JPH03146524A - Preparation of polyimide film - Google Patents

Abstract

PURPOSE:To prepare a polyimide film having excellent heat resistance and mechanical characteristics by orientating or coating a polyamic acid solution on a substrate, peeling the prepared film and subsequently subjecting the peeled film to a dehydrative cyclization reaction, the polyamic acid solution being prepared by polycondensing specific components such as a tetracarboxylic dianhydride in an organic solvent. CONSTITUTION:(A) A tetracarboxylic dianhydride, (B) can aromatic diamine and (C) compounds of formula I and/or II (A is a group of formula III, etc.; R is O, etc.) are polycondensed in an A/B/C molar ratio of 100/60-100/2-20 and under a relation of 0.95 X (mole number of B + 2 X mole number of C) < mole number of A < 1.05 X (mole number of B + 2 X mole number of C), and the prepared polyamic acid solution is orientated or coated on a substrate and subsequently peeled. The prepared gel film having a self-supporting property and a three-dimensional net structure is dehydratively cyclized to provide a polyimide film suitable for electronics, etc.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a method for producing a polyimide film that has excellent heat resistance and is widely used in electronics, transportation equipment, aerospace, etc. By preparing a new polyamic acid that gives a three-dimensional network structure, a so-called gel-like structure, in the form of a polyamic acid precursor, and then dehydrating and cyclizing this, it has excellent heat resistance and mechanical properties. The present invention relates to a method for obtaining a novel polyimide film with excellent properties.

[Prior art]

Polyamic acid obtained by polycondensing tetracarboxylic dianhydride and aromatic diamine in an organic solvent is used as a precursor, and dehydration and cyclization are proceeded by thermal dehydration or chemical dehydration reaction using a dehydrating agent to produce polyimide resin. Methods for obtaining it are well known, and numerous patent applications have been filed.

Generally, the polycondensation reaction is carried out in an organic solvent so that the polymer concentration of polyamic acid, which is a precursor of polyimide resin, is 5 to 20% by weight, and a high molecular weight polyamic acid solution uniformly dissolved in the organic solvent is removed. A film or a molded product is obtained by using a solvent, and a dehydration/cyclization reaction is further advanced by high temperature treatment or chemical treatment to obtain a polyimide molded product.

Due to its excellent heat resistance, abrasion resistance, chemical resistance, electrical insulation, and mechanical properties, polyimide resin is widely used as a material for electrical and electronic materials, adhesives, paints, composite materials, fibers, and film materials. ing.

Due to its excellent properties, polyimide resin films are used in a wide variety of applications as covering materials for electric wires, cables, wires, etc., and as insulating materials for transformers, printed wiring boards, etc.

Regarding the method for producing a polyimide film, a polyimide film is obtained by casting an organic polar solution of polyamic acid onto a substrate (support), and then promoting the dehydration ring-closing reaction of the polyamic acid by heating or chemical treatment. is common.

In addition, after casting an organic polar solution of polyamic acid,
It is also possible to obtain a film by desolvation by drying or by immersing the polymer solution together with the substrate in a coagulation bath to coagulate the polymer solution. The film obtained here is sometimes called a gel film, but unlike the gel film that gives a three-dimensional network structure obtained in the present invention,
It does not form a three-dimensional network structure due to chemical bonds. Hereinafter, the three-dimensional network structure film obtained by the present invention will be referred to as a gel film.

These polyimide films can also be obtained by polycondensation, and films obtained from a combination of pyromellitic dianhydride and 4,4°-diaminodiphenyl ether, which are typical polyimides, also have heat resistance. This type has high tensile properties.

However, in general, as heat resistance increases, the film tends to become brittle, and heat resistance and mechanical properties tend to contradict each other. In particular, polyimide made by combining pyromellitic dianhydride and paraphenylene diamine exhibits the highest level of physicochemical heat resistance, but it has poor film properties, is brittle, and has extremely poor mechanical properties. It is inferior. In this type of polyimide, it is also possible to improve the mechanical properties of the polyimide film by copolymerization technology. As an attempt to improve mechanical properties without reducing heat resistance, as shown in JP-A-63-254131, aromatic diamine was used in a combination system of pyromellitic dianhydride and paraphenylene diamine. 4.4 as another ingredient
-There are examples of copolymerization using diaminodiphenyl ether, but in order to improve the film forming ability, 4
．． 4゛-Shea is here.

[Purpose of the invention]

The purpose of the present invention is to improve the film forming ability and mechanical properties of a polyimide film containing tetracarboxylic dianhydride and aromatic diamine as main components without impairing the excellent heat resistance inherent to its constituent units. The present invention provides a method for producing a polyimide film having excellent properties with good reproducibility.

That is, the present invention forms a three-dimensional network structure of molecular chains by incorporating a small amount of specific monomer components into the constituent units of polyamic acid, which is a precursor of polyimide, and is self-supporting even when containing a large amount of solvent. By preparing a so-called polymeric gel film with high properties and further proceeding with dehydration and cyclization reactions to form a three-dimensional network structure of polyimide film, it is possible to achieve excellent mechanical properties without impairing the heat resistance of polyimide. The purpose is to obtain a polyimide film with a high temperature.

[Structure and effects of the invention]

The present invention is as follows.

(1) Contains the following [A] [B] [C] ingredients [A]/[
B]/(C) molar ratio is (100)/(60~
100) / (2 to 20) and 0.95X [(Number of moles of B) + 2x (Number of moles of C)]
< (Number of moles of A) < 1.05x [(Number of moles of B) + 2x (Number of moles of C)] An organic polar solvent solution of polyamic acid is cast or coated on a substrate to form a self-supporting solution. A method for producing a polyimide film, which comprises producing a polyamic acid gel film that provides a three-dimensional network structure, then peeling it off from a substrate, and subjecting the film to a dehydration and cyclization reaction.

[A] Tetracarboxylic dianhydride alone or in combination of two or more CI)] -N NH, -HC CIn-H
, NR represents 10--CH--CO--5o2] (2) [A
] component and [B] [C] A polyamic acid solution obtained by polycondensing the acid component is cast or coated onto a substrate to produce a uniform gel film of polyamic acid, and the film is peeled off from the substrate. Claim (1) wherein the dehydration/cyclization reaction is carried out.
)ifc! Method for producing a polyimide film (3): A gel film of polyamic acid containing 60 to 97% by weight of the total amount of an organic polar solvent is prepared by removing the solvent to a solvent content of 50% by weight or less, and then the film is prepared. The method for producing a polyimide film according to claim 1, wherein the polyimide film is subjected to a dehydration and cyclization reaction.

(4) A polyamic acid gel film containing 50% by weight or less of the total amount of organic polar solvent is fixed at least at both ends of the film, dried at a temperature of 50 to 200°C, and then dried at a temperature of 150°C or higher. The method for producing a polyimide film according to claim 1, wherein the polyimide film is heat-treated.

(5) A gel film of polyamic acid containing 50% by weight or less of the total amount of organic polar solvent is imidized by chemical dehydration treatment using a dehydrating agent such as an organic acid anhydride and a catalyst such as a tertiary amine. 2. The method for producing a polyimide film according to claim 1, wherein the polyimide film is heat-treated by drying and heating.

(6) A polyamic acid gel film containing 50% by weight or less of the total amount of organic polar solvent is immersed in a coagulation bath containing at least water, the film is coagulated and peeled off from the substrate, and then dried and heated. Claim (1) for heat treatment
) The method for producing the polyimide film described in ).

(7) [A] Claim in which the component tetracarboxylic dianhydride is pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, or biphenyltetracarboxylic dianhydride alone or in a mixture of two or more of them ( 1) The method for producing the polyimide film described above.

(8) Claim (B) wherein the aromatic diamine of component (B) is para-phenylene diamine, meta-phenylene diamine, or 4.4°-diaminodiphenyl ether alone or in a mixture.
1) The method for producing the polyimide film described above.

Representative examples of the tetracarboxylic dianhydride of component [A] in the present invention include pyromellitic dianhydride, 3.3-
．． 4.4--benzophenonetetracarboxylic dianhydride, 3.3-. 4.4″-Biphenyltetracarboxylic dianhydride, 2..3.3=, 4-Biphenyltetracarboxylic dianhydride, 2.2, S; a--Biphenyltetracarboxylic dianhydride, 2 .2-.6.6- -Biphenyltetracarboxylic dianhydride, 2,3.8.7-naphthalenetetracarboxylic dianhydride, 1,2.5.6-
Naphthalenetetracarboxylic dianhydride, 2,2-bis(
3,4-dicarboxyphenyl)brobannianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride), 3.4,9.10-perylene Tetracarboxylic dianhydride, naphthalene-1,2,4,5-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, benzene-1,2,3,4 -tetracarboxylic dianhydride, ethylene glycol bis(anhydrotrimellitate), etc., and these can be used alone or in a mixture of two or more.

Among these, as the tetracarboxylic dianhydride, it is preferable to use pyromellitic dianhydride, benzophenonetetracarboxylic dianhydride, and biphenyltetracarboxylic dianhydride alone or in a mixture of two or more, as these have high heat resistance. , is preferable for obtaining a polyimide film with excellent mechanical properties.

[B] Representative examples of the aromatic diamine of the component include meta-phenylene diamine, para-phenylene diamine, and 4.4-
-diaminodiphenylpropane, 4.4-diaminodiphenylmethane, 3.3-diaminodiphenylmethane, 4.4- -diaminodiphenyl sulfide, 4.4
- -Diamino diphenyl sulfone, 3.3- -diaminodiphenylsulfone, 3,4''-diaminodiphenylsulfone, 4.4- -diaminodiphenyl ether, 3.3''-diaminodiphenyl ether, 3.4-
Diaminodiphenyl ether, 4.4″-diaminobenzophenone, 3.3-diaminobenzophenone,
2.2--Bis(4-aminophenyl)propane, benzidine 3.3--diaminobiphenyl, 2.6
-diaminopyridine, 2,5-diaminopyridine, 3,
4-diaminopyridine, bis[4-(4-aminophenoxy)phenyl]sulfone, bis(4-(3-aminophenoxy)phenyl)sulfone, bis(4-(4-aminophenoxy)phenyl)ether, bis[4 -(3-
Aminophenoxy)phenyl]ether, 2.2'
-bis[4-(4-aminophenoxy)phenyl]propane, 2.2' -bis(4-(3-aminophenoxy)phenyl)propane, 4.4- -bis(4-aminophenoquine)biphenyl, i , 4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 2.2′-bisC4-(3-
aminophenoxy)phenyl]hexafluoropropane,
Examples include 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, and derivatives thereof. These can be used alone or in a mixture of two or more.

Among these, it is recommended to use para-phenylene diamine, meta-phenylene diamine, and 4.4°-diaminodiphenyl ether alone or in a mixture of two or more as the aromatic diamine to produce a polyimide film with high heat resistance and excellent mechanical properties. preferred in terms of obtaining

[C] acid component, It is expressed by the following formula.

CIH-)(,N NH,・)ICI 14)
]-H,N NH,・HCI\'
\ / A or AC'I'l・H
7N/\NBF"CICIIIH, N/R is 10--C
represents H--CO--3oU] As a representative example, 3.3-. 4.4"-tetraaminodiphenyl ether tetrabasic acid salt, 3.3", 4.4-
Tetraaminodiphenylmethane tetrabasic acid salt, 3.3-.
4.4= -tetraaminobenzophenone◆tetracyclic salt, 3.3-. 4.4= -tetraaminodiphenylsulfone tetrabasic acid salt, 3.3'', 4.4- -tetraminobiphenyl tetrabasic acid salt, 1,2,4.5-tetraminobenzene tetrabasic acid salt , 3,3°, 4-triaminodiphenyl ether dihydrochloride, 3,3°, 4-triaminodiphenylmethane dihydrochloride, 3,3.4-triaminobenzophenone dihydrochloride, 3°3′, 4-triaminodiphenylsulfone dihydrochloride, 3.3°, 4-triaminobiphenyl dihydrochloride, 1.2.4-) riaminobenzene dihydrochloride, and these triamino compounds are dihydrochloride. It may be used in the form of a salt.The above substances exist as hydrates, and they can be used alone or in a mixture of two or more.

Moreover, these compounds may be salts other than hydrochloride, for example, sulfates and the like. When the above-mentioned tetraamino compound and triamino compound do not form a salt, for example,
3. F", 4.4-tetraamino diphenyl ether, 3,3.4.4'-tetraaminobenzophenone, etc. also have the ability to form a three-dimensional network structure of polyamic acid, but when these are used, gel It is preferable to use it in combination as the above-mentioned hydrochloride compound because the time required for the reaction to occur is considerably shortened.

These [A](B)[c) components may be used alone or in combination.
Since it is used in a mixture of more than one species, the resulting polymers include copolymers. In addition, [A
] [B] Polyamic acid solution of EC) and the above [A] (
B) (It is also possible to obtain a gel film of polyamic acid by mixing a polyamic acid solution in which at least one of the components C is different from the above-described one and then gelling the mixture.

The polyamic acid structure consisting of components [A], (B), and [C] is preferably reacted in an organic polar solvent at a temperature range of -10 to +b. The reaction time is within 5 hours, preferably within 2 hours. If the reaction temperature is lower than 110° C., it is not preferable because in addition to the difficulty in handling and the reaction method, the reaction itself may not proceed sufficiently because the temperature itself is too low. If the reaction temperature exceeds 30° C., a gelation phenomenon may occur during generation, and a uniform film may not be obtained.

Therefore, when producing a film from a polyamic acid solution obtained by polycondensing components [A] and [B] and [C], the polyamic acid solution and the substrate for film production, etc., are After controlling the temperature to 10 to +30°C, it is preferable to cast or apply the polyamic acid solution onto the substrate to form a film.

The amount of polyamic acid obtained in the organic solvent used during the reaction is 3 to 40% by weight, preferably 5 to 3% by weight.
From the viewpoint of ease of handling, it is preferable to adjust the content to 0% by weight. If the concentration of polyamic acid is less than 3% by weight, the resulting gel will have poor self-supporting properties, and if it exceeds 40% by weight, the solid content concentration will be too high, resulting in an increase in solution viscosity during polymerization.
Polymerization reactions tend not to proceed as expected.

Therefore, the polyamic acid gel obtained by the reaction is
It is a gel containing 60 to 97% by weight of the total amount of organic polar solvent.

The organic solvent used needs to be inert to the reaction and at the same time dissolve the [A], (B), and [C] components to be reacted. Typical examples include N,N-dimethylformamide, N , N-dimethylacetamide, N
, N-diethylformamide, N,N-diethylacetamide, dimethylsulfoxide, N-methyl-2-viclidone, N,N-dimethylmethoxyacetamide hexamethylphosphoamide, pyridine, dimethylsulfone, tetramethylenesulfone 1, cresyl, phenol, Examples include phenols such as xylenol, benzene, toluene, xylene, benzonitrile, dioxane, and cyclohexane. These solvents may be used alone or in a mixture of two or more.

The molar ratio of [A]/[B]/[C] to be reacted is (
100)/(60-100)/(2-20), particularly preferably (,100)/(
80 to 100)/(4 to 10), but the preferred composition range may vary slightly depending on the type of monomer used.

Generally, when preparing a polyamic acid from a tetracarboxylic dianhydride and an aromatic diamine, it is preferable to react both components in equimolar amounts as much as possible in order to increase the molecular weight, and in the present invention, in order to increase the degree of polymerization, [ A] / [B)
The molar ratio of the components is (100) / (80-100), [
The molar ratio of A]/[B)/[C] is (100)/
In order to keep it within the range of (60 to 100)/(2 to 20) and to adjust the equivalent ratio of the reactive groups of tetracarboxylic dianhydride and amines to within ±5%, 0.95x [(B
(number of moles of)+22(number of moles of C))<(number of moles of A)
It is necessary to set the value to <1.05x [(number of moles of B)+2x(number of moles of C)].

When a 7-mer is blended and reacted with a composition outside this range, that is, (number of moles of A) < 0.95x [(number of moles of B)
+2x (number of moles of C)], the degree of polymerization does not increase, and the properties of the obtained polymer, such as mechanical properties, are also extremely low. Also, (number of moles of A) > 1
．． In the case of 05x [(number of moles of B) + 2 x (number of moles of C)], unreacted monomers will remain in the polymerization solution, which will affect the properties of the film obtained by evaporating and drying the polymer solution. This will have a negative impact. For example, there is a tendency to deteriorate the thermal properties, moisture absorption properties, etc. of the polyimide film finally obtained.

−. The molar ratio of [A]/[B] components is (100)/(
If it is outside the range of 60 to 100), the degree of polymerization of the polymer will not increase and the resulting structure will be incomplete. Furthermore,
If the molar ratio of the [C] acid component to this is less than 2, a three-dimensional network structure will not be formed and so-called gelation will not occur. A preferable molar ratio of component [C] to form a three-dimensional network structure is 2 or more. However, even when the molar ratio of the [C] acid component is less than 2, the apparent viscosity of the polymer solution may be increased and the film-forming ability of the polyamic acid may be significantly improved.

[C] If the molar ratio of the acid component is greater than 20, the number of crosslinking points in the three-dimensional network structure increases, which tends to reduce the film properties of the gel structure and make the film brittle. Therefore, the molar ratio of component [C] is preferably within the range of 2 to 20.

In addition, as the blending ratio of the [C] component increases, the heat resistance of the polyimide resin obtained by the dehydration/cyclization reaction decreases, so preferably the molar ratio of the [C] acid component is 1.
It is below O.

The reaction between [A] (B) and [C] components is the reaction between [A] component and [B]
[C] This is an acid component reaction, and the preparation method is to add the [A] component to a solution in which the CB] [C] component is dissolved in an organic solvent under an inert atmosphere such as nitrogen gas.

[A] Acid component may be added in solid form or in liquid form dissolved in a solvent. [A] Acid component [B] [C] Acid component may be added to a solution dissolved in an organic solvent. In addition, it is possible to add the acid component [C] during the reaction of the component [A] and component B). However, it is possible to add the acid component [C] to the system in which a predetermined amount of component CA) and component (C1) have been reacted in advance. (If a Bll component is added, the reaction may not proceed and gelation may not occur depending on the preparation conditions, so care must be taken.

In addition to components [A], (B), and [C], a small amount of polycarboxylic acid such as trimellitic acid, carboxylic acid anhydride, or a derivative thereof may be included.

In addition, the three-dimensional network structure of polyamic acid may contain other substances other than the solvent, such as various metal compounds, low-molecular organic compounds, polymer compounds, inorganic fillers, colorants, reinforcing fibers, etc. do not have.

Regarding the method of obtaining a polyimide resin by dehydrating and cyclizing polyamic acid, as is generally known, imidization is completed by high temperature treatment or chemical dehydration treatment using a dehydrating agent or the like.

The polyamic acid gel obtained in the present invention is a structure mainly composed of a covalent three-dimensional network structure, and provides a self-supporting gel-like structure at room temperature. When this material is treated at high temperature, a uniform polyimide film can be formed, and as a result, a film with specific performance can be obtained.

In other words, a film that has been imidized while retaining the three-dimensional network structure (gel) of polyamic acid to some extent is thought to have a unique molecular structure at the microscopic level, and mechanical treatments such as film stretching etc. Alternatively, a polyimide film having unique performance can be prepared by preparing a porous coagulated film by replacing the solvent in a coagulation bath.

Regarding the polyamic acid film prepared from components [A], [B], and [C] of the present invention, gelation occurs after the polyamic acid solution is cast onto the substrate, and the total amount of
A self-supporting polyamic acid gel film containing 97Mff1% of an organic polar solvent is obtained. After this polyamic is desolvated at a temperature of 0° C. or lower and under normal pressure or vacuum to adjust the solvent content to 50% by weight or less, preferably 40% by weight or less, the film is subjected to a dehydration/cyclization reaction. Obtaining a polyimide film is preferable because it provides a film with few defects and excellent physical properties.

In addition, a gel-like film of polyamic acid containing a solvent is immersed in a bath containing a poor solvent of polyamic acid as a coagulation bath, and the organic polar solvent remaining in the film is removed by solvent replacement or the film is washed. be able to.

Thereafter, the film is separated from the substrate and subjected to high temperature treatment or chemical treatment to obtain a polyimide film. In this case, water is mainly used as the coagulating liquid, but alcohols such as methanol and ethanol may be included as long as it is not more than 50% by weight of the entire coagulating liquid. Also, if it is 20% by weight or less of the total coagulation liquid, ketones such as acetone, N.

Amide solvents such as N-dimethylacetamide, 1.2-
It may also contain a chlorinated solvent such as dichloroethane. By strengthening the cleaning of the film as described above, it is possible to remove impurities such as chlorine contained in the film.

As a method for proceeding with imidization while maintaining the three-dimensional network structure (gel), a method similar to the imidization method used for general polyimide resins can be used.

For example, when completing imidization by high temperature treatment,
The self-supporting polyamic acid gel film is dried at a temperature of 50 to 200°C for at least 10 seconds, and further dried at a temperature of 150 to 500°C, preferably 200 to 450°C.
Heat treated at high temperature of ℃.

In this case, a film with excellent dimensional stability and mechanical properties can be obtained by fixing both ends of the pair of films with a fixed frame, chuck, binkaide, or the like. This method is effective because polyamic acid gel films shrink particularly when dried or heat treated.

Furthermore, there is a method of chemically dehydrating and cyclizing a film having a three-dimensional network structure (gel) of polyamic acid by immersing it in a dehydrating agent or including it in a dehydrating agent.

In chemical dehydration reactions, it is effective to use acid anhydrides using amines as catalysts.

Examples of acid anhydrides include acetic anhydride, propionic anhydride,
There are aliphatic acid anhydrides such as butyric anhydride and benzoic anhydride. These can be used alone or as a mixture of two or more.

Examples of amines used as catalysts include tertiary amines such as trimethylamine, triethylamine, triethylenediamine, tributylamine, dimethylaniline, pyridine, α-picoline, β-picoline, γ-picoline, isoquinoline, and lutidine. and at least one of these amines.

The amount of acid anhydride added in the chemical dehydration reaction is 1 to 5 equivalents, preferably 1 to 3 equivalents, per equivalent of carboxyl group present in the polyamic acid. The amount of catalyst is 0.0% relative to 1 equivalent of carboxy groups present in the polyamic acid. O1-1.5 equivalents, preferably 0.2-1
It is equivalent.

As described above, a gel film of polyamic acid is prepared from the polymerization reaction solution of [A], [B], and (C). By this, a polyimide film having a microscopically unique molecular structure is prepared.

The polyimide film obtained from the novel polyamic acid gel film of the present invention has a three-dimensional network structure, so it improves the mechanical properties of the film itself and has excellent mechanical strength with both heat resistance and toughness. This provides superior performance.

In particular, polyimides with high heat resistance, such as tetracarboxylic dianhydride such as pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, biphenyltetracarboxylic dianhydride, and aromatic diamines thereof, When parafait is used alone or in a mixed system of two or more types, the film performance is significantly improved due to the formation of a three-dimensional gel structure of polyamic acid by addition of component [C].

In addition, due to the unique molecular structure, depending on the film forming conditions, polyimide resin may repeatedly swell and contract due to the ingress and egress of solvent, or may exhibit functionality such as changing its state due to external stimuli such as temperature. Because it also has excellent heat resistance, it is expected to be applied as a functional polymer with substance separation ability, stimulus-responsive action, catalytic action, etc.

[Examples and comparative examples]

The present invention will be explained below using examples.

Example 1 In a 300 ml four rosetteable flask, 0.0 I
8 mol (1,818 g) of purified paraphenylene diamine (abbreviation: PPD) and 0.0016 mol (0°63
38g) of 3.3-. 4. Collect 4-tetraaminobiphenyl tetracyclic salt trihydrate (abbreviation: TABT), add 50 g of distilled N,N-dimethylacetamide (abbreviation: DMAc), and stir to dissolve. Ta.

Under a nitrogen atmosphere, the temperature of the external water bath was controlled at 5°C, and while stirring the above solution, 0.02 mol (4,366
g) Purified anhydrous pyromellitic dianhydride (abbreviation:
PMDA) was gradually added in a solid state while being careful not to raise the temperature of Hamaki.

After all the PMDA was added, stirring was continued. After a uniform polyamic acid solution was obtained, the polymer solution was cast onto a glass plate. The amount of solution applied was controlled by a spacer. When left standing for a while, the cast polymer solution gelled, and a gel film of polyamic acid was obtained.

The resulting polyamic acid gel film was agar-like and self-supporting.

This polyamic acid gel film was vacuum dried at 30°C, and the solvent content in the film was removed by peeling and 80°C.
After drying in a shoe dryer for IsO minutes at 120℃ and BO minutes at 120℃, it was fixed on an iron frame and continuously dried at 150℃ for 1 hour, 200℃ for 1 hour, 300℃ for 1 hour, and 400℃ for 1 hour. A uniform polyimide film was obtained. The resulting film was reddish brown in color and had a thickness of 50 μm.

When the infrared absorption spectrum of this polyimide film was taken, it was 1780cm 1720c.
A characteristic absorption band of imide groups was observed at II', confirming imidization.

Regarding the properties of this film, the 5% weight loss temperature of the film by thermogravimetric analysis, the glass transition temperature of the film by thermomechanical analysis (TMA), and the tensile properties of the film were evaluated by a material testing machine.

The tensile properties were determined by cutting the obtained polyimide film into strips with a width of 5 mm, and using a chuck distance of 1i30a+a+.

The measurement was carried out under the test conditions of a tensile rate of 5/min. The measurement is 2
It was carried out at 3°C. As shown in Table 1, this film had excellent heat resistance and good mechanical properties.

Comparative Example 1 In four 300 m, l separable flasks, 0°0
Two moles (2,182 g) of purified para-phenylenediamine (abbreviated as diPPD) were collected and 50 g of distilled N
, N-dimethylacetamide (abbreviation = DM Ac
) was added and stirred to dissolve.

Under a nitrogen atmosphere, the temperature of the external water bath was controlled at 5°C, and while stirring the above solution, 0.02 mol (4,368
g) Purified anhydrous pyromellitic dianhydride (abbreviation:
PDMA) was gradually added in a solid state while being careful not to raise the temperature of the solution.

The obtained polymer solution was a viscous liquid, and the intrinsic viscosity at 30°C was 1.6 dL/g. This polymer solution did not gel even after being left at room temperature for 5 hours.

A film was prepared from this polymer under the same conditions as in Example 1, and drying and heat treatment were attempted, but the film became brittle after being dried in a dryer at 120°C for 60 minutes.
It was not possible to process it by fixing it to an iron frame. Also,
The film after high-temperature heat treatment at the free end under the same temperature conditions as in Example 1 was also very brittle, making it impossible to evaluate the glass transition temperature by thermomechanical analysis and the tensile properties of the film by a material testing machine.

Example 2 In a 300 m, 9 x 4 rosemable flask, 001
4 mol (1,513 g) of purified paraphenylenediamine (abbreviation: PPD) and 0.0038 mol (0,720 g)
7 g) of 4.4′-diaminodiphenyl ether and 0
．． 0012 moles (0,4752 g) of 3,3°, 4,4
- Tetraaminobiphenyl tetracyclic salt dihydrate (abbreviation: TABT) was collected, and 50 g of distilled N,N
-Dimethylacetamide (abbreviation: DMAc) was added and stirred to dissolve.

Under a nitrogen atmosphere, the temperature of the external water bath was controlled at 5°C, and while stirring the above solution, 0.02 mol (4,388
g) Purified anhydrous pyromellitic dianhydride (abbreviation:
PMDA) was gradually added in a solid state while being careful not to raise the temperature of the solution.

After that, a polymer solution and a polyimide film were prepared in the same manner as in Example 1, and 0.01
24 mol (1,340 g) of purified paraphenylenediamine (abbreviation: PPD) and 0.0014 mol (0°55
44g) of 3.3°,4,4°-tetraaminobiphenyl tetracyclic salt dihydrate (abbreviation: TABT) was collected, and 30g of distilled N,N-dimethylacetamide (abbreviation: diDMAc) was collected. ) was added and stirred to dissolve.

Under a nitrogen atmosphere, the temperature of the external water bath was controlled at 5°C, and while stirring the above solution, 0.0152 mol (3,3
18 g) of purified anhydrous pyromellitic dianhydride (abbreviation: PMDA) was gradually added in solid form, taking care not to raise the temperature of the solution.

In another 300φ four separable flask, this time 0.004 mol (10,4324 g) of purified metaphenylenediamine (abbreviation: MPD) and 0.0006 mol (0,2376 g) of 3.3' , 4.4°-tetraaminobiphenyl tetracyclic salt trihydrate (abbreviation: TABT
) was collected, and 20 g of distilled N,N-dimethylacetamide (abbreviation: DMAc) was added and stirred to dissolve.

Similarly, under a nitrogen atmosphere, the temperature of the external water bath was controlled at 5°C, and while stirring the above solution, 0.0048 mol (r, 048 g) of purified anhydrous pyromellitic dianhydride (abbreviation: PMDA) was added. was added gradually while being in solid form, being careful not to raise the temperature of the solution.

These two reaction solutions were mixed and stirred while controlling the temperature at 5°C to obtain a homogeneous solution, and then this solution was cast onto a glass plate before gelation occurred. A polyimide film was prepared in the same manner as in Example 1,
Various characteristics were evaluated. The results were as shown in Table 1.

Examples 4 to 8 and Comparative Examples 2 to 6 Various monomers and solvents of the type and amount shown in Table 1 were charged into four 500 ml rosebud flasks, and Example 1
A polymer solution and a polyimide film were prepared in the same manner as in Comparative Example 1, and various properties were evaluated.

The final high temperature heat treatment temperature performed in the preparation of the polyimide film was as shown in Table 1.

In Examples 3 to 8, gelation of the polyamic acid film was confirmed after the prepared polymer solution was cast onto a glass plate and left to stand. Further, regarding the polyimide film after heat treatment, although no large difference in thermal properties was observed compared to the comparative example, the mechanical properties of the film, particularly the tensile strength and elongation, were improved.

Claims (1)

[Claims] (1) Contains the following [A] [B] [C] components [A]/[B]
]/[C] molar ratio is (100)/(60-100)/
(2 to 20) and 0.95x [(number of moles of B)+2x(number of moles of C)]<
(Number of moles of A)<1.05x [(Number of moles of B)+2x(
A polyamic acid gel film having a self-supporting three-dimensional network structure is produced by casting or coating an organic polar solvent solution of polyamic acid (number of moles of C) on a substrate. A method for producing a polyimide film, which comprises peeling the film and subjecting the film to a dehydration and cyclization reaction. [A] Tetracarboxylic dianhydride [B] Aromatic diamine [C] A single compound or a combination of two or more compounds represented by the following formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ or ▲ Numerical formulas, chemical formulas, tables, etc. ▼ [In the formula, A represents ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, R is -O-, - CH_2-, -CO-, -SO_2-] (2) In an organic solvent at a temperature range of -10 to +30°C [A
A polyamic acid solution obtained by polycondensing components [B] and [C] is cast or coated onto a substrate to produce a uniform gel film of polyamic acid, and the film is peeled off from the substrate. The method for producing a polyimide film according to claim 1, wherein the polyimide film is subjected to a dehydration and cyclization reaction. (3) After preparing a gel film of polyamic acid containing 60 to 97% by weight of the total amount of organic polar solvent to a solvent content of 50% by weight or less by removing the solvent, the film is
The method for producing a polyimide film according to claim (1), wherein a dehydration/cyclization reaction is carried out. (4) A gel film of polyamic acid containing 50% by weight or less of an organic polar solvent based on the total amount is fixed at least on both ends of the film, dried at a temperature of 50 to 200°C, and then heat treated at a temperature of 150°C or higher. The method for producing a polyimide film according to claim (1). (5) A gel film of polyamic acid containing 50% by weight or less of the total amount of organic polar solvent is imidized by chemical dehydration treatment using a dehydrating agent such as an organic acid anhydride and a catalyst such as a tertiary amine. The method for producing a polyimide film according to claim 1, wherein the polyimide film is subjected to heat treatment by drying and heating after proceeding. (6) A polyamic acid gel film containing 50% by weight or less of the total amount of organic polar solvent is immersed in a coagulation bath containing at least water, the film is coagulated and peeled off from the substrate, and then dried and heated. Claim (1) for heat treatment
) The method for producing the polyimide film described in ). (7) A claim in which the tetracarboxylic dianhydride of component [A] is pyromellitic dianhydride, benzophenonetetracarboxylic dianhydride, or biphenyltetracarboxylic dianhydride alone or in a mixture of two or more thereof. (1) A method for producing a polyimide film as described. (8) A claim in which the aromatic diamine of component [B] is one or a mixture of para-phenylene diamine, meta-phenylene diamine, and 4,4'-diaminodiphenyl ether (
1) The method for producing the polyimide film described above.