JP2002248638A - Method for manufacturing polyimide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a polyimide film with high productivity without bringing about the lowering of strength. SOLUTION: The polyimide film can be manufactured with high productivity without bringing about the lowering of strength by a process for casting or applying a polyamic acid organic solvent solution on a support to dry the formed layer to manufacture a partially cured and/or partially dried polyamic acid film, a process for immersing the polyamic acid film in a tertiary amine or a tertiary amine solution or coating the same with the tertiary amine or the tertiary amine solution and a process for drying the polyamic acid film while imidating the polyamic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention provides a method for producing a polyimide film having good productivity and high mechanical strength.

[0002]

2. Description of the Related Art Polyimide films have heat resistance, insulation, solvent resistance, low temperature resistance and the like, and are widely used as materials for electric and electronic devices for computers and IC control.

In recent years, polyimide films have been widely used for small general-purpose devices such as mobile phones, and the demand for polyimide films has been increasing. As a result, the development of a method for producing polyimide films having even higher productivity has been rapidly developed. Is peeling.

[0004] Usually, a polyimide film is produced by either a heat curing method or a chemical curing method.
For example, in the case of the heat curing method, a solvent is removed from a polyamic acid varnish, which is a polyimide precursor, to form a polyamic acid film, and then converted to a polyimide film by heating. In this method, if the heating time is reduced, problems such as insufficient physical properties and breakage of the film arise. In addition, in the case of the chemical curing method, a gel film is obtained by mixing a polyamic acid varnish with a chemical imidizing agent, and this is further cured and dried to obtain a polyimide film, but partially cured to improve productivity. Attempting to shorten the time of preparing a partially dried polyamic acid film (gel film) and / or insufficient chemical imidization of the gel film, resulting in a tear propagation strength of the resulting polyimide film,
There is a problem that basic mechanical strength such as tensile strength and adhesive strength is reduced.

[0005]

SUMMARY OF THE INVENTION In view of the above situation, the present inventors have made intensive studies and as a result, the present invention relates to a method for producing a polyimide film having high productivity and high mechanical strength. It has been reached.

[0006]

According to the method for producing a polyimide film of the present invention, a polyamic acid organic solvent solution is cast or coated on a support, dried, partially cured and / or partially cured. Step of manufacturing a dried polyamic acid film, immersing the polyamic acid film in a tertiary amine or a solution of a tertiary amine, or applying a tertiary amine or a solution of a tertiary amine to the polyamic acid film. The method includes a step of applying and then a step of drying the film while imidizing the polyamic acid to polyimide.

[0007] The method may further include a step of removing excess droplets remaining on the film surface.

Furthermore, the partially cured and / or partially dried polyamic acid film has a residual volatile matter content of 5%.
To 100 wt% or less, and the imidization ratio may be 50% or more.

[0009] The tertiary amine may be selected from the group consisting of quinoline, isoquinoline, β-picoline and pyridine.

[0010] The polyimide film of the present invention can be produced by any of the above methods.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for producing a polyimide film according to the present invention, a polyamic acid organic solvent solution is cast or coated on a support, dried and partially cured and / or partially dried. A step of producing a polyamic acid film, wherein the polyamic acid film is a tertiary amine or tertiary amine;
A polyamic acid film is immersed in a solution of a tertiary amine, or a tertiary amine or a tertiary amine is immersed in the polyamic acid film.
Applying a solution of a secondary amine, followed by imidizing the polyamic acid into polyimide and drying the film. Hereinafter, a method for producing a polyimide film of the present invention will be described based on an example of the embodiment.

The method for producing a polyimide film of the present invention is basically applicable to any polyimide film production.

The polyamic acid used in the present invention is a precursor of polyimide, and basically any known polyamic acid can be applied. Usually, at least one kind of aromatic dianhydride and at least one kind of diamine are used as raw materials, and substantially equimolar amounts thereof are dissolved in an organic solvent, and the resulting polyamic acid organic solvent solution is controlled. It is manufactured by stirring under the temperature condition described above until the polymerization of the acid dianhydride and the diamine is completed.

Here, the materials used for producing the polyamic acid which is the polyimide precursor of the present invention will be described.

Examples of the acid anhydride which can be used for producing polyamic acid include pyromellitic dianhydride, 2,2
3,6,7-naphthalenetetracarboxylic dianhydride,
3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 3,4,9,1
O-perylenetetracarboxylic dianhydride, bis (3,4
-Dicarboxyphenyl) propane dianhydride, 1,1-
Bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxyphenyl)
Methane dianhydride, bis (3,4-dicarboxyphenyl) ethane dianhydride, oxydiphthalic dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride,
Includes p-phenylene bis (trimellitic acid monoester acid anhydride), ethylene bis (trimellitic acid monoester acid anhydride), bisphenol A bis (trimellitic acid monoester acid anhydride) and the like. These may be used alone or in a mixture at any ratio.

Of these, the acid dianhydride most suitably used in the polyimide precursor polyamic acid of the present invention is pyromellitic dianhydride, 3,3 ', 4,
4'-benzophenonetetracarboxylic dianhydride, 3,
3 ′, 4,4′-biphenyltetracarboxylic dianhydride and p-phenylenebis (trimellitic acid monoester acid anhydride), which can be used alone or in a mixture at any ratio.

Suitable diamines which can be used in the preparation of the polyimide precursor polyamic acid according to the present invention are 4,4'-diaminodiphenylpropane, 4,4 '
-Diaminodiphenylmethane, benzidine, 3,3'-
Dichlorobenzidine, 4,4′-diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfone,
4,4′-diaminodiphenylsulfone, 4,4′-diaminodiphenylether, 3,3′-diaminodiphenylether, 3,4′-diaminodiphenylether, 1,5-diaminonaphthalene, 4,4′-diaminodiphenyldiethylsilane, 4,4'-diaminodiphenylsilane, 4,4'-diaminodiphenylethylphosphine oxide, 4,4'-diaminodiphenyl N-methylamine, 4,4'-diaminodiphenyl N-phenylamine, 1,4-diaminobenzene (P-phenylenediamine), 1,3-diaminobenzene, 1,2-diaminobenzene, and the like, and these can be preferably used alone or in a mixture at any ratio.

Among these diamines, 4,4'-diaminodiphenyl ether and p-phenylenediamine are particularly preferred, and they are preferably used in a molar ratio of 100: 0 to 0: 100, preferably 100: 0 to 10:90. A mixed mixture can be preferably used.

Solvents that can be preferably used for synthesizing the polyamic acid include amide solvents, ie, N, N-dimethylformamide, N, N-dimethylacetamide,
N-methyl-2-pyrrolidone and the like, and it is preferable to use N, N-dimethylformamide or N, N-dimethylacetamide alone or in a mixture at an arbitrary ratio.

The polyamic acid solution is usually 5 to 35 wt.
%, Preferably 10 to 30% by weight. When the concentration is within this range, an appropriate molecular weight and solution viscosity can be obtained.

The polyimide is obtained by imidizing a polyamic acid as a precursor. For the imidation, either a thermal curing method or a chemical curing method is used. The thermal curing method is a method in which an imidization reaction proceeds only by heating without the action of a dehydrating ring-closing agent or the like. In addition, the chemical curing method is represented by a polyamic acid organic solvent solution, a chemical conversion agent represented by an acid anhydride such as acetic anhydride, and a tertiary amine such as isoquinoline, β-picoline, and pyridine. This is a method of reacting with a catalyst. A thermal curing method may be used in combination with the chemical curing method. The reaction conditions for imidization can vary depending on the type of polyamic acid, the thickness of the film, the selection of a thermal curing method and / or a chemical curing method, and the like.

When the imidation is carried out by a chemical curing method, in the production of the polyimide film according to the present invention, the chemical conversion agent added to the polyamic acid solution may be, for example, an aliphatic acid anhydride, an aromatic acid anhydride, N, N'-dialkylcarbodiimides, lower aliphatic halides, halogenated lower aliphatic halides, halogenated lower fatty acid anhydrides, arylphosphonic dihalides, thionyl halides, or a mixture of two or more thereof.
Among them, aliphatic anhydrides such as acetic anhydride, propionic anhydride, and lacnic anhydride or a mixture of two or more thereof can be preferably used. The amount of the chemical conversion agent is 0.5 to the number of moles of amic acid in the polyamic acid solution.
It can be used in a ratio of up to 5 times, preferably 1 to 4 times, more preferably 1.5 to 3 times.

For effective imidization, it is preferable to use a catalyst simultaneously with the chemical conversion agent. As the catalyst, an aliphatic tertiary amine, an aromatic tertiary amine, a heterocyclic tertiary amine or the like is used. Among them, those selected from heterocyclic tertiary amines can be particularly preferably used. Specifically, quinoline, isoquinoline, β-picoline, pyridine and the like are preferably used. As the amount of the catalyst, with respect to the number of moles of amic acid in the polyamic acid solution,
It can be used in a ratio of 0.1 to 2 times, preferably 0.2 to 1 time. If the amount is too small, the imidization ratio tends to be smaller than a suitable range, and if the amount is too large, the curing speed is increased, and it is difficult to cast on the support.

In the method for producing a polyimide film of the present invention, the step of producing a partially cured and / or partially dried polyamic acid film (referred to as a gel film) can be performed by a known method. That is, the prepared polyamic acid organic solvent solution is cast or applied on a support such as a glass plate, an endless stainless belt, or a stainless steel drum, and thermally imidized. Alternatively, the chemical conversion agent and the catalyst are activated by mixing the chemical conversion agent and the catalyst at a low temperature into the polyamic acid solution, and subsequently casting the polyamic acid solution into a film on a support and heating. . By these thermal or chemical imidization, a polyamic acid film (gel film) which is partially cured and has a self-supporting property is produced.

The gel film is at an intermediate stage of curing from polyamic acid to polyimide, and has self-supporting properties.
The state of the gel film can be represented by the residual volatile matter content and the imidization ratio. The residual volatile content and the imidation ratio are calculated by the following equations.

The residual volatile matter content is represented by the following formula: (A−B) × 100 / B (1) In Formula 1, A and B represent the following. A: Weight of gel film B: Calculated from weight after heating gel film at 450 ° C. for 20 minutes.

The imidation ratio can be calculated by the following formula (C / D) × 100 / (E / F) using the infrared absorption spectrometry. In the formula 2, C, D, E and F are as follows: Represents C: Absorption peak height of gel film at 1370 cm ^-1 D: Absorption peak height of gel film at 1500 cm ^-1 E: Absorption peak height of polyimide film at 1370 cm ^-1 F: Absorption peak of polyimide film at 1500 cm ^-1 Calculated from height.

The gel film has a residual volatile matter content of 5 to 500.
%, Preferably 5-100%, more preferably 1%
It is in the range of 0-80%, most preferably 30-60%. It is preferable to use a film in this range. The imidation ratio of the gel film is in the range of 50% or more, preferably 80%.
Or more, more preferably 85% or more, and most preferably 90% or more.
% Or more. It is preferable to use a film in this range, and if it is out of this range, it is difficult to achieve a predetermined effect.

According to the method for producing a polyimide film of the present invention, the gel film preparation time is the same as the conventional gel film production time as long as a gel film having the above-mentioned residual volatile content and imidation ratio can be obtained. More than 20-70
%, Or even 10 to 70%.

Next, the partially cured and / or partially dried polyamic acid film obtained by the heat curing method or the chemical curing method is coated with a tertiary amine or a tertiary amine solution. Or partially cured and / or
Or a partially dried polyamic acid film
It is subjected to a step of dipping in a solution of a tertiary amine or a tertiary amine.

The tertiary amine to be applied or dipped on the partially cured and / or partially dried polyamic acid film (gel film) includes an aliphatic tertiary amine, an aromatic tertiary amine, Heterocyclic tertiary amines and the like are used. Among them, those selected from heterocyclic tertiary amines can be particularly preferably used. Specifically, quinoline, isoquinoline, β-picoline, pyridine and the like are preferably used. These tertiary amines may be used alone or in a mixture of two or more. Further, it can be used as an organic solvent solution. In this case, it may be diluted with any solvent, but amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone And N, N-
It is preferred to use dimethylformamide or N, N-dimethylacetamide alone or in a mixture in any proportion. When used after dilution, any concentration may be used, but the concentration of the tertiary amine is 100 to 5% by weight.
It is preferable to use a solution prepared so that When an excessively dilute solution is used, the effect of suppressing a decrease in strength, which is one of the objects of the present invention, is reduced.

The tertiary amine or tertiary amine is added to the gel film.
As a method of applying the graded amine solution, a known method that can be used by those skilled in the art can be used.For example, a coating method using a gravure coat, a spray coat, a knife coater, or the like can be used, and control of the coating amount and uniformity can be used. From the viewpoint of properties, a gravure coater can be particularly preferably used. The application amount is 1
g / m ² or more and 40 g / m ² are preferable, and 5 g / m ² or more and 30 g / m ² are more preferable. If the coating amount is less than this range, it is difficult to suppress the strength from decreasing. If the amount is larger than this range, the appearance of the film becomes worse.

When dipping in a tertiary amine or a tertiary amine solution, there is no particular limitation, and a general dip coating method can be used. Specifically, the gel film is immersed in a bath containing the above solution continuously or in batches. Immersion time is 1 second or more and 100
Seconds, preferably 1 to 20 seconds, are preferred. If the length is longer than this range, the appearance of the film becomes poor, and if the immersion time is too short, it becomes difficult to suppress a decrease in strength.

After the tertiary amine or the tertiary amine solution is applied or immersed in the gel film, a step of removing excess liquid droplets on the film surface may be added. It is preferable because an excellent polyimide film can be obtained. Known methods such as liquid squeezing by a nip roll, an air knife, a doctor blade, wiping, and sucking can be used for removing the droplets, and a nip roll is preferably used from the viewpoint of film appearance, liquid drainage, workability, and the like. obtain.

As described above, the gel film to which the tertiary amine or the tertiary amine solution has been applied or immersed is fixed at the ends in order to avoid shrinkage during curing.
The fixed gel film is subjected to a drying step. The water, the residual solvent, the residual converting agent and the catalyst in the gel film are removed, and the imidized amic acid is completely imidized to obtain a polyimide film. Regarding the temperature condition of this drying step, it is preferable that the temperature is finally raised to a temperature of 500 to 580 ° C., and heating is performed in this temperature range for 1 to 400 seconds. If the temperature is higher than this temperature and / or the heating time is long, thermal degradation of the film occurs, causing a problem. Conversely, if the temperature is lower than this temperature and / or the heating time is short, the predetermined effect is not exhibited.

With respect to the polyimide film produced by the method for producing a polyimide film of the present invention, a polyimide film capable of maintaining a desired mechanical strength can be obtained even if the time for forming a gel film is shortened. Therefore,
The productivity can be improved by shortening the gel film making time, preventing the tear propagation strength and the adhesive strength from decreasing,
A polyimide film with improved tensile strength is obtained.

The polyimide film according to the present invention is preferably used for a flexible printed circuit board, a magnetic tape for general magnetic recording, a magnetic disk, a passivation film of a semiconductor element such as a solar cell, and the like.

[0038]

EXAMPLES The effects of the present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples, and those skilled in the art depart from the scope of the present invention. Without departing, various changes, modifications, and alterations may be made.

The tear propagation strength of the polyimide film is A
STM D-1938, tensile strength is JIS C-2318
It measured according to.

The adhesive strength was determined by using a nylon-epoxy adhesive and electrolytic copper foil (trade name: 3ECV, manufactured by Mitsui Kinzoku Mining Co., Ltd.).
LP, thickness 35 μm) and a polyimide film to form a three-layer copper-clad laminate.
Was evaluated at 90 ° peel with a copper pattern width of 3 mm.

The temperature conditions in the heating step of the gel film were the same for both the comparative example and the example.

Comparative Example 1 Pyromellitic dianhydride /
Polyamic acid was synthesized at a molar ratio of 4,4'-diaminodiphenyl ether / p-phenylenediamine of 4/3/1. D containing 18.5 wt% of this polyamic acid
100 g of the MF solution was prepared, 35 g of acetic anhydride and a conversion agent composed of 5 g of β-picoline were mixed, stirred, defoamed by centrifugation, and then cast on an aluminum foil to a thickness of 400 μm. The process from stirring to defoaming was performed while cooling to 0 ° C. The laminate of the aluminum foil and the polyamic acid solution was heated at 120 ° C.
Heating was performed for 50 seconds to obtain a gel film having self-supporting properties. The residual volatile matter content of this gel film was 41% by weight, and the imidization ratio was 81%. This gel film was peeled off from the aluminum foil and fixed to a frame. The gel film was heated at 300 ° C., 400 ° C., and 500 ° C. for 30 seconds each to produce a polyimide film having a thickness of 25 μm.
Table 1 shows the basic mechanical properties of this polyimide film.

Comparative Example 2 Comparative Example 1 was conducted except that the laminate of the aluminum foil and the polyamic acid solution was heated at 160 ° C. for 75 seconds.
A polyimide film having a thickness of 25 μm was produced in exactly the same manner as described above. The gel film that passed through the intermediate stage had a residual volatile content of 36% by weight and an imidization ratio of 78%. Table 1 shows the basic mechanical properties of this polyimide film.
Shown in

Comparative Example 3 Pyromellitic dianhydride /
4,4'-diaminodiphenyl ether is added at a molar ratio of 1 /
A polyimide film having a thickness of 25 μm was produced in exactly the same manner as in Comparative Example 1 except that the polyimide film was used at a ratio of 1. The gel film passed through the intermediate stage had a residual volatile matter content of 40% by weight and an imidization ratio of 89%. Table 1 shows the tear propagation strength of this polyimide film.

Comparative Example 4 Comparative Example 2 was conducted except that the laminate of the aluminum foil and the polyamic acid solution was heated at 160 ° C. for 75 seconds.
A polyimide film having a thickness of 25 μm was produced in exactly the same manner as described above. The gel film passed through the intermediate stage had a residual volatile matter content of 38% by weight and an imidization ratio of 87%. Table 1 shows the basic mechanical properties of this polyimide film.
Shown in

Comparing Comparative Examples 1 and 2, and Comparative Examples 3 and 4, when the time for forming the gel film was shortened, the mechanical strengths of the tear propagation strength, the tensile strength, and the adhesive strength were all reduced.
It turns out that it falls.

Example 1 A gel film having a residual volatile content of 48 wt% and an imidation ratio of 78% was obtained in the same manner as in Comparative Example 2. The gel film was immersed in isoquinoline and passed through a nip roll to remove excess droplets, and then heated at 300 ° C., 400 ° C., and 500 ° C. for 30 seconds each to produce a polyimide film having a thickness of 25 μm. Table 1 shows the basic mechanical properties of this polyimide film.

Example 2 A gel film having a residual volatile matter content of 53% by weight and an imidation ratio of 78% was obtained in the same manner as in Comparative Example 2. This gel film is treated with 35 of isoquinoline.
After immersion in a DMF solution by weight and blowing compressed air to remove excess liquid droplets, the mixture was heated under the same conditions as in Comparative Example 2 to obtain a polyimide film having a thickness of 25 μm. Table 1 shows the basic mechanical properties of this polyimide film.

Example 3 A gel film having a residual volatile matter content of 49% by weight and an imidation ratio of 87% was obtained in the same manner as in Comparative Example 4. The gel film was immersed in isoquinoline and blown with compressed air to remove extra liquid droplets, and then heated under the same conditions as in Comparative Example 4 to obtain a polyimide film having a thickness of 25 μm. Table 1 shows the basic mechanical properties of this polyimide film.

Example 4 A gel film having a residual volatile matter content of 52% by weight and an imidation ratio of 87% was obtained in the same manner as in Comparative Example 4. This gel film is treated with 35 of isoquinoline.
After immersing in a DMF solution by weight and blowing compressed air to remove extra droplets, the mixture was heated under the same conditions as in Comparative Example 2 to obtain a polyimide film. Table 1 shows the basic mechanical properties of this polyimide film.

Example 5 In the same manner as in Comparative Example 4, a gel film having a residual volatile matter content of 51% by weight and an imidization ratio of 85% was obtained. This gel film is related to β picoline,
The compressed air was blown to remove excess liquid droplets, and then heated under the same conditions as in Comparative Example 2 to obtain a polyimide film. Table 1 shows the basic mechanical properties of this polyimide film.
Shown in

Example 6 Pyromellitic dianhydride /
4,4'-diaminodiphenyl ether is added at a molar ratio of 1 /
The polyamic acid was synthesized at a ratio of 1. 100 g of a DMF solution containing 18.5 wt% of this polyamic acid was prepared, a conversion agent consisting of 35 g of acetic anhydride and 5 g of β-picoline was mixed, stirred, defoamed by centrifugation, and then flown on an aluminum foil at a thickness of 400 μm. It was spread-coated. 0 from stirring to defoaming
Performed while cooling to ° C. The laminate of the aluminum foil and the polyamic acid solution was heated at 140 ° C. for 110 seconds to obtain a gel film having self-supporting properties. The residual volatile matter content of this gel film was 46% by weight, and the imidization ratio was 82%. After immersing this gel film in isoquinoline and removing excess droplets by passing through a nip roll,
Heating was performed at 300 ° C., 400 ° C., and 500 ° C. for 30 seconds each to produce a polyimide film having a thickness of 25 μm. Table 1 shows the basic mechanical properties of this polyimide film.

Example 7 Pyromellitic dianhydride /
4,4'-diaminodiphenyl ether is added at a molar ratio of 1 /
The polyamic acid was synthesized at a ratio of 1. 100 g of a DMF solution containing 18.5 wt% of this polyamic acid was prepared, a conversion agent consisting of 35 g of acetic anhydride and 5 g of β-picoline was mixed, stirred, defoamed by centrifugation, and then flown on an aluminum foil at a thickness of 400 μm. It was spread-coated. 0 from stirring to defoaming
Performed while cooling to ° C. The laminate of the aluminum foil and the polyamic acid solution was heated at 170 ° C. for 60 seconds to obtain a gel film having self-supporting properties. The residual volatile matter content of this gel film was 42% by weight, and the imidization ratio was 88%. This gel film was immersed in isoquinoline and passed through a nip roll to remove excess droplets.
The polyimide film was heated at 00 ° C., 400 ° C., and 500 ° C. for 30 seconds to produce a polyimide film having a thickness of 25 μm. Table 1 shows the basic mechanical properties of this polyimide film.

[0054]

[Table 1]

In the table, PMDA indicates pyromellitic dianhydride, 4,4 'ODA indicates 4,4'-diaminodiphenyl ether, and p-PDA indicates p-phenylenediamine.

In Examples 1 to 7, numerical values comparable to the mechanical strengths of the polyimide films according to Comparative Examples 1 and 3 in which the gel film preparation time was long were obtained although the gel film preparation time was shortened.

[0057]

According to the method for producing a polyimide film of the present invention, a polyimide film having high mechanical properties with good productivity can be produced.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F073 AA10 AA24 AA32 BA31 BB01 EA01 EA24 GA01 HA04 HA05 HA06 HA09 4F205 AA40 AC05 AG01 GA07 GB02 GC06 GW05 GW31

Claims (6)

[Claims] 1. A step of casting or coating a polyamic acid organic solvent solution on a support and drying to produce a partially cured and / or partially dried polyamic acid film, said polyamic acid film In a tertiary amine or a tertiary amine solution, or applying a tertiary amine or a tertiary amine solution to the polyamic acid film, and then imidizing the polyamic acid to polyimide, and A method for producing a polyimide film, comprising a step of drying the film. 2. The method for producing a polyimide film according to claim 1, further comprising a step of removing extra droplets remaining on the film surface. 3. The partially cured and / or partially dried polyamic acid film has a residual volatiles content of 5-10.
The method for producing a polyimide film according to claim 1 or 2, wherein the amount is 0 wt% or less. 4. The method for producing a polyimide film according to claim 1, wherein the partially cured and / or partially dried polyamic acid film has an imidation ratio of 50% or more. . 5. The method according to claim 5, wherein the tertiary amine is selected from the group consisting of quinoline, isoquinoline, β-picoline, and pyridine. 6. A polyimide film produced by the method according to claim 1.