JP2011059464A - Method for manufacturing seamless belt for electrophotographic device, seamless belt for electrophotographic device, and electrophotographic device using the belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a resin-made seamless belt, capable of facilitating release of the belt from a mold (demolding) without damage thereon, repeatedly using the mold without maintenance, and efficiently manufacturing the belt. <P>SOLUTION: In the method for manufacturing a seamless belt for electrophotographic device by applying a coating liquid containing a resin component to the inner surface or outer surface of a cylindrical die, followed by drying and/or curing to thereby form a film, and demolding the film, the formed film is treated with supercritical fluid or subcritical fluid together with the cylindrical die, and then demolded. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a seamless belt provided in an image forming apparatus such as a copy printer, and an image forming apparatus using the same, and more particularly to an intermediate transfer belt suitable for full color image formation and an image forming apparatus using the same.

  Conventionally, seamless belts have been used in various applications in electrophotographic apparatuses. Particularly in recent full-color electrophotographic apparatuses, an intermediate transfer belt system in which developed images of four colors of yellow, magenta, cyan, and black are once overlaid on an intermediate transfer medium, and then collectively transferred to a transfer medium such as paper. Is used.

  Such an intermediate transfer belt system has a system that uses four color developing devices for one photoconductor, but has a drawback in that the printing speed is slow. For this reason, as a method capable of high-speed printing, a four-tandem tandem method is used in which photoconductors are arranged for four colors, and each color is continuously transferred directly to paper. However, in this method, there are fluctuations due to the environment of the paper, etc., and it is very difficult to match the position accuracy of overlapping each color image, causing a color misregistration image. Therefore, in recent years, it has become the mainstream to adopt an intermediate transfer method for the quadruple tandem method.

  Under such circumstances, the required characteristics (high-speed transfer, positional accuracy) of the intermediate transfer belt are also stricter than before, and it is necessary to satisfy the characteristics corresponding to these requirements. Yes. In particular, for positional accuracy, it is required to suppress fluctuation due to deformation such as elongation of the belt itself due to continuous use. Further, the intermediate transfer belt is laid out over a wide area of the apparatus, and is required to be flame retardant because a high voltage is applied for transfer. In order to meet such requirements, polyimide resins, polyamideimide resins, and the like that are high elastic modulus and high heat resistance resins are mainly used as intermediate transfer belt materials.

  A seamless belt made of polyimide resin or polyamideimide resin is generally applied to a mold by applying a solution of polyimide resin precursor or polyamideimide resin precursor dissolved in a solvent, a so-called varnish resin solution, to a mold. A film is formed by drying and curing, and the film is formed by peeling (demolding) the film (seamless belt) from the mold.

When removing the mold, the surface of the mold is moderately roughened, a mold release layer is formed on the mold, or a mold release agent is applied so that the seamless belt can be easily peeled off from the mold. Is being processed.
For example, Patent Document 1 proposes a method of demolding with air, Patent Document 2 proposes a method of providing a release layer, and Patent Document 3 proposes a method of making the mold an appropriate surface roughness. In Patent Document 4, a method of providing a release layer and defining its surface roughness is proposed.
However, in the above method, it is necessary to remove the mold from the mold while blowing air from the end gap. At this time, depending on the tightness of the seamless belt and the air sending conditions, the membrane is often partially damaged. On the other hand, the release layer and the release agent are not durable and need to be regularly maintained.
In addition, as described in Patent Document 5, the shape of the mold is devised, or as described in Patent Document 6, a mold in which a metal belt (flexible belt) is covered on a core mold is used. Proposals have been made. However, there are problems in that the precision of the mold is likely to vary, and that the latter metal belt is damaged by repeated use and needs to be replaced, resulting in an expensive mold.

The present invention has been made in view of the above prior art, and can be easily released from the mold (demolded) without causing damage and the like, and the mold can be used repeatedly without maintenance, with high efficiency. Provided is a method for producing a resin seamless belt that can be produced. In addition, a seamless belt (particularly, made of polyimide resin or polyamide-imide resin) that is highly elastic and excellent in heat resistance and flame retardancy is manufactured by the above-described method, and a belt member that requires high-speed transfer, positional accuracy, and durability. It is intended to be installed in an electrophotographic apparatus as (especially an intermediate transfer belt).
That is, an object of the present invention is to provide a seamless belt manufacturing method, a seamless belt (intermediate transfer belt) mounted on an electrophotographic apparatus, and an electrophotographic apparatus including the seamless belt (intermediate transfer belt).
Hereinafter, the “electrophotographic apparatus” may be referred to as an “image forming apparatus”.

As a result of intensive studies, the present inventors applied a coating liquid containing a resin component to a mold, dried and cured this, and formed a seamless belt-shaped molded film under supercritical fluid or subcritical fluid. It has been found that the resin-made seamless belt can be easily released (demolded) from the mold without damaging the resin-made seamless belt. That is, the said subject is solved by invention described in the following (1)-(8).
(1) Manufacture of a seamless belt for an electrophotographic apparatus in which a coating liquid containing a resin component is applied to the inner surface or outer surface of a cylindrical mold, and the film is formed by drying and / or curing, and then demolding. A method for producing a seamless belt for an electrophotographic apparatus, characterized in that the formed film is treated with a supercritical fluid or a subcritical fluid together with the cylindrical mold and demolded.
(2) The method for producing a seamless belt for an electrophotographic apparatus according to (1), wherein the supercritical fluid or subcritical fluid is supercritical carbon dioxide or subcritical carbon dioxide.
(3) The seamless belt for an electrophotographic apparatus according to (1), wherein the resin component is a polyimide resin precursor or a polyamideimide resin precursor, and the molded film contains a polyimide resin or a polyamideimide resin. Manufacturing method.
(4) The method for producing a seamless belt for an electrophotographic apparatus according to any one of (1) to (3), wherein the coating liquid contains an electric resistance adjusting material.
(5) A coating liquid containing at least a resin component is applied to the inner or outer surface of a cylindrical mold to form a coating film, and the seamless coating for electrophotographic apparatus is formed by drying and / or curing the coating film. A seamless belt for an electrophotographic apparatus, which is manufactured by removing the molded film from the cylindrical mold after being formed into a film, according to any one of the above (1) to (4) A seamless belt for an electrophotographic apparatus, characterized by being manufactured.
(6) The seamless belt for an electrophotographic apparatus according to (5), which is provided in the electrophotographic apparatus.
(7) The electrophotographic apparatus seamless belt according to (6), wherein the electrophotographic apparatus seamless belt is an intermediate transfer belt.
(8) In an electrophotographic apparatus equipped with a seamless belt for an electrophotographic apparatus, the seamless belt for an electrophotographic apparatus is the seamless belt for an electrophotographic apparatus according to any one of (5) to (7). A feature of an electrophotographic apparatus.

According to the production method of the present invention, even without using a mold release agent, even a molded film of polyimide resin or polyamideimide resin having a very high adhesive property can be easily released from the mold (demolding) without being damaged. In addition, the mold can be used repeatedly for a long time without maintenance, and a resin seamless belt can be produced with high efficiency.
Moreover, it is not necessary to provide the mold with a special structure for releasing (demolding), and it is possible to use an inexpensive mold.
In addition, if a coating film containing a polyimide resin precursor or a polyamideimide resin precursor as a resin component is used as a molded film, it is made of a polyimide resin having excellent mechanical strength (high elasticity), heat resistance and flame retardancy. Or, a seamless belt made of polyamide-imide resin can be manufactured, and since such a seamless belt has little change in continuous use, high-speed transfer, positional accuracy, and durability of an electrophotographic apparatus (image forming apparatus) are required. It can be used as various belt members.
Among them, a plurality of color toner development images sequentially formed on the image carrier are sequentially superimposed on an intermediate transfer belt to perform primary transfer, and the primary transfer image is collectively transferred to a recording medium, so-called secondary transfer. It can be suitably used as an intermediate transfer belt type intermediate transfer belt.
That is, it is possible to configure an electrophotographic apparatus (image forming apparatus) capable of forming a high-quality image provided with a high-quality seamless belt without defects (in particular, a high-quality intermediate transfer belt having no abnormal image due to defects).

It is a schematic diagram which shows the supercritical fluid exposure apparatus for making mold removal (seamless belt) based on this invention easy. It is a principal part schematic diagram for demonstrating the image forming apparatus equipped with the seamless belt obtained by the manufacturing method which concerns on this invention as a belt member. FIG. 3 is a schematic diagram of a main part showing an example of a configuration of an image forming apparatus in which a plurality of photosensitive drums are arranged in parallel along one intermediate transfer belt formed of a seamless belt according to the present invention. It is the schematic of the pressure vessel of a supercritical fluid exposure apparatus.

  As described above, the method for producing a seamless belt according to the present invention comprises applying a coating liquid containing at least a resin component to the inner surface or outer surface of a cylindrical mold to form a coating film, and drying and / or drying the coating film. After being cured to form a seamless belt-shaped molded film, the cylindrical mold on which the molded film is formed is exposed to a supercritical fluid or subcritical fluid atmosphere, and then the molded film is removed from the cylindrical mold. It is characterized by molding.

  The production method of the present invention can be easily released from the mold without damaging the seamless belt. For this reason, the seamless belt to be produced has no defects and is of high quality and is used for various applications, but is particularly useful as a belt member for an electrophotographic apparatus. In electrophotographic apparatuses, seamless belts are used for several members, but as an important member that requires high-speed transfer, positional accuracy, durability, and stable electrical characteristics, especially in the intermediate transfer belt system. There is an intermediate transfer belt to be used, and a seamless belt produced by the production method of the present invention can be suitably used as this member. Hereinafter, the present invention will be described focusing on the intermediate transfer belt.

The seamless belt of the present invention comprises an intermediate transfer belt type electrophotographic apparatus [a so-called so-called image carrier (for example, a photosensitive drum) in which a plurality of color toner developed images sequentially formed are sequentially superimposed on the intermediate transfer belt. It is suitably equipped as an intermediate transfer belt having a thickness of 20 to 500 μm in an apparatus that performs primary transfer and secondary transfer of the primary transfer image to a recording medium at once. And a filler (or additive) that adjusts the electrical resistance in the resin, that is, a so-called electrical resistance adjusting material.
As such a resin, from the viewpoint of flame retardancy, for example, a fluorine-based resin such as PVDF, ETFE, a polyimide resin or a polyamide-imide resin is preferable, and particularly from the viewpoint of mechanical strength (high elasticity) and heat resistance. A polyimide resin or a polyamideimide resin is preferred.

Examples of the electrical resistance adjusting material include a metal oxide, carbon black, an ionic conductive agent, and a conductive polymer material.
Examples of the metal oxide include zinc oxide, tin oxide, titanium oxide, zirconium oxide, aluminum oxide, and silicon oxide. Moreover, in order to improve dispersibility, the metal oxide may be subjected to surface treatment in advance.
Examples of carbon black include ketjen black, furnace black, acetylene black, thermal black, and gas black.
Examples of the ionic conductive agent include tetraalkylammonium salts, trialkylbenzylammonium salts, alkylsulfonates, alkylbenzenesulfonates, alkyl sulfates, glycerol fatty acid esters, sorbitan fatty acid esters, polyoxyethylene alkylamines, and polyoxyethylene fatty acids. Alcohol ester, alkyl betaine, lithium perchlorate, etc. are mentioned, and these may be used in combination.
The electrical resistance adjusting material in the present invention is not limited to the above exemplary compounds.
In addition, the coating liquid containing at least the resin component in the method for producing a seamless belt of the present invention further contains additives such as a dispersion aid, a reinforcing material, a lubricant, a heat conduction material, and an antioxidant as necessary. May be.

The electrical resistance adjusting material contained in the seamless belt suitably equipped as the intermediate transfer belt is preferably 1 × 10 ⁸ to 1 × 10 ¹³ Ω / □ in surface resistance and 1 × 10 ⁶ to 1 × in volume resistance. Although the amount is 10 ¹² Ω · cm, it is necessary to select and add an amount in a range where the molded film is brittle and does not easily break from the viewpoint of mechanical strength.
In other words, in the case of an intermediate transfer belt, an electrical characteristic (for example, a coating liquid in which the blending of the resin component (for example, a polyimide resin precursor or a polyamideimide resin precursor) and an electrical resistance adjusting material is appropriately adjusted is used. It is preferable to manufacture and use a seamless belt having a balance between surface resistance and volume resistance) and mechanical strength.

  In the case of carbon black, the content of the electric resistance adjusting material in the present invention is 10 to 25 wt%, preferably 15 to 20 wt% of the total solid content in the coating liquid. Moreover, as content in the case of a metal oxide, it is 1-50 wt% of the total solid of a coating liquid, Preferably it is 10-30 wt%. If the content is less than the range of the respective electric resistance adjusting materials, the effect cannot be sufficiently obtained, and if the content is greater than the respective range, the mechanical strength of the intermediate transfer belt (seamless belt) decreases. This is not preferable for practical use.

A polyimide resin (hereinafter sometimes abbreviated as “polyimide”) or a polyamideimide resin (hereinafter sometimes abbreviated as “polyamideimide”) suitably used as a material for the seamless belt is specifically described below. explain.
<Polyimide>
Although it does not limit as a polyimide used for this invention, Aromatic polyimide is mentioned as a preferable example. The aromatic polyimide is obtained via a polyamic acid (polyimide precursor) by a reaction between a generally known aromatic polycarboxylic acid anhydride (or a derivative thereof) and an aromatic diamine.
That is, polyimide, particularly aromatic polyimide, is insoluble in solvents and the like due to its rigid main chain structure and has an infusible property. Therefore, first, a polyimide precursor (polyamic acid or polyamic acid) soluble in an organic solvent is synthesized by a reaction between an aromatic polycarboxylic acid anhydride and an aromatic diamine. Molding is carried out by the method, and then the polyamic acid is heated or dehydrated by a chemical method to cyclize (imidize) to obtain polyimide. The outline of the reaction for obtaining the aromatic polyimide is shown in the following formula (1).

[In the formula (1), Ar ¹ represents a tetravalent aromatic residue containing at least one carbon 6-membered ring, and Ar ² represents a divalent aromatic residue containing at least one carbon 6-membered ring. . ]

Specific examples of the tetravalent aromatic carboxylic acid anhydride (aromatic polyvalent carboxylic acid anhydride) containing at least one carbon 6-membered ring include, for example, pyromellitic dianhydride, 3, 3 ′, 4 , 4′-benzophenone tetracarboxylic dianhydride, 2,2 ′, 3,3′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2, 2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, Bis (3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-Zika Boxyphenyl) methane dianhydride, 2,2-bis (3,4-dicarboxylphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 2,3,6,7-naphthalene Tetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic Acid dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic acid An anhydride etc. are mentioned. You may use these individually or in mixture of 2 or more types.
In addition, an acid anhydride other than the aromatic polyvalent carboxylic acid anhydride represented by the above formula (1), for example, an aliphatic polyvalent carboxylic acid such as ethylenetetracarboxylic dianhydride or cyclopentanetetracarboxylic dianhydride. Acid anhydrides can also be used, and these may be used alone or in combination with the aromatic polycarboxylic acid anhydride.
In the formula (1), an aromatic polyvalent carboxylic acid anhydride is used, but a derivative thereof (for example, an ester derivative) may be used.

Next, specific examples of the divalent aromatic diamine (aromatic diamine) containing at least one carbon 6-membered ring to be reacted with the aromatic polyvalent carboxylic acid anhydride include, for example, m-phenylenediamine, o- Phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, bis (3-aminophenyl) ) Sulfide, (3-aminophenyl) (4-aminophenyl) sulfide, bis (4-aminophenyl) sulfide, bis (3-aminophenyl) sulfide, (3-aminophenyl) (4-aminophenyl) sulfoxide, bis (3-aminophenyl) sulfone, (3-aminophenyl) ( -Aminophenyl) sulfone, bis (4-aminophenyl) sulfone, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 3,4 '-Diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, bis [4- (3-aminophenoxy) phenyl] methane, bis [4- (4-aminophenoxy) phenyl] methane, 1,1-bis [4- ( 3-aminophenoxy) phenyl] ethane, 1,1-bis [4- (4-aminophenoxy) phenyl] -ethane, 1,2-bis [4- (3-aminophenoxy) phenyl] ethane, 1,2- Bis [4- (4-aminophenoxy) phenyl] ethane, 2,2-bis [4- (3-aminophenoxy) phenyl] Lopan, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] butane, 2,2-bis [3- (3-amino Phenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3- Hexafluoropropane, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 1,4-bis (4 -Aminophenoxy) benzene, 4,4'-bis (3-aminophenoxy) biphenyl, 4,4'-bis (4-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone Bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (3-amino Phenoxy) phenyl] sulfoxide, bis [4- (4-aminophenoxy) phenyl] sulfoxide, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [ 4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 1,4-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,3-bis [ 4- (3-aminophenoxy) benzoyl] benzene, 4,4′-bis [3- (4-aminophenoxy) Benzoyl] diphenyl ether, 4,4′-bis [3- (3-aminophenoxy) benzoyl] diphenyl ether, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzophenone, 4, 4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] diphenylsulfone, bis [4- {4- (4-aminophenoxy) phenoxy} phenyl] sulfone, 1,4-bis [4 -(4-aminophenoxy) phenoxy] -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene, and the like. You may use these individually or in mixture of 2 or more types. In order to effectively express the physical properties in the present invention, it is particularly preferable to use 4,4′-diaminodiphenyl ether as at least one of the components.
In addition, aliphatic diamines other than the aromatic diamine represented by the above formula (1) can also be used and may be used in combination with the aromatic diamine.

  In the case of obtaining an aromatic polyimide, a polyimide precursor (polyamic acid) is obtained by polymerization reaction in an organic polar solvent using substantially the same molar amount of the aromatic polycarboxylic anhydride component and the aromatic diamine component. Then, the polyamic acid is dehydrated to cyclize and imidize. The method for producing polyamic acid will be specifically described below.

Here, examples of the organic polar solvent used in the polymerization reaction for obtaining the polyamic acid include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, and formamide such as N, N-dimethylformamide and N, N-diethylformamide. Solvents, acetamide solvents such as N, N-dimethylacetamide, N, N-diethylacetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone, phenol, o-, m- Or phenol solvents such as p-cresol, xylenol, halogenated phenol, catechol, ether solvents such as tetrahydrofuran, dioxane, dioxolane, alcohol solvents such as methanol, ethanol, butanol, cellosolve such as butyl cellosolve Or hexamethylphosphoramide, etc. can be mentioned γ- butyrolactone, to use them alone or as a mixed solvent desirable.
The solvent is not particularly limited as long as it dissolves the polyamic acid, but N, N-dimethylacetamide and N-methyl-2-pyrrolidone are particularly preferable.

  As an example for producing a polyimide precursor, first, one or more kinds of diamines are dissolved in the above organic solvent or dispersed in a slurry state in an inert gas atmosphere such as argon or nitrogen. When at least one aromatic polycarboxylic acid anhydride (or derivative thereof) is added to this solution (either in a solid state, in a solution state dissolved in an organic solvent, or in a slurry state), heat is generated. Thus, a ring-opening polyaddition reaction occurs, and the viscosity of the solution rapidly increases, and a high molecular weight polyamic acid solution is obtained. In this case, the reaction temperature is usually controlled to −20 ° C. to 100 ° C., desirably 60 ° C. or less. The reaction time is about 30 minutes to 12 hours.

  The above is an example. Contrary to the addition procedure in the reaction, first, an aromatic polyvalent carboxylic acid anhydride (aromatic tetracarboxylic dianhydride) or a derivative thereof is dissolved or dispersed in an organic solvent, The aromatic diamine (substantially, “diamine”) may be added to the solution. The diamine may be added in a solid state, in a solution state dissolved in an organic solvent, or in a slurry state. That is, the mixing order of the aromatic tetracarboxylic dianhydride component and the diamine component is not limited. Further, the aromatic tetracarboxylic dianhydride and the diamine may be simultaneously added to the organic polar solvent for reaction.

  As described above, the polyamic acid is uniformly mixed in the organic polar solvent by polymerizing the aromatic polyvalent carboxylic acid anhydride or derivative thereof and the aromatic diamine component in about an equimolar amount in the organic polar solvent. A polyimide precursor solution is obtained in a dissolved state.

The polyimide precursor solution in the present invention (polyamic acid solution: “coating solution containing a polyimide resin precursor”) can be synthesized as described above, but it can be easily used as an organic solvent. What is marketed as what is called a polyimide varnish of the state in which the polyamic acid composition was dissolved can also be obtained and used.
Examples of this include Trenys (manufactured by Toray Industries, Inc.), U-Varnish (manufactured by Ube Industries, Ltd.), Rika Coat (manufactured by Nippon Nippon Chemical Co., Ltd.), Optmer (manufactured by JSR), SE812 (manufactured by Nissan Chemical Industries), CRC8000 ( Sumitomo Bakelite Co., Ltd.) is a typical example.

  Mix and disperse fillers (for example, electrical resistance adjusting agents, or additives such as dispersion aids, reinforcing materials, lubricants, heat conduction materials, antioxidants, etc.) into the synthesized or obtained polyamic acid solution as necessary. Thus, a coating solution is prepared. The coating liquid is applied to a support (molding mold) as described later, and then subjected to a treatment such as heating, whereby conversion (imidation) from polyamic acid, which is a polyimide precursor, to polyimide is performed.

The polyamic acid can be imidized by the heating method (1) or the chemical method (2) as described above.
The heating method (1) is a method of converting polyamic acid to polyimide by, for example, heat treatment at 200 to 350 ° C., and is a simple and practical method for obtaining polyimide (polyimide resin).
On the other hand, the chemical method (2) is a method in which a polyamic acid is reacted with a dehydrating cyclization reagent (for example, a mixture of a carboxylic acid anhydride and a tertiary amine, etc.) and then heated to completely imidize, Compared with the heating method of (1), since it is a complicated and expensive method, the method of (1) is usually used frequently.
In order to exhibit the intrinsic performance of polyimide, it is preferable to complete imidization by heating to a temperature above the glass transition temperature of the corresponding polyimide.

The progress of imidization (degree of imidization) can be evaluated by a commonly performed method for measuring the imidization rate.
As a method for measuring such an imidization rate, for example, a nucleus calculated from an integral ratio of ¹ H attributed to an amide group in the vicinity of 9 to 11 ppm and ¹ H attributed to an aromatic ring in the vicinity of 6 to 9 ppm. Various methods such as magnetic resonance spectroscopy (NMR method), Fourier transform infrared spectroscopy (FT-IR method), a method for quantifying moisture accompanying imide ring closure, and a carboxylic acid neutralization titration method are used. Fourier transform infrared spectroscopy (FT-IR method) is the most common method.

In the Fourier transform infrared spectroscopy (FT-IR method), the imidization rate is defined as, for example, the following formula (a).
That is, assuming that (A) is the number of moles of imide groups at the firing stage (imidation treatment stage) and (B) is the number of moles of imide groups when 100% imidized (theoretical), Is done.
Imidation ratio (%) = [(A) / (B)] × 100 (a)

  The number of moles of the imide group in this definition can be determined from the absorbance ratio of the characteristic absorption of the imide group measured by the FT-IR method. For example, as a typical characteristic absorption, the imidization ratio can be evaluated using the following absorbance ratio.

(1) Absorbance ratio between 725 cm ^-1 (immobilization vibration band of imide ring C = O group) which is one of the characteristic absorptions of imide and 1,015 cm ^-1 of characteristic absorption of benzene ring (2) Characteristics of imide Absorbance ratio between 1,380 cm ^-1 (an azimuthal vibration band of imide ring CN group), which is one of the absorptions, and 1,500 cm ^-1 characteristic absorption of the benzene ring (3) One of the characteristic absorptions of imide Absorption ratio of 1,720 cm ^-1 (immobilization vibration band of imide ring C = O group) and 1,500 cm ^-1 characteristic absorption of benzene ring (4) 1, which is one of characteristic absorption of imide Absorbance ratio between 720 cm ⁻¹ and characteristic absorption of amide group 1,670 cm ⁻¹ (interaction between amide group N—H bending vibration and CN stretching vibration) and amide group over 3000 to 3300 cm ⁻¹ If it is confirmed that the multiple absorption band of the origin has disappeared, further imidization Reliability of the binding is enhanced.

Next, polyamideimide will be described.
<Polyamideimide>
Polyamideimide is a resin having a rigid imide group and an amide group imparting flexibility in the molecular skeleton, and the polyamideimide used in the present invention may have a generally known structure. Although not limited, aromatic polyamide imide is a particularly preferable example.
As a method for synthesizing the polyamideimide resin, the following known acid chloride method (a) or isocyanate method (b) can be applied.
(A) Acid chloride method: derivative of trivalent carboxylic acid compound having acid anhydride group and carbonyl halide group [hereinafter referred to as “derivative halide of trivalent carboxylic acid compound having acid anhydride group”. is there. ] (Most typically, an acid chloride compound of the derivative) and a diamine are reacted in a solvent to produce a polyamideimide via a polyamide-amic acid (polyamideimide resin precursor). For example, a method described in Japanese Patent Publication No. 42-15637 is known.
(B) Isocyanate method: a trivalent carboxylic acid compound having an acid anhydride group and a carboxylate group [hereinafter sometimes referred to as “a derivative of a trivalent carboxylic acid having an acid anhydride group”. ] And an isocyanate compound (in particular, an aromatic isocyanate compound is preferred) in a solvent to produce a polyamideimide. For example, a method described in Japanese Patent Publication No. 44-19274 is known.
In the present invention, both the acid chloride method (a) and the isocyanate method (b) can be used. Each production method will be described below with an aromatic polyamideimide preferably used as an example.

(A) Acid chloride method:
As a derivative halide of a trivalent carboxylic acid compound having an acid anhydride group, for example, compounds represented by the following structural formula (2) and structural formula (3) can be used.

  [In the formula (2), X represents a halogen atom. ]

[In the formula (3), X represents a halogen atom, and Y represents a single bond, —CH ₂ —, —CO—, —SO ₂ — or —O—. ]

In Structural Formula (2) or Structural Formula (3), examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom, with a chlorine atom being preferred. Most representative is trimellitic anhydride chloride.
A derivative halide of a trivalent carboxylic acid compound having an acid anhydride group represented by the structural formula (2) or the structural formula (3) is an example of a raw material for obtaining an aromatic polyamideimide. It is not something that can be done.
In addition to the aromatic trivalent carboxylic acid compound represented by the structural formula (2) or structural formula (3), a derivative halide of a trivalent carboxylic acid compound having an aliphatic acid anhydride group can also be used. Yes, it can be used in combination with aromatic derivatives.

On the other hand, the diamine to be reacted with the aromatic polyvalent carboxylic acid anhydride in the acid chloride method is not particularly limited, but any of aromatic diamine, aliphatic diamine, and alicyclic diamine can be used, but aromatic diamine is preferred. Used.
Aromatic diamines include m-phenylenediamine, p-phenylenediamine, oxydianiline, diamino-m-xylylene, diamino-p-xylylene, 1,4-naphthalenediamine, 1,5-naphthalenediamine, 2,6- Naphthalenediamine, 2,7-naphthalenediamine, 2,2'-bis- (4-aminophenyl) propane, 2,2'-bis- (4-aminophenyl) hexafluoropropane, 4,4'-diaminodiphenyl Sulfone, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl sulfone, 3,3′-diaminodiphenyl ether, 3,4-diaminobiphenyl, 4,4′-diaminobenzophenone, 3,4-diaminodiphenyl ether, isopropyl Lidendianiline, 3,3′-Diaminobenzophenone, -Tolidine, 2,4-tolylenediamine, 1,3-bis- (3-aminophenoxy) benzene, 1,4-bis- (4-aminophenoxy) benzene, 1,3-bis- (4-aminophenoxy) ) Benzene, 2,2-bis- [4- (4-aminophenoxy) phenyl] propane, bis- [4- (4-aminophenoxy) phenyl] sulfone, bis- [4- (3-aminophenoxy) phenyl] Sulfone, 4,4′-bis- (4-aminophenoxy) biphenyl, 2,2′-bis- [4- (4-aminophenoxy) phenyl] hexafluoropropane, 4,4′-diaminodiphenyl sulfide, 3 , 3′-diaminodiphenyl sulfide and the like.
Examples of the aliphatic diamine include methylene diamine and hexafluoroisopropylidene diamine.
Also, siloxane compounds having amino groups at both ends as diamines, such as 1,3-bis (3-aminopropyl) -1,1,3,3-tetramethyldisiloxane, α, ω-bis (3- Aminopropyl) polydimethylsiloxane, 1,3-bis (3-aminophenoxymethyl) -1,1,3,3-tetramethyldisiloxane, α, ω-bis (3-aminophenoxymethyl) polydimethylsiloxane, , 3, -bis (2- (3-aminophenoxy) ethyl) -1,1,3,3-tetramethyldisiloxane, α, ω-bis (2- (3-aminophenoxy) ethyl) polydimethylsiloxane, 1,3-bis (3- (3-aminophenoxy) propyl) -1,1,3,3-tetramethyldisiloxane, α, ω-bis (3- (3-aminophenoxy) pro If pill) polydimethylsiloxane is used, silicone-modified polyamideimide can be obtained.

  In order to obtain the polyamideimide (polyamideimide resin) in the present invention by the acid chloride method, as in the case of the production of the polyimide resin, a derivative halide and a diamine of a trivalent carboxylic acid compound having an acid anhydride group described above. Are dissolved in an organic polar solvent, reacted at a low temperature (0 to 30 ° C.) to obtain a polyamideimide resin precursor (polyamide-amic acid), and then imidized.

The organic polar solvent that can be used is the same as in the case of the polyimide, and is a sulfoxide solvent (for example, dimethyl sulfoxide, diethyl sulfoxide, etc.), a formamide solvent (for example, N, N-dimethylformamide, N, N- Diethylformamide, etc.), acetamide solvents (eg, N, N-dimethylacetamide, N, N-diethylacetamide, etc.), pyrrolidone solvents (eg, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, etc.) , Phenolic solvents (eg, phenol, o-, m-, or p-cresol, xylenol, halogenated phenol, catechol, etc.), ethereal solvents (eg, tetrahydrofuran, dioxane, dioxolane, etc.), alcoholic solvents (eg, Methanol, ethanol, Ethanol, etc.), cellosolve-based solvents (e.g., butyl cellosolve, etc.), or hexamethylphosphoramide, γ- butyrolactone.
These are desirably used alone or as a mixed solvent. The solvent is not particularly limited as long as it dissolves polyamide-amic acid, but N, N-dimethylacetamide and N-methyl-2-pyrrolidone are particularly preferable.

The polyamide-amic acid solution obtained as described above is applied to a desired support, for example, a mold for molding to form a coating film, and this coating film is treated by heating or the like, whereby imidization is performed to form a polyamide. -Conversion from amic acid to polyamide-imide (polyamideimide).
As the imidization method, a method of dehydrating and ring-closing the amic acid by heat treatment as in the case of the polyimide and a method of chemically ring-closing using a dehydration ring-closing catalyst are used.
When dehydrating and ring-closing by heat treatment, for example, the reaction temperature is 150 to 400 ° C., preferably 180 to 350 ° C., and the heat treatment time is 30 seconds to 10 hours, preferably 5 minutes to 5 hours. When a dehydration ring closure catalyst is used, the reaction temperature is 0 to 180 ° C., preferably 10 to 80 ° C., and the reaction time is several tens of minutes to several days, preferably 2 to 12 hours. Examples of the dehydration ring closure catalyst include acid anhydrides such as acetic acid, propionic acid, butyric acid, and benzoic acid.

(B) Isocyanate method:
Examples of the trivalent carboxylic acid compound having an acid anhydride group and a carboxylate group (derivative of a trivalent carboxylic acid having an acid anhydride group) used in the case of the isocyanate method include the following structural formula (4) and structure: The compound shown in Formula (5) can be used.

  [In Formula (4), R shows a hydrogen atom, a C1-C10 alkyl group, or a phenyl group. ]

[In the formula (5), R represents a hydrogen atom, an alkyl group or a phenyl group having 1 to 10 carbon atoms, Y is a single _{bond, -CH 2 -, - CO -} , - shows or -O- - SO ₂ . ]

Any of the derivatives represented by the above general formula can be used, but the most typical example is trimellitic anhydride. These trivalent carboxylic acid derivatives having an acid anhydride group can be used alone or in combination depending on the purpose.
A derivative of a trivalent carboxylic acid compound having an acid anhydride group and a carboxylate group represented by the structural formula (4) or the structural formula (5) is an example of a raw material for obtaining an aromatic polyamideimide, However, it is not limited to these.
In addition to the aromatic trivalent carboxylic acid compound represented by the above structural formula (4) or structural formula (5), an aliphatic trivalent carboxylic acid compound can also be used. It can also be used in combination with an acid compound.

Next, as one isocyanate compound to be reacted with a trivalent carboxylic acid compound having an acid anhydride group and a carboxylate group in the isocyanate method, for example, 4,4′-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4 '-[2,2-bis (4-phenoxyphenyl) propane] diisocyanate, biphenyl-4,4'-diisocyanate, biphenyl-3,3'-diisocyanate, biphenyl-3 , 4'-diisocyanate, 3,3'-dimethylbiphenyl-4,4'-diisocyanate, 2,2'-dimethylbiphenyl-4,4'-diisocyanate, 3,3'-diethylbiphenyl-4,4'-diisocyanate , 2, 2 -Diethylbiphenyl-4,4'-diisocyanate, 3,3'-dimethoxybiphenyl-4,4'-diisocyanate, 2,2'-dimethoxybiphenyl-4,4'-diisocyanate, naphthalene-1,5-diisocyanate, naphthalene -2,6-diisocyanate and the like.
As the isocyanate compound, an aromatic isocyanate compound (aromatic polyisocyanate) is particularly preferably used. These aromatic polyisocyanates can be used alone or in combination.
If necessary, as a part of this, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, transcyclohexane-1,4-diisocyanate, hydrogenated m- Aliphatic, such as xylylene diisocyanate and lysine diisocyanate, alicyclic isocyanate and trifunctional or higher polyisocyanate can also be used.

In order to obtain the polyamideimide in the present invention by the isocyanate method, the above-described trivalent carboxylic acid derivative having an acid anhydride group and an aromatic polyisocyanate are mixed with an organic polar solvent in the same manner as in the production of the polyimide. After the solution containing the polyamideimide precursor obtained by dissolution and adjustment in the substrate is applied to the support, the polyamideimide precursor is converted into the polyamideimide by heat treatment. During the conversion to the polyamide imide by this isocyanate method, carbon dioxide gas is generated and the polyamide imide is generated without passing through the polyamic acid.
The production | generation example of aromatic polyamideimide by the polyamide imidation at the time of using trimellitic anhydride and aromatic diisocyanate to following formula (6) is shown.

  [In the formula (6), Ar represents a divalent aromatic group. ]

  As the precursor to be converted into polyimide (polyimide resin) or polyamideimide (polyamideimide resin) as described above, a material obtained by reacting a single composition as a raw material is usually used. It is also possible to combine and use precursors that have been reacted using other selected components as raw materials. Moreover, the copolymer which has a polyimide repeating unit and a polyamideimide repeating unit may be sufficient.

Next, a method for producing a seamless belt using the coating liquid containing at least the resin component of the present invention, that is, the coating liquid containing the polyimide resin precursor or the polyamideimide resin precursor will be described.
In the present invention, as a method for producing a seamless belt using the coating liquid containing the polyimide resin precursor or the polyamideimide resin precursor, the coating liquid may be a mold (cylindrical mold) such as centrifugal molding. There are a method of applying to the inner surface and a method of applying to the outer surface of the mold (cylindrical mold) with a nozzle or dispenser, and the coating formed on the inner surface or the outer surface of the mold is dried and / or cured to form a seamless belt. After forming the molded film, the cylindrical mold on which the molded film is formed is exposed to a supercritical fluid or subcritical fluid atmosphere, and then the molded film is removed from the cylindrical mold to obtain the desired seamless belt. Is obtained. However, in the case of centrifugal molding, the surface of the resulting belt is a surface in contact with the mold side, so that the surface characteristics (surface state) are affected by the state of the mold surface. For this reason, since the inner surface precision of a metal mold | die is managed severely, there exists a tendency for metal mold | die cost to become very high.
Therefore, in the following, a method for applying a coating liquid to the outer surface of a mold will be described as an example. In addition, the following description is an example and conditions etc. are not limited to this.

While slowly rotating a cylindrical mold, for example, a cylindrical metal mold, a coating liquid containing at least a resin component (for example, a coating liquid containing a polyimide resin precursor or a polyamideimide resin precursor) is used as a nozzle or Application and casting (formation of a coating film) is performed uniformly on the entire outer surface of the cylinder by a liquid supply device such as a dispenser. Thereafter, the rotation speed is increased to a predetermined speed, and when the predetermined speed is reached, the rotation speed is maintained at a constant speed and the rotation is continued for a desired time. And the solvent in a coating film is evaporated at the temperature of about 80-150 degreeC, heating up gradually while rotating. In this process, it is preferable to efficiently circulate and remove atmospheric vapor (such as a volatilized solvent). When a self-supporting film is formed, the mold is transferred to a heating furnace (firing furnace) capable of high-temperature processing, and the temperature is raised stepwise, and finally high-temperature heat processing (firing is performed at about 250 ° C. to 450 ° C. And sufficiently imidizing or polyimidizing the polyimide resin precursor or the polyamideimide resin precursor. After the imidization is completed, the cylindrical mold on which the molded film is formed is slowly cooled and exposed to a supercritical fluid or subcritical fluid atmosphere, and then the molded film (substantially “film”) is cylindrical. Release from the mold. The mold may be formed with a release agent or a release layer so that it can be easily removed, but is preferably roughened so that a supercritical fluid or a subcritical fluid can easily enter.
Conventionally, at the time of demolding, a part of both ends of the film on the formed mold surface is cut, and a gap is formed between the mold and the film while air is slowly blown from the cut part. The method of extracting is performed. However, in the conventional method, when the mold is repeatedly used, if the release layer formed on the mold surface is deteriorated or partly contaminated, the mold cannot be released and the film may be damaged. There were problems that often occurred. In recent years, there has been a demand for further reduction in film thickness due to a demand for cost reduction, and in the conventional demolding method, defects at the time of demolding from a mold are increasing.
That is, the cylindrical mold on which the molded film of the present invention is formed is exposed to a supercritical fluid or subcritical fluid atmosphere, and then the molded film is released (demolded) from the cylindrical mold. The (seamless belt) can be easily released from the mold without damaging it, and the mold can be used repeatedly for a long period of time without maintenance, making it possible to produce a seamless belt with high productivity.

Then, next, the demolding method by the supercritical fluid or subcritical fluid of this invention is demonstrated.
First, the supercritical fluid or subcritical fluid will be described.
A supercritical fluid refers to a fluid that exceeds the limit temperature and pressure (critical point) at which gas and liquid can coexist. The supercritical fluid has a characteristic that, in a high density state, the ability to dissolve a substance is generally much larger than the dissolving power of the fluid at room temperature. This is thought to be because the fluid is under high pressure, so the kinetic energy of the fluid is large, and the viscosity is small. In addition, since the solubility can be controlled by adjusting the density by temperature and pressure, it is also a remarkable characteristic that the application range is wide. In general, a supercritical fluid having a density of 0.2 g · cm ³ or more is often used as a solvent for chemical substances. Also, as described above, the supercritical fluid has a high fluid kinetic energy and a low viscosity, so that the supercritical fluid diffuses quickly into the medium. For this reason, although it is difficult to permeate into a porous body with a solvent that is generally used, it is known that if a supercritical fluid is used, it penetrates into the porous body relatively easily. Furthermore, since the thermal conductivity is larger than that of the liquid, it is possible to quickly remove the heat of reaction due to the chemical reaction generated in the supercritical state.

The supercritical fluid exists as a non-condensable high-density fluid in a temperature / pressure region that exceeds the limit (critical point) where gas and liquid can coexist, does not cause condensation even when compressed, and exceeds the critical temperature. And as long as it is the fluid in the state more than a critical pressure, there is no restriction | limiting in particular, According to the objective, it can select suitably. Moreover, there is no restriction | limiting in particular as critical temperature and critical pressure of a supercritical fluid. Examples of these fluids include carbon monoxide, carbon dioxide, ammonia, nitrogen, water, methanol, ethanol, ethane, propane, butane, hexane, 2,3-dimethylbutane, benzene, chlorotrifluoromethane, and dimethyl ether. It is done. The critical temperature is preferably −273 to 300 ° C., particularly preferably 0 to 1400 ° C. When using a medium in which the medium for supercriticality is denatured by heat, a medium having a low critical temperature is preferable. Examples include carbon dioxide (critical temperature 31.0 ° C.), ethane (critical temperature 32.2 ° C.), propane (critical temperature 96.6 ° C.), ammonia (critical temperature 132.3 ° C.), and the like. The subcritical fluid is not particularly limited as long as it exists as a high-pressure liquid in the temperature / pressure region near the critical point, and can be appropriately selected according to the purpose. Various materials mentioned as the supercritical fluid can be preferably used as the subcritical fluid. For the present invention, a supercritical fluid or a subcritical fluid may be used alone, or two or more kinds may be mixed and used.

When applying a supercritical fluid or subcritical fluid to an organic material as described in the present invention, it is preferable to use carbon dioxide as the main medium. Carbon dioxide has a supercritical pressure of 7.3 MPa and a supercritical temperature of 31.0 ° C. It can create a supercritical state relatively easily, has little thermal damage to organic materials, and is nonflammable and low-toxic and easy to handle. Since it is mentioned as an advantage, it is widely used in the food industry.

Next, the process by the supercritical carbon dioxide of the metal mold | die in which the coating film produced as mentioned above was formed is demonstrated.
By placing a seamless belt in the supercritical carbon dioxide field, the mold on which the coating film has been formed penetrates into the coating film and the interface between the coating film and the mold depending on the type of fluid, pressure, and temperature conditions. To do. Thereby, the adhesiveness of a coating film and a metal mold | die can be eliminated.
Supercritical carbon dioxide is preferable because it has a low critical temperature among supercritical fluids.
As preferable conditions for the supercritical carbon dioxide or subcritical carbon dioxide treatment, the temperature is preferably 30 to 200 ° C, more preferably 30 ° C to 60 ° C, and the pressure is preferably 7.1 to 60 MPa, and preferably 20 to 40 MPa. Further preferred.
Further, if necessary, a lubricant that can be dissolved in supercritical carbon dioxide may be added. By introducing this, the lubricant dissolved in carbon dioxide supercritically enters the interface between the coating film and the mold, and can be removed more easily when the coating film is removed from the mold. .
As the lubricant that is easily dissolved in supercritical carbon dioxide, a surfactant or wax having a fluorine-based or silicon-based functional group is suitable.
Moreover, you may use together other liquids (entrainer) other than a carbon dioxide.

There is no restriction | limiting in particular as an apparatus used for a process, Although it can select suitably according to the objective, For example, the pressure vessel (4) for performing a process and supercritical carbon dioxide shown in FIG. 1 are supplied. And a separation tank (not shown) having a pressure pump (1) for performing the separation and a pressure reducing valve (7) for separating the gas containing the extracted residue into the extract and the solvent. . As a processing method using the apparatus, first, a mold having a coating film formed thereon is put into the pressure vessel (4). Next, the supercritical carbon dioxide is supplied into the pressure vessel (4) by the pressure pump (1), and the mold is treated with the supercritical carbon dioxide. The pressure and temperature conditions at this time are performed under any conditions within the above-described range.
The processing time under these conditions is very short, and about 1 to 10 minutes is sufficient.
The supercritical carbon dioxide is returned to room temperature and normal pressure, the seamless belt is taken out from the pressure vessel (4), and the coating film is removed from the mold.
According to the said method, a coating film can be easily removed from a metal mold | die, without being damaged.
In addition, since supercritical carbon dioxide is used, the mold can be taken out from the apparatus, and the coating film can be taken out immediately, and the mold surface is also washed, so without washing, It can be repeated as it is and put into the production line.
Here, although it is the pressure vessel (4) of FIG. 1, the size of the seamless belt mold is naturally necessary, but the mold of the seamless belt is generally cylindrical.
If this is used as a cylindrical container, the space volume inside is large.
In particular, as the size of the seamless belt increases, this space increases and it takes a long time to create a supercritical state.
Therefore, it is preferable that the pressure vessel (4) has a donut shape corresponding to a mold shape.
The outline is shown in FIG.

A high-quality seamless belt without defects produced by the above-described method is, for example, a primary transfer by sequentially superimposing a plurality of color toner developed images sequentially formed on an image carrier on an intermediate transfer belt. It is suitably used as an intermediate transfer belt of an electrophotographic apparatus of a so-called intermediate transfer type that collectively transfers a primary transfer image onto a recording medium, and constitutes an electrophotographic apparatus (image forming apparatus) capable of forming a high-quality image. be able to.
A seamless belt used in a belt constituting unit provided in an electrophotographic apparatus (hereinafter referred to as “image forming apparatus”) in the present invention will be described in detail below with reference to a schematic diagram of a main part. The schematic diagram is an example, and the present invention is not limited to this.

FIG. 2 is a schematic diagram of a main part for explaining an image forming apparatus equipped with a seamless belt obtained by the manufacturing method according to the present invention as a belt member.
The intermediate transfer unit (500) including the belt member shown in FIG. 2 includes an intermediate transfer belt (501) that is an intermediate transfer member stretched around a plurality of rollers. Around the intermediate transfer belt (501), there are a secondary transfer bias roller (605) as a secondary transfer charge applying means of the secondary transfer unit (600), and a belt cleaning blade (504) as an intermediate transfer body cleaning means. A lubricant application brush (505), which is a lubricant application member of the lubricant application means, is disposed so as to face each other.
Further, position detection marks (not shown) are provided on the outer peripheral surface or inner peripheral surface of the intermediate transfer belt (501). However, on the outer peripheral surface side of the intermediate transfer belt (501), it is necessary to devise a position detection mark that avoids the passing area of the belt cleaning blade (504), which may be difficult to arrange. In this case, a position detection mark may be provided on the inner peripheral surface side of the intermediate transfer belt (501). The optical sensor (514) serving as a mark detection sensor is provided at a position between the primary transfer bias roller (507) and the belt driving roller (508) on which the intermediate transfer belt (501) is stretched.

  The intermediate transfer belt (501) includes a primary transfer bias roller (507), a belt driving roller (508), a belt tension roller (509), a secondary transfer counter roller (510), which are primary transfer charge applying means, and a cleaning device. It is stretched between the counter roller (511) and the feedback current detection roller (512). Each roller is made of a conductive material, and each roller other than the primary transfer bias roller (507) is grounded. The primary transfer bias roller (507) is controlled by a primary transfer power source (801) controlled by a constant current or a constant voltage so that the current or voltage is controlled to a predetermined magnitude according to the number of superimposed toner images. A bias is applied.

The intermediate transfer belt (501) is driven in the direction of the arrow by a belt drive roller (508) that is driven to rotate in the direction of the arrow by a drive motor (not shown).
The intermediate transfer belt (501) as the belt member is usually a semiconductor or an insulator and has a single-layer or multi-layer structure, but in the present invention, a seamless belt is preferably used, thereby improving durability. In addition, excellent image formation can be realized. In addition, the intermediate transfer belt is set to be larger than the maximum sheet passing size in order to superimpose the toner images formed on the photosensitive drum (200).

  A secondary transfer bias roller (605), which is a secondary transfer means, is in contact with / separating means, which will be described later, with respect to the belt outer peripheral surface of a portion of the intermediate transfer belt (501) stretched around the secondary transfer counter roller (510). It is comprised so that contact / separation is possible by the contact / separation mechanism. The secondary transfer bias roller (605) sandwiches the transfer paper (P) as a recording medium between the secondary transfer counter roller (510) and the intermediate transfer belt (501) stretched between the secondary transfer counter roller (510). A transfer bias having a predetermined current is applied by a secondary transfer power source (802) that is arranged and controlled at a constant current.

  The registration roller (610) is a transfer sheet as a transfer material at a predetermined timing between the secondary transfer bias roller (605) and the intermediate transfer belt (501) stretched around the secondary transfer counter roller (510). Send (P). Further, a cleaning blade (608) as a cleaning unit is in contact with the secondary transfer bias roller (605). The cleaning blade (608) removes and removes adhering material adhering to the surface of the secondary transfer bias roller (605).

  In the color copying machine having such a configuration, when the image forming cycle is started, the photosensitive drum (200) is rotated in a counterclockwise direction indicated by an arrow by a driving motor (not shown), and the photosensitive drum (200) is rotated on the photosensitive drum (200). In addition, Bk (black) toner image formation, C (cyan) toner image formation, M (magenta) toner image formation, and Y (yellow) toner image formation are performed. The intermediate transfer belt (501) is rotated clockwise by the belt driving roller (508) as indicated by an arrow. As the intermediate transfer belt (501) rotates, the primary transfer of the Bk toner image, the C toner image, the M toner image, and the Y toner image is performed by the transfer bias by the voltage applied to the primary transfer bias roller (507). Finally, the toner images are formed on the intermediate transfer belt (501) in the order of Bk, C, M, and Y.

For example, the Bk toner image formation is performed as follows.
In FIG. 2, a charging charger (203) uniformly charges the surface of the photosensitive drum (200) to a predetermined potential with a negative charge by corona discharge. The timing is determined based on the belt mark detection signal, and raster exposure with laser light is performed based on the Bk color image signal by a writing optical unit (not shown). When this raster image is exposed, the charge proportional to the exposure light amount disappears in the exposed portion of the surface of the photosensitive drum (200) that is initially charged uniformly, and a Bk electrostatic latent image is formed. When the negatively charged Bk toner on the developing roller of the Bk developing device (231K) comes into contact with this Bk electrostatic latent image, the toner adheres to the portion where the charge of the photosensitive drum (200) remains. In other words, toner is attracted to a portion having no charge, that is, an exposed portion, and a Bk toner image similar to the electrostatic latent image is formed.

  The Bk toner image formed on the photosensitive drum (200) in this way is primary on the belt outer peripheral surface of the intermediate transfer belt (501) rotating at a constant speed while being in contact with the photosensitive drum (200). Transcribed. Some untransferred residual toner remaining on the surface of the photoreceptor drum (200) after the primary transfer is cleaned by the photoreceptor cleaning device (201) in preparation for reuse of the photoreceptor drum (200). Is done. On the photosensitive drum (200) side, the process proceeds to the C image forming process after the Bk image forming process, and reading of the C image data by the color scanner starts at a predetermined timing. A C electrostatic latent image is formed on the surface of the body drum (200).

  Then, after the rear end portion of the previous Bk electrostatic latent image passes and before the front end portion of the C electrostatic latent image arrives, the revolver developing unit (230) is rotated, and the C developing machine ( 231C) is set at the development position, and the C electrostatic latent image is developed with C toner. Thereafter, the development of the C electrostatic latent image area is continued. When the rear end portion of the C electrostatic latent image passes, the revolver developing unit is rotated in the same manner as in the previous Bk developing machine (231K). Then, the next M developing machine (231M) is moved to the developing position. This is also completed before the leading edge of the next Y electrostatic latent image reaches the developing position. Note that the M and Y image forming steps are the same as the Bk and C steps described above because the operations of reading color image data, forming an electrostatic latent image, and developing are the same as those described above.

The Bk, C, M, and Y toner images sequentially formed on the photosensitive drum (200) in this manner are sequentially aligned on the same surface on the intermediate transfer belt (501) and primarily transferred. As a result, a toner image having a maximum of four colors superimposed on the intermediate transfer belt (501) is formed. On the other hand, at the time when the image forming operation is started, the transfer paper (P) is fed from a paper feed unit such as a transfer paper cassette or a manual feed tray, and is waiting at the nip of the registration roller (610).
Then, on the intermediate transfer belt (501), the intermediate transfer belt (501) stretched around the secondary transfer counter roller (510) and the secondary transfer bias roller (605) form a nip. When the leading edge of the toner image approaches, the registration roller (610) is driven so that the leading edge of the transfer paper (P) coincides with the leading edge of the toner image, and is transferred along the transfer paper guide plate (601). The paper (P) is conveyed, and the registration between the transfer paper (P) and the toner image is performed.

  In this way, when the transfer paper (P) passes through the secondary transfer portion, the intermediate transfer belt (501) is transferred by the transfer bias generated by the voltage applied to the secondary transfer bias roller (605) by the secondary transfer power source (802). ) The four-color superimposed toner image on the top is transferred onto the transfer paper (P) at once (secondary transfer). This transfer paper (P) is conveyed along the transfer paper guide plate (601) and passes through a portion facing the transfer paper neutralization charger (606) comprising a static elimination needle disposed downstream of the secondary transfer portion. After being neutralized by this, the belt is conveyed toward the fixing device (270) by the belt conveying device (210) which is a belt component (see FIG. 2). Then, after the toner image is melted and fixed at the nip portion of the fixing rollers (271) and (272) of the fixing device (270), the transfer paper (P) is sent out of the apparatus main body by a discharge roller (not shown). Stacked face up on a copy tray (not shown). Note that the fixing device (270) may be configured to include a belt component if necessary.

  On the other hand, the surface of the photosensitive drum (200) after the belt transfer is cleaned by the photosensitive member cleaning device (201) and is uniformly discharged by the discharging lamp (202). The residual toner remaining on the outer peripheral surface of the intermediate transfer belt (501) after the toner image is secondarily transferred to the transfer paper (P) is cleaned by the belt cleaning blade (504). The belt cleaning blade (504) is configured to contact and separate at a predetermined timing with respect to the belt outer peripheral surface of the intermediate transfer belt (501) by a cleaning member separating and contacting mechanism (not shown).

  On the upstream side of the belt cleaning blade (504) in the moving direction of the intermediate transfer belt (501), a toner seal member (502) contacting and separating from the belt outer peripheral surface of the intermediate transfer belt (501) is provided. Yes. The toner seal member (502) receives the falling toner that has dropped from the belt cleaning blade (504) during cleaning of the residual toner, and prevents the falling toner from scattering on the transfer path of the transfer paper (P). It is preventing. The toner seal member (502) is brought into contact with and separated from the belt outer peripheral surface of the intermediate transfer belt (501) together with the belt cleaning blade (504) by the cleaning member separating and contacting mechanism.

  The lubricant (506) scraped by the lubricant application brush (505) is applied to the belt outer peripheral surface of the intermediate transfer belt (501) from which the residual toner has been removed in this way. The lubricant (506) is made of, for example, a solid body such as zinc stearate, and is disposed so as to come into contact with the lubricant application brush (505). Further, residual charges remaining on the outer peripheral surface of the intermediate transfer belt (501) are removed by a neutralizing bias applied by a belt neutralizing brush (not shown) in contact with the outer peripheral surface of the intermediate transfer belt (501). Here, the lubricant application brush (505) and the belt neutralizing brush are brought into and out of contact with the outer peripheral surface of the intermediate transfer belt (501) at a predetermined timing by a contact / separation mechanism (not shown). It has become.

  Here, at the time of repeat copying, the operation of the color scanner and the image formation on the photosensitive drum (200) are performed at a predetermined timing following the first color (Y) image forming process. The process proceeds to the image forming process for the first color (Bk). The intermediate transfer belt (501) has two sheets in the area cleaned by the belt cleaning blade (504) on the outer peripheral surface of the belt following the batch transfer process of the first four-color superimposed toner image to the transfer paper. The Bk toner image of the eye is primarily transferred. After that, the operation is the same as the first sheet. The above is a copy mode for obtaining a four-color full-color copy. In the three-color copy mode and the two-color copy mode, the same operation as described above is performed for the designated color and the number of times. In the case of the single color copy mode, only the developing device of the predetermined color of the revolver developing unit (230) is set in the developing operation state until the predetermined number of sheets is completed, and the belt cleaning blade (504) is moved to the intermediate transfer belt (501). The copy operation is performed with the touch panel kept in contact.

In the above-described embodiment, the copying machine including only one photosensitive drum 1 has been described. However, the present invention includes a plurality of photosensitive drums as shown in an exemplary configuration in a schematic diagram of a main part in FIG. The present invention can also be applied to an image forming apparatus arranged side by side along one intermediate transfer belt made of a seamless belt.
FIG. 3 shows a four-drum type digital color printer having four photosensitive drums (21BK, 21Y, 21M, 21C) for forming toner images of four different colors (black, yellow, magenta, cyan). An example of the configuration is shown.

  In FIG. 3, the printer main body (10) includes an image writing unit (12), an image forming unit (13), and a paper feeding unit (14) for performing color image formation by electrophotography. Based on the image signal, the image processing unit converts the image into black (BK), magenta (M), yellow (Y), and cyan (C) color signals for image formation, and the image writing unit (12). Send to. The image writing unit (12) is a laser scanning optical system including, for example, a laser light source, a deflector such as a rotary polygon mirror, a scanning imaging optical system, and a mirror group, and corresponds to each color signal described above. Image writing corresponding to each color signal is performed on an image carrier (photoreceptor) (21BK, 21M, 21Y, 21C) provided for each color of the image forming unit (13) having four writing optical paths. .

  The image forming unit (13) includes photosensitive members (21BK, 21M, 21Y, and 21C) that are image carriers for black (BK), magenta (M), yellow (Y), and cyan (C). I have. As each photoconductor for each color, an OPC photoconductor is usually used. Around each photosensitive member (21BK, 21M, 21Y, 21C), there are a charging device, a laser beam exposure unit from the writing unit (12), and a developing device (20BK) for each color of black, magenta, yellow, and cyan. , 20M, 20Y, 20C), a primary transfer bias roller (23BK, 23M, 23Y, 23C) as a primary transfer unit, a cleaning device (not shown), a photoconductor neutralizing device (not shown), and the like. . The developing device (20BK, 20M, 20Y, 20C) uses a two-component magnetic brush developing system. The intermediate transfer belt (22), which is a belt component, is interposed between each photoconductor (21BK, 21M, 21Y, 21C) and each primary transfer bias roller (23BK, 23M, 23Y, 23C). The toner images of the respective colors formed on the photoconductor are sequentially superimposed and transferred.

  On the other hand, the transfer paper (P) is fed from the paper feeding section (14) and then carried on the transfer conveyance belt (50), which is a belt constituting section, via the registration rollers (16). When the intermediate transfer belt (22) and the transfer conveying belt (50) come into contact with each other, the toner image transferred onto the intermediate transfer belt (22) is transferred to a secondary transfer bias roller (60) as a secondary transfer unit. ) For secondary transfer (collective transfer). Thereby, a color image is formed on the transfer paper (P). The transfer paper (P) on which the color image is formed is conveyed to the fixing device (15) by the transfer conveying belt (50). After the image transferred by the fixing device (15) is fixed, the transfer paper (P) is removed from the printer main body. To be discharged.

  Residual toner remaining on the intermediate transfer belt (22) without being transferred during the secondary transfer is removed from the intermediate transfer belt (22) by the belt cleaning member (25). A lubricant application device (27) is disposed downstream of the belt cleaning member (25). The lubricant application device (27) includes a solid lubricant and a conductive brush that rubs the intermediate transfer belt (22) to apply the solid lubricant. The conductive brush is always in contact with the intermediate transfer belt (22) and applies a solid lubricant to the intermediate transfer belt (22). The solid lubricant has an effect of improving the cleaning property of the intermediate transfer belt (22), preventing the occurrence of filming and improving the durability.

  EXAMPLES Hereinafter, the present invention will be described more specifically based on examples. However, the present invention is not limited by these examples, and these examples are appropriately modified without departing from the gist of the present invention. Is also within the scope of the present invention.

A coating solution was prepared as follows, and a seamless belt was produced using this coating solution.
<Preparation of coating solution>
First, carbon black (Special Black 4; Evonik Degussa Co., Ltd.) dispersed in N-methyl-2-pyrrolidone with a bead mill in advance in a polyimide varnish (U-varnish A; Ube Industries, Ltd.) mainly composed of a polyimide resin precursor. (Manufactured) was prepared so that the carbon black content was 17% by weight of the polyamic acid solid content, and well stirred and mixed to prepare a coating solution.

[Manufacture of seamless belts]
Next, a metal cylinder having an outer diameter of 100 mm and a length of 300 mm roughened by blasting is used as a mold, and the coating liquid is formed into a cylinder while rotating the cylinder at 50 rpm (times / minute). It apply | coated with the dispenser so that it might cast on an outer surface uniformly. When the predetermined amount was completely poured and the coating film was spread evenly, the number of revolutions was increased to 100 rpm, introduced into a hot air circulating dryer, gradually heated to 110 ° C. and heated for 60 minutes. Further, the temperature is raised and heated at 200 ° C. for 20 minutes, the rotation is stopped, and it is slowly cooled to take out the cylindrical mold on which the formed film is formed, and this is introduced into a heating furnace (firing furnace) capable of high-temperature processing. Thus, the temperature was raised to 320 ° C. and heat treatment (firing) was performed for 60 minutes.
After stopping the heating and gradually cooling to room temperature, the cylindrical mold on which the formed film was formed was placed in the supercritical fluid exposure apparatus (apparatus 300) shown in FIG. Next, carbon dioxide was supplied to the pressure cell by a supply cylinder, adjusted to 30 MPa and 40 ° C. with a pressure pump and temperature adjusting means, and after the temperature and pressure were stabilized, the pressure cell was sealed and allowed to stand for 3 minutes. After standing, the temperature and pressure were gradually lowered to the atmosphere, the mold was taken out, the coating film was removed from the mold, and a seamless belt with a film thickness of 60 μm was obtained. At the time of mold removal, it was possible to easily remove the film without damaging the film (seamless belt) by holding the end of the film and sliding it from the cylindrical mold.
Similarly, 1000 seamless belts of 20 pieces each were produced using 50 pieces of cylindrical molds, but there were no defects.

A coating solution was prepared as follows, and a seamless belt was produced using this coating solution.
<Preparation of coating solution>
First, carbon black (MA77; manufactured by Mitsubishi Chemical Corporation) dispersed in N-methyl-2-pyrrolidone in a bead mill in advance in a polyamideimide varnish (HR16NN; manufactured by Toyobo Co., Ltd.) containing a polyamideimide resin precursor as a main component. ) Was prepared so that the carbon black content was 20% by weight of the polyamic acid solid content, and well stirred and mixed to prepare a coating solution.

[Production of seamless belt]
Next, a metal cylinder having an outer diameter of 100 mm and a length of 300 mm roughened by blasting is used as a mold, and the coating liquid is formed into a cylinder while rotating the cylinder at 50 rpm (times / minute). It apply | coated with the dispenser so that it might cast on an outer surface uniformly. When the predetermined amount was completely poured and the coating film was spread evenly, the number of revolutions was increased to 100 rpm, introduced into a hot air circulating dryer, gradually heated to 110 ° C. and heated for 60 minutes. Further, the temperature is raised and heated at 200 ° C. for 20 minutes, the rotation is stopped, and it is slowly cooled to take out the cylindrical mold on which the formed film is formed, and this is introduced into a heating furnace (firing furnace) capable of high-temperature processing. Specifically, the temperature was raised to 260 ° C. and heat treatment (firing) was performed for 60 minutes.
After stopping the heating and gradually cooling to room temperature, the cylindrical mold on which the formed film was formed was placed in the supercritical fluid exposure apparatus (apparatus 300) shown in FIG. Next, carbon dioxide was supplied to the pressure cell by a supply cylinder, adjusted to 30 MPa and 40 ° C. with a pressure pump and temperature adjusting means, and after the temperature and pressure were stabilized, the pressure cell was sealed and allowed to stand for 3 minutes. After standing, the temperature and pressure were gradually lowered to the atmosphere, the mold was taken out, the coating film was removed from the mold, and a seamless belt with a film thickness of 60 μm was obtained. In the same way as in Example 1, the mold release from the cylindrical mold could be easily removed without damaging the molded film (seamless belt) simply by holding the end of the molded film and sliding it from the cylindrical mold.
Similarly, 1000 seamless belts of 20 pieces each were produced using 50 pieces of cylindrical molds, but there were no defects.

[Comparative Example 1]
In Example 1, a mold (cylindrical type) having a fluorine-based release layer formed on the outer surface was used, and after forming a coating film in the same manner as in Example 1, a molded film was formed by heat treatment. At the time of demolding), the apparatus shown in FIG. 1 was not used, and demolding was performed by the following method.
Cut part of the end of the molded film obtained by the heat treatment, slide it from the mold while holding the end of the molded film while blowing air to the gap with the mold, and remove the molded film from the mold Removed.
Similarly, 1000 seamless belts of 20 each were manufactured using 50 cylindrical molds, but a part of the end of the molded film was damaged by the blown air, or rapidly by air blowing. As a result, the coating film was distorted, and 100 defective products were generated, such as those in which a part of the coating film had streaks.

Exactly the same as in Example 1, using the prepared coating liquid, the production of a molded film (seamless belt), the release (demolding) of the molded film (seamless belt), and the same mold (cylindrical type) And repeated 100 times.
As a result, a good molded film (seamless belt) could be obtained 100 times, and there were no defective products. That is, there was no problem in the durability of the mold (cylindrical type), and it was not necessary to perform regular maintenance.

[Comparative Example 2]
Using the mold from which a good product was obtained in Comparative Example 1, in the same manner as in Comparative Example 1, the production of the molded film (seamless belt) and the release (demolding) of the molded film (seamless belt) were repeated 100 times. Carried out.
As a result, the mold release performance decreased from around the 20th time, and the time required for releasing (demolding) the molded film (seamless belt) increased. In addition, a part of the mold stuck to the mold from the 30th time and could not be released (demolded), resulting in a defect that a hole was generated in the molded film (seamless belt).

  The belt selected from the seamless belts manufactured in Examples 1 to 3 was deployed as an intermediate transfer belt of an electrophotographic apparatus (image forming apparatus) having the configuration shown in FIG. The positional accuracy was also good, and a high-quality image without abnormal images was obtained.

  That is, according to the manufacturing method of the present invention, it is possible to achieve high productivity without causing defects even when maintenance of the mold is unnecessary, and a high-quality seamless belt without defects can be obtained easily and efficiently. In particular, seamless belts made of polyimide resin or polyamide-imide resin have excellent mechanical strength (high elasticity), heat resistance, and flame retardancy, so electrophotographic devices that require high-speed transfer, positional accuracy, and durability It can be suitably used as an intermediate transfer belt in (image forming apparatus).

(Reference in FIG. 1)
1: High-pressure liquid pump
2: Stop valve
3: Filter
4: Pressure vessel
5: Stirrer
6: Filter
7: Pressure reducing valve
8: Flow meter T; Thermometer P; Pressure gauge

(Reference in FIG. 2)
P Transfer paper L Laser light 70 Static elimination roller 80 Ground roller 200 Photosensitive drum 201 Photosensitive drum cleaning device 202 Static elimination lamp 203 Charger charger 204 Surface potential sensor 205 Image density sensor 210 Belt conveying device 230 Revolver development unit 231Y Y developer 231K Bk development Machine 231C C developing machine 231M M developing machine 270 fixing device 271 and 272 fixing roller 500 intermediate transfer unit 501 intermediate transfer belt 502 toner seal member 503 charging charger 504 belt cleaning blade 505 lubricant application brush 506 lubricant 507 primary transfer bias roller 508 Belt drive roller 509 Belt tension roller 510 Secondary transfer counter roller 511 Cleaning counter roller 512 Feed bag Current detection roller 513 Toner image 514 Optical sensor 600 Secondary transfer unit 601 Transfer paper guide plate 605 Secondary transfer bias roller 606 Transfer paper neutralization charger 608 Cleaning blade 610 Registration roller 801 Primary transfer power source 802 Secondary transfer power source

(Reference in FIG. 3)
P Transfer paper 10 Printer body 12 Image writing unit 13 Image forming unit 14 Paper feeding unit 15 Fixing device 16 Registration roller 20BK, 20M, 20Y, 20C Developing device 21BK, 21M, 21Y, 21C Photoconductor 22 Intermediate transfer belt 23BK, 23M , 23Y, 23C Primary transfer bias roller 25 Belt cleaning member 26 Drive roller 27 Lubricant coating device 50 Transfer conveyor belt 60 Secondary transfer bias roller

(Reference in FIG. 4)
41 Pressure vessel 42 Seamless belt mold

Japanese Patent No. 4044417 JP 2006-264187 A JP-A-2005-14443 JP 2009-12307 A JP 2006-301196 A JP 2006-116821 A

Claims (8)

  This is a method for producing a seamless belt for an electrophotographic apparatus in which a coating liquid containing a resin component is applied to the inner surface or outer surface of a cylindrical mold, and the film is formed by drying and / or curing, and then demolding. A method of manufacturing a seamless belt for an electrophotographic apparatus, wherein the film formed is treated with a supercritical fluid or a subcritical fluid together with the cylindrical mold and demolded.   The method for producing a seamless belt for an electrophotographic apparatus according to claim 1, wherein the supercritical fluid or subcritical fluid is supercritical carbon dioxide or subcritical carbon dioxide.   The method for producing a seamless belt for an electrophotographic apparatus according to claim 1, wherein the resin component is a polyimide resin precursor or a polyamide-imide resin precursor, and the molded film contains a polyimide resin or a polyamide-imide resin.   The method for producing a seamless belt for an electrophotographic apparatus according to any one of claims 1 to 3, wherein the coating liquid contains an electric resistance adjusting material.   A coating liquid containing at least a resin component is applied to the inner or outer surface of the cylindrical mold to form a coating film, and the coating film is dried and / or cured to form a seamless belt-shaped molding film for an electrophotographic apparatus. 5. A seamless belt for an electrophotographic apparatus manufactured after the molded film is removed from the cylindrical mold, and manufactured by the method according to claim 1. A seamless belt for electrophotographic devices.   The seamless belt for an electrophotographic apparatus according to claim 5, which is mounted on the electrophotographic apparatus.   The seamless belt for an electrophotographic apparatus according to claim 6, wherein the seamless belt for the electrophotographic apparatus is an intermediate transfer belt.   An electrophotographic apparatus equipped with a seamless belt for an electrophotographic apparatus, wherein the seamless belt for an electrophotographic apparatus is the seamless belt for an electrophotographic apparatus according to any one of claims 5 to 7. .

Images