JPS614730A - Production of organic solvent-soluble polyimide compound - Google Patents

Abstract

PURPOSE:To obtain an organic solvent-soluble polyimide compound excellent in heat resistance, water absorption resistance and light transmission, by imidating a specified polyamic acid derived from 2,3,5-tricarboxycyclopentylacetic anhydride, etc. CONSTITUTION:A mixture of at least 25mol% 2,3,5-tricarboxycyclopentylacetic anhydride and at least 3mol% aromatic tetracarboxylic acid anhydride (e.g., pyromellitic dianhydride) is reacted with an organic diamine (e.g., 4,4'-diaminodiphenyl ether or 4,4'-diaminodiphenylmethane) to prepare a polyamic acid. The obtained polyamic acid is dissolved in an organic solvent (e.g., N-methyl-2-pyrrolidone) and imidated by, for example, heating to about 120-250 deg.C to obtain the purpose organic solvent-soluble polyimide compound.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for producing a polyimide compound, and particularly to a method for producing an organic solvent-soluble polyimide compound with improved heat resistance, anti-cough properties, and light transmittance.

[Prior art] Polyimide compounds generally have excellent heat resistance, so they can be used in films, wire coatings, adhesives, etc. used at high temperatures.
It is very useful as a raw material for paints, etc.

Conventional polyimide compounds are produced by polymerizing an aromatic tetracarboxylic dianhydride such as pyromellitic anhydride and an aromatic amine in a polar solvent to obtain an aromatic polyamic acid, and then using this solution as a base material. A film-like aromatic polyimide compound is known, which is obtained by applying the compound to a film, forming it into a film, and then dehydrating and ring-closing it by a method such as heating. However, in conventional aromatic polyimide compounds, their precursor, aromatic polyamine chloride, has poor stability, and if left at room temperature,
The viscosity of the polyamic acid solution decreases, and if left for a long time, part of the solution undergoes dehydration and ring closure to form polyimide, which becomes insolubilized and becomes cloudy. Therefore, conventional solutions of aromatic polyamic acids have to be stored at low temperatures and must be handled with care.

In addition, in the above method for producing polyimide compounds, when imidizing the polyamic acid applied to the base material, it is necessary to heat it for a long time at a high temperature of usually 400°C or higher, which is disadvantageous from the viewpoint of energy saving. Due to the accompanying dehydration reaction, defects such as voids and pinholes occur in the resulting film, making it difficult to obtain a smooth and homogeneous polyimide compound film. Furthermore, the aromatic polyimide compounds produced in this manner generally have the drawbacks of being significantly colored and having low light transmittance, as well as having low anti-cough properties and high water absorption.

The present inventors previously discovered that a polyimide compound obtained from 2.3.5-tricarboxycyclopentyl acetic acid or its anhydride is soluble in certain organic solvents and has high storage stability, and filed a patent application ( (Japanese Patent Application No. 58-73884). Since this polyimide compound is soluble in a certain organic solvent, a film of the polyimide compound can be produced by casting the solution onto a smooth surface. In this case, a smooth and homogeneous film can be obtained since no dehydration reaction is involved during film production, but further improvements in the heat resistance and aqueous properties of the resulting polyimide compound were desired. .

[Object of the Invention] The object of the present invention is to improve the method for producing a polyimide compound disclosed in the above-mentioned Japanese Patent Application No. 73884/1984, and to produce an organic solvent-soluble polyimide compound with further improved heat resistance, anti-cough properties, and light transmittance. The objective is to provide a manufacturing method for

[Structure of the Invention] According to the present invention, (A) 25 mol% or more of 2,3.5-tricarboxycyclopentyl acetic acid dianhydride (hereinafter referred to as rTCA-AHJ) and 3 mol of aromatic tetracarboxylic dianhydride; % or more and (B) an organic diamine.

Among the two types of tetracarboxylic dianhydrides (hereinafter collectively referred to as "tetracarboxylic anhydrides") as component (A) used in the present invention, TCA/AH contains, for example, dicyclopentadiene. Method of ozonolysis and oxidation with hydrogen peroxide (British Patent No. 872355, J, Org, C
hem, 28.2537 (1983)), or a method of oxidizing hydroxydicyclopentadiene obtained by hydrating dicyclopentadiene with nitric acid (West German Patent No. 107)
It can be produced by dehydrating a tetracarboxylic acid obtained by a method such as No. 8120).

Specific examples of the aromatic tetracarboxylic dianhydride of component (A) include pyromellitic dianhydride, 3,3'',
4,4°-henzophenonetetracarboxylic dianhydride,
3,3'',4,4°-biphenylsulfonetetracarboxylic dianhydride, 1,2,5.8-naphthalenetetracarboxylic dianhydride, 1,4,5.8-naphthalenetetracarboxylic dianhydride , 2,3,8.7-naphthalenetetracarboxylic dianhydride, furantetracarboxylic dianhydride, 3,3°, 4,4°-biphenylethertetracarboxylic dianhydride, 3,3°, 4 , 4°-dimethyldiphenylsilane tetracarboxylic dianhydride, 3,3°, 4,
Examples include 4°-tetraphenylsilane tetracarboxylic dianhydride, 3.3', 4.4°-perfluoroisopropylidene tetracarboxylic dianhydride, and preferably pyromellitic dianhydride, 3,3°, 4,4°
-benzophenonetetracarboxylic dianhydride, 3°3'
, 4,4'-biphenylsulfone tetracarboxylic dianhydride can be used. The above aromatic tetracarboxylic dianhydrides can be used alone or in combination of two or more.

When two or more aromatic tetracarboxylic dianhydrides are combined, the resulting polyimide compound has better solubility and heat resistance, and is easy to obtain or synthesize. 3,3°,
4,4"-benzophenonetetracarboxylic dianhydride; 3.3°,4,4-benzophenonetetracarboxylic dianhydride and 3.3',4,4°-biphenylsulfonetetracarboxylic dianhydride: pyro Mellitic dianhydride and 3,3",4.4'-henzophenonetetracarboxylic dianhydride and 3,3°,4,4
Combinations such as °-biphenylsulfone tetracarboxylic dianhydride are preferred.

In the production method of the present invention, the tetracarboxylic acid collection of component (A) is blended so that the proportion of TCAφAH is 25 mol% or more and the aromatic tetracarboxylic dianhydride is 3 mol% or more. be exposed. Preferably, the aromatic tetracarboxylic dianhydride is blended in an amount of 5 to 65 mol%, more preferably 10 to 60 mol%. If the amount of aromatic tetracarboxylic dianhydride is less than 3 mol%, no improvement in heat resistance and anti-cough properties can be expected, and if it exceeds 75 mol%, the light transmittance of the resulting polyimide compound will deteriorate, and It is also insoluble in organic solvents.

In addition, as the organic diamine of the component (B) used in the present invention, a compound represented by the general formula: H2N-R-NH2... (I) (R is a divalent aromatic group, an aliphatic group, a (representing a cyclic group or an organosiloxane group). In the above general formula (I) (wherein X1.x2 , x3
and x4 may be the same or different, -Hl-CH
3 or 10CH3, Y represents -CH2-5-C2H4-1-〇-1-S-1 SO2- or -CONH-, n represents O or 1); ( CH2) n -(n=2-20), CH3 ■ -(CH2)3 C-(CH2)3-1CH3 Divalent aliphatic group or alicyclic group having 2 to 20 carbon atoms; etc. aliphatic, cycloaliphatic or aromatic hydrocarbon CTL
Indicates a monovalent aliphatic, alicyclic or aromatic hydrocarbon group such as H2n+t - (n = 1 to 20), m
is an integer from 1 to 100].

Specific examples of organic diamines represented by the general formula CI) are as follows:
Paraphenylenediamine, metaphenylenecyamine, 4
．． 4'-diaminodiphenylmethane, 4'-4'-diaminodiphenylethane, benzidine, 4'4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 3
, 3°-diaminobenzophenone, 4.4′-diaminobenzophenone, 1,5-diaminonaphthalene, 3,3
°-dimethyl-4,4°-diaminobiphenyl, 3,4
°-Diaminobenzanilide, 3,4°-diaminodiphenyl ether, metaxylylene diamine, paraxylylene diamine, ethylene diamine, 1,3-propanediamine, tetramethylene diamine, pentamethylene diamine, hexamethylene diamine, heptamethylene diamine, octa methylene diamine, nonamethylene diamine,
4,4゜-dimethylhbutamethylenediamine, 1,4-
Diaminocyclohexane, tetrahydrodicyclopentadienylene diamine, hexahydro-4,7-methanoindanilene shimethylene diamine, tricyclo[8,2,
1,02.7]-landecylenedimethyldiamine, and diaminoorganosiloxanes represented by the following. These organic diamines can be used alone or in combination of two or more.

Among these organic diamines, aromatic diamines such as 4,4°-diaminodiphenyl ether, which are represented by polyimide compounds in which R in the general formula (I) is an aromatic group, have higher heat resistance. ,
In the case of diamines represented by 4,4°-diaminodiphenylmethane and 4,4°-diaminodiphenylsulfone,
The resulting polyimide compound has excellent solubility and is also soluble in cyclohexanone, γ-butyrolactone, and the like.

To carry out the production method of the present invention, first, a mixture of tetracarboxylic acid anhydrides as component (A) and an organic diamine as component (B) are reacted in an organic solvent to obtain an organic solvent solution of polyamic acid. The obtained organic solvent solution of polyamic acid is used as it is, or the polyamic acid is recovered from the organic solvent solution by a conventional method, purified if necessary, and then dissolved in an organic solvent again before being subjected to an imidization reaction. .

The reaction ratio of the tetracarboxylic acid anhydride (A) component and the organic diamine (B) component is preferably carried out in equimolar terms, but as long as the desired polyamic acid is obtained,
The ratio of these seven factors may be slightly varied. For example, in order to obtain a high molecular weight polyamic acid, 0.7 to 0.7 to
It is preferable to use about 1.3 mol. Moreover, the molecular weight of the polyamic acid can also be adjusted by adding a monoamine or a dicarboxylic acid anhydride. The reaction temperature when producing polyamic acid is generally 0 to 100°C, preferably 5 to 60°C. The organic solvent used in this reaction is generally preferably an aprotic polar solvent, such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, or N.

N-dimethylformamide, dimethylsulfoxide, tetramethylurea, hexamethylphosphoric triamide, γ-
Examples include butyrolactone. In addition to these polar solvents, common organic solvents such as alcohols, phenols, ketones, esters, lactones, ethers,
halogenated hydrocarbons, hydrocarbons such as methyl alcohol, ethyl alcohol, inpropyl alcohol,
Ethylene glycol, propylene glycol, 1.4
-Butanediol, triethylene glycol, ethylene glycol methyl ether, phenol, m-cresol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methyl acetate, ethyl acetate, butyl acetate, diethyl oxalate, diethyl malonate, γ-butyrolactone , diethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, dichloromethane,
1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, 0-dichlorobenzene, hexane, heptane, octane, pentene, toluene, xylene, and the like can also be used. It is desirable to use these general organic solvents in combination with the above-mentioned aprotic organic solvent, and when used in combination, it becomes easier to obtain a high molecular weight polyamic acid. For example, when a tetracarboxylic acid anhydride and an organic diamine are reacted using a solvent of about 7/3 (volume ratio) of acetone/dimethylformamide, the reaction system becomes homogeneous, and a polyamic acid having a particularly high molecular weight can be easily obtained. The amount of solvent used is usually 0.1 to 50 times the total amount of the mixture of tetracarboxylic acid anhydride and organic diamine, but preferably 0.5 to 2 times the amount by weight.
0 times the weight.

The polyamic acid thus obtained is then subjected to an imidization reaction. In this imidization reaction, the above-mentioned aprotic polar solvent is suitably used as a solvent. Therefore, when an aprotic polar solvent is used in the above reaction of the tetracarboxylic acid anhydride and the organic diamine, the obtained polyamic acid solution can be used as it is in the imidization reaction. If an organic solvent other than an aprotic polar solvent is used in the reaction between a tetracarboxylic acid anhydride and an organic diamine, collect the polyamic acid using a conventional method, purify it if necessary, and then use the aprotic acid again. It is desirable to carry out the imidization reaction by dissolving in a polar solvent.

As a method for imidizing polyamic acid, an organic solvent solution of polyamic acid obtained in this way is
A method of advancing the imidization reaction by heating to 50 ° C., a method of advancing the imidization reaction by heating an organic solvent solution of polyamic acid at 60 to 150 ° C. and distilling off the water produced in the reaction out of the system. A method can be used in which a tertiary amine is added as needed in the presence of an organic carboxylic anhydride, and the polyamic acid solution is heated to advance the imidization reaction.

In general, the last method listed above among the above-mentioned methods is preferred because it facilitates control of the imidization reaction. In this method, the concentration of the polyamic acid solution in an organic solvent is preferably 1 to 50% by weight, particularly preferably 1 to 3% by weight.
It is 0% by weight. Further, the boiling point of the organic carboxylic acid anhydride used in the imidization reaction 2w is preferably 250°C or lower. If the boiling point of the organic carboxylic acid anhydride exceeds 250°C, the organic carboxylic acid anhydride will not be removed at the same time during the process of removing the solvent by heating when forming a film using the imidization reaction solution as it is, and It will remain and have an adverse effect on physical properties, etc. Examples of such organic carboxylic anhydrides include acetic anhydride, propionic anhydride, acetic anhydride, isobutyric anhydride, and valeric anhydride. Mixed acid anhydrides of these organic carboxylic acids, such as acid anhydrides obtained from acetic acid and propionic acid, can also be used. When using organic carboxylic acid anhydride, the amount used is 1 mole of repeating structural unit of polyamic acid.
0.2 to 20 times the mole is preferable. When the amount is less than 0.2 times the mole, the imidization reaction progresses slowly, and when the amount exceeds 20 times the mole, the solubility of the polyamic acid in the organic solvent decreases. Furthermore, in order to accelerate the imidization reaction when using an organic carboxylic acid anhydride, a tertiary amine can be added as a catalyst if necessary. In addition, there is also an effect of suppressing a decrease in the solution viscosity of the obtained polyimide.

The tertiary amine preferably has a boiling point of 250° C. or lower for the same reason as in the case of organic carboxylic acid anhydrides, such as aliphatic tertiary amines such as triethylamine, tripropylamine, and tributylamine;

Examples include aromatic tertiary amines such as N-dimethylaniline, and heterocyclic compounds such as pyridine, 2-methylpyridine, N-methylimitanol, quinoline, and inquinoline.

The amount of the tertiary amine added is preferably 20 times or less in mole per mole of repeating structural unit of the polyamic acid. When the amount exceeds 20 times the mole, the solubility of polyamic acid in organic solvents tends to decrease. The reaction temperature of the imidization reaction when using an organic carboxylic acid anhydride is preferably 0 to 20
The temperature is 0°C, particularly preferably 20 to 170°C. If the temperature is lower than 0°C, the progress of the imidization reaction will be delayed, and if the temperature exceeds 200°C, the molecular weight of the polyimide will decrease significantly. The organic carboxylic acid anhydride and the tertiary amine may be added in any order, or may be added after mixing them.

The polyimide compound thus obtained is produced by casting an organic solvent solution of the polyimide compound onto the smooth surface of a base material such as a glass plate or metal plate, and then removing the organic solvent etc. by heating or other methods. By doing so, it can be made into a film. Alternatively, the polyimide compound can be recovered from the organic solvent solution of the polyimide compound after the reaction, redissolved in the organic solvent, and then formed into a film by the above method. Examples of the organic solvent used for this redissolution include the aforementioned aprotic polar solvents and phenolic solvents.

Intrinsic viscosity η of the polyimide compound obtained in this way
1nh (@ degree 0.5g/100ml, solvent m-cresol or dimethylformamide, measurement temperature 30℃)
is preferably 0.05 dl/g or more, particularly preferably 0.05 to 20 dl/g. Intrinsic viscosity is 0.05d
If it is less than 1/g, moldability will be insufficient and undesirable.

(t is the flow rate of the polymer solution, to is the flow rate of m-cresol, dimethylformamide or N-methylpyrrolidone).

[Effects of the Invention] The polyimide compound obtained by the production method of the present invention is easily dissolved in the above-mentioned certain organic solvents, and is very stable in a solution state, so that it can be stored for a long period of time. In addition, the polyimide compound exhibits excellent properties such as heat resistance, mechanical properties, electrical properties, and chemical resistance properties, and is particularly characterized by excellent tensile water resistance, heat resistance, and light transmittance. For example, it is useful for high-temperature films, adhesives, paints, etc. Specifically, it is useful for printed wiring boards, flexible wiring boards, surface protection films or interlayer insulation films for semiconductor integrated circuit elements, liquid crystal alignment films, coating materials for enameled electric wires, Useful for various laminates, gaskets, etc.

[Examples] The present invention will be explained in further detail using nine examples below, but the present invention is not limited to these examples.

Example 1 In a one-liter flask, 4,4°-diaminodiphenyl ether (D D E) was added to 200+ g of dimethylformamide (DMF) under nitrogen flow. OOg(0,1
00 mol), and 5.45 g (0,025 mol) of pyromellitic dianhydride was added to the resulting solution at 25°C with stirring.
and TCA・A HIEL, 81 g (0,0'?5 mol)
was added as a powder, and the mixture was reacted at 25° C. for 18 hours to obtain polyamic acid.

After diluting the obtained polyamic acid solution by adding 200 ml of DMF, 55.4 g of pyridine and 51 ml of acetic anhydride were added.
．． 0g was added and the reaction was carried out at 90°C for 3 hours to synthesize a polyimide compound. The obtained polyimide compound solution was poured into a large amount of methanol and coagulated. The solidified polyimide compound was vacuum dried at 100°C for 1814 minutes. The obtained polyimide compound was soluble in aprotic polar solvents such as DMF and N-methyl-2-pyrrolidone, and phenolic solvents such as m-cresol.

When the infrared absorption spectrum of the obtained polyimide compound was measured, the spectrum shown in FIG. 1 was obtained. 1780c
+r'', 1730cm-1 based on imide group <>C-
0 stretching vibration appears, and the C=O stretching vibration of
It was found that imidization of 5% or more was progressing.

A predetermined amount of DMF was added to this polyimide compound to give a concentration of 15% by weight, and the solution was cast onto the smooth surface of a glass plate. The mixture was further dried by heating at 200°C for xi hours to completely remove the solvent and obtain a uniform yellow transparent film with a thickness of 25 gm. The tensile strength of the obtained polyimide compound film was determined. In addition, the temperature for 10% thermal decomposition was measured from thermogravimetric analysis (under nitrogen flow, temperature increase rate: 10°C/11in). Furthermore, the light transmittance of this polyimide compound film for light with a wavelength of 400 nm was determined and converted into a film thickness of 10 gm. Further, the water absorption rate of this polyimide compound film was determined by the method specified in JIS C8481 (immersion temperature: 25°C x 24 hours).

These results are shown in Table 1.

Example 2 In Example 1, 3 was used instead of pyromellitic a dianhydride.
,3°,4,4°-benzophenonetetracarboxylic dianhydride (hereinafter abbreviated as BTDA) 8.0Eig (0
, 025 mol), 18.81 g (
0,075 mol), a polyimide compound was produced in the same manner as in Example 1 except for the imidization conditions shown in Table 1, and a film with a thickness of 28 μm was produced. Table 1 shows the results of a test conducted in the same manner as in Example 1. Note that the obtained polyimide compound was soluble in aprotic polar solvents such as DMF and N-methyl-2-pyrrolidone, and phenolic solvents such as m-cresol.

Example 3 In Example 1, B was used instead of pyromellitic dianhydride.
The procedure was the same as in Example 1 except that 12 g (0,050 mol) of TDA 1B was used, 8.41 g (0,050 mol) of TCA-AH was used, and the imidization conditions shown in Table 1 were adopted. A polyimide compound was produced. The obtained polyimide was soluble in phenolic solvents such as m-cresol. From this polyimide compound, m is used as a solvent.
- A film having a thickness of 25 tiles was produced in the same manner as in Example 1 except that cresol was used. Table 1 shows the results of a test conducted in the same manner as in Example 1.

Example 4 In Example 1, B was used instead of pyromellitic dianhydride.
The procedure was the same as in Example 1 except that 24.18 g (0,075 mol) of TDA was used, 4.21 g (0,025 mol) of TCA@AH was used, and the imidization conditions shown in Table 1 were adopted. A polyimide compound was produced. The obtained polyimide was soluble in phenolic solvents such as m-cresol. From this polyimide compound, m is used as a solvent.
-A film having a thickness of 25 IL was prepared in the same manner as in Example 1 except that cresol was used. Table 1 shows the results of a test conducted in the same manner as in Example 1.

Example 5 In Example 1, pyromellitic dianhydride and TCA-
The amount of AH used was changed to 5.45 g (0,025 mol) and 8.41 g (0,050 mol), respectively, and
Using 8.08 g (0,025 mol) of TDA, Table 1
A polyimide compound was produced in the same manner as in Example 1, except that the imidization conditions shown in Figure 1 were used, and a film having a thickness of 30 mm was produced. Table 1 shows the results of a test conducted in the same manner as in Example 1.

Note that the obtained polyimide contains DMF, N-methyl-2
- It was soluble in aprotic polar solvents such as pyrrolidone and phenolic solvents such as m-cresol.

Example 6 In a one-liter flask, under nitrogen flow, add 12.54 ml of 2.5-(4-aminophenyl)-3,4-cyphenylthiophene to 200 ml of N-methylpyrrolidone (NMP).
4.83 g (0,015 mol) of B TDA and 3,36 g (0,015 mol) of TCA-AH were added to the resulting solution as a powder at 25°C with stirring. The mixture was added as is, and the mixture was reacted at 50° C. for 3 hours to obtain polyamic acid.

9.18 g of acetic anhydride and 11.73 g of pyridine were added to the obtained polyamic acid solution, and the mixture was reacted at 130° C. for 3 hours to synthesize a polyimide compound. The obtained polyimide compound solution was poured into a large amount of methanol and coagulated. The solidified polyimide compound was vacuum dried at 120° C. for 18 hours to obtain 19.8 g of product. When the infrared absorption spectrum of the produced polymer was measured, it was 1780c "", 1730c
C-O stretching vibration based on the imide group appears at m-',
Based on the amide group of polyamic acid < 1850 cm-1
It was found that the obtained polyimide compound had undergone imidization of at least 85% since the > C=O stretching vibration had disappeared. The intrinsic viscosity of this polyimide compound was 0.39 dl/g (in NMP). This polyimide compound was soluble in polar solvents such as DMF, NMP, γ-butyrolactone, and cyclohexanone, and phenolic solvents such as m-cresol.

Example 7 A polyimide compound was produced in the same manner as in Example 6, except that 3.27 g (0,015 mol) of pyromellitic dianhydride was added instead of BTDA.

The yield of the obtained polyimide compound was 17.0 g, and its intrinsic viscosity was 0.54 dl/g (in NMP).

This polyimide compound was soluble in aprotic polar solvents such as DMF, NMP, and γ-butyrolactone, and phenolic solvents such as m-cresol.

Comparative Example 1 In Example 1, pyromellitic dianhydride was not used,
A polyimide compound was produced in the same manner as in Example 1, except that the amount of TCA used was changed to 18.82 g (0,100 mol) and the imidization conditions shown in Table 1 were adopted. This polyimide compound was soluble in aprotic polar solvents such as DMF and N-methyl-2-pyrroliton. From the obtained polyimide compound, a thickness of 20 mm was prepared in the same manner as in Example 1.
A film of the seal was made. Table 1 shows the results of a test conducted in the same manner as in Example 1. .

Comparative Example 2 In Example 1, pyromellitic dianhydride and TC
B T D A 32.24 g (0,
A polyamic acid was synthesized in the same manner as in Example 1 except that 100 mol) was used, and then this polyamic acid was subjected to an imidization reaction in the same manner as in Example 1, but the polymer precipitated immediately after the start of the reaction. When the infrared absorption spectrum of the produced polymer was measured, imidization of the polyamic acid was progressing, but this polymer was insoluble in any organic solvent and it was impossible to form it into a film by casting the solution. .

Comparative Example 3 Polyamic acid was synthesized in the same manner as in Example 1, except that TCA-AH was not used and the amount of pyromellitic dianhydride used was 21.80 g (0,100 mol). Then, this polyamic acid was subjected to an imidization reaction in the same manner as in Example 1, but the polymer precipitated immediately after the start of the reaction. When the infrared absorption spectrum of the produced polymer was measured, imidization of the polyamic acid was progressing, but this polymer was insoluble in any organic solvent and it was impossible to form it into a film by casting the solution. .

Comparative Example 4 A polyamic acid was synthesized in the same manner as in Comparative Example 3, and the obtained polyamic acid solution was cast onto the smooth surface of a glass plate, and then heated at 300°C for 30 minutes to form a sheet with a thickness of 25 IL. A film of polyimide compound was obtained. The characteristic values of this film were measured in the same manner as in Example 1, and the results are shown in Table 1.

[Brief explanation of the drawing]

FIG. 1 shows the infrared absorption spectrum of the polyimide compound film of the present invention produced in Example 1.

Claims (1)

[Claims] A polyamic acid obtained from (A) a mixture consisting of 25 mol% or more of 2,3,5-tricarboxycyclopentyl acetic dianhydride and 3 mol% or more of aromatic tetracarboxylic dianhydride, and (B) an organic diamine. A method for producing an organic solvent-soluble polyimide compound comprising imidization.