Dispersion 2 was obtained. When the particle size of carbon black in the obtained dispersion was measured using Microtrac UPA (manufactured by HONEYWELL), the D50 particle size was 113 nm.

(Preparation of Colorant Dispersion 3)
In the production of the colorant dispersion 1, the colorant was prepared in the same manner as in the production of the colorant dispersion 1, except that the mixing and dispersing time in the rotary rotor type dispersion machine Cavitron CD1010 (manufactured by Taihei Koki Co., Ltd.) was 55 minutes. Dispersion 3 was obtained. When the particle size of carbon black in the obtained dispersion was measured using Microtrac UPA (manufactured by HONEYWELL), the D50 particle size was 125 nm.

(Preparation of colorant dispersion 4)
In the production of the colorant dispersion 1, the colorant was prepared in the same manner as in the production of the colorant dispersion 1 except that the mixing and dispersion time in the rotary rotor type dispersion machine Cavitron CD1010 (manufactured by Taihei Koki Co., Ltd.) was 20 minutes. Dispersion 4 was obtained. When the particle size of carbon black in the obtained dispersion was measured using Microtrac UPA (manufactured by HONEYWELL), the D50 particle size was 141 nm.

(Preparation of colorant dispersion 5)
In the production of the colorant dispersion 1, the colorant was prepared in the same manner as in the production of the colorant dispersion 1, except that the mixing and dispersing time in the rotary rotor type dispersing machine Cavitron CD1010 (manufactured by Taihei Koki Co., Ltd.) was 15 minutes. Dispersion 5 was obtained. When the particle size of carbon black in the obtained dispersion was measured using Microtrac UPA (manufactured by HONEYWELL), the D50 particle size was 146 nm.

(Preparation of colorant dispersion 6)
In the preparation of the colorant dispersion 1, the colorant was prepared in the same manner as in the preparation of the colorant dispersion 1, except that the mixing and dispersing time in the rotary rotor type dispersing machine Cavitron CD1010 (manufactured by Taihei Koki Co., Ltd.) was 10 minutes. Dispersion 6 was obtained. When the particle size of carbon black in the obtained dispersion was measured using Microtrac UPA (manufactured by HONEYWELL), the D50 particle size was 154 nm.

(Preparation of Colorant Dispersion 7)
In the production of the colorant dispersion 1, the colorant was prepared in the same manner as in the production of the colorant dispersion 1, except that the mixing and dispersing time in the rotary rotor type dispersing machine Cavitron CD1010 (manufactured by Taihei Koki Co., Ltd.) was 5 minutes. Dispersion 7 was obtained. The particle diameter of carbon black in the obtained dispersion was measured using Microtrac UPA (manufactured by HONEYWELL), and the D50 particle diameter was 167 nm.

(Preparation of Toner 1)
Resin dispersion [styrene-butyl acrylate-acrylic acid copolymer (copolymer molar ratio 82: 18: 2), Mw = 23,000, Tg = 65 ° C., particle size 170 μm] (40% by mass dispersion) 260 parts by weight-colorant dispersion 1 15 parts by weight-mold release dispersion (HNP0190: manufactured by Nippon Seiwa Co., Ltd.) (30% by weight dispersion) 20 parts by weight-polyaluminum hydroxide (Pho2S: manufactured by Asada Chemical Co., Ltd.) 0 .5 parts by mass

The above components were mixed and dispersed in a round stainless steel flask using Ultratarrax T50 (manufactured by IKA), and then heated to 55 ° C. while stirring the flask in an oil bath for heating. After maintaining at 55 ° C. for 30 minutes, the particle size was measured with a Coulter counter (Multisizer 2: manufactured by Coulter), and it was confirmed that aggregate particles of 4.5 μm were formed. Further, the temperature of the heating oil bath was raised and held at 65 ° C. for 1 hour. When the particle size was measured, it was confirmed that 5.3 μm aggregate particles were generated. Then, after adding 3 parts by mass of an anionic surfactant (Neogen RK: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) to the dispersion containing the aggregate particles, the stainless steel flask is sealed and stirred using a magnetic seal. While continuing, it was heated to 97 ° C. and held for 4 hours. After cooling, the volume average particle diameter was measured with a Coulter counter and confirmed to be 5.4 μm.
Toner particles were filtered off from the prepared toner particle-containing liquid, washed with a sodium hydroxide solution having a pH of 10.0, and then washed with ion-exchanged water three times. Thereafter, the toner particles are freeze-dried for 6 hours and then vacuum-dried for 24 hours, sieved to a volume average particle size of 5.4 μm, a GSDv (average volume particle size distribution) of 1.25, and a shape factor of 133. Dry toner particles 1 were obtained.

Toner obtained by adding 1.5 parts by weight of hydrophobic silica (TS720: manufactured by Cabot) to 50 parts by weight of the obtained dry toner particles, blending with a sample mill, and externally adding the hydrophobic silica 1 was obtained.
5 g of the obtained toner 1 was weighed, pellet-molded with a pressure molding machine (diameter 50 mm), and measured with an LCR meter (LCR meter 6440A type: manufactured by Toyo Technica Co., Ltd.) at a frequency of 1 kHz and a voltage of 5V. As a result, the dielectric loss tangent (tan δ) was 2.59 × 10 ⁻³ .

The average shape factor of the toner particles was determined as follows. First, for 1000 toner particles, an image of the toner particles was taken from an optical microscope into an image analyzer (LUZEX III: manufactured by Nireco Corporation), and the maximum length and area of the photographed image of the toner particles were determined. Next, the shape factor [(maximum length of particle) ² × π × 100 / (area × 4)] is obtained for each toner particle from the obtained maximum length and area, and the average value thereof is calculated as the average shape factor (ML2 / A).

(Preparation of Toner 2)
Dry toner particles 2 were obtained in the same manner as in the preparation of the toner 1 except that the colorant dispersion 2 was used instead of the colorant dispersion 1 in the preparation of the toner 1. When the obtained dry toner particles 2 were measured, the volume average particle diameter was 5.8 μm, GSDv was 1.28, and the shape factor was 132. Toner obtained by adding 1.5 parts by weight of hydrophobic silica (TS720: manufactured by Cabot Corporation) to 50 parts by weight of the obtained dry toner particles, blending with a sample mill, and externally adding the hydrophobic silica 2 was obtained.
5 g of the obtained toner 2 was weighed, pelleted with a pressure molding machine (diameter 50 mm), and measured with an LCR meter (LCR meter 6440A type: manufactured by Toyo Technica) under the conditions of a frequency of 1 kHz and a voltage of 5V. As a result, the dielectric loss tangent (tan δ) was 1.28 × 10 ⁻³ .

(Preparation of Toner 3)
Dry toner particles 3 were obtained in the same manner as in the preparation of the toner 1 except that the colorant dispersion 3 was used instead of the colorant dispersion 1 in the production of the toner 1. When the obtained dry toner particles 3 were measured, the volume average particle size was 5.6 μm, GSDv was 1.24, and the shape factor was 136. Toner obtained by adding 1.5 parts by weight of hydrophobic silica (TS720: manufactured by Cabot Corporation) to 50 parts by weight of the obtained dry toner particles, blending with a sample mill, and externally adding the hydrophobic silica 3 was obtained.
5 g of the obtained toner 3 was weighed, pelleted with a pressure molding machine (diameter 50 mm), and measured with an LCR meter (LCR meter 6440A type: manufactured by Toyo Technica Co., Ltd.) at a frequency of 1 kHz and a voltage of 5V. As a result, the dielectric loss tangent (tan δ) was 3.86 × 10 ⁻³ .

(Preparation of Toner 4)
Dry toner particles 4 were obtained in the same manner as in the preparation of the toner 1 except that the colorant dispersion 4 was used instead of the colorant dispersion 1 in the preparation of the toner 1. When the obtained dry toner particles 4 were measured, the volume average particle diameter was 5.2 μm, GSDv was 1.22, and the shape factor was 133. Toner obtained by adding 1.5 parts by weight of hydrophobic silica (TS720: manufactured by Cabot Corporation) to 50 parts by weight of the obtained dry toner particles, blending with a sample mill, and externally adding the hydrophobic silica 4 was obtained.
5 g of the obtained toner 4 was weighed, pelleted with a pressure molding machine (diameter 50 mm), and measured with a LCR meter (LCR meter 6440A type: manufactured by Toyo Technica Co., Ltd.) at a frequency of 1 kHz and a voltage of 5V. As a result, the dielectric loss tangent (tan δ) was 7.26 × 10 ⁻³ .

(Preparation of Toner 5)
Dry toner particles 5 were obtained in the same manner as in the preparation of the toner 1 except that the colorant dispersion 5 was used instead of the colorant dispersion 1 in the production of the toner 1. When the obtained dry toner particles 5 were measured, the volume average particle diameter was 5.9 μm, GSDv was 1.31, and the shape factor was 141. Toner obtained by adding 1.5 parts by weight of hydrophobic silica (TS720: manufactured by Cabot Corporation) to 50 parts by weight of the obtained dry toner particles, blending with a sample mill, and externally adding the hydrophobic silica 5 was obtained.
5 g of the obtained toner 5 was weighed, pelleted with a pressure molding machine (diameter 50 mm), and measured with a LCR meter (LCR meter 6440A type: manufactured by Toyo Technica Co., Ltd.) at a frequency of 1 kHz and a voltage of 5V. As a result, the dielectric loss tangent (tan δ) was 9.89 × 10 ⁻³ .

(Production of Toner 6)
Dry toner particles 6 were obtained in the same manner as in the preparation of the toner 1 except that the colorant dispersion 6 was used instead of the colorant dispersion 1 in the production of the toner 1. When the obtained dry toner particles 6 were measured, the volume average particle diameter was 6.0 μm, GSDv was 1.35, and the shape factor was 142. Toner obtained by adding 1.5 parts by weight of hydrophobic silica (TS720: manufactured by Cabot Corporation) to 50 parts by weight of the obtained dry toner particles, blending with a sample mill, and externally adding the hydrophobic silica 6 was obtained.
5 g of the obtained toner 6 was weighed, pelleted with a pressure molding machine (diameter 50 mm), and measured with a LCR meter (LCR meter 6440A type: manufactured by Toyo Technica Co., Ltd.) at a frequency of 1 kHz and a voltage of 5V. As a result, the dielectric loss tangent (tan δ) was 1.28 × 10 ⁻² .

(Preparation of Toner 7)
Dry toner particles 7 were obtained in the same manner as in the preparation of the toner 1 except that the colorant dispersion 7 was used instead of the colorant dispersion 1 in the production of the toner 1. When the obtained dry toner particles 7 were measured, the volume average particle diameter was 6.1 μm, GSDv was 1.31, and the shape factor was 140. Toner obtained by adding 1.5 parts by weight of hydrophobic silica (TS720: manufactured by Cabot Corporation) to 50 parts by weight of the obtained dry toner particles, blending with a sample mill, and externally adding the hydrophobic silica 6 was obtained.
5 g of the obtained toner 7 was measured, pellet-molded (diameter 50 mm) with a pressure molding machine, and measured with a LCR meter (LCR meter 6440A type: manufactured by Toyo Technica Co., Ltd.) at a frequency of 1 kHz and a voltage of 5V. As a result, the dielectric loss tangent (tan δ) was 1.83 × 10 ⁻² .

[Example 1]
The obtained intermediate transfer belt 1 and toner 1 were mounted on a full-color composite machine (DocuCentre C75550I: manufactured by Fuji Xerox Co., Ltd.). The toner 1 was mounted only on the black process cartridge, and the image was printed only in black to evaluate the image quality. For the image quality evaluation, A4 paper was used, and the initial image quality and the image quality after printing 100,000 sheets were used. The paper was printed with the A4 paper sideways, and the output pattern was black halftone (toner density 30%).
The results are shown in Table 1.

[Example 2]
In Example 1, evaluation was performed in the same manner as in Example 1 except that the intermediate transfer belt 2 was used instead of the intermediate transfer belt 1. The results are shown in Table 1.

Example 3
In Example 1, evaluation was performed in the same manner as in Example 1 except that the intermediate transfer belt 3 was used instead of the intermediate transfer belt 1. The results are shown in Table 1.

Example 4
In Example 1, evaluation was performed in the same manner as in Example 1 except that the intermediate transfer belt 4 was used instead of the intermediate transfer belt 1. The results are shown in Table 1.

Example 5
In Example 1, evaluation was performed in the same manner as in Example 1 except that the intermediate transfer belt 3 was used instead of the intermediate transfer belt 1 and the toner 2 was used instead of the toner 1. The results are shown in Table 1.

Example 6
In Example 1, evaluation was performed in the same manner as in Example 1 except that the intermediate transfer belt 3 was used instead of the intermediate transfer belt 1 and the toner 3 was used instead of the toner 1. The results are shown in Table 1.

Example 7
In Example 1, evaluation was performed in the same manner as in Example 1 except that the intermediate transfer belt 3 was used instead of the intermediate transfer belt 1 and the toner 4 was used instead of the toner 1. The results are shown in Table 1.

[Comparative Example 1]
In Example 1, evaluation was performed in the same manner as in Example 1 except that the intermediate transfer belt 3 was used instead of the intermediate transfer belt 1 and the toner 5 was used instead of the toner 1. The results are shown in Table 1.

[Comparative Example 2]
In Example 1, evaluation was performed in the same manner as in Example 1 except that the intermediate transfer belt 3 was used instead of the intermediate transfer belt 1 and the toner 6 was used instead of the toner 1. The results are shown in Table 1.

[Comparative Example 3]
In Example 1, evaluation was performed in the same manner as in Example 1 except that the intermediate transfer belt 3 was used instead of the intermediate transfer belt 1 and the toner 7 was used instead of the toner 1. The results are shown in Table 1.

[Comparative Example 4]
In Example 1, evaluation was performed in the same manner as in Example 1 except that the intermediate transfer belt 5 was used instead of the intermediate transfer belt 1 and the toner 2 was used instead of the toner 1. The results are shown in Table 1.

[Comparative Example 5]
In Example 1, evaluation was performed in the same manner as in Example 1 except that the intermediate transfer belt 6 was used instead of the intermediate transfer belt 1 and the toner 2 was used instead of the toner 1. The results are shown in Table 1.

[Comparative Example 6]
In Example 1, evaluation was performed in the same manner as in Example 1 except that the intermediate transfer belt 7 was used instead of the intermediate transfer belt 1. The results are shown in Table 1.

[Comparative Example 7]
In Example 1, evaluation was performed in the same manner as in Example 1 except that the intermediate transfer belt 8 was used instead of the intermediate transfer belt 1. The results are shown in Table 1.

[Comparative Example 8]
In Example 1, evaluation was performed in the same manner as in Example 1 except that the intermediate transfer belt 9 was used instead of the intermediate transfer belt 1. The results are shown in Table 1.

[Comparative Example 9]
In Example 1, evaluation was performed in the same manner as in Example 1 except that the intermediate transfer belt 4 was used instead of the intermediate transfer belt 1 and the toner 6 was used instead of the toner 1. The results are shown in Table 1.

As is apparent from Table 1, in Examples 1 to 6, good output images were obtained even at the initial stage and after printing 100,000 sheets. Further, in Example 7, an extremely slight image blur due to transfer failure occurred after printing 100,000 sheets, but the print quality was not significantly deteriorated.
In contrast, in Comparative Examples 1 to 3 and 9, fogging occurred due to poor toner charge maintenance in the initial and output images after 100,000 sheets were printed. In Comparative Examples 4 to 5, image disturbance due to toner scattering occurred in the initial and output images after 100,000 sheets were printed. Further, in Comparative Examples 6 to 8, a good output image was obtained in the initial stage, but after 100,000 sheets were printed, image disturbance and partial density unevenness occurred in the output image due to toner scattering.

1 is a schematic view showing a preferred embodiment of an image forming apparatus of the present invention. FIG. 3 is a schematic cross-sectional view showing an embodiment of a push-up annular coating device used for producing an intermediate transfer belt in the present invention.

Explanation of symbols

  101a to 101d ... image carrier, 102a to 102d ... charging device, 103a to 103d ... developing device, 104a to 104d ... image carrier cleaning device, 105a to 105d ... primary transfer roll, 106a to 106d ... tension roll, 107 ... intermediate Transfer belt, 108 ... backup roll, 109 ... secondary transfer roll, 110 ... fixing device, 111 ... intermediate transfer belt cleaning device, 112 ... drive roll, 113 ... image output medium, 114 ... image exposure device, 201 ... cylindrical forming tube 202 ... polyimide precursor solution, 203 ... annular coating tank, 204 ... polyimide precursor coating film, 205 ... annular body, 206 ... annular sealing material

Claims (4)

An image carrier, a charging unit for charging the image carrier, an exposure unit for forming an electrostatic latent image on the image carrier charged by the charging unit, and an electrostatic latent image on the image carrier. Developing means for developing with toner to form a toner image, primary transfer means for transferring the toner image to an intermediate transfer member, and secondary for transferring the toner image transferred to the intermediate transfer member to an image output medium And an image forming apparatus characterized by satisfying all of the following formulas (1), (2), and (3).
0 ≦ Log (R) −Log (6.0 × 10 ¹¹ × tan δ) (1)
9.2 ≦ Log (R) ≦ 10.0 (2)
1.0 × 10 ⁻³ ≦ tan δ ≦ 10.0 × 10 ⁻³ (3)
[In the above formulas (1) to (3), Log (R) represents a common logarithm value (logΩ / □) of the surface resistivity of the intermediate transfer member, and tan δ represents a dielectric loss tangent of the toner at 1 kHz. ]   The image forming apparatus according to claim 1, wherein the intermediate transfer member is an intermediate transfer belt.   The image forming apparatus according to claim 1, wherein the toner contains carbon black.   The image forming apparatus according to any one of claims 1 to 3, wherein a process speed is 50 mm / sec or more and 500 mm / sec or less.

Images