JP3386502B2 - Method for producing polyimide and polyimide film - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a polyimide and a polyimide film, and more particularly to a method for producing a polyimide and a polyimide film by a chemical imidization reaction of polyamic acid, which has excellent toughness and high visible light transmittance. And a method for producing a polyimide film.

[0002]

2. Description of the Related Art Polyimide film is widely used as an industrial material including electric equipment due to its stability at high temperature and excellent electrical characteristics. For example, flexible printed circuit board material and TAB (Tape Auto). It has been put to practical use as a base film material for mated bonding) and a coating material for copper wires. As described above, the polyimide film has excellent properties as compared with other resin films, but the properties required for the polyimide film become more advanced with the progress of technology, and it is desired that the polyimide film has various performances depending on the application.

In recent years, when a polyimide film is used as a base film material for TAB technology and flexible printed circuit board technology, in which the tendency toward miniaturization and refinement has become more prominent, the alignment by transmitted light is more accurate in the manufacturing process. In order to perform well, it is desired that the polyimide film itself has high transparency.

Conventionally, by keeping the maximum baking temperature at the time of forming a polyimide film low (about 300 ° C.),
It is known that a polyimide film having high visible light transmittance can be obtained, but the film obtained by this method is very brittle and cannot be used. On the other hand, a film with high toughness can be obtained by increasing the maximum baking temperature during film formation, but in this case, the color of the obtained film is dark and the visible light transmittance is low due to thermal deterioration due to high temperature baking. In addition, as the film thickness increases, the visible light transmittance decreases significantly.
From the above, it was difficult to make visible light transmittance and toughness compatible with each other by these conventional methods.

Therefore, the inventors of the present invention have conducted intensive studies for the purpose of providing a method for producing a polyimide film having both excellent toughness and high visible light transmittance, and as a result, as a result, a specific compound in polyamic acid was identified. The present inventors have found that the polyimide and polyimide film obtained by addition have both excellent toughness and high visible light transmittance, leading to the present invention.

[0006]

The gist of the method for producing a polyimide according to the present invention is that it is used as a catalyst for an imidization reaction in a method for producing a polyimide by imidizing a polyamic acid by a chemical method. A compound having a boiling point higher than the boiling point of the tertiary amine and the boiling point of the polymerization solvent of the polyamic acid is mixed with the polyamic acid, followed by baking / drying.
The maximum heat treatment temperature is higher than the boiling point of the high boiling point compound.
To raise it.

In such a method for producing a polyimide, the high boiling point compound is added in a polyamic acid solution in an amount of about 1 to 500% by weight relative to the amount of the polyamic acid resin in the solution.
More preferably, about 5 to 100% is added.

Further, the gist of the method for producing a polyimide film according to the present invention is that it is used as a catalyst for an imidization reaction in a method for producing a polyimide film by imidizing a polyamic acid by a chemical method.
After mixing the boiling point of the primary amine, and the compound having a higher boiling point than the boiling point of the polymerization solvent of the polyamic acid with the polyamic acid, a film is formed, and then the maximum heat treatment temperature in the firing / drying step is higher than the boiling point of the high boiling point compound. It is to make it higher and imidize .

In the method for producing such a polyimide film
The high boiling point compound in a polyamic acid solution.
1-500 by weight ratio to the amount of polyamic acid resin in the liquid
%, More preferably about 5 to 100%
In .

[0010]

In the method for producing a polyimide and a polyimide film according to the present invention, although the theoretical elucidation is not sufficient, the boiling point of a tertiary amine used as a catalyst for an imidization reaction and polyamide are used for polyamic acid which is a precursor of polyimide. Since a compound having a higher boiling point than the boiling point of the acid polymerization solvent is mixed, in the drying step involving imidization reaction, the high boiling point compound remains until the latter stage of drying, and polyamic acid that causes coloring due to heat deterioration is effective. Is imidized. As a result, it is possible to obtain a film which is less deteriorated by heat and therefore less colored and which is excellent in toughness.

When the amount of the high boiling point compound added is less than 1% by weight, the effect of the present invention, that is, the polyimide and the polyimide film having little toughness and toughness cannot be obtained. In addition, even if the amount of the high boiling point compound added is increased, that is, a certain fixed amount (for example, 500% by weight)
Even if added in the above amount, it does not become colorless and transparent, and the toughness does not increase.

[0012]

EXAMPLES Next, examples of the method for producing a polyimide and a polyimide film according to the present invention will be described in detail.

The method for producing a polyimide and a polyimide film according to the present invention is carried out by adding a dehydrating agent, a catalyst and a specific compound to a polyamic acid solution which is a precursor of a polyimide and mixing them to obtain a flat plate such as a glass plate, a drum or an endless film. A polyimide film having both excellent toughness and high visible light transmittance is obtained by casting or coating on a belt to form a film and baking at high temperature.

The polyamic acid solution used here can be obtained by a known method. That is, it can be obtained by using tetracarboxylic dianhydride component and diamine component in substantially equimolar amounts and polymerizing in an organic polar solvent. It is desirable that the polyamic acid is dissolved in the organic polar solvent in an amount of 5 to 40% by weight, preferably 10 to 30% by weight from the viewpoint of handling. The viscosity of this polyamic acid solution is 10
00-5000 poise, preferably 1500-3000
It is preferable that it is in the poise range from the viewpoint of easy film forming by casting.

As the organic polar solvent, sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, formamide solvents such as N, N'-dimethylformamide and N, N'-diethylformamide, N,
Acetamide-based solvents such as N'-dimethylacetamide and N, N'-diethylacetamide, N-methyl-2-
Pyrrolidone-based solvents such as pyrrolidone and N-vinyl-2-pyrrolidone, phenol-based solvents such as phenol, o-, m- or p-cresol, xylenol, halogenated phenol and catechol, or hexamethylphosphoramide, γ-butyrolactone And so on. These are preferably used alone or as a mixture, and aromatic hydrocarbons such as xylene and toluene can be used.

Examples of the dehydrating agent include aliphatic acid anhydrides such as acetic anhydride, aromatic acid anhydrides such as benzoic acid anhydride and phthalic acid anhydride. As the catalyst, for example, aliphatic tertiary amines such as triethylamine, N
-Aromatic tertiary amines such as dimethylaniline, and heterocyclic tertiary amines such as pyridine, picoline, quinoline and isoquinoline.

The specific compound essential to the present invention means that the boiling point of the tertiary amine used as a catalyst for the dehydration cyclization reaction of polyamic acid and the boiling point of the solvent used for polymerizing the polyamic acid are higher. It is a compound that has. For example, as a catalyst, pyridine (boiling point 115 ° C.), picoline (same 129
-145 ° C.), quinoline (same 237 ° C.), isoquinoline (same 242 ° C.) and the like, and N, N′-dimethylformamide (same 153 ° C.), N, N ′ as a solvent for further polymerizing the polyamic acid. -Dimethylacetamide (at 166 ° C.), N-methylpyrrolidone (at 202 ° C.), etc., each alone or in an appropriate combination, anthracene (at 340 ° C.), which is a compound having a boiling point higher than these boiling points, Naphthalene (at 218 ° C), methylformanilide (at 243 ° C), phenyl ether (at 2 ° C)
58 ° C), benzophenone (305 ° C), phenanthrene (340 ° C), anthraquinone (380 ° C)
C.), benzanthracene (at 437.degree. C.) and the like are used alone or in an appropriate combination. All of them have the effects of the present invention, but the compounds are not limited to these compounds.

As described above, in order to realize high visible light transmittance of the polyimide and the polyimide film, the tertiary amine used as a catalyst for the dehydration cyclization reaction of the polyamic acid and the solvent used when polymerizing the polyamic acid are used. It suffices to add a compound having a boiling point higher than the boiling point, and the upper limit of the boiling point of the compound having a high boiling point is not particularly limited. However,
Practically, a large amount of impurities remain in the polyimide and polyimide film in applications such as substrate materials,
The boiling point of this compound is more preferably equal to or lower than the maximum heat treatment temperature in the firing / drying step, since it may have an adverse effect on the electrical insulation characteristics.

The effect of the invention is obtained by adding these high boiling point compounds to the polyamic acid solution in a weight ratio of about 1 to 500%, more preferably about 5 to 100%, based on the amount of the polyamic acid resin in the solution. Is obtained. If the addition ratio of the high boiling point compound is less than this, the effect cannot be expected, and if it is more than this, the effect is saturated. Although the action due to the addition of this high boiling point compound is not theoretically clear, when the high boiling point compound remains until the latter stage of drying in the drying step involving the imidization reaction, the polyamic acid that causes coloring due to heat deterioration is effectively It is considered that the film is imidized, and as a result, a film having less heat deterioration, less coloring, and excellent toughness can be obtained.

Next, a few examples of producing a polyimide film by the method of the present invention will be described. In the first production example, a high boiling point compound is mixed in advance with a polyamic acid solution, and then a dehydrating agent and a catalyst in a stoichiometric amount or more are added and mixed, and then,
It is applied on a glass plate to form a film. The film is dried at a temperature of 150 ° C. or lower for about 5 to 90 minutes to obtain a polyamic acid film having self-supporting property. Then, this is peeled off from the support, and the end portion of the film is fixed. afterwards,
It is imidized by gradually heating to about 100 to 500 ° C. to obtain the polyimide film of the present invention.

In the second production example, a mixture of a stoichiometric or more stoichiometric dehydrating agent, a catalyst and a high boiling point compound was added and mixed, and then the mixture was applied in a film form on a glass plate. The polyimide film of the present invention is obtained by the same procedure as described above.

In the third production example, a high boiling point compound is added at the stage of polymerizing a polyamic acid, and a dehydrating agent and a catalyst having a stoichiometric amount or more are added to the obtained polyamic acid solution and mixed, and then the glass is added. It is applied on a plate and the polyimide film of the present invention is obtained by the same procedure as described above.

As described above, in any of the methods for producing a polyimide film, in the drying step involving the imidization reaction, the high boiling point compound remains until the latter stage of drying, and the polyamic acid that causes coloration due to heat deterioration is effectively imidized. To be made. As a result, it is possible to obtain a film which is less deteriorated by heat and therefore is less colored and is excellent in toughness.

Next, examples of the present invention will be described more specifically, but the present invention is not limited to the examples.

Example 1 Using a 2-liter separable flask, diaminodiphenyl ether (hereinafter referred to as ODA) in dehydrated and purified N, N'-dimethylformamide (hereinafter referred to as DMF).
Abbreviated. ) And pyromellitic dianhydride (hereinafter PMDA
Abbreviated. Was reacted in an ice bath in an equimolar amount to adjust the charged concentration of the monomer to 18% by weight to obtain a polyamic acid solution.

On the other hand, as shown in Table 1, 11.4 g of acetic anhydride as a dehydrating agent and 11.2 of isoquinoline as a catalyst.
g, 1 g of benzophenone as a high-boiling point additive as a solvent D
A dehydrating agent solution was prepared by dissolving it in 11.2 g of MF. This dehydrating agent solution was mixed with 100 g of the above polyamic acid solution, and the polyamic acid solution that had been stirred and defoamed was cast-coated on an aluminum foil and then dried at 80 ° C. for 5 minutes, after which the aluminum foil was peeled off and the polyamide The acid film was fixed with a support frame.

[Table 1]

Then, the polyamic acid film is heated at a temperature and a time shown in Table 2 for dehydration ring closure (imidization).
After being allowed to dry, the polyimide film was removed from the support frame to obtain a polyimide film having a thickness of about 75 μm.

[Table 2]

The color tone of the obtained polyimide film was evaluated by the Lab method using Σ90 manufactured by Nippon Denshoku Co., Ltd. The results are shown in Table 3. In the table, L represents lightness, a and b represent hues in red-green direction and yellow-blue direction, respectively, and C represents saturation. Here, the larger the value of L, the higher the lightness, that is, the higher the visible light transmittance.

[Table 3]

Folding resistance was measured according to ASTM D-2176 as one of the toughnesses of the obtained polyimide film. The measured values are shown in Table 4.

[Table 4]

Example 2 2 g of benzophenone as a high-boiling point additive, solvent DM
A dehydrating agent solution was obtained in the same manner as in Example 1 except that 10.4 g of F was used. This dehydrating agent solution was mixed with 100 g of the polyamic acid solution obtained in the same manner as in Example 1 to obtain a polyimide film having a thickness of about 75 μm in the same manner. The color tone of the obtained polyimide film was evaluated by the Lab method and the folding endurance was measured. The results are shown in Tables 3 and 4.

Example 3 4 g of benzophenone as a high-boiling point additive, solvent DM
A dehydrating agent solution was obtained in the same manner as in Example 1 except that 8.8 g of F was used. This dehydrating agent solution was mixed with 100 g of the polyamic acid solution obtained in the same manner as in Example 1 to obtain a polyimide film having a thickness of about 75 μm in the same manner. The color tone of the obtained polyimide film was evaluated by the Lab method and the folding endurance was measured. The results are shown in Tables 3 and 4.

Example 4 6 g of benzophenone as a high-boiling point additive, solvent DM
A dehydrating agent solution was obtained in the same manner as in Example 1 except that 7.0 g of F was used. This dehydrating agent solution was mixed with 100 g of the polyamic acid solution obtained in the same manner as in Example 1 to obtain a polyimide film having a thickness of about 75 μm in the same manner. The color tone of the obtained polyimide film was evaluated by the Lab method and the folding endurance was measured. The results are shown in Tables 3 and 4.

Comparative Example 1 A dehydrating agent solution was prepared by dissolving 11.4 g of acetic anhydride as a dehydrating agent and 11.2 g of isoquinoline as a catalyst in 11.2 g of DMF as a solvent. This dehydrating agent solution was mixed with 100 g of the polyamic acid solution obtained in the same manner as in Example 1 to obtain a polyimide film having a thickness of about 75 μm in the same manner. The color tone of the obtained polyimide film was evaluated by the Lab method and the folding endurance was measured. The results are shown in Tables 3 and 4.

As is clear from Table 3, the polyimide film produced by mixing the additive having a high boiling point according to this embodiment has a color tone different from that of the polyimide film produced by the conventional method in which the additive is not added. The excellent effect was obtained. The effect was recognized even when the amount of the additive added was about 1 g with respect to 100 g of the polyamic acid solution.
In g, there was almost no difference in the effect depending on the added amount. In order to obtain a more obvious effect, it is necessary to add 4 g or more of the additive, and the sample to which 6 g of benzophenone has been added has a 67% improvement in brightness as compared with the conventional sample.

The additives are not limited to benzophenone, and various additives having a boiling point higher than that of the dehydrating catalyst are also effective. In addition, ring-opening polyaddition of the polyamic acid in this example,
It is needless to say that the present invention is also effective for the polyamic acid solution obtained by various other various methods and the heat drying method. Other,
The polyimide obtained by the present invention is suitable for use other than a film, etc., and the present invention is carried out in a mode in which various improvements, modifications and variations are added based on the knowledge of those skilled in the art, within the scope not departing from the gist thereof. It is possible.

[0036]

INDUSTRIAL APPLICABILITY The present invention relates to the boiling point of a tertiary amine used as a catalyst for a dehydrating agent in a dehydration ring closure reaction of polyamic acid,
And, by adding a compound having a higher boiling point than the boiling point of the solvent used to polymerize the polyamic acid, by imidizing the polyamic acid to produce a polyimide, excellent toughness,
Moreover, it was possible to realize a polyimide film having excellent visible light transmittance. Therefore, by using such a polyimide film, it is possible to provide not only a flexible printed wiring board having high alignment accuracy by transmitted light but also a flexible printed wiring board having excellent toughness and high durability.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-4-189865 (JP, A) JP-A-62-279837 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08G 73/00-73/26 C08L 79/00-79/08

Claims (4)

(57) [Claims] 1. A method for producing a polyimide by imidizing a polyamic acid by a chemical method, wherein the boiling point of a tertiary amine used as a catalyst for an imidization reaction is higher than that of a polymerization solvent for the polyamic acid. A method for producing a polyimide, characterized in that the compound is mixed with a polyamic acid and the maximum heat treatment temperature in the firing / drying step is made higher than the boiling point of the high boiling point compound. 2. The high boiling point compound is added to a polyamic acid solution in a weight ratio of 1 with respect to the amount of the polyamic acid resin in the solution.
~ 500% is added, The manufacturing method of the polyimide of Claim 1 characterized by the above-mentioned. 3. A method for producing a polyimide film by imidizing a polyamic acid by a chemical method,
The boiling point of the tertiary amine used as a catalyst for the imidization reaction,
And a compound having a boiling point higher than that of the polymerization solvent of the polyamic acid are mixed with the polyamic acid, and then a film is formed, followed by baking.
A method for producing a polyimide film, which comprises imidizing the compound by making the maximum heat treatment temperature in the drying step higher than the boiling point of the high boiling point compound. 4. The high boiling point compound is added to a polyamic acid solution in a weight ratio of 1 with respect to the amount of the polyamic acid resin in the solution.
The method for producing a polyimide film according to claim 3, wherein the content is added in an amount of ˜500%.