JP3397482B2 - Image forming apparatus and method of manufacturing intermediate transfer body - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus and an intermediate transfer member used in the image forming apparatus.
In particular, the toner image formed on the first image carrier is temporarily transferred onto the intermediate transfer member and then the second image is transferred onto the second image carrier.
Copier, printer, image forming apparatus and該画 of facsimile obtaining image formation is further transferred to an image bearing member
The present invention relates to a method for manufacturing an intermediate transfer member used in an image forming apparatus .

[0002]

2. Description of the Related Art An image forming apparatus using an intermediate transfer member is
A color image forming apparatus, a multicolor image forming apparatus, or a color image that sequentially outputs a plurality of component color images of color image information or multicolor image information by layered transfer and outputs an image formed by synthesizing and reproducing the color image or the multicolor image. It is effective as an image forming apparatus having a forming function and a multicolor image forming function, and it is possible to obtain an image in which component color images are not misregistered (color misalignment).

FIG. 1 shows a schematic view of 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. Medium resistance elastic roller 20 as an intermediate transfer member
Are using.

Reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) which is repeatedly used as a first image bearing member, and rotates at a predetermined peripheral speed (process speed) in a clockwise direction indicated by an arrow. Driven.

In the course of rotation, the photosensitive drum 1 is uniformly charged to a predetermined polarity and potential by a primary charger (corona discharger) 2, and then 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.

Then, the electrostatic latent image is transferred to the first developing device 41.
It is developed by the magenta toner M which is the first color by the (magenta developing device). At this time, the second to fourth developing devices 42,
43, 44 (cyan, yellow, black developing devices)
Is activated-off and does not affect the photosensitive drum 1,
The magenta toner image of the first color is not affected by the second to fourth developing units 42 to 44.

The intermediate transfer member 20 is rotationally driven in the counterclockwise direction indicated by the arrow at the same peripheral speed as the photosensitive drum 1.

The intermediate transfer member 20 of this embodiment comprises a pipe-shaped core metal 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.
While the color magenta toner image passes through the nip portion between the photosensitive drum 1 and the intermediate transfer body 20, the outer peripheral surface of the intermediate transfer body 20 is formed by the electric field formed by the primary transfer bias applied to the intermediate transfer body 20. Are sequentially transferred to the intermediate transfer.

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

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

First from the photosensitive drum 1 to the intermediate transfer body 20
~ The primary transfer bias for the sequential superposition transfer of the toner image of the fourth color is the bias power source 6 with the polarity (+) opposite to that of the toner.
It is applied from 1. The applied voltage is, for example, +2 kV to +
It is in the range of 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 may be separated from the intermediate transfer member 20 in the step of sequentially transferring the fourth color toner image.

The transfer of the composite color toner image superposedly transferred onto the intermediate transfer member 20 onto the transfer material 24 which is the second image carrier is carried out while the transfer roller 25 is in contact with the intermediate transfer member 20. 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, the secondary transfer bias is applied from the bias power source 29 to the transfer roller 25. 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 that has received the toner image transfer is introduced into the fixing device 15 and is heated and fixed.

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 onto the first image carrier, for example, JP-A-63-
It is superior to the transfer method as described in JP-A-301960 in the following points.

(1) There is little color shift when the toner images of the respective colors are superposed.

(2) As shown in FIG. 1, an image is transferred from the intermediate transfer member without requiring any processing or control (for example, gripping by a gripper, adsorbing, giving a curvature, etc.) to the second image carrier. Since it can be transferred, a wide variety of second image carriers can be selected. Thin paper (40 g / m ² paper) such as envelopes, postcards, label paper, etc.
It is possible to transfer from a thick paper (200 g / m ² paper) to a thick paper (200 g / m ² paper) regardless of the width of the second image carrier, the length of the second image carrier, or the thickness of the second image carrier.

(3) Since the intermediate transfer member has excellent rigidity, dimensional accuracy such as dents, distortions, and deformations does not easily occur due to repeated use, so that the frequency of replacement of the intermediate transfer member can be reduced. .

As described above, due to the 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.

[0023]

However, these color electrophotographic apparatuses have not been functioning as apparatuses that make full use of the above advantages and are truly expected and satisfying to users. Is. That is, when the image forming apparatus using the intermediate transfer member is actually used repeatedly in various environments, the following problems still occur.

(1) 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, are sufficiently high. Not a thing. Therefore, a cleaning device that should be provided for the photosensitive drum and the intermediate transfer member is indispensable, and the load on the device is large for cleaning a large amount of transfer residual toner, which makes the cleaning device considerably complicated in structure and expensive. It becomes a thing.

(2) The image transferred to the intermediate transfer member and a part of the image transferred to the second image support are not transferred as shown in FIG. It may be). This is because the transfer efficiency has not reached 100% as described in (1). As the cause, it seems that the material used for the intermediate transfer member, the surface property, the resistance, or the magnitude of the applied bias at the time of transfer, the timing thereof or the mechanical configuration of the image forming apparatus, etc., act in a complex manner, The main cause is unknown. However, as the durability of the intermediate transfer body progresses,
Or, it is known that the worse the environment becomes, the lower the temperature and the lower humidity.

(3) The surface property and resistance of the intermediate transfer member may change as the durability is increased by repeatedly using the intermediate transfer member. In the worst case, the surface of the intermediate transfer member is scraped, which makes it impossible to maintain a good transfer efficiency initially obtained and a uniform image.

(4) As shown in FIG. 1, the intermediate transfer body 20 is provided with an intermediate transfer body cleaner 35. This is an apparatus for removing the untransferred toner from the intermediate transfer member by the time when the next series of transfer steps is started. As this cleaning method, there are various methods such as blade cleaning, fur brush cleaning, or a combination thereof. When the cycle of transferring toner on the surface of the intermediate transfer body 20-adhering-releasing is repeated several thousand times or tens of thousands times, The toner that cannot be completely removed by the cleaner 35 gradually accumulates on the surface of the intermediate transfer body 20, and so-called filming is formed. In this case, the transferability of the toner from the first image carrier is deteriorated, and the image quality is reduced or the overall transfer efficiency is deteriorated due to a spotted white image due to poor transfer of the filmed portion. Invite.

However, the present invention is directed to an image forming apparatus and an image forming apparatus using an intermediate transfer member which solves the above problems.
The present invention proposes a method for producing an intermediate transfer member used in .

An object of the present invention is to provide an image forming apparatus and an image forming apparatus which have very high transfer efficiency from the first image carrier to the intermediate transfer member and transfer efficiency from the intermediate transfer member to the second image carrier.
The present invention provides a method for manufacturing an intermediate transfer member used in an image forming apparatus . Another object is to obtain a uniform and uniform image quality without so-called "blank image", which does not depend on the type of paper or OHP sheet which is the second image carrier and does not cause transfer failure of a minute portion of the image. Image forming apparatus and image forming apparatus
The present invention provides a method for producing an intermediate transfer member used in . Another object is to use an image forming apparatus and an image forming apparatus which can maintain the same characteristics as those of the initial stage without any change even if the intermediate transfer body is repeatedly used for severe durability.
The present invention provides a method for producing the intermediate transfer member . Another object of the present invention is to provide an image forming apparatus and an image forming apparatus which do not cause filming due to adhesion of toner to the surface of an intermediate transfer member.
The present invention provides a method for producing an intermediate transfer member used in a recording medium .

[0030]

That is, according to the present invention, an image formed by transferring an image formed on a first image bearing member onto an intermediate transfer member and then further transferring it onto a second image bearing member. In the apparatus, the resistance of the intermediate transfer member is 1 × 10 ⁴ Ω or more and less than 1 × 10 ¹⁰ Ω, and the electrostatic capacity of the intermediate transfer member is 1 × 10 ⁻¹² F or more. has a coating layer as the surface layer of the elastic layer and the thickness 1μm~200μm thickness 1 mm to 5 mm, the image forming apparatus, wherein said coating layer contains a polyamide resin or a polyurethane resin (provided that the The resistance of the intermediate transfer member is
Linear pressure 4 so that the axes of the object and metal roll are parallel
Contact at 0 g / cm ² , DC power supply, resistor and potential difference
Connect the meter and drive the metal roll to rotate and follow it.
Adjust the rotation speed of the intermediate transfer member to 2 to 20 rpm.
And apply +1 kV from the DC power supply to the intermediate transfer member,
The potential across the resistor inserted downstream of the intermediate transfer member
Read the difference V _r at the potentiometer, determined from the potential difference V _r obtained
It is obtained from the obtained current value I. In addition, the electrostatic capacity of the intermediate transfer member
The amount is such that the axes of the intermediate transfer member and the metal roll are parallel to each other.
Contact with a linear pressure of 40 g / cm ^{2 so} that the
Connect the anti-static device and potentiometer to drive and rotate the metal roll
However, the rotation speed of the intermediate transfer member driven by this is 2 to 20 rp.
m so that the intermediate transfer member is 5
Apply an AC voltage of 00Vrms (frequency 95Hz),
The potential across the resistor inserted downstream of the intermediate transfer member
The difference is measured with a potentiometer and calculated from the resulting potential difference.
Current value I ₁ and 500 V to the intermediate transfer member with an AC power supply.
rms AC voltage (frequency 105Hz) is applied
The potential difference between both ends of the resistor inserted on the downstream side of the intermediary transfer member.
Measured with a potentiometer and calculated from the obtained potential difference.
It is obtained from the flow value I ₂ . ) . The present invention also provides a method of manufacturing an intermediate transfer member for an image forming apparatus, which comprises transferring an image formed on a first image bearing member onto an intermediate transfer member and then further transferring it onto a second image bearing member. In the above, the resistance of the intermediate transfer member is set to 1 × 10 ⁴ Ω or more and less than 1 × 10 ¹⁰ Ω, and a thickness of 1 μm is used as a surface layer on the elastic layer having a thickness of 1 mm to 5 mm.
m to 200 μm, and by forming a coating layer containing a polyamide resin or a polyurethane resin, the intermediate transfer member has a capacitance of 1 × 10 ⁻¹² F or more. Method (however, the intermediate transfer
The resistance of the image body is such that the axes of the intermediate transfer body and the metal roll are
Brought into contact at a linear pressure of 40 g / cm ² so as to be parallel, DC
Connect the power supply, resistor and potentiometer to drive the metal roll.
The rotational speed of the intermediate transfer body, which rotates dynamically and is driven by this, is 2 to 2
Adjust to 0 rpm, + 1kV from DC power supply
It is applied to the intermediate transfer member and is inserted on the downstream side of the intermediate transfer member.
Read the potential difference V _r across the resistor with a potentiometer
It is obtained from the current value I obtained from the obtained potential difference V _r . Well
In addition, the capacitance of the intermediate transfer member is different from that of the intermediate transfer member and the metal roller.
The linear pressure of 40 g / cm ² so that both axes are parallel.
Abut, connect the AC power supply, resistor and potentiometer,
An intermediate transfer member that drives and rotates the metal roll and follows it.
Adjust so that the rotation speed of the
AC voltage (frequency) of 500 Vrms to the intermediate transfer member at the source.
Applied to the downstream side of the intermediate transfer member.
Measure the potential difference across the resistor with a potentiometer and obtain
Current value I ₁ calculated from the generated potential difference and AC power supply
An AC voltage of 500 Vrms (frequency 10
5 Hz) was applied, and the intermediate transfer member was inserted on the downstream side.
The potential difference across the resistor was measured with a potentiometer and obtained
It is determined from the current value I ₂ calculated from the potential difference . ) .

The present invention will be described in detail below.

The transfer efficiency of the intermediate transfer member largely depends on the resistance value of the member. That is, the resistance value of the intermediate transfer member is 1
When it is less than × 10 ⁴ Ω, the transfer efficiency of the toner from the intermediate transfer member to the second image bearing member (hereinafter referred to as the secondary transfer efficiency)
There lowered, 1 × least 10 ¹⁰ Omega from the first image bearing member (referred to hereafter as primary transfer efficiency) toner transfer efficiency to the intermediate transfer member is lowered. Decrease in primary transfer efficiency or secondary transfer efficiency is the total transfer efficiency (= primary transfer efficiency x secondary transfer efficiency)
Is caused, which leads to a decrease in image density and an increase in waste toner. Therefore, in order to satisfy both the primary transfer efficiency and the secondary transfer efficiency with high values, the resistance value of the intermediate transfer member is set to 1
It is necessary to make it 10 ⁴ Ω or more and less than 1 × 10 ¹⁰ Ω.

As described above, if the resistance value of the intermediate transfer member is set to 1 × 10 ⁴ Ω or more and less than 1 × 10 ¹⁰ Ω, a high total transfer efficiency can be obtained, and problems such as a hollow image can also occur. No, you can get a good image.

The resistance value of the intermediate transfer member of the present invention was determined according to the following procedure.

(1) Intermediate transfer member and metal roll (Φ30)
Are brought into contact with each other at a linear pressure of 40 g / cm ² so that their axes are parallel to each other, and a DC power source, a resistor and a potentiometer are connected (Fig. 2).

(2) The metal roll is driven and rotated, and the rotation speed of the intermediate transfer member driven by the metal roll is adjusted to be 2 to 20 rpm.

(3) +1 kV is applied to the circuit from the DC power source, and the potential difference V _r at both ends of the resistor having an appropriate resistance value inserted on the downstream side of the intermediate transfer member is read by a potentiometer.

(4) The current value I flowing in the circuit is obtained from the obtained potential difference V _r , and the current value I is applied voltage (1000
The value divided by V) is taken as the resistance value of the intermediate transfer member.

However, in the present invention, attention is paid to the electrostatic capacity as a physical property value of the member in order to further improve the overall transfer efficiency and obtain an intermediate transfer member having higher image quality and higher durability. That is, in the above-mentioned intermediate transfer member, the above-mentioned object can be achieved by setting the electrostatic capacity of the intermediate transfer member to 1 × 10 ⁻¹² F or more. The reason why the transfer efficiency is improved by increasing the electrostatic capacity is considered as follows. That is, assuming that the electric field applied between the first image carrier and the intermediate transfer member is E1 and the electric field applied between the intermediate transfer member and the second image carrier is E2, E1 and E2 are as follows. Can be written on.

E1 = (V _h1 −V _c ) / (d _m / ε _m + d _t1 / ε _t + d _c / ε _c + g ₁ ) ... (1) E2 = (V _h2 −V _p ) / (d _c / ε _c + d _t2 / ε _t + d _p / ε _p + g ₂ ) (2) where V _h1 : surface potential Vc on the toner layer on the first image carrier V _c : surface potential V on the intermediate transfer member _h2 : surface potential on the toner layer on the intermediate transfer member V _p : surface potential on the second image carrier d _m : thickness of the recording layer of the first image carrier d _t1 : first image carrier Thickness of upper toner layer d _c : Thickness of elastic layer and coating layer of intermediate transfer member d _t2 : Thickness of toner layer on intermediate transfer member d _p : Thickness of second image carrier ε _m : First image Dielectric constant ε _t of recording layer of carrier: Dielectric constant ε _c of toner layer: Dielectric constant ε _p of elastic layer and coating layer of intermediate transfer member: Dielectric constant g ₁ of second image carrier: First image carrier And gap width of the intermediate transfer member g _2: transfer efficiency in the electrostatic transfer of the gap width toner and the second image bearing member and the intermediate transfer member is proportional to the electric field E applied to the gap between the transfer material and the toner layer It is known. Then, as is clear from the equations (1) and (2), it is found that E1 and E2 increase as ε _c increases. Further, the capacitance C and the relative permittivity ε are C = a × ε
(A is a constant). Therefore, when the electrostatic capacitance C of the intermediate transfer member is increased, the value of the electric field E is increased,
It can be seen that the transfer efficiency is improved.

The capacitance of the intermediate transfer member of the present invention was determined according to the following measuring procedure.

(1) Intermediate transfer member and metal roll (Φ30)
Are brought into contact with each other at a linear pressure of 40 g / cm ² so that their axes are parallel, and an AC power source, a resistor and a potentiometer are connected (Fig. 2).

(2) The metal roll is driven and rotated, and the rotational speed of the intermediate transfer member driven by the drive is adjusted to be 2 to 20 rpm.

(3) The intermediate transfer member is heated to 50 with an external AC power source.
An AC voltage (frequency: 95 Hz) of 0 Vrms is applied.

(4) The potential difference between both ends of the resistor having an appropriate resistance value inserted on the downstream side of the intermediate transfer member is measured by a potentiometer to calculate the current flowing through the circuit (that is, the sample). The obtained current value is set as the current value I ₁ .

(5) 50 by using an external AC power source for the intermediate transfer member
An AC voltage (frequency 105 Hz) of 0 Vrms is applied.

(6) The potential difference between both ends of the resistor having an appropriate resistance value inserted on the downstream side of the intermediate transfer member is measured with a potentiometer to calculate the current flowing through the circuit (ie, sample). The obtained current value is set as the current value I ₂ .

(7) Substituting the obtained value into the following equation,
The capacitance C of the intermediate transfer member is calculated. ^{_{Formula: C = {(I 2 2}} /500 2 -I 1 2/500 2) / (1
05 ² -95) ^2} intermediate transfer member used in the ^1/2 / 2 [pi present invention, for example, roller-shaped with at least a rubber, an elastomer, an elastic layer made of resin on the cylindrical conductive support, and further, A roller shape having one or more coating layers on the elastic layer, or
The belt shape and various modes as shown in FIG. 6 can be selected according to the purpose and need. Figure 3
~ Shown in FIG.

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 each figure, 100 is a rigid cylindrical conductive support, 101 is an elastic layer, and 10 is an elastic layer.
2 and 103 are coating layers, and 104 is an intermediate transfer belt.

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

The thickness of the elastic layer is 1 mm to 5 mm. The thickness of the coating layer is a thin layer der to tell an upper layer or the photosensitive member surface thereon flexibility of the lower elastic layer
It is necessary to be 1 μm to 200 μm.

The resistance value of the intermediate transfer member used in the present invention is 1
It is necessary to adjust to 0 ⁴ to 10 ¹⁰ , but in order to control the resistance in this region, it is necessary to add a conductive agent in some cases. The conductive agent is not particularly limited, but carbon, aluminum powder, nickel powder or the like can be used. It is also possible to use a conductive resin instead of dispersing the conductive agent in the resin. Specific examples thereof include quaternary ammonium salt-containing polymethylmethacrylate, polyvinylaniline, polyvinylpyrrole, polydiacetylene and polyethyleneimine. Among these, the conductive particle-dispersed resin is preferable from the viewpoint of controlling the conductivity.

The intermediate transfer member of the present invention has a capacitance of 1
It is necessary to adjust to × 10 ^-12 F or more. The material used for that purpose is not particularly limited, but in one or more of rubber, resin, filler, etc.,
A material having a high dielectric constant can be used.

Examples of the rubber having a high dielectric constant include styrene-butadiene rubber, butadiene rubber, ethylene-propylene rubber, chloroprene rubber, chlorosulfonated polyethylene, chlorinated polyethylene, acrylonitrile-butadiene rubber, acrylic rubber and fluororubber.

[0055] As the high dielectric constant resin, polyamide, Ru polyurethane der.

Examples of the filler having a high dielectric constant include inorganic compounds such as potassium titanate, strontium titanate, barium titanate and titanium oxide, and fine powders of organic compounds such as polyvinylidene fluoride. Among these, potassium titanate, strontium titanate, and barium titanate, which have been once sintered into a fine powder, have a very high relative dielectric constant of several thousand to ten thousand, so a small amount of The addition can increase the electrostatic capacity of the intermediate transfer member.

Of course, in manufacturing the intermediate transfer member of the present invention, it is not necessary to select a material from the above material group, and the resistance value and electrostatic pre-capacitance of the obtained intermediate transfer member are shown in the present invention. It should be within the range.

As described above, the intermediate transfer member of the present invention is adjusted to have a resistance value region in which the primary transfer efficiency and the secondary transfer efficiency are compatible with each other at a high value, and the electrostatic capacity of the intermediate transfer member is adjusted. The transfer efficiency can be further increased due to the large size. Therefore, the image forming apparatus using the intermediate transfer member of the present invention has the following features.

(1) It is possible to obtain a good image without a hollow image.

(2) The transfer residual toner is small, and therefore the cleaning device for the intermediate transfer member can be downsized.

(3) The residual toner after transfer is small, and therefore, the intermediate transfer member is repeatedly used, and filming does not easily occur even if the durability is advanced, and a good image can be maintained.

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

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

[0064]

The present invention will be described in detail below with reference to examples. (Example 1) Diameter 182 mm, length 320 mm, thickness 5
A roller having an elastic layer was obtained by transfer-molding a rubber compound having the following composition using a metal mold on the surface of an aluminum cylindrical roller having a size of mm. The following barium titanate is a barium titanate powder 137
Sintered at 0 ° C for 2 hours, then fine powder (average particle size 5μ)
The crushed product was used.

Rubber compounding SBR rubber 100 parts (parts by weight, the same hereinafter) 50 parts barium titanate 50 parts zinc oxide 2 parts conductive carbon black 10 parts naphthenic oil 40 parts vulcanizing agent 2 parts vulcanization accelerator 3 parts A coating material was prepared according to the following formulation and used as a coating layer coating material for obtaining a coating layer on the elastic layer.

Coating layer coating formulation Polyurethane prepolymer 50 parts Acetylene black 4 parts Toluene 120 parts Curing agent 50 parts The above coating composition is spray coated on the elastic layer to give a thickness of 50 μm.
m coating layer was formed, and then the solvent was removed by heating at 85 ° C. for 1 hour, and the coating layer was crosslinked to obtain an intermediate transfer member having a tough surface layer. This intermediate transfer member has a resistance of 5 × 10 ⁷ Ω and a capacitance of 5 × 10 ^-11.
It was F.

This intermediate transfer member was mounted on the full-color electrophotographic apparatus shown in FIG. 1 and an OPC photosensitive drum was used as a photosensitive member to print a full-color image on 80 g / cm ² paper. Defined and measured. Primary transfer efficiency (transfer efficiency from photosensitive drum to intermediate transfer body); image density on intermediate transfer body / (transfer residual image density on photosensitive drum + image density on intermediate transfer body). Secondary transfer efficiency (transfer efficiency from intermediate transfer body to paper); image density on paper / (image density on paper + transfer residual image density on intermediate transfer body).

As a result of measuring the transfer efficiency, the primary transfer efficiency was 93% and the secondary transfer efficiency was 94%. In addition, the full-color print image had characters and fine lines without voids, and the solid image had uniform image quality. After the durability test of 10,000 sheets, the same image quality as the initial one was obtained, and the secondary transfer efficiency was 93.
%, Almost no decrease was seen.

The presence or absence of filming by the toner was judged by observation with an optical microscope. Even when the surface of the intermediate transfer member of Example 1 after running 10,000 sheets was observed, filming by the toner was not observed.

The image forming conditions of this embodiment are shown below.

Photoconductor: OPC photosensitive drum surface potential: -700V Color developer (both four colors): Non-magnetic one-component toner Primary transfer voltage: + 900V Secondary transfer voltage: + 3400V Process speed: 120mm / sec Development bias: -500V (Example 2) Diameter 182 mm, length 320 mm, thickness 5
A roller having an elastic layer was obtained by transfer-molding a rubber compound having the following composition using a metal mold on the surface of an aluminum cylindrical roller having a size of mm.

[0072] Next, a coating material was prepared according to the following formulation to obtain a coating layer coating material for obtaining a coating layer on the elastic layer.

Coating composition for coating layer N-methoxymethylated nylon 10 parts Calcium titanate 5 parts Carbon black 0.5 parts Methanol 100 parts Citric acid 0.3 parts The above coating composition is spray coated on the elastic layer to give a thickness of 30 μm.
m coating layer was formed, and thereafter, the residual solvent was removed by heating at 120 ° C. for 1 hour, and the coating layer was cross-linked to obtain an intermediate transfer member having a tough surface layer.

The intermediate transfer member had a resistance of 1 × 10 ⁷ Ω and a capacitance of 2 × 10 ^-11 F. In the same manner as in Example 1, transfer efficiency measurement and 10,000-sheet durability test were performed. A good image was obtained from the initial stage, and filming did not occur even after 10,000 sheets were used. The results are shown in Table 1. (Example 3) An intermediate transfer member was prepared in the same manner as in Example 1 except that the elastic layer coating composition was changed as follows, and electrostatic capacity measurement, transfer efficiency measurement and durability test were performed. went. In terms of image quality, a good full-color image that was the same as the initial stage was obtained even after 10,000 sheets had been used. The results are shown in Table 1.

[0075]   Coating composition for coating layer Acrylic modified polyurethane 50 parts                       Hardener 40 parts                       Polyvinylidene fluoride fine powder 30 parts                       Dispersant 1.5 parts                       Methyl ethyl ketone 120 parts

Comparative Example 1 An intermediate transfer member was prepared in the same manner as in Example 1 except that the compounding amount of conductive carbon black was changed to 18 parts in the rubber compounding of Example 1, and the same procedure as in Example 1 was carried out. The resistance value, capacitance, transfer efficiency and durability test were performed. Since the resistance of the intermediate transfer member was high, the primary transfer efficiency was lower than in the initial stage, and a void image was generated. The results are shown in Table 1.

Comparative Example 2 An intermediate transfer member was prepared in the same manner as in Example 1 except that barium titanate was not added in the rubber compounding of Example 1, and the resistance value and electrostatic capacity were the same as in Example 1. The transfer efficiency was measured and the durability test was performed.
Since the electrostatic capacity was as small as 8 × 10 ^-13 (F), the secondary transfer efficiency was poor. Although a good image was obtained even after 10,000 sheets, slight filming was observed when the surface of the intermediate transfer and other surfaces was observed with a microscope. The degree of void is early,
Both were good after running 10,000 sheets. The results are shown in Table 1.

[0078]

[Table 1]

[0079]

As described above, the present invention has the first aspect.
In the image forming apparatus for transferring the image formed on the image bearing member onto the intermediate transfer member, and further transferring the image onto the second image bearing member, at 1 × 10 ⁴ Ω or more and less than 1 × 10 ¹⁰ Ω. And the electrostatic capacity of the intermediate transfer member is 1 × 10 ⁻¹² F or more, and high values can be obtained for both the primary transfer efficiency and the secondary transfer efficiency. Therefore, the following effects can be obtained by using the image forming apparatus of the present invention. (1) A good image can be obtained without the occurrence of a hollow image. (2) The residual toner after transfer is small, and the size of the cleaning device can be reduced. (3) Since transfer efficiency is high, occurrence of filming due to durability can be suppressed.

[Brief description of drawings]

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

FIG. 2 is a circuit diagram for measuring the resistance value or capacitance of the intermediate transfer member of the present invention.

FIG. 3 is a sectional view of a roller-shaped intermediate transfer member of the present invention having an elastic layer.

FIG. 4 is a sectional view of a roller-shaped intermediate transfer member of the present invention having a coating layer on an elastic layer.

FIG. 5 is a sectional view of a roller-shaped intermediate transfer member of the present invention having a plurality of coating layers on an elastic layer.

FIG. 6 is a schematic diagram of a color image output device using an intermediate transfer belt.

FIG. 7 is a diagram illustrating a hollow image.

[Explanation of symbols]

1 photosensitive drum 2 Primary charger 3 Image exposure means 9 paper cassettes 14 Photosensitive drum cleaning device 15 Fixer 20 Intermediate transfer body 21 core 22 Elastic layer 24 Transfer material 25 Transfer roller 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 cores 101 elastic layer 102 coating layer 103 coating layer 104 Belt-shaped intermediate transfer member 200 metal roll 201 resistor 202 power supply 203 potentiometer

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takashi Kusaba, 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Hiroyuki Kobayashi, 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-5-333725 (JP, A) JP-A-5-142955 (JP, A) JP-A-6-289729 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/16

Claims (6)

(57) [Claims] 1. An image forming apparatus for transferring an image formed on a first image carrier onto an intermediate transfer member and then further transferring it onto a second image carrier, wherein the resistance of the intermediate transfer member is increased. 1 × 10 ⁴ Ω or more and less than 1 × 10 ¹⁰ Ω, the electrostatic capacity of the intermediate transfer member is 1 × 10 ⁻¹² F or more, and the intermediate transfer member has an elastic layer with a thickness of 1 mm to 5 mm; Thickness 1 μm
An image forming apparatus having a coating layer as a surface layer of ˜200 μm, the coating layer containing a polyamide resin or a polyurethane resin (provided that the resistance of the intermediate transfer member is reduced).
As for the resistance, the axes of the intermediate transfer member and the metal roll are parallel to each other.
Contact with a linear pressure of 40 g / cm ^{2 so} that the
Connect the anti-static device and potentiometer to drive and rotate the metal roll
However, the rotation speed of the intermediate transfer member driven by this is 2 to 20 rp.
Adjust to m, + 1kV from DC power source
The voltage applied to the transfer body and the resistance inserted in the downstream side of the intermediate transfer body.
The potential difference V _r at both ends of the counter was read by a potentiometer and obtained.
It is obtained from the current value I obtained from the potential difference V _r . Also, the
The capacitance of the intermediate transfer member is determined by comparing the intermediate transfer member and the metal roll.
Contact as both axes are parallel at a linear pressure of 40 g / cm ²
And connect an AC power supply, a resistor and a potentiometer to the metal
The rotation of the intermediate transfer body that drives and rotates the roll
Adjust so that the number is 2 to 20 rpm, and use an AC power supply
An AC voltage of 500 Vrms (frequency 95
Hz) is applied, and the resistance inserted in the downstream side of the intermediate transfer member is
The potential difference between the two ends of the counter was measured with a potentiometer and the
The current value I ₁ calculated from the difference and the intermediate value with the AC power supply
AC voltage of 500Vrms (frequency 105H
z) is applied, and the resistance is inserted in the downstream side of the intermediate transfer member.
Potential obtained by measuring the potential difference across the instrument with a potentiometer
It is determined from the current value I ₂ calculated from the difference . ) . 2. The intermediate transfer member is a roller.
The image forming apparatus described. 3. The intermediate transfer member is a belt.
The image forming apparatus described. 4. The image forming apparatus according to claim 1, wherein the first image carrier is a photosensitive drum having a photosensitive layer on a conductive rigid roller. 5. The image forming apparatus according to claim 4, wherein at least the outermost layer of the photosensitive drum contains tetrafluoroethylene resin powder. 6. A method of manufacturing an intermediate transfer member for an image forming apparatus, comprising: transferring an image formed on a first image bearing member onto an intermediate transfer member; and further transferring the image onto a second image bearing member. , The resistance of the intermediate transfer member is 1 × 10 ⁴ Ω or more, 1 × 10 4
^{It is} less than ¹⁰ Ω, and the surface layer has a thickness of 1 on the elastic layer with a thickness of 1 mm to 5 mm.
The intermediate transfer member has a capacitance of 1 × 10 ⁻¹² F or more by forming a coating layer having a thickness of μm to 200 μm and containing a polyamide resin or a polyurethane resin. Method (however, the intermediate
The resistance of the transfer body is determined by setting the intermediate transfer body and the metal roll on both axes.
A linear pressure of 40 g / cm ^{2 so} that the
Current source, resistor and potentiometer, and connect the metal roll.
The rotational speed of the intermediate transfer body, which is driven to rotate and follows this, is 2 to
Adjust to 20 rpm, + 1kV from DC power supply
Is applied to the intermediate transfer member, and is inserted on the downstream side of the intermediate transfer member.
Read the potential difference V _r across the resistor with a potentiometer ,
It is obtained from the current value I obtained from the obtained potential difference V _r .
In addition, the capacitance of the intermediate transfer member is different from that of the intermediate transfer member and the metal.
Linear pressure of 40g / cm so that both axes are parallel
² and make contact, connect AC power supply, resistor and potentiometer.
Drive the metal roll to rotate and follow the intermediate rotation.
Adjust the rotation speed of the image to be 2 to 20 rpm, and
AC voltage of 500 Vrms is applied to the intermediate transfer member by a flowing power source.
(Frequency of 95 Hz) is applied to the downstream side of the intermediate transfer member.
Measure the potential difference across the inserted resistor with a potentiometer
Then, the current value I ₁ calculated from the obtained potential difference and the alternating current
An AC voltage (frequency) of 500 Vrms is applied to the intermediate transfer member by a power source.
Wave number of 105 Hz) is applied, and it is inserted on the downstream side of the intermediate transfer member.
Measure the potential difference across the inserted resistor with a potentiometer,
Calculated from the obtained calculated from a potential difference current value I ₂ Metropolitan
It ) .