JP6872107B2 - Endless belt, endless belt unit, and image forming device - Google Patents

Description

The present invention relates to an endless belt, an endless belt unit, and an image forming apparatus.

In an image forming apparatus adopting an electrophotographic method, an endless belt is applied to an intermediate transfer belt, a recording medium transfer transfer belt, and the like.

For example, Patent Document 1 states, "In an endless belt stretched between a driving roller and a driven roller and driven to rotate by a frictional force accompanying the rotation of the driving roller, a direction orthogonal to the rotation direction of the endless belt. Is the width direction, a frictional force acts on the inner peripheral surface of the endless belt that contacts the outer peripheral surface of the drive roller in the direction of pulling the endless belt back to a normal position when the endless belt is displaced in the width direction. An endless belt formed so as to do so is disclosed.

Further, Patent Document 2 contains "a belt-shaped substrate, at least one resin selected from the group consisting of a polyimide resin and a polyamide-imide resin, and rubber particles dispersed in the resin, and is provided on the inner surface of the substrate. An endless belt comprising a friction layer provided on the

Further, in the image forming apparatus adopting the electrophotographic method, a conductive roll is also applied. For example, Patent Document 3 states that "the outer diameter becomes smaller from the central portion in the axial direction toward both ends. Moreover, a conductive roll in which the coefficient of friction of the surface decreases from the central portion in the axial direction toward both ends is disclosed.

Japanese Unexamined Patent Publication No. 2000-255821 Japanese Unexamined Patent Publication No. 2006-084721 Japanese Unexamined Patent Publication No. 2015-135423

The object of the present invention is that, as compared with the case where the contact angles of water on the inner peripheral surface are equal on the entire surface, the generation of cracks generated when the plurality of rolls are hung in a tensioned state and repeatedly rotationally driven is suppressed. The purpose is to provide endless belts.

The above problem is solved by the following invention. That is,
< 1 >
A endless belt which is driven to rotate in multiple roles spanned under tension,
The belt body containing resin A and
It contains resin B and is arranged on the inner peripheral surface side of both ends in the belt axial direction and at a position where it comes into contact with the corner of the outer peripheral surface of the roll when it is rotationally driven, and is arranged on the outer peripheral surface side and the belt shaft. A high contact angle portion where the surface on the center side in the direction is in contact with the belt main body portion and the contact angle of water on the inner peripheral surface is higher than the inner peripheral surface of the belt main body portion.
An endless belt for an image forming apparatus having.

< 2 >
Endless belt according to <1> containing the pre-Symbol resin A and the resin B and the same structural units in the molecular structure.

< 3 >
Before Symbol high contact angle portion, the endless belt according to <1> or <2>, containing a low friction material.

< 4 >
Before SL contact angle of the inner circumferential surface of the water of the belt body portion 50 ° to 70 ° or less, the contact angle of the inner circumferential surface of the water high contact angle portion is 75 ° to 100 ° <1> to < The endless belt according to any one of 3 >.

< 5 >
The endless belt according to any one of < 1 > to < 4 > and
A plurality of rolls in which the endless belt is hung under tension, and
An endless belt unit that is attached to and detached from the image forming apparatus.

< 6 >
Image holder and
A charging means for charging the surface of the image holder and
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image holder, and
A developing means for developing a static charge image formed on the surface of the image holder as a toner image with a developer containing toner, and a developing means.
A transfer means having the endless belt unit according to < 5 > and transferring a toner image formed on the surface of the image holder to the surface of a recording medium via the endless belt.
An image forming apparatus comprising.

According to the invention according to < 1 > or < 3 > , as compared with the case where the contact angles of water on the inner peripheral surface are equal on the entire surface, the plurality of rolls are hung in a tensioned state and repeatedly rotationally driven. An endless belt is provided in which the occurrence of cracks that occur at the time is suppressed.
According to the invention according to < 2 > , as compared with the case where the resin A contained in the belt main body portion and the resin B contained in the high contact angle portion are resins that do not contain the same structural unit in the molecular structure, the belt main body portion Provided is an endless belt in which the occurrence of peeling at the interface between the high contact angle portion and the high contact angle portion is suppressed.
According to the invention according to < 4 > , as compared with the case where the contact angle of water on the inner peripheral surface of the high contact angle portion is less than 75 °, the plurality of rolls are hung in a tensioned state and repeatedly driven by rotation. An endless belt that can easily suppress the occurrence of cracks that occur when the belt is formed is provided.

According to the invention according to < 5 > or < 6 > , an endless belt unit or an image in which the endless belt has a longer life than the case where an endless belt having the same contact angle of water on the inner peripheral surface is applied. A forming device is provided.

It is a schematic perspective view which shows an example of the endless belt which concerns on this embodiment. It is sectional drawing which shows the one end side in the axial direction of the endless belt which concerns on this embodiment in the state of being hung on a roll. It is explanatory drawing for demonstrating an example of the method of manufacturing the endless belt which concerns on this embodiment by a spiral coating method. It is explanatory drawing for demonstrating an example of the method of manufacturing the endless belt which concerns on this embodiment by a spiral coating method. (A) is a schematic plan view showing an example of a circular electrode, and (B) is a schematic cross-sectional view thereof. It is a schematic block diagram which shows an example of the image forming apparatus which concerns on this embodiment. It is a schematic block diagram which shows an example of another image forming apparatus which concerns on this embodiment. It is sectional drawing which shows the one end side in the axial direction of the conventional endless belt in the state of being hung on a roll.

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

(Endless belt)
The endless belt according to the present embodiment is an endless belt for an image forming apparatus that is hung and rotationally driven in a state where tension is applied to a plurality of rolls.
This endless belt has a belt main body portion containing the resin A and a high contact angle portion containing the resin B. The high contact angle portion is a position on the inner peripheral surface side of both ends in the axial direction of the belt and in contact with the corner (hereinafter, also referred to as "roll edge") of the end portion of the outer peripheral surface of the roll when the belt is rotationally driven. The outer peripheral surface side and the surface on the central side in the belt axial direction are in contact with the belt main body. The contact angle of water on the inner peripheral surface of the high contact angle portion is higher than the contact angle of water on the inner peripheral surface of the belt main body portion.

The belt axial direction refers to a direction that becomes the axial direction of the rolls when the endless belt is hung on the plurality of rolls in a state where tension is applied.

By having the above-mentioned configuration, the endless belt according to the present embodiment suppresses the generation of cracks that occur when a plurality of rolls are hung in a tensioned state and repeatedly rotationally driven.
The reason can be inferred as follows.

Conventionally, in an image forming apparatus, an endless belt (intermediate transfer belt, recording medium transfer transfer belt, etc.) has been used as an intermediate transfer body, a recording medium transfer body, or the like. In the image forming apparatus, the endless belt is hung and arranged in a state where tension is applied to a plurality of rolls, and by rotationally driving at least one of the plurality of rolls, the endless belt is driven by the rolls. It is rotationally driven in this way. An endless belt having an axial length longer than that of the roll is used from the viewpoint of suppressing axial deviation with respect to the roll.
Here, a conventional endless belt will be described with reference to an example. FIG. 8 is a cross-sectional view showing one end side in the axial direction of the conventional endless belt hung in a state where tension is applied to the roll. Since the endless belt 301 shown in FIG. 8 has a longer axial length than the roll 109, both ends of the endless belt 301 are hung in a state of protruding outward in the axial direction from the end of the roll 109. Therefore, the inner peripheral surface of the endless belt 301 is in contact with the corner (roll edge) 109E of the roll 109. The endless belt 301 is composed of only the belt main body 303, and the entire belt main body 303 is made of the same material. Therefore, in the endless belt 301, the contact angle of water on the inner peripheral surface is the same in all regions, that is, the portion that contacts the corner (roll edge) 109E of the roll 109 also contacts the other region of the outer peripheral surface of the roll 109. Also has the same contact angle.

However, when the conventional endless belt 301 is hung on the roll 109 with tension applied and is repeatedly rotationally driven (for example, rotationally driven by the number of times equivalent to the formation of 600,000 images in an image forming apparatus). Then, cracks may occur at the position where the roll 109 comes into contact with the corner (roll edge) 109E.
In this method, when at least one roll 109 of the plurality of rolls is rotationally driven to drive the endless belt 301, the rotation speed of the endless belt 301 and the rotation speed of the roll 109 are always driven to be equal to each other. It is thought that this is not easy. That is, the endless belt 301 that rotates driven by the roll 109 that is driven to rotate slips, and friction occurs between the roll 109 and the endless belt 301 during this slip. The load applied to the endless belt 301 due to this friction becomes large especially at the portion of the roll 109 that comes into contact with the corner (roll edge) 109E. Then, it is considered that wear and fine cracks are generated by the load due to friction, and further, the load is repeatedly driven by rotation, which leads to cracks (breakage).

On the other hand, the endless belt according to the present embodiment has a belt main body portion and a high contact angle portion. Here, the endless belt according to the present embodiment will be described with reference to an example. FIG. 1 is a schematic perspective view showing an example of an endless belt according to the present embodiment, and FIG. 2 is a cross-sectional view showing one end side in the axial direction of the endless belt according to the present embodiment in a state of being hung on a roll. Is. As shown in FIG. 2, the endless belt 101 has a belt main body portion 103 and a high contact angle portion 105. The high contact angle portion 105 is arranged on the inner peripheral surface side of both end portions in the belt axial direction and at a position where it comes into contact with the corner (roll edge) 109E of the end portion of the outer peripheral surface of the roll 109 when it is rotationally driven. Moreover, the outer peripheral surface side and the surface on the central side in the belt axial direction are arranged so as to be in contact with the belt main body portion 103. The contact angle of water on the inner peripheral surface 105in of the high contact angle portion 105 is higher than the contact angle of water on the inner peripheral surface 103in of the belt main body 103. That is, in the present embodiment, the frictional force is increased in the inner peripheral surface of the endless belt 101 in the region in contact with the central portion in the belt axial direction, that is, the outer peripheral surface of the roll 109 and responsible for the driven rotation accompanying the rotational drive of the roll 109. On the other hand, the frictional force at the position where the roll 109 comes into contact with the corner (roll edge) 109E is reduced. As a result, even if slippage occurs between the roll 109 and the endless belt 101 and friction occurs, the position where the endless belt 101 comes into contact with the corner (roll edge) 109E of the roll 109, that is, the inner circumference of the high contact angle portion 105. Since the frictional force of the surface 105in is reduced, the load due to friction when slippage occurs is reduced, and the occurrence of cracks (breakage) after repeated rotational driving is suppressed. In addition, the generation of wear debris and the generation of fine cracks before the occurrence of cracks (breaks) are suppressed.
On the other hand, since the inner peripheral surface 103in of the belt main body 103, which has a higher frictional force than the high contact angle 105, is in contact with the roll 109, the responsiveness of the roll 109 to the rotational drive is maintained. As a result, the occurrence of idling in which the endless belt 101 is driven in a state where it is not fully driven by the rotational drive of the roll 109 is suppressed, and the rotational drive performance is ensured.

As a means for increasing the contact angle of water at both ends of the inner peripheral surface of the endless belt, the friction on both ends of the inner peripheral surface is further reduced with respect to the endless belt 301 composed of only the belt body 303 as shown in FIG. A method of applying a material (fluororesin particles or the like) or a method of performing a surface treatment for improving mold releasability can be considered. However, as described above, the present embodiment is intended to suppress the occurrence of cracks, and the cracks are a phenomenon that occurs when a plurality of rolls are hung in a tensioned state and repeatedly driven to rotate. Therefore, it is required to exhibit a high contact angle of water for a long period of time after being repeatedly driven by rotation.
On the other hand, the endless belt according to the present embodiment has a high contact angle portion on the inner peripheral surface side of both ends in the belt axial direction, in which the outer peripheral surface side and the surface on the central side in the belt axial direction are in contact with the belt main body portion. Compared with the method of applying a low friction material to both ends of the inner peripheral surface and the method of performing a surface treatment for improving mold releasability, a high water contact angle can be exhibited for a long period of time. Therefore, it is considered that the occurrence of cracks (breakage) after being repeatedly driven by rotation is suppressed.

As described above, according to the present embodiment, the occurrence of cracks in the endless belt, which occurs when a plurality of rolls are hung in a tensioned state and repeatedly rotationally driven, is suppressed. As a result, the life of the endless belt is extended.

Next, the configuration of the endless belt according to the present embodiment will be described in detail.

In the present embodiment, as shown in FIG. 1, the endless belt 101 is formed in an endless shape. Further, as shown in FIG. 2, the endless belt 101 has a belt main body portion 103 and a high contact angle portion 105. The high contact angle portion 105 is arranged on the inner peripheral surface side of both ends in the belt axial direction and at a position where it comes into contact with the corner (roll edge) 109E of the roll 109 when rotationally driven, and is arranged on the outer peripheral surface side and the belt. The surface on the central side in the axial direction is arranged so as to be in contact with the belt main body 103.
It is more preferable that the high contact angle portion 105 is formed in a region that does not contribute to the formation of an image when the endless belt 101 is mounted on the image forming apparatus.
Further, the endless belt 101 shown in FIG. 2 is composed of only the belt main body portion 103 and the high contact angle portion 105, but the present invention is not limited to this configuration, and another layer is further provided on the outer peripheral surface side of the belt main body portion 103. It may be in a laminated manner. For example, it may be composed of a laminated body in which a release layer is provided on the outer peripheral surface of the belt main body 103.

-Water contact angle-
In the endless belt according to the present embodiment, the contact angle of water on the inner peripheral surface of the high contact angle portion is higher than the contact angle of water on the inner peripheral surface of the belt main body portion.

Specifically, the contact angle of water on the inner peripheral surface of the high contact angle portion is preferably 75 ° or more and 100 ° or less, more preferably 80 ° or more and 100 ° or less, and further preferably 85 °. It is 90 ° or more and 90 ° or less.
When the contact angle of water on the inner peripheral surface of the high contact angle portion is 75 ° or more, the frictional force at the position where the endless belt comes into contact with the corner (roll edge) of the roll is further reduced, and tension is applied to multiple rolls. It becomes easy to suppress the occurrence of cracks that occur when the product is hung in the applied state and repeatedly driven to rotate.
On the other hand, when the contact angle of water on the inner peripheral surface of the high contact angle portion is 100 ° or less, it is easy to ensure the followability with the roll at both ends of the endless belt.

The contact angle of water on the inner peripheral surface of the belt body is preferably 50 ° or more and 70 ° or less, more preferably 55 ° or more and 70 ° or less, and further preferably 60 ° or more and 65 ° or less. ..
Since the contact angle of water on the inner peripheral surface of the belt body is 70 ° or less, the responsiveness to the rotational drive of the roll is easily maintained, and the endless belt does not fully follow the rotational drive of the roll. The occurrence of the phenomenon driven by the belt) is likely to be suppressed.
On the other hand, since the contact angle of water on the inner peripheral surface of the belt main body is 50 ° or more, the coating liquid is applied particularly on the outer peripheral surface of the cylindrical or columnar core body (mold) to form a coating film. Then, in the case of a manufacturing method in which an endless belt is formed by drying and forming a film, it becomes easy to improve the discharge property of gas generated from the coating film at the time of film formation.

The difference between the contact angle of water on the inner peripheral surface of the high contact angle portion and the contact angle of water on the inner peripheral surface of the belt main body portion is tensioned by a plurality of rolls while maintaining the responsiveness to the rotational drive of the rolls. It is preferable that the distance is 15 ° or more, and more preferably 20 ° or more, from the viewpoint of facilitating the occurrence of cracks that occur when the water is hung and repeatedly driven to rotate.
On the other hand, the difference between the water contact angle of the inner peripheral surface of the high contact angle portion and the water contact angle of the inner peripheral surface of the belt main body is preferably within 40 °, and is within 30 °. It is more preferable to have.

-Measuring method The contact angle of water on the inner peripheral surface of the endless belt is measured by the following method.
That is, using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., model number: CA-X-FACE), water droplets and surface when ion-exchanged water droplets are dropped on the surface based on the θ / 2 method at 20 ° C. It is performed by measuring the contact angle with (°).

-Achievement method In the endless belt, a method of realizing a configuration in which the contact angle of water on the inner peripheral surface of the high contact angle portion is higher than the contact angle of water on the inner peripheral surface of the belt main body, and further, the high contact angle portion and the belt main body. The method for controlling the contact angle of water on the inner peripheral surface of each portion within the above-mentioned preferable range is not particularly limited, and examples thereof include the following methods (1) and (2). The following methods (1) and (2) may be used in combination.

(1) "Method of selecting a resin": That is, by selecting a resin material having a higher water contact angle than the resin A contained in the belt main body as the resin B contained in the high contact angle portion, both of them can be used. A method of controlling the contact angle of water on the inner peripheral surface can be mentioned.
In this case, the resin A and the resin B are preferably the main components in the belt main body portion and the high contact angle portion, respectively, and are, for example, the resins contained in the belt main body portion and the high contact angle portion in the contents described later. More preferably.

(2) "Method of adjusting by adding low friction material": That is, low friction material is added to the high contact angle part, and low friction material is not added to the belt body part, or it is lower than the high contact angle part. A method of controlling the contact angle of water on the inner peripheral surface between the two by adding at the addition rate can be mentioned.
The low friction material refers to a material having an action of reducing the frictional force on the surface (that is, increasing the contact angle of water) by adding it.

However, when the endless belt is hung on a plurality of rolls with tension applied and repeatedly driven to rotate, peeling may occur at the interface between the belt main body portion and the high contact angle portion. Therefore, from the viewpoint of suppressing peeling between the belt main body and the high contact angle portion, in order to improve the adhesiveness between the two, the resin A contained in the belt main body and the resin B contained in the high contact angle portion have high affinity. It is preferable to select a resin.
The resin material used for the resin A contained in the belt main body and the resin B contained in the high contact angle portion is preferably selected from the viewpoint of the above affinity, and then the belt main body portion and the high contact angle portion are used. It is more preferable to control the contact angle of water by the above-mentioned (2) "method of adjusting by adding a low-friction material" rather than the method of selecting a resin (that is, the method of (1) above).

Here, a resin having a high affinity will be described.
As the combination of resins having a high affinity, for example, it is preferable that the resin A and the resin B are a combination of resins containing the same structural unit in the molecular structure. Specifically, an embodiment in which a monomer having the same chemical structure is included as a monomer as a raw material for the resin A and a monomer as a raw material for the resin B can be mentioned.

Further, it is preferable that the resin A and the resin B are resins having a molecular structure consisting of only the same structural units (in this case, the structural units constituting the resin A and the resin B may be the same, for example, both. The average molecular weight of each structural unit may be different, and when there are a plurality of structural units, the molar ratio of each structural unit may be different).
For example, an embodiment in which the monomer as the raw material of the resin A and the monomer as the raw material of the resin B consist only of the monomers having the same chemical structure can be mentioned (in this case, only the monomers having the same chemical structure as the resin A and the resin B are polymerized). Any resin may be used, for example, the degree of polymerization of the two may be different, and in the case of a copolymer of a plurality of monomers, the polymerization ratio (molar ratio) of each monomer may be different). ..

Next, the composition of the material constituting the endless belt according to the present embodiment will be described.

-Composition-
The belt main body portion and the high contact angle portion included in the endless belt according to the present embodiment are configured to contain resin A and resin B, respectively. Further, the endless belt may contain a conductive agent from the viewpoint of imparting conductivity, and may contain a low friction material such as fluororesin particles particularly in a high contact angle portion. In addition, it may be composed of a well-known additive.

-Resin material The belt body contains resin A, and the high contact angle portion contains resin B.
It is preferable that the resin A and the resin B are the main components in the belt main body portion and the high contact angle portion, respectively. For example, the content of the resin A in the belt main body is preferably 75% by mass or more and 95% by mass or less, more preferably 77% by mass or more and 80% by mass or less, based on the total mass of the belt main body. On the other hand, the content of the resin B in the high contact angle portion is preferably 64% by mass or more and 76% by mass or less, and more preferably 68% by mass or more and 72% by mass or less, based on the total mass of the high contact angle portion.

Further, from the viewpoint of suppressing peeling between the belt main body portion and the high contact angle portion, the resin A contained in the belt main body portion and the resin B contained in the high contact angle portion are preferably resins having high affinity.
For example, it is preferable that the resin A and the resin B are resins having the same structural unit in the molecular structure, and the monomer used as the raw material of the resin A and the monomer used as the raw material of the resin B contain a monomer having the same chemical structure. preferable.
Further, the resin A and the resin B are resins having a molecular structure consisting of only the same structural units (however, the average molecular weights of the resin A and the resin B may be different, and when there are a plurality of structural units, the resin A and the resin B may have different average molecular weights. The molar ratio of each structural unit may be different). For example, the monomer that is the raw material of the resin A and the monomer that is the raw material of the resin B are only monomers having the same chemical structure (however, the degree of polymerization of the resin A and the resin B may be different, and a plurality of monomers are used. In the case of a copolymer, the molar ratio of each monomer may be different).

Specific examples of the resin material used as the resin A and the resin B include a polyimide resin, a fluoride polyimide resin, a polyamide resin, a polyamideimide resin, a polyether ether ester resin, a polyarylate resin, and a polyester resin.
It is preferable that the resin A and the resin B are the same resin in the above-mentioned specific examples. That is, when the polyimide resin is used as the resin A, it is preferable to use the polyimide resin as the resin B as well.
For the belt main body and the high contact angle portion, one type of resin material may be used alone, or two or more types may be used in combination.

As the resin material, a thermosetting resin is preferable, and a polyimide resin is particularly preferable.
Examples of the polyimide resin include imidized polyamic acids (polyamic acids), which are polymers of tetracarboxylic dianhydride and diamine compounds. Specifically, the polyimide resin is obtained by polymerizing an equimolar amount of a tetracarboxylic acid dianhydride and a diamine compound in a solvent to obtain a polyamic acid solution, and imidizing the polyamic acid. Can be mentioned.

Examples of the polyimide resin include resins having a structural unit represented by the following general formula (I).

(In the general formula (I), R ¹ is a tetravalent organic group, which is an aromatic group, an aliphatic group, a cyclic aliphatic group, a group combining an aromatic group and an aliphatic group, or a group in which they are substituted. The group. R ² is a divalent organic group, which is an aromatic group, an aliphatic group, a cyclic aliphatic group, a group combining an aromatic group and an aliphatic group, or a group in which they are substituted. )

When the resin A and the resin B are polyimide resins, it is preferable that the constituent units represented by the general formula (I) include those having the same structure.

Specifically, as the tetracarboxylic dianhydride, pyromellitic dianhydride, 3,3', 4,4'-benzophenonetetracarboxylic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic Acid dianhydride, 2,3,3',4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid Dihydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,2'-bis (3,4-dicarboxyphenyl) sulfonic acid dianhydride, perylene-3,4,9,10 Examples thereof include −tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, and ethylenetetracarboxylic dianhydride.

On the other hand, specific examples of the diamine compound include 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,3'-dichlorobenzidine, and 4,4'-diaminodiphenylsulfide. , 3,3'-diaminodiphenylsulphon, 1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3,3'-dimethyl 4,4'-biphenyldiamine, benzidine, 3,3'-dimethylbenzidine , 3,3'-dimethoxybenzidine, 4,4'-diaminodiphenylsulphon, 4,4'-diaminodiphenylpropane, 2,4-bis (β-aminotri-butyl) toluene, bis (p-β-amino-) Tertiary butylphenyl) ether, bis (p-β-methyl-δ-aminophenyl) benzene, bis-p- (1,1-dimethyl-5-amino-pentyl) benzene, 1-isopropyl-2,4-m -Phenylenediamine, m-xylylene diamine, p-xylylene diamine, di (p-aminocyclohexyl) methane, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, diaminopropyltetramethylene, 3-Methylheptamethylenediamine, 4,4-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2-bis-3-aminoprovoxyetan, 2,2-dimethylpropylenediamine, 3-methoxyhexamethylenediamine , 2,5-Dimethylheptamethylenediamine, 3-Methylheptamethylenediamine, 5-Methylnonamethylenediamine, 2,17-diaminoeicosadecan, 1,4-diaminocyclohexane, 1,10-diamino-1,10- dimethyl decane, 12-diamino-octadecane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, _{piperazine, H 2 N (CH 2)} 3 O (CH 2) 2 O (CH 2) NH 2, Examples thereof include _{H 2} N (CH ₂ ) ₃ S (CH ₂ ) ₃ NH ₂ , H ₂ N (CH ₂ ) ₃ N (CH ₃ ) ₂ (CH ₂ ) ₃ NH _2.

As the solvent for polymerizing the tetracarboxylic dianhydride and the diamine, a polar solvent (organic polar solvent) is preferably used from the viewpoint of solubility and the like. As the polar solvent, N, N-dialkylamides are preferable, and specifically, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, N having a low molecular weight thereof are preferable. , N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethyl sulfoxide, hexamethylphosphortriamide, N-methyl-2-pyrrolidone, pyridine, tetramethylenesulfone, dimethyltetramethylenesulfone and the like. These may be singular or used in combination.

-Low friction material The high contact angle portion of the endless belt may include a low friction material. The low friction material refers to a material having an action of reducing the frictional force on the surface (that is, increasing the contact angle of water) by adding it.

From the viewpoint that the contact angle of water on the inner peripheral surface between the belt body and the high contact angle is the above-mentioned relationship, a low friction material is added to the high contact angle and a low friction material is added to the belt body. It is preferable not to add it.

Examples of the low friction material include fluororesin particles, silicone resin particles, silica, zinc stearate and the like.
Among these, fluororesin particles are preferably used.
The low friction material may be used alone or in combination of two or more.

Examples of the fluororesin particles include ethylene tetrafluoride resin, ethylene trifluoride resin, propylene hexafluoride resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride dichloride resin, and copolymers thereof. Fluorine can be mentioned.
Among these, the fluororesin particles include polytetrafluoroethylene (tetrafluoroethylene resin “PTFE”), tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer (“FEP”), and tetra. A copolymer of fluoroethylene and perfluoroalkyl vinyl ether (“PFA”) is preferable, and polytetrafluoroethylene (tetrafluoroethylene resin “PTFE”) is particularly preferable.

The fluororesin particles are primary particles, secondary particles having a secondary particle size of 2 μm or less (preferably 1 μm or less, more preferably 0.5 μm or less) (aggregated state in which two or more primary particles are aggregated), or these. It is preferable that the particles are contained in a mixed state.
It is preferable that the fluororesin particles are dispersed and contained in the primary particles, the secondary particles, or a mixed state thereof, and the secondary particle diameter in the state of at least the agglomerated particles is in the above range. That is, it is preferable that the fluororesin particles are dispersed in a state where the aggregation of the fluororesin particles is suppressed.
The primary particle size of the fluororesin particles (particle size of the particles in a non-aggregated state) is preferably 0.1 μm or more and 0.3 μm or less.

The primary particle size and the secondary particle size of the fluorine resin particles are observed by an SEM (scanning electron microscope) (for example, a magnification of 5000 times or more), and the maximum diameter of each of the primary particles or the fluorine resin particles in the state of aggregated particles is determined. Measure and use this as the average value performed for 50 particles. A JSM-6700F manufactured by JEOL Ltd. is used as the SEM, and a secondary electronic image having an acceleration voltage of 5 kV is observed.

When fluororesin particles are used as the low friction material, the content of the fluororesin particles at the high contact angle portion is preferably 0.1% by mass or more and 20% by mass or less with respect to the total mass of the high contact angle portion, for example. It is preferably 8% by mass or more and 12% by mass or less.
The fluororesin particles may be used alone or in combination of two or more.

Further, from the viewpoint of satisfactorily dispersing the fluororesin particles, for example, a fluorograft polymer may be used in combination as a dispersant.
Examples of the fluorine-based graft polymer include a copolymer of a macromonomer having a polymerizable functional group at one end of the molecular chain and a polymerizable fluorine-based monomer having an alkyl fluoride group.
Specifically, as a fluorograft polymer, for example, as a macromer, a polymer such as an acrylic acid ester, a methacrylic acid ester, or a styrene compound or a copolymer thereof, and as a fluoromonomer, perfluoroalkylethyl methacrylate or perfluoro Examples thereof include a graft copolymer with alkyl methacrylate and the like.

The polymerization ratio of the macromonomer and the polymerizable fluorine-based monomer is, for example, 10% by mass or more and 50% by mass or less (preferably 10% by mass or more and 40% by mass or less, more preferably 10) as the fluorine content in the fluorine-based graft polymer. The polymerization ratio is preferably 3% by mass or more and 30% by mass or less).
The molecular weight of the fluorine-based graft polymer is, for example, preferably 5000 or more and 20000 or less in terms of number average molecular weight, preferably 5000 or more and 17500 or less, and more preferably 5000 or more and 12000 or less.
The amount of the fluorine-based graft polymer is, for example, preferably 0.1% by mass or more and 10% by mass or less with respect to the fluororesin particles.

-Conducting agent The endless belt may contain a conductive agent from the viewpoint of imparting conductivity in both the belt main body portion and the high contact angle portion.
The conductive agent, conductive (e.g. a volume resistivity of less than 10 ⁷ Ω · cm, the following is the same) or semi-conductive (e.g., a volume resistivity of 10 ⁷ Ω · cm or more ^{10 13 Ω} · cm or less, and so on ) Powder (preferably a powder composed of particles having a primary particle size of less than 10 μm, preferably a powder composed of particles having a primary particle size of 1 μm or less).
The conductive agent is not particularly limited, but is, for example, carbon black (for example, Ketjen black, acetylene black, carbon black whose surface has been oxidized), metal (for example, aluminum or nickel), metal oxide (for example, oxidation). Ittrium, tin oxide, etc.), ionic conductive substances (for example, potassium titanate, LiCl, etc.) and the like can be mentioned.

The conductive agent is selected according to the purpose of use, but carbon black is preferable, and pH 5 or less (preferably pH 4) is particularly good from the viewpoint of stability of electric resistance over time and electric field dependence that suppresses electric field concentration due to transfer voltage. An oxidation-treated carbon black having a pH of 5.5 or less, more preferably 4.0 or less (for example, carbon black obtained by imparting a carboxyl group, a quinone group, a lactone group, a hydroxyl group or the like to the surface) is preferable.

The average primary particle size of carbon black is, for example, preferably 10 nm or more and 50 nm or less, and more preferably 15 nm or more and 30 nm or less.
The average primary particle size of carbon black is measured by the following method.
First, a measurement sample having a thickness of 100 nm is taken from the endless belt to be measured by cutting with a microtome, and this measurement sample is observed by a TEM (transmission electron microscope). Then, the diameter of a circle equal to the projected area of each of the 50 carbon black particles is defined as the particle diameter, and the average value thereof is defined as the average primary particle diameter.

The content of the conductive agent is selected according to the target resistance. For example, in both the belt body portion and the high contact angle portion, it is preferably 1% by mass or more and 50% by mass or less with respect to the total mass, and further. It is more preferably 2% by mass or more and 40% by mass or less, and further preferably 4% by mass or more and 30% by mass or less.
The conductive agent may be used alone or in combination of two or more.

Other additives other than the conductive agent include, for example, a dispersant for improving the dispersibility of carbon black, various fillers for imparting various functions such as mechanical strength, and a catalyst for promoting the imidization reaction. Examples include leveling agents for improving film forming quality.

(Manufacturing method of endless belt)
Here, a method of manufacturing the endless belt according to the present embodiment will be described. As an example, a method of manufacturing the endless belt 101 including the belt main body portion 103 and the high contact angle portion 105 shown in FIG. 2 will be described.

The method for forming the belt main body portion 103 and the high contact angle portion 105 in the endless belt 101 is not particularly limited, and can be formed by adopting a conventionally known method.

For example, a manufacturing method having the following steps can be mentioned.
(Coating liquid preparation step) A step of preparing a coating liquid for a high contact corner portion for forming a high contact corner portion 105 and a coating liquid for a belt main body portion for forming a belt main body portion 103. Contact angle portion coating process) For applying the coating liquid for high contact corners to the defined regions of both ends in the axial direction on the surface of the cylindrical or columnar core to form the high contact corners 105. Step of forming high contact corner coating film ・ (Belt main body coating process) Apply the coating liquid for belt main body on the core body so as to cover the outer peripheral surface of the high contact corner coating film, and apply the coating liquid for the belt main body. Step of forming the belt main body coating film for forming 103- (Drying step) Step of drying to remove the solvent in the high contact angle coating film and the belt main body coating film- (Demolding step) Drying The process of removing the integrally molded endless belt (high contact angle part and belt body part) from the core body

A separate high contact corner coating film drying step may be provided between the high contact corner coating step and the belt body coating step. That is, in the belt body coating step, the high contact angle coating film formed in the high contact angle coating step is once dried to remove a predetermined amount of solvent from the high contact angle coating film, and then high. The coating liquid for the belt body may be applied so as to cover the outer peripheral surface of the contact angle coating film. By providing the high contact angle portion coating film drying step, the formation accuracy (the degree of formation in the region to be formed) of the high contact angle portion and the belt main body portion can be improved.
On the other hand, from the viewpoint of improving the adhesiveness between the belt body and the high contact angle portion and suppressing the peeling of both, the high contact angle portion coating film formed in the high contact angle portion coating step has not been dried. It is preferable to apply the coating liquid for the belt body to the undried high contact angle coating film in the state so as to cover the outer peripheral surface. That is, from the viewpoint of obtaining the adhesiveness, it is preferable not to provide the high contact angle coating film drying step between the high contact angle coating step and the belt body coating step.

When a polyimide resin or the like is used as the resin material, a firing step (imidization step) may be provided after the drying step.

Here, a method of applying the coating liquid for the high contact angle portion to the defined regions of both ends in the axial direction of the core body surface in the high contact angle portion coating process, and a method of applying the coating liquid for the high contact angle portion in the belt body portion coating step of the high contact angle portion coating film. A method of applying the coating liquid for the belt body portion on the core body so as to cover the outer peripheral surface will be described.
Any coating method is not particularly limited and can be carried out by adopting a conventionally known method. For example, the spiral coating apparatus shown in FIGS. 3 and 4 is used to apply the coating liquid for the high contact angle portion, and then the coating liquid for the belt body portion is applied so as to cover the outer peripheral surface of the high contact angle portion coating film. A method of applying can be mentioned.

First, the coating liquid for high contact corners is applied to the defined regions of both ends of the surface of the cylindrical or columnar core 30 in the axial direction using a spiral coating device to form the high contact corners 105. A high contact angle coating film 105b is formed. Specifically, the core body 30 is made horizontal in the axial direction, and the coating liquid for the high contact angle portion is flowed down from the nozzle 52A of the flow-down device 52 while being rotated around the axis (direction of arrow B) by the rotating device 40. It is attached to both ends in the axial direction on the surface of the core body 30. The coating liquid for the high contact angle portion is supplied from the tank 54 to the flow-down device 52 through the supply pipe 58 by the pump 56. The coating liquid for high contact corners adhering to both ends of the core 30 in the axial direction is smoothed by a blade (spatula) 62 as an example of a smoothing mechanism.

The flow-down device 52 and the blade 62 are supported so as to be movable in the axial direction (arrow C direction) of the core body 30, and the flow-down device 52 and the blade 62 are in a state where the core body 30 is rotated at a preset rotation speed. By discharging the coating liquid for the high contact angle portion while the blade 62 and the blade 62 move in the axial direction of the core body 30 (direction of arrow C), the surface of the core body 30 is spirally formed in the defined regions at both ends in the axial direction. The coating liquid for the high contact corner portion is applied to the surface, and the high contact corner coating film 105b is formed.

Next, a spiral coating device is used on the outer peripheral surface of the high contact angle coating film 105b and on the region between the high contact angle coating films 105b at both ends (the region where the surface of the core 30 is exposed). The coating liquid 51 for the belt main body is applied to form the belt main body coating film 103b for forming the belt main body 103. Specifically, the core body 30 having the high contact angle coating film 105b formed on both ends is used for the belt main body while being rotated in the axial direction (arrow B direction) by the rotating device 40 with its axial direction horizontal. The coating liquid 51 flows down from the nozzle 52A of the flow device 52 and is applied so as to cover the outer peripheral surface of the high contact angle coating film 105b at both ends and the exposed region of the core body 30 surface between them. The coated coating liquid 51 for the belt body is smoothed by a blade (spatula) 62 as an example of the smoothing mechanism, and the belt body coating film 103b is formed.

After that, the high contact angle coating film 105b and the belt body coating film 103b formed on the core 30 are subjected to a drying step, a firing step (if necessary), and a mold removal step to obtain the present embodiment. The endless belt 101 is obtained. The endless belt 101 may be further drilled, ribbed, or the like.
Further, in the case of an endless belt having another layer such as a release layer on the outer peripheral surface side of the belt main body 103, the endless belt is formed by further forming another layer such as a release layer by a known method. Is obtained.

-Characteristics of endless belt-
The surface resistivity of the outer peripheral surface of the endless belt according to the present embodiment is, for example, a common logarithmic value of 9 from the viewpoint of transferability when used as an intermediate transfer belt, a recording medium transfer transfer belt, or the like in an image forming apparatus. It is preferably (LogΩ / □) or more and 13 (LogΩ / □) or less, and more preferably 10 (LogΩ / □) or more and 12 (LogΩ / □) or less.
The common logarithmic value of the surface resistivity is controlled by the type of the conductive agent and the amount of the conductive agent added.

Here, the method for measuring the surface resistivity is as follows. Measurement is performed according to JIS-K6911 using a circular electrode (for example, "UR probe" of Hi-Lester IP manufactured by Mitsubishi Yuka Co., Ltd.). The method of measuring the surface resistivity will be described with reference to the drawings. FIG. 5 is a schematic plan view (A) and a schematic cross-sectional view (B) showing an example of a circular electrode. The circular electrode shown in FIG. 5 includes a first voltage application electrode A and a plate-shaped insulator B. The first voltage application electrode A is a cylindrical ring-shaped electrode having a columnar electrode portion C and an inner diameter larger than the outer diameter of the columnar electrode portion C and surrounding the columnar electrode portion C at regular intervals. It includes a part D. A belt T is sandwiched between the columnar electrode portion C and the ring-shaped electrode portion D of the first voltage application electrode A and the plate-shaped insulator B, and the columnar electrode portion C and the ring-shaped electrode of the first voltage application electrode A are sandwiched between them. The current I (A) that flows when the voltage V (V) is applied to the part D is measured, and the surface resistance ρs (Ω / □) of the transfer surface of the belt T is calculated by the following formula. Here, in the following formula, d (mm) indicates the outer diameter of the columnar electrode portion C, and D (mm) indicates the inner diameter of the ring-shaped electrode portion D.
Formula: ρs = π × (D + d) / (D−d) × (V / I)
For the surface resistance, a circular electrode (UR probe of Hi-Lester IP manufactured by Mitsubishi Yuka Co., Ltd .: outer diameter Φ16 mm of columnar electrode portion C, inner diameter Φ30 mm, outer diameter Φ40 mm of ring-shaped electrode portion D) was used. The current value after applying a voltage of 500 V for 10 seconds under a 22 ° C./55% RH environment is obtained and calculated.

The total volume resistivity of the endless belt 101 according to the present embodiment (particularly, the total volume in the thickness direction of the region that does not have the high contact angle portion 105, that is, the region whose thickness direction is composed of only the belt main body portion 103). The resistivity) is, for example, 8 (LogΩcm) or more and 13 (LogΩcm) or less in terms of common logarithmic value when used as an intermediate transfer belt, a recording medium transfer transfer belt, or the like in an image forming apparatus. Is preferable. The common logarithmic value of volume resistivity is controlled by the type of conductive agent and the amount of conductive agent added.

Here, the volume resistivity is measured according to JIS-K6911 using a circular electrode (for example, a UR probe of Hi-Lester IP manufactured by Mitsubishi Yuka Co., Ltd.). The method for measuring the volume resistivity will be described with reference to FIG. The measurement is performed with the same device as the surface resistivity. However, in the circular electrode shown in FIG. 5, a second voltage application electrode B'is provided instead of the plate-shaped insulator B at the time of measuring the surface resistivity. Then, the belt T is sandwiched between the columnar electrode portion C and the ring-shaped electrode portion D of the first voltage application electrode A and the second voltage application electrode B', and the columnar electrode portion C of the first voltage application electrode A is sandwiched between them. The current I (A) flowing when the voltage V (V) is applied between the second voltage application electrode B and the second voltage application electrode B is measured, and the volume resistance ρv (Ωcm) of the belt T is calculated by the following formula. Here, in the following formula, t indicates the thickness of the belt T.
Equation ρv = 19.6 × (V / I) × t
For the volume resistance, a circular electrode (UR probe of Hi-Lester IP manufactured by Mitsubishi Yuka Co., Ltd .: outer diameter Φ16 mm of columnar electrode portion C, inner diameter Φ30 mm, outer diameter Φ40 mm of ring-shaped electrode portion D) was used. The current value after applying a voltage of 500 V for 10 seconds under a 22 ° C./55% RH environment is obtained and calculated.

The numerical value of 19.6 shown in the above equation is an electrode coefficient for converting into resistivity, and is πd ^{2 from the outer diameter d (mm) of the columnar electrode portion and the sample thickness t (cm).} Calculated as / 4t. The thickness of the belt T is measured using an eddy current film thickness meter CTR-1500E manufactured by Sanko Electronics Co., Ltd.

-Dimensions-
The thickness of the endless belt 101 according to the present embodiment (in the case of the endless belt 101 shown in FIG. 2, the thickness of the belt main body 103 in the portion having no high contact angle portion 105 and the thickness in the portion having the high contact angle portion 105). The total thickness of the high contact angle portion 105 and the belt body portion 103) is, for example, preferably 0.05 mm or more and 0.50 mm or less, more preferably 0.06 mm or more and 0.30 mm or less, and further. It is preferably 0.06 mm or more and 0.15 mm or less.
Further, in the portion having the high contact angle portion 105, the ratio of the thickness of the high contact angle portion 105 to the thickness of the endless belt 101 (total thickness of the high contact angle portion 105 and the belt main body portion 103) is 20% or more. It is preferably 70% or less, more preferably 40% or more and 50% or less. The specific thickness range of the high contact angle portion 105 is 20 μm or more and 60 μm or less, and more preferably 30 μm or more and 40 μm or less.
Further, the width (length in the belt axial direction) of the high contact angle portion 105 is preferably 5 mm or more and 40 mm or less, and more preferably 15 mm or more and 25 mm or less. It is more preferable that the high contact angle portion 105 is arranged in a region that does not contribute to the formation of an image when the endless belt 101 is mounted on the image forming apparatus.

-Use-
The endless belt 101 according to the present embodiment is a belt member in an image forming apparatus, for example, an intermediate transfer belt in which a toner image on an image holder is transferred (primary transfer) and then transferred again on a recording medium (secondary transfer). When the toner image held on the intermediate transfer body is secondarily transferred to a recording medium, the recording medium is conveyed in contact with the back surface (non-transfer surface) of the recording medium and a voltage is applied for the secondary transfer. It is used as a transfer belt, a recording medium transfer transfer belt that conveys a recording medium and applies a voltage for transfer in a mode in which a toner image on an image holder is directly transferred to the surface of the recording medium.

(Image forming device)
The image forming apparatus according to the present embodiment includes an image holder, a charging means for charging the surface of the image holder, and a static charge image forming means for forming a static charge image on the surface of the charged image holder. It has a developing means for developing a static charge image formed on the surface of the image holder as a toner image by a developer containing toner, and the above-mentioned endless belt according to the present embodiment, and is provided on the surface of the image holder. A transfer means for transferring the formed toner image to the surface of a recording medium via the endless belt is provided.

Specifically, in the image forming apparatus according to the present embodiment, for example, the transfer means is a primary transfer means for primary transferring the toner image formed on the intermediate transfer body and the image holder to the intermediate transfer body, and the intermediate transfer body. Examples thereof include a configuration including a secondary transfer means for secondary transfer of the transferred toner image to a recording medium, and an endless belt according to the present embodiment as the intermediate transfer body.

Further, in the image forming apparatus according to the present embodiment, for example, the transfer means records a recording medium transport transfer body (recording medium transport transfer belt) for transporting the recording medium and a toner image formed on the image holder as the recording medium. Examples thereof include a configuration in which a transfer means for transferring to a recording medium conveyed by a transfer transfer body is provided, and the recording medium transfer transfer body is provided with an endless belt according to the present embodiment.

Examples of the image forming apparatus according to the present embodiment include a normal monocolor image forming apparatus in which only monochromatic toner is stored in the developing apparatus, and the toner image held on the image holder is sequentially primary-transferred to the intermediate transfer body. Examples thereof include a color image forming apparatus that repeats the above steps, and a tandem type color image forming apparatus in which a plurality of image holders equipped with a developer for each color are arranged in series on an intermediate transfer body.

Hereinafter, the image forming apparatus according to the present embodiment will be described with reference to the drawings. FIG. 6 is a schematic configuration diagram showing an example of the image forming apparatus according to the present embodiment. FIG. 7 is a schematic configuration diagram showing another image forming apparatus according to the present embodiment. FIG. 6 is an image forming apparatus including an intermediate transfer body (intermediate transfer belt), and FIG. 7 is an image forming apparatus including a recording medium transfer transfer body (recording medium transfer transfer belt).

The image forming apparatus shown in FIG. 6 is an electrophotographic first to output images of each color of yellow (Y), magenta (M), cyan (C), and black (K) based on color-separated image data. A fourth image forming unit 10Y, 10M, 10C, 10K (image forming means) is provided. These image forming units (hereinafter, simply referred to as “units”) 10Y, 10M, 10C, and 10K are arranged side by side at a specific distance from each other in the horizontal direction. The units 10Y, 10M, 10C, and 10K may be process cartridges that are attached to and detached from the image forming apparatus main body.

An intermediate transfer belt 20 as an intermediate transfer body is extended through each unit above the drawings of each unit 10Y, 10M, 10C, and 10K. The intermediate transfer belt 20 is provided by being wound around a drive roll 22 arranged apart from each other from the left to the right in the figure and a support roll 24 in contact with the inner surface of the intermediate transfer belt 20, and the first unit 10Y to the fourth unit. The transfer unit for the image forming apparatus is configured so as to travel in the direction toward 10K.
The support roll 24 is urged in a direction away from the drive roll 22 by a spring or the like (not shown), and a specific tension is applied to the intermediate transfer belt 20 wound around the support roll 24. Further, an intermediate transfer body cleaning device 30 is provided on the side surface of the image holder of the intermediate transfer belt 20 so as to face the drive roll 22.
Further, each of the developing devices (development means) 4Y, 4M, 4C, and 4K of each unit 10Y, 10M, 10C, and 10K has yellow, magenta, cyan, and black contained in the toner cartridges 8Y, 8M, 8C, and 8K, respectively. 4 color toners are supplied.

Since the first to fourth units 10Y, 10M, 10C, and 10K described above have the same configuration, here, the first unit forming a yellow image arranged on the upstream side in the traveling direction of the intermediate transfer belt. 10Y will be described as a representative. The second to fourth units are provided with reference numerals with magenta (M), cyan (C), and black (K) instead of yellow (Y) in the portion equivalent to the first unit 10Y. The description of 10M, 10C, and 10K will be omitted.

The first unit 10Y has a photoconductor 1Y that acts as an image holder. Around the photoconductor 1Y, a charge roll 2Y that charges the surface of the photoconductor 1Y to a specific potential, and a laser beam 3Y based on a color-separated image signal expose the charged surface to form a static charge image. Exposure device 3, developing device (development means) 4Y that supplies charged toner to the electrostatic charge image to develop the electrostatic charge image, and primary transfer roll 5Y (primary) that transfers the developed toner image onto the intermediate transfer belt 20. The transfer means) and the photoconductor cleaning device (cleaning means) 6Y for removing the toner remaining on the surface of the photoconductor 1Y after the primary transfer with a cleaning blade are arranged in this order.
The primary transfer roll 5Y is arranged inside the intermediate transfer belt 20 and is provided at a position facing the photoconductor 1Y. Further, a bias power supply (not shown) for applying a primary transfer bias is connected to each of the primary transfer rolls 5Y, 5M, 5C, and 5K. Each bias power supply changes the transfer bias applied to each primary transfer roll by control by a control unit (not shown).

Hereinafter, the operation of forming a yellow image in the first unit 10Y will be described. First, prior to the operation, the surface of the photoconductor 1Y is charged with a potential of about −600 V or more and −800 V or less by the charging roll 2Y.
The photoconductor 1Y is formed by laminating a photosensitive layer on a conductive substrate (volume resistivity at 20 ° C.: 1 × 10 ^{6 Ωcm or less).} This photosensitive layer usually has a high resistivity (resistance of a general resin), but has a property that when the laser beam 3Y is irradiated, the specific resistance of the portion irradiated with the laser beam changes. Therefore, the laser beam 3Y is output to the surface of the charged photoconductor 1Y via the exposure apparatus 3 according to the image data for yellow sent from the control unit (not shown). The laser beam 3Y irradiates the photosensitive layer on the surface of the photoconductor 1Y, whereby an electrostatic charge image of the yellow print pattern is formed on the surface of the photoconductor 1Y.

The static charge image is an image formed on the surface of the photoconductor 1Y by charging. The laser beam 3Y reduces the specific resistance of the irradiated portion of the photosensitizer layer, and the charged charge on the surface of the photoconductor 1Y flows. On the other hand, it is a so-called negative latent image formed by the residual charge of the portion not irradiated with the laser beam 3Y.
The electrostatic charge image formed on the photoconductor 1Y in this way is rotated to a specific developing position as the photoconductor 1Y travels. Then, at this developing position, the electrostatic charge image on the photoconductor 1Y is made into a visible image (developed image) by the developing device 4Y.

For example, yellow toner is housed in the developing apparatus 4Y. The yellow toner is triboelectrically charged by being agitated inside the developing apparatus 4Y, and has a charge having the same polarity (negative electrode property) as the charged charge on the photoconductor 1Y, and is a developer roll (developer holder). It is held on. Then, as the surface of the photoconductor 1Y passes through the developing device 4Y, the yellow toner is electrostatically adhered to the statically eliminated latent image portion on the surface of the photoconductor 1Y, and the latent image is developed by the yellow toner. .. The photoconductor 1Y on which the yellow toner image is formed is continuously traveled at a specific speed, and the toner image developed on the photoconductor 1Y is conveyed to a specific primary transfer position.

When the yellow toner image on the photoconductor 1Y is transferred to the primary transfer, a specific primary transfer bias is applied to the primary transfer roll 5Y, and the electrostatic force from the photoconductor 1Y toward the primary transfer roll 5Y is the toner image. The toner image on the photoconductor 1Y is transferred onto the intermediate transfer belt 20. The transfer bias applied at this time has a polarity (+) opposite to the polarity (−) of the toner, and is controlled to about +10 μA by the control unit (not shown) in the first unit 10Y, for example.
On the other hand, the toner remaining on the photoconductor 1Y is removed by the cleaning device 6Y and recovered.

Further, the primary transfer bias applied to the primary transfer rolls 5M, 5C, and 5K after the second unit 10M is also controlled according to the first unit.
In this way, the intermediate transfer belt 20 to which the yellow toner image is transferred in the first unit 10Y is sequentially conveyed through the second to fourth units 10M, 10C, and 10K, and the toner images of each color are superimposed and multiplex transferred.

The intermediate transfer belt 20 on which the toner images of four colors are multiplex-transferred through the first to fourth units is arranged on the image holding surface side of the support roll 24 and the intermediate transfer belt 20 in contact with the intermediate transfer belt 20 and the inner surface of the intermediate transfer belt 20. It leads to a secondary transfer unit composed of the secondary transfer roll (secondary transfer means) 26. On the other hand, the recording medium P is fed to the gap where the secondary transfer roll 26 and the intermediate transfer belt 20 are in pressure contact with each other via the supply mechanism at a specific timing, and a specific secondary transfer bias is applied to the support roll 24. To. The transfer bias applied at this time is (-) polarity, which is the same polarity as the polarity (-) of the toner, and the electrostatic force from the intermediate transfer belt 20 toward the recording medium P is applied to the toner image, and the transfer bias is applied on the intermediate transfer belt 20. The toner image of is transferred onto the recording medium P. The secondary transfer bias at this time is determined according to the resistance detected by the resistance detecting means (not shown) that detects the resistance of the secondary transfer unit, and is voltage controlled.

After that, the recording medium P is sent to the fixing device (fixing means) 28 to heat the toner image, and the color-overlapped toner image is melted and fixed on the recording medium P. The recording medium P for which the color image has been fixed is carried out toward the discharge unit, and a series of color image forming operations is completed.
The image forming apparatus exemplified above has a configuration in which the toner image is transferred to the recording medium P via the intermediate transfer belt 20, but the present invention is not limited to this configuration, and the toner image can be directly generated from the photoconductor. The structure may be transferred to the recording medium P.

On the other hand, in the image forming apparatus shown in FIG. 7, the photoforming units Y, M, C, and BK rotate in the clockwise direction of the arrow at a specific peripheral speed (process speed), respectively, so that the photoconductors 201Y, 201M, and 201C are rotated. , 201BK is provided. Around the photoconductors 201Y, 201M, 201C, 201BK, charging devices 202Y, 202M, 202C, 202BK, exposure devices 203Y, 203M, 203C, 203BK, and each color developing device (yellow developing device 204Y, magenta developing device 204M, The cyan developing device 204C and the black developing device 204BK) and the photoconductor cleaning members 205Y, 205M, 205C, and 205BK are arranged, respectively.

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

The recording medium transfer transfer belt 206 is supported from the inner surface side by the belt support rolls 210, 211, 212, 213, and forms a transfer unit for an image forming apparatus. The recording medium transfer transfer belt 206 rotates in the counterclockwise direction of the arrow at the same peripheral speed as the photoconductors 201Y, 201M, 201C, and 201BK, and is located between the belt support rolls 212 and 213. The portions are arranged so as to be in contact with the photoconductors 201Y, 201M, 201C, and 201BK, respectively. The recording medium transfer transfer belt 206 is provided with a belt cleaning member 214.

The transfer rolls 207Y, 207M, 207C, and 207BK are located inside the recording medium transfer transfer belt 206 and at positions facing the portions where the recording medium transfer transfer belt 206 and the photoconductors 201Y, 201M, 201C, and 201BK are in contact with each other. Each of them is arranged to form a transfer region for transferring a toner image to the recording medium 216 via the photoconductors 201Y, 201M, 201C, and 201BK and the recording medium transfer transfer belt 206. The transfer rolls 207Y, 207M, 207C, and 207BK may be arranged directly under the photoconductors 201Y, 201M, 201C, and 201BK, or may be arranged at a position deviated from the directly below.

The fixing device 209 is arranged so as to transfer after passing through the respective transfer regions of the recording medium transfer transfer belt 206 and the photoconductors 201Y, 201M, 201C, and 201BK.

The recording medium 216 is conveyed to the recording medium transfer transfer belt 206 by the recording medium transfer roll 208.

In the image forming unit BK, the photoconductor 201BK is rotationally driven. In conjunction with this, the charging device 202BK is driven to charge the surface of the photoconductor 201BK to a specific polarity and potential. The photoconductor 201BK whose surface is charged is then exposed to an image by the exposure device 203BK, and an electrostatic latent image is formed on the surface thereof.

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

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

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

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

The recording medium 216 on which the toner image is transferred by the transfer rolls 207BK, 207C, 207M and 207Y is further conveyed to the fixing device 209 for fixing.
As described above, an image is formed on the recording medium.

Hereinafter, the present invention will be described with reference to Examples, but the present invention is not limited to these Examples. In the following, "part" and "%" are based on mass unless otherwise specified.

[Example 1]
-Preparation of coating liquid Polygonide precursor solution (trade name: U varnish, manufactured by Unitica, solid content concentration 18%, solvent is N-methylpyrrolidone) and carbon black (trade name: Special Black4, manufactured by Orion Engineered Carbons) Was mixed and dispersed using a jet mill to obtain a coating liquid A having a carbon black content of 28 parts with respect to 100 parts of the solid content of the coating liquid.
Further, a coating liquid B was obtained in which polytetrafluoroethylene (PTFE) particles (trade name: Lubron L2, manufactured by Daikin Industries, Ltd.) were mixed with the coating liquid A so as to have a concentration of 10%.
The coating liquid A is used as a coating liquid for forming a belt main body, and the coating liquid B is used as a coating liquid for forming a high contact angle portion.

-Manufacture of endless belt Coating liquid B (coating liquid for forming high contact corners) is applied to both ends of the outer peripheral surface of the cylindrical mold using the spiral coating device shown in FIGS. 3 and 4, and 10 at 170 ° C. It was dried for a minute to form a high contact corner coating film. After that, the coating liquid A (coating liquid for forming the belt main body) is applied to the entire surface of the mold so as to cover the outer peripheral surface of the high contact corner coating film, and dried at 170 ° C. for 20 minutes to form the belt main body coating film. Formed. Then, it was fired at 300 ° C. for 100 minutes and removed from the mold to obtain an endless belt.
The dimensions of each part of the obtained endless belt are as follows.
-Endless belt thickness (average thickness): 80 μm
・ Thickness of high contact angle (average thickness): 40 μm
・ Width of one side of high contact angle: 20 mm
-Distance between the high contact corners at both ends (the length of the central part where the high contact corners do not exist): 310 mm

[Example 2]
In Example 1, after the coating liquid B (coating liquid for forming a high contact angle portion) was applied, it was not dried at 170 ° C. for 10 minutes, but was applied to the undried high contact corner coating film. An endless belt was obtained in the same manner as in Example 1 except that the liquid A (coating liquid for forming the belt main body) was applied.

[Comparative Example 1]
The coating liquid A prepared in Example 1 was applied to the outer peripheral surface of the cylindrical mold, dried at 170 ° C. for 20 minutes, and then fired at 300 ° C. for 100 minutes to remove the mold from the mold. In this way, an endless belt having no high contact angle portion was obtained.

[Comparative Example 2]
PTFE particles (trade name: Lubron L2, manufactured by Daikin Industries, Ltd.) are applied to a region having a width of 20 mm on the inner peripheral surfaces of both ends of the endless belt obtained in Comparative Example 1 with Bencot, and the excess is wiped off to obtain PTFE. Was applied to the surface to obtain an endless belt.

<Measurement>
-Water contact angle For the inner peripheral surface of the endless belt obtained in each example, the water contact angles at both ends were first measured. Specifically, the contact angles of water are measured by the above-mentioned method at a total of eight points at positions 10 mm central from both ends in the axial direction and at intervals of 90 ° in the circumferential direction, and the average value is the water at both ends. The contact angle was set.
Regarding the contact angle of water in the central part, the contact angle of water was measured at the center position in the axial direction of the inner peripheral surface and at intervals of 90 ° in the circumferential direction at a total of four points by the above-mentioned method, and the average value thereof. Was taken as the contact angle of water in the central part.

<Evaluation>
-Belt idle endurance test A belt idle endurance test was conducted on the endless belts obtained in each example by the following method.
As an intermediate transfer belt in the modified machine of ApeosPort-VC7776 (manufactured by Fuji Xerox Co., Ltd.), the endless belts obtained in Examples and Comparative Examples were attached, and A4 paper was attached at a process speed of 450 mm / sec without image formation. An idling durability test equivalent to 600,000 sheets was carried out.
Evaluation was made according to the following evaluation criteria.
A (○): No crack (break) occurs at the position where it contacts the roll edge of the inner peripheral surface of the endless belt B (×): Crack (break) occurs at the position where it contacts the roll edge of the inner peripheral surface of the endless belt

The depth of the crack (break) generated in Comparative Example 1 was 0.01 mm, and the depth of the crack (break) generated in Comparative Example 2 was 0.008 mm.

From the results shown in Table 1, it can be seen that in this example, the generation of cracks that occur when a plurality of rolls are hung in a tensioned state and repeatedly rotationally driven is suppressed as compared with the comparative example. ..

1Y, 1M, 1C, 1K Photoreceptor 2Y, 2M, 2C, 2K Charging roll 3Y, 3M, 3C, 3K Laser beam 3 Exposure device 4Y, 4M, 4C, 4K Developer 5Y, 5M, 5C, 5K Primary transfer roll 6Y, 6M, 6C, 6K Cleaning device 8Y, 8M, 8C, 8K Toner cartridge 10Y, 10M, 10C, 10K Image forming unit 20 Intermediate transfer belt 22 Drive roll 24 Support roll 26 Secondary transfer roll 30 Core body 51 Belt body Coating liquid 52 Flowing device 52A Nozzle 62 Blade (an example of smoothing mechanism)
101 Endless belt (transfer belt)
103 Belt body 103b Belt body coating film 103in Belt body inner peripheral surface 105 High contact angle 105b High contact angle coating film 105in High contact angle inner peripheral surface 109 Roll 109E Roll edge 201Y, 201M, 201C, 201BK Photoreceptor 202Y, 202M, 202C, 202BK Charging device 203Y, 203M, 203C, 203BK Exposed device 204Y, 204M, 204C, 204BK Developing device 205Y, 205M, 205C, 205BK Photoreceptor cleaning member 206 Recording medium transfer transfer belt 207Y, 207M , 207C, 207BK Transfer roll 208 Recording medium transfer roll 209 Fixing device 210, 211, 212, 213 Belt support roll 214 Belt cleaning member 216 Recording medium 301 Endless belt 303 Belt body Y, M, C, BK Image forming unit

Claims (5)

An endless belt that is hung and rotationally driven with tension applied to multiple rolls.
The belt body containing resin A and
It contains resin B and is arranged on the inner peripheral surface side of both ends in the belt axial direction and at a position where it comes into contact with the corner of the outer peripheral surface of the roll when it is rotationally driven, and is arranged on the outer peripheral surface side and the belt shaft. A high contact angle portion where the surface on the center side in the direction is in contact with the belt main body portion and the contact angle of water on the inner peripheral surface is higher than the inner peripheral surface of the belt main body portion.
Have a endless belt for said resin A and the resin B is an image forming apparatus including the same configuration units in the molecular structure. The endless belt according to claim 1, wherein the high contact angle portion contains a low friction material. Claim 1 or claim that the contact angle of water on the inner peripheral surface of the belt main body is 50 ° or more and 70 ° or less, and the contact angle of water on the inner peripheral surface of the high contact angle portion is 75 ° or more and 100 ° or less. The endless belt according to 2. The endless belt according to any one of claims 1 to 3.
A plurality of rolls in which the endless belt is hung under tension, and
An endless belt unit that is attached to and detached from the image forming apparatus. Image holder and
A charging means for charging the surface of the image holder and
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image holder, and
A developing means for developing a static charge image formed on the surface of the image holder as a toner image with a developer containing toner, and a developing means.
A transfer means having the endless belt unit according to claim 4 and transferring a toner image formed on the surface of the image holder to the surface of a recording medium via the endless belt.
An image forming apparatus comprising.

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