JPH0820721A - Polyimide film and its production - Google Patents

Abstract

PURPOSE:To obtain a polyimide film whose surface has fine projections and which is excellent in surface lubricity and heat resistance and suitable for a flexible printed circuit substrate by mixing specific polyimides. CONSTITUTION:This film contains 5-20wt.% fine polyimide particles dispersed therein and having repeating units of the formula and has projections formed by the particles on its surface. The film is obtd. by reacting an arom. tetracarboxylic dianhydride with an arom. diamine in an org. solvent contg. the polyimide dissolved therein and forming the resultant polyamic acid into film. The polyimide having repeating units of the formula is obtd. by reacting bis [4-(4-aminophenoxy)phenyl]] sulfone with 3,3'4,4'- diphenylsulfonetetracarboxylic dianhydride in an org. polar solvent and subjecting the resultant product to imidization by dehydration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyimide film having excellent surface smoothness, which is preferably used as a substrate film for a fine patterned flexible printed wiring board or the like, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
Since the polyimide film is excellent in heat resistance, chemical resistance, mechanical strength, electrical characteristics, etc., it has been suitably used as a heat resistant material, a laminated plate, a flexible printed circuit board and the like.

However, a polyimide film that has not been surface-treated has a large friction with a roll or the like when laminated with a copper foil, and wrinkles may occur, which may cause troubles such as winding around the roll. There was a need to improve the surface lubricity of the film.

Conventionally, as a means for improving the surface activity of a polyimide film, surface treatment such as sand blasting or embossing, or a polyimide film having calcium phosphate (JP-A-62-68852) or silica (JP-A-6-68852).
No. 2-68853) and the like are mixed to form fine protrusions on the film surface to reduce surface friction.

However, the former method of surface treatment is
It has a drawback that the film surface is excessively roughened and the appearance of the film is easily damaged. In the latter method, the above-mentioned inorganic fine particles are difficult to uniformly disperse in the polyamic acid solution and remain as a lump without being dispersed, and the inorganic fine particles contain impurities, which adversely affect the electrical properties of the film. There was a drawback. Further, since there is no reactivity between the inorganic fine particles and the polyimide polymer and there is no direct bond, the mechanical strength may be lowered if they are blended excessively.

The present invention has been made in view of the above circumstances.
An object of the present invention is to provide a polyimide film having excellent properties such as heat resistance, mechanical strength, and electrical properties, which is excellent in surface smoothness of the film, and a method for producing the same.

[0007]

Means and Actions for Solving the Problems As a result of intensive studies for achieving the above object, the present inventors have found that a polyimide film having a repeating unit represented by the following formula (A) is mixed in the polyimide film. It has been found that a polyimide film can be obtained in which fine projections can be generated on the film surface, the surface smoothness of the film is excellent, and the heat resistance is also excellent.

[0008]

Embedded image

Further, as a method for producing such a polyimide film, bis (4- (4-aminophenoxy) phenyl) sulfone (BAPS) and 3,3 ', 4,4'-
Diphenyl sulfone tetracarboxylic acid dianhydride (DSD
A) is dissolved in an organic polar solvent to obtain a polyimide having a repeating unit of the above formula (A) to be a protrusion of the film, which is obtained by performing a dehydration imidization by reacting with A) in an organic polar solvent. A polyamic acid solution is prepared by reacting a group tetracarboxylic acid dianhydride and an aromatic diamine, and by imidizing the polyamic acid solution into a film, a polyimide film having the above-mentioned excellent properties can be industrially advantageously produced. Found out.

In this case, the polyimide of the formula (A) is soluble in a solvent, the polyimide of the formula (A) is dissolved in an organic polar solvent, and the aromatic compound is dissolved in an organic polar solvent containing the polyimide (A). When polyamic acid obtained by reacting tetracarboxylic dianhydride and aromatic diamine is subjected to film formation imidization, the reason why the protrusion of the above formula (A) occurs on the film surface is not clear, but by the above method Forming fine protrusions on the polyimide film surface, improving the slipperiness of the film surface, mechanical strength does not decrease, does not contain inorganic fine particles, etc., excellent in transparency of the film, and there is no protrusion of protrusions. The inventors have found that they also have excellent heat resistance, and have completed the present invention.

Therefore, in the present invention, the fine particles of polyimide having a repeating unit represented by the following formula (A) are 5 to 20.
Aromatic tetracarboxylic acid dianhydride in a polar organic solvent in which a polyimide film having a protrusion of fine polyimide particles dispersed on the surface and a polyimide having a repeating unit represented by the following formula (A) is dissolved. And a aromatic diamine are reacted to obtain a polyamic acid, which is then imidized to form a film.

[0012]

Embedded image

The present invention will be described in more detail below. In the polyimide film of the present invention, a polyimide having a repeating unit represented by the following formula (A) is uniformly dispersed and contained, and fine protrusions are formed on the surface by the polyimide. It will be. Here, the content of the polyimide represented by the formula (A) in the polyimide film is preferably 5 to 20% (% by weight, the same applies hereinafter). If it is less than 5%, the projections on the surface of the film are few and the surface smoothness may not be obtained in some cases, and if it is more than 20%, the physical properties of the film may deteriorate.

[0014]

[Chemical 4]

In the present invention, the polyimide having the repeating unit of the above formula (A) is a polymer and has a logarithmic viscosity of 0.1 at 30 ° C. in a molecular weight of 0.5 g / 100 ml DMF (N, N-dimethylformamide). It is preferably ˜1.5.

The logarithmic viscosity is such that the polyimide concentration is 0.5.
It can be determined by the following formula from the result of measurement using a solution of g / 100 ml DMF under measurement conditions of 30 ° C.

[0017]

[Equation 1]

When manufacturing the above-mentioned polyimide film,
A method of dissolving the polyimide of the above formula (A) in an organic polar solvent, reacting the aromatic tetracarboxylic dianhydride and the aromatic diamine in this solvent to obtain a polyamic acid, and then subjecting this to film formation imidization Can be adopted.

In this case, first, the method for obtaining the polyimide of the formula (A) will be described. As the method for obtaining the polyimide, (1) bis (4- (4-aminophenoxy) phenyl) sulfone (BAPS) and 3, 3 ', 4, 4'-
Diphenyl sulfone tetracarboxylic acid dianhydride (DSD
(2) Bis (4- (4), in which the reaction system (A) is reacted in an organic polar solvent at room temperature, the temperature of the reaction system is further raised to 60 to 80 ° C, and a dehydrating agent and a catalyst are added to dehydrate imidize.
-Aminophenoxy) phenyl) sulfone (BAPS)
And 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic acid dianhydride (DSDA) are reacted in an organic polar solvent at room temperature, and toluene is further added to this reaction system,
The temperature was raised to 140 to 200 ° C. to thermally close the ring, and the generated water was azeotropically distilled with toluene to remove it from the reaction system to obtain a polyimide solution, and then the polyimide solution was reprecipitated in methanol. It can be obtained by various methods such as a method of filtering and drying.

Here, the dehydrating agent used in the method (1) is preferably an aliphatic acid anhydride such as acetic anhydride, propionic acid, butyric anhydride, and the catalyst is triethylamine, trimethylamine, di- Tertiary amines such as n-butylamine, pyridine, α-, β-, γ-picoline, isoquinoline, dimethylaniline, triethylenediamine and dimethylamine are preferable.

Further, the polyimide of the formula (A) is relatively
A low degree of polymerization is preferred for uniform dissolution in the polyamic acid solution for film formation. Therefore, when polymerizing BAP
As for the molar ratio of S and DSDA, assuming that the total amount is 100, DSDA 70 to 51 relative to BAPS 30 to 49,
Or BAPS 70-51 for DSDA 30-49
Use within the range is preferred.

In the present invention, the thus obtained polyimide represented by the formula (A) is dissolved in an organic polar solvent, and an aromatic diamine and an aromatic tetracarboxylic acid dianhydride are added to the polyamic acid. To get a solution,
As the organic polar solvent used here, N, N-dimethylacetamide, N, N-dimethylformamide, N-
Methyl-2-pyrrolidone, dimethyl sulfoxide and the like can be mentioned.

Further, the compounding amount of the polyimide of the formula (A) is
The amount is preferably 5 to 20% with respect to the polyamic acid solid content in the obtained polyamic acid solution.

As the aromatic diamine used as the raw material for the polyimide film, for example, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane,
4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide, m-phenylenediamine, p-phenylenediamine, m-toluylenediene Amine, p-toluylene diamine, benzidine, 1,5-diaminonaphthalene, 1,3
-Bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4'-bis (4-aminophenoxy) biphenyl, 2,2-bis (4- (4-aminophenoxy) ) Phenyl) propane,
2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane, 4,4'-diaminobenzanilide, 3,3'-dihydroxy-4,4'-diaminobiphenyl, 1,4-diamino Anthraquinone,
2,6-diaminoanthraquinone, 2,6-diaminopyridine and the like can be mentioned.

On the other hand, examples of the aromatic tetracarboxylic dianhydride include 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.

The charging ratio of the aromatic tetracarboxylic dianhydride and the aromatic diamine of these film raw materials is as follows.
Although it is not particularly limited, it can be approximately equimolar.

Further, as a reaction procedure for obtaining a polyamic acid solution as a film raw material, a method of first dissolving an aromatic diamine in an organic polar solvent in which polyimide is suspended, and then adding an acid dianhydride, On the contrary, any of a method of dissolving the acid dianhydride in an organic polar solvent and then adding the diamine, a method of mixing both and then adding to the solvent is possible.
In addition, the reaction conditions are not particularly limited, but the heat generation is suppressed and the polyamic acid is contained in the solution at 10 to 20 ° C. for 10 to 20 ° C. or less.
It is preferable to perform it so that the concentration becomes%.

As a method for obtaining a polyimide film from a polyamic acid solution containing the polyimide represented by the above formula (A), a method similar to the method for producing a polyimide film from a usual polyamic acid solution can be used. The acid solution is cast on a flat plate such as a glass plate, pre-dried, peeled off, and then both ends are held at 150 to 250 ° C.
Desolvation with a method of heating and imidization at 300 ~ 450 ℃
A method such as chemical imidization in which a dehydrating agent and a catalyst are added at the time of film formation to effect dehydration ring closure can be mentioned. Here, as the dehydrating agent used for the chemical imidization, acetic anhydride, propionic anhydride, butyric anhydride, etc., which are aliphatic acid anhydrides, are preferable. As the catalyst, tertiary amines such as pyridine, α-, β-, γ-picoline, isoquinoline, dimethylaniline, triethylenediamine and dimethylamine are preferable.

Since the polyimide film obtained by the above method contains the polyimide represented by the above formula (A), it has excellent transparency and is free from the feeling of foreign matter.
Since it has fine protrusions on the surface, it is excellent in the surface activity of the polyimide film, and because it can retain the mechanical strength and heat resistance that are the original properties of the polyimide film, it is flexible such as a fine patterned flexible film. It is preferably used for printed circuit boards and the like.

[0030]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following examples,% means% by weight.

[Example 1] N, N in a 500 ml flask
-Take 200 g of dimethylformamide and add BAPS to 1
0g (0.02312 mol), 12.42 of DSDA
5 g (0.03468 mol) was charged, and the mixture was reacted at 25 ° C. for 30 minutes while flowing nitrogen gas. Next, the system temperature is 60 ℃
And continued to stir for 3 hours. To this polyamic acid solution, 12 ml of acetic anhydride and 1.6 ml of triethylamine were added and reacted at 60 ° C. for 5 hours to dehydrate the polyamic acid to obtain a polyimide. This polyimide solution was added to a large amount of methanol, reprecipitated, filtered, and dried to obtain a polyimide.

Next, 200 g of N, N-dimethylformamide was placed in a 500 ml flask, and 4.59 g of the above-mentioned polyimide was added and dissolved by stirring well. Diaminodiphenyl ether 10.12g (0.05mo
l) is added and dissolved, and pyromellitic dianhydride 1 is further added.
0.906 g (0.05 mol) was gradually added while suppressing heat generation to prepare a polyamic acid solution.

This polyamic acid solution was thinly spread on a glass plate with an applicator, dried in an oven at 110 ° C. for 60 minutes, peeled off, fixed on an iron frame, and kept at 200 ° C., 6 ° C.
The temperature was raised to 0 ° C. for 3 minutes, and then the temperature was raised to 350 ° C., and the solvent was imidized in 60 minutes to obtain a polyimide film having a thickness of 25 μm. When this polyimide film was observed with a scanning electron microscope, many fine protrusions having a diameter of 0.5 to 1 μm were observed on the film surface.

[Example 2] N, N in a 500 ml flask
-Take 200 g of dimethylformamide and add BAPS to 1
5 g (0.03468 mol), DSDA 8.283
g (0.02312 mol) was charged, and the mixture was reacted at 25 ° C. for 30 minutes while flowing nitrogen gas. Next, the temperature inside the system was raised to 60 ° C., and stirring was continued for 3 hours. To this polyamic acid solution, 12 ml of acetic anhydride and 1.6 ml of triethylamine were added and reacted at 60 ° C. for 5 hours to dehydrate the polyamic acid to obtain a polyimide. This polyimide solution was added to a large amount of methanol, reprecipitated, filtered, and dried to obtain a polyimide.

Next, 200 g of N, N-dimethylformamide was placed in a 500 ml flask, and 3.69 g of the above polyimide was added and dissolved by stirring well, and 10.12 g (0.05 mol) of diaminodiphenyl ether was added thereto.
Is added and dissolved, and further pyromellitic dianhydride 10.
A polyamic acid solution was prepared by gradually adding 906 g (0.05 mol) while suppressing heat generation.

This polyamic acid solution was thinly spread on a glass plate with an applicator, dried in an oven at 110 ° C. for 60 minutes, peeled off, fixed on an iron frame, and kept at 200 ° C., 6 ° C.
The temperature was raised to 0 ° C. for 3 minutes, and then the temperature was raised to 350 ° C., and the solvent was imidized in 60 minutes to obtain a polyimide film having a thickness of 25 μm. When this polyimide film was observed with a scanning electron microscope, the same protrusions as in Example 1 were observed.

[Example 3] N, N in a 500 ml flask
-Take 200 g of dimethylformamide and add BAPS to 1
0g (0.02312 mol), DSDA 9.112
g (0.02543 mol) was charged, and the reaction was carried out at 25 ° C. for 30 minutes while flowing a nitrogen gas. Next, the temperature inside the system was raised to 60 ° C., and stirring was continued for 3 hours. To this polyamic acid solution, 12 ml of acetic anhydride and 1.6 ml of triethylamine were added and reacted at 60 ° C. for 5 hours to dehydrate the polyamic acid to obtain a polyimide. This polyimide solution was added to a large amount of methanol, reprecipitated, filtered, and dried to obtain a polyimide.

Next, 200 g of N, N-dimethylformamide was placed in a 500 ml flask, 2.324 g of the above-mentioned polyimide was added, and the mixture was stirred well to dissolve it, and 10.12 g of diaminodiphenyl ether (0.05 mo) was added thereto.
l) is added and dissolved, and pyromellitic dianhydride 1 is further added.
0.906 g (0.05 mol) was gradually added while suppressing heat generation to prepare a polyamic acid solution.

This polyamic acid solution was spread thinly on a glass plate with an applicator, dried in an oven at 110 ° C. for 60 minutes, peeled off, fixed on an iron frame, and kept at 200 ° C., 6 ° C.
The temperature was raised to 0 ° C. for 3 minutes, and then the temperature was raised to 350 ° C., and the solvent was imidized in 60 minutes to obtain a polyimide film having a thickness of 25 μm. When this polyimide film was observed with a scanning electron microscope, many fine protrusions having a diameter of 0.5 to 2 μm were observed on the surface of the film.

Example 4 N, N was added to a 500 ml flask.
-Take 200 g of dimethylformamide and add BAPS to 1
0 g (0.02312 mol), DSDA 8.698
g (0.02428 mol) was charged, and the reaction was carried out at 25 ° C. for 30 minutes while flowing a nitrogen gas. Next, the temperature inside the system was raised to 60 ° C., and stirring was continued for 3 hours. To this polyamic acid solution, 12 ml of acetic anhydride and 1.6 ml of triethylamine were added and reacted at 60 ° C. for 5 hours to dehydrate the polyamic acid to obtain a polyimide. This polyimide solution was added to a large amount of methanol, reprecipitated, filtered, and dried to obtain a polyimide.

Then, 200 g of N, N-dimethylformamide was placed in a 500 ml flask, 1.101 g of the above-mentioned polyimide was added, and the mixture was dissolved by stirring well, and 10.12 g of diaminodiphenyl ether (0.05 mo) was added.
l) is added and dissolved, and pyromellitic dianhydride 1 is further added.
0.906 g (0.05 mol) was gradually added while suppressing heat generation to prepare a polyamic acid solution.

This polyamic acid solution was thinly spread on a glass plate with an applicator, dried in an oven at 110 ° C. for 60 minutes, peeled off, fixed on an iron frame, and 200 ° C. at 6 ° C.
The temperature was raised to 0 ° C. for 3 minutes, and then the temperature was raised to 350 ° C., and the solvent was imidized in 60 minutes to obtain a polyimide film having a thickness of 25 μm. When this polyimide film was observed with a scanning electron microscope, many fine protrusions having a diameter of 0.5 to 1 μm were observed on the film surface.

Example 5 N, N was added to a 500 ml flask.
-Take 200 g of dimethylformamide and add BAPS to 1
0 g (0.02312 mol), DSDA 8.698
g (0.02428 mol) was charged, and the reaction was carried out at 25 ° C. for 30 minutes while flowing a nitrogen gas. Next, 80 m of toluene
1 was added and the temperature in the system was raised to 140 ° C. while heating for 1 hour, and distilled water was removed from the system together with toluene, and further heated under reflux for 8 hours to remove the distilled water. Except for polyimide. The reaction system was cooled to 25 ° C., the polyimide solution was added to a large amount of methanol, reprecipitated, filtered, and dried to obtain a polyimide.

Next, 200 g of N, N-dimethylformamide was placed in a 500 ml flask, 2.324 g of the above-mentioned polyimide was added, and the mixture was stirred well to dissolve it. Then, 10.12 g of diaminodiphenyl ether (0.05 mo) was added.
l) is added and dissolved, and pyromellitic dianhydride 1 is further added.
0.906 g (0.05 mol) was gradually added while suppressing heat generation to prepare a polyamic acid solution.

This polyamic acid solution was thinly spread on a glass plate with an applicator, dried in an oven at 110 ° C. for 60 minutes, peeled off, fixed on an iron frame, and 200 ° C. at 6 ° C.
The temperature was raised to 0 ° C. for 3 minutes, and then the temperature was raised to 350 ° C., and the solvent was imidized in 60 minutes to obtain a polyimide film having a thickness of 25 μm. When this polyimide film was observed with a scanning electron microscope, many fine protrusions having a diameter of about 0.5 μm were observed on the surface of the film.

[Example 6] N, N in a 500 ml flask
-Take 200 g of dimethylformamide and add BAPS to 1
0g (0.02312 mol), DSDA 9.526
g (0.02659 mol) was charged, and the mixture was reacted at 25 ° C. for 30 minutes while flowing nitrogen gas. Next, 80 m of toluene
1 was added and the temperature in the system was raised to 140 ° C. while heating for 1 hour, and distilled water was removed from the system together with toluene, and further heated under reflux for 8 hours to remove the distilled water. Except for polyimide. This reaction system was cooled to 25 ° C., and this polyimide solution was added to a large amount of methanol, reprecipitated, filtered, and dried to obtain a polyimide.

Then, 200 g of N, N-dimethylformamide was placed in a 500 ml flask, 3.3691 g of the above-mentioned polyimide was added, and the mixture was stirred well to dissolve it. Then, 10.12 g of diaminodiphenyl ether (0.05 m) was added.
Ol) was added and dissolved, and 10.906 g (0.05 mol) of pyromellitic dianhydride was gradually added while suppressing heat generation to prepare a polyamic acid solution.

This polyamic acid solution was thinly spread on a glass plate with an applicator, dried in an oven at 110 ° C. for 60 minutes, then peeled off, fixed on an iron frame, and kept at 200 ° C., 6 ° C.
The temperature was raised to 0 ° C. for 3 minutes, and then the temperature was raised to 350 ° C., and the solvent was imidized in 60 minutes to obtain a polyimide film having a thickness of 25 μm. When this polyimide film was observed with a scanning electron microscope, many fine protrusions having a diameter of 0.5 to 1 μm were observed on the film surface.

[Comparative Example 1] N, N was added to a 500 ml flask.
Taking 153.4 g of dimethylformamide, dinitrodiphenyl ether 10.01 while flowing nitrogen gas.
2 g (0.05 mol) was added and dissolved, and then 10.906 g (0.05 mol) pyromellitic dianhydride was prepared to prepare a 12% polyamic acid solution while suppressing heat generation.

This polyamic acid solution was thinly spread on a glass plate with an applicator, dried in an oven at 110 ° C. for 60 minutes, peeled off, fixed on an iron frame, and kept at 200 ° C., 6 ° C.
The temperature was raised to 0 ° C. for 3 minutes, and then the temperature was raised to 350 ° C., and the solvent was imidized in 60 minutes to obtain a polyimide film having a thickness of 25 μm.

[Comparative Example 2] N, N was added to a 500 ml flask.
-Take 200 g of dimethylformamide and add BAPS to 1
0g (0.02312 mol), 12.42 of DSDA
5 g (0.03468 mol) was charged, and the mixture was reacted at 25 ° C. for 30 minutes while flowing nitrogen gas. Next, the system temperature is 60 ℃
And continued to stir for 3 hours. To this polyamic acid solution, 12 ml of acetic anhydride and 1.6 ml of triethylamine were added, and the mixture was reacted at 60 ° C. for 5 hours to dehydrate the polyamic acid,
Polyimide was used. This polyimide solution was added to a large amount of methanol, reprecipitated, filtered, and dried to obtain a polyimide.

Next, 200 g of N, N-dimethylformamide was placed in a 500 ml flask, 0.647 g of the above-mentioned polyimide was added, and the mixture was stirred well and dissolved. Diaminodiphenyl ether 10.12g (0.05m
Ol) was added and dissolved, and 10.906 g (0.05 mol) of pyromellitic dianhydride was gradually added while suppressing heat generation to prepare a polyamic acid solution.

This polyamic acid solution was thinly spread on a glass plate with an applicator, dried in an oven at 110 ° C. for 60 minutes, peeled off, fixed on an iron frame, and kept at 200 ° C., 6 ° C.
The temperature was raised to 0 ° C. for 3 minutes, and then the temperature was raised to 350 ° C., and the solvent was imidized in 60 minutes to obtain a polyimide film having a thickness of 25 μm. When this polyimide film was observed with a scanning electron microscope, minute projections having a diameter of less than 0.5 μm were sparsely seen on the film surface.

[Comparative Example 3] N, N was added to a 500 ml flask.
-Take 200 g of dimethylformamide and add BAPS to 1
0g (0.02312 mol), 12.42 of DSDA
5 g (0.03468 mol) was charged, and the mixture was reacted at 25 ° C. for 30 minutes while flowing nitrogen gas. Next, the system temperature is 60 ℃
And continued to stir for 3 hours. To this polyamic acid solution, 12 ml of acetic anhydride and 1.6 ml of triethylamine were added, and the mixture was reacted at 60 ° C. for 5 hours to dehydrate the polyamic acid,
Polyimide was used. This polyimide solution was added to a large amount of methanol, reprecipitated, filtered, and dried to obtain a polyimide.

Then, 200 g of N, N-dimethylformamide was placed in a 500 ml flask, and 6.973 g of the above-mentioned polyimide was added, and the mixture was stirred well and dissolved. Diaminodiphenyl ether 10.12g (0.05m
Ol) was added and dissolved, and 10.906 g (0.05 mol) of pyromellitic dianhydride was gradually added while suppressing heat generation to prepare a polyamic acid solution.

This polyamic acid solution was thinly spread on a glass plate with an applicator, dried in an oven at 110 ° C. for 60 minutes, peeled off, fixed on an iron frame, and kept at 200 ° C., 6 ° C.
The temperature was raised to 0 ° C. for 3 minutes, and then the temperature was raised to 350 ° C., and the solvent was imidized in 60 minutes to obtain a polyimide film having a thickness of 25 μm. When this polyimide film was observed with a scanning electron microscope, minute protrusions with a diameter of 2 to 3 μm were observed on the film surface, but the mechanical strength was reduced.

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. Dynamic friction coefficient: The film surface friction coefficient was measured based on JIS K7125. Mechanical strength (tensile strength, elastic modulus, tensile elongation): AST
It was measured using a TENSILON type tester based on MD882-88.

[0058]

[Table 1]

[0059]

INDUSTRIAL APPLICABILITY The polyimide film of the present invention does not impair the original physical properties, appearance and transparency of the polyimide film, and the surface thereof is excellent in slipperiness, and can be suitably used for flexible printed circuit boards and the like. it can.

Further, according to the production method of the present invention, the above-mentioned excellent polyimide film can be produced industrially advantageously.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masahiro Yuyama, Inventor Masahiro Yuyama 1 Towada, Kamisu-cho, Kashima-gun, Ibaraki Shin-Etsu Chemical Co., Ltd., Polymer Functional Materials Research Center (72) Inventor Kiyoshi Motoumi Kashima-gun, Ibaraki Prefecture No. 1 Towada, Kamisu Town, Shin-Etsu Chemical Co., Ltd.

Claims (2)

[Claims] 1. Fine particles of polyimide having a repeating unit represented by the following formula (A) are dispersed in an amount of 5 to 20% by weight,
A polyimide film having protrusions of the fine polyimide particles on the surface. Embedded image 2. A polyamic acid is obtained by reacting an aromatic tetracarboxylic dianhydride and an aromatic diamine in an organic polar solvent in which a polyimide having a repeating unit represented by the above formula (A) is dissolved. The method for producing a polyimide film according to claim 1, wherein the film is imidized.