JPH069801A - Production of polyimide film - Google Patents

Abstract

PURPOSE:To produce a polyimide film having a high imidation ratio at low temperature while keeping a shape of a film of a polyamic acid. CONSTITUTION:A film of a polyamic acid containing 7-30wt.% good solvent is immersed in an immersing liquid containing an acid anhydride, ethers and/or ketones to imidate the polyamic acid. The polyamic acid can be obtained by reaction of an tetracarboxylic acid dianhydride with an aromatic diamine. The film of the polyamic acid can be obtained by a casting method. The imidation ratio of the objective polyimide film can be further increased by immersing a film of polyamic acid in the immersing liquid and then subjecting the film to heat treatment at lower temperature than a glass transition temperature of a polyimide.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention provides a polyimide film having excellent heat resistance and mechanical properties, which can be used in a wide variety of fields such as electronics, transportation equipment, aerospace fields, and separation / purification fields such as membrane separation. Regarding the method.

[0002]

2. Description of the Related Art A polyimide film is widely used as a covering material for electric wires, cables, wires, etc., insulating material for transformers, printed wiring boards, etc., separation membrane material, etc. by utilizing its excellent characteristics. .

On the other hand, a polyimide is usually prepared by polycondensing a tetracarboxylic dianhydride and an aromatic diamine in an organic solvent, and polyamic acid (also referred to as polyamic acid) as a precursor is heated and dehydrated. Alternatively, it can be obtained by dehydration and cyclization by a chemical dehydration method using a dehydrating agent. Therefore, it is difficult to manufacture a polyimide film by a conventional method such as an extrusion molding method.

Therefore, this polyimide film is usually produced by casting an organic polar solvent solution of polyamic acid on a substrate (support) and then heat-treating it to dehydrate and cyclize the polyamic acid. There is.

However, in this method, in order to obtain a film having a high imidization ratio, it is necessary to heat at a temperature higher than the glass transition temperature of polyimide. In that case, the high temperature treatment causes the polyimide film to deteriorate due to heat or oxidation, or a gel-like substance is generated. Therefore, the characteristics of the film deteriorate and the degree of coloring increases.

A method of treating a polyamic acid film at a low temperature with a dehydrating agent is also known. However, with this method, it is usually difficult to obtain a film having a high imidization ratio while maintaining the shape of the film.

[0007]

Therefore, the object of the present invention is to improve the imidization ratio efficiently at low temperature.
It is to provide a method for manufacturing a polyimide film.

Another object of the present invention is to provide a method capable of producing a polyimide film having a high imidization ratio while maintaining the shape of the polyamic acid film.

Still another object of the present invention is to provide a method for producing a polyimide film having excellent mechanical properties without impairing the excellent heat resistance and chemical resistance of polyimide.

[0010]

As a result of intensive studies to achieve the above object, the present inventors have found that when a film of polyamic acid containing a specific amount of a good solvent is immersed in an organic solvent containing an acid anhydride for imidization. , (A) using a specific organic solvent,
(B) It was found that a polyimide film having a high imidization rate can be obtained even at a low temperature by subjecting it to a heat treatment at a specific temperature after the immersion, and completed the present invention.

That is, the present invention is a method of obtaining a polyimide film by immersing a film of polyamic acid containing 7 to 30% by weight of a good solvent in an immersion liquid containing an acid anhydride and a solvent to imidize it. Provided is a method for producing a polyimide film using ethers and / or ketones as the solvent.

Further, according to the present invention, a film of polyamic acid containing 7 to 30% by weight of a good solvent is dipped in an immersion liquid containing an acid anhydride and a solvent and heated at a temperature lower than the glass transition temperature of polyimide. Provided is a method of manufacturing a polyimide film to be treated.

The polyamic acid can be obtained by reacting a tetracarboxylic acid with an acid component such as a dianhydride or a lower dialkyl ester thereof and a diamine. A preferred polyamic acid can be obtained by reacting a tetracarboxylic dianhydride with an aromatic diamine.

Examples of the tetracarboxylic dianhydride 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 , Bis (3,4-dicarboxyphenyl) ether dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1 , 2,4,5-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,2-bis (3,4)
-Dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride,
Aromatic tetracarboxylic acid dianhydrides such as 3,4,9,10-perylenetetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride and ethylene glycol bis (anhydrotrimellitate) Anhydrides: alicyclic tetracarboxylic acid dianhydrides corresponding to these can be exemplified. These tetracarboxylic dianhydrides can be used alone or in combination of two or more.

Among these compounds, the heat resistance is high,
Compounds that give polyimide films with excellent chemical resistance and mechanical properties, such as pyromellitic dianhydride, benzophenonetetracarboxylic dianhydride, biphenyltetracarboxylic dianhydride, bis (dicarboxyphenyl)
Ether dianhydride is often used.

As the diamine, an aliphatic diamine,
Alicyclic diamines can be used, but aromatic diamines are often used in order to improve heat resistance.

Examples of aromatic diamines include m-phenylenediamine, p-phenylenediamine, and 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, 4,4'-
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 include diaminonaphthalene and derivatives thereof. The derivatives include compounds substituted with various substituents such as a halogen atom, a lower alkyl group and a lower alkoxy group. These aromatic diamines may be used alone or in combination of two or more.

Among these aromatic diamines, compounds which give a polyimide film excellent in heat resistance, chemical resistance and mechanical properties, such as m-phenylenediamine,
p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfide,
4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 4,4'-diaminobenzophenone, 2,2-bis (4-aminophenyl) propane, 4,4'-diaminobiphenyl are commonly used. It

The reaction of an acid component such as tetracarboxylic dianhydride with a diamine is usually a solvent which is inert to the reaction and in which the polyamic acid is soluble, such as N, N-dimethylformamide, N, N. -Dimethylacetamide, N-
It can be carried out in methylpyrrolidone or a mixed solvent thereof.

The reaction conditions can be appropriately selected depending on the type of raw material. For example, it is usually desirable to carry out the reaction between tetracarboxylic dianhydride and aromatic diamine at a temperature of 70 ° C. or lower.

The polyamic acid thus obtained is subjected to a film forming step as an organic solvent solution. The organic solvent is
Any solvent may be used as long as it is a good solvent for the polyamic acid, and may be the same as or different from the solvent used in the polycondensation reaction. Examples of good solvents for polyamic acid include N, N
-Dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, dimethylsulfoxide, N-methyl-2
-Pyrrolidone, N, N-dimethylmethoxyacetamide, hexamethylphosphoamide, pyridine, dimethyl sulfone, tetramethylene sulfone, phenol, cresol, xylenol and the like or a mixed solvent thereof can be used.

If necessary, various additives such as plasticizers, antioxidants, ultraviolet absorbers, fillers, lubricants, colorants and the like may be added to the organic solvent solution of polyamic acid. Good.

The concentration of the polyamic acid in the solution used in the film forming step may be within the range capable of forming a film, for example, 5
It is about 30% by weight.

The polyamic acid film can be formed by a conventional method such as a casting method (casting method). In the casting method, a dope solution of polyamic acid is cast on a support to form a polyamic acid film. The type of the support is not particularly limited, and may be, for example, a rotary drum having a flat surface, a sheet, a support plate, or the like.

The thickness of the polyamic acid film is not particularly limited, but is usually 2 to 500 μm, preferably 1
It is about 0 to 100 μm.

A feature of the first invention is that the film of (a1) polyamic acid contains a specific amount of the good solvent.
The point is that the film of (a2) polyamic acid is imidized by immersing it in a dipping solution containing an acid anhydride and ethers and / or ketones.

The content of the good solvent in the film is 7 to 3
It is 0% by weight, preferably 8 to 25% by weight, more preferably 8 to 20% by weight. When the content of the good solvent is less than 7% by weight, the acid anhydride is uniformly permeated into the film,
It becomes difficult to obtain a polyimide film having a high imidization ratio. On the other hand, if the content of the good solvent exceeds 30% by weight,
The supporting property as a film is lowered, and the film is easily diffused during the dipping treatment, so that the film shape cannot be maintained.

The content of the good solvent can be easily controlled by the drying conditions during film formation and after film formation. The polyamic acid film can be dried at room temperature to about 150 ° C. under normal pressure or reduced pressure depending on the kind of the good solvent.

The acid anhydride contained in the immersion treatment liquid is
Various acid anhydrides that chemically cause a cyclodehydration reaction, for example, aliphatic acid anhydrides such as acetic anhydride, propionic anhydride, butyric anhydride; aromatic acid anhydrides such as benzoic anhydride, phthalic anhydride, etc. Is mentioned. Preferred acid anhydrides include acetic anhydride. These acid anhydrides can be used alone or in combination of two or more.

The content of the acid anhydride is 1 equivalent or more, preferably 1.2 equivalents or more based on 1 equivalent of the carboxyl group of the polyamic acid.

The immersion treatment liquid preferably contains an amine catalyst. As the catalyst, trimethylamine, triethylamine, triethylenediamine, tributylamine, dimethylaniline, pyridine, α-picoline, β-
Tertiary amines such as picoline, γ-picoline, isoquinoline and lutidine, 1,5-diazabicyclo [4.3.
0] nonene-5,1,4-diazabicyclo [2.2.
2] Octane, 1,8-diazabicyclo [5.4.0]
An organic base such as undecene-7 is exemplified. The amount of the catalyst is 1 equivalent of the carboxyl group of polyamic acid,
It is 0.01 equivalent or more, preferably 0.05 equivalent or more.

As the solvent in the dipping treatment solution, ethers such as diethyl ether, diisopropyl ether, tetrahydrofuran, dioxane; ketones such as acetone, methyl ethyl ketone, diethyl ketone, diisopropyl ketone, methyl isobutyl ketone, cyclohexanone; a mixture thereof A solvent can be illustrated. By using such a solvent, a polyimide film having a high imidization ratio can be easily obtained. If necessary, the good solvent or another solvent may be added to the immersion treatment liquid.

The imidation by the immersion treatment can be appropriately selected depending on the kind of the solvent and the like, and is usually room temperature to 100 ° C., preferably about 15 to 50 ° C. Also, the immersion time can be selected according to the desired degree of imidization, and usually 10 minutes to
It is 48 hours, preferably about 30 minutes to 36 hours.

In such a method, the imidization ratio of the polyimide film can be increased by a simple operation of dipping and at a low temperature. Therefore, it is possible to obtain a polyimide film which has little heat deterioration and coloration and is excellent in heat resistance, chemical resistance and mechanical properties.

A feature of the second invention is that the film of (b1) polyamic acid contains the good solvent, (b2)
After immersing the film in an immersion liquid containing an acid anhydride and a solvent,
(B3) The polyamic acid film is heat-treated at a temperature lower than the glass transition temperature of polyimide.
The glass transition temperature can be easily measured by differential thermal analysis or the like.

As the polyamic acid film containing the good solvent, the same polyamic acid film (a1) as in the above method can be used.

Unlike the first invention, the solvent in the dipping treatment liquid is not particularly limited as long as it is a poor solvent for the polyamic acid and is miscible with the good solvent in the film. Examples of such a solvent include, in addition to the ethers and ketones, aliphatic hydrocarbons such as hexane and octane: alicyclic hydrocarbons such as cyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene. Hydrogen; chloroform, methylene chloride,
Examples thereof include halogenated hydrocarbons such as carbon tetrachloride and ethylene chloride; esters such as methyl acetate, ethyl acetate and butyl acetate; and mixed solvents thereof. Preferred solvents include ethers and / or ketones as described above. If necessary, the good solvent or another solvent may be added to the immersion treatment liquid.

In this method, the imidization ratio can be increased by heat treatment. Therefore, the immersion treatment (b
The dipping time in 2) and the imidization ratio by the dipping treatment may be shorter than the dipping time by the above method (a2) as long as the acid anhydride uniformly diffuses in the film. May be smaller. Further, in the case of obtaining a polyimide film having a higher imidization ratio, the imidization ratio of the film before the heat treatment may be increased in advance by immersion treatment in the same manner as the above method. Therefore, the immersion treatment can usually be performed at room temperature to about 100 ° C. for about 10 minutes to 48 hours.

It is important that the heat treatment is carried out at a temperature lower than the glass transition temperature of the finally obtained polyimide. The heating temperature can be selected according to the units constituting the polyimide, the desired imidization ratio, and the like. A preferable heating temperature is 70 ° C. to a temperature lower than the glass transition temperature of polyimide. Since the glass transition temperature of the aromatic polyimide is generally in the range of about 200 to 500 ° C., it is desirable to perform heat treatment at a temperature below the glass transition temperature depending on the type of polyimide. . A preferable heating temperature is about 100 to 350 ° C. Further, the heating time can be selected according to the desired imidization ratio, and is, for example, about 5 minutes to 24 hours.

In such a method, the imidization ratio of the polyimide film can be increased by the low temperature treatment.
Therefore, the polyimide film has less heat deterioration and coloring, exhibits high heat resistance and chemical resistance, and has excellent mechanical properties.

A preferred embodiment of the present invention is a combination of the above two processes, ie, (c1) 7-30% by weight.
A film of polyamic acid containing a good solvent of (c2)
It also includes a method in which the film of the (c3) polyamic acid is heat-treated at a temperature lower than the glass transition temperature of the polyimide by immersing it in an immersion liquid containing an acid anhydride, an ether and / or a ketone to imidize it. In this method, not only can the imidization ratio be increased by the dipping treatment, but the imidization ratio can be further increased by the heat treatment.

[0042]

According to the method of the present invention, when a film of polyamic acid containing a specific amount of a good solvent is immersed in an organic solvent containing an acid anhydride for imidization, a specific organic solvent is used as the solvent. After the immersion, heat treatment is performed at a specific temperature, so that the imidization ratio of the polyimide film can be efficiently increased at a low temperature. Further, according to the method of the present invention, while maintaining the shape of the polyamic acid film,
A polyimide film having a high imidization ratio can be manufactured. Therefore, the obtained polyimide film is excellent in heat resistance, chemical resistance and mechanical properties.

[0043]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited by these examples.

[0044] The measurement of imidization ratio was calculated as the peak intensity ratio of the 1000 cm ^-1 and 740 cm ^-1 on the basis of the infrared absorption spectrum. Further, the imidation ratio of the film obtained by heat-treating the polyamic acid film at 250 ° C. was set to 100%.

Reference Example 1 4,4'-bis (4-aminophenoxy) was placed in a flask.
55.2 g (0.15 mol) of biphenyl was added, and N, N
261 g of dimethylacetamide were added and dissolved.
While stirring the solution under a nitrogen gas atmosphere, 4,4 '
45.6 g (0.147 mol) of oxydiphthalic dianhydride were added slowly, taking care not to exceed a temperature of 70 ° C. A uniform polyamic acid solution was obtained by adding the whole amount of 4,4'-oxydiphthalic acid dianhydride and then stirring.

N, N-dimethylacetamide was added to the obtained polyamic acid solution to adjust the solid concentration to 10% by weight, and the solution was cast on a glass plate.

The cast polymer solution was heated at 100 ° C. for 2 hours to prepare a polyamic acid film having a thickness of 23 μm. The amount of N, N-dimethylacetamide remaining in the obtained film was measured by gas chromatography and found to be 12.2% by weight. The imidation ratio of the film was 17%.

Example 1 Polyamic acid film (20c) obtained in Reference Example 1
m × 20 cm) was immersed in a mixed solvent containing 360 ml of diethyl ether, 40 ml of acetic anhydride and 80 ml of pyridine at room temperature for 18 hours to prepare a polyimide film.
The glass transition temperature of the obtained polyimide film is 235.
° C., a tensile modulus ^{1.9 × 10 3 kg / cm 2} , breaking strength 690 kg / cm ^2, was breaking elongation 8.0%.

Example 2 A polyimide film was produced in the same manner as in Example 1 except that tetrahydrane was used instead of diethyl ether in the immersion liquid of Example 1.

Example 3 A polyimide film was prepared in the same manner as in Example 1 except that methyl ethyl ketone was used instead of diethyl ether in the immersion liquid of Example 1.

Comparative Example 1 The polyamic acid solution prepared in Reference Example 1 was cast on a glass plate, and the cast polymer solution was vacuum dried at 100 ° C. for 2 days to prepare a polyamic acid film having a thickness of 20 μm. . The amount of N, N-dimethylacetamide remaining in the obtained film was measured by gas chromatography and found to be 5.6% by weight. The imidation ratio of the film was 56%.

Comparative Example 2 A polyimide film was prepared in the same manner as in Example 1 except that toluene was used instead of diethyl ether in the immersion liquid of Example 1.

Comparative Example 3 A polyimide film was produced in the same manner as in Example 1 except that n-hexane was used instead of diethyl ether in the immersion liquid of Example 1.

Comparative Example 4 A polyamic acid film was subjected to immersion treatment in the same manner as in Example 1 without using diethyl ether as the immersion liquid in Example 1.
The film shape could not be maintained and the powdery polyimide was obtained.

Comparative Example 5 Polyamic acid film (20c) obtained in Comparative Example 1
(m × 20 cm) was immersed in the immersion liquid used in Example 1 for 24 hours to produce a polyimide film.

Comparative Example 6 A polyimide film was prepared in the same manner as in Comparative Example 5 except that methyl ethyl ketone was used instead of the diethyl ether in the immersion liquid of Comparative Example 5.

Comparative Example 7 A polyimide film was prepared in the same manner as in Comparative Example 5 except that toluene was used instead of diethyl ether in the immersion liquid of Comparative Example 5.

Comparative Example 8 The polyamic acid film obtained in Reference Example 1 was used as 250
It heat-processed at 2 degreeC for 2 hours, and produced the polyimide film.
The glass transition temperature of the obtained polyimide film is 240.
° C., a tensile modulus ^{1.2 × 10 3 kg / cm 2} , breaking strength 890 kg / cm ^2, was breaking elongation 9.0%.

Example 4 Polyamic acid film (20c) obtained in Reference Example 1
m × 20 cm) in a mixed solvent containing 360 ml of diethyl ether, 40 ml of acetic anhydride and 80 ml of pyridine.
It was immersed for 8 hours. Then, the film was heated at 200 ° C. for 6 hours to produce a polyimide film. The glass transition temperature of the obtained polyimide film is 240 ° C., the tensile elastic modulus is 1.9 × 10 ³ kg / cm ² , and the breaking strength is 640 kg /.
It was cm ² , and the breaking elongation was 4.0%.

Example 5 A polyimide film was produced in the same manner as in Example 4 except that tetrahydrofuran was used instead of diethyl ether in the immersion liquid of Example 4.

Example 6 A polyimide film was produced in the same manner as in Example 4 except that methyl ethyl ketone was used instead of diethyl ether in the immersion liquid of Example 4.

Then, except for Comparative Example 4 in which no film was obtained, the film thickness, appearance and imidization ratio of the films obtained in the above Examples, Comparative Examples and Reference Examples were evaluated, and the results shown in the table were obtained. Obtained.

[0063]

[Table 1] From the table, it is possible to obtain a polyimide film having a higher imidization rate than in the case of high-temperature heat treatment by a simple operation of immersing the polyamic acid film in an immersion liquid containing an acid anhydride and a specific solvent. Further, as is clear from the comparison between Examples 4 to 6 and Comparative Example 3, the polyamic acid film is immersed in an immersion liquid containing an acid anhydride and a solvent, and heated at a low temperature, so that a high temperature heat treatment is performed. A polyimide film having a high imidization rate can be obtained.

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[Procedure amendment]

[Submission date] August 12, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0049

[Correction method] Change

[Correction content]

[0049] Instead of diethyl ether dip of Example 1, except for using tetra <br/> hydrate b furan, in the same manner as in Example 1, to produce a polyimide film.

Claims (2)

[Claims] 1. A method for obtaining a polyimide film by immersing a film of a polyamic acid containing 7 to 30% by weight of a good solvent in an immersion liquid containing an acid anhydride and a solvent to obtain a polyimide film. A method for producing a polyimide film using ethers and / or ketones. 2. A polyimide film in which a film of polyamic acid containing 7 to 30% by weight of a good solvent is dipped in an immersion liquid containing an acid anhydride and a solvent, and heat-treated at a temperature lower than the glass transition temperature of polyimide. Manufacturing method.