JP2003245932A - Method for manufacturing polyimide resin-made endless belt and polyimide resin-made endless belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a polyimide resin-made endless belt using the non-proton based polar solvent, which enables an application time of a polyimide precursor film to be shortened while the polyimide precursor solvent comprising a polyimide precursor of a high polymerization degree and a non-proton based polar solvent is used, and to provide the polyimide resin- made endless belt which is manufactured by the method for manufacturing the polyimide resin-made endless belt, free from an irregularity in a film thickness and high in a tensile strength. <P>SOLUTION: The method for manufacturing the polyimide resin-made endless belt comprises a process for forming a polyimide precursor film by applying the polyimide precursor solution in a heated state to a surface of a cylindrical core body; and a process for forming a polyimide resin film by heating the polyimide precursor film. The polyimide resin-made endless belt to be manufactured by the manufacturing method is also provided. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoconductor, a charging body, a transfer body or a fixing body in an image forming apparatus utilizing an electrophotographic process such as a copying machine or a printer, and further to various fields. The present invention relates to a method for producing an endless belt made of a polyimide resin that can be preferably used, and an endless belt made of a polyimide resin produced by the production method.

[0002]

2. Description of the Related Art The electrophotographic process is disclosed in Japanese Examined Patent Publication No.
A number of methods are known as described in Japanese Patent Publication No. 910, etc. Generally, a latent image is formed electrically on the surface of a photoconductor (latent image carrier) using a photoconductive substance by various means, and the formed latent image is developed with a toner. After forming the image, the toner image on the surface of the photoconductor is
The fixed image is transferred through a plurality of steps of transferring to the surface of a transfer material such as paper with or without an intermediate transfer member and fixing the transferred image with heat, pressure, heat and pressure, or solvent vapor. Is formed.

In an image forming apparatus utilizing such an electrophotographic process, various rotating bodies made of metal, plastic, or rubber are used as a photoconductor, a charging body, a transfer body, a fixing body, etc. In order to reduce the size or improve 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 for such an endless belt, a polyimide resin is particularly preferable in terms of strength, dimensional stability, heat resistance and the like.

In order to produce an endless belt made of a polyimide resin, for example, as disclosed in Japanese Patent No. 2986870, a polyimide precursor solution is uniformly applied to the inner surface of a cylindrical core, and the endless belt is rotated. There is a centrifugal molding method of drying and then heat curing. But with this method,
There is a problem that it takes a lot of man-hours and time to manufacture the endless belt.

Another method for producing an endless belt made of a polyimide resin is disclosed in, for example, JP-A-61-273919.
There is also a method in which a cylindrical core body having a desired outer diameter is prepared, a polyimide resin film is formed on the surface of the core body by a dip coating method, and then the core body is peeled off, as described in Japanese Patent Laid-Open Publication No. 2003-242242. This method has an advantage that the number of steps for manufacturing the endless belt is small, but has a problem that it is difficult to form a thick film.

Here, the polyimide precursor solution used in the method for producing an endless belt made of a polyimide resin is a solution of a polyamic acid obtained by polymerization of an acid anhydride and a diamine in a solvent. As the solvent, an aprotic polar solvent such as N-methyl-2-pyrrolidone or N, N-dimethylacetamide is used due to the properties of the polyamic acid resin.

Since the endless belt made of polyimide resin is mainly used for being stretched, the higher the tensile strength of the polyimide resin, the more desirable. Improving the tensile strength is achieved by increasing the degree of polymerization of the polyamic acid that is a polyimide precursor. However, as the degree of polymerization increases, the solution viscosity of the polyimide precursor solution also increases, so due to the high solution viscosity, the time required for film formation increases and the coating speed increases. There is a problem that you can not. In addition, when the coating speed cannot be increased, there is a problem that foreign matter is likely to adhere during coating, resulting in a high manufacturing cost.

For the problem that the coating speed cannot be increased, even if the polymerization degree of the polyimide precursor is lowered and a polyimide precursor solution having a low solution viscosity is used, the coating step can be speeded up. In addition to the problem that the tensile strength is reduced, if the solution viscosity is too low, the polyimide resin film is easily peeled off, due to the effect of the release agent applied to the surface of the cylindrical core body in advance, immediately after application. However, there is a problem in that the film may cause surface defects such as unevenness and cissing.

On the other hand, there is also a polyimide resin produced without using an aprotic polar solvent, as disclosed in, for example, Japanese Patent Application Laid-Open No. 10-81749. However, this type of polyimide resin has mechanical strength,
It has a disadvantage that the tensile strength is smaller than that of a polyimide resin prepared by using an aprotic polar solvent.

[0010]

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 a method for producing an endless belt made of a polyimide resin using an aprotic polar solvent,
While using a polyimide precursor solution consisting of a polyimide precursor having a high degree of polymerization and an aprotic polar solvent,
An object of the present invention is to provide a method for producing an endless belt made of a polyimide resin capable of shortening the application time of a polyimide precursor coating. Another object of the present invention is to provide an endless belt made of a polyimide resin, which is produced by the method for producing an endless belt made of a polyimide resin and has no unevenness in film thickness and high tensile strength.

[0011]

The above problems can be solved by the following means. That is, the present invention is

<1> A step of applying a heated polyimide precursor solution to the surface of a cylindrical core to form a polyimide precursor coating film, and heating the polyimide precursor coating film to form a polyimide resin film. And a step of forming the endless belt made of a polyimide resin.

<2> The method for producing an endless belt made of a polyimide resin according to <1>, wherein the heated polyimide precursor solution is a solution prepared in a range of room temperature to 50 ° C. Is.

<3> The method for producing a polyimide resin endless belt according to <1> or <2>, wherein the solution viscosity of the polyimide precursor solution is 20 to 100 Pa · s.

<4> The mass average molecular weight of the polyimide precursor in the polyimide precursor solution is 40,000 to 2
The method for producing an endless belt made of a polyimide resin according to any one of <1> to <3>, wherein the endless belt is 100,000.

<5> A polyimide resin endless belt characterized by being manufactured by the method for manufacturing a polyimide resin endless belt according to any one of <1> to <4>.

<6> The polyimide resin endless belt according to <5>, which has a tensile strength of 200 MPa or more.

[0018]

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 applying a heated polyimide precursor solution to a surface of a cylindrical core to form a polyimide precursor coating film (hereinafter , "Polyimide precursor coating film forming step") and a step of heating the polyimide precursor coating film to form a polyimide resin film (hereinafter referred to as "polyimide resin film forming step"). In other words, the method further includes a step of peeling the polyimide resin film from the cylindrical core body and, if necessary, other steps. 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, a conventionally known one can be used. Further, as the aprotic polar solvent, N-methyl-2-pyrrolidone, N,
Conventionally known compounds such as N-dimethylacetamide, acetamide, N, N-dimethylformamide and the like can be used. The mixing ratio and the like in the preparation are appropriately selected and performed.

In the present invention, the prepared polyimide precursor solution needs to be in a heated state when applied to the surface of the cylindrical core. Here, the "heated state" means that the temperature of the polyimide precursor solution is higher than room temperature. Thereby, the solution viscosity of the polyimide precursor solution can be made lower than that at room temperature. That is, even if a polyimide precursor solution consisting of a polyimide precursor having a high degree of polymerization and an aprotic polar solvent is used, the solution viscosity is lower than that at room temperature, so the solution viscosity It is possible to suppress a decrease in coating speed caused by a high value. As a result, speeding up of the coating process can be achieved.

The upper limit temperature of the polyimide precursor solution in a heated state is that the polyimide precursor is deteriorated, the life of the produced polyimide resin film is shortened, and evaporation of the aprotic polar solvent is significantly accelerated. In terms of
It is preferably 50 ° C. Therefore, the preferable range of the solution temperature of the polyimide precursor solution is room temperature or higher and 50 or lower, and particularly preferably 40 ° C. or higher and 50 ° C. or lower.

As described above, when a polyimide precursor solution having a predetermined composition is used, by changing the solution temperature,
The solution viscosity can be adjusted. For example, a polyimide precursor solution prepared by dissolving a polyamic acid (polyimide precursor) having a mass average molecular weight of 150,000 in N-methyl-2-pyrrolidone (aprotic polar solvent) is at room temperature. At (22 ° C), the solution viscosity is 13
Although it is 2 Pa · s, the viscosity is 52 to 63 Pa · by setting the solution temperature of the polyimide precursor solution to 40 to 50 ° C.
It becomes possible to lower it to s. As a result, by using the polyimide precursor solution in such a heated state, it becomes possible to apply it at a speed 2.1 to 2.5 times that at room temperature (about 22 ° C.).

The solution viscosity range of the polyimide precursor solution in a heated state is 20 to 100 Pa.s so that the polyimide precursor coating film is free from uneven thickness and repellency, and the coating process can be speeded up. Is preferably adjusted to the range of 30 to 80 Pa · s, more preferably to the range of 30 to 80 Pa · s, and particularly preferably to the range of 40 to 70 Pa · s.

The mass average molecular weight of the polyimide precursor used in the heated polyimide precursor solution is
Depending on the tensile strength required for the manufactured polyimide resin endless belt, it is appropriately adjusted.
It is preferably in the range of 20,000 to 200,000, and more preferably in the range of 50,000 to 180,000. The mass average molecular weight of the polyimide precursor,
If it is less than 40,000, the desired tensile strength may not be obtained, and if it is more than 200,000, the viscosity becomes very high, which makes it difficult to form a coating film. There may be a problem that the rigidity of the polyimide resin film is too high.

Further, the content of the polyimide precursor used in the heated polyimide precursor solution is preferably 10% by mass or more, and more preferably 15% by mass or more. When the content of the polyimide precursor is less than 10% by mass, there may be a problem that a desired solution viscosity cannot be obtained and a problem that a drying speed becomes slow and a polyimide precursor coating film has uneven thickness. .

In the step of forming the polyimide precursor coating film, the polyimide precursor solution is coated on the cylindrical core body to form the polyimide precursor coating film. A small amount of polyimide precursor solution is pushed up from the central part of the coating tank to be pushed up, a cylindrical core is immersed in a polyimide precursor solution and is pulled up to be immersed, and a cylindrical core is rotated on its surface. Known existing methods such as a flow coating method for discharging a polyimide precursor solution and a blade coating method for metallizing a coating with a blade at that time 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. It should be noted that "coating on a cylindrical core" means coating on the surface of the side surface of the cylindrical core which may include a cylinder, and when a layer is provided on the surface, on the surface of the layer. Means

In the step of forming the polyimide precursor coating film, when the polyimide precursor solution is applied by the push-up coating method,
Since the polyimide precursor solution has a very high viscosity, the film thickness may be too thicker than desired. In that case, a push-up coating method in which the film thickness is controlled by the following annular body can be applied.

A push-up coating method in which the film thickness is controlled by an annular body will be described with reference to the drawings. FIG. 1 is a schematic diagram for explaining the present coating method, in which a polyimide precursor solution 2 placed in a coating tank 3 is provided with a hole 6 larger than the outer diameter of the cylindrical core 1 in cross section. 5 is floated, the cylindrical core body 1 is immersed in the polyimide precursor solution 2 through the hole 6, and then pulled up. However, the figure shows only the coating main part, and other devices are omitted.

The push-up 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 for a push-up coating method in which the film thickness is controlled by an annular body. However, the figure shows only the main part of coating, and other devices are omitted. As shown in FIG. 1, in this push-up coating method, a ring-shaped body 5 having a hole larger than the outer diameter of a cylindrical core 1 is floated on a polyimide precursor solution 2 filled in a coating tank 3, This is a coating method in which the cylindrical core body 1 is dipped in the polyimide precursor solution 2 through the hole 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.

Further, fixing means for temporarily fixing the annular body 5 may be provided so that the annular body 5 is located in the central portion 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 detachable so that the annular body 5 can freely move when the cylindrical core 1 is pulled up after being immersed. Will be placed.

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. In addition, the gap between the outer diameter of the cylindrical core 1 and the diameter of the hole 6 is preferably 1 to 3 times the desired wet film thickness. It is set to 1 to 3 times because 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 have a straight line shape shown 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 have 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. Also, FIG.
As shown in (c), a part of the inner wall (uppermost part) is a polygonal line shape 9 forming a narrowest part.
In particular, as shown in FIGS. 3A to 3C, it is preferable that the lower part soaked in the polyimide precursor solution 2 has a wide bottom. here,
FIG. 3 shows the shape of the wall surface of the hole provided in the annular body, where (a) is a linear wall surface, (b) is a curved wall surface,
(C) is a schematic sectional drawing which shows a polygonal wall surface.

When the push-up coating is performed, the cylindrical core body 1 is immersed in the polyimide precursor solution 2 through the hole 6. At that time, the cylindrical core 1 is prevented from coming into contact with the annular body 5.
Here, the polyimide precursor solution 2 in which the cylindrical core 1 is immersed is heated to a predetermined temperature in the coating tank 3 with a heating device, for example, a temperature of 40 to 50 ° C., or
The coating tank 3 equipped with a heat retaining device has one of the modes in which the one heated in advance to 40 to 50 ° C. is injected. Then, the cylindrical core 1 is pulled up through the hole 6.
At this time, the film 4 is formed by the gap between the cylindrical core 1 and the hole 6. The pulling speed is 100-1500 mm
/ Min is preferable. The polyimide precursor solution preferable for this coating method has a solid content concentration of 10 to 40% by mass and a viscosity of 20 to 100 Pa · s.

The annular body 5 can move freely on the liquid surface of the polyimide precursor solution 2. Moreover, the hole 6 of the annular body is circular, and the outer circumference of the cylindrical core 1 is also circular. Therefore, when pulling up the cylindrical core 1 through the hole 6, the frictional resistance between the cylindrical core 1 and the annular body 5 becomes constant,
The annular body 5 moves. That is, when pulling up the cylindrical core 1,
When the gap between the annular body 5 and the cylindrical core 1 is narrowed at a certain position, the frictional resistance is increased in the narrowed portion. On the other hand, on the other side, the frictional resistance decreases,
The frictional resistance may be temporarily 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 1.

Further, the position where the frictional resistance is 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, it is possible to provide the cylindrical core 1 with a constant wet film thickness.

Further, the coating apparatus used for the push-up coating method is
A cylindrical core body holding means for holding the cylindrical core body, and, if desired, a first moving means for vertically moving the holding means and / or a vertically moving container for containing the polyimide precursor solution. It may have two moving means. 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 push-up coating method in which the film thickness is controlled by the annular body, the sagging at the upper end of the cylindrical core is reduced due to the use of the highly viscous polyimide precursor solution, The film thickness can be easily made uniform.

It is desirable that the cylindrical core is in a state close to room temperature during the application of the polyimide precursor solution and immediately after the application. When the cylindrical core is warmer than room temperature, the polyimide precursor coating film exists on the surface of the cylindrical core body in a state of low viscosity, the coating film moves actively, and the cylindrical core body upper part during coating. It is easy to cause dripping in. On the other hand, when the cylindrical core is used after cooling to room temperature or lower, the heat of the polyimide precursor solution is rapidly removed and the temperature of the solution is remarkably lowered, and furthermore, moisture absorption of the solution occurs due to dew condensation, which deteriorates the solution. It may happen.

-Polyimide resin film forming step-In the polyimide resin film forming step, the coating film is not deformed even if it is allowed to stand for the purpose of removing excessive aprotic polar solvent remaining in the polyimide precursor coating film. Do some drying. The drying condition is 30 to 6 at a temperature of 90 to 120 ° C.
It is preferably 0 minutes. In addition to heating, it is also effective to apply wind. The drying temperature is preferably increased stepwise or at a constant rate within the time period in order to reduce formation of bubbles in the dissolved gas of the aprotic polar solvent.

In the step of forming a polyimide resin film, after the drying, the polyimide precursor film is formed by heating the polyimide precursor coating film at preferably 300 to 450 ° C., more preferably around 350 ° C. for 20 to 60 minutes. can do. During heating, since the polyimide resin film may swell when the aprotic polar solvent remains, it is preferable to completely remove the residual solvent before heating, specifically, before heating. At 200-250 ° C
It is preferable that the residual solvent is removed by heating and drying at the temperature of 10 to 30 minutes, and then the temperature is raised stepwise or at a constant rate to heat to form the polyimide resin film.

After heating, an endless belt made of polyimide resin is obtained through a step of peeling the formed polyimide resin film from the cylindrical core. If necessary, the endless belt may be subjected to cutting, punching, tape winding, or the like at the end.

In the present invention, the material of the cylindrical core is appropriately selected according to the purpose, and for example, a metal such as aluminum, copper or stainless steel can be preferably used. Further, 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 may adhere to the surface of the cylindrical core body in the polyimide resin film forming step. Since the property 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 may be plated with chromium or nickel, the surface may be coated with a fluororesin or silicone resin surface, or the surface of the polyimide resin should not be adhered. It is effective to apply the release agent of. Further, it is also effective to form the cylindrical core body itself from a fluorine-based resin having releasability.

According to the method for producing an endless belt made of a polyimide resin of the present invention, since the polyimide precursor solution is used in a heated state in the step of forming the polyimide precursor coating film, a polyimide precursor having a high degree of polymerization, Also, even if a polyimide precursor solution composed of an aprotic polar solvent and having a high viscosity at room temperature is used, the coating time of the polyimide precursor coating can be shortened and the coating process can be speeded up. Further, the polyimide resin endless belt manufactured by the method for manufacturing the polyimide resin endless belt has no film thickness unevenness because the coating step is accelerated, and uses a high degree of polymerization polyimide precursor. Therefore, it has an excellent effect of high tensile strength.

The polyimide resin endless belt obtained by the manufacturing method of the present invention (the polyimide resin endless belt of the present invention) is a photosensitive member, a charged member, or a photosensitive member in an image forming apparatus utilizing an electrophotographic process such as a copying machine or a printer. Transfer body,
It can be used as a fixing member.

The polyimide resin endless belt of the present invention is
When used as a charged body such as a transfer belt or a contact charging film, a conductive substance is dispersed in a resin material as needed. As the conductive material, for example, carbon black, carbon beads obtained by granulating carbon black, carbon fiber, carbon-based material such as graphite, copper, silver, metal or alloy such as aluminum, tin oxide,
Indium oxide, antimony oxide, SnO ₂ —In ₂ O ₃
Examples thereof include conductive metal oxides such as complex oxides, conductive whiskers such as potassium titanate, and the like.

The polyimide resin endless belt of the present invention can also be used as a fixing member (fixing belt). The fixing belt is in pressure contact with the fixing roll and is driven to rotate, thereby forming a nip for fixing the toner image by passing the recording paper on which the toner image is formed. As described above, since the fixing belt needs to be brought into pressure contact with the fixing roll, particularly high tensile strength is required.

In order to manufacture an endless belt made of a polyimide resin used as a fixing member, the mass average molecular weight of the polyimide precursor used in the polyimide precursor solution is 40,
000 to 200,000 is preferable,
The range of 50,000 to 180,000 is more preferable.

Since the polyimide precursor solution containing the polyimide precursor in the above molecular weight range has a high solution viscosity at room temperature, it was heated to 35 to 55 ° C. in the above-mentioned polyimide precursor coating film forming step. It is preferably used in a state, and more preferably used in a state of being heated to 40 to 50 ° C.

Thus, in the polyimide precursor coating film forming step, the polyimide resin produced by adjusting the mass average molecular weight of the polyimide precursor to the above range and the solution temperature of the polyimide precursor solution to the above range The tensile strength of endless belts is required as a fixing belt. 3
It becomes 00 MPa or more. If the tensile strength is less than 300 MPa and the polyimide resin endless belt is stretched and used, the endless belt may break.
It is difficult to use as a fixing body.

When the polyimide resin endless belt of the present invention is used as a fixing member (fixing belt), a releasable resin film is formed on the surface of the fixing belt in order to improve the releasability of the toner adhering to the surface. Is effective. Examples of the material for the releasable resin film include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (P
FA), a fluororesin such as tetrafluoroethylene-hexafluoropropylene copolymer (FEP) and the like are preferable. Further, carbon powder may be dispersed in the releasable resin film in order to improve durability and electrostatic offset.

To form these fluororesin films,
A method of applying the aqueous dispersion to the surface of the endless belt made of a polyimide resin and baking it 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 it is preferable that the primer layer further contains at least one compound selected from fluororesins.

Thus, the primer layer,
In order to form a fluororesin film, a polyimide resin film (belt) may be applied on the surface of the cylindrical core after heat curing to form a polyimide resin film (belt), but the primer may be applied without drying the solvent. The layer and the fluororesin dispersion 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,
Even without the primer layer, the adhesion of the fluororesin film may become strong.

When the polyimide resin endless belt of the present invention is used as a fixing member, its thickness is 25 to 50.
It is preferably in the range of 0 μm. The thickness of the primer layer provided as necessary is preferably in the range of 0.5 to 10 μm. Also, the thickness of the fluororesin film is 4 to 40 μm.
A range of m is preferred.

[0056]

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

(Example 1) [Production of endless belt made of polyimide resin] High-viscosity polyimide precursor solution (trade name: U varnish S, high-viscosity type,
Ube Industries) was prepared. The solution viscosity is room temperature 22 ℃
Was 132 Pa · s. Using this solution, push-up coating was performed by the coating apparatus shown in FIG. This polyimide precursor solution was poured into the coating tank 3 equipped with a heating device and heated so that the solution temperature became 50 ° C. At this time, the solution viscosity was 52 Pa · s.

The cylindrical core 1 has an outer diameter of 67.7 mm,
Prepare an aluminum cylinder with a length of 500 mm, apply a silicone release agent (trade name: KS700, manufactured by Shin-Etsu Chemical Co., Ltd.) on the surface, bake at 300 ° C for 1 hour, and bring it to room temperature. Let it cool naturally. On the other hand, as the annular body 5, a hollow annular body made of aluminum having an inner diameter of 68.9 mm was produced. The weight of the annular body 5 was 225 g.

After the annular body 5 was floated on the polyimide precursor solution, the cylindrical core body 1 was pulled up, and the coating speed limit was examined. The coating speed limit is a speed within a range in which the ring-shaped body 5 does not rise above the liquid surface, and becomes slower as the solution viscosity increases. When the annular body 5 rises above the liquid level beyond the coating speed limit, the annular body 5 drops to the liquid surface after the coating is completed, and bubbles are mixed in the polyimide precursor solution at that time, and the next coating At that time, it may cause air bubbles to be trapped in the coating film. In this embodiment, the coating speed limit is 760 m.
m / min, and the cylindrical core has a wet film thickness of about 600.
A μm polyimide precursor coating was formed.

The polyimide precursor coating film was subjected to horizontal rotary drying at 100 ° C. for 120 minutes in a drying oven. The polyimide resin film after drying was good without any abnormality. Then, it was heated at 380 ° C. for 20 minutes to be cured. There was no particular abnormality in the polyimide resin film after firing.

After cooling to room temperature, the coating was removed from the cylindrical core body to obtain an endless belt made of polyimide resin having a thickness of 80 μm. Since the mold release agent was applied to the surface of the cylindrical core, the polyimide resin did not adhere to the surface of the cylindrical core.

[Evaluation] The manufactured polyimide resin endless belt of Example 1 was evaluated for unevenness in film thickness and cissing based on the following criteria. The evaluation results are shown in Table 1. In addition, in Table 1, the solution temperature and the solution viscosity in the heated state of the polyimide precursor solution are also shown.

(Criteria for determination of film thickness unevenness) ◯: 10 μm or less Δ: Over 10 μm and 20 μm or less ×: Over 20 μm (repelling criterion) ○: Good as an endless belt without any problems △: Some defects, but usable as endless belt ×: Not usable as endless belt

[0064]

[Table 1]

(Example 2) A polyimide resin endless belt was produced in the same manner as in Example 1 except that the high-viscosity polyimide precursor solution was heated to 40 ° C. And evaluated. The evaluation results are shown in Table 1.
Also described in. The solution viscosity in the heated state is 63 Pa
・ It was s. The coating speed limit was 630 mm / min. There was no particular abnormality in the polyimide resin film after drying and baking.

Comparative Example 1 A polyimide resin was prepared in the same manner as in Example 1 except that the high-viscosity polyimide precursor solution was used while being kept at room temperature of 22 ° C. without heating. An endless belt was manufactured and evaluated. The evaluation results are also shown in Table 1. The solution viscosity at this time was 132 Pa · s. Coating speed limit is 300 mm
/ Min, and the film thickness on the upper part of the cylindrical core was slightly reduced after drying. This is because the coating speed was slow, and liquid dripping occurred on the upper part of the cylindrical core body where the standing time after coating was long.

Comparative Example 2 In Example 1, as the polyimide precursor solution, a low-viscosity polyimide precursor solution (trade name: U Varnish S, low-viscosity type, Ube Industries)
And a high-viscosity polyimide precursor solution used in Example 1 were mixed and stirred at a ratio of 2: 1 and used at room temperature of 22 ° C. without heating. In the same manner as in Example 1, a polyimide resin endless belt was manufactured and evaluated. The evaluation results are also shown in Table 1. The solution viscosity at this time (room temperature 22 ° C) is 19 Pa · s.
Met. Although the coating speed limit was 1200 mm / min, some film thickness unevenness and cissing occurred after drying. This is because the viscosity of the solution was too low, and the release agent on the surface of the cylindrical core made the coating liquid easily move during drying.

(Example 3) [Production of endless belt made of polyimide resin] Using the same polyimide precursor solution as in Example 1, which was heated to 50 ° C, coating was carried out by a blade coating method as shown in Fig. 4. It was Here, FIG. 4 is a schematic configuration diagram showing an example of an apparatus using the blade coating method. The blade coating method is to put the coating liquid 2 (heated polyimide precursor solution) in a pressure tank 11 equipped with a heating device and pressurize the coating liquid 2 so that a fixed amount of the coating liquid 2 is dropped to the nozzle 12 Is a coating method in which the coating film on the cylindrical core 1 which is rotating while moving at a constant speed in the horizontal direction is smoothed by the blade 13 to form a coating film in a spiral shape. As the coating conditions, the pressure to the pressure tank 11 was 0.4 MPa, and the rotation speed of the cylindrical core was 120 rpm. As a result, in order to achieve good film formation, the nozzle 12 corresponding to the coating speed is used.
The horizontal moving speed of was 180 mm / min.

Comparative Example 3 A polyimide resin was prepared in the same manner as in Example 3 except that the high-viscosity polyimide precursor solution was used while being kept at room temperature of 22 ° C. without heating. An endless belt was manufactured. As a result, the dropping of the coating liquid from the nozzle 12 becomes extremely slow,
The horizontal movement speed of the nozzle 12 corresponding to the coating speed is 20 m
It was m / min.

[0070]

As described above, according to the present invention,
A method for producing an endless belt made of a polyimide resin using an aprotic polar solvent, wherein a polyimide precursor having a high degree of polymerization, and an aprotic polar solvent, while using a polyimide precursor solution consisting of a polyimide precursor It is possible to provide a method for manufacturing a polyimide resin endless belt that enables a reduction in coating time. 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 and has no film thickness unevenness and high tensile strength.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of an apparatus used in a push-up 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 shows the shape of the wall surface of the hole provided in the annular body, where (a) is a linear wall surface, (b) is a curved wall surface,
(C) is a schematic sectional drawing which shows a polygonal wall surface.

FIG. 4 is a schematic configuration diagram showing an example of an apparatus using a blade coating method.

[Explanation of symbols]

1 Cylindrical core 2 Polyimide precursor solution 3 coating tanks 4 Polyimide precursor coating 5 ring 6 Annular hole 7 Inclined linear annular inner wall 8 curved inner wall 9 Line-shaped annular inner wall 11 Pressurized tank 12 nozzles 13 blades

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 15/20 101 G03G 15/20 101 4J038 21/00 350 21/00 350 // B29K 79:00 B29K 79 : 00 B29L 29:00 B29L 29:00 F term (reference) 2H033 AA31 BA07 BE03 2H035 CA05 CB06 2H071 BA42 DA06 DA09 DA12 2H200 FA13 HA28 HB13 HB45 HB47 JB07 JB45 JB47 JC04 JC15 JC17 MA04 MA20 A40A40A40A40A40A40A40A40A40A40A40A40A40A40A40A40A40A20 AR06 AR17 AR20 GA07 GB01 GC01 GE06 GE10 GF03 GF24 4J038 DJ021 DJ031 NA11

Claims (6)

[Claims] 1. A step of applying a heated polyimide precursor solution to a surface of a cylindrical core to form a polyimide precursor coating film, and heating the polyimide precursor coating film to form a polyimide resin film. The method for producing an endless belt made of a polyimide resin, comprising: 2. The method for producing an endless belt made of a polyimide resin according to claim 1, wherein the polyimide precursor solution in a heated state is a solution adjusted to a range of room temperature to 50 ° C. 3. The method for producing an endless belt made of a polyimide resin according to claim 1 or 2, wherein the solution viscosity of the polyimide precursor solution is 20 to 100 Pa · s. 4. The mass average molecular weight of the polyimide precursor in the polyimide precursor solution is 40,000 to 200,
It is 000, The manufacturing method of the endless belt made from a polyimide resin in any one of Claims 1-3 characterized by the above-mentioned. 5. A polyimide resin endless belt manufactured by the method for manufacturing a polyimide resin endless belt according to claim 1. 6. The endless belt made of a polyimide resin according to claim 5, which has a tensile strength of 200 MPa or more.