JPH0464428A - Manufacture of uniaxially stretched film containing aromatic heterocyclic polyimide - Google Patents

Abstract

PURPOSE:To obtain a uniaxially stretched film having a high modulus of elasticity, by a method wherein after a filmlike polyimide precursor is stretched in a uniaxially direction, stretching is performed in the same direction while performing chemical imide ring closure and strained heat treatment is performed further under tension of 1-100MPa at a heat treatment temperature of 420-550 deg.C. CONSTITUTION:At the time of manufacturing of a uniaxially stretched film comprised of aromatic heterocyclic polyimide containing benzobisazole skeleton in a main chain having structure of a formula I(X shows S, O, NH, Ar shows a formula II or III, Y, Y' show a hydrogen atom or an alkyl group or a alkoxy group or a halogen group and Z shows a single bond or -O- or -CH2- a formula IV or V), after a filmlike polyimide precursor is stretched in a uniaxial direction, stretching is performed in the same direction while performing chemical imide ring closure. Strained heat treatment is performed under tension of 1-100MPa at a heat treatment temperature of 420-550 deg.C. With this construction, uniaxially stretched film having the high modulus of elasticity can be obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for producing a uniaxially stretched film made of an aromatic heterocyclic polyimide having a high modulus of elasticity and excellent heat resistance.
In particular, the present invention relates to a method for producing a uniaxially stretched film made of an aromatic heterocyclic polyimide containing a penzobisazur skeleton in its main chain.

[Conventional technology and issues]

Aromatic heterocyclic polymers are expected to be materials with high strength, high elastic modulus, and high heat resistance. Among them, PPBT (poly p
-phenylene-henzobisthiadur) is a rigid and rigid compound obtained by reacting 2,5-diaminobenzene-14-dithiol dihydrochloride and terephthalic acid in polyphosphoric acid at a high temperature of 160 to 200°C for a long time. molecule, 110
Gives the tensile modulus in GPa.

However, PPBT is insoluble in solvents other than strong acids such as methanesulfonic acid and chlorosulfonic acid, and furthermore, such solvents are highly corrosive to equipment, and therefore are not preferred from an industrial perspective.

[Means for Solving the Problems] As a result of intensive studies by the present inventors to produce a film with a high elastic modulus and excellent heat resistance without using such highly corrosive solvents, the inventors found that The present invention was achieved by discovering that this can be achieved by forming an aromatic heterocyclic polyimide containing a benzobisazole skeleton into a film under specific conditions.

That is, the gist of the present invention is that when producing a uniaxially stretched film made of an aromatic heterocyclic polyimide containing a benzobisazole skeleton in the main chain having the following structure (1), the polyimide precursor in the form of a film is uniaxially stretched. After stretching in the same direction while performing chemical imide ring opening, the heat treatment temperature was 420 to 550°C and 1 to 100 MPa.
The present invention relates to a method for producing a uniaxially stretched aromatic heterocyclic polyimide film, which comprises subjecting the film to tension heat treatment under a tension of .

... (1) (In the formula, X represents S, O, NH, Ar represents a hydrogen atom, an alkyl group, an alkoxy group, or a halogen group, Z represents a single bond, -o--GHzCH.

s---c---so□---C- or o CL F3 Indicates C-. ) C.F.

The present invention will be explained in more detail below.

Specific examples of monomers for obtaining the aromatic heterocyclic polyimide having the above structure of the present invention include the following compounds. As the aromatic diamine, those giving the following structural formula (II), namely, 2.6-(4,4'-diamino-diphenyl)benzo(1,2-d: 4.5
-d') bisthiazole, 2.6-(4,4'-
Diamino-diphenyl)benzo(1,ld: 4.
5-d') bisoxazole, 2.6-(4,4'
-diamino-diphenyl)benzo[1,2-d: 4
．． 5-d'']bisimidazole.

(In the formula, X represents S, O, NH) Further, examples of the aromatic tetracarboxylic dianhydride include those having the following structural formula (III), ie, bilomeli nodoic dianhydride, 3, 4. 3', 4'-hensiphenotetracarboxylic dianhydride, 3.3', 4゜4'-diphenyltetracarboxylic dianhydride, 22'3.3' -
Diphenyltetracarboxylic dianhydride, 2,2-bis(
3,4-dicarboxyphenyl)propanihydride, bis(3,4-dicarboxyphenyl)bis(trifluoromethyl)methane dianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, bis(3, Examples thereof include 4-dicarboxyphenyl)ether dianhydride, bis(3°4-dicarboxyphenyl)methane dianhydride, and the like.

, y, y' are hydrogen atoms, alkyl groups, alkoxy groups, or halogen groups, Z is a single bond, 0--C
H2--3--C- CH:l CF.

Indicates SO, -C- or -C-. ) CH, CF3 As the amide solvent used for polymerization in the present invention,
N-methyl-2-pyrrolidone (NMP), 1.3
-dimethyl-2-imidacylindinone (DMl), N,
N'-dimethylformamide (DMF), N, N'-
Examples include dimethylacetamide (DMAc), hexamethylphosphortriamide (HMPA), and mixed solvents thereof. By reacting the aromatic diamine with the aromatic carboxylic acid derivative in the amide solvent described above, a polyamic acid solution, which is a precursor of the polyimide in the present invention, can be obtained.

The present invention focuses on the fact that polyimide is produced using polyamic acid as its precursor. The polyamic acid used in the present invention can be produced by reacting aromatic diamines and aromatic tetracarboxylic acid anhydrides having the structures shown in H and m above in an amide solvent; Also, since the final polyimide structure has higher flexibility, it has excellent solubility in polar solvents such as amide solvents. A film-like product can be obtained very easily from a liquid by casting or extrusion.

In addition, when obtaining a film-like product, an imide ring-opening reagent is allowed to coexist in the polyamic acid solution within a range that does not impair the solution properties.
The imide ring may be partially opened.

The feature of the present invention is that a polyamic acid film having such a specific structure is subjected to a specific treatment, and further, the film is imidized (chemical imide ring opening) and a specific treatment is applied to the polyamic acid film. The purpose is to create a polyimide film that has a high elastic modulus and excellent heat resistance.

That is, after stretching a polyamic acid film, which is a film-like polyimide precursor, in a uniaxial direction, it is stretched in the same direction while chemical imide ring-opening is performed, and then the heat treatment temperature is 420 to 550'C and 1 to 100 MPa. under the tension of
It is characterized by applying tension heat treatment.

The present invention is characterized by such two-layer stretching treatment,
Each tension heat treatment is indispensable to the other, and if even one of these three is lacking, the object of the present invention cannot be achieved.

It is desirable that the stretching ratio applied during stretching of the polyamic acid film and during chemical imide ring opening of the polyamic acid film obtained as a result is set to 1.1 times or more, and the upper limit is set as high as possible. Because it is limited by the mechanical strength of

In addition, the polymer concentration during stretching of the polyamic acid film was 6
Setting it to 0 to 100%, preferably 70 to 90%, increases the strength of the film and allows a higher stretching ratio to be obtained.

Further, during tension heat treatment, it is essential that the tension exceeds 1 MPa or more and that the heat treatment temperature exceeds 420° C. in order to obtain a high modulus uniaxially stretched film. However, on the other hand, applying a tension exceeding 1°OM Pa to the film may cause the film to break during heat treatment, and if the temperature exceeds 550°C, heat treatment may cause significant thermal deterioration of the film. The present invention is limited by the above factors.

The heat treatment time is usually 10 seconds to 30 minutes, preferably 1 to 30 minutes.
It is 5 minutes.

[Examples] The present invention will be further explained in detail with reference to Examples below, but the present invention is not limited by these Examples unless it departs from the gist thereof.

Note that the polymerization of polyamic acid was performed in a nitrogen stream. or,
The logarithmic viscosity ηing of polyamic acid is polymer concentration 0.2
Dilute with N-methyl-2pyrrolidone to give 3 g/di.
Measured at 0°C.

In the following, 2,6(4,4'-diamino-diphenyl)benzo[1,2-d:45d')bisthiazole is referred to as DAPBT, 2,6(44'-diamino-diphenyl)benzo[1,2-d:45d')
diphenyl)henzo[1°2-d: 4,5-d'
) Bisthiazole is DBO, pyromellitic dianhydride is PMDA, N-methyl-2-pyrrolidone is NMP, 1.
3-dimethyl-2-imidazolidinone is abbreviated as DMI.

Reference example-1 4.494g (12 mmol) of DAPBT was added to NMP45
slurry in rne. Add PMDA powder to this slurry in a predetermined molar ratio to DAPBT using NMP.
20 mffi was added to initiate polymerization at room temperature.

The solution gradually became viscous and homogeneous. Table 1 shows the ηinh of the polyamic acid solution obtained after 8 hours of polymerization.

Reference Example 2 The same procedure as Reference Example 1 was carried out except that the charging ratio of DAPBT and PMDA and the polymerization conditions were changed as shown in Table 1. Table 1 shows the ηinh of the obtained polyamic acid solution.

Examples 1 and 2 The polyamic acid solutions obtained in Reference Examples 1 and 2 were cast onto a glass plate to obtain a film. Next, NMP/water-
It was immersed in a coagulation bath consisting of 75/25 (volume ratio).

After several minutes, the film was peeled off from the glass plate and stretched to 2.6 times. This film was then treated with acetic anhydride/pyridine-7.
Immersed in a chemical ring-closing bath consisting of 0/30 (volume ratio) 1
．． The film was stretched to 1x and immersed in a solvent of the same composition overnight. Further, this film was transferred to toluene and immersed for 5 hours, and then dried at room temperature while being stretched to 1.1 times. The film thickness at this point was 25μ.

Then, the film was subjected to the heat treatment shown below while applying a constant load.

100℃~400'C: Constant rate of temperature increase 45 at 10'C/min
0"C: held for 5 minutes 500"C: held for 1 minute The dynamic elastic modulus (measured with Hybron DOVII model manufactured by Toyo Baldwin Co., Ltd.) of the heat-treated polyimide uniaxially stretched film thus obtained was measured. The results obtained are shown in Table-2. In addition, the tension in Tables 2 to 2 was calculated from the load and the final film thickness.

Comparative Examples 1 and 2 Uniaxially stretched films were obtained in the same manner as in Examples except that the stretching of the polyamic acid cast film was omitted.

In addition, the dynamic elastic modulus was measured in the same manner as in the examples. The results obtained are shown in Table-2.

Table 2 As is clear from Examples 1 and 2 and Comparative Examples 1 and 2, when comparing polyimides with the same preparation composition and ηinh,
When a polyamic acid cast film is stretched, it is possible to obtain a uniaxially stretched film with an extremely high modulus of elasticity.

(Effects of the Invention) By treating the uniaxially stretched film obtained from the aromatic heterocyclic polyimide of the present invention under specific conditions, a uniaxially stretched film having a high elastic modulus can be obtained.

The uniaxially stretched film that exhibits high elastic modulus and high heat resistance obtained from the aromatic heterocyclic polyimide of the present invention can be applied to electronic materials such as video tapes for extremely long periods of use.

Claims (1)

[Claims] (1) When producing a uniaxially stretched film consisting of an aromatic heterocyclic polyimide containing a benzobisazole skeleton in the main chain having the following structure (I), the polyimide precursor in the form of a film was stretched in the uniaxial direction. After that, the film is stretched in the same direction while chemically ring-opening the imide, and further subjected to tension heat treatment at a heat treatment temperature of 420 to 550°C under a tension of 1 to 100 MPa. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) (In the formula, X represents S, O, NH, and Ar is ▼, Y, Y' are hydrogen atoms, alkyl groups, alkoxy groups, or halogen groups, Z is a single bond, -O-, -CH_2-, -S-, ▲
There are mathematical formulas, chemical formulas, tables, etc. ▼, -SO_2-, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼. )