JPH04161428A - Polyimide film - Google Patents

Abstract

PURPOSE:To provide the title high-modulus film excellent in resistance to water and moisture and dimensional stability, useful for flexible printing circuit boards, etc., made up of each specific two kinds of recurring unit. CONSTITUTION:The objective film made up of two kinds of recurring unit of formulas I and II (X is H or F), respectively, with the molar ratio I/II of (40:60)-(60:40). The present film can be obtained from a polyamic acid copolymer solution as precursor, which can be prepared by polymerization, in an organic polar solvent, between equimolar amounts of an acid anhydride and diamine component.

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.

[Prior Art] 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. There is. 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 due to tension, and has a problem with 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.

[Problems to be Solved by the Invention] An object of the present invention is to obtain a polyimide film that has 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.) In order to obtain a polyimide film with excellent water resistance, moisture resistance, and high elastic modulus, the present inventors developed various long-chain diamines, rigid diamines, and acid dianhydrides. As a result of studying the copolymerization of diamines, we found that although diamines have relatively long chains and a large number of bending groups, polyimide films obtained by copolymerizing with diamines have high elastic modulus in certain combinations. We found that this shows that

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. Also,
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 to 6
It is in the range of 0/40. 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 using substantially equimolar amounts of acid anhydride and diamine components and polymerizing them in a polar solvent.

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

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

(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 way that (b) is in excess of (a), and prepare a precipitate having amino groups at both ends. After obtaining a polymer and subsequently adding the aromatic diamine component (c) to it, the total diamine component C(b) + (c
)) A copolymerization method in which an insufficient amount of aromatic tetracarboxylic dianhydride (a) is added and reacted so as to be substantially equimolar.

A block copolymer can be obtained by this method.

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.

As the aromatic diamine component (b), an aromatic diamine represented by the general formula % is used. General formula (1)
The aromatic diamine represented by 2゜2-bisC4
-C4-aminophenoxy)phenyl]propane, 2,
Examples include 2-bisC4-(4-aminophenoxy)tuunyl]hexafluoropropane, which may be used alone or in combination of two or more.

Further, as the aromatic diamine (C), paraphenylene diamine represented by the general formula is used.

In addition, as the organic polar solvent used in the formation reaction of the polyamic acid copolymer, sulfoxide-based solvents such as dimethyl sulfoxide and diethyl sulfoxide, formamide-based solvents such as N,N-dimethylformamide, N,N-diethylformamide, etc. , N,N-dimethylacetamide, acetamide solvents such as N,N-diethylacetamide, N-methyl-2-pyrrolidone, N-vinyl-2
-Pyrrolidone solvents such as pyrrolidone, phenol, 0
-1m-1 or p-cresol, xylenol, halogenated phenol, phenolic solvents such as catechol, hexamethylphosphoramide, γ-butyrolactone, etc., which can be used alone or in combination.
It is preferable to use a mixture of more than one type of hydrocarbon, and it is also possible to use aromatic hydrocarbons such as xylene and toluene.

In addition, this polyamic acid copolymer contains 5 to 40% by weight, preferably 10 to 30% by weight of each of the above in a specific solvent.
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. . Note that 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 paraphenylenediamine, PMDA
is pyromellitic dianhydride, BAPP is 2,2-bis(
4-(4-aminophenoxy)phenyl]propane, D
MF 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, 108.38 g (0,497 mol) of PMDA 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.

After adding acetic anhydride as a dehydrating side and pyridine as a catalyst to this polyamic acid solution, 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. , the coating was fixed to a support frame.

Thereafter, it was heated at about 110°C for about 90 seconds, about 200°C for about 60 seconds, about 300°C for about 60 seconds, and then heated at about 400°C for about 60 seconds, dehydrated and ring-closed, dried, and then removed from the support frame. , a polyimide film of about 25 μm was obtained. The initial elastic modulus of this film was 630 kg/mJ, and the water absorption
The rate was 4.2%.

Comparative Example 2 20.81 g (0,294 mol) of EAPP I and 64.19 g (0,294 mol) of PMDA were mixed with DMF8
Polymerization was carried out in 15 g to obtain a 18.5% by weight polyamic acid solution. Hereinafter, approximately 25 μm was obtained by the same operation as in Comparative Example 1.
A polyimide film having a thickness of .

The initial elastic modulus of this film was 280 kg/am2, and the water absorption rate was 0.5%.

Example 1 BAPP79 was added to 815 g of DMF in the same manner as in Comparative Example 1.
．． 53g (0,194mol), PMDA84゜52g
(0,388 mol), P-PDA 20.95 g (0,1
94 mol) were added in order and polymerized to obtain a 18.5% by weight polyamide # 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 is 600 kg/atai"
The water absorption rate was 5%.

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.) 2. Ratio (A) of repeating units represented by the above general formulas (A) and (B)
The polyimide film according to claim 1, wherein /(B) is in the range of 40/60 to 60/40.