JPH09227697A - Preparation of heat-resistant polyimide film through gel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for preparing a heat-resistant polyimide film through a gel using a polyamidic acid solution which can stably control, for a long period of time, the viscosity of a polyamidic acid soln. having a capability of forming a gel upon a three-dimensional crosslinking reaction and enables the soln. to be stably applied onto a substrate. SOLUTION: A polyamidic acid soln. having a capability of forming a gel upon a three-dimensional crosslinking reaction is applied onto a substrate in an inert gas atmosphere at a temp. of -10 deg.C or below. The resultant coating of the polyamidic acid soln. is heated to form a self-supporting polyamidic acid gel film on the substrate. Subsequently, an org. solvent contained in the polyamidic acid gel film is removed, followed by heat treatment to conduct imidation. Pref., the polyamidic acid soln. is stored at a temp. of -10 deg.C or below.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for continuously producing a heat-resistant film mainly having a polyimide film which is excellent in heat resistance and is widely used in the fields of electronics, transportation equipment, aerospace and the like. Specifically, a film is prepared via a polyamic acid that gives a three-dimensional network structure, a so-called gel-like structure, in the state of the polyamic acid that is a precursor of polyimide, and further dehydration / cyclization reaction mainly involving heat treatment. The present invention relates to a method for producing a novel polyimide film having excellent heat resistance and mechanical properties by completing imidization of the film.

[0002]

2. Description of the Related Art Polyimide has excellent heat resistance, abrasion resistance, chemical resistance, electrical insulation, and mechanical properties,
It is widely used in electronic materials, adhesives, paints, composite materials, fibers and film materials. Among them, the polyimide film has various applications due to its excellent properties as a covering material for electric wires, cables, wires, etc., and an insulating material for transformers, printed wiring boards, etc.

The polyimide is prepared by using a polyamic acid obtained by polycondensing a tetracarboxylic dianhydride and an aromatic diamine in an organic solvent as a precursor, and dehydrating by heating or by a chemical reaction with a dehydrating agent. It is general to proceed with cyclization to obtain a polyimide, and this method is known and many patent applications have been filed.

The method for producing a polyamic acid which is a precursor of polyimide is carried out by reacting a tetracarboxylic dianhydride and an aromatic diamine in an organic solvent at a reaction temperature of 0 to 30 ° C. so that the polymer concentration becomes 5 to 20% by weight. The method of polyaddition reaction is generally used. By this method, a high molecular weight polyamic acid solution uniformly dissolved in an organic solvent can be obtained. This polyamic acid solution is applied to a base material or the like under a temperature atmosphere of at least room temperature or discharged from a die, and becomes a molded body of a film or fiber of polyamic acid by desolvation, and is used as a precursor of a polyimide molded body. Further, it is a usual method to carry out dehydration / ring-closing reaction of this molded product by high temperature treatment or chemical treatment to obtain a polyimide molded product. For example, JP-A-61-178834 and JP-A-61-78834.
No. 181828, No. 61-250031, No. 63-25413, etc.

Among these polyimides, it is possible to obtain a molded product such as a film having high mechanical properties, depending on the combination type of tetracarboxylic dianhydride and aromatic diamine to be polycondensed. The film obtained from a combination of pyromellitic dianhydride and 4,4'-diaminodiphenyl ether as a polyimide is a type having high heat resistance and excellent tensile properties.

However, in general, when trying to increase the heat resistance, the film tends to become brittle, and the heat resistance and the mechanical properties tend to contradict each other. In particular, a polyimide obtained by combining pyromellitic dianhydride and para-phenylenediamine has the highest level of heat resistance and tensile elastic modulus in physicochemical heat resistance, but is poor in film performance due to brittleness. In particular, it is completely inferior in mechanical properties. In this type of polyimide, it has been attempted to improve the mechanical properties of the polyimide film by a copolymerization technique without lowering the heat resistance.

For example, as shown in JP-A-63-254131, in a combination system of pyromellitic dianhydride and paraphenylenediamine, 4,4'-diaminodiphenyl ether is used as another aromatic diamine. Although there are some examples of polymerization, when the amount of 4,4'-diaminodiphenyl ether component added to improve the film-forming ability is increased, the heat resistance of the film may be lowered, resulting in heat resistance. It was not easy to obtain a film having both excellent mechanical properties and mechanical properties.

In recent years, a polycarboxylic acid having a specific blending ratio is added to a reaction system of tetracarboxylic dianhydride and an aromatic diamine to cause a polyaddition reaction to form a polyamic acid molded article via a polyamic acid gel. Further, there is a method for obtaining a polyimide molded body by subjecting this to dehydration / ring-closing reaction.
-109424 and 03-146524. In this method, a three-dimensional network structure is developed by the presence of appropriate crosslinking points, and finally a polymer system having excellent heat resistance, mechanical properties and chemical resistance of polyimide is prepared. This method is unique in that it passes through a polyamic acid gel, and is one of the methods particularly effective for modifying a polyimide system in which pyromellitic dianhydride and paraphenylenediamine are combined.

However, in the method for obtaining a molded product of a polyamic acid and further a molded product of a polyimide via the gel of the polyamic acid, the polyamic acid solution hardly flows after the gel formation is completed, so that the film is not formed. There is an inconvenience that it is not possible to shape a molded product having a complicated shape such as a fiber or a fiber with good quality.

Therefore, at present, the solution of a viscous amic acid oligomer or polymer before gelation is applied onto a substrate or extruded from a die, gelation is completed after shaping, and drying with hot air is subsequently carried out to finally finish. Generally, a molding process for forming a molded body such as a film is mainly adopted.

However, in the method of completing the gelation after the shaping, the operation at around room temperature is mainly used, and the gelling of the polymer solution from the polyamic acid oligomer or polymer solution is completed in a relatively short time and the subsequent treatment is performed. Since the shape becomes difficult, it was very difficult to produce a molded product having a uniform quality with respect to sequential changes in viscosity of the polyamic acid solution until gelation. In addition, there are many problems such as the need to improve the existing equipment and technology in the method of storing the oligomeric or polymer solution of amic acid obtained by this reaction and the method of removing impurities in the polyamic acid solution by the filter. It was

[0012]

Therefore, according to the present invention, it is possible to stably control the viscosity of a polyamic acid solution having a gel-forming ability by a three-dimensional crosslinking reaction for a long time,
An object of the present invention is to provide a method for producing a heat-resistant polyimide film via a gel, which uses a polyamic acid solution that can be applied to a substrate in a stable state.

[0013]

Means for Solving the Problems The present inventors have found that a reaction solution obtained by reacting monomers containing tetracarboxylic dianhydride, aromatic diamine and polyvalent amine as main components in an organic solvent is , Controlling the polymerization conditions such as the reaction temperature before forming the polymer gel (molecular chain) by paying attention to the fact that the change in viscosity with time at a low temperature of −10 ° C. or less is stable, Moreover, a method for obtaining a polyimide film having excellent heat resistance and mechanical properties, which allows continuous production of a good quality polyimide film, has been reached.

The present invention adopts the following constitution for solving the above-mentioned problems.

In the method for producing a heat-resistant polyimide film of the present invention, a polyamic acid solution having a gel-forming ability by a three-dimensional crosslinking reaction is applied on a substrate at a temperature of -10 ° C or lower in an inert gas atmosphere, Then, the applied polyamic acid solution is heated to form a self-supporting polyamic acid gel film on the substrate, and subsequently the organic solvent in the polyamic acid gel film is removed, and further heat treatment is performed to perform imidization. Is characterized by.

According to the present invention, in the above method for producing a heat-resistant polyimide, a polyamic acid solution capable of forming a polymer gel by a three-dimensional cross-linking reaction is stored in an inert gas atmosphere at a temperature of -10 ° C or lower and solid. 5 to 30 minutes
It is characterized by using a resin whose weight% and apparent viscosity are maintained at 1 to 5000 poise.

In the present invention, in the method for producing a heat resistant polyimide, the applied polyamic acid solution is heated to
The method for producing a heat-resistant polyimide film according to claim 1, wherein the method of forming a polyamic acid gel film having self-supporting properties on a substrate is performed in an inert gas atmosphere.

According to the present invention, in the above method for producing a heat-resistant polyimide, the method of removing the organic solvent in the polyamic acid gel film is performed by blowing hot air at a temperature not exceeding 200 ° C. onto the polyamic acid gel film on the substrate. It is characterized by

According to the present invention, in the above method for producing a heat-resistant polyimide, the method for imidizing is to peel off the polyamic acid gel film from the substrate and drive at least one of both edges of the polyamic acid gel film. It is characterized in that the polyamic acid film is imidized while being continuously run by bringing it into contact with a pinned belt.

The present invention is characterized in that in the above method for producing a heat resistant polyimide, the heat treatment temperature for imidization is within a range not exceeding 500 ° C.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION A polyamic acid solution capable of forming a polymer gel by a three-dimensional crosslinking reaction is typically a monomer containing tetracarboxylic dianhydride, aromatic diamine and polyvalent amine as main components. Manufactured from.

Under an inert atmosphere such as nitrogen gas, -1
Used in the present invention by gradually adding tetracarboxylic acid dianhydride to a high molecular weight while stirring in a solution prepared by dissolving an aromatic diamine and a polyvalent amine in an organic solvent at a temperature of 0 ° C. or lower. A polyamic acid solution is prepared. The tetracarboxylic acid dianhydride may be added in a solid form or in a liquid form dissolved in a solvent. A method in which an aromatic diamine and a polyvalent amine are added to tetracarboxylic dianhydride may be used.

Typical examples of the tetracarboxylic dianhydride used in the present invention include pyromellitic dianhydride, 3,
3 ', 4,4'-benzophenone tetracarboxylic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride , 2,2 ', 3,3'-biphenyltetracarboxylic dianhydride, 2,2', 6,6'-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic acid Dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride,
Bis (3,4-dicarboxyphenyl) sulfone dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, naphthalene-1, 2,4,5-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride and the like. Further, tetracarboxylic dianhydride or fluorine having a relatively large molecular weight in which amide group, ester group, ether group, sulfone group, methylene group, propane group, phenylene group, imidazole group, thiazole group and the like are arbitrarily combined in the molecule. A tetracarboxylic dianhydride containing a halogen group in its structure can also be used. Further, terephthalic acid dichloride, isophthalic acid dichloride, pphenylcarboxylic acid dichloride, and acyl halide derivative of aromatic tricarboxylic acid anhydride can also be used. These can be used alone or as a mixture of two or more kinds.

Typical examples of aromatic diamines to be reacted with tetracarboxylic dianhydride include metaphenylenediamine, paraphenylenediamine, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylmethane, 3,3 '. -Diaminodiphenylmethane, 4,4'-
Diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 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-aminophenoxy) biphenyl, 1,
4-bis (4-aminophenoxy) benzene, 1,3-
Bis (4-aminophenoxy) benzene, 2,2′-bis [4- (3-aminophenoxy) phenyl] hexafluoropropane, 1,5-diaminonaphthalene, 2,6-
Examples thereof include diaminonaphthalene and derivatives thereof. Further, dihydrazide compounds such as isophthalic acid dihydrazide can also be used. These can be used alone or as a mixture of two or more.

The polyvalent amine used in the present invention refers to a compound having three or more amino groups and / or ammonium groups in one molecular structure.

Typical examples of polyamines include 3,3 ',
4,4'-tetraaminodiphenyl ether, 3,
3 ', 4,4'-tetraaminodiphenylmethane, 3,
3 ', 4,4'-tetraaminobenzophenone, 3,
3 ', 4,4'-tetraaminodiphenyl sulfone,
3,3 ', 4,4'-tetraaminobiphenyl, 1,
2,4,5-Tetraaminobenzene, 3,3 ', 4-triaminodiphenyl ether, 3,3', 4-triaminodiphenylmethane, 3,3 ', 4-triaminobenzophenone, 3,3', 4- Triaminodiphenyl sulfone, 3,3 ′, 4-triaminobiphenyl, 1,2,4
-Triaminobenzene and compounds in which the functional groups of these compounds are converted into the form of quaternary ammonium salts, for example 3,
3 ', 4,4'-tetraaminobiphenyl tetrahydrochloride and the like can be mentioned. The quaternary ammonium salt may be used in the form of acetate, p-toluenesulfonate, picrate, etc., in addition to the hydrochloride. Some of these compounds also include those in which all of the polyamine functional groups are not in the quaternary ammonium salt form. Further, some of the above substances exist as hydrates, and these polyvalent amines can be used alone or as a mixture of two or more kinds. It is also possible to use aliphatic polyamines.

In the present invention, the molar ratio of tetracarboxylic dianhydride / aromatic diamine / polyvalent amine is set to 100/50 in order to control the molecular weight between crosslinking points of the polyamic acid molecular chain and the degree of crosslinking to cause gelation. To 100/1 to 25, and the equivalent ratio of the reaction groups of tetracarboxylic dianhydride and amines (aromatic diamine and polyvalent amine) (acid value /
Amine ratio) within the range of 0.95 to 1.05 (± 5%
It is preferable to adjust the ratio to the above) in order to obtain a stable polyamic acid gel with few unreacted terminal groups.

When the monomers are mixed and reacted in a composition outside this range, the three-dimensional cross-linking reaction of the polyamic acid is incomplete, the resulting polyamic acid does not form a gel, and the polyamic acid does not form a gel. Even if a gel is obtained, it becomes inhomogeneous or unstable, and finally the desired properties of the film, for example, physical properties such as tensile strength and tensile elastic modulus of the film are different, which is not preferable.

The molar ratio of tetracarboxylic dianhydride / polyvalent amine to be reacted is preferably 100 / (1 to 25), particularly preferably 100 / (2 to 15), Depending on the type of monomer used, the suitable composition range may be slightly shifted.

The polyvalent amine functions as a cross-linking point of the polyamic acid gel, and changes the network concentration (crosslinking density) existing in the polyamic acid gel depending on the blending amount. The number of moles of the polyvalent amine compounded is 100% of tetracarboxylic dianhydride.
If it is less than 1 mol per mol, the number of cross-linking points of the polyamic acid component in the solution will be small, the three-dimensional network structure will be incomplete, and a self-supporting polymer gel (swollen body) will be difficult to form. If the blending mole number of the polyvalent amine is more than 25 moles, the crosslinking points of the three-dimensional network structure are increased and the molecular weight between the crosslinking points is decreased, and the volume swelling degree of the polyamic acid gel is reduced, resulting in a brittle polymer. It becomes a gel and finally reduces the performance of the film obtained by desolvation. Therefore, the number of moles of the polyvalent amine compounded is 10% of tetracarboxylic dianhydride.
It is preferably in the range of 1 to 25 mol with respect to 0 mol.

The organic solvent used in the polymerization of the polyamic acid containing tetracarboxylic dianhydride, aromatic diamine and polyvalent amine as the main components is inert to the polymerization reaction and, at the same time, the monomers and The one having the ability to dissolve the high molecular weight substance containing the oligomer produced by the reaction or swell the high molecular weight substance is used, and representative ones are N, N-dimethylformamide, N, N
-Dimethylacetamide, N, N-diethylformamide, N, N-diethylacetamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, N, N-dimethylmethoxyacetamide, hexamethylphosphoamide, pyridine, dimethyl sulfone, tetramethylene sulfone ,
Phenols such as cresol, phenol, and xylenol, and benzene, toluene, xylene, benzonitrile, dioxane, cyclohexane, and the like can be given. These solvents are used alone or in combination of two or more.

The total monomer concentration during polyamic acid polymerization is usually 5 to 30% by weight, preferably 10% by weight of the total solvent.
-20% by weight.

When the monomer concentration is less than 5% by weight, the degree of polymerization is low and the mechanical strength of the final film tends to be lowered, which is not preferable. When the monomer concentration exceeds 30% by weight, the film forming processability is impaired due to an increase in solution viscosity with an increase in the degree of polymerization, and it is difficult to obtain a uniform film of good quality.

Polymerization of a polyamic acid containing tetracarboxylic dianhydride, aromatic diamine and polyvalent amine as main components is carried out in an organic solvent, preferably under a temperature condition of -30 to 30 ° C, particularly preferably -20 to 20 ° C. The reaction is carried out in the temperature range of 20 ° C. The reaction time varies depending on the reaction temperature, but is 10 hours or less, preferably 5 hours or less. The reason for adopting the reaction temperature is that when the reaction temperature is lower than -30 ° C,
In addition to the difficulty in handling and the reaction method, the reaction itself may not proceed sufficiently because the temperature is too low, which is not preferable. When the reaction temperature is higher than 30 ° C., the decomposition of the monomer is accelerated, which makes it difficult to form a high molecular weight compound, or the reaction until gelation is too fast, resulting in a non-uniform swollen body. There is not preferable.

These tetracarboxylic dianhydrides, aromatic diamines and polyvalent amine components are used alone or as a mixture of two or more kinds, and thus the polyamic acid obtained includes those of copolymers. Further, a polyamic acid mixture in which a polyamic acid composed of a specific component and a polyamic acid in which at least one of the constituent components of the polyamic acid is different are mixed is also included.

Various other components can be mixed with the reaction solution mainly containing tetracarboxylic dianhydride, aromatic diamine and polyvalent amine. Examples of the third component to be mixed with the polyamic acid include low molecular weight organic compounds, inorganic substances, metal compounds, polymer compounds and the like.

In the molded product obtained from the polyamic acid solution of the present invention, substances other than the solvent, such as various metal compounds, low molecular weight organic compounds, polymer compounds, inorganic fillers, colorants, Reinforcing fibers and the like can be included.

Further, in the reaction system using terephthalic acid dichloride, isophthalic acid dichloride, biphenylcarboxylic acid dichloride, and an acyl halide derivative of an aromatic tricarboxylic acid anhydride, the above reaction conditions are similarly applied.

The resulting reaction solution had an apparent viscosity of 1
It is a uniform solution of ~ 5000 poise, and it is desirable to cool it immediately and store it at a low temperature of -10 ° C or lower in order to prevent gelation of the solution. By storing the reaction solution under this temperature condition, the reactivity (gelation) is suppressed, the solid content concentration of the reaction solution is 5 to 30% by weight, and the apparent viscosity is 1 to 5
It can be maintained at 000 poise for a long time. For the storage of the reaction solution, in addition to the above temperature conditions, an inert gas atmosphere is desirable in order to prevent decomposition of the monomer due to hydrolysis or the like. Further, stirring may be added in order to prevent the reaction solution from becoming non-uniform during storage.

Since the reaction solution contains unreacted monomers, impurities, air during stirring, etc., it is necessary to filter and defoam the reaction solution before processing it into a film. The reaction solution may be filtered / defoamed in the same manner as the filtration / defoaming of a usual polymer solution, for example, by using a filter or a mesh. At this time, in order to suppress gelation, -10 It is desirable to carry out in an atmosphere of ℃ or less.

To this reaction solution, an additive for accelerating the imidization reaction, such as a tertiary amine or an acid anhydride, is added in an amount of 0.5 mol or less per 1 mol of the amide group of the polyamic acid. be able to. Examples of the tertiary amine include triethylamine, pyridine, isoquinoline and the like.
Acid anhydrides include acetic anhydride, propionic anhydride, benzoic anhydride and the like.

The reaction solution thus obtained was -1
A film is continuously formed by applying a casting method such as a doctor blade method or a coating method such as an extrusion method from a die onto a substrate at a constant thickness in an atmosphere of an inert gas such as nitrogen gas at 0 ° C or less. To mold. By applying the reaction solution to the base material at −10 ° C. or lower, the change in viscosity can be controlled, and a stable reaction solution can be applied. Further, by applying the reaction solution to the base material in an inert atmosphere such as nitrogen gas, hydrolysis of the monomer in the reaction solution can be prevented.

The atmosphere in which the three-dimensional cross-linking reaction of the reaction solution coated on the substrate is continuously performed is carried out under an atmosphere of an inert gas such as nitrogen gas in order to prevent mixing of water and hydrolysis of the monomer. Is desirable. Under this inert gas atmosphere, the temperature is raised to 10 to 80 ° C. to promote the three-dimensional crosslinking reaction of the reaction solution to obtain a polymer gel having a film-like self-supporting property and an apparent viscosity of 1,000 to 100,000 poises. Then, hot air having a temperature of 50 to 200 ° C. is blown in the drying furnace to remove the organic solvent in the polymer gel to obtain a solid polyamic acid film. When the drying temperature is higher than 200 ° C., imidization due to dehydration / ring-closing reaction of the polyamic acid component is likely to proceed, a shape change due to shrinkage is caused, and a phenomenon such as curling or wrinkling which impairs the film appearance is unfavorably caused. On the other hand, if the temperature is lower than 50 ° C., it takes a long time to dry and the productivity is lowered, which is not preferable.

The polyamic acid film dried at a temperature not exceeding 200 ° C. has a volatile component reduced to 50% by weight or less based on the whole film. Subsequently, the dried polyamic acid film was peeled off from the base material, and at least one of both edges of the polyamic acid gel film was brought into contact with a belt with a pin being driven to continuously run the polyamic acid film, and continuously. 50-200 ℃
And then heat-treated at a temperature of 150 to 500 ° C. for imidization to obtain a polyimide film.
Desirably, the imidization treatment is performed on both edges of the polyamic acid gel film by fixing them with a belt having two pins so as to obtain dimensional stability in the width direction of the film. Can be obtained.

In the drying and heat treatment in the imidization step, the polyamide acid film is brought into contact with the belt with pins to run the polyimide film, whereby the polyimide film can be continuously produced.

The rate of temperature rise during the heat treatment in the imidization step can be changed depending on factors such as the type of polymer, heat treatment temperature / time and productivity, but is usually 0.2 ° C.
/ Sec or more and less than 500 ° C / sec. 50 to 200
The drying time at ° C is preferably 1 to 60 minutes. 150 ℃ ~
The heat treatment time at 500 ° C. is preferably 1 to 120 minutes, more preferably 2 to 60 minutes. The film production rate is preferably 0.1 to 20 m / min, more preferably 0.2 to 10 m / min.

Since the polyimide film obtained through the polyamic acid gel through the above treatment steps has a cross-linking point due to a polyfunctional monomer and has a three-dimensional network structure, it has a molecular structure. The heat resistance is high and the mechanical properties are superior to those of polyamic acid that does not pass through a gel. It is also possible to control the state of molecular chain aggregation in the film by controlling the network structure.

The heat-resistant polyimide film of the present invention may contain other resins for the purpose of imparting desired and desired properties. The mixture of other resins may be added at any time during the production stage of the polyimide film.

The heat-resistant polyimide film obtained by the production method of the present invention is a material for electronics such as semiconductor elements and conversion elements, which is required to have high heat resistance and mechanical properties, separation film, insulating film, photoconductor, etc. It is useful as a material.

[0050]

【Example】

[Example 1] 9.080 g in a 500 cc polymerization container
(0.084 mol) of purified paraphenylenediamine (abbreviation: PPD) and 3.168 g (0.008 mol) of 3,3 ', 4,4'-tetraaminobiphenyl tetrahydrochloride dihydrate (Abbreviation: TABT) was collected and 50 g of distilled N-methyl-2-pyrrolidone (abbreviation: NMP)
Was added, stirred and dissolved to obtain a solution.

Under a nitrogen gas atmosphere, the temperature of the external water tank is set to 5
21. While controlling the temperature to 0 ° C. and being careful to keep the temperature of the solution from rising, 21.
83 g (0.100 mol) of purified anhydrous pyromellitic dianhydride (abbreviation: PMDA) was gradually added as a solid. After all the additions were completed, stirring was continued to prepare a uniform polyamic acid solution.

The concentration of the polyamic acid solution was 12% by weight, and the solution viscosity at -20 ° C measured by a rotational viscometer was 30.
It was 0 poise. The solution viscosity at −20 ° C. after 5 hours was 350 poise and the change in viscosity was small.

The polyamic acid solution cooled to -20 ° C. was then continuously supplied to a coating apparatus (coater) cooled to -20 ° C. under a nitrogen gas atmosphere, and a stainless belt whose surface was polished from the coater section. The polyamic acid solution was continuously coated on the top to a constant thickness. The width of the coating was 200 mm and the thickness was 250 μm.

The polyamic acid solution gelled until the temperature of the continuously coated polyamic acid coating film was raised to 100 ° C., resulting in an agar-like polyamic acid gel film. Take out a part of this gel film, 2
The apparent viscosity measured at 5 ° C was 5800 poise.

This gel film was continuously passed through a hot air drying oven and dried at 100 ° C. for 30 minutes to remove the solvent. The desolvated gel film solidified and became a strong film, so it was peeled from the substrate to give a polyamic acid continuous film. Then, fix both edges of the film with a pin type tenter, and pass through a heat treatment furnace for 20 minutes at 150 ° C., 15 minutes at 200 ° C., 10 minutes at 300 ° C.
Imidization was completed by heat-treating stepwise at 400 ° C. for 10 minutes and 450 ° C. for 20 minutes to obtain a polyimide film. The thickness of the obtained polyimide film was 25 μm.

[0056] The infrared absorption spectrum of the resulting polyimide film, 1780 cm ^-1, characteristic absorption of an imide group in 1720 cm ^-1 was observed, it is a polyimide film was confirmed. When the film was subjected to thermomechanical analysis while applying a tensile load, an inflection point of the thermal expansion curve which was considered to correspond to the glass transition temperature was observed at 450 ° C., and the linear expansion coefficient at 100 ° C. was 1.0 × 10. ^-6 cm / c
It was m / ° C.

A polyimide film was cut into a strip shape with a width of 5 mm, and a tensile test of the film was performed.
mm and a pulling rate of 5 mm / min at 23 ° C. The tensile strength of the film is 22 kgf / mm ² , the tensile elastic modulus is 1080 kgf / mm ² , and the tensile elongation is 5.
It was 0%.

[Comparative Example 1] Polyamic acid was polymerized under the same reaction conditions using the same monomers and solvents as those in Example 1 to prepare a uniform polyamic acid solution as in Example 1.

This polyamic acid solution was continuously transferred to a container cooled at 0 ° C. in a closed system and stored under a nitrogen gas atmosphere with stirring.

The concentration of this polyamic acid solution is 12% by weight.
The viscosity before storage in the container was 230 poise at 0 ° C. with a rotary viscometer. After storage for 3 hours in a container, this polyamic acid solution gelled and became agar-like. Since the polyamic acid gel did not flow, the polyamic acid gel could not be applied to the surface of the base material by an ordinary coating device, and a film could not be produced.

Example 2 6.89 (0.06 mol) of purified PPD was collected in a 1000 cc four-necked separable flask, and 300 g of distilled N, N-dimethylformamide (abbreviation: DMF) was stirred and dissolved.

Under a nitrogen gas atmosphere, the temperature of the external water tank is set to 0.
The temperature is controlled to be 17.6 ° C., and the solution is stirred for 17.6.
4 g (0.06 mol) of purified 3,3 ', 4,4'-
Biphenyl tetracarboxylic dianhydride (abbreviation: BPD
A) was solidly added gradually while being careful not to raise the temperature of the solution, to prepare a uniform polyamic acid solution. 400 g of distilled N, N-dimethylacetamide (abbreviation: DM) was added to the polyamic acid solution in the flask.
Ac) was added, followed by 10.81 g (0.10 mol) of purified PPD and 7.92 g (0.02 mol) of TABT.
Was added and stirred to dissolve.

Similarly, under a nitrogen gas atmosphere, the temperature of the external water tank is controlled to 0 ° C., and 30.56 while stirring.
g (0.14 mol) of purified PMDA as a solid,
The solution was gradually added, taking care not to raise the temperature of the solution. After all the additions were completed, stirring was continued until the solid content was dissolved.

The reacted polyamic acid solution was filtered and
After defoaming, the mixture was cooled to -25 ° C over 30 minutes and stored under a nitrogen gas atmosphere with stirring.

The concentration of the polyamic acid solution was 12% by weight, and the solution viscosity at −25 ° C. measured by a rotational viscometer was 80.
It was 0 poise. The solution viscosity at -25 ° C after 5 hours was 880 poise, and the change in viscosity was small.

The polyamic acid solution cooled to -25 ° C. was then continuously supplied to a coating device (coater) cooled to -25 ° C. in a nitrogen gas atmosphere, and the stainless belt whose surface was polished from the coater part. The polyamic acid solution was continuously coated on the top to a constant thickness. The width of the coating was controlled to 500 mm and the thickness was controlled to 500 μm.

By the time the temperature of the continuously coated polyamic acid coating film was raised to 50 ° C., the polyamic acid solution gelled and became an agar-like polyamic acid gel film. A part of the gel film was taken out and the apparent viscosity measured at 25 ° C. was 7500 poise. This gel film is continuously passed through a hot-air drying oven and heated at 150 ° C for 20
After drying for a minute, the solvent was removed. The desolvated gel film solidified and became a strong film, which was peeled from the substrate to obtain a polyamic acid continuous film. Then, fix both edges of the film with a pin type tenter, pass through a heat treatment furnace, 200 ° C. for 20 minutes, 300 ° C. for 10 minutes, 4
Imidization was completed by stepwise heat treatment under conditions of 00 ° C. for 10 minutes and 430 ° C. for 10 minutes to obtain a polyimide film. The thickness of the obtained polyimide film was 45 μm.

[0068] The infrared absorption spectrum of the resulting polyimide film, 1780 cm ^-1, characteristic absorption of an imide group in 1720 cm ^-1 was observed, it is a polyimide film was confirmed. When the thermomechanical analysis of the film was performed while applying a tensile load, an inflection point of the thermal expansion curve which is considered to correspond to the glass transition temperature was observed at 440 ° C.,
The linear expansion coefficient at 100 ° C is 1.5 × 10 ^-6 cm / cm /
° C.

A polyimide film was cut into a strip shape with a width of 5 mm, and a tensile test of the film was performed.
mm and a pulling rate of 5 mm / min at 23 ° C. The tensile strength of the film is 28 kgf / mm ² , the tensile elastic modulus is 980 kgf / mm ² , and the tensile elongation is 15%.
Met.

Example 3 10.81 g (0.10 mol) of purified PPD and 12.01 g (0.06 mol) of purified 4,4'-in a 1000 cc four-necked separable flask. Diaminodiphenyl ether (abbreviation: 4,
4'-DPE) and 7.92 g (0.02 mol) TA
BT was collected and 546 g of distilled NMP was added and stirred to dissolve.

Under a nitrogen gas atmosphere, the temperature of the external water tank is set to 0.
The temperature was controlled to 4 ° C, and the solution was stirred at 43.6.
6 g (0.20 mol) of purified PMDA was added slowly as a solid, taking care not to raise the temperature of the solution. After all the additions were completed, stirring was continued to prepare a uniform polyamic acid solution. -20 this polyamic acid solution
It was continuously transferred to a container cooled to 0 ° C in a closed system and stored under a nitrogen gas atmosphere with stirring.

On the other hand, a commercially available polyetherimide resin (G
74.40 g of Ultem (manufactured by Company E) was taken and dissolved in 174 g of distilled NMP in a 500 cc beaker.
After the polyetherimide resin was completely dissolved, this solution was continuously transferred to a container in which the above polyamic acid solution consisting of PMDA / PPD / TABT was stored in a closed system, and stirring was continued under a nitrogen gas atmosphere to homogenize the solution. A polyamic acid / polyetherimide resin mixed solution was obtained.

The concentration of the polyamic acid / polyetherimide resin mixed solution was 17% by weight, and the solution viscosity at −20 ° C. measured by a rotary viscometer was 1200 poise. 5
After a lapse of time, the solution viscosity at −20 ° C. was 1400 poise and the change in viscosity was small.

The polyamic acid / polyetherimide resin mixed solution cooled to -20 ° C. was placed under a nitrogen gas atmosphere-2.
The polyamic acid solution was continuously supplied to a coating device (coater) cooled to 0 ° C., and continuously coated with a uniform thickness on a stainless belt whose surface was polished from the coater section. The width of the coating is 300mm and the thickness is 400μ
Controlled to m.

The mixed solution gelled until the coating film of the continuously coated mixed solution was heated up to 100 ° C. at an average heating rate of 10 ° C./min. It became a composite gel film of ether imide resin. A part of this gel film was taken out and the apparent viscosity measured at 25 ° C. was 7500 poise.

The gel film was continuously passed through a hot air drying oven and dried at 130 ° C. for 20 minutes to remove the solvent. The desolvated gel film solidified and became a strong film, which was peeled off from the substrate to obtain a polyamic acid / polyetherimide resin composite film. Continued
Fix both edges of the film with a pin type tenter, and pass through a heat treatment furnace at 200 ° C for 20 minutes, 300 ° C for 10 minutes,
Heat treatment was carried out stepwise at 400 ° C. for 20 minutes to complete imidization to obtain a polyimide / polyetherimide resin composite film. The thickness of the obtained composite film is 50.
μm. Although this composite film was opaque, it was relatively uniform and had a good appearance without macroscopically showing a large phase separation structure.

When the film was subjected to thermomechanical analysis while applying a tensile load, an inflection point of the thermal expansion curve, which is considered to correspond to the glass transition temperature at 380 ° C., was observed.
The coefficient of linear expansion at ° C was 2.5 x 10 ^-5 cm / cm / ° C.

A composite film of polyimide / polyetherimide resin was cut into a strip shape with a width of 5 mm, and the film was subjected to a tensile test by a chuck distance of 30 mm and a tensile speed of 5 m.
It was performed at 23 ° C. under the condition of m / min. The tensile strength of the film is 18 kgf / mm ² , and the tensile elastic modulus is 380 kgf.
/ Mm ² , and the tensile elongation was 25%.

Comparative Example 2 TAB in the above Example 3
The amount of purified 4,4′-DPE was adjusted to 10.
A homogeneous polyamic acid / polyetherimide resin mixed solution was obtained in the same manner as in Example 3 except that the amount was changed to 03 g (0.0996 mol).

The concentration of the polyamic acid / polyetherimide resin mixed solution was 17% by weight, and the solution viscosity at −20 ° C. measured by a rotary viscometer was 5600 poise. 5
The solution viscosity at −20 ° C. after the lapse of time was 5600 poise and there was no change in viscosity.

Films were continuously produced by a coating apparatus (coater) in the same manner as in Example 3 above. Even if the coating film of the mixed solution continuously coated at -20 ° C was heated to 100 ° C, the mixed solution did not gel. Subsequently, a polyamic acid / polyetherimide resin composite film obtained by drying and heat treatment in the same manner as in Example 3 had a macroscopically large phase-separated structure on the surface and had a poor appearance. The tensile strength of the film measured in the same manner as in Example 3 was 15 kgf / mm ² , the tensile elastic modulus was 350 kgf / mm ² , and the tensile elongation was 25%.
And the mechanical properties were inferior to those of Example 3.

[0082]

According to the method for producing a heat-resistant polyimide film of the present invention, a polyamic acid solution having a gel-forming ability by a three-dimensional crosslinking reaction is treated in an inert gas atmosphere at -10
Since it is applied on the substrate at a temperature of ℃ or less and imidized via the polymer gel, the polyamic acid solution can be applied in a state where the viscosity is stably controlled, and the resulting heat-resistant polyimide film has a high quality. Will be stable,
It also has excellent mechanical properties.

In the imidization treatment in the method for producing a heat-resistant polyimide film of the present invention, the polyamic acid film is brought into contact with a belt with a pin, and the imidization is carried out while continuously running. A method of manufacturing a polyimide film becomes possible.

Claims (6)

[Claims] (1) A polyamic acid solution having a gel-forming ability by a three-dimensional cross-linking reaction, under an inert gas atmosphere,
It is applied on a substrate at a temperature of 10 ° C. or lower, and (2) the applied polyamic acid solution is heated to form a polyamic acid gel film having self-supporting properties on the substrate, (3) Sequential polyamic acid gel film A method for producing a heat-resistant polyimide film, characterized in that the organic solvent therein is removed, and (4) further heat treatment is carried out for imidization. 2. The polyamic acid solution capable of forming a polymer gel by the three-dimensional crosslinking reaction is stored at a temperature of −10 ° C. or lower, and the solid content concentration of the reaction solution is 5 to 30% by weight. %, The apparent viscosity is maintained at 1 to 5,000 poises, The method for producing a heat-resistant polyimide film according to claim 1, wherein 3. The method of heating the applied polyamic acid solution to form a polyamic acid gel film having self-supporting properties on a substrate is carried out under an inert gas atmosphere. A method for producing the heat-resistant polyimide film described. 4. The method for removing the organic solvent in the polyamic acid gel film comprises blowing hot air at a temperature not exceeding 200 ° C. onto the polyamic acid gel film on the substrate. Method for producing heat-resistant polyimide film. 5. The method of imidization comprises peeling a polyamic acid gel film from a substrate and contacting at least one of both edges of the polyamic acid gel film with a driven belt with a pin to form a polyamide The method for producing a heat-resistant polyimide film according to claim 1, wherein imidization is performed while the acid film is continuously run. 6. The method for producing a heat-resistant polyimide film according to claim 1, wherein the heat treatment temperature for imidization is within the range of 500 ° C.