JP2018146795A - Transfer belt, transfer belt unit, image forming apparatus, and method for manufacturing transfer belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transfer belt that achieves both excellent cleanability and high flexibility.SOLUTION: A transfer belt comprises: a first resin layer that contains at least one resin A selected from the group consisting of polyimide and polyamide-imide, and at least one solvent A1 selected from the solvent group A consisting of N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, N,N-diethylacetamide, and γ-butyrolactone; and a second resin layer that is arranged on an outer peripheral surface of the first resin layer, and contains at least one resin B selected from the group consisting of polyimide and polyamide-imide, and at least one solvent B1 selected from the solvent group B consisting of a urea-based solvent, an alkoxy group-containing amide-based solvent, and an ester group-containing amide-based solvent.SELECTED DRAWING: None

Description

  The present invention relates to a transfer belt, a transfer belt unit, an image forming apparatus, and a transfer belt manufacturing method.

A belt member having a two-layer structure has been proposed as a belt member (intermediate transfer belt or the like) used in an image forming apparatus.
For example, Patent Document 1 includes an outer layer and an inner layer each having a polyimide resin as a resin component, and at least the outer layer polyimide resin constituting the outer layer contains a conductive substance and the outer layer polyimide resin. A semiconductive seamless belt is disclosed in which the elastic modulus of the resin is smaller than the elastic modulus of the inner layer polyimide resin constituting the inner layer.
Patent Document 2 discloses an intermediate transfer belt having an inner peripheral surface layer and an outer peripheral surface layer having a higher resistance than the inner peripheral surface layer by laminating a polyimide resin layer in which a conductive material is dispersed. The inner peripheral surface layer and the polyimide resin layer of the outer peripheral surface layer have the same ratio of the resin material and the conductive material in the polyimide resin, and have different drying temperatures when forming each layer. The common logarithm of the surface resistivity of the belt, the common logarithm of the surface resistivity of the inner peripheral surface layer, and the common logarithm of the volume resistivity of the belt when 100 V is applied are in a specific relationship. A transfer belt is disclosed.
Patent Document 3 discloses a conductive endless belt having a base layer containing a polyamide resin and a surface layer containing an aromatic polyimide resin.

JP 2002-162836 A JP2013-125201A JP 2012-215659 A

  The subject of the present invention is, in order from the inner surface side, a first resin layer containing at least one resin A selected from the group consisting of polyimide and polyamideimide, and at least one selected from the group consisting of polyimide and polyamideimide. In the transfer belt having the second resin layer containing the seed resin B, both the first resin layer and the second resin layer contain only the solvent A1 as a solvent, and excellent cleaning properties and high resistance to resistance are obtained. An object of the present invention is to provide a transfer belt having both flexibility.

  In order to achieve the above object, the following invention is provided.

The invention according to claim 1
At least one resin A selected from the group consisting of polyimide and polyamideimide, and N-methylpyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, N, N-diethylacetamide and γ-butyrolactone A first resin layer containing at least one solvent A1 selected from the solvent group A,
At least one resin B selected from the group consisting of polyimide and polyamideimide, and a urea solvent, an alkoxy group-containing amide solvent, and an ester group-containing amide solvent, disposed on the outer peripheral surface of the first resin layer A second resin layer containing at least one solvent B1 selected from the solvent group B consisting of:
A transfer belt having
The invention according to claim 2
2. The transfer according to claim 1, wherein at least one of the resins A contained in the first resin layer and at least one of the resins B contained in the second resin layer are composed only of structural units having the same structure. It is a belt.
The invention according to claim 3
The solvent B1 is tetramethylurea, tetraethylurea, 1,3-dimethyl-2-imidazolidinone, N, N-dimethylpropyleneurea, 3-methoxy-N, N-dimethylpropanamide, and 3-nbutoxy- 3. The transfer belt according to claim 1, wherein the transfer belt is at least one solvent selected from the group consisting of N, N-dimethylpropanamide.
The invention according to claim 4
The transfer belt according to any one of claims 1 to 3, wherein the solvent B1 is 1,3-dimethyl-2-imidazolidinone.
The invention according to claim 5
The average film thickness of the first resin layer is 50% or more with respect to the sum of the average film thicknesses of the first resin layer and the second resin layer. The transfer belt according to Item 1.
The invention according to claim 6
The transfer belt according to any one of claims 1 to 5,
A plurality of rolls over which the transfer belt is tensioned;
And a transfer belt unit that is detachably attached to the image forming apparatus.

The invention according to claim 7 provides:
An image carrier,
Charging means for charging the surface of the image carrier;
An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged image carrier;
Developing means for developing an electrostatic latent image on the surface of the image carrier with toner to form a toner image;
The transfer belt according to any one of claims 1 to 5,
Primary transfer means for primarily transferring the toner image formed on the surface of the image carrier onto the outer peripheral surface of the transfer belt;
Secondary transfer means for secondary transfer of the toner image primarily transferred to the outer peripheral surface of the transfer belt to a recording medium;
Fixing means for fixing the toner image secondarily transferred to the recording medium;
Cleaning means for cleaning the outer peripheral surface of the transfer belt;
An image forming apparatus.

The invention according to claim 8 provides:
At least one selected from the group consisting of polyimide precursors, polyamideimide precursors and polyamideimide resins, and N-methylpyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, N, N-diethylacetamide And a step of curing a composition containing at least one solvent A1 selected from solvent group A consisting of γ-butyrolactone to form a first resin layer;
At least one selected from the group consisting of a polyimide precursor, a polyamideimide precursor and a polyamideimide resin, and a solvent group B consisting of a urea solvent, an alkoxy group-containing amide solvent and an ester group-containing amide solvent. Curing the composition containing at least one solvent B1 to form a second resin layer on the outer peripheral surface of the first resin layer;
Is a manufacturing method of a transfer belt having

According to the invention according to claim 1 or 3, in order from the inner surface side, the first resin layer containing at least one kind of resin A selected from the group consisting of polyimide and polyamideimide, and the group consisting of polyimide and polyamideimide In the transfer belt having the second resin layer containing at least one resin B selected from the above, the first resin layer and the second resin layer are both superior to the case where the solvent contains only the solvent A1 as a solvent. Provided is a transfer belt in which both cleaning properties and high bending resistance are compatible.
According to the second aspect of the present invention, there is provided a transfer belt in which warpage is suppressed as compared with a case where at least one of the resins A and at least one of the resins B does not include a resin composed only of structural units having the same structure. Is done.
According to the invention of claim 4, as compared with the case where the solvent B1 is tetramethylurea, 3-methoxy-N, N-dimethylpropanamide, or 3-nbutoxy-N, N-dimethylpropanamide, A transfer belt having improved flex resistance is provided.
According to the invention which concerns on Claim 5, compared with the case where the average film thickness of a 1st resin layer is less than 50% with respect to the sum of the average film thickness of a 1st resin layer and a 2nd resin layer. Thus, a transfer belt with improved bending resistance is provided.

  According to the invention of claim 6 or 7, in order from the inner surface side, the first resin layer containing at least one kind of resin A selected from the group consisting of polyimide and polyamideimide, and the group consisting of polyimide and polyamideimide In the transfer belt having the second resin layer containing at least one kind of resin B selected from the above, compared to a case where a transfer belt in which both the first resin layer and the second resin layer contain the solvent A1 is applied, Provided is a transfer belt unit or an image forming apparatus provided with a transfer belt that has both excellent cleaning properties and high bending resistance.

  According to the invention according to claim 8, at least one selected from the group consisting of a polyimide precursor, a polyamideimide precursor and a polyamideimide resin, and a composition containing a solvent are cured to obtain the first resin layer and In an embodiment in which the second resin layer is formed in order, N-methylpyrrolidone may be used for both the solvent in the composition for forming the first resin layer and the solvent in the composition for forming the second resin layer. Compared to the case of containing only at least a solvent selected from solvent group A consisting of N, N-dimethylacetamide, N, N-dimethylformamide, N, N-diethylacetamide and γ-butyrolactone, Provided is a method for manufacturing a transfer belt that has both flexibility.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an exemplary embodiment. It is a schematic block diagram which shows another example of the image forming apparatus which concerns on this embodiment. It is a schematic perspective view which shows an example of the transfer belt unit which concerns on this embodiment.

  Hereinafter, an embodiment which is an example of the present invention will be described in detail.

<Transfer belt>
The transfer belt according to this embodiment includes at least one resin A selected from the group consisting of polyimide and polyamideimide, N-methylpyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, N, A first resin layer containing at least one solvent A1 selected from the solvent group A consisting of N-diethylacetamide and γ-butyrolactone; and disposed on the outer peripheral surface of the first resin layer, from polyimide and polyamideimide And at least one resin B selected from the group, and at least one solvent B1 selected from the solvent group B consisting of a urea solvent, an alkoxy group-containing amide solvent, and an ester group-containing amide solvent. 2 resin layers.

Here, as the transfer belt provided in the image forming apparatus, for example, an intermediate transfer belt used in an intermediate transfer type image forming apparatus; an intermediate transfer type image forming apparatus disposed in contact with an intermediate transfer body, A secondary transfer belt that conveys the recording medium to a transfer position where the toner image on the body is transferred to the recording medium; a toner image on the image holding body that is disposed in contact with the image holding body in an image forming apparatus of a direct transfer type A recording medium conveyance belt (direct transfer belt) that conveys the recording medium to a transfer position where the toner is transferred to the recording medium is used.
Since these transfer belts are stretched around a plurality of rolls under tension, the belts are bent in contact with the rolls during this rotation (bent along the roll surface). , The state of being straightened between the rolls is alternately repeated (for example, in the case of a transfer belt stretched around four rolls, the bending (bending) and the release from the bending are measured during one rotation. Repeated 4 times). Further, the bending resistance tends to decrease due to the repetition of the bent state (bent in the belt rotation direction) and the straightened state due to the long-time rotation drive.
In addition, the transfer belt may have a meandering (walking) phenomenon that approaches one side in the roll axis direction during rotation. From the viewpoint of suppressing the meandering, a meandering correction unit is provided at the end of the roll in the axial direction. There is. However, in a transfer belt that rotates in a meandering state, the inner peripheral surface is in contact with the roll surface and one end side is in contact with the meandering correction unit, and between the rolls, the roller and the meandering correction unit are in contact with each other. The state of not being repeated. At this time, a part of the transfer belt (a part in the roll axis direction) is bent when it is in contact with the meandering correction part, while it is straightened without being bent when it is not in contact with the meandering correction part. For this reason, with the rotation driving for a long time, a state in which a part of the transfer belt is bent (bent in the roll axis direction) and a state in which the transfer belt is straightened are repeated, and the transfer belt may be broken.
In addition, after the secondary transfer, in order to remove foreign matters such as toner and paper dust remaining on the belt surface, a cleaning means (for example, a cleaning blade, a cleaning brush, etc.) that contacts the belt surface may be provided. In the image forming apparatus, the operation of scraping the foreign matter on the belt surface by the cleaning unit is repeated with repeated image formation, which may cause damage to the belt surface. When the belt surface is damaged, foreign matters such as residual toner (especially, an external additive added to the surface of the toner) are easily embedded in the scratch. As a result, a cleaning failure is likely to occur.
The occurrence of poor cleaning is a problem that may occur due to scratches on the belt surface even in the secondary transfer belt and the recording medium conveyance belt in the direct transfer type image forming apparatus.

On the other hand, the transfer belt according to the present embodiment has, in order from the inner surface side, a first resin layer containing resin A and a second resin layer containing resin B, and the first resin layer is The solvent A1 is included, and the second resin layer includes the solvent B1.
As a result, a transfer belt that achieves both excellent cleaning properties and high bending resistance is realized. The reason is not clear, but is presumed as follows.
First, the significance of the second resin layer containing the solvent B1 will be described.
The second resin layer is a composition in which a precursor of resin B (at least one resin selected from the group consisting of polyimide and polyamideimide) and the like (for example, polyamic acid which is a precursor of polyimide) is dissolved in solvent B1. Is applied to form a coating layer (coating film), and this coating layer is heated and cured. It is considered that an interaction occurs between the polar group of the solvent B1 and the polar group of the resin B in the process of heating and curing the composition.
Here, the solvent B1 is a polar group (e.g., -O-, tertiary nitrogen atom (-) than the solvent A1 that has been widely used as a solvent for dissolving a polyimide precursor, a polyamideimide resin, or a precursor thereof. It is considered that the above interaction occurs more strongly than the interaction between the polar group of the solvent A1 and the polar group of the resin A because it has many N <)). Due to this interaction, in the second resin layer, a state in which the molecular chains of the solvent B1 and the molecular chain of the resin B are densely packed (hereinafter referred to as “packing state”) is formed. It is thought.
Due to this packing state, the hardness of the second resin layer (that is, the hardness of the outer layer) is increased, and even if image formation is repeated over a long period of time, the surface of the belt is less likely to be scratched.

Next, the significance of the first resin layer containing the solvent A1 will be described.
When the transfer belt is driven to rotate, the state in which the transfer belt is bent and the state in which the transfer belt is straightened are repeated as described above, and this bending becomes particularly tight toward the inner layer side of the transfer belt in contact with the roll. On the other hand, in the present embodiment, for the reasons described above, the first resin layer (inner layer) is more easily suppressed from increasing in hardness than the second resin layer (outer layer) and is likely to be a flexible layer. That is, in the present embodiment, the first resin layer located on the inner layer side to be bent more tightly has flexibility, so that the bending resistance is secured, and as a result, the bending resistance of the entire transfer belt is ensured. it is conceivable that.
Therefore, according to the transfer belt of the present embodiment, both excellent cleaning properties and high bending resistance are achieved.

The polar group of the solvent B1 corresponds to a urea group when the solvent B1 is a urea solvent, and corresponds to an alkoxy group and an amide group when the solvent B1 is an alkoxy group-containing amide solvent, and the solvent B1 is an ester group. In the case of containing amide solvents, ester groups and amide groups are applicable.
The polar group of the polyimide precursor and the polyimide resin corresponds to an amide group or a carboxyl group, and the polar group of the polyamideimide precursor and the polyamideimide resin corresponds to an amide group or an imide group.

The transfer belt according to this embodiment will be described in detail.
The transfer belt according to the present embodiment includes a first resin layer and a second resin layer disposed on the outer peripheral surface of the first resin layer.
In this embodiment, (a) even if the transfer belt is a two-layer transfer belt composed of only the first resin layer and the second resin layer, (b) the first resin layer, the second resin layer, and It may be a transfer belt in which other layers are laminated. However, (a) is preferable.
As another layer, for example, a sliding layer formed on the inner peripheral surface side of the first resin layer in order to improve slidability with various members such as a roll; for a recording medium (for example, paper) having a large surface irregularity And an elastic layer formed on the inner surface of the first resin layer for improving the followability.

<First resin layer (inner layer)>
The first resin layer includes resin A (at least one resin selected from the group consisting of polyimide and polyamideimide), N-methylpyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, N, And at least one solvent A1 selected from the solvent group A consisting of N-diethylacetamide and γ-butyrolactone.
The first resin layer is obtained using at least one of a polyimide precursor composition, a polyamideimide precursor composition, and a polyamideimide resin composition.
Hereinafter, a polyimide precursor composition (hereinafter also referred to as “polyimide precursor composition A1”), a polyamideimide precursor composition (hereinafter also referred to as “polyamideimide precursor composition A2”), a polyamideimide resin composition (hereinafter referred to as “polyamideimide precursor composition A2”). , Also referred to as “polyamideimide resin composition A3”).

(Polyimide precursor composition A1)
The polyimide precursor composition A1 includes a resin having a repeating unit represented by the following general formula (I) (hereinafter referred to as “specific polyimide precursor”), N-methylpyrrolidone, N, N-dimethylacetamide, N, And those containing at least one solvent A1 selected from solvent group A consisting of N-dimethylformamide, N, N-diethylacetamide and γ-butyrolactone. In addition, the polyimide precursor composition A1 may contain the electroconductive particle mentioned later and another additive as needed.

-Polyimide precursor (polyamic acid)-
Examples of the polyimide precursor include a resin having a repeating unit represented by the general formula (I).

(In general formula (I), A represents a tetravalent organic group, and B represents a divalent organic group.)

Here, in the general formula (I), the tetravalent organic group represented by A is a residue obtained by removing four carboxyl groups from a tetracarboxylic dianhydride as a raw material.
On the other hand, the divalent organic group represented by B is a residue obtained by removing two amino groups from a diamine compound as a raw material.

  That is, the specific polyimide precursor having a repeating unit represented by the general formula (I) is a polymer of tetracarboxylic dianhydride and a diamine compound.

  The tetracarboxylic dianhydride includes both aromatic and aliphatic compounds, but is preferably an aromatic compound. That is, in the general formula (I), the tetravalent organic group represented by A is preferably an aromatic organic group.

  Examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, and 3,3 ′, 4,4′-biphenyl. Sulfonetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3 ′, 4,4′- Biphenyl ether tetracarboxylic dianhydride, 3,3 ′, 4,4′-dimethyldiphenylsilane tetracarboxylic dianhydride, 3,3 ′, 4,4′-tetraphenylsilane tetracarboxylic dianhydride, 1 , 2,3,4-furantetracarboxylic dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenyl sulfide dianhydride, 4,4′-bis (3,4-dicarboxyl) Noxi) diphenylsulfone dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylpropane dianhydride, 3,3 ′, 4,4′-perfluoroisopropylidenediphthalic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, bis (phthalic acid) phenylphosphine oxide dianhydride, p- Phenylene-bis (triphenylphthalic acid) dianhydride, m-phenylene-bis (triphenylphthalic acid) dianhydride, bis (triphenylphthalic acid) -4,4′-diphenyl ether dianhydride, bis (triphenyl) Phthalic acid) -4,4'-diphenylmethane dianhydride.

  Examples of the aliphatic tetracarboxylic dianhydride include butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4. -Cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 3,5,6-tricarboxynorbonane 2-acetic acid dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 5- (2,5-dioxotetrahydrofuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid Aliphatic or alicyclic tetracarboxylic dianhydrides such as acid dianhydrides, bicyclo [2,2,2] -oct-7-ene-2,3,5,6-tetracarboxylic dianhydrides; , 3,3a, 4,5,9b-hexahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 1,3,3a, 4,5 9b-Hexahydro-5-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 1,3,3a, 4,5 Aliphatic tetracarboxylic acids having an aromatic ring such as 9b-hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione A dianhydride etc. are mentioned.

  Among these, the tetracarboxylic dianhydride is preferably an aromatic tetracarboxylic dianhydride, specifically, for example, pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyl. Tetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyl ether tetracarboxylic dianhydride, 3,3 ′, 4 , 4′-benzophenonetetracarboxylic dianhydride is preferable, and pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4 ′ -Benzophenone tetracarboxylic dianhydride is good, especially 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride.

In addition, tetracarboxylic dianhydride may be used individually by 1 type, and may be used together in combination of 2 or more types.
When two or more kinds are used in combination, aromatic tetracarboxylic dianhydride or aliphatic tetracarboxylic dianhydride may be used in combination, and aromatic tetracarboxylic dianhydride and aliphatic tetracarboxylic You may combine with an acid dianhydride.

  On the other hand, a diamine compound is a diamine compound having two amino groups in the molecular structure. Examples of diamine compounds include aromatic and aliphatic compounds, but aromatic compounds are preferred. That is, in the general formula (I), the divalent organic group represented by B is preferably an aromatic organic group.

Examples of the diamine compound include p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylethane, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl sulfide. 4,4′-diaminodiphenylsulfone, 1,5-diaminonaphthalene, 3,3-dimethyl-4,4′-diaminobiphenyl, 5-amino-1- (4′-aminophenyl) -1,3,3 -Trimethylindane, 6-amino-1- (4'-aminophenyl) -1,3,3-trimethylindane, 4,4'-diaminobenzanilide, 3,5-diamino-3'-trifluoromethylbenzanilide 3,5-diamino-4′-trifluoromethylbenzanilide, 3,4′-diaminodiphenyl ether, 2 7-diaminofluorene, 2,2-bis (4-aminophenyl) hexafluoropropane, 4,4′-methylene-bis (2-chloroaniline), 2,2 ′, 5,5′-tetrachloro-4, 4'-diaminobiphenyl, 2,2'-dichloro-4,4'-diamino-5,5'-dimethoxybiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 4,4'-diamino- 2,2′-bis (trifluoromethyl) biphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) -biphenyl, 1,3′-bis (4-aminophenoxy) benzene, 9,9-bis 4-aminophenyl) fluorene, 4,4 ′-(p-phenyleneisopropylidene) bisaniline, 4,4 ′-(m-phenyleneisopropylidene) bisaniline, 2,2′-bis [4- (4-amino-2 -Trifluoromethylphenoxy) phenyl] hexafluoropropane, aromatic diamines such as 4,4′-bis [4- (4-amino-2-trifluoromethyl) phenoxy] -octafluorobiphenyl; diaminotetraphenylthiophene, etc. An aromatic diamine having two amino groups bonded to an aromatic ring and a hetero atom other than the nitrogen atom of the amino group; 1,1-metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylene Diamine, Octamethylenediamine, Nonamethylenediamine, 4,4-Diaminohept Diamine, 1,4-diaminocyclohexane, isophorone diamine, tetrahydrodicyclopentadiene cyclopentadienylide diamine, hexahydro-4,7-meth Noin mite range diamine, tricyclo [6,2,1,0 ^2.7] - Examples thereof include aliphatic diamines such as undecylenedimethyl diamine and 4,4′-methylene bis (cyclohexylamine), and alicyclic diamines.

  Among these, as the diamine compound, an aromatic diamine compound is preferable. Specifically, for example, p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl sulfide, and 4,4′-diaminodiphenyl sulfone are preferable, and 4,4′-diaminodiphenyl ether and p-phenylenediamine are particularly preferable.

  In addition, a diamine compound may be used individually by 1 type, and may be used together in combination of 2 or more types. Moreover, when using together and using 2 or more types, you may use together an aromatic diamine compound or an aliphatic diamine compound, respectively, or may combine an aromatic diamine compound and an aliphatic diamine compound.

The specific polyimide precursor may be a resin partially imidized.
Specifically, examples of the specific polyimide precursor include a resin having a repeating unit represented by General Formula (I-1), General Formula (I-2), and General Formula (I-3).

In General Formula (I-1), General Formula (I-2), and General Formula (I-3), A represents a tetravalent organic group, and B represents a divalent organic group. In addition, A and B are synonymous with A and B in general formula (I).
l represents an integer of 1 or more, and m and n each independently represents 0 or an integer of 1 or more.

The number average molecular weight of the specific polyimide precursor is preferably from 5,000 to 100,000, more preferably from 7,000 to 50,000, and still more preferably from 10,000 to 30,000.
When the number average molecular weight of the specific polyimide precursor is within the above range, the solubility of the polyimide precursor in the composition and the mechanical properties of the film after film formation are improved.
In addition, the specific polyimide precursor of the target number average molecular weight is obtained by adjusting the molar equivalent ratio of a tetracarboxylic dianhydride and a diamine compound.

The number average molecular weight of the specific polyimide precursor is measured by a gel permeation chromatography (GPC) method under the following measurement conditions.
Column: Tosoh TSKgel α-M (7.8 mm ID × 30 cm)
Eluent: DMF (dimethylformamide) / 30 mM LiBr / 60 mM phosphoric acidFlow rate: 0.6 mL / min
・ Injection volume: 60 μL
・ Detector: RI (differential refractive index detector)

  The content (concentration) of the specific polyimide precursor may be 0.1% by mass or more and 40% by mass or less, preferably 0.5% by mass or more and 25% by mass with respect to the total polyimide precursor composition A1. Hereinafter, it is more preferably 1% by mass or more and 20% by mass or less.

(Polyamideimide precursor composition A2 and polyamideimide resin composition A3)
The polyamideimide precursor composition A2 is composed of a polyamideimide precursor and a solvent group A consisting of N-methylpyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, N, N-diethylacetamide and γ-butyrolactone. And at least one solvent A1 selected. The polyamideimide resin composition A3 is selected from a solvent group A consisting of a polyamideimide resin and N-methylpyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, N, N-diethylacetamide and γ-butyrolactone. And at least one solvent A1. In addition, the polyamideimide precursor composition A2 and the polyamideimide resin composition A3 may include conductive particles described later and other additives as necessary.

-Polyamideimide precursor and polyamideimide resin-
Examples of the polyamideimide precursor include polyamide-polyamic acid which is a condensate from tricarboxylic acid and diamine compound. When the polyamide-polyamic acid as the polyamide-imide precursor is subjected to an imidization reaction (dehydration ring-closing reaction), a polyamide-imide resin is obtained.
Specifically, the polyamideimide precursor is, for example, (1) a method in which an equimolar amount of a tricarboxylic acid anhydride and a diamine is polycondensed in an organic polar solvent in the presence of a dehydration catalyst at a high temperature; A method in which an equimolar amount of acid monochloride and diamine is subjected to polycondensation and imidization reaction at low temperature in an organic polar solvent, and (3) a method in which tricarboxylic acid anhydride and diisocyanate are polycondensed at high temperature in an organic polar solvent. , Etc., and polyamide-polyamic acid obtained. And when the polyamide-polyamic acid which is the obtained polyamide-imide precursor is imidized (dehydration ring-closing reaction), a polyamide-imide resin is obtained.

  Examples of the tricarboxylic acid anhydride include trimellitic acid anhydride or trimellitic acid monochloride.

Examples of the diamine compound include those similar to those exemplified as the diamine compound used for the synthesis of the polyamic acid (hereinafter also referred to as “DA-1”) in the description of the polyimide precursor described above. Examples of the diamine compound also include the following aromatic diamine compounds (hereinafter also referred to as “DA-2”).
Of these, aromatic diamine compounds are preferred, and DA-2 is particularly preferred.
Specific examples of the aromatic diamine compound (DA-2) include 3,3′-diaminobenzophenone, p-phenylenediamine, 4,4′-diaminodiphenyl, 4,4′-diaminodiphenylamide, 4 , 4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, bis [4- {3- (4-aminophenoxy) benzoyl} phenyl] ether, 4,4′-bis (3-aminophenoxy) biphenyl, Bis [4- (3-aminophenoxy) phenyl] sulfone 2,2′-bis [4- (3-aminophenoxy) phenyl] propane.

Examples of the diisocyanate compound include those in which two amino groups in the diamine compound (DA-1) used for the synthesis of polyamic acid are substituted with isocyanate groups. Moreover, as a diisocyanate compound, the diisocyanate compound shown below (henceforth "DI-1") is also mentioned. Among these, DI-1 is preferable.
Specific examples of the diisocyanate compound (DI-1) include 3,3′-dimethylbiphenyl-4,4′-diisocyanate, 2,2′-dimethylbiphenyl-4,4′-diisocyanate, and biphenyl-4,4′-diisocyanate. Biphenyl-3,3'-diisocyanate, biphenyl-3,4'-diisocyanate, 3,3'-diethylbiphenyl-4,4'-diisocyanate, 2,2'-diethylbiphenyl-4,4'-diisocyanate, 3, , 3′-dimethoxybiphenyl-4,4′-diisocyanate, 2,2′-dimethoxybiphenyl-4,4′-diisocyanate.
Examples of the diisocyanate compound include those obtained by stabilizing an isocyanato group with a blocking agent. The blocking agent includes alcohol, phenol, oxime, etc., but there is no particular limitation.

<Second resin layer (outer layer)>
The second resin layer is a solvent group consisting of a resin B (at least one resin selected from the group consisting of polyimide and polyamideimide), a urea solvent, an alkoxy group-containing amide solvent, and an ester group-containing amide solvent. And at least one solvent B1 selected from B.
The second resin layer is contained in the polyamideimide precursor composition A2 in which the solvent A1 contained in the polyimide precursor composition A1 is changed to the solvent B1 (hereinafter also referred to as “polyimide precursor composition B1”). What changed the solvent A1 into the solvent B1 (hereinafter also referred to as “polyamideimide precursor composition B2”), and what changed the solvent A1 contained in the polyamideimide resin composition A3 into the solvent B1 (hereinafter referred to as “polyamideimide”). It is obtained in the same manner as the first resin layer using at least one of the resin compositions B3 ”.
Moreover, a polyimide precursor, a polyamideimide precursor, and a polyamideimide resin are synonymous with the above-mentioned thing.

(Solvent B1)
The solvent B1 contained in the second resin layer is at least one selected from the solvent group B consisting of a urea solvent, an alkoxy group-containing amide solvent, and an ester group-containing amide solvent.
Hereinafter, a urea solvent, an alkoxy group-containing amide solvent, and an ester group-containing amide solvent will be described in order.

-Urea solvent-
The urea solvent is a solvent having a urea group (N—C (═O) —N). Specifically, the urea-based solvent is preferably a solvent having a “* —N (Ra ¹ ) —C (═O) —N (Ra ² ) — *” structure. Here, Ra ¹ and Ra ² each independently represent a hydrogen atom, an alkyl group, a phenyl group, or a phenylalkyl group. Both ends * of two N atoms indicate a bonding site with another atomic group of the structure. A urea solvent is a solvent having a ring structure in which both ends * of two N atoms are linked via a linking group consisting of, for example, alkylene, -O-, -C (= O)-, or a combination thereof. It may be.

The alkyl group representing Ra ¹ and Ra ² may be any of chain, branched, and cyclic, and may have a substituent. Specific examples of the alkyl group include alkyl groups having 1 to 6 carbon atoms (preferably 1 to 4 carbon atoms) (for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group). Etc.).
Examples of the substituent of the alkyl group include an alkoxy group (preferably an alkoxy group having 1 to 4 carbon atoms), a hydroxyl group, a ketone group, an ester group, an alkylcarbonyloxy group, and the like. Specific examples of the alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, an i-butoxy group, and a t-butoxy group.
Specific examples of the ketone group include a methylcarbonyl group (acetyl group), an ethylcarbonyl group, and an n-propylcarbonyl group. Specific examples of the ester group include methoxycarbonyl group (—COOMe), ethoxycarbonyl group, n-propoxycarbonyl group, acetoxy group (—OC (═O) Me) and the like. Specific examples of the alkylcarbonyloxy group include a methylcarbonyloxy group (acetyloxy group), an ethylcarbonyloxy group, and an n-propylcarbonyloxy group.

The phenyl skeleton of the phenyl group and phenylalkyl group representing Ra ¹ and Ra ² may have a substituent. Examples of the substituent of the phenyl skeleton include the same substituents as the alkyl group.

  In addition, when the urea solvent has a ring structure in which both ends * of the two N atoms are connected, the number of ring members is preferably 5 or 6.

  Examples of urea solvents include 1,3-dimethylurea, 1,3-diethylurea, 1,3-diphenylurea, 1,3-dicyclohexylurea, tetramethylurea, tetraethylurea, and 2-imidazolidinone. Propylene urea, 1,3-dimethyl-2-imidazolidinone, N, N′-dimethylpropylene urea, and the like.

-Alkoxy group-containing amide solvent, ester group-containing amide solvent-
The alkoxy group-containing amide solvent is a solvent having an alkoxy group and an amide group. On the other hand, the ester group-containing amide solvent is a solvent having an ester group and an amide group. Examples of the alkoxy group and the ester group include the same groups as the alkoxy group and the ester group exemplified as “substituents for alkyl groups representing Ra ¹ and Ra ² ” in the description of the urea solvent. The alkoxy group-containing amide solvent may have an ester group, and the ester group-containing amide solvent may have an alkoxy group.

  Hereinafter, both the alkoxy group-containing amide solvent and the ester group-containing amide solvent will be referred to as “alkoxy group or ester group-containing amide solvent”.

  The alkoxy group or ester group-containing amide solvent is not particularly limited, and specifically, an amide solvent represented by the following general formula (Am1), an amide solvent represented by the following general formula (Am2), and the like are preferable. It is mentioned in.

In General Formula (Am1), Rb ¹ , Rb ² , Rb ³ , Rb ⁴ , Rb ⁵ , and Rb ⁶ each independently represent a hydrogen atom or an alkyl group. Rb ⁷ represents an alkoxy group or an ester group.
The alkyl group representing Rb ^{1 to} Rb ⁶ has the same meaning as the “alkyl group representing Ra ¹ and Ra ² ” described in the description of the urea solvent.
Alkoxy and ester groups show a rb ^7, in the description of urea solvent, exemplified alkoxy groups as the "substituents for the alkyl group represented by Ra ^1, and Ra ^2" is synonymous with an ester group.

  Specific examples of the amide solvent represented by the general formula (Am1) are shown below, but are not limited thereto.

  In specific examples of the amide solvent represented by the general formula (Am1), Me = methyl group, Et = ethyl group, nPr = n-propyl group, nBu = n-butyl group.

In General Formula (Am2), Rc ¹ , Rc ² , Rc ³ , Rc ⁴ , Rc ⁵ , Rc ⁶ , Rc ⁷ , and Rc ⁸ each independently represent a hydrogen atom or an alkyl group. Rc ⁹ represents an alkoxy group or an ester group.
Alkyl group represented by rc ¹ to Rc ⁸ is synonymous with that described in the description of the urea-based solvent "alkyl group represented by Ra ^1, and Ra ^2".
Alkoxy and ester groups show a rc ^9, in explanation of the urea based solvent, exemplified alkoxy groups as the "substituents for the alkyl group represented by Ra ^1, and Ra ^2" is synonymous with an ester group.

  Specific examples of the amide solvent represented by the general formula (Am2) are shown below, but are not limited thereto.

  In specific examples of the amide solvent represented by the general formula (Am2), Me = methyl group, Et = ethyl group, and nPr = n-propyl group.

Among the solvent group B described above (urea solvents, alkoxy group-containing amide solvents, and ester group-containing amide solvents), examples of urea solvents include tetramethylurea, tetraethylurea, and 1,3-dimethyl-2. -Imidazolidinone and N, N-dimethylpropyleneurea are preferable. Examples of the amide solvent containing an alkoxy group or an ester group include 3-methoxy-N, N-dimethylpropanamide (Exemplary Compound B-4), 3-nbutoxy -N, N-dimethylpropanamide (Exemplary Compound B-7) is preferred. Among these, 1,3-dimethyl-2-imidazolidinone (DMI) is particularly preferable.
These tetramethylurea, tetraethylurea, 1,3-dimethyl-2-imidazolidinone, N, N-dimethylpropyleneurea, 3-methoxy-N, N-dimethylpropanamide, or 3-n butoxy-N, N -Dimethylpropanamide (hereinafter referred to as “specific solvent B1”) has two polar groups in one molecule. Specifically, the specific solvent B1 has at least one of —O— and a tertiary nitrogen atom (—N <). On the other hand, for example, N-methylpyrrolidone has been widely used as a solvent for dissolving a polyimide precursor, a polyamideimide precursor, and a polyamideimide resin. For example, N-methylpyrrolidone has only one tertiary nitrogen atom (-N <) in one molecule. I don't have it. For this reason, by including the specific solvent B1 (preferably 1,3-dimethyl-2-imidazolidinone) in the second resin layer, the mutual relationship between the polar group of the specific solvent B1 and the polar group of the resin B is increased. The action is likely to occur more strongly than the interaction between the polar group of the solvent A1 and the polar group of the resin A, that is, the above-described packing state is more likely to be formed in the second resin layer. As a result, it is considered that the surface of the belt is less likely to be damaged, and as a result, the cleaning property is further improved.

In the transfer belt according to the present embodiment, it is preferable that at least one of the resins A included in the first resin layer and at least one of the resins B included in the second resin layer include structural units having the same structure. . That is, it is preferable that at least one kind of resin A and at least one kind of resin B are resins using at least one monomer having the same molecular structure as a raw material.
However, in both the first resin layer and the second resin layer, the proportion of the resin containing structural units having the same structure is preferably 50% by mass or more based on the total resin contained in each resin layer.
Moreover, it is more preferable that at least one of the resins A contained in the first resin layer and at least one of the resins B contained in the second resin layer are resins composed only of structural units having the same structure. In this case, in both the first resin layer and the second resin layer, it is preferable that the ratio of the resin consisting only of structural units having the same structure is 50% by mass or more based on the total resin contained in each resin layer. Further, it is more preferable that both the resin A and the resin B include only one kind of resin, and the resin A and the resin B are resins composed only of structural units having the same structure.
Thereby, the warp of the transfer belt is suppressed. That is, dimensional stability is improved. The reason for this is that at least one of the resins contained in the first resin layer and the second resin layer includes a structural unit having the same structure, so that the adhesion between the first resin layer and the second resin layer is improved. This is considered to be due to the fact that the difference in thermal shrinkage between the first resin layer and the second resin layer and the difference in thermal expansion are less likely to occur while improving.

Whether at least one of the resins contained in the first resin layer and the second resin layer contains a structural unit having the same structure can be confirmed by the following method.
The first resin layer and the second resin layer are sampled from the transfer belt, and the infrared absorption spectrum is measured for each resin layer. As a result, when characteristic peaks (a peak derived from an amide bond, a peak derived from an imide bond) possessed by a polyamide resin or a polyamideimide resin are present in the same wavelength region, it can be determined that the structural unit includes the same structure. .
In addition, when it is difficult to determine whether or not structural units having the same structure are included in the measurement of the infrared absorption spectrum, the measurement result of ¹ H-NMR ( ¹ H-nuclear magnetic resonance method) may be used as necessary.

In the transfer belt of this embodiment, the average film thickness of the first resin layer is the sum of the average film thicknesses of the first resin layer and the second resin layer from the viewpoint of improving the bending resistance of the entire transfer belt. On the other hand, it is preferably 50% or more, more preferably 60% or more, and further preferably 65% or more.
The upper limit is preferably 90% or less, more preferably 85% or less, and still more preferably 80% or less.

The average film thicknesses of the first resin layer and the second resin layer are measured by the following method.
The first resin layer and the second resin layer are collected from the transfer belt, and the cross section of each resin layer is observed using a color 3D laser microscope (model VK85550) manufactured by Keyence Corporation. And the thickness of arbitrary 10 places in a cross section is measured, and let the average value of these thickness be the average film thickness of each resin layer.

(Conductive particles)
The resin layer (referring to at least one of the first resin layer and the second resin layer, hereinafter the same) may contain conductive particles added for imparting conductivity. The conductive particles may be conductive (for example, a volume resistivity of less than 10 ⁷ Ω · cm, the same shall apply hereinafter) or semiconductive (for example, a volume resistivity of 10 ⁷ Ω · cm to 10 ¹³ Ω · cm, and the same shall apply hereinafter). Selected) depending on the purpose of use.
Examples of the conductive particles include carbon black, metal (for example, aluminum and nickel), metal oxide (for example, yttrium oxide and tin oxide), and ion conductive material (for example, potassium titanate, LiCl, and the like). .
These conductive particles may be used alone or in combination of two or more. The primary particle size of the conductive particles is preferably less than 10 μm (preferably 1 μm or less).

Among these, as the conductive particles, carbon black is preferable, and acidic carbon black having a pH of 5.0 or less is particularly preferable.
As acidic carbon black, from the viewpoint of electrical resistance stability over time, acidic carbon black having a pH of 4.5 or less is more preferable, and acidic carbon black having a pH of 4.0 or less is more preferable.
Examples of the acidic carbon black include carbon black whose surface is oxidized, 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.
In addition, pH of acidic carbon black is a value measured by the pH measuring method of JISZ8802 (2011) regulation.

  Specific examples of carbon black include “Special Black 350”, “Special Black 100”, “Special Black 250”, “Special Black 5”, “Special Black 4” and “Special” manufactured by Orion Engineered Carbons. "Black 4A", "Special Black 550", "Special Black 6", "Color Black FW200", "Color Black FW1", "Color Black FW2", "Color Black FW2V", Cabot "MONARCH1000", Cabot “MONARCH 1300”, “MONARCH 1400”, “MOGUL-L”, “REGAL 400R” and the like can be mentioned.

  The content of the conductive particles is not particularly limited, but is 1 part by mass with respect to 100 parts by mass of the entire resin contained in the resin layer from the viewpoint of the appearance, mechanical, and electrical quality of the transfer belt. It is good that it is 40 mass parts or less (preferably 10 mass parts or more and 30 mass parts or less). In addition, if electroconductive particle is included in the composition (Polyimide precursor composition A1, B1, Polyamideimide precursor composition A2, B2, or Polyamideimide resin composition A3, B3) for obtaining the said resin layer. Good.

(Other additives)
The resin layer may contain various fillers for the purpose of imparting various functions such as mechanical strength. Further, it may contain a catalyst for promoting imidization reaction, a leveling agent for improving film forming quality, an antioxidant for preventing thermal deterioration of the transfer belt, a surfactant for improving fluidity, and the like. .
What is necessary is just to select content of another additive according to the characteristic made into the said resin layer. Other additives may be included in the composition for obtaining the resin layer.

[Characteristics of transfer belt, etc.]
In the transfer belt according to the present embodiment, from the viewpoint of achieving both excellent cleaning properties and high bending resistance, the Young's modulus of the first resin layer, the Young's modulus of the second resin layer, and the second resin layer and A preferable range of the difference in Young's modulus of the first resin layer (Young's modulus of the second resin layer−Young's modulus of the first resin layer) is as follows.
The difference in Young's modulus between the second resin layer and the first resin layer is preferably 300 MPa to 2000 MPa, more preferably 400 MPa to 1000 MPa.
A method for measuring the Young's modulus will be described in the section of Examples.

When the transfer belt according to this embodiment is applied to, for example, an intermediate transfer belt, the total thickness (average thickness) of the intermediate transfer belt is 0.05 mm to 0.5 mm (preferably 0.06 mm to 0.30 mm). ).
When the transfer belt according to this embodiment is applied to, for example, a recording medium conveyance belt (direct transfer belt), the total thickness (average thickness) of the recording medium conveyance belt is 0.05 mm or more and 0.5 mm or less (preferably 0.06 mm to 0.30 mm).

[Method of manufacturing transfer belt]
The transfer belt manufacturing method according to this embodiment includes at least one selected from the group consisting of a polyimide precursor, a polyamideimide precursor, and a polyamideimide resin, and N-methylpyrrolidone, N, N-dimethylacetamide, N Curing a composition containing at least one solvent A1 selected from solvent group A consisting of N, N-dimethylformamide, N, N-diethylacetamide and γ-butyrolactone to form a first resin layer; At least one selected from the group consisting of a polyimide precursor, a polyamideimide precursor and a polyamideimide resin, and a solvent group B consisting of a urea solvent, an alkoxy group-containing amide solvent and an ester group-containing amide solvent. And curing the composition containing at least one solvent B1. And a step of forming a second resin layer on the outer peripheral surface of the fat layer.
As an example of the manufacturing method of the transfer belt according to the present embodiment, for example, a step of preparing a composition for forming each layer (first resin layer, second resin layer), respectively (preparing step of the composition) Then, the prepared composition is applied onto a cylindrical substrate (for example, a cylindrical mold) so that the first resin layer is an inner layer and the second resin layer is an outer layer, thereby forming a coating film. Examples thereof include a method having a step (hereinafter also referred to as “coating film forming step”) and a step of drying the coating film formed on the substrate (hereinafter also referred to as “drying step”). In addition, you may have the process (henceforth a "resin film formation process") which further heats the dried coating film (dry film) and forms a resin film.
The “coating film forming step” corresponds to the above-described “step of forming the first resin layer” and “step of forming the second resin layer”.
Hereinafter, as an example of a method for manufacturing a transfer belt, a case where the transfer belt includes a first resin layer and a second resin layer, and the first resin layer and the second resin layer include a polyimide resin will be described. To do. In addition, also when the 1st resin layer and the 2nd resin layer contain a polyamide-imide resin, a transfer belt can be manufactured according to the following method.

<Process for preparing composition>
In the preparation process of the composition, a polyimide precursor composition A1 and a polyimide precursor composition B1 (hereinafter simply referred to as “precursor composition”) for forming each resin layer (first resin layer, second resin layer). In the precursor composition, conductive particles such as carbon black may be dispersed according to the purpose, and other additives may be dispersed as necessary. As a method for dispersing these in the precursor composition, for example, a media mill for pulverizing using the impact force of media such as ceramic beads and balls, a high shear force passing through an orifice at a high pressure and colliding with the media. Commonly used dispersion methods such as wet jet mills and homogenizers that utilize the impact force of the time are included.

<Formation process of coating film>
Next, the precursor composition is applied to the inner surface or the outer surface of the cylindrical substrate so that the first resin layer becomes the inner layer and the second resin layer becomes the outer layer, thereby forming a coating film. As the cylindrical substrate, for example, a cylindrical metal substrate is preferably used. Instead of metal, a base material made of other material such as resin, glass, or ceramic may be used. Further, a glass coat, a ceramic coat, or the like may be provided on the surface of the base material, or a silicone-based or fluorine-based release agent may be applied.

Here, in order to apply the precursor composition with high accuracy, a step of defoaming the precursor composition is preferably performed before the application. By defoaming the precursor composition, foaming at the time of coating and occurrence of defects in the coating film are suppressed.
Examples of the method for defoaming the precursor composition include a method for reducing the pressure, a method for centrifuging, and the like. However, defoaming under a reduced pressure is simple and suitable for high defoaming ability.

  As a method of applying the precursor composition to the surface of the cylindrical base material, for example, by discharging the precursor composition from the nozzle, the cylindrical base material is moved by moving the rotating cylindrical base material in the rotation axis direction. A method of applying a precursor composition to the outer peripheral surface of a cylindrical substrate, a dip coating method in which a cylindrical substrate is immersed in the precursor composition and pulling it up, an inner periphery of the cylindrical substrate A method of pouring the surface in the axial direction can be used.

<Drying process>
Subsequently, the formed coating film is dried to form a dry film.
The coating film is dried by, for example, heating the substrate while rotating it to volatilize the solvent. It is preferable to dry the coating film until the precursor composition does not sag even without rotating the substrate.
As drying conditions, for example, a drying time in the range of 50 ° C. or higher and 180 ° C. or lower (preferably 60 ° C. or higher and 150 ° C. or lower) in the range of 15 minutes or longer and 60 minutes or shorter (preferably 20 minutes or longer and 40 minutes or shorter); More preferably.
In addition, it is preferable that the solvent content in a dry film | membrane is 50 mass% or less (preferably 30 mass% or less) with respect to the total mass of a dry film | membrane.

<Resin film formation process>
Then, you may have the process of heating the formed dry film at still higher temperature (in this embodiment, an imidation process is performed).
By heating at a higher temperature, the solvent is further volatilized in the dry film, and a resin film (a first resin layer and a second resin layer) containing a polyimide resin is formed.
As heating conditions for the imidization treatment, for example, by heating at 150 ° C. or higher and 400 ° C. or lower (preferably 200 ° C. or higher and 300 ° C. or lower) for 20 minutes or longer and 60 minutes or shorter, an imidization reaction occurs and a resin film is formed. The In the heating reaction, before reaching the final temperature of heating, it is preferable to heat by gradually increasing the temperature stepwise or at a constant rate. The temperature of imidization varies depending on, for example, the types of tetracarboxylic dianhydride and diamine used as raw materials. If imidization is insufficient, the mechanical properties and electrical properties are inferior, so that the imidization is completed. Set.
Thereafter, the resin film is peeled off from the cylindrical substrate by a known method such as blowing air into the gap between the cylindrical substrate and the resin film.
By passing through the above process, the transfer belt of this embodiment is obtained.

[Usage example of transfer belt]
The transfer belt according to this embodiment can be used as, for example, a transfer belt for an electrophotographic image forming apparatus. Examples of the transfer belt for an electrophotographic image forming apparatus include, for example, an intermediate transfer belt used in an intermediate transfer type image forming apparatus; an intermediate transfer belt disposed in contact with an intermediate transfer body in an intermediate transfer type image forming apparatus. A secondary transfer belt that conveys the recording medium to a transfer position where the toner image on the body is transferred to the recording medium; a toner image on the image holding body that is disposed in contact with the image holding body in an image forming apparatus of a direct transfer type And a belt member such as a recording medium conveyance belt that conveys the recording medium to a transfer position at which the recording medium is transferred to the recording medium.

<Image forming apparatus>
An image forming apparatus according to this embodiment includes the transfer belt of the above embodiment. When the transfer belt is applied to a belt member such as an intermediate transfer belt or a recording medium conveyance belt, the image forming apparatus according to the present embodiment includes, for example, an image carrier and a charging unit that charges the surface of the image carrier. A latent image forming unit that forms a latent image on the surface of the charged image carrier, a developing unit that develops the latent image formed on the surface of the image carrier as a toner image with a developer containing toner, and a toner. And a transfer unit that includes the transfer belt according to the exemplary embodiment and transfers the toner image onto the surface of the recording medium.
The transfer unit may include a transfer belt unit described later.

  Specifically, in the image forming apparatus according to the present embodiment, for example, the transfer unit includes an intermediate transfer member, a primary transfer unit that primarily transfers a toner image formed on the image holding member to the intermediate transfer member, and the intermediate transfer member. And a secondary transfer unit that secondary-transfers the toner image transferred to the recording medium, and includes the transfer belt according to the present embodiment as the intermediate transfer member.

  In addition, the image forming apparatus according to the present embodiment includes, for example, a recording medium conveyance body (recording medium conveyance belt) for the transfer unit to convey the recording medium, and a toner image formed on the image holding body. And a transfer means for transferring to the recording medium transported by the recording medium, and the transfer belt according to the present embodiment may be provided as the recording medium transport body.

  The image forming apparatus according to the present embodiment is, for example, a normal monocolor image forming apparatus in which only a single color toner is accommodated in a developing device, and a toner image held on an image holding body is sequentially subjected to primary transfer to an intermediate transfer body. Examples thereof include a color image forming apparatus that repeats and a tandem type color image forming apparatus in which a plurality of image carriers each having a developing device for each color are arranged in series on an intermediate transfer member.

  Hereinafter, an image forming apparatus according to the present embodiment will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to the present embodiment. The image forming apparatus shown in FIG. 1 is an image forming apparatus in which the transfer belt according to the present embodiment is applied to an intermediate transfer member (intermediate transfer belt).
As shown in FIG. 1, the image forming apparatus 100 according to the present embodiment is, for example, a so-called tandem method, and around the four image carriers 101 a to 101 d made of an electrophotographic photosensitive member along the rotation direction. In order, charging devices 102a to 102d, exposure devices 114a to 114d, developing devices 103a to 103d, primary transfer devices (primary transfer rolls) 105a to 105d, and image carrier cleaning devices 104a to 104d are arranged. Note that a static eliminator may be provided in order to remove residual potential remaining on the surfaces of the image carriers 101a to 101d after transfer.

  The intermediate transfer belt 107 is supported while applying tension by the support rolls 106a to 106d, the driving roll 111, and the opposing roll 108, thereby forming an intermediate transfer belt unit 107b. With the support rolls 106a to 106d, the driving roll 111, and the opposing roll 108, the intermediate transfer belt 107 is in contact with the surfaces of the image carriers 101a to 101d, and the image carriers 101a to 101d and the primary transfer rollers 105a to 105d. Can be moved in the direction of arrow A. A portion where the primary transfer rolls 105a to 105d come into contact with the image carriers 101a to 101d via the intermediate transfer belt 107 is a primary transfer portion, and a primary contact portion between the image carriers 101a to 101d and the primary transfer rollers 105a to 105d is a primary transfer portion. A transfer voltage is applied.

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

  In the multi-color image forming apparatus 100 having this configuration, the image carrier 101a rotates in the direction of arrow C, and after the surface is charged by the charging device 102a, the first color is exposed by the exposure device 114a such as laser light. An electrostatic latent image is formed. The formed electrostatic latent image is developed (developed) with a developer containing toner by a developing device 103a containing toner corresponding to the color to form a toner image. The developing devices 103a to 103d contain toners (for example, yellow, magenta, cyan, and black) corresponding to the electrostatic latent images of the respective colors.

  The toner image formed on the image carrier 101a is electrostatically transferred (primary transfer) onto the intermediate transfer belt 107 by the primary transfer roll 105a when passing through the primary transfer portion. Thereafter, the toner images of the second color, the third color, and the fourth color are primarily transferred onto the intermediate transfer belt 107 holding the toner image of the first color by the primary transfer rolls 105b to 105d so that the toner images of the second color, the third color, and the fourth color are sequentially superimposed. Finally, a multi-colored multiple toner image is obtained.

  The multiple toner images formed on the intermediate transfer belt 107 are electrostatically collectively transferred to the recording medium 115 when passing through the secondary transfer portion. The recording medium 115 onto which the toner image has been transferred is conveyed to the fixing device 110, fixed by heating and pressing, or heating or pressing, and then discharged outside the apparatus.

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

-Image carrier-
As the image carriers 101a to 101d, known electrophotographic photoreceptors are widely applied. As the electrophotographic photoreceptor, an inorganic photoreceptor having a photosensitive layer made of an inorganic material, an organic photoreceptor having a photosensitive layer made of an organic material, or the like is used. In organic photoconductors, a function-separated type organic photoconductor that stacks a charge generation layer that generates charge upon exposure and a charge transport layer that transports charge, or a single layer that performs the function of generating charge and the function of transporting charge Type organic photoreceptors are preferably used. In addition, as the inorganic photoconductor, a photoconductive layer composed of amorphous silicon is preferably used.

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

-Charging device-
The charging devices 102a to 102d are not particularly limited, and are, for example, conductive (here, “conductive” in the charging device means, for example, a volume resistivity of less than 10 ⁷ Ωcm) or semiconductive (here. In the charging device, “semiconductive” means, for example, a contact charger using a roller, brush, film, rubber blade or the like having a volume resistivity of 10 ⁷ Ωcm or more and 10 ¹³ Ωcm or less. Known chargers such as scorotron chargers and corotron chargers using discharge are widely applied. Among these, a contact charger is preferable.

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

-Exposure device-
There are no particular limitations on the exposure apparatuses 114a to 114d, and for example, a light source such as a semiconductor laser light, an LED (Light Emitting Diode) light, or a liquid crystal shutter light on the surfaces of the image carriers 101a to 101d, or these A well-known exposure apparatus such as an optical system apparatus capable of performing imagewise exposure from a light source via a polygon mirror is widely applied.

-Developer-
The developing devices 103a to 103d are selected according to the purpose. For example, a known developing device that develops a one-component developer or a two-component developer in a contact or non-contact manner using a brush or a roller can be used.

-Primary transfer roll-
The primary transfer rolls 105a to 105d may be either a single layer or a multilayer. For example, in the case of a single layer structure, it is composed of a roll in which an appropriate amount of conductive particles such as carbon black is blended in foamed or non-foamed silicone rubber, urethane rubber, EPDM, or the like.

-Image carrier cleaning device-
The image carrier cleaning devices 104a to 104d are for removing residual toner adhering to the surfaces of the image carriers 101a to 101d after the primary transfer process. In addition to the cleaning blade, brush cleaning or roll cleaning is performed. Used. Among these, it is desirable to use a cleaning blade. Examples of the material for the cleaning blade include urethane rubber, neoprene rubber, and silicone rubber.

-Secondary transfer roll-
The layer structure of the secondary transfer roll 109 is not particularly limited. For example, in the case of a three-layer structure, the layer structure includes a core layer, an intermediate layer, and a coating layer that covers the surface. The core layer is a foamed material such as silicone rubber, urethane rubber, or EPDM in which conductive particles are dispersed, and the intermediate layer is composed of these non-foamed materials. Examples of the material for the coating layer include tetrafluoroethylene-hexafluoropropylene copolymer or perfluoroalkoxy resin. The volume resistivity of the secondary transfer roll 109 is desirably 10 ⁷ Ωcm or less. Moreover, it is good also as a two-layer structure except an intermediate | middle layer.

-Opposite roll-
The counter roll 108 forms a counter electrode of the secondary transfer roll 109. The layer structure of the facing roll 108 may be either a single layer or a multilayer. For example, in the case of a single layer structure, it is composed of a roll in which an appropriate amount of conductive particles such as carbon black is blended in silicone rubber, urethane rubber, EPDM, or the like. In the case of a two-layer structure, it is composed of a roll in which the outer peripheral surface of the elastic layer made of the rubber material is covered with a high resistance layer.

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

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

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

Next, an image forming apparatus using the transfer belt of this embodiment as a recording medium conveyance body (paper conveyance belt) will be described.
FIG. 2 is a schematic configuration diagram illustrating another example of the image forming apparatus according to the present embodiment. The image forming apparatus shown in FIG. 2 is an image forming apparatus in which the transfer belt according to the present embodiment is applied to a recording medium conveyance body.

  In the image forming apparatus shown in FIG. 2, the units Y, M, C, and BK are provided with photosensitive drums 201Y, 201M, 201C, and 201BK, respectively, so as to rotate in the clockwise direction indicated by arrows. Around the photosensitive drums 201Y, 201M, 201C, and 201BK, there are chargers 202Y, 202M, 202C, and 202BK, exposure units 203Y, 203M, 203C, and 203BK, and each color developing device (yellow developing device 204Y, magenta developing device 204M). , Cyan developing device 204C, black developing device 204BK) and photosensitive drum cleaning members 205Y, 205M, 205C, and 205BK, respectively.

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

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

  The transfer rolls 207Y, 207M, 207C, and 207BK are disposed inside the paper transport belt 206 and at positions facing the portions where the paper transport belt 206 is in contact with the photosensitive drums 201Y, 201M, 201C, and 201BK, respectively. The transfer areas for transferring the toner image onto the sheet (transfer body) 216 via the photosensitive drums 201Y, 201M, 201C, 201BK and the sheet conveying belt 206 are formed. As shown in FIG. 2, the transfer rolls 207Y, 207M, 207C, and 207BK may be arranged immediately below the photosensitive drums 201Y, 201M, 201C, and 201BK, or may be arranged at positions shifted from the positions immediately below.

  The fixing device 209 is disposed so as to be conveyed after passing through respective transfer regions of the paper conveyance belt 206 and the photosensitive drums 201Y, 201M, 201C, and 201BK.

  The paper 216 is transported to the paper transport belt 206 by the paper transport roll 208.

  In the image forming apparatus shown in FIG. 2, in the unit BK, the photosensitive drum 201BK is rotationally driven. In conjunction with this, the charger 202BK is driven to charge the surface of the photosensitive drum 201BK to a desired polarity and potential. Next, the photosensitive drum 201BK whose surface is charged is exposed imagewise by the exposure device 203BK, and an electrostatic latent image is formed on the surface.

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

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

  Thereafter, the toner remaining on the photosensitive drum 201BK is cleaned and removed by the photosensitive drum cleaning member 205BK. The photosensitive drum 201BK is used for the next image transfer.

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

The paper 216 onto which the toner image has been transferred by the transfer rolls 207BK, 207C, 207M, and 207Y is further conveyed to the fixing device 209 and fixed.
Thus, a target image is formed on the paper.

<Transfer belt unit>
Examples of the transfer belt unit according to the present embodiment include a transfer belt according to the present embodiment and a plurality of rolls that span the transfer belt in a tensioned state.

  As the transfer belt unit of the present embodiment, for example, a state where tension is applied between the transfer belt and the transfer belt, such as the intermediate transfer belt unit 107b shown in FIG. 1 and the sheet conveying belt unit 220 shown in FIG. And a plurality of rolls to be hung around.

For example, the transfer belt unit shown in FIG. 3 may be used as an example of the transfer belt unit according to the present embodiment.
FIG. 3 is a schematic perspective view showing the transfer belt unit according to the present embodiment.
As shown in FIG. 3, the transfer belt unit 130 according to the present embodiment includes the transfer belt 30 according to the present embodiment. For example, the transfer belt 30 includes a driving roll 131 and a driven roll that are arranged to face each other. It is stretched by 132 in the state where tension was applied.
Here, when the transfer belt 30 is applied as an intermediate transfer member, the transfer belt unit 130 according to the present embodiment uses the transfer belt 30 to transfer the toner image on the surface of the photosensitive member (image holding member) as a roll that supports the transfer belt 30. A roll for primary transfer and a roll for secondary transfer of the toner image transferred onto the transfer belt 30 to the recording medium may be disposed.
The number of rolls that support the transfer belt 30 is not limited, and may be arranged according to the usage mode. The transfer belt unit 130 having the above configuration is used by being incorporated in the apparatus, and rotates while the transfer belt 30 is also supported as the drive roll 131 and the driven roll 132 rotate.

  Examples will be described below, but the present invention is not limited to these examples. In the following description, “part” and “%” are all based on mass unless otherwise specified.

<Example 1>
(Manufacture of transfer belt)
The solid content concentration after imidization by reacting 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 4,4′-diaminodiphenyl ether in N-methylpyrrolidone (NMP) was 18% by mass. A polyamic acid solution was prepared. 80 parts by mass of carbon black (manufactured by Orion Engineered Carbons, trade name: Special Black 4) is added to 100 parts by weight of the resulting polyamic acid solution, and a jet mill disperser (manufactured by Geanus, trade name: Geanus PY). The dispersion unit A was obtained by using a minimum cross-sectional area of 0.032 mm ² ) at a collision part and passing the dispersion unit part 5 times at a pressure of 200 MPa to perform dispersion / mixing. To the obtained dispersion A, the previously prepared polyamic acid solution was added so that the carbon black was 26 parts by mass relative to the polyamic acid solid content, and a planetary mixer (manufactured by Aikosha Seisakusho, trade name: The mixture was stirred and mixed using an Aiko mixer to obtain a polyamic acid solution for inner layer (polyimide precursor composition A1).
Next, 1,3-dimethyl-2-imidazolidinone (DMI) was used as a solvent for reacting 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 4,4′-diaminodiphenyl ether. A dispersion was obtained in the same procedure as described above except that it was used to obtain a polyamic acid solution for outer layer (polyimide precursor composition B1).
Next, the polyamic acid solution for the inner layer is injected into the outer peripheral surface of the cylindrical substrate, and after forming the coating film while rotating the cylinder around the axis at 50 rpm, the coating film is dried at 145 ° C. for 18 minutes. Thus, a dry film 1 having a thickness of 70 μm was formed.
Next, in the same manner as the production of the dry film 1, the outer layer polyamic acid solution was applied on the dry film 1 while rotating the centrifugal mold around the axis at 50 rpm to form a paint film. Was dried by heating at 145 ° C. for 18 minutes to form a dry film 2 having a thickness of 30 μm. Thereby, the cylindrical molded object which laminated | stacked the dry film 2 on the dry film 1 was obtained.
Next, this cylindrical molded body was heated at 200 ° C. for 30 minutes, 260 ° C. for 30 minutes, 300 ° C. for 30 minutes, and 320 ° C. for 20 minutes to form a polyimide resin film (PI resin film). Thereafter, when the temperature of the cylindrical molded body was cooled to room temperature (30 ° C.), the PI resin film was peeled off from the centrifugal mold, and the central portion of the PI resin film was cut into a width of 369 mm. As a result, a transfer belt in which the second resin layer (outer layer) was laminated on the first resin layer (inner layer) was obtained.

<Examples 2-6, Comparative Examples 1-3>
In Example 1, the components and solvent types in the inner layer polyamic acid solution, the components and solvent types in the outer layer polyamic acid solution were changed as shown in Table 1, and the film thickness (outer layer / inner layer) was Examples 2 to 6 and Comparative Example in the same procedure as Example 1 except that the injection amount (coating amount) of the inner layer polyamic acid solution and the outer layer polyamic acid solution was changed to the thickness shown in FIG. 1 to 3 transfer belts were obtained.

  The following measurement and evaluation were performed using the transfer belt obtained in each example.

(Measurement of average film thickness of first resin layer and second resin layer)
The first resin layer and the second resin layer were sampled from the transfer belt obtained in each example, and the average film thicknesses of the first resin layer and the second resin layer were measured by the method described above. . The results are shown in Table 1. In addition, the film thickness in Table 1 represents “average film thickness”.

(Measurement of Young's modulus)
The Young's modulus was a value measured by a tensile test based on JIS K7127. Specifically, the first resin layer and the second resin layer were cut out from the transfer belt to be measured to prepare test pieces (5 mm × 40 mm). Using this test piece, Young's modulus of each layer was measured 10 times, and the average value was used as measurement data. The measuring machine used was a tensile tester MODEL-1605N manufactured by Aiko Engineering Co., Ltd., and the measurement conditions were 22 ° C. and 55% RH environment, and the tensile speed was 20 mm / min. The results are shown in Table 1.

[Evaluation]
<Cleanability>
The transfer belt obtained in each example was incorporated into a full-color printer (DocuPrint C5450) manufactured by Fuji Xerox as an intermediate transfer member, and C2 paper A4 paper manufactured by Fuji Xerox was used in a low temperature and low humidity (10 ° C, 15% RH) environment. Used, 20,000 comprehensive patterns with letters and patches were output.
The evaluation of the cleaning property is to determine whether or not streaks due to poor cleaning have occurred in the output paper, and whether or not external additives etc. are stuck in the scratched surface of the belt after the output (external additive) And the like) was observed with a scanning electron microscope (SEM). The evaluation criteria are shown below.
-Evaluation criteria-
G1 (◯): no streaking occurs and no external additive or the like is attached.
G2 (x): streaks are generated, and adhesion (intrusion) of an external additive or the like is observed on the belt surface from SEM observation.

<Flexibility>
Using a MIT testing machine (manufactured by Ueshima Seisakusho Co., Ltd .: MODEL FT-701), the number of folds to break at a sample width of 15 mm and a tensile load of 1 kg was measured in accordance with JIS-P8115 (2001).
Specifically, the transfer belt obtained in each example was cut into a strip-like sample having a width of 15 mm and a length of 200 mm in the circumferential direction, both ends were fixed and a tensile tension of 1 kgf was applied, and a terminal having a curvature shape of R 0.38 mm Was repeatedly bent (bent) in the left and right directions by 90 °. At this time, the number of folding times until the sample broke was measured, and the bending resistance was evaluated based on the number of folding times. “Breaking” means a state in which the belt is cut in the entire width direction.
In addition, the measurement was performed in a normal temperature and normal humidity (22 ° C., 45% RH) environment. The evaluation criteria are shown below. If it is G3 or more, it is within a practically acceptable range.
G1 (◎): No break even after exceeding 3000 times G2 (◯): Break at 1500 times or more and 2999 times or less G3 (△): Break at 500 times or more and 1499 times or less G4 (x): Break at 499 times or less

<Dimensional stability>
The transfer belt obtained in each example is supported by two parallel rollers while applying tension from the inside of the transfer belt, and a tension F (F = 19.6 N) is applied to the transfer belt. State. In this state, a laser displacement meter (LK-030 manufactured by Keyence Corporation) is scanned in the belt width direction over the entire width of the transfer belt at the center position of the two rolls.
Thereby, the distance between the outer peripheral surface of the belt and the laser displacement meter is measured, and the unevenness amount of the transfer belt in the belt width direction is obtained. This measurement is performed at eight locations in the circumferential direction of the transfer belt (positions separated by 45 ° in the circumferential direction). Then, the difference Δh between the maximum value Max and the minimum value Min of the obtained unevenness amount was calculated as flatness (mm), and dimensional stability was evaluated based on the flatness.
G1 (◯): Maximum unevenness Δh including end portion is 1.2 mm or less G2 (×): Maximum unevenness Δh including end exceeds 1.2 mm

Abbreviations in Table 1 are as follows.
BPDA: 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride ODA: 4,4′-diaminodiphenyl ether PPD: p-phenylenediamine DMI: 1,3-dimethyl-2-imidazolidi Non-NMP: N-methylpyrrolidone

As shown in Table 1, in each example in which the first resin layer includes the solvent A1 and the second resin layer includes the solvent B1, the first resin layer includes the solvent B1 and the second resin layer includes It can be seen that Comparative Example 1 containing the solvent A1 and the first resin layer and the second resin layer both have superior cleaning properties compared to the Comparative Example 3 containing the solvent A1. Moreover, it turns out that each Example has the bending resistance improved compared with the comparative example 2 in which the resin layer which consists of a single layer contains solvent B1.
That is, in each Example, it can be seen that a transfer belt having both excellent cleaning properties and high bending resistance is obtained. Also, the resins contained in the first resin layer and the second resin layer have the same structure. It turns out that Examples 1-4, 6 which consist only of these structural units have favorable step stability compared with Example 5 in which the said resin contains a different structural unit.
Further, in Example 1 in which the second resin layer contains 1,3-dimethyl-2-imidazolidinone (DMI) as the solvent B1, Examples 2 to 4 in which the second resin layer contains a solvent B1 other than DMI. , 6, it can be seen that the bending resistance is improved.
Furthermore, Examples 1-3, 5, 6 in which the film thickness of the first resin layer is 50% or more with respect to the total thickness of the first resin layer and the second resin layer are It can be seen that the bending resistance is improved as compared with Example 4 in which the layer thickness is less than 50%.

30 transfer belt, 100 image forming apparatus, 101a to 101d image holding member, 102a to 102d charging device (charging unit), 103a to 103d, 204Y, 204M, 204C, 204BK developing device (developing unit), 104a to 104d image holding member Cleaning device, 105a to 105d Primary transfer roll, 106a to 106e Support roll, 107b, 220 Intermediate transfer belt unit, 108 Opposing roll, 109 Secondary transfer roll, 110 Fixing device (fixing means), 111 Drive roll, 112, 113 Intermediate Transfer belt cleaning device, 114a to 114d exposure device, 115 recording medium, 116 secondary transfer belt, 130 transfer belt unit, 131 driving roll, 132 driven roll, 201Y, 201M, 201C, 201BK photosensitive Drum (image holder), 202Y, 202M202C, 202BK Charger (charging means), 203Y, 203M, 203C, 203BK Exposure unit (latent image forming means), 205Y, 205M, 205C, 205BK Photosensitive drum cleaning member, 206 Paper Transport belt, 207Y, 207M, 207C, 207BK Transfer roll (transfer means), 208 Paper transport roll, 209 Fixing device, 210 Belt support roll, 212 Belt support roll, 214 Belt cleaning member, 216 Paper (recording medium)

Claims (8)

At least one resin A selected from the group consisting of polyimide and polyamideimide, and N-methylpyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, N, N-diethylacetamide and γ-butyrolactone A first resin layer containing at least one solvent A1 selected from the solvent group A,
At least one resin B selected from the group consisting of polyimide and polyamideimide, and a urea solvent, an alkoxy group-containing amide solvent, and an ester group-containing amide solvent, disposed on the outer peripheral surface of the first resin layer A second resin layer containing at least one solvent B1 selected from the solvent group B consisting of:
Having a transfer belt.   2. The transfer according to claim 1, wherein at least one of the resins A contained in the first resin layer and at least one of the resins B contained in the second resin layer are composed only of structural units having the same structure. belt.   The solvent B1 is tetramethylurea, tetraethylurea, 1,3-dimethyl-2-imidazolidinone, N, N-dimethylpropyleneurea, 3-methoxy-N, N-dimethylpropanamide, and 3-nbutoxy- The transfer belt according to claim 1 or 2, wherein the transfer belt is at least one solvent selected from the group consisting of N, N-dimethylpropanamide.   The transfer belt according to any one of claims 1 to 3, wherein the solvent B1 is 1,3-dimethyl-2-imidazolidinone.   The average film thickness of the first resin layer is 50% or more with respect to the sum of the average film thicknesses of the first resin layer and the second resin layer. The transfer belt according to item 1. The transfer belt according to any one of claims 1 to 5,
A plurality of rolls over which the transfer belt is tensioned;
And a transfer belt unit that is detachably attached to the image forming apparatus. An image carrier,
Charging means for charging the surface of the image carrier;
An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged image carrier;
Developing means for developing an electrostatic latent image on the surface of the image carrier with toner to form a toner image;
The transfer belt according to any one of claims 1 to 5,
Primary transfer means for primarily transferring the toner image formed on the surface of the image carrier onto the outer peripheral surface of the transfer belt;
Secondary transfer means for secondary transfer of the toner image primarily transferred to the outer peripheral surface of the transfer belt to a recording medium;
Fixing means for fixing the toner image secondarily transferred to the recording medium;
Cleaning means for cleaning the outer peripheral surface of the transfer belt;
An image forming apparatus. At least one selected from the group consisting of polyimide precursors, polyamideimide precursors and polyamideimide resins, and N-methylpyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, N, N-diethylacetamide And a step of curing a composition containing at least one solvent A1 selected from solvent group A consisting of γ-butyrolactone to form a first resin layer;
At least one selected from the group consisting of a polyimide precursor, a polyamideimide precursor and a polyamideimide resin, and a solvent group B consisting of a urea solvent, an alkoxy group-containing amide solvent and an ester group-containing amide solvent. Curing the composition containing at least one solvent B1 to form a second resin layer on the outer peripheral surface of the first resin layer;
A method of manufacturing a transfer belt having