JP5065577B2 - Seamless belt forming method, seamless belt and electrophotographic apparatus - Google Patents

Description

  The present invention relates to a seamless belt forming method used in an electrophotographic apparatus such as a copying machine or a printer, a seamless belt, and an electrophotographic apparatus using the seamless belt.

  In recent years, seamless belts made of heat-resistant resins have been used as functional members such as fixing belts and transfer belts in electrophotographic apparatuses. As the heat-resistant resin, polyimide is particularly used from the viewpoints of heat resistance, mechanical strength, dimensional stability, flame retardancy, and the like. In recent years, an intermediate transfer belt system has become the mainstream in full-color electrophotographic apparatuses that have become widespread, and a polyimide seamless belt is preferably used as the intermediate transfer belt.

  Such a seamless belt can be manufactured by dipping in which a cylinder or cylinder is dipped in a coating solution and pulled up, and then heated to form a belt, or by spray coating in which the coating solution is sprayed onto the outer surface of the cylinder by spraying or the like. Although there is a method by construction, it is not suitable for the production of a polyimide seamless belt because of the waste of the coating solution, the limitation of the viscosity of the solution, and the difficulty in increasing the film thickness. Therefore, a centrifugal molding method is generally used in which a coating liquid is applied to a cylindrical inner surface, heated and dried while rotating to remove the solvent, and then imidized at a temperature of 250 ° C. or higher.

  As the cylindrical material, metal such as iron, stainless steel, and aluminum is used because heat resistance is required. However, if the metal surface remains as it is, the polyimide will adhere to the inner surface during the heat processing, and the belt will peel off. It becomes impossible. In order to solve this problem, attempts have been made to provide a release layer on the inner surface of the cylindrical shape. For example, it is conceivable to apply silicone or a fluorine-based mold release agent, but it is difficult to form a uniform film because the applicability to the inner surface of the coating liquid is reduced. In addition, there are proposals such as providing a PVA resin film on the inner surface of a cylindrical shape (for example, see Patent Document 1) and providing a ceramic layer (for example, see Patent Document 2). There are problems such as insufficient in terms of sex.

Further, it has been proposed to form a glass layer by coating and heating polysilazane as an inner surface release layer (see, for example, Patent Document 3). However, when the coated surface is flat or the formed film is a thin film of 40 μm or less, the film does not peel off during the formation, but the cylindrical surface with curvature has a release property on the glass surface formed of polysilazane. Since it was too good, there was a problem that the belt was partially peeled off from the inner surface of the cylinder and deformed due to resin shrinkage during the imidization reaction process. Therefore, as a measure for improvement, centrifugal molding is performed until the polyimide precursor is dried, and then once peeled off from the cylindrical shape, imidization is performed by attaching a belt to the outer surface of a cylindrical metal cylinder having an outer diameter smaller than the inner diameter of the cylindrical shape. There is a problem that the resin shrinkage in imidization is not uniform, so that there are problems such as non-uniform mechanical strength as a belt (a weak part occurs) and complicated processes.
JP-A-3-261518 JP-A-7-304049 JP 2000-179511 A

  The present invention solves the above-mentioned problems of the prior art. In the polyimide seamless belt centrifugal molding method, the drying step and the imidization step can be carried out in the same cylindrical shape, and the film thickness uniformity and mechanical strength can be achieved. It is an object of the present invention to provide a method for forming a seamless belt that enables the formation of a seamless belt having uniform uniformity. It is another object of the present invention to provide an electrophotographic apparatus using the obtained seamless belt as a transfer belt or a fixing belt, and particularly to provide an electrophotographic apparatus using an intermediate transfer type intermediate transfer belt.

  In order to achieve the above object, according to the invention described in claim 1, the coating liquid containing the heat resistant resin or the heat resistant resin precursor is applied to the inner surface of the cylindrical mold, and heated and dried. There is provided a method for forming a seamless belt by reacting to form a seamless belt, wherein a coating layer containing scaly silica is provided on a cylindrical inner surface.

  According to the second aspect of the present invention, the coating layer containing scaly silica is formed by applying a water-like or organic solvent slurry of scaly silica to a cylindrical inner surface and drying it. A method for forming a seamless belt according to Item 1 is provided.

  According to the invention described in claim 3, the seamless belt forming method according to claim 1 or 2, wherein the scaly silica is composed of secondary particles of leaf-like silica.

  According to the invention described in claim 4, the heat resistant resin or the heat resistant resin precursor is a polyimide precursor or a polyamideimide precursor, according to any one of claims 1 to 3. A method of forming a seamless belt is provided.

  According to the invention described in claim 5, the coating liquid containing the heat resistant resin or the heat resistant resin precursor is obtained by dispersing the inorganic filler in the N-methylpyrrolidone solution of the polyimide precursor or the polyamideimide precursor. The method for forming a seamless belt according to any one of claims 1 to 3, wherein:

  According to the sixth aspect of the present invention, there is provided a seamless belt formed by the seamless belt forming method according to any one of the first to fifth aspects.

  According to the seventh aspect of the present invention, there is provided an electrophotographic apparatus using the seamless belt according to the sixth aspect as a transfer belt or a fixing belt.

  According to the invention described in claim 8, transfer means for performing primary transfer for sequentially superimposing a plurality of color toner images sequentially formed on at least one image carrier on a single intermediate transfer belt, and transfer 7. An electrophotographic apparatus of an intermediate transfer method for transferring a primary transfer image on an intermediate transfer belt by means to a transfer material and performing secondary transfer, wherein the seamless belt according to claim 6 is used as the intermediate transfer belt. An electrophotographic apparatus is provided.

According to the seamless belt forming method of the present invention, the drying step and the imidization step can be performed in the same cylindrical shape in the centrifugal molding method of polyimide or polyamide-imide, and the high-quality and stability with excellent mechanical strength. High seamless belt can be formed.
Further, according to an electrophotographic apparatus using the obtained seamless belt as a transfer belt or a fixing belt, particularly an electrophotographic apparatus using an intermediate transfer type intermediate transfer belt, an electrophotographic apparatus having a durable intermediate transfer belt Can be obtained.

Hereinafter, embodiments of the present invention will be described in detail.
The layer containing scaly silica provided by coating on the cylindrical inner surface according to the present invention will be described.
The layer containing scaly silica provided by coating on the cylindrical inner surface used in the present invention is a scaly silica water or organic solvent slurry or scaly silica water or organic solvent slurry on the cylindrical inner surface. It is obtained by applying and drying a coating liquid containing a resin or a resin precursor.

As the slurry of water or organic solvent of scaly silica, those commercially available under the name of Sun Lovely manufactured by Asahi Glass Co., Ltd. are available.
The scaly silica contained in the water or organic solvent slurry of the scaly silica is substantially composed of the secondary silica particles formed by laminating the flake primary particles in parallel with each other in parallel between the planes. Scale-like silica having a laminated particle form (hereinafter also referred to as “leafy silica secondary particles of the present invention”).

  The above-mentioned thin primary particles have a thickness of 0.001 to 0.1 μm. Such flake primary particles form leaf-like silica secondary particles in which the planes are oriented in parallel with each other and overlap each other, and the thickness of the secondary particles is 0.001 to 3 μm. The ratio (aspect ratio) of the longest length of the leaf-like secondary particles (plate) to the thickness is preferably at least 10, preferably 30 or more, more preferably 50 or more. The ratio of the minimum length of the leaf-like secondary particles (plate) to the thickness is scaly silica having at least 2, preferably 5 or more, more preferably 10 or more. The secondary particles exist independently of each other without fusing.

When the thickness of the leaf-like secondary particles is less than 0.001 μm, the mechanical strength of the leaf-like secondary particles becomes insufficient, which is not preferable. On the other hand, when the thickness of the leaf-like secondary particles is larger than 3 μm, the characteristics as a cured product cannot be sufficiently exhibited when used for cured product applications.
The upper limit of the ratio of the longest length to the thickness of the leaf-shaped secondary particles and the upper limit of the ratio of the minimum length is not particularly specified, but the former is 300 or less, preferably 200 or less, and the latter is 150 or less, preferably 100 or less is practical.

As described above, the thickness and length of the leaf-like secondary particles referred to in the present invention mean the average value of the secondary particles unless otherwise specified.
Further, in the present invention, the scale-like shape is not particularly limited as long as the particles have a substantially thin plate-like form, which may be bent or twisted partially or entirely.

  When the slurry of water or organic solvent of scaly silica is applied and dried on a substrate (in the present invention, a cylindrical inner surface), it has a unique self-forming property and easily forms a strong silica film even at room temperature. There is a characteristic that can be. The formed film has a structure in which scaly silica is laminated in parallel along the substrate.

  When a seamless belt is produced using a cylindrical shape with such a coating on the inner surface, uneven belt thickness due to repelling of the coating liquid or partial shrinkage due to resin shrinkage in the drying process and imidization reaction process There is no peeling of the belt, and the drying step and the imidization step can be performed in the same cylindrical shape. In addition, there is no non-uniformity of resin shrinkage as in the method of imidizing by peeling off from the cylindrical mold and attaching a belt to the outer surface of a cylindrical metal cylinder having an outer diameter smaller than the cylindrical inner diameter (type 2 system). It is possible to produce a belt having uniform mechanical strength (no weak portion) with fewer steps than the type 2 system. In addition, said 2 type | system | group method was so called from using the separate cylindrical type | mold from which a drying process and an imidation process differed in a diameter.

The reason for these effects is not clear, but the following is presumed.
Since silica has a glass-like structure, it is considered that it has good paintability with respect to the coating liquid and has similar properties in peelability. However, since the scaly silica layer has a structure in which scaly silica overlaps and is laminated in parallel to the substrate as described above, the layer surface is not a perfect mirror surface such as a glass surface, but the layer surface is a scaly overlapping part. It is thought that it has unevenness of about 0.001 to 0.1 μm. For this reason, it is thought that the anchor effect works when the coating liquid partially enters the unevenness and cures the resin, thereby improving the adhesion between the scaly silica layer and the resin film.

Next, formation of the layer containing scaly silica will be described.
The dispersion of scaly silica is applied so as to be uniform over the whole while slowly rotating the cylindrical rotating body. Thereafter, the rotational speed is increased and the motor rotates at a constant speed for a certain time. While rotating, the solvent is evaporated at room temperature or gradually at a temperature of about 70 to 150 ° C. After evaporation, the solution is heated at a temperature of about 80 ° C. to 150 ° C. for about 8 H (hours) to form a flaky silica film. Let
The above is an example, and other methods such as dipping and wiping may be used as long as coating can be applied to the inner surface of the cylindrical mold, and a heat-resistant resin or the like is mixed with the flaky silica dispersion as necessary to form a cylinder. It is also possible to increase the adhesion to the mold and control the surface properties. In addition, it is desirable that the heating conditions be such that when the heat resistant resin is mixed, the resin is formed.

Next, centrifugal molding will be described. However, the following description is an example and is not limited thereto.
The coating solution is uniformly applied to the whole while slowly rotating the cylindrical rotating body. Thereafter, the rotational speed is increased and the motor rotates at a constant speed for a certain time. While rotating, the temperature is gradually raised and the solvent is evaporated at a temperature of about 70 to 150 ° C. In this drying step, it is preferable to circulate and remove atmospheric vapor efficiently. When a self-supporting film is obtained, the temperature is gradually raised and fired at about 300 ° C. to 400 ° C. to sufficiently imidize (imidization step). After slow cooling, peel from the mold and take out as a seamless belt. Of course, after removing the solvent, after cooling to room temperature and removing the belt from the cylindrical shape, the belt may be fitted to the outer surface of the cylindrical shape to perform imidization, but the complexity of the process and the uniformity of the belt can be improved. In view of this, it is preferable to continue the drying and imidization.

  Although the imidization temperature varies slightly depending on the type of polyimide (300 ° C. to 500 ° C.), it is generally considered that the imidization reaction is completed to some extent at about 300 ° C. to 400 ° C.

Next, polyimide will be described.
A polyimide is generally obtained by a condensation reaction between an aromatic polycarboxylic acid anhydride or a derivative thereof and an aromatic diamine. However, because it has insoluble and infusible properties due to its rigid main chain structure, first a polyamic acid (or polyamic acid to polyimide precursor) soluble in an organic solvent is synthesized from an acid anhydride and an aromatic diamine, At this stage, molding is performed by various methods, and then polyimide is obtained by dehydration cyclization (imidization) by heating or a chemical method (see formula (1) showing a synthesis reaction).

  For example, if aromatic polycarboxylic acid anhydride is specifically mentioned, ethylenetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, 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-dicarboxyphenyl) methane dianhydride, 2,2-bis (3,4-dicarboxylphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 2 , 3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,2 , 3,4-benzenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7 , 8-phenanthrenetetracarboxylic dianhydride, and the like. These may be used alone or in combination of two or more.

  Next, examples of the aromatic diamine that can be used as a mixture include m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, and 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) (4-aminophenyl) sulfone, bis (4-amino) Phenyl) sulfone, 3,3′-diamino Nzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, bis [4- (3-amino Phenoxy) phenyl] methane, bis [4- (4-aminophenoxy) phenyl] methane, 1,1-bis [4- (3-aminophenoxy) phenyl] ethane, 1,1-bis [4- (4-amino) Phenoxy) 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] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2, -Bis [4- (3-aminophenoxy) phenyl] butane, 2,2-bis [3- (3-aminophenoxy) 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-amino Nophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) 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-aminopheno B) benzoyl] diphenyl ether, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4-amino-α, α-dimethyl) Benzyl) phenoxy] diphenylsulfone, bis [4- {4- (4-aminophenoxy) phenoxy} phenyl] sulfone, 1,4-bis [4- (4-aminophenoxy) phenoxy] -α, α-dimethylbenzyl] Examples include benzene, 1,3-bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene, and the like. These are used individually or in mixture of 2 or more types.

  A polyimide precursor (polyamic acid) can be obtained by polymerizing the above aromatic polycarboxylic acid anhydride component and diamine component in a substantially equimolar organic polar solvent.

The manufacturing method of a polyamic acid is demonstrated concretely.
Examples of the organic polar solvent used in the polymerization reaction of polyamic acid include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, formamide solvents such as N, N-dimethylformamide and N, N-diethylformamide, and N, N. -Acetamide solvents such as dimethylacetamide, N, N-diethylacetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, phenol, o-, m-, or p-cresol, Phenolic solvents such as xylenol, halogenated phenol and catechol; ether solvents such as tetrahydrofuran, dioxane and dioxolane; alcohol solvents such as methanol, ethanol and butanol; cellosolve such as butyl cellosolve or hexamethyl Phosphoramides, .gamma.-butyrolactone, etc. may be mentioned, it is desirable to use them alone or as a mixed solvent. The solvent is not particularly limited as long as it dissolves polyamic acid, but N, N-dimethylacetamide and N-methyl-2-pyrrolidone are particularly preferable.

  First, 1 type or multiple types of diamine is melt | dissolved in said organic solvent, or is diffused in slurry form in inert gas atmosphere, such as argon and nitrogen. When at least one aromatic polycarboxylic acid anhydride or derivative thereof is added to this solution in a solid state, an organic solvent solution state or a slurry state, a ring-opening polyaddition reaction occurs with heat generation. The viscosity of the polymerization solution is rapidly increased to obtain a high molecular weight polyamic acid solution. The reaction temperature at this time is −20 ° C. to 100 ° C., preferably 60 ° C. or less. The reaction time is 30 minutes to 12 hours.

In this reaction, contrary to the above addition procedure, first, the aromatic polycarboxylic anhydride or derivative thereof is first dissolved or diffused in an organic solvent, and the solution or slurry of the diamine solid or organic solvent in this solution. May be added. Moreover, you may make it react simultaneously, and the mixing order of an acid dianhydride component and a diamine component is not limited.
The aromatic polycarboxylic acid anhydride or derivative thereof and the aromatic diamine component are weighed approximately equimolarly and dissolved in the organic polar solvent. In the present invention, the order of adding the aromatic tetracarboxylic dianhydride and the aromatic diamine is not limited. You may add simultaneously. Moreover, you may mix the organic polar solvent which melt | dissolved each.

  As described above, the polyamic acid composition according to the present invention is obtained by subjecting an aromatic polycarboxylic acid anhydride or a derivative thereof and an aromatic diamine component to an approximately equimolar amount by polymerization reaction in an organic polar solvent. A polyamic acid solution in which the product is uniformly dissolved in the organic polar solvent is obtained.

  Although these polyamic acid compositions can be easily synthesized as described above, it is easy to obtain a commercially available polyimide varnish in which the polyamic acid composition is dissolved in an organic solvent. Is possible. These include, for example, Torenice (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 (manufactured by Sumitomo Bakelite) And the like.

  Various additives can be added to the polyamic acid composition as necessary in order to improve various properties. As the reinforcing agent, for example, one or more glass fibers, carbon fibers, aromatic polyamide fibers, silicon carbide fibers, potassium titanate fibers, and glass beads can be added. Further, for the purpose of improving the slipperiness, one or more solid lubricants such as molybdenum disulfide, graphite, boron nitride, lead monoxide, lead powder and the like can be added. One or more usual additives such as an antioxidant, a heat stabilizer, an ultraviolet absorber, a lubricant, and a colorant can be added as long as the object of the present invention is not impaired. In particular, when it is used as a seamless belt member for an electrophotographic apparatus, it is necessary to contain various additives depending on the application, but an inorganic filler having a reinforcing effect as described above is particularly required from the viewpoint of mechanical strength. It is.

  Further, when used as a fixing belt, it contains an inorganic filler having high thermal conductivity. In addition, when used for a transfer conveyance belt, an intermediate transfer belt, etc., as a resistance control agent, carbon black, graphite, or a metal such as copper, tin, aluminum, indium, tin oxide, zinc oxide, titanium oxide, indium oxide, Examples thereof include metal oxide fine powders such as antimony oxide, bismuth oxide, tin oxide doped with antimony, and indium oxide doped with tin. In addition, as an ion conductive resistance control agent, tetraalkylammonium salt, trialkylbenzyl, ammonium salt, alkylsulfonate, alkylbenzenesulfonate, alkylsulfate, glycerol fatty acid ester, sorbitan fatty acid ester, polyoxyethylene alkylamine Polyoxyethylene fatty alcohol ester, alkyl betaine, lithium perchlorate, and the like may be used in combination. The present invention is not limited to these exemplified compounds.

  Of these resistance control agents, carbon black can be preferably used for the polyimide used in the present invention. However, carbon black has a high cohesion between particles, and its affinity with other resins and solvents is weaker than that, so it is also difficult to uniformly mix or disperse. Therefore, in order to solve this problem, carbon black is uniformly mixed or dispersed by coating the surface of carbon black with various surfactants and resins to enhance the affinity with a solid or liquid base. Many technologies have been studied.

  For example, as a method for improving the dispersibility of carbon black, a method of treating carbon black with a coupling agent (for example, JP-A-63-175869, JP-A-63-158666, British Patent No. 1583564) No. 1583411, etc.) has been studied, but these have the problem that the dispersion of the treated carbon black into the polymerizable monomer is still incomplete and the cost is high. Further, a method using a monomer component in the presence of carbon black (see, for example, JP-A No. 64-6965 and West German Patent No. 3102823) has been proposed. Since it was bad, dispersion | distribution to the polymerizable monomer of carbon black after grafting was inadequate. Further, a method of treating carbon black by reacting with an organic compound by a polymer reaction using the surface functional group of carbon black (see, for example, JP-A-1-284564 and JP-A-5-241378), etc. Has also been considered.

  Examples of organic compounds that can be used in the present invention include vinyl acetate, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, p-methoxystyrene, p-bromostyrene, and p-chlorostyrene. , Styrene compounds such as sodium p-styrenesulfonate, acrylic acid ester compounds such as methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, glycidyl acrylate, methacryl Methacrylic acid ester compounds such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, acrylonitrile, acrylamide, N-isopropylacrylamide, N-piperylacrylamide Of N- substituted acrylamide compounds, divinyl benzene, methylenebisacrylamide, 1,3-butanediol dimethacrylate, but crosslinking monomers and the like in and the like, but is not limited thereto.

  The polyamic acid thus obtained can be imidized by (a) heating method or (b) chemical method, but (a) is converted to polyimide by heating at 200 to 350 ° C. By the conversion method, a polyimide resin can be obtained simply and practically. (B) is a method in which polyamic acid is heated and completely imidized after a treatment reaction with a dehydrating cyclization reagent such as a mixture of carboxylic acid anhydride and tertiary amine, but is more complicated than (a). Since this is a costly method, (a) is often used.

  In order to complete imidization by heating, the intrinsic performance of the polyimide cannot be exhibited unless it is heated above the glass transition temperature of the polyimide used essentially. In order to evaluate the degree of imidization, the imidation rate is usually measured.

  Various methods for measuring the imidization rate are known, and nuclear magnetic resonance spectroscopy is calculated from the integration ratio of 1H attributed to the amide group in the vicinity of 9 to 11 ppm and 1H attributed to the aromatic ring in the vicinity of 6 to 9 ppm. (NMR method), Fourier transform infrared spectroscopy (FT-IR method), a method for quantifying moisture accompanying imide ring closure, and carboxylic acid neutralization titration method, but most commonly, Fourier transform infrared spectroscopy ( FT-IR method) is used.

  In the Fourier transform infrared spectroscopy (FT-IR method), the imidization rate can be defined as the following formula (1).

Imidation ratio = (number of moles of imide groups in the firing stage) / (number of moles of imide groups when theoretically imidized at 100%) × 100 (1)
This can be determined from the absorbance ratio of the characteristic absorption of the imide group of IR. Typical examples are:
(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 benzene ring characteristic absorption of 1,015 cm −1 (2) Characteristic absorption of imide Absorbance ratio between 1,380 cm −1 (inflection vibration band of imide ring C—N group) which is one of the above and 1,500 cm −1 characteristic absorption of benzene ring (3) One of characteristic absorption of imide Absorbance ratio between 1,720 cm <-1> (immobilization vibration band of imide ring C = O group) and 1,500 cm <-1> characteristic absorption of benzene ring (4) 1,720 cm <-1> which is one of characteristic absorptions of imide The imidation ratio can be evaluated using the absorbance ratio of amide group characteristic absorption 1,670 cm −1 (interaction between amide group N—H bending vibration and C—N stretching vibration).
Moreover, if it confirms that the multiple absorption band derived from amide group over 3000-3300cm-1 has lose | disappeared, the reliability of imidation completion will increase further.

Next, polyamideimide will be described.
Polyamideimide is a resin having a rigid imide group and an amide group imparting flexibility in the molecular skeleton, and a general polyamideimide used in the present invention can be used.

  As a method for synthesizing a polyamideimide resin, generally, (i) an isocyanate method to a method of producing a trivalent carboxylic acid derivative having an acid anhydride group and an aromatic isocyanate in a solvent (for example, Japanese Examined Patent Publication 44-44). 19ii), (ii) acid chloride method to a derivative halide of a trivalent carboxylic acid having an acid anhydride group, most typically a method of producing the derivative chloride and diamine in a solvent (for example, Japanese Examined Patent Publication No. 42) -15637).

Each manufacturing method will be described.
(I) Isocyanate method As the derivative of the trivalent carboxylic acid having an acid anhydride group, for example, compounds represented by the general formulas (I) and (II) can be used.

  Any of these can be used, but most typically trimellitic anhydride is used. These trivalent carboxylic acid derivatives having an acid anhydride group may be used alone or in combination depending on the purpose.

  Next, examples of the aromatic polyisocyanate used in the polyamideimide used in the present invention include 4,4′-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,4′-diphenyl ether diisocyanate, and 4,4 ′. -[2,2-bis (4-phenoxyphenyl) propane] diisocyanate, biphenyl-4,4'-diisocyanate, biphenyl-3,3'-diisocyanate, biphenyl-3,4'-diisocyanate, 3,3'-dimethyl Biphenyl-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, etc. are used. be able to. These can be used alone or in combination. Hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, transcyclohexane-1,4-diisocyanate, hydrogenated m-xylylene diene as necessary Aliphatic such as isocyanate and lysine diisocyanate, alicyclic isocyanate and trifunctional or higher polyisocyanate can also be used.

  In the isocyanate method, polyamideimide is produced while generating carbon dioxide gas without passing through a polyamic acid. An example using trimellitic anhydride and aromatic isocyanate is shown in the general formula (I). (In the formula (2), Ar represents an aromatic group.)

(Ii) Acid chloride method As the derivative halide of a trivalent carboxylic acid having an acid anhydride group, for example, compounds represented by the general formulas (III) and (IV) can be used.

  The halogen element is preferably chloride. Specific examples include terephthalic acid, isophthalic acid, 4,4′-biphenyldicarboxylic acid, 4,4′-biphenyletherdicarboxylic acid, 4,4′-biphenylsulfonedicarboxylic acid, 4, 4′-benzophenone dicarboxylic acid, pyromellitic acid, trimellitic acid, 3,3 ′, 4,4′-benzophenone tetracarboxylic acid, 3,3 ′, 4,4′-biphenylsulfone tetracarboxylic acid, 3,3 ′ , 4,4'-biphenyltetracarboxylic acid, adipic acid, sebacic acid, maleic acid, fumaric acid, dimer acid, stilbene dicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, etc. Examples include acid chlorides of carboxylic acids.

The diamine is not particularly limited, and any of an aromatic diamine, an aliphatic diamine, and an alicyclic diamine is used, and an aromatic diamine is preferably used.
Aromatic diamines include m-phenylenediamine, p-phenylenediamine, oxydianiline, methylenediamine, hexafluoroisopropylidenediamine, 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) hexafluoro Propane, 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, iso Propylidenedianiline, 3,3′-diaminobenzophenone, o-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] Xafluoropropane, 4,4′-diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfide, and the like. 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 resin used in the present invention by the acid chloride method, the above-described trivalent carboxylic acid derivative halide having an acid anhydride group and diamine are dissolved in an organic polar solvent, as in the production of the polyimide resin. After that, it is reacted at a low temperature (0 to 30 ° C.) to form a polyamic acid (polyamic acid).

  Examples of the organic polar solvent used include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, formamide solvents such as N, N-dimethylformamide and N, N-diethylformamide, N, N-dimethylacetamide, N, Acetamide solvents such as N-diethylacetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone, phenol, o-, m-, or p-cresol, xylenol, halogenated phenol, Phenol solvents such as catechol, ether solvents such as tetrahydrofuran, dioxane and dioxolane, alcohol solvents such as methanol, ethanol and butanol, cellosolve such as butyl cellosolve or hexamethylphosphoramide, γ-butyl Lactone, and the like can be illustrated, it is desirable to use them alone or as a mixed solvent. The solvent is not particularly limited as long as it dissolves polyamic acid, but N, N-dimethylacetamide and N-methyl-2-pyrrolidone are particularly preferable.

  Thereafter, the polyamic acid is imidized to form polyamideimide. Examples of the imidization method include a method of dehydrating and cyclizing by heating and a method of chemically cyclizing using a dehydrating and ring-closing catalyst. When dehydrating and ring-closing by heating, the reaction temperature is 150 to 400 ° C., preferably 180 to 350 ° C., and the 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.

  Polyamideimide also contains inorganic fillers such as the same reinforcing agent and resistance adjusting agent as necessary, as with the polyimide described above.

An electrophotographic apparatus in which the seamless belt of the present invention is used as an intermediate transfer belt will be described below.
As shown in FIG. 3, the intermediate transfer unit 500 includes an intermediate transfer belt 501 that is an intermediate transfer body stretched around a plurality of rollers. Around the intermediate transfer belt 501, a secondary transfer bias roller 605 that is a secondary transfer charge applying unit of the secondary transfer unit 600, a belt cleaning blade 504 that is an intermediate transfer member cleaning unit, and a lubricant for a lubricant application unit. A lubricant application brush 505 or the like that is an application member is disposed so as to face each other.

A position detection mark is provided on the outer peripheral surface or the 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 provision of position detection marks so as to avoid the passing area of the belt cleaning blade 504, which may be difficult to arrange. A position detection mark is provided on the inner peripheral surface side of the intermediate transfer belt 501. An optical sensor 514 serving as a mark detection sensor is provided at a position between the primary transfer bias roller 507 and the drive roller 508 where the intermediate transfer belt 501 is bridged.
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, a cleaning counter roller 511, and a feedback current detection roller 512, which are primary transfer charge applying units. It is stretched around. Each roller is formed of a conductive material, and each roller other than the primary transfer bias roller 507 is grounded. The primary transfer bias roller 507 is applied with a transfer bias controlled to a predetermined current or voltage according to the number of superimposed toner images by a primary transfer power source 801 controlled by a constant current or a constant voltage. ing.

  The intermediate transfer belt 501 is driven in the arrow direction by a belt driving roller 508 that is driven to rotate in the arrow direction by a drive motor (not shown). The intermediate transfer belt 501 is a semiconductor or an insulator and has a single layer or a multilayer structure. Further, 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 serving as a secondary transfer unit is attached to and separated from a belt outer peripheral surface of the intermediate transfer belt 501 in a portion stretched around the secondary transfer counter roller 510 by a contact / separation mechanism, which will be described later. It is configured to be able to contact and separate. The secondary transfer bias roller 605 is disposed so as to sandwich the recording paper P between the portion of the intermediate transfer belt 501 stretched around the secondary transfer counter roller 510 and is subjected to constant current control. A transfer bias having a predetermined current is applied by the transfer power source 802.

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

  In the color copying machine having such a configuration, when an image forming cycle is started, the photosensitive drum 200 is rotated in a counterclockwise direction indicated by an arrow by a drive motor (not shown), and Bk toner is placed on the photosensitive drum 200. Image formation, C toner image formation, M toner image formation, and Y 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 respective 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. 3, 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 uniformly charged, 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 does not adhere to the remaining portion of the photosensitive drum 200, and the charge is not charged. The toner is attracted to the nonexposed portion, that is, the 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 manner is primarily transferred onto the belt outer peripheral surface of the intermediate transfer belt 501 that is rotating at a constant speed while being in contact with the photosensitive drum 200. 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. On the photosensitive drum 200 side, the process proceeds to the Y image forming process after the Bk image forming process, and reading of the Y image data by the color scanner starts at a predetermined timing, and the photosensitive drum is written by laser beam writing with the Y image data. A Y electrostatic latent image is formed on the surface of 200.

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

  The Bk, Y, C, and M toner images sequentially formed on the photosensitive drum 200 in this way 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.

  When the leading edge of the toner image on the intermediate transfer belt 501 reaches the secondary transfer portion where the nip is formed by the intermediate transfer belt 501 stretched around the secondary transfer counter roller 510 and the secondary transfer bias roller 605. Then, 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 the transfer paper P is conveyed along the transfer paper guide plate 601, and the transfer paper P and the toner image are transferred. Resist alignment is performed.

  In this way, when the transfer paper P passes through the secondary transfer portion, the four-color superimposed toner image on the intermediate transfer belt 501 is transferred by the transfer bias applied by the secondary transfer power source 802 to the secondary transfer bias roller 605. Are collectively transferred (secondary transfer) onto the transfer paper P. After the transfer paper P is conveyed along the transfer paper guide plate 601 and passed through a portion facing the transfer paper neutralization charger 606 composed of a static elimination needle disposed on the downstream side of the secondary transfer portion, the transfer paper P is discharged. Then, it is sent by a belt conveying device 210 toward a fixing device (not shown) (see FIG. 3). Then, after the toner image is melted and fixed at the nip portion of the fixing roller of the fixing device, the transfer paper P is sent out of the apparatus main body by the discharge roller and stacked face up on a copy tray (not shown).

  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. Further, 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 be brought into contact with and separated from the belt outer peripheral surface of the intermediate transfer belt 501 at a predetermined timing by a cleaning member separating and contacting mechanism (not shown). A toner seal member 503 that contacts and separates from the belt outer peripheral surface of the intermediate transfer belt 501 is provided on the upstream side of the belt cleaning blade 504 in the movement direction of the intermediate transfer belt 501. The toner seal member 503 receives the falling toner dropped from the belt cleaning blade 504 when cleaning the residual toner, and prevents the falling toner from scattering on the transfer path of the transfer paper P. The toner seal member 503 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 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 502 that is in contact with the outer peripheral surface of the intermediate transfer belt 501. Here, the lubricant application brush 505 and the belt neutralizing brush 502 are brought into contact with and separated from the outer peripheral surface of the intermediate transfer belt 501 at a predetermined timing by respective contact and separation mechanisms (not shown). Yes.

  Here, at the time of repeat copy, 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 (M) image formation process of the first sheet and the first color of the second sheet. The process proceeds to the image forming process (Bk). Further, the intermediate transfer belt 501 has a second Bk toner 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 image is first 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 predetermined color developing machine 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 kept in contact with the intermediate transfer belt 501. The copy operation is performed in the state.

  The copy mode for obtaining a four-color full-color copy has been described above. 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 number of times. Further, in the single color copy mode, only the predetermined color developer of the revolver developing unit 230 is set in the developing operation state until the predetermined number of copies are completed, and the belt cleaning blade 504 is brought into contact with the intermediate transfer belt 501. The copy operation is performed in the left state.

  In the above embodiment, the copying machine having only one photosensitive drum has been described. However, in the present invention, for example, a plurality of photosensitive drums as shown in FIG. 4 are arranged side by side along one intermediate transfer belt. It can also be applied to an image forming apparatus. FIG. 4 shows a configuration of a four-drum digital color printer including four photosensitive drums 21BK, 21Y, 21M, and 21C for forming toner images of four different colors (black, yellow, magenta, and cyan). An example is shown.

  In FIG. 4, the printer 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 an electrophotographic method. 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. Send. 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. Image writing corresponding to each color signal is performed on image carriers (photoconductors) 21BK, 21M, 21Y, and 21C that have a writing optical path and are provided for each color of the image forming unit 13.

  The image forming unit 13 includes photoreceptors 21BK, 21M, 21Y, and 21C that are image carriers for black (BK), magenta (M), yellow (Y), and cyan (C). . As each photoconductor for each color, an OPC photoconductor is usually used. Around the photoreceptors 21BK, 21M, 21Y, and 21C, there are a charging device, an exposure unit for laser light from the writing unit 12, and developing devices 20BK, 20M, 20Y for black, magenta, yellow, and cyan, respectively. 20C, primary transfer bias rollers 23BK, 23M, 23Y, and 23C as primary transfer units, cleaning devices 30BK, 30M, 30Y, and 30C, and a photosensitive member discharging device (not shown) are disposed. The developing devices 20BK, 20M, 20Y, and 20C use a two-component magnetic brush developing system. The intermediate transfer belt 22 is interposed between the photoconductors 21BK, 21M, 21Y, and 21C and the primary transfer bias rollers 23BK, 23M, 23Y, and 23C, and the toner images of the respective colors formed on the photoconductors. Are sequentially superimposed and transferred.

  On the other hand, the transfer paper P is fed from the paper feed unit 14 and then carried on the transfer conveyance belt 50 via the registration rollers 16. When the intermediate transfer belt 22 and the transfer conveyance belt 50 come into contact, the toner image transferred onto the intermediate transfer belt 22 is subjected to secondary transfer (collective transfer) by a secondary transfer bias roller 60 as a secondary transfer unit. ) As a result, 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, and after the image transferred by the fixing device 15 is fixed, it is discharged out of the printer main body.

  The residual toner that is not transferred during the secondary transfer and remains on the intermediate transfer belt 22 is removed from the intermediate transfer belt 22 by the belt cleaning device 25. A lubricant application device (not shown) is disposed on the downstream side of the belt cleaning device 25. This lubricant application device includes a solid lubricant and a conductive brush that rubs the intermediate transfer belt 22 to apply the solid lubricant. The conductive brush is in constant 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.

  In addition to the intermediate transfer belt type image forming apparatus using the intermediate transfer belt 501 in FIG. 3 or the intermediate transfer belt 22 in FIG. 4 as described above, the present invention is not limited to the intermediate transfer belt 501 or the intermediate transfer belt. The present invention can also be applied to a transfer / conveying belt type image forming apparatus that uses a transfer / conveying belt instead of the belt 22. Also, this transfer / conveyor belt type image forming apparatus can be applied to any of the above-mentioned 1-drum system and 4-drum system.

  Hereinafter, the present invention will be described specifically by way of examples. However, the present invention is not limited to the following examples.

[Example 1]
<Production of scaly silica layer on cylindrical inner surface>
While rotating an SUS cylindrical mold having an inner diameter of 100 mm, a length of 300 mm, and a thickness of 10 mm at 50 rpm, scale-like silica slurry (Asahi Glass Co., Ltd. Sunlably LFS HN-050 leaf-like silica secondary particle average particle size 0.5 μm) 4 g Was applied to the inner surface of the cylindrical mold by uniformly flowing.
When the entire amount had been flowed and the coating film had spread evenly, the number of revolutions was increased to 500 rpm, and the resulting solution was put into a hot air circulating dryer and blown and dried at 80 ° C. for 120 minutes (drying step). Thereafter, the rotation was stopped, and after heating at 150 ° C. for 8H, the mixture was cooled to room temperature to obtain a scaly silica layer.

<Preparation of coating liquid>
A polyamic acid was obtained by polymerizing an equimolar amount of biphenyl-3,4,3 ′, 4′-tetracarboxylic anhydride and 4,4′-diaminodiphenyl ether in N-methylpyrrolidone solvent at room temperature. To this solution, a carbon black (BP-L manufactured by Cabot) dispersion finely pulverized and dispersed in N-methylpyrrolidone with a bead mill was mixed. Further, polydimethylsiloxane (Toray Dow Corning Silicone SH200) having a kinematic viscosity at 25 ° C. of 1 cSt is added to 0.01 wt% of the carbon black-dispersed polyamic acid solution, and well stirred and mixed. Produced.
The obtained carbon black-dispersed polyamic acid solution had a polyamic acid solid content of 13 wt%, carbon black of 3 wt%, and N-methylpyrrolidone of 84 wt%.

<Production of belt>
The coating liquid was uniformly applied to the inner surface of the cylindrical mold while rotating the cylindrical mold on which the scaly silica layer was formed at 50 rpm. When all the flow was completed and the coating film was spread evenly, the number of revolutions was increased to 500 rpm, and it was put into a hot air circulating dryer, gradually heated to 120 ° C. and heated for 120 minutes (drying step). Thereafter, the temperature was gradually raised to 350 ° C. and baked for 30 minutes (imidization step). After stopping the heating, it was slowly cooled to room temperature and then taken out, and the formed coating film was peeled off from the cylindrical inner surface to obtain a seamless belt having a film thickness of 90 μm.

[Example 2]
The same procedure as in Example 1 was conducted except that the flaky silica slurry (Sunlably LFS HN-050) in Example 1 was changed to a flaky silica slurry (Sunlably LFS HN-150 leaf-like silica secondary particles average 1.5 μm).

[Comparative Example 1]
Example 1 was carried out in the same manner as in Example 1 except that no flaky silica layer was provided on a SUS cylindrical mold having an inner diameter of 100 mm, a length of 300 mm, and a thickness of 10 mm. As a result, the belt stuck to the inner surface of the cylindrical mold and could not be peeled off.

[Comparative Example 2]
<Preparation of polysilazane treatment layer on cylindrical inner surface>
A SUS cylindrical shape having an inner diameter of 100 mm, a length of 300 mm, and a thickness of 10 mm was coated with Clariant Japan polysilazane L110 (1% diluted solution) by dipping, sufficiently dried at room temperature, and then 120 ° C for 1 hour at 95 ° C. The treatment was performed in an 80% RH environment for 3 hours to form a polysilazane treatment layer.
Except for the cylindrical shape whose inner surface was treated with polysilazane, the same procedure as in Example 1 was carried out, but a part of the belt was peeled off during the imidization step, and a deformed belt was obtained.

[Comparative Example 3]
While rotating the cylindrical mold of Comparative Example 2 at 50 rpm, the coating liquid used in Example 1 was applied by flowing uniformly over the inner surface of the cylindrical mold. When all the flow was completed and the coating film was spread evenly, the number of revolutions was increased to 500 rpm, and the temperature was gradually increased to 120 ° C. and heated for 120 minutes (drying step). After that, the rotation was stopped, the coating film formed in a belt shape was peeled off from the mold, and a stainless steel cylindrical mold having an outer mirror finish with an outer diameter of 98 mm and a length of 300 mm was inserted inside the belt film, fixed, and then placed in a firing furnace. The temperature was raised to 350 ° C. and the mixture was baked for 30 minutes (imidization step). After stopping the heating, it was slowly cooled to room temperature and then taken out, and the formed coating film was peeled off from the inner surface of the cylinder to obtain a seamless belt having a film thickness of about 90 μm.

After visually observing the cylindrical releasability and the belt shape of the seamless belt obtained in each Example and Comparative Example, the size of FIG. 1 (b) was obtained from the sample collection position shown in FIG. 1 (a). Four samples were cut out and the tear test was performed. Further, a belt from which a sample was not cut out was attached as an intermediate transfer belt of the electrophotographic apparatus of FIG. 4, and the durability of the belt was evaluated by observing the state of the belt when continuous printing of a maximum of 10,000 sheets was performed. The evaluation results are shown in Table 1.
As the mechanical strength of the seamless belt, the tear strength was selected because polyimide and polyamideimide have high elastic modulus and excellent tensile strength, but they are not soft and weak against cracks and cracks. There is a problem that cracks occur during use as a belt. Therefore, tear strength was selected as an index of cracks and cracks.

<Tear test>
Using a strograph (Toyo Seiki), tearing is performed in the direction of the arrow at a distance between chucks of 50 mm and a tearing speed of 100 mm / sec, and the tear strength is measured (see FIG. 2).

  As is apparent from Table 1, the seamless belts of the examples can be peeled off from the cylindrical shape without any problem after imidization, the shape is good without deformation, the mechanical strength is strong, and the intermediate transfer belt type electron As a result of using it as an intermediate transfer belt of a photographic apparatus, it was found that there was no crack / breakage and good durability.

(A) is a perspective view which shows the collection position of the test sample of tear strength of a seamless belt, (b) is a top view which shows the magnitude | size of a test piece. It is a perspective view which shows the distance between chuck | zippers of a test piece, and a tear direction in a tear strength tester. 1 is a schematic cross-sectional view of an intermediate transfer belt type electrophotographic apparatus in which a seamless belt of the present invention is used. FIG. 4 is a schematic cross-sectional view of an intermediate transfer belt type electrophotographic apparatus different from the type in FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Printer main body 12 Image writing part 13 Image forming part 14 Paper feed part 15 Fixing device 16 Registration roller 20BK, 20M, 20Y, 20C Each developing device 21BK, 21M, 21Y, 21C Each photoreceptor 22 Intermediate transfer belt 23BK, 23M, 23Y, 23C Primary transfer bias roller 25 Belt cleaning device 30BK, 30M, 30Y, 30C Cleaning device 50 Transfer conveyance belt 200 Photoconductor 201 Photoconductor cleaning device 202 Static elimination lamp 210 Belt conveyance device 230 Revolver development unit 231K, 231C, 231M , 231Y Each developing device 500 Intermediate transfer unit 501 Intermediate transfer belt 502 Belt neutralizing brush 503 Toner seal member 504 Belt cleaning blade 505 Lubricant application brush 506 Lubricant 507 Primary transfer bias roller 508 Drive roller 509 Belt tension roller 510 Secondary transfer counter roller 511 Cleaning counter roller 512 Feedback current detection roller 514 Optical sensor 600 Secondary transfer unit 601 Transfer paper guide plate 605 Secondary transfer bias roller 606 Transfer paper Charger 608 Cleaning blade 610 Registration roller 801 Primary transfer power supply 802 Secondary transfer power supply P Transfer paper

Claims (8)

A drying step of forming a coating layer containing scaly silica by applying a slurry of water or organic solvent of scaly silica to a cylindrical inner surface and drying;
A chemical reaction step in which a coating liquid containing a heat-resistant resin or a heat-resistant resin precursor is applied onto the coating layer formed on the inner surface of the cylindrical mold, and baked to cause a chemical reaction;
A method for forming a seamless belt, comprising: The method for forming a seamless belt according to claim 1, wherein the same cylindrical shape is used in the drying step and the chemical reaction step, and the chemical reaction step is continuously performed after the drying step.   The method for forming a seamless belt according to claim 1 or 2, wherein the scaly silica is composed of secondary particles of leaf-like silica.   The method for forming a seamless belt according to any one of claims 1 to 3, wherein the heat resistant resin or the heat resistant resin precursor is a polyimide precursor or a polyamideimide precursor.   The coating liquid containing the heat resistant resin or the heat resistant resin precursor has an inorganic filler dispersed in an N-methylpyrrolidone solution of a polyimide precursor or a polyamideimide precursor. 4. The method for forming a seamless belt according to any one of 3 above.   A seamless belt formed by the seamless belt forming method according to claim 1.   An electrophotographic apparatus using the seamless belt according to claim 6 as a transfer belt or a fixing belt. A transfer means for performing primary transfer for sequentially superimposing a plurality of color toner images sequentially formed on at least one image carrier on a single intermediate transfer belt; and primary transfer on the intermediate transfer belt by the transfer means. An intermediate transfer type electrophotographic apparatus for transferring images to a transfer material in a batch and performing secondary transfer,
An electrophotographic apparatus using the seamless belt according to claim 6 as the intermediate transfer belt.

Images