JPH11309729A - Production of tubular article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an ultra-thin film seamless tubular article in which the inner layer of uniform thickness, circumferential length, and circumferential length difference is made to be of a polyimide layer, and the outer layer is made to be of a fluororesin layer. SOLUTION: A coat with a prescribed thickness prepared from the solution of a polyimide precursor is formed on the outer surface of a core body, and the precursor solution is heat-treated to a state in which at least strength as a tubular article can be kept to form an inner layer. Next, the outside of the inner layer is coated with a fluororesin and heat-treated to form an outer layer of the fluororesin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heat-resistant resin such as polyimide, polyamideimide, aromatic polyester, polyether sulfone, polyesterimide, thermosetting butadiene, polybenzimidazole, bismaleimide triazine resin and a precursor solution. The present invention relates to a method for producing a tubular article.

[0002]

2. Description of the Related Art The above-mentioned heat-resistant resins are molded into many shapes and used due to their excellent physical and chemical properties. In particular, in the most advanced technological fields such as the aerospace industry and electronic equipment, which are making remarkable progress, their excellent heat resistance, mechanical strength, dimensional stability, and chemical stability have come to be applied to many fields. Was.

However, on the other hand, a high heat treatment or the like for a long time is required for imidization and curing reaction, and a simple heat treatment does not cause re-melting and hardening. It is difficult, for example, to perform processing that makes full use of the characteristics of the resin. That is, at present, it is very difficult to establish a molding technique.

[0004] Conventionally, many thin-film seamless tubular articles have been developed, such as plastic polymer material tubes and rubber tubes, and their uses are very diverse.

However, as a method for producing these tubes, that is, tubular articles, extrusion molding (injection), extrusion blow molding (inflation) and the like are mainly used, and thin films, particularly several μm to several tens μm, are uniformly formed. It is very difficult to produce a seamless tubular article having a film thickness. Still, recently, in order to somehow produce a thin tubular material, after extruding inflation to reduce the film thickness,
Methods of stretching in the longitudinal direction or passing between pressure rolls to reduce the thickness have been attempted, but uneven thickness and partial thickness differences occur, and it is not possible to obtain a uniform thin film tubular article. It was possible. In addition, as a method for producing a tubular material using a polyimide resin, for example, after corona discharge treatment of the tetrafluoroethylene-hexafluoropropylene copolymer film surface,
The polyimide film is heat-laminated, the tape of the two-layer structure is wound around a core bar with a fixed wrap width, and the wrap portion is heat-welded with an ethylene tetrafluoride-propylene hexafluoride copolymer, There is a method of extracting a core metal and forming a tubular object.

However, the tubular articles produced by these methods cannot be used in a temperature range exceeding the heat resistance of ethylene tetrafluoride-propylene hexafluoride copolymer, and take advantage of the excellent heat resistance of polyimide. Not only is it not cut, but also a helical wrap remains on the structure, and it is difficult to obtain a tubular article having a uniform thickness.

An example of a method for obtaining a polyimide tube having a uniform thickness is disclosed in Japanese Patent Application Laid-Open No. 1-156017 (International Patent Classification B29C 41/12). In this method, after pouring a polyimide precursor liquid into the inner surface of a molded tube such as a glass tube or a stainless steel tube having a smooth inner surface, the molded tube is held vertically, and a running body such as a bullet-shaped body is placed on the inner surface. It is dropped by its own weight to form a certain thickness. Then, it is dried and imidized by heating, and is withdrawn from the molded tube as a tubular material.

However, in this method, when the viscosity of the polyimide precursor liquid is high, the polyimide precursor liquid accumulates downward, causing a variation in the falling speed of the bullet-shaped traveling body, resulting in an uneven film thickness. In addition, there is a problem that the outer diameter of the tubular article can be limited, and a small one cannot be manufactured.
In addition, this method is inferior in mass productivity even though it can be produced experimentally, and it is also difficult to carry out subsequent processes such as drying, curing, and firing.

Further, it has been studied whether a thin film can be obtained by utilizing a method of producing a thin film, that is, a so-called casting method. As a casting method, a coating material to be formed and a precursor material of the coating material are liquefied, and a core is dipped into the liquid and then pulled up, or a coating material precursor is applied to the surface of the core. Many methods such as a method of spraying a liquid material or a powder or the like have been considered and examined, but all have a limit on the viscosity of the liquefied substance of the precursor material of the coating material, and the viscosity is high. In other words, it was impossible to make the film thickness thin and uniform even if it was applied to the core by any method. Of course, even if the coating applied to the core is dried, cured, and reacted in this way, the coating is pulled out from the core and separated to obtain a uniform tubular product. In order to apply a more viscous coating material evenly, apply the coating material to the core, create a die-shaped outer mold with some space from the core, pass it through, Can be considered. However, in order to form a uniform thin film on the outside of the core, it is very important to take parallelism between the core and the outer die, but it is difficult to take the parallelism. When it becomes a slightly long tube,
It was impossible to control the thickness of the tubular object to be formed within ± 10%, or even ± 5% or less, of the thickness of the tubular object for forming the degree of parallelism and eccentricity between the core and the outer die. if,
When it becomes possible to manufacture seamless tubular articles using such heat-resistant materials, conveyor belts for high-performance precision machines, copiers,
It can be used for functional materials of precision equipment such as image processing films such as laser printers. Further, when used in such applications, the surface state of the inner and outer layers of the seamless tubular article, that is, the outer layer surface is as smooth as possible,
The surface of the inner layer is required to change the surface condition at will.

[0010]

As described above, as described above, polyimides, polyamide imides, aromatic polyesters, polyether sulfones, polyester imides, polybenzimidazoles, thermosetting butadiene, and bismaleimide triazine resins have heat resistant temperatures. It is very difficult to uniformly produce a thin-film seamless tubular article using a resin having a high melting point and a very high melting point even with a thermosetting or thermoplastic resin.

Since it is difficult for such a heat-resistant resin to be melted by heat and deformed in a molten state or formed into a thin film,
Intermediates (polyamic acids) produced by the reaction of aromatic tetracarboxylic anhydrides that are precursors of these heat-resistant resins, intermediates composed of pyromellitic anhydride and aromatic diamines, polyesterimide intermediates, Ether sulfone intermediate, aromatic diamine ester resin intermediate, bismaleimide triazine resin intermediate, polybenzo-imidazole intermediate, thermosetting butadiene intermediate, etc.
A method is considered in which an intermediate or precursor before drying, curing, or reaction is formed into a gel or varnish using a solvent or the like.

However, these gel-like and varnish-like intermediates generally show high viscosity and maintain a state like an adhesive, so that they are extremely difficult to mold and process, and furthermore, a uniform thin film is formed. It was impossible to do so.

The present invention completely solves these difficulties,
Moreover, it is an object of the present invention to provide a technology that can reasonably cope with mass production.

Further, the present invention provides an extremely thin seamless tubular article having a uniform thickness, a circumferential length, and a circumferential length difference of 3 to 300 μm, and the outer surface of the tubular article is in contact with an air layer. The purpose is to produce a tubular article that shows the surface condition and the inner surface is an artificial surface, that is, the surface condition of the core body surface.

[0015]

Means for Solving the Problems The present inventors have conducted various studies as a method of forming a coating on the surface of a core with high precision. As a result, the precursor of a tubular molded product was previously formed on the surface of the core. After attaching the bodily fluid thicker than the final film formation thickness, without restraining both or at least one of the outer mold and the core, using the repulsive force of the tubular molded product precursor liquid,
After passing the outer mold outside the core to form a coating of a predetermined thickness on the outer surface of the core, the tubular molded product precursor liquid is dried, cured, extracted, and baked by means of at least a tubular material. After holding the tubular material coating material on the core until the strength can be maintained, the tubular material is separated from the core and 3 μm to 300 μm.
A thin film with a thickness in the range of μm, uniform thickness accuracy, and a tubular object whose outer surface is in contact with the air layer and whose inner surface is in contact with the core surface has been found. Was.

That is, as a method of uniformly applying the tubular molded product precursor solution to the core, first, the core material is dipped in the tubular molded product precursor solution and pulled up, or the precursor solution is brush-coated, flow-coated, or the like. After applying thicker than the gap between the core and the prepared outer die using a typical coating method,
The outer die, the outer die and / or the core are not restrained, that is, the outer die is passed through the core and dropped by the weight of the outer die, or the outer die is fixed or flexible. By fixing the outer die and pulling it up with the core moving freely (such as hanging the core with a thread), the distance between the core and the outer die is automatically adjusted. Then, a tubular molded product precursor liquid coating was uniformly formed. Further, in order to make the film thickness of the tubular molded product precursor liquid uniform (there is some thickness variation before and after in the longitudinal direction), the core body pulling speed or the outer die lowering speed is determined by adjusting the tubular molded product precursor liquid. Is greatly related to the viscosity of the film, and the film forming speed is 2 mm / sec to 210 mm / s.
ec was found to be optimal. That is, the optimum condition is that the outside of the core body is allowed to pass through the outer die as an outer die by natural fall, and the natural fall speed depends on the viscosity of the tubular molded product precursor liquid and the weight balance of the outer die.
It has been found that it is optimal to adjust so as to be in the range of mm / sec to 210 mm / sec.

[0017]

As described above, after uniformly applying the tubular molded product precursor liquid to the core, the tubular molded product precursor liquid is heated,
Using natural drying, heat curing, solvent extraction, etc., at least, after holding the core to a state that can maintain the strength as a tubular body, by separating the tubular body from the core, film thickness, perimeter, An ultra-thin tubular article with a uniform circumferential difference was obtained.

[0018] The method of the present invention can be applied to ultra-thin films,
It has been found that it is suitable for obtaining a tubular article having a thickness of about 500 μm, and is suitable for molding using a high-viscosity liquid having a viscosity of a tubular molded article precursor liquid of about 50 to 10,000 poise. The present invention also includes a method of so-called compounding, in which the surface of the tubular article thus obtained is treated with another material in an intermediate step.

[0019]

Embodiments of the present invention will be described below.

The heat resistance is high, such as polyimide, polyamide imide, aromatic polyester, polyether sulfone, polyester imide, polybenzimidazole, thermosetting butadiene and bismaleimide triazine resin, and even thermosetting or thermoplastic resin is very high. It is very difficult to uniformly produce a thin-film seamless tubular material with a resin having a high melting point. Since such heat-resistant resins are difficult to be melted by heat and deformed or formed into a thin film in a molten state, in the present invention, the reaction of the aromatic tetracarboxylic anhydride which is a precursor of these heat-resistant resins is performed. (Polyamic acid), intermediate composed of pyromellitic anhydride and aromatic diamine, polyesterimide intermediate, polyether sulfone intermediate, aromatic diamine ester resin intermediate, bismaleimide triazine resin Intermediates, polybenzo-imidazole intermediates, thermosetting butadiene intermediates, and other intermediates and precursors before drying, curing, and reaction are molded into a gel or varnish using a solvent or the like. .

First, a metal material, for example, stainless steel, aluminum, or iron, which has been subjected to surface plating, or a core material such as a glass pipe or a rod, is prepared, and then the surface is coated on the inner surface of the coated tubular article. Finish to the required shape using means such as cutting and molding.

Next, a material to be a release material is applied to the surface of the material as the core material, if necessary. For example, if it is necessary to apply a release material, it is desirable to apply a material that reaches the required temperature when the tubular material is separated from the core, such as silicon treatment or fluoro resin treatment.

The core thus prepared is immersed in a precursor solution for a tubular material coating material, for example, a polyimide (hereinafter, the tubular material coating material is exemplified by polyimide) precursor solution, pulled up, and pulled up. A polyimide precursor solution is deposited around the body. Of course, in this case, the polyimide precursor is in a state of irregularly adhering to the core. As a method of attaching the polyimide precursor to the core body, various methods such as a method of pouring the precursor solution, a brush application, and the like can be used.

Next, from the upper part of the core, an outer ring prepared in advance with a necessary interval for the thickness of the tubular material coating is inserted and dropped by its own weight. The outer mold descends along the core.
At that time, the lowering speed of the outer mold is determined by the viscosity of the polyimide precursor liquid and the weight of the outer mold.

The speed at which the outer mold descends is an important factor in forming a uniform tubular coating. That is, for example, if the viscosity of the coating material is high, the distance between the outer ring and the core is small, and the weight of the outer ring is light, the speed at which the outer ring descends outside the core is extremely high. To be late,
The outer ring is wavy and descends, causing unevenness in the thickness of the tubular film. Conversely, if the viscosity of the coating material is low, or if the distance between the outer ring and the core required for the tubular object is extremely wide, the outer ring falls with almost no resistance. Thickness is uneven, and a tubular coating having a uniform thickness cannot be obtained.

That is, according to the present invention, in order to obtain a uniform tubular material coating, the viscosity of the coating material, the distance between the outer mold and the core,
That is, depending on the thickness of the coating of the tubular material, the diameter of the outer core, the weight of the outer die, the shape of the outer die, and many factors, the speed at which the outer die passes through the core is 2 mm / sec to 210 mm / sec.
It was found that a uniform tubular coating could be obtained if it was in between. In other words, the outer die is fixed or has a flexible fixing so that the speed at which the outer die passes through the core is 2 mm / sec to 210 mm / sec, and the core is pulled up with a degree of freedom. For example, the present invention can be applied to a case where the core is hung with a string, a thread, or the like, or when the core is very thin and slightly deformed (for example, a wire). Of course, it is also possible to adopt a method in which the outer mold is fixed or flexible, the core body is dropped, and the core body passes inside the outer mold.

Naturally, the viscosity of the heat-resistant resin precursor used for the tubular material coating material is also limited, and it is desirable to use a high-viscosity liquid having a viscosity of 50 to 10,000 poise. In other words, for a viscosity liquid of 50 poise or less, the passing speed of the outer ring outside the core body is 2 mm /
It is very difficult to maintain the temperature for more than sec, and if it is 10,000 poise or more, it becomes difficult to apply the present invention.

As a result of the experiment based on the present invention, the relationship between the final product film thickness of the tubular article obtained and the speed of passage through the outer die and the core, the relationship between the viscosity of the tubular article coating precursor liquid, and the core Tables 1, 2, and 3 show examples of the results of measurements of the relationship between the diameter, the outer die, and the passing speed of the core, respectively.

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

[Table 3]

Next, after the tubular coating material precursor is formed on the surface of the core body in this manner, it is subjected to drying (natural drying, heat drying, etc.), curing, reaction, extraction, etc. The tubular material coating material is held on the core until the strength can be maintained. For example, when the coating material is polyimide, heat drying at 120 ° C to 200 ° C is performed,
By removing the solvent contained in the polyimide precursor liquid, a state in which the strength as a tubular object can be maintained.
In this state, or after the imidization reaction is advanced by a method such as heating or the like, or completely imidization reaction is performed, the thin film tubular article is forcibly separated from the core body.
Of course, the thin-film tubular article thus obtained has a surface state in which the outer surface is in contact with the air layer, and the inner face of the tubular article shows the same shape as the outer shape of the core. Therefore, by giving the core body a special surface condition, it is possible to form the inner shape of the tubular object as it is.

Although polyimide has been mainly described, a study on a precursor of polybenzimidazole and the like also revealed that a uniform tubular product could be similarly obtained.

[0034]

EXAMPLES Next, specific examples and comparative examples will be described.
The present embodiment does not limit the contents of the present invention.

REFERENCE EXAMPLE 1 The surface of a stainless steel rod having an outer mold diameter of 40 mm and a length of 1000 mm was made into a surface, and a silicon solution was diluted as a mold release agent on the surface of the core body which had been processed into a ground shape. Core.

Next, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride adjusted to a viscosity of 1000 poise was reacted with an aromatic diamine in N-methyl-2-pyrrolidone. 8 in the polyimide precursor solution
It was immersed to 00 mm. Next, an aluminum ring-shaped outer die having an inner diameter of 40.5 mm, a weight of 665 g, a liquid contacting part angle of 45 °, and a land length of 3 mm was prepared, and was naturally dropped from the upper portion of the vertically placed core body. The outer mold dropped at a very high speed at the beginning when passing through the part where the polyimide precursor was applied, but immediately fell down at a rather slow speed, which was immediately regulated by the viscosity resistance of the polyimide precursor. did. When the descending speed of the outer mold was measured, it was 7.2 mm.
It was found that the vehicle was descending at a speed of / sec. When the outer ring is lowered and reaches the lowest point of the core, the outer ring is removed from the core, and the core is left in a drying oven at 120 ° C. for 30 minutes. The drying temperature was increased and the mixture was left for another 20 minutes. Subsequently, the temperature of the drying furnace was set to 300 ° C., left for 60 minutes, then set to 350 ° C., left for 60 minutes, and subjected to an imidization reaction.
Remove it from the drying oven. Thereafter, the core body and the tubular film formed on the core body were cooled by air cooling. Then, after confirming that the coating of the tubular material did not flow down or was not sticky when touched by hand, the tubular material was carefully removed from the core and separated. The thus obtained tubular article had a completely uniform thickness and a circumferential length except for the upper and lower ends of 3 cm. When this tubular object was measured in more detail, the film thickness was 22 μm ± 1 μm, the perimeter was 40 mmφ ± 2%, and the perimeter difference was 1% when measured as upper, middle, and lower.
It had a complete walled uniform thin-film tubular product within.

Further, the tubular material was cut open to view the inner surface, and the inner surface shape was charted by a surface roughness meter. It was completely equivalent, and the outer surface had a shape in contact with natural air having an Rz of 1 μm or less.

REFERENCE COMPARATIVE EXAMPLE 1 Under the conditions of Reference Example 1, the gap between the outer diameter of the core and the inner diameter of the ring-shaped outer die was positioned and fixed as accurately as possible at the top of the core, and then the polyimide precursor was fixed. After the core is immersed in the body solution tank to a predetermined position and the polyimide precursor solution is attached to the surface of the core, the core and the polyimide precursor solution are separated and the gap between the ring-shaped outer mold is held precisely. The polyimide precursor solution coating was formed with a thickness of 500 μm on the surface of the core body by mechanically traveling at a speed of 20 mm / sec while the ring-shaped outer die was removed from the core body.

Thereafter, a heat-reaction was conducted under the same conditions as in Reference Example 1 to obtain a completely imidized polyimide tube.

The average value of the film thickness of this tubular article was 42
μm, and the difference between the maximum and minimum thickness was 16 μm. In addition, even in the result of producing a tubular article by repeating the method several times by this method, there were variations in data every time, and reproducibility was not obtained. In addition, unnatural irregularities are generated in a thin portion of the tubular film, and it is impossible to satisfy the characteristics as a tubular material.

REFERENCE COMPARATIVE EXAMPLE 2 A polyimide precursor solution was adhered to the outer surface of the core body in the same manner as in Reference Example 1 except that the weight of the aluminum ring-shaped outer mold was changed to 2025 g. After that, the inner diameter 40.
When the outer mold is placed on the polyimide precursor solution at the upper part of the core, the outer mold cannot be balanced by the repulsion of the polyimide precursor solution, and the outer mold inner diameter and However, it fell at a rapid speed without keeping the gap with the outer diameter of the core body, and it was impossible to obtain a tubular article with high thickness accuracy.

Reference Comparative Example 3 A cylindrical stainless steel rod 1 m in diameter and 19.5 mm in diameter and 3 cm in length was prepared with a cylindrical stainless steel pipe of 40 mm in outer diameter and 20 mm in inner diameter. Shape. After the silicone diluent used in Reference Example 1 was applied to the inside of the cylinder without the cylinder, the polyimide precursor used in Reference Example 1 was sprayed into a pipe, a conical rod was put therein, and allowed to fall naturally. The rod reached the bottom of the pipe. When the weight of the rod was measured, it was determined to be too light because it was about 75 g. Then, the length of the rod was set to 24 cm and about 600 g, and it was seen through the inside of the pipe. The coating on the inner surface could not be formed.

REFERENCE EXAMPLE 2 Using exactly the same outer mold and core material as in Reference Example 1 and using the same precursor solution, a string is formed at the center of the upper end of the core body, and the outer die is fixed. After passing through the upper part of the core material to which the precursor liquid was attached, the string attached to the core material was pulled up at a constant speed so that the core body passed through the inner surface of the outer mold. Of course, the core had a degree of freedom, and the parallelism was controlled by the precursor liquid. After adjusting the pulling speed of the core to 7.2 mm / sec of Reference Example 1, the same post-treatment as in Reference Example 1 was performed. Was completed.

REFERENCE COMPARATIVE EXAMPLE 4 In the same manner as in Reference Example 1, when the viscosity of the polyimide precursor was raised to 20,000 poise, the outer ring did not drop at all and no tubular product was obtained.

Reference Comparative Example 5 In the same manner as Reference Comparative Example 2, only the weight of the outer ring was reduced to 50
I tried it down to 00g. The descent speed of the outer ring was 217 mm / sec, but the descent state of the outer ring was unstable, and a clean film could not be formed.

Reference Example 3 Outer die 10 mm, glass rod 2 m long, and inner diameter 1
An outer ring of 0.8 mm and weighing 500 g was prepared. Further, a bismaleimide triazine resin precursor, bismaleide, a cyanate ester liquid, and a liquid having a viscosity of 500 poise were applied to a glass rod as a tubular coating material.
After that, the glass was naturally dropped through the outer ring, and the glass rod passing speed of the outer ring was 198 mm / sec. Thereafter, heat curing was performed at 300 ° C. for 3 hours to obtain a tubular material coated body on a glass rod.

Further, the glass rod and the tubular coating were separated, and the upper and lower ends of 50 mm were removed to obtain a bismaleimide triazine resin tubular article of about 1.8 m. When its dimensions were measured, it was a very uniform seamless tubular article with an inner diameter of 10 mm and a film thickness of 53 μm ± 2%. Furthermore, when the surface conditions of the outer surface and the inner surface were measured, the glass rod was used for the core body, so that the outer surface was very smooth.
1 μm or less, and the inner surface was 1.5 μm or less.

Example 1 A surface of an aluminum core having an outer diameter of 180 mm and a length of 500 mm was subjected to sandblasting, and then coated with a polytetrafluoroethylene resin to obtain a core. The surface roughness of the core body is Rz 3.0 μm. Next, wires were attached to the upper three places of this core so that it could be suspended in the air.

3.3 ', 4.4'- having a viscosity of 100 poise
A polyimide precursor solution is prepared by reacting biphenyltetracarboxylic dianhydride and an aromatic diamine in N-methyl-2-virolidone, and the polyimide precursor solution is coated with a core having a thickness of about 430 mm and a thickness of about 430 mm. Brush painting was performed so as to be 1 mm or more. Thereafter, an aluminum ring-shaped outer die having an inner diameter of 181 mm, a weight of 1050 g, and a liquid contact part angle of 30 ° was passed through the upper part of the core body, and was placed on the polyimide precursor solution. At the same time, the core body was lifted with three wires. This outer mold once passed the outside of the core by its own weight only after the outer mold was once balanced by the repulsive force of the polyimide precursor solution. In this case, there was no place where the core and the outer mold were fixed at all, and the film was formed while being adjusted freely, and a 0.5 mm-thick polyimide precursor solution was formed on the surface of the core.

The average falling speed of the ring-shaped outer die passing through the surface of the core was 10.0 mm / sec.

Thereafter, the core coated with the polyimide precursor solution was heated at 150 ° C. for 80 minutes and at 230 ° C.
After heating at a temperature of 30 minutes respectively, and performing an imidization reaction and cooling, the core and the polyimide tubular material were separated, and the inner diameter was 180 m.
m, a tubular article having a length of 300 mm was obtained.

After that, this tubular object was again re-formed with an outer diameter of 180 m.
m of stainless steel core, and further, ethylene tetrafluoride and a mixed solution of gold copolymer were coated on the surface of the tubular material and dried. After that, at a temperature of 300 ° C. for 40 minutes and 400
Each of them was heated at a temperature of 50 ° C. for 50 minutes, then cooled to room temperature, and the tube was removed from the core to obtain a tube obtained by applying a fluoro resin to the surface of completely imidized polyimide.
The thickness of this tubular article was 45 μm, and the thickness variation was ± 2.3 μm.

The length of the tubular object falling within the range of the thickness of the variation was 380 mm.

The outer surface roughness of this tubular article, Rz 0.2
μm, and the inner surface roughness was Rz 2.8 to 3.0 μm.

When the thus obtained tubular article was used as a film for image processing in a copying machine, it showed very high performance.

[0056]

As described above, according to the present invention, a tubular molded product precursor solution is uniformly applied to a core body, and then the tubular molded product precursor solution is heated, naturally dried, heat-cured, and a solvent extraction method. At least, by holding the core to a state where the strength as a tubular object can be maintained, by separating the tubular material from the core, the film thickness, perimeter, difference in perimeter uniform, ultra-thin film A tubular object can be obtained.

Claims (6)

[Claims] 1. A method for producing a tubular article having an inner layer made of polyimide and an outer layer made of a fluororesin, comprising: forming a film made of a polyimide precursor solution on an outer surface of a core to a predetermined thickness; A tubular article having a step of heat-treating the precursor liquid to a state where the strength of the article can be maintained, and a step of applying a fluororesin to the outside of the inner layer and heat-treating to form an outer layer made of the fluororesin. Manufacturing method. 2. A core body and an outer mold having an inner diameter of a predetermined gap with respect to the outer diameter of the core body are prepared, and a polyimide precursor solution is previously adhered to the surface of the core body so as to be thicker than a final coating film forming thickness. After that, by passing the outer die outside the core without restraining at least one of the outer die or the core, a coating made of a polyimide precursor liquid is formed on the outer surface of the core with a predetermined thickness. A method for producing a tubular article according to claim 1. 3. The method for producing a tubular article according to claim 2, wherein a speed at which the outer mold passes outside the core body is 2 mm / sec or more and 210 mm / sec or less. 4. The polyimide precursor liquid has a viscosity of 50%.
The method for producing a tubular article according to claim 1, wherein the pressure is from 1 to 10,000 poise. 5. The finally obtained tubular article has a thickness of 3 to 3
The method for producing a tubular article according to claim 1, wherein the thickness is 00 µm. 6. The method for producing a tubular article according to claim 1, wherein the tubular article is a film for copier image processing.