JP2008209658A - Polyimide endless seamless belt, manufacturing method thereof, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyimide endless seamless belt which provides stable traveling performance under different environments, and is free from the occurrence of warpage at its edge part, a manufacturing method thereof, and an image forming device. <P>SOLUTION: The ratio of moisture absorption linear expansion coefficients (S/B) which is the ratio of a moisture absorption linear expansion coefficient (S) from the surface of the belt to the vicinity of the center of the belt, to a moisture absorption linear expansion coefficient (B) from the vicinity of the center of the belt to the backside surface is in the range of 0.9≤the ratio of moisture absorption linear expansion coefficients (S/B) ≤1.1, when the moisture absorption linear expansion coefficients are measured under the high humidity condition of 35°C/85% (relative humidity) and the low humidity condition of 35°C/35% (relative humidity). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polyimide endless seamless belt, a manufacturing method thereof, and an image forming apparatus, which are provided in an image forming apparatus such as a copying machine or a printer.

  Conventionally, seamless belts have been used as members in electrophotographic apparatuses. Particularly in recent full-color electrophotographic apparatuses, an intermediate transfer belt that temporarily superimposes four color developed images of yellow, magenta, cyan, and black on an intermediate transfer belt and then collectively transfers the image onto a transfer medium such as paper. This seamless belt is used.

  An image forming apparatus configured to transfer a toner image formed on an image carrier onto a sheet while conveying a recording sheet by a belt-shaped conveying device (referred to as a transfer conveying belt) is also well known. Yes.

  As a method of such an image forming apparatus, in order to perform high-speed printing, a four-tandem tandem method is used in which a photosensitive member is arranged for four colors and each color is continuously transferred to paper.

  In the intermediate transfer belt method, first, images of four colors are transferred onto the intermediate transfer belt, and then transferred onto a transfer material in a lump. In the transfer conveyance belt system, a transfer material is conveyed by a conveyance belt, and four colors are directly transferred onto the transfer material.

  In such a belt, since the state of the belt varies depending on the environment, it is very difficult to match the position accuracy when the color images are overlapped with each other, and there is a problem in that it causes problems such as color misregistration images.

  As a characteristic required for a belt used in such a system, there is a demand for positional accuracy, and it is required to suppress fluctuations in the environment of the belt because of such demand for positional accuracy. Examples of the environmental fluctuation of the belt include temperature and humidity fluctuations, and it is required to suppress fluctuations in the circumferential length and the axial length of the belt as much as possible.

  Therefore, a material having a low coefficient of thermal expansion and a coefficient of thermal expansion in the circumferential direction and the axial direction is desired.

  Also, if the linear expansion coefficient in the circumferential direction is large, poor running of the belt may occur, or if the linear expansion coefficient in the circumferential direction or the axial direction differs greatly, for example, the flatness of the belt is impaired, particularly at the end portion. This causes a problem that a problem such as warping occurs.

  Polycarbonate, polyvinylidene fluoride, and ETFE (ethylene-tetrafluoroethylene) are used as materials for such an intermediate transfer belt or transfer conveyance belt, but in recent years it has extremely high flame retardancy, high strength, and thermal characteristics. Many excellent polyimide materials (including polymers having an imide bond such as polyamideimide) have been used.

  For example, as a belt using such a polyimide material or the like, a polyimide-based intermediate transfer body (refer to Patent Document 1) in which carbon black content and surface resistance are defined, and centrifugal molding that includes conductive fine powder and in which volume resistance is defined. Examples include a seamless belt obtained by the method (see Patent Document 2).

  However, although polyimide has excellent heat resistance, it has been pointed out that it is slightly inferior in terms of hygroscopicity, and further improvement of the coefficient of linear expansion of moisture is desired.

  Conventionally, as an example of improving the hygroscopic linear expansion coefficient of an electrophotographic polyimide belt, an example in which the hygroscopic linear expansion coefficient in the belt circumferential direction and the (thermal) linear expansion coefficient are controlled to a predetermined relationship to improve dimensional stability. (Refer to Patent Document 3), an example (refer to Patent Document 4) in which the moisture absorption linear expansion coefficient and the tear strength are simultaneously controlled to improve the dimensional stability and cracking of the belt end.

  Examples of the relationship between the moisture absorption or the thermal linear expansion coefficient in the circumferential direction and the axial direction (the linear expansion coefficient in the circumferential direction is 90% or more in the axial direction) are mentioned (see Patent Document 4). However, the running performance and warpage were not improved sufficiently and simultaneously.

Another reason why polyimide is used is that it has good affinity with the resistance control material. Carbon black, which is the most typical resistance control material, is a so-called medium resistance region (typically a region having a volume resistance of about 10 ⁸ Ω · cm to 10 ¹² Ω · cm) when added to a general resin. It was difficult to obtain uniform resistance and stability, and it involved major technical problems. The resistance uniformity and stability when added to polyimide are excellent, and the importance of endless seamless belts made of polyimide is increasing. In particular, belts with improved moisture absorption coefficient and controlled electrical properties are desired. ing.
Japanese Patent No. 2560727 Japanese Patent No. 3116143 JP 2005-266493 A JP 2005-250139 A JP 2005-014440 A

The present invention has been made in view of the above-described problems of the prior art, and in an image forming apparatus using an intermediate transfer belt or a transfer conveyance belt, stable belt running performance and endlessness even in different environments. It is an object of the present invention to provide a polyimide endless seamless belt, a method for manufacturing the same, and an image forming apparatus in which no warpage occurs.
Furthermore, an object of the present invention is to provide a polyimide endless seamless belt, a method for manufacturing the same, and an image forming apparatus that do not generate belt runnability and warp at the end and have uniform electrical characteristics. .

In order to achieve this object, the invention according to claim 1 is characterized in that, as a condition for measuring the coefficient of linear expansion of moisture absorption, from the belt surface measured in a high humidity condition of 35 ° C./85% and a low humidity condition of 35 ° C./35%. The hygroscopic linear expansion coefficient ratio (S / B), which is the ratio between the hygroscopic linear expansion coefficient (S) up to and the hygroscopic linear expansion coefficient (B) from near the center of the belt to the back surface,
0.9 ≦ Hygroscopic linear expansion coefficient ratio (S / B) ≦ 1.1 (1)
It exists in the range of General formula (1), It is characterized by the above-mentioned.

  The invention according to claim 2 is characterized in that the polyimide endless seamless belt according to claim 1 is manufactured by a roll coat method.

  According to a third aspect of the present invention, there is provided at least a charging device that forms an electrostatic latent image on an image carrier, a developing device that forms a toner image using a developer corresponding to each color on the image carrier, and a toner image. The intermediate transfer device that sequentially superimposes the image on the intermediate transfer member running endlessly, temporarily transfers the temporary transfer image on the intermediate transfer member to the transfer material, and then transfers the toner image on the transfer material. An image forming apparatus having a fixing device for fixing a toner image on a transfer material by heating or pressurizing, wherein the intermediate transfer device is equipped with the polyimide endless seamless belt according to claim 1.

  According to a fourth aspect of the present invention, at least a charging device that forms an electrostatic latent image on an image carrier, a developing device that forms a toner image using a developer corresponding to each color on the image carrier, and a toner image A transfer conveyance device that sequentially superimposes and transfers the image onto a transfer material on a transfer conveyance body that travels endlessly, and a fixing device that fixes the toner image on the transfer material by heating or pressurizing the toner image on the transfer material. An image forming apparatus having the polyimide endless seamless belt according to claim 1 mounted thereon.

  According to the present invention, it is possible to realize a polyimide endless seamless belt, a method for manufacturing the same, and an image forming apparatus that do not generate stable belt runnability and warping at the end even in different environments.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

The seamless belt of the present invention can be preferably applied to a polyimide endless seamless belt for an image forming apparatus such as an electrophotographic apparatus.
Regarding the seamless belt of the present invention, first, the constituent materials of the belt will be described.

<Polyimide>
The polyimide used in the present invention is obtained via a polyamic acid (polyimide precursor) by a reaction between a generally known aromatic polycarboxylic acid anhydride or derivative thereof and an aromatic diamine. That is, polyimide is insoluble in solvents due to its rigid main chain structure, and has infusible properties, so it is first soluble in organic solvents from aromatic polycarboxylic anhydrides and aromatic diamines. New polyimide precursor (polyamic acid or polyamic acid) is synthesized and molded by various methods at this stage, and then polyamic acid is dehydrated by heating or chemical method (imidation) And polyimide. The outline of the reaction is shown below.

In the above chemical 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 aromatic polyvalent carboxylic acid anhydride include, for example, 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.

  Specific examples of the aromatic diamine to be reacted with the aromatic polycarboxylic 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) (4-aminophenyl) sulfone Bis (4-aminophenyl) sulfo 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] propane, 2,2-bis [4- (4-aminophenoxy) phenyl Nyl] propane, 2,2-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-amino) Phenoxy) 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-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-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. These can be used alone or in admixture of two or more.

  A polyimide precursor (polyamic acid) can be obtained by carrying out a polymerization reaction in an organic polar solvent using substantially equimolar amounts of the aromatic polycarboxylic anhydride component and the diamine component. Below, 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, N , N-dimethylacetamide, N, N-diethylacetamide and other acetamide solvents, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone and other pyrrolidone solvents, phenol, o-, m-, or p- Phenol solvents such as 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 hexa Chill phosphoramide, .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.

  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), it generates heat. 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, the aromatic polycarboxylic acid anhydride or derivative thereof is first dissolved or diffused in an organic solvent, and the diamine may be added to this solution. Good. 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 acid dianhydride component and the diamine component is not limited. Further, the aromatic tetracarboxylic dianhydride and the aromatic diamine may be simultaneously added to the organic polar solvent for reaction.

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

  As the polyimide precursor solution (polyamic acid solution) in the present invention, the one synthesized as described above can be used, but the so-called polyamic acid composition is simply dissolved in an organic solvent. What is marketed as a polyimide varnish can also be obtained and used.

  Examples of this include Trenys (manufactured by Toray Industries, Inc.), U-Varnish (manufactured by Ube Industries), Rika Coat (manufactured by Nippon Nippon Chemical Co., Ltd.), Optmer (manufactured by JSR), SE812 (manufactured by Nissan Chemical Industries, Ltd.), CRC8000 ( Sumitomo Bakelite Co., Ltd.) is a typical example.

  A coating solution is prepared by mixing and dispersing a filler in the synthesized or obtained polyamic acid solution. 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 a heating method (1) or a chemical method (2). The heating method (1) is a method of converting polyamic acid to polyimide by heat treatment at, for example, 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 (such as a mixture of a carboxylic acid anhydride and a tertiary amine) and then heat-treated to completely imidize, (1 The method (1) is often used because the method is more complicated and costly than the method of heating. 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, nuclear magnetic resonance spectroscopy calculated from an integration ratio of 1H attributed to an amide group in the vicinity of 9 to 11 ppm and 1H attributed to an aromatic ring in the vicinity of 6 to 9 ppm. Various methods such as a method (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. Conversion infrared spectroscopy (FT-IR method) is the most common method.

In Fourier transform infrared spectroscopy (FT-IR method), the imidization rate is defined as follows, for example. 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), the following formula: It is represented by
Imidation ratio (%) = [(A) / (B)] × 100

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 imidation ratio can be evaluated using the following absorbance ratios.
(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.

  The filler is dispersed in the polyimide precursor solution using a disperser such as a bead mill, a ball mill, a nanomizer, a paint shaker, or a jet mill.

  Next, a method for producing a seamless belt using the coating liquid containing the polyimide precursor will be described.

First, centrifugal molding, which is one of the most representative methods for producing a polyimide belt, will be described. However, the following description is an example, and the conditions are not limited thereto.
When producing a seamless belt, it can be achieved by including the following steps.
That is, an application step (step 1) for applying and casting the coating liquid on a support (molding mold), and a removal step for removing the solvent in the coating film applied and cast on the support by heating (step 1). Step 2), an acceleration step (Step 3) for heating and heating to promote imidation of the precursor contained in the coating film, and a mold release step for releasing the formed thin film from the support to form a seamless belt ( It can be manufactured by step 4).

First, a case where centrifugal molding is used as a support (molding mold) will be described as an example. In addition, the following description is an example and conditions (setting conditions) etc. are not limited to this.
Centrifugal molding is composed of a cylindrical rotating body. While this cylindrical rotating body is slowly rotated, coating and casting (coating film coating) is performed so that the coating liquid is uniform over the entire inner surface of the cylinder. Form. 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 obtained, it is returned to room temperature, transferred to a heating furnace (firing furnace) capable of high-temperature treatment, heated in steps, and finally heated at about 250 ° C. to 450 ° C. ( Calcination) and sufficiently imidization or polyamide-imidization of the polyimide precursor or polyamide-imide precursor.

  After completion of imidization and the like, the thin film is peeled off from the mold by slow cooling. A seamless belt is thus formed. In addition, it is preferable to previously form a mold release agent or a mold release layer on the mold so that the mold can be easily peeled off. By this molding method, it is possible to produce a relatively thin film which is difficult by extrusion molding or the like.

  In the case of centrifugal molding, since the mold rotates at a high speed, the degree of orientation of polyimide increases, and there is a drawback that physical properties in the circumferential direction and the axial direction tend to be different. A roll coat method is mentioned as a manufacturing method of the polyimide seamless endless belt which eliminated this fault.

Next, the roll coat method will be described with reference to FIG.
As shown in FIG. 1, A is a paint pan for storing defoamed polyamic acid, which is a paint, C is a metal roller for continuously pumping paint from the paint pan A, and D is a continuous E is an eccentric roller for adjusting the thickness of the paint drawn up to the metal roller C to a predetermined thickness, and E is a transfer of the paint (coating film) having a predetermined thickness from the metal roller C. It is a work (die) for making it adhere.
In the roll coating method using such a manufacturing apparatus, for example, the manufacturing is performed under the following conditions.

[Production conditions]
Metal roller peripheral speed: 40 mm / s
Work peripheral speed: 55mm / s
Metal roller gap: 0.4mm
Eccentric roller clearance: 0.3 mm
Wet film thickness on workpiece: about 180μm
Under the above-mentioned conditions, a polyamic acid paint that has been sufficiently defoamed is poured into a paint pan. The lower part of the metal roller is immersed in the paint, for example, the paint is attached to the surface of the metal roller at a very slow speed of 40 mm / s and pumped upward. Thereafter, the paint thickness on the metal roller is adjusted by an eccentric roller which is installed on the metal roller and can adjust an arbitrary gap with the metal roller. Next, the gap with the metal roller C is adjusted to, for example, 0.4 mm using the eccentric roller D, and the workpiece from the mold roller C on the work (mold) E rotating in the opposite direction to the metal roller C is removed. The paint is transferred, and a paint with a predetermined film thickness is deposited on the mold E.

  The subsequent steps are the same as the centrifugal molding method described above, and the removal step (step 2) in which the solvent in the coating film coated and cast on the support is removed by heating, heating and heating are included in the coating film. It can be manufactured by an accelerating step (step 3) for promoting imidization of the precursor, and a releasing step (step 4) in which the formed thin film is released from the support to form a seamless belt.

  Moreover, when manufacturing a thick film belt or a multilayer belt, after a removal process (step 2), it returns to a coating apparatus, and also applies a coating material, and manufactures the belt which has arbitrary film thickness and layer structure. I can do it.

  Compared with the centrifugal molding method, the roll coating method has a much slower mold rotation speed during coating, so the orientation of the polyimide is less and the difference in physical properties between the circumferential direction and the axial direction is less likely to occur. The difference in the coefficient of expansion of moisture absorption between the circumferential direction and the axial direction can be eliminated by the construction method.

  By measuring the coefficient of linear hygroscopic expansion of the seamless belt of the present invention, it is possible to evaluate the running performance and edge warpage of the belt.

A method for measuring the coefficient of linear expansion of moisture will be described with reference to FIG.
First, the measuring apparatus shown in FIG. 2 will be described. a and a ′ are upper and lower arms, respectively, and a weight b for applying a predetermined load to the sample is attached to the lower arm a ′, and the lower portion of the weight b is flat (horizontal). For example, the lower part of the weight may be flat such as a mirror finish. For example, a laser micro gauge for measuring the distance to the lower part of the weight is arranged in a substantially vertically downward direction of the weight. With this gauge, for example, the distance of the weight door is optically measured to measure the expansion coefficient and the like. Samples (belts) are mounted on these upper and lower arms, and the linear expansion coefficient is measured, for example, optically.

[Method of measuring linear expansion coefficient]
A sample polyimide sheet cut into a predetermined shape (width 10 mm, length 70 mm) from the circumferential direction and the axial direction of the central portion of the seamless belt is attached to the arms a and a ′ of the measuring apparatus shown in FIG. 2 as described above. The weight of the aluminum weight b is adjusted so that the linear pressure applied to the sample is 150 g / cm. A reflective laser microgauge c is set in the measuring device at the lower part of the weight b, and the distance from the lower part of the weight b is measured.

This elongation measuring device is placed in a constant temperature and humidity chamber, and the amount of elongation (ΔL) in both environments of 35 ° C./35% (RH: relative humidity) and 35 ° C./85% (RH: relative humidity) is measured. The hygroscopic linear expansion coefficient was calculated using the formula.
Moisture absorption linear expansion coefficient (ppm /%) = (ΔL / 50 mm) / 50%

As a result of the examination, the moisture absorption linear expansion coefficient (S) from the belt surface to the vicinity of the center measured under high humidity conditions 35 ° C./85% and low humidity conditions 35 ° C./35% as the measurement conditions of the moisture absorption linear expansion coefficient and the belt The hygroscopic linear expansion coefficient ratio (S / B), which is the ratio with the hygroscopic linear expansion coefficient (B) from the vicinity of the center to the back surface,
0.9 ≦ Hygroscopic linear expansion coefficient ratio (S / B) ≦ 1.1 (1)
It was found that the belt edge warpage can be reduced if the above is satisfied.

  In the present invention, the manufactured seamless belt is prepared by removing the sample A from the front surface (the surface in contact with the toner image) to half the thickness of the seamless belt, for example, by polishing, and the back surface (driving). From the surface contacting the means) to half of the thickness of this seamless belt, the hygroscopic coefficient of linear expansion was measured with the sample B prepared by deleting in the same manner as described above, and these values were designated as S and B, respectively. Ask. Using these values, the hygroscopic linear expansion coefficient ratio (S / B) is determined. The thickness of the belt is an average value, and these averages are measured, for example, at 10 points according to the JIS method.

Next, a method for measuring the belt edge warp will be described.
[Measurement method of edge warp]
As shown in FIG. 3, two 40φ (40 mm diameter) round bars are put in the seamless belt and stretched by applying a load of 3 kg. At the left and right ends of the belt stretched around the round bar, the width of the central portion of the belt was measured with calipers, the difference from 40 mm was calculated, and the sum of the differences between the left and right ends was defined as the edge warp.

  The reason why the coefficient of hygroscopic expansion differs in the film thickness direction is not certain, but for example, in centrifugal molding, the filler is unevenly distributed in the film thickness direction due to the influence of centrifugal force, the surface in contact with the mold and the free surface Therefore, the volatility of the solvent is different in the film thickness direction.

[Measurement method of belt thickness]
The film thickness of the seamless belt of the present invention was measured using the following equipment.
Measuring equipment Anritsu Corporation measuring stand K402B
Detector Electronic Micrometer
Measurement pressure 30g (indenter spherical)
N number of measurements n = 5
The film thickness was determined as an average value of n = 5.

Next, materials other than the polyimide material suitably used for the belt of the present invention will be described below.
In the present invention, carbon black may be used as a resistance control agent.

Carbon black, carbon having at least volatiles from 0.4 to 25 percent, primary particle diameter 10 to 30 nm, specific surface area 30~300m ² / g, an acid group in the oil absorption 30~300cm ³ / 100g, pH4 following surface It is preferable to use black. It has been found that by using such carbon black, a film-forming liquid composition having high resistance uniformity (in other words, less variation in resistance) and good dispersion stability can be produced. It is presumed that the good dispersion stability suppresses the orientation due to centrifugal force during rotational molding and reduces the difference in physical properties between the circumferential direction and the axial direction.

  The term “acidic carbon black” in the present specification means carbon black having an acidic group on its surface. Among them, carbon black having a pH of 4 or less and volatile content of 0.4 to 25% It is preferable to use it.

  The reason why the resistance uniformity (resistance variation) becomes high when the pH of the carbon black is 4 or less is not clear, but it is estimated that such carbon black has many surface acidic groups that influence the pH. For this reason, the affinity of the pigment particles themselves to the film-forming solution solvent is increased, which enables fine dispersion, and as a result, resistance uniformity is increased (resistance variation is reduced).

  In addition, the reason why the uniformity of resistance is high (the resistance variation is reduced) when the volatile content of the carbon black used in the present invention is 0.4% by weight or more is not clear. Since such carbon black has many surface acidic groups, the affinity of the pigment particles per se to the film-forming solution solvent is increased, so that fine dispersion is possible, and as a result, resistance uniformity is expected to increase.

Here, “pH of carbon black” in the present invention means a value obtained by the following measurement method.
That is, 1 to 10 g of carbon black sample is weighed in a beaker, water is added at a rate of 10 ml per 1 g of sample, covered with a watch glass and boiled for 15 minutes (To make the sample easy to wet, a few drops such as ethanol can be added. Good). After boiling, the mixture is cooled to room temperature, and the supernatant is removed by a gradient method or a centrifugal separation method to leave a mud. An electrode of a glass electrode pH meter is put in this mud and the pH is measured by JISZ8802 (pH measurement method). In this case, since the measured value may change depending on the electrode insertion position, the beaker is moved and the position of the electrode is changed so that the muddy surface of the electrode surface is in sufficient contact, and the pH value is constant. Read the value when.

  Further, in the present invention, the film-forming liquid (paint of FIG. 1) used in the present invention using carbon black having a volatile content in the range of 0.4% to 25%, more preferably in the range of 15% to 20%. When an intermediate transfer body is prepared by adjusting the coating liquid used for panning, an intermediate transfer body with high electrical resistance uniformity can be obtained.

  Furthermore, in the method of forming a film forming solution into an intermediate transfer member by centrifugal molding or the like, even if the film forming solution is made of carbon black having a volatile content of more than 25% by weight, the resistance uniformity is more than this. Since it does not increase, it is particularly desirable to use carbon black having a volatile content in the range of 0.4 to 25%. This is presumably because too much volatile component causes an inhibition of the dispersibility of carbon black.

The term “carbon black volatile matter” as used herein means a value obtained by the following measurement method.
A dry sample of carbon black is packed into a platinum crucible or a porcelain crucible of the same shape and capacity with a lid so that it does not exceed 2 mm under the lid, and its mass is measured. Cover this, put it in an electric furnace, and in a deoxygenated stream (in a nitrogen stream), heat it at 950 ± 25 ° C for exactly 7 minutes, remove it, and let it cool to room temperature in a desiccator. Weigh the mass and calculate the volatile content using the following formula.
V = (WD−WR) / WD × 100
In the above formula,
V: Volatile content (%)
WD: mass of dry sample (g)
WR: Mass of the sample after heating (g)
It is.

  Such acidic carbon black is, for example, MA7, MA8, # 2200B (manufactured by Mitsubishi Kasei), RAVEN1255 (Colombia), REGAL400R, MOGUL L (manufactured by Kibot), Color Black FW1, Color Black FW18, Color Black S170, Commercially available products such as Color Black S150, Printex U, Special Black 4 (manufactured by Degussa) can be used, as well as carbon black having the above-mentioned performance, such as those newly produced for this purpose. is there.

  As for the production method of acidic carbon black, carbon black is generally performed using a channel black method, a furnace black method or the like. In the channel black method, natural gas, town gas and hydrocarbons are partially burned as raw materials and collided with cold surfaces. In the furnace black method, natural gas or petroleum fraction is used as a raw material, and the raw material is sprayed into a closed reactor and thermally decomposed. Furthermore, these carbon blacks can be oxidized with nitric acid or the like to obtain a desired acidity.

Since the carbon black used as the raw material of the belt of the present invention is excellent in dispersion stability, the volume resistance is in the range of 10 ⁸ Ω · cm to 10 ¹² Ω · cm, that is, the electric characteristics of the belt are easily in the so-called medium resistance region. It is preferable to use those that can be controlled.
The amount of carbon black used in the belt of the present invention is desirably in the range of 10 to 25% by weight.
If the addition amount is less than 10% by weight, it is difficult to control the resistance uniformly, and if it exceeds 25% by weight, the mechanical properties of the belt may be deteriorated.

Next, an image forming apparatus on which the seamless belt of the present invention is mounted will be described.
The image forming apparatus shown in FIG. 4 shows an example of the configuration of an image forming apparatus that employs an intermediate transfer method.
(Intermediate transfer method)
In FIG. 4, the printer main body 10 includes an image writing unit 17, 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 transmits them to the image writing unit 17. To do. 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 photoconductors 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 each of the photoconductors 21BK, 21M, 21Y, and 21C, there are a charging device, a laser beam exposure unit from the image writing unit 17, and developing devices 20Bk, 20M, and 20Y for black, magenta, yellow, and cyan colors. 20C, primary transfer bias rollers 23Bk, 23M, 23Y, and 23C as primary transfer means, a cleaning device (not shown), and a photosensitive member discharging device not shown. The developing devices 20Bk, 20M, 20Y, and 20C use a two-component magnetic brush developing method.

  The intermediate transfer belt 24, which is a belt component, is interposed between the photosensitive members 21BK, 21M, 21Y, and 21C and the primary transfer bias rollers 23Bk, 23M, 23Y, and 23C, and is formed on the photosensitive members. The toner images of each color are sequentially superimposed and transferred.

  On the other hand, the transfer paper P is fed from the paper feed unit 14 and then carried by the transfer conveyance belt 50, which is a belt component, via the registration roller 16. When the intermediate transfer belt 24 and the transfer conveyance belt 50 come into contact, the toner image transferred onto the intermediate transfer belt 24 is subjected to secondary transfer (collective transfer) by a secondary transfer bias roller 51 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 10.

(Transfer conveyance method)
FIG. 5 shows an image forming apparatus that forms an image using an electrophotographic system, and this image forming apparatus shows an example employing a transfer conveyance system. As shown in FIG. 5, this apparatus includes a photosensitive drum 11Y, which is an image carrier that forms images of four different colors of yellow (Y), magenta (M), cyan (C), and black (K). 11M, 11C, and 11K (hereinafter simply referred to as “photosensitive drum 11 if not specified”) are arranged at intervals along an arrow A direction that is a moving direction of the transfer conveyance belt 60 of the transfer belt device 6. This is a direct transfer type image forming apparatus having a continuous tandem configuration.

  The four photosensitive drums 11 have toner image forming units 1Y, 1M, 1C, and 1K (images for forming colors of yellow (Y), magenta (M), cyan (C), and black (K)). Hereinafter, when not specified, it is simply provided in the toner image forming unit 1).

  The toner image forming units 1Y, 1M, 1C, and 1K are each provided with a developing unit 12 corresponding to each photosensitive drum 11. The positions of the respective toner image forming portions 1 are set such that the rotation axes of the respective photosensitive drums 11 are parallel to each other and have a predetermined equal pitch in the sheet moving direction (arrow and direction A).

  In addition, this color laser printer has the optical writing unit 2, the paper feed cassettes 3 and 4, the registration roller pair 5, and the transfer paper (paper) P in a state where the transfer paper P is carried on each toner image forming unit. And a transfer belt device 6 that sequentially conveys the image to 1 and conveys the image to the fixing unit 7. In this embodiment, the transfer belt device 6 also functions as a transfer unit.

  The color laser printer further includes a paper discharge tray 8, a paper feed unit (manual feed tray) 14, a toner supply container 22, and the like.

  The optical writing unit 2 includes a light source, a polygon mirror, an fθ lens, a reflection mirror, and the like, and irradiates the surface of each photosensitive drum 11 with laser light corresponding to each color image based on the image data. And each latent image is formed there. The fixing unit 7 is a fixing device using a belt fixing method.

  The transfer belt device 6 includes a transfer conveyance belt 60 that is a transfer belt that is stretched around a plurality of support rollers 54, 61, 62, 65, 66 including a driving roller 63 and rotates in the direction of arrow A, and the transfer conveyance belt A belt cleaning device 85 for cleaning 60 belt surfaces (in this example, the belt outer surface) is provided, and the drive roller 63 is rotated in the direction of the arrow by a drive source (not shown).

  The transfer / conveying belt 60 is a direct transfer / conveying belt that adsorbs and conveys a transfer sheet, which is a transfer material onto which an image is transferred, to the belt surface.

  As shown in FIG. 5, the belt cleaning device 85 rotates in contact with the surface (outer surface) opposite to the surface in contact with the drive roller 63 of the belt portion (region L) wound around the drive roller 63 of the transfer conveyance belt 60. A brush (not shown) and a blade (not shown) are provided, and a relative speed difference is provided between the rotational speed of the rotating brush and the moving speed of the transfer conveyance belt 60.

  The transfer conveyance belt 60 adsorbs a sheet on the belt surface and conveys a transfer sheet on which toner images are sequentially transferred in a superimposed state.

  The transfer conveyance belt 60 is stretched between a plurality of support rollers 54, 61, 62, 65, 66. Of the support rollers, the transfer roller 60 has a support roller 61 at the inlet portion upstream of the transfer paper moving direction. A predetermined voltage is applied from a power source (not shown), but is arranged on the outer peripheral surface of the transfer conveyance belt 60 so as to face each other.

  The transfer paper fed between the support roller 61 and the electrostatic attraction roller 80 is electrostatically adsorbed on the transfer transfer belt 60 in a charged state, which is respectively photosensitive drums 11Y, 11M, 11C, 11K. The toner images of the respective colors are sequentially transferred in a superimposed state at the respective transfer positions that are in contact with each other.

  At each transfer position corresponding to each of the photosensitive drums 11Y, 11M, 11C, and 11K, roller-shaped transfer bias applying members 27Y, 27M, 27C, and 27K are respectively provided as transfer electric field forming units that form transfer electric fields. It is provided so as to be in contact with the back surface of the transfer conveyance belt 60.

  The transfer bias applying members 27Y, 27M, 27C, and 27K are bias rollers each provided with a sponge or the like on the outer periphery, and there are roller cores from the transfer bias power supplies 9Y, 9M, 9C, and 9K (not shown). A transfer bias is applied to the gold. The transfer bias is applied to the transfer conveyance belt 60 by the applied transfer bias, and a transfer electric field having a predetermined strength is generated between the transfer conveyance belt 60 and the surface of each photosensitive drum 11 at each of the four transfer positions. Is formed. At each transfer position, a backup roller 68 is provided in the vicinity of each transfer position in order to keep the contact between the transfer paper and each photosensitive drum 11 in an optimal state in order to obtain the best transfer nip.

  The transfer bias applying members 27Y, 27M, and 27C and the three backup rollers 68 corresponding to the transfer bias applying members 27Y, 27M, and 27C are rotatably held by a swing bracket (not shown), and the swing bracket is a rotation shaft (not shown). ) Around the center.

  The swing bracket is rotated by rotation of a cam (not shown) fixed to a cam shaft (not shown).

  Further, both the support roller 61 on the entrance side and the electrostatic attraction roller 80 are rotatably supported by a roller bracket (not shown).

  On the other hand, the transfer bias applying member 27K and the backup roller 68 corresponding to the transfer bias applying member 27K are supported by an outlet bracket (not shown) so as to be rotatable about an axis (not shown).

  The outlet bracket is rotated clockwise by operating a handle (not shown) when the transfer belt device 6 is attached to or detached from the main body, whereby the transfer bias applying member 27K and the corresponding backup roller 68 are Separated from the photosensitive drum 11K for black images.

  A support roller 54 that pushes the outer peripheral surface of the transfer conveyance belt 60 is provided on the downstream side in the movement direction of the transfer conveyance belt 60 with respect to the drive roller 63, and the winding angle of the transfer conveyance belt 60 with respect to the drive roller 63 is an optimum angle. I have to.

  Further downstream of the support roller 54, a tension support roller 65 that is pressed and urged by a spring 59 is provided in contact with the inner surface of the transfer conveyance belt 60, thereby applying a predetermined tension to the transfer conveyance belt 60. I am doing so.

  When the transfer paper P passes through the transfer nips of the toner image forming portions 1Y, 1M, 1C, and 1K, the toner images of the respective colors formed on the photosensitive drums 11Y, 11M, 11C, and 11K are transferred. The images are sequentially transferred to the superimposed state by the action of the electric field and nip pressure. Thereby, a full-color toner image is formed on the transfer paper P.

  After the toner image is transferred to the transfer paper P, the surfaces of the photoconductive drums 11Y, 11M, 11C, and 11K are cleaned and discharged by each cleaning device, and are prepared for the next formation of an electrostatic latent image.

  The transfer paper P on which the full-color toner image is formed is fixed in the first discharge direction indicated by the arrow B or the arrow C according to the switching position of the switching guide 21 after the toner image is fixed by the fixing unit 7. Heading in the second paper discharge direction.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the description of these examples, and is interpreted within the scope disclosed in the specification and drawings.

[Examples 1 to 3 and Comparative Examples 1 and 2]
[Preparation of coating solution]
Biphenyl-3,4,3 ′, 4′-tetracarboxylic acid anhydride and 4,4′-diaminodiphenyl ether were polymerized in equimolar amounts in an N-methylpyrrolidone solvent to obtain a polyamic acid solution. In the obtained polyamic acid solution, carbon black (BP-L manufactured by Cabot) dispersed in N-methyl-2-pyrrolidone with a bead mill in advance was used, so that the carbon content was 17% by weight of the polyamic acid solid content. Then, the mixture was thoroughly mixed with stirring to prepare a coating solution.

[Preparation of seamless belt A]
Next, a metal cylinder having an inner diameter of 100 mm and a length of 300 mm having a mirror-finished inner surface is used as a mold, and the coating liquid is uniformly cast on the inner surface of the cylinder while rotating the cylinder at 50 rpm (times / minute). And then applied as if to flow. When the predetermined amount was completely poured and the coating film was spread evenly, the number of revolutions was increased to 150 rpm, the hot air circulating dryer was introduced, and the temperature was gradually raised to 120 ° C. and heated for 30 minutes. Thereafter, the rotation was stopped, the mixture was put into a heating furnace (baking furnace) capable of high temperature treatment, heated to 350 ° C., and subjected to heat treatment (baking) for 30 minutes.

  After stopping heating by treating for a predetermined time, the mold was taken out after gradually cooling to room temperature, and the formed coating film was peeled from the inner surface of the cylinder to obtain a polyimide seamless belt A having a film thickness of 60 μm.

[Production of seamless belts B to D]
A seamless belt B was obtained in the same manner except that the number of revolutions was 150 rpm was changed to 200 rpm (B), 100 rpm (C), and 90 rpm (D).

[Production of seamless belt E]
The metal cylinder used in the production of the seamless belt A was attached as a work of the roll coat coating apparatus shown in FIG. A similar coating solution was poured into the pan, the paint was drawn up at a rotation speed of the metal roller of 40 mm / sec, and the thickness of the paint on the metal roller was controlled with an eccentric roller gap of 0.3 mm. The mold work is controlled to 35 mm / sec, and the paint is uniformly applied on the mold with a metal roller gap of 0.1 mm, and then charged into a hot-air circulating dryer, and the temperature is gradually raised to 90 ° C. and 30 Heated for minutes. Thereafter, the mold was taken out, cooled to room temperature, and coated again in the same manner as described above, then charged into a hot air circulating dryer, gradually heated to 130 ° C. and heated for 40 minutes. Then, it put into the heating furnace (baking furnace) in which high temperature processing is possible, heated up to 350 degreeC, and heat-processed (baking) for 30 minutes. In the same manner as the seamless belt A, it was peeled from the inner surface of the cylinder to obtain a polyimide seamless belt E having a film thickness of 60 μm. The film thickness was determined as an average value of the number of measurements 5 using a measurement stand K402B (detector Electronic Micrometer) manufactured by Anritsu Corporation at a measurement pressure of 30 g (indentation sphere).

  After measuring the edge warp of the seamless belts A to E, it was mounted on the intermediate transfer belt unit shown in FIG. (100 hr idling test) Then, the polyimide sample cut out from the belt was polished, and the hygroscopic expansion coefficients in the front and back directions were measured using a 30 μm-thick strip (the film thickness measurement method is the same as described above). The allowable width of the edge warp is ± 6 mm. Table 1 below shows the evaluation results of Examples 1 to 3 and Comparative Examples 1 and 2.

[Examples 4 and 5]
The seamless belt F of Examples 1 to 3 was mounted on an image forming apparatus as shown in FIGS. 4 and 5, and a 100,000 sheet passing test was performed as an intermediate transfer belt and a transfer conveyance belt. In both cases, there was no problem in belt running performance and image quality (uniformity).

  From the above results, by adopting the configuration of the present invention, an intermediate transfer belt or a transfer conveyance belt that does not generate belt running and end warp and has uniform electric characteristics, and an image forming apparatus using them are provided. Can be provided.

  Although the present invention has been described above, the present invention is not limited to the above description, and various modifications can be made without departing from the scope of the invention.

It is a figure which shows the apparatus structure used for the manufacturing method of the seamless belt of this invention. It is a figure which shows the structure of the measuring apparatus for measuring the linear expansion coefficient of the seamless belt of this invention. It is explanatory drawing for measuring the curvature of the seamless belt of this invention. 1 is a diagram illustrating a configuration example of an image forming apparatus that employs an intermediate transfer method. 1 is a diagram illustrating a configuration example of an image forming apparatus adopting a transfer conveyance method.

Explanation of symbols

A Paint pan B Paint (Polyamic acid coating solution)
C Metal roller D Eccentric roller E Workpiece (mold)
P paper (transfer paper)
a upper part a 'lower part b weight c measuring means (laser micro gauge)
1C, 1Y, 1M, 1K Toner image forming unit 2 Optical writing unit 3, 4 Paper feed cassette 5 Registration roller pair 6 Transfer belt device 7 Fixing unit 8 Paper discharge tray 10 Image forming apparatus (printer) main body 11C, 11Y, 11M , 11K, 21C, 21Y, 21M, 21BK Photosensitive drum (image carrier)
DESCRIPTION OF SYMBOLS 12 Developing unit 13 Image forming part 14 Paper feeding part 15 Fixing device 16 Registration roller 17 Image writing part 20C, 20Y, 20M, 20Bk Developing device 21 Switching guide 22 Toner supply container 24 Intermediate transfer belt 23C, 23Y, 23M, 23Bk Bias Roller 27C, 27Y, 27M, 27K Transfer bias applying member 50 Transfer conveying belt 51 Secondary transfer bias roller 59 Spring 60 Transfer conveying belt 54, 61, 62, 65, 66 Support roller 63 Driving roller 68 Backup roller 80 Electrostatic adsorption roller 85 Cleaning device

Claims (4)

As the measurement conditions of the moisture absorption linear expansion coefficient, the moisture absorption linear expansion coefficient (S) from the belt surface to the vicinity of the center measured under high humidity conditions of 35 ° C./85% and low humidity conditions of 35 ° C./35% and from the vicinity of the center of the belt. The hygroscopic linear expansion coefficient ratio (S / B), which is a ratio with the hygroscopic linear expansion coefficient (B) up to the back surface,
0.9 ≦ Hygroscopic linear expansion coefficient ratio (S / B) ≦ 1.1 (1)
A polyimide endless seamless belt, which falls within the range of the general formula (1).   A method for producing a polyimide endless seamless belt according to claim 1, wherein the polyimide endless seamless belt is produced by a roll coating method. At least a charging device that forms an electrostatic latent image on the image carrier, a developing device that forms a toner image using a developer corresponding to each color on the image carrier, and an intermediate that travels the toner image endlessly An intermediate transfer device that sequentially superimposes and temporarily transfers the image on the transfer member, and temporarily transfers the temporary transfer image on the intermediate transfer member onto the transfer material, and heats or pressurizes the toner image on the transfer material. An image forming apparatus having a fixing device for fixing a toner image on the transfer material,
An image forming apparatus comprising the polyimide endless seamless belt according to claim 1. At least a charging device that forms an electrostatic latent image on an image carrier, a developing device that forms a toner image using a developer corresponding to each color on the image carrier, and a transfer that travels the toner image endlessly An image forming apparatus having a transfer conveyance device that sequentially superimposes and transfers a transfer material on a transfer material, and a fixing device that fixes the toner image on the transfer material by heating or pressurizing the toner image on the transfer material. There,
An image forming apparatus comprising the polyimide endless seamless belt according to claim 1.

Images