JP2912922B2 - Manufacturing method for tubular objects - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a tubular article made of polyimide or a polyimide precursor solution resin.

(Prior art) Polyimide resin has excellent heat resistance, dimensional stability, mechanical properties, and chemical properties, and its uses are based on its respective properties. Flexible, printed circuit boards, heat-resistant wire coating materials, magnetic materials It is used for various applications such as tape.
Commercially available polyimide film, for example, a polyamic acid is made from an acid anhydride such as biphenyltetracarboxylic dianhydride and a diamine, and then made into a film by a method such as casting at this stage, and then into a polyimide by dehydration cyclization. The method has been taken.

In addition, for example, as a method for producing a tubular article made of polyimide or a polyimide precursor solution, a surface of a tetrafluoroethylene-hexafluoroethylene copolymer film is subjected to corona discharge treatment, and then thermally laminated with a polyimide film to form a two-layer structure. The body tape is wrapped around the core with a fixed wrap width, heated again to the melting temperature of the ethylene tetrafluoride-hexafluoroethylene copolymer, and the wrap around the core is rolled over the ethylene tetrafluoride-6 There is a method of adhering with a fluorinated propylene copolymer and extracting a core metal to form a tubular material.

In addition, as a method for producing a tubular product from a polyimide precursor, a polyamic acid solution is poured into the inner surface of a molded tube such as a glass tube or a stainless steel tube having a smooth inner surface to form the tube to a constant thickness. A method is also known in which the film is dried and imidized by heating to form a film, and then the film is extracted from a molded tube.

Further, as disclosed in JP-A-64-22514, a polyimide precursor having a viscosity of 3000 poise is uniformly applied to the outer surface of the heat-shrinkable tube, and then imidized by heating to obtain a polyimide tube. After that, there is also a method in which the heat-shrinkable tube is heated and shrunk to reduce its outer diameter, and then the polyimide tube is removed.

(Problems to be Solved by the Invention) However, the tubular article produced by the above-described first method cannot be used in a temperature range exceeding the heat resistance of the ethylene tetrafluoride-hexafluoroethylene copolymer. Not only is the excellent heat resistance of the polyimide not fully utilized, but also due to its structure, a spiral wrap portion remains, and the tubular article is composed of thick and thin portions.

Further, the tubular article manufactured by the second method is composed of a single polyimide resin, but it is very difficult to extract the polyimide tubular article from the inner surface of a molded pipe such as a glass or stainless steel pipe. In addition, it is difficult to produce a tubular article having a small outer diameter because the polyimide tubular article is taken out from the inner surface of the molded tube, and it must be said that producing a long article is also very difficult.

Further, the polyimide tubular article manufactured by the third method is a tubular article obtained from a polyimide resin alone as in the above-described second method. However, the heat-shrinkable tube for applying the polyimide precursor to the outer surface must be insoluble in N-methyl-2-pyrrolidone contained in the polyimide precursor at the reaction temperature for imidization of the polyimide precursor. Then, a heat-shrinkable tube made of a fluorine resin must be used. In addition, the same quantity of the heat-shrinkable tube made of fluororesin is consumed for manufacturing the polyimide tubular article, which is very expensive.

Further, since the processing temperature of the fluororesin heat-shrinkable tube is high, the uneven thickness and the fluctuation rate of the outer diameter are large, and the performance variation of the heat-shrinkable tube directly adversely affects the polyimide tube.

Further, since the contact angle of the surface of the heat-shrinkable tube made of fluorinated resin is very large, when a polyamic acid solution having a low viscosity is easily applied to the outer surface of the heat-shrinkable tube made of fluorinated resin and the solution is easily repelled, the solution becomes a layer of the fluorinated resin tube. In this case, the coating may be frayed, resulting in uneven coating and pinholes.

The present invention solves the above-mentioned conventional problems, and provides a method for producing a tubular article using a polyimide or polyimide precursor solution that can be easily produced and reduced in cost.

(Means for Solving the Problems) The inventors of the present invention have conducted various studies on the problems of the prior art and the problems of the polyimide resin during processing. The present invention has invented a method for producing a new polyimide tubular article using a release resin or a core or cylinder coated with a release resin for the core or cylinder. That is, the present invention relates to a mold or a cylinder to which polyimide or a polyimide precursor solution is applied and which is to be molded, and a mold-releasing resin, for example, polyvinyl fluoride, polyvinylidene fluoride, polyvinyl chloride trifluoride, or polytetrafluoroethylene. Fluorinated ethylene, ethylene tetrafluoride-propylene hexafluoride copolymer, ethylene-tetrafluoroethylene copolymer, ethylene-ethylene trifluoride ethylene copolymer, ethylene tetrafluoride-perfluoroalkyl vinyl ether copolymer Or a resin such as silicon polyimide, polyamide, phenol, polypropylene, epoxy, or the like. A hydroxyl group (-O) such as a hydrophilic resin, for example, polyvinyl alcohol, starch, cellulose, vinyl acetate, etc.
H), carboxyl group (-COOH), a amino group (-NH _2),
A coating film made of a resin containing a polar group or a dissociation group such as a carbonyl group (> CO) or a sulfone group (-SO ₃ H) is formed, and a tube made of polyimide or a polyimide precursor solution is formed on the outer surface or inner surface thereof. A molding liquid is applied, and the applied polyimide or polyimide precursor is heated at least to a state where the strength can be maintained as a tubular material, and then the tubular material is taken out from the core.

In addition, when imidization has not been completely performed on the taken-out tubular article, it is preferable to put it in a mold again or to further perform imidation by heating in the state of the tubular article.

(Function) By forming a thin coating film having hydrophilicity on the outer surface or inner peripheral surface of a core or a cylinder coated with a release resin or a release resin, polyimide or a polyimide precursor having a low viscosity is formed thereon. Is applied uniformly without repelling the solution.

Then, in the heating step, the polyimide precursor solution is converted into polyimide, and a strong polyimide tubular article is obtained. Thereafter, separation from the core or the cylinder is performed by the release effect of the release resin, and both can be easily separated.

(Example) An example of the manufacturing method of the present invention will be described step by step.
However, the present embodiment does not limit the scope of the present invention.

First, the core used in the present invention is molded or cut out of the above-mentioned releasable resin as it is, subjected to a cutting process, etc., and used after finishing to the inner dimensions of the tubular article, or After applying or applying the resin on the surface of the core material made of metal or heat-resistant resin, it is baked and cured, and a method of providing a coating layer of the releasable resin on the surface of the core material or extruding and press-molding the releasable resin. Various processing methods are conceivable, such as a method of molding on a core material or a method of covering a tube made of a release resin on the core material.

However, in general, it is desirable to mold the releasable resin in some form on the surface of the metal core material in view of the dimensional accuracy of the tubular article itself. Also, when a release resin is molded on the surface of a core material such as a metal, the adhesion between the core material and the release resin is quite important, and only the release layer is peeled off from the core material by heating or floating. Otherwise, the accuracy of the tubular object is not obtained at all.

Further, the cylinder used in the present invention, the mold release resin alone molded as it is, cut out, subjected to cutting, etc.,
The inner peripheral surface is used after finishing it to the processing internal dimensions of the tubular object, or after applying or applying the release resin to the inner peripheral surface of the cylinder made of metal or heat resistant resin, baking and curing,
Various processing methods are conceivable, such as a method of providing a coating layer of a release resin on the surface of the core material.

By the way, when the polyimide or polyimide precursor solution is heated to be imidized and separated from the core material, the larger the contact angle of the releasable resin is, the more suitable it is. The larger the contact angle of the resin, the more difficult it is to apply the polyimide or polyimide precursor solution uniformly to the surface of the release resin, and even if the coating can be applied uniformly, a little heat is applied to perform a little imidization. In this case (when the concentration of the solute is increased by applying heat), the uniformity of the applied liquid is lost, and it is impossible to form a tubular article with high accuracy.

Therefore, in the present invention, a hydrophilic resin, for example, polyvinyl alcohol, starch, cellulose, vinyl acetate, or the like is applied to the surface of the release resin of the core to form a hydrophilic coating film. With this hydrophilic coating film, the polyimide or polyimide precursor solution can be uniformly applied to the surface of the release resin.

Subsequently, a tubular article using polyimide or a polyimide precursor solution is produced using the releasable core or cylinder on which the hydrophilic coating film is formed.

For example, a releasable core or cylinder is immersed in a container containing a polyimide solution or a polyimide precursor solution.

In the case of a core, when the core is pulled up between a drawing ring having an outer diameter and a predetermined gap, a resin film having a predetermined thickness is formed on the core.

On the other hand, in the case of a cylinder, when the cylinder is pulled up between a cannon-shaped body or a spherical body having an inner diameter and a predetermined gap, a resin film having a predetermined thickness is formed on the inner peripheral surface of the cylinder.

As a method of forming the polyimide or polyimide precursor solution on the outer peripheral surface of the core, and on the inner peripheral surface of the cylinder,
It is also possible to mold using a scraper or to mold by an extrusion method.

Then, the core or the cylinder is placed in a heating furnace and heated at a predetermined temperature to reduce the solvent concentration in the polyimide or polyimide precursor solution, thereby maintaining the strength as a tubular object.

In addition, this heating causes some imide conversion of the polyimide or the polyimide precursor solution itself, and the resin is cured. As the solvent in the polyimide or polyimide precursor solution is gradually removed, imidation occurs little by little, and a state is maintained in which the strength of the tubular article is maintained.

Finally, the core body or the cylinder is cooled, and the tubular body separates from the core body or the cylinder due to the release effect of the core body and the cylinder,
A predetermined tubular object is obtained.

Further, since the release layer is still firmly formed on the core or the cylinder, the formation of the tubular article again may be started from the step of forming the hydrophilic coating film.

The tubular material obtained in this manner removes a little of the solvent contained in the tubular material or performs a little imidization, rather than completely imidizing on the core or cylinder, It is desirable to cool at the stage where the strength is maintained and separate it from the core or cylinder. Because, when the imidization of the tubular material is completely performed on the releasable core or cylinder, the polyimide or the polyimide precursor solution increases the adhesion in a completely imidized state, and how the releasable core is Or even the cylinder comes into close contact and cannot be separated.

Further, it is desirable that the tubular material separated in a state where the imidization is slightly started is put into a core or a cylinder again, or only the tubular material is reheated and completely imidized to be used as a tubular material.

 Next, specific examples of the present invention will be described.

(Example 1) A stainless steel core having an outer diameter of 50 mm and a length of 500 mm was coated with polytetrafluoroethylene (hereinafter, referred to as PTFE) resin.
A smooth PTFE resin-coated core was prepared.

Next, a 10% aqueous solution of polyvinyl alcohol is prepared as a hydrophilic coating film material, and the PTFE-coated core is immersed in this solution and dried at a temperature of 100 ° C. for 2 minutes to obtain a hydrophilic film having a thickness of 0.5 to 1 μm. A coating film was formed.

After cooling this core to room temperature,
A polyimide precursor solution of Poise viscosity is applied to the outer surface of the core.
It was applied with a thickness of 210 μm.

This core was heated in an oven at 140 ° C. for 90 minutes to remove the solvent, and subsequently heated at 200 ° C. for 10 minutes to perform imide conversion.

Thereafter, after cooling to room temperature, the core was released from the core to obtain a polyimide tubular article having an inner diameter of 50 mm, a thickness of 100 μm, and a length of 450 mm.

Further, after that, the tubular body was inserted again into the metal core, and the core was put into an oven, and heated at 250 ° C. for 20 minutes and at 400 ° C. for 20 minutes. Then, it was cooled again to obtain a completely imidized tubular material.

In this case, there was no adhesion between the metal core and the tubular object, and the tube could be easily separated.

(Example 2) A core made of ethylene tetrafluoride-perfluoroalkyl vinyl ether (hereinafter referred to as PFA) resin having an outer diameter of 30 mm and a length of 1500 mm is formed. Then, an aqueous solution in which starch-based glue is dissolved in water is prepared as a hydrophilic coating film material, and a core molded with PFA resin is immersed in this solution, dried at room temperature for 60 minutes, and a hydrophilic solution is formed on the outer surface of the resin core. A conductive coating film was formed.

Further, the core was immersed in a polyimide precursor solution having a viscosity of 20 poise, pulled up between the outer diameter of the core and a ring-shaped outer mold having a gap of 200 μm, and the polyimide precursor was applied to the outer surface of the core with a thickness of 210 μm. A body solution was applied.

The core was heated in an oven at 200 ° C. for 15 minutes to remove the solvent.

Further, the core was put again in an oven and heated at 350 ° C. for 60 minutes. Thereafter, the mixture was cooled to obtain a completely imidized tubular material.

In this case, there was no adhesion between the PFA core body and the tubular article, and it could be easily separated, and a polyimide tubular article having an inner diameter of 30 mm, a thickness of 18 μm, and a length of 1400 mm was obtained.

Example 3 An aluminum core having an outer diameter of 90 mm and a length of 1000 mm was coated with PFA to prepare a smooth PFA resin-coated core.

Next, make a cellulose aqueous solution as a hydrophilic coating material,
The PFA-coated core was immersed in the solution and dried at 100 ° C. for 15 minutes to form a hydrophilic coating film having a thickness of 0.5 to 1 μm.

Then, a polyimide precursor solution having a viscosity of 100 poise was applied to the outer diameter of the core with a thickness of 210 μm using a screver.

This core was heated in an oven at 250 ° C. for 10 minutes to remove the solvent, further heated at 120 ° C. for 90 minutes, and then heated at 160 ° C. for 20 minutes to perform imide conversion.

After that, cool down to room temperature, remove from core, 90mm inside diameter
A polyimide tube having a thickness of 20 μm and a length of 900 mm was obtained.

Example 4 An aluminum core having an outer diameter of 200 mm and a length of 1000 mm was coated with PFA to prepare a smooth PFA resin-coated core.

Next, polyvinyl alcohol is used as a hydrophilic coating material.
A 10% aqueous solution was prepared, and the PFA-coated core was immersed in this solution and dried at 100 ° C. for 2 minutes to form a hydrophilic coating film having a thickness of 0.5 to 1 μm.

This core was immersed in a polyimide precursor solution having a viscosity of 100 poise, and the outer surface of the core was uniformly coated with the polyimide precursor solution to a thickness of 200 μm.

The core was heated in an oven at 150 ° C. for 10 minutes to remove the solvent, further heated at 120 ° C. for 90 minutes, and then heated at 160 ° C. for 20 minutes to perform imide conversion.

Then, after cooling to room temperature, the core was released from the core, and the tubular material was heated at 350 ° C. for 1 hour, and the inner diameter was 200 mm and the thickness was 20 mm.
A 900 μm-long polyimide tube was obtained. Its tensile strength was 27 kg / mm ² .

(Example 5) An aluminum core having an outer diameter of 90 mm and a length of 1000 mm was coated with polyvinylidene fluoride (hereinafter referred to as PVdF), and was smoothed.
A PVdF resin-coated core was prepared.

Next, an aqueous vinyl acetate solution was prepared as a hydrophilic coating material, and the core was immersed in this solution.
After drying for a minute, a hydrophilic coating film was formed.

A polyimide precursor solution having a viscosity of 100 poise was applied to the outer surface of the core to a uniform thickness of 210 μm.

This core was heated in an oven at 150 ° C. for 10 minutes to remove the solvent, further heated at 120 ° C. for 90 minutes, and then heated at 160 ° C. for 20 minutes to perform imide conversion.

Then, after cooling to room temperature, the core was released from the core, and the tubular material was heated at 350 ° C. for 1 hour to obtain an inner diameter of 90 mm and a thickness of 20 mm.
A 900 μm-long polyimide tube was obtained.

(Example 6) The inner surface of a stainless steel cylinder having an inner diameter of 50 mm and a length of 500 mm was coated with a PTFE resin to prepare a smooth PTFE resin-coated cylinder.

Next, polyvinyl alcohol is used as a hydrophilic coating material.
Make a 10% aqueous solution, immerse the above PTFE coated cylinder in this solution, dry at 100 ° C for 2 minutes and
To form a hydrophilic coating film having a thickness of

After cooling the cylinder to room temperature, the core was immersed in a polyimide precursor solution having a viscosity of 1000 poise, the space between the cantilevers was pulled up, and a 210 μm-thick polyimide precursor solution was applied to the inner surface of the cylinder. .

This cylinder was heated in an oven at 140 ° C. for 90 minutes to remove the solvent, and further heated at 200 ° C. for 10 minutes to perform imide conversion.

After that, cool to room temperature, remove from the cylinder,
A polyimide tube having a thickness of 50 mm, a thickness of 100 μm, and a length of 450 mm was obtained.

Furthermore, after this, the tubular object is again inserted into the metal cylinder, and the cylinder is put into an oven at 250 ° C for 20 minutes at 400 ° C.
For 20 minutes. Then, after cooling again, a completely imidized tubular material was obtained.

In this case, there was no close contact between the metal cylinder and the tubular object, and the tube could be easily separated.

(Comparative Example 1) The surface of a stainless steel core having an outer diameter of 30 mm and a length of 1500 mm was mirror-finished to a surface roughness of 0.5 μm or less by puff polishing, and a polyimide precursor was applied to the core in the same manner as in Example 2. It was applied to the outer surface of the core with a thickness of 200 μm by the method.

The coated core of the polyimide precursor solution was heated in an oven at 200 ° C. for 15 minutes to remove the solvent, and then heated at 350 ° C. for 60 minutes to perform imide conversion.

Tried to remove the polyimide tube after cooling, the polyimide tube is tightly adhered to the stainless steel core,
It was not possible to remove it from the core while keeping the tubular shape.

(Comparative Example 2) Using the PTFE-coated core used in Example 4, PTFE was directly immersed in a polyvinyl alcohol solution without being immersed.
A polyimide precursor was formed on the coated surface in the same manner as in Example 4.

In this state, the polyimide precursor solution was a PTFE-coated core, and a spot-like repelling phenomenon occurred at a diameter of 1 to 2 mm.

Furthermore, when the polyamide coating mold was placed in an oven at 120 ° C., the repelling phenomenon spread over the whole within several minutes, and a polyimide tubular article could not be obtained.

In the above-described embodiments of the present invention, various polyimide precursor solutions were used as the thermosetting resin. These solutions are described in, for example, Japanese Patent Publication No. 37-97, Japanese Patent Publication No. 60-362, or The production method thereof is known in Japanese Patent Application Laid-Open No. 56-38324 and the like, and is not limited to the material of the tubular article of the present invention.

Further, as the thermosetting resin, an epoxy resin or the like can be used in addition to the polyimide precursor.

In addition, as for the fluorine resin coated on the surface of the metal core, a tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA) or a tetrafluoroethylene-hexafluoroethylene copolymer other than the PTFE resin is used. FEP) or ethylene tetrafluoride copolymer (ETFE) can also be used.

Further, as the releasable resin, in addition to the above-mentioned fluorine resin, silicon or polypropylene resin can be used.

The polyimide tubular article manufactured by the present invention is expected to be used for a very wide range of applications, for example, a conveyor belt requiring dimensional stability or heat resistance, or a tubular film for fixing hot-melt toner such as a copying machine or a laser beam printer. You.

(Effect of the Invention) According to the present invention, a polyimide or a polyimide precursor solution can be uniformly applied without being repelled on the surface by the hydrophilic coating film formed on the surface of the releasable core or the cylinder. Moreover, the surface tension of the polyimide or polyimide precursor solution and the releasable core or the cylinder and the release resin is successfully combined, and furthermore, due to the combination with the imidation rate of the polyimide or polyimide precursor solution, there is no conventional method. Can be molded.

As described above, according to the present invention, a tubular article can be manufactured very easily, and the manufacturing cost can be reduced because the core can be used repeatedly.

Furthermore, the polyimide tubular article obtained by the production method of the present invention had a uniform thickness, and a highly accurate tubular article could be easily obtained.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hitoshi Fujiwara 5-13-13 Ichiriyama, Otsu City, Shiga Prefecture Ai. S. Tuchii (72) Inventor Yoji Tani 5-13-13 Ichiriyama, Otsu City, Shiga Pref. S. (56) References JP-A-3-180309 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 41/00-41/52 B29C 33/00-33/76 B29K 77:00-79:00 B29L 23:00-23:24

Claims (4)

(57) [Claims] 1. A hydrophilic coating film is formed on an outer surface of a core made of a release resin or a core coated with a release resin, and a polyimide or polyimide precursor solution is formed on the hydrophilic coating film. A tubular molding liquid is applied, and the applied polyimide or polyimide precursor solution is heated at least until the strength can be maintained as a tubular object, and then the tubular object is taken out from the core to produce a tubular object. Method. 2. A hydrophilic coating film is formed on the inner peripheral surface of a cylinder made of a release resin or a cylinder coated with a release resin, and a polyimide or polyimide precursor solution is formed on the hydrophilic coating film. A tubular molding liquid is applied, and the applied polyimide or polyimide precursor solution is heated at least until the strength can be maintained as a tubular object, and then the tubular object is taken out from the core to produce a tubular object. Method. 3. The method for producing a tubular article according to claim 1, wherein the thickness of the tubular article is in the range of 5 to 5000 μm. 4. Hydroxyl groups (—O
H), carboxyl group (-COOH), a amino group (-NH _2),
First, a resin containing a polar group such as a carbonyl group (> CO) or a sulfol group (—SO ₃ H) or a dissociation group is used.
Item 4. The method for producing a tubular article according to any one of Items 2, 2 and 3.