JP2021092616A - Intermediate transfer body and electro-photographic image formation apparatus - Google Patents

Abstract

To provide an intermediate transfer body and electro-photographic image formation apparatus which can efficiently improve the dielectric constant while suppressing the reduction in the intensity.SOLUTION: An intermediate transfer body according to the present invention includes at least a base material layer. The relative dielectric constant at a frequency of 1 MHz is within a range of 10-100. There is formed a co-continuous structure in which a resin phase 1 and a resin phase 2 exist and the resin phase 1 and the resin phase 2 exist as mutually-continuous phases in a unit area of 100 μm2 when observing a cross section of the base material layer at at least 1000 magnification or greater using an electron microscope. The resin phase 1 contains a ferrodielectric substance within a range of 10-70 vol.% with respect to the entire resin phase 1. The resin phase 2 contains a conductor within a range of 1-20 vol.% with respect to the entire resin phase 2.SELECTED DRAWING: Figure 1

Description

The present invention relates to an intermediate transfer body and an electrophotographic image forming apparatus, and in particular, an intermediate transfer body and an electrophotographic image capable of efficiently improving the dielectric constant while suppressing a decrease in strength and having excellent uneven paper transferability. Regarding an image forming apparatus.

Conventionally, as an electrophotographic image forming apparatus using an intermediate transfer body (also referred to as an intermediate transfer belt), a toner image formed on a photoconductor is primaryly transferred to the intermediate transfer body, and the toner on the intermediate transfer body is transferred. It is known that an image is secondarily transferred to a transfer material such as transfer paper (recording paper). That is, after the toner image formed on the photoconductor, which is charged to a predetermined polarity, is transferred to the intermediate transfer body by using electrostatic force, the toner image of the intermediate transfer body is transferred by using electrostatic force. Transfer onto the material.

An image forming apparatus using such an intermediate transfer body sequentially superimposes toner images formed on each photoconductor on the intermediate transfer body by utilizing electrostatic force, and further, collectively superimposes the superimposed toner images on a transfer material. Since it can be transferred, it is widely used as a color image forming apparatus.

It is known that by increasing the dielectric constant of the intermediate transfer body, the voltage applied to the intermediate transfer body is reduced, and the voltage is applied to the toner by that amount to improve the electric field strength. In order to improve the dielectric constant of the intermediate transfer material, it is effective to add a highly dielectric material to the intermediate transfer material, and it is common to add a ferroelectric substance in particular.
For example, as disclosed in Patent Document 1, a technique of adding a ferroelectric substance to an intermediate transfer material to improve transferability is known. The dielectric constant of such a technique is about 10 to 20, but in recent years, it has been required to deal with various media such as uneven paper, and it is necessary to further increase the dielectric constant.

Ferroelectrics are effective as a means for improving the dielectric constant because of their high dielectric constant. When used for a resin belt such as an intermediate transfer material, it is common to disperse the ferroelectric substance and make a prototype. In such a case, in order to improve the performance of the intermediate transfer body, it is effective to add 20% by volume or more of the ferroelectric substance to the entire intermediate transfer body.
However, in the method of improving the dielectric constant by adding 20% by volume or more of the ferroelectric substance and dispersing it as described above, the strength is lowered and it is difficult to secure the durability of the intermediate transfer material.

Japanese Unexamined Patent Publication No. 8-152759

The present invention has been made in view of the above problems and situations, and the problem to be solved is that the dielectric constant can be efficiently improved while suppressing the decrease in strength, and the intermediate paper has excellent transferability. It is to provide a transfer body and an electrophotographic image forming apparatus.

In order to solve the above problems, the present inventor has set the relative permittivity within a specific range in the process of examining the cause of the above problems, and when the substrate layer is cross-sectionally observed, a resin containing a ferroelectric substance. A phase 1 and a resin phase 2 containing a conductor are present, and the resin phase 1 and the resin phase 2 form a co-continuous structure in which they are present as continuous phases, respectively, and a ferroelectric substance in the resin phase 1 is formed. By defining the content of the conductor and the content of the conductor in the resin phase 2, the dielectric constant can be efficiently improved in the thickness direction of the intermediate transfer material, and the uneven paper transferability is excellent. I found it and came up with the present invention.
That is, the above-mentioned problem according to the present invention is solved by the following means.

1. 1. An intermediate transcript having at least a substrate layer,
The relative permittivity at a frequency of 1 MHz is in the range of 10 to 100.
When the substrate layer is cross-sectionally observed with an electron microscope at a magnification of at least 1000, the resin phase 1 and the resin phase 2 are present in a unit area of ^{100 μm 2, and the resin phase 1 and the resin phase 2 are present.} They form co-continuous structures that exist as continuous phases with each other.
The resin phase 1 contains a ferroelectric substance in the range of 10 to 70% by volume with respect to the entire resin phase 1.
An intermediate transfer material, wherein the resin phase 2 contains a conductor in the range of 1 to 20% by volume with respect to the entire resin phase 2.

2. The intermediate transfer material according to item 1, wherein the resin phase 1 is continuously present from the front surface to the back surface in the thickness direction of the base material layer.

3. 3. The intermediate transfer body according to the first or second paragraph, which has a surface layer on the outermost surface of the intermediate transfer body.

4. The intermediate transfer product according to any one of items 1 to 3, wherein the thickness of the intermediate transfer material is in the range of 50 to 100 μm.

5. The intermediate transfer material according to any one of items 1 to 4, wherein the ferroelectric substance is either barium titanate or strontium titanate.

6. The intermediate transfer material according to any one of items 1 to 5, wherein the resin phase 1 and the resin phase 2 contain at least any one of polyimide, polyamide, and polyacetal.

7. The intermediate transfer material according to any one of items 1 to 6, wherein the conductor is any of carbon black, carbon nanotubes, and graphene.

8. An electrophotographic image forming apparatus comprising the intermediate transfer member according to any one of items 1 to 7.

According to the above means of the present invention, it is possible to provide an intermediate transfer body and an electrophotographic image forming apparatus which can efficiently improve the dielectric constant while suppressing a decrease in strength and have excellent transferability on uneven paper.
Although the mechanism of expression or mechanism of action of the effect of the present invention has not been clarified, it is inferred as follows.
When the transfer region is considered as a circuit, it is effective to increase the transfer electric field in order to increase the mobility of the toner. However, simply increasing the voltage causes noise such as discharge. In order to increase the transfer electric field at a desired voltage, it is effective to increase the partial pressure applied to the toner layer. In order to change the partial pressure, it is effective to change the resistance and capacitance of the members in the circuit, but in the case of a constant voltage, changing the resistance causes insufficient current, resulting in transfer failure.
Therefore, it is effective to increase the capacitance of the intermediate transfer material. Since "capacitance = relative permittivity x film thickness", increasing the relative permittivity (within the range of 10 to 100) temporarily increases the transfer electric field to the toner layer and improves transferability. Then it is inferred.
Further, in order to increase the relative dielectric constant, in the base material layer, the region where the ferroelectrics exist at high density and the region where the conductor exists are allowed to exist as continuous phases with each other. That is, a co-continuous structure in which the resin phase 1 and the resin phase 2 exist in a unit area of ^{100 μm 2} when the substrate layer is observed in cross section, and the resin phase 1 and the resin phase 2 each exist as continuous phases. The body is formed, the resin phase 1 contains a ferroelectric substance in the range of 10 to 70% by volume with respect to the entire resin phase 1, and the resin phase 2 is the entire resin phase 2. On the other hand, by containing the conductor in the range of 1 to 20% by volume, it is possible to efficiently develop the dielectric property in the thickness direction of the intermediate transfer material while suppressing the decrease in strength, and the unevenness can be exhibited. It is presumed that it has excellent paper transferability.

Schematic for explaining a co-continuous structure Conceptual cross-sectional view showing an example of the layer structure of the intermediate transfer member of the present invention. Schematic diagram showing the structure of the image forming apparatus of the present invention Block diagram showing the configuration of the image forming apparatus of the present invention Block diagram showing the configuration of the image forming apparatus of the present invention Schematic diagram for explaining the method of measuring the dielectric constant

The intermediate transfer material of the present invention is an intermediate transfer material having at least a base material layer, and the dielectric constant at a frequency of 1 MHz is in the range of 10 to 100, and the base material layer is used with an electron microscope. A co-continuous structure in which the resin phase 1 and the resin phase 2 are present in a unit area of ^{100 μm 2} when the cross section is observed at least at a magnification of 1000 or more, and the resin phase 1 and the resin phase 2 are respectively present as continuous phases. The body is formed, the resin phase 1 contains a ferroelectric substance in the range of 10 to 70% by volume with respect to the entire resin phase 1, and the resin phase 2 is the entire resin phase 2. It is characterized by containing a conductor in the range of 1 to 20% by volume.
This feature is a technical feature common to or corresponding to each of the following embodiments.

In an embodiment of the present invention, the resin phase 1 is continuously present from the front surface to the back surface in the thickness direction of the base material layer, so that the ferroelectric substance contained in the resin phase 1 is directly present between the electrodes. It is preferable because it tends to be in contact with each other and the dielectric constant can be improved most effectively.

Further, it is preferable to have a surface layer on the outermost surface of the intermediate transfer material because the transferability can be improved.

It is preferable that the thickness of the intermediate transfer body is in the range of 50 to 100 μm in terms of improvement of transfer efficiency and strength of the intermediate transfer body.

It is preferable that the ferroelectric substance is either barium titanate or strontium titanate in that transferability can be improved.

It is preferable that the resin phase 1 and the resin phase 2 contain at least any one of polyimide, polyamide or polyacetal from the viewpoint of ensuring strength and durability.

It is more preferable that the conductor is any of carbon black, carbon nanotubes, or graphene in terms of making the intermediate transfer material conductive and easy to handle.

The intermediate transfer member of the present invention is suitably used for an electrophotographic image forming apparatus.

Hereinafter, the present invention, its constituent elements, and modes and modes for carrying out the present invention will be described. In the present application, "~" is used to mean that the numerical values described before and after the value are included as the lower limit value and the upper limit value.

[Overview of the intermediate transcript of the present invention]
In the intermediate transfer material of the present invention, the resin phase 1 and the resin phase 2 are present in a unit area of ^{100 μm 2} when the substrate layer is cross-sectionally observed with an electron microscope at a magnification of at least 1000 and the resin. The phase 1 and the resin phase 2 each form a co-continuous structure in which they exist as continuous phases, and the resin phase 1 contains a ferroelectric substance in the range of 10 to 70% by volume with respect to the entire resin phase 1. It is characterized in that the resin phase 2 contains a conductor in the range of 1 to 20% by volume with respect to the entire resin phase 2.

<Relative permittivity>
The intermediate transfer material of the present invention has a relative permittivity at a frequency of 1 MHz in the range of 10 to 100 under an environment of a temperature of 23 ° C. and a humidity of 50% RH.
When the relative permittivity is 10 or more, it is easy to increase the transfer electric field, which is preferable. On the other hand, when the relative permittivity is 100 or less, the adhesive force between the toner and the intermediate transfer body does not become too large, and the transfer efficiency does not decrease, which is preferable. The relative permittivity is more preferably in the range of 20 to 50, and particularly preferably in the range of 30 to 40.
The relative permittivity refers to the relative permittivity of the entire intermediate transfer body (for example, in the case of having a surface layer or an elastic layer, the entire intermediate transfer body including each of these layers).

The relative permittivity can be calculated by the following method.
The permittivity of the intermediate transfer material is measured. Specifically, as shown in FIG. 6, a thin film electrode 201 having a resistance of one digit Ω is formed on both sides of the intermediate transfer body 87a by sputtering or the like, and cut out with a mold of 10 mmφ to prepare a measurement sample, and an impedance analyzer “ The dielectric constant (F / m) was measured by the electrode contact method in an environment of a temperature of 23 ° C. and a humidity of 50% RH under the condition of a frequency of 1 Hz to 1 MHz using a “12608 W type” (manufactured by Solartronic Analytical Co., Ltd.). , Converted to relative permittivity.

<Method of observing the cross section of the base material layer>
As a method for observing the cross section of the base material layer, platinum-palladium was sputtered on the sample surface of the base material layer as a pretreatment. Specifically, after being inserted into the sputtering apparatus, the measurement surface was thinly coated by the sputtering method, then inserted into the measuring apparatus, evacuated, and the acceleration voltage was observed at 5 kV. Then, using a transmission electron microscope "2000FX" (manufactured by JEOL Ltd.), the observation was performed at a magnification of 100 times, 5000 times, and 10000 times.

In the present invention, when the base material layer is cross-sectionally observed by the method described above, the resin phase 1 and the resin phase 2 are present in a unit area of ^{100 μm 2, and the resin phase 1 and the resin phase 2 are mutually present.} It forms a co-continuous structure that existed as a continuous phase.
In the present invention, as shown in FIG. 1, the "co-continuous structure" means that the resin phase 1 (R1) is three-dimensionally and continuously connected by the composition constituting the resin phase 1 (R1). It is a continuous phase having a structure, and the resin phase 2 (R2) is also a continuous phase having a structure in which the resin phase 2 (R2) is three-dimensionally and continuously connected by the composition constituting the resin phase 2 (R2). It means that two continuous phases exist together.
Further, the continuous phase is a state in which all the compositions constituting the resin phase 1 (R1) or the resin phase 2 (R2) are continuously connected and have no cavity (there is no unconnected portion). Is preferable.

Further, the resin phase 1 is continuously present from the front surface to the back surface of the thickness of the base material layer, so that the ferroelectric substance in the resin phase 1 is in direct contact between the electrodes, and the dielectric constant is effectively obtained. Is preferable in that the value can be increased. The resin phase 2 also preferably exists continuously from the front surface to the back surface of the thickness of the base material layer, but it does not have to be continuous.

The resin phase 1 contains a ferroelectric substance in the range of 10 to 70% by volume with respect to the entire resin phase 1. Preferably, it is in the range of 30 to 50% by volume.
Further, the resin phase 2 contains a conductor in the range of 1 to 20% by volume with respect to the entire resin phase 2. Preferably, it is in the range of 5 to 15% by volume.

The content of the ferroelectric substance in the resin phase 1 and the content of the conductor in the resin phase 2 are calculated as follows.
The total volume is set to 100% by volume, and the desired volume ratio of each material is set. After that, the required weight is calculated from the specific gravity of each material and mixed to complete each prescription liquid.

The area occupied by the high-dielectric region in the cross-sectional direction of 100 μm ² of the resin phase 1 is 50% or less from the viewpoint of ensuring strength, that is, the high-dielectric region ^{occupies 50 μm 2} or less.

Further, as a means for forming the co-continuous structure in the base material layer, a crystalline resin and an amorphous resin that are incompatible with each other are mixed in a mass ratio of 40 to 60:60 to 40. It can be formed by mixing, and it is particularly preferable to mix at 50:50.

[Layer structure of intermediate transcript]
FIG. 2 is a conceptual cross-sectional view showing an example of the layer structure of the intermediate transfer member of the present invention.
The intermediate transfer body 1a of the present invention has at least a base material layer 2a. The base material layer 2a contains a ferroelectric substance and a conductor.
The intermediate transfer body 1a may have a single-layer structure composed of only the base material layer 2a, but if necessary, layers such as the elastic layer 3a or the surface layer 4a are placed on the base material layer 2a in this order. It is also possible to have a configuration having the above.

The thickness of the intermediate transfer material can be appropriately determined depending on the purpose of use thereof and the like, but is preferably in the range of 50 to 100 μm. The thinner the thickness, the lower the voltage required for transfer, the more the discharge is suppressed, and the transfer efficiency is improved. Therefore, 100 μm or less is preferable. Further, if the thickness is 50 μm or more, the strength of the intermediate transfer material can be sufficiently maintained.

Electrical resistance of the intermediate transfer body (the volume resistivity) ^is preferably in the range of 10 5 ~10 ¹¹ Ω · cm. The electric resistance value can be controlled by the content of the conductor described later.
As for the shape of the intermediate transfer body, the intermediate transfer body having an endless structure does not have a thickness change due to superposition, and an arbitrary part can be set as the rotation start position of the intermediate transfer body, and the control mechanism of the rotation start position can be omitted. It has advantages and is preferable.

The surface resistivity of the intermediate transfer material (whole) is preferably in the range of ^{10 9} to ^{12 Ω · cm.}
The breaking stress of the intermediate transfer body (whole) is preferably 100 MPa or more, more preferably 120 MPa or more, and the breaking elongation is preferably 20% or more, more preferably 40% or more. By setting the breaking stress and breaking elongation within the above ranges, high crack resistance and high wear resistance can be obtained.
The breaking stress was measured in accordance with JIS K7161, and the breaking elongation was measured in accordance with JIS K7161.

<Base layer>
The base material layer according to the present invention contains a ferroelectric substance and a conductor. In particular, as described above, the resin phase 1 and the resin phase 2 are present in the base material layer, and the ferroelectric substance is contained in the range of 20 to 70% by volume with respect to the entire resin phase 1, and the resin phase 2 is present. It is contained in the range of 1 to 20% by volume based on the whole.

(Ferroelectric)
In the present invention, a ferroelectric substance is a kind of dielectric, and is a substance in which electric dipoles are aligned even if there is no electric field outside, and the direction of the dipoles can be changed by an electric field. In the present invention, the ferroelectric substance refers to a substance having a relative permittivity of 15 or more at a frequency of 1 MHz in an environment of a temperature of 23 ° C. and a humidity of 50% RH. Preferably, the relative permittivity is 20 or more, more preferably 100 or more. A higher dielectric constant is preferable from the viewpoint of exhibiting the effect of the present invention. The upper limit is constrained by the availability of materials.

Further, the state in which the electric dipole moments are spontaneously aligned in this way is called a ferroelectric state, and this property is called a ferroelectricity. Among the ferroelectric substances, in the present invention, ferroelectric ceramics are desirable as the ferroelectric material because of the load in the production process and the stability during aging, and barium titanate, calcium titanate, and strontium titanate are preferable. , Magnesium titanate, calcium zirconate and the like. Moreover, you may use these solid solutions as a ferroelectric substance.
Of these, as the ferroelectric substance according to the present invention, it is preferable to contain either barium titanate or strontium titanate in that transferability can be improved.

The method for producing barium titanate is not particularly limited, and for example, it can be produced by the method described in paragraphs 0033 to 0044 of Japanese Patent No. 6368246.
Specifically, an aqueous solution containing barium and titanium hydroxide is prepared, and the aqueous solution is subjected to a hydrothermal reaction under high temperature and high pressure conditions.
The temperature of the hydrothermal reaction is 200 ° C. or higher, preferably 200 to 450 ° C., more preferably 250 to 400 ° C., and the total pressure is 2 MPa or higher, preferably 2 to 50 MPa, more preferably 10 to 40 MPa, usually 0.1. The reaction may be carried out for a minute or more, preferably 0.1 to 1 hour, more preferably 0.1 to 30 minutes. A hydrothermal reaction is carried out under such high temperature and high pressure conditions to control the particle morphology such as the ratio value (c / a) and the average primary particle size. Then, after filtering and washing with water, the particles are dried and crushed to obtain barium titanate particles.
As a means for setting the value of the ratio and the average primary particle size according to the present invention into the above range, the type of raw material in the aqueous solution containing barium and titanium hydroxide, the Ba / Ti ratio, the amount of alkali, and the reaction scale. , Reaction temperature, reaction pressure, reaction time, etc. can be controlled.
The method for producing strontium titanate is not particularly limited, and the strontium titanate can be produced by the same method as barium titanate described above.

(Average primary particle size of ferroelectric particles)
The average primary particle size of the ferroelectric particles (referring to those in the state of fine particles of the ferroelectric substance) is preferably 300 nm or less in that the residual polarization can be reduced. The lower limit of the average primary particle size is 30 nm, more preferably 50 nm, and the optimum range is in the range of 90 to 110 nm.
For the measurement of the average primary particle size of the ferroelectric particles, 200 or more particles were randomly measured using a transmission electron microscope (TEM) (manufactured by Hitachi High-Tech), and the average value was obtained. When the shape of the particles is not spherical, the average value of the major axis and the minor axis can be calculated as the diameter of each particle.

Further, the ferroelectric substance according to the present invention preferably contains the ferroelectric substance in the range of 5 to 30% by volume with respect to the entire base material layer. When it is 5% by volume or more, there is a high dielectricing effect of the intermediate transfer material, that is, an effect of improving transferability. When it is 30% by volume or less, it can have the required mechanical strength.

(conductor)
The base material layer according to the present invention contains a conductor in addition to the ferroelectric substance.
In the present invention, the conductor is not particularly limited as long as it is a conductive substance. Specifically, as the conductor (conductive agent) used in the present invention, a known electronic conductive substance or ionic conductive substance can be used, and the conductor is carbon black, carbon nanotube, graphite or graphene. It is preferable that the intermediate transfer material has conductivity, and it is more preferable that the intermediate transfer material is made of carbon black, carbon nanotubes, or graphene in terms of ease of handling.
The amount of the conductor used in the present invention is preferably in the range of 0.1 to 20% by volume with respect to the entire base material layer. When it is 0.1% by volume or more, the toner is not contaminated on the surface of the base material layer, and when it is 20% by volume or less, the strength of the base material layer and the charge amount of the toner are not lowered, which is good. Is. More preferably, it is in the range of 0.5 to 15% by volume, and even more preferably, it is in the range of 1 to 10% by volume.

(Carbon black)
Examples of carbon black among the conductors include gas black, acetylene black, oil furnace black, thermal black, channel black, and Ketjen black. Effective methods for obtaining the desired conductivity with a smaller amount of mixing include Ketjen black, acetylene black and oil furnace black. Ketjen black is a contactive furnace type carbon black.

The average primary particle size of carbon black is preferably in the range of 10 to 50 nm. Within the range of the child, when the ferroelectric substance is coated with the conductor, it is easy to control the coverage ratio of the ferroelectric substance by the conductor to an appropriate value.
The average primary particle size can be measured by the method of FPAR-1000 (manufactured by Otsuka Electronics Co., Ltd.) using a photon counting method.

(carbon nanotube)
A carbon nanotube (hereinafter abbreviated as CNT) is a defect-free single-walled material having a structure in which a graphite hexagonal net plane is rolled into a tubular shape, or a multi-walled tubular material in which they are laminated in a nested manner. .. The average tube diameter of the CNTs contained in the intermediate transfer material of the present invention is preferably in the range of 10 to 150 nm, and the length of the CNTs is preferably in the range of 5 to 12 μm. By setting the diameter and length of the CNTs in the above ranges, appropriate conductivity can be imparted to the intermediate transfer material, and when the ferroelectric substance is coated, it can be efficiently coated.

This CNT may be covalently bonded to a functional group, if necessary. For example, a strong acid treatment of CNT produces oxidized CNT in which a carboxylic acid is introduced on the surface, and the oxidized CNT is reacted with thionyl chloride and then reacted with an alkyl alcohol or the like to dissolve in an organic solvent. CNT can be generated. By using such chemically decorated CNTs, the CNTs can be uniformly dispersed in the resin. Further, by applying an electric field from the outside with the CNTs dispersed in the resin, the CNTs can be oriented in a desired direction, and the dielectric constant of the intermediate transfer material can be improved.

The average tube system and the length can be obtained from a scanning electron microscope (SEM) photograph of the cross section of the intermediate transfer body, and are adjusted by cutting (grinding) CNTs or mixing two or more types of CNTs. It is possible.

(Graphite)
As the graphite used in the present invention, both natural products and artificial synthetic products can be used. It is difficult to unambiguously define the preferable particle size of graphite because the shape of graphite is scaly and the shape changes during the dispersion step during the production of the toner carrier, but it is difficult to unambiguously define it. The width (in the direction of the graphite fracture surface) is preferably 100 μm or less. As a measuring method, the sample is directly observed with a microscope and measured.

(Graphene)
Graphene is a sheet-like substance consisting of a planar hexagonal lattice structure of carbon atoms. The graphene sheet is flat graphene and is usually a single layer. Graphene sheets are artificial and are available as flaky powders. For example, it can be produced by a chemical vapor deposition (CVD) method.

The graphene sheet does not have to be completely single layer, and may partially include two or more layers. For this reason, graphene sheets have, for example, less than two layers. Further, the size is preferably less than 2 μm, and the thickness is preferably 2 nm or less. The graphene sheet laminate preferably has, for example, two or more layers, a size of 5 to 25 μm, and a thickness of 12 nm or less.

Commercially available products can be used for the graphene sheet and its laminate. The number, size and thickness of the graphene sheet and its laminate can be measured, for example, by a transmission electron microscope (TEM).

(resin)
The base material layer according to the present invention preferably contains the ferroelectric substance and the conductor in a dispersed state in the resin.
That is, when the substrate layer is cross-sectionally observed with an electron microscope at a magnification of at least 1000, the resin phase 1 and the resin phase 2 are present in a unit area of ^{100 μm 2, and the resin phase 1 and the resin phase 2 are present.} Form a co-continuous structure in which each of them exists as a continuous phase with each other, and the resin phase 1 contains a ferroelectric substance in the range of 10 to 70% by volume with respect to the entire resin phase 1. The resin phase 2 contains a conductor in the range of 1 to 20% by volume with respect to the entire resin phase 2.

As the resin constituting the resin phase 1 and the resin phase 2 according to the present invention, various resins can be used, but polyimide (PI), polyamide (PA), polyacetal (POM), polyamideimide (PAI), and the like. Super engineering plastics having strength and durability such as polyphenylene sulfide (PPS) and polyetheretherketone (PEEK) are desirable.

Among these, it is preferable to contain at least any one of polyimide, polyamide or polyacetal. Among them, polyimide is more preferable because it has excellent properties such as heat resistance, bending resistance, flexibility, and dimensional stability.
In particular, the resin phase 1 is preferably composed of polyimide (amorphous), and the resin phase 2 is preferably composed of polyacetal (crystalline).
The polyimide can be obtained, for example, by synthesizing a polyamic acid (polyimide precursor) from an acid anhydride and a diamine compound, and imidizing the polyamic acid by heat or a catalyst.

The acid anhydride used for the synthesis of polyimide is not particularly limited, and for example, biphenyltetracarboxylic acid dianhydride, terphenyltetracarboxylic acid dianhydride, benzophenone tetracarboxylic acid dianhydride, pyromellitic anhydride, and the like. Examples thereof include aromatic tetracarboxylic acid dianhydrides such as oxydiphthalic acid dianhydride, diphenylsulfone tetracarboxylic acid dianhydride, hexafluoroisopropyridene diphthalic acid dianhydride, and cyclobutane tetracarboxylic acid dianhydride.

The diamine compound used in the synthesis of polyimide is not particularly limited, but for example, p-phenylenediamine, m-phenylenediamine, 2,4-diaminotoluene, 4,4'-diaminodiphenylmethane, 4,4'. -Diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, 3,7 -Diamino-dimethyldibenzothiophene-5,5'-dioxide, 4,4'-diaminobenzophenone, 4,4'-bis (4-aminophenyl) sulfide, 4,4'-diaminobenzanilide, 1,4-bis Examples thereof include aromatic diamines such as (4-aminophenoxy) benzene.

The resin (whole resin) constituting the resin phase 1 and the resin phase 2 according to the present invention is preferably contained in the range of 50 to 95% by volume with respect to the entire base material layer. When it is 50% by volume or more, it can have the required mechanical strength. When it is 95% by volume or less, a space containing a ferroelectric substance or a conductor can be secured.

<Elastic layer>
The elastic layer used in the present invention is a layer having desired conductivity and elasticity that can be formed on the outer peripheral surface of the base material, if necessary.
The elastic layer is made of a rubber material. The thickness of the elastic layer is preferably within, for example, 50 to 400 μm.
Examples of rubber materials include resins having rubber elasticity such as urethane rubber, chloroprene rubber (CR) and nitrile rubber (NBR). The rubber material preferably contains chloroprene rubber or nitrile butadiene rubber from the viewpoint of controlling the electrical resistance of the intermediate transfer material.

<Surface layer>
If necessary, the surface layer (also referred to as “coating layer” or “surface layer”) is a layer that can be formed on the outer peripheral surface of the base material or the outer peripheral surface of the elastic layer, and has an effect of improving transferability.
The surface layer is other than the metal oxide fine particles (A), the (meth) acrylate monomer (B) having a refractive index nD in the range of 1.6 to 1.8, and the (meth) acrylate monomer (B). It is preferably obtained by irradiating the coating film of the coating liquid for forming a surface layer containing the active energy ray-curable composition containing the polyfunctional (meth) acrylate (C) of the above with active energy rays and curing the coating liquid. .. This makes it possible to improve the durability of the intermediate transfer material.
The thickness of the surface layer is preferably in the range of 2 to 20 μm, more preferably in the range of 1 to 5 μm in that cracking can be prevented, and is 1.5 to 2.5 μm. It is particularly preferable that it is within the range.

[Manufacturing method of intermediate transcript]
Next, a method for producing an intermediate transfer product having a base material layer according to the present invention will be described. The following production method is an example, and any method capable of producing an intermediate transcript can be used.
First, a dispersion liquid A in which ferroelectric particles are dispersed in a solvent is prepared. In addition, a dispersion liquid B in which the conductor is dispersed in a solvent is also prepared. Here, both the dispersion liquid A and the dispersion liquid B may use a dispersant to the extent that the dielectric constant and the mechanical properties are not affected.
The prepared dispersion liquid A and dispersion liquid B are mixed and dispersed with the resin of the polyimide varnish "Yupia-AT (U-varnish-A)" (manufactured by Ube Industries, Ltd.). At this time, the contents of the ferroelectric substance and the conductor are appropriately adjusted so as to be in a preferable range. The mixing / dispersing operation can be performed using a mixer or the like. The ferroelectric substance and, if necessary, the conductor may be mixed and dispersed in the polyimide varnish without preparing the dispersion liquid A and the dispersion liquid B.
A coating liquid for forming a base material layer can be prepared by the mixing / dispersing operation.

Next, while rotating the stainless steel cylindrical mold around the cylindrical shaft, the dispense nozzle is moved in the axial direction, and the coating liquid for forming the base material layer is discharged from the nozzle to discharge the coating liquid for forming the base material layer from the outer peripheral surface of the mold. It is applied spirally on top to form a coating that connects them.
Next, most of the solvent is volatilized by heating the cylindrical mold at 130 ° C. for 1 hour while rotating the mold, and then heating at 350 ° C. for 1 hour to form an endless belt-shaped base material layer. be able to. Then, this base material layer is processed to obtain an intermediate transfer material containing a ferroelectric substance and a conductor in the resin.
The intermediate transfer body may be prepared using only the base material layer prepared by the above method, or the intermediate transfer body may be prepared by bonding the elastic layer and the surface layer to the base material layer. A known method may be used for forming the elastic layer and the surface layer, and the method is not particularly limited.

[Electrophotograph image forming apparatus]
Next, an electrophotographic image forming apparatus including the intermediate transfer member of the present invention will be described.
The electrophotographic image forming apparatus of the present invention (hereinafter, also referred to as an image forming apparatus) is, for example, as shown in FIG. 3, 4 of yellow (Y), magenta (M), cyan (C), and black (K). A tandem image forming apparatus in which photoconductor drums 83Y, 83M, 83C, and 83K as photoconductors corresponding to colors are arranged in series in the traveling direction of the intermediate transfer body.

As shown in FIG. 4, the image forming apparatus 1 includes a control unit 10 composed of a CPU (Central Processing Unit) 11, a ROM (Read Only Memory) 12, a memory such as a RAM (Random Access Memory) 13, and the like. A storage unit 20 composed of an HDD (Hard Disk Drive), an SSD (Solid State Drive), etc., a network I / F unit 30 composed of a NIC (Network Interface Card), a modem, etc., and a touch panel or the like. A display operation unit 40, an image reading unit 50 composed of an ADF (Auto Memory Feeder) and a scanner, an image processing unit 60 composed of a RIP (Raster Image Processor), a transport unit 70, and an image forming unit. The image forming unit 80 that processes the paper conveyed from the conveying unit 70, including the 80 and the like, includes the intermediate transfer unit of the present embodiment.

As shown in FIG. 3, the transport unit 70 includes a paper feed device 71, a transport mechanism 72, a paper discharge device 73, and the like. The paper housed in the paper feeding device 71 is fed one by one from the uppermost portion, and is conveyed to the image forming unit 80 by a conveying mechanism 72 provided with a plurality of conveying rollers such as a resist roller. At this time, the resist portion on which the resist roller is arranged corrects the inclination of the fed paper and adjusts the transfer timing. Then, the paper on which the image is formed by the image forming unit 80 is discharged to the paper ejection tray outside the machine by the paper ejection device 73 provided with the paper ejection roller.

As shown in FIGS. 3 and 5, the image forming unit 80 includes an exposure apparatus 81 (81Y, 81M, 81C, 81K) and a developing apparatus 82 provided corresponding to different color components Y, M, C, and K. (82Y, 82M, 82C, 82K), Photoreceptor drum 83 (83Y, 83M, 83C, 83K), Charging device 84 (84Y, 84M, 84C, 84K), Cleaning device 85 (85Y, 85M, 85C, 85K), It is composed of a primary transfer roller 86 (86Y, 86M, 86C, 86K), an intermediate transfer unit 87, a fixing device 88, and the like. Each element will be outlined below. In the following description, symbols excluding Y, M, C, and K are used as necessary.

In the photoconductor drum 83 of each color component Y, M, C, K, an organic photoconductor layer (OPC) provided with an overcoat layer as a protective layer is formed on the outer peripheral surface of a cylindrical metal substrate made of an aluminum material. It is an image carrier. The photoconductor drum 83 is rotated counterclockwise in FIG. 3 by following the intermediate transfer body in a grounded state.

The charging device 84 for each of the color components Y, M, C, and K is a scorotron type, and is arranged close to the corresponding photoconductor drum 83 in a state in which the longitudinal direction thereof is along the rotation axis direction of the photoconductor drum 83. By corona discharge having the same polarity as the toner, a uniform potential is applied to the surface of the photoconductor drum 83.

The exposure apparatus 81 for each color component Y, M, C, K scans in parallel with the rotation axis of the photoconductor drum 83 by, for example, a polygon mirror, and is uniformly charged on the surface of the corresponding photoconductor drum 83. An electrostatic latent image is formed by performing image exposure based on the image data.

The developing device 82 of each color component Y, M, C, K contains a two-component developer composed of a toner having a small particle size of the corresponding color component and a magnetic material, and the toner is applied to the surface of the photoconductor drum 83. The electrostatic latent image carried on the photoconductor drum 83 is visualized with toner.

The primary transfer roller 86 of each color component Y, M, C, K presses the intermediate transfer body of the present embodiment against the photoconductor drum 83, and sequentially superimposes each color toner image formed on the corresponding photoconductor drum 83 in the middle. Primary transfer to the transcript.

The cleaning device 85 for each of the color components Y, M, C, and K recovers the residual toner remaining on the corresponding photoconductor drum 83 after the primary transfer. Further, a lubricant application mechanism (not shown) is provided adjacent to the photoconductor drum 83 of the cleaning device 85 in the rotation direction, and the lubricant is applied to the photosensitive surface of the corresponding photoconductor drum 83. There is.

The intermediate transfer unit 87 includes an endless intermediate transfer body 87a to be transferred, a support roller 87b, a secondary transfer roller 87c, an intermediate transfer cleaning unit 87d, and the like, and the intermediate transfer body 87a is stretched on a plurality of support rollers 87b. It is constructed by being hung. When the intermediate transfer body 87a on which the toner images of each color are first transferred by the primary transfer rollers 86Y, 86M, 86C, and 86K is pressed against the paper by the secondary transfer roller 87c, the intermediate transfer body 87a and the secondary transfer roller 87c The toner image is secondarily transferred to the paper by the electric field acting on the toner based on the transfer voltage between them, and sent to the fixing device 88. The intermediate transfer cleaning unit 87d has a belt cleaning blade that is slidably contacted with the surface of the intermediate transfer body 87a. The transfer residual toner remaining on the surface of the intermediate transfer body 87a after the secondary transfer is scraped off and removed by the belt cleaning blade.

The fixing device 88 includes a heating roller 88a and a fixing roller 88b as heat sources, a fixing belt 88c and a pressure roller 88d hung on the fixing roller 88b, and the pressure roller 88d is pressed against the fixing roller 88b via the fixing belt 88c. The pressure contact portion constitutes the nip portion. Then, the fixing belt 88c heated by the heating roller 88a and each roller heat and pressurize the paper passing through the nip portion to fix the unfixed toner image formed on the paper.

Then, the paper on which the toner image is fixed by the fixing device 88 is discharged to the paper ejection tray outside the machine by the paper ejection device 73 provided with the paper ejection roller.

Note that FIGS. 3 and 5 are examples of the image forming apparatus 1 of the present invention, and the structure and configuration thereof can be appropriately changed as long as the intermediate transfer body 87a of the present invention can be used.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the following examples, the operation was performed at room temperature (25 ° C.) unless otherwise specified. Unless otherwise specified, "%" and "parts" mean "mass%" and "parts by mass", respectively.

[Manufacturing of intermediate transcript 1]
<Preparation of coating liquid for forming base material layer>
A polyimide precursor coating liquid was synthesized as shown below. Since polyimide 4 is insoluble in a solvent, a polyamic acid coating solution was prepared from a solution of an amide-based solvent of polyamic acid 3.
Specifically, first, using NMP (N-methyl-2-pyrrolidone) is a good solvent for the polyamic acid 3, wherein the polyamic acid 3 dissolved, there CB NMP dispersion of NMP dispersion and BaTiO ₃ of (carbon black) The liquid was mixed. Here, 7% by volume of carbon black and 70% by volume of barium titanate are added to the above polyamic acid 3 and mixed using a mixer to use a coating liquid for forming a base material layer, and the resin phase 1 is used. Was prepared.
Further, the polyacetal resin was dissolved in NMP, and similarly, the NMP dispersion of CB was added so as to have 20% by volume of carbon black to prepare the resin phase 2.
The obtained resin phase 1 and resin phase 2 were mixed and stirred at a mass ratio of 50:50 to prepare a coating liquid.

<Formation of base material layer>
Next, while rotating the stainless steel cylindrical mold around the cylindrical shaft, the dispense nozzle is moved in the axial direction, and the coating liquid for forming the base material layer is discharged from the nozzle to discharge the coating liquid for forming the base material layer from the outer peripheral surface of the mold. It was applied in a spiral shape on top to form a coating film in which they were connected.
Next, most of the solvent was volatilized by heating the cylindrical mold at 100 ° C. for 1 hour while rotating the mold, and then heating at 250 ° C. for 1 hour to form an endless belt-shaped base material layer. .. The thickness of the base material layer formed by the above method was 70 μm.

<Preparation of coating liquid for surface layer formation>
Polyfunctional acrylate "DPCA120" (manufactured by Nippon Kayaku Co., Ltd.) 50 parts by mass Polyfunctional urethane acrylate: "UA-1100H" (manufactured by Shin-Nakamura Chemical Co., Ltd.)
50 parts by mass Polymerization initiator: 1-hydroxy-cyclohexyl-phenyl-ketone: "IRGACURE 184" (manufactured by BASF Japan Ltd.) 5 parts by mass Solvent: propylene glycol so that the solid content concentration of the above material is 10% by mass. It was dissolved and dispersed in monomethyl ether acetate (PMA) to prepare a coating solution for forming a surface layer.

<Formation of surface layer>
By spraying the coating liquid for forming the surface layer on the outer peripheral surface of the base material layer using a spray device manufactured by Wyddy Mechatro Solutions Co., Ltd. so that the dry film thickness is 2 μm under the following coating conditions. A coating film is formed, and the coating film is irradiated with ultraviolet rays as active energy rays under the following irradiation conditions to cure the coating film to form a surface layer having a thickness of 2 μm, thereby forming a surface layer having a thickness of 50 μm. Intermediate transcript 1 was obtained. The irradiation of ultraviolet rays was performed while fixing the light source and rotating the base material on which the coating film was formed on the outer peripheral surface of the elastic layer.
(Spray application conditions)
Nozzle scan speed: 1-10 mm / sec
Nozzle distance: 100-150 mm
Number of nozzles: 1
Coating liquid supply amount: 1 to 5 mL / min
O 2 flow rate: _{2 to 6 L / min}
(Ultraviolet irradiation conditions)
Type of light source: High-pressure mercury lamp "H04-L41" (manufactured by Eye Graphics)
Distance from the irradiation port to the surface of the coating film: 100 mm
Irradiation light intensity: 1 J / cm ²
Irradiation time (time for rotating the base material): 240 seconds

[Manufacturing of intermediate transcripts 2-9]
In the production of the intermediate transfer body 1, the types and contents of the resin and the conductor in the dielectric, the resin phase 1 and the resin phase 2, the presence or absence of the surface layer, and the thickness of the intermediate transfer body are changed as shown in Table I below. Intermediate transcripts 2 to 9 were produced in the same manner except for the above. As the intermediate transfer materials 5 and 9, titanium oxide, which is a normal dielectric material, was used instead of a ferroelectric material.

[Measurement of relative permittivity]
The dielectric constant was measured for the base material layer of each of the manufactured intermediate transfer materials. Specifically, as shown in FIG. 6, a thin film electrode 201 having a resistance of 1 digit Ω is formed on both surfaces of the intermediate transfer body (base material layer) 87a by sputtering or the like, and the measurement sample is cut out with a mold of 10 mmφ. The dielectric constant (F) was produced by the electrode contact method using an impedance analyzer "12608W type" (manufactured by Solartron Analytical Co., Ltd.) under the condition of a frequency of 1 Hz to 1 MHz, a temperature of 23 ° C. and a humidity of 50% RH. / M) was measured and converted into a relative permittivity.

[Method of observing the cross section of the base material layer>
As a method for observing the cross section of the base material layer, platinum-palladium was sputtered on the sample surface of the base material layer as a pretreatment. Specifically, after being inserted into the sputtering apparatus, a vacuum was created and the acceleration voltage was observed at 5 kV. Then, using a transmission electron microscope "2000FX" (manufactured by JEOL Ltd.), the base material layer was observed at a magnification of 100 times, 5000 times, and 10000 times, and the presence or absence of a co-continuous structure was confirmed.

[Evaluation]
<Concave and convex paper transferability>
The superiority and inferiority of the image quality was compared by the transferability evaluation using the uneven paper. Using 203 g of Rezac paper, the transfer state of toner was ranked for the recesses. The evaluation conditions and evaluation machines were as follows, and ○ and ◎ were passed.
Evaluation conditions: Environment 20 ° C 50%
Evaluation machine: bizhub PRESS C1100
(Standard)
⊚: Completely transferred.
◯: Several points are missing in the second layer. There is no problem with the single color part.
Δ: Monochromatic parts are sparsely missing.
X: The monochromatic part is completely missing.

<Durability>
The paper passing durability was 2000000 sheets under the following conditions and the following evaluation machine, and the damage status of the intermediate transfer material was compared between the time of passing 1,000,000 sheets and the time of passing 2000000 sheets. ○ and ◎ were accepted.
Evaluation conditions: Environment 20 ° C 50%
Evaluation machine: bizhub PRESS C1100
(Standard)
⊚: With 2000000 sheets durability, no cracks ○: With 1,000,000 sheets durability, no cracks △: With 1,000,000 sheets durability, damage was confirmed at the end.
×: With a durability of 1,000,000 sheets, damage was confirmed not only at the edges but also at the center.

As shown in the above results, it can be seen that the intermediate transfer material of the present invention is superior to the intermediate transfer material of the comparative example in terms of uneven paper transferability and durability.

R1 resin phase 1
R2 resin phase 2
1a Intermediate transfer body 2a Base material layer 3a Elastic layer 4a Surface layer 1 Image forming apparatus 10 Control unit 11 CPU
12 ROM
13 RAM
20 Storage unit 30 Network I / F unit 40 Display operation unit 50 Image reading unit 60 Image processing unit 70 Transport unit 71 Feeding device 72 Transport mechanism 73 Paper ejection device 80 Image forming unit 81, 81Y, 81M, 81C, 81K Exposure device 82, 82Y, 82M, 82C, 82K Developer 83, 83Y, 83M, 83C, 83K Photoreceptor drum 84, 84Y, 84M, 84C, 84K Charging device 85, 85Y, 85M, 85C, 85K Cleaning device 86, 86Y, 86M , 86C, 86K Primary transfer roller 87 Intermediate transfer unit 87a Intermediate transfer body 87b Support roller 87c Secondary transfer roller 87d Intermediate transfer cleaning unit 88 Fixing device 88a Heating roller 88b Fixing roller 88c Fixing belt 88d Pressurizing roller 201 Thin film electrode

Claims (8)

An intermediate transcript having at least a substrate layer,
The relative permittivity at a frequency of 1 MHz is in the range of 10 to 100.
When the substrate layer is cross-sectionally observed with an electron microscope at a magnification of at least 1000, the resin phase 1 and the resin phase 2 are present in a unit area of ^{100 μm 2, and the resin phase 1 and the resin phase 2 are present.} They form co-continuous structures that exist as continuous phases with each other.
The resin phase 1 contains a ferroelectric substance in the range of 10 to 70% by volume with respect to the entire resin phase 1.
An intermediate transfer material, wherein the resin phase 2 contains a conductor in the range of 1 to 20% by volume with respect to the entire resin phase 2. The intermediate transfer material according to claim 1, wherein the resin phase 1 is continuously present from the front surface to the back surface in the thickness direction of the base material layer. The intermediate transfer member according to claim 1 or 2, wherein the intermediate transfer body has a surface layer on the outermost surface. The intermediate transfer member according to any one of claims 1 to 3, wherein the thickness of the intermediate transfer body is in the range of 50 to 100 μm. The intermediate transfer material according to any one of claims 1 to 4, wherein the ferroelectric substance is either barium titanate or strontium titanate. The intermediate transfer product according to any one of claims 1 to 5, wherein the resin phase 1 and the resin phase 2 contain at least any one of polyimide, polyamide, and polyacetal. The intermediate transfer material according to any one of claims 1 to 6, wherein the conductor is any of carbon black, carbon nanotubes, and graphene. An electrophotographic image forming apparatus comprising the intermediate transfer member according to any one of claims 1 to 7.

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