JPH04161437A - Polyimide film - Google Patents

Abstract

PURPOSE:To provide a polyimide film having specific repeating units and exhibiting excellent water resistance, excellent moisture resistance, good dimensional stability and high elasticmodulus CONSTITUTION:A polyimide film having repeating units of formula I and II (X is H, fluorine atom; R is OH, methyl, methoxy, chlorine and fluorine). The repeating unit I/II ratio of formula I and II is preferably 40/60 to 60/40.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a polyimide film that has excellent water resistance and moisture resistance, high elastic modulus, and therefore excellent dimensional stability.

[Conventional technology]

Polyimide generally has excellent heat resistance, electrical insulation, chemical resistance, and radiation resistance, and is widely used for applications such as insulating layers of flexible printed circuit boards. However, conventional polyimides have the disadvantage of poor water resistance and moisture resistance, that is, high water absorption and moisture absorption rates, due to their chemical structure. Therefore, for example, when this polyimide film is used as an insulating layer of a flexible printed circuit board, it absorbs moisture during the etching process and other processes where it is exposed to water, resulting in dimensional changes, making it very difficult to carry out microfabrication. I was invited.

Therefore, as an attempt to lower the water absorption rate and moisture absorption rate, it has been proposed to use a long-chain aromatic diamine to reduce the proportion of the total number of imide rings and to produce a polyimide film with a low water absorption rate. However, although this polyimide film has excellent water resistance and moisture resistance,
Many long-chain diamines have several bending groups in their structure, which has the disadvantage of low elastic modulus.

That is, this polyimide film has a large strain against tensilan, and has a problem in dimensional stability when microfabrication is performed, for example, in the production of flexible printed circuit boards.

As mentioned above, there has been a desire for a polyimide film that has both excellent water resistance, moisture resistance, and high elastic modulus.

[Invention tries to solve! i! The object of the present invention is to obtain a polyimide film having both excellent water resistance and moisture resistance and high elastic modulus.

[Means to solve the problem]

That is, the present invention includes a polyimide film having repeating units represented by the following general formulas (A) and (B).

(X represents a hydrogen atom or a fluorine atom; R represents a hydroxyl group, a methyl group, a methoxy group, a chlorine atom, or a fluorine atom) As a result of studying the copolymerization of various long-chain diamines, rigid diamines, and acid dianhydrides, we found that although the diamine has a relatively long chain and a large number of bent groups, it is possible to copolymerize it using it. It has been found that the obtained polyimide film exhibits a high elastic modulus in certain specific combinations.

That is, the polyimide film according to the present invention has a repeating unit represented by the general formula (A) containing a long-chain aromatic diamine residue having a bending group, and a repeating unit represented by the general formula (B) containing a rigid aromatic diamine residue. It consists of a copolymer composed of repeating units represented by

The polyimide copolymer of the present invention may be a random copolymer, an alternating copolymer, or a block copolymer, and
The number of repeating units represented by general formulas (A) and (B) is preferably in the range of 100 to 10,000, and the molar ratio (A)/(B) is in the range of 20/80 to 80/20. is preferable, more preferably 40/60~
The range is 60/40. If the ratio of (A) is smaller than the above range, the water absorption rate of the film will be high, and conversely, if the ratio of (A) is larger than the above range, the elastic modulus will be low.

It is also possible to compound various organic additives, inorganic fillers, or various reinforcing materials singly or in combination with this polyimide copolymer.

Next, a method for manufacturing this polyimide film will be explained. This polyimide copolymer is obtained from a polyamic acid copolymer solution which is its precursor, and this polyamic acid copolymer solution can be produced by a known method. That is, it is obtained by polymerizing in an organic polar solvent using substantially equimolar amounts of acid anhydride and diamine components.

A specific example of the method for producing this polyamic acid copolymer solution is shown below.

(1) A copolymerization method in which a mixture of aromatic tetracarboxylic dianhydride (a) and aromatic diamine compounds (b) and (c) are reacted in substantially equimolar amounts in an organic polar solvent; A random copolymer is obtained.

(2) Aromatic tetracarboxylic dianhydride (a) and one aromatic diamine compound (b) are reacted in an organic polar solvent using a molar excess of (a) over (b), and both ends are reacted. A prepolymer having an acid anhydride group is obtained, and then an aromatic diamine compound (C) is added thereto, and a wholly aromatic diamine ((b
) + (c)) is aromatic tetracarboxylic dianhydride (a
), a copolymerization method in which the copolymerization method is added in a substantially equimolar amount with
By this method, a copolymer can be obtained in which the length of the segment in which one of the repeating units is present is constant within the copolymer molecule.

(3) React the aromatic tetracarboxylic dianhydride (a) with the aromatic diamine compound (b) in such a manner that (b) is in excess of (a), and prepare a precipitate having amino groups at both ends. A polymer is obtained and then an aromatic diamine component (
After additional addition of c), total diamine component C(b) + (c)
) A copolymerization method in which the insufficient amount of aromatic tetracarboxylic dianhydride (a) is added and reacted so as to be substantially equimolar.

By this method, a Pronk copolymer can be obtained.

Methods other than those described above may be used to obtain the polyamic acid copolymer, and it is also possible to obtain the polyamic acid copolymer by mixing different types of polyamic acid solutions. It is preferable to use the method (2) because it yields products with excellent properties.

In order to obtain the above polyamic acid, pyromellitic dianhydride is used as the aromatic tetracarboxylic dianhydride.

The aromatic diamine component represented by the general formula (1) and the aromatic diamine component represented by the general formula (If) are used as the components (b) and (c).

As the aromatic diamine represented by general formula (1), 2.2
-BisC4-(4-aminophenoxy)phenyl]propane, 2,2-bisC4-C4-aminophenoxy)phenyl]hexafluoropropane, etc., which may be used alone or in combination of two or more. .

Further, as the aromatic diamine represented by the general formula (I[), 3.3'-dihydroxy-4,4'-diaminobiphenyl, 3.3'-dimethyl-4,4'-diaminobiphenyl, 3.3'-dimethoxy-4,4'-diaminobiphenyl,3.3'-dichloro-4,4'-diaminobiphenyl,3.3'-difluoro-4,4'-diaminobiphenyl, etc., and these may be used alone. or 2
Used in combination of more than one species.

In addition, as the organic polar solvent used in the production reaction of the polyamic acid copolymer, sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, N,N-dimethylformamide, N,N-diethylformamide medium, N,N- Acetamide solvents such as dimethylacetamide, N,N-diethylacetamide, N-methyl-
Pyrrolidone solvents such as 2-pyrrolidone, N-vinyl-2-pyrrolidone, phenol, 0-, m-, or p-
Examples include phenolic solvents such as cresol, xylenol, halogenated phenol, and catechol, hexamethylphosphoramide, and T-butyrolactone, and it is preferable to use these alone or as a mixture of two or more. It is also possible to use aromatic hydrocarbons such as xylene and toluene.

Further, this polyamic acid copolymer is contained in the organic polar solvent in an amount of 5 to 40% by weight, preferably 10 to 30% by weight.
From the viewpoint of handling, it is desirable that the material be dissolved.

Next, a conventionally known method can be used to produce a polyimide film from this polyamic acid solution. That is, either a thermal method of thermal dehydration or a chemical method using a dehydrating agent and a catalyst may be used, but chemical methods are preferred because the resulting polyimide polymer has excellent mechanical properties. ．． The dehydrating agent mentioned here includes, for example, aliphatic acid anhydrides such as acetic anhydride, aromatic acid anhydrides such as phthalic anhydride, and the like. Examples of catalysts include aliphatic tertiary amines such as triethylamine, aromatic tertiary amines such as N,N-dimethylaniline, and heterocyclic tertiary amines such as pyridine, picoline, isoquinoline, and quinoline. can be mentioned.

In this way, a polyimide film having both low water absorption and high elastic modulus can be obtained.

〔Example〕

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited only to these Examples.

In the examples, ODA is 4,4'-diaminodiphenyl ether, p-PDA is phenylene diamine, PMDA
is pyromellitic dianhydride, BAPP is 2,2-bisC
4-(4-aminophenoxy)phenyl]propane, D
MB represents 3,3'-dimethyl-4,4', diaminobiphenyl, and DMF represents dimethylformamide.

Comparative Example 1 Dehydrated and purified DMF815 in 21 separable flasks
g, here 0DA49.75 g (0°248
mol) and stirred until uniform.

Next, 38 g (0,497 mol) of PMDAloB was added thereto and reacted for 2 hours. During this time, the reaction system was kept at 0°C.
Cooled with ice water. Next, here is p-pDA26.8
7 g (0,248 mol) was added thereto, and the reaction was further continued for 4 hours to obtain a polyamic acid solution with a solid content of 18.5% by weight.

Anhydrous acid is added to this polyamic acid solution as a dehydrating agent.
After adding pyridine as a catalyst, it was cast onto a glass plate, dried at about 100°C for about 90 seconds, and then the polyamic acid coating was peeled off from the glass plate and fixed to a support frame. Then about 90 seconds at about 110"C, about 60 seconds at about 200C, about 60 seconds at about 300C, followed by about 400"
After heating at C for about 60 seconds, dehydrating and ring-closing, and drying, the film was removed from the support frame to obtain a polyimide film of about 25 μm. The initial elastic modulus of this film is 630 kg/s+w
”, and the water absorption rate was 4.2%.

Comparative example 2 BAPP 120.81g (0,294 mol) and PMD
A64.19g (0,294 mol) in DMF 815
The polymer was polymerized in 100 g to obtain a 18.5% by weight polyamic acid solution. Thereafter, a polyimide film having a thickness of about 25 μm was obtained by the same operation as in Comparative Example 1.

The initial elastic modulus of this film was 280 kg/ml, and the water absorption rate was 0.5%.

Implementation N1 Add BAPP71 to 815g of DMF using the same procedure as Comparative Example 1.
．． 72g (0,175 mol), PMDAT6゜21
g (0,35+-le), DMB37.08g (0
, 175 mol) were added in order and polymerized to obtain a 18.5% by weight polyamic acid solution. Thereafter, a polyimide film having a thickness of about 25 am was obtained by the same operation as in Comparative Example 1. The initial elastic modulus of this film is 660 kg/m■2
The water absorption rate was 1.3%.

The above results are summarized in Table 1.

Table 1 [Effects of the Invention] The polyimide film of the present invention has a high elastic modulus and has excellent water resistance and moisture resistance.

Claims (1)

[Claims] 1. A polyimide film having repeating units represented by the following general formulas (A) and (B). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (X represents a hydrogen atom or a fluorine atom, R represents a hydroxyl group, methyl group, methoxy group, chlorine atom or fluorine atom.) 2. General formulas (A) and (B) above The polyimide film according to claim 1, wherein the ratio (A)/(B) of repeating units represented by is in the range of 40/60 to 60/40.