JP2005215028A - Polyimide endless belt and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent unevenness in film quality due to an imidation reaction by attaining lowering of burning temperature and shortening of burning time for carrying out imidation, and to provide a polyimide endless belt having uniform properties and a manufacturing method by which the polyimide endless belt having uniform properties can easily be obtained. <P>SOLUTION: The polyimide endless belt is composed chiefly of a polyimide tubular part obtained by applying a soluble polyimide solution or a polyimide-polyamic acid copolymer solution on a tubular substrate and carrying out imidation, and the polyimide endless belt is used as an intermediate transfer belt and/or a fixing belt of an electrophotographic apparatus. A molar fraction of imido groups in the total amount of imido groups and amic acid groups present in the polyimide-polyamic acid copolymer (imidation rate) is preferably 50-99%. Such an endless belt is obtained by the manufacturing method including a step of applying a soluble polyimide solution or a polyimide-polyamic acid copolymer solution on a tubular substrate, and a step of forming a polyimide tubular part by carrying out imidation by drying and burning. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polyimide endless belt suitably used for electrophotographic apparatuses such as electrophotographic copying machines, laser beam printers, facsimiles, and composite apparatuses thereof, and a method for manufacturing the same.

  An image forming apparatus using an electrophotographic method forms a uniform charge on an image carrier made of a photoconductive photoreceptor made of an inorganic or organic material, and forms an electrostatic image with a laser beam or the like that modulates an image signal. Then, the electrostatic latent image is developed with a charged toner to form a visualized toner image. The toner image is electrostatically transferred to a transfer material such as a recording sheet through an intermediate transfer member or directly, thereby obtaining a desired reproduced image. In particular, as an image forming apparatus that employs a system in which a toner image formed on the image carrier is primarily transferred to an intermediate transfer member, and a toner image on the intermediate transfer member is secondarily transferred to a recording paper. One disclosed in Japanese Patent No. 206567 is known.

  Here, a method of primary transfer of a toner image on a photosensitive member to an intermediate transfer member and then secondary transfer of the toner image on the intermediate transfer member to a recording medium such as paper, an image forming apparatus adopting a so-called intermediate transfer method. Various proposals have been made as materials for the intermediate transfer belt to be used. For example, polycarbonate resin (for example, see Patent Document 1), PVDF (polyvinylidene fluoride) (for example, see Patent Documents 2 and 3), polyalkylene phthalate. (For example, refer to Patent Document 4), PC (polycarbonate) / PAT (polyalkylene terephthalate) blend material (for example, refer to Patent Document 5), ETFE (ethylene tetrafluoroethylene copolymer) / PC, ETFE / PAT , PC / PAT blend material (for example, see Patent Document 6), etc. It proposed to use a semiconductive endless belt with added click has been made.

In recent years, a method for fixing a toner image on a recording medium by heating an intermediate transfer member, that is, an intermediate transfer-fixing method is disclosed, for example, see Patent Document 7. ). In such an intermediate transfer-fixing method, after a toner image is secondarily transferred to a recording medium via an intermediate transfer member, the intermediate transfer member is directly or indirectly heated to come into contact with the intermediate transfer member. The toner image on the recording medium is fixed on an image receiving medium such as paper. The device can be reduced in size and cost compared to the conventional device in which the intermediate transfer mechanism and the fixing mechanism are separated. Has the advantage of being.
The endless belt used in this system is required to have a mechanical strength that can withstand stress during driving, and at the same time, heat resistance of 200 ° C. or higher that is imparted during fixing. From this requirement, a polyimide resin having both high mechanical strength and heat resistance is used as a material used for the intermediate transfer and the fixing belt.

Polyimide resins are generally difficult to heat and melt due to their high heat resistance, and are insoluble in various solvents. For molding, a solution of polyamic acid, which is the precursor, is applied to a substrate and dried. A polyimide molded body is obtained by heating to perform a dehydration imidization reaction of an amic acid group. In the imidation reaction by heating at this time, since a high temperature of 200 ° C. to 350 ° C. is generally required, there is a problem in terms of energy consumption.
In addition, due to the dehydration reaction of the polyamic acid, voids are generated in the coating film, and the film thickness direction and in-plane quality variations are likely to occur due to the stress generated by the volume shrinkage accompanying the dehydration reaction. In particular, when used as a transfer belt that requires high uniformity and surface smoothness, variation in resistance value is regarded as a major problem in quality.
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 JP-A-6-258960 etc.

The object of the present invention in consideration of the above problems is to reduce the firing temperature and the firing time for imidization, prevent variation in film quality due to imidization reaction, and endless made of polyimide with uniform characteristics The belt is to provide.
A second object of the present invention is to provide a polyimide endless belt manufacturing method that can easily obtain a polyimide endless belt having uniform characteristics without requiring high energy addition for imidization. It is to provide.
At the same time, the present invention seeks to achieve the effect of reducing the environmental burden associated with the discharge of thermal energy used during polyimide molding.

  As a result of intensive studies to solve the above problems, the present inventors use a polyimide having a specific structure or a polyimide-polyamic acid copolymer solution to reduce the firing temperature for imidization or The inventors have found that it is possible to shorten the firing time, and that it is possible to obtain a belt having uniform characteristics by preventing variation in film quality due to imidization reaction, and the present invention has been completed.

That is, the polyimide endless belt of the present invention is mainly composed of a polyimide tubular molded body obtained by applying a soluble polyimide solution or a polyimide-polyamic acid copolymer solution to a tubular substrate and then imidizing. And
As a preferred embodiment of the present invention, the molar fraction of imide groups (imidation ratio) in the total amount of imide groups and amic acid groups present in the polyimide-polyamic acid copolymer is 50 to 99%. Can be mentioned.

Furthermore, it is preferable that the structure derived from the tetracarboxylic dianhydride in the said soluble polyimide or a polyimide-polyamic acid copolymer has a specific structure. That is, as a specific structure derived from tetracarboxylic dianhydride, a structure derived from at least one tetracarboxylic dianhydride selected from the group consisting of the following (A) to (H) is used as an all tetracarboxylic dianhydride. It is characterized by containing 50 mol% or more in the derived structure.
(A) 4- (2,5-dioxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic dianhydride,
(B) 5- (2,5-dioxotetrahydrofuryl) -3-methyl-cyclohexane-1,2-dicarboxylic dianhydride,
(C) 2,3,5-tricarboxycyclopentyl acetic acid dianhydride,
(D) 1,2,3,4-cyclopentanetetracarboxylic dianhydride,
(E) 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride,
(F) 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride,
(G) 3,3 ′, 4,4′-diphenyl ether tetracarboxylic dianhydride,
(H) 3,3 ′, 4,4′-dimethyldiphenylsilanetetracarboxylic dianhydride.

Here, the soluble polyimide or the polyimide-polyamic acid copolymer heats a polyamic acid obtained by a polymerization reaction between a tetracarboxylic dianhydride and a diamine compound, a dehydrating agent, or a dehydrating agent. It is preferably synthesized by acting a catalyst together with the agent. Preferable dehydrating agents used here include monovalent carboxylic acid anhydrides, and preferred catalysts for use with the dehydrating agent include tertiary amines.
The solvent used for the soluble polyimide solution or the polyimide-polyamic acid copolymer solution is N-methyl-2-pyrrolidone, γ-butyrolactone, dimethyl sulfoxide, N, N-dimethylformamide, N, N-dimethylacetamide, It is preferable that the solvent contains 50% by mass or more of one or more selected from the group consisting of:
Moreover, even if the polyimide tubular molded body used as the main body of the polyimide endless belt of the present invention contains 5 to 60 parts by mass of a filler component made of inorganic powder or organic powder with respect to 100 parts by mass of polyimide. Good.
Furthermore, it is preferable that the polyimide tubular molded body which is the main body of the polyimide endless belt of the present invention further contains carbon nanotubes in addition to polyimide.
Such a polyimide endless belt of the present invention can be suitably used for intermediate transfer and / or fixing of an electrophotographic apparatus.

The polyimide endless belt manufacturing method according to claim 11 of the present invention includes a step of applying a soluble polyimide solution or a polyimide-polyamic acid copolymer solution to a tubular base material, and imidization by drying and baking to form a polyimide tubular tube. And a step of forming a molded body.
The soluble polyimide or polyimide-polyamic acid copolymer used in this production method is preferably obtained by removing the dehydrating agent after the dehydrating agent is allowed to act on the precursor polyamic acid in a solution. Here, in removing the dehydrating agent, it is preferable to apply distillation by heating / depressurization or a reprecipitation method using a poor solvent.
Furthermore, the molar fraction of imide groups (imidation rate) in the total amount of imide groups and amic acid groups present in the polyimide-polyamic acid copolymer is 50 to 99%, the soluble polyimide Or a structure derived from at least one tetracarboxylic dianhydride selected from the group consisting of (A) to (H) in the structure derived from all tetracarboxylic dianhydrides in the polyimide-polyamic acid copolymer. Of polyimide, the polyimide tubular molded body contains 5 to 60 parts by mass of a filler component composed of inorganic powder or organic powder with respect to 100 parts by mass of polyimide. It is a preferable aspect to contain.

The endless belt made of polyimide of the present invention can reduce the firing temperature and the firing time for imidization by using a specific soluble polyimide as a raw material, and variations in film quality due to imidization reaction. Prevent and have uniform characteristics.
Moreover, according to the manufacturing method of the polyimide endless belt of the present invention, a polyimide endless belt having uniform characteristics can be easily manufactured without requiring addition of high energy.
Since the endless belt made of polyimide of the present invention does not require the addition of high energy at the time of production, it also has the effect of reducing the environmental load associated with the discharge of thermal energy used during the polyimide molding process.

Hereinafter, the present invention will be described in detail.
The polyimide endless belt of the present invention is obtained by using a soluble polyimide having a specific structure or a precursor thereof, and has a uniform characteristic in which generation of voids and deviation in film thickness are suppressed.
The polyamic acid, which is a precursor of the soluble polyimide or polyimide-polyamic acid copolymer (hereinafter may be collectively referred to as soluble polyimide, etc.) used in the present invention, is a tetracarboxylic dianhydride, a diamine compound, Can be obtained by polymerization reaction in a substantially equimolar amount of an organic polar solvent. Hereinafter, processes for obtaining these compounds and precursors such as soluble polyimide will be described.

(Tetracarboxylic dianhydride)
The tetracarboxylic dianhydride used in the present invention is at least one tetracarboxylic dianhydride selected from the group consisting of the following (A) to (H), and tetracarboxylic acids having these specific structures The dianhydride is preferably used in an amount of 50 mol% or more of all tetracarboxylic dianhydrides.
(A) 4- (2,5-dioxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic dianhydride,
(B) 5- (2,5-dioxotetrahydrofuryl) -3-methyl-cyclohexane-1,2-dicarboxylic dianhydride,
(C) 2,3,5-tricarboxycyclopentyl acetic acid dianhydride,
(D) 1,2,3,4-cyclopentanetetracarboxylic dianhydride,
(E) 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride,
(F) 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride,
(G) 3,3 ′, 4,4′-diphenyl ether tetracarboxylic dianhydride,
(H) 3,3 ′, 4,4′-dimethyldiphenylsilanetetracarboxylic dianhydride.

By using tetracarboxylic dianhydrides having these specific structures, the solubility in solvents can be improved even after polyamic acid is converted into a polyimide / or polyimide-polyamic acid copolymer by the imidization treatment described later. Can be maintained.
When using a general tetracarboxylic dianhydride other than the above-mentioned specific structure as a main component, the rigidity of the molecule is improved by ring-closing the polyamic acid by imidization treatment, so that Since the solubility is significantly reduced and precipitation occurs, it is impossible to obtain a molded product having a uniform film thickness by coating, particularly by a coating method.

  These tetracarboxylic dianhydrides selected from the above (A) to (H) can be used alone or in combination of two or more. The content of the tetracarboxylic dianhydride selected from the above (A) to (H) in the total carboxylic dianhydride is 50 mol% or more, and more preferably in the range of 70 to 100 mol%. When the content of the tetracarboxylic dianhydride having a specific structure is too small, the solvent solubility is lowered when imidized, and the varnish stability may be significantly lowered.

Moreover, in producing the endless belt of the present invention, in addition to the tetracarboxylic dianhydrides shown in the above (A) to (H), a tetracarboxylic dianhydride having another structure is within a range of less than 50 mol%. Can be used together.
The tetracarboxylic dianhydride having such other structure is not particularly limited, and any known aromatic or aliphatic compound can be used.
Examples of the aromatic tetracarboxylic acid include pyromellitic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 3,3 ′, 4,4′-tetraphenylsilanetetracarboxylic dianhydride, 1,2,3,4-furantetracarboxylic 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, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, bis (phthalic acid) phenylphosphine oxa Dianhydride, p-phenylene-bis (triphenylphthalic acid) dianhydride, m-phenylene-bis (triphenylphthalic acid) dianhydride, bis (triphenylphthalic acid) -4,4′-diphenyl ether Anhydride, bis (triphenylphthalic acid) -4,4'-diphenylmethane dianhydride, etc. can be mentioned.

Examples of the aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1 , 2,3,4-cyclobutanetetracarboxylic acid, 3,5,6-tricarboxynorbonane-2-acetic acid dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, bicyclo [2, 2,2] -oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and the like, or aliphatic or alicyclic tetracarboxylic dianhydrides;
1,3,3a, 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 , 9b-Hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione An acid dianhydride etc. can be mentioned.

(Diamine compound)
Moreover, the diamine compound used for reaction with the said tetracarboxylic dianhydride will not be specifically limited if it is a diamine compound which has two amino groups in molecular structure.
Specifically, for example, 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-dia Nofuruoren,

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) full Orene, 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;
An aromatic diamine having two amino groups bonded to an aromatic ring such as diaminotetraphenylthiophene and a hetero atom 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, isophorone Diamine, Tetrahydrodicyclopentadienylenediamine, Hexahydro-4,7-methanoindanylene methylene diamine, Tricyclo [6,2,1,02.7] -Undecylenedimethyl diamine, 4,4'-methylenebis (cyclohexylamine) ) And other aliphatic diamines and alicyclic diamines;
Etc.
Examples of the diamine compound used in the present invention include p-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl sulfide, and 4,4′-diaminodiphenylsulfone. preferable.
These diamine compounds can be used alone or in combination of two or more.

(Polymerization solvent)
Examples of the organic polar solvent used in the production reaction of the polyamic acid which is a precursor such as a soluble polyimide in the present invention include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide; N, N-dimethylformamide, N, N -Formamide solvents such as 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; Phenol , O-, m-, or p-cresol, xylenol, halogenated phenol, catechol, and other phenol solvents; tetrahydrofuran, dioxane, dioxolane, and other ether solvents; methanol, ethanol, butanol, and other alcohol solvents; Cellosolv solvents such as tilcellosolve; or hexamethylphosphoramide, γ-butyrolactone, and the like. These are preferably used alone or as a mixture, and moreover, aromatic hydrocarbons such as xylene and toluene Can also be used.
The organic solvent used for the reaction is not particularly limited as long as it can dissolve the produced polyamic acid.

[Polyamic acid polymerization]
Such a polyamic acid is produced by dissolving the tetracarboxylic dianhydride and the diamine compound in the organic polar solvent and then performing a polycondensation reaction between an acid anhydride group and an amino group.
The molar ratio of tetracarboxylic dianhydride and diamine compound is preferably equivalent. That is, theoretically, when the molar ratio of tetracarboxylic dianhydride and diamine compound is equivalent, the degree of polymerization increases and the solution viscosity becomes maximum. However, the polymerization viscosity can be adjusted by setting the polymerization concentration to a range of 0.95 to 1.05 as necessary from the purity of the raw material monomer and the necessity for coating.

1. Solid content concentration at the time of polyamic acid polymerization The solid content concentration of the polyamic acid solution is not particularly defined, but is preferably 5 to 50% by mass. Furthermore, 10 to 30% by mass is particularly suitable. When the solid content concentration is less than 5% by mass, the degree of polymerization of the polyamic acid is low, and the strength of the molded product finally obtained is lowered. Moreover, when the solid content concentration at the time of polymerization is higher than 50% by mass, an insoluble part of the raw material monomer is generated and the reaction does not proceed.

2. Reaction temperature at the time of polyamic acid polymerization The reaction at the time of polyamic acid polymerization is performed in a temperature range of 0 ° C to 80 ° C. When the reaction temperature is 0 ° C. or lower, the viscosity of the solution becomes so high that it is difficult to sufficiently stir the reaction system, which is not preferable in terms of reaction efficiency. Further, when the temperature of the reaction system is too high, there is a concern that an undesired imidation reaction (ring-closing dehydration reaction caused by heating) may occur in parallel with the polymerization of the polyamic acid, from the viewpoint of reaction control. Problems are pointed out.

[Imidation reaction]
The soluble polyimid or polyimide-polyamic acid copolymer used in the present invention heats the polyamic acid obtained by the above reaction or causes a dehydrating agent to act on the polyamic acid, thereby forming an amic acid group in the polyamic acid. Is converted to an imide group by a dehydration ring closure reaction. Here, when taking the method of making a dehydrating agent act, you may make a catalyst act with a dehydrating agent if desired.

  When the imidization reaction is performed by heating, the heating temperature is usually in the range of 60 to 250 ° C, preferably in the range of 100 to 200 ° C. If the heating temperature is less than 60 ° C., there is a concern that dehydration ring closure does not proceed sufficiently. Moreover, when the heating temperature is too high, the molecular weight of the resulting polymer tends to be small, and the heating temperature may be selected in consideration of the desired molecular weight of the polyimide.

When the imidation reaction is carried out by adding a dehydrating agent and optionally a cyclization catalyst to the polyamic acid solution, the dehydrating agent is preferably a monovalent carboxylic acid anhydride and is particularly limited as long as it is a monovalent carboxylic acid anhydride. Not done. Specifically, for example, acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride can be used.
It is preferable that the usage-amount of a dehydrating agent shall be 0.01-3 equivalent with respect to 1 mol of repeating units of a polyamic acid.
A cyclization catalyst can be used together with the dehydrating agent. Examples of the catalyst that can be used here include, but are not limited to, tertiary amines such as pyridine, collidine, lutidine, and triethylamine. The amount of the cyclization catalyst used is preferably 0.01 to 5 equivalents per mole of the dehydrating agent used.
Dehydration ring closure performed using this dehydrating agent 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 and ring closure is usually in the range of 0 to 180 ° C, preferably 60 to 150 ° C.

The polyimide-polyamic acid copolymer used for the endless belt made of polyimide in the present invention has an imidization ratio defined by the molar fraction of the imide group in the amide group and the amic acid group in the molecular structure of 50 to 99%. 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 at the time of manufacturing the belt, and it is difficult to obtain sufficient strength when the belt is formed.
Examples of a method for removing the acted dehydrating agent and catalyst from the polyimide / or polyimide-polyamic acid copolymer solution imidized with the catalyst / dehydrating agent include distillation by distillation under reduced pressure or reprecipitation.
The method by heating under reduced pressure is carried out under vacuum (under reduced pressure of about 20 mmHg) at a temperature of 80 to 120 ° C., and the tertiary amine used as a catalyst, the unreacted dehydrating agent and the hydrolyzed carboxylic acid are retained. Left.

In the reprecipitation method, a large excess of a poor solvent that dissolves the tertiary amine used as a catalyst, unreacted dehydrating agent and hydrolyzed carboxylic acid and does not dissolve the partially imidized polyamic acid is prepared. The reaction solution is added to the poor solvent.
The poor solvent used here is not particularly limited, and water, alcohol solvents such as methanol and ethanol, ketone solvents such as acetone and methyl ethyl ketone, and hydrocarbon solvents such as hexane are used. The When the reaction solution is added to this solvent, the tertiary amine to be removed dissolves. Therefore, by filtering off the polyimide / polyimide-polyamic acid copolymer deposited here, these unnecessary components are removed. Is done. The precipitate separated by filtration is used after being dried and again dissolved in a solvent such as N-methyl-2-pyrrolidone (NMP).

As described above, a soluble polyimide solution or a polyimide-polyamic acid copolymer solution that is a raw material of the polyimide endless belt of the present invention can be obtained. The polyimide endless belt of the present invention is produced by applying this soluble polyimide solution or polyimide-polyamic acid copolymer solution to a tubular base material, imidizing by drying and firing to form a polyimide tubular molded body. The
Hereafter, this manufacturing method is demonstrated according to a process.

[Coating solvent]
A coating process is a process of apply | coating solutions, such as a soluble polyimide, to a tubular base material.
As described above, the solvent of the soluble polyimide or polyimide-polyamic acid copolymer solution is N-methyl-2-pyrrolidone, γ-butyrolactone, dimethyl sulfoxide, N, N-dimethylformamide, N, N-dimethylacetamide, 1 type or 2 types or more chosen from are included in 50 mass% or more in all the solvents, It is characterized by the above-mentioned. This solvent may be the one used in the previous polyamic acid synthesis, which may be used in this step as a solution.After the polyamic acid synthesis or after the imidization reaction, once the solvent used so far is removed, A predetermined solvent may be substituted for use. Substitution of the solvent may be carried out by either re-precipitation of the polymer and re-dissolving in the predetermined solvent, or by distilling off the solvent and adding the predetermined solvent to adjust the composition.

(Filler component)
In order to control the resistance value, thermal conductivity, and mechanical strength, a filler component made of inorganic powder or organic powder can be further introduced into the polyimide resin layer of the polyimide endless belt in the present invention.
The kind of filler introduced into the resin is not particularly limited. For example, from the viewpoint of controlling the resistance value, a method of mixing an appropriate amount of conductive inorganic powder such as carbon black and carbon nanotubes in a resin is most effective. In addition to carbon black and carbon nanotubes, small-diameter metal particles, metal oxide particles, titanium oxide, various inorganic particles, whiskers formed with a conductive material such as metal oxide, etc., have the same effect. be able to. Furthermore, it is possible to add a powder made of an ion conductive material such as LiCl or a conductive polymer material such as polyaniline.
From the viewpoint of controlling thermal conductivity, for example, aluminum nitride, boron nitride, alumina, silicon carbide, silicon, silica, graphite and the like can be mentioned. Among these, boron nitride is preferable in that it has a high heat conduction function, exhibits a release effect, is chemically stable, and is harmless.
Further, from the viewpoint of controlling the mechanical strength, for example, carbon nanotubes can be mentioned.

(carbon nanotube)
Here, the carbon nanotube used as the filler will be described. By adding carbon nanotubes, not only the resistance value of the soluble polyimide material can be controlled but also the mechanical strength can be improved.
A carbon nanotube is a cylindrical hollow fiber made of carbon, and includes one having a length several tens of times or more the diameter. Specifically, the polyimide precursor solution preferably has a diameter of 0.005 to 1 μm and a length of 1 to 100 μm, more preferably a diameter of 0.01 to 0.5 μm and a length of 1 to 10 μm. It is preferable in consideration of the coating process and the thickness of the coating film. Carbon nanotubes can be produced by a known method such as a thermal decomposition method using a catalyst, an arc discharge method or a laser evaporation method. Moreover, it can also obtain as a commercial item and such a commercial item is also preferably used for this invention.

Here, when a filler component such as added inorganic powder causes poor dispersion in the resin, dielectric breakdown of the material occurs, or when an intermediate transfer member formed by this endless belt is used, There is a concern that image defects may occur due to non-uniform physical properties. On the other hand, when the filler component is dispersed in the resin in a very uniform manner, the number of contact points between the powders may be reduced, and as a result, the electrical conductivity may not be exhibited. In order to solve the conflicting problems, it is required that the inorganic powder is sufficiently dispersed in the resin and that the contact points between the inorganic powders per unit volume can be sufficiently secured. For that purpose, it is necessary to appropriately select the type and amount of the added filler, and to optimize the dispersion method and dispersion conditions in the dispersion step for dispersing the filler in the polyimide solution.
This dispersion condition can be optimized by a known method, but as a typical example, a method of setting the addition amount of the filler component to an optimum amount described below, dispersion by jet mill dispersion, bead mill dispersion, etc. Although methods using means can be adopted, the present invention is not limited to these methods as long as the object of the present invention can be achieved.

  Although there is no restriction | limiting in particular in the addition amount of the filler component contained in the resin component used as the matrix of a belt, For example, in the case of inorganic powder, it is the range of 5-60 mass parts with respect to 100 mass parts of polyimides. In the case of organic powder, it is preferably in the range of 1 to 50 parts by mass. If the addition amount is too small, the purpose of controlling the resistance value and thermal conductivity, which are the purpose of adding the filler component, cannot be sufficiently achieved. On the other hand, when the addition amount is too large, the toughness of the resin is lowered.

When a filler component is contained as desired, the filler component, for example, inorganic powder is added to the soluble polyimide or polyimide-polyamic acid copolymer solution according to the present invention when the resin such as soluble polyimide is dried (as a solid content). A total of 5-60 mass parts is contained with respect to mass parts. As a method of inclusion, a method in which inorganic powder is mixed in an organic solvent, and then a monomer that is a precursor of polyamic acid is polymerized in this organic solvent, a solution in the middle of the polymerization reaction or after completion of the reaction Examples of the method include mixing the inorganic powder as it is or mixing an inorganic powder dispersion prepared in advance.
Physical methods such as stirring with a mixer or stirrer, parallel rolls, ultrasonic dispersion, etc. are used to disperse the inorganic powder in the solution and disrupt the aggregates formed in the dispersion medium for the purpose of uniform dispersion. Furthermore, chemical methods such as introduction of a dispersant are exemplified, but the present invention is not limited to these.

Next, a solution such as a soluble polyimide which may contain a filler component if desired is applied to a tubular substrate, specifically, for example, an inner surface or an outer surface of a cylindrical mold. The tubular substrate is not particularly limited to a mold, and conventionally known molds made of various materials such as resin, glass, and ceramic can be suitably used. It is also possible to appropriately select to provide a glass coat, a ceramic coat or the like on the surface of the mold, and to use a silicone-based or fluorine-based release agent.
Furthermore, by moving the film thickness control mold with the clearance adjusted to the cylindrical mold through the cylindrical mold in parallel, the excess solution can be eliminated and the thickness of the solution on the cylindrical mold can be made uniform. it can. In addition, as long as the uniform thickness control of the solution is performed at the stage of applying the solution onto a tubular base material such as a cylindrical mold, it is not necessary to use a film thickness control mold.

  The thickness of the polyimide endless belt of the present invention is 10 from the viewpoint of maintaining a suitable range of thermal conductivity, resistance value, etc., and securing sufficient strength and toughness in consideration of the use of the belt. -1000 micrometers is preferable and it is still more desirable that it is 30-150 micrometers. Therefore, in the coating process, the coating amount may be determined in consideration of this thickness.

[Belt forming process]
In the production method of the present invention, after the soluble polyimide solution or the like is applied to the tubular base material, it is dried by combining any of vacuum drying and heat drying, or a combination of these, followed by firing to form soluble polyimide or the like. A step of forming a polyimide tubular molded body by completing the ring closure reaction and imidation reaction of the amic acid group contained in the solution is performed.
Specifically, a cylindrical mold (tubular substrate) coated with a solution of soluble polyimide or the like according to the present invention is dried by placing it in a heated or vacuum environment, and then fired to advance the imidization reaction. . Thereafter, the resin is removed from the mold, and the desired endless belt made of polyimide can be obtained.

Vacuum drying is preferably performed at 50 to 200 ° C. for 10 minutes to 3 hours under reduced pressure conditions of about 0.1 to 100 mmHg. In the case of heat drying, the temperature conditions are in the range of 100 to 250 ° C., It is preferably performed for about 10 minutes to 3 hours. As the heating means, a known means may be used. For example, heating on a hot plate, drying in a heating oven, or the like can be used.
After carrying out the drying step, a firing step is carried out for the purpose of further imidization and completing the reaction. The firing step is preferably performed at a temperature of 150 ° C. or higher for about 10 minutes to 3 hours.

  The tubular polyimide molded body obtained after the imidation reaction can be used as it is, or can be cut into a desired width according to the use mode to obtain a polyimide endless belt.

In the endless belt made of polyimide, if the difference between the maximum thickness and the minimum thickness is too large, it will cause wrinkles. The wrinkle of the belt should be reduced as much as possible because it induces a decrease in image quality when transferring or fixing. From this point, it is desirable that the difference between the maximum thickness and the minimum thickness of the polyimide endless belt is 20% or less of the average thickness of the polyimide endless belt. According to the manufacturing method of the present invention, such an endless belt having a uniform thickness can be easily obtained. Here, the “belt thickness” is a thickness that can be measured by a thickness meter that measures the distance between flat plates in contact with the belt at an area of 5 mm ² or more. The height of the following protrusions is ignored.

The polyimide endless belt of the present invention can be obtained without performing a dehydration imidization reaction by high-temperature heating that is generally performed, so it does not require high energy at the time of production, and can be used for high-temperature heating such as 200 ° C. to 350 ° C. Since the occurrence of voids is effectively suppressed, the belt surface is excellent in smoothness and thickness uniformity, and can be suitably used as an endless belt for intermediate transfer and fixing in an electrophotographic apparatus.
Such characteristics are largely attributed to the specific tetracarboxylic dianhydride as a raw material, but such a raw material is used in place of such a general tetracarboxylic dianhydride. For example, it can be easily detected by analyzing the resin component in the belt by pyrolysis gas chromatography and confirming the molecular structure and content of the raw material monomer in the resin component.

  As described above, the polyimide endless belt and the manufacturing method thereof according to the present invention have been described. However, the present invention is not limited to these embodiments, and the knowledge of those skilled in the art is within the scope of the present invention. Based on the above, the present invention can be implemented in a mode with various improvements, changes, and modifications.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
[Synthesis Example 1: Synthesis of polyimide (1-1)]
1-1. Synthesis of polyamic acid (1-0) 1600 g of N-methyl-2-pyrrolidone (NMP) was placed in a 5000 ml flask equipped with a stirring blade and heated to 60 ° C. As a diamine compound, 160.03 g of 4,4′-diaminodiphenyl ether was added and stirred until completely dissolved. While continuing heating and stirring, as the specific tetracarboxylic dianhydride, 4- (2,5-dioxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid 239.97 g of anhydride was gradually added and dissolved. After the tetracarboxylic dianhydride was dissolved, the polyamic acid polymerization reaction proceeded and the viscosity of the solution increased. When the viscosity of the solution reached 10 Pa · s, 2000 g of NMP was added and diluted to 10%, and then cooled to room temperature to obtain a polyamic acid (1-0) solution.

1-2. Synthesis of Polyimide (1-1) 500 g of the polyamic acid (1-0) solution obtained as described above was weighed into a flask container, and 31.60 g of pyridine and 40.35 g of acetic anhydride were added. Dehydration ring closure reaction was performed at 120 ° C. for 3 hours. After distilling off the catalyst and the dehydrating agent, the solution concentration was adjusted to 10% to obtain a polyimide (1-1) solution.
A part of the polyimide (1-1) was poured into methyl alcohol to precipitate the produced polymer. Washed with methanol, dried at 40 ° C. under reduced pressure for 15 hours, dissolved in d6-DMSO (N, N-dimethylsulfoxide), quantified carboxylic acid protons attributed to amic acid by NMR, and determined imidation rate. The calculated value was 100%.

[Synthesis Example 2: Synthesis of polyimide-polyamic acid (1-2)]
The same as Synthesis Example 1 except that 500 g of polyamic acid (1-0) obtained in the same manner as in Synthesis Example 1 was used and the compound to be added was changed to 23.70 g of pyridine and 30.25 g of acetic anhydride. Thus, polyimide-polyamic acid (1-2) was obtained. The imidation ratio calculated in the same manner as in Synthesis Example 1 was 77%.

[Synthesis Example 3: Synthesis of polyimide-polyamic acid (1-3)]
A polyimide-polyamic acid (1-3) was obtained in the same manner as in Synthesis Example 1 except that 500 g of the polyamic acid (1-0) was used and 18.96 g of pyridine and 24.21 g of acetic anhydride were added. . The imidation ratio calculated in the same manner as in Synthesis Example 1 was 51%.

[Synthesis Example 4: Synthesis of polyimide (1-4)]
To 500 g of the polyamic acid (1-0) solution used in Synthesis Example 1, 31.60 of pyridine and 40.35 g of acetic anhydride were added, and a dehydration ring-closing reaction was performed at 120 ° C. for 3 hours. The reaction solution was added to a large excess of methanol and reprecipitation was performed to remove the catalyst and the dehydrating agent. The precipitated white polymer was filtered off and dried, and then redissolved in NMP to adjust the solution concentration to 10% to obtain a polyimide (1-4) solution. When the imidation ratio was calculated in the same manner as in Synthesis Example 1, it was 100%.

[Synthesis Example 5: Synthesis of polyimide (1-5)]
500 g of the polyamic acid (1-0) solution obtained in the same manner as in Synthesis Example 1 was weighed into a flask container, then refluxed at 200 ° C., and subjected to dehydration ring closure reaction for 3 hours. The solution was cooled to room temperature to obtain a polyimide (1-5) solution. The imidation ratio was calculated in the same manner as in Synthesis Example 1 and was 100%.

[Synthesis Example 6: Synthesis of polyimide (2-1)]
6-1. Synthesis of polyamic acid (2-0) 15000 g of N-methyl-2-pyrrolidone (NMP) was placed in a 5000 ml flask equipped with a stirring blade and heated to 60 ° C. 160.52 g of 4,4′-diaminodiphenyl ether was added as a diamine compound and stirred until it was completely dissolved. While continuing heating and stirring, as the specific tetracarboxylic dianhydride, 4- (2,5-dioxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid 180.52 g of anhydride and 58.96 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, which is a general tetracarboxylic dianhydride used together, were gradually added and dissolved. After the tetracarboxylic dianhydride was dissolved, the polyamic acid polymerization reaction proceeded and the viscosity of the solution increased. When the viscosity of the solution reached 10 Pa · s, 2000 g of NMP was added and diluted to 10%, and then cooled to room temperature to obtain a polyamic acid (2-0) solution.

6-2. Synthesis of Polyimide (2-1) 500 g of the polyamic acid (2-0) solution obtained as described above was weighed into a flask container, and 31.70 g of pyridine and 40.50 g of acetic anhydride were added. Dehydration ring closure reaction was performed at 120 ° C. for 3 hours. The catalyst and the dehydrating agent were distilled off to adjust the solution concentration to 10% to obtain a polyimide (2-1) solution. When the imidation ratio was calculated in the same manner as in Example 1, it was 100%.

[Synthesis Example 7: Synthesis of polyimide (3-1)]
7-1. Synthesis of polyamic acid (3-0) 15000 g of N-methyl-2-pyrrolidone (NMP) was placed in a 5000 ml flask equipped with a stirring blade and heated to 60 ° C. As a diamine compound, 143.41 g of 4,4′-diaminodiphenyl ether was added and stirred until completely dissolved. While continuing heating and stirring, 256.59 g of 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride was gradually added and dissolved as the specific tetracarboxylic dianhydride. After dissolution of tetracarboxylic dianhydride, the polyamic acid polymerization reaction proceeded and the viscosity of the solution increased. When the viscosity of the solution reached 10 Pa · s, 2000 g of NMP was added and diluted to 10%, and then cooled to room temperature to obtain a polyamic acid (3-0) solution.

7-2. Synthesis of Polyimide (3-1) 500 g of the polyamic acid (3-0) solution obtained as described above was weighed into a flask container, and 28.48 g of pyridine and 36.36 g of acetic anhydride were added. Dehydration ring closure reaction was performed at 120 ° C. for 3 hours. The catalyst and the dehydrating agent were distilled off, and the solution concentration was adjusted to 10% to obtain a polyimide (3-1) solution. When the imidation ratio was calculated in the same manner as in Example 1, it was 100%.
These synthesis examples are summarized in Table 1 below. In addition, the abbreviation of the compound in the following Table 1 is as showing below.

(Polyimide and its precursor)
PAA: Polyamic acid PI: Polyimide PI-PAA: Polyimide polyamic acid copolymer (tetracarboxylic dianhydrides)
TDA: 4- (2,5-dioxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic dianhydride DSDA: 3,3 ′, 4,4′- Biphenylsulfone tetracarboxylic dianhydride BPDA: 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (solvent)
NMP: N-methyl-2-pyrrolidone THF: Tetrahydrofuran

[Example 1]
(Manufacture of belts)
4 g of carbon black 3030B (manufactured by Mitsubishi Chemical Corporation) was added to 200 g of NMP, and the mixture was stirred well and treated with an ultrasonic disperser to prepare a carbon black dispersion having a particle size of 1 μm or less. In this dispersion, 20.00 g of the polyimide (1-1) solution obtained in Synthesis Example 1 was dissolved.
The polyimide solution in which the carbon black thus obtained was dispersed was uniformly applied to the surface of a cylindrical SUS mold having an inner diameter of 90 mm and a length of 450 mm. The cylindrical mold was preliminarily coated with a fluorine-based release agent to improve the peelability after belt molding.
Next, it was dried for 30 minutes at a temperature of 120 ° C. while rotating the mold. Next, the mold was placed in an oven and baked at 250 ° C. for about 30 minutes. Thereafter, the mold was allowed to cool at room temperature, the resin was removed from the mold, and the desired endless belt made of polyimide (1-1) was obtained.

The following measurements were performed on various properties of the polyimide endless belt obtained in Example 1. The evaluation results are shown in Tables 2 and 3 below.
[Endless belt evaluation 1]
(1. Imidization rate)
A test piece was cut out from the obtained endless belt made of polyimide and measured by FT-IR (Perkin Elmer Fourier transform infrared absorption spectrum spectrometer). The 400 ° C. calcined product as 100% imidization ratio was determined by the ratio of the vibration peaks of the aromatic ring of the stretch peak and 1012 cm ^-1 of the carbonyl group of the 1776 cm ^-1.
(2. Belt thickness measurement)
Ten test pieces were randomly cut out from the obtained endless belt made of polyimide, and a film thickness meter was used.

(3. Volume resistance value)
A test piece of 10 cm × 10 cm was cut out from the obtained endless belt made of polyimide, and its volume resistance value was measured with an ultra high resistance measuring device manufactured by Advantech.
As a result, the imidization ratio of this polyimide endless belt was about 100%, the thickness was 70 ± 2 μm, and the volume resistance value was 1 × 10 ⁸ Ω · cm.
(4. Tensile strength, elongation, elastic modulus)
A dumbbell-shaped test piece having a width of 5 mm was produced from the obtained endless belt made of polyimide using a punching machine. Tensile strength (speed: 100 mm / min), elastic modulus, and elongation at break were measured using a tensile tester 1605N manufactured by Aiko Engineering.
(5. Electrophotographic mounting test)
The obtained polyimide endless belt was incorporated into an electrophotographic apparatus DocuCentreColor400CP manufactured by Fuji Xerox Co., Ltd., and the initial copy image quality was evaluated. As evaluation items for copy image quality, the presence / absence of printing deviation, the presence / absence of uneven printing density, the presence / absence of ghost, etc. were evaluated. The image quality after the 50,000 sheet passing test was similarly evaluated. The belt length before and after the paper passing test was measured, and the belt durability when using the actual machine was evaluated and compared.

[Examples 2 to 7]
Instead of the polyimide (1-1) used in Example 1, the polyimide-polyamic acid (1-2) obtained in Synthesis Example 2, the polyimide-polyamic acid (1-3) obtained in Synthesis Example 3, Polyimide (1-4) obtained in Synthesis Example 4; polyimide (1-5) obtained in Synthesis Example 5; polyimide (2-1) obtained in Synthesis Example 6; polyimide obtained in Synthesis Example 7 -A polyimide endless belt was produced in the same manner as in Example 1 except that the polyamic acid (3-1) solution was used, and Examples 2, 3, 4, 5, 6 and 7 were obtained, respectively. Tables 2 and 3 show the results of evaluating the characteristics of the obtained polyimide endless belts in the same manner as in Example 1.

From the results shown in Tables 2 and 3, it can be seen that the polyimide endless belts of Examples 1 to 7 according to the present invention are sufficiently advanced in imidation reaction and have high film strength. Moreover, the film thickness unevenness of the film observed in the progress of the imidization reaction was suppressed, and the belt had a uniform thickness. Further, the volume resistivity was stabilized in the range of 1 × 10 ⁶ to 1 × 10 ¹² Ωcm, and it was confirmed that the volume resistivity was suitable for an intermediate transfer belt.
Further, even in the evaluation of an actual device mounted on an electrophotographic apparatus, the belt did not stretch and there was no problem in print quality.

[Comparative Synthesis Example 1: Synthesis of polyimide (4-1)]
1. Synthesis of polyamic acid (4-0) 1600 g of N-methyl-2-pyrrolidone (NMP) was placed in a 5000 ml flask equipped with a stirring blade and heated to 60 ° C. As a diamine compound, 161.99 g of 4,4′-diaminodiphenyl ether was added and stirred until it was completely dissolved. While continuing heating and stirring, 238.01 g of 3,3 ′, 4,4′-biphenylcarboxylic dianhydride, which is a general tetracarboxylic dianhydride, was gradually added and dissolved. After dissolution of tetracarboxylic dianhydride, the polyamic acid polymerization reaction proceeded and the viscosity of the solution increased. When the viscosity of the solution reached 10 Pa · s, 2000 g of NMP was added and diluted to 10%, and then cooled to room temperature to obtain a polyamic acid (4-0) solution.
2. Synthesis of Polyimide (4-1) 500 g of the polyamic acid (4-0) solution obtained as described above was weighed into a flask container, and 32.04 g of pyridine and 40.91 g of acetic anhydride were added. Dehydration ring closure reaction was performed at 120 ° C. As the imidization reaction progressed, a pale yellow polyimide was deposited, and a soluble polyimide could not be obtained.

[Comparative Synthesis Example 2: Synthesis of polyimide (1-6)]
500 g of the polyamic acid (1-0) solution obtained in the same manner as in Synthesis Example 1 was weighed into a flask container, and 28.80 g of pyrrolidine as a secondary amine compound and 24.06 g of acetic acid as a carboxylic acid compound were added. The mixture was heated to reflux at 120 ° C. When the imidization rate was measured for the obtained polymer, the imidation rate was 5%, and the reaction hardly proceeded.

[Comparative Synthesis Example 3: Synthesis of Polyimide (5-1)]
1. Synthesis of polyamic acid (5-0) A reaction was carried out in the same manner as in Synthesis Example 1 except that the solvent was THF, to obtain a polyamic acid (5-0) solution.
2. Synthesis of polyimide (5-1) The reaction was performed in the same manner as in Synthesis Example 1 except that the polyamic acid (5-0) obtained as described above was used. As the imidization reaction progressed, a pale yellow polyimide was deposited, and a soluble polyimide could not be obtained.
These comparative synthesis examples are also shown in Table 1. In Table 1, “Comparative Synthesis Example 1” to “Comparative Synthesis Example 3” are abbreviated as “Comparison 1” to “Comparison 3”, respectively.

[Comparative Examples 1-3]
Using the polyamic acid (1-0), polyamic acid (2-0), and polyamic acid (3-0) obtained in Comparative Synthesis Examples 1, 2, and 3, a polyimide endless belt was prepared in the same manner as in Example 1. It manufactured and it was set as Comparative Examples 1-3, respectively.
The endless belts of Comparative Examples 1 to 3 were evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 2 and 3 above.

As is apparent from Tables 2 to 3, in the comparative example, polyimide using a normal synthesis process is used, but the endless belt made of polyimide obtained under any condition is also a void during the imidization reaction. Due to the occurrence of this, etc., there was a large variation in the thickness. Moreover, imidation could not be completed under the present study conditions, and the film strength was not sufficient and there was a problem in use as a belt. Further, since the volume resistivity is low when the imidization reaction is not sufficiently progressed, if the imidization reaction is difficult to proceed, there is a problem that the belt quality ultimately varies depending on the firing process.
Furthermore, the belt which was incorporated into the electrophotographic apparatus and subjected to the paper passing test was stretched, and the apparatus trouble occurred due to the poor belt tension. There was a shift in the print position, and the print quality tended to deteriorate.

(Comparative Examples 4-6)
Using the polyamic acid (1-0) obtained in Synthesis Example 1 as a raw material, the firing temperature is 300 ° C., the firing time is 30 minutes (Comparative Example 4), 1 hour (Comparative Example 5), 2 hours (Comparative Example) A polyimide endless belt was produced in the same manner as in Example 1 except for 6).
The endless belt made of polyimide obtained under any of the conditions of Comparative Examples 4 to 6 was also affected by the generation of voids due to high temperature heating, and a large variation in thickness was observed.
In addition, although the firing temperature was high under the examination conditions of Comparative Examples 4 and 5, imidation could not be completed in Comparative Example 5 despite the longer firing time. Compared with -5, the film strength was not sufficient and there was a problem in using as a belt. On the other hand, in Comparative Example 6, although imidization equivalent to that obtained in Examples 1 to 5 was achieved, the variation in film thickness due to void generation was large, and further compared to Examples 1 to 5 Since the firing temperature is high and the firing time is long, there is a problem in terms of energy consumption during production.

Example 8
4 g of carbon nanotubes (diameter: about 20 nm, length: about 2 μm) made by Showa Denko were put into 200 g of NMP and stirred well. Furthermore, it processed with the ultrasonic disperser and was set as the particle diameter of 1 micrometer or less. In this dispersion, 200.00 g of the polyimide (1-1) solution obtained in Synthesis Example 1 was dissolved.
The polyimide solution in which the carbon nanotubes thus obtained were dispersed was uniformly applied to the surface of a cylindrical SUS mold having an inner diameter of 90 mm and a length of 450 mm. The cylindrical mold was preliminarily coated with a fluorine-based release agent to improve the peelability after belt molding. Next, it was dried for 30 minutes at a temperature of 120 ° C. while rotating the mold. Next, the mold was placed in an oven and baked at 250 ° C. for about 30 minutes. Thereafter, the mold was allowed to cool at room temperature, the resin was removed from the mold, and the desired endless belt made of polyimide (1-1) was obtained.

The obtained polyimide endless belt was evaluated as follows. The evaluation results other than the following abrasion resistance test carried out specifically on Example 8 are also shown in Tables 2 and 3 above.
[Endless belt evaluation 2]
(1. Belt state)
The surface of the obtained endless belt made of polyimide was visually observed for the presence of voids and the presence or absence of film shrinkage.
As a result, the polyimide endless belt surface was uniform without voids.
(2. Wear resistance test)
The abrasion resistance test was determined by the following method.
The produced belt was cut into about 100 mm square, and the small piece was fixed to the glass plate with an instantaneous adhesive. This sample was set on a scratch tester CSR-101 (manufactured by Reska Co., Ltd.) rotary sample table. A nylon cloth was placed on a 10φ probe, and the sample surface was rubbed while rotating at 200 rpm with a load of 2 kg. The amount of wear after 2000 revolutions was evaluated by the film thickness with the untested part using a stylus type film thickness meter Alphastep 500 KLA Tencor.
As a result, although the film thickness after the test was reduced by 5 μm, it is found that the film is at a level that is not problematic for use and is excellent in wear resistance.

(3. Belt thickness measurement)
The same measurement as in Example 1 was performed.
As a result, the thickness was 70 ± 2 μm.
(4. Volume resistance value)
The same measurement as in Example 1 was performed.
As a result, the volume resistance of this polyimide endless belt was 1 × 10 ⁸ Ω · cm.
(5. Tensile strength, elongation, elastic modulus)
The same measurement as in Example 1 was performed.
As a result, the tensile strength was 24 kg / mm ² , the elastic modulus was 300 kg / mm ^2, and the elongation at break was 20%.
(5. Electrophotographic machine mounting test)
The same evaluation as in Example 1 was performed.
As a result, it was good both before and after paper passing.

In comparison between these examples and comparative examples, it was confirmed that the polyimide having the specific structure according to the present invention has good solubility and stability in solvents such as NMP even though the imidization fraction is high. It was. By using the soluble polyimide solution according to the present invention, it is not necessary to carry out an imidization reaction at a high temperature unlike conventional polyamic varnishes, and a polyimide film can be produced simply by drying a solvent at a low temperature. As a result, the endless belt made of polyimide according to the present invention can be manufactured with lower energy at the time of firing compared to the endless belt made of polyimide obtained by the conventional manufacturing method, and the generation of voids seen at the time of thermal imidization, etc. Thus, non-uniformity of the film due to in-plane variation of the imidization reaction can be prevented. Furthermore, while the conventional manufacturing method performs imidization treatment for each individual belt by heating, according to the manufacturing method of the present invention, the imidization reaction is collectively performed in a polyimide varnish state, This can greatly contribute to energy consumption reduction in the entire manufacturing process.
In addition, from the results of Example 8, when carbon nanotubes are used as the filler, they are uniform, the generation of voids is suppressed, and good conductivity is exhibited. Furthermore, mechanical strength, in particular, breaking strength, wear resistance, is exhibited. It was also found that an excellent endless belt can be obtained.
Even if the endless belt made of polyimide according to the present invention has a high imide fraction even if it is processed with low energy, it is not necessary to apply high energy, and sufficient belt strength and high durability can be obtained. .
Therefore, according to this invention, the environmental load reduction effect accompanying discharge | emission of the thermal energy used at the time of a polyimide molding process can also be acquired.

Claims (17)

  A polyimide endless belt comprising a polyimide tubular molded body obtained by applying a soluble polyimide solution or a polyimide-polyamic acid copolymer solution to a tubular base material, followed by imidization.   The molar fraction (imidation ratio) of the imide group in the total amount of imide groups and amic acid groups present in the polyimide-polyamic acid copolymer is 50 to 99%. Endless belt made of polyimide as described in 1. In the structure derived from all tetracarboxylic dianhydrides in the soluble polyimide or polyimide-polyamic acid copolymer, at least one tetracarboxylic dianhydride selected from the group consisting of (A) to (H) below: The endless belt made of polyimide according to claim 1 or 2, wherein the structure derived from 50 mol% or more is included.
(A) 4- (2,5-dioxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic dianhydride,
(B) 5- (2,5-dioxotetrahydrofuryl) -3-methyl-cyclohexane-1,2-dicarboxylic dianhydride,
(C) 2,3,5-tricarboxycyclopentyl acetic acid dianhydride,
(D) 1,2,3,4-cyclopentanetetracarboxylic dianhydride,
(E) 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride,
(F) 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride,
(G) 3,3 ′, 4,4′-diphenyl ether tetracarboxylic dianhydride,
(H) 3,3 ′, 4,4′-dimethyldiphenylsilanetetracarboxylic dianhydride.   The soluble polyimide or polyimide-polyamic acid copolymer was synthesized by heating a polyamic acid obtained by a polymerization reaction between a tetracarboxylic dianhydride and a diamine compound or by acting a dehydrating agent. The endless belt made of polyimide according to any one of claims 1 to 3, wherein the endless belt is made of polyimide.   The endless belt made of polyimide according to any one of claims 1 to 4, wherein the dehydrating agent is a monovalent carboxylic acid anhydride.   The endless belt made of polyimide according to any one of claims 1 to 4, wherein a tertiary amine catalyst is allowed to act together with the dehydrating agent.   The solvent of the soluble polyimide solution or the polyimide-polyamic acid copolymer solution is composed of N-methyl-2-pyrrolidone, γ-butyrolactone, dimethyl sulfoxide, N, N-dimethylformamide, N, N-dimethylacetamide. The endless belt made of polyimide according to any one of claims 1 to 6, wherein 50% by mass or more of one kind or two or more kinds selected from the group is contained in all the solvents.   The said polyimide tubular molded object contains 5-60 mass parts of filler components which consist of inorganic powder or organic powder with respect to 100 mass parts of polyimides. Endless belt made of polyimide as described in 1.   The polyimide endless belt according to any one of claims 1 to 4, wherein the polyimide tubular molded body contains carbon nanotubes.   The endless belt made of polyimide according to any one of claims 1 to 9, wherein the endless belt is used for intermediate transfer and / or fixing in an electrophotographic apparatus.   A polyimide endless process comprising: a step of applying a soluble polyimide solution or a polyimide-polyamic acid copolymer solution to a tubular substrate; and a step of imidizing by drying and baking to form a polyimide tubular molded body. A method for manufacturing a belt.   The soluble polyimide or polyimide-polyamic acid copolymer is obtained by removing a dehydrating agent after allowing the polyamic acid as a precursor to act on the dehydrating agent in a solution. Of manufacturing an endless belt made of polyimide.   The method for producing an endless belt made of polyimide according to claim 11 or 12, wherein the removal of the dehydrating agent is performed by distillation by heating or decompression, or by a reprecipitation method using a poor solvent. .   The molar fraction (imidation ratio) of imide groups in the total amount of imide groups and amic acid groups present in the polyimide-polyamic acid copolymer is 50 to 99%, characterized in that: A method for producing an endless belt made of polyimide as described in 1. In the structure derived from all tetracarboxylic dianhydrides in the soluble polyimide or polyimide-polyamic acid copolymer, at least one tetracarboxylic dianhydride selected from the group consisting of (A) to (H) below: The method for producing an endless belt made of polyimide according to any one of claims 11 to 14, wherein a structure derived from 50 mol% or more is contained.
(A) 4- (2,5-dioxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic dianhydride,
(B) 5- (2,5-dioxotetrahydrofuryl) -3-methyl-cyclohexane-1,2-dicarboxylic dianhydride,
(C) 2,3,5-tricarboxycyclopentyl acetic acid dianhydride,
(D) 1,2,3,4-cyclopentanetetracarboxylic dianhydride,
(E) 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride,
(F) 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride,
(G) 3,3 ′, 4,4′-diphenyl ether tetracarboxylic dianhydride,
(H) 3,3 ′, 4,4′-dimethyldiphenylsilanetetracarboxylic dianhydride.   The said polyimide tubular molded object contains 5-60 mass parts of filler components which consist of inorganic powder or organic powder with respect to 100 mass parts of polyimides, The any one of Claims 11 thru | or 15 characterized by the above-mentioned. A method for producing an endless belt made of polyimide as described in 1.   The said polyimide tubular molded object contains a carbon nanotube, The manufacturing method of the polyimide endless belt of any one of Claim 11 thru | or 15 characterized by the above-mentioned.