JP6922191B2 - Conductive member for image forming device, transfer unit for image forming device and image forming device - Google Patents

Description

The present invention relates to a conductive member for an image forming apparatus, a transfer unit for an image forming apparatus, and an image forming apparatus.

In the electrophotographic image forming apparatus, various conductive members such as a charging roll, a transfer belt, a recording medium transfer belt, and a transfer roll are used.

For example, Patent Document 1 describes a rubber composition having a sea-island structure, which comprises a continuous phase of an organic polymer material made of an ion conductive rubber material and a particle phase of an organic polymer material made of an electron conductive rubber material. The ionic conductive rubber material is mainly composed of the raw material rubber A having a volume resistivity of 1 × 10 ¹² Ω · cm or less, and the electronic conductive rubber material is obtained by blending conductive particles in the raw material rubber B. A semi-conductive rubber composition characterized by being conductive "is disclosed.

JP-A-2002-003651

A conductive member used in an image forming apparatus using an ionic conductive material and an electronically conductive conductive material may cause resistance fluctuations when a high voltage is repeatedly applied.

Therefore, according to the present invention, in a conductive member for an image forming apparatus having a layer containing an ion-conductive conductive material and an electron-conductive conductive material, the ion-conductive conductive material and the electron-conductive material are provided. Of the 8000 conductive paths in a 10 μm × 10 μm square, the layer containing the conductive material has a cumulative frequency of less than 50 or more than 300 in the range of resistance value 11.5 LogΩ or more and 12.0 LogΩ or less, or conductivity. An object of the present invention is to provide a conductive member for an image forming apparatus in which fluctuations in electrical resistance are suppressed even when a high voltage is repeatedly applied, as compared with a case where the cumulative frequency in the range of a path resistance value of less than 11.5 LogΩ exceeds 200. And.

The following inventions are provided in order to achieve the above object.
The invention according to <1 > is
It has a sea part containing an ionic conductive material and an island part composed of an aggregate of an electronically conductive conductive material, and has a resistance value of 11 out of 8000 conductive paths in a 10 μm × 10 μm square. A conductive member for an image forming apparatus having a layer in which the cumulative frequency in the range of 5.5 LogΩ or more and 12.0 LogΩ or less is 50 or more and 300 or less, and the cumulative frequency in the range of the resistance value of the conductive path less than 11.5 LogΩ is 200 or less.
The invention according to <2 > is
The conductive member for an image forming apparatus according to < 1 > , wherein the ionic conductive material is a rubber material.
The invention according to <3 > is
The conductive member for an image forming apparatus according to < 1 > or < 2 > , wherein the electronically conductive conductive material is carbon black.
The invention according to <4 > is
The conductive member for an image forming apparatus according to any one of < 1 > to < 3 > , which has an endless belt shape.

The invention according to <5 > is
A transfer belt composed of the conductive member for an image forming apparatus according to < 4 >, and
A plurality of rolls that hang the transfer belt under tension, and
A transfer unit for an image forming apparatus equipped with.
The invention according to <6 > is
The transfer unit for an image forming apparatus according to < 5, wherein the transfer belt is a recording medium transfer transfer belt that conveys the recording medium in a transfer unit in which a toner image is transferred to the recording medium.

The invention according to <7 > is
Image holder and
A charging means for charging the surface of the image holder and
An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the image holder,
A developing means for developing the electrostatic latent image on the surface of the image holder with a developer containing toner to form a toner image, and
A transfer means having a transfer belt composed of the conductive member for an image forming apparatus according to < 4 >, and transferring the toner image formed on the surface of the image holder to a recording medium.
A fixing means for fixing the toner image transferred to the recording medium, and
An image forming apparatus equipped with.
The invention according to <8 > is
The image forming apparatus according to < 7 > , wherein the transfer belt is a recording medium transfer transfer belt that conveys the recording medium in a transfer unit in which the toner image is transferred to the recording medium.

According to the invention according to < 1 > , < 2 > , < 3 > or < 4 > , the conductivity for an image forming apparatus having a layer containing an ionic conductive material and an electron conductive conductive material. In the member, the layer containing the ionic conductive material and the electronically conductive conductive material has a resistance value of 11.5 LogΩ or more and 12.0 LogΩ or less among 8000 conductive paths in a 10 μm × 10 μm square. Compared to the case where the cumulative frequency of is less than 50 or more than 300, or the cumulative frequency in the range where the resistance value of the conductive path is less than 11.5 LogΩ exceeds 200, the fluctuation of the electric resistance changes even if a high voltage is repeatedly applied. Provided is a conductive member for an image forming apparatus that is suppressed.

According to the invention according to < 5 > or < 6 > , the cumulative frequency in the range of resistance value of 11.5 LogΩ or more and 12.0 LogΩ or less is less than 50 out of 8000 conductive paths in a 10 μm × 10 μm square as a transfer belt. Compared to the case where the resistance value of the conductive path exceeds 300, or the case where a transfer belt having a layer having a cumulative frequency of more than 200 in the range of the resistance value of less than 11.5 LogΩ of the conductive path is provided, the fluctuation of the electric resistance changes even if a high voltage is repeatedly applied. A transfer unit for an image forming apparatus to which a suppressed transfer belt is applied is provided.

According to the invention according to < 7 > or < 8 > , the cumulative frequency in the range of resistance value of 11.5 LogΩ or more and 12.0 LogΩ or less is less than 50 out of 8000 conductive paths in a 10 μm × 10 μm square as a transfer belt. Compared to the case where the resistance value of the conductive path exceeds 300, or the case where a transfer belt having a layer having a cumulative frequency of more than 200 in the range of the resistance value of less than 11.5 LogΩ of the conductive path is provided, the fluctuation of the electric resistance changes even if a high voltage is repeatedly applied. An image forming apparatus to which a suppressed transfer belt is applied is provided.

It is a schematic perspective view which shows an example of the conductive member for an image forming apparatus which concerns on this embodiment. It is the schematic which shows an example of the layer structure of the conductive member for an image forming apparatus which concerns on this embodiment. It is a schematic plan view (A) and a schematic cross-sectional view (B) which show an example of a circular electrode. It is a schematic block diagram which shows an example of the image forming apparatus which concerns on this embodiment. It is a schematic block diagram which shows another example of the image forming apparatus which concerns on this embodiment. It is a schematic perspective view which shows an example of the transfer unit for an image forming apparatus which concerns on this embodiment. It is an image obtained by measuring a part of the cross section of the endless belt-shaped conductive member manufactured in the Example by an atomic force microscope (AFM). It is an image obtained by measuring a part of the cross section of the endless belt-shaped conductive member manufactured in the Example by a scanning electron microscope (SEM).

Hereinafter, embodiments that are an example of the present invention will be described in detail with reference to the drawings.

[Conductive member]
The conductive member for an image forming apparatus (hereinafter, may be simply referred to as “conductive member”) according to the present embodiment includes a sea portion containing an ion conductive conductive material and an electron conductive conductive material. It is provided with a layer having an island portion composed of agglomerates. In this layer, the cumulative frequency in the range of resistance value of 11.5 LogΩ or more and 12.0 LogΩ or less is 50 or more and 300 out of 8000 conductive paths (conductive sites) in 10 μm × 10 μm square. It has the characteristic that the cumulative frequency in the range of the resistance value of the conductive path of less than 11.5 LogΩ is 200 or less.
In the present specification, "conductive" means that the volume resistivity is ^{less than 1.0 × 10 14} Ω · cm.

In an electrophotographic image forming apparatus, for example, a toner image formed on the surface of an image holder (hereinafter, may be referred to as "electrophotographic photosensitive member" or "photoreceptor") is directly or intermediate on a recording medium. It is transferred via a transcript. The conductive member for the image forming apparatus is applied as an endless belt to, for example, a recording medium transfer transfer belt (also referred to as a “transfer transfer belt”) or an intermediate transfer belt that conveys a recording medium to a transfer unit.
In recent years, image forming apparatus is required to have high speed and high image quality, and when transferring a toner image formed on the surface of an electrophotographic photosensitive member, for example, a high voltage is applied to a transfer transfer belt or an intermediate transfer belt. (For example, 1.0 kV or more) is applied. The transfer transfer belt and the intermediate transfer belt are designed to have high resistance because a high voltage is repeatedly applied by continuous use. Therefore, the belt is required to be used under a high voltage in addition to increasing the resistance.

By the way, the transfer transfer belt and the intermediate transfer belt include, for example, an ionic conductive material (hereinafter, may be referred to as an "ionic conductive material") and an electron conductive conductive material as materials constituting the belt. A material (hereinafter, may be referred to as an "electroconductive material") may be used.

However, belts made of ionic conductive materials cause an increase in resistance due to repeated application of high voltage due to continuous use. It is considered that the increase in resistance of the ionic conductive material due to repeated application of high voltage is caused by the uneven distribution of ions and the oxidative deterioration of the ionic conductive material.
On the other hand, when an electronically conductive material is used, the resistance of the conductivity decreases due to dielectric breakdown of the ionic conductive material existing between the electron conductive materials. It is considered that this is due to hopping conduction between conductors such as an electronically conductive material.
As described above, the conductive member used in the image forming apparatus using the ionic conductive material and the electron conductive material may cause resistance fluctuation when a high voltage is repeatedly applied.

On the other hand, in the conductive member according to the present embodiment, in particular, when the conductive path in the square of 10 μm × 10 μm satisfies the above conditions, the fluctuation of the electric resistance is suppressed even if the high voltage is repeatedly applied. .. The reason is not clear, but it is presumed as follows.

The resistance value of the conductive path of the conductive member containing the ionic conductive material and the electron conductive material was investigated using a conductive atomic force microscope (hereinafter, also referred to as "conductive AFM"). The resistance value of the conductive path is the resistance value when the flowing current value is measured by the measurement with a conductive atomic force microscope (hereinafter, may be referred to as a resistance value (current value)).
As a result, when the cumulative frequency in the range of resistance value 11.5 LogΩ or more and 12.0 LogΩ or less exceeds 300 out of 8000 conductive paths in a 110 μm × 10 μm square, or the resistance value of the conductive path is less than 11.5 LogΩ (current value). It has been found that when the cumulative frequency in the range (over 60 pA) is too large, resistance reduction due to dielectric breakdown due to hopping conduction is likely to occur.
On the other hand, it has been found that when the cumulative frequency in the range of resistance value 11.5 LogΩ or more and 12.0 LogΩ or less (current value is 20 pA or more and 60 pA or less) is too small, resistance increase due to uneven distribution of ions is likely to occur.
Therefore, the cumulative frequency in the range of resistance value 11.5 LogΩ or more and 12.0 LogΩ or less (current value is 20 pA or more and 60 pA or less) is set as an appropriate range, and the resistance value of the conductive path is less than 11.5 LogΩ (current value exceeds 60 pA). If the cumulative frequency of the above is set to a certain level or less, the increase in resistance and the decrease in resistance of the conductive member as a whole can be easily balanced. This is because the current content decreased at the location where the resistance increased in the conductive path of the conductive member is compensated for by the current component increased at the location where the resistance decreased in the other conductive path, so that the resistance of the entire conductive member fluctuates. It will be difficult.

For the above reasons, it is presumed that the conductive member according to the present embodiment suppresses fluctuations in electrical resistance even if a high voltage is repeatedly applied.

As described above, the conductive member according to the present embodiment includes a layer having a sea portion containing an ionic conductive material and an island portion composed of an aggregate of the electron conductive material. In the conductive member whose conductive path in a 10 μm × 10 μm square satisfies the above conditions, the islands composed of aggregates of the electron conductive material are not unevenly distributed in the sea portion containing the ion conductive material. It is considered that it is distributed in a nearly uniform state throughout the sea.

The shape of the conductive member according to the present embodiment is not particularly limited, and may be, for example, an endless belt shape, a roll shape, or a plate shape. Further, the conductive member according to the present embodiment may have a structure of a single layer as it is having the above characteristics, or may have a structure of a laminated body in which layers other than the above layers are laminated. Hereinafter, as an example of the conductive member according to the present embodiment, a transfer transfer belt which is an endless belt-shaped conductive member (hereinafter, may be referred to as a “conductive belt member”) will be mainly described.

FIG. 1 is a schematic perspective view showing a conductive belt member as an example of the conductive member according to the present embodiment. FIG. 2 is a schematic view showing an example of the layer structure.

The conductive belt member 10 for the image forming apparatus shown in FIG. 1 has a base material layer 10A and a surface layer 10B provided on the outer peripheral surface of the base material layer 10A.

<Base layer>
The base material layer 10A has a sea portion containing an ionic conductive material and an island portion in which the electron conductive material is aggregated, and is configured to contain other well-known additives, if necessary.
The base material layer 10A has, for example, 20 or more and 50 or less islands in a 10 μm × 10 μm square, and is distributed in a nearly uniform state. There is.
In addition, FIG. 7 is an image obtained by measuring a cross section of a conductive belt member having a sea portion containing an ion conductive material and an island portion in which an electron conductive material is aggregated by an atomic force microscope (AFM). As an example, the high contrast position (black spot part) is an agglomerated island part of carbon black.

(Ion conductive material)
The ionic conductive material contained in the base material layer 10A is not particularly limited as long as it is a conductive material having ionic conductivity. For example, the ions are separated and the ions move to exhibit conductivity, and specific materials include resin materials and rubber materials. When the conductive member according to the present embodiment is used as the transfer transfer belt, the ion conductive material contained in the base material layer 10A is preferably a rubber material from the viewpoint of elasticity.

Examples of rubber materials include isoprene rubber, chloroprene rubber (CR), epichlorohydrin rubber (ECO), butyl rubber, polyurethane, silicone rubber, fluororubber, styrene-butadiene rubber, butadiene rubber, nitrile rubber, ethylene propylene rubber, and epi. Chlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, ethylene-propylene-diene ternary copolymer rubber (EPDM), acrylonitrile-butadiene copolymer rubber (NBR), natural rubber, etc. , And rubber in which these are mixed.

Among these rubber materials, polar rubbers such as epichlorohydrin rubber (ECO), chloroprene rubber (CR), and EPDM, and rubbers mixed thereto are preferably mentioned.

The content of the rubber material in the base material layer 10A is preferably 50% by mass or more and 90% by mass or less, more preferably 70% by mass or more and 85% by mass or less, and particularly preferably 75% by mass or more and 80% by mass or less.
From the viewpoint of controlling electrical resistance, the conductive organic polymer material is preferably a rubber material containing EPDM, CR, ECO, and NBR as rubber components. It is more preferable that each of these rubber components is contained in the following mass ratio with respect to 100% by mass of the rubber material, for example.
EPDM: 20% by mass or more and 45% by mass or less (more preferably 35% by mass or more and 40% by mass or less)
-CR: 20% by mass or more and 40% by mass or less (more preferably 30% by mass or more and 35% by mass or less)
-ECO: 0% by mass or more and 20% by mass or less (more preferably 10% by mass or more and 15% by mass or less)
-NBR: 0% by mass or more and 15% by mass or less

(Electromagnetic conductive material)
The electron conductive material contained in the base material layer 10A aggregates in the base material layer 10A to form an island portion. For example, among the islands (aggregates) formed by agglomerating electronically conductive materials in the base material layer 10A, there are 20 or more islands having a particle size of 100 nm or more and 3 μm or less in a 10 μm × 10 μm square. It is preferable that there are less than one.

In the present embodiment, the diameter of the island portion due to the aggregation of the electron conductive material means the maximum diameter of the island portion. The diameter of the islands of the electronically conductive material and the number of islands in a 10 μm × 10 μm square can be measured by observing the cross section of the conductive member, and the specific method is as follows.

The conductive member is cut along the thickness direction using a single-edged razor to cut out a cross section, and the cross section of the base material layer is observed with a scanning electron microscope (SEM). The maximum diameter of each island within one field of view was measured with the part with low contrast at the time of cross-sectional observation as the island.
FIG. 8 is an image obtained by measuring the cross section of the conductive member with a scanning electron microscope (SEM), and the low contrast position (white spot portion) is an agglomerated island portion of carbon black.
Further, for the conductive member, the number of islands is calculated in a 10 μm × 10 μm square by measuring the conductive path and the diameter of the islands, which will be described later.

From the viewpoint of suppressing the concentration of current in the sea area by applying a high voltage and suppressing the dielectric breakdown between islands, the island area where the electron conductive material aggregates has a particle size of 100 nm or more and 3 μm or less is 10 μm. It is preferable that the number is 20 or more and 50 or less in a square of × 10 μm square. It is preferably 25 or more and 40 or less.
Although some islands having a particle size of less than 100 nm may be present in the base material layer 10A, the area ratio of the islands made of the electronically conductive material having a particle size of 100 nm or more and 3 μm or less is 60% or more. It is preferably 80% or more, and it is particularly preferable that there are no islands of 100%, that is, less than 100 nm. Further, it is preferable that the island portion having a length of more than 3 μm does not exist because it may cause dielectric breakdown due to the concentration of the electric field on the island portion.

The electronically conductive material may be at least one selected from the group consisting of carbon black, pyrolyzed carbon, graphite, conductive metals or alloys, conductive metal oxides, and surface conductive treated insulating materials.
Specific examples of the electronically conductive material include carbon black such as Ketjen black and acetylene black; thermally decomposed carbon; graphite; various conductive metals or alloys such as aluminum, copper, nickel and stainless steel; tin oxide. , Indium oxide, titanium oxide, tin oxide-antimony oxide solid solution, tin oxide-indium oxide solid solution, and various other conductive metal oxides; examples thereof include those obtained by conductively treating the surface of an insulating material. The electron conductive material may be used alone or in combination of two or more.

Among these, carbon black is preferable from the viewpoint of suppressing environmental fluctuations in belt resistance. The carbon black has a pH of 5 or less (preferably pH 4.5 or less, more preferably pH 4.0) from the viewpoint of the stability of the electric resistance over time and the electric field dependence that suppresses the electric field concentration due to the transfer voltage. The oxidation-treated carbon black (for example, carbon black obtained by imparting a carboxyl group, a quinone group, a lactone group, a hydroxyl group, or the like to the surface) is preferable.

The average primary particle size of the electron conductive material is, for example, 35 nm or less (preferably 24 nm or less, more preferably 16 nm or less). When the average primary particle size of the electron conductive material is in this range, the electron conductive material is likely to aggregate to form islands having a particle size of 100 nm or more and 3 μm or less.
In particular, when the average primary particle size of carbon black is 24 nm or less, the conductive path due to carbon black is fine and uniform, and the decrease in resistance due to discharge deterioration on the belt surface is easily suppressed.
From the above viewpoint, the smaller the average primary particle size of carbon black is, the better, but if the primary particle size is too small, the bulk density becomes small and handling becomes difficult, and the specific surface area becomes large, so that the dispersion becomes thixotropy. It is preferably 10 nm or more (preferably 12 nm or more) because it exhibits properties.

The average primary particle size of carbon black is measured by the following method.
A measurement sample having a thickness of 200 nm is taken from the base material layer 10A of the conductive member by cutting with a microtome, and this measurement sample is observed by a TEM (transmission electron microscope). Then, the diameters of 50 primary particles of carbon black are measured, and the average value thereof is taken as the average primary particle size.

The content of the electron conductive material in the base material layer 10A depends on the target resistance, but is 1% by mass or more and 50% by mass or less (preferably 10% by mass or more) with respect to the total components constituting the base material layer 10A. 40% by mass or less, more preferably 20% by mass or more and 30% by mass or less). By setting the content of the electronically conductive material in this range, the cumulative frequency in the range of resistance value of 11.5 LogΩ or more and 12.0 LogΩ or less is 50 or more and 300 or less among 8000 conductive paths in a square of 10 μm × 10 μm. Therefore, it becomes easy to satisfy the condition that the cumulative frequency in the range where the resistance value of the conductive path is less than 11.5 LogΩ is 200 or less. Further, for example, it becomes easy to have 20 or more and 50 or less islands having a particle size of 50 nm or more and 3 μm or less in a 10 μm × 10 μm square square, which is composed of an agglomerate of an electron conductive material.

Insulating or semi-conductive particles may be added to the base material layer 10A to adjust the volume resistivity of the base material layer 10A. For example, silica, zinc oxide (zinc white) and the like can be mentioned.

Further, the following compounding raw materials for rubber may be used for the base material layer 10A.
For example, as a filler, titanium oxide, magnesium oxide, calcium carbonate, calcium sulfate, etc., clay, talc, etc., and as a rubber chemical, a vulcanizing agent, a vulcanization accelerator, an antiaging agent, a plasticizer, a process oil, etc. Examples of the colorant include various pigments.
Further, an acid receiving agent, a reinforcing agent, etc. may be added.

The thickness of the base material layer 10A may be set according to the intended use. For example, in the case of the base material layer 10A of the transfer transfer belt, the thickness of the base material layer 10A is considered from the viewpoints of strength as the transfer transfer belt, suppression of permanent elongation change, prevention of breakage or tearing during belt polishing, surface smoothness, and the like. Is preferably 100 μm or more and 1000 μm or less, and more preferably 300 μm or more and 600 μm or less.

<Surface layer>
The surface layer 10B is a layer provided on the base material layer 10A as needed. The surface layer 10B is composed of, for example, a resin material and a conductive agent, and if necessary, is composed of other known additives.
The base material layer 10A made of rubber or the like is prone to wrinkles and discharge products generated by image formation are likely to adhere to the base material layer 10A, but the surface layer 10B is provided on the outer peripheral surface of the base material layer 10A. This makes it easier to suppress the generation of wrinkles and the adhesion of discharge products, toner, and the like.

(resin)
Examples of the resin constituting the surface layer 10B include polyurethane resin, polyester resin, and polyacrylic resin.

(Conducting agent)
The conductive agent contained in the surface layer 10B is not particularly limited. From the viewpoint of suppressing environmental fluctuations in belt resistance, an electronically conductive material is preferable, and specifically, carbon black is preferable.
The carbon black has a pH of 5 or less (preferably pH 4.5 or less, more preferably pH 4.0) from the viewpoint of the stability of the electric resistance over time and the electric field dependence that suppresses the electric field concentration due to the transfer voltage. The oxidation-treated carbon black (for example, carbon black obtained by imparting a carboxyl group, a quinone group, a lactone group, a hydroxyl group, or the like to the surface) is preferable.
The carbon black having a pH of 5 or less is the same as that described as the electronically conductive material of the base material layer 10A.

The content of the conductive agent in the surface layer 10B is selected according to the desired resistance. For example, it is 1% by mass or more and 50% by mass or less, preferably 2% by mass or more and 40% by mass or less, and more preferably 4% by mass or more and 30% by mass or less with respect to the total components constituting the layer.
The conductive agent in the surface layer 10B may be used alone or in combination of two or more.

The thickness of the surface layer 10B is, for example, preferably 2 μm or more and 30 μm or less, preferably 5 μm or more and 15 μm or less.

<Characteristics of conductive members>
(Cumulative frequency of resistance values in the conductive path)
The cumulative frequency in the range of resistance value (current value) of 11.5 LogΩ or more and 12.0 LogΩ or less (current value is 20 pA or more and 60 pA or less) in 10 μm × 10 μm square by conductive AFM measurement described later is 50 or more and 300 or less (current value). It is preferably 70 or more and 280 or less, and more preferably 90 or more and 250 or less).
The cumulative frequency in the range of the resistance value (current value) of the conductive path less than 11.5 LogΩ (current value exceeds 60 pA) is 200 or less (preferably 180 or less, more preferably 160 or less). The lower limit of the resistance value and the upper limit of the current value are not particularly limited. For example, the lower limit of the resistance value is 11.3 LogΩ or more, and the upper limit of the current value is 100 pA or less.
When the cumulative frequency of the resistance value (current value) of the conductive path is within the above range, the fluctuation of the electric resistance is suppressed even if a high voltage is repeatedly applied.

(Measurement of resistance value of conductive path and calculation of cumulative frequency)
The resistance value (current value) of the conductive path in the conductive member is measured by the following method.
A small piece (sample) is cut out from the conductive member, a conductive double-sided tape is attached to the surface of the sample, and then a sample from which static electricity has been removed is prepared. Conductive AFM measurement (manufactured by Digital Instruments) with a resolution of 512 x 512 in a grid pattern so that the measurement voltage of -5.0 V is applied to the surface of the sample and the range of 10 μm × 10 μm is measured in an almost uniform state in the atmosphere. , Using Nanosample IIIa + D3100). The number of measurement points of the conductive path is 8000. At this time, the point where a current of 3.0 pA or more flows through the probe and the conductive double-sided tape is defined as a conductive path (conductive site).
Image analysis of this conductive path is performed, and the number of conductive paths (adjacent conductive paths are collectively counted as one) is calculated.
After that, the frequency of each section of the resistance value (current value) is drawn from the side with the larger resistance value (the side with the smaller current value), and the resistance value of the conductive path when the current value is 20 pA or more and 60 pA or less is 11.5 LogΩ or more. The cumulative frequency in the range of 12.0 LogΩ or less and the cumulative frequency in the range of less than 11.5 LogΩ of the resistance value of the conductive path when the current value exceeds 60 pA are calculated.

(Surface resistivity and volume resistivity)
When the conductive member 10 according to the present embodiment is a transport transfer belt, the surface resistivity of the outer peripheral surface thereof is preferably 8.5 LogΩ / □ or more and 11.0 LogΩ / □ or less, and 10.0 LogΩ / □ or more 11 More preferably, it is 0.0 LogΩ / □ or less.
Further, when the conductive belt member 10 according to the present embodiment is a transport transfer belt, the overall volume resistivity is preferably 10.0 LogΩ · cm or more and 12.5 LogΩ · cm or less, and 10.0 LogΩ · cm or more. It is more preferably 11.6 LogΩ · cm or less. When the volume resistivity of the conductive belt member 10 according to the present embodiment is 10.0 LogΩ · cm or more, it is possible to suppress transfer defects at the edges of the paper caused by the inflow of current into the non-passing region. Yes, if it is 12.5 LogΩ · cm or less, it is possible to suppress a defect due to discharge generated as the transfer voltage increases.

The method for measuring the surface resistivity is as follows. Measurement is performed according to JIS K6911 (1995) using a circular electrode (for example, "UR probe" of Hi-Lester IP manufactured by Mitsubishi Yuka Co., Ltd.). The method of measuring the surface resistivity will be described with reference to the drawings. FIG. 3 is a schematic plan view (A) and a schematic cross-sectional view (B) showing an example of a circular electrode. The circular electrode shown in FIG. 3 includes a first voltage application electrode A and a plate-shaped insulator B. The first voltage application electrode A has a columnar electrode portion C and an inner diameter larger than the outer diameter of the columnar electrode portion C, and is a cylindrical ring-shaped electrode that surrounds the columnar electrode portion C at regular intervals. It includes a part D. A belt T is sandwiched between the columnar electrode portion C and the ring-shaped electrode portion D of the first voltage application electrode A and the plate-shaped insulator B, and the columnar electrode portion C and the ring-shaped electrode of the first voltage application electrode A are sandwiched between them. The current I (A) that flows when the voltage V (V) is applied to the part D is measured, and the surface resistance ρs (Ω / □) of the transfer surface of the belt T is calculated by the following formula. Here, in the following formula, d (mm) indicates the outer diameter of the columnar electrode portion C, and D (mm) indicates the inner diameter of the ring-shaped electrode portion D.
Formula: ρs = π × (D + d) / (D−d) × (V / I)
For the surface resistance, a circular electrode (UR probe of Hi-Lester IP manufactured by Mitsubishi Yuka Co., Ltd .: outer diameter Φ16 mm of columnar electrode portion C, inner diameter Φ30 mm, outer diameter Φ40 mm of ring-shaped electrode portion D) was used. The current value after applying a voltage of 500 V for 10 seconds under a 22 ° C./55% RH environment is obtained and calculated.

On the other hand, the volume resistivity is measured according to JIS K6911 (1995) using a circular electrode (for example, a UR probe of Hi-Lester IP manufactured by Mitsubishi Yuka Co., Ltd.). The method for measuring the volume resistivity will be described with reference to FIG. The measurement is performed with the same device as the surface resistivity. However, in the circular electrode shown in FIG. 3, a second voltage application electrode B'is provided instead of the plate-shaped insulator B at the time of measuring the surface resistivity. Then, the belt T is sandwiched between the columnar electrode portion C and the ring-shaped electrode portion D of the first voltage application electrode A and the second voltage application electrode B', and the columnar electrode portion C of the first voltage application electrode A is sandwiched between them. The current I (A) flowing when the voltage V (V) is applied between the second voltage application electrode B and the second voltage application electrode B is measured, and the volume resistance ρv (Ωcm) of the belt T is calculated by the following formula. Here, in the following formula, t indicates the thickness of the belt T.
Equation ρv = 19.6 × (V / I) × t
For the volume resistance, a circular electrode (UR probe of Hi-Lester IP manufactured by Mitsubishi Yuka Co., Ltd .: outer diameter Φ16 mm of columnar electrode portion C, inner diameter Φ30 mm, outer diameter Φ40 mm of ring-shaped electrode portion D) was used. The current value after applying a voltage of 500 V for 10 seconds under a 22 ° C./55% RH environment is obtained and calculated.

Further, 19.6 are electrodes coefficient for converting the resistivity, the outer diameter of the cylindrical electrode portion d (mm), than the thickness t (cm) of the sample, [pi] d ² / 4t represented by the formula Is calculated as. The thickness of the belt T is measured using an eddy current film thickness meter CTR-1500E manufactured by Sanko Electronics Co., Ltd.

The surface resistivity and volume resistivity of the conductive belt member 10 according to the present embodiment are controlled by the type of the ion conductive material, the type of the electron conductive material, the addition amount of the electron conductive material, and the like.

<Manufacturing method of conductive member>
The method for manufacturing the conductive member according to the present embodiment is not particularly limited. For example, in the case of manufacturing the conductive belt member 10 having the layer structure shown in FIG. 2, the base material layer 10A contains an ion conductive material. The structure may have a sea portion and an island portion composed of an agglomerate of an electron conductive material. For example, it can be produced by forming the base material layer 10A as described below and then forming the surface layer 10B on the outer peripheral surface of the base material layer 10A.
First, as the formation of the base material layer 10A, for example, a rubber composition containing a rubber material such as chloroprene rubber or EPDM, an electronically conductive material, a vulcanizing agent, a vulcanization accelerator, etc. is put into a Banbury mixer and kneaded. ..
Furthermore, the kneaded product sufficiently kneaded with a roll is molded into an endless belt shape by a tube crosshead extrusion molding machine, and the rubber composition formed into an endless belt shape is heated by pressurized steam in a vulcanization can. Vulcanize to form a base rubber. The obtained base material is put on the outside of the metal tube and the surface is polished to obtain an endless belt-shaped base material layer 10A.
The kneading of the rubber composition is not limited to the Banbury mixer, and examples thereof include a closed kneader such as a pressure kneader and an open kneader such as an open roll.

When the base material layer 10A is formed as described above, for example, after preparing a rubber composition in which EPDM and CB are kneaded in advance, another rubber material, an electronically conductive material, a vulcanizing agent, a vulcanization accelerator, etc. And kneading the rubber composition, the cumulative frequency in the range of resistance value 11.5 LogΩ or more and 12.0 LogΩ or less is 50 or more and 300 or less among 8000 conductive paths in a square of 10 μm × 10 μm square. A substrate layer 10A having a cumulative frequency of 200 or less in the range of resistance value less than 11.5 LogΩ can be obtained.
Then, in the base material layer 10A, aggregates of the electronically conductive material are easily formed. For example, an island portion having a particle size of 100 nm or more and 3 μm or less of the aggregates of the electronically conductive material is formed, and 10 μm × 10 μm square square. The number of the islands in the above is likely to be 20 or more and 50 or less. If necessary, the particle size of the agglomerates of the electronically conductive material in the rubber composition can be adjusted by passing the rubber composition through a mesh and sieving the agglomerates of the electronically conductive material.

The method of forming the surface layer 10B on the outer peripheral surface of the base material layer 10A is not particularly limited. For example, a coating liquid for forming a surface layer in which a resin and a conductive agent are dispersed is applied by a dip coating method, a spray coating method, or electrostatic coating. The surface layer 10B is formed by applying the coating on the base material layer 10A by a method, a roll coating method, or the like and then drying the coating.

The conductive belt member 10 according to the present embodiment primary transfers a toner image formed on the surface of an image holder (electrophotographic photosensitive member) to an intermediate transfer belt, and then secondarily transfers the toner image from the intermediate transfer belt to a recording medium such as paper. In the image forming apparatus to be transferred, the transfer transfer belt, which is arranged to face the intermediate transfer belt in the secondary transfer section and conveys the recording medium in the secondary transfer section, and the recording medium such as paper on which the toner image is transferred are conveyed. At the same time, the transfer transfer belt that conveys the recording medium in the transfer unit that directly transfers the toner image from the image holder to the recording medium, and the intermediate transfer in which the toner image formed on the surface of the image holder of the image forming apparatus is primarily transferred. It can be applied as various conductive belt members such as belts.

[Image forming device]
The image forming apparatus according to the present embodiment includes an image holder, a charging means for charging the surface of the image holder, and an electrostatic latent image forming means for forming an electrostatic latent image on the surface of the image holder. It has a developing means for developing the electrostatic latent image on the surface of the image holder with a developer containing toner to form a toner image, and a transfer belt composed of the conductive belt member according to the present embodiment. An image forming apparatus including a transfer means for transferring the toner image formed on the surface of the image holder to a recording medium, and a fixing means for fixing the toner image transferred to the recording medium.

When the image forming apparatus according to the present embodiment has a configuration for transferring the toner image formed on the image holder to the recording medium via the intermediate transfer belt, it is composed of the conductive belt member according to the present embodiment. The transfer belt is arranged in the secondary transfer section so as to face the intermediate transfer belt, and can be suitably used as a transfer transfer belt that conveys the recording medium and secondarily transfers the toner image. Alternatively, in a configuration in which the toner image formed on the surface of the image holder is directly transferred to the recording medium, the toner image formed on the surface of the image holder is arranged so as to face the image holder and conveys the recording medium. Can also be suitably used as a transfer transfer belt for transferring the toner to a recording medium.

The image forming apparatus according to the present embodiment is, for example, a normal monocolor image forming apparatus in which only a single color toner is stored in a developing apparatus, and a toner image held on an image holder is sequentially subjected to primary transfer to an intermediate transfer belt. Examples thereof include a repeating color image forming apparatus and a tandem type color image forming apparatus in which a plurality of image holders equipped with a developer for each color are arranged in series on an intermediate transfer belt.

FIG. 4 is a schematic configuration diagram showing an example of the image forming apparatus according to the present embodiment. The image forming apparatus shown in FIG. 4 is an image forming apparatus in which the conductive belt member according to the present embodiment is applied to a secondary transfer belt 116 (an example of a transport transfer belt).
As shown in FIG. 4, the image forming apparatus 100 according to the present embodiment is, for example, a so-called tandem system, around four image holders 101a to 101d made of electrophotographic photosensitive members, along the rotation direction thereof. The charging devices 102a to 102d, the exposure devices 114a to 114d, the developing devices 103a to 103d, the primary transfer devices (primary transfer rolls) 105a to 105d, and the image holder cleaning devices 104a to 104d are sequentially arranged. A static eliminator may be provided to remove the residual potential remaining on the surface of the image holders 101a to 101d after transfer.

The intermediate transfer belt 107 is supported by the support rolls 106a to 106d, the drive roll 111, and the opposing roll 108 while applying tension to form the transfer unit 107b. By these support rolls 106a to 106d, the drive rolls 111, and the opposing rolls 108, the intermediate transfer belt 107 is in contact with the surfaces of the image holders 101a to 101d, and the image holders 101a to 101d and the primary transfer rolls 105a to 105d are brought into contact with each other. And can be moved in the direction of arrow A. The portion where the primary transfer rolls 105a to 105d come into contact with the image holders 101a to 101d via the intermediate transfer belt 107 becomes the primary transfer portion, and the contact portion between the image holders 101a to 101d and the primary transfer rolls 105a to 105d is primary. A transfer voltage is applied.

As the secondary transfer device, the opposing roll 108 and the secondary transfer roll 109 are arranged to face each other via the intermediate transfer belt 107 and the secondary transfer belt 116. The secondary transfer belt 116 is supported by the secondary transfer roll 109 and the support roll 106e. While the recording medium 115 such as paper is in contact with the surface of the intermediate transfer belt 107, it moves in the direction of arrow B in the region sandwiched between the intermediate transfer belt 107 and the secondary transfer roll 109, and then passes through the fixing device 110. The portion where the secondary transfer roll 109 contacts the opposing roll 108 via the intermediate transfer belt 107 and the secondary transfer belt 116 becomes the secondary transfer portion, and the contact portion between the secondary transfer roll 109 and the opposing roll 108 is the secondary transfer portion. A transfer voltage is applied. Further, the intermediate transfer belt cleaning devices 112 and 113 are arranged so as to come into contact with the intermediate transfer belt 107 after transfer.

In the multicolor image forming apparatus 100 having this configuration, the image holder 101a is rotated in the direction of the arrow C, and the surface thereof is charged by the charging apparatus 102a, and then the first color is charged by the exposure apparatus 114a such as a laser beam. An electrostatic latent image is formed. The formed electrostatic latent image is developed (visualized) with a developer containing toner by a developing device 103a containing toner corresponding to the color to form a toner image. The developing devices 103a to 103d contain toners (for example, yellow, magenta, cyan, and black) corresponding to the electrostatic latent images of each color.

When the toner image formed on the image holder 101a passes through the primary transfer unit, it is electrostatically transferred (primary transfer) onto the intermediate transfer belt 107 by the primary transfer roll 105a. Subsequent primary transfer is performed by the primary transfer rolls 105b to 105d on the intermediate transfer belt 107 holding the toner image of the first color so that the toner images of the second color, the third color, and the fourth color are sequentially superimposed. Finally, a multicolored multiple toner image is obtained.

When the multilayer toner image formed on the intermediate transfer belt 107 passes through the secondary transfer unit, it is electrostatically collectively transferred to the recording medium 115 conveyed by the secondary transfer belt 116. The recording medium 115 on which the toner image is transferred is conveyed to the fixing device 110, heated and pressurized, or fixed by heating or pressurizing, and then discharged to the outside of the machine.

Residual toner is removed from the image holders 101a to 101d after the primary transfer by the image holder cleaning devices 104a to 104d. On the other hand, the intermediate transfer belt 107 after the secondary transfer is prepared for the next image forming process by removing the residual toner by the intermediate transfer belt cleaning devices 112 and 113.

(Image holder)
As the image holders 101a to 101d, known electrophotographic photosensitive members are widely applied. As the electrophotographic photosensitive member, an inorganic photosensitive member whose photosensitive layer is made of an inorganic material, an organic photosensitive member whose photosensitive layer is made of an organic material, or the like is used. In organic photoconductors, a function-separated organic photoconductor in which a charge generation layer that generates electric charge by exposure and a charge transport layer that transports electric charge are laminated, and a single layer that has a function of generating electric charge and a function of transporting electric charge. A type organic photoconductor is preferably used. Further, as the inorganic photoconductor, one in which the photosensitive layer is made of amorphous silicon is preferably used.

The shape of the image holder is not particularly limited, and a known shape such as a cylindrical drum shape, a sheet shape, or a plate shape is adopted.

(Charging device)
The charging devices 102a to 102d are not particularly limited, and for example, a contact type charger using a conductive roller, a brush, a film, a rubber blade, or the like, a scorotron charger using corona discharge, a corotron charger, or the like. Known chargers are widely applied. Of these, a contact type charger is preferable.

The charging devices 102a to 102d usually apply a direct current to the image holders 101a to 101d, but an alternating current may be further superimposed and applied.

(Exposure device)
The exposure devices 114a to 114d are not particularly limited, and for example, a light source such as a semiconductor laser beam, an LED (Light Emitting Diode) light, or a liquid crystal shutter light, or a light source thereof on the surface of the image holder 101a to 101d. A known exposure device is widely applied, such as an optical system device capable of exposing a predetermined image from a light source of the above through a polygon mirror.

(Developer)
The developing devices 103a to 103d are selected according to the purpose. For example, a known developer that develops a one-component developer or a two-component developer with or without contact using a brush, a roller, or the like can be mentioned.

(Primary transfer roll)
The primary transfer rolls 105a to 105d may be either single-layer or multi-layer. 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 mixed with foamed or non-foamed silicone rubber, urethane rubber, EPDM or the like.

(Image holder cleaning device)
The image holder cleaning devices 104a to 104d are for removing residual toner adhering to the surface of the image holders 101a to 101d after the primary transfer step. Used. Among these, it is preferable to use a cleaning blade. Examples of the material of the cleaning blade include urethane rubber, neoprene rubber, and silicone rubber.

(Secondary transfer roll)
The layer structure of the secondary transfer roll 109 is not particularly limited, but for example, in the case of a three-layer structure, it is composed of a core layer, an intermediate layer, and a coating layer that covers the surface thereof. The core layer is a foam such as silicone rubber, urethane rubber, or EPDM in which conductive particles are dispersed, and the intermediate layer is composed of these non-foams. Examples of the material of the coating layer include a tetrafluoroethylene-hexafluoropropylene copolymer, a perfluoroalkoxy resin, and the like. The volume resistivity of the secondary transfer roll 109 is preferably 10 ⁷ [Omega] cm or less. Further, a two-layer structure excluding the intermediate layer may be used.

(Opposite roll)
The counter roll 108 forms the counter electrode of the secondary transfer roll 109. The layer structure of the opposing roll 108 may be either a single layer or a multi-layer structure. 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 mixed with 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 made of the above rubber material is covered with a high resistance layer.

A voltage of 1 kV or more and 6 kV or less is usually applied to the core of the opposing roll 108 and the secondary transfer roll 109. Instead of applying a voltage to the core body of the opposing roll 108, a voltage may be applied to the electrically conductive electrode member and the secondary transfer roll 109 that are in contact with the opposing roll 108. Examples of the electrode member include a metal roll, a conductive rubber roll, a conductive brush, a metal plate, a conductive resin plate, and the like.

(Fixing device)
As the fixing device 110, for example, a known fixing device such as a thermal roller fixing device, a pressure roller fixing device, or a flash fixing device is widely applied.

(Intermediate transfer belt cleaning device)
As the intermediate transfer belt cleaning devices 112 and 113, in addition to the cleaning blade, brush cleaning, roll cleaning, or the like is used. Among these, it is preferable to use the cleaning blade. Examples of the material of the cleaning blade include urethane rubber, neoprene rubber, and silicone rubber.

FIG. 5 is a schematic configuration diagram showing another example of the image forming apparatus according to the present embodiment. The image forming apparatus shown in FIG. 5 is an image forming apparatus in which the conductive belt member according to the present embodiment is applied to the transfer transfer belt 206.

In the image forming apparatus shown in FIG. 5, the units Y, M, C, and BK are provided with the photoconductor drums 201Y, 201M, 201C, and 201BK, respectively, so as to rotate in the clockwise direction of the arrow. Around the photoconductor drums 201Y, 201M, 201C, 201BK, there are chargers 202Y, 202M, 202C, 202BK, exposure devices 203Y, 203M, 203C, 203BK, and each color developing device (yellow developing device 204Y, magenta developing device 204M). , Cyan developing device 204C, black developing device 204BK), and photoconductor drum cleaning members 205Y, 205M, 205C, 205BK, respectively.

Four units Y, M, C, and BK are arranged in parallel with respect to the transfer transfer belt 206 in the order of units BK, C, M, and Y, but the order of units BK, Y, C, and M, etc. An appropriate order is set according to the image forming method.

The transfer transfer belt 206 is supported by the belt support rolls 210, 211, 212, 213 while applying tension from the inner surface side to form the transfer unit 220. The transfer transfer belt 206 rotates in the counterclockwise direction of the arrow at the same peripheral speed as the photoconductor drums 201Y, 201M, 201C, and 201BK, and is a part thereof located between the belt support rolls 212 and 213. Are arranged so as to be in contact with the photoconductor drums 201Y, 201M, 201C, and 201BK, respectively. The transport transfer belt 206 is provided with a belt cleaning member 214.

The transfer rolls 207Y, 207M, 207C, and 207BK are arranged at positions inside the transfer transfer belt 206 and facing the portions where the transfer transfer belt 206 and the photoconductor drums 201Y, 201M, 201C, and 201BK are in contact with each other. , Photoreceptor drums 201Y, 201M, 201C, 201BK and a transfer region for transferring the toner image to the paper (transferred body) 216 via the transfer transfer belt 206 are formed. As shown in FIG. 2, the transfer rolls 207Y, 207M, 207C, and 207BK may be arranged directly under the photoconductor drums 201Y, 201M, 201C, and 201BK, or may be arranged at positions deviated from the directly below.

The fixing device 209 is arranged so as to be transported after passing through the respective transfer regions of the transfer transfer belt 206 and the photoconductor drums 201Y, 201M, 201C, and 201BK.

The paper transport roll 208 transports the paper 216 to the transport transfer belt 206.

In the image forming apparatus shown in FIG. 5, in the unit BK, the photoconductor drum 201BK is rotationally driven. In conjunction with this, the charger 202BK is driven to charge the surface of the photoconductor drum 201BK to the desired polarity and potential. The photoconductor drum 201BK whose surface is charged is then exposed to an image by the exposure device 203BK, and an electrostatic latent image is formed on the surface thereof.

Subsequently, the electrostatic latent image is developed by the black developing apparatus 204BK. Then, a toner image is formed on the surface of the photoconductor drum 201BK. The developer at this time may be a one-component type or a two-component type.

This toner image passes through the transfer region between the photoconductor drum 201BK and the transfer transfer belt 206, and the paper 216 is electrostatically attracted to the transfer transfer belt 206 and conveyed to the transfer region, and is applied from the transfer roll 207BK. By the electric field formed by the transfer bias, the paper is sequentially transferred to the surface of the paper 216.

After that, the toner remaining on the photoconductor drum 201BK is cleaned and removed by the photoconductor drum cleaning member 205BK. Then, the photoconductor drum 201BK is used for the next image transfer.

The above image transfer is also performed in units C, M and Y by the above method.

The paper 216 on which the toner image is transferred by the transfer rolls 207BK, 207C, 207M and 207Y is further conveyed to the fixing device 209 for fixing.
As a result, the desired image is formed on the paper.

[Transfer unit]
The transfer unit for an image forming apparatus of the present embodiment (hereinafter, also simply referred to as “transfer unit”) is a state in which a transfer belt composed of the conductive belt member according to the present embodiment and the transfer belt are tensioned. It has multiple rolls to be hung in.

As the transfer unit, for example, a conductive belt member and a plurality of rolls in which the conductive belt member is hung under tension, and at least one of the plurality of rolls has a pair of regulating members. And may be provided. For example, in an image forming apparatus to which this transfer unit is applied, even when the conductive belt member meanders and the conductive belt member comes into contact with the restricting member of the roll and a mechanical load is applied, the conductive belt member is conductive. The belt member is likely to suppress the occurrence of breakage.

In the transfer unit according to the present embodiment, when the conductive belt member according to the present embodiment is applied as a transfer transfer belt, the surface or intermediate transfer belt of the photoconductor (image holder) is used as a roll for supporting the conductive belt member. A roll for transferring the toner image on the surface of the surface to the conductive belt member may be arranged. Further, other members may be arranged. The number of rolls that support the conductive belt member is not limited, and may be arranged according to the usage mode. The transfer unit having the above configuration is used by being incorporated in an image forming apparatus.

For example, as an example of the transfer unit according to the present embodiment, the transfer unit shown in FIG. 6 may be used. FIG. 6 is a schematic perspective view showing an example of the transfer unit. As shown in FIG. 6, the transfer unit 330 includes a conductive belt member 310, a winding roll 334, a drive roll 336, and a steering mechanism 370. The conductive belt member 310 is wound around the winding roll 334, the drive roll 336, and the steering roll 372 constituting the steering mechanism 370 in a tensioned state.

The steering mechanism 370 has a function of limiting the axial movement of the drive roll 336 of the conductive belt member 310 that is circulated by the drive roll 336. As shown in FIG. 6, the steering mechanism 370 includes a steering roll 372, a pair of slide bearings 374, a pair of tension springs 376, a pair of contact members 378, and a pair of guides 384 (an example of a regulating member). It is configured to include. The steering roll 372 is designed so that the conductive belt member 310 is wound around the steering roll 372 and rotates around the axis.

The steering roll 372 includes a shaft (not shown), a cylinder 382, and a pair of guides 384. The cylinder 382 is fixed to the outer circumference of the shaft. Each guide 384 is fixed to the outer circumference of the shaft while being in contact with each end surface of the cylinder 382 in a state where the surfaces on the large diameter side face each other. Then, when the end portion pushes the guide 384 due to the belt meandering, the guide 384 hits the pair of contact members 378, and the steering roll 372 tilts to reduce the degree of meandering. The steering roll 372 continues to rotate when the meandering forces in the opposite direction are balanced.

The pair of slide bearings 374 rotatably support the steering roll 372 around the axis at both ends of the steering roll 372. The pair of tension springs 376 support the pair of slide bearings 374 in a tensioned state. The steering roll 372 can be moved and tilted with respect to, for example, the drive roll 336 due to vibration, meandering, or the like accompanying the rotation of the conductive belt member 310.

The conductive member according to the present embodiment has been described mainly by taking a transfer transfer belt as an example. However, the conductive member according to the present embodiment is not limited to the belt as long as it is a conductive member in the image forming apparatus, for example. It can also be applied to charged members, transfer rolls, and the like.

Hereinafter, examples of the present invention will be specifically described, but the present invention is not limited to the following examples. In the following description, unless otherwise specified, "parts" and "%" are all based on mass.

<Example 1>
(Making base rubber)
A rubber composition was prepared by blending each component in the ratio of the following rubber blending 1.
-Rubber formulation 1-
EPDM: (Ethethylene propylene diene rubber, EP33 manufactured by JSR) 35 parts CR: (Chloroprene rubber, TSR-61 manufactured by Toso) 35 parts ECO: (Epichlorohydrin rubber, 610 manufactured by Daiso) 15 parts NBR: (Nitrile butadiene Rubber, DN211 manufactured by Nippon Zeon Co., Ltd. 15 parts Electronic conductive material: CB (carbon black, manufactured by Mitsubishi Chemical Co., Ltd. # 3030B) 23 parts Sulcanization: (manufactured by Tsurumi Chemical Co., Ltd.) 0.5 parts ZnO: (manufactured by Kyodo Chemical Co., Ltd.) 5 parts Vulcanization accelerator: (manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., Noxeller M) 1 part Stealic acid: 0.5 parts

The composition of the rubber formulation 1 was put into a Banbury mixer and kneaded, and then the rubber composition was kneaded with two rolls. The obtained kneaded product was molded into an endless belt shape by a tube crosshead extrusion molding machine.
Next, the rubber composition formed into an endless belt shape was vulcanized by heating with pressurized steam (temperature 126 ° C., pressure 1.5 kg / cm ² ) in a vulcanizing can to form a base rubber. .. The obtained base rubber was put on the outside of the metal tube, and the surface was polished to prepare an endless belt-shaped base rubber layer (diameter 40 mm, width 340 mm, thickness 492 μm).

(Preparation of surface layer)
A coating liquid for forming a surface layer was prepared by blending 20 parts by mass of carbon black "FW200" manufactured by Orion Engineered Carbons Co., Ltd. with 100 parts by mass of silicon-modified acrylic urethane (JYL841 manufactured by Nippon Achison Co., Ltd.).
A coating liquid for forming a surface layer was spray-coated on the surface of the prepared base rubber layer, and then heat-dried at 180 ° C. for 30 minutes to form a surface layer (thickness: 8 μm).
By the above method, a conductive belt member having a diameter of 40 mm, a width of 340 mm, and a thickness of 500 μm was produced.

<Example 2 and Comparative Examples 1 to 3>
A conductive belt member was produced in the same manner as in Example 1 except that the composition of the rubber composition and the kneading method were changed according to Table 1.

[evaluation]
The following measurements and evaluations were performed on the conductive belt members obtained in each example.

<Measurement of resistance value (current value) of conductive path>
The measurement was performed according to the method described above.

<Measurement of volume resistivity>
The volumetric resistance value of the conductive belt member obtained in each example was measured according to JIS K6911 (1995) using a circular electrode (for example, a UR probe of Hi-Lester IP manufactured by Mitsubishi Yuka Co., Ltd.).
The volume resistivity was calculated by using a circular electrode (UR probe of Hi-Lester IP manufactured by Mitsubishi Yuka Co., Ltd.) to obtain the current value after applying a voltage of 500 V for 10 seconds under a 22 ° C./55% RH environment. ..
The volume resistivity is calculated by converting the measured volume resistivity into the electrode area and thickness.

<Measurement of volume resistance before and after energization test>
-Energization test-
The conductive belt member obtained in each example is put on the outside of the metal tube, the electrode of the metal pipe is provided on the counter electrode, and the metal tube is rotated at a speed of 530 mm / s in an environment of 10 ° C. and 15% RH. Then, using a high-voltage power supply (610C manufactured by Trek), the voltage was adjusted so that a current of −120 μA flowed through the opposite metal pipe, and the voltage was applied continuously for 120 hours.
-Measurement of volume resistance value-
The change in volume resistance before and after the test was measured by the above resistance measuring method, and the amount of change in resistance due to energization was calculated.

<Image quality evaluation>
The obtained conductive belt member was attached to "Color 1000 Press" manufactured by Fuji Xerox Co., Ltd. as a transfer transfer belt, and the paper (A3J paper basis weight 82 g / m ² paper thickness 97 μm) under an environment of 10 ° C. and 15% RH. (Fuji Xerox Co., Ltd.)), 100 consecutive halftone images with an image density of 200% were formed. The image quality of the obtained image was evaluated as follows.
The image quality evaluation was performed before the above-mentioned energization test and after the energization test, respectively.

The evaluation criteria are as follows.
A: No color unevenness on the image B: Minor color unevenness C: Partial color unevenness and color loss D: Color unevenness and color loss on the entire image

10 Conductive belt member (conductive member)
10A base material layer (conductive layer)
10B Surface layer 100 Image forming apparatus 101a to 101d Image holders 102a to 102d Charging apparatus (charging means)
103a to 103d, 204Y, 204M, 204C, 204BK developing equipment (development means)
104a to 104d Image holder cleaning device 105a to 105d Primary transfer roll (transfer means)
106a to 106e Support roll 107 Intermediate transfer belt 108 Opposing roll 109 Secondary transfer roll (transfer means)
110, 209 Fixing device (fixing means)
111 Drive rolls 112, 113 Intermediate transfer belt cleaning device 114a to 114d Exposure device (latent image forming means)
115 Recording medium 116 Secondary transfer belt (conductive member)
201Y, 201M, 201C, 201BK Photoreceptor drum (image holder)
202Y, 202M, 202C, 202BK Charger (charging means)
203Y, 203M, 203C, 203BK Exposed device (latent image forming means)
205Y, 205M, 205C, 205BK Photoreceptor drum cleaning member 206 Recording medium transfer transfer belt 207Y, 207M, 207C, 207BK Transfer roll (transfer means)
214 Belt cleaning member 216 Paper (recording medium)
220, 330 transfer unit

Claims (7)

It has a sea part containing an ionic conductive material and an island part composed of an aggregate of an electronically conductive conductive material, and 10 μm × 10 μm is selected in a grid pattern with a resolution of 512 × 512. Of the 8000 paths, the layer in which the cumulative frequency in the range of resistance value 11.5 LogΩ or more and 12.0 LogΩ or less is 50 or more and 300 or less, and the cumulative frequency in the range of resistance value less than 11.5 LogΩ of the conductive path is 200 or less. A conductive member for an endless belt-shaped image forming apparatus. The conductive member for an image forming apparatus according to claim 1, wherein the ionic conductive material is a rubber material. The conductive member for an image forming apparatus according to claim 1 or 2, wherein the electronically conductive conductive material is carbon black. A transfer belt composed of the conductive member for an image forming apparatus according to any one of claims 1 to 3.
A plurality of rolls that hang the transfer belt under tension, and
A transfer unit for an image forming apparatus equipped with. The transfer unit for an image forming apparatus according to claim 4 , wherein the transfer belt is a recording medium transfer transfer belt that conveys the recording medium in a transfer unit in which a toner image is transferred to the recording medium. Image holder and
A charging means for charging the surface of the image holder and
An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the image holder,
A developing means for developing the electrostatic latent image on the surface of the image holder with a developer containing toner to form a toner image, and
It has a transfer belt made of the conductive member for an image forming apparatus according to any one of claims 1 to 3, and transfers the toner image formed on the surface of the image holder to a recording medium. Transfer means to be
A fixing means for fixing the toner image transferred to the recording medium, and
An image forming apparatus equipped with. The image forming apparatus according to claim 6 , wherein the transfer belt is a recording medium transfer transfer belt that conveys the recording medium in a transfer unit in which the toner image is transferred to the recording medium.

Images