POLYIMIDE SOLUTION, HEAT-RESISTANT NON-WOVEN FABRIC, AND METHOD FOR MANUFACTURING SAME

Abstract

The present invention provides a polyimide solution which does not require a ring-closing process at a high temperature for obtaining a heat-resistant polyimide non-woven fabric and which is hardly affected by atmosphere humidity in fiber production by electrospinning, so that a fiber with a stable diameter can be obtained in any circumstance.

A polyimide solution including: (a) a resin containing 50 mol % or more, based on the total amount of the resin, of a structural unit represented by the general formula (1); and (b) a solvent.

##STR00001##

Claims

1. A polyimide solution comprising: (a) a resin containing 50 mol % or more, based on the total amount of the resin, of a structural unit represented by the general formula (1); and (b) a solvent. ##STR00009## (In the formula, R.sup.1 and R.sup.2 each independently represent an alkyl group with a carbon number of 1 to 10, a fluoroalkyl group, a cyano group or a nitro group, and Z represents a hydroxyl group or a carboxyl group. Y represents a tetravalent organic group with a carbon number of 4 to 30. X represents one of the structures shown below. p, q, r and s each represent an integer of 0 to 4, where p+q is larger than 1. n represents an integer of 0 to 4. R.sup.3 and R.sup.4 each independently represent a hydrogen atom, an alkyl group with a carbon number of 1 to 4, a fluoroalkyl group, or a phenyl group. R.sup.5 to R.sup.11 each represent an alkyl group with a carbon number of 1 to 4, a fluoroalkyl group or a phenyl group, and may be the same or different. t represents an integer of 0 to 3.) ##STR00010##

2. The polyimide solution according to claim 1, wherein the resin has a specific inductive capacity of 3.2 or more.

3. The polyimide solution according to claim 1, wherein in the general formula (1), Y represents an organic group including diphenyl sulfone or diphenyl ketone.

4. The polyimide solution according to claim 1, wherein in the general formula (1), Y represents an organic group including benzene, cyclobutane, cycloheptane, cyclohexane, naphthalene, biphenyl, terphenyl, diphenyl ether, triphenyl ether, diphenylmethane or diphenylhexafloropropane.

5. The polyimide solution according to claim 1, wherein in the general formula (1), X represents a sulfone group or a ketone group, and each of p and q is equal to 0.

6. The polyimide solution according to claim 1, wherein 5 to 50 mol % of X is constituted by any one of the structures shown below. ##STR00011##

7. The polyimide solution according to claim 1, wherein 40 to 95 mol % of X is constituted by any one of the structures shown below. ##STR00012##

8. The polyimide solution according to claim 3, wherein 40 mol % or more of Y is constituted by diphenyl sulfone or diphenyl ketone.

9. The polyimide solution according to claim 4, wherein 5 to 50 mol % of Y is constituted by benzene.

10. A polyimide solution which contains a resin represented by the general formula (2), and (b) a solvent, and is used for formation of a non-woven fabric. ##STR00013## (In the formula, R.sup.12 represents a divalent organic group having at least two carbon atoms, and R.sup.13 represents a tetravalent organic group having at least two carbon atoms.)

11. A non-woven fabric which is formed using the polyimide solution according to claim 1.

12. A method for manufacturing the non-woven fabric according to claim 11, the method comprising forming the non-woven fabric by electrospinning.

13. The non-woven fabric according to claim 11, which is formed by electrospinning.

14. The non-woven fabric according to claim 11, which has a glass-transition point of 200° C. or higher.

15. A high-order processed article comprising the non-woven fabric according to claim 11.

16. The high-order processed article according to claim 15, which is used in a separator for batteries, an acoustic material, an electromagnetic shielding material, a separation filter or a heat-resistant bag filter.

17. A separator for electric double layer capacitors which comprises the non-woven fabric according to claim 11.

Description

EXAMPLES

[0074] Hereinafter, the present invention will be described by showing examples and techniques, but the present invention is not limited to these examples.

<Measurement of Water Absorption Ratio>

[0075] A 6-inch silicon wafer was spin-coated with a polyimide solution in such a manner that the film thickness would be about 15 μm after drying at 120° C. for 4 minutes. After the spin-coating, the coated solution was dried at 120° C. for 4 minutes by a hot plate attached to coating and developing equipment SCW-636 manufactured by Dainippon Screen Mfg. Co., Ltd., and was then subjected to a heating treatment at 300° C. for 1 hour using an inert oven INH-9CD manufactured by Koyo Thermo Systems Co., Ltd., thereby obtaining a polyimide film. The wafer with the film formed thereon was immersed in 45% aqueous hydrogen fluoride at room temperature for 3 minutes, and washed with deionized water for 10 minutes, and the film was separated from the wafer. The weight of the film was measured, the film was then dried at 200° C. for 1 hour, and the bone-dry weight was determined. The water absorption ratio was determined from the water-absorbing weight and the bone-dry weight using the following equation.

water absorption ratio=(water-absorbing weight−bone-dry weight)/bone-dry weight×100(%)

<Measurement of Specific Inductive Capacity>

[0076] An aluminum substrate was spin-coated with a polyimide solution. After the spin-coating, the coated solution was dried at 120° C. for 4 minutes by a hot plate attached to coating and developing equipment SCW-636 manufactured by Dainippon Screen Mfg. Co., Ltd., and was then subjected to a heating treatment at 300° C. for 1 hour using an inert oven INH-9CD manufactured by Koyo Thermo Systems Co., Ltd., thereby obtaining a polyimide film with a thickness of 5 μm. An upper aluminum electrode was deposited on the film using vacuum deposition equipment EBH-6 manufactured by Japan Vacuum Engineering Co., Ltd., thereby obtaining a measurement sample.

[0077] The capacitance at 1 MHz was then measured using a LCR meter 4284 A manufactured by Yokogawa Hewlett-Packard, and the specific inductive capacity (s) was determined from the following equation.

∈=C.Math.d/∈.sub.0.Math.S

(where C is a capacitance (unit: F), d is a sample film thickness (unit: m), ∈.sub.0 is a dielectric constant in vacuum, and S is an upper electrode area (unit: m.sup.2))

<Measurement of Glass-Transition Point>

[0078] A silicon substrate was spin-coated with a polyimide solution. After the spin-coating, the coated solution was dried at 120° C. for 4 minutes by a hot plate attached to coating and developing equipment SCW-636 manufactured by Dainippon Screen Mfg. Co., Ltd., and was then subjected to a heating treatment at 300° C. for 1 hour using an inert oven INH-9CD manufactured by Koyo Thermo Systems Co., Ltd., thereby obtaining a polyimide film with a thickness of 10 μm. The wafer with the film formed thereon was immersed in 45% aqueous hydrogen fluoride at room temperature for 3 minutes, and washed with deionized water for 10 minutes, and the film was separated from the wafer. The film was dried at 120° C. for 2 hours to remove water, and cut out so as to have a weight of 5 mg. The sample was heated from room temperature to 400° C. at a temperature rise rate of 10° C./min to measure the glass-transition point using DSC-50 manufactured by Shimadzu Corporation.

Example 1

[0079] In a 500 mL three-necked flask equipped with a N.sub.2 gas inflow glass tube, a stirrer and a thermometer, 3.66 g of 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (0.01 mol; manufactured by AZ Electronic Materials Co., Ltd.) and 3.20 g of 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (0.01 mol; manufactured by Wakayama Seika Kogyo Co., Ltd.) were dissolved in 30 g of N-methyl-2-pyrrolidone (NMP; manufactured by Mitsubishi Chemical Corporation) and 10 g of toluene (manufactured by Tokyo Chemical Industry Co., Ltd.) under a dry nitrogen gas flow at 40° C. or lower. To the solution was added 4.36 g of pyromellitic dianhydride (0.02 mol; manufactured by Daicel Chemical Industries, Ltd.), the mixture was stirred at 40° C. for 2 hours, the liquid temperature was then raised to 180° C., and the mixture was further stirred for 4 hours, and reacted while distilled toluene and water were removed.

[0080] The resin solution thus obtained was filtered by a 2 μm of polytetrafluoroethylene membrane filter to obtain a polyimide solution. A 4-inch silicon wafer was spin-coated with the polyimide solution in an atmosphere at room temperature and a humidity of 50%. The solution was not whitened even after being left standing for 120 seconds after the coating.

[0081] The water absorption ratio was 1.9%, the specific inductive capacity was 2.9, and the glass-transition point was 170° C.

Example 2

[0082] In a 500 mL three-necked flask equipped with a N.sub.2 gas inflow grass tube, a stirrer and a thermometer, 22.8 g of bis(3-amino-4-hydroxyphenyl)fluolene (0.06 mol; manufactured by AZ Electronic Materials Co., Ltd.) and 4.88 g of 2,4-diaminotoluene (0.04 mol; manufactured by Tokyo Chemical Industry Co., Ltd.) were dissolved in 235 g of NMP and 10 g of toluene (manufactured by Tokyo Chemical Industry Co., Ltd.) under a dry nitrogen gas flow at 40° C. or lower. To the solution was added 31.0 g of 3,3′,4,4′-diphenylethertetracarboxylic dianhydride (0.1 mol; manufactured by MANAC Inc.), and the mixture was stirred at 40° C. for 1 hour, the temperature of the solution was then raised to 180° C., and the solution was stirred for 6 hours.

[0083] The resin solution thus obtained was filtered by a 2 μm of polytetrafluoroethylene membrane filter to obtain a polyimide solution. A 4-inch silicon wafer was spin-coated with the polyimide solution in an atmosphere at room temperature and a humidity of 50%. The solution was not whitened even after being left standing for 120 seconds after the coating.

[0084] The water absorption ratio was 1.5%, the specific inductive capacity was 3.2, and the glass-transition point was 200° C.

Example 3

[0085] In a 500 mL three-necked flask equipped with a N.sub.2 gas inflow glass tube, a stirrer and a thermometer, 11.5 g of 2,2-bis(3-carboxyl-4-aminophenyl)methane (manufactured by Wakayama Seika Kogyo Co., Ltd.; 0.05 mol) and 12.8 g of 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (manufactured by Wakayama Seika Kogyo Co., Ltd.; 0.04 mol) and 2.48 g of 1,3-bis(3-aminopropyl)tetramethyldisiloxane (manufactured by Shin-Etsu Chemical Co., Ltd.; 0.01 mol) were dissolved in 240 g of NMP under a dry nitrogen gas flow at 40° C. or lower. To the solution were added 10.9 g of pyromellitic dianhydride (manufactured by Daicel Chemical Industries, Ltd.; 0.05 mol) and 22.2 g of 2,2-bis(hexafluoropropane)phthallic anhydride (0.05 mol; manufactured by Daikin Industries, Ltd.), the mixture was stirred at 40° C. for 2 hours, the liquid temperature was then raised to 180° C., and the mixture was further stirred for 4 hours, and reacted while distilled toluene and water were removed.

[0086] The resin solution thus obtained was filtered by a 2 μm of polytetrafluoroethylene membrane filter to obtain a polyimide solution. A 4-inch silicon wafer was spin-coated with the polyimide solution in an atmosphere at room temperature and a humidity of 50%. The solution was not whitened even after being left standing for 120 seconds after the coating.

[0087] The water absorption ratio was 2.5%, the specific inductive capacity was 3.0, and the glass-transition point was 180° C.

Example 4

[0088] In a 500 mL three-necked flask equipped with a N.sub.2 gas inflow glass tube, a stirrer and a thermometer, 28.0 g of bis(3-amino-4-hydroxyphenyl) sulfone (0.1 mol; manufactured by AZ Electronic Materials Co., Ltd.) was dissolved in 230 g of NMP and 10 g of toluene under a dry nitrogen gas flow at 40° C. To the solution were added 10.9 g of pyromellitic dianhydride (manufactured by Daicel Chemical Industries, Ltd.; 0.05 mol) and 17.9 g of 3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride (0.05 mol; manufactured by New Japan Chemical Co., Ltd.), the mixture was stirred at 40° C. for 2 hours, the liquid temperature was then raised to 180° C., and the mixture was further stirred for 4 hours, and reacted while distilled toluene and water were removed.

[0089] The resin solution thus obtained was filtered by a 2 μm of polytetrafluoroethylene membrane filter to obtain a polyimide solution. A 4-inch silicon wafer was spin-coated with the polyimide solution in an atmosphere at room temperature and a humidity of 50%. The solution was not whitened even after being left standing for 120 seconds after the coating. The water absorption ratio was 9.0%, the specific inductive capacity was 3.6, and the glass-transition point was 220° C.

Example 5

[0090] In a 500 mL three-necked flask equipped with a N.sub.2 gas inflow glass tube, a stirrer and a thermometer, 14.9 g of bis(3-amino-4-hydroxyphenyl)cyclohexane (0.05 mol; manufactured by Tokyo Chemical Industry Co., Ltd.) and 12.8 g of 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (0.04 mol; manufactured by Wakayama Seika Kogyo Co., Ltd.) and 2.48 g of 1,3-bis(3-aminopropyl)tetramethyldisiloxane (manufactured by Shin-Etsu Chemical Co., Ltd.; 0.01 mol) were dissolved in 205 g of NMP under a dry nitrogen gas flow at 40° C. or lower. To the solution were added 10.9 g of pyromellitic dianhydride (0.05 mol; manufactured by Daicel Chemical Industries, Ltd.) and 9.8 g of cyclobutanoic anhydride (0.05 mol; manufactured by Tokyo Chemical Industry Co., Ltd.), the mixture was stirred at 40° C. for 2 hours, the liquid temperature was then raised to 180° C., and the mixture was further stirred for 4 hours, and reacted while distilled toluene and water were removed.

[0091] The resin solution thus obtained was filtered by a 2 μm of polytetrafluoroethylene membrane filter to obtain a polyimide solution. A 4-inch silicon wafer was spin-coated with the polyimide solution in an atmosphere at room temperature and a humidity of 50%. The solution was not whitened even after being left standing for 120 seconds after the coating.

[0092] The water absorption ratio was 1.4%, the specific inductive capacity was 2.9, and the glass-transition point was 190° C.

Example 6

[0093] In a 500 mL three-necked flask equipped with a N.sub.2 gas inflow glass tube, a stirrer and a thermometer, 1.04 g of bis(3-amino-4-hydroxyphenyl)cyclopentane (0.05 mol; manufactured by Tokyo Chemical Industry Co., Ltd.) and 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (0.05 mol; manufactured by Wakayama Seika Kogyo Co., Ltd.) were dissolved in 40 g of N-methyl-2-pyrrolidone (NMP; manufactured by Mitsubishi Chemical Corporation) under a dry nitrogen gas flow at 40° C. or lower. To the solution were added 10.9 g of pyromellitic dianhydride (0.05 mol; manufactured by Daicel Chemical Industries, Ltd.) and 22.2 g of cyclobutanoic anhydride (0.05 mol; manufactured by Tokyo Chemical Industry Co., Ltd.), the mixture was stirred at 40° C. for 2 hours, the liquid temperature was then raised to 180° C., and the mixture was further stirred for 4 hours, and reacted while distilled toluene and water were removed.

[0094] The resin solution thus obtained was filtered by a 2 μm of polytetrafluoroethylene membrane filter to obtain a polyimide solution. A 4-inch silicon wafer was spin-coated with the polyimide solution in an atmosphere at room temperature and a humidity of 50%. The solution was not whitened even after being left standing for 120 seconds after the coating.

[0095] The water absorption ratio was 1.5%, the specific inductive capacity was 2.9, and the glass-transition point was 180° C.

Comparative Example 1

[0096] In a 500 mL three-necked flask equipped with a N.sub.2 gas inflow glass tube, a stirrer and a thermometer, 2.8 g of 4,4′-diaminodiphenyl ether (0.05 mol; manufactured by Wakayama Seika Kogyo Co., Ltd.) and 1.60 g of 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (0.05 mol; manufactured by Wakayama Seika Kogyo Co., Ltd.) were dissolved in 40 g of NMP and 10 g of toluene (manufactured by Tokyo Chemical Industry Co., Ltd.) in under a dry nitrogen gas flow at 40° C. To the solution was added 22.2 g of 2,2-bis(hexafluoroisopropylidene)phthallic anhydride (0.05 mol; manufactured by Daikin Industries, Ltd.), the mixture was stirred at 40° C. for 2 hours, the liquid temperature was then raised to 180° C., and the mixture was further stirred for 4 hours, and reacted while distilled toluene and water were removed.

[0097] The resin solution thus obtained was filtered by a 2 μm of polytetrafluoroethylene membrane filter to obtain a polyimide solution. A 4-inch silicon wafer was spin-coated with the polyimide solution in an atmosphere at room temperature and a humidity of 50%. The whole coated film was whitened due to moisture absorption 30 seconds after the coating.

[0098] The water absorption ratio was 1.0%, the specific inductive capacity was 2.6, and the glass-transition point was 170° C.

Example 7

[0099] The polyimide solution obtained in Example 1 was diluted to a concentration of 12%, and applied onto an earthed aluminum foil at a voltage of 15 kV under an environment at a temperature of 24° C. and a humidity of 50% using an electrospray coater while the solution was fed at the rate of 20 μL/min using a needle having a nozzle inner diameter of 0.84 mm (G18) (the distance between the nozzle and the aluminum foil was 250 mm). As a result, a polyimide non-woven fabric was formed on the aluminum foil.

Comparative Example 2

[0100] The same procedure as in Example 7 was carried out to prepare a polyimide non-woven fabric from the polyimide solution obtained in Comparative Example 1, but moisture absorption occurred, so that a white fragile film was formed, and thus a tough non-woven fabric was not obtained.

Examples 8 to 25 and Comparative Example 3

[0101] Except that a diamine, an amount of NMP and an acid dianhydride as shown in Tables 1 and 2 were used in place of 3.66 g of 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (0.01 mol; manufactured by AZ Electronic Materials Co., Ltd.), 3.20 g of 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (0.01 mol; manufactured by Wakayama Seika Kogyo Co., Ltd.), 30 g of N-methyl-2-pyrrolidone (NMP; manufactured by Mitsubishi Chemical Corporation) and 4.36 g of pyromellitic dianhydride (0.02 mol; manufactured by Daicel Chemical Industries, Ltd.), the same procedure as in Example 1 was carried out to obtain a polyimide solution. A 4-inch silicon wafer was spin-coated with the polyimide solution in an atmosphere at room temperature and a humidity of 50%, and occurrence of whitening over the whole coated film, and the water absorption ratio, the specific inductive capacity and the glass-transition point of the coated film were measured.

Examples 26 to 48 and Comparative Example 4

[0102] Using the polyimide solution obtained in each of Examples 2 to 6, Examples 8 to 25 and Comparative Example 3, a non-woven fabric formation test was conducted in the same manner as in Example 7, and the non-woven fabric formation state and the average of the diameters of fibers forming the non-woven fabric were measured.

[0103] The results of examples and comparative examples are shown in Tables 1, 2 and 3.

TABLE-US-00001 TABLE 1 Glass- Amount of Water absorption transition NMP Film ratio Specific point Diamine component (g) Acid dianhydride component whitening (%) inductive (° C.) Example 1 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (3.66 g) (0.01 mol; 30 Pyromellitic dianhydride (4.36 g) (0.02 mol; Not 1.9 2.9 170 manufactured by AZ Electronic Materials Co., Ltd.) manufactured by Daicel Chemical Industries, Ltd.) observed 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (3.20 g) (0.01 mol; manufactured by Wakayama Seika Kogyo Co., Ltd.) Example 2 bis(3-amino-4-hydroxyphenyl)fluorene (22.8 g) (0.06 mol; manufactured 235 3,3′,4,4′-diphenylethertetracarboxylic dianhydride Not 1.5 3.2 2.00 by AZ Electronic Materials Co., Ltd.) (31.0 g) (0.1 mol; manufactured by MANAC Inc.) observed 2,4-diaminotoluene (4.88 g) (0.04 mol; manufactured by Tokyo Chemical Industry Co., Ltd.) Example 3 2,2-bis(3-carboxyl-4-aminophenyl)methane (11.5 g) (0.05 mol; 240 Pyromellitic dianhydride (10.9 g) (0.05 mol; Not 2.5 3 180 manufactured by Wakayama Seika Kogyo Co., Ltd.) manufactured by Daicel Chemical Industries, Ltd.) observed 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (12.8) g (0.04 mol; 2,2-bis(hexafluoropropane) phthalic anhydride (22.2 g) manufactured by Wakayama Seika Kogyo Co., Ltd.) (0.05 mol; manufactured by Daikin Industries, Ltd.) 1,3-bis(3-aminopropyl)tetramethyldisiloxane (2.48 g) (0.01 mol; manufactured by Shin-Etsu Chemical Co., Ltd.) Example 4 bis(3-amino-4-hydroxyphenyl) sulfone (28.0 g) (0.01 mol; manufactured 230 Pyromellitic dianhydride (10.9 g) (0.05 mol; Not 9 3.6 220 by AZ Electronic Materials co., Ltd.) manufactured by Daicel Chemical Industries, Ltd.) observed 3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride (17.9 g) (0.05 mol; manufactured by New Japan Chemical Co., Ltd.) Example 5 bis(3-amino-4-hydroxyphenyl)cyclohexane (14.9 g) (0.05 mol; 205 Pyromellitic dianhydride (10.9 g) (0.05 mol; Not 1.4 2.9 190 manufactured by Tokyo Chemical Industry Co., Ltd.) manufactured by Daicel Chemical Industries, Ltd.) observed 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (12.8) g (0.04 mol; Cyclobutanoic dianhydride (9.8 g) (0.05 mol; manufactured by Wakayama Seika Kogyo Co., Ltd.) manufactured by Tokyo Chemical Industry Co., Ltd.) 1,3-bis(3-aminopropyl)tetramethyldisiloxane (2.48 g) (0.01 mol; manufactured by Shin-Etsu Chemical Co., Ltd.) Example 6 bis(3-amino-4-hydroxyphenyl)cyclopentane (1.04 g) (0.05 mol; 40 Pyromellitic dianhydride (10.9 g) (0.05 mol; Not 1.5 2.9 180 manufactured by Tokyo Chemical Industry Co., Ltd.) manufactured by Daicel Chemical Industries, Ltd.) observed 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (16.0 g) (0.05 mol; Cyclobutanoic dianhydride (22.2 g) (0.05 mol; manufactured by Wakayama Seika Kogyo Co., Ltd.) manufactured by Tokyo Chemical Industry Co., Ltd.) Example 8 3,3′-diaminodiphenyl sulfone (24.3 g): 0.098 mol; manufactured by 130 3,3′,4,4′-diphenylethertetracarboxylic dianhydride Not 3.5 3.3 180 Wakayama Seika Kogyo Co., Ltd.) (31.0 g) (0.1 mol; manufactured by MANAC Inc.) observed bis(3-amino-4-hydroxyphenyl)fluorene (0.760 g) (0.002 mol; manufactured by AZ Electronic Materials Co., Ltd.) Example 9 3,3′-diaminodiphenyl sulfone (23.6 g): 0.095 mol; manufactured by 132 3,3′,4,4′-diphenylethertetracarboxylic dianhydride Not 2.5 3.3 190 Wakayama Seika Kogyo Co., Ltd.) (31.0 g) (0.1 mol; manufactured by MANAC Inc.) observed bis(3-amino-4-hydroxyphenyl)fluorene (1.90 g) (0.005 mol; manufactured by AZ Electronic Materials Co., Ltd.) Example 10 3,3′-diaminodiphenyl sulfone (9.93 g): 0.04 mol; manufactured by 149 3,3′,4,4′-diphenylethertetracarboxylic dianhydride Not 1.5 3.3 210 Wakayama Seiko Kogyo Co., Ltd.) (31.0 g) (0.1 mol; manufactured by MANAC Inc.) observed bis(3-amino-4-hydroxyphenyl)fluorene (22.8 g) (0.06 mol; manufactured by AZ Electronic Materials Co. Ltd.) Example 11 3,3′-diaminodiphenyl sulfone (7.45 g): 0.03 mol; manufactured by 152 3,3′,4,4′-diphenylethertetracarboxylic dianhydride Not 1.5 3.2 210 Wakayama Seika Kogyo Co., Ltd.) (31.0 g) (0.1 mol; manufactured by MANAC Inc.) observed bis(3-amino-4-hydroxyphenyl)fluorene (26.6 g) (0.07 mol; manufactured by AZ Electronic Materials Co., Ltd.) Example 12 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (1.83 g) (0.005 mol; 161 3,3′,4,4′-diphenylethertetracarboxylic dianhydride Not 1.5 3.2 200 manufactured by AZ Materials) (31.0 g) (0.1 mol; manufactured by MANAC Inc.) observed bis(3-amino-4-hydroxyphenyl)fluorene (36.1 g) (0.095 mol; manufactured by AZ Electronic Materials Co., Ltd.) Example 13 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (18.3 g) (0.05 mol; 159 3,3′,4,4′-diphenylethertetracarboxylic dianhydride Not 1.2 3 180 manufactured by AZ Materials) (31.0 g) (0.1 mol; manufactured by MANAC Inc.) observed bis(3-amino-4-hydroxyphenyl)fluorene (19.0 g) (0.05 mol; manufactured by AZ Electronic Materials Co., Ltd.)

TABLE-US-00002 TABLE 2 Amount Water absorption Glass-transition of NMP Film ratio Specific point Diamine component (g) Acid dianhydride component whitening (%) inductive (° C.) Example 14 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (22.0 g) (0.06 mol; 159 3,3′,4,4′-diphenylethertetracarboxylic dianhydride (31.0 g) Not 1.2 3 190 manufactured by AZ Electronic Materials Co., Ltd.) (0.1 mol; manufactured by MANAC Inc.) observed bis(3-amino-4-hydroxyphenyl) fluorene (15.2 g) (0.04 mol; manufactured by AZ Electronic Materials Co., Ltd.) Example 15 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (36.6 g) (0.1 mol; 158 3,3′,4,4′-diphenylethertetracarboxylic dianhydride (31.0 g) Not 0.8 2.9 170 manufactured by AZ Electronic Materials Co., Ltd.) (0.1 mol; manufactured by MANAC Inc.) observed Example 16 bis(3-amino-4-hydroxyphenyl)fluorene (22.8 g) (0.06 mol; 136 3,3′,4,4′-diphenylethertetracarboxylic dianhydride (29.5 g) Not 1.5 3.2 200 manufactured by AZ Electonic Materials Co., Ltd.) (0.095 mol; manufactured by MANAC Inc.) observed 2,4-diaminotoluene (4.88 g) (0.04 mol; manufactured by Tokyo Pyromellitic dianhydride (1.09 g) (0.005 mol; Chemical Industry Co., Ltd.) manufactured by Daicel Chemical Industries, Ltd.) Example 17 bis(3-amino-4-hydroxyphenyl)fluorene (22.8 g) (0.06 mol; 126 3,3′,4,4′-diphenylethertetracarboxylic dianhydride (15.5 g) Not 1.5 3.3 210 manufactured by AZ Electronic Materials Co., Ltd.) (0.05 mol; manufactured by MANAC Inc.) observed 2,4-diaminotoluene (4.88 g) (0.04 mol; manufactured by Tokyo Pyromellitic dianhydride (10.9 g) (0.05 mol; manufactured Chemical Industry Co., Ltd.) by Daicel Chemical Industries, Ltd.) Example 18 bis(3-amino-4-hydroxyphenyl)fluorene (22.8 g) (0.06 mol; 115 Pyromellitic dianhydride (21.8 g) (0.1 mol; manufactured Not 3.2 3.3 220 manufactured by AZ Electronic Materials Co., Ltd.) by Daicel Chemical Industries, Ltd.) observed 2,4-diaminotoluene (4.88 g) (0.04 mol; manufactured by Tokyo Chemical Industry Co., Ltd.) Example 19 bis(3-amino-4-hydroxyphenyl)fluorene (22.8 g) (0.06 mol; 138 3,3′,4,4′-diphenylethertetracarboxylic dianhydride (21.7 g) Not 3.3 3.3 200 manufactured by AZ Electronic Materials Co., Ltd.) (0.07 mol; manufactured by MANAC Inc.) observed 2,4-diaminotoluene (4.88 g) (0.04 mol; manufactured by Tokyo 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (9.67 g) Chemical Industry Co., Ltd.) (0.03 mol; manufactured by Daicel Chemical Industries, Ltd.) Example 20 bis(3-amino-4-hydroxyphenyl)fluorene (22.8 g) (0.06 mol; 138 3,3′,4,4′-diphenylethertetracarboxylic dianhydride (18.6 g) Not 1.4 3.3 200 manufactured by AZ Electronic Materials Co., Ltd.) (0.06 mol; manufactured by MANAC Inc.) observed 2,4-diaminotoluene (4.88 g) (0.04 mol; manufactured by Tokyo 3,3′,4,4′-benzophenonetetracarboxylic anhydride (12.9 g) Chemical Industry Co., Ltd.) (0.04 mol; manufactured by Daicel Chemical Industries, Ltd.) Example 21 bis(3-amino-4-hydroxyphenyl)fluorene (22.8 g) (0.06 mol; 140 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (32.2 g) Not 1.5 3.3 210 manufactured by AZ Electronic Materials Co., Ltd.) (0.1 mol; manufactured by Daicel Chemical Industries, observed 2,4-diaminotoluene (4.88 g) (0.04 mol; manufactured by Tokyo Ltd.) Chemical Industry Co., Ltd.) Example 22 3,3′-diaminodiphenyl sulfone (14.9 g) (0.06 mol; manufactured by 130 3,3′,4,4′-diphenylethertetracarboxylic dianhydride (15.5 g) Not 1.5 3.4 210 Wakayama Seika Kogyo Co., Ltd.) (0.05 mol; manufactured by MANAC Inc.) observed 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (14.6 g) (0.04 mol; Pyromellitic dianhydride (10.9 g) (0.05 mol; manufactured manufactured by AZ Electronic Materials Co., Ltd.) by Daicel Chemical Industries, Ltd.) Example 23 3,3′-diaminodiphenyl sulfone (19.9 g) (0.08 mol; manufactured by 137 3,3′,4,4′-diphenylethertetracarboxylic dianhydride (15.5 g) Not 1.5 3.4 210 Wakayama Seika Kogyo Co., Ltd.) (0.05 mol; manufactured by MANAC Inc.) observed 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (7.32 g) (0.02 mol; 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (16.1 g) manufactured by AZ Electronic Materials Co., Ltd.) (0.05 mol; manufactured by Daicel Chemical Industries, Ltd.) Example 24 3,3′-diaminodiphenyl sulfone (14.9 g) (0.06 mol; manufactured by 132 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (16.1 g) Not 1.5 3.5 200 Wakayama Seika Kogyo Co., Ltd.) (0.05 mol; manufactured by Daicel Chemical Industries, observed 2,2-bis(3-amino-4-hyroxyphenyl)hexafluoropropane (14.6 g) (0.04 mol; Ltd.) manufactured by AZ Electronic Materials Co., Ltd.) Pyromellitic dianhydride (10.9 g) (0.05 mol; manufactured by Daicel chemical Industries, Ltd.) Example 25 3,3′-diaminodiphenyl sulfone (19.9 g) (0.08 mol; manufactured by 127 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (16.1 g) Not 1.5 3.5 210 Wakayama Seika Kogyo Co., Ltd.) (0.05 mol; manufactured by Daicel Chemical Industries, observed 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (7.32 g) (0.02 mol; Ltd.) manufactured by AZ Electronic Materials) Pyromellitic dianhydride (10.9 g) (0.05 mol; manufactured by Daicel Chemical Industries, Ltd.) Comparative 4,4′-diaminodiphenyl ether (10.0 g) (0.05 mol; manufactured by 164 2,2-bis(hexafluoroisopropylidene) phthalic anhydride Observed 1 2.6 170 Example 1 Wakayama Seika Kogyo Co., Ltd.) (44.4 g) (0.1 mol; manufactured by Daikin Industries, 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (16.0 g) (0.05 mol; Ltd.) manufactured by Wakayama Seika Kogyo Co., Ltd.) Comparative 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (32.0 g) (0.1 mol; 147 3,3′,4,4′-diphenylethertetracarboxylic dianhydride (31.0 g) Observed 1 2.7 190 Example 3 manufactured by Wakayama Seika Kogyo Co., Ltd.) (0.1 mol; manufactured by MANAC Inc.)

TABLE-US-00003 TABLE 3 Examples of Formation of Fiber corresponding nonwoven diameter polyimide solution cloth (μm) Example 7 Example 1 Good 6 Example 26 Example 2 Good 3.6 Example 27 Example 3 Good 4 Example 28 Example 4 Good 4 Example 29 Example 5 Good 4 Example 30 Example 6 Good 4 Example 31 Example 8 Good 3.2 Example 32 Example 9 Good 2.8 Example 33 Example 10 Good 2.8 Example 34 Example 11 Good 3.2 Example 35 Example 12 Good 3 Example 36 Example 13 Good 3 Example 37 Example 14 Good 5 Example 38 Example 15 Good 6 Example 39 Example 16 Good 2.6 Example 40 Example 17 Good 2.6 Example 41 Example 18 Good 3.6 Example 42 Example 19 Good 3.2 Example 43 Example 20 Good 2 Example 44 Example 21 Good 2 Example 45 Example 22 Good 1.4 Example 46 Example 23 Good 1.4 Example 47 Example 24 Good 1 Example 48 Example 25 Good 1 Comparative Comparative Bad — Example 2 Example 1 (whitening) Comparative Comparative Bad — Example 4 Example 3 (whitening)