JP2000072900A - Production of polyimide film having low shrinkage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for the production of a polyimide film having low shrinkage in high production efficiency. SOLUTION: A polyamic acid solution produced by polymerizing pyromellitic dianhydride and 4,4'-diaminodiphenyl ether in an organic solvent is cast or extruded in the form of a film and dried and heat-treated to obtain a polyimide film. The film is continuously heat-treated with hot air under a tension of 1-10 kg/m applied to the film in longitudinal direction and then cooled to obtain the objective film.

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 low shrinkage polyimide film having improved heat shrinkage.

[0002]

2. Description of the Related Art A polyimide obtained by polycondensing an aromatic tetracarboxylic dianhydride and an aromatic diamine is known as a polymer having extremely excellent heat resistance.

[0003] Although this polyimide is insoluble in a solvent, its precursor, polyamic acid, is soluble in a specific organic solvent. Therefore, this polyamic acid organic solvent solution is cast and dried at the same time as imidization. As a result, a heat-resistant film can be obtained.

Since this polyimide film has excellent heat resistance, insulation properties and mechanical properties, it has been conventionally used as a base film for flexible printed circuit boards.

[0005]

In order to make a flexible printed circuit board using a polyimide film as a base film, a metal foil such as copper is laminated or vacuum deposited.
It is necessary to attach a metal by sputtering or the like, but considerable heat is applied in this step, so dimensional stability against heat is required.

In particular, recently, a polyimide film which has a small shrinkage due to heat due to fine patterning of a flexible printed board has been desired.

As a means for meeting such a demand, Japanese Patent Application Laid-Open No. Sho 62-41024 discloses that a polyimide film is substantially used.
A method has been proposed in which a tension is reduced, heat treatment is performed in a heating oven, and then cooling is performed. The method of heat treatment under no tension is an effective method because the latent shrinkage stress is relaxed and the shrinkage is reduced by subsequent heating, but has the following disadvantages.

That is, in order to perform heat treatment under no tension, a method in which a roll wound with a film is left in a heating oven (Example of Japanese Patent Application Laid-Open No. 62-41024) or a continuous machine equipped with an unwinding and winding machine There is a method of continuously processing the film in a selective heating furnace, but in any case, it will be processed under no tension for a long time, so the film will be in a wavy state,
This causes a problem that the heat shrinkage ratio varies. In particular, in the case of continuous processing, there is a disadvantage that the film meanders and a complete product roll cannot be obtained.

Further, even in the case of a batch type in which the film is left in a dryer, it is impossible to prevent wrinkles from being generated on the film surface, so that it cannot be used as a base film for a precision printed circuit board. In addition, these methods have a problem in that the effect of the low shrinkage ratio varies, and for example, in the portion where wrinkles occur, the heat shrinkage ratio in the MD direction and the TD direction fluctuates greatly.

Furthermore, in order to improve the dimensional stability against heat, a polyimide film is prepared from a polyamic acid solution employing biphenyltetracarboxylic dianhydride as aromatic tetracarboxylic dianhydride and phenylenediamine as aromatic diamine. A special raw material production method was used.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a method for producing a polyimide film having low shrinkage and high production efficiency.

[0012]

In order to solve the above problems, the present invention employs the following means.

That is, in the present invention, a polyamic acid solution obtained by polymerizing pyromellitic dianhydride and 4,4′-diaminodiphenyl ether in an organic solvent is cast or extruded into a film, dried and heat-treated. The obtained polyimide film is subjected to a heat treatment with hot air continuously while applying a tension of 1 to 10 kg / m in the length direction of the film, and then subjected to a cooling process, thereby producing a low-shrinkage polyimide film. And preferably, a catalyst and a dehydrating agent are added to the polyamic acid solution.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The polyimide in the present invention mainly has a structure of the following formula (I).

[0015]

Embedded image In the structure of the formula (I), a precursor of the following formula (II) is closed.

[0016]

Embedded image (Where R is a pyromellitic dianhydride residue, R 'is 4,
4'-diaminodiphenyl ether residue, n is a natural number. The polyimide having the structure of the formula (I) comprises pyromellitic dianhydride and 4,4′-diaminodiphenyl ether,
It is obtained by condensation polymerization in an organic solvent in the presence of a catalyst and a dehydrating agent.

In the present invention, it is preferable to use pyromellitic dianhydride alone as the aromatic tetracarboxylic dianhydride, but if it is 40 mol% or less, another aromatic tetracarboxylic dianhydride may be used. Can be used together. Aromatic tetracarboxylic dianhydrides that can be used in combination with pyromellitic dianhydride include 2,3,6,7-naphthalenetetracarboxylic dianhydride and 3,3 ′, 4,4′-diphenyltetracarboxylic acid Dianhydride, 2,2'-bis (3,4-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, 3,4,9,10-perylenetetracarboxylic Acid dianhydride, bis (3,4-carboxyphenyl) ether dianhydride, naphthalene-1,2,4,5-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride Anhydride, decahydro-naphthalene-1,4,5,8-tetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,7-hexahydronaphthalene-1,2,5,6- Tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,4,5,
8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride,
Phenanthrene-1,8,9,10-tetracarboxylic dianhydride, 2,2-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) Ethane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, Benzene-1,2,3,4-tetracarboxylic dianhydride, 3,4,3 ′, 4′-benzophenonetetracarboxylic dianhydride, or a mixture of two or more of these.

As the aromatic diamine, 4,4 ′
It is preferable to use -diaminodiphenyl ether alone, but other aromatic diamines can be used in combination as long as the content is 40 mol% or less. Aromatic diamines that can be used in combination with 4,4′-diaminodiphenyl ether include metaphenylenediamine, paraphenylenediamine, 4,4′-diaminodiphenylpropane, 4,4′-diaminodiphenylmethane, benzidine, 4,4′-diaminodiphenyl Sulfide, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 2,6-diaminopyridine,
Bis- (4-aminophenyl) diethylsilane, bis- (4
-Aminophenyl) diphenylsilane, 3,3'-dichlorobenzidine, bis- (4-aminophenyl) ethylphosphine oxide, bis- (4-aminophenyl) phenylphosphine oxide, bis- (4-aminophenyl)-
N-phenylamine, bis- (4-aminophenyl) -N
-Methylamine, 1,5-diaminonaphthalene, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,4'-dimethyl-
3 ', 4-diaminobiphenyl, 3,3'-dimethoxybenzidine, 2,4-bis (beta-amino-t-butyl) toluene, bis (para-beta-amino-t-butyl-phenyl) ether, para -Bis- (2-methyl-4-amino-bentyl) benzene, para-bis- (1,1-dimethyl-5-amino-bentyl) benzene, m-xylylenediamine, p-xylylenediamine, 1,3 -Diaminoadamantane, 3,3'-diamino-1,1'-diadamantane, 3,
3'-diamino-1,1'-diadamantane, bis (para-amino-cyclohexyl) methane, hexamethylenediamine, peptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, 3
-Methylheptamethylenediamine, 4,4-dimethylheptamethylenediamine, 2,11-diamino-dodecane, 1,2
-Bis- (3-amino-propoxy) ethane, 2,2-dimethylpropylenediamine, 3-methoxy-hexamethylenediamine, 2,5-dimethylhexamethylenediamine, 5-methylnonamethylenediamine, 5-methylnonamethylenediamine , 1,4-diamino-cyclohexane,
1,12-diamino-octadecane, 2,5-diamino-1,3,
4-oxadiazole, 2,2-bis (4-aminophenyl) hexafluoropropane, N- (3-aminophenyl) -4-aminobenzamide, 4-aminophenyl-
3-aminobenzoate and the like.

The organic solvent used for the condensation polymerization of the polyimide in the present invention includes N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, N, N-diethylacetamide, -With dimethylmethoxyacetamide, N-methyl-caprolactam, dimethylsulfoxide, N-methyl-2-pyrrolidone, tetramethylurea, pyridine, dimethylsulfone, hexamethylphosphoramide, tetramethylenesulfone, formamide, N-methylformamide and butyrolactone is there. These organic solvents can be used alone or in combination of solvents, or in combination with a solvent having poor solvent properties such as benzene, benzonitrile, dioxane, butyrolactone, xylene, toluene and cyclohexane.

As the catalyst, tertiary amines are preferably used. Specific examples of these amines include trimethylamine, triethylamine, triethylenediamine, and the like.
Pyridine, isoquinoline, 2-ethylpyridine, 2-methylpyridine, N-ethylmorpholine, N-methylmorpholine, diethylcyclohexylamine, N-dimethylcyclohexylamine, 4-benzoylpyridine,
2,4-lutidine, 2,6-lutidine, 2,4,6-collidine,
3,4-lutidine, 3,5-lutidine, 4-methylpyridine, 3-methylpyridine, 4-isopropylpyridine,
N-dimethylbenzylamine, 4-benzylpyridine,
And N-dimethyldodecylamine.

Examples of the dehydrating agent include organic carboxylic acid anhydrides, N, N-dialkylcarbodiimides, lower fatty acid halides, halogenated lower fatty acid halides, halogenated lower fatty acid anhydrides, arylphosphonic dihalides and thionyl halides. Is mentioned.

Here, the organic carboxylic acid anhydrides include acetic anhydride, propionic anhydride, butyric anhydride, valeric anhydride, anhydrides thereof mixed with each other, and aromatic monocarboxylic acids such as benzoic acid and naphthoic acid. And mixtures thereof with anhydrides of carbonic acid and formic acid and fatty acid ketene (ketene and dimethylketene). Among them, the use of acetic anhydride and ketene is preferable.

In addition to benzoic anhydride, other aromatic anhydrides which can be used include o-, m- and p-toluic acid, m-
-And p-ethylbenzoic acid, p-propylbenzoic acid, p
-Isopropylbenzoic acid, anisic acid, o-, m- and p
-Nitrobenzoic acid, o-, m- and p-halobenzoic acid,
Various dibromo and dichlorobenzoic acids, tribromo and trichlorobenzoic acids, isomers of dimethyl benzoic acid such as hemelicylic acid, 3,4-xylylic acid, isoxylylic acid and mesitylene acid, veratric acid, trimethoxybenzoic acid, alpha and beta naphthoic acid, Mixed anhydrides of the above anhydrides and mixed anhydrides of fatty acids and monocarboxylic acids such as acetic acid and propionic acid; and mixed anhydrides of carbonic acid and formic acid. Things.

The N, N'-dialkylcarbodiimides are represented by the formula: RN = C = NR, where R can be different alkyl groups, but are generally the same, preferably Groups are 1 to 8
Is a lower alkyl group of carbon atoms.

Halogen-containing dehydrating agents include acetyl chloride, acetyl bromide, acetyl iodide and acetyl fluoride, propionyl chloride, collected propionyl, propionyl iodide, and propionyl fluoride, isobutyryl chloride, isobutyryl bromide, n-chloride -Butyryl, n-butyryl bromide, valeryl chloride, mono-chloride, di- and tri-chloroacetyl chloride, bromoacetyl bromide, chloroacetic anhydride,
Examples include phenylphosphonic dichloride, thionyl chloride, thionyl bromide, thionyl fluoride and thionyl chlorofluoride, and trifluoroacetic anhydride.

The resulting polyamic acid solution is extruded in a cast or film form, and dried and heat-treated.
The imidization proceeds and a polyimide film having the structure of the above formula (I) is obtained.

The drying and heat treatment is performed by subjecting the polyamic acid solution cast or extruded to a film shape to 200 to 550.
It can be achieved by passing through a dry heat treatment zone maintained in a high temperature atmosphere at 250C, preferably 250 to 500C.

In the present invention, the film thickness is 5 to 150.
It is necessary to adjust the thickness to be μm, preferably 7 to 125 μm.

In the present invention, the obtained polyimide film is continuously subjected to a heat treatment with hot air while applying a tension of 1 to 10 kg / m in a longitudinal direction of the film, and then subjected to a cooling treatment.

If the tension in the longitudinal direction is less than 1 kg / m, the film will be wrinkled and meandered during continuous winding, making it difficult to commercialize the film. The film cannot be obtained. The preferred range of the tension is 2 kg / m to 7 kg / m.

The heat source for the heat treatment is hot air, which is blown onto the film surface to impart low shrinkage to the film.

It is also possible to use a radiation heater in addition to the hot air.

The heat treatment temperature is preferably from 300 to 500 ° C, more preferably from 350 to 450 ° C. Further, the processing time is preferably about 1 second to 10 minutes. If the treatment time is longer than this, it is not preferable because the properties such as the flatness of the film are deteriorated.

[0034]

Example 1 An equimolar amount of pyromellitic dianhydride and 4,4'-diaminodiphenyl ether were placed in N, N-dimethylformamide and the reaction was allowed to proceed with stirring to obtain a polyamic acid solution.

After adding acetic anhydride and isoquinoline to the polyamic acid solution and stirring, the solution is extruded on a heated support, converted into a polyimide to form a self-supporting film, peeled from the support, and further removed to an imide. Was completed, the solvent was dried, and the resultant was rolled up into a roll of a polyimide film having a thickness of 25 μm. This polyimide film is continuously fed into a tunnel type hot blast stove,
It was wound up while cooling to room temperature. The film tension during the heat treatment was adjusted by the difference in rotation speed between the feed roller and the take-up roller, and the heat treatment time was adjusted by the relative rotation speed of each roller.

The shrinkage of the film after heat treatment and cooling was determined by treating the sample at 350 ° C. for 30 minutes,
It was calculated as a shrinkage ratio in the length direction (MD) and the width direction (TD). The measuring method conformed to JPCA-BM01-1988.

Table 1 shows the obtained results.

[0038]

[Table 1] As a comparison, experiments at 0 kg / m and 0.5 kg / m were performed, and although the heat shrinkage rate was excellent in each case, the film was wavy and it was difficult to continuously wind the film. .

Example 2 Pyromellitic dianhydride and 4,4'- as diamine component
Diaminodiphenyl ether (70 mol%) and p-
Phenylenediamine (30 mol%) and N,
The polyamic acid solution was obtained by allowing the reaction to proceed while stirring in N-dimethylformamide.

Acetic anhydride and isoquinoline were added to the polyamic acid solution, and the mixture was stirred. The solution was extruded on a heated support, converted into a polyimide to form a self-supporting film, peeled from the support, and further separated into an imide. Was completed, and dried and heat-treated by passing through a drying heat treatment zone at 250 to 450 ° C., and wound into a roll as a 25 μm-thick polyimide film. This polyimide film was continuously fed into a tunnel type hot blast stove and wound up while cooling to room temperature. The film tension during the heat treatment was adjusted by the difference in rotation speed between the feed roller and the take-up roller, and the heat treatment time was adjusted by the relative rotation speed of each roller.

The shrinkability of the film after heat treatment and cooling was determined by treating the sample at 350 ° C. for 30 minutes,
It was calculated as a shrinkage ratio in the length direction (MD) and the width direction (TD). The measuring method conformed to JPCA-BM01-1988.

Table 2 shows the obtained results.

[0043]

[Table 2] In addition, for comparison, experiments were performed with tensions of 0 kg / m and 0.5 kg / m.
The film was wavy and difficult to wind continuously.

[0044]

According to the production method of the present invention, the low-shrinkage polyimide film is prepared by applying a tension of 1 to 10 kg / m in the longitudinal direction and continuously treating it with hot air. The film shape is better than that of heat treatment below, and continuous processing is possible.

Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court II (Reference) // B29K 79:00 105: 02 C08L 79:08

Claims (2)

[Claims] A polyamic acid solution obtained by polymerizing pyromellitic dianhydride and 4,4′-diaminodiphenyl ether in an organic solvent is cast or extruded into a film,
A low-shrinkage polyimide film obtained by subjecting a polyimide film obtained by drying and heat treatment to heat treatment with hot air continuously while applying a tension of 1 to 10 kg / m in the length direction of the film, and then to cooling treatment. Manufacturing method. 2. A catalyst and a dehydrating agent are added to a polyamic acid solution obtained by polymerizing pyromellitic dianhydride and 4,4′-diaminodiphenyl ether in an organic solvent, and the resultant is cast or formed into a film. Extrusion, drying, heat treatment polyimide film obtained in the length direction of the film 1 to 1
A method for producing a low-shrinkage polyimide film, which is subjected to heat treatment with hot air continuously while applying a tension of 0 kg / m, and then to cooling treatment.