JP5446655B2 - Polyimide polymer composition, polyimide endless belt, method for producing polyimide endless belt, belt unit, and image forming apparatus - Google Patents

Description

  The present invention relates to a polyimide polymer composition, a polyimide endless belt, a method for producing a polyimide endless belt, a belt unit, and an image forming apparatus.

  An image forming apparatus using an electrophotographic method forms an electrostatic latent image with a laser beam or the like that modulates an image signal by forming an electric charge on an image carrier that is a photosensitive member containing an inorganic or organic material. Thereafter, the electrostatic latent image is developed with charged toner to obtain a visualized toner image. The toner image is electrostatically transferred to a recording medium such as a recording sheet through an intermediate transfer member or directly to obtain a required reproduced image.

  Examples of materials used in the image forming apparatus employing the intermediate transfer method include polycarbonate resin (see, for example, Patent Document 1), polyvinylidene fluoride (see, for example, Patent Documents 2 and 3), and polyalkylene phthalate (for example, Patent Document). 4), blend material of PC (polycarbonate) / PAT (polyalkylene terephthalate) (for example, see Patent Document 5), blend material of ETFE (ethylene tetrafluoroethylene copolymer) / PC, ETFE / PAT, PC / PAT A proposal has been made to use an endless belt whose main component is (see, for example, Patent Document 6).

  As other belt materials, elastic belts with a reinforcing material formed by laminating a woven fabric such as special polyester and an elastic member have been proposed (see, for example, Patent Documents 7 and 8).

  In addition, in an image forming apparatus for electrostatically transferring directly to a recording medium such as recording paper, a transfer material centering on a tandem color image forming apparatus in which a plurality of photosensitive members each having a developing device for each color are arranged. A transfer / conveying belt system that adsorbs and conveys the toner onto an endless belt has been proposed and has already been put into practical use.

  On the other hand, as a belt that can be used for an intermediate transfer belt, a transfer conveyance belt, or the like whose strength is insufficient, deformed, or durable, a transfer belt in which a filler is dispersed in a polyimide resin has been proposed (for example, Patent Documents 9 to 11). reference). An endless belt made of polyimide resin can be said to have extremely excellent characteristics as a transfer belt compared to other materials because of its mechanical strength, high elastic modulus, creep resistance, and the like.

  On the other hand, it has been proposed to modify the acid polymer terminal to a nylon salt type (see, for example, Patent Documents 12 and 13). In addition, it has been proposed to improve the dispersibility of carbon black by using a low molecular weight polyamic acid (see, for example, Patent Document 14).

JP-A-6-095521 Japanese Patent Laid-Open No. 5-200904 JP-A-6-228335 Japanese Patent Laid-Open No. 6-149081 Japanese Patent Laid-Open No. 6-149083 Japanese Patent Laid-Open No. 6-149079 Japanese Patent Laid-Open No. 9-305038 Japanese Patent Laid-Open No. 10-240020 JP-A-5-77252 Japanese Patent Laid-Open No. 10-63115 JP 2001-34076 A JP 2005-247987 A Japanese Patent Laying-Open No. 2005-247988 JP 2002-308995 A

  By the way, for example, when manufacturing a polyimide molded body, since a polyimide resin generally does not melt and is insoluble in various solvents, a polyamic acid solution, which is a precursor, is applied to a substrate and heated after drying. Then, a dehydration imidization reaction of an amic acid group is performed to obtain a polyimide molded body. The imidization reaction is generally performed at a high temperature of 300 ° C to 400 ° C. For example, when the polyimide molded body is a belt and the dehydration imidization reaction of polyamic acid proceeds rapidly, voids may be generated in the film of the belt, and due to the stress generated by volume shrinkage accompanying the dehydration reaction There may be variations in quality in the direction of the belt thickness and in the plane.

  The purpose of the present invention is to be soluble in a solvent compared to a polyimide resin not having the structure of the present application, and compared to molding using a polyamic acid which is a polyimide resin precursor, Polyimide molded body can be obtained simply by drying the solvent after coating the molecular composition on the substrate, and the obtained polyimide molded body has a predetermined mechanical strength and the quality variation is suppressed. System polymer composition.

  As a result of intensive studies to solve the above problems, the present inventors have completed the present invention shown below. The present invention has the following features.

The invention according to claim 1
Carbon black having a pH of less than 7 is dispersed in a solution containing a polyimide polymer having the structure of the general formula (1) shown below and a solvent, with respect to the diamine compound in the polymerization reaction to obtain the general formula (1) shown below. The molar ratio of tetracarboxylic dianhydride (α = (number of equivalents of tetracarboxylic dianhydride) / (number of equivalents of diamine compound)) is 0.90 or more and less than 1.00. It is.

... General formula (1)
(In general formula (1), R1 and R3 represent a tetravalent organic group. R2, R4 and R5 represent a divalent organic group. M and n represent an integer of 1 or more, and m / (m + n). ≧ 0.5.)

The invention according to claim 2
R1 and R3 in the general formula (1) are selected from the following:

R2, R4 and R5 in the general formula (1) are selected from the following:

The polyimide polymer composition according to claim 1, further comprising 50 mol% or more of a polyimide polymer having a selected structure of R1, R2, R2, R4, and R5.

The invention according to claim 3
In the structure represented by the general formula (1), 1,3,3a, 4,5,9b-hexahydro-5 (tetrahydro-2,5-dioxo-3-furanyl) naphtho [1,2-c] furan- The polyimide-based polymer composition according to claim 1 or 2, further comprising a third component selected from the group consisting of 1,3-dione and ethylene glycol bisanhydro trimellitate.

The invention according to claim 4
The process of apply | coating the polyimide-type polymer composition as described in any one of the said Claim 1 to 3 to the surface of a cylindrical base material, The polyimide-type polymer composition apply | coated on the said cylindrical metal mold | die A process for heat-treating a product, and a method for producing a polyimide endless belt.

The invention according to claim 5
A polyimide endless belt for transfer or fixing obtained by heat-treating the polyimide polymer composition according to any one of claims 1 to 3.

The invention according to claim 6
A transfer or fixing polyimide endless belt manufactured by the manufacturing process according to claim 4.

The invention according to claim 7 provides:
A belt unit comprising the polyimide endless belt according to claim 5.

The invention according to claim 8 provides:
A latent image forming unit that forms a latent image on the latent image carrier, a developing unit that develops the latent image using a developer for developing an electrostatic image, and a developed toner image via an intermediate transfer member or An image forming apparatus comprising: a transfer unit that transfers onto a transfer medium without intervention; and a fixing unit that fixes a toner image on the transfer target; and a transfer belt used for the transfer unit and the fixing unit The image forming apparatus according to claim 5 or 6, wherein at least one of the fixing belts is a polyimide endless belt.

  According to invention of Claim 1, compared with the case where it does not have this structure, the polyimide-type polymer composition with the high dispersibility of carbon black below pH 7 is provided.

  According to the second aspect of the present invention, a polyimide polymer having a high dispersibility of carbon black having a pH of less than 7 and a mechanical strength higher than that of a general polyimide polymer, as compared with the case without this configuration. A composition is provided.

  According to the third aspect of the present invention, there is provided a polyimide-based polymer composition in which the degree of rigidity is adjusted as compared with the case where this configuration is not provided.

  According to invention of Claim 4, compared with the shaping | molding using the polyamic acid which is a precursor of a polyimide resin, the solvent is dried after coating the base material with the polyimide-type polymer composition dissolved in the solvent. A polyimide endless belt can be obtained only by this.

  According to invention of Claim 5, compared with the case where it does not have this structure, the abrasion-proof polyimide endless belt with which the dispersion | variation in quality was suppressed is provided.

  According to the sixth aspect of the present invention, there is provided a polyimide endless belt having high wear resistance and reduced quality variation compared to the case without this configuration.

  According to the seventh aspect of the present invention, there is provided a belt unit that, when used in an image forming apparatus, can obtain high image quality over a long period of time as compared with the case where the present configuration is not provided.

  According to the eighth aspect of the present invention, there is provided an image forming apparatus capable of obtaining high image quality over a long period of time as compared with the case where this configuration is not provided.

It is a figure for demonstrating the measuring method of surface resistivity and volume resistivity. 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 the other example of the image forming apparatus of this embodiment.

  A polyimide polymer composition, a polyimide endless belt, a method for producing a polyimide endless belt, a belt unit, and an image forming apparatus according to embodiments of the present invention will be described below.

<Polyimide polymer composition>
In the polyimide-based polymer composition of the present embodiment, carbon black having a pH of less than 7 (hereinafter sometimes referred to as “acidic carbon black”) has a structure represented by the following general formula (1) and has molecular ends at the molecular ends. It is dispersed in a solution containing an amino group-containing polyimide polymer (hereinafter sometimes referred to as “specific polyimide”) and a solvent. The polyimide polymer having an amino group at the molecular terminal represented by the general formula (1) shown below has an amino group at the molecular terminal, so that the polyimide polymer is particularly affected by the interaction between the amino group and acidic carbon black. Dispersibility of acidic carbon black in the composition is high.

... General formula (1)

  In general formula (1), R1 and R3 represent a tetravalent organic group. R2, R4, and R5 represent a divalent organic group. m and n are integers of 1 or more (preferably integers of 1 to 1000), and m / (m + n) is 0.5 to 0.9.

  Furthermore, m / (m + n) is more preferably 0.6 or more and 0.8 or less. In the general formula (1), when m / (m + n) is less than 0.5, there is a problem that high-temperature and long-time heat treatment is required to develop strength, while m / (m + n) is 0. If it exceeds .9, there is a problem that it becomes insoluble in the solvent.

[Measurement method of m / (m + n)]
The polyamic acid varnish was diluted with N-methylpyrrolidone to a solid content of 1% by mass. The diluted solution was applied on the silicone wafer substrate under the following conditions.
Application method: Spin coating method,
Coating conditions: 100 rpm × 10 seconds + 3000 rpm × 30 seconds After the coating film was formed, the sample piece was immersed in tetrahydrofuran for 30 minutes.

The sample piece was dried under 10 mmHg for 12 hours, and the infrared absorption spectrum was measured. Absorbance of 1500 cm ^-1 derived from an aromatic ring (A (phenyl)) as an internal standard, the absorbance derived from an imide group carbonyl near 1780 cm ^-1 (A (imide)) ratio of P (sample) = A (imide) / A (phenyl) was calculated.

Separately, a fully imidized sample obtained by treating a sample formed by the same method at 400 ° C. for 1 hour was prepared, and an infrared absorption spectrum was measured in the same manner.
P (completely imidized sample) = A (imide) / A (phenyl) was determined.

Furthermore, m / (m + n) was calculated by the following formula.
Imidization rate = P (specimen) / P (completely imidized sample)
m / (m + n) = 1-imidization rate

  The “polyimide polymer” (also referred to as “specific polyimide”) in the present embodiment refers to a soluble polyimide that dissolves at a solid content concentration of 20 mass% when N-methylpyrrolidone is used as a solvent.

(Polyimide polymer)
First, the specific polyimide will be described.

In the specific imide in the present embodiment, R1 and R3 in the general formula (1) are further selected from the following:

R2, R4 and R5 in the general formula (1) are selected from the following:

And the polyimide polymer which has the structure of selected R1, R2, R2, R4, R5 contains 50 mol% or more.

  In General formula (1), R1 and R3 represent a tetravalent organic group. Examples of the tetravalent organic group include a group having a residue structure obtained by removing four carboxyl groups from a tetracarboxylic acid compound, and a group having the above structure is preferable.

Here, the group having the structure of R1 and R3 in the general formula (1) is a residue structure obtained by removing four carboxyl groups from the tetracarboxylic acid compound shown below.

  R2, R4 and R5 in the general formula (1) represent a divalent organic group. Examples of the divalent organic group include a group having a residue structure obtained by removing two amino groups from a diamine acid compound, and a group having the above structure is preferable.

  The specific polyimide uses a tetracarboxylic dianhydride and a diamine compound, and an excess of the diamine compound compared to the tetracarboxylic dianhydride so that the polymer terminal of the polyimide polymer is an amino group, and an organic polar solvent A polyamic acid is produced by polymerization reaction in the resin, and the polyamic acid is used. Therefore, at the time of polymerization of the polyimide polymer in the present embodiment, the number of equivalents of the diamine compound involved in the polymerization reaction is set higher than the number of equivalents of tetracarboxylic dianhydride.

  In such a polymerization reaction, the molar ratio of tetracarboxylic dianhydride to diamine compound (α = (number of equivalents of tetracarboxylic dianhydride) / (number of equivalents of diamine compound)) is 0.85 or more and 0.999 or less. A range is preferable, and a range of 0.95 to 0.985 is more preferable.

  When the molar ratio is less than 0.90, the molecular weight of the resin becomes small. For example, when the polyamic acid in the present embodiment is a polyimide endless belt, the mechanical performance may be low. If it exceeds 99, the interaction of acidic carbon black may be reduced.

  Further, at the time of producing the polyamic acid in the present embodiment, 1,3,3a, 4,5,9b-hexahydro-5 (tetrahydro-2,5-dioxo-3) is contained in the structure represented by the general formula (1). -Furanyl) naphtho [1,2-c] furan-1,3-dione and a third component selected from the group consisting of ethylene glycol bisanhydro trimellitate may be further contained. By containing the third component, the degree of rigidity of the polyimide polymer obtained after the dehydration imidation reaction described later is adjusted.

  The polyamic acid obtained as described above is dehydrated and imidized in a solution to produce a polyimide polymer.

(Imidation reaction)
The polyimide polymer used in the present embodiment is prepared by (i) heating, or (ii) dehydrating agent and catalyst acting on the polyamic acid, and dehydrating and cyclizing a part of the amic acid group in the polyamic acid. To obtain an imide group.

  The heating temperature in the imidization reaction by heating is usually 60 ° C. to 250 ° C., preferably 100 ° C. to 200 ° C. When the heating temperature is less than 60 ° C., dehydration ring closure does not proceed sufficiently, and when the heating temperature exceeds 200 ° C., the resulting polymer has a low molecular weight.

  On the other hand, in the imidization reaction by adding a dehydrating agent and a catalyst to the polyamic acid solution, the dehydrating agent is not particularly limited as long as it is a monovalent carboxylic acid anhydride. For example, acetic anhydride, propionic anhydride, anhydrous An acid anhydride such as trifluoroacetic acid is used. The amount of the dehydrating agent used is preferably 0.01 to 3 equivalents per mole of the polyamic acid repeating unit.

  As the catalyst, for example, tertiary amines such as pyridine, collidine, lutidine, and triethylamine can be used, but the catalyst is not limited thereto. The amount of the catalyst used is preferably 0.01 to 5 equivalents per 1 mol of the polyamic acid repeating unit.

  Dehydration ring closure is performed by adding a dehydrating agent and a cyclization catalyst to the polyamic acid solution and heating as necessary. The reaction temperature for dehydration ring closure is usually 0 ° C. to 180 ° C., preferably 60 ° C. to 150 ° C.

  The polyimide polymer used in the polyimide endless belt in the present embodiment has an imidization ratio defined by the molar fraction of the imide group in the amic acid group and the imide group in the molecular structure from 50% to 100%. It is preferable that This is because if the imidization rate is less than 50%, the imidization reaction does not proceed sufficiently in the firing step during belt production, and the belt becomes brittle.

  As a method for removing the acted dehydrating agent and catalyst from the polyimide solution or polyimide-polyamic acid copolymer solution imidized with the catalyst and the dehydrating agent, distillation by distillation under reduced pressure or reprecipitation method is used. The reduced-pressure heating is performed under vacuum at a temperature of 80 ° C. to 120 ° C., and the tertiary amine, unreacted dehydrating agent and hydrolyzed carboxylic acid used as a catalyst are distilled off.

  In the reprecipitation method, the tertiary amine used as a catalyst, the unreacted dehydrating agent and the hydrolyzed carboxylic acid are dissolved, and the partially imidized polyamic acid is not dissolved in a large excess in a poor solvent. This is done by adding the reaction solution. The poor solvent is not particularly limited, and water, alcohol solvents such as methanol and ethanol, ketone solvents such as acetone and methyl ethyl ketone, hydrocarbon solvents such as hexane, and the like are used. The precipitated polyimide polymer or polyimide-polyamic acid copolymer is filtered and dried, and then dissolved again in a solvent such as NMP.

[Tetracarboxylic dianhydride]
There is no restriction | limiting in particular as tetracarboxylic dianhydride used for manufacture of a specific polyimide, You may use any compound of an aromatic type and an aliphatic type. However, the tetracarboxylic dianhydride used for the polyimide polymer having a specific structure contained in an amount of 50 mol% or more is a tetracarboxylic acid having a structure in which R1 and R3 in the general formula (1) are selected from any of the above. Acid dianhydride.

  Examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride, 3,4,3 ′, 4′-benzoenone tetracarboxylic dianhydride, 3,3 ′, 4,4. '-Biphenylsulfonetetracarboxylic dianhydride, 2,3,3', 4'-biphenyltetracarboxylic dianhydride, 2,3,2 ', 3'-biphenyltetracarboxylic dianhydride, oxydiphthalic acid Anhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyl ether tetracarboxylic acid Dianhydride, 3,3 ′, 4,4′-dimethyldiphenylsilanetetracarboxylic dianhydride, 3,3 ′, 4,4′-tetraphenylsilanetetracarboxylic dianhydride, 1,2,3 4-Franteto Carboxylic dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenyl sulfide dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylsulfone dianhydride, 4, 4′-bis (3,4-dicarboxyphenoxy) diphenylpropane dianhydride, 3,3 ′, 4,4′-perfluoroisopropylidenediphthalic 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, Examples thereof include bis (triphenylphthalic 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 acid, 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-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride Aliphatic or cycloaliphatic tetracarboxylic dianhydrides such as bicyclo [2,2,2] -oct-7-ene-2,3,5,6-tetracarboxylic dianhydride; , , 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, 4,5,9b-hexahydro-8- Examples include aliphatic tetracarboxylic dianhydrides having an aromatic ring such as methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione. It is done.

  The tetracarboxylic dianhydride is preferably an aromatic tetracarboxylic dianhydride, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, oxydiphthalic acid More preferred is a dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride.

  These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

[Diamine compound]
The diamine compound used for the production of the specific polyimide is not particularly limited as long as it is a diamine compound having two amino groups in the molecular structure. However, the diamine compound used for the polyimide polymer having a specific structure contained in an amount of 50 mol% or more is a diamine compound having a structure in which R2, R4, and R5 in the general formula (1) are selected from any one of the above. .

  Examples of the diamine compound include p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylethane, 4,4′-diaminodiphenyl ether, and 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′-trifluoromethylbenz Anilide, 3,5-diamino-4'-trifluoromethylbenzanilide, 3,4'-diamino Phenyl 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- Minophenoxy) 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, 4,4'-bis [4- (4-amino-2-trifluoromethyl) phenoxy] -octafluorobiphenyl, etc. An aromatic diamine having two amino groups bonded to an aromatic ring such as diaminotetraphenylthiophene and a heteroatom other than the nitrogen atom of the amino group; 1,1-metaxylylenediamine, 1, 3-propanediamine, tetramethylenediamine, pentamethylenediamine, octamethylenediamine , Nonamethylenediamine, 4,4-diaminoheptamethylenediamine, 1,4-diaminocyclohexane, isophoronediamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-methanoindanylenediethylenediamine, tricyclo [6 , 2,1,02.7] -undecylenedimethyldiamine, aliphatic diamines such as 4,4′-methylenebis (cyclohexylamine), and alicyclic diamines.

  As the diamine compound, p-phenylenediamine, 4,4'-diaminodiphenyl ether, and 2,2-bis [4- (4-aminophenoxy) phenyl] propane are preferable. These diamine compounds may be used alone or in combination of two or more.

[Combination of tetracarboxylic dianhydride and diamine compound]
As specific polyimide, Preferably, what contains aromatic tetracarboxylic dianhydride and aromatic diamine is preferable.

[solvent]
Examples of the solvent used when polymerizing the polyamic acid as the specific polyimide precursor include organic polar solvents. Specifically, sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide; N, N-dimethylformamide, N Formamide solvents such as N, N-diethylformamide; Acetamide solvents such as N, N-dimethylacetamide and N, N-diethylacetamide; Pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone Phenolic solvents such as phenol, o-, m-, or p-cresol, xylenol, halogenated phenol, catechol; ether solvents such as tetrahydrofuran, dioxane, dioxolane; alcohol solvents such as methanol, ethanol, butanol; butyl Cellosolve such as cellosolve; and hexamethylphosphoramide, γ- butyrolactone. For the polymerization of the specific polyamic acid, the organic polar solvent is preferably used alone or in combination, but aromatic hydrocarbons such as xylene and toluene may be used. The solvent used when polymerizing the specific polyamic acid is not particularly limited as long as it dissolves the polyamic acid.

  The solid content concentration at the time of polymerizing the polyamic acid which is the specific polyimide precursor is not particularly defined, but is preferably 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 30% by mass or less.

  The polymerization temperature when polymerizing the polyamic acid which is a precursor of the specific polyimide is preferably in the range of 0 ° C. or higher and 80 ° C. or lower.

(Acid carbon black)
Acidic carbon black is produced by subjecting carbon black to oxidation treatment to give a carboxyl group, a quinone group, a lactone group, a hydroxyl group or the like to the surface. This oxidation treatment is an air oxidation method in which contact is made with air in a high temperature (eg, 300 ° C. or higher and 800 ° C. or lower) atmosphere, and a reaction with nitrogen oxides or ozone at room temperature (eg, 25 ° C., the same applies hereinafter). The method is performed by air oxidation under a high temperature (for example, 300 to 800 ° C.) and then ozone oxidation under a low temperature (for example, 20 ° C. or more and 200 ° C. or less).

  Specifically, acidic carbon black is produced by, for example, a contact method. Examples of the contact method include a channel method and a gas black method. Acidic carbon black can be produced by a furnace black method using gas or oil as a raw material. Further, if necessary, after performing these treatments, a liquid phase oxidation treatment with nitric acid or the like may be performed.

  Acidic carbon black can be manufactured by a contact method, but is generally manufactured by a closed furnace method. In the furnace method, only carbon black having a high pH and a low volatile content is usually produced. However, the pH may be adjusted by performing the above-described liquid acid treatment. For this reason, carbon black obtained by manufacturing by the furnace method and adjusted to have a pH of less than 7 by a post-process treatment can also be applied.

The pH value of acidic carbon black is less than 7, but is preferably 4.4 or less, more preferably 4.0 or less.
Here, the pH of the acidic carbon black is obtained by adjusting an aqueous suspension of carbon black (1 g of carbon black is dispersed and suspended in 100 ml of pure water) and measuring with a glass electrode. In addition, the pH of the acidic carbon black is adjusted by conditions such as the treatment temperature and treatment time in the oxidation treatment step.

  For example, the content of the volatile component of the acidic carbon black is preferably 1% by mass to 25% by mass, more preferably 2% by mass to 20% by mass, and still more preferably 3.5% to 15% by mass. .

  Specific examples of the acidic carbon black include “Printex 150T” (pH 4.5, volatile content 10.0%) and “Special Black 350” (pH 3.5, volatile content 2.2) manufactured by Degussa. %), “Special Black 100” (pH 3.3, volatile content 2.2%), “Special Black 250” (pH 3.1, volatile content 2.0%), “Special Black 5” (pH 3. 0, volatile content 15.0%), "Special Black 4" (pH 3.0, volatile content 14.0%), "Special Black 4A" (pH 3.0, volatile content 14.0%), " "Special Black 550" (pH 2.8, volatile content 2.5%), "Special Black 6" (pH 2.5, volatile content 18.0%), "Color Black FW200" (pH 2.5, volatile content 20) . %), “Color Black FW2” (pH 2.5, volatile content 16.5%), “Color Black FW2V” (pH 2.5, volatile content 16.5%), “MONARCH1000” (pH 2. 5, volatile content 9.5%), “MONARCH 1300” (pH 2.5, volatile content 9.5%) manufactured by Cabot, “MONARCH 1400” (pH 2.5, volatile content 9.0%) manufactured by Cabot, “ MOGUL-L "(pH 2.5, volatile matter 5.0%)," REGAL400R "(pH 4.0, volatile matter 3.5%) and the like.

  The content of acidic carbon black is preferably 20 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the polyimide-based polymer (specific polyimide) in the soluble polyimide composition according to the present embodiment. It is more preferable that the amount is not less than 35 parts by mass.

  The dispersant used to disperse the acidic carbon black when preparing the soluble polyimide composition may be low molecular weight or high molecular weight, and any kind of dispersion selected from cationic, anionic and nonionic An agent may be used. It is preferable to use a nonionic polymer as the dispersant.

-Nonionic polymer-
Nonionic polymers include poly (N-vinyl-2-pyrrolidone), poly (N, N′-diethylacrylazide), poly (N-vinylformamide), poly (N-vinylacetamide), poly (N -Vinylphthalamide), poly (N-vinylsuccinic acid amide), poly (N-vinylurea), poly (N-vinylpiperidone), poly (N-vinylcaprolactam), poly (N-vinyloxazoline) and the like. A single or a plurality of nonionic polymers may be added. In the present embodiment, it is preferable that poly (N-vinyl-2-pyrrolidone) is contained because the dispersibility of carbon black is further increased.

  The compounding amount of the nonionic polymer is preferably 0.2 parts by mass or more and 3 parts by mass or less with respect to 100 parts by mass of the polyimide polymer of the present embodiment.

  An example of the method for producing the soluble polyimide composition in the present embodiment will be described below.

  First, the polyamic acid solution obtained by polymerizing the tetracarboxylic dianhydride component and the diamine component in an organic solvent is added to a poor solvent such as methanol, and the polyamic acid is once precipitated and reprecipitated and purified. . After filtering off the precipitated polyamic acid, it may be redissolved in a solvent such as γ-butyrolactone to obtain a polyamic acid solution. Next, the polyamic acid solution is subjected to (i) heating or (ii) the action of a dehydrating agent and a catalyst to convert a part of the amic acid group in the polyamic acid to an imide group by a dehydration ring-closing reaction, A polymer solution is obtained. Next, a predetermined amount of acidic carbon black is added to the polyimide polymer solution and mixed to disperse the acidic carbon black.

  Examples of methods for dispersing specific carbon black and breaking up the aggregates include physical methods such as stirring with a mixer or stirrer, parallel rolls, ultrasonic dispersion, and chemical methods such as introduction of a dispersant. However, it is not limited to these.

(Viscosity of soluble polyimide composition)
The viscosity of the soluble polyimide composition is not particularly specified, but a range in which an appropriate viscosity is expressed is selected based on the ease of the coating process when manufacturing the polyimide endless belt. In general, the optimum viscosity range for coating is preferably 1 Pa · s or more and 100 Pa · s or less, and the solid content concentration to be the viscosity is 10% by mass with respect to 100 parts by mass of the coating solvent (for example, organic polar solvent). More than 40 mass% is desirable. In addition, the said viscosity was measured with the E-type viscosity meter, and the measuring method is as follows.

  Using an E-type rotational viscometer TV-20H manufactured by Toki Sangyo Co., Ltd., measurement was performed with a standard rotor (1 ° 34 "× R24).

<Measurement conditions>
Measurement temperature: 22 ° C
Rotational speed: 10 rpm (50 to 100 Pa · s or more), 0.5 to 10 rpm (less than 50 Pa · s).

(Solid fraction of polyimide polymer)
In the polyimide polymer of the present embodiment, the solid content concentration in the soluble polyimide composition is preferably 10% by mass or more from the viewpoint of obtaining a predetermined thickness as a belt material. The solid content concentration is desirably 15% by mass or more, and the upper limit is 50% by mass.

(Imidation rate of polyimide polymer)
The imidization ratio of the polyimide polymer in the soluble polyimide composition is preferably 50% or more. When it is less than 50%, in order to improve the mechanical strength of the belt, it is necessary to cause an imidization reaction by heat treatment during the molding process. The imidation ratio is measured by the following method.

(Measurement of imidization rate)
(I) A polyimide polymer solution is diluted to a solid content of 1% by mass.
(Ii) A coating film is prepared by spin coating (1000 rpm × 20 seconds) on a silicone wafer.
(Iii) The coating film sample is placed in an oven adjusted to 380 ° C. and subjected to heat treatment for 30 minutes to complete imidization (a 100% imide standard sample is prepared).
(Iv) Similarly to the above (i) and (ii), a polyimide polymer solution to be measured (solid content: 1% by mass) is spin-coated (1000 rpm × 20 seconds) on a silicone wafer to produce a coating film. To do. The coating film sample formed with the coating is immersed in a tetrahydrofuran (THF) solvent for 12 hours together with the silicon wafer, and the remaining NMP in the coating film is eluted and substituted with THF.
(V) A sample is taken out from the THF solvent and dried at 25 ° C. under reduced pressure (10 mmHg, 1.3 kPa) for 12 hours (a polyimide polymer sample for measurement is prepared).
(Vi) Using a Fourier transform infrared spectrophotometer (FT-730, manufactured by Horiba, Ltd.), infrared absorption spectra of a 100% imide standard sample and a polyimide polymer sample for measurement were measured. Aromatic ring-derived absorption peak near 1500 cm ^-1 in 100% imide standard samples (Ab ratio of 'to the (1500cm ^-1)), absorption peaks derived from an imide bond in the vicinity of ^{1780cm -1 (Ab' (1780cm -1} )) I '(100) is obtained. Similarly, it was measured for polyimide polymer sample, for the aromatic ring-derived absorption peak near ^{1500cm -1 (Ab (1500cm -1)} ), absorption peaks derived from an imide bond in the vicinity of 1780cm ^-1 (Ab (1780cm ^- The ratio of ¹ )) was determined as I (100).

  From the formula {I (100) / I ′ (100)}, the imidization ratio of the polyimide polymer was determined. That is, it is as follows.

[Equation 1]
I ′ (100) = (Ab ′ (1780 cm ⁻¹ )) / (Ab ′ (1500 cm ⁻¹ ))
I (100) = (Ab (1780 cm ⁻¹ )) / (Ab (1500 cm ⁻¹ ))
(Imidization rate) = I (100) / I ′ (100)

<Polyimide endless belt and manufacturing method thereof>
The soluble polyimide composition of the present embodiment described above is applied to the surface of the cylindrical substrate, and the soluble polyimide composition applied on the cylindrical mold is heat-treated to be included in the soluble polyimide composition. And distilling the remaining amic acid structure part as an unreacted imide.

  Next, an example of the manufacturing method of the polyimide endless belt of this embodiment is shown concretely.

  First, the soluble polyimide composition of this embodiment is applied to the surface of a cylindrical substrate. As the cylindrical base material, a cylindrical mold is preferable. Instead of the mold, molds made of various known materials such as resin, glass, ceramic, etc. are good as the base material according to this embodiment. Can work.

  It is also possible to appropriately select to provide a glass coat or ceramic coat on the surface of the substrate and to use a silicone-based or fluorine-based release agent.

  Furthermore, by moving the film thickness control base material, whose clearance with respect to the cylindrical base material is adjusted, through the cylindrical base material in parallel, the excess solution is eliminated and the thickness of the cylindrical base material solution is made uniform. . If the uniform thickness control of the solution is performed at the stage of applying the solution onto the cylindrical base material, the base material for film thickness control need not be used.

  As the surface of the cylindrical substrate, any of the inner surface / outer surface of the cylindrical substrate can be used. When coating on the inner surface of the substrate, the outer surface of the belt, which is a functional surface of the formed polyimide endless belt, comes into contact with the surface of the substrate, causing contamination from the substrate and deteriorating the characteristics of the polyimide endless belt. There is. On the other hand, when the coating is performed on the outer surface of the base material, it is possible to prevent contamination of the outer surface of the belt, which is a functional surface of the formed polyimide endless belt, from the mold, but it is molded in a state where it is in contact with the atmospheric phase in the drying / firing process. Therefore, oxidative degradation of the conductive polymer, volatilization of the dopant, and the like may occur. Therefore, it is necessary to individually take appropriate process conditions corresponding to the coated surface of the cylindrical base material.

(Coating solvent)
The coating solvent used when the soluble polyimide composition is applied to the surface of the cylindrical substrate is a solvent contained in the soluble polyimide composition. For example, sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, N, N-dimethyl Formamide solvents such as formamide, N, N-diethylformamide, acetamide solvents such as N, N-dimethylacetamide, N, N-diethylacetamide, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, etc. Pyrrolidone solvents, phenol solvents such as phenol, o-, m-, or p-cresol, xylenol, halogenated phenol, catechol, ether solvents such as tetrahydrofuran, dioxane, dioxolane, alcohols such as methanol, ethanol, butanol Le solvents, cellosolve-based or hexamethylphosphoramide, such as butyl cellosolve, .gamma.-butyrolactone and the like are preferably used those alone or as a mixture.

  The coating solvent may be used from the time of synthesizing the polyamic acid that is the precursor described above, or may be replaced with a predetermined solvent after the synthesis of the polyimide polymer. For solvent replacement, a method of diluting a polyamic acid solution or a polyimide polymer solution by adding a predetermined amount of solvent, a method of reprecipitating a polymer and then re-dissolving in a predetermined solvent, a solvent Any of the methods of adjusting the composition by adding a predetermined solvent while gradually distilling off may be used.

  Next, heat treatment is performed while leveling the coating film pressure while rotating the cylindrical substrate coated with the soluble polyimide composition in the circumferential direction. The rotational speed of the cylindrical substrate is adjusted in the range of 1 to 100 rpm according to the viscosity of the coating solution, and is adjusted so that the thickness of the molded body becomes equal while the coating solution is slowly flowing. By the heat treatment, drying is performed until the solvent contained in the coating film volatilizes 20% by mass or more, preferably 60% by mass or more. At this time, the solvent may remain in the film, and there is no problem as long as the surface of the coating film is dry and does not flow even when tilted. The drying temperature is preferably 50 ° C to 200 ° C.

  After drying, the residual solvent is surely distilled off, and the amic acid structure remaining in the polyimide is dehydrated and cyclized to convert to imide, so that the treatment is performed at a high temperature. Since the above-described drying treatment does not flow even when the coating is inclined, the heat treatment does not require rotating the cylindrical mold. For the purpose of merely distilling off the residual solvent, it is desirable that the heating temperature be in the range of 150 ° C to 250 ° C. Moreover, when accompanying imide conversion, it is preferable to fully advance an imide conversion reaction. The heating temperature at this time is, for example, 150 ° C. or higher and 350 ° C. or lower, and desirably 200 ° C. or higher and 300 ° C. or lower. However, the heating temperature differs depending on the types of the raw material tetracarboxylic dianhydride and diamine. It must be set to a temperature that completes the process. If imidization is insufficient, mechanical properties and electrical properties may be inferior.

  On the other hand, as the imide conversion, the following chemical imidization may be performed. In the chemical imidization method, a dehydrating agent and / or a catalyst is added to the polyamic acid composition to chemically advance the imidization reaction. The dehydrating agent is not particularly limited as long as it is a monovalent carboxylic anhydride. For example, the amount of the dehydrating agent used may be one or more selected from acid anhydrides such as acetic anhydride, propionic anhydride, trifluoroacetic anhydride, butanoic anhydride and oxalic anhydride. In addition, it is preferably 0.01 mol or more and 2 mol or less with respect to 1 mol of the polyamic acid repeating unit.

  As the catalyst, for example, one kind or two or more kinds selected from tertiary amines such as pyridine, picoline, collidine, lutidine, quinoline, isoquinoline and triethylamine may be used, but the catalyst is not limited thereto. The amount of the catalyst used is preferably 0.01 mol or more and 2 mol or less with respect to 1 mol of the dehydrating agent used.

  This chemical imidation reaction is performed by adding a dehydrating agent and / or a catalyst to the polyamic acid solution and heating as necessary. The reaction temperature for dehydration and ring closure is usually 0 ° C. or higher and 180 ° C. or lower, preferably 60 ° C. or higher and 150 ° C. or lower.

  There is no particular limitation as long as it is partially imidized, but the composition ratio of the imidized structure to the unreacted amic acid structure is 0/100 (mol / mol) to 80/20 (mol / mol). ) Is preferable. When the composition ratio between the imide group and the amic acid group exceeds 80/20 (mol / mol), the polyamic acid-polyimide copolymer may be insolubilized.

  The dehydrating agent and / or catalyst that has acted on the polyamic acid may not be removed, but may be removed by the following method. As a method of removing the dehydrating agent and / or the catalyst that has acted, heating under reduced pressure or reprecipitation method can be used. The reduced pressure heating is performed at a temperature of 80 ° C. or higher and 120 ° C. or lower under vacuum to distill off the tertiary amine, unreacted dehydrating agent and hydrolyzed carboxylic acid used as a catalyst. The reprecipitation method uses a poor solvent that dissolves the catalyst, unreacted dehydrating agent and hydrolyzed carboxylic acid, and does not dissolve the polyamic acid-polyimide copolymer. This is done by adding liquid. The poor solvent is not particularly limited, and water, alcohol solvents such as methanol and ethanol, ketone solvents such as acetone and methyl ethyl ketone, hydrocarbon solvents such as hexane, and the like can be used. The precipitated polyamic acid-polyimide copolymer is filtered and dried, and then dissolved again in a solvent such as γ-butyrolactone and N-methyl-2-pyrrolidone.

  In the imide conversion, conversion from polyamic acid to polyimide occurs due to the dehydration ring closure reaction of polyamic acid. As a result, a weight reduction corresponding to the amount of water desorbed by the reaction occurs, and the content of acidic carbon black in the polyimide resin component in the polyimide endless belt increases compared to the content of conductive polymer in the polyamic acid resin component. To do. Thereafter, the resin is removed from the mold (base material), and the target polyimide endless belt can be obtained.

  The method for producing the polyimide endless belt of the present embodiment has been described above. However, the present embodiment is not limited to these embodiments, and is based on the knowledge of those skilled in the art without departing from the spirit of the present embodiment. The present invention can be implemented with various improvements, changes and modifications. In addition, you may use as a roll, without removing from a metal mold | die.

(Folding resistance)
The polyimide endless belt according to the present embodiment has a ten-piece sample cut out from the polyimide endless belt until the test piece breaks when measured with a MIT tester under a tensile load of 1.0 kg and a refraction angle of 135 °. The number of reciprocal bending (folding resistance) N was measured. The above measurement was performed on each of 10 pieces of samples, and the obtained number of reciprocal bendings (number of folding times) N was determined, and the average value was used as a representative value.

(Surface resistivity measurement)
The surface resistivity ρs of the outer peripheral surface of the polyimide endless belt was measured as follows. Measure the endless belt of polyimide using a circular electrode (UR probe of HI-Lester IP manufactured by Mitsubishi Yuka Co., Ltd .: cylindrical electrode part outer diameter Φ16 mm, ring electrode part inner diameter Φ30 mm, outer diameter Φ40 mm), and JIS K6911 ( 1995). Specifically, a voltage of 100 V was applied in a 22 ° C./55% RH environment, the current after 10 seconds was measured, and the common logarithm of the surface resistivity (ρs) was calculated.

The details of the method for measuring the surface resistivity are as follows. As shown in FIG. 1, the circular electrode used for measuring the surface resistivity includes a first voltage application electrode A and a plate-like insulator B. The first voltage application electrode A includes a columnar electrode portion C and a cylindrical ring-shaped electrode portion D having an inner diameter larger than the outer diameter of the columnar electrode portion C and surrounding the columnar electrode portion C. Prepare. A cylindrical endless belt T as a measurement sample is sandwiched between the cylindrical electrode portion C and the ring-shaped electrode portion D in the first voltage application electrode A and the plate insulator B, and the cylindrical electrode in the first voltage application electrode A The current I (A) that flows when the voltage V (V) is applied between the part C and the ring-shaped electrode part D is measured, and the surface resistivity ρs (LogΩ / □) is obtained by the following equation.
[Equation 2]
Formula: ρs = π × (D + d) / (D−d) × (V / I)
Here, in the above formula, d (cm) indicates the outer diameter of the cylindrical electrode portion C. D (cm) indicates the inner diameter of the ring-shaped electrode portion D.

<Image forming apparatus>
The image forming apparatus according to the present embodiment includes one or more endless belts, and at least one of the one or more endless belts is the polyimide endless belt according to the present embodiment described above. The endless belt according to this embodiment is used in various applications such as an intermediate transfer belt, a transfer conveyance belt, a conveyance belt, and a fixing belt in an electrophotographic image forming apparatus such as an electrophotographic copying machine, a laser beam printer, a facsimile, and a composite device thereof. Can be used.

  The endless belt is not particularly limited as long as the outer peripheral surface of the endless belt repeats contact and peeling with respect to the recording medium during image formation, and examples thereof include an intermediate transfer belt, a transfer conveyance belt, and a fixing belt. . And the endless belt of this embodiment can be utilized as these endless belts.

  For this reason, in the part using the endless belt of the present embodiment as the endless belt of the image forming apparatus, occurrence of paper jam is suppressed even in a low temperature and low humidity environment.

  As the configuration of the image forming apparatus of the present embodiment, a known configuration is adopted as long as at least one endless belt is mounted.

  Typical configurations of the image forming apparatus of the present embodiment include, for example, an image carrier, a charging unit that charges the surface of the image carrier, and an exposure unit that exposes the surface of the image carrier to form an electrostatic latent image. Developing means for developing the electrostatic latent image formed on the surface of the image carrier with a developer to form a toner image; and transfer means for transferring the toner image formed on the surface of the image carrier to a recording medium; A fixing unit that fixes the toner image transferred to the surface of the recording medium; and a cleaning unit that removes adhering substances such as toner and dust attached to the surface of the image carrier after the toner image is transferred to the recording medium. And other known means may be further provided as necessary.

  In the image forming apparatus having the above-described configuration, when an intermediate transfer belt is used, the toner image is transferred by an intermediate transfer method. In this case, after the toner image formed on the surface of the image carrier is transferred to the outer peripheral surface of the intermediate transfer member by the primary transfer unit, the secondary transfer unit in a state where the recording medium is held on the outer peripheral surface of the intermediate transfer member. And is transferred to the recording medium from the outer peripheral surface of the intermediate transfer member at the secondary transfer portion.

  Further, in the image forming apparatus having the above-described configuration, when a transfer conveyance belt is used, after the toner image formed on the surface of the image carrier is transferred to the outer peripheral surface of the transfer conveyance belt, the recording medium is transferred by the transfer conveyance belt. It is conveyed to fixing means.

  Further, in the image forming apparatus having the above-described configuration, a fixing unit using a fixing belt can be used. The fixing unit includes at least a pair of fixing members disposed so as to face each other, but at least one of the fixing members may be a fixing belt.

  The specific configuration of the fixing means (fixing device) including the fixing belt includes, for example, one or more driving members and an endless belt (fixing belt) that can be driven and rotated by the one or more driving members. The endless belt outer peripheral surface, wherein the endless belt outer peripheral surface is disposed in contact with the endless belt outer peripheral surface, and the drive member surface of any one of the one or more driving members and the endless belt outer peripheral surface The pressure member is formed by the pressing member that presses the surface toward the driving member surface.

  The fixing unit may have other configurations / functions as necessary in addition to the configurations / functions described above. For example, the fixing unit may be used by applying a lubricant to the inner peripheral surface of the endless belt. May be. As the lubricant, a known liquid lubricant (for example, silicone oil) can be used. Further, the lubricant can be continuously supplied via a felt or the like provided in contact with the inner peripheral surface of the endless belt.

  Further, it is preferable that the fixing unit can adjust the pressure distribution in the endless belt axial direction of the press contact portion by the pressing member. For example, when a lubricant is used, the presence of the lubricant applied to the inner peripheral surface, such as bringing the lubricant to one end of the endless belt or collecting it at the center, is adjusted by adjusting the pressure distribution. Can be controlled. For this reason, for example, excess lubricant can be collected and collected at one end of the endless belt, or the lubricant can be moved to the center of the endless belt. Can prevent contamination in the device.

  The adjustment of the pressure distribution is particularly useful when a lubricant is used and the above-described streak roughness is given to the inner peripheral surface of the endless belt to be used. In this case, it is easier to control the presence state of the lubricant applied to the inner peripheral surface by adjusting the pressure distribution of the pressure contact portion in consideration of the direction of the streaky roughness.

  Next, a specific example of the image forming apparatus according to the present exemplary embodiment will be described in detail with reference to the drawings. In the specific examples shown below, the fixing means includes a pair of fixing rolls, but at least one fixing roll may be replaced with a fixing belt.

  FIG. 2 is a schematic configuration diagram illustrating an example of the image forming apparatus according to the present exemplary embodiment. This image forming apparatus uses the endless belt of this embodiment as an intermediate transfer belt.

  An image forming apparatus 100 shown in FIG. 2 includes photosensitive drums 101Y, 101M, 101C, and 101BK, and an image is formed on the surface of the surface by a known electrophotographic process (not shown) as it rotates in the direction of arrow A. An electrostatic latent image corresponding to the information is formed (note that charging means and cleaning means are not shown in FIG. 2).

  Around the photosensitive drums 101Y, 101M, 101C, and 101BK, developing units 105 to 108 corresponding to the respective colors of yellow (Y), magenta (M), cyan (C), and black (BK) are provided. The electrostatic latent images formed on the photosensitive drums 101Y, 101M, 101C, and 101BK are developed by the developing units 105 to 108 to form toner images.

  Therefore, for example, the electrostatic latent image written on the photosensitive drum 101Y corresponds to yellow image information, and this electrostatic latent image is developed by the developing unit 105 containing yellow (Y) toner, A yellow toner image is formed on the photosensitive drum 101Y.

  The intermediate transfer belt 102 is a belt-like intermediate transfer belt disposed so as to be in contact with the surface of the photoconductive drums 101Y, 101M, 101C, and 101BK, and is stretched around a plurality of rolls 117 to 119 to extend in the arrow B direction. Rotate to. As the intermediate transfer belt 102, the above-described endless belt of the present embodiment is applied.

  The unfixed toner images formed on the photosensitive drums 101Y, 101M, 101C, and 101BK are sequentially exposed at respective primary transfer positions where the photosensitive drums 101Y, 101M, 101C, and 101BK are in contact with the intermediate transfer belt 102. The toner images of the respective colors are superimposed and transferred from the body drums 101Y, 101M, 101C, and 101BK onto the surface of the intermediate transfer belt 102.

  In this primary transfer position, charging to the contact area before transfer is performed on the back side of the intermediate transfer belt 102 by the shielding members 121 to 124 for preventing the transfer electric field from acting on unnecessary areas of the intermediate transfer belt 102. The corona dischargers 109 to 112 that prevent the toner are disposed, and a voltage having a polarity opposite to the charging polarity of the toner is applied to the corona dischargers 109 to 112, so that the photosensitive drums 101Y, 101M, 101C, and 101BK The unfixed toner image is electrostatically transferred to the outer peripheral surface of the intermediate transfer belt 102. The primary transfer means is not limited to the corona discharger as long as it uses an electrostatic force, and may be a roll or a brush to which a voltage is applied.

  The unfixed toner image primarily transferred onto the intermediate transfer belt 102 in this way is conveyed to a secondary transfer position facing the conveyance path of the recording medium 103 as the intermediate transfer belt 102 rotates. At the secondary transfer position, a secondary transfer roll 120 and a back roll 117 in contact with the back side of the intermediate transfer belt 102 are disposed with the intermediate transfer belt 102 interposed therebetween.

  The recording medium 103 carried out from the paper supply unit 113 at a predetermined timing by the feed roller 126 is inserted into a contact portion between the secondary transfer roll 120 and the intermediate transfer belt 102. At this time, a voltage is applied to the contact portion between the secondary transfer roll 120 and the roll 117, and the unfixed toner image held on the intermediate transfer belt 102 is transferred to the recording medium 103 at the secondary transfer position. .

  Then, the recording medium 103 on which the unfixed toner image is transferred is peeled off from the intermediate transfer belt 102, and the heating roll 127 of the fixing device provided with the heating roll 127 and the pressure roll 128 facing each other by the conveying belt 115 is added to the heating roll 127. The unfixed toner image is fixed by being sent to the contact portion with the pressure roll 128. At this time, an apparatus configuration of a simultaneous transfer fixing process in which the secondary transfer process and the fixing process are simultaneously performed may be employed.

  The intermediate transfer belt 102 is provided with a cleaning device 116. The cleaning device 116 is disposed so as to be able to contact and separate from the intermediate transfer belt 102 and is separated from the intermediate transfer belt 102 until the secondary transfer is performed.

  FIG. 3 is a schematic configuration diagram illustrating another example of the image forming apparatus according to the present exemplary embodiment. This image forming apparatus is an embodiment in which the endless belt of this embodiment is applied as a transfer conveyance belt.

  An image forming apparatus 200 shown in FIG. 3 includes image forming units 200Y, 200M, 200C, and 200BK including a photosensitive drum, a charging unit, a developing device, and a photosensitive drum cleaner, a transfer conveyance belt 206, and transfer rolls 207Y and 207M. , 207C, 207BK, a recording medium conveyance roll 208, and a fixing unit 209. The transfer / conveying belt 206 includes the endless belt according to the present embodiment.

  The image forming units 200Y, 200M, 200C, and 200BK are provided with photosensitive drums 201Y, 201M, 201C, and 201BK, which are image carriers that can rotate at a predetermined peripheral speed in the direction of arrow A (clockwise direction). Around the photosensitive drums 201Y, 201M, 201C, and 201BK, charging units 202Y, 202M, 202C, and 202BK, exposure units 203Y, 203M, 203C, and 203BK, and color developing units (yellow developing unit 204Y and magenta developing unit 204M). , A cyan developing device 204C and a black developing device 204BK) and photoconductor cleaners 205Y, 205M, 205C, and 205BK, respectively.

  The four image forming units 200Y, 200M, 200C, and 200BK are arranged in parallel with the transfer conveyance belt 206 in the order of the image forming units 200Y, 200M, 200C, and 200BK, but the image forming units 200BK, 200Y, and 200C are arranged. , 200M order, etc., an appropriate order is set according to the image forming method.

  The transfer conveyance belt 206 can be rotated by support rollers 210, 211, 212, and 213 in the direction of arrow B (counterclockwise direction) at the same peripheral speed as the photosensitive drums 201Y, 201M, 201C, and 201BK. A part of the rollers 212 and 213 located in the middle is arranged so as to be in contact with the photosensitive drums 201Y, 201M, 201C, and 201BK, respectively. The transfer conveyance belt 206 is provided with a cleaning device 214.

  The transfer rolls 207Y, 207M, 207C, and 207BK are disposed inside the transfer conveyance belt 206 at positions facing the portions where the transfer conveyance 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 recording medium P are formed via the photosensitive drums 201Y, 201M, 201C, 201BK and the transfer conveyance belt 206.

  The fixing unit 209 is arranged so that it can be conveyed after passing through the respective transfer regions of the transfer conveyance belt 206 and the photosensitive drums 201Y, 201M, 201C, and 201BK.

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

  In the image forming unit 200Y, the photosensitive drum 201Y is rotationally driven. In conjunction with this, the charging means 202Y is driven to charge the surface of the photosensitive drum 201Y to a predetermined polarity and potential. Next, the surface of the photosensitive drum 201Y is exposed imagewise by the exposure unit 203Y, and an electrostatic latent image is formed on the surface.

  Subsequently, the electrostatic latent image is developed by the yellow developing device 204Y. As a result, a toner image is formed on the surface of the photosensitive drum 201Y. The toner at this time may be either a one-component toner or a two-component toner, but here it is a two-component toner.

  As the toner image passes through the transfer area between the photosensitive drum 201Y and the transfer conveyance belt 206, the recording medium P is electrostatically attracted to the transfer conveyance belt 206 and conveyed to the transfer area, and is transferred from the transfer roll 207Y. The image is sequentially transferred onto the outer peripheral surface of the recording medium P by an electric field formed by the applied transfer bias.

  Thereafter, the toner remaining on the photosensitive drum 201Y is cleaned and removed by the photosensitive drum cleaner 205Y. Then, the photosensitive drum 201Y is subjected to the next transfer cycle.

  The above transfer cycle is similarly performed in the image forming units 200M, 200C, and 200BK.

  The recording medium P onto which the toner image has been transferred by the transfer rolls 207Y, 207M, 207C, and 207BK is further conveyed to the fixing unit 209 and fixed. Thus, a desired image is formed on the recording medium.

  As a recording medium, a sheet-like member made of a relatively flexible material such as a paper recording medium (so-called paper) or a recording medium made of a plastic film (so-called OHP sheet) is usually used. However, in the image forming apparatus using the transfer conveyance belt shown in FIG. 3 as an example, a plate-like member made of a relatively rigid material (for example, a thick plastic card) is also used as a recording medium. The

  The electrophotographic image forming apparatus using the endless belt according to this embodiment has been described above. However, the endless belt according to this embodiment is not limited to the electrophotographic image forming apparatus, and one or more endless belts are mounted. The present invention is also applicable to known image forming apparatuses other than the electrophotographic system (for example, an ink jet recording apparatus including an endless belt for paper conveyance, for example).

  The image forming apparatus described above is not limited to these embodiments, and various improvements, changes, and modifications are made based on the knowledge of those skilled in the art without departing from the spirit thereof. It can be implemented.

  Hereinafter, although this embodiment is described using an example, this embodiment is not limited at all by these examples. In the following description, “part” means “part by mass” unless otherwise specified.

[Preparation of polyimide polymer solution]
Synthesis example 1:
In 800 g of N-methyl-2-pyrrolidone (hereinafter abbreviated as “NMP”), as a diamine compound, 19.26 g (hereinafter, m-PDA: 178 mmol), 2,2′-bis {4- ( Aminophenoxy) phenyl} propane 73.1 g (hereinafter, BAPP: 178 mmol) was added and dissolved while stirring at room temperature (25 ° C.). Subsequently, 3,4,3 ′, 4′-benzophenonetetracarboxylic dianhydride 57.38 g (hereinafter referred to as BTDA: 178 mmol) as tetracarboxylic dianhydride, and 1,3,3a, 4, as the third component 5,9b-Hexahydro-5 (tetrahydro-2,5-dioxo-3-furanyl) naphtho [1,2-c] furan-1,3-dione 50.26 g (hereinafter, TDA: 167 mmol) was gradually added. . After the addition and dissolution of tetracarboxylic dianhydride, the temperature of the reaction solution was heated to 60 ° C., and then the polymerization reaction was carried out for 20 hours while maintaining the reaction solution temperature. To the reaction solution, 56.34 g of pyridine (hereinafter, Py: 712 mmol) as a catalyst and 72.20 g of acetic anhydride (hereinafter, Ac ₂ O: 712 mmol) as a dehydrating agent were added, and the reaction was performed at 100 ° C. for 4 hours. While maintaining the temperature, the pressure was reduced at 10 mmHg (1.3 kPa) to distill off the catalyst, the dehydrating agent and the dehydrating agent decomposition product. Filter using # 800 stainless steel mesh, cool to room temperature (25 ° C), and measure solution viscosity at 25 ° C using Papas of 5.0 Pa · s (E-type rotational viscometer TV-20H manufactured by Toki Sangyo Co., Ltd.) A polyimide polymer solution (PI-1) having a temperature of 22 ° C. and a rotation speed of 10 rpm was obtained.

  The composition of the obtained polyamic acid resin was BTDA / TDA / m-PDA / BAPP = 50/47/50/50 (molar ratio), and had a structure in which the amino group was the molecular end.

Synthesis Example 2 to Synthesis Example 13:
Polyimide polymers PI-2 to PI-13 were obtained by using tetracarboxylic dianhydride, diamine compound, catalyst, and dehydrating agent as shown in Table 1. Any of the polyimide polymer resins had a structure in which the amino group was the molecular end due to the excess of the diamine compound.

Synthesis Example 14:
According to Synthesis Example 1, polyamic acid was polymerized. A polyamic acid solution PI-14 was obtained without performing the imidization reaction.

Synthesis Examples 15 to 16:
According to Table 1, polyimide polymer solution PI-15 terminated with an amino group of α = 0.89 and polyimide polymer solution PI-16 terminated with an acid anhydride structure of α = 1.03 were obtained. It was.

Preparation Example 1: Preparation of polyimide polymer composition (B-1):
To 1000 g of the polyimide-based polymer solution PI-1 obtained in Synthesis Example 1, an oxidized carbon black (SPECIAL BLACK4: manufactured by Degussa, pH 4.0, volatile content: 14.4) as a dried acidic carbon black as a conductive agent. 06.2% (hereinafter abbreviated as “SB-4”) was gradually added. A polyimide polymer composition (SS-1) in which carbon black is dispersed in a polyamic acid solution by dispersing at 30 ° C. for 12 hours in a pole mill and then filtered through a # 400 stainless steel mesh to disperse the carbon black. Obtained.

Preparation Examples 2 to 13:
In place of the polyimide polymer solution PI-1 of Preparation Example 1, the polymer solutions PI-2 to PI-12 obtained in Synthesis Examples 2 to 12 were used, respectively, and the oxidized carbon was added in the amounts shown in Table 2. According to Preparation Example 1 except that black (SPECIAL BLACK4: manufactured by Degussa, pH 4.0, volatile content: 14.0%: hereinafter abbreviated as “SB-4”) was added, a polyimide polymer composition ( SS-2) to (SS-12) were respectively prepared.

Preparation Example 14:
Instead of the polyimide polymer solution PI-1 of Preparation Example 1, the polyamic acid solution PI-14 obtained in Synthesis Example 14 was used, and the oxidized carbon black (SPECIAL BLACK4: manufactured by Degussa) was added in the amount shown in Table 2. , PH 4.0, volatile content: 14.0%: hereinafter abbreviated as “SB-4”), a polyamic acid composition (SS-14) was prepared according to Preparation Example 1.

Preparation Examples 15-16:
In place of the polyimide polymer solution PI-1 of Preparation Example 1, the polymer solutions PI-15 to PI-16 obtained in Synthesis Examples 15 to 16 were used, respectively, and oxidized carbon was added in the amounts shown in Table 2. According to Preparation Example 1 except that black (SPECIAL BLACK4: manufactured by Degussa, pH 4.0, volatile content: 14.0%: hereinafter abbreviated as “SB-4”) was added, a polyimide polymer composition ( SS-15) to (SS-16) were respectively prepared.

Example 1: Production of polyimide endless belt (TT-1);
A cylindrical mold made of SUS material having an outer diameter of 90 mm and a length of 450 mm was prepared, and a silicone release agent was applied to the outer surface and subjected to a drying treatment (release agent treatment). While rotating the cylindrical mold subjected to the release agent treatment in the circumferential direction at a speed of 10 rpm, the coating liquid polyimide polymer composition (SS-1) is dispensed from the end of the cylindrical mold with a 1.0 mm diameter dispenser. While discharging more, application was carried out while pressing with a uniform pressure with a metal blade placed on the mold. The dispenser unit was moved in the axial direction of the cylindrical mold at a speed of 100 mm / min to apply the coating liquid on the cylindrical mold in a spiral manner. After coating, the blade was released and the cylindrical mold was kept rotating for 2 minutes for leveling.

  Thereafter, the mold and the coated material were subjected to a drying treatment for 30 minutes while rotating at 10 rpm in an air atmosphere at 150 ° C. in a drying furnace. After drying, the solvent was volatilized from the coated material, whereby the coated material changed to a polyamic acid resin molded product (endless belt body) having self-supporting properties.

  After the drying treatment, a baking treatment was performed at 250 ° C. for 30 minutes in a clean oven to distill off the solvent and complete the imidization reaction. Thereafter, the mold was set to 25 ° C., the resin was removed from the mold, and the target polyimide endless belt (TT-1) was obtained.

Examples 2 to 13: Production of polyimide endless belts (TT-2) to (TT-13);
A polyimide according to Example 1 except that the polyimide polymer compositions (SS-2) to (SS-13) were used in place of the polyimide polymer composition (SS-1) of Example 1. Endless belts (TT-2) to (TT-13) were produced.

Comparative Examples 1-3: Production of polyimide endless belts (TT-14) to (TT-16);
Instead of the polyimide polymer composition (SS-1) of Example 1, a polyamic acid composition (SS-14) and polyimide polymer compositions (SS-15) to (SS-16) were used. Except for the above, polyimide endless belts (TT-14) to (TT-16) were produced in accordance with Example 1, respectively.

(Evaluation of polyimide endless belt)
The following evaluation was performed about the polyimide endless belt obtained in Examples 1-13 and Comparative Examples 1-3. The results are shown in Table 4.

(Measurement of film thickness)
The film thickness of the belt was measured by the method described above.

(Measurement of surface resistivity)
The surface resistivity ρs was determined by the method described above.

(Measurement of volume resistivity)
Each of the obtained polyimide endless belts using a circular electrode (Mitsubishi Yuka Co., Ltd. High Lester IP UR probe: cylindrical electrode part outer diameter Φ16 mm, ring electrode part inner diameter Φ30 mm, outer diameter Φ40 mm), It was measured according to JIS K6911 (1995). Specifically, under a 22 ° C./55% RH environment, a voltage of 100 V was applied, the current after 30 seconds was measured, and the common logarithm of volume resistivity (ρv) was calculated. The results are shown in Table 4.

  Details of the volume resistivity measurement method are as follows. For the measurement of the volume resistivity, the apparatus shown in FIG. 1 can be used similarly to the measurement of the surface resistivity. As shown in FIG. 1, the circular electrode used for measuring the surface resistivity includes a first voltage application electrode A and a second voltage application electrode B. The first voltage application electrode A includes a columnar electrode portion C and a cylindrical ring-shaped electrode portion D having an inner diameter larger than the outer diameter of the columnar electrode portion C and surrounding the columnar electrode portion C. Prepare. A polyimide endless belt T, which is a measurement sample, is sandwiched between the cylindrical electrode portion C and the ring-shaped electrode portion D and the second voltage application electrode B in the first voltage application electrode A. Then, the current I (A) that flows when the voltage V (V) is applied between the cylindrical electrode portion C and the second voltage application electrode B in the first voltage application electrode A is measured, and the volume resistance is calculated by the following equation: The rate ρv (Log Ω · cm) is obtained.

Formula: ρv = πd ² / 4t × (V / I)
Here, in the above formula, d (cm) indicates the outer diameter of the cylindrical electrode portion C. t (cm) represents the film thickness of the polyimide endless belt T.

(Measure folding times)
The folding resistance of the belt was measured by the method described above.

(Evaluation of print quality)
In the produced polyimide endless belt, the following evaluations were performed as initial characteristics. Using a modified DocuCenterColor 2220 manufactured by Fuji Xerox Co., Ltd. (process speed: 250 mm / sec, modified to primary transfer current: 35 μA), the obtained polyimide endless belt was mounted as an intermediate transfer belt, and high temperature and high humidity (28 ° C., 85%) RH) and low-temperature and low-humidity (10 ° C, 15% RH) color toner (cyan toner, magenta toner) such as DocuCentreColor 2220 manufactured by Fuji Xerox Co., and 50% halftone of Cyan and Magenta is output to Fuji Xerox C2 paper Then, the density unevenness and the spot defect were visually evaluated according to the following criteria. The results are shown in Table 4.

-Density unevenness-
The print portion of the tenth print sample is divided into 3 × 3 = 9 equal parts, and each chromaticity is measured using a chromaticity meter CR-210 (manufactured by Minolta Co., Ltd.). The color difference ΔE, which is the difference from the above, was obtained. “O” or higher was accepted.
A: Color difference ΔE is less than 0.3 (density unevenness is not confirmed).
○: Color difference ΔE is 0.3 or more and less than 0.5.
Δ: Color difference ΔE is 0.5 or more and less than 1.0.
X: Color difference ΔE is 1.0 or more.

-Spotted defect-
Spots in the printed part of the 10th printed sample were visually observed and evaluated according to the following criteria. “O” or higher was accepted.
A: Less than 10 spots with a size of less than 0.5 mm.
A: 10 or more and less than 50 spots with a size of less than 0.5 mm were generated.
Δ: 50 or more and less than 100 spots with a size of less than 0.5 mm were generated. Alternatively, less than 50 spots having a size of 0.5 mm or more and less than 1.0 mm were generated, and spots having a size of 1.0 mm or more were not generated.
X: 100 or more spots having a size of less than 0.5 mm were generated. Alternatively, 50 or more spots having a size of 0.5 mm or more and less than 1.0 mm were generated. Alternatively, one or more spots having a size of 1.0 mm or more occurred.

(Evaluation of characteristics after paper passing test)
The film thickness, surface resistivity, volume resistivity, belt presence / absence after folding test, and folding resistance were also measured after passing 1000 sheets (after 30% halftone image formation). Comparison was made with paper.

  As shown in Table 4, the polyimide endless belts of Examples 1 to 11 maintain durability such as folding resistance and wear resistance, and stable resistance characteristics when mounted on an electrophotographic apparatus, and have good copy image quality. It was found that can be expressed stably.

  As an application example of the present invention, there is application to an image forming apparatus such as a copying machine or a printer using an electrophotographic system.

  A first voltage application electrode, B second voltage application electrode, C cylindrical electrode part, D ring electrode part, T polyimide endless belt, 100 image forming apparatus, 101Y, 101M, 101C, 101BK photosensitive drum, 102 intermediate transfer Belt, 105, 106, 107, 108 Developer, 200 Image forming apparatus, 200Y, 200M, 200C, 200BK Image forming unit, 206 Transfer conveyance belt.

Claims (8)

Carbon black having a pH of less than 7 is dispersed in a solution containing a polyimide polymer having the structure of the general formula (1) shown below and a solvent, with respect to the diamine compound in the polymerization reaction to obtain the general formula (1) shown below. Polyimide having a molar ratio of tetracarboxylic dianhydride (α = (number of equivalents of tetracarboxylic dianhydride) / (number of equivalents of diamine compound)) of 0.90 or more and less than 1.00 -Based polymer composition.

... General formula (1)
(In general formula (1), R1 and R3 represent a tetravalent organic group. R2, R4 and R5 represent a divalent organic group. M and n represent an integer of 1 or more, and m / (m + n). ≧ 0.5.) R1 and R3 in the general formula (1) are selected from the following:

R2, R4 and R5 in the general formula (1) are selected from the following:

2. The polyimide polymer composition according to claim 1, further comprising 50 mol% or more of a polyimide polymer having a selected structure of R1, R2, R2, R4, and R5.   In the structure represented by the general formula (1), 1,3,3a, 4,5,9b-hexahydro-5 (tetrahydro-2,5-dioxo-3-furanyl) naphtho [1,2-c] furan- The polyimide-based polymer composition according to claim 1 or 2, further comprising a third component selected from the group consisting of 1,3-dione and ethylene glycol bisanhydro trimellitate. object. Applying the polyimide polymer composition according to any one of claims 1 to 3 to the surface of a cylindrical substrate;
Heat-treating the polyimide-based polymer composition applied on the cylindrical mold; and
A process for producing a polyimide endless belt, comprising:   A polyimide endless belt for transfer or fixing, wherein the polyimide-based polymer composition according to any one of claims 1 to 3 is heat-treated.   A polyimide endless belt for transfer or fixing, which is manufactured by the manufacturing process according to claim 4.   A belt unit comprising the polyimide endless belt according to claim 5. A latent image forming unit that forms a latent image on the latent image carrier, a developing unit that develops the latent image using a developer for developing an electrostatic image, and a developed toner image via an intermediate transfer member or An image forming apparatus comprising: transfer means for transferring onto a transfer body without intervention; and fixing means for fixing a toner image on the transfer body;
7. The image forming apparatus according to claim 5, wherein at least one of a transfer belt used for the transfer unit and a fixing belt used for the fixing unit is the polyimide endless belt according to claim 5.