JP3451795B2 - Aromatic polyimide, semipermeable membrane and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aromatic polyimide, a semipermeable membrane and a method for producing the same. More specifically, the present invention is
The present invention relates to an aromatic polyimide having a sulfonic acid group in a polyimide skeleton, an aromatic polyimide semipermeable membrane, a method for producing the aromatic polyimide, and a method for producing the aromatic polyimide semipermeable membrane.

[0002]

2. Description of the Related Art Aromatic polyimides are, for example, films,
It is used industrially in large quantities as a sheet, a molded product, a hollow fiber, a varnish, etc. in the fields of electronic materials, electrical insulation, gas separation, medical fields and the like. Aromatic polyimides are generally polycondensed in an organic solvent in an approximately equimolar amount of an aromatic tetracarboxylic dianhydride such as pyromellitic dianhydride and an aromatic diamine such as diaminodiphenyl ether into a polyamic acid, and then It has been prepared by imidizing a polyamic acid with heating or in an acid anhydride such as acetic anhydride.

Recently, a polyimide having a polyimide skeleton having a sulfonic acid group, an alkali sulfonate group, an ammonium sulfonate group, etc. has been proposed. For example, in Japanese Unexamined Patent Publication No. 6-87957, an aromatic tetracarboxylic acid, an aromatic diamine having an ammonium sulfonate group, and an aromatic diamine having no ammonium sulfonate group are described as N-methylpyrrolidone. Polycondensation to polyamic acid in various organic solvents, and then imidization (chemical imidization) in triethylamine and acid anhydride 2
A copolyimide produced by a step polymerization method and a production method thereof are disclosed. The publication describes only a copolyimide having an aromatic diamine residue having an ammonium sulfonate group as a copolymerization component, and does not disclose any homopolyimide. Further, there is no disclosure about the one-step polymerization method. Further, although there is a description including an extremely wide range of tetracarboxylic acids as a general formula of aromatic tetracarboxylic acid, there is no specific description about biphenyltetracarboxylic dianhydride.

Japanese Unexamined Patent Publication (Kokai) No. 5-192552 discloses an aromatic polyimide gas separation membrane composed of an aromatic tetracarboxylic acid and a copolyimide having bisphenylfluorenediamine having a sulfonic acid group as a diamine as a copolymerization component. ing. In the examples of the publication, N is used as a solvent.
Disclosed is a homogeneous membrane using benzyl methylpyrrolidone, and using benzophenonetetracarboxylic acid and bisphenylfluorenediamine having a sulfonic acid group as a diamine as a copolymerization component. JP-A-63-283704
JP-A-63-283707 discloses a copolyimide containing pyromellitic dianhydride as an aromatic tetracarboxylic acid and diaminobenzenesulfonic acid having a sulfonic acid alkali metal base as a diamine as a copolymerization component. Homogeneous membranes such as selective permeation membranes and amphoteric polyelectrolyte separation membranes are disclosed. Japanese Unexamined Patent Publication (Kokai) No. 58-153541 discloses an ion exchange membrane of a polyimide comprising an aliphatic dianhydride and a diamine having a sulfonic acid group or an alkali sulfonate group.

By introducing a highly polar sulfonic acid group, an alkali metal sulfonate group, an ammonium sulfonate group or the like into the polyimide skeleton, gas permeability, selectivity, etc. are improved. Further, in order to practically use polyimide as a gas separation membrane which is practically efficient, it is most desirable to use it as an asymmetric hollow fiber membrane. However, polyimides having these groups, which have been conventionally disclosed and proposed, do not have sufficient spinnability and film-forming properties and cannot be formed into hollow fiber membranes, or a technique for forming hollow fiber membranes has not been established, or hollow fiber membranes have not been established. Even if it could be realized, the mechanical strength of the film was inferior.

[0006]

DISCLOSURE OF THE INVENTION The present invention has a fragrance which is excellent in gas permeability and selectivity, and is capable of easily forming a high-strength asymmetric hollow fiber membrane, and is excellent in spinnability and film-forming property. It is intended to provide a group polyimide and an aromatic polyimide semipermeable membrane. Further, the present invention has a sulfonic acid group in the main chain skeleton, which is excellent in gas permeability and selectivity, and can easily form a high-strength asymmetric hollow fiber membrane, and is excellent in spinnability and film-forming property. An object of the present invention is to provide a method for producing an aromatic polyimide and a method for producing an aromatic polyimide semipermeable membrane.

The inventors of the present invention have been particularly interested in aromatic polyimides having a sulfonic acid group, an alkali metal sulfonate group, an ammonium sulfonate group, etc. I researched earnestly. As a result, are biphenyltetracarboxylic acid compounds, such as biphenyltetracarboxylic dianhydride, and aromatic diamine having a sulfonic acid group, cannot be polymerized or imidized in a phenol solvent or an amide solvent? , Or an aromatic polyimide of biphenyltetracarboxylic acid and an aromatic diamine having a sulfonic acid group is insoluble in a phenolic solvent or an amide solvent, and thus a semipermeable membrane such as a hollow fiber membrane is obtained by a conventional method. Inability to do, biphenyltetracarboxylic acid compound, for example, biphenyltetracarboxylic dianhydride, and aromatic diamine having a sulfonic acid ammonium group are reacted in a phenolic solvent to polymerize in a single step,
An aromatic polyimide having an ammonium sulfonate group is imidized to obtain an aromatic polyimide having a sulfonic acid group in the main chain skeleton easily by acid treatment of the aromatic polyimide having an ammonium sulfonate group, When an aromatic polyimide having an ammonium sulfonate group is subjected to an acid treatment with a semi-permeable membrane, an aromatic polyimide semi-permeable membrane in which the ammonium sulfonate group is converted into a sulfonic acid group is obtained, and a biphenyl tetracarboxylic acid in a phenol solvent is used. The present inventors have found that the above object can be achieved by a method of polymerizing and imidizing a dianhydride and an aromatic diamine having an ammonium sulfonate group, and arrived at the present invention.

[0008]

[Means for Solving the Problems]

In the present invention, the repeating unit is represented by the general formula (1),

[0010]

[Chemical 19] And an aromatic polyimide represented by

However, Ar in the general formula (1) is an aromatic diamine residue represented by the following general formulas (2) and (3), and at least one of R _{1 to} R ₄ in the general formula (2) is One is SO
₃ H group, other than hydrogen atom or an alkyl group having 1 to 3 carbon atoms, at least one of R _{1 to} R _{8 in} the general formula (3) is a —SO ₃ H group, and the others are hydrogen atoms. Or an alkyl group having 1 to 3 carbon atoms, X is a direct bond, —O
Shown over, over SO ₂ over, over NH chromatography, alkylene group having 1 to 3 carbon atoms, an alkylidene group or an alkenylene group.

[0012]

[Chemical 20]

[0013]

[Chemical 21]

In the present invention, the repeating unit is represented by the general formula (1),

[0015]

[Chemical formula 22]

The present invention relates to an aromatic polyimide semipermeable membrane represented by

However, Ar in the general formula (1) is an aromatic diamine residue represented by the following general formulas (2) and (3), and at least one of R _{1 to} R ₄ in the general formula (2) is One is SO
₃ H group, other than hydrogen atom or an alkyl group having 1 to 3 carbon atoms, at least one of R _{1 to} R _{8 in} the general formula (3) is a —SO ₃ H group, and the others are hydrogen atoms. Or an alkyl group having 1 to 3 carbon atoms, X is a direct bond, —O
Shown over, over SO ₂ over, over NH chromatography, alkylene group having 1 to 3 carbon atoms, an alkylidene group or an alkenylene group.

[0018]

[Chemical formula 23]

[0019]

[Chemical formula 24]

In the present invention, the repeating unit has the general formula (4),

[0021]

[Chemical 25]

The present invention relates to a process for producing an aromatic polyimide represented by the general formula (1), which comprises subjecting the aromatic polyimide represented by

However, Ar 'in the general formula (4) is an aromatic diamine residue represented by the following general formulas (5) and (6), and at least R _{1 to} R ₄ in the general formula (5) is represented. One is -S
O ₃ N (L) ₄ group [L is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms] and the other is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ₁ in the general formula (6) At least one of R ₈ to R ₈ is a —SO ₃ N (L) ₄ group [L is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms] and the other is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; , X is a direct bond,
Shown over O over, over SO ₂ over, over NH chromatography, alkylene group having 1 to 3 carbon atoms, an alkylidene group or an alkenylene group.

[0024]

[Chemical formula 26]

[0025]

[Chemical 27]

The present invention relates to a biphenyltetracarboxylic acid compound and the compounds represented by the general formulas (7) and (8)

[0027]

[Chemical 28]

[0028]

[Chemical 29]

Approximately equimolar amount of the aromatic diamine compound shown in (1) is polymerized and imidized in a phenolic solvent to give a repeating unit of the general formula (4),

[0030]

[Chemical 30]

An aromatic polyimide represented by the following formula is obtained, and the polyimide is treated with an acid to obtain —SO ₃ N (L) _{4 of the} polyimide.
The present invention relates to a method for producing an aromatic polyimide represented by the general formula (1), which is characterized by converting a group to a —SO ₃ H group.

However, at least one of R _{1 to} R _{4 in} the general formula (7) is a —SO ₃ N (L) ₄ group [L is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms], and Represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and at least one of R _{1 to} R _{8 in} the general formula (8) is —SO ₃ N (L) ₄
A group [L is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms],
Others represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, X represents a direct bond, —O—, —SO ₂ —, —NH—, an alkylene group having 1 to 3 carbon atoms, an alkylidene group or an alkenylene group. Ar 'in the general formula (4) represents an aromatic diamine residue represented by the general formulas (7) and (8).

In the present invention, the repeating unit is represented by the general formula (4),

[0034]

[Chemical 31]

The present invention relates to a method for producing an aromatic polyimide semipermeable membrane represented by the general formula (1), which comprises subjecting an aromatic polyimide semipermeable membrane represented by

However, Ar 'in the general formula (4) is an aromatic diamine residue represented by the following general formulas (5) and (6), and at least R _{1 to} R ₄ in the general formula (5) are represented. One is -S
O ₃ N (L) ₄ group [L is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms] and the other is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ₁ in the general formula (6) At least one of R ₈ to R ₈ is a —SO ₃ N (L) ₄ group [L is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms] and the other is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; , X is a direct bond,
Shown over O over, over SO ₂ over, over NH chromatography, alkylene group having 1 to 3 carbon atoms, an alkylidene group or an alkenylene group.

[0037]

[Chemical 32]

[0038]

[Chemical 33]

The present invention relates to a biphenyltetracarboxylic acid compound and the compounds represented by the general formulas (7) and (8)

[0040]

[Chemical 34]

[0041]

[Chemical 35]

Approximately equimolar amounts of the aromatic diamine compound shown in (1) are polymerized and imidized in a phenolic solvent to give a repeating unit of the general formula (4),

[0043]

[Chemical 36]

An aromatic polyimide semipermeable membrane represented by
The aromatic compound represented by the general formula (1), wherein the polyimide semipermeable membrane is treated with an acid to convert the -SO ₃ N (L) ₄ group of the polyimide semipermeable membrane into an -SO ₃ H group. The present invention relates to a method for manufacturing a polyimide semipermeable membrane.

However, at least one of R _{1 to} R _{4 in} the general formula (7) is a —SO ₃ N (L) ₄ group [L is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms], and Represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and at least one of R _{1 to} R _{8 in} the general formula (8) is —SO ₃ N (L) ₄
A group [L is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms],
Others represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, X represents a direct bond, —O—, —SO ₂ —, —NH—, an alkylene group having 1 to 3 carbon atoms, an alkylidene group or an alkenylene group. Ar 'in the general formula (4) represents an aromatic diamine residue represented by the general formulas (7) and (8).

In the present invention, the aromatic polyimide represented by the general formula (1) is a biphenyltetracarboxylic acid compound and an aromatic diamine compound having an ammonium sulfonate group represented by the general formulas (7) and (8). By polymerizing and imidizing approximately equimolar amounts of and in a phenolic solvent, an aromatic polyimide having an ammonium sulfonate group is obtained, which is obtained by acid treatment. But,
When using benzophenonetetracarboxylic acid or pyromellitic dianhydride instead of the biphenyltetracarboxylic acid compound, even one-step polymerization in a phenolic solvent using an aromatic diamine having an ammonium sulfonate group,
It cannot be imidized, or even if it can be polymerized and imidized, the spinnability and film-forming properties are insufficient and it is difficult to obtain a high-strength asymmetric hollow fiber membrane. Further, even when using a biphenyl tetracarboxylic acid compound, instead of the aromatic diamine compound having an ammonium sulfonate group,
Even when a diamine having a sulfonic acid group (-SO ₃ H) or an alkali metal sulfonate is used, it cannot be polymerized and imidized in a single step in a phenolic solvent or is insoluble in a phenolic solvent. It is difficult to obtain a high strength asymmetric hollow fiber membrane due to insufficient spinnability and film forming property.

In the present invention, the biphenyltetracarboxylic acid compound includes 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride and 2,3,3', 4'-biphenyltetracarboxylic dianhydride. And the like, and these biphenyltetracarboxylic acids and their esters can also be used.

As the aromatic diamine compound having an ammonium sulfonate group represented by the general formulas (7) and (8), 2,5-diaminobenzenesulfonic acid ammonium salt, 2,5-diaminobenzenesulfonic acid trimethylammonium salt, 2, Triethylammonium 5-diaminobenzenesulfonate, Tributylammonium 2,5-diaminobenzenesulfonate, Triamylammonium 2,5-diaminobenzenesulfonate, Ammonium 2,4-diaminobenzenesulfonate, 2,4-Diaminobenzenesulfonate Trimethylammonium, triethylammonium 2,4-diaminobenzenesulfonate,
Tributylammonium 2,4-diaminobenzenesulfonate, Triamylammonium 2,4-diaminobenzenesulfonate, Ammonium 2,4-diaminobenzene-1,5-disulfonate, Trimethylammonium 2,4-diaminobenzene-1,5-disulfonate Ammonium, 2,
Triethylammonium 4-diaminobenzene-1,5-disulfonate, Tributylammonium 2,4-diaminobenzene-1,5-disulfonate, Triamylammonium 2,4-diaminobenzene-1,5-disulfonate, 3,3′-dimethyl-4 , 4'-Diaminobiphenyl-5-sulphonic acid ammonium, 3,3'-dimethyl-4,4'-diaminobiphenyl-5-sulphonic acid trimethylammonium, 3,3'-dimethyl-4,4 '
-Diaminobiphenyl-5-triethylammonium sulfonate, 3,3'-dimethyl-4,4'-diaminobiphenyl-5-tributylammonium sulfonate,
3,3'-Dimethyl-4,4'-diaminobiphenyl-5-triamyl ammonium sulfonate, 3,3'-Dimethyl-4,4'-diaminobiphenyl-6,6'-ammonium disulfonate, 3,3'-dimethyl-4,3
4'-diaminobiphenyl-6,6'-trimethylammonium disulfonate, 3,3'-dimethyl-4,4 '
-Diaminobiphenyl-6,6'-triethylammonium disulfonate, 3,3'-dimethyl-4,4'-diaminobiphenyl-6,6'-tributylammonium disulfonate, 3,3'-dimethyl-4,4'-diaminobiphenyl-6 6'-triammonium disulfonate, benzidine-2,2'-ammonium disulfonate, benzidine-2,2'-trimethylammonium disulfonate, benzidine-2,2'-triethylammonium disulfonate, tributylammonium benzidine-2,2'-disulfonate, benzidine-2,2
2'-triammonium disulfonate, 4,4 '
-Diaminodiphenyl ether-2-ammonium sulfonate, 4,4'-diaminodiphenyl ether-2-trimethylammonium sulfonate, 4,4'-diaminodiphenyl ether-2-triethylammonium sulfonate, 4,4'-diaminodiphenyl ether-2
-Tributylammonium sulfonate, 4,4'-diaminodiphenyl ether-2-triamyl ammonium sulfonate, 4,4'-diaminodiphenyl ether-3-ammonium sulfonate, 4,4'-diaminodiphenyl ether-3-trimethylammonium sulfonate, 4,4 '-Diaminodiphenyl ether-3-sulfonic acid triethylammonium, 4,4'-diaminodiphenyl ether-3-sulfonic acid tributylammonium, 4,4'-diaminodiphenyl ether-3-sulfonic acid triamyl ammonium, 4,4'-diaminodiphenyl ether-2, 2'-ammonium disulfonate, 4,4'-diaminodiphenyl ether-2,
2'-Trimethylammonium disulfonate, 4,4 '
-Diaminodiphenyl ether-2,2'-disulfonic acid triethylammonium, 4,4'-diaminodiphenyl ether-2,2'-disulfonic acid tributylammonium, 4,4'-diaminodiphenyl ether-2,2'-disulfonic acid triamylammonium, 4,
Ammonium 4'-diaminodiphenylsulfone-3-sulfonate, trimethylammonium 4,4'-diaminodiphenylsulfone-3-sulfonate, triethylammonium 4,4'-diaminodiphenylsulfone-3-sulfonate, 4,4'-diaminodiphenylsulfone Tributylammonium sulfonate, 4,4'-diaminodiphenylsulfone-3-triammonium sulfonate, 4,4'-diaminodiphenylsulfone 3,3'-ammonium disulfonate, 4,4'-diaminodiphenylsulfone-3 , 3'-disulfonic acid trimethylammonium, 4,4'-diaminodiphenylsulfone 3,3'-disulfonic acid triethylammonium, 4,4'-diaminodiphenylsulfone 3,
3'-Tributylammonium disulfonate, 4,4 '
-Diaminodiphenyl sulfone-3,3'-triammonium disulfonate, 4,4'-diaminodiphenylmethane-2,2'-ammonium disulfonate,
Trimethylammonium 4,4'-diaminodiphenylmethane-2,2'-disulfonate, Triethylammonium 4,4'-diaminodiphenylmethane-2,2'-disulfonate, Tributylammonium 4,4'-diaminodiphenylmethane-2,2'-disulfonate , 4,
4'-diaminodiphenylmethane-2,2'-triammonium ammonium disulfonate, 4,4'-diaminodiphenylmethane-3,3'-ammonium disulfonate,
Trimethylammonium 4,4'-diaminodiphenylmethane-3,3'-disulfonate, Triethylammonium 4,4'-diaminodiphenylmethane-3,3'-disulfonate, Tributylammonium 4,4'-diaminodiphenylmethane-3,3'-disulfonate , 4,
4'-diaminodiphenylmethane-3,3'-triammonium disulfonate, 4,4'-diaminodiphenylamine-2-ammonium sulfonate, 4,4 '
-Trimethylammonium diaminodiphenylamine-2-sulfonate, 4,4'-diaminodiphenylamine-2-triethylammonium sulfonate, 4,4'-diaminodiphenylamine-2-tributylammonium sulfonate, 4,4'-diaminodiphenylamine-2-triasulfonate Milammonium, 4,4'-diaminostilbene-2,2'-disulfonic acid ammonium, 4,4'-diaminostilbene-2,2'-disulfonic acid trimethylammonium, 4,4'-diaminostilbene-2,2'-disulfonic acid Examples thereof include triethylammonium, 4,4'-diaminostilbene-2,2'-disulfonic acid tributylammonium, and 4,4'-diaminostilbene-2,2'-disulfonic acid triamylammonium.

In the present invention, the phenolic solvent has a melting point of about 100 ° C. or lower, preferably 80 ° C. or lower, and a boiling point at atmospheric pressure of 300 ° C. or lower, preferably 280.
A material having a temperature of ° C or less is suitable because it does not cause problems in handling the polymerization solution such as freezing of the solvent in the polymerization solution. Specifically, a hydrogen atom in a benzene nucleus of a monovalent phenol such as phenol, o-, m- or p-cresol, 3,5-xylenol, carvacrol, and thymol, or catechol, or a monovalent phenol is replaced with a halogen atom. Preferred are halogenated phenols. These solvents may be a mixture. Examples of halogenated phenols include 3-chlorophenol, 4-chlorophenol, 3-bromophenol, 4-bromophenol, 2--4-bromophenol, 2-chlorofluoro-4-hydroxytoluene, 2-chlorofluoro-5-hydroxytoluene, 3-chlorofluorocarbon. 6-hydroxytoluene, 4-chloro 2-hydroxytoluene, 2-brom 4-hydroxytoluene, 2
-Bromo 5-hydroxytoluene, 3-Bromo 6-hydroxytoluene, 4-Bromou 2-hydroxytoluene and the like can be mentioned. Among the halogenated phenols, 4-chlorophenol is particularly preferable.

In the present invention, for the polymerization and imidization in a phenolic solvent, generally, approximately equimolar amounts of a biphenyltetracarboxylic acid compound and an aromatic diamine compound having an ammonium sulfonate group are dissolved in a phenolic solvent. , 100-250 ° C, preferably 130-200 °
It is preferable to carry out the reaction by heating to the reaction temperature of C and removing the produced water, since a practically sufficient polymerization rate can be obtained and evaporation / desorption of the solvent from the polymerization system can be suppressed. Is. The reaction may be carried out batchwise or continuously.

The polycondensation reaction and the imidization reaction proceed at the reaction temperature, and a solution of a polyimide having ammonium sulfonate groups dissolved in a phenolic solvent is obtained in one step. The reaction time is about 10 to 60 hours. that time,
The amount of the biphenyltetracarboxylic acid compound and the aromatic diamine compound having an ammonium sulfonate group with respect to the solvent used is such that the amount (concentration) of the polyimide in the solvent is 5 to 50.
%, Particularly when the polymerization liquid is directly used for the production of a semipermeable membrane such as a hollow fiber membrane, the concentration is 10 to 40% by weight, and further 12
It is preferable that the polymerization liquid has a rotational viscosity (measured at 100 ° C.) of 25 to 8,000 poises, particularly 100 to 3,000 poises. If the rotational viscosity is too high or too low, spinnability and film-forming properties will suffer.

In the present invention, the aromatic polyimide having a sulfonic acid group can be obtained by removing a phenolic solvent from a polyimide solution having an ammonium sulfonate group by heating, evaporation or the like, and then treating with an acid.
The ammonium sulfonate group is converted to a sulfonate group by the acid treatment. The semipermeable membrane is a semipermeable membrane of a polyimide having an ammonium sulfonate group formed by a method such as a dry method, a wet method or a dry-wet method from a solution of a polyimide having an ammonium sulfonate group obtained by polymerization / imidization. Can be obtained by subjecting it to an acid treatment. In particular, a dry-wet method in which a solution of a polyimide having an ammonium sulfonate group is cast or discharged from a molding machine into the air or extruded, then introduced into a coagulating liquid to coagulate, and the adhered coagulating liquid is washed and dried is The acid treatment in the step is preferable because a semipermeable membrane having a sulfonic acid group having good permeability and selectivity can be obtained.

The coagulating liquid used in the wet method or the dry-wet method for obtaining the semipermeable membrane of polyimide having an ammonium sulfonate group is, for example, water, methanol, ethanol, or the like.
Alcoholic solvents such as propanol and isopropanol, acetone, methyl ethyl ketone, diethyl ketone,
A polar solvent that does not dissolve the polyimide and is compatible with the solvent of the polyimide solution, such as a ketone solvent such as ethyl propyl ketone, a mixed solvent of these water, an alcohol solvent, a ketone solvent, or the like is used. Among them, a mixed solvent of water, particularly a mixed solvent of water and an alcoholic solvent, for example, a mixed solvent of water and ethanol forms a defect-free, permeable, highly selective asymmetric semipermeable membrane. It is possible and preferable.

The coagulated polyimide semi-permeable membrane having ammonium sulfonate groups is washed with an alcohol solvent such as methanol, ethanol, propanol or isopropanol, and then an inert solvent such as isopentane, n-hexane or isooctane. , Washed with an aliphatic hydrocarbon solvent such as n-heptane, dried, further acid-treated after heat treatment, acid-treated in a wet state without being dried or heat-treated, or unwashed You may perform acid treatment.

In the present invention, the acid treatment of the polyimide semipermeable membrane having an ammonium sulfonate group is carried out by bringing the semipermeable membrane into contact with an acidic solution. The method of contacting with the acidic solution is not particularly limited, but a method of immersing the semipermeable membrane in the acidic solution is suitably adopted. The immersion treatment time for converting the ammonium sulfonate group into the sulfonate group is 1 second to 100 hours, preferably 1 minute to 10 hours. The acidic solution used for the acid treatment may be a solution of an inorganic acid or a solution of an organic acid. Suitable inorganic acids include, for example, mineral acids such as hydrochloric acid, sulfuric acid and nitric acid, and suitable organic acids include saturated fatty acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid and caproic acid. Can be mentioned. Inorganic or organic acids other than these mineral acids and saturated fatty acids can be used as long as they can convert ammonium sulfonate groups into sulfonic acid groups. The acidic solution is usually used as an aqueous solution or a solution of an organic solvent such as alcohol, ketone or hydrocarbon, or a mixed solution thereof, and the concentration thereof is 0.001 to 50 mol / liter, particularly 0.01 to 10 mol. Mols / liter are preferred. Further, the immersion temperature is conveniently around room temperature and suitable.

The semipermeable membrane having a sulfonic acid group obtained by the acid treatment is washed with an alcohol solvent such as methanol, ethanol, propanol or isopropanol, and then an inert solvent such as isopentane, n-hexane, isooctane, After washing with an aliphatic hydrocarbon solvent such as n-heptane, drying and further heat treatment if necessary. The heat treatment temperature is preferably lower than the softening point or the second-order transition point of the semipermeable membrane having a sulfonic acid group, because it does not destroy the asymmetric structure of the asymmetric semipermeable membrane, and usually 90 to 400. The temperature is appropriately selected from the temperature of ° C.

In the present invention, the shape of the semipermeable membrane having a sulfonic acid group may be any shape such as a film / sheet flat membrane and a hollow fiber hollow fiber membrane, but it is an effective membrane as a separation membrane. Hollow fiber membranes having a large area are preferable.
As a method for producing a hollow fiber membrane, for example, Japanese Patent Publication No. 61-352.
No. 82, Japanese Patent Publication No. 1-48044 (USP. 4)
460526), Japanese Patent Publication No. 6-93988, and the like. Next, one example of a preferred method for producing a hollow fiber membrane in the present invention will be described, but the present invention is not limited to this example.

A solution of a polyimide having an ammonium sulfonate group polymerized and imidized in a phenolic solvent was used as a dope solution and extruded into the air from a hollow fiber spinning nozzle to form a hollow fiber shaped article. The molded product is introduced into a coagulating liquid to coagulate, and the product is washed with an alcohol-based solvent and an aliphatic hydrocarbon-based solvent to form a polyimide hollow fiber membrane having an ammonium sulfonate group, and then subjected to an acid treatment to form an asymmetric sulfonic acid group. A hollow fiber membrane having is obtained.

More specifically, a solution of a polyimide having an ammonium sulfonate group polymerized and imidized in a phenolic solvent is used as a dope solution, and the spinning nozzle discharge temperature is 60 to 150 ° from a hollow fiber spinning nozzle. The rotational viscosity at C, preferably 70 to 120 ° C, is 10 to 100.
After the dope liquid of 00 poise, especially 100 to 6000 poise, is extruded into the air to form a hollow fiber shaped article, the article is held at -10 to + 60 ° C, preferably -5 to + 40 ° C. In the coagulating liquid, preferably, the coagulating liquid is introduced into an alcohol-based solvent or a mixed solvent of water and an alcohol-based solvent to coagulate, and washed with an alcohol-based solvent and / or an aliphatic hydrocarbon-based solvent and ammonium sulfonate. After forming a polyimide hollow fiber membrane having a group, the concentration of mineral acid, saturated fatty acid, etc. is 0.001 to 50 mol /
1 second to 100 hours, preferably 1 minute to 10 hours in an acid solution of liter, preferably 0.01 to 10 mol / liter
After immersion for a time, the ammonium sulfonate groups of the polyimide are converted into sulfonic acid groups, but it is not necessary to convert all the ammonium sulfonate groups of the polyimide forming the hollow fiber membrane into sulfonic acid groups. Adjusting the concentration and soaking time of the acidic solution to convert only the ammonium sulfonate groups of the polyimide that forms part of the hollow fibers, especially the outer surface of the hollow fiber membrane, which is the gas selective separation layer, to sulfonic acid groups. Is also possible. After converting the ammonium sulfonate group of the polyimide into a sulfonate group, the polyimide is washed with an alcohol solvent and / or an aliphatic hydrocarbon solvent, and the washing solvent is 50 to 150 °.
A hollow fiber membrane having an asymmetric sulfonic acid group, which is suitable as a separation membrane, can be obtained by evaporating and drying at a temperature of C, and further by heat treatment after drying.

This hollow fiber membrane has high strength, and is extremely excellent in selectivity and permeability, and can be suitably used as a separation membrane. In particular, the gas separation membrane is suitable for separation of mixed gas, for example, separation of oxygen-nitrogen, separation of helium-nitrogen, separation of hydrogen, separation of carbon dioxide gas and the like.

[0061]

EFFECTS OF THE INVENTION According to the present invention, there are provided an aromatic polyimide having a sulfonic acid group and a semipermeable membrane having an aromatic polyimide having excellent spinnability, film-forming property, gas permeability and high selectivity. can do. Further, according to the present invention, it is possible to carry out polymerization and imidization of an aromatic polyimide having an ammonium sulfonate group, which is excellent in spinnability and film-forming property, in a single step. And an asymmetric hollow fiber membrane having a high-strength sulfonic acid group excellent in gas permeability and selectivity can be easily produced.

[0062]

EXAMPLES In each example, the permeation performance of the hollow fiber membrane is
Thread film, stainless steel pipe and epoxy resin
Create a hollow fiber membrane bundle for permeation performance evaluation using adhesive
Then store it in a stainless steel container and
Made The effective membrane area of the hollow fiber membrane bundle is about 5 cm²And
It was. He / O for modules₂/ N₂= 30/30 /
40 mixed gas is introduced to separate the hollow fiber membrane from outside and inside.
Differential pressure is 10 kg / cm²The introduced gas in the hollow fiber membrane.
It was brought into contact with the outer surface and permeated inside the hollow fiber membrane. each
The permeation rate (P ') of the gas is
It was calculated from the measured values of gas chromatography analysis. Measurement
The constant temperature was 50 ° C. The unit of transmission rate (P ') is
Ncc / (cm²-Sec. -CmHg).

Example 1 99 mmol of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) and triethylammonium 2,4-diaminobenzenesulfonate (mDABS)
-Et ₃ N) 100 mmol and 195 g of 4-chlorophenol were placed in a separable flask equipped with a stirrer and a nitrogen gas introducing tube, and the mixture was stirred at 160 ° C.
Polymerization at 45 ° C. for 45 hours and imidization reaction were carried out to prepare a solution of an aromatic polyimide having a concentration of 23% by weight of triethylammonium sulfonate group dissolved in 4-chlorophenol.

The aromatic polyimide solution having a triethylammonium sulfonate group was filtered through a 400-mesh stainless steel wire net to prepare a dope for spinning. The dope liquid for spinning was prepared by using this as a hollow fiber spinning nozzle (outer diameter of circular opening: 1000 μm, slit width of circular opening: 200 μm, outer diameter of core opening: 400).
A hollow fiber spinning nozzle is charged into the air through a hollow fiber spinning nozzle, and then the hollow fiber shaped article is passed through a dry nitrogen gas atmosphere. Immerse in the primary coagulation liquid of C, and
Temperature in secondary coagulator equipped with a pair of guide rolls 0 ° C
The secondary coagulation liquid is reciprocated between the guide rolls to complete the solidification of the hollow fiber shaped product to form a hollow wet film, and the take-up roll takes up at a speed of 15 m / min. I took it in and spun it.

The obtained aromatic polyimide hollow fiber wet membrane having triethylammonium sulfonate group was wound on a bobbin, thoroughly washed with ethanol, and then washed.
It was immersed in a 6 mol / liter hydrochloric acid aqueous solution at room temperature for 2 hours to convert the triethylammonium sulfonate group into a sulfonate group. After immersion, thoroughly wash with ethanol, and then replace the ethanol with isooctane, then at 100 ° C
Then, isooctane was evaporated and dried, and further heat-treated at a temperature of 270 ° C. for 30 minutes to obtain an asymmetric aromatic polyimide hollow fiber membrane having a sulfonic acid group. The outer diameter of the hollow fiber membrane was 350 μm, and the membrane thickness was 60 μm. The permeation performance evaluation results of this asymmetric aromatic polyimide hollow fiber membrane are shown in Table 1.

Example 2 Example 1 was repeated except that the primary coagulation liquid (ethanol) in spinning the solution of the aromatic polyimide having a triethylammonium sulfonate group in Example 1 was replaced with 75% by weight aqueous ethanol solution. In the same manner as described above, an asymmetric aromatic polyimide hollow fiber membrane having a sulfonic acid group was obtained. The outer diameter of the hollow fiber membrane was 350 μm, and the membrane thickness was 57 μm. The permeation performance evaluation results of this asymmetric aromatic polyimide hollow fiber membrane are shown in Table 1.

Example 3 Example 1 was repeated except that the 60% by weight aqueous ethanol solution was used as the primary coagulating liquid (ethanol) during the spinning of the aromatic polyimide solution having a triethylammonium sulfonate group in Example 1. In the same manner as described above, an asymmetric aromatic polyimide hollow fiber membrane having a sulfonic acid group was obtained. The outer diameter of the hollow fiber membrane was 345 μm, and the membrane thickness was 60 μm. The permeation performance evaluation results of this asymmetric aromatic polyimide hollow fiber membrane are shown in Table 1.

Example 4 The acid-treated 6 mol / l hydrochloric acid aqueous solution of Example 1 was added to
An asymmetric aromatic polyimide hollow fiber membrane having a sulfonic acid group was obtained in the same manner as in Example 1 except that the ethanol solution containing 20% by weight of a mol / liter hydrochloric acid aqueous solution was used. The outer diameter of the hollow fiber membrane is 352 μm, and the membrane thickness is 61 μm
Met. The permeation performance evaluation results of this asymmetric aromatic polyimide hollow fiber membrane are shown in Table 1.

Example 5 99 mmol of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) and triethylammonium 3,3'-dimethyl-4,4'-diaminobiphenyl-5-sulfonate (OST -Et ₃ N) 100 mmol and 4-chlorophenol 341 g were placed in a separable flask equipped with a stirrer and a nitrogen gas introduction tube, and polymerized under stirring at a temperature of 160 ° C. for 19 hours to perform imidization reaction. Then, a solution of an aromatic polyimide having a concentration of 16% by weight of triethylammonium sulfonate group dissolved in 4-chlorophenol was prepared.

The aromatic polyimide solution having a triethylammonium sulfonate group was filtered through a 400-mesh stainless steel wire net to prepare a spinning dope. The dope liquid for spinning was prepared by using this as a hollow fiber spinning nozzle (outer diameter of circular opening: 1000 μm, slit width of circular opening: 200 μm, outer diameter of core opening: 400).
A hollow fiber spinning nozzle is charged into the air through a hollow fiber spinning nozzle, and then the hollow fiber shaped article is passed through a dry nitrogen gas atmosphere. Immerse in the primary coagulation liquid of C, and
Temperature in secondary coagulator equipped with a pair of guide rolls 0 ° C
The secondary coagulation liquid is reciprocated between the guide rolls to complete the solidification of the hollow fiber shaped product to form a hollow wet film, and the take-up roll takes up at a speed of 15 m / min. I took it in and spun it.

The obtained aromatic polyimide hollow fiber wet membrane having a triethylammonium sulfonate group was wound on a bobbin, thoroughly washed with ethanol, and then the ethanol was replaced with isooctane.
Was heated to evaporate and dry isooctane. The dried hollow fiber membrane was immersed in a 6 mol / liter hydrochloric acid aqueous solution at room temperature for 30 minutes to convert the triethylammonium sulfonate group into a sulfonate group. After immersion, thoroughly wash with ethanol, then replace ethanol with isooctane, heat to 100 ° C to evaporate and dry isooctane, and heat treat at 270 ° C for 30 minutes to remove sulfonic acid groups. An asymmetric aromatic polyimide hollow fiber membrane was obtained. The outer diameter of the hollow fiber membrane was 350 μm, and the membrane thickness was 60 μm. The permeation performance evaluation results of this asymmetric aromatic polyimide hollow fiber membrane are shown in Table 1.

Example 6 A sulfonic acid group was added in the same manner as in Example 5 except that the time for immersing the dried hollow fiber membrane of Example 5 in a 6 mol / liter hydrochloric acid aqueous solution was changed from 30 minutes to 2 hours. An asymmetric aromatic polyimide hollow fiber membrane was obtained. The outer diameter of the hollow fiber membrane was 361 μm, and the membrane thickness was 65 μm. The permeation performance evaluation results of this asymmetric aromatic polyimide hollow fiber membrane are shown in Table 1.

[0073]

[Table 1]

Comparative Example 1 99 mmol of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 100 mmol of 2,4-diaminobenzenesulfonic acid (mDABS) were prepared.
Along with 217 g of 4-chlorophenol, the mixture was placed in a separable flask equipped with a stirrer and a nitrogen gas introducing pipe,
Polymerization and imidization reaction were carried out at a temperature of 160 ° C. for 5 hours with stirring, but a polymer was deposited and a homogeneous aromatic polyimide solution could not be obtained.

Comparative Example 2 99 mmol of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) and sodium 2,4-diaminobenzenesulfonate (mDABS-Na) 10
0 mmol and 227 g of 4-chlorophenol were placed in a separable flask equipped with a stirrer and a nitrogen gas introducing tube, and polymerization and imidization reaction were carried out at a temperature of 160 ° C. for 4 hours under stirring. A polymer was precipitated and a homogeneous aromatic polyimide solution could not be obtained.

Comparative Example 3 99 mmol of pyromellitic dianhydride (PMDA),
Triethylammonium 2,4-diaminobenzenesulfonate (mDABS-Et ₃ N) 100 mmol,
Along with 227 g of 4-chlorophenol, the mixture was placed in a separable flask equipped with a stirrer and a nitrogen gas introducing tube,
Polymerization and imidization reaction were carried out at a temperature of 160 ° C. for 10 hours under stirring, but the polymer was turbid and a homogeneous aromatic polyimide solution could not be obtained.

Comparative Example 4 99 mmol of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) and triethylammonium 2,4-diaminobenzenesulfonate (mDABS)
-Et ₃ N) 100 mmol and 218 g of N-methylpyrrolidone were placed in a separable flask equipped with a stirrer and a nitrogen gas introduction tube, and the mixture was stirred at 160 ° C.
Polymerization and imidization reaction were carried out at the temperature of 40 hours, but the polymerization solution gelled and it was difficult to form a hollow fiber membrane.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08G 73/00-73/26

Claims (15)

(57) [Claims] 1. The repeating unit is represented by the general formula (1): An aromatic polyimide represented by. However, Ar in the general formula (1) is an aromatic diamine residue represented by the following general formulas (2) and (3), and at least one of R _{1 to} R ₄ in the general formula (2) is -SO ₃ H group, other than hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ₁ in the general formula (3)
At least one of R ₈ to R ₈ is a —SO ₃ H group, and the other is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and X is a direct bond, —O—, —SO ₂ —, —NH—, Carbon number 1
3 represents an alkylene group, an alkylidene group or an alkenylene group. [Chemical 2] [Chemical 3] 2. Ar in the general formula (1) is represented by the following general formula:
The aromatic diamine residue shown in (2) and (3) has the general formula
R in equation (2)₁~ R_FourAt least one of -SO₃
H group, other than hydrogen atom or C 1-3 alkyl
R in the general formula (3) ₁~ R₈At least
One is -SO₃H group, other than hydrogen atom or carbon
The alkyl group of formulas 1 to 3, wherein X is a direct bond.
The aromatic polyimide described in. 3. Ar in the general formula (1) is an aromatic diamine residue represented by the following general formula (2), and at least one of R _{1 to} R ₄ in the general formula (2) is The aromatic polyimide according to claim 1, wherein the aromatic polyimide is a SO ₃ H group and the others are hydrogen atoms. 4. The repeating unit has the general formula (4): The method for producing an aromatic polyimide according to claim 1, wherein the aromatic polyimide represented by the formula (5) is treated with an acid. However,
Ar ′ in the general formula (4) is an aromatic diamine residue represented by the following general formulas (5) and (6), and at least one of R _{1 to} R ₄ in the general formula (5) is SO ₃ N (L) ₄
A group [L is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms],
Others represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and at least one of R _{1 to} R _{8 in} the general formula (6) is
-SO ₃ N (L) ₄ group [L is a hydrogen atom or 1 to 5 carbon atoms
Alkyl group], and other than hydrogen atom or carbon number 1 to
3 represents an alkyl group, X is a direct bond, —O—, —SO
_2- , -NH-, an alkylene group having 1 to 3 carbon atoms, an alkylidene group or an alkenylene group. [Chemical 5] [Chemical 6] 5. A biphenyltetracarboxylic acid compound and compounds represented by the general formulas (7) and (8): [Chemical 8] Monovalent Fe approximately equimolar with the aromatic diamine compound shown in
From Noles, Catechols and Halogenated Phenols
By repeating polymerization and imidization in any solvent selected, the repeating unit is represented by the general formula (4): An aromatic polyimide represented by the following formula is obtained, and the polyimide is treated with an acid to change the --SO ₃ N (L) ₄ group of the polyimide to --SO ₃
The method for producing an aromatic polyimide according to claim 1, wherein the aromatic polyimide is converted into an H group. However, R _{1 to} R in the general formula (7)
_At least one of ₄ is —SO ₃ N (L) ₄ [L is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms], and the other is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. At least one of R _{1 to} R ₈ in (8) is —SO ₃ N.
(L) ₄ [L is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms] and the other is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and X is a direct bond, —O—, —SO ₂ — , -N
H- represents an alkylene group having 1 to 3 carbon atoms, an alkylidene group or an alkenylene group, and Ar ′ in the general formula (4) is
The aromatic diamine residues represented by the above general formulas (7) and (8) are shown. 6. An aromatic diamine compound represented by the general formula (7) or (8) is represented by the general formula (7).
At least one of R _{1 to} R ₄ in the formula is —SO ₃ N
(L) ₄ groups [L is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms], and the others are a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R _{1 to} R ₈ in the general formula (8) are shown. At least one of —SO ₃ N (L) ₄ group [L is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms] and the other is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and X is directly The method for producing an aromatic polyimide according to claim 5, which is a bond. 7. The aromatic diamine compound is the aromatic diamine compound represented by the general formula (7), wherein R ₁ to
The method for producing an aromatic polyimide according to claim 5, wherein at least one of R ₄ is a —SO ₃ N (L) ₄ group [L is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms]. 8. The repeating unit has the general formula (1): An aromatic polyimide semipermeable membrane represented by. However, Ar in the general formula (1) is an aromatic diamine residue represented by the following general formulas (2) and (3), and R _{1 to} R ₄ in the general formula (2) are represented.
At least one of the, at over SO ₃ H group, other represents an alkyl group having 1 to 3 carbon hydrogen atom or a carbon, at least one of R ₁ to R ₈ of general formula (3), over SO ₃ H
Other groups are hydrogen atoms or alkyl groups having 1 to 3 carbon atoms, and X is a direct bond, —O—, —SO ₂ —, —NH
Represents an alkylene group having 1 to 3 carbon atoms, an alkylidene group or an alkenylene group. [Chemical 11] [Chemical 12] 9. Ar in the general formula (1) is an aromatic diamine residue represented by the general formulas (2) and (3), and at least one of R _{1 to} R ₄ in the general formula (2). Is a —SO ₃ H group,
In addition, a hydrogen atom or an alkyl group having 1 to 3 carbon atoms is shown, and at least one of R _{1 to} R _{8 in} the general formula (3) is
-SO ₃ H group, other than hydrogen atom or C 1-3
The aromatic polyimide semipermeable membrane according to claim 8, wherein X is a direct bond in the alkyl group. 10. Ar in the general formula (1) is represented by the general formula (2).
An aromatic diamine residue represented by R ₁ in the general formula (2)
9. The aromatic polyimide semipermeable membrane according to claim 8, wherein at least one of R ₄ to R ₄ is a —SO ₃ H group, and the others are hydrogen atoms. 11. The repeating unit has the general formula (4): The method for producing an aromatic polyimide semipermeable membrane according to claim 8, characterized in that the aromatic polyimide semipermeable membrane represented by However, Ar ′ in the general formula (4) is an aromatic diamine residue represented by the following general formulas (5) and (6), and at least one of R _{1 to} R ₄ in the general formula (5) is , -SO ₃
N (L) ₄ group [L is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms], and the other is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R _{1 to} R in the general formula (6) _At least one of —SO ₃ N (L) ₄ group [L is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms], and the other is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; Is a direct bond, -O
Shown over, over SO ₂ over, over NH chromatography, alkylene group having 1 to 3 carbon atoms, an alkylidene group or an alkenylene group. [Chemical 14] [Chemical 15] 12. A biphenyltetracarboxylic acid compound,
General formulas (7) and (8) [Chemical 17] Monovalent Fe approximately equimolar with the aromatic diamine compound shown in
From Noles, Catechols and Halogenated Phenols
Obtained by polymerizing and imidizing in any selected solvent
By forming a film using a solution of aromatic polyimide
And the repeating unit is represented by the general formula (4): An aromatic polyimide semipermeable membrane represented by the following formula is obtained, and the polyimide semipermeable membrane is treated with an acid to obtain a -SO ₃ N of the polyimide semipermeable membrane.
The method for producing an aromatic polyimide semipermeable membrane according to claim 8, wherein the (L) ₄ group is converted to a —SO ₃ H group. However, at least one of R _{1 to} R _{4 in} the general formula (7) is
-SO ₃ N (L) ₄ [L is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms], and other than that is a hydrogen atom or 1 to 3 carbon atoms
At least one of R _{1 to} R _{8 in} the general formula (8) is —SO ₃ N (L) ₄ [L is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms], and Represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, X is a direct bond,
Over O over, over SO ₂ over, over NH chromatography, an alkylene group, an alkylidene group or an alkenylene group having 1 to 3 carbon atoms, the general formula (4) in Ar 'is the general formula (7) and (8 )
The aromatic diamine residue shown in is shown. 13. The aromatic diamine compound has the general formula (7):
And the aromatic diamine compound represented by (8), at least one of R _{1 to} R _{4 in} the formula (7) is —SO ₃
N (L) ₄ group [L is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms] and the other is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R _{1 to} R in the general formula (8) _At least one of —SO ₃ N (L) ₄ group [L is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms] and the other is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and X is The method for producing an aromatic polyimide semipermeable membrane according to claim 12, which is a direct bond. 14. The aromatic diamine compound has the general formula (7):
An aromatic diamine compound represented by R ₁ in the general formula (7)
At least one of R ₄ to —R ₄ is a —SO ₃ N (L) ₄ group [L
Is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms]. 15. The method for producing an aromatic polyimide semipermeable membrane according to claim 13 or 14, wherein the aromatic polyimide semipermeable membrane is a hollow fiber membrane.