JPH06192419A - Production of polyimide film - Google Patents

Abstract

PURPOSE:To produce a polyimide film excellent in mechanical strength and dimensional stability continuously in a relatively short time. CONSTITUTION:A soln. of a polyamic acid precursor is mixed with a dehydrating agent in an amt. of 0.2-0.8 equivalent (based on polyamide units in the soln.) and a catalyst in an amt. of 0.02-0.3 equivalent (based as above) and thereby partially chemically imidized. The soln. is then formed into a film and thermally imidized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyimide film which is excellent in mechanical strength and dimensional stability and which can be industrially advantageously produced as a polyimide film suitable for a substrate film such as a flexible printed circuit board. .

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
Polyimide films have been used for heat-resistant materials, laminates, flexible printed boards, etc. because they are excellent in heat resistance, chemical resistance, mechanical strength, and electrical characteristics.

As a method for molding a polyimide film, generally, a part of the thermoplastic polyimide resin is removed, and a precursor thereof, a polyamic acid solution, is cast on a smooth surface and the solvent is removed to form a film, and then both ends are held. To completely remove the solvent,
The method of thermal imidization is adopted. in this case,
As a method of imidizing a polyamic acid, a method of evaporating a solvent and then thermally imidizing it, and a method of mixing a dehydrating agent and a catalyst to chemically imidize at a low temperature are known.

However, in the former thermal imidization method, the process of forming a film by removing the solvent takes a long time, and the polyimide acid is hydrolyzed by being unnecessarily exposed to heat at the polyamic acid stage, and therefore However, there is a problem that the physical properties of the finally obtained polyimide film are likely to deteriorate.

On the other hand, in the latter case of the chemical imidization, since the imidization proceeds at a low temperature, a polyamic acid solution in which a dehydrating agent and a catalyst are mixed is cast onto a smooth surface such as glass or a stainless steel plate to form a solvent. Since the imidization is almost completed at the time when the film is vapor-deposited, the hydrolysis of the polyamic acid is small, and the orientation effect produced when the solvent is evaporated is large,
It is known that a film having good physical properties can be obtained.
However, the polyamic acid solution mixed with the dehydrating agent has a drawback that it cannot be stored because the gelation occurs in several hours because imidization gradually progresses even at room temperature. Therefore, long-time continuous molding using chemical imidization is difficult.

The present invention has been made in view of the above circumstances.
It is an object of the present invention to provide a method for producing a polyimide film capable of producing a polyimide film excellent in mechanical strength and dimensional stability in a relatively short time and by continuous operation.

[0007]

Means and Actions for Solving the Problems As a result of intensive studies for achieving the above object, the present inventor has found that the solution of polyamic acid precursor is 0.2 per polyamide unit of the solution.
When 0.8 to 0.8 equivalent of a dehydrating agent and 0.02 to 0.3 equivalent of a catalyst are added and mixed to partially perform chemical imidization, and then a film is formed by thermal imidization, the dehydrating agent is used. Also, even if the polyamic acid solution after the addition of the catalyst is stored for a long time, gelation or hydrolysis of the polyamic acid is not caused, and the partial chemical imidization gives strength to the molecular chain during film formation and an orientation effect. Is further increased, and by thermal imidization by film formation, a polyimide film having excellent mechanical strength and dimensional stability close to the physical properties of conventional complete chemical imidization can be obtained in a relatively short time. Moreover, they have found that they can be manufactured continuously, and have completed the present invention.

Therefore, according to the present invention, 0.2 to 0.8 equivalents of a dehydrating agent and 0.02 to 0.3 equivalents of a catalyst are added to and mixed with a polyamic acid precursor solution based on polyamide units of the solution. Then, a method for producing a polyimide film is provided, in which the film is formed by thermal chemical imidization after partial chemical imidization.

The present invention will be described in more detail below. In the method for producing a polyimide film of the present invention, a specific amount of a dehydrating agent and a catalyst are added to and mixed with a polyamic acid precursor solution so that the polyamic acid is partially imidized. After this, it is formed into a film and thermally imidized.

In this case, the polyamic acid precursor solution can be prepared, for example, by reacting an aromatic tetracarboxylic dianhydride with an aromatic diamine or an aliphatic diamine in an organic polar solvent.

Here, as the aromatic tetracarboxylic acid dianhydride, for example, pyromellitic dianhydride, 3,3 ',
4,4'-biphenyl tetracarboxylic dianhydride, diphenyl ether tetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride and the like can be mentioned.

As the aromatic diamine, for example, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4,4'-diaminodiphenylpropane,
4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide, m-phenylenediamine, p-phenylenediamine, m-toluylenediamine, p-toluylenediamine, benzidine, 1,5-diaminonaphthalene, etc. Can be mentioned.

Further, as the aliphatic diamine, for example, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, diaminopropyl, tetramethylenediamine, 3-methylheptamethylenediamine, 4,4- Dimethyl-heptabis- (3-aminopropoxymethane), 2,2-dimethylpropylenediamine, 3-methoxyhexamethylenediamine, 2,5-dimethylhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 3-methylheptamethylene Diamine, 5-methylnonamethylenediamine, 2,11-diaminododecane, 1,4-diaminocyclohexane, 1,10-diamino-1,10-dimethyldecane, 1,12-diaminooctadecane, 4,4′- Diamino-3,3'-dimethyldicyclohexyne, 4,4'-diaminodicyclohexylmethane, 4,4'-diaminodicyclohexane,
1,4-cyclohexanebis (methylamine) and the like can be mentioned.

Examples of the organic polar solvent include N, N-dimethylacetamide, N, N-dimethylformamide, N-methyl-2-pyrrolidone and dimethyl sulfoxide.

Further, in order to improve the lubricity of the film surface, a filler such as silica, alumina or calcium phosphate may be mixed.

The use ratio of the aromatic tetracarboxylic dianhydride and the aromatic diamine or the aliphatic diamine is not particularly limited, but they can be approximately equimolar amounts, and the concentrations of these two components in the solvent are also set. Although appropriately selected, it is suitable to be about 10 to 30%. If the concentration is less than 10% or more than 30%, the solution viscosity may be too high and bubbles may be generated during film formation or the surface smoothness may be deteriorated.

Further, the reaction conditions are not particularly limited, but 4
It is desirable to carry out the reaction at 0 ° C or lower, particularly 30 ° C or lower for 2 to 10 hours.

In the present invention, a dehydrating agent and a catalyst are added to and mixed with the polyamic acid precursor solution to partially chemically imidize it.

In this case, the amount of the dehydrating agent added is 0.2 to 1 unit of the polyamic acid in the polyamic acid precursor solution.
It is 0.8 equivalent, preferably 0.3 to 0.7 equivalent. If the amount of the dehydrating agent added is less than 0.2 equivalent, the effect of partial chemical imidization cannot be obtained, and if it exceeds 0.8 equivalent, gelation occurs within a few hours at room temperature.

The amount of catalyst added is 0.02 to 1 unit of polyamic acid in the polyamic acid precursor solution.
It is 0.3 equivalent, preferably 0.05 to 0.2 equivalent.
If the addition amount of the catalyst is 0.02 equivalent or less, the effect of the catalyst is not sufficient, and addition of 0.3 equivalent or more does not change the effect.

The above-mentioned dehydrating agent and catalyst are previously dissolved in an organic solvent, diluted, and then added to the polyamic acid precursor solution,
It is preferable to mix quickly and uniformly so that partial gelation can be prevented.

When the polyamic acid solution is stirred for 30 minutes to several hours after the addition of the dehydrating agent and the catalyst, partial chemical imidization proceeds during this period, and the polyamic acid solution changes from pale yellow to orange.

Next, the partially imidized polyamic acid solution thus obtained is cast onto a smooth surface of a glass plate, a stainless plate or the like and pre-dried at 90 to 120 ° C. for 5 to 15 minutes. The solvent is evaporated and the partially imidized polyamic acid film is peeled off. At this point, 20-40% of the solvent remains in the film, but since the film is partially imidized, it is then fixed on an iron frame or the like to skip the solvent and completely imidize the film. Does not endure contraction and does not tear or separate.

Further, the film predried as described above is heated at 150 to 200 ° C. for 5 to 15 minutes to remove the solvent by holding both ends and heated at 300 to 450 ° C. for 2 to 15 minutes. The heating imidization proceeds to complete imidization.

[0025]

According to the method for producing a polyimide film of the present invention, a polyimide film having excellent mechanical properties and dimensional stability, which is suitable as a flexible printed circuit board or the like, can be industrially advantageously used in a relatively short time. It can be manufactured. Furthermore, according to the method of the present invention, the polyamic acid solution can be stored without gelation of the polyamic acid solution, so that the polyimide film can be manufactured by continuously operating for a long time.

[0026]

EXAMPLES The present invention will be specifically described below with reference to Reference Examples, Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Reference Example 1 A 1000 ml flask was charged with N,
356.6 g of N-dimethylformamide and 20.024 g (0.1 mol) of diaminodiphenyl ether were charged and stirred while flowing a nitrogen gas to dissolve the diaminodiphenyl ether. Next, pyromellitic dianhydride 2
1.812 g (0.1 mol) was added at a temperature of 25 ° C. while suppressing the heat generation and reacted. After adding pyromellitic dianhydride, pyromellitic dianhydride adhering to the beaker was washed with 20 g of DMF, and the whole was put into the flask. Stirring under nitrogen was continued for 3 hours to synthesize a polyamic acid solution (10% concentration).

Example 1 100 g of the polyamic acid solution synthesized in Reference Example 1 was placed in a 500 ml flask and stirred under nitrogen. Then, in a 50 ml beaker, 1.70 acetic anhydride.
8 g (0.5 equivalent of polyamic acid unit) and 0.324 g of isoquinoline were taken and diluted with 10 g of DMF, and this was added to the flask in which the polyamic acid was stirred. The polyamic acid solution changed from yellow to orange over time after the addition. After stirring for 1 hour, this polyamic acid solution was thinly spread on a glass plate with an applicator, dried in an oven at 110 ° C. for 10 minutes, peeled off, and fixed on an iron frame,
The film was desolvated at 200 ° C. for 10 minutes and 350 ° C. for 10 minutes to form a 25 μm thick film.

Example 2 100 g of the polyamic acid solution synthesized in Reference Example 1 was placed in a 500 ml flask and stirred under nitrogen. Then add 1.22 acetic anhydride in a 50 ml beaker.
0 g (0.5 equivalents in terms of polyamic acid unit) and 0.1418 g of pyridine were taken and diluted with 10 g of DMF, and this was added to the flask in which the polyamic acid was stirred. The polyamic acid solution changed from yellow to orange over time after the addition. After stirring for 1 hour, the polyamic acid solution was thinly spread on a glass plate with an applicator and placed in an oven for 1 hour.
After drying at 10 ℃ for 10 minutes, peel it off and fix it to the iron frame.
Desolvation imidization was carried out at 00 ° C. for 10 minutes and 350 ° C. for 10 minutes to obtain a film having a thickness of 25 μm.

Comparative Example 1 The polyamic acid solution of Reference Example 1 was thinly spread on a glass plate with an applicator, dried in an oven at 110 ° C. for 60 minutes, then peeled off and fixed on an iron frame, and 200 ° C. for 60 minutes. The film was desolvated at 350 ° C. for 60 minutes to give a film having a thickness of 25 μm.

[Comparative Example 2] 100 g of the polyamic acid solution synthesized in Reference Example 1 was placed in a 500 ml flask and stirred under nitrogen. Then add 4.88 acetic anhydride to a 50 ml beaker.
0 g (2 equivalents in terms of polyamic acid unit), pyridine 0.
926 g was taken and diluted with 10 g DMF, and this was added to the flask in which the polyamic acid was stirred. The polyamic acid solution changed from yellow to orange over time after the addition. After stirring for 1 hour, the polyamic acid solution was thinly spread on a glass plate with an applicator, and then 110 ° C in an oven.
After drying at ℃ for 10 minutes, peel it off and fix it on the iron frame.
Desolvation imidization at ℃, 10 minutes, 350 ℃, 10 minutes to 2
The film was 5 μm thick.

Comparative Example 3 100 g of the polyamic acid solution synthesized in Reference Example 1 was placed in a 500 ml flask and stirred under nitrogen. Then add 0.24 acetic anhydride to a 50 ml beaker.
40 g (0.1 equivalent in terms of polyamic acid unit) and 0.1389 g of isoquinoline are taken and diluted with 10 g of DMF,
This was added to the stirring flask with polyamic acid. The polyamic acid solution changed from yellow to light orange as time passed after the addition. After stirring for 1 hour, the polyamic acid solution was thinly spread on a glass plate with an applicator,
It was dried in an oven at 110 ° C for 10 minutes, peeled off, fixed on an iron frame, and solvent-imidized at 200 ° C for 10 minutes and 350 ° C for 10 minutes to obtain a film having a thickness of 25 µm.

The physical properties of the polyimide films obtained in the above Examples and Comparative Examples were measured by the following methods. The results are shown in Table 1. Mechanical strength (tensile strength, elastic modulus, elongation): ASTM D
882-88. Heat shrinkage rate: Based on JIS C2318 6.3.5
After heating for 2 hours in a constant temperature bath at a temperature of 200 ± 3 ° C., it was taken out and left at room temperature for 30 minutes.

[0034]

[Table 1]

From the results shown in Table 1, it was confirmed that the method of the present invention can industrially produce a polyimide film excellent in mechanical strength and dimensional stability.

Claims (1)

[Claims] 1. A polyamic acid precursor solution containing 0.2 to 0.8 equivalent of a dehydrating agent with respect to polyamide units of the solution, and 0.1.
A method for producing a polyimide film, comprising adding and mixing 02 to 0.3 equivalent of a catalyst to partially chemically imidize it, and then forming a film to thermally imidize it.