JPH0940775A - Polyimide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyimide film having all of good flexibility, strength, heat resistance and heat fusibility by forming a film from a polyimide consisting of specified imide units and terminal groups. SOLUTION: This polyimide film is composed mainly of a polyimide consisting of 80-100mol% imide units of formula I and 20-0mol% imide units of formula II (R and R' respectively are a tetravalent and divalent aromatic or aliphatic group) and having a polymer terminal comprising a tetracarboxylic acid anhydride residue or having the amine terminal blocked with a dicarboxylic acid anhydride. A solution of a polyamic acid or polyimide is cast on the surface of a support and heated to a temperature higher than the glass transition temperature of polymide and equal to the cure temperature thereof, i.e., 270-350 deg.C, to effect ring-closing through dehydration and remove the solvent, thus giving a film of a polyimide having an inherent viscosity <=inh of 0.3-3dl/g.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyimide film, and more particularly to a polyimide film having flexibility, strength, heat resistance and heat fusion property.

[0002]

2. Description of the Related Art Polymer having both heat resistance and adhesiveness
As such, polyimide-based and polybenzimidazole-based polymers have been developed. Some thermoplastic polyimide-based films are also known (eg, US Pat. No. 406).
5345, U.S. Pat. No. 5,298,331, JP-A-2-
272077, JP-A-7-41752, JP-A-7-
118625). However, a conventionally known thermoplastic polyimide film requires heating at a low temperature during imidization / film formation, and is easily deteriorated (gelled) when heated at a high temperature during film formation. For this reason, it is difficult to obtain a polyimide film or film that is thermally stable and has a large adhesive force by heat fusion.

Further, a moisture-resistant polyimide using 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride and 1,3-bis (4-aminophenoxy) benzene as a monomer component (Japanese Patent Laid-Open No. Sho 61-61). No. 143433) and a coating agent (JP-A-2-286743) are known.
There is no example of using these as a polyimide film for heat fusion, and it is difficult to obtain a polyimide film having heat resistance and capable of heat fusion after all.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to have heat resistance such that gelation does not substantially occur during imidization / film forming at high temperature, flexibility and strength as a film, and heat resistance. An object of the present invention is to provide a polyimide film having adhesive strength by fusion bonding.

[0005]

That is, the present invention provides:
Consisting of the following imide units (A) and (B),

Embedded image

Embedded image [In the formula (B), R and R ′ are respectively tetravalent and 2
Represents a valent aromatic group or an aliphatic group. (A) is 80 to 100 mol%, and (B) is 20 to 0 mol%.
The present invention relates to a polyimide film characterized in that the polymer terminal is a tetracarboxylic acid anhydride residue, or a polyimide having an amine terminal sealed with a dicarboxylic acid anhydride as a main component.

The polyimide in this invention is 1,3-
Bis (4-aminophenoxy) benzene (hereinafter simply referred to as T
PE-R may be abbreviated), 2, 3, 3 ',
Two components of 4'-biphenyltetracarboxylic dianhydride (hereinafter sometimes simply referred to as a-BPDA);
In some cases, other tetracarboxylic dianhydride and diamine component are used in a ratio such that the above-mentioned two components are 80 mol% or more, and the tetracarboxylic dianhydride is used under an excess condition or with a dicarboxylic acid anhydride at a diamine terminal. Is reacted in an organic solvent under the condition of sealing to form a solution of polyamic acid (part of which may be imidized if a uniform solution state is maintained), and a film is formed from the solution of polyamic acid. It can be produced by imidization (dehydration ring closure) and drying.

The above-mentioned polyamic acid is 2, 3, 3 ',
4'-biphenyltetracarboxylic dianhydride and 1,3-
Bis (4-aminophenoxy) benzene and optionally other tetracarboxylic dianhydrides and other diamines in an organic solvent at about 100 ° C. or less, especially 20-60.
It is preferably synthesized by polymerizing at a temperature of ° C. The polyimide film of the present invention uses the solution composition of the polyamic acid as a dope solution, forms a thin film of the dope solution, and evaporates and removes the solvent from the thin film and imidizes the polyamic acid. Can be manufactured by.

Further, the polyamic acid produced as described above is heated to 150 to 250 ° C., or an imidizing agent is added and reacted at a temperature of 150 ° C. or lower, particularly 15 to 50 ° C. to give an imide ring. The polyimide film can be produced by any method of evaporating the solvent and then precipitating it in a poor solvent to obtain a powder, and then dissolving the powder in an organic solution to form a film and drying.

As the tetracarboxylic acid dianhydride which can be used in the present invention, 2,3,3 ', 4'-biphenyltetracarboxylic acid dianhydride is most preferable, but 20 mol% or less thereof is other than that. Aromatic tetracarboxylic dianhydride (in the above formula, tetracarboxylic dianhydride containing an R group), for example, pyromellitic dianhydride, 3,3 ′,
4,4′-benzophenonetetracarboxylic dianhydride,
3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl)
Propane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride or 2,3,6,7-naphthalenetetracarboxylic dianhydride Anhydrous or the like, preferably 3,
It may be replaced by 3 ', 4,4'-biphenyltetracarboxylic dianhydride.

As the diamine which can be used in the present invention, 1,3-bis (4-aminophenoxy) benzene is most preferable, but 20 mol% or less of the other diamine (containing R'group in the above formula). Diamines), for example 4,
4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenylmethane, 2,2
-Bis (4-aminophenyl) propane, 1,4-bis (4-aminophenoxy) benzene, 4,4'-bis (4-aminophenyl) diphenylether, 4,4 '
-Bis (4-aminophenyl) diphenyl sulfone,
4,4'-bis (4-aminophenyl) diphenyl sulfide, 4,4'-bis (4-aminophenyl) diphenylmethane, 4,4'-bis (4-aminophenoxy)
Diphenyl ether, 4,4'-bis (4-aminophenoxy) diphenyl sulfone, 4,4'-bis (4-aminophenoxy) diphenyl sulfide, 4,4'-bis (4-aminophenoxy) diphenylmethane, , 2
-Flexible aromatic diamine having a plurality of benzene rings such as bis [4- (aminophenoxy) phenyl] propane and 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 1,4- Aliphatic diamines such as diaminobutane, 1,6-diaminohexane, 1,8-diaminooctane, 1,10-diaminodecane, and 1,12-diaminododecane, diamines such as xylenediamine, and more than one benzene ring among them. It may be replaced by a flexible aromatic diamine.

In the present invention, examples of the dicarboxylic acid anhydride for blocking the amine terminal of the polymer include phthalic anhydride and its substitution product, hexahydrophthalic anhydride and its substitution product, succinic anhydride and its substitution product, and the like. Is mentioned. Particularly, phthalic anhydride is preferable.

The organic solvent used for synthesizing the polyamic acid is N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, dimethylsulfoxide. , Hexamethylphosphoramide, N-methylcaprolactam, cresols and the like.
These organic solvents may be used alone or in combination of two or more.

To obtain the polyimide of the present invention, the amount of diamine (as the number of moles of amino groups) used in the above organic solvent is the total number of moles of acid anhydride (tetraacid dianhydride and dicarboxylic acid anhydride). As total moles as acid anhydride groups), preferably 0.92-1.
0, particularly 0.98 to 1.0, of which 0.99 in particular
Is 1.0 to 1.0, and the amount of the dicarboxylic acid anhydride used is preferably 0.05 or less, particularly 0.0001 to 0. 0, as a ratio of the tetracarboxylic dianhydride to the molar amount of the acid anhydride group.
It is preferable to react each component in a ratio of 02 to obtain a polyamic acid.

When the amount of the above-mentioned diamine and dicarboxylic acid anhydride used is out of the above range, the molecular weight of the polyamic acid obtained, that is, the polyimide, is small, and the strength and adhesive strength of the film are lowered. Further, particularly under conditions where the diamine component is in excess, gelation occurs during imidization of the polyamic acid or removal of the solvent, resulting in deterioration of the physical properties of the film and deterioration of the heat fusion force. For the purpose of limiting gelation, phosphorus stabilizers such as triphenyl phosphite and triphenyl phosphate are added in a range of 0.01 to 1% with respect to the solid content (polymer) concentration during polyamic acid polymerization. It can be added.

The adhesive polyimide film of the present invention comprises
The polyamic acid solution (transparent viscous solution) obtained as described above is cast-coated on a support such as a glass plate, a stainless steel mirror surface, and a belt surface, dried at 100 to 180 ° C., and then a casting substrate. From the glass transition temperature, preferably 180 to 350 ° C., particularly preferably higher than the glass transition temperature (Tg) and 350 ° C.
Hereinafter, among them, in particular, 270 to 350 ° C. (especially 300 to
It is heated at a curing temperature of (350 ° C. is preferable) for 1 to 60 minutes to perform dehydration ring closure to imidize and remove the solvent, and the imidization rate is 99% or more, the volatile component content is 0.1% or less, and the thickness is 1 to 5
It can be made as a 0 μm transparent film.
Alternatively, the polyimide film of the present invention is solvent soluble (eg, N-methyl-2-pyrrolidone, m-crezo-
(Soluble in a solvent such as a solvent), the polyamic acid solution is heated to 150 to 250 ° C., or an imidizing agent is added and reacted at a temperature of 150 ° C. or lower, particularly 15 to 50 ° C. Then, the obtained polyimide solution is cast and applied, preferably heated to a temperature of 270 to 350 ° C. to evaporate the solvent to obtain a polyimide film. Alternatively, the polyimide solution is precipitated in a poor solvent to form a polyimide powder, which is then dissolved in an organic solvent that is easy to evaporate to form a polyimide solution, which is then cast / coated / solvent evaporated to obtain a polyimide film. You can also
Thus, the logarithmic viscosity ηinh is 0.3 to 3 dl /
It is possible to obtain a polyimide film composed of polyimide, which is preferably 0.5 to 2.0 dl / g.

Since the polyimide film obtained as described above has flexibility, strength and heat resistance,
It can be used for producing a laminate by heat fusion with various base materials (preferably metal foil).

The above-mentioned polyimide film is preferably inserted between various substrates, and the pressure is 1-1000 kg / cm ² , the temperature is not less than the glass transition temperature (Tg) of polyimide and not more than 350 ° C., and particularly 250-. 1 at a temperature of 350 ° C
By heat-sealing for 2 seconds to 30 minutes, a laminate having high peel strength can be obtained.

The polyimide film in this invention is
The film is not limited to a so-called film, but may be in the form of a film formed as a coating film on the surface of a substrate. In this case, the thickness is preferably 1 to 50 μm. In this case,
After applying the polyamic acid solution or the polyimide solution to the surface of the base material, a film can be formed under the same heating conditions as in the film formation. Through this film, a laminate can be obtained by heat fusion with the same or different base materials under the same conditions as described above.

[0019]

The present invention will be described below in more detail with reference to examples and comparative examples. In Examples and Comparative Examples,
The following measurement tests were performed on each polyimide film. The glass transition temperature (Tg) of polyimide was determined from the inflection point of the endothermic curve by DSC measurement. The logarithmic viscosity ηinh of polyimide is obtained by casting a polyamic acid solution on a glass plate, and then 20 minutes at 80 ° C, 20 minutes at 200 ° C, and 300 ° C.
Heat treatment was performed in the air for 30 minutes in air to obtain a polyimide film, which was measured in N-methyl-2-pyrrolidone at a concentration of 0.5 g / dl (30 ° C.) and calculated by the following formula. Logarithmic viscosity ηinh = ln (t / t _o ) / c (where c is the concentration of polyimide and t _o is N
The time for the methyl-2-pyrrolidone to fall through the viscous tube,
t is the time for the sample solution to drop in the viscous tube. ) The mechanical properties of the polyimide film are ASTM D-8.
82. The heat-sealing property and heat resistance of the polyimide film are IPC-TM- (2.4.9) for a metal foil laminate in which two metal foils (electrolytic copper foil having a thickness of 35 μm) are heat-sealed with a polyimide film. '90
The peel strength measured in accordance with the “Peeling method” and the peel strength after floating the metal foil laminate in a solder bath at 290 ° C. for 1 minute were measured, and the appearance was observed and evaluated.

Example 1 29.23 g (0.100 mol) of 1,3-bis (4-aminophenoxy) benzene (TPE-R) was placed in a reaction vessel equipped with a stirrer, a cooling tube, a thermometer and a nitrogen introducing tube. , 59 mg of triphenyl phosphate, and 269 g of N, N-dimethylacetamide. Next, under a nitrogen stream 2,
29.71 g (0.101 mol) of 3,3 ′, 4′-biphenyltetracarboxylic dianhydride (a-BPDA) was gradually added, and the mixture was stirred for 4 hours while maintaining a temperature of 60 ° C. or lower to give a light weight. A brown transparent viscous polyamic acid solution was obtained (sometimes abbreviated as varnish A).

This varnish A was applied on a glass plate with an applicator, heated at 140 ° C. for 20 minutes and dried, and then the film-like material was peeled off, fixed on a stainless pin tenter and fixed at 200 ° C. for 20 minutes. After heating in air at 300 ° C. for 30 minutes, a yellow transparent polyimide film having a thickness of 10 μm was obtained. Using this polyimide film, ηinh and mechanical properties were measured. The polyimide film is ηinh
Of 0.70, Tg of 250 ° C., and tensile modulus of 27
0 kgf / mm ² , tensile strength 10.5 kgf / m
The m ² and the elongation were 75%.

Two films of the above-mentioned film were used as electrolytic copper foils (thickness: 35).
μm) and preheated with a hot press kept at 300 ° C. for 5 minutes, and then pressure-bonded by heat fusion at a pressure of 30 kgf / cm ² for 20 seconds. Then, it cooled to room temperature and obtained the metal foil laminated body which is a laminated body. The peel strength of this metal foil laminate was 1.9 kgf / cm, and the 90 ° peel strength remained 1.9 kgf / cm even after soldering, and no abnormalities were observed in the appearance.

The polyimide film of Example 1 was replaced with
Highly rigid polyimide film with a thickness of 25 μm (Kapton,
It was sandwiched between a DuPont company) and an electrolytic copper foil, and the same heat fusion operation as the conditions described in Example 1 was performed. 90 ° peel strength is 1.2kgf / cm, 1.2k after soldering
The gf / cm was maintained, and no abnormalities were found in the appearance. The peeling occurred between the two types of polyimide films.

Example 2 29.52 g (0.10 g) of TPE-R in Example 1 was used.
1 mol), a-BPDA was changed to 29.42 g (0.100 mol), and the reaction time was changed from 4 hours to 1 hour. After polymerization of polyamic acid was carried out in the same manner as in Example 1, 0.296 g (0.02 mol) of phthalic anhydride was added, followed by polymerization for 3 hours to obtain a light brown transparent viscous polyamic acid solution. A yellow transparent polyimide film was obtained from this solution in the same manner as in Example 1. This polyimide film has an ηinh of 0.73 and a Tg of 250.
° C, tensile elastic modulus 270 kgf / mm ² , tensile strength 1
It was 0.5 kgf / mm ² and the elongation was 75%.

As in Example 1, the polyimide film was interposed between two electrolytic copper foils and thermocompression bonded. The 90 ° peel strength of the obtained metal foil laminate was 2.0 kgf / cm, which was 2.0 kgf / cm even after the soldering treatment and had no abnormal appearance.

Example 3 Polymerization solvent used in Example 1: 269 g of N, N-dimethylacetamide and 235 g of N-methyl-2-pyrrolidone
In the same manner as in Example 2, a polyamic acid solution in which the amine terminal was capped with a phthalic anhydride residue was obtained in the same manner as in Example 2. Then, the cooling tube was replaced with a cooling tube equipped with a water separator, 30 g of toluene was added to the reaction solution, the temperature in the reaction system was raised to 180 ° C., and the reaction was continued for 5 hours. The water produced by imidization was azeotropically distilled with toluene, and a theoretical amount of water was removed to the outside of the system to obtain a pale yellowish brown transparent viscous polyimide solution. A yellow transparent polyimide film was obtained from this solution in the same manner as in Example 1.

This adhesive polyimide film has ηin
h is 0.75, Tg is 250 ° C, and tensile modulus is 270k.
It had a gf / cm, a tensile strength of 10.5 kgf / mm ² , and an elongation of 75%. Example 1 using the above polyimide film
In the same manner as above, it was interposed between two electrolytic copper foils and heat-sealed. The 90 ° peel strength of the obtained metal foil laminate was 2.1 kgf /
The result was 2.1 cmf / cm even after soldering, and there was no abnormal appearance.

Example 4 29.71 g (0.10) of a-BPDA in Example 1
1-mol), a-BPDA 23.68g (0.0
81 mol) and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride 5.88 g (0.020 mol) were used and the same procedure as in Example 1 was carried out to obtain a yellow transparent polyimide film. Obtained.

This polyimide film has an ηinh of 0.75, a Tg of 248 ° C. and a tensile elastic modulus of 280 kgf.
/ Cm, tensile strength 11 kgf / mm ² , elongation 80%
Met. Similar to Example 1, the polyimide film was interposed between two electrolytic copper foils and heat-sealed. The 90 ° peel strength of the obtained metal foil laminate was 1.4 kgf / cm, which was 1.4 kgf / cm even after the soldering treatment and had no abnormal appearance.

Comparative Example 1 The TPE-R used in Example 1 was 29.53 g (0.10).
1 mol) and a-BPDA were changed to 29.42 g (0.100 mol), and the same procedure as in Example 1 was carried out to obtain a polyimide film.

This polyimide film was found to have a gel, and when trying to measure ηinh, N
It swelled in -methyl-2-pyrrolidone but did not dissolve and could not be measured. As in Example 1, the polyimide film was interposed between two electrolytic copper foils and thermocompression bonded. The 90 ° peel strength of the obtained metal foil laminate is 0.1 kgf / c.
It was m or less.

Example 5 TPE-R in Example 1 29.23 g (0.100)
26.32 g (0.090) of TPE-R instead of mol.
Mol) and 1,6-diaminohexane 1.16 g (0.0
A polyimide film was obtained in the same manner as in Example 1 except that 10 mol) was used. This polyimide film is ηi
The nh was 0.83 and the Tg was 232 ° C. Similar to Example 1, the polyimide film was interposed between two electrolytic copper foils and heat-sealed. The 90 ° peel strength of the obtained metal foil laminate was 1.6 kgf / cm, which was 1.
There was no change of 6 kgf / cm, and there was no abnormal appearance.

[0033]

INDUSTRIAL APPLICABILITY The polyimide film of the present invention has heat resistance such that gelation does not substantially occur by molding under high temperature, flexibility and strength as a film, and heat fusion bonding which causes no practical problems. Have sex.

The polyimide film of the present invention, which is obtained by curing polyimide at a temperature not lower than the glass transition temperature and is thermally stable, has a stable content with a small volatile content and a small thermal change. have.

Claims (3)

[Claims] 1. A compound comprising the following imide units (A) and (B): Embedded image [In the formula (B), R and R ′ are respectively tetravalent and 2
Represents a valent aromatic group or an aliphatic group. (A) is 80 to 100 mol%, and (B) is 20 to 0 mol%.
The polyimide film is characterized in that the polymer terminal is a tetracarboxylic acid anhydride residue or a polyimide having an amine terminal sealed with a dicarboxylic acid anhydride as a main component. 2. A method comprising casting a solution of polyamic acid or polyimide on the surface of a support and heating it to a curing temperature higher than the glass transition temperature of polyimide and 270 to 350 ° C. for dehydration ring closure and solvent removal. The polyimide film according to claim 1, wherein the logarithmic viscosity ηinh is 0.3 to 3 dl / g. 3. The glass transition temperature Tg of polyimide is 23.
The polyimide film according to claim 2, which has a temperature of 0 to 300 ° C.