JP2023066584A - Transfer belt and electrophotographic image forming apparatus - Google Patents

Abstract

To provide a transfer belt that is provided with transferability, cleanability, and durability without impairing a function to hold a toner image and a transfer material, and an electrophotographic image forming apparatus provided with the transfer belt.SOLUTION: A transfer belt of the present invention is a transfer belt having a base material layer, and a surface layer laminated on the base material layer. The dielectric constant of the base material layer is within a range of 20-100. The dielectric constant of an area from a surface on the side of the surface layer to a depth of 15 μm is within a range of 5-10. The Martens hardness of the surface on the side of the surface layer is within a range of 300-700 N/mm2.SELECTED DRAWING: Figure 3A

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer belt and an electrophotographic image forming apparatus, and more particularly, a transfer belt provided with transferability, cleanability, and durability without impairing the function of holding a toner image or a transfer material, and the transfer belt. and an electrophotographic image forming apparatus.

In an electrophotographic image forming apparatus, for example, a latent image formed on an image carrier (photoreceptor) is developed with toner, and the resulting toner image is transferred onto an intermediate transfer belt, which is a belt-shaped transfer member. (primary transfer) and temporarily held. Next, the toner image on the intermediate transfer belt is transferred (secondary transfer) onto a transfer material such as paper. At the time of secondary transfer, the transfer material is placed on a secondary transfer belt (also called a “paper conveying belt” or “transfer conveying belt”), conveyed to the position of the intermediate transfer belt, and transferred from the intermediate transfer belt. The transfer of the toner image to (secondary transfer) is performed on the secondary transfer belt.

Transfer belts such as intermediate transfer belts and secondary transfer belts used in this image forming method have excellent transfer properties from the electrostatic latent image bearing member to the intermediate transfer belt and from the intermediate transfer belt to the transfer material on the secondary transfer belt. There is a demand for good toner transferability and cleanability for cleanly removing residual toner after transfer.

In recent years, electrophotographic image forming apparatuses use a variety of transfer materials, and there is a demand for compatibility with not only plain paper and OA paper, but also cardboard, coated paper, and paper with uneven surfaces. It is In particular, there is a demand for improvements in transfer belts such as intermediate transfer belts and secondary transfer belts.

Here, it is generally known that a transfer belt having a large electrostatic capacity is advantageous in terms of transfer rate, retention of transfer material and toner image, and the like. However, increasing the capacitance causes a problem that foreign matter such as paper dust and residual toner tends to adhere to the transfer belt. In order to address such a problem, for example, Japanese Patent Application Laid-Open No. 2002-200002 describes a technique for reducing the contamination of the transfer belt by reducing the surface energy of the surface of the secondary transfer belt (transfer/conveyor belt). However, the technique described in Japanese Patent Application Laid-Open No. 2002-200010 is insufficient in reducing contamination when charged toner adheres to the surface of the transfer belt, and a means for reducing the electric force is required. become.

Further, in Patent Document 2, based on the technical idea that the lower the relative dielectric constant of the surface layer, the smaller the mirror image force between the toner and the transfer belt, the relative dielectric constant of the entire transfer belt is 15 or more, and the relative dielectric constant of the surface layer is 15 or more. Techniques for intermediate transfer belts with a modulus of 6 or less and a volume resistivity within a specified range are described. However, in the intermediate transfer belt described in Patent Document 2, it is preferable that the hardness of the surface layer is set low from the viewpoint of durability.

Furthermore, Patent Document 3 describes a technique for an intermediate transfer belt having a hard coat layer with high hardness as a surface layer. This configuration reduces the penetration of toner into the intermediate transfer belt and improves the toner releasability. It is said that Here, the ultraviolet curable resin or the like specifically described as the constituent material of the hard coat layer in Patent Document 3 has a lower relative dielectric constant than the commonly used base layer material, and is also said to have the effect of reducing the mirror image force. Conceivable. However, in order to obtain the effect of reducing the image force, a hard coat layer having a dielectric constant as low as the thickness of the toner layer is required. .

On the other hand, it is assumed that increasing the toner releasability of the intermediate transfer belt makes it difficult to retain the toner image. Based on such a technical idea, there is known a technique for increasing the dielectric constant of the surface layer of the transfer belt from the viewpoint of sufficiently holding the toner image and the transfer material (see, for example, Patent Document 4). .

In this way, in transfer belts such as intermediate transfer belts and secondary transfer belts, while having the function of sufficiently holding toner images and transfer materials, the transferability of toner images and the ability to remove paper dust, residual toner, etc. are improved. At present, a transfer belt having sufficient cleaning properties and durability has not been obtained.

JP 2006-53319 A JP 2019-148729 A Japanese Unexamined Patent Application Publication No. 2009-192901 Japanese Patent Application Laid-Open No. 2005-99181

The present invention has been made in view of the above-mentioned problems and circumstances, and the problem to be solved is to provide a transfer toner having transferability, cleanability, and durability without impairing the function of holding a toner image or a transfer material. An object of the present invention is to provide a belt and an electrophotographic image forming apparatus having the transfer belt.

In order to solve the above problems, the present inventors, in the process of studying the causes of the above problems, have found that a transfer belt having a base layer and a surface layer laminated on the base layer has a ratio of the base layer By setting the dielectric constant and the relative dielectric constant in a region from the surface of the surface layer to a depth of 15 μm within specific ranges, respectively, and setting the Martens hardness of the surface on the surface layer side within a specific range, the toner image and the The present inventors have found that it is possible to provide a transfer belt imparted with transferability, cleanability, and durability without impairing the function of holding a transfer material, leading to the present invention. That is, the above problems related to the present invention are solved by the following means.

1. A transfer belt having a base layer and a surface layer laminated on the base layer,
the dielectric constant of the base material layer is in the range of 20 to 100,
The dielectric constant in the region from the surface of the surface layer to a depth of 15 μm is within the range of 5 to 10, and the Martens hardness of the surface of the surface layer is within the range of 300 to 700 N/mm ² . Characterized transfer belt.

2. 2. The transfer belt according to claim 1, wherein the surface layer contains a cured product of a composition containing alkoxysilane.

3. Furthermore, having an intermediate layer between the base layer and the surface layer,
The intermediate layer contains a resin selected from polyimide resin, polyamideimide resin, polyphenylene sulfide resin and polyetheretherketone resin,
Item 1 or 2, wherein the total layer thickness of the intermediate layer and the surface layer is in the range of 10 to 20 μm, and the layer thickness of the base layer is in the range of 40 to 100 μm. The transfer belt according to the item.

4. 4. The transfer belt according to any one of items 1 to 3, wherein the Martens hardness of the outer surface is in the range of 500 to 600 N/mm ² .

5. 5. The transfer belt according to any one of items 1 to 4, wherein the dielectric constant of the base material layer is in the range of 40 to 100.

6. 4. The transfer belt according to item 3, wherein the dielectric constant of the intermediate layer is in the range of 5-10.

7. 7. The transfer belt according to any one of items 1 to 6, wherein the dielectric constant of the surface layer is in the range of 2-5.

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

Provided are a transfer belt imparted with transferability, cleanability, and durability without impairing the function of holding a toner image or a transfer material, and an electrophotographic image forming apparatus equipped with the transfer belt. It is to be.

Although the expression mechanism or action mechanism of the effects of the present invention has not been clarified, it is speculated as follows.

The transfer belt of the present invention has a base layer having a dielectric constant of 20 to 100 and a surface layer laminated on the base layer, and the dielectric constant in a region from the surface of the surface layer to a depth of 15 μm The ratio is in the range of 5-10. That the region has a dielectric constant within the range of 5 to 10 means that it has a layered region with a sufficiently low dielectric constant and a sufficient thickness. In addition, in the transfer belt of the present invention, the layered region may be composed of only the surface layer, or may be composed of the surface layer and the intermediate layer. Furthermore, the surface on the surface layer side has a sufficiently high Martens hardness within the range of 300 to 700 N/mm ² .

When the transfer belt of the present invention is used as an intermediate transfer belt, a layered region having a low relative permittivity and a thickness corresponding to the thickness of the toner layer is formed on the surface side where primary transfer and secondary transfer of the toner image are performed. and the surface has a sufficiently high hardness, the releasability of the toner image in the secondary transfer can be improved. In addition, the same action mechanism also improves the ability to clean residual toner after secondary transfer. Furthermore, even though the surface on the surface layer side has a high hardness, even if the high-hardness surface layer is not thickened, a region with a low relative dielectric constant exists from the surface on the surface layer side to a thickness of 15 μm, so that the transfer belt can be durable. Excellent in sex.

Further, the transfer belt of the present invention is provided with a base layer having a sufficiently high relative dielectric constant of 20 to 100 inside the layered region having a low relative dielectric constant, so that when used as an intermediate transfer belt, The electric field acting on the toner can be strengthened, and good primary transfer can be performed even if the toner attracting force is weakened due to the presence of the layered region having a low dielectric constant. Further, the substrate layer having a high dielectric constant has polarization charges, and the transfer belt of the present invention has the ability to sufficiently retain the toner image from the primary transfer to the secondary transfer. In addition, since a reverse bias is applied at the time of secondary transfer, the above-mentioned polarized charge quickly disappears and is polarized to the opposite polarity, so secondary transfer from the intermediate transfer belt to the transfer material can be performed smoothly.

When the transfer belt of the present invention is used as a secondary transfer belt, it is provided with a base layer having a sufficiently high relative dielectric constant of 20 to 100 inside a layered region having a low relative dielectric constant. Secondary transfer can be performed, and the transfer belt can be charged by the secondary transfer bias to sufficiently attract and hold the transfer material. Further, the secondary transfer belt is also excellent in cleaning performance against paper dust and residual toner and in durability, as in the case of the intermediate transfer belt.

1 is a plan view of an example of a transfer belt of the present invention; FIG. II-II line sectional view of the transfer belt shown in FIG. FIG. 2 is an enlarged cross-sectional schematic diagram of the X portion of the transfer belt shown in FIG. FIG. 4 is an enlarged schematic cross-sectional view of another example of the transfer belt of the present invention; One embodiment of an apparatus for making a transfer belt of the present invention FIG. 1 is a sectional view showing an example of an electrophotographic image forming apparatus having the transfer belt of the present invention as an intermediate transfer belt;

The transfer belt of the present invention is a transfer belt having a base layer and a surface layer laminated on the base layer, wherein the base layer has a dielectric constant in the range of 20 to 100, and the surface layer The dielectric constant in the region from the surface of the side to a depth of 15 μm is within the range of 5 to 10, and the Martens hardness of the surface of the surface layer is within the range of 300 to 700 N/mm ² do. This feature is a technical feature common to or corresponding to each of the following embodiments (forms).

As an embodiment of the present invention, from the viewpoint of exhibiting the effects of the present invention, particularly from the viewpoint of sufficiently high Martens hardness of the surface on the surface layer side, the surface layer is a cured product of a composition containing an alkoxysilane. preferably included. More preferably, the surface layer typically comprises a cured composition containing an alkoxysilane.

As an embodiment of the present invention, from the viewpoint of manifesting the effects of the present invention, an intermediate layer is further provided between the base material layer and the surface layer, and the intermediate layer is a polyimide resin, a polyamideimide resin, or a polyphenylene sulfide resin. and a polyether ether ketone resin, the total layer thickness of the intermediate layer and the surface layer is in the range of 10 to 20 μm, and the layer thickness of the base layer is in the range of 40 to 100 μm. preferably within.

As an embodiment of the present invention, from the viewpoint of exhibiting the effects of the present invention, it is preferable that the Martens hardness of the surface on the surface layer side is in the range of 500 to 600 N/mm ² . Further, the dielectric constant of the base material layer is preferably in the range of 40-100. The dielectric constant of the intermediate layer is preferably in the range of 5-10. It is preferable that at least one of the dielectric constant of the surface layer is within the range of 2-5.

The transfer belt of the present invention can be suitably equipped in an electrophotographic image forming apparatus.

DETAILED DESCRIPTION OF THE INVENTION The present invention, its constituent elements, and embodiments and modes for carrying out the present invention will be described in detail below. In the present application, "-" is used to mean that the numerical values before and after it are included as the lower limit and the upper limit.

[Transfer belt]
A transfer belt of the present invention is a transfer belt having a substrate layer and a surface layer laminated on the substrate layer, and is characterized by satisfying the following requirements (1) to (3). do.
(1) The dielectric constant of the substrate layer is in the range of 20-100.
(2) The relative permittivity is within the range of 5 to 10 in a region from the surface on the surface side to a depth of 15 μm.
(3) The Martens hardness of the surface on the surface layer side is in the range of 300 to 700 N/mm ² .

The transfer belt of the present invention has a base layer and a surface layer laminated on the base layer. The transfer belt of the present invention may optionally have layers other than the base layer and the surface layer as long as the above requirements (1) to (3) are satisfied. Other layers include an intermediate layer arranged between the substrate layer and the surface layer. When the transfer belt of the present invention is used, for example, in the case of an intermediate transfer belt, a toner image is transferred to the outer surface of the transfer belt. Also, in the case of the secondary transfer belt, the transfer material is placed on the surface of the outer layer during use.

Since the shape of the transfer belt of the present invention is an endless structure, there is no change in thickness due to overlapping, and any portion can be used as the rotation start position of the transfer belt, and a control mechanism for the rotation start position can be omitted. It is preferable because of its advantages.

Hereinafter, an embodiment of the transfer belt of the present invention will be described with reference to the drawings, taking a transfer belt having an endless structure as an example. However, the scope of the present invention is not limited to the illustrated examples. 1 and 2 are a plan view and a cross-sectional view taken along line II-II of an example of the transfer belt of the present invention (endless structure transfer belt) in a state in which it is stretched between two transport rollers. 3A is an enlarged schematic cross-sectional view of the X portion of the transfer belt shown in FIG. 2. FIG. FIG. 3B is an enlarged schematic cross-sectional view of another example of the transfer belt of the present invention.

1 and 2, the transfer belt 1A of the present invention is stretched by two transport rollers R1 and R2 so as to be transportable in the D direction. The transfer belt 1A is composed of a base layer 2 and a surface layer 3 laminated on the base layer 2 . In the transfer belt 1A, the inner peripheral surface in contact with the transport rollers R1 and R2 is the surface S2 on the base layer 2 side, and the outer peripheral surface exposed to the outside is the surface S1 on the surface layer 3 side.

FIG. 3B shows an enlarged schematic sectional view of a transfer belt 1B having an intermediate layer 4 on a base layer 2 and a surface layer 3 on the intermediate layer 4. FIG. The transfer belt 1B is a transfer belt having an endless structure similar to the transfer belt 1A except that the layer structure is a three-layer structure. 1 and 2 instead of the transfer belt 1A, the inner peripheral surface in contact with the transport rollers R1 and R2 is the surface S2 on the base layer 2 side, and the outer peripheral surface exposed to the outside. is the surface S1 on the surface layer 3 side.

Requirements (1) to (3) of the transfer belt of the present invention will be described with reference to FIGS. 3A and 3B. In FIG. 3A, the thickness of the transfer belt 1A, the layer thickness of the base layer 2 and the layer thickness of the surface layer 3 are indicated by "Tt", "Tb" and "Ts", respectively. In FIG. 3B, the thickness of the transfer belt 1B, the layer thickness of the base layer 2, the layer thickness of the intermediate layer 4 and the layer thickness of the surface layer 3 are represented by "Tt", "Tb", "Tm" and "Ts", respectively. show.

In the transfer belts 1A and 1B, the dielectric constant of the base material layer 2 is in the range of 20-100 according to the requirement (1). When the dielectric constant of the base material layer 2 is within the above range, the transfer belts 1A and 1B are excellent in retaining the toner image and the transfer material, and the effects of the transferability and the cleaning property are not deteriorated. The dielectric constant of the substrate layer 2 is preferably in the range of 40-100, more preferably in the range of 60-80. Constituent materials for setting the dielectric constant of the base material layer 2 to the above range will be described later.

Further, the layer thickness Tb of the substrate layer 2 is preferably in the range of 20-300 μm, more preferably in the range of 30-200 μm, and even more preferably in the range of 40-100 μm. When the layer thickness Tb of the base material layer 2 is within the above range, the transfer belts 1A and 1B can easily enjoy the advantage of the base material layer 2 having a high dielectric constant, and the toner image and the transfer material can be easily retained. , transferability and cleanability are easily achieved.

In the transfer belts 1A and 1B, according to the requirement (2), the dielectric constant in the region from the surface S1 on the surface layer 3 side to a depth of 15 μm (hereinafter also referred to as “region L”) is within the range of 5 to 10. be. The transfer belts 1A and 1B are excellent in transferability and cleaning property because the relative permittivity in the region L is within the above range. The dielectric constant in region L is preferably in the range of 5-8, more preferably in the range of 5-6.

Here, the transfer belt 1A is an example in which the layer thickness Ts of the surface layer 3 is 15 μm or more, that is, the entire area L is composed of the surface layer 3 in the embodiment of the two-layer structure in which the transfer belt is composed of a base layer and a surface layer. When the transfer belt of the present invention has a two-layer structure consisting of a base layer and a surface layer, the ratio of the thickness of the surface layer 3 to the thickness of the base layer 2 in the region L is not particularly limited as long as the requirement (2) is satisfied. However, for example, a range of 15:0 to 10:5 can be applied. When the layer thickness Ts of the surface layer 3 is 15 μm or more, the thickness of the base layer 2 in the region L is 0 μm, and the ratio is 15:0. When the layer thickness Ts of the surface layer 3 is 10 μm, the thickness of the base layer 2 in the region L is 5 μm, and the ratio is 10:5.

In addition, if all the requirements (1) to (3) are satisfied, the entire base layer 2 is present in the region L, that is, the total thickness of the surface layer 3 and the base layer 2 is 15 μm. Included in the present invention. However, considering the thickness Tt of the transfer belt 1A and the layer thickness Tb of the base material layer 2, the base material layer 2 exists beyond the area L while forming a part of the area L, or is outside the area L. An embodiment in which the base material layer 2 exists in is preferable.

In the transfer belt 1</b>A, when the layer thickness Ts of the surface layer 3 is 15 μm or more, the dielectric constant in the region L is the same as that of the surface layer 3 . When the layer thickness Ts of the surface layer 3 is less than 15 μm, the region L consists of the surface layer 3 and part of the base material layer 2 . In this case, the relative dielectric constant in the region L corresponds to the relative dielectric constant of the mixed material composed of the constituent material of the surface layer 3 and part of the constituent material of the base layer 2 measured by the following method.

In order to satisfy the requirement (2) above, when the transfer belt has a two-layer structure of a base layer and a surface layer like the transfer belt 1A, the relative permittivity of the surface layer 3 is 10 or less, and 2 to 2. A range of 10 is preferred, and 2 to 5 is more preferred. Also, the layer thickness Ts of the surface layer 3 is preferably 5 μm or more, more preferably in the range of 5 to 20 μm, even more preferably in the range of 10 to 20 μm. When the dielectric constant and layer thickness of the surface layer 3 are within the above ranges, the surface layer has a low dielectric constant and a layer thickness corresponding to the thickness of the toner layer, thereby further improving toner releasability. Constituent materials for setting the dielectric constant of the surface layer 3 to the above range will be described later.

In addition, in the embodiment of the transfer belt 1B having a three-layer structure including a base layer, an intermediate layer, and a surface layer, the transfer belt 1B has a total layer thickness of 15 μm, which is the layer thickness Ts of the surface layer 3 and the layer thickness Tm of the intermediate layer 4. For example. When the transfer belt has a two-layer structure consisting of a base layer and a surface layer, the base layer has a high relative dielectric constant of 20 to 100 according to the requirement (1), and the surface layer has a relative dielectric constant of 10 or less according to the requirement (2). It has a low relationship with When the transfer belt has a three-layer structure consisting of a base layer, an intermediate layer, and a surface layer, the requirement that the base layer has a dielectric constant as high as 20 to 100 does not change according to the requirement (1). Therefore, it is preferable that the layer has the same function as the surface layer in the case of the two-layer structure.

In the transfer belt 1B, the layer structure in the area L is not particularly limited as long as the requirement (2) is satisfied. For example, the region L may consist of only the surface layer 3 , may consist of the surface layer 3 and the intermediate layer 4 , or may consist of the surface layer 3 , the intermediate layer 4 and the base layer 2 . The region L is preferably composed of the surface layer 3 and the intermediate layer 4, or preferably composed of the surface layer 3, the intermediate layer 4 and the substrate layer 2, and more preferably composed of the surface layer 3 and the intermediate layer 4.

Also in the transfer belt 1B, if all the requirements (1) to (3) are satisfied, the entire base layer 2 exists within the region L, that is, the surface layer 3, the intermediate layer 4, and the base layer 2 An aspect in which the total layer thickness is 15 μm is also included in the present invention. However, considering the thickness Tt of the transfer belt 1B and the layer thickness Tb of the base material layer 2, the base material layer 2 exists beyond the area L while constituting a part of the area L, or is outside the area L. An embodiment in which the base material layer 2 exists in is preferable.

Taking these into account, in the transfer belt 1B, the total layer thickness of the layer thickness Ts of the surface layer 3 and the layer thickness Tm of the intermediate layer 4 is preferably in the range of 10 to 20 μm, more preferably in the range of 15 to 20 μm. preferable. When the transfer belt has a three-layer structure of a substrate layer, an intermediate layer, and a surface layer like the transfer belt 1B, the relative permittivity and layer It is preferable that the thickness be a combination of the following.

The dielectric constant of the surface layer 3 is preferably in the range of 2-10, more preferably 2-5. The dielectric constant of the intermediate layer 4 is preferably in the range of 5-20, more preferably 5-10. Also, the layer thickness Ts of the surface layer 3 is preferably in the range of 1 to 15 μm, more preferably in the range of 1 to 10 μm. The layer thickness Tm of the intermediate layer 4 is preferably within the range of 5 to 15 μm, more preferably within the range of 10 to 15 μm. Since the total layer thickness, each dielectric constant, and each layer thickness of the surface layer 3 and the intermediate layer 4 are within the above ranges, the surface layer 3 and the intermediate layer 4 have a low dielectric constant and a layer thickness corresponding to the thickness of the toner layer. As a result, the toner releasability is further improved. Constituent materials for setting the dielectric constants of the surface layer 3 and the intermediate layer 4 to the above range will be described later.

Further, in the transfer belts 1A and 1B, the Martens hardness of the surface S1 on the surface layer 3 side is within the range of 300 to 700 N/mm ² according to the requirement (3). Since the Martens hardness of the surface S1 on the surface layer 3 side is within the above range, the transfer belts 1A and 1B are excellent in transferability, cleanability and durability. The Martens hardness of the surface S1 on the surface layer 3 side is preferably in the range of 500 to 600 N/mm ² .

In order to set the Martens hardness of the surface S1 on the surface layer 3 side within the above range, the constituent material of the surface layer 3 is appropriately selected. As will be described later, the constituent material of the surface layer 3 has a dielectric constant that satisfies the requirement (2) and also satisfies the requirement (3).

Considering the requirement (2) above, the thickness Tt of the transfer belts 1A and 1B is 15 μm or more, and can be appropriately determined according to the purpose of use. From the viewpoint of satisfying the requirement (2) above and generally from the viewpoint of satisfying mechanical properties such as strength and flexibility, the thickness is preferably 40 to 400 μm, more preferably 65 to 300 μm. In addition, in the transfer belt of the present invention, the dielectric constant of the transfer belt itself is not particularly limited as long as the above (1) to (3) are satisfied. is more preferred.

The relative permittivity of each constituent layer in the transfer belt, the region L, and the transfer belt itself is a relative permittivity measured by the following method. A method for measuring the Martens hardness of the surface S1 on the surface layer 3 side is also shown below.

<Dielectric constant>
In the present invention, the relative permittivity of each object to be measured refers to the relative permittivity at a frequency of 1 MHz measured under an environment of temperature 23° C. and humidity 50% RH. A dielectric constant can be calculated, for example, by the following method.

In order to obtain the relative dielectric constant of the transfer belt, first, the transfer belt is subjected to dielectric constant measurement. Specifically, a thin film electrode having a resistance of one digit Ω is formed on both sides of the transfer belt by sputtering or the like, cut out with a mold of 10 mmφ to prepare a measurement sample, and an impedance analyzer "12608W type" (manufactured by Solartron Analytical) is used. Using this, the dielectric constant (F/m) is measured by the electrode contact method under the conditions of a frequency of 1 MHz, a temperature of 23° C. and a humidity of 50% RH, and converted to a relative dielectric constant.

For example, the dielectric constants of the base layer 2 and the surface layer 3 of the transfer belt 1A shown in FIG. is measured in the same manner as above, and the dielectric constant of the surface layer 3 is calculated from the difference. The obtained permittivity is converted into a relative permittivity.

Further, for example, the transfer belt 1B shown in FIG. 3B has a structure having an intermediate layer 4 between the base layer 2 and the surface layer 3. In this case, the dielectric constant of each layer is the dielectric constant of the transfer belt 1B, the dielectric constant of the laminate of the intermediate layer 4 and the base layer 2 remaining after scraping off the surface layer 3 from the transfer belt 1A, and the intermediate layer from the laminate. The dielectric constant of the substrate layer 2 left after the layer 4 is scraped off is measured in the same manner as described above, and the dielectric constants of the substrate layer 3 and the intermediate layer 4 are calculated. The obtained permittivity is converted into a relative permittivity.

In the case of a two-layer structure of a substrate layer and a surface layer, the relationship between the dielectric constant and thickness of the transfer belt and each layer and the layer thickness can be expressed by the following formula (I). In the case of the three-layer structure of the surface layer and the surface layer, it can be represented by the following formula (II).

The meaning of each symbol in Formula (I) and Formula (II) is as follows.
ε: permittivity of transfer belt d: thickness of transfer belt (“Tt” in FIGS. 3A and 3B)
ε ₁ : dielectric constant of the surface layer ε ₂ : dielectric constant of the base layer ε ₃ : dielectric constant of the intermediate layer d ₁ : layer thickness of the surface layer (“Ts” in FIGS. 3A and 3B)
d ₂ : layer thickness of base material layer (“Tb” in FIGS. 3A and 3B)
d ₃ : Layer thickness of intermediate layer (“Tm” in FIG. 3B)

Further, the dielectric constant of the region (region L) from the surface S1 on the side of the surface layer 3 to a depth of 15 μm in the above requirement (2) is equivalent to the dielectric constant of the transfer belt 1A when explained using the transfer belt 1A shown in FIG. , the dielectric constant of the remaining area (region L) of the transfer belt 1A from the surface S1 on the surface layer 3 side to a depth of 15 μm is removed in the same manner as described above, and the dielectric constant of the region L is calculated from the difference. The obtained permittivity is converted into a relative permittivity.

<Martens hardness>
In the present invention, the Martens hardness (unit: N/mm ² ) is determined by the following formula (III) by pressing an indenter into the object to be measured while applying a load.
Formula (III) Martens hardness = (test load [N]) / (contact surface area of indenter with measurement object under test load [mm ² ])

The Martens hardness can be measured using a commercially available hardness measuring device, for example, an ultra-micro hardness tester "H-100V" (manufactured by Fisher Instruments). In this measuring device, a quadrangular pyramid-shaped indenter is pushed into the object to be measured while applying a test load, and when the desired depth is reached, the surface area of the indenter in contact with the object to be measured is calculated from the depth of indentation. Martens hardness [N/mm ² ] is calculated from the above formula (III).

(Measurement condition)
Measuring machine: Hardness meter indentation tester "H-100V" (manufactured by Fisher Instruments)
Measurement indenter: Vickers indenter Measurement environment: temperature 23°C, humidity 50% RH
Measurement sample: Cut the transfer belt into a size of 5 cm x 5 cm to prepare a measurement sample Maximum test load: 1 mN
Load Condition: Apply load proportionally with time at a rate that reaches the maximum test load in 10 sec.
Load creep time: 5 seconds Note that measurements are taken at 10 random points for each sample, and the average value is taken as the Martens hardness [N/mm ² ].

Next, constituent materials of each layer of the transfer belt of the present invention for satisfying the requirements (1) to (3) of the transfer belt of the present invention will be described.

(Base material layer)
The base material layer 2 satisfies the requirement (1), that is, has a dielectric constant within the range of 20-100. The constituent material of the base material layer 2 is not particularly limited as long as it satisfies the requirements of (1).

In the transfer belts 1A and 1B, the base layer 2 typically has conductivity. The constituent material of the base material layer 2 contains, for example, a matrix resin for molding into a belt shape, particularly an endless belt, and a conductive agent for imparting conductivity. In addition, in the constituent material, when the conductive agent has a higher relative dielectric constant than the resin, the conductive agent has a function of adjusting the conductivity of the base material layer 2 and a function of adjusting the relative dielectric constant. In the case where a conductive agent is used to impart conductivity to the base material layer 2, the volume resistivity of the transfer belts 1A and 1B at an applied voltage of 100 V is 1.0×10 ⁵ to 9.0×10 ⁹ Ω·cm. It is preferable to adjust the conductivity of the base material layer 2 so as to fall within the range of .

In the above, the base material layer 2 may consist only of a resin and a conductive agent, as long as it satisfies the requirements of the required conductivity and the dielectric constant of (1). However, in order to give the substrate layer 2 a high relative dielectric constant as in (1), the substrate layer 2, in addition to the resin and the conductive agent, has a relative dielectric constant of 100 or more, preferably 500 or more. It preferably contains a body. Note that ferroelectrics generally do not have electrical conductivity. In the present specification, the dielectric constant refers to the dielectric constant at a frequency of 1 MHz under an environment of temperature 23° C. and humidity 50% RH.

The base material layer 2 may contain components other than the resin, the conductive agent and the ferroelectric as long as the requirements of (1) are satisfied. Other components include inorganic fillers other than conductive agents and ferroelectrics, leveling agents such as silicone oil, and the like.

<Resin>
Examples of resins used for the base layer 2 include polyimide resins, polyamide resins, polyamideimide resins, polymethyl methacrylate resins, polycarbonate resins, polystyrene resins, acrylonitrile-styrene copolymer resins, polyvinyl chloride resins, acetate resins, and ABS resins. , polyester resins, polyamide resins, polyphenylene sulfide resins, polyether ether ketone resins, and the like. These resins may be used individually by 1 type, and may be used in combination of 2 or more type.

Among these, super engineering plastics having strength and durability such as polyimide resins, polyamideimide resins, polyphenylene sulfide resins and polyetheretherketone resins are preferred, and polyimide resins and polyamideimide resins are more preferred. Among them, polyimide resin is more preferable because of its excellent properties such as heat resistance, bending resistance, flexibility, and dimensional stability. Polyimide resin (hereinafter also simply referred to as "polyimide".) Is obtained by, for example, synthesizing a polyamic acid (polyimide precursor) from an acid anhydride and a diamine compound, and imidizing the polyamic acid with heat or a catalyst. .

The acid anhydride used for polyimide synthesis is not particularly limited, but examples include biphenyltetracarboxylic dianhydride, terphenyltetracarboxylic dianhydride, benzophenonetetracarboxylic dianhydride, pyromellitic anhydride, Aromatic tetracarboxylic dianhydrides such as oxydiphthalic dianhydride, diphenylsulfonetetracarboxylic dianhydride, hexafluoroisopropylidene diphthalic dianhydride, and cyclobutanetetracarboxylic dianhydride are included.

The diamine compound used for polyimide synthesis is not particularly limited, but examples include 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 aromatic diamines such as (4-aminophenoxy)benzene;

When producing a base material layer containing polyimide, for example, a polyimide varnish or the like containing polyamic acid, which is a polyimide precursor, as a main component can be used. Examples of commercially available polyimide varnishes include Iupia (registered trademark)-AT (U-varnish-A) and Iupia (registered trademark)-ST (U-varnish-S) both manufactured by Ube Industries.

Polyamideimide resin (hereinafter also simply referred to as "polyamideimide".) Is a resin having a rigid imide group in the molecular skeleton and an amide group that imparts flexibility, and the polyamideimide used in the present invention is generally can be used.

In general, a method for synthesizing a polyamideimide resin includes an acid chloride method (a): a trivalent carboxylic acid derivative halide having an acid anhydride group, most typically a chloride compound of the derivative and a diamine as a solvent. There is known a known method (see, for example, Japanese Examined Patent Publication No. 42-15637) in which the compound is produced by reacting it in the medium. Alternatively, isocyanate method (b): a known method for producing by reacting a trivalent derivative containing an acid anhydride group and a carboxylic acid with an aromatic isocyanate in a solvent (for example, JP-B-44-19274 Publication No. 2003-120002) and the like are known, and any of them can be used.

For example, it is produced by polycondensation of trimellitic acid and an aromatic diamine or diisocyanate by a known method. In this case, the same aromatic diamine as the raw material for the polyimide can be used. Examples of diisocyanate include compounds in which the amino group in the diamine component described above is substituted with an isocyanate group.

When producing a base material layer containing polyamideimide, for example, a polyimide varnish or the like containing a polyamideimide precursor as a main component can be used. As a commercially available polyamideimide varnish, for example, HR-16NN (manufactured by Toyobo Co., Ltd.) can be used.

The resin according to the present invention is preferably contained within a range of 50 to 95% by volume with respect to the entire substrate layer 2 . It can have required mechanical strength as it is 50 volume% or more. When it is 95% by volume or less, a space containing a ferroelectric substance and a conductive agent can be secured.

<Conductive agent>
The conductive agent used for the base material layer 2 is not particularly limited as long as it is a substance having conductivity. Specifically, known electronically conductive substances and ionically conductive substances can be used, preferably carbon black, carbon nanotubes, graphite or graphene, and carbon black or carbon nanotubes can be used in the substrate layer. It is more preferable in that it can have conductivity and that it is easy to handle.

The amount of the conductive agent used in the present invention to be added is preferably within the range of 0.1 to 20% by volume with respect to the entire substrate layer 2 . When it is 0.1% by volume or more, it is easy to suppress the occurrence of toner contamination on the surfaces S1 on the surface layer 3 side of the transfer belts 1A and 1B. A decrease in the amount is difficult to recognize. The amount of the conductive agent added is more preferably in the range of 0.5 to 15% by volume, more preferably in the range of 1 to 10% by volume.

Among conductive agents, carbon black includes, for example, gas black, acetylene black, oil furnace black, thermal black, channel black, and ketjen black. Those effective in obtaining the desired electrical conductivity with smaller amounts of mixing include ketjen black, acetylene black and oil furnace black. In addition, Ketjen black is contactive furnace type carbon black.

The average primary particle size of carbon black is preferably in the range of 10-50 nm. The average primary particle size can be measured by a method of FPAR-1000 (manufactured by Otsuka Electronics Co., Ltd.) using a photon counting method.

A commercial item can be used as carbon black. Commercially available products include carbon black “MA8” and “MA11” (both manufactured by Mitsubishi Chemical Corporation).

A carbon nanotube (hereinafter abbreviated as CNT) is a defect-free single layer having a structure in which graphite hexagonal mesh planes are rolled into a cylindrical shape, or a multi-layer tubular substance in which they are laminated in a nested manner. . The average tube diameter of CNTs is preferably in the range of 10-150 nm, and the length of CNTs is preferably in the range of 5-12 μm. Appropriate electrical conductivity can be imparted to the substrate layer by setting the diameter and length of the CNTs within the above ranges.

The CNT may optionally have covalently attached functional groups. For example, by treating CNT with a strong acid, oxidized CNT with a carboxylic acid introduced to the surface is generated, and after reacting the oxidized CNT with thionyl chloride, it is reacted with an alkyl alcohol or the like, resulting in a chemical decoration that dissolves in an organic solvent. CNTs can be produced. By using such chemically decorated CNTs, the CNTs can be uniformly dispersed in the resin. In addition, by applying an electric field from the outside while the CNTs are dispersed in the resin, the CNTs can be oriented in a desired direction, and the dielectric constant of the substrate layer 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 transfer belt, and can be adjusted by cutting (pulverizing) CNTs or mixing two or more types of CNTs. is possible.

<Ferroelectric>
The ferroelectric used for the substrate layer 2 has a dielectric constant of 20 or higher, preferably 100 or higher, more preferably 500 or higher, and even more preferably 1000 or higher. This makes it easier to give the substrate layer 2 a high dielectric constant (20 to 100) that satisfies the requirement (1).

The amount of the ferroelectric used in the present invention is an amount that allows the dielectric constant of the base layer 2 to satisfy the requirement (1). 2, it is preferably contained in the range of 5 to 40% by volume, more preferably in the range of 10 to 30% by volume, and still more preferably in the range of 10 to 20% by volume. .

As ferroelectrics, ferroelectric ceramics are preferable, and barium titanate (relative permittivity; 1200), calcium titanate (relative permittivity; 140), strontium titanate (relative permittivity;; 200), and magnesium titanate. (relative permittivity: 20) and the like.

Of these, the ferroelectric according to the present invention preferably contains at least one compound selected from barium titanate, calcium titanate, and strontium titanate from the viewpoint of permittivity control and durability. .

Preferably, the form of the ferroelectric is particles. The ferroelectric particles according to the present invention preferably have an average primary particle size of 300 nm or less in terms of dispersibility. The lower limit of the average primary particle size is 30 nm, preferably 50 nm, and the optimum range is 90 to 110 nm.

The average primary particle size of ferroelectric particles can be measured, for example, by analyzing an image obtained by a transmission electron microscope (TEM) (manufactured by Hitachi High-Tech). For example, 200 or more particles may be randomly selected from among the particles present in the image, the particle diameters may be measured, and the average value may be obtained. In addition, 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.

A commercially available product can be used as the ferroelectric particles. Commercially available products include barium titanate particles "BT05" (manufactured by Sakai Chemical Industry Co., Ltd.).

The physical properties of the base material layer 2, such as relative permittivity and layer thickness, are as described above.

(surface)
In order for the transfer belts 1A and 1B to satisfy the requirement (2), the surface layer 3 preferably has the layer thickness and dielectric constant as explained above. Further, the surface layer 3 is configured so that the transfer belts 1A and 1B satisfy the requirement (3), that is, the requirement that the surface S1 on the surface layer 3 side has a Martens hardness within the range of 300 to 700 N/mm ² . be. Here, the surface S1 of the transfer belts 1A and 1B on the surface layer 3 side indicates the main surface of the surface layer 3 opposite to the base layer 2 . Hereinafter, the surface S1 on the surface layer 3 side is also referred to as "surface S1 of the surface layer 3".

The constituent material of the surface layer 3 contains, for example, a film-forming component for maintaining the shape of the layer as an essential component, and optionally contains a dielectric constant adjuster. As the film forming component, a material is appropriately selected such that the surface S1 of the surface layer 3 has the Martens hardness within the above range. As the film formation component, for example, a material having a surface Martens hardness close to the range of 300 to 700 N/mm ² when formed into a film by itself is preferable. Typically, such a film forming component is the main component of the constituent material of the surface layer 3 . In the surface layer 3, in order to obtain a dielectric constant that allows the transfer belts 1A and 1B to satisfy the requirement (2), a dielectric constant adjuster having a dielectric constant different from that of the film forming component is added in the constituent material. may contain.

In order for the transfer belts 1A and 1B to satisfy the requirements of (2), if the relative permittivity set for the surface layer 3 is smaller than the relative permittivity of the film-forming component, the film is formed as a relative permittivity adjuster. A material is selected that has a relative dielectric constant less than that of the component. Similarly, if the dielectric constant set for the surface layer 3 is greater than the dielectric constant of the film-forming component, a material having a dielectric constant greater than that of the film-forming component is selected as the dielectric constant adjuster. be done. If the relative permittivity set for the surface layer 3 is the same as the relative permittivity of the film-forming component, it is not necessary to use the relative permittivity adjuster.

Examples of film-forming components for the surface layer 3 include organic materials, inorganic materials, and organic-inorganic composite materials whose surface Martens hardness is close to the above range. Organic materials are typically resins, and inorganic materials and organic-inorganic composite materials include cured products obtained by curing sol-gel materials.

Examples of the above resins include acrylic resins, polyimide resins, polyamideimide resins, polyphenylene sulfide resins, polyetheretherketone resins, and the like. Super engineering plastics with good properties are preferred. Among these, polyimide resins and polyamideimide resins are more preferable. Among them, polyimide resin is more preferable because of its excellent properties such as heat resistance, bending resistance, flexibility, and dimensional stability. As the polyimide resin, the same polyimide resin as described for the base material layer 2 can be used.

Examples of sol-gel materials used as raw materials for inorganic materials and organic-inorganic composite materials include metal salts, metal alkoxides, and the like. In the present invention, alkoxysilanes are preferred for improving transferability.

The alkoxysilane preferably contains a tetrafunctional alkoxysilane (also referred to as "tetraalkoxysilane") or a trifunctional alkoxysilane (also referred to as "trialkoxysilane") from the viewpoint of obtaining higher Martens hardness. In addition, alkoxysilane makes it difficult for shrinkage to occur during curing, and from the viewpoint of reducing the occurrence of warping at the end of the transfer belt, furthermore, bifunctional alkoxysilane (also referred to as “dialkoxysilane”) or monofunctional alkoxysilane is used. It is also called alkoxysilane (“monoalkoxysilane”). ) may contain.

When the alkoxysilane contains tetraalkoxysilane or trialkoxysilane and dialkoxysilane or monoalkoxysilane, the tetraalkoxysilane or trialkoxysilane is contained in the range of 80 to 90% by mass based on the total alkoxysilane. It is preferable to contain monoalkoxysilane or dialkoxysilane in the range of 10 to 20% by mass.

Alkoxy groups in alkoxysilanes include alkoxy groups derived from aliphatic alcohols such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, and tert-butoxy groups, An alkoxy group derived from an aromatic alcohol such as a phenoxy group can be mentioned.

Examples of monovalent organic groups other than silicon-bonded alkoxy groups possessed by monofunctional alkoxysilanes, bifunctional alkoxysilanes, and trifunctional alkoxysilanes include aliphatic hydrocarbon groups having 1 to 18 carbon atoms.

Examples of alkoxysilanes include monofunctional alkoxysilanes such as trimethylmethoxysilane, triethylmethoxysilane, trimethylethoxysilane and triethylethoxysilane.

Bifunctional alkoxysilanes include dimethyldimethoxysilane, diethyldimethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, dimethyldiethoxysilane and diethyldiethoxysilane.

Trifunctional alkoxysilanes include methyltrimethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, isopropyltrimethoxysilane, n-butyltrimethoxysilane, isobutyltrimethoxysilane, n-hexyltrimethoxysilane, n- Octyltrimethoxysilane, n-decyltrimethoxysilane, n-dodecyltrimethoxysilane, n-tetradecyltrimethoxysilane, n-hexadecyltrimethoxysilane, n-octadecyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane Silane, n-propyltriethoxysilane, isopropyltriethoxysilane, n-butyltriethoxysilane, isobutyltriethoxysilane, n-hexyltriethoxysilane, n-octyltriethoxysilane, n-decyltriethoxysilane, n-dodecyl triethoxysilane, n-tetradecyltriethoxysilane, n-hexadecyltriethoxysilane, n-octadecyltriethoxysilane and the like.

Examples of tetrafunctional alkoxysilanes include tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetra-isopropoxysilane and tetraphenoxysilane.

The relative permittivity of the film-forming components exemplified above is, for example, about 3 to 10 in the case of a polyimide resin, and about 2 to 5 in the case of a cured alkoxysilane. The constituent material of the surface layer 3 is made to contain a dielectric constant adjuster appropriately according to the type of the film-forming component based on the set value of the dielectric constant of the surface layer 3 .

As the dielectric constant adjuster, for example, the ferroelectric substance and conductive agent described in the section of the base material layer 2 can be used. Ferroelectrics include barium titanate and the like, and conductive agents include carbon black and the like.

The ratio of the dielectric constant adjuster to the film forming component in the constituent material of the surface layer 3 is such that the surface S1 of the resulting surface layer 3 has a Martens hardness of 300 to 700 N/mm ² and the dielectric constant of the surface layer 3 is a predetermined value. Set to a range of values. In addition, the constituent material of the surface layer 3 contains other components other than the film-forming components and the dielectric constant adjuster, if necessary, within the range that the surface layer 3 obtained does not impair the characteristics of Martens hardness and dielectric constant. You may Other components include components similar to other components in the constituent material of the base material layer 2 .

When the surface layer 3 contains components such as a cured sol-gel material and a dielectric constant modifier as film-forming components, the surface layer 3 typically contains components such as a sol-gel material and a dielectric constant modifier. It is a layer obtained by curing the composition. As used herein, the term “cured product of the composition” refers to a cured product obtained by curing the composition as a whole when the composition contains a curable component and the curable component cures.

Here, regarding the surface layer for satisfying the requirements (2) and (3) related to the transfer belt of the present invention, a two-layer structure consisting of a base layer and a surface layer such as the transfer belt 1A and a transfer belt Preferred embodiments of each of the three-layer structures such as 1B consisting of a substrate layer, an intermediate layer and a surface layer will be described below. In the case of the three-layer structure, it is necessary to consider the structure for satisfying the requirement (2) as a pair of the intermediate layer and the surface layer. Therefore, in the case of the three-layer structure, the surface layer and the intermediate layer are paired for explanation.

<Surface layer in the case of two-layer structure>
For the surface layer in the case of the two-layer structure, taking the transfer belt 1A as an example, the hardness of the surface S1 on the surface layer 3 side is the requirement (3), that is, the Martens hardness is within the range of 300 to 700 N/mm ^{2 .} It satisfies the requirement of Further, as described above, in order for the transfer belt 1A to satisfy the requirement (2), the surface layer 3 preferably has a layer thickness Ts of, for example, 5 μm or more, more preferably in the range of 5 to 20 μm, and 10 to 10 μm. More preferably within the range of 20 μm. Also, the dielectric constant of the surface layer 3 is 10 or less, preferably in the range of 2-10, more preferably 2-5.

Considering these factors, the constituent material of the surface layer 3 of the transfer belt 1A is selected from super engineering plastics having strength and durability, such as polyimide resin, polyamideimide resin, polyphenylene sulfide resin, and polyether ether ketone resin, as film-forming components. Polyimide resin is more preferable. When a polyimide resin is used, the surface layer 3 can be composed only of the polyimide resin. When a polyimide resin is used, the surface layer 3 may contain a dielectric constant adjuster. For example, carbon black is added to the entire surface layer 3 in an amount of 1 to 15% by volume, depending on the set value of the dielectric constant. can be contained within the range of Moreover, when the dielectric constant of the surface layer 3 is set higher than the dielectric constant of the polyimide resin, barium titanate may be used as the dielectric constant adjuster.

The surface layer 3 of the transfer belt 1A has a Martens hardness of 300 to 400 N/mm ² , a dielectric constant of 3 to 10, and a layer thickness Ts of 10 to 20 μm on the surface S1 when the film-forming component is a polyimide resin. is preferred.

<Surface layer and intermediate layer in case of three-layer structure>
For the surface layer in the case of the three-layer structure, taking the transfer belt 1B as an example, the hardness of the surface S1 on the surface layer 3 side is the requirement (3), that is, the Martens hardness is within the range of 300 to 700 N/mm ^{2 .} It satisfies the requirement of Also, as described above, in order for the transfer belt 1B to satisfy the requirement (2), for example, the combination of the dielectric constants and layer thicknesses of the surface layer 3 and the intermediate layer 4 is appropriately selected.

Specifically, as described above, the total layer thickness of the layer thickness Ts of the surface layer 3 and the layer thickness Tm of the intermediate layer 4 is preferably in the range of 10 to 20 μm, more preferably in the range of 15 to 20 μm. . Also, the dielectric constant of the surface layer 3 is preferably in the range of 2-10, more preferably 2-5. The dielectric constant of the intermediate layer 4 is preferably in the range of 5-20, more preferably 5-10. Furthermore, the layer thickness Ts of the surface layer 3 is preferably in the range of 1 to 15 μm, more preferably in the range of 1 to 10 μm. The layer thickness Tm of the intermediate layer 4 is preferably within the range of 5 to 15 μm, more preferably within the range of 10 to 15 μm.

The constituent material of the surface layer 3 in the transfer belt 1B may be any of cured products obtained by curing the above-described resins and sol-gel materials as film-forming components. As the resin, polyimide resin, polyamideimide resin, polyphenylene sulfide resin, polyetheretherketone resin, etc. are preferable, and polyimide resin is more preferable. These resins may be used individually by 1 type, and may be used in combination of 2 or more type. From the viewpoint of achieving a Martens hardness in the high range of 300 to 700 N/mm ² , the film-forming component is preferably a cured product obtained by curing a sol-gel material, more preferably an alkoxysilane cured product.

When the film-forming component is a polyimide resin, the surface layer 3 of the transfer belt 1B may be made of only the polyimide resin, and may further contain a dielectric constant adjuster. When the constituent material of the surface layer 3, which contains a polyimide resin as a film-forming component, contains a dielectric constant adjuster, for example, carbon black is added to the entire surface layer 3 according to the set value of the dielectric constant. It can be contained within a range of up to 15% by volume. Further, when the dielectric constant of the surface layer 3 is set higher than the dielectric constant of the polyimide resin, for example, barium titanate as a dielectric constant adjuster is added to the entire surface layer 3 by 1 to 15 volumes. You may use it in the range of %.

The surface layer 3 of the transfer belt 1B has a Martens hardness of 300 to 400 N/mm ² , a dielectric constant of 6 to 8, and a layer thickness Ts of 1 to 10 μm on the surface S1 when the film-forming component is a polyimide resin. is preferred.

As for the constituent material of the surface layer 3 of the transfer belt 1B, when the film-forming component is a cured product of alkoxysilane, the surface layer 3 may be composed only of a cured product of alkoxysilane, and further contains a dielectric constant adjuster. may When the constituent material of the surface layer 3, which contains a cured product of alkoxysilane as a film-forming component, contains a dielectric constant adjuster, for example, titanic acid is added to the entire surface layer 3 according to the set value of the dielectric constant. Barium may be contained within the range of 1-15% by volume. Similarly, carbon black can be contained within the range of 1 to 15% by volume with respect to the entire surface layer 3 .

The surface layer 3 of the transfer belt 1B has a Martens hardness of 400 to 700 N/mm ² , a dielectric constant of 2 to 6, and a layer thickness Ts of 1 to 5 μm when the film forming component is a cured product of alkoxysilane. A preferred embodiment is

The intermediate layer 4 in the transfer belt 1B preferably has the layer thickness and dielectric constant as described above so that the transfer belt 1B satisfies the requirement (2). Like the material of the surface layer 3, the material of the intermediate layer 4 contains, for example, a film-forming component for maintaining the shape of the layer as an essential component, and optionally contains a dielectric constant adjuster.

Examples of the film-forming component of the intermediate layer 4 include resins similar to those used for the base layer 2, preferably polyimide resins, polyamideimide resins, polyphenylene sulfide resins, polyetheretherketone resins, etc., and more preferably polyimide resins. . These resins may be used individually by 1 type, and may be used in combination of 2 or more type.

In order to obtain the preferable relative dielectric constant in the intermediate layer 4, the constituent material of the intermediate layer 4 may contain a relative dielectric constant adjuster. For example, in the material constituting the intermediate layer 4 in the transfer belt 1B, when the film-forming component is a polyimide resin, the intermediate layer 4 may be composed only of the polyimide resin in order to obtain the preferable dielectric constant. It may contain a dielectric constant adjuster.

When the constituent material of the intermediate layer 4, which contains a polyimide resin as a film-forming component, contains a dielectric constant adjuster, for example, carbon black is added to the entire intermediate layer 4 according to the set value of the dielectric constant. , 1 to 15% by volume. Further, when the relative dielectric constant of the intermediate layer 4 is set higher than that of the polyimide resin, for example, barium titanate as a relative dielectric constant adjuster is added to the intermediate layer 4 as a whole to 1 to You may use within the range of 40 volume%.

The physical properties of the intermediate layer 4, such as relative permittivity and layer thickness, are as described above.

[Manufacturing method of transfer belt]
As a method for manufacturing the transfer belt of the present invention, a known method for manufacturing a transfer belt can be applied. For example, in the case of a transfer belt having an endless structure, a cylindrical mold is used as a mold for molding, and each layer is sequentially formed on the outer peripheral surface or the inner peripheral surface of the mold, and then removed from the mold. can be manufactured. Film formation is preferably performed by a wet method. That is, first, a coating liquid for forming each layer constituting the transfer belt is prepared, and each layer is formed on the outer peripheral surface or the inner peripheral surface of the mold by coating, drying, and curing using the coating liquid to a predetermined amount. form in order.

Hereinafter, the method for manufacturing the transfer belt of the present invention will be described by taking as an example a transfer belt 1B having a three-layer structure in which a base layer 2, an intermediate layer 4 and a surface layer 3 are laminated in this order. Note that the following manufacturing method is an example, and any method that can manufacture a transfer belt can be used.

(Preparation of coating liquid)
As the coating liquids, a base layer forming coating liquid, an intermediate layer forming coating liquid, and a surface layer forming coating liquid are prepared corresponding to the base layer 2, the intermediate layer 4, and the surface layer 3, respectively. When the film-forming components of the base material layer 2, the intermediate layer 4, and the surface layer 3 are resins, the coating liquid may contain the resin itself, and a varnish containing a precursor of the resin as a main component such as polyimide varnish. etc. may be included.

The substrate layer-forming coating liquid contains a conductive agent, and optionally ferroelectric particles, in addition to the resin or resin precursor. The content of each component is adjusted, for example, so that the obtained base material layer has the above content. The substrate layer-forming coating liquid contains, in addition to the solid content constituting the substrate layer, a volatile component that is usually volatilized and removed during drying and curing. Volatile components include, for example, solvents. The viscosity of the substrate layer-forming coating liquid is set according to the thickness of the coating film, coating method, coating conditions, solution temperature, and the like. Adjustment of viscosity is performed by adjusting the kind or content of a solvent, for example.

In order to improve the state of dispersion of the conductive agent and the ferroelectric particles in the coating solution for forming the substrate layer, these components are previously dispersed in a dispersion medium to prepare a dispersion solution. You may use for preparation of the coating liquid for material layer formation. The dispersion may contain a dispersant to an extent that does not affect the dielectric constant and mechanical properties of the substrate layer. The dispersion medium is preferably the same as the solvent in the base layer forming coating liquid.

The intermediate layer-forming coating liquid and the surface layer-forming coating liquid when the film-forming component of the intermediate layer 4 and the surface layer 3 is a resin can also be prepared in the same manner as the substrate layer-forming coating liquid. When a conductive agent or ferroelectric particles are used as the dielectric constant adjuster, it is preferable to prepare each layer-forming coating liquid using a dispersion liquid in the same manner as described above. The content of each component is adjusted, for example, so that the obtained intermediate layer and surface layer have the above content.

When the film-forming component of the surface layer 3 is a sol-gel material, for example, a cured product of alkoxysilane, the surface layer-forming coating liquid contains the alkoxysilane and each component contained in the surface layer as a solid content, and a solvent and the like as a volatile component. contains The solvent to be used is not particularly limited as long as it can uniformly disperse and dissolve the alkoxysilane and the organic component. Examples thereof include various alcohols such as methanol and ethanol, as well as acetone, toluene, and xylene. . Although the hydrolysis of alkoxysilane, which will be described later, can be carried out using moisture in the atmosphere, the coating liquid for surface layer formation may contain water for hydrolysis of the alkoxysilane, if necessary.

When a dielectric constant modifier such as a conductive agent or ferroelectric particles is contained in addition to the alkoxysilane, it is preferable to prepare the surface layer forming coating liquid using the dispersion liquid in the same manner as described above.

Alkoxysilane forms a cured product through a dehydration-condensation reaction after hydrolysis. In order to accelerate the hydrolysis reaction of the alkoxysilane, the surface layer forming coating liquid may appropriately contain a catalyst such as hydrochloric acid, phosphoric acid, or acetic acid. The coating liquid for surface layer formation can also contain alkoxysilane as a hydrolyzate. By using a hydrolyzate, the dehydration condensation reaction may proceed gradually. The viscosity of the surface layer forming coating liquid is preferably in the range of 10 to 100 cP for smooth coating. The degree of hydrolysis when forming a hydrolyzate is preferably such that the viscosity of the surface layer forming coating liquid can be maintained within the above range.

(Formation of each layer)
Then, each layer is sequentially formed (film-formed) on the outer peripheral surface or the inner peripheral surface of the cylindrical mold. The following is an example of film formation using the outer peripheral surface of the mold. The order of forming each layer on the outer peripheral surface of the mold is the order of the base layer 2, the intermediate layer 4, and the surface layer 3, or the order of the surface layer 3, when the film-forming components of each layer are all resins, particularly polyimide resins. The order is the intermediate layer 4 and the base layer 2 . When the surface layer 3, the intermediate layer 4, and the substrate layer 2 are formed in this order, the inner peripheral surface and the outer peripheral surface of the obtained laminate are reversed after removing from the mold.

When the film forming component of the surface layer 3 is a cured sol-gel material such as alkoxysilane, for example, a method of forming films on the outer peripheral surface of the mold in the order of the base layer 2, the intermediate layer 4, and the surface layer 3, or the mold A laminate is formed on the outer peripheral surface of the intermediate layer 4 and the base layer 2 in this order, and after removing it from the mold, the inner peripheral surface and the outer peripheral surface of the obtained laminate are reversed, and then gold is applied to the laminate. A method of forming the surface layer 3 on the outer peripheral surface of the laminate, that is, on the outer peripheral surface of the intermediate layer 4 by inserting a mold can be used.

In the following, first, an example in which the film-forming components of each layer are all resins and the films are formed in the order of the surface layer 3, the intermediate layer 4, and the substrate layer 2 will be described. When the film-forming components of each layer are all resins and the films are formed in the order of the substrate layer 2, the intermediate layer 4, and the surface layer 3, the steps are the same except that the order of layer formation is changed.

The application of the surface layer forming coating liquid to the outer peripheral surface of the cylindrical mold can be performed by, for example, the apparatus shown in FIG. FIG. 4 shows an example of a coating device used when producing the transfer belt of the present invention. As shown in FIG. 4, the coating device 1b includes coating means 2b (for example, a dispenser nozzle) having a nozzle, and a metal cylindrical mold 5b.

The coating means 2b atomizes the surface layer forming coating liquid 3b onto the outer peripheral surface of the cylindrical mold 5b to form a coating film 4b on the cylindrical mold 5b. Specifically, the cylindrical mold 5b is rotated at a desired speed in the direction of the arrow 7b, and while the coating means 2b is moved in the direction of the arrow 6b, the surface layer forming coating solution 3b is cast from the nozzle. A uniform coating film 4b is formed. The thickness of the coating film 4b is adjusted so that the thickness of the surface layer obtained after drying and curing is a predetermined thickness.

The number of rotations of the cylindrical mold 5b can be appropriately set according to the viscosity of the surface layer forming coating liquid 3b, the size of the cylindrical mold 5b, and the like, and is preferably about 30 to 100 rpm, for example.

Next, the coating film made of the surface layer forming coating liquid formed on the outer peripheral surface is dried and cured to form the surface layer 3 . Drying of the coated film is a step of removing volatile components such as a solvent in the surface layer forming coating liquid. When the surface layer forming coating liquid contains a resin itself, it is cured by drying. When the coating liquid for surface layer formation contains a resin precursor, curing is a step of causing a curing reaction of the resin precursor in the coating liquid for surface layer formation to form a resin. The curing reaction of the resin precursor is, for example, imidization of a polyimide precursor or polyamideimidation of a polyamideimide precursor.

Drying is preferably effected by heating and curing is effected by heating to the reaction temperature. When both drying and curing are performed by heating, the heat treatment may be performed in one stage, or may be performed in a multi-stage heating method. By using the multi-stage heating method, it is possible to prevent the generation of minute voids in the seamless belt due to evaporation of ring-closing water and solvent generated in the curing reaction.

The heating in the first stage is low-temperature heating, for example, heating at a low temperature of about 50 to 150° C. to remove the solvent. The heating time is appropriately set according to the type and content of volatile components such as the solvent in the surface layer forming coating liquid, the heating temperature, and the like, but is preferably about 30 to 90 minutes. The low-temperature heating is preferably carried out until the state of the film after low-temperature heating reaches a state in which the film itself can be supported, ie, a state in which it has self-supporting properties. Further, the low-temperature heating is preferably performed while rotating the cylindrical mold about its axis, and the rotation speed is preferably, for example, about 30 to 100 rpm. Furthermore, in this step, it is preferable to efficiently circulate and remove atmospheric vapor (volatilized solvent, etc.).

Heating for curing performed after low-temperature heating is high-temperature heating, and the heating temperature can be as high as about 250 to 450° C., for example, depending on the temperature of the curing reaction of the resin precursor. The heating time is appropriately set according to the type of resin precursor, the thickness of the surface layer, the heating temperature, etc., but is preferably about 30 to 120 minutes. In addition, in the heat treatment, it is preferable to raise the temperature stepwise in both cases of low-temperature heating and high-temperature heating.

Next, an intermediate layer forming coating liquid is applied to the outer peripheral surface of the surface layer 3 formed on the outer peripheral surface of the mold, dried and cured to form the intermediate layer 4 . The application, drying, and curing of the intermediate layer-forming coating liquid can be performed in the same manner as in the formation of the surface layer 3 using the surface layer-forming coating liquid. Furthermore, the surface layer 3 and the intermediate layer 4 are laminated in this order on the outer peripheral surface of the mold. The application, drying, and curing of the substrate layer-forming coating liquid can be performed in the same manner as in the formation of the surface layer 3 using the surface layer-forming coating liquid.

By omitting the formation (film formation) of the intermediate layer 3 in the production of the transfer belt 1B, the transfer belt 1A having a two-layer structure in which the base layer 2 and the surface layer 3 are laminated in this order can be produced.

Next, the case where the film forming component of the surface layer 3 is a cured sol-gel material such as alkoxysilane will be described. When the substrate layer 2, the intermediate layer 4, and the surface layer 3 are formed in this order on the outer peripheral surface of the mold, the substrate layer 2 and the intermediate layer 4 are formed when all the film-forming components of the above layers are resins. can be done in the same way as In addition, a laminate is molded in the order of the intermediate layer 4 and the base material layer 2, and after removing it from the mold, the inner peripheral surface and the outer peripheral surface of the obtained laminate are reversed, and the mold is placed on the laminate. In the method of inserting and forming the surface layer 3 on the outer peripheral surface of the intermediate layer 4, also in the method of forming the laminate in the order of the intermediate layer 4 and the base material layer 2, the film-forming components of the above layers are all resins. can be done in the same way as

On the outer peripheral surface of the mold, the substrate layer 2 and the intermediate layer 4 are laminated in this order, that is, on the outer peripheral surface of the intermediate layer 4, the film-forming component is a sol-gel material, for example, a cured product of alkoxysilane. In order to form a certain surface layer 3 , a coating liquid containing the alkoxysilane or its hydrolyzate is used as the surface layer forming coating liquid for forming the surface layer 3 .

Specifically, the surface layer 3 can be formed by coating the surface layer forming coating solution to form a coating film, and curing the alkoxysilane in the coating film by hydrolysis and dehydration condensation reaction. .

A preferred method for applying the surface layer forming coating liquid to the outer peripheral surface of the intermediate layer 4 is, for example, spray coating. The coated film of the surface layer forming coating liquid is then dried and cured to form the surface layer 3 . Drying of the coated film is a step of removing volatile components such as a solvent in the surface layer forming coating liquid. The curing treatment is a step of curing the alkoxysilane by hydrolysis and dehydration condensation reaction.

Drying of the coated film of the surface layer forming coating liquid may be carried out by natural drying, but is typically carried out by heat treatment. Here, the heat treatment for drying also promotes curing due to hydrolysis and dehydration condensation reactions. Therefore, drying and curing can be performed in a single heat treatment. The conditions for the heat treatment are not particularly limited as long as the surface layer 3 having a hardness within a predetermined range can be formed. Depending on the layer thickness of the surface layer 3, the coating step may be performed not only once but also multiple times. That is, the surface layer 3 may consist of one coat, or may consist of multiple coats.

≪Application≫
The transfer belt of the present invention is used as an intermediate transfer belt for developing a latent image formed on an image carrier (photoreceptor) with toner and transferring the obtained toner image to a transfer material in an electrophotographic image forming apparatus. is preferred. It is also preferable to use it as a secondary transfer belt (paper transport belt) on which the transfer material is placed when the toner image on the intermediate transfer belt is transferred (secondary transfer) onto a transfer material such as paper.

[Electrophotographic image forming apparatus]
The transfer belt of the present invention described above can be suitably used as an intermediate transfer belt or a secondary transfer belt in various known electrophotographic image forming apparatuses such as a monochrome image forming apparatus and a full-color image forming apparatus. .

FIG. 3 is a cross-sectional view showing an example of the configuration of an image forming apparatus equipped with the transfer belt of the present invention as an intermediate transfer belt.

This image forming apparatus includes a plurality of sets of image forming units 20Y, 20M, 20C, and 20Bk, and an intermediate transfer section that transfers toner images formed in these image forming units 20Y, 20M, 20C, and 20Bk onto a transfer material P. 10, and a fixing device 30 for performing a fixing process to obtain a toner layer by fixing the toner image by applying heat and pressure to the transfer material P. As shown in FIG.

A yellow toner image is formed in the image forming unit 20Y, a magenta toner image is formed in the image forming unit 20M, and a cyan toner image is formed in the image forming unit 20C. In 20Bk, a black toner image is formed.

The image forming units 20Y, 20M, 20C, and 20Bk apply a uniform potential to the surfaces of the photoreceptors 11Y, 11M, 11C, and 11Bk, which are electrostatic latent image carriers, and the photoreceptors 11Y, 11M, 11C, and 11Bk. charging means 23Y, 23M, 23C and 23Bk; exposure means 22Y, 22M, 22C and 22Bk for forming electrostatic latent images of desired shapes on the uniformly charged photoreceptors 11Y, 11M, 11C and 11Bk; Developing means 21Y, 21M, 21C, and 21Bk for conveying chromatic toner onto photoreceptors 11Y, 11M, 11C, and 11Bk to visualize electrostatic latent images, and photoreceptors 11Y, 11M, 11C, and 11Bk after primary transfer. Cleaning means 25Y, 25M, 25C, and 25Bk are provided for collecting residual toner remaining thereon.

The intermediate transfer section 10 includes an intermediate transfer belt 16 that circulates and a primary transfer roller 13Y as a primary transfer means that transfers toner images formed by the image forming units 20Y, 20M, 20C, and 20Bk onto the intermediate transfer belt 16; 13M, 13C, 13Bk and secondary transfer rollers as secondary transfer means for transferring the chromatic toner images transferred onto the intermediate transfer belt 16 by the primary transfer rollers 13Y, 13M, 13C, 13Bk onto the transfer material P. 13A, and cleaning means 12 for collecting residual toner remaining on the intermediate transfer belt 16. FIG.

The transfer belt of the present invention is used as the intermediate transfer belt 16 . The intermediate transfer belt 16 is an endless belt that is stretched and rotatably supported by a plurality of support rollers 16a to 16d.

The toner images of each color formed by the image forming units 20Y, 20M, 20C, and 20Bk are sequentially transferred onto the rotating endless intermediate transfer belt 16 by the primary transfer rollers 13Y, 13M, 13C, and 13Bk, and superimposed. A mixed color image is formed. A transfer material P accommodated in a paper feed cassette 41 is fed by a paper feed transport means 42, passed through a plurality of intermediate rollers 44a to 44d and a registration roller 46, and transferred to a secondary transfer roller 13A as a secondary transfer means. A color image is transferred onto the transfer material P all at once. The transfer material P onto which the color image has been transferred is subjected to fixing processing by a fixing device 30 equipped with a heat roller fixing device, and is sandwiched between paper discharge rollers and placed on a paper discharge tray outside the machine.

On the other hand, after the color image is transferred onto the transfer material P by the secondary transfer roller 13A, residual toner is removed by the cleaning means 12 from the intermediate transfer belt 16 having an endless structure that separates the transfer material P by curvature.

According to the image forming apparatus as described above, since the intermediate transfer belt is made of the transfer belt of the present invention, the intermediate transfer belt has excellent transferability and cleanability as well as high durability. , an image with high image quality can be formed over a long period of time.

[Developer]
The developer used in the image forming apparatus of the present invention may be a one-component developer using magnetic or non-magnetic toner, or may be a two-component developer in which toner and carrier are mixed. As the toner constituting the developer, various known ones can be used without any particular limitation. For example, it is preferable to use a so-called polymerized toner having a volume-based median diameter of 3 to 9 μm and obtained by a polymerization method. By using the polymerized toner, a high resolution and a stable image density can be obtained in the formed image, and the occurrence of image fogging can be greatly suppressed.

As the carrier for forming the two-component developer, various known carriers can be used without any particular limitation. For example, a ferrite carrier composed of magnetic particles having a volume-based median diameter of 30 to 65 μm and a magnetization amount of 20 to 70 emu/g is preferable. If a carrier with a volume-based median diameter of less than 30 μm is used, carrier adhesion may occur, resulting in a blank image. An image with uniform image density may not be formed.

[Transfer material]
The transfer material P used in the image forming apparatus of the present invention includes plain paper from thin paper to thick paper, fine paper, coated printing paper such as art paper and coated paper, commercially available Japanese paper and postcard paper, Various kinds of OHP plastic films, cloths, etc. can be mentioned, but the material is not limited to these. By using the transfer belt of the present invention, it is possible to form a high-quality image without impairing the transferability of the toner image onto the transfer material even when the uneven paper is used as the transfer material.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these.

[Example 1]
By using the same device as shown in FIG. 4, each layer is formed in the order of the surface layer and the base layer on the outer peripheral surface of the stainless steel cylindrical mold, and the inner peripheral surface and the outer peripheral surface are reversed to obtain the structure shown in FIG. 3A. A transfer belt 1 was manufactured as an endless belt having a two-layer structure composed of a base layer 2 and a surface layer 3 similar to the transfer belt 1A.

<Preparation of dispersion>
The following dispersion liquid A and dispersion liquid B were prepared and used as coating liquids for forming each layer.
Dispersion A: A dispersion obtained by dispersing barium titanate particles “BT05” (manufactured by Sakai Chemical Industry Co., Ltd.) in a solvent (N-methyl-2-pyrrolidone).
Dispersion B: A dispersion obtained by dispersing carbon black “MA11” (manufactured by Mitsubishi Chemical Corporation) in a solvent (N-methyl-2-pyrrolidone).

<Formation of surface layer>
Dispersion B is added to polyimide varnish "Upia-AT (U-Varnish-A)" (manufactured by Ube Industries, Ltd.) so that the total solid content of the surface layer is 5% by volume of carbon black, and a mixer is added. and mixed to prepare a coating liquid for forming a substrate layer.

Next, while rotating the cylindrical mold made of stainless steel around the cylindrical axis, the dispensing nozzle is moved in the axial direction, and the layer thickness after drying the base layer forming coating liquid from the nozzle becomes 20 μm. , and applied spirally on the outer peripheral surface of the mold to form a coating film in which they were connected.

Next, by heating the cylindrical mold at 100°C for 1 hour while rotating, most of the solvent is volatilized from the coated film, and then heated at 230°C for 1 hour to remove the An endless belt-like surface layer was formed.

<Formation of base material layer>
Dispersions A and B are added to polyimide varnish "Upia-AT (U-Varnish-A)" (manufactured by Ube Industries, Ltd.), barium titanate 10% by volume, carbon black 5 based on the total solid content of the base layer. It added so that it might become volume%, and it mixed using the mixer, and prepared the coating liquid for base material layer formation.

Next, while the mold having the surface layer formed on the outer peripheral surface obtained above is rotated about the cylindrical axis, the dispensing nozzle is moved in the axial direction, and the coating liquid for forming the base material layer is discharged from the nozzle. It was discharged so that the layer thickness after drying was 50 μm, and was spirally applied to the outer peripheral surface of the surface layer formed on the outer peripheral surface of the mold to form a coating film in which the layers were connected.

Next, the mold is heated at 100°C for 1 hour while rotating to volatilize most of the solvent from the coated film, and then heated at 360°C for 1 hour to form an endless belt with a two-layer structure. bottom. The obtained endless belt was removed from the mold, and the transfer belt 1 was obtained by reversing the inner peripheral surface and the outer peripheral surface.

[Example 2]
By using the same apparatus as in Example 1, each layer is formed on the outer peripheral surface of a stainless steel cylindrical mold in the order of a surface layer, an intermediate layer and a base layer, and the inner peripheral surface and the outer peripheral surface are reversed to obtain the structure shown in FIG. 3B. A transfer belt 2 was manufactured as an endless belt having a three-layer structure composed of a base layer 2, an intermediate layer 4, and a surface layer 3 similar to the transfer belt 1B shown.

<Formation of surface layer>
Apply "Upia-AT (U-Varnish-A)" (manufactured by Ube Industries, Ltd.) from a stainless steel cylindrical mold while rotating it around the cylindrical axis and moving the dispensing nozzle in the axial direction. The liquid was discharged so that the layer thickness after drying was 5 μm, and the liquid was applied spirally onto the outer peripheral surface of the mold to form a coating film in which the liquid was connected.

Next, while rotating the cylindrical mold, it is heated at 100°C for 1 hour to volatilize most of the solvent from the coating film, and then heated at 230°C for 1 hour to form an endless film on the outer peripheral surface of the mold. A belt-like surface layer was formed.

<Formation of Intermediate Layer>
Dispersion B is added to polyimide varnish "Upia-AT (U-Varnish-A)" (manufactured by Ube Industries, Ltd.) so that carbon black becomes 5.5% by volume based on the total solid content of the intermediate layer. , and mixed using a mixer to prepare a coating solution for forming an intermediate layer.

While the mold having the surface layer formed on the outer peripheral surface obtained above is rotated around the cylindrical axis, the dispensing nozzle is moved in the axial direction, and the coating liquid for forming the intermediate layer is dried from the nozzle. It was extruded to a thickness of 10 μm, and applied spirally to the outer peripheral surface of the surface layer formed on the outer peripheral surface of the mold to form a coating film in which the layers were connected.

Next, the mold is heated at 100° C. for 1 hour while rotating to volatilize most of the solvent from the coating film, and then heated at 230° C. for 1 hour to obtain an endless film on the outer peripheral surface of the mold. A laminate was obtained in which a belt-like surface layer and an intermediate layer were formed in that order.

<Formation of base material layer>
Dispersions A and B are added to polyimide varnish "Upia-AT (U-Varnish-A)" (manufactured by Ube Industries, Ltd.), barium titanate 10% by volume, carbon black 5 based on the total solid content of the base layer. It added so that it might become volume%, and it mixed using the mixer, and prepared the coating liquid for base material layer formation.

The mold obtained above, in which the surface layer and the intermediate layer are laminated on the outer peripheral surface, is rotated around the cylindrical axis, and the dispensing nozzle is moved in the axial direction, and the coating liquid for forming the base layer is discharged from the nozzle. It was discharged so that the layer thickness after drying was 50 μm, and was spirally applied to the outer peripheral surface of the intermediate layer formed on the outer peripheral surface of the mold to form a coating film in which the layers were connected.

Next, the mold is heated at 100° C. for 1 hour while rotating to volatilize most of the solvent from the coating film, and then heated at 360° C. for 1 hour to give the following on the outer peripheral surface of the mold. A laminate was obtained in which an endless belt-like surface layer, an intermediate layer and a base layer were formed in that order. The obtained endless belt-like laminated body was removed from the mold, and the transfer belt 2 was obtained by inverting the inner peripheral surface and the outer peripheral surface.

[Example 3]
Using the same apparatus as in Example 1, the intermediate layer and the substrate layer are formed in this order on the outer peripheral surface of a cylindrical mold made of stainless steel, and the resulting laminate is removed from the mold. Furthermore, after inserting a mold into the laminated body in which the inner peripheral surface and the outer peripheral surface are reversed, a surface layer is formed on the outer peripheral surface of the intermediate layer, thereby forming a base layer 2 similar to the transfer belt 1B shown in FIG. 3B. A transfer belt 3 was manufactured as an endless belt having a three-layer structure consisting of an intermediate layer 4 and a surface layer 3 .

<Formation of Intermediate Layer>
Dispersion B is added to polyimide varnish "Upia-AT (U-Varnish-A)" (manufactured by Ube Industries, Ltd.) so that carbon black becomes 5.5% by volume based on the total solid content of the intermediate layer. , and mixed using a mixer to prepare a coating solution for forming an intermediate layer.

A cylindrical mold made of stainless steel was rotated around the cylindrical axis, and the dispensing nozzle was moved in the axial direction, and the intermediate layer forming coating liquid was discharged from the nozzle so that the layer thickness after drying was 12 μm. Then, it was spirally applied on the outer peripheral surface of the mold to form a coating film in which they were connected.

Next, the cylindrical mold is heated at 100° C. for 1 hour while rotating to volatilize most of the solvent, and then heated at 230° C. for 1 hour to form an endless belt on the outer peripheral surface of the mold. An intermediate layer was formed.

<Formation of base material layer>
Dispersions A and B are added to polyimide varnish "Upia-AT (U-Varnish-A)" (manufactured by Ube Industries, Ltd.), barium titanate 10% by volume, carbon black 5 based on the total solid content of the base layer. It added so that it might become volume%, and it mixed using the mixer, and prepared the coating liquid for base material layer formation.

After drying the base layer-forming coating liquid from the nozzle while moving the dispensing nozzle in the axial direction while rotating the mold having the intermediate layer formed on the outer peripheral surface obtained above, around the cylindrical axis. was discharged so as to have a layer thickness of 50 μm, and was spirally applied to the outer peripheral surface of the intermediate layer formed on the outer peripheral surface of the mold to form a coating film in which the layers were connected.

Next, the mold is heated at 100° C. for 1 hour while rotating to evaporate most of the solvent, and then heated at 360° C. for 1 hour to form an endless belt on the outer peripheral surface of the mold. A laminate was obtained in which the intermediate layer and the substrate layer were formed in that order.

<Formation of surface layer>
A surface layer forming coating liquid was prepared by dissolving 90 g of tetraethoxysilane, 10 g of triethylethoxysilane and 100 g of butanol, and further adding barium titanate to the total solid content of the surface layer so as to be 3% by volume. .

The endless belt-like laminated body in which the intermediate layer and the base material layer were laminated was removed from the mold, the inner peripheral surface and the outer peripheral surface were reversed, and then the mold was fitted. On the outer peripheral surface of the intermediate layer of the laminate in which the mold is fitted, the surface layer forming coating liquid is sprayed under the following coating conditions so that the dry layer thickness of the coating layer is 3 μm (spray device: Wide Mechatronics Solutions Co., Ltd. ) to form a coating film, which is then baked at 100° C. for 60 minutes in an air atmosphere to form a surface layer, thereby obtaining a transfer belt 3 .

<Spray application conditions>
Nozzle scan speed: 1-10mm/sec
Nozzle distance: 100-150mm
Number of nozzles: 1
Application liquid supply rate: 1 to 5 mL/min
O ₂ flow rate: 2 to 6 L/min, air atmosphere

[Example 4]
A transfer belt 4 having a three-layer structure was manufactured in the same manner as in Example 3, except that the layer thickness of the surface layer was changed to 4 μm and the layer thickness of the intermediate layer was changed to 11 μm.

[Example 5]
Same as Example 3 except that the amount of barium titanate added to the base layer was 20% by volume with respect to the total solid content of the base layer, the layer thickness of the surface layer was 4 μm, and the layer thickness of the intermediate layer was 11 μm. Then, a transfer belt 5 having a three-layer structure was manufactured.

[Example 6]
In Example 3, the amount of barium titanate added to the base layer was set to 20% by volume based on the total solid content of the base layer, and the amount of carbon black added to the intermediate layer was set to 5 based on the entire solid content of the intermediate layer. A transfer belt 6 having a three-layer structure was manufactured in the same manner except that the thickness of the surface layer was changed to 2 μm and the thickness of the intermediate layer was changed to 13 μm.

[Example 7]
In Example 3, the amount of barium titanate added to the base layer was 20% by volume based on the total solid content of the base layer, and the amount of carbon black added to the intermediate layer was 5% by volume based on the total solid content of the intermediate layer. %, the addition amount of barium titanate in the surface layer to the total solid content of the surface layer was 2% by volume, the layer thickness was 2 μm, and the layer thickness of the intermediate layer was 13 μm. manufactured.

[Example 8]
In Example 1, the amount of carbon black added to the base layer was 10% by volume with respect to the total solid content of the base layer, the amount of barium titanate added was 30% by volume with respect to the entire solid content of the base layer, A transfer belt 8 having a two-layer structure was produced in the same manner, except that the amount of carbon black added to the surface layer was 3% by volume relative to the total solid content of the surface layer.

[Example 9]
In Example 3, the amount of carbon black added to the intermediate layer was 8% by volume, the layer thickness was 10 μm, and barium titanate was not added to the surface layer, except that the layer thickness was 5 μm. A transfer belt 9 was manufactured.

[Comparative Example 1]
A transfer belt 10 having a two-layer structure was manufactured by the following method.

<Formation of base material layer>
Dispersion B is added to polyimide varnish "Upia-AT (U-Varnish-A)" (manufactured by Ube Industries, Ltd.) so that carbon black becomes 5% by volume based on the total solid content of the base material layer, A coating liquid for forming a substrate layer was prepared by mixing using a mixer.

A cylindrical mold made of stainless steel is rotated around the cylindrical axis, and the dispensing nozzle is moved in the axial direction, and the coating liquid for forming the substrate layer is discharged from the nozzle so that the layer thickness after drying becomes 50 μm. Then, it was spirally applied on the outer peripheral surface of the mold to form a coating film in which they were connected.

Next, the cylindrical mold is heated at 100° C. for 1 hour while rotating to volatilize most of the solvent, and then heated at 360° C. for 1 hour to form an endless belt on the outer peripheral surface of the mold was formed.

<Formation of surface layer>
A surface layer was formed as follows by the method disclosed in JP-A-2019-197147. That is, for 100 parts by volume of zinc oxide particles, 8 parts by volume of 3-acryloxypropyltrimethoxysilane (KBM-5103; Shin-Etsu Chemical Co., Ltd.), which is a surface treatment agent, and a solvent (toluene: methanol = 1:1 (volume ratio) mixed solvent) 300 parts by volume), dispersed for 45 minutes using a wet media dispersion type device, and then the solvent was removed. Subsequently, it was dried at 150° C. for 10 minutes to obtain surface-treated zinc oxide 1.

For 100 parts by volume of tin oxide particles, 20 parts by volume of 3-acryloxypropyltrimethoxysilane (KBM-5103; Shin-Etsu Chemical Co., Ltd.), which is a surface treatment agent, and a solvent (toluene: isopropyl alcohol = 1:1 ( 700 parts by volume of the mixed solvent) of volume ratio) was mixed, dispersed for 40 minutes using a wet media dispersion type device, and then the solvent was removed. Subsequently, it was dried at 150° C. for 10 minutes to obtain surface-treated tin oxide 1.

Surface-treated zinc oxide 1 (first particles) 10 parts by volume, surface-treated tin oxide 1 (second particles) 15 parts by volume, monomer 1 (KAYARAD DPEA-12; Nippon Kayaku Co., Ltd. ) 68 parts by volume, photopolymerization initiator 1 (Irgacure OXE02; BASF) 5 parts by volume, reaction accelerator (KAYACURE EPA, Nippon Kayaku Co., Ltd.) 2 parts by volume, so that the solid content concentration is 15% by mass Then, a coating liquid 1 for forming a surface layer was prepared by dissolving and dispersing in methyl isobutyl ketone (MIBK) as a solvent.

The coating liquid is applied to the outer peripheral surface of the base material layer by a dip coating method using a coating device in an environment of 20 ° C. and a relative humidity of 50% so that the dry layer thickness is 1 μm to form a coating film. formed. Then, the coating film thus formed was irradiated with ultraviolet rays as active rays (active energy rays) under the following irradiation conditions to cure the coating film and form a surface layer on the outer peripheral surface of the substrate layer. The ultraviolet irradiation was carried out while the light source was fixed and the precursor formed with the coating film formed on the outer peripheral surface of the substrate layer was rotated at a peripheral speed of 60 mm/s.

(Ultraviolet irradiation conditions)
Type of light source: LED light source (SPX-TA; Eye Graphics)
Distance from the irradiation port to the surface of the coating film: 50 mm
Atmosphere: Nitrogen (oxygen concentration: 600 ppm or less)
Irradiation light amount: 3.3 J/cm ²
Irradiation time (precursor rotation time): 240 seconds Irradiation wavelength: 365 nm

[Comparative Example 2]
For base layer formation Dispersion liquid A and dispersion liquid B were added to the coating liquid so that the amount of barium titanate was 20% by volume and the amount of carbon black was 5% by volume, respectively, based on the total solid content of the base layer. A base layer was formed in the same manner as in Example 2 except for the above, and a surface layer was formed as follows to manufacture a transfer belt 11 having a two-layer structure.

<Formation of surface layer>
A methyl ethyl ketone solution (solid content 5% by mass) of polyvinylidene fluoride “KYNAR 740” (manufactured by Tokyo Zairyo Co., Ltd.) is applied to the outer peripheral surface of the obtained base layer using a coating device using a dip coating method. A coated film was formed by coating so as to have a thickness of 20 μm, and after applying hot air at 60° C. for 10 minutes, it was dried at 120° C. for 20 minutes.

[Comparative Example 3]
A two-layer structure was formed in the same manner as in Example 3 except that the intermediate layer was not formed, the amount of barium titanate added to the surface layer was 2% by volume with respect to the total solid content of the surface layer, and the layer thickness was 1 μm. A transfer belt 12 was manufactured.

[Comparative Example 4]
A transfer belt 13 having a three-layer structure was manufactured by the following method.
<Formation of base material layer>
Dispersion B is added to polyimide varnish "Upia-AT (U-Varnish-A)" (manufactured by Ube Industries, Ltd.) so that carbon black becomes 5% by volume based on the total solid content of the base material layer, A coating liquid for forming a substrate layer was prepared by mixing using a mixer.

Next, while rotating the cylindrical mold made of stainless steel around the cylindrical axis, the dispensing nozzle is moved in the axial direction, and the layer thickness after drying the base layer forming coating liquid from the nozzle becomes 50 μm. , and applied spirally on the outer peripheral surface of the mold to form a coating film in which they were connected.

Next, the cylindrical mold is heated at 100° C. for 1 hour while rotating to volatilize most of the solvent, and then heated at 360° C. for 1 hour to form an endless belt on the outer peripheral surface of the mold was formed.

<Formation of Intermediate Layer>
Dispersion B was adjusted so that carbon black was 5% by volume with respect to the total solid content of the intermediate layer, and acrylonitrile butadiene rubber "Nipol (registered trademark) 1041" (NBR) (manufactured by Nippon Zeon Co., Ltd.), which is an elastic material, was added. 38.5% by volume, 4% by volume of polychloroprene rubber “Denka Chloroprene DCR (registered trademark)-66” (manufactured by Denka) as an elastic material, 3% by volume of Al ₂ O ₃ and 1% of TiO ₂ % by volume, 3% by volume of SiO ₂ , and 10% by volume of sulfur as a cross-linking agent are dissolved and dispersed in toluene so that the solid content concentration is 20% by mass. A liquid was prepared.

After drying the intermediate layer forming coating liquid from the nozzle while moving the dispensing nozzle in the axial direction while rotating the mold having the base layer formed on the outer peripheral surface obtained above, around the cylindrical axis. was discharged so as to have a layer thickness of 15 μm, and was spirally coated on the outer peripheral surface of the mold to form a coating film in which they were connected.

Next, the mold is heated at 50° C. for 1 hour while rotating to volatilize most of the solvent, and then heated at 170° C. for 20 minutes to perform a thermal cross-linking treatment, thereby removing the outer peripheral surface of the mold. Then, a laminate was obtained in which an endless belt-like base material layer and an intermediate layer were formed in that order.

<Formation of surface layer>
In Comparative Example 2, the base layer and the intermediate layer were formed in the same manner except that the amount of barium titanate added to the surface layer was 5% by volume with respect to the total solid content of the surface layer, and the layer thickness of the surface layer was 5 μm. A surface layer was formed on the outer peripheral surface of the laminated body formed in order.

[Comparative Example 5]
In Example 3, a transfer belt 14 having a two-layer structure was manufactured by forming a surface layer as follows without forming an intermediate layer.

<Formation of surface layer>
Polyvinylidene fluoride "KYNAR 740" (manufactured by Tokyo Zairyo Co., Ltd.) is dispersed in a methyl ethyl ketone solution (solid content: 5% by mass) so that the amount of barium titanate added is 10% by volume based on the total solid content of the surface layer. Liquid A was added and mixed using a mixer to prepare a surface layer forming coating liquid.

The surface layer forming coating solution was applied to the outer peripheral surface of the obtained base material layer using a coating device using a dip coating method so that the thickness after drying was 20 μm to form a coating film. of hot air for 10 minutes and then dried at 120° C. for 20 minutes.

[Comparative Example 6]
A transfer belt 15 having a two-layer structure was manufactured in the same manner as in Example 1, except that 40% by volume of barium titanate was added to the base material layer.

[Measurement and evaluation of physical properties]
Using the transfer belts 1 to 15 obtained above, the following physical properties were measured and evaluated. The results are shown in Table I together with the configuration of the transfer belt.

The abbreviations in Table I are PI for polyimide resin, NBR for acrylonitrile butadiene rubber, CR for polychloroprene rubber, PVDF for polyvinylidene fluoride, and CB for carbon black.

<Measurement of dielectric constant and layer thickness>
Regarding transfer belts 1 to 15, the dielectric constant and layer thickness of each layer were measured by the above method. At the same time, the dielectric constant was measured in a region from the surface on the surface side to a depth of 15 μm.

<Measurement of Martens hardness>
For the transfer belts 1 to 15, the Martens hardness [N/mm ² ] on the outer surface was measured by the method described above.

<Transferability evaluation>
Under the following evaluation conditions, the image quality was compared by evaluating transferability using uneven paper. Lethac 302g paper was used, and the toner transfer state was ranked with respect to the depressions. A rank of 3 or higher was regarded as a pass.

(Evaluation conditions)
Environment: temperature 20°C, relative humidity 50%
Evaluation machine: bizhub PRESS C1100 (manufactured by Konica Minolta)

(Evaluation criteria)
Rank 5: Completely transferred.
Rank 4: Several points are missing from the second layer. There is no problem with the single color part.
Rank 3: The second layer is sparsely missing. There is no problem with the single color part.
Rank 2: The single-color part is sparsely missing.
Rank 1: The single-color portion is completely missing.

<Cleanability evaluation>
Under the following evaluation conditions, an image with a printing rate of 2.5% for each color of YMCK was subjected to live-action durability printing on A4 size Konica Minolta J paper, and then MC halftone images were printed on 3 sheets of the above paper, The resulting three halftone images were visually observed and evaluated according to the following criteria. △, ○ and ◎ are acceptable.

(Evaluation conditions)
Environment: temperature 20°C, relative humidity 50%
Evaluation machine: bizhub PRESS C1100 (manufactured by Konica Minolta)

(Evaluation criteria)
◎: No cleaning failure after 2 million copies (no defects such as streaks on the image)
◯: No cleaning failure after 1,000,000 copies (no defects such as streaks on the image)
△: Poor cleaning after 1,000,000 copies (defects such as streaks occurred on the image)
×: Poor cleaning after 500,000 copies (defects such as streaks occurred on the image)

<Durability evaluation>
A paper-passing durability test was performed under the following evaluation conditions to compare the belt breakage conditions. △ or more was set as the pass.
(Evaluation conditions)
Environment: temperature 20°C, relative humidity 50%
Evaluation machine: bizhub PRESS C1100 (manufactured by Konica Minolta)
Paper-passing endurance test: 2 million sheets of paper were passed, and the state of damage to the belt when passing 1 million sheets and when passing 2 million sheets were compared.

(Evaluation criteria)
⊚: No cracks after durability of 2,000,000 sheets.
◯: No cracks after durability of 1,000,000 sheets.
Δ: Damage was confirmed at the edges after 1,000,000 copies.
x: After 1,000,000 copies, damage was confirmed not only at the edge but also at the center.

Table I shows that the transfer belt of the present invention is excellent in transferability, cleanability and durability.

1A, 1B transfer belt 2 base layer 3 surface layer 4 intermediate layer 10 intermediate transfer section 11Y, 11M, 11C, 11Bk photoreceptor 12 cleaning means 13Y, 13M, 13C, 13Bk primary transfer roller 13A secondary transfer roller 16 intermediate transfer belt 16a ~16d Support rollers 20Y, 20M, 20C, 20Bk Image forming units 21Y, 21M, 21C, 21Bk Developing means 22Y, 22M, 22C, 22Bk Exposure means 23Y, 23M, 23C, 23Bk Charging means 25Y, 25M, 25C, 25Bk Cleaning means 30 fixing device 41 paper feed cassette 42 paper feed transport means 44a, 44b, 44c, 44d paper feed roller 46 registration roller N1 fixing nip portion P transfer material

Claims (8)

A transfer belt having a base layer and a surface layer laminated on the base layer,
the dielectric constant of the base material layer is in the range of 20 to 100,
The dielectric constant in the region from the surface of the surface layer to a depth of 15 μm is within the range of 5 to 10, and the Martens hardness of the surface of the surface layer is within the range of 300 to 700 N/mm ² . Characterized transfer belt. 2. The transfer belt according to claim 1, wherein the surface layer contains a cured composition containing alkoxysilane. Furthermore, having an intermediate layer between the base layer and the surface layer,
The intermediate layer contains a resin selected from polyimide resin, polyamideimide resin, polyphenylene sulfide resin and polyetheretherketone resin,
The total layer thickness of the intermediate layer and the surface layer is in the range of 10 to 20 μm, and the layer thickness of the base layer is in the range of 40 to 100 μm. 2. The transfer belt according to 2 above. 4. The transfer belt according to any one of claims 1 to 3, wherein the Martens hardness of the outer surface is in the range of 500 to 600 N/mm ² . 5. The transfer belt according to any one of claims 1 to 4, wherein the dielectric constant of the base material layer is in the range of 40-100. 4. The transfer belt according to claim 3, wherein the dielectric constant of said intermediate layer is in the range of 5-10. 7. The transfer belt according to any one of claims 1 to 6, wherein the dielectric constant of the surface layer is in the range of 2-5. An electrophotographic image forming apparatus comprising the transfer belt according to any one of claims 1 to 7.

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