JP2002030519A - Method for producing polyimide film/fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a drawn polyimide film and a drawn polyimide fiber having high strength. SOLUTION: A polyisoimide is drawn and then imidated. Preferably the polyisoimide is swollen with a solvent in the drawing and the polyisoimide is formed by introducing a polyamic acid into a solution of a condensation agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an oriented polyimide film and fiber.

[0002]

2. Description of the Related Art Polyimide is widely used industrially because of its excellent heat resistance and mechanical properties. In particular, since a wholly aromatic polyimide has a rigid structure, it is expected to exhibit particularly high heat resistance and mechanical properties. However, such a rigid wholly aromatic polyimide is infusible and insoluble, and it is difficult to mold the polyimide in a state of polyimide. Therefore, molding in a precursor state has been attempted. The main one is to form a fiber or film in the state of polyamic acid or polyamide ester, which consists of the reaction of an amine component and an acid anhydride.However, even in these methods, there are only a few cases where the physical properties of polyimide are improved by orientation. There is only what was done.

[0003] Collection of Polymers, Vol. 65, No 5, pp2
82-290 reports a method in which a polyamic acid solution which is a precursor of polyparaphenylene pyromellitic imide is formed and then dried, and the obtained polyamic acid film is uniaxially stretched in a solvent and then imidized. . The tensile modulus of the obtained film increases with the stretching ratio and reaches 105 GPa, but the tensile strength is 0.2 to
0.3 GPa, which is low and not at a level suitable for practical use.

Further, there is an example in which a polyamide ester is used as a polyimide precursor as a precursor of polyparaphenylenepyromellitimide. For example, Polymer P
reprints, Japan Vol. 41, No.
9 (1992) 3752-2754, a method is proposed in which a precursor polyamide ester obtained by introducing a long-chain (10 to 18 carbon atoms) ester group into a polymer chain is wet-spun, stretch-oriented, and then imidized by heating. Have been. However, the strength of the obtained polyimide fiber is at most 0.46 Gpa, and the improvement of the strength by stretching is limited.

[0005] As another polyimide precursor, there is a report utilizing polyisoimide, which is a structural isomer of imide. For example, Macromoleculus 1992,
25, 4559-4568. However, at present, there is no example of stretching in the state of this polyisoimide, and there is no example of a polyimide film having improved strength obtained by further heat treatment. A stretching technique capable of greatly improving the strength of a rigid wholly aromatic polyimide by such orientation has not been completed yet.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a method for producing a high-strength oriented polyimide film and fiber which cannot be obtained by the prior art.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a method for producing a polyimide film and a fiber, wherein a polyisoimide is drawn and then imidized. The polyisoimide in the present invention is represented by the following formula (I)

[0008]

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(In the formula, R ₁ represents an aliphatic group, a monocyclic aliphatic group, a monocyclic aromatic group, a condensed polycyclic aromatic group, or an aromatic group connected directly or by a crosslinking member. Represents a tetravalent group selected from the group consisting of a non-fused polycyclic aromatic group, and R ₂ represents an aliphatic group, a monocyclic aliphatic group, a monocyclic aromatic group, a fused polycyclic aromatic group. Selected from the group consisting of non-condensed polycyclic aromatic groups in which the groups and the aromatic groups are connected to each other directly or by a bridging member
Represents a valence group. 5% of a polyisoimide component represented by
More preferably, it is at least 50%, more preferably at least 80%.

[0010] The polyisoimide film / fiber can be produced using polyamic acid as a precursor thereof as a raw material.

(A) Preparation of Polyisoimide Precursor Polyamic acid, which is a precursor of polyisoimide, is obtained by polymerizing a diamine and an acid anhydride in a solvent. The acid anhydride used in the present invention has a general formula (II)

[0012]

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(Wherein R ₁ represents at least a tetravalent organic group).

Specific examples of the acid anhydride include pyromellitic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 2,3,5,6-pyridinetetracarboxylic dianhydride 2,3,4,5-thiophenetetracarboxylic dianhydride, 2,2 ′, 3,3′-benzophenonetetracarboxylic dianhydride, 2,3 ′, 3,4′-benzophenonetetracarboxylic dianhydride Anhydrous, 3,3 ', 4
4'-benzophenonetetracarboxylic dianhydride, 3,
3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride , 3,3 ′, 4,4′-p-terphenyltetracarboxylic dianhydride, 2,2 ′, 3,3′-p
-Terphenyltetracarboxylic dianhydride, 2,3
3 ′, 4′-p-terphenyltetracarboxylic dianhydride, 1,2,4,5-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1 2,2,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 2,3 1,6,7-anthracenetetracarboxylic dianhydride, 1,2,5,6-anthracenetetracarboxylic dianhydride, 1,2,6,7-phenanthrenetetracarboxylic dianhydride, 1,2 , 7,8-Phenanthrenetetracarboxylic dianhydride, 1,2,9,10
Phenanthrene tetracarboxylic dianhydride, 3,4
9,10-perylenetetracarboxylic dianhydride, 2,6
-Dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,4,
5,8-tetracarboxylic dianhydride, 2,3,6,7-
Tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 1,4,5,8-tetrachloronaphthalene-2,3,6,7-tetracarboxylic dianhydride, bis (2 3-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) ) Methane dianhydride, bis (2,3-dicarboxyphenyl) sulfone dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3-dicarboxyphenyl) Ethane dianhydride, 1,1-bis (3,
4-dicarboxyphenyl) ethane dianhydride, 2,2-
Bis (2,3-dicarboxyphenyl) propane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,6-bis (3,4-dicarboxyphenoxy) pyridine dianhydride Anhydride, 1,1,1,3,3
3-Hexafluoro-2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) dimethylsilane dianhydride, and the like, but are not limited thereto. Absent.

The diamine used for the polymerization of the polyamic acid of the present invention is represented by the following formula (III):

[0016]

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(Wherein R _{2 is an} aliphatic or aromatic general). As specific examples, m-phenylenediamine, p-phenylenediamine, 1,4-diaminonaphthalene, 1,5-diaminonaphthalene, 1,8-diaminonaphthalene, 2,6-diaminonaphthalene, 2,7
-Diaminonaphthalene, 2,6-diaminoanthracene, 2,7-diaminoanthracene, 1,8-diaminoanthracene, 2,4-diaminotoluene, 2,5-diamino (m-xylene), 2,5-diaminopyridine,
2,6-diaminopyridine, 3,5-diaminopyridine, 2,4-diaminotoluenebenzidine, 3,3′-
Diaminobiphenyl, 3,3′-dichlorobenzidine,
3,3′-dimethylbenzidine, 3,3′-dimethoxybenzidine, 2,2′-diaminobenzophenone, 4,
4'-diaminobenzophenone, 3,3'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenylmethane, 4,4 '
-Diaminodiphenylmethane, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfide, 4,
4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenylthioether, 4,4'-diamino-
3,3 ′, 5,5′-tetramethyldiphenyl ether, 4,4′-diamino-3,3 ′, 5,5′-tetraethyldiphenyl ether, 4,4′-diamino-3,
3 ′, 5,5′-tetramethyldiphenylmethane, 1,
3-bis (3-aminophenoxy) benzene, 1,3-
Bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 1,4-bis (4
-Aminophenoxy) benzene, 2,6-bis (3-aminophenoxy) pyridine, 1,4-bis (3-aminophenylsulfonyl) benzene, 1,4-bis (4-aminophenylsulfonyl) benzene, 1,4 -Screw (3
-Aminophenylthioether) benzene, 1,4-bis (4-aminophenylthioether) benzene, 4,
4'-bis (3-aminophenoxy) diphenylsulfone, 4,4'-bis (4-aminophenoxy) diphenylsulfone, bis (4-aminophenyl) aminebis (4-aminophenyl) -N-methylaminebis (4 −
Aminophenyl) -N-phenylamine bis (4-aminophenyl) phosphine oxide, 1,1-bis (3-
Aminophenyl) ethane, 1,1-bis (4-aminophenyl) ethane, 2,2-bis (3-aminophenyl)
Propane, 2,2-bis (4-aminophenyl) propane, 2,2-bis (4-amino-3,5-dimethylphenyl) propane, 4,4′-bis (4-aminophenoxy) biphenyl, bis [ 4- (3-aminophenoxy)
Phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] methane, bis [3- Methyl-4
-(4-aminophenoxy) phenyl] methane, bis [3-chloro-4- (4-aminophenoxy) phenyl] methane, bis [3,5-dimethyl-4- (4-aminophenoxy) phenyl] methane, 1 , 1-bis [4-
(4-aminophenoxy) phenyl] ethane, 1,1-
Bis [3-methyl-4- (4-aminophenoxy) phenyl] ethane, 1,1-bis [3-chloro-4- (4-
Aminophenoxy) phenyl] ethane, 1,1-bis [3,5-dimethyl-4- (4-aminophenoxy) phenyl] ethane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, , 2-Bis [3-methyl-4- (4-aminophenoxy) phenyl] propane, 2,2-bis [3-chloro-4- (4-aminophenoxy) phenyl] propane, 2,2-bis [3 , 5-
Dimethyl-4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy)
Phenyl] butane, 2,2-bis [3-methyl-4-
(4-aminophenoxy) phenyl] butane, 2,2-
Bis [3,5-dimethyl-4- (4-aminophenoxy) phenyl] butane, 2,2-bis [3,5-dibromo-4- (4-aminophenoxy) phenyl] butane,
1,1,1,3,3,3-hexafluoro-2,2-bis (4-aminophenyl) propane, 1,1,1,3,
3,3-hexafluoro-2,2-bis [3-methyl-
4- (4-aminophenoxy) phenyl] propane and the like, but is not limited thereto.

The solvent used for polymerizing the polyamic acid may be any solvent that dissolves the polyamic acid and does not react with the condensing agent. Specific examples include N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, hexamethylphosphoramide, 1,3-dimethylimidazolidinone, tetramethylurea, 1,3-
Aprotic polar solvents such as dipyropyrimidazolidinone, N-methylcaprolactam, dimethylsulfoxide, dimethylsulfone, tetramethylsulfone, ethylene glycol, pyridine, 2-picoline, 3-picoline, 4-picoline, 2,3 -Heteroaromatic compounds such as lutidine, 2,4-lutidine, 2,5-lutidine, 2,6-lutidine, 3,4-lutidine, 3,5-lutidine, 2,6-lutidine; Cresols and the like.

These solvents include carbon tetrachloride, chloroform, dichloromethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane, 1,1,1,2-
To be used by mixing with other solvents such as organic halides such as tetrachloroethane, 1,1,2,2-tetrachloroethane, trichloroethylene and tetrachloroethylene, benzene, toluene, benzonitrile, xylene, solvent naphtha, and dioxane. It is possible, but not limited to this.

In order to obtain the polyamic acid in the present invention, the amount of the diamine used in the above-mentioned organic solvent is preferably 0.90 to 1.10 as a ratio to the number of moles of the acid anhydride.
More preferably, the reaction is carried out at 0.95 to 1.05 to obtain a polyamic acid.

In the polyamic acid, it is preferable to block the terminal of the polymer. When the end capping agent is used for sealing, the terminal capping agent is phthalic anhydride and its substituted product, hexahydrophthalic anhydride and its substituted product, succinic anhydride and its substituted product, and the amine component is aniline and The substituents include, but are not limited to.

(A) Production of Polyisoimide Molding Precursor The method for producing a polyisoimide film and fibers from the precursor polyamic acid is not limited, but the following method can be used.

(1) A condensing agent is charged into a polyamic acid solution to be converted into a polyisoimide, and then molded into a film or fiber.

(2) After casting the polyamic acid solution as a film or spinning from a nozzle, the solvent of the polyamic acid solution is completely or partially removed and then reacted with a condensing agent to form polyisoimidization.

(3) The polyamic acid solution is cast as a film or spun from a nozzle and directly introduced into the condensing agent solution to obtain a polyisoimide molded article.

Of the above, (1) can be used only when the polyisoimide used is soluble in a solvent. (2) and (3) are preferable methods for producing polyimide having high rigidity, since polyisoimide can be used regardless of whether it is soluble or not in a solvent.

The method (3) is a particularly preferable method since a polyisoimide film and a fiber having high stretchability can be obtained in the stretching described later.

Examples of the condensing agent include acid anhydrides such as acetic anhydride, benzoic anhydride and trifluoroacetic acid dianhydride; chlorides such as phosgene, thionyl chloride, tosyl chloride and nicotyl chloride; phosphorus trichloride, Phosphorus compounds such as triphenyl phosphate and diethyl phosphate cyanide; condensing agents such as N, N'-disubstituted carbodiimides such as N, N'-dicyclohexylcarbodiimide, and more preferably N, N'-dicyclohexylcarbodiimide However, it is not limited to this.

To further facilitate the progress of isoimidization, tertiary aliphatic amines such as trimethylamine, triethylamine, tributylamine and diisopropylethylamine; N, N-dimethylaniline, 1,8-
Heterocyclic compounds such as aromatic amines such as bis (N, N-dimethylamino) naphthalene, pyridine, lutidine, quinoline, isoquinoline, 1,8-diazabicyclo [5.4.0] undecene, and N, N-dimethylaminopyridine It may be used as a reaction accelerator.

In the methods (2) and (3) for producing polyisoimide films and fibers, the condensing agent can be used as a solution with the following solvents. The solvent constituting the solution may be any general organic solvent which does not react by dissolving the condensing agent and does not substantially dissolve the polyisoimide in the condensing agent solution. Particularly, by using a condensing agent solution that does not dissolve the polyisoimide but swells, the swelling step described below is not required, and a swellable isoimide having high stretchability can be obtained.

As such a solvent, N-methyl-2-
Pyrrolidone, N, N-dimethylformamide, N, N '
Amide solvents such as diethylacetamide and general organic solvents such as aromatics, hydrocarbons, alcohols, ketones, esters and ethers, especially N
Highly polar solvents such as -methyl-2-pyrrolidone and N, N ',-dimethylacetamide are preferably used when using a polyisoimide which gives a highly rigid polyimide after imidization.

These organic solvents may be used alone,
Alternatively, two or more kinds may be used in combination. The solution is preferably dehydrated because the resulting polyisoimide component reacts with moisture and returns to polyamic acid.

Although the concentration of the condensing agent in the condensation solution is not specified, it is preferably 1% or more in order to allow the reaction to proceed sufficiently.

The reaction temperature at the time of reacting the condensing agent with the polyamic acid is not particularly limited, but a temperature from the freezing point of the condensing agent solution to the boiling point of the solvent can be used.

When the condensing agent is added directly to the polyamic acid solution as in the above (1), the resulting polyisoimide may be isolated by a technique such as reprecipitation. The isolated polyisoimide may be redissolved in a solvent and cast as a film or spun from a nozzle. The reprecipitation solvent at this time is not particularly limited, but may be any solvent that does not contain water, dissolves the condensing agent, and does not dissolve the polyisoimide. Alternatively, the material may be cast or spun from a nozzle in a molten state without re-melting. The temperature at this time is not particularly limited, but is preferably a temperature at which imidization is not performed.

Similarly, in the above method (1), the polyisoimide solution may be cast directly as a film or spun from a nozzle without isolation after the formation of the polyisoimide.

After the polyamic acid solution is cast as a film or spun from a nozzle as in the above (2), the solvent of the polyamic acid solution is completely or partially removed, and then the polyamic acid solution is reacted with a condensing agent to form polyisoimidization. Examples of the method for removing the solvent in this case include removal by heating under reduced pressure or normal pressure, and removal by heating at reduced pressure or normal pressure after immersion in a solvent having a lower boiling point and solvent replacement. It is not something that can be done.

As described in the above (3), the polyamic acid solution is cast into a film or spun from a nozzle and directly introduced into the condensation solution, thereby introducing the polyamic acid solution into the condensing agent solution in the method for obtaining a polyisoimide molded article. As the method, any generally known wet or dry-wet molding method may be used. Examples of the film forming method include a die extrusion method, a casting method using an applicator, a method using a coater, and the like, but are not limited thereto. In addition, spinning methods such as wet spinning and dry jet spinning are exemplified, but not limited thereto. These steps are preferably performed in a low-humidity atmosphere in order to prevent inactivation of the condensing agent.

(C) Stretching The polyisoimide obtained by the above (1), (2) and (3) is stretched to obtain a stretched polyisoimide. The details will be described below.

Examples of the stretching method of the polyisoimide include dry stretching and wet stretching, but are not particularly limited. In order to further increase the stretching ratio, wet stretching is preferable, and these may be combined. The heating temperature in the dry stretching is not particularly limited.

In the stretching, it is preferable that the polyisoimide is swollen with a solvent. By stretching while the polyisoimide is swollen with a solvent, uniform and high-magnification stretching can be performed.

The solvent used for swelling the polyisoimide is not particularly limited as long as the solvent swells without substantially dissolving the polyisoimide. Examples of such a solvent include amide solvents such as N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N′-diethylacetamide, and aromatics, hydrocarbons, alcohols, ketones, esters, and ethers. Examples include, but are not limited to, general organic solvents. These organic solvents may be used alone or in combination of two or more. Further, it is more preferable to use the solvent used for polyisoimidization as it is. The solution is preferably dehydrated because the resulting polyisoimide component reacts with moisture and returns to polyamic acid. The immersion time in the swelling solution may be a time sufficient for swelling.

The degree of swelling of the swollen polyisoimide film or fiber is not particularly limited, but is preferably 10 to 3000%, more preferably 100 to 3000%.
2000%. The degree of swelling at this time was calculated from the weight ratio between the swollen state and the dried state. That is, when the weight in the dry state was W1 and the weight at the time of swelling was W2, it was calculated as (W2 / W1-1) × 100 = swelling degree.

After stretching, the obtained stretched polyisoimide may be washed with a poor solvent and replaced with a solvent. At this time, as the poor solvent, hydrocarbons, alcohols, ketones, esters,
Examples include general organic solvents such as ethers, but are not limited thereto. These organic solvents may be used alone or in combination of two or more. The stretching method is
Any generally known method may be used. In biaxial stretching, either simultaneous or sequential stretching may be used. The stretching may be performed in a solvent, in air, in an inert atmosphere, or in a heated state. The temperature at the time of stretching may be any temperature at which the solvent does not evaporate.

(D) Imidization The polyisoimide produced by the above method is imidized.
Although any method may be used for this method, a preferable method is heat treatment by heating. Examples of the heat treatment method include, but are not limited to, hot air heating, vacuum heating, infrared heating, microwave heating, and heating by contact using a hot plate or a hot roll. A polyimide is obtained by performing a heat treatment at 50 to 500 ° C. using these methods. At this time, it is preferable that the imidization be advanced by increasing the temperature stepwise. By performing imidization sufficiently, a film having good hydrolysis resistance can be obtained.

[0046]

The method of the present invention will be described in more detail with reference to the following examples. However, these examples do not limit the scope of the present invention.

The logarithmic viscosity of the polyamic acid was measured at 35 ° C. at a polymer concentration of 0.5 g / 100 ml in NMP. The degree of swelling was calculated from the weight ratio between the swollen state and the dried state. That is, when the weight in the dry state was W1 and the weight at the time of swelling was W2, it was calculated as (W2 / W1-1) × 100 = swelling degree. The elongation was measured using a sample of 25 mm × 5 mm at a tensile speed of 2 mm / min and measured by Orientec UCT-1T.

(A) Preparation of Polyamic Acid Solution A reaction vessel equipped with a thermometer, a stirrer, and a material input port is
In a nitrogen atmosphere, 910 mL of N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP) dehydrated with molecular sieves was added, and 19.9 g of paraphenyldiamine was added. After completely dissolving, the mixture was cooled to 0 ° C. in an ice bath. 40.1 g of pyromellitic anhydride was added to the cooled diamine solution.
Was added and reacted. The reaction temperature was raised to 25 ° C., and the reaction was further performed for 1 hour in a cooled state. 2 at room temperature
After reacting for an hour, 0.011 g of aniline was added and reacted for another 30 minutes. After completion of the reaction, the mixture was filtered under a nitrogen atmosphere and then defoamed to obtain a polyamic acid solution. The logarithmic viscosity of this solution was 4.12 and the final polymer concentration was 6 wt.
%.

(A) Production of Polyisoimide Precursor N, N was placed in a vessel equipped with a temperature controller and a stirrer.
An NMP solution having a concentration of 15% by weight of N′-dicyclohexylcarbodiimide (hereinafter abbreviated as DCC) was charged and heated to 45 ° C. to form a DCC bath. Further, the polyamic acid solution prepared in the above (A) was placed on a glass
Was cast using a doctor blade. This was introduced into the above-described DCC bath and solidified by reaction for 10 minutes, then peeled off from the glass substrate, and further reacted for 10 minutes for a total of 20 minutes to obtain a polyisoimide film.

(C) Stretching The above-mentioned polyisoimide was NMP: toluene = 25: 75.
After immersion at room temperature for 15 minutes, the film was cut into a 120 mm square film, stretched and set between the support members without slack, and both ends of the isoimide film were fixed with chucks. The degree of swelling of the film at this time was 1780%. This was 1.5 times in the TD direction at room temperature and 1.5 times in the MD direction.
The film was sequentially stretched twice at a speed of 5 mm / sec.

After the stretching, the film is detached from the stretching machine while being fixed to the two pairs of support members with the film attached to the stretching machine, immersed in isopropanol at room temperature for 10 minutes to extract the solvent and the like from the imide precursor and re-examined. Coagulated.

(D) Production of imide The polyisoimide produced in (c) was fixed to a frame, and then heat-treated with a dryer. That is, 5 minutes at 80 ° C, 200 ° C
The temperature was increased stepwise to 10 minutes, 250 ° C. for 8 minutes, 350 ° C. for 5 minutes, and 380 ° C. for 5 minutes to obtain a polyimide film. The thickness of the obtained polyimide film is 12μ.
m, the tensile modulus in the MD direction was 20.0 GPa, the tensile strength was 0.49 GPa, and the elongation was 6.0%.

[0053]

According to the method of the present invention, it is possible to produce a polyimide film and a fiber having improved mechanical properties by stretching orientation.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Jiro Jonobu 2-1 Hinode-machi, Iwakuni-shi, Yamaguchi Prefecture F-term in the Iwakuni Research Center, Teijin Limited 4F071 AA60 AF13 AF45 BA02 BB02 BB12 BB13 BC01 BC02 4L035 EE08 FF01 MD01

Claims (3)

[Claims] 1. A method for producing a polyimide film and a fiber, comprising stretching a polyisoimide and then imidizing it. 2. The method according to claim 1, wherein the polyisoimide is swollen by a solvent during stretching. 3. The method for producing a polyimide film and fiber according to claim 1, wherein the polyisoimide is formed by introducing a polyamic acid solution into a condensing agent solution.