JPH10251515A - Composite film and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composite film having excellent heat-resistance, chemical resistance and mechanical properties and useful as an electronic material, etc., by including a polyethersulfone and a polyimide. SOLUTION: This composite film contains a continuous phase of a polyethersulfone of formula I ((m) is 10-500) and a polyimide phase dispersed in the polyethersulfone phase in the form of particles. The objective film is produced by mixing a polyethersulfone of the formula I with a polyisoimide of formula II ((n) is 2-150; X and Y are each methyl, trifluoromethyl, methoxy, phenoxy or H), casting the obtained solution and isomerizing the polyisoimide into a polyimide preferably by inducing the isomerization with heat, acid or base.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite film comprising a molecular composite material of polyethersulfone and polyimide, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, poly (oxy-1,4-phenylenesulfonyl-1,4-phenylene) (polyethersulfone, hereinafter referred to as PES) and poly (oxy-1,4-phenyleneisopropylidene-1,4-). Polysulfone-based resins such as phenyleneoxy-1,4-phenylenesulfonyl-1,4-phenylene (polysulfone, hereinafter referred to as PSF) are known as inexpensive high-performance engineering plastics. Inferior to polyimide in mechanical properties.

[0003] For this reason, researches on blending a polysulfone resin with another resin to modify the polysulfone resin have been widely conducted. For example, U.S. Pat.
No. 812 describes a blend composition of polyimide and PES that is soluble in an organic solvent having a specific structure,
It is described that they are compatible in a limited area. However, the polyimide described in this document has a thermoplastic flexible structure, and the mechanical properties and heat resistance of PES are insufficiently improved.

On the other hand, polypyromellitimide having a rigid rod-like skeleton has low solubility in organic solvents and it is extremely difficult to obtain a polyimide solution. Therefore, molding and processing using a polyamic acid as a precursor thereof is difficult. Is being done. However, when a solution of a polyamic acid and a solution of a polysulfone-based resin are mixed, only a heterogeneous solution having a significantly different polarity due to the influence of active hydrogen of the carboxyl group of the polyamic acid can be obtained. A film formed from such a non-uniform solution has a band-like or irregular cross-sectional form in which the polyimide and the polysulfone-based resin are completely phase-separated, and the mechanical strength is higher than that of the original polysulfone-based resin. However, only inferior brittle films could be obtained, and the composite of polyimide and polysulfone resin had not yet been realized.

Also, Wallace et al. (Polymer Magazine, Vol. 31,
p2411) uses a polyisoimide having no active hydrogen as a precursor of polypyromellitic acid to study a solution blend of a polyisoimide of a specific structure and a polyetherimide structurally similar to the polyisoimide. Have gained. However, the report reports that only a non-uniform and opaque film can be obtained from polyisoimide and polysulfone-based resins.

On the other hand, JP-A-5-230213 and JP-A-7-
No. 283544 discloses that it has excellent heat resistance and dimensional stability.
A wiring board and a circuit board using a polyimide having a 2′-disubstituted diaminobenzidine skeleton are disclosed. However, these polyimides also have poor solubility in organic solvents and cannot achieve the object.

Further, in High Perform. Polymers, Vol. 7, p. 81, 2,2 ', 6,6 to improve the solubility further than polyimide having a 2,2'-disubstituted diaminobenzidine skeleton. Polyimides using '-tetrasubstituted benzidine are disclosed. The polyimide having a flexible skeleton described therein introduced into an acid component has excellent solubility in an organic solvent, but polypyromellitimide using pyromellitic dianhydride as an acid component is insoluble. As described above, conventionally, a solution blend of a rigid rod-like polyimide and a polysulfone-based resin cannot be obtained, and a composite film of these polymers cannot be produced.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a film made of polyethersulfone and polyimide which has excellent heat resistance, chemical resistance and mechanical properties.

The present inventors have intensively studied the structure of a rigid rod-like polyimide suitable for the above purpose. As a result, they have found that a rigid film having a specific structure can be mixed with polyethersulfone as a polyisoimide as a precursor thereof to obtain a composite film having properties superior to that of a mixed solution. Was.

That is, the present invention provides the following formula (I):

Embedded image (Wherein, m represents an integer of 10 to 500) having a continuous phase of polyether sulfone and a polyimide phase dispersed in particles in the continuous phase, and a mixed region at an interface between both phases. Is provided. In the film of the present invention, the polyimide is represented by the following formula (I
I):

Embedded image (In the formula, n is an integer of 2-150, X and Y each independently represent a methyl group, a trifluoromethyl group, a methoxy group, a phenoxy group or hydrogen, and at least one of X and Y is other than hydrogen. Is a substituent.).

Further, the present invention relates to a polyether sulfone represented by the above formula (I), and the following formula (III):

Embedded image (Wherein, n, X and Y are the same as above) to prepare a solution by mixing with the polyisoimide, and after forming this solution into a film, isomerizing the polyisoimide to polyimide. The present invention provides a method for producing the composite film.

In the film of the present invention, the polyimide is substantially spherical and is dispersed in a continuous layer of polyether sulfone. Further, in the film of the present invention, it is presumed that a mixed region exists at the interface between the continuous phase of polyether sulfone and the polyimide phase dispersed therein. In the present specification, the film means a film formed of a polymer, and includes a so-called sheet.

[0013]

DETAILED DISCLOSURE OF THE INVENTION

(1) Polyether sulfone PES of the above formula (I) used for the film of the present invention
It is preferable to use one soluble in an organic solvent. Commercially available products include, for example, Victrex 4100 (Sumitomo Chemical Industries, Ltd.)
Manufactured) can be used, but is not limited thereto.

(2) Polyimide represented by the above formula (II), which forms a dispersed phase in the film of the present invention,
The polyimide having a rigid rod-like skeleton can be obtained by preparing a solution by mixing with polyethersulfone in the form of polyisoimide represented by the formula (III), and then performing isomerization.

Such a polyisoimide can be obtained by reacting pyromellitic dianhydride with a diamine in an organic solvent to prepare a polyamic acid, and then closing the ring.

(Diamine) 2,2′-Disubstituted or 2,2 ′, 6,6′-tetrasubstituted benzidine is used as the diamine which is one of the components used in the production of polyamic acid. It is considered that when the diamine has such a substituent, the two aromatic rings have a non-planar structure, the intermolecular force is reduced, and the heat resistance and the dimensional stability are improved. That is, it is preferable that at least one of X and Y has a substituent other than hydrogen since such a non-planar structure is easily obtained.

The substituents of benzidine are a methyl group, a trifluoromethyl group, a methoxy group and a phenoxy group. The substituents are particularly preferably a methyl group and a trifluoromethyl group because of the availability of monomers, and 2,2 ′
-Bis (trifluoromethyl) -4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2 ', 6,6'-tetramethylbenzidine and the like are preferable.

The copolymerization may be carried out by using another diamine together. Such diamines include, for example, p-
Phenylenediamine, m-phenylenediamine, 4,4 '
-Diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 2,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 3,3 ' -Diaminodiphenyl sulfone,
4,4′-diaminodiphenyl sulfide, 3,4′-diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfide, 3,3′-diaminobenzophenone,
4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenylpropane,
3,4′-diaminodiphenylpropane, 3,3′-diaminodiphenylpropane, 4,4′-diaminodiphenylhexafluoropropane, 3,4′-diaminodiphenylhexafluoropropane, 3,3′-diaminodiphenylhexafluoropropane , Bis [4- (3-diaminophenoxy) phenyl] methane, bis [4- (4-aminophenoxy) phenyl] methane, 2,2-bis [4- (3-
Aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane,
2,2-bis [4- (3-aminophenoxy) phenyl]
Hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane,
3-bis (3-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, bis [4- (3
-Aminophenoxy) phenyl] sulfone, bis [4-
(4-aminophenoxy) phenyl] sulfone, bis [4
-(4-Aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether and the like are used.

(Acid Anhydride) The acid anhydride, which is the other component used in the production of polyamic acid, may be a tetracarboxylic anhydride having a rigid structure. Pyromellitic dianhydride is particularly preferred. Further, another tetracarboxylic dianhydride may be copolymerized. Examples of such tetracarboxylic dianhydrides include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, oxydiphthalic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic acid Dianhydride, 2,2 ', 3,3'-
Benzophenone tetracabonic acid dianhydride, 3,3 ', 4,
4'-benzophenonetetracarboxylic dianhydride, 2,2
-Bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) sulfone dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, Bis (2,3-dicarboxyphenyl) methane dianhydride 2,3,6,7 naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,2-bis (2,3-dicarboxyphenyl) hexafluoropropane dianhydride, 2,2-bis
(3,4 dicarboxyphenyl) hexafluoropropane dianhydride, bis (3,4 dicarboxyphenyl) difluoromethane dianhydride, bis (2,3 dicarboxyphenyl) difluoromethane dianhydride, 1 , 3-bis (3,4-
(Dicarboxyphenyl) -1,1,3,3-tetramethyldisiloxane dianhydride and derivatives thereof are used.

(Production of polyisoimide) A known production method may be used to produce a polyisoimide using the diamine component and the acid dianhydride via a polyamic acid. That is, approximately equimolar amounts of the diamine component and the acid dianhydride are dissolved in an appropriate organic solvent at a temperature of -5 to 50 ° C for 1 to 24.
After reacting for a time, a polyamic acid is produced.

The acid anhydride and the diamine used are not limited to one component, respectively, and two or more kinds may be used as a mixture. Further, if necessary, the terminal may be blocked with phthalic anhydride and its derivative or aniline and its derivative.

Examples of the organic solvent used here include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, 1,3-dimethyl-2-imidazolidinone, dimethylsulfo Oxide, dimethyl sulfide, dimethyl sulfone, pyridine, tetramethyl urea, diglyme, triglyme,
Examples include tetrahydrofuran, dioxane, and cyclohexanone.

The obtained polyamic acid can be further imidized by a known method. That is, a dehydration condensing agent is added to the polyamic acid, and if necessary, the mixture is cooled and subjected to a dehydration ring-closing reaction (isoimidization) with stirring. After filtering the reaction solution, it is poured into a precipitant such as 2-propanol to precipitate a reaction product, which is separated by filtration, washed and dried to obtain the polyisoimide represented by the formula (III).

As the condensing agent used in the production of the polyisoimide, any known condensing agent for such a reaction can be used. Examples include dicyclohexylcarbodiimide (DCC), trifluoroacetic anhydride, thionyl chloride, acetyl chloride, ethyl chloroformate, phosphorus trichloride and the like. Among them, DCC and trifluoroacetic anhydride-triethylamine-based condensing agent are preferable because they produce isoimide quantitatively.

The isoimide unit does not have a carboxyl group, and the rigidity and symmetry of the skeleton are disturbed as compared with polyimide, and as a result, the solubility in an organic solvent is high. In addition, it isomerized to imide by heat, acid catalyst and base catalyst without release of volatile components such as moisture, so that polyimide is obtained without generation of voids and foaming, and it is more compatible and film-forming than the corresponding polyamic acid. It is superior in terms of sex.

(Mixed solution of polyisoimide and polyether sulfone) A mixed solution is prepared by dissolving polyisoimide and PES in a common solvent of these polymers. Such a solvent is not particularly limited as long as it can dissolve both the polyisoimide and PES. However, toluene, cyclohexanone, chloroform, methylene chloride, N-methyl-
2-Pyrrolidone and N, N-dimethylacetamide are preferred. In addition, N, N-dimethylformamide, 1,3-
Dimethyl-2-imidazolidinone, dimethyl sulfoxide, dimethyl sulfide, dimethyl sulfone, pyridine, tetramethyl urea, diglyme, triglyme,
You may use tetrahydrofuran, dioxane, etc.

The total polymer concentration in the blend solution used for film formation is 50% by weight or less, preferably 10 to 30% by weight.
It is. If the polymer concentration is higher than this, the stability of the solution will be reduced and the film-forming properties will also be poor.

The mixing ratio of PES and polyisoimide is as follows:
2 to 10 parts by weight of polyisoimide per 100 parts by weight of PES
0 parts by weight, preferably 4 to 50 parts by weight are blended to prepare a blend solution.

The thickness of the composite film is 2 to 50 μm.
m, preferably 5 to 25 μm. The thickness of the film can be appropriately adjusted depending on the concentration of the blend solution and the film forming conditions.

(Isomerization Reaction of Polyisoimide) The isomerization reaction refers to the rearrangement of isoimide to imide in the molecule, and its chemical basis and examples are described in Polymer Jour.
nal, vol. 26, p. 313 (1994). That is, it is a chemical reaction in which the molecular structure changes without changing the atomic configuration to imide which is a structural isomer of isoimide. For such isomerization, a method by heating, a method by the action of an acidic compound or a basic compound, or the like can be used. These can be used alone or in combination.

When the isomerization is performed by heating, the temperature may be a temperature at which the polyisoimide is isomerized, and is preferably equal to or higher than the glass transition temperature (Tg) of the polyisoimide. Specifically, 80 to 500 ° C, preferably 150 to
The temperature is 400 ° C, more preferably 200 to 350 ° C.

The acidic compound used for the isomerization may be any of organic and inorganic acidic compounds. Examples of the organic acidic compound include a carboxylic acid derivative and a sulfonic acid derivative. Specific examples include benzoic acid, acetic acid, p-toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid and derivatives thereof. In addition, a compound which induces an acidic compound by the action of actinic rays such as ultraviolet rays or heat can also be used. Examples of such compounds include one or two of dialis sulfonium salt, triallylsulfonium salt, dialkylphenacylsulfonium salt, allyldiazonium salt, cyanate ester, aromatic sulfonate ester, nitrobenzyl ester, aromatic sulfamide and the like. More than one species can be used in combination. Further, as the inorganic acidic compound, hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid and the like can be used. These can be used in combination.

On the other hand, as the basic compound used for the isomerization, an organic or inorganic basic compound is used. Primary, secondary and tertiary amine compounds can be used as the organic basic compound. Particularly, a tertiary amine compound is preferable in order to avoid a side reaction with the polyisoimide.
Such tertiary amine compounds are specifically exemplified by triethylamine, pyridine, 1,8-diazabicyclo [5,4,0]
-7-undecene (DBU), dimethylaminopyridine,
Picoline and the like and derivatives thereof.

A compound which induces an acidic compound by the action of actinic rays such as ultraviolet rays or heat may be used. Examples of such a compound include an o-nitrobenzylcarbamoyl compound derivative and a nifedipine derivative. As inorganic basic compounds, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate,
A known basic compound such as sodium bicarbonate can be used.

(Production of Composite Film) In the film of the present invention, the above-mentioned isomerization of polyisoimide is carried out in a film forming step. That is, a composite film of PES and polyimide is prepared by dissolving PES and polyisoimide in a common solvent thereof to prepare a blend solution, coating and casting the solution on a support, followed by drying and heat treatment.

As a support used for film formation, a substrate of copper, aluminum, nickel, glass, ceramic, glass / epoxy or the like is used. In addition, various substrates such as sheets and foils can be used. It is preferable to use a support having good heat resistance. The coating may be performed by a usual method, for example, by using a knife coater, a doctor blade, a kiss coater, an applicator, or the like, by a known method.

Drying is an important step in removing the organic solvent and forming a film, and a temperature of 20 to 200 ° C. is preferred. If the drying temperature is lower than 20 ° C., the solvent cannot be sufficiently removed, which is not preferable. 200 ° C
Exceeding the ratio is undesirable because the solvent evaporates too quickly and causes foaming. Drying may be performed at normal pressure or under reduced pressure.

The heat treatment may be performed as needed. When drying is performed in the presence of an acidic compound and a basic compound, isomerization of a polyisoimide to a polyimide may progress during the drying. Drying and heat treatment may be performed separately or may be performed without distinction. That is, drying and heat treatment can be performed simultaneously while gradually increasing the drying temperature. The operation of the heat treatment may be performed at normal pressure or at reduced pressure.

The polyisoimide has a substantially spherical, specifically spherical, deformed particle shape in the polyethersulfone matrix. The diameter of the particles is preferably from 0.1 to 5 μm. If the particle size is larger than this, it becomes difficult to form a spherical island-like dispersion state, and the particles may be separated into layers, which is not preferable in terms of the mechanical strength of the blend film.

According to the present invention, a rigid rod-shaped polyimide having a chemical structure that is hardly soluble in an organic solvent is mixed with polyethersulfone as a polyisoimide as a precursor thereof to form a uniform solution. The composite film obtained from this solution is transparent and has a structure in which polyimide domains are uniformly dispersed in a polyethersulfone matrix. Furthermore, since the interface between the two is a mixed phase, even when a stress is applied, no interfacial delamination occurs, and it has excellent characteristics as compared with the case where an inorganic filler is used.

[0041]

EXAMPLES Next, the present invention will be described more specifically based on examples.

[Synthesis Example] Synthesis of 2,2 ', 6,6'-tetramethylbenzidine (TMBZ) According to the method described in J. Am. Chem. Soc., 67, 928, (1945). Synthesized. That is, 5-nitro-1,
3-xylene (10.0 g, 41.6 mmol) and zinc dust (25.
0 g) was dispersed in 40 mL of ethanol, 50 mL of 30% by weight sodium hydroxide was added thereto, and the mixture was heated for 4 hours.
After the reflux, the mixture was poured into a 30% by weight aqueous acetic acid solution, and the precipitate was collected. The precipitate was washed with water and dried under reduced pressure to give 2,
2 ′, 6,6′-Tetramethylhydrazobenzene was synthesized. Recrystallized from petroleum ether, melting point 124-125 ° C
To obtain pale yellow needle-like crystals.

The 2,2 ′, 6,6′-tetramethylhydrazobenzene (2.46 g, 10.0 mmol) synthesized here was mixed with 3N
The mixture was heated and refluxed in 100 mL of hydrochloric acid for 4 hours, allowed to cool, and then slowly added with a 20% by weight aqueous sodium hydroxide solution until precipitation began to occur, and then saturated sodium acetate was added until the precipitate was precipitated.

Next, the precipitate was removed by filtration, and
The mixture was extracted three times with 0 mL of ether, dried over magnesium sulfate, and concentrated. After adding 20 mL of benzene and 40 mL of petroleum ether and heating to remove the insoluble portion, and left to cool, crystals precipitate. When this is recrystallized from a 50% aqueous ethanol solution, TMBZ having a melting point of 167 to 169 ° C is obtained.

(Synthesis of Polyamic Acid [PMDA / TMBX]) T
MBZ (1.20 g, 5.0 mmol) was dissolved in N-methyl-2-pyrrolidone (NMP) (19.2 mL) and cooled in an ice bath. To this solution was added pyromellitic dianhydride (1.09 g, 5.
(0 mmol) was added, followed by stirring at room temperature for 19 hours to obtain a polyamic acid.

(Synthesis of Polyisoimide [PMDA / TMBX]) Next, 90 m was added to the synthesized polyamic acid [PMDA / TMBX] solution.
L of NMP was added and stirred until uniform. Next, triethylamine (1.40 mL, 10.0 mmol) was added, followed by cooling in an ice bath. Trifluoroacetic anhydride (2.10
mL, 15.0 mmol) was added dropwise, and after completion of the addition, the mixture was stirred at room temperature for 4 hours.

After completion of the reaction, the reaction solution was poured into 1 L of 2-propanol, and the precipitate was collected by filtration and dried at 40 ° C. under reduced pressure to obtain a 96% yield of polyisoimide [PMD
A / TMBX].

(Preparation of Blend Solution) 20 parts by weight of polyether sulfone (PES) was dissolved in 80 parts by weight of DMAc to prepare a PES solution. Similarly, 20 parts by weight of the above-mentioned polyisoimide [PMDA / TMBX] was dissolved in 80 parts by weight of DMAc to prepare a PII solution. In each embodiment, PE
The S solution and the PII solution were mixed at a predetermined weight ratio, and stirred at room temperature for 4 hours to prepare a blend solution.

(Preparation Method of Blend Film) A blend solution of each composition was cast on a glass plate, and the mixture was heated at 80 ° C. for 10 minutes.
Dried on a hot plate. Next, a heat treatment was performed while reducing the pressure at 200 ° C. for 3 hours to prepare a film having a thickness of 25 μm.

(Method of Observing Morphology of Blend Film) Measurement was performed at an acceleration voltage of 100 kv using a transmission electron microscope (TEM) (Hitachi H-800). Energy dispersive X-ray analysis (EDX) was performed using Kevex Delta IV.

Example 1 4 parts by weight of PII solution and PES
A blend solution was prepared from 96 parts by weight of the solution. This solution was a homogeneous and transparent solution without phase separation. Next, a film was prepared from this solution. The resulting film was pale yellow and transparent. FIG. 1 shows the result of TEM observation of the blend film. Fine particulate spherical domains were observed. The size of this domain was about 0.2 μm. FIG. 2 shows the result of EDX analysis of both the matrix portion and the domain portion of the film. The presence of S atoms was confirmed from both the matrix part (part A in FIG. 1: FIG. 2 (a)) and the domain part (part B in FIG. 1: FIG. 2 (b)), and the polyimide and PES were uniformly compatible It is confirmed that the mixed region exists at the interface between the continuous phase of PES and the polyimide phase.

Example 2 10 parts by weight of PII solution and P
A blend solution was prepared by mixing 90 parts by weight of the ES solution. This solution was a homogeneous and transparent solution without phase separation. A film was prepared from this solution under the above conditions. The resulting film was pale yellow and transparent.

FIG. 3 shows the result of TEM observation of the blend film. Fine particulate spherical domains were observed. The size of this domain was about 0.4 μm.
FIG. 4 shows the results of EDX analysis of the matrix portion and the domain portion of the film. The presence of S atoms was confirmed from the matrix portion (A portion in FIG. 3: FIG. 4 (a)), and a small amount of S atoms was confirmed from the domain portion (B portion in FIG. 3: FIG. 4 (b)). In this film, polyimide domains are dispersed in the PES matrix, and it is presumed that a mixed region is formed at the interface between the continuous phase of PES and the polyimide phase.

Example 3 20 parts by weight of PII solution and PE
A blend solution was prepared from 80 parts by weight of the S solution. This solution was a homogeneous and transparent solution without phase separation. Then, a film was prepared from this solution under the above conditions.
The resulting film was pale yellow and opaque. When the TEM observation of the blend film was performed, fine granular spherical domains were observed as in Example 2. The size of this domain was about 1.0 μm.

Comparative Example 1 Polyisoimide [PMDA / TMBX]
We tried to make a blend film using polyimide [PMDA / TMBX] instead of. That is, polyisoimide [P
The synthesis of polyimide [PMDA / TMBX] was attempted by chemical imidation using pyridine and acetic anhydride instead of triethylamine and trifluoroacetic anhydride in the synthesis of [MDA / TMBX]. And a polyimide solution could not be obtained.

Comparative Example 2 Polyisoimide [PMDA / TMBX]
We tried to make a blend film using polyamic acid [PMDA / TMBX] instead of. Polyamic acid [PMDA / TM
BX] and 20 parts by weight of DMAc to prepare a polyamic acid solution, and 10 parts by weight of this polyamic acid solution.
90 parts by weight of the PES solution were stirred and mixed. This blend solution became cloudy and became an opaque solution. This heterogeneous solution was formed into a film in the same manner as in the example. However, the surface where the precipitate was deposited on the surface was not smooth, and a blend film could not be obtained.

[0057]

The film has excellent heat resistance, mechanical properties, and chemical resistance, which are characteristics of polyimide, and can be used for electronic materials,
It can be used as a film material, a semiconductor peripheral material, an optical material, a medical hygiene material, and the like.

[Brief description of the drawings]

FIG. 1 is a transmission electron micrograph showing the structure of a film obtained in Example 1.

FIG. 2 is an energy dispersive X-ray analysis chart of the film obtained in Example 1.

FIG. 3 is a transmission electron micrograph showing the structure of a film obtained in Example 2.

FIG. 4 is an energy dispersive X-ray analysis chart of the film obtained in Example 2.

 ────────────────────────────────────────────────── ─── Continued on front page (72) Inventor Masahiro Yoshioka 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation

Claims (5)

[Claims] 1. The following formula (I): (Wherein m represents an integer of 10 to 500). A composite film comprising a continuous phase of polyethersulfone represented by the following formula: and a polyimide phase dispersed in the continuous phase in the form of particles. 2. The polyimide is represented by the following formula (II): (In the formula, n is an integer of 2-150, X and Y each independently represent a methyl group, a trifluoromethyl group, a methoxy group, a phenoxy group or hydrogen, and at least one of X and Y is a substituent other than hydrogen. The composite film according to claim 1, which is a polyimide represented by the following formula: 3. The following formula (I): Wherein m represents an integer of 10 to 500, and a polyether sulfone represented by the following formula (III): (In the formula, n is an integer of 2-150, X and Y each independently represent a methyl group, a trifluoromethyl group, a methoxy group, a phenoxy group or hydrogen, and at least one of X and Y is other than hydrogen. 2. A composite film according to claim 1, wherein the solution is prepared by mixing the polyisoimide represented by the formula (1) with a polyisoimide represented by the formula: Law. 4. The method according to claim 3, wherein the isomerization of the polyisoimide is induced by heat, acid or base. 5. The following formula (I): Wherein m represents an integer of 10 to 500, and a polyether sulfone represented by the following formula (III): (In the formula, n is an integer of 2-150, X and Y each independently represent a methyl group, a trifluoromethyl group, a methoxy group, a phenoxy group or hydrogen, and at least one of X and Y is other than hydrogen. A mixed polymer solution obtained by dissolving a polyisoimide represented by formula (1) in a common solvent.