JP2002138151A - Polyparaphenylenepyromellitimide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyparaphenylenepyromellitimide film having high mechanical properties such as toughness. SOLUTION: This polyparaphenylenepyromellitimide film with good balance fulfils formulae (1) and (2) below: 1.950<(nx+ny)/2 (1), 1.495<d<1.529 (2) (nx is a refraction index in the direction being maximum within the film surface, ny is a refraction index in the direction perpendicular to the direction of nx, and d is film density).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyparaphenylene pyromellitic imide film, and more particularly to a high heat resistant polyparaphenylene pyromellitic imide film having high modulus and practical toughness. is there.

[0002]

2. Description of the Related Art It is known that a wholly aromatic polyimide has excellent thermal and mechanical properties. Among them, a polyimide composed of paraphenylenediamine and pyromellitic dianhydride having a completely rigid structure is known. Due to its structure, it is expected to have high mechanical strength. However, in the molding process, in particular, polyparaphenylenepyromellitimide is infusible and insoluble, and it is difficult to mold in the state of polyimide. Therefore, a molding process in a precursor state is performed. An alignment operation in the state of polyamic acid, which has been conventionally used for the alignment operation of polyimide, has also been attempted to construct this polyparaphenylenepyromellitimide. However, polyamic acid is extremely susceptible to hydrolysis, and particularly polyamic acid comprising paraphenylenediamine and pyromellitic acid, which are precursors of highly rigid fully rigid polyimide, is particularly susceptible to hydrolysis. The resulting polyimide is extremely brittle, and almost no film is obtained which can sufficiently measure mechanical properties.

[0003] In addition, a film obtained by the imide having a very high self-cohesive force and a coarse crystal has not been obtained so far which is very brittle and exhibits sufficient mechanical properties. That is, in order to exhibit the high mechanical strength expected from this structure, it is indispensable to develop an alignment technique that suppresses self-aggregation while maintaining the orientation.

A report on polyparaphenylenepyromellitimide film, the only physical property of which has been evaluated, is a collection of polymer papers, Vol. In the case of 65, No 5, pp 282-290, an amic acid solution which is a precursor of polyparaphenylene pyromellitimide is formed and then dried, and the obtained amic acid film is stretched in a swelling solvent to increase the uniaxial orientation strength. The aims. However, a report of a biaxially stretched film, which is not a polyparaphenylenepyromellitimide film having practical strength, has not yet been obtained.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyparaphenylenepyromellitimide film having high mechanical properties such as toughness.

[0006]

Means for Solving the Problems The present invention has been studied diligently to control the self-aggregating force of polyparaphenylene pyromellitic imide and to obtain a polyparaphenylene pyromellitic imide film having a new structure having a high molecular orientation. The present invention has been reached. That is, the present invention is as follows.

[0007] 1. The main component is the following formula (1)

[0008]

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And the following formulas (2) and (3): 1.950 <(nx + ny) / 2 (2) 1.495 <d <1.529 (3) Here, nx is the refractive index in the direction that maximizes in the plane of the film, ny is the refractive index in the direction perpendicular to the plane, and d is the density.) Pyromellitimide film.

[0010] 2. Formulas (4) and (5) below: 2.05 <(nx + ny) / 2 <2.20 (4) 1.500 <d <1.525 (5) (where nx, ny, d in the above formula) Is the same as the above)), wherein the polyparaphenylenepyromellitimide-based film satisfies the above.

3. The polyparaphenylenepyromellitimide-based film described above that satisfies the following formula (6): nx-ny <0.11 (6) (where nx and ny in the above formula are the same as above).

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The polyparaphenylenepyromellitimide-based film (also simply referred to as polyimide film) of the present invention mainly uses pyromellitic dianhydride as an acid component and mainly p-phenylenediamine as a diamine component. The following formula (1) mainly derived by using

[0013]

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And a repeating unit represented by the formula:

The proportion of pyromellitic dianhydride in the acid component used is 50 mol% or more, more preferably 80 mol%.
% Or more.

The proportion of p-phenylenediamine in the amine component used is at least 50 mol%, more preferably at least 80%.

The secondary component other than pyromellitic dianhydride used as the acid component includes the following formula (II):

[0018]

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(Wherein R ₁ represents at least a tetravalent organic group).

Specific examples of such subcomponents are 1, 2,
3,4-benzenetetracarboxylic dianhydride, 2,3
5,6-pyridinetetracarboxylic dianhydride, 2,3
4,5-thiophenetetracarboxylic dianhydride, 2,
2 ′, 3,3′-benzophenonetetracarboxylic dianhydride, 2,3 ′, 3,4′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride , 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 3,3 ′
-Biphenyltetracarboxylic dianhydride, 2,3
3 ′, 4′-biphenyltetracarboxylic dianhydride,
3,3 ′, 4,4′-p-terphenyltetracarboxylic dianhydride, 2,2 ′, 3,3′-p-terphenyltetracarboxylic dianhydride, 2,3,3 ′, 4 '-P-terphenyltetracarboxylic dianhydride, 1,2,4,5
-Naphthalenetetracarboxylic dianhydride, 1,2,5
6-naphthalenetetracarboxylic dianhydride, 1,2,2
6,7-naphthalenetetracarboxylic dianhydride, 1,
4,5,8-naphthalenetetracarboxylic dianhydride,
2,3,6,7-naphthalenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,5,6-anthracenetetracarboxylic dianhydride, 1, 2,6,7-phenanthrene tetracarboxylic dianhydride, 1,2,7,8-phenanthrene tetracarboxylic dianhydride, 1,2,9,10-phenanthrene tetracarboxylic dianhydride Thing, 3,4,9,10-
Perylene tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 1,4,5,8-tetrachloronaphthalene-2,
3,6,7-tetracarboxylic dianhydride, bis (2,3
-Dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride,
Bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, bis (2,3-dicarboxyphenyl) sulfone dianhydride, bis (3,4 -Dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, 2, 2-bis (2,3-dicarboxyphenyl) propane dianhydride,
2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,6-bis (3,4-dicarboxyphenoxy) pyridine dianhydride, 1,1,1,3,3,3-
Examples include, but are not limited to, hexafluoro-2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) dimethylsilane dianhydride.

The secondary component of p-phenylenediamine used as the diamine is represented by the following formula (III):

[0022]

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(Wherein R ₂ represents at least a tetravalent organic group). As a specific example, m
-Phenylenediamine, 1,4-diaminonaphthalene,
1,5-diaminonaphthalene, 1,8-diaminonaphthalene, 2,6-diaminonaphthalene, 2,7-diaminonaphthalene, 2,6-diaminoanthracene, 2,7-
Diaminoanthracene, 1,8-diaminoanthracene, 2,4-diaminotoluene, 2,5-diamino (m
-Xylene), 2,5-diaminopyridine, 2,6-diaminopyridine, 3,5-diaminopyridine, 2,4-
Diaminotoluenebenzidine, 3,3′-diaminobiphenyl, 3,3′-dichlorobenzidine, 3,3′-dimethylbenzidine, 3,3′-dimethoxybenzidine,
2,2′-diaminobenzophenone, 4,4′-diaminobenzophenone, 3,3′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 3,
3′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylsulfone, 4,4′-diaminodiphenylsulfone, 3,
3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenylthioether, 4,4'-diamino-3,3 ',
5,5'-tetramethyldiphenyl ether, 4,4 '
-Diamino-3,3 ', 5,5'-tetraethyldiphenyl ether, 4,4'-diamino-3,3', 5
5'-tetramethyldiphenylmethane, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4
-Aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 2,6-bis (3-aminophenoxy) pyridine, 1,4-bis (3-aminophenylsulfonyl) benzene, 1,4-bis (4-aminophenylsulfonyl) benzene, 1,4-bis (3-aminophenylthioether) benzene, 1,4-bis (4-
Aminophenylthioether) benzene, 4,4′-bis (3-aminophenoxy) diphenylsulfone,
4'-bis (4-aminophenoxy) diphenylsulfone, bis (4-aminophenyl) aminebis (4-aminophenyl) -N-methylaminebis (4-aminophenyl) -N-phenylaminebis (4-aminophenyl ) Phosphine oxide, 1,1-bis (3-aminophenyl) ethane, 1,1-bis (4-aminophenyl)
Ethane, 2,2-bis (3-aminophenyl) propane, 2,2-bis (4-aminophenyl) propane,
2,2-bis (4-amino-3,5-dimethylphenyl) propane, 4,4′-bis (4-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy)
Phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] methane, bis [3- Methyl-4
-(4-aminophenoxy) phenyl] methane, bis [3-chloro-4- (4-aminophenoxy) phenyl] methane, bis [3,5-dimethyl-4- (4-aminophenoxy) phenyl] methane, 1 , 1-bis [4-
(4-aminophenoxy) phenyl] ethane, 1,1-
Bis [3-methyl-4- (4-aminophenoxy) phenyl] ethane, 1,1-bis [3-chloro-4- (4-
Aminophenoxy) phenyl] ethane, 1,1-bis [3,5-dimethyl-4- (4-aminophenoxy) phenyl] ethane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, , 2-Bis [3-methyl-4- (4-aminophenoxy) phenyl] propane, 2,2-bis [3-chloro-4- (4-aminophenoxy) phenyl] propane, 2,2-bis [3 , 5-
Dimethyl-4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy)
Phenyl] butane, 2,2-bis [3-methyl-4-
(4-aminophenoxy) phenyl] butane, 2,2-
Bis [3,5-dimethyl-4- (4-aminophenoxy) phenyl] butane, 2,2-bis [3,5-dibromo-4- (4-aminophenoxy) phenyl] butane,
1,1,1,3,3,3-hexafluoro-2,2-bis (4-aminophenyl) propane, 1,1,1,3,
3,3-hexafluoro-2,2-bis [3-methyl-
4- (4-aminophenoxy) phenyl] propane and the like, but is not limited thereto.

The polyimide film of the present invention is characterized by satisfying the following formulas (2) and (3). 1.950 <(nx + ny) / 2 (2) 1.495 <d <1.529 (3)

Here, nx is the refractive index in the direction maximizing in the plane of the film, ny is the refractive index in the direction perpendicular to the plane, and d is the density of the film. (Nx + ny) / 2 in the above formula (2) is a measure of the plane orientation of the molecular chain,
The larger the value, the more the molecular chain is oriented in the plane of the film. If this value is less than 1.95, the film is insufficiently oriented and it is difficult to exhibit high Young's modulus and strength. Also, d in the above formula (3) indicates the degree of crystallinity and the completeness of the imide. If d is less than 1.495, the film is insufficiently imidized or insufficiently crystallized, and is inferior in heat resistance and mechanical properties. It will be. If it exceeds 1.529, crystallization will be excessive and the toughness of the film will decrease.

The polyimide film of the present invention comprises (nx +
ny) / 2 preferably satisfies the following expression (4). 2.05 <(nx + ny) / 2 <2.20 (4)

With respect to the above formula (4), it is difficult to produce a film having an average in-plane refractive index of more than 2.20, and it is not practical. (It is a good word that it is difficult to realize a film that exceeds it, not a word that it is not possible to realize a film if it exceeds it.) Also, in the polyimide film of the present invention, d satisfies the following formula (5). preferable. 1.500 <d <1.525 (5)

In general, it is preferable that the characteristics of the film are excellent in any direction in the plane. However, the polyimide film of the present invention has the following formula (6): nx-ny <0.11 (6) Satisfaction is particularly preferable because there is little difference in physical properties in the film plane and the film is well balanced.

The thickness of the polyimide film of the present invention is usually 0.1 to 50 μm.

Such a balanced polyimide film of the present invention can be realized by imidizing the polyimide precursor film after highly orienting the polymer chains by biaxial stretching. Hereinafter, this method will be described.

That is, a polyimide precursor film is obtained by directly introducing the polyamic acid solution into a solvent containing dicyclohexylcarbodiimide (DCC) as a dehydrating condensing agent, and then the polyimide precursor film swells in the solvent. After stretching this in the biaxial direction orthogonal to the state, it is heated at 50 to 500 ° C. to imidize it, thereby suppressing the self-aggregation force of the molecular chains and maintaining a high degree of plane orientation. A polyparaphenylene pyromellitic imide film can be obtained.

The preparation of a polyamic acid solution, solidification by DCC, production of a polyimide precursor, stretching, and imidization by heating will be described in order.

(A) Preparation of Polyamic Acid Solution Polyamic acid, which is a precursor of polyisoimide, can be obtained by polymerizing p-phenylenediamine and pyromellitic anhydride in a solvent.

The solvent for the polymerization of the polyamic acid may be any solvent that dissolves the polyamic acid and does not react with the condensing agent. Specific examples include N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, hexamethylphosphoramide, 1,3-dimethylimidazolidinone, tetramethylurea, 1,3-dipyrrolimidazo Aprotic polar solvents such as lydinone, N-methylcaprolactam, dimethylsulfoxide, dimethylsulfone, tetramethylsulfone, ethylene glycol, pyridine, 2-picoline, 3-picoline, 4-picoline, 2,3-lutidine, Heteroaromatic compounds such as 2,4-lutidine, 2,5-lutidine, 2,6-lutidine, 3,4-lutidine, 3,5-lutidine, 2,6-lutidine; Cresols and the like.

These solvents include carbon tetrachloride, chloroform, dichloromethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane, 1,1,1,2-
Mixture with organic halides such as tetrachloroethane, 1,1,2,2-tetrachloroethane, trichloroethylene, tetrachloroethylene, and other solvents such as benzene, toluene, benzonitrile, xylene, solvent naphtha, and dioxane It is possible, but not limited to this.

Specific examples include N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone hexamethylphosphoramide, 1,3-dimethylimidazolidinone, tetramethylurea, 1,3-dipyrro Pyrimidazolidinone, N-methylcaprolactam,
Aprotic polar solvents such as dimethyl sulfoxide, dimethyl sulfone, tetramethyl sulfone, ethylene glycol, etc., pyridine, 2-picoline, 3-picoline, 4
-Picoline, 2,3-lutidine, 2,4-lutidine,
Heteroaromatic compounds such as 2,5-lutidine, 2,6-lutidine, 3,4-lutidine, 3,5-lutidine, 2,6-lutidine and the like, cresols and the like can be mentioned.

These solvents include carbon tetrachloride, chloroform, dichloromethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane, 1,1,1,2-
Mixture with organic halides such as tetrachloroethane, 1,1,2,2-tetrachloroethane, trichloroethylene, tetrachloroethylene, and other solvents such as benzene, toluene, benzonitrile, xylene, solvent naphtha, and dioxane It is possible, but not limited to this.

In order to obtain the polyamic acid in the present invention, the amount of the diamine used in the above organic solvent is preferably 0.90 to 1.10, more preferably 0.95 to 1 as a ratio to the number of moles of the acid anhydride. It is preferable to make the polyamic acid by the reaction at 0.05.

In this polymer, the terminal of the polymer may be sealed. As an end capping agent, phthalic anhydride and a substituted product thereof, hexahydrophthalic anhydride and a substituted product thereof,
Examples of the succinic anhydride and its substituted product and the amine component include aniline and its substituted product, but are not limited thereto.

The reaction temperature is from -10 ° C to 100 ° C.
And more preferably -10 to 80 ° C.
The resulting polyamic acid solution was filtered under a nitrogen atmosphere,
It is more preferable to remove a solid substance for forming a film later.

Since the polyimide in the present invention is insoluble in a solvent, the solution viscosity cannot be measured. Therefore, the solution viscosity in the state of this amic acid was measured and used as an index of the degree of polymerization. The logarithmic viscosity of the polyamic acid is not particularly limited, but is preferably 1 or more, more preferably 3 or more. As long as the viscosity is within the range of a film castable, the higher the viscosity, the more preferable the mechanical properties of the obtained imide film are.

(A) Solidification by DCC and Production of Polyisoimide The polyamic acid solution prepared by the above-described method is cast as a film, and is directly introduced into the DCC solution to be isoimidated in a swollen state to obtain a polyimide precursor polyisoimide. And the N, N generated
'-Dicyclohexylcarbodiurea (DCU) is rapidly eluted in the solvent. Next, details of the method for producing the polyimide precursor will be described in detail.

The solvent of the DCC solution may be any general organic solvent that does not dissolve DCC and does not react with the amic acid solution. Examples of such a solvent include amide solvents such as N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N′-diethylacetamide and general solvents such as aromatics, hydrocarbons, alcohols, ketones, esters, and ethers. An organic solvent is exemplified, but not limited thereto. Also more preferably N-methyl-2-pyrrolidone,
Highly polar solvents such as N, N-dimethylacetamide are preferred. When these solvents are used, urea generated simultaneously with the reaction can be quickly eluted from the polyimide precursor. These organic solvents may be used alone or in combination of two or more. The solution is preferably dehydrated because the resulting polyisoimide component reacts with moisture and returns to amic acid.

Although the DCC concentration in the DCC solution is not specified, it is preferably 1% by weight or more in order to allow the reaction to proceed sufficiently.

When the polyamic acid solution is introduced into the DCC solution, the temperature is preferably from 10 to 120 ° C., more preferably from 20 to 80 ° C., in order to enhance the reactivity and increase the solubility of the generated DCU. Further, it is preferable that the obtained polyimide precursor is further washed with a solvent in which DCU and DCC are soluble.

In the present invention, the DCC of the polyamic acid solution
As a method for introducing the compound into a solution, any of generally known wet and dry-wet molding methods may be used. Examples of the film forming method include a die extrusion method, a casting method using an applicator, a method using a coater, and the like, but are not limited thereto. These steps are preferably performed in a low-humidity atmosphere to prevent inactivation of DCC. In particular,
For example, a polyamic acid solution is cast as a film on a glass substrate using a doctor blade, and then dipped in an NMP solution containing a DCC solution. The film swells and isoimidization proceeds in this state.

(C) Stretching The polyimide precursor obtained by the above-described method is swollen and stretched to obtain a stretched polyimide precursor.
The details will be described below.

The swelling solution of the polyimide precursor may be any solvent that swells the polyisoimide without dissolving it. Examples of such a solvent include N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N'-
Amide solvents and aromatics such as diethylacetamide,
Examples include general organic solvents such as hydrocarbons, alcohols, ketones, esters, and ethers, but are not limited thereto. In order to elute DCU from the imide precursor, N-methyl-2-pyrrolidone, N, N,-
Highly polar solvents such as dimethylacetamide are preferred. These organic solvents may be used alone or in combination of two or more. Further, it is more preferable to use the solvent used for polyisoimidization as it is. The solution is preferably dehydrated because the resulting polyisoimide component reacts with moisture and returns to amic acid. The immersion time in the swelling solution may be a time sufficient for swelling.

For this stretching operation, any generally known method may be used. For example, in a swelling solvent, in air,
Further, the film may be stretched in a heated state. The temperature at the time of stretching may be such that the swelling solvent does not evaporate.

The stretching is performed in two orthogonal directions. At this time, the stretching ratio is preferably 1.2 times or more in one direction,
The product of the stretching ratio (area stretching ratio) in two orthogonal directions is more preferably 1.4 or more.

(D) Imidation by heating The stretched polyimide precursor containing a solvent produced by the method described above is imidized by heating. This method may use any method. This imidization method includes hot air heating, vacuum heating, infrared heating, microwave heating,
Heating by contact using a hot plate or a hot roll can be exemplified, but is not limited thereto. A polyimide film is obtained by performing a heat treatment at 50 to 500 ° C. using these methods. At this time, it is preferable that the imidization be completely advanced by increasing the temperature stepwise.

[0052]

The present invention will be described below in more detail with reference to examples. However, these examples do not limit the scope of the present invention.

The logarithmic viscosity of the polyamic acid was dissolved in NMP and measured at 35 ° C. at a polymer concentration of 0.5 G / 100 ml. The elongation was measured using a sample of 25 mm × 5 mm at a tensile speed of 2 mm / min, and measured according to Orientec UCT-1T.

Measurement of refractive index by microwave is 100 mm
Using a sample having a size of 100 mm and a MOA-2001A microwave molecular orientation meter manufactured by Shin-Oji Paper Co., Ltd.
The measurement was performed under a measurement frequency of GHz. Density was measured using the flotation method.

Example 1 N-methyl-2-pyrrolidone 910 m dehydrated with molecular sieves under a nitrogen atmosphere was placed in a reaction vessel equipped with a thermometer / stirrer and a raw material inlet.
After adding 19.9 g of paraphenyldiamine and completely dissolving, the mixture was cooled to 0 ° C. in an ice bath.
After adding 40.1 g of pyromellitic dianhydride to the cooled diamine solution and reacting for 1 hour, after further reacting at room temperature for 2 hours, 0.011 g of aniline was added and reacted for 30 minutes. The logarithmic viscosity of the obtained polyamic acid solution was 4.12.

This amic acid solution was applied on a glass plate to a thickness of 1.
Cast using a 5 mm doctor blade, DCC
It was introduced into a DCC bath composed of an N-methyl-2-pyrrolidone solution having a concentration of 15 wt%, solidified by reaction for 8 minutes, peeled off from the glass substrate, and further reacted for 12 minutes to obtain a planar polyimide precursor film. .

The polyimide precursor was mixed with NMP as a swelling solvent.
After the film was immersed at room temperature for 15 minutes, the film was fixed with a chuck and simultaneously biaxially stretched at a magnification of 2.3 times in two orthogonal directions. After stretching, the film was immersed in isopropanol to extract a swelling solvent and the like from the imide precursor.

After the stretched film is fixed on the frame, the temperature is increased stepwise at 80 ° C. for 5 minutes, at 200 ° C. for 10 minutes, at 250 ° C. for 8 minutes, at 350 ° C. for 5 minutes, and at 380 ° C. for 5 minutes. Thus, a polyparaphenylene pyromellitimide film was obtained. The thickness of the obtained polyparaphenylenepyromellitimide film is 8.5 μm, and the tensile elastic modulus is 13.0 GPa and 14.5 GP in the orthogonal stretching direction.
a, tensile strength is 0.36 GPa and 0.3 respectively
7 Gpa and elongation were 9.2% and 5.8%, respectively. The average refractive index in the biaxial direction (nx
+ Ny) /2=2.16, biaxial refractive index difference nx-ny
= 0.001. The density is 1.503 g / cm
^{Was 3} .

[Comparative Example 1] The same procedure as in Example 1 was performed except that the stretching operation was not performed. Atsumi of the obtained polyparaphenylene pyromellitimide film is 3
The resulting film was 5.5 μm and the mechanical properties were very fragile and could not be measured. According to the microwave, the average refractive index in the biaxial direction (nx + ny) /2=2.09, and the difference between the biaxial refractive indices nx−ny = 0.01. The density is 1.
It was 534 g / cm ³ .

[0060]

According to the present invention, a highly heat-resistant polyparaphenylenepyromellitimide film having a high Young's modulus and strength can be obtained. The polyparaphenylenepyromellitimide film of the present invention has a high elastic modulus and strength,
For example, it is useful as an electronic substrate material.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Jiro Jonobu 2-1 Hinode-cho, Iwakuni-shi, Yamaguchi F-term in the Iwakuni Research Center, Teijin Limited 4F071 AA60 AF14 AF20 AF31Y AG05 AH13 BA02 BB02 BB08 BC01 BC11

Claims (3)

[Claims] The main component is represented by the following formula (1): Paraphenylene pyromellitic imide represented by
And the following formulas (2) and (3): 1.950 <(nx + ny) / 2 (2) 1.495 <d <1.529 (3) (where nx is the refraction in the direction that maximizes in the film plane) Ny is a refractive index in a direction orthogonal to the in-plane direction, and d is a density.). 2. The following formulas (4) and (5): 2.05 <(nx + ny) / 2 <2.20 (4) 1.500 <d <1.525 (5) (wherein the above formulas 2. The polyparaphenylenepyromellitimide film according to claim 1, wherein the definitions of nx, ny, and d are the same as described above. 3. The following formula (6): nx−ny <0.11 (6) (where the definitions of nx and ny in the above formula are the same as above). Or the polyparaphenylenepyromellitimide film as described in 2 above.