JP2003334830A - Method for manufacturing endless belt made of polyimide resin and endless belt made of polyimide resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an endless belt made of a polyimide resin which can improve the uniformity of a film thickness and which is easy to release a polyimide resin film from a cylindrical core and to provide the method for manufacturing the endless belt made of the polyimide resin which can deal with a wide width request characteristic and a cost and the endless belt made of the polyimide resin manufactured by the method for manufacturing the endless belt made of the polyimide resin. <P>SOLUTION: The method for manufacturing the endless belt made of the polyimide resin comprises: a polyimide precursor coating film forming process of forming a polyimide precursor coating film by coating the surface of the cylindrical core with the polyimide precursor solution; a polyimide resin film forming process of forming the polyimide resin film by heating to react after once lowering a temperature after the polyimide precursor coating film is heated and dried; and a polyimide resin film releasing process of releasing the polyimide resin film from the core. The endless belt made of the polyimide resin is provided. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a copying machine,
A method for manufacturing an endless belt made of a polyimide resin that can be used as a photoreceptor, a charging roller, a transfer roller and a fixing belt in an image forming apparatus using an electrophotographic process such as a printer and a facsimile, and a polyimide preferably manufactured by the manufacturing method. The present invention relates to a resin endless belt.

[0002]

2. Description of the Related Art In an image forming apparatus using an electrophotographic process, a rotating member made of metal, plastic or rubber is used as a photosensitive member, a charging unit, a transfer unit and a fixing unit. In order to reduce the size or increase the performance, it is sometimes preferable that these rotating bodies are deformable, and a belt made of a thin plastic film is used as the rotating body. In this case, if the belt has a seam, a defect due to the seam occurs in the output image, and therefore an endless belt having no seam is preferable. As a material, a polyimide resin is particularly preferable in terms of strength, dimensional stability, heat resistance and the like.

To manufacture an endless belt made of a polyimide resin, for example, a centrifugal molding method is known in which a polyimide precursor solution is applied to the inner surface of a cylindrical body and dried while rotating (see, for example, Patent Document 1). .). In addition to this, an inner surface coating method is known in which a polyimide precursor solution is spread on the inner surface of a cylindrical body (see, for example, Patent Document 2). However, these methods of forming a film on the inner surface have a disadvantage in that it is necessary to remove the film from the cylindrical body and mount it on the outer mold at the time of thermosetting the polyimide precursor, which has the disadvantage of requiring man-hours.

As another method for producing an endless belt made of a polyimide resin, for example, a polyimide precursor solution is applied to the surface of a cylindrical core by a dip coating method, dried, and heated to react, then the polyimide There is also a method of peeling the resin film from the cylindrical core body (for example, refer to Patent Document 3). This method has an advantage that the number of steps for transferring the outer die is unnecessary. However, when the polyimide resin film is formed, it has a property that the shrinkage during the heating reaction is very large, and during the heating reaction, the film shrinks in the thickness direction and the axial direction of the cylindrical core. Since the amount of shrinkage of the coating varies depending on the axial position of the cylindrical core body, there is a problem that the thickness of the coating becomes uneven.

When the polyimide resin film is peeled from the cylindrical core after the reaction by heating as in the manufacturing method, the coefficient of thermal expansion of the polyimide resin and the coefficient of thermal expansion of the cylindrical core are It is preferable that the difference is large. That is, as described above, when the polyimide resin film is formed, it is not easy to extract it from the cylindrical core body due to the contracting force during the heating reaction. Therefore, it is preferable to peel off by utilizing the phenomenon that the cylindrical core shrinks more than the polyimide resin film when cooled after the reaction by heating to form the polyimide resin film. Therefore, the higher the coefficient of thermal expansion of the cylindrical core is, the more preferable, but the coefficient of thermal expansion of the metal material usable as the cylindrical core is 23 × 10 ⁻⁶ / aluminum.
K, 18-8SUS is 18 × 10 ^-6 / K, copper is 17 × 1
0 ^-6 / K, iron 12 x 10 ^-6 / K, brass 18 x 10 ^-6
/ K, nickel is 15 × 10 ^-6 / K (both are room temperature)
And, it is not a very large value.

On the other hand, the smaller the coefficient of thermal expansion of the polyimide resin (film), the more preferable. The coefficient of thermal expansion of various polyimide resins is 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (hereinafter appropriately referred to as BPDA) and p-phenylenediamine (hereinafter appropriately referred to as PDA). 12 x 10 ^-6 / using a polyimide precursor consisting of
21 × 10 ⁻⁶ using a polyimide precursor composed of K, BPDA and 4,4′-diaminodiphenyl ether
/ K, pyromellitic dianhydride (PMDA) and 4,4 '
-Using a polyimide precursor composed of diaminodiphenyl ether, 20 × 10 ⁻⁶ / K, 3,3 ′, 4,
4'-benzophenone tetracarboxylic dianhydride and 4,
One using a polyimide precursor consisting of 4'-diaminodiphenylmethane, 50 x 10 ^-6 / K, 3,3 ', 4,
4'-benzophenone tetracarboxylic dianhydride and 4,
A polyimide precursor composed of 4'-diaminobenzophenone is used, which has a density of 24 × 10 ^-6 / K, etc., and in view of the coefficient of thermal expansion of the cylindrical core material, even when compared with the largest aluminum, this BPD that is significantly smaller
There is only one type consisting of A and PDA.

However, in using the endless belt made of polyimide resin, it is preferable that a wide range of candidate materials can be selected so as to meet the required characteristics and the material price. However, BPDA, which is a precursor material that is considered to have a favorable coefficient of thermal expansion, is more expensive than other monomers, and a polyimide resin endless belt using this is expensive.
A polyimide resin that does not use BPDA has an advantage in that the price is low, but has a problem that the coefficient of thermal expansion is not smaller than that of aluminum.

[0008]

[Patent Document 1] JP-A-57-74131

[Patent Document 2] Japanese Patent Laid-Open No. 62-19437

[Patent Document 3] Japanese Patent Laid-Open No. 61-273919

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the various problems in the prior art and achieve the following objects. That is, the present invention is capable of improving the uniformity of the film thickness, and to provide a method for producing a polyimide resin endless belt that is easy to peel from the cylindrical core of the polyimide resin coating. To aim. Another object of the present invention is to provide a method for manufacturing an endless belt made of a polyimide resin, which can meet a wide range of required characteristics and costs. It is an object of the present invention to provide an endless belt made of a polyimide resin manufactured by the method for manufacturing an endless belt made of a polyimide resin.

[0010]

The above object can be achieved by the present invention described below. That is, the present invention is

<1> A polyimide precursor coating film forming step of forming a polyimide precursor coating film by coating the surface of a cylindrical core with a polyimide precursor solution, and heating and drying the polyimide precursor coating film. , Once, after lowering the temperature, heat reaction to form a polyimide resin film forming a polyimide resin film forming step, and a polyimide resin film peeling step of peeling the polyimide resin film from the cylindrical core A method for manufacturing an endless belt made of a polyimide resin, characterized in that

<2> In the step of forming the polyimide resin film, air is introduced into the gap between the cylindrical core body and the polyimide precursor coating film after the temperature is once lowered and before the heating reaction. It is characterized by blowing in <
1> is a method for producing an endless belt made of a polyimide resin.

<3> The polyimide precursor solution contains a fibrous substance <1> or <2>
The method for producing an endless belt made of a polyimide resin according to 1.

<4> The method for producing an endless belt made of a polyimide resin according to <3>, wherein the fibrous substance is made of an inorganic needle-shaped single crystal.

<5> Any one of <1> to <4>, wherein in the polyimide resin film peeling step, the polyimide resin film is hygroscopically expanded to be peeled off.
And a method for producing an endless belt made of a polyimide resin.

<6> A polyimide resin endless belt manufactured by the method for manufacturing a polyimide resin endless belt according to any one of <1> to <5>.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION A method for producing an endless belt made of a polyimide resin according to the present invention comprises a step of forming a polyimide precursor coating film by applying a polyimide precursor solution onto the surface of a cylindrical core body to form a polyimide precursor coating film. And, after heating and drying the polyimide precursor coating film, once lowering the temperature, a polyimide resin film forming step of reacting by heating to form a polyimide resin film; And a polyimide resin film peeling step of peeling from the core. Moreover, you may have another process as needed. Hereinafter, the method for producing the endless belt made of the polyimide resin of the present invention will be described in detail for each step.

-Polyimide precursor coating film forming step-In the polyimide precursor coating film forming step, first, the polyimide precursor is dissolved in an aprotic polar solvent to prepare a polyimide precursor solution. As the polyimide precursor, those composed of various combinations listed above can be used. The polyimide precursor may be used as a mixture of two or more kinds, or may be copolymerized by mixing an acid or amine monomer.

In particular, a polyimide precursor composed of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) and p-phenylenediamine (PDA), and BP
It is preferable to use a polyimide precursor solution prepared by mixing an acid anhydride other than DA and a polyimide precursor containing an arbitrary diamine. By using such a polyimide precursor, the required physical properties can be changed and the material cost can be reduced while keeping the coefficient of thermal expansion of the produced polyimide resin low. This is because the coefficient of thermal expansion of the polyimide resin produced using the polyimide precursor composed of BPDA and PDA is smaller than that of the cylindrical core made of aluminum, and there is a margin in the difference, so the coefficient of thermal expansion is This is because another polyimide precursor may be mixed in a range smaller than that of the cylindrical core made of aluminum.

Other polyimide precursors that can be used in combination with the polyimide precursor composed of BPDA and PDA include BPD.
A consisting of A and 4,4′-diaminodiphenyl ether, a consisting of pyromellitic dianhydride (hereinafter, abbreviated as PMDA as appropriate) and 4,4′-diaminodiphenyl ether, 3,3 ′, 4,4 What consists of'-benzophenone tetracarboxylic acid dianhydride and 4,4'-diaminodiphenylmethane, what consists of 3,3 ', 4,4'-benzophenone tetracarboxylic acid dianhydride and 4,4'-diaminobenzophenone, Although it may be appropriately selected from the above, those composed of PMDA and 4,4′-diaminodiphenyl ether are preferably used in view of suitability for mixing, characteristics, material cost and the like.

The mixing ratio of the polyimide precursor composed of BPDA and PDA and the polyimide precursor composed of other composition is
The more the polyimide precursor having another composition is, the more preferable it is in terms of price. However, if the polyimide precursor is too much, the coefficient of thermal expansion becomes large, and it becomes difficult to peel from the cylindrical core body.
(Polyimide precursor consisting of): (polyimide precursor consisting of other composition) = 5: 5 to 1: 9. The larger the outer diameter of the cylindrical core, the larger the dimensional difference with the polyimide resin film formed on the surface thereof, and the more likely it is that it will come off easily. Therefore, increase the mixing ratio of the polyimide precursor composed of another composition. be able to. When the polyimide resin film is peeled off from the core by hygroscopic expansion, which will be described later, the coefficient of thermal expansion may be large to some extent, so that it is possible to increase the amount of the polyimide precursor having another composition, and in some cases, BPDA and PDA. It does not matter if the polyimide precursor consisting of is not used. On the other hand, a polyimide resin film formed from a polyimide precursor composed of BPDA and PDA is known to have the strongest mechanical strength among polyimide resins, and when used as a fixing belt or a transfer belt, it deforms. There is an advantage that it is difficult to do. On the other hand, in a member such as a transfer belt that directly contacts the surface of the photoconductor, the surface of the photoconductor may be damaged or
In some cases, it is preferable that the mechanical strength is low to some extent because it may be worn out. Even in this case,
It is effective to mix the polyimide precursor composed of BPDA and PDA with the polyimide precursor composed of other composition to adjust the strength, and the polyimide precursor composed of BPDA and PDA may not be used.

The above-mentioned polyimide precursor is dissolved in an aprotic polar solvent such as N-methylpyrrolidone, N, N-dimethylacetamide, acetamide, N, N-dimethylformamide to give a polyimide precursor solution. Is prepared. The mixing ratio, concentration, viscosity, etc. of the polyimide precursor during the preparation are appropriately selected and performed.

In the present invention, the polyimide precursor solution may contain (add) a fibrous substance. In the present invention, the “fibrous substance” refers to a substance having a fine needle-like single crystal. Specific examples thereof include those in which minute needle-shaped single crystals made of zinc oxide, titanium oxide, potassium titanate, aluminum borate, silicon carbide, silicon nitride, graphite and the like are entangled to form a fiber. As described above, since the fibrous substance is a single crystal, it is characterized in that the strength (tensile strength, elastic modulus, etc.) is very strong.

The step of applying the polyimide precursor solution,
Considering the thickness of the coating film, the length of the fibrous substance is 1 to 5
The diameter is preferably 0 μm and the diameter is preferably 0.05 to 5 μm. Further, the addition amount of the fibrous substance is preferably 1 to 40% by mass, and more preferably 5 to 30% by mass based on the total solid content of the polyimide precursor solution. Polyimide resin produced using a polyimide precursor solution containing such a fibrous substance, the fibrous substance is dispersed in the polyimide resin, entangled well with the resin and difficult to deform, the strength of the resin is increased. Not only can the coefficient of thermal expansion be kept small.

Here, the coefficient of thermal expansion of the polyimide resin (coating) produced using the prepared polyimide precursor solution should be smaller than that of the cylindrical core used in the same production method, but specifically, Is preferably 20 × 10 ⁻⁶ / K or less. On the other hand, the coefficient of thermal expansion of the cylindrical core may be larger than the coefficient of thermal expansion of the polyimide resin (coating) produced using the polyimide precursor solution prepared as described above. , 23 × 10 ⁻⁶ / K or more is preferable. Further, the difference between the coefficient of thermal expansion of the produced polyimide resin film and the coefficient of thermal expansion of the cylindrical core is preferably 7 × 10 ⁻⁶ / K or more, and 10 ×
It is more preferably 10 ⁻⁶ / K or more. On the other hand, it is also known that the polyimide resin expands by absorbing water, and when the polyimide resin film formed on the surface of the cylindrical core is difficult to peel off, the film is formed by absorbing water by humidifying. It can be expanded and peeled.
The hygroscopic expansion coefficient (expansion coefficient per 1% of humidity) also differs depending on the type of polyimide resin.
Polyimide consisting of A and PDA is 11ppm, BPDA
And 4,4'-diaminodiphenyl ether are 22 ppm, and those consisting of PMDA and 4,4'-diaminodiphenyl ether are 22 ppm. Therefore,
By utilizing the hygroscopic expansion of the polyimide resin, even if the difference between the coefficient of thermal expansion of the polyimide resin and that of the cylindrical core is small,
The polyimide resin film can be peeled off from the cylindrical core, and in this case, the difference may be less than 7 × 10 ⁻⁶ / K.

In the present invention, a metal such as aluminum, copper or stainless steel can be preferably used as the cylindrical core body of the polyimide resin endless belt. However, as described above, the coefficient of thermal expansion is From the viewpoint of being large, aluminum is more preferable. However, when utilizing the hygroscopic expansion of the polyimide resin, a metal other than aluminum may be used. In addition, when the cylindrical core is made of aluminum, when it is heated to 350 [deg.] C., the strength is lowered and the deformation is likely to occur. Such thermal deformation of aluminum is likely to occur when strain is accumulated during cold working into a cylindrical core shape. In order to remove such distortion, there is a method of annealing aluminum. However, since thermal deformation also occurs due to annealing, it is necessary to perform processing into a predetermined shape after that. Annealing is a method of heating an aluminum material to 350 to 400 ° C. and naturally cooling it in air.

When the coating liquid of the polyimide precursor is directly applied to the surface of the metal cylindrical core body, the formed polyimide resin film is formed on the surface of the cylindrical core body in the polyimide resin film forming step described later. Since the possibility of adhesion is high, it is more preferable that the surface of the cylindrical core is provided with releasability. In order to impart releasability, the surface of the cylindrical core is plated with chromium or nickel, the surface is coated with a fluororesin or a silicone resin, or the surface of the cylindrical core is separated so that the polyimide resin does not adhere to the surface. It is effective to apply a mold agent.

If the residual solvent cannot be completely removed during drying, or if the water generated during heating cannot be completely removed, swelling of the polyimide resin coating may be unavoidable. This is a remarkable problem especially when the thickness of the polyimide resin film exceeds 50 μm. In that case, the surface of the cylindrical core should have a Ra of 0.2 to 2 μm.
It is effective to roughen the surface to about m. Thereby, the residual solvent or water vapor generated from the polyimide resin film,
The bulge can be prevented by passing through a slight gap formed between the cylindrical core body and the polyimide resin film to the outside. For roughening the surface of the cylindrical core, blasting,
There are methods such as cutting and sanding.

In the step of forming the polyimide precursor coating film, the polyimide precursor solution is applied to the surface of the cylindrical core body to form a polyimide precursor coating film. An existing coating method such as a dip coating method of immersing in a precursor solution and pulling it up, a flow coating method of discharging a polyimide precursor solution onto the surface of a cylindrical core while rotating it, and a blade coating method of metalling a coating with a blade at that time, etc. A known method can be adopted. In the above-mentioned flow coating method or blade coating method, the coating portion is horizontally moved and thus the coating film is formed in a spiral shape. However, since the polyimide precursor solution dries slowly, the seam is naturally smoothed. In addition, "coating on the surface of a cylindrical core" means coating on the surface of the side surface of the cylindrical core including a cylinder, and in the case of having a layer, the surface of the layer.

When the polyimide precursor solution is applied by the dip coating method in the step of forming the polyimide precursor coating film, the viscosity of the polyimide precursor solution is so high that the film thickness may become too thicker than the desired value. is there. In that case, for example, the following dip coating method in which the film thickness is controlled by an annular body can be applied.

The dip coating method in which the film thickness is controlled by the annular body will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram showing an example of an apparatus used in the dip coating method in which the film thickness is controlled by a ring. However, the figure shows only the main part of coating, and other devices are omitted. As shown in FIG. 1, in this dip coating method, an annular body 5 having a hole larger than the outer diameter of the cylindrical core 1 is floated on a polyimide precursor solution 2 filled in a coating tank 3 Is a coating method in which the cylindrical core body 1 is immersed in the polyimide precursor solution 2 and then pulled up.

FIG. 2 is an enlarged perspective view of an essential part for explaining the installation state of the annular body 5 shown in FIG. As shown in FIG. 2, an annular body 5 having a hole 6 having a diameter larger than the outer diameter of the cylindrical core body 1 by a constant gap is floated on the liquid surface of the polyimide precursor solution 2.

The ring-shaped body 5 floats on the liquid surface of the polyimide precursor solution 2 and its material is preferably one that is not attacked by the polyimide precursor solution 2, and examples thereof include various metals and various plastics. Further, the structure of the annular body 5 may be, for example, a hollow structure so that the polyimide precursor solution 2 easily floats on the liquid surface.

The annular body 5 can freely move on the liquid surface of the polyimide precursor solution 2. Therefore, in addition to the method of suspending the annular body 5 on the solution so that the annular body 5 can move on the solution 2 with a slight force, the method of supporting the annular body 5 with a roll or a bearing, and the annular body 5 by air There is a method of supporting with pressure, and a method of installing it in a freely movable state. Further, fixing means for temporarily fixing the annular body 5 may be provided so that the annular body 5 is located at the center of the coating tank 3. As such fixing means, there are means for providing legs on the annular body 5, means for fixing the coating tank 3 and the annular body 5, and the like. However,
When these fixing means are used, as will be described later, the fixing means is detachably arranged so that the annular body 5 can freely move when the cylindrical core body 1 is immersed and then pulled up. It

The gap between the outer diameter of the cylindrical core 1 and the diameter of the hole 6 is adjusted in view of the desired coating film thickness. Desired coating thickness,
That is, the dry film thickness is the product of the wet film thickness and the concentration of nonvolatile components in the polyimide precursor solution 2. From this, the desired wet film thickness is determined. The gap between the outer diameter of the cylindrical core 1 and the diameter of the hole 6 is preferably 1 to 2 times the desired wet film thickness. The reason why it is set to 1 to 2 times is that the distance of the gap does not always become the wet film thickness due to the viscosity and / or the surface tension of the polyimide precursor solution 2. Thus, the desired diameter of the hole 6 is obtained from the desired dry film thickness and the desired wet film thickness.

The wall surface of the hole 6 provided in the annular body 5 may be configured to be substantially perpendicular to the liquid surface of the floating polyimide precursor solution 2. For example, it may be a straight line in the cross-sectional view shown in FIG. 1 and the straight line may be perpendicular to the liquid surface of the polyimide precursor solution, or may be configured in another form. For example, as shown in FIG. 3A, the lower part immersed in the polyimide precursor solution 2 is wide and the upper part is narrow,
Examples thereof include an oblique straight line shape 7 or a curved shape 8 in which the lower part immersed in the polyimide precursor solution 2 is wide and the upper part is narrow as shown in FIG. In particular, FIG.
As shown in FIG. 3A or FIG. 3B, it is preferable that the lower part that is dipped in the polyimide precursor solution 2 has a wide bottom. Here, FIG.
Shows the shape of the wall surface of the hole 6 provided in the annular body 5, (a) is a linear wall surface 7, and (b) is a curved wall surface 8.
It is a schematic sectional drawing which shows.

When the dip coating is performed, the cylindrical core 1 is provided with holes 6
And is immersed in the polyimide precursor solution 2. that time,
The cylindrical core body 1 is prevented from coming into contact with the annular body 5. Then, the cylindrical core 1 is pulled up through the hole 6. On this occasion,
The coating film 4 is formed by the gap between the cylindrical core 1 and the hole 6. The pulling rate is 100 to 1500 mm / mi
It is preferably about n. The solid content concentration of the polyimide precursor solution preferable for this coating method is 10 to 40% by mass,
The viscosity is 1 to 100 Pa · s.

When the cylindrical core 1 is pulled up through the hole 6, the annular body 5 is in a freely movable state, and the hole 6 of the annular body is circular, and the outer periphery of the cylindrical core 1 is also circular. Therefore, the annular body 5 can move so that the frictional resistance between the cylindrical core 1 and the annular body 5 becomes constant. That is,
When pulling up the cylindrical core body 1, if the gap between the annular body 5 and the cylindrical core body 1 is attempted to be narrowed at a certain position, the friction resistance is increased in the portion which is attempted to be narrowed. On the other hand, on the opposite side, the frictional resistance becomes small, and the frictional resistance may temporarily become non-uniform. However, since the annular body 5 moves freely, the outer circumference of the cylindrical core body 1 is circular, and the hole 6 of the annular body is circular, such frictional resistance is uniform from a non-uniform state. The annular body 5 moves so as to be in such a state. Therefore, the annular body 5 does not come into contact with the cylindrical core body 1.

Further, the position where the frictional resistance becomes uniform is a position where the circular shape of the outer periphery of the cylindrical core 1 and the circular shape of the hole 6 of the annular body are substantially concentric circles. Therefore, even if the center of the circle of the cross section of the cylindrical core 1 is displaced within the allowable range in the axial direction, the annular body 5 moves to follow it. Therefore, the polyimide precursor coating film 4 having a constant wet film thickness can be provided on the surface of the cylindrical core body 1.

Further, the coating device used in the dip coating method is a cylindrical core body holding means for holding the cylindrical core body, and, if desired, a first moving means and / or a first moving means for vertically moving the holding means. You may have a 2nd moving means which moves the container which accommodates a polyimide precursor solution up and down. The holding means, the first moving means, and / or the second moving means may have a deflection in a plane that intersects the pulling direction during movement. Even in such a case, the annular body 5 can move according to the shake.

By applying such a dip coating method in which the film thickness is controlled by the annular body 5, the sagging at the upper end portion of the cylindrical core body due to the use of the highly viscous polyimide precursor solution is reduced, The film thickness can be easily made uniform.

In the polyimide precursor coating film forming step, in addition to the above dip coating method, an annular coating method as shown in FIG. 4 can also be applied. Here, FIG. 4 is a schematic configuration diagram showing an example of an apparatus used for the annular coating method. In FIG. 4, a difference from FIG. 1 is that an annular sealing material 9 capable of passing the cylindrical core 1 is provided at the bottom of the annular coating tank 3 ′. An annular seal material 9 is attached to the bottom of the annular application tank 3 ', and the annular core 3 is inserted into the center of the annular sealing material 9 to form the annular application tank 3'.
Then, the polyimide precursor solution 2 is stored. This prevents the polyimide precursor solution 2 from leaking. The cylindrical core body 1 is sequentially lifted from the lower part to the upper part of the annular coating tank 3 ′, and the annular seal material 9 is inserted therethrough,
The coating film 4 is applied to the surface. The function of the annular body 5 is the same as that described above. In such an annular coating method, the annular coating tank 3 '
Can be made smaller than the dip coating tank 3, so that there is an advantage that the required amount of the solution can be small.

-Polyimide resin film forming step-In the polyimide resin film forming step, after the polyimide precursor coating film is dried by heating, the temperature is once lowered and then the reaction is carried out by heating to form a polyimide resin film. To do. First, in the polyimide resin film forming step,
For the purpose of removing the aprotic polar solvent which remains excessively in the polyimide precursor coating film, heating and drying are carried out to such an extent that the coating film is not deformed even when it is allowed to stand. The heating conditions are 90 to 170 ° C.
It is preferable that the temperature is 30 to 60 minutes. At that time, the higher the temperature, the shorter the heating time may be. In addition to heating, it is also effective to apply wind. The heating temperature may be increased stepwise or at a constant rate within the time period in order to reduce bubbles of the dissolved gas of the aprotic polar solvent. Incidentally, if too much aprotic polar solvent is removed from the polyimide precursor coating film, the polyimide precursor coating film does not yet retain the strength as a belt, so when the temperature is lowered as described below, the polyimide precursor The coating film may crack. Therefore, to some extent (specifically, 1 in the polyimide precursor coating film)
5 to 45 mass%), it is better to leave the solvent.

Next, in the present invention, the polyimide precursor coating film is heated and dried, and then its temperature is once lowered. Here, "to lower the temperature" means to cool the polyimide precursor coating film, which has been in a high temperature state by heating and drying, together with the cylindrical core body to lower the temperature of the polyimide precursor coating film. . The temperature to be lowered is preferably returned to room temperature. Specifically, for example, the temperature of the polyimide precursor coating film is 23 for 5 minutes to 1 hour.
Reduce to ℃ (room temperature).

As a result, the polyimide precursor coating film shrinks as the temperature decreases. The contraction rate is as small as 0.5 to 2% in the axial direction, but due to this contraction,
Misalignment occurs at the boundary between the polyimide precursor coating and the cylindrical core (the surface of the cylindrical core), and a gap is created between the polyimide precursor coating and the cylindrical core. . Once such a gap is generated, as will be described later, during the heat reaction, even if the shrinkage rate of the polyimide precursor coating film is large, the formed polyimide resin film is displaced from the cylindrical core body. This facilitates the contraction, and allows uniform contraction in the axial direction. On the other hand, if the temperature is not lowered once, the polyimide precursor coating film is likely to shrink non-uniformly in the axial position on the surface of the cylindrical core body during the heating reaction, and the shrinkage is large. Non-uniformity of the film thickness occurs, that is, the part has a large film thickness, and conversely the part with a small shrinkage has a small film thickness. In particular, the film thickness is often thick at the end portions of the polyimide precursor coating film and thin at the central portion.

After lowering the temperature and before carrying out the heating reaction, in order to secure the gap between the polyimide precursor coating film and the cylindrical core, the polyimide precursor Air is preferably blown into the gap between the body coating film and the cylindrical core body. As a method of blowing air, a method of sending compressed air from the end of the film with a nozzle using an air gun or a small hole is previously made in the cylindrical core body,
There is a method of blowing compressed air from there. In addition, when the polyimide resin film is hygroscopically expanded to be peeled off, the air may not be blown.

In the polyimide resin film forming step, as described above, the polyimide precursor coating film, the cylindrical core,
After forming the gap between, preferably 300-450
℃, more preferably around 350 ℃, 20-60 minutes,
By heating and reacting the polyimide precursor coating film, a polyimide resin coating film can be formed. During the heating reaction,
Since the polyimide resin film may swell if the aprotic polar solvent remains, it is preferable to completely remove the residual solvent before reaching the final heating temperature. First, it is dried by heating at a temperature of 200 to 250 ° C. for 10 to 30 minutes to remove the residual solvent, and then the temperature is raised stepwise or at a constant rate to heat to form a polyimide resin film. It is preferable.

In the polyimide resin film forming step of the present invention, before heating and drying, the polyimide precursor coating film is changed to a specific solvent which does not dissolve the polyimide precursor but can dissolve the aprotic polar solvent. You may perform the process which makes it contact and may perform the process of forming a polyimide precursor film. As a result, the aprotic polar solvent exudes from the polyimide precursor coating film into the specific solvent, and the specific solvent permeates instead. Here, since the polyimide precursor is insoluble in a specific solvent, the polyimide precursor is deposited, and the polyimide precursor coating is solidified to such an extent that the coating does not deform even when it is allowed to stand, and a polyimide precursor coating is formed. . As a result, the above-mentioned drying process is performed quickly, and the drying time can be shortened.

The contact between the polyimide precursor coating film and the specific solvent is preferably performed immediately after the step of forming the polyimide precursor coating film. After applying the polyimide precursor solution,
Since the solvent contained in the coating film dries slowly at room temperature as described above, the coating film remains wet forever, and the coating film hangs downward under the influence of gravity. Therefore, immediately after the application of the polyimide precursor, the polyimide precursor coating film is brought into contact with a specific solvent to solidify the polyimide precursor coating film, whereby the sagging can be prevented.

As a method for contacting the polyimide precursor coating film with the specific solvent, a method of immersing the polyimide precursor coating film in the specific solvent is preferable, but in addition, the specific solvent is allowed to flow down to the polyimide precursor coating film. Or you may spray. If the method of applying the polyimide precursor is a centrifugal molding method, the rotation of the cylindrical core may be stopped and immersed in a specific solvent, but while the cylindrical core is being rotated, the coating of the polyimide precursor on the inner surface is performed. You may spray a specific solvent.

When the polyimide precursor is deposited, the elution amount of the aprotic polar solvent from the polyimide precursor coating changes depending on the time of contacting the polyimide precursor coating with the specific solvent. When the aprotic polar solvent is completely removed from the coating film, the precipitated and solidified polyimide precursor film may become brittle, so the aprotic polar solvent remains in an amount of about 5 to 50% by mass. Is preferred. The contact time of the polyimide precursor coating film with the specific solvent for that depends on the film thickness of the polyimide precursor coating film,
About 10 seconds to 10 minutes is preferable. The thicker the film thickness of the polyimide precursor coating, the more solvent is contained, so it is preferable to lengthen the contact time.

As the specific solvent to be brought into contact with the polyimide precursor coating film, a solvent in which the polyimide precursor is insoluble and an aprotic polar solvent can be dissolved is used. Specifically, water, alcohols (for example,
Methanol, ethanol, etc.), hydrocarbons (eg, hexane, heptane, toluene, xylene etc.), ketones (eg acetone, butanone etc.), esters (eg ethyl acetate etc.) can be mentioned. These may be used alone or as a mixture, but water or a mixture containing water is most preferable because it is the easiest to handle.

In the step of forming a polyimide precursor film as described above, when the treatment of bringing the polyimide precursor coating film into contact with the specific solvent is performed, the specific solvent that has permeated into the formed polyimide precursor film and the residual non-solvent Drying is performed for the purpose of removing the polar polar solvent. Drying condition is 50
It is preferably carried out at a temperature of 120 ° C for 10 to 60 minutes. Since the aprotic polar solvent is less likely to evaporate between the specific solvent and the aprotic polar solvent, a state in which the aprotic polar solvent remains in the polyimide precursor film is formed. In this state, the precipitated polyimide precursor is brought into a dissolved state again and becomes transparent. After that, the polyimide precursor film is subjected to a polyimide resin film forming step in the present invention of heating and drying, then once lowering the temperature and then reacting by heating to form a polyimide resin film. Become.

-Polyimide resin film peeling step-After the heating reaction, a polyimide resin endless belt is obtained by a step of peeling the formed polyimide resin film from the cylindrical core. When the polyimide resin film is difficult to peel off from the cylindrical core body, the polyimide resin film can also be peeled by absorbing and expanding the polyimide resin film under high humidity environment. The high humidity environment is 25 to 120 ° C.
The humidity is preferably 80% or more, and the holding time is preferably 5 to 48 hours. If necessary, the endless belt may be subjected to cutting, punching, tape winding, or the like at the end.

According to the method for producing an endless belt made of polyimide resin of the present invention, after the polyimide precursor coating film is dried by heating in the step of forming the polyimide resin film,
Before heating and reacting, the temperature of the polyimide precursor coating film is once lowered, so that a gap is formed between the cylindrical core body and the polyimide precursor coating film, and the polyimide precursor is formed by the gap. Since the coating film shrinks uniformly, the uniformity of the film thickness can be improved, and the polyimide resin film can be easily peeled from the cylindrical core body. Further, according to the method for producing an endless belt made of a polyimide resin of the present invention, since the polyimide resin film is easily separated from the cylindrical core body, the cylindrical core body and the polyimide resin film have a coefficient of thermal expansion. Even if the difference between is set small,
It is possible to prevent the peeling property from being deteriorated. Therefore, it becomes easy to change the composition (type and mixing ratio) of the polyimide precursor used in the polyimide precursor solution for obtaining the polyimide resin film, and it is possible to meet a wide range of required characteristics and costs. Further, the polyimide resin endless belt manufactured by the method for manufacturing the polyimide resin endless belt has an excellent effect that it has a uniform film thickness and can meet a wide range of required characteristics and costs.

The polyimide resin endless belt obtained by the manufacturing method of the present invention can be used as a photoreceptor, a charging means, a transfer means, a fixing means, etc. in an image forming apparatus such as an electrophotographic copying machine or a laser printer.

When the endless belt is used as a transfer belt or a charged body such as a contact charging film, a conductive substance is dispersed in the resin material as needed. As the conductive substance, for example, carbon black, carbon beads granulated carbon black, carbon fiber,
Carbonaceous substances such as graphite, metals or alloys such as copper, silver and aluminum, tin oxide, indium oxide, antimony oxide, conductive metal oxides such as SnO ₂ —In ₂ O ₃ composite oxide, potassium titanate, etc. Conductive whiskers and the like can be mentioned.

When the endless belt is used as a fixing member, it is effective to form a non-adhesive resin film on the surface of the belt in order to improve the releasability of the toner adhering to the surface. Examples of the material for the non-adhesive resin film include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and the like. Fluorine-based resins are preferred. Further, carbon powder may be dispersed in the non-adhesive resin film in order to improve durability and electrostatic offset.

To form these fluororesin films,
A method in which the aqueous dispersion is applied to the surface of the endless belt and baked is preferable. Further, when the adhesion of the fluororesin film is insufficient, there is a method of applying and forming a primer layer on the belt surface in advance, if necessary. Examples of the material of the primer layer include polyphenylene sulfide, polyether sulfone, polysulfone, polyamide imide, polyimide and derivatives thereof, and the like.
Further, it preferably contains at least one compound selected from fluorine-based resins.

Thus, the primer layer is formed on the belt surface,
In order to form the fluororesin film, these may be applied after forming a polyimide resin film (belt) on the surface of the cylindrical core by heating and curing, but applying a polyimide precursor solution. After contacting with water, dry the solvent, or without drying the solvent, the primer layer,
Alternatively, the fluororesin dispersion liquid may be applied, and then heated to simultaneously perform the imide conversion completion reaction and the baking treatment of the fluororesin film. In this case, the adhesion of the fluororesin film may become strong even without the primer layer.

When the endless belt is used as a fixing member,
The thickness is preferably in the range of 25 to 500 μm. The thickness of the primer layer provided as necessary is preferably in the range of 0.5 to 10 μm. The thickness of the fluororesin film is preferably in the range of 4-40 μm. The primer layer and the fluororesin film have a certain degree of flexibility, and since expansion and contraction can follow the polyimide resin film, the coefficient of thermal expansion or the coefficient of hygroscopic expansion of the laminate is polyimide. It can be considered the same as the value of the resin alone.

[0062]

EXAMPLES The present invention will be specifically described below with reference to examples. However, each embodiment does not limit the present invention.

(Example 1) -Polyimide precursor coating film forming step-A 22% by mass concentration polyimide precursor solution A was prepared by synthesizing BPDA and PDA in N, N-dimethylacetamide. The viscosity is 35 Pa · s. Separately, PMDA
And 4,4'-diaminodiphenyl ether with N, N-
A 22 mass% concentration polyimide precursor solution B synthesized in dimethylacetamide was also prepared. The viscosity here is 28
Pa · s. Next, both precursor solutions were mixed at a ratio (mass ratio) of polyimide precursor solution A: polyimide precursor solution B = 3: 7 to obtain a polyimide precursor solution.

Using this polyimide precursor solution, as shown in FIG.
By a cyclic coating method as shown, a polyimide precursor coating film
Formed. The cylindrical core 1 has an outer diameter of 68 mm and a length of 4
A 00 mm aluminum cylinder was prepared. Such a
Luminium cylinder has an outer diameter of 70 mm and a length of 400 mm
The aluminum blank tube of is heated at 350 ° C for 10 minutes,
After cooling down, the surface is cut to an outer diameter of 68 mm.
In addition, by blasting with spherical alumina particles
The surface is roughened to Ra 0.8 μm. So
The surface of the silicone release agent (trade name: KS70
0, manufactured by Shin-Etsu Chemical Co., Ltd., and applied at 300 ° C for 1:00
In the meantime, it was baked. Thermal expansion of the used cylindrical core 1
Expansion rate is 23 × 10 ^-6Was / K. As the annular body 5,
Outer diameter 110 mm, smallest inner diameter 69 mm, height 30 mm
Of aluminum was manufactured. The inner wall is sloped
It

The inner surface of the cylindrical core 1 has an inner diameter of 66 mm.
It was passed through an annular coating tank 3 ′ having an inner diameter of 150 mm and a height of 50 mm, to which an annular seal material 9 made of polyethylene having a central hole of 1 was attached. Then, the polyimide precursor solution 2 is placed in the annular coating tank 3 ′, the annular body 5 is arranged,
The cylindrical core 1 was lifted at 0.5 m / min to apply the coating. As a result, a polyimide precursor coating film 4 having a wet film thickness of about 500 μm was formed on the surface of the cylindrical core body 1.

-Polyimide resin film forming step-Next, while the cylindrical core 1 is horizontal and rotated at 20 rpm, it is dried at room temperature for 5 minutes and then at 80 ° C for 20 minutes.
It was dried by heating at 100 ° C. for 1 hour. As a result, a polyimide resin coating film having a thickness of about 150 μm was fixed. Next, the cylindrical core body 1 on which the polyimide precursor coating film was formed was cooled to room temperature. At this time, the polyimide precursor coating film shrank by 1% in the axial direction.

Then, at one end of the cylindrical core 1, the width 2
A 0 mm polyester tape was wrapped around for one coat. Next, a PFA dispersion water-based paint (trade name: AW5000, manufactured by Daikin Industries, Ltd.) has an inner diameter of 9
It was placed in a coating tank having a height of 0 mm and a height of 480 mm, and the cylindrical core body 1 was dipped in the coating tank so that the coating portion was on the lower side and the polyimide precursor coating film on the upper portion was left by 5 mm. Then, it was pulled up at a speed of 0.3 m / min to form a PFA coating film. After drying at 80 ° C. for 10 minutes, the polyester tape was removed. Further, 20 minutes at 150 ℃, followed by 2
It was dried by heating at 00 ° C. for 20 minutes. Then 380 ° C
Was heated for 30 minutes to form a polyimide resin film and the PFA coating film was baked.

-Polyimide resin film peeling step-After cooling to room temperature, the polyimide resin film is peeled off from the cylindrical core 1 to give a film thickness of 75 μm and a uniform film thickness of 30 μm on the polyimide resin film. An endless belt having a PFA layer could be obtained. The coefficient of thermal expansion of the formed polyimide resin film was 15 × 10 ⁻⁶ / K. In this step, it was confirmed that the formed polyimide resin film was easily separated from the cylindrical core body 1.
This is because, as described above, the coefficient of thermal expansion of the cylindrical core body 1 used in this example is 23 × 10 ⁻⁶ / K, and there is a large difference in coefficient of thermal expansion from the polyimide resin film. Is.
The obtained polyimide resin endless belt in Example 1 could be suitably used as a fixing belt for electrophotography.

(Example 2) In Example 1, the polyimine
The polyimide precursor solution in the process of forming the precursor film
Same as Example 1 except that the composition described below was changed.
Then, an endless belt was produced. Melting of the polyimide precursor
Liquid A and the above polyimide precursor solution B
In the ratio of precursor solution A: polyimide precursor solution B = 2: 8
Mix and further mix at 10% by weight, based on their solid content,
Potassium tannate fiber (Tismo: trade name, Otsuka Chemical Co., Ltd.
Made as a fibrous substance, and a polyimide precursor solution
did. In this embodiment, the formed polyimide resin skin
The coefficient of thermal expansion of the film is 15 × 10 ^-6/ K, cylindrical core
The coefficient of thermal expansion of 1 is 23 × 10^-6Was / K.

In the polyimide resin film peeling process of this example, it was confirmed that the polyimide resin film formed was easily peeled from the cylindrical core 1. This is because there is a large difference in coefficient of thermal expansion with the polyimide resin film, as in Example 1. The thus obtained polyimide resin endless belt in Example 2 was also suitable for use as a fixing belt for electrophotography.

(Example 3) -Polyimide precursor coating film forming step-In Example 1, 14 mass% of conductive potassium titanate was added to the solid content of the polyimide precursor solution in the polyimide precursor coating film forming step. Fiber (Dentor: trade name, made by Otsuka Chemical Co., Ltd.) and 4% by mass of carbon black (Conductex 975, made by Columbia Carbon Co., Ltd.)
Was added and dispersed by a sand mill to prepare a polyimide precursor solution in Example 3.

Using this polyimide precursor solution, a polyimide precursor coating film was formed by an annular coating method as shown in FIG. As the cylindrical core 1, an aluminum cylindrical body having an outer diameter of 168 mm and a length of 450 mm was prepared. The surface of such an aluminum cylinder was subjected to a surface roughening treatment and a treatment with a silicone-based releasing agent in the same manner as in Example 1.
The coefficient of thermal expansion of the used cylindrical core body 1 was 23 × 10 ⁻⁶ / K. As the annular body 5, an aluminum hollow body having an outer diameter of 250 mm, a minimum inner diameter of 169 mm, and a height of 40 mm was produced. The inner wall is sloped.

The cylindrical core 1 has an inner diameter of 166 m on its bottom surface.
It was passed through an annular coating tank 3 ′ having an inner diameter of 250 mm and a height of 50 mm, to which an annular seal material 9 made of polyethylene having a central hole of m was attached. And the annular coating tank 3 '
The polyimide precursor solution 2 was put in the above, the annular body 5 was arranged, the cylindrical core body 1 was raised at 0.3 m / min, and coating was performed. As a result, a polyimide precursor coating film 4 having a wet film thickness of about 500 μm was formed on the surface of the cylindrical core body 1.

-Polyimide resin film forming step-Next, while the cylindrical core 1 is horizontal and rotated at 60 rpm, it is dried at room temperature for 5 minutes and then at 80 ° C for 20 minutes.
It was heated and dried at 130 ° C. for 1 hour. Next, the cylindrical core body 1 on which the polyimide precursor coating film was formed was cooled to room temperature. At this time, the polyimide precursor coating film has a thickness of 0.
Shrink 5%. Then, compressed air was blown by an air gun between the end of the polyimide precursor coating film and the cylindrical core body 1. As a result, an air layer was formed between the polyimide precursor coating film and the cylindrical core body 1, and the formation of the gap was ensured. As a result, a polyimide resin coating film having a thickness of about 150 μm was fixed. After that, the cylindrical core 1 was set vertically, and heat reaction was performed at 200 ° C. for 30 minutes and 380 ° C. for 30 minutes to obtain a polyimide resin film.

-Polyimide resin film peeling step-After cooling to room temperature, the polyimide resin film was peeled from the cylindrical core 1 to obtain a uniform endless belt having a film thickness of 70 µm. The coefficient of thermal expansion of the formed polyimide resin film was 16 × 10 ⁻⁶ / K.
In this step, it was confirmed that the formed polyimide resin film was easily separated from the cylindrical core body 1. This is because there is a large difference in coefficient of thermal expansion with the polyimide resin film, as in Example 1. Example 3 obtained
The endless belt made of a polyimide resin in No. 1 had a volume resistivity of about 10 ⁹ Ω · cm and could be suitably used as a transfer belt for electrophotography.

Comparative Example 1 In Example 3, after heating and drying the polyimide precursor coating film, without cooling to room temperature,
After heating and drying, the polyimide resin endless belt of Comparative Example 1 was produced in the same manner as in Example 3 except that the reaction was continuously performed at 200 ° C. for 30 minutes and 380 ° C. for 30 minutes. The obtained polyimide resin endless belt had a film thickness of 73 μm at the position 8 cm from the end and 68 μm at the center, which proved to be non-uniform, and it was difficult to use it as an electrophotographic transfer belt. there were.

(Embodiment 4) A cylindrical core having an outer diameter of 6
A cylinder made of SUS304 having a length of 8.1 mm and a length of 400 mm was prepared. The surface was roughened to Ra 0.8 μm by blasting with spherical alumina particles. A silicone release agent (same as in Example 1) is applied to the surface of the surface of
A baking treatment was performed at 0 ° C. for 1 hour. The coefficient of thermal expansion of the cylindrical core used was 18 × 10 ⁻⁶ / K. Since this value is smaller than that of aluminum, the outer diameter was made 0.1 mm larger than that of the aluminum core body of Example 1 so that the outer diameter during heating was the same. Then, in the polyimide precursor coating film forming step, the inner diameter of the minimum portion of the annular body was adjusted to 69.1 mm in accordance with the increase of the outer diameter of the core body, and the PFA layer was formed on the polyimide resin film in the same manner as in Example 1. An endless belt having The coefficient of thermal expansion of the formed polyimide resin film was 15 × 10 ⁻⁶ / K. Next, the polyimide resin film together with the cylindrical core,
Hold for a whole day in a high temperature and high humidity environment room at 30 ° C and 85% RH,
Absorbed water. As a result, the polyimide resin film expanded about 0.1% and could be easily peeled off from the cylindrical core. When the polyimide resin film after peeling was returned to a normal environment, an endless belt having the same results as in Example 1 including the belt diameter was obtained.

Example 5 A 22% by mass concentration polyimide precursor solution C prepared by synthesizing BPDA and 4,4′-diaminodiphenyl ether in N-methylpyrrolidone was prepared. The viscosity is 40 Pa · s. Carbon black (trade name: Special Black 4, manufactured by Degussa Huls) was mixed in this solution at a solid content mass ratio of 23%, and then dispersed by a sand mill for 24 hours, and further an alkyl-modified silicone leveling agent (trade name: DC3PA, Dow). Corning Torre Silicone) has a nonvolatile content of 500
It was added so as to be ppm. On the other hand, the outer peripheral surface of an aluminum cylindrical tube having an outer diameter of 168 mm and a length of 400 mm was roughened in the same manner as in Example 1 to form a silicone release agent layer to obtain a core. As an annular body, outer diameter 200 mm, inner diameter 1
A hollow ring made of stainless steel with a height of 80 mm and a height of 30 mm is produced, and inside this, a Teflon (R) having an outer diameter of 180 mm, a triangular cross section, and an inner diameter of the narrowest part is 169 mm.
The thing which fitted the ring made was prepared. Then, the ascending speed of the core is set to 0.9 to so that the ascending height of the annular body from the liquid surface of the PI precursor solution is always 15 mm higher than the stop position.
It was adjusted to 0.7 m / min and applied in the same manner as in Example 1. Then, drying and heating / baking were performed in the same manner as in Example 1. The coefficient of thermal expansion of the formed polyimide resin film is 2
It was 1 × 10 ⁻⁶ / K. Next, the polyimide resin film together with the cylindrical core was kept for a whole day in a high temperature and high humidity environment chamber at 35 ° C. and 90% RH to absorb water sufficiently. As a result, the polyimide resin film expanded about 0.1% and could be easily peeled off from the cylindrical core. This endless belt could be suitably used as a transfer belt for electrophotography. The hardness of the belt surface was half that of polyimide composed of BPDA and PDA, and even when it was brought into contact with the photoconductor, it was scarcely scratched.

[0079]

EFFECTS OF THE INVENTION According to the present invention, a method for producing a polyimide resin endless belt capable of improving the film thickness uniformity and easily peeling the polyimide resin coating from the cylindrical core body. Can be provided. It is also possible to provide a method for manufacturing an endless belt made of a polyimide resin, which can meet a wide range of required characteristics and costs. Further, it is possible to provide an endless belt made of a polyimide resin, which is manufactured by the method for manufacturing an endless belt made of a polyimide resin, has a uniform film thickness, and meets a wide range of required characteristics and costs.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of an apparatus used in a dip coating method in which a film thickness is controlled by an annular body.

FIG. 2 is an enlarged perspective view of an essential part for explaining the installation state of the annular body shown in FIG.

FIG. 3 is a schematic cross-sectional view showing the shape of the wall surface of the hole provided in the annular body, wherein (a) is a linear wall surface and (b) is a curved wall surface.

FIG. 4 is a schematic configuration diagram showing an example of an apparatus used in the annular coating method.

[Explanation of symbols]

1 Cylindrical core 2 Polyimide precursor solution 3 coating tanks 3'ring coating tank 4 Polyimide precursor coating 5 ring 6 Annular hole 7 Inclined linear annular inner wall 8 curved inner wall 9 Annular sealing material

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 15/02 101 G03G 15/02 101 4F205 15/16 15/16 4J002 15/20 102 15/20 102 21/00 350 21/00 350 // B29K 79:00 B29K 79:00 B29L 29:00 B29L 29:00 F term (reference) 2H033 AA02 AA31 BA11 BA12 BB04 BB05 BB12 2H035 CA05 CB06 2H171 FA07 FA09 FA11 FA15 FA19 FA30 GA01 GA15 PA05 PA08 PA13 PA14 QA09 QA17 QB07 QC05 QC14 QC40 TA11 UA02 UA03 UA05 UA07 UA10 UA22 XA03 2H200 FA13 HA03 HB13 HB22 HB45 HB46 HB47 JA02 JB06 JB45 JB46 JB47 A01 A17 A17 A01 A17 A20 A17 A20 A17 A20 A17 A20 A17 A20 A17 A20 A17 A20 A17 A20 A17 A20 MAF MA17 MA20 MA17 MA20 MA17 MA20 MA17 MA17 MA20 MA17 MA17 MA20 MA17 MA20 MA17 MA17 MA20 MA20 AG16 GA06 GB01 GC01 GF24 GN18 GN21 GW05 GW31 4J002 CM041 DA026 DE106 DE136 DE186 DJ006 DK006 FA046 GM01

Claims (6)

[Claims] 1. A polyimide precursor coating film forming step of applying a polyimide precursor solution to the surface of a cylindrical core to form a polyimide precursor coating film, and heating and drying the polyimide precursor coating film, Once
After lowering the temperature, a polyimide resin film forming step of reacting by heating to form a polyimide resin film, and a polyimide resin film peeling step of peeling the polyimide resin film from the cylindrical core are characterized. And a method for manufacturing an endless belt made of a polyimide resin. 2. In the step of forming the polyimide resin film, air is blown into a gap between the cylindrical core body and the polyimide precursor coating film after the temperature is once lowered and before the heating reaction. Blowing is carried out.
The method for producing an endless belt made of a polyimide resin according to 1. 3. The method for producing an endless belt made of a polyimide resin according to claim 1, wherein the polyimide precursor solution contains a fibrous substance. 4. The method for producing an endless belt made of a polyimide resin according to claim 3, wherein the fibrous substance is made of an inorganic needle-shaped single crystal. 5. The method for producing a polyimide resin endless belt according to claim 1, wherein in the polyimide resin film peeling step, the polyimide resin film is hygroscopically expanded to be peeled off. . 6. An endless belt made of a polyimide resin, which is manufactured by the method for manufacturing an endless belt made of a polyimide resin according to claim 1.