JP3769135B2 - Manufacturing method of endless belt - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an endless belt in which a belt precursor solution applied to an inner peripheral surface of a cylindrical centrifugal mold is formed into a film by centrifugal force by rotation and then solidified as an endless film. In particular, an intermediate provided in an image forming apparatus such as a full-color copying machine, a printer, or a facsimile machine that forms a color toner image by superimposing and transferring each color toner image and then transferring the toner image again onto a transfer material to obtain a full-color image. The present invention relates to a method for producing an intermediate transfer belt as a transfer member.
[0002]
[Prior art]
For example, in an electrostatic copying process such as a color copying machine or a color printer, in order to obtain a full color image, a toner image of each color is formed on a photoreceptor, and the toner image is sequentially transferred to an intermediate transfer belt. After a multicolor toner image is formed on the transfer belt, it is electrostatically collectively retransferred onto the transfer material to form a multicolor image with no image shift.
[0003]
A polymer used for an intermediate transfer belt of a color copying machine or the like is required to have flame retardancy, strength, and electrical stability. For example, a fluorine resin or a polyimide resin is used. In many cases, a conductive control agent such as carbon is added to these materials in order to obtain a desired electric resistance. In particular, polyimide is a material that is expected in relation to strength and triboelectric chargeability. The following centrifugal molding method is mentioned as a method of producing an endless belt using this polyimide.
[0004]
When manufacturing an endless belt by the centrifugal molding method using the polyimide-based material, the outline of the manufacturing method includes the following steps. First, a release layer is formed on the inner peripheral surface of a cylindrical centrifugal mold, and a polyamic acid solution is poured onto the release layer as a polyimide precursor solution to be a belt, and then the centrifugal mold is rotated. Thus, the precursor solution is cast on the inner peripheral surface of the centrifugal mold by centrifugal force. Subsequently, the solvent in the precursor solution is volatilized by a heating means or the like while the centrifugal mold is rotated, and a polyimide precursor belt is formed on the inner peripheral surface of the centrifugal mold. Furthermore, a polyimide resin belt can be obtained by heating the polyimide precursor belt and ring-closing imidization at a high temperature. The ring-closing imidization by heating may be performed while the polyimide precursor belt is attached to the centrifugal mold or may be performed after being removed from the centrifugal mold.
[0005]
[Problems to be solved by the invention]
The endless belt used as the intermediate transfer member or the like is one of the characteristics in which the uniformity of the film thickness is important. However, the conventional manufacturing method has a problem that the film thickness varies due to the runout of the centrifugal mold. When the film thickness varies, the resistance value varies in the film thickness direction, which results in lack of image uniformity and further causes transfer omission. Hereinafter, the relationship between the occurrence of such variation in film thickness and the runout of the centrifugal mold will be described with reference to FIG.
[0006]
FIG. 6 is a cross-sectional view showing a belt formed on the inner peripheral surface of the centrifugal mold. Reference numeral 1a indicates an inner peripheral surface of the centrifugal mold, reference numeral 1b indicates a rotation center, and reference numeral 6 indicates an endless film. Yes. Regarding the relationship between film thickness variation and mold runout, the following has been found by the applicant's experiment. As shown in FIG. 6, in the centrifugal molding of the endless belt described above, the film surface 6a formed on the inner peripheral surface 1a of the mold by high-speed centrifugation is formed in a perfect circle shape around the rotation axis of the mold. On the other hand, since the inner peripheral surface 1a of the centrifugal mold has a shake, the inner peripheral surface 1a does not coincide with the perfect circular virtual surface 1c centering on the rotation shaft 1b, and is not a perfect perfect circle. As a result, the film thickness varies. That is, the inner peripheral surface 1a at the time of the centrifugal mold is formed on the inner peripheral surface 1a located on the inner side of the ideal virtual surface 1c, and is positioned on the outer side of the virtual surface 1c. A thick film is formed on the inner peripheral surface 1a.
[0007]
In order to eliminate such a variation in film thickness, it is necessary to suppress the deflection of the inner peripheral surface 1a as much as possible when the centrifugal mold is rotated. However, in order to suppress the vibration almost completely, not only high accuracy is required for the centrifugal mold itself, but also high accuracy is required for equipment for attaching the centrifugal mold to the apparatus. Establishing such high-precision equipment requires advanced technology and at the same time costs high.
[0008]
Accordingly, in view of the above problems, the present invention provides an endless belt manufacturing method capable of obtaining a belt with very little variation in film thickness regardless of the vibration even when the inner peripheral surface of the centrifugal mold has vibration. The purpose is to propose.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the invention described in claim 1 is provided with a release layer composed of polyimide on the inner peripheral surface of a cylindrical centrifugal mold, and then a polyamic acid on the release layer. In the method for producing a polyimide endless belt, the polyamic acid endless membrane is subjected to centrifugal molding using a solution , and the polyamic acid endless membrane is subjected to high-temperature heat treatment to imide ring closure of the polyamic acid . A polyamic acid solution is formed on the inner surface by centrifugal molding to form a polyamic acid film, and then the polyamic acid film is subjected to high-temperature heat treatment to imide ring closure to provide a release film composed of polyimide . It is a manufacturing method of an endless belt.
[0010]
The invention described in claim 2 is the invention described in claim 1, wherein the inner diameter side surface of the release layer composed of the polyimide is formed in a substantially circular shape with respect to the rotation center of the centrifugal mold, In addition, the inner surface of the polyamic acid endless membrane is centrifugally formed on a concentric circle of a release layer made of the polyimide .
[0011]
The invention described in claim 3 is the invention described in claim 1 or 2, wherein the centrifugal mold is detachably set by positioning the rotation direction on the support portion of the centrifuge body, and the centrifugal mold The polyamic acid solution is applied onto the inner peripheral surface of the substrate and centrifuged and solidified by heating and solidified, and then the centrifugal mold is unset from the centrifuge body and subjected to high-temperature heat treatment to obtain polyimide. After the mold release layer is formed, the centrifugal mold is again set back to the same positional relationship as that during the centrifugal molding of the polyamic acid solution in the mold release layer with respect to the support portion of the centrifuge body. , as well as centrifugal molding polyamic acid endless film using a polyamic acid solution on the release layer, the polyamic acid by imide ring closure to the polyimide by subjecting the high-temperature heat treatment in the polyamic acid endless film It is characterized in.
[0012]
[Action]
The polyamic acid film, which is a release layer composed of the polyimide, is smoothed by centrifugal force on the inner peripheral surface of a rotating centrifugal mold, and the surface of the polyamide acid film is a circle having the same distance from the center of the rotating shaft ( It is molded into a nearly perfect circle). In this state, the resin is dried and cured to ring-close the polyamic acid to form a polyimide . The perfect circle surface of the release layer made of polyimide is used as a molding surface (surface for molding the outer diameter side surface of the belt) for belt molding performed later. And while forming the polyamic acid endless film using a polyamic acid solution on the release layer, the polyamic acid endless film, centrifugal molding as an endless film having a true circle surface of the release layer and concentrically Is done. In this way, the polyamic acid film is centrifugally molded to have a perfect circle surface, dried and cured, and then formed on the perfect circle surface of the release layer composed of polyimide. If the polyamic acid is subjected to centrifugal molding and subjected to high-temperature heat treatment on the polyamic acid endless film to imide ring closure of the polyamic acid to form a polyimide, a uniform film is not affected by the shake of the centrifugal mold or the like. An endless belt made of thick polyimide is obtained.
[0013]
Also, when removing the centrifugal mold from the centrifuge body to perform high-temperature drying and curing of the release layer, etc., it is the same as when forming the release layer with respect to the support portion of the centrifuge body when reattaching. By setting the positional relationship, the surface of the release layer can always maintain the perfect circle position at the time of molding.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As one embodiment, a manufacturing method in which an endless belt as an intermediate transfer member used in a color copying machine is centrifugally molded using a polyimide material will be described.
[0015]
First, polyamic acid is used as a belt precursor for polyimide, which is a basic material of the belt. This polyamic acid is soluble in a specific solvent, and has a property of changing to polyimide by ring closure of imide by heat or a catalyst. A polyamic acid solution obtained by dissolving this polyamic acid in a specific solvent is sprayed with a conductive control agent such as carbon in order to obtain a desired electric resistance value. About this addition amount, it is necessary to determine by preliminary experiment so that desired resistance may be obtained.
[0016]
The carbon to be dispersed is classified into acetylene black, oil furnace black, thermal black, channel black and the like, but the carbon usable in the production method according to the present invention is not limited to a specific type.
[0017]
The carbon spraying method can be carried out using means such as ultrasonic dispersion, ball mill, sand mill, etc. Generally, instead of spraying carbon directly into the polyamic acid solution, polyamic acid is used. Carbon is sprinkled in a solvent that can be dissolved, and the carbon dispersion solution and the polyamic acid solution are mixed. Here, the case of using a sand mill for the dispersion of carbon into the solvent will be described as an example. The particle size of carbon in the obtained solvent depends on the dispersion time, the amount of media, the rotational speed of the disk, the viscosity of the carbon dispersion solution, etc. Will change. Therefore, it is necessary to determine the dispersion conditions for the carbon to be used by preliminary experiments so that a desired particle size can be obtained.
[0018]
As a material for the release layer, a polyimide material is used. Therefore, in this example, since the polyimide material is used for the belt base material, the release layer is made of polyimide which is a material similar to the belt so that it can withstand the ring-closing imidization treatment in a high temperature atmosphere at the time of forming the belt. Use system materials.
[0019]
The process of the manufacturing method of the present embodiment is roughly divided into a release layer forming process and a belt forming process, and each forming process is performed by injecting and applying a liquid material into the mold and centrifugal molding. It consists of a series of steps of smoothing and solidification of the liquid film, high-temperature treatment (imide ring closure) transferred to the furnace, mold release and processing. And the characteristic of the manufacturing method which concerns on this invention exists in using the centrifugal molding method in the formation process of the said mold release layer.
[0020]
First, the outline of the configuration of the centrifugal mold used in this embodiment and the support portion of the centrifugal mold will be described, and then the release layer forming step and the belt forming step will be described in detail in order. FIG. 1 is a cross-sectional view showing a state in which a centrifugal mold is attached to a support portion of a centrifugal main body, and FIG. 2 is a view showing a configuration of the support portion on the centrifuge main body side. The centrifugal mold 1 has an inner diameter of 100 mm and a length of 250 mm. As will be described below, the centrifugal mold 1 is detachable from the centrifuge body by a chuck mechanism for positioning the positional relationship with the support portion 2 of the centrifuge body. In addition, what is necessary is just to determine the magnitude | size of the centrifugal mold 1 from the size of the cylindrical film required as an endless film.
[0021]
As shown in FIG. 2, the support unit 2 on the centrifuge side is provided with three movable claw chucks 3. Here, the rotation shaft portion of the centrifugal mold 1 corresponding to the shape of the chuck 3 is provided. When inserted, the three chucks 3 are engaged so as to expand, and the centrifugal mold 1 is rotatably held by the support portion 2. Further, in this chuck mechanism, a positioning groove 4 is provided in the support portion 2, and a not-shown convex portion corresponding to the groove 4 is provided at an end portion on the centrifugal mold 1 side. When the centrifugal mold 1 is attached or detached, the convex part engages with the groove 4 so that the centrifugal mold 1 can always be returned to the same positional relationship with respect to the support part 2 and set. The support portion 2 is connected to a motor drive mechanism (not shown), and the centrifugal mold 1 is rotated together with the support portion 2 by driving the motor.
[0022]
The centrifugal mold 1 attached in the same state as when the release layer was formed by the chuck mechanism had a deflection of the inner peripheral surface 1a of 150 μm. In the centrifugal mold 1 attached to the support part 2 of the centrifuge, a polyamic acid solution prepared by dissolving polyamic acid as a liquid material as a release material precursor in NMP (N-methylpyrrolidone) to 15 wt% is prepared. It is poured onto the inner peripheral surface 1a and applied.
[0023]
FIG. 3 is a view showing an injection process of a liquid material which is a precursor of the release layer. In injecting the liquid material 5 ′, the material solution 5 is directed from the nozzle 7 moving at a constant speed in the axial direction of the centrifugal mold 1 toward the inner peripheral surface 1 a while slowly rotating the centrifugal mold 1 at 10 rpm. ′ Is discharged by a predetermined amount.
[0024]
After the injection of the liquid material 5 'as the release material is completed, the rotational speed of the centrifugal mold 1 is increased to 400 rpm, and the liquid material 5' made of the polyamic acid solution is cast on the inner peripheral surface 1a. The high speed centrifugation is continued for a predetermined time, and the material solution 5 'is smoothed in a layered manner on the inner peripheral surface 1a by the centrifugal force at this time. Further, while the centrifugal mold 1 is being rotated, the temperature of the centrifugal mold 1 is gradually raised to volatilize the solvent, and the temperature is kept at 100 ° C. to volatilize the solvent content in the liquid material 5 ′. Due to this volatilization, solidification of the liquid material 5 'proceeds and is fixed on the inner peripheral surface 1a. This volatilization is performed more efficiently in a heated atmosphere than at normal temperature. In this example, the temperature of the centrifugal mold 1 was increased by attaching a sheet heater (not shown) outside the centrifugal mold 1. In addition, the heating method of this centrifugal mold 1 is not specifically limited.
[0025]
When the evaporation of the solvent progresses and the liquid material 5 'is fixed on the inner peripheral surface 1a, the centrifugal mold 1 is once removed from the centrifuge body, placed in a furnace maintained at 300 ° C, heated for 20 minutes and fixed. The formed material was ring-closed with the imide to complete the formation of the release layer. FIG. 4 is a cross-sectional view showing the formation state of the release layer thus obtained. The surface 5a on the inner diameter side of the release layer 5 formed by the centrifugal rotation is formed into a substantially perfect circle whose cross-sectional shape is equidistant from the rotation center 1b. The perfect circular surface 5a is a molding surface that defines the outer surface of an endless film as a belt to be formed later.
[0026]
The centrifugal mold 1 once removed from the centrifuge for the imide ring closure is set again in the centrifuge, and a belt is formed on the release layer 5. At this time, the chuck mechanism is set to the same positional relationship as that at the time of forming the release layer 5 with respect to the support portion 2 of the centrifuge, and the perfect circle position of the surface 5a of the release layer 5 is secured. The centrifugal mold 1 set in this state was 30 μm when the runout of the inner peripheral surface 1a was measured.
[0027]
Next, a belt forming process using the centrifugal mold 1 in which the release layer 5 is formed will be described. As the belt base material, a polyamic acid dissolved in NMP (N-methylpyrrolidone) to 20% by weight is used. Specifically, as a liquid material that is a precursor of a belt, carbon black REGAL400 (Cabot Corporation) is dispersed in NMP by a sand mill so that the particle size thereof becomes 0.07 μm, and this solution is polyamic acid. A polyamic acid mixed solution prepared by mixing with the solution was used. As for the composition at this time, REGAL400 was 15 wt% with respect to the solid content of a polyimide.
[0028]
First, the centrifugal mold 1 is rotated while being set in a centrifuge, and the polyamic acid mixed solution is injected into the inner peripheral surface 1a. This injection was performed by feeding the nozzle 7 in the axial direction of the centrifugal mold 1 at a constant speed while slowly rotating the centrifugal mold 1 at 10 rpm as in the case of forming the release layer 5.
[0029]
After the injection of the polyamic acid mixed solution, the rotational speed was increased to 400 rpm, the rotational speed was maintained for a predetermined time, and the polyamic acid mixed solution by centrifugal force was smoothed on the release layer 5. Then, the temperature of the centrifugal mold 1 is gradually raised during the centrifugal molding, the temperature is maintained at 100 ° C., and the solvent in the polyamic acid mixed solution is volatilized. Here, solidification of the polyamic acid proceeds by completely evaporating and removing the remaining solvent, and a cylindrical polyamic acid film as an endless film is fixed on the release layer 5. This volatilization is more efficient in a heating atmosphere in a shorter time than normal temperature, and in this example, a sheet heater was attached and heated in the same manner as in the formation of the release layer 5.
[0030]
FIG. 5 shows the formation state of the polyamic acid film thus obtained. As shown in this figure, the surface 6a on the inner diameter side of the polyamic acid film 6 is formed into a substantially circular shape with respect to the rotation center 1b by the above centrifugal molding. And the surface 6a of this polyamic-acid film 6 was a perfect circle, and was shape | molded as a concentric circle of the surface 5a of the said release layer 5, As a result, the film thickness became uniform.
[0031]
After fixing the polyamic acid film 6, the film 6 is further heated to give various characteristics such as heat resistance, chemical resistance and mechanical properties necessary for the belt, and the polyimide film is closed by imide ring closure in a high temperature atmosphere. Change. This imide ring closure was performed by removing the entire centrifugal mold 1 from the centrifuge body and placing it in a furnace maintained at 300 ° C. and heating for 20 minutes. However, the actual imide ring closure method is not limited to the method of transferring to a high temperature furnace, and after fixing the polyamic acid film 6, the centrifugal mold 1 may be continuously rotated while being heated, The polyamic acid film may be released from the centrifugal mold 1 and the taken out film may be covered with a separately prepared cylindrical cylinder for imidization, and the whole may be heated by means such as hot air.
[0032]
The endless belt made of polyimide resin finally obtained in this manner is processed as it is or as appropriate according to each application and used as one functional member. In order to use an endless belt as an intermediate transfer belt of a color copying machine as in this embodiment, after releasing from the centrifugal mold 1, the polyimide film is cut into necessary dimensions, and both ends are opened as necessary. Attach a stopper member to the.
[0033]
For the belt obtained by the production method according to the present invention and the belt obtained by the production method of the following comparative example, the film thickness and the like are measured, and further used as an intermediate transfer belt in an actual copying machine, The evaluation was performed. The belt of the comparative example was manufactured by the following method.
[0034]
A centrifugal mold 1 having an inner diameter of 100 mm and a length of 250 mm was used. The mold runout with the centrifugal mold 1 attached was 150 μm as in the above example. As the liquid material for the release layer, the polyamic acid is dissolved in NMP (N-methylpyrrolidone) and the polyamic acid solution prepared to 15 wt% is used. This liquid material is applied to the inner peripheral surface 1 a of the centrifugal mold 1. Coated by spray. Thereafter, the centrifugal mold 1 is placed in a furnace maintained at 100 ° C., and after the solvent in the material is sufficiently volatilized and fixed, it is transferred to a furnace maintained at 300 ° C. and heated for 20 minutes to close the imide. Thus, a release layer was formed.
[0035]
As the belt base material, a polyamic acid dissolved in NMP (N-methylpyrrolidone) to 20% by weight was used. Further, REGAL400 (Cabot Corporation), which is carbon black, was dispersed in NMP with a sand mill so that the particle size thereof was 0.07 μm, and this solution was mixed with the polyamic acid solution to prepare a polyamic acid mixed solution. . The composition at this time was 15 wt% of REGAL 400 with respect to the solid content of the polyimide as in the example.
[0036]
When the centrifugal mold 1 was set in a centrifuge and the runout of the surface of the release layer was measured, it was 150 μm. In this state, while the centrifugal mold 1 is rotated at 10 rpm, the above polyamic acid mixed solution is injected into the mold coated with the release layer as a liquid material of the belt, and centrifugal molding is performed under the same conditions as in the above embodiment. The polyamic acid mixed solution was smoothed. Then, the temperature of the centrifugal mold 1 was gradually raised and maintained at 100 ° C., and the solvent was volatilized and fixed as a polyamic acid film. In this comparative example, a sheet-like heater is attached to the outside of the mold for heating.
[0037]
After being fixed in the mold as a polyamic acid film, the centrifugal mold 1 was moved into a furnace maintained at 300 ° C. and heated for 20 minutes to perform imide ring closure. The polyimide film thus obtained was released from the mold, and a stopper was attached to obtain an intermediate transfer belt.
[0038]
The measurement and evaluation of the belt gave the following results. The intermediate transfer belt of the example had a film thickness of 48 to 51 μm and a resistance value in the film thickness direction of 4 × 10 9 to 8 × 10 9 Ω. When this belt was used as an intermediate transfer belt of a full-color copying machine, a full-color image without image omission was obtained.
[0039]
On the other hand, the belt of the comparative example had a film thickness of 29 to 70 μm and a resistance value in the film thickness direction of 6 × 10 8 to 9 × 10 9 Ω. When this belt was used as an intermediate transfer belt for a full-color copying machine, only an image with remarkable white spots and uneven shading was obtained.
[0040]
【The invention's effect】
According to the invention described in claims 1 and 2, after providing the release layer composed of polyimide on the inner peripheral surface of the cylindrical centrifugal mold, the polyamic acid solution is used on the release layer. In a method for producing a polyimide endless belt obtained by centrifugally molding a polyamic acid endless membrane and subjecting the polyamic acid endless membrane to high temperature heat treatment to imide ring closure of the polyamic acid, a polyamide is formed on the inner surface of the centrifugal mold. After forming the polyamic acid film by centrifugal molding of the acid solution, a release film composed of polyimide is provided by subjecting the polyamic acid film to high-temperature heat treatment and ring closure of the imide. even if deflection due to the accuracy is somewhat rough to the inner peripheral surface of the centrifugal mold, no vibration on the inner diameter side surface of the centrifugal molding mold release layer, in order that, the releasing layer Of film thickness It is possible to form one polyimide endless belt, moreover, since the releasing layer can withstand the high temperature atmosphere composed of polyimide is provided on the inner peripheral surface of the cylindrical centrifugal mold, heating the polyamic acid film By closing the polyamic acid in a high temperature atmosphere, a polyimide endless belt made of polyimide can be formed on the inner peripheral surface of the cylindrical centrifugal mold .
[0041]
According to the invention described in claim 3, the centrifugal mold positions the rotational direction to the support portion of the centrifuge body detachably set, the polyamic acid solution on the inner circumferential surface on the centrifugal mold After forming a mold release layer composed of polyimide by applying and high-temperature heat treatment by removing the set from the centrifuge body and fixing by centrifugally forming and solidifying by heating Again, the centrifugal mold is set back with respect to the support portion of the centrifuge body in the same positional relationship as that at the time of centrifugal molding of the polyamic acid solution in the mold release layer, and the polyamic acid solution is placed on the mold release layer. as well as centrifugal molding polyamic acid endless film with, since the polyamic acid was imide ring closure is subjected to high-temperature heat treatment in the polyamic acid endless film to polyimide, the centrifugal mold detachable Ri, Therefore, it is possible to perform a high temperature treatment of the release layer in centrifuge outer, it is possible to reduce the number of introduction equipment in mass production, moreover, in setting again to centrifuge the centrifugal mold, Since the centrifugal mold is positioned so as to return to the same positional relationship as when the mold release layer is formed, the surface of the mold release layer does not shake , and therefore an endless belt with a uniform film thickness is always formed. be able to.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a set state of a centrifugal mold used in the manufacturing method of the present embodiment.
FIG. 2 is a plan view showing a configuration of a support portion in FIG.
FIG. 3 is a view for explaining a step of injecting the liquid material for the release layer in the manufacturing method of the present embodiment.
FIG. 4 is a cross-sectional view showing a state of forming a release layer formed by the manufacturing method of this example.
FIG. 5 is a cross-sectional view showing a state of forming an endless film solidified on the release layer by the manufacturing method of this example.
FIG. 6 is a cross-sectional view for explaining the relationship between the deflection of the centrifugal mold and the variation in the film thickness of the belt in the conventional manufacturing method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Centrifugal mold 1a Inner peripheral surface of centrifugal mold 1b Rotation center of centrifugal mold 2 Support part of centrifuge body 3 Release layer 5 'Liquid material of release layer 5a Inner diameter side surface of release layer 4 Endless film (Polyamic acid film, polyimide film)
6a Inner diameter surface of endless membrane

Claims (3)

After providing a release layer composed of polyimide on the inner peripheral surface of a cylindrical centrifugal mold, the polyamic acid endless film is centrifugally molded on the release layer using a polyamic acid solution , and the polyamic acid In a method for producing a polyimide endless belt obtained by subjecting an endless film to a high temperature heat treatment to imide ring closure of polyamic acid, after forming a polyamic acid film by centrifugally molding a polyamic acid solution on the inner surface of the centrifugal mold A process for producing an endless belt, characterized in that a release film composed of polyimide is provided by subjecting this polyamic acid film to high-temperature heat treatment and ring closure with imide . The inner diameter side surface of the release layer composed of the polyimide is formed in a substantially circular shape with respect to the rotation center of the centrifugal mold, and the inner diameter side surface of the polyamic acid endless film is formed of the polyimide. 2. The method for producing an endless belt according to claim 1, wherein centrifugal molding is performed on concentric circles of the mold layer. The centrifugal mold and detachably set in positions the rotational direction to the support portion of the centrifuge body, and by coating the polyamic acid solution on the inner circumferential surface on the centrifugal mold is heated and solidified while centrifugal molding After fixing, and releasing the set of the centrifugal mold from the centrifuge body and performing a high-temperature heat treatment, a release layer composed of polyimide is formed, and then the centrifugal mold is again connected to the centrifuge body. set back to the same position relationship as when the centrifugal molding of the polyamic acid solution of the release layer to the support portion of the, for centrifugal molding polyamic acid endless film using a polyamic acid solution on the release layer The method for producing an endless belt according to claim 1 , wherein the polyamic acid endless film is subjected to high-temperature heat treatment to imide ring closure of the polyamic acid to form a polyimide .

Images