JP3020174B2 - Low shrinkage polyimide film - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a low-shrinkage polyimide film having improved heat shrinkability.

[Conventional technology]

A polyimide obtained by polycondensing an aromatic tetracarboxylic dianhydride and an aromatic diamine is known as a polymer having extremely excellent heat resistance.

Although this polyimide is insoluble in a solvent, its precursor polyamic acid is soluble in a specific organic solvent,
The heat-resistant film is obtained by casting and drying the polyamic acid organic solvent solution simultaneously with imidization.

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.

[Problems to be solved by the invention]

In order to make a flexible printed circuit board using a polyimide film as a base film, it is necessary to laminate a metal foil such as copper or attach a metal by vacuum evaporation, sputtering, or the like. Dimensional stability 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 means for responding to such demands, Japanese Patent Application Laid-Open No. 62-4102
No. 4 discloses a polyimide film under substantially no tension,
A method of cooling after heating in a heating oven has been proposed.

The method of heat treatment under no tension relaxes latent shrinkage stress,
This is an effective method because shrinkage is reduced by subsequent heating, but has the following disadvantages.

That is, in order to perform heat treatment without tension, a method in which a roll wound with a film is left in a heating oven (Japanese Patent Laid-Open No. Sho 62-62).
There is a method in which a film is continuously processed in a continuous heating furnace equipped with an unwinding and winding machine. However, in any case, the film is processed under no tension for a long time. The film becomes wavy, causing 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, and there is a disadvantage that the film cannot be used as a base film for a precision printed circuit board.

In addition, these methods have a problem in that the low shrinkage effect varies, for example, in a portion where wrinkles occur, the heat shrinkage in the MD direction and the TD direction greatly fluctuates.

The present invention solves the above-mentioned disadvantages of the prior art, and has low shrinkage,
It is another object of the present invention to provide a polyimide film having good product production efficiency.

[Means for solving the problem]

 In order to solve the above problems, the present invention takes the following measures.

That is, the low-shrinkage polyimide film of the present invention is obtained by polymerizing pyromellitic dianhydride and 4,4'-diaminodiphenyl ether in an organic solvent, casting or extruding a polyamic acid solution into a film, and drying. The heat-treated polyimide film is tensioned by 1k in the longitudinal direction of the film.
g / m, 10 kg / m or less, and then heat-treated, followed by cooling, and the shrinkage after heat treatment at 200 ° C for 1 hour is 0.05
% Or less.

The polyimide in the present invention mainly has a structure of the following formula (I).

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

(Where R is a pyromellitic dianhydride residue and R 'is 4,4
-Diaminodiphenyl ether residue, n is a natural number. The polyimide having the formula (I) can be obtained by polycondensing pyromellitic dianhydride with 4,4'-diaminodiphenyl ether in an organic solvent.

In the present invention, it is preferable to use pyromellitic dihydrate alone as the acid component, but other aromatic tetracarboxylic dihydrates can be used in combination if it is 40 mol% or less. Acid components that can be used in combination include 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3 ′, 4,4′-diphenyltetracarboxylic dianhydride, 1,2,5,6 -Naphthalenetetracarboxylic dianhydride, 2,2 ', 3,3'-diphenyltetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, bis ( 3,4-dicarboxyphenyl) sulfone dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, naphthalene-1, 2,4,5-
Tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, decahydro-naphthalene-1,
4,5,8-tetracarboxylic dianhydride, 4,8-dimethyl-1,
2,3,5,6,7-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 )
Propane dianhydride, 1,1-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, and the like, or a mixture of two or more thereof.

As the diamine component, it is preferable to use 4,4'-diaminodiphenyl ether alone.
If it is below, other aromatic diamines can be used in combination. Examples of the diamine component that can be used in combination include metaphenylenediamine, para-phenylenediamine, and 4,4'-
Diamino-diphenylpropane, 4,4'-diamino-diphenylmethane, benzidine, 4,4'-diamino-diphenylsulfide, 4,4'-diamino-diphenylsulfone, 3,3'-diamino-diphenylsulfone, 2,6-
Diamino-pyridine, bis- (4-amino-phenyl)
Diethylsilane, bis- (4-amino-phenyl) diphenylsilane, 3,3'-dichloro-benzidine, bis-
(4-amino-phenyl) ethylphosphoxide, bis- (4-amino-phenyl) phenylphosphoxide, bis- (4-amino-phenyl) -N-
Phenylamine, bis- (4-amino-phenyl) -N
-Methyl-amine, 1,5-diamino-naphthalene, 3,3 '
-Dimethyl-4,4'-diamino-biphenyl, 3,4'-dimethyl-3 ', 4-diamino-biphenyl, 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-pentyl) benzene, para-bis-
(1,1-dimethyl-5-amino-pentyl) benzene,
m-xylylenediamine, p-xylylenediamine, 1,
3-diaminoadamantane, 3,3'-diamino-1,1'-
Diadamantane, 3,3'-diaminomethyl-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, 2,5-dimethylheptamethylenediamine, 5-methylnonamethylenediamine, 1,4
-Diamino-cyclohexane, 1,12-diamino-octadecane, 2,5-diamino-1,3,4-oxadiazole, 2,
Examples include 2-bis (4-aminophenyl) hexafluoropropane, N- (3-aminophenyl) -4-aminobenzamide, 4-aminophenyl-3-aminobenzoate, or a mixture of two or more thereof.

Next, as the organic solvent used for the condensation polymerization of the polyimide in the present invention, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, N, N-
Diethylacetamide, N-dimethylmethoxyacetamide, N-methyl-caprolactam, dimethylsulfoxide, N-methyl-2-pyrrolidone, tetramethylurea, pyridine, dimethylsulfone, hexamethylphosphoramide, tetramethylenesulfone, formamide, N
-Methylformamide and butyrolactone. These organic solvents may be used alone or in combination, or may be benzene, benzonitrile, dioxane, butyrolactone,
It can be used in combination with less solvent solvents such as xylene, toluene and cyclohexane.

As the catalyst, tertiary amines are preferably used, and specific examples of these amines include trimethylamine, triethylamine, triethylenediamine, pyridine, isoquinoline, 2-ethylpyridine, 2-methylpyridine, triethylamine, N-ethylmorph. Olin, N-
Methyl morpholin, 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 Examples include methylpyridine, 4-isopropylpyridine, N-dimethylbenzylamine, 4-benzylpyridine, and N-dimethyldodecylamine.

Further, as a dehydrating agent, organic carboxylic anhydride, N,
N'-dialkylcarbodiimides, lower fatty acid halides, halogenated lower fatty acid halides, halogenated lower fatty acid anhydrides, arylphosphonic dihalides and thionyl halides.

Here, as the organic carboxylic anhydride, acetic anhydride, propionic anhydride, butyric anhydride, valeric anhydride, anhydrides thereof mixed with each other and aromatic monocarboxylic acids such as benzoic acid, naphthoic acid, etc. And a mixture with carbonic acid and formic acid and anhydrides of aliphatic ketene (ketene and dimethylketene). Of these, acetic anhydride and ketene are preferred.

In addition to benzoic anhydride, other aromatic anhydrides which may 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 trichloro benzoic acid, 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, and biphenylcarboxylic acid. Acid anhydrides and mixed anhydrides of the above anhydrides and mixed anhydrides of fatty acid monocarboxylic acids with anhydrides such as acetic acid and propionic acid, and mixed anhydrides with carbonic acid and formic acid anhydrides.

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

Dehydrating agents containing halogen include acetyl chloride, acetyl bromide, acetyl iodide and acetyl fluoride, propionyl chloride, propionyl bromide, propionyl iodide and propionyl fluoride, isobutyryl chloride, isobutyryl bromide, n-butyryl chloride, N-butyryl bromide, valeryl chloride, mono-, di- and tri-chloroacetyl chloride, bromoacetyl bromide, chloroacetic anhydride, phenylphosphonic dichloride, thionyl chloride, thionyl bromide, thionyl fluoride and thionylchloro Fluoride and trifluoroacetic anhydride.

The resulting polyamic acid solution is cast or extruded in the form of a film, and is dried and heat-treated in the presence of the catalyst and the dehydrating agent, whereby imidization proceeds and the polyimide film having the structure of the formula (I) is dried and dried. Heat treatment is
Polyamide acid solution cast or extruded into film
This can be achieved by passing through a dry heat treatment zone maintained at a high temperature atmosphere of 200 to 550 ° C, preferably 250 to 500 ° C.

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

In the present invention, the obtained polyimide film is subjected to heat treatment at a relatively low temperature and in a relatively short time while maintaining the tension in the longitudinal direction of the film at 1 kg / m or more and 10 kg / m or less.

The lower the tension, the lower the shrinkage of the film.
Especially under complete tension, especially when performing continuous winding, the film is meandering, and the variation in heat shrinkage tends to be large.Therefore, it is preferably 1 kg / m or more. Cannot be obtained.

As a heating means, a method of irradiating far infrared rays or a method of blowing hot air is preferable. The polyimide film has an absorption peak in the far-infrared region, and is heated in a very short time by irradiating far-infrared rays including this absorption wavelength.

Further, in addition to far-infrared irradiation and hot air blowing, a radiation heater can be used in combination, and a heat treatment can be performed using only the radiation heater.

The heating time in the heat treatment may be short, preferably 1 to 60 seconds, particularly 2 to 30 seconds is sufficient.

The heat treatment temperature is not particularly limited, but is 70-300 ° C.
Particularly, 100 to 230 ° C is preferable.

The polyimide film of the present invention thus obtained has a shrinkage rate of 0.05% in both the film length direction (MD) and the width direction (TD) after heat treatment at 200 ° C. for 1 hour.
It has the following highly practical characteristics.

〔Example〕

Hereinafter, the effects of the present invention will be specifically described with reference to examples.

Example 1 Pyromellitic dianhydride was prepared by equilibrating 4,4'-diaminodiphenyl ether in N, N-dimethylacetamide and agitating the reaction to obtain a polyamic acid solution.

Acetic anhydride and isoquinoline were added to this polyamic acid solution, and the mixture was stirred. The solution was extruded on a heated support, converted to a polyimide to form a self-supporting film, peeled from the support, and further converted to 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 polyimide film having a thickness of 25 μm.

This polyimide film was continuously fed into a tunnel-type infrared irradiation furnace at the temperature shown in Table 1, heat-treated under the conditions shown in Table 1, and then cooled to room temperature while being wound up outside the furnace. 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.

 Table 1 shows the results.

Example 2 A polyimide film having a thickness of 125 μm was obtained in the same manner as in Example 1. This was fed into a tunnel-type infrared irradiation furnace at 230 ° C., heat-treated for 30 seconds at the treatment tension shown in Table 2, and then cooled to room temperature.

 Table 2 shows the evaluation results of the heat shrinkage of the obtained film.

(Effect of the Invention) The polyimide film of the present invention has a tension in the length direction of 10
Since the film is obtained by performing a heat treatment at a relatively low temperature for a short time while keeping it at or below kg / m, the heat treatment efficiency is excellent, and the film does not generate waving or wrinkles, and can be made continuous.

In addition, the polyimide film of the present invention has excellent shrinkage after heat treatment at 200 ° C. for 1 hour in both the MD and TD directions of 0.05% or less, and is useful for applications such as flexible printed circuit boards.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-264027 (JP, A) JP-A-61-264028 (JP, A) JP-A-57-109613 (JP, A) 41024 (JP, A) JP-A-1-198638 (JP, A) JP-A-57-178831 (JP, A) JP-A-60-190314 (JP, A) JP-A-63-230320 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 71/02 B29C 41/12 C08J 7/00 301

Claims (1)

(57) [Claims] 1. A polyimide obtained by casting or extruding a polyamic acid solution obtained by polymerizing pyromellitic dianhydride and 4,4'-diaminodiphenyl ether in an organic solvent, drying and heat-treating the polyamic acid solution. The film is heat-treated while maintaining the tension in the length direction of the film at not less than 1 kg / m and not more than 10 kg / m, and then subjected to a cooling treatment to reduce the shrinkage after heat treatment at 200 ° C. for 1 hour to 0.05% or less. Shrinkable polyimide film.