JPH0355232A - Lowshrinkable polyimide film - Google Patents

Abstract

PURPOSE:To attempt to improve shrinking properties to heat by performing a heat-treatment for a short time by irradiating a film with far IR rays while a specified tension or lower is applied in the longitudinal direction of a film and then performing a cooling treatment. CONSTITUTION:While a tension of 1-10kg/m or lower is applied in the longitudinal direction of a film, a heating treatment is performed for a short time by irradiating a film with far IR rays and then cooling treatment is performed. This polyimide is obtd. by performing polycondensation of an arom. tetracarboxylic dianhydride and an arom. diamine in an org. solvent in the presence of a catalyst and a dehydrating agent. By holding a tension of 1-10kg/m or less in the longitudinal direction to a polyimide film and treating the film by irradiating it with IR rays like this, a polyimide film with good heat efficiency and exhibiting a low shrinkage factor is obtd. and it is a useful material for a flexible printed base.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a low-shrinkage polyimide film with improved heat-shrinkability.

[Prior Art] Polyylide obtained by polycondensation of aromatic tetracarboxylic dianhydride and aromatic diamine is known as a polymer with extremely excellent heat resistance. This polyester is insoluble in solvents, but its precursor, polyamic acid, is soluble in specific organic solvents. A heat-resistant film is obtained.

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

[Problem 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 metal foil such as copper or to attach metal by vacuum evaporation, sputtering, etc. Since a considerable amount of heat is applied to the material, dimensional stability against heat is required.

In particular, with the recent trend toward fine patterning of flexible printed circuit boards, polyimide films that shrink less due to heat are desired.

As a means to meet such demands,
Japanese Patent No. 024 proposes a method in which a boiled ξ-d film is heat-treated in a heating oven under substantially no tension, and then cooled.

The method of heat treatment under no tension is an effective method because it relieves latent shrinkage stress and shrinkage becomes smaller with respect to subsequent heating, but it has the following drawbacks.

That is, in order to perform heat treatment under no tension, a method is disclosed in which a roll of film is left in a heating oven (Japanese Unexamined Patent Publication No. 1986-62-1).
41024 (example)) or there is a method of continuously processing the film in a continuous heating furnace equipped with an unwinding and winding machine, but in either case, the film must be processed for a long time under no tension. The problem arises that the film becomes wavy and the heat shrinkage rate varies. Particularly in the case of continuous processing, the disadvantage arises that the film meanderes, making it impossible to obtain a complete roll of product.

Furthermore, even if the film is left in a dryer in batch mode, wrinkles cannot be prevented from forming on the surface of the film, which has the drawback that it cannot be used as a base film for precision printed circuit boards.

It is an object of the present invention to overcome the drawbacks of the above-mentioned prior art and to provide a polyimide film that has low shrinkage and is highly efficient in product production. [Means for Solving the Problems] In order to solve the above problems, the present invention takes the following measures.

That is, the low-shrinkage polyamide straw film of the present invention is obtained by maintaining the tension in the longitudinal direction of the film at 10 kg/m or less, heating it for a short time by irradiating it with far infrared rays, and then cooling it. It is characterized by this.

The polyimide in the present invention mainly has the structure of the following formula (1).

OO 11]1 The structure of (1) 2 is a ring-closed precursor of (II) 2 below.

(Margins below this page) 00 l1) 1? Here, R is a tetravalent aromatic group, and R' is a divalent aromatic group. ) (I) The polyimide having the structure 2 is obtained by mixing an aromatic tetracarboxylic dianhydride and an aromatic diamine in an organic solvent.
Obtained by polycondensation in the presence of a catalyst and a dehydrating agent.

Examples of the aromatic tetracarboxylic dianhydride used in the present invention include pyromellitic dianhydride, 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)brovani anhydride, bis(3,4-
dicarboxyphenyl) sulfone dianhydride, 3.4,9
．． 10-Berylenetetracarboxylic dianhydride, bis(3
．． 4-dicarboxyphenyl)ether dianhydride, naphthalene-1.2.4. 5-tetracarboxylic dianhydride, naphthalene-1,4,5.8-tetracarboxylic dianhydride, decahydronaphthalene-1.4,5. 8-tetracarboxylic dianhydride, 4,8-dimethyl-1.2,3
．． 5,6. 7-Hexahydride naphthalene-1.2.5
．． 6-tetracarboxylic dianhydride, 2.6-dichloronaphthalene-1.45.8-tetracarboxylic dianhydride, 2.7-dichloronaphthalene-1.4,5. 8-tetracarboxylic dianhydride, 2.3,6. 7-tetrac-naphthalene-1.4,5. 8-tetracarboxylic dianhydride, phenanthrene-1.8,9.10-tetracarboxylic dianhydride, 2.2-bis(2,3-dicarboxyphenyl)fluorane di=water s, t. i-bis (2.
3-dicarboxyphenyl)ethane dianhydride, 1.1-
Bis(3,4-dicarboxyphenyl)ethanihydride, bis(2,3-dicarboxyphenyl)methanihydride, bis(3,4-dicarboxyphenyl)methanihydride, bis(3.4-dicarboxyphenyl)methanihydride -dicarboxyphenyl) sulfone dianhydride, benzene-1.2, 3.4-tetracarboxylic dianhydride, 3,4.3', 4'-benzophenonetetracarboxylic dianhydride, or these 2
Although mixtures of more than one species may be mentioned, use of biromellitic dianhydride is particularly preferred.

Examples of aromatic diamines include metaphenylene diamine, paraphenylene diamine, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylmethane, benzidine, and 4,4'-diaminodiphenylpropane. diphenyl sulfide, 4,4'-diaminodiphenylsulfone, 3,3'diaminodiphenylsulfone,
4.4'-Diaminodiphenyl ether, 2,6-diaξnobilidine, 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-
Methyl-amine, l15-diaminonaphthalene, 3.
3-dimethyl-4,4'-dia≧nobiphenyl, 3.
4'-dimethyl-3',4-diaminobiphenyl, 3
．． 3'-dimethoxybenzidine, 2,4-bis(beta-amino-t-butyl)toluene, bis(valavator axinot-t-butyruphenyl)ether, valar bis-(2-methyl-4-aminopentyl) benzene,
Barrabis-(1,1-dimethyl-5-aminopentyl)benzene, m-xylylenediamine, p-xylylenediamine, 1,3-diaminoadamantane, 3,3'
-Diamino-1,1-diadamantane, 3.3'-diaminomethyl-1.1'-diadamantane, bis(para-aminohexyl)methane, hexamethylene diamine, beptamethylene diamine, octamethylene diamine, nonamethylene diamine 2, decamethylene diamine,
3-methylhebutamethylene diamine, 4,4-dimethylhebutamethylene diamine, 2,l1-diaminodecane, 12-bis-(3-anobroboxy)ethane,
2,2-dimethylpropylenediamine, 3-methoxyhexamethylenediamine, 2.5-dimethylhexamethylenediamine, 2.5-dimethylhexamethylenediamine, 5-methylnonamethylenediamine, 1,4-dia ξNocyclohexane, 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-aξnobenzoate, or two or more of these) Among them, 4,4'-diaminodiphenyl ether is preferably used.

Next, the organic solvents used in the polycondensation of polyimide in the present invention include N,N-dimethylformamide, N,N-
Dimethylacetamide, N,N-diethylformamide, N. N-diethylacetamide, N-dimethylmethoxyacetamide, N-methylcabrolactam, dimethylsulfoxide, N-methyl-2-pyrrolidone, tetramethylurea, pyridine, dimethylsulfone, hexamethylphosphoramide, tetramethylene Sulfone, formamide, N-methylformamide and butyrolactone. These organic solvents can be used alone or in combination, or in combination with less solvent solvents such as benzene, penzonitrile, dioxane, butyrolactone, xylene, toluene, and cyclohexane.

As a catalyst, it is preferable to use tertiary amines, and specific examples of these amines include trimethylamine, triethylamine, triethylenediamine, pyridine, isoquinoline, 2-ethylpyridine, 2-methylpyridine,
1. ethylamine, N-ethylmorpholine, N-methylmorpholine, diethylcyclohexylamine, N
-dimethylcyclohexyluane, 4-benzoylpyridine, 2,4-lutidine, 2,6-lutidine, 2,4.
6-collidine, 3,4-lutidine, 3,5-lutidine,
Examples include 4-methylpyridine, 3-methylpyridine, 4-isopropylbyridine, N-dimethylbenzylamine, 4-benzylpyridine, and N-dimethyldodecylamine.

Furthermore, as a dehydrating agent, organic carboxylic acid anhydride, N,
Examples include N'-dialkyl luposiimides, lower fatty acid halides, halogenated lower fatty acid halides, halogenated lower fatty acid anhydrides, arylphosphonic acid dihalides, and thionyl halides.

Here, examples of organic carboxylic anhydrides include acetic anhydride, propionic anhydride, butyric anhydride, valeric anhydride, anhydrides in which these are mixed with each other, and anhydrides of aromatic monocarboxylic acids such as benzoic acid and naphthoic acid. Examples include mixtures with carbonic acid and formic acid and anhydrides of aliphatic ketenes (ketene and dimethylketene), among which acetic anhydride and ketenes are preferably used.

Besides benzoic anhydride, other aromatic anhydrides that may be used include o-, m- and p-toluic acid, m- and p-ethylbenzoic acid, p-propylbenzoic acid, p-isobrobyl benzoic acid. , anisic acid, 0-, m- and p-nitrobenzoic acid, 0-, m- and p-halobenzoic acid, various dibromo- and dichlorobenzoic acids, tribromo- and trichlorobenzoic acid, isomers of dimethylbenzoic acid such as hemerityl. acid,
Anhydrides of acids such as 3,4-xylylic acid, isoxylylic acid and mesitylenic acid, veratrum acid, trimethoxybenzoic acid, alpha-1 and beta-naphthoic acid, and biphenylcarboxylic acid, and mixed anhydrides of the above-mentioned anhydrides and Examples include mixed anhydrides of fatty acid monocarboxylic acids, such as acetic acid and propionic acid, and mixed anhydrides with carbonic acid and formic acid anhydrides.

N. N'-dialkyl luposiimides have the formula: R-
N=C-N-R (wherein R can be different alkyl groups but are generally the same), preferably the R group is a lower alkyl group of 1 to 8 carbon atoms .

Dehydrating agents containing halogens include acetyl chloride, acetyl bromide, acetyl iodide and acetyl fluoride, probionyl chloride, propionyl bromide, probionyl iodide and brobionyl fluoride, isobutyryl chloride, isobutyryl bromide, n chloride.
-butyryl, n-butyryl bromide, valeryl chloride, mono-di- and trichloroacetyl chloride, promoacetyl bromide, chloroacetic anhydride, phenylphosphonic dichloride, thionyl chloride, thionyl bromide, thionyl fluoride and thionyl chloride fluoride , and trifluoroacetic anhydride.

The resulting boria acid solution is cast or extruded into a film, dried and heat treated to advance imidization and yield a polyimide film having the structure of formula (1).

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

In the present invention, the obtained polyimide film is heat-treated for a short time by irradiating it with far infrared rays while maintaining the longitudinal tension of the film at 10 kg/m or less. The lower the tension, the lower the shrinkage of the film.However, under no tension, the film tends to meander, especially when continuous winding is performed, so it is preferably 1 kg/m or more, and more than 10 kg/rn. In this case, it becomes impossible to obtain a film with low heat shrinkage, which is the object of the present invention.

The means of heating is irradiation with far infrared rays. A polyimide film has an absorption peak in the far infrared region, and by irradiating it with far infrared rays that include this absorption wavelength, it can be heated in an extremely short time.

The far-infrared heater is not particularly limited, but a ceramic heater is preferred. In addition to far-infrared irradiation, hot air can also be used in combination.

In the present invention, by using far infrared rays, the heating time may be extremely short, preferably 1 to 60 seconds, and more preferably 2 to 30 seconds.

The heat treatment temperature is not particularly limited, but is preferably 180 to 470°C, preferably 200 to 450'C.

[Example] Hereinafter, the effects of the present invention will be specifically explained with reference to Examples.

In addition, the heat shrinkage rate in the examples indicates the shrinkage rate (%) in the length direction (MO) and width direction (TD) of the film after processing the film sample at 350 ° C for 30 minutes.
This value is 0. When it is less than 1%, it becomes extremely practical. The measurement method was based on JPCA-BMOIl988.

Example 1 Biromellitic dianhydride and 4,4-diaminodiphenyl ether were placed in equal moles in N,N-dimethylacetate and the reaction proceeded with stirring to produce boria ξ.
An acid solution was obtained.

After adding acetic anhydride and isoquinoline to this polyamic acid solution and stirring, the solution was extruded onto a heating support to convert it into polyimide and form a self-supporting film, which was then peeled off from the support and further applied to the imido. Upon completion of the conversion reaction, the solvent was dried, and a polyimide film having a thickness of 25 μm was wound up into a roll.

This polyimide film was continuously fed into a tunnel-type infrared irradiation furnace at the temperatures shown in Table 1, heat-treated under the conditions shown in Table 1, and then cooled to room temperature while being rolled up outside the furnace. The film tension during heat treatment was adjusted by the difference in rotational speed between the feed roller and take-up roller, and the heat treatment time was set at 11 intervals depending on the relative rotational speed of each roller.

Table 1 shows the evaluation results of the hot water shrinkage rate of the obtained film.

(Margins below this page) Table 1 For comparison, the tension was 0.5 kg/m and the temperature was 260 kg/m.
A similar experiment was conducted at °C, but the film was wavy and difficult to wind up continuously.

Example 2 A polyimide film having a thickness of 125 μm was obtained in the same manner as in Example 1. This was sent into a tunnel-type infrared irradiation furnace at 250''C, heat-treated for 30 seconds at the treatment tension shown in Table 2, and then cooled to room temperature.

Table 2 shows the results of evaluating the heat shrinkage rate of the obtained film.

Table 2 [Effects of the invention] The present invention can reduce the tension in the longitudinal direction of the polyimide film to 10k.
g/m or less and heat-treated by irradiating with infrared rays, the heating efficiency is extremely high and a low-shrinkage rate polyamide film can be obtained in a short period of time. Also obtained Bolii ξ
The shrinkage rate of the film is 0 after processing at 350°C for 30 minutes.
．． 1% or less, and a material useful for flexible printed circuit boards etc. can be obtained.

Claims (1)

[Claims] Keep the tension in the length direction of the film below 10 kg/m,
A low-shrinkage polyimide film that is made by heating it for a short time by irradiating it with far infrared rays, and then cooling it.