JP2001354767A - Polyimide and its manufacturing method, and gas separating membrane made by using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a gas separating membrane of a polyimide resin having excellent selectivity, heat resistance, chemical resistance, film forming properties, etc. SOLUTION: The polyimide resin has repeating structural units represented by formula (1) (wherein R is a tetravalent organic group; n is an integer of 1 to 8; and m is an integer of 50 to 800). The gas separating membrane is made by using it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas separation membrane made of a polyimide resin and having excellent permeation performance. The gas separation membrane of the present invention not only has excellent permeation performance, but also has extremely good heat resistance, chemical resistance, and the like.

[0002] Gas separation using a separation membrane is useful in various fields because it requires less energy for separation than other methods.

[0003] The separation membrane of the present invention can be used, for example, to separate and recover hydrogen during the synthesis of ammonia, to recover carbon dioxide, remove sulfur oxides and nitrogen oxides from waste gas of thermal power plants and waste incinerators, and to remove off-gas from oil fields. Of carbon dioxide from natural gas, removal of hydrogen sulfide and carbon dioxide from natural gas and separation of helium, recovery of gasoline leaked from gasoline distribution stations, recovery of trace benzene from gasoline, removal of olefins and paraffins in petroleum refining processes Used for separation, pervaporation separation of volatile substance mixture liquid, removal of gas dissolved in liquid, separation of oxygen and nitrogen of air, etc.

[0004]

2. Description of the Related Art Conventionally, a cellulose acetate membrane is well known as a gas separation membrane having excellent properties such as heat resistance, solubility, and film forming properties. Etc. are low and are not satisfactory for practical use. Polysulfone semipermeable membranes are industrially produced as separation membranes with improved heat resistance, but their permeation performance is insufficient and not satisfactory. Although a silicone membrane is known as an oxygen selective permeable membrane, silicone has insufficient mechanical strength and is not industrially satisfactory. Recently, aromatic polyimide resins with high elastic modulus, high strength, low expansion properties, and excellent heat resistance have begun to be studied.
Focusing on selective separation and heat resistance, solubility in various solvents,
In addition, a satisfactory gas separation membrane cannot be obtained, and a practical gas separation membrane has not been obtained.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a gas separation membrane having excellent permselectivity and excellent heat resistance, chemical resistance, film-forming properties, and the like, and a polymer suitable therefor. It is in.

The present inventors have conducted intensive studies to solve the above problems of the gas separation membrane, and found that the above problems can be solved by a gas separation membrane made of a polyimide resin having a specific repeating structural unit. Finally, the present invention has been completed.

That is, the first invention of the present application is the following formula (1):

[0008]

Embedded image (Wherein, R is a tetravalent organic group, n is an integer of 1 to 8,
m means an integer of 50 to 800. The present invention provides a polyimide resin having a repeating structural unit represented by the following formula:

The second invention of the present application is the following formula (2):

[0010]

Embedded image (Wherein, R represents a tetravalent organic group) and a tetracarboxylic dianhydride represented by the following formula (3):

[0011]

Embedded image (Wherein, n represents an integer of 1 to 8). A method for producing a polyimide resin having a repeating structural unit represented by the formula (1), wherein the diamine is polycondensed with a diamine represented by the formula (1). . Further, the third invention of the present application relates to a gas separation membrane obtained from the polyimide resin.

The polyimide resin of the present invention has an average degree of polymerization of 50 to 800 as a repeating structural unit represented by the above (1).
If the degree of polymerization is lower than this, the mechanical strength is inferior and the resin becomes brittle. On the other hand, if it is large, the resin becomes inferior in workability and film forming property due to high viscosity.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The first invention is a polyimide having a repeating structural unit represented by the above formula (1). formula
In (1), R is a tetravalent organic group and is derived from a tetracarboxylic dianhydride represented by the following formula (2).

[0014]

Embedded image (In the formula, R is the same as described above.)

Specific examples of such an acid dianhydride include:
Pyromellitic dianhydride, methylpyromellitic dianhydride, trifluoromethylpyromellitic dianhydride, phenylpyromellitic dianhydride, diphenylpyromellitic dianhydride, 3,3 ', 4,4' -Biphenyltetracarboxylic dianhydride, 2,2'-diphenyl-3,3 ', 4,4'-
Biphenyltetracarboxylic dianhydride, 2,2'-ditrifluoro-3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride 3,3'4,4'-benzophenonetetracarboxylic dianhydride, 2,2'3,3'-benzophenonetetracarboxylic dianhydride, 3,3 ', 4,4'-diphenylsulfonetetracarboxylic acid Dianhydride, 3,3 ', 4,4'-
Diphenylhexafluoroisopropylidenetetracarboxylic dianhydride, 1,1'-bis (3,4-dicarboxyphenyl) -1-phenyl-2,2,2-trifluorofluoroethane dianhydride, 3,3 ', 4,4'-diphenylisopropylidenetetracarboxylic dianhydride, 3,3 ', 4,4'-diphenylmethanetetracarboxylic dianhydride, 3,3'4,4'
-Benzosulfidetetracarboxylic dianhydride, 2,2 '
3,3′-benzosulfidetetracarboxylic dianhydride,
3,3 ', 4,4'-diphenylaminetetracarboxylic dianhydride, 3,3', 4,4'-diphenylamidetetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenoxy ) Diphenylpropane dianhydride, bis (3,4-dicarboxyphenoxy) benzene dianhydride, bis (3,4
-Dicarboxyphenoxy) ethane dianhydride, bis (3,
4-dicarboxyphenyl) hexafluoropropane dianhydride, 4,4'-bis (3,4-dicarboxyphenoxy)
Diphenyl sulfide dianhydride, 4,4'-oxydiphthalic dianhydride, bis (3,4-dicarboxyphenyl)
And phosphine oxide dianhydride.

Accordingly, preferable R includes those having the following structural formulas.

[0017]

Embedded image

(Diamine) The polyimide of the formula (1) is prepared by combining the above-mentioned acid dianhydride with the following formula (3):

[0019]

Embedded image (Wherein, n is the same as described above).

In the diamine represented by the above general formula (3), 4,4'-diaminophenoxymethane, 1,2-bis (4-aminophenoxy) ethane, and 1,3-bis (4-aminophenoxy) Propane, 1,4-bis (4-aminophenoxy) butane, 1,5-bis (4-aminophenoxy)
Pentane, 1,6-bis (4-aminophenoxy) hexane, 1,7-bis (4-aminophenoxy) heptane, 1,
8-S (4-minophenoxy) octane, 1,9-bis (4
-Aminophenoxy) nonane, 1,10-bis (4-aminophenoxy) decane, 1,11-bis (4-aminophenoxy) undecane, 1,12-bis (4-aminophenoxy) dodecane, 1,13-bis (4-aminophenoxy)
Tridecane, 1,14-bis (4-aminophenoxy) tetradecane, 1,15-bis (4-aminophenoxy) pentadecane, 1,16-bis (4-aminophenoxy) hexadecane, 1,17-bis (4-amino Phenoxy) heptadecane, 1,18-bis (4-aminophenoxy) octadecane, 1,19-bis (4-aminophenoxy) nonadecane, 1,20-bis (4-aminophenoxy) icosane, and the like.

In the formula (3), when the value of-(CH ₂ ) _n- increases, the strength of the resin decreases. Therefore, n is preferably 8 or less. Polyimides can be produced by equimolar condensation polymerization of these tetracarboxylic dianhydrides and diamines. The polymerization method is not particularly limited, and any conventionally known method can be employed as a polymerization method for polyimide.

(Production method) The novel polyimide of the present invention has the following formula (2):

[0023]

Embedded image (Wherein R is as defined above) and a tetracarboxylic dianhydride represented by the following formula (3):

[0024]

Embedded image (Wherein, n is the same as described above). The ratio of the two used for double-jumping is 1: 0.95 to 1: 1 in molar ratio.
05, preferably about equimolar.

The polymerization method is not particularly limited, and a polyimide can be produced by using a known polycondensation method with the above-mentioned tetracarboxylic dianhydride.

As the solvent used for the polymerization reaction, N-
Methyl-2-pyrrolidone, N, N-dimethylacetamide, dimethylsulfoxide, diglyme, N, N-dimethylformamide, 1,3-dimethyl-2-imidazolidin, hexamethylphosphoramide, m-cresol and the like. These may be used alone or in combination of two or more. The use amount of the solvent with respect to the raw material is not particularly limited, but usually it is preferable to use 3 to 30% by weight.

In the reaction, a diamine component and a tetracarboxylic dianhydride component are mixed and reacted at a temperature lower than room temperature for usually 3 to 20 hours to obtain a polyamic acid. Next, a dehydration ring-closing agent such as acetic anhydride, pyridine or triethylamine is added to the reaction solution, and the mixture is further added at room temperature.
The polyamic acid is made into a polyimide by reacting for ~ 24 hours. Alternatively, the polyamic acid is heated to 180 to 200 ° C., and benzene, toluene, xylene, chlorobenzene,
While adding a hydrocarbon or a chlorinated solvent which can azeotrope with water such as dichlorobenzene and removing the water generated by the cyclization of the amic acid out of the system by azeotropy, the polyamic acid is reacted with the polyimide for 5 to 10 hours to obtain a polyimide. Become The polyimide obtained from these was N-methyl-2-pyrrolidone, N, N-
Dimethylacetamide, dimethylsulfoxide, diglyme, N, N-dimethylformamide, 1,3-dimethyl-2-imidazolidin, hexamethylphosphoramide,
It is soluble in m-cresol and the like.

(Gas separation membrane and manufacturing method thereof)
The present invention is a gas separation membrane comprising the polyimide resin represented by the above formula (1). Since this polyimide resin is a polymer obtained by condensation polymerization of tetracarboxylic dianhydride and a diamine component as raw materials, some polyimide resins have various repeating structural units depending on the type of raw material, mixing ratio and the like.

The polyimide resin used in the present invention is N
-Methyl-2-pyrrolidone 0.5 g per deciliter
Intrinsic viscosity of 0.4 to 2.
0, preferably 0.5 to 1.5. If the intrinsic viscosity is lower than this, the self-supporting property of the gas separation membrane is poor, and the mechanical strength is insufficient. On the other hand, if the intrinsic viscosity is larger than this, it is difficult to obtain a uniform film-forming solution, and it becomes difficult to form a film. Therefore, the degree of polymerization m is 50-800, preferably 110-7.
00.

The gas separation membrane of the present invention can be produced from the polyimide by various methods. That is, the polyimide represented by the formula (1) is dissolved in a film-forming solution solvent to form a uniform film-forming solution, which is cast and applied to a suitable support substrate, and then subjected to a heat treatment or a heat treatment under reduced pressure. The solvent is evaporated to a homogeneous film. A sufficiently thin film is necessary to achieve a practicable gas permeation performance, that is, a large permeation speed, but the film thickness is preferably 0.03 to 20 μm from the viewpoint of mechanical strength and generation of pinholes.

Therefore, the film forming solution is desirably 20% by weight or less, preferably 10% by weight or less for forming the thin film. In order to improve the film-forming property, the film-forming solvent is N-methyl-2-pyrrolidone, N, N-dimethylacetamide, dimethylsulfoxide, N, N-dimethylformamide, 1,3-dimethyl- like the polymerization reaction solvent. Organic solvents such as 2-imidazolidinone and hexamethylphosphoramide that dissolve the polyimide resin of the present invention uniformly and well are preferable.

The supporting substrate used for applying the film forming solution is not particularly limited. A member having a smooth surface made of a material exemplified by a heat-resistant polymer, glass, metal, ceramic or the like is exemplified. After applying the film-forming solution to the supporting substrate, the heating temperature depends on the film-forming solution solvent.
It is 0-200 ° C, preferably 100-150 ° C. Particularly preferably, after most of the solvent is evaporated in such a temperature range, the temperature is raised to 200 to 300 ° C., and the solvent is completely evaporated to obtain a uniform thin film.

As another method, after the film-forming solution is applied to the supporting substrate, the film-forming solution is quickly immersed in water or an organic solvent (poor solvent for polyimide) which is completely mixed with the organic solvent, and then dried at the above temperature. Then, a heterogeneous film having an active separation thin film layer may be formed. There is no limitation on these film shapes and film forms, and a composite film may be used. The membrane shape can be a flat membrane or a hollow fiber membrane.

[0034]

Next, the present invention will be described more specifically with reference to examples. The physical properties of the obtained separation membrane were measured by the following methods.

[0035]Gas permeability coefficient  An index indicating the rate of gas permeation through a semipermeable membrane, in units
Is represented by the following equation. Barrer = 1 × 10^-Tencm^Three(STP) cm / cm^Two/ S / c
mHg [cm^Three(STP) transmits at standard temperature and pressure (0 ° C, 1 atm)
The volume of gas, cm is the thickness of the film, cm^TwoIs
The area of the film, s indicates time, and cmHg indicates pressure. ]

[0036]Selectivity  Gas selectivity of semi-permeable membranes is measured for each gas alone on the same membrane
It is expressed by the ratio of the transmission coefficient. For example, CO_Two/ N_Two=
50 indicates that the film concerned is CO_TwoGas N_Two50 times faster than gas
Indicates transmission.

The gas separation membrane provided by the present invention comprises:
It has excellent heat resistance, chemical resistance, etc., can be used as a gas separation membrane in a wide range of fields, and its gas permeation performance and selectivity are much better than conventional heat-resistant polymer materials.

Example 1 (Preparation of polyimide resin) 4,4'-diaminophenoxymethane was placed in a 1 L three-necked flask equipped with a dropping funnel.
0 g (21.7 mmol) and 131.8 g of N, N-dimethylacetamide (the amount of which the concentration of the total weight of the starting material diamine and acid dianhydride becomes 10%) were dissolved under stirring in an argon gas atmosphere. After immersing this flask in a water bath at 0 to 10 ° C., 3,3 ′, 4,4′-diphenylhexafluoroisopropylidenetetracarboxylic dianhydride (6FDA) 9.
64 g (21.7 mmol) were added in three portions over 1 hour.

After the addition, the flask was returned to room temperature and reacted with stirring for 8 hours to obtain a polyamic acid. 7.75 g (76 mmol) of acetic anhydride as an imidizing agent (3.5 times the molar amount of the starting diamine) and pyridine 6.
After adding 00 g (76 mmol) (3.5 times the molar amount of the starting diamine) and reacting at room temperature for 15 hours, the mixture was added to a water-alcohol mixed solution (10 times the amount of the polymerization reaction solution). To obtain a polyimide resin precipitate. It was further washed several times with alcohol and dried.

The obtained polyimide resin was in the form of a pale yellow flake, and the yield was 13.35 g (91.2%). The intrinsic viscosity of the polyimide resin is 1.84 (dL / g) (NMP,
30 ° C). As a result of the analysis, the structure of this polyimide resin was determined by NMR spectrum (FIG. 1) and IR spectrum.
The following structure was confirmed from (FIG. 2).

[0041]

Embedded image The average degree of polymerization m of the obtained polyimide resin was 650. This polyimide resin is an organic solvent (N-methyl-2-
Pyrrolidone, N, N-dimethylacetamide, dimethylsulfoxide, N, N-dimethylformamide, 1,3-
Dimethyl-2-imidazolidinone, hexamethylphosphoramide).

(Production and Evaluation of Gas Separation Membrane) This polyimide resin was dissolved in N-methyl-2-pyrrolidone at a concentration of 18% by weight, filtered through a filter paper having a pore size of 5 μm, and defoamed under reduced pressure. This polyimide resin solution was cast and applied on a glass plate, and was heated at 80 ° C. × 2 hours, 110 ° C. × 1 hour, 150 ° C. × 1
The solvent was removed at 200 ° C. for 1 hour. After peeling from the glass plate, it was subjected to a heat treatment in a vacuum dryer at 200 ° C. for 72 hours.

Even when the obtained film was folded in two, the film was so strong that no crack was formed. Tables 1 and 2 below show the permeation coefficients and selective separation properties of each gas when the pressure difference between the two surfaces of helium, methane, nitrogen, oxygen, and carbon dioxide at 25 ° C. is 2.97 atm. It was shown to.

Example 2 (Production of polyimide resin) Diamine was 1,2-bis (4-
Polyimide was polymerized in the same manner as in Example 1 except that the amount was changed to 10 g (40 mmol) of aminophenoxy) ethane. The acid dianhydride used in the reaction, 6FDA, was equimolar to the diamine, and the imidizing agent used was 3.5 times the molar amount of the diamine. The obtained polyimide resin was in the form of a pale yellow flake, and the yield was 25.4 g (97.1%).

The intrinsic viscosity of the polyimide resin is 1.02 (dL
/ G) (NMP, 30 ° C). As a result of the analysis, the structure of this polyimide resin was confirmed by NMR spectra (FIG.
The following structure was confirmed from the R spectrum (FIG. 4).

[0046]

Embedded image

The average degree of polymerization m of the obtained polyimide resin was 520. This polyimide resin is an organic solvent (N-
Methyl-2-pyrrolidone, N, N-dimethylacetamide, dimethylsulfoxide, N, N-dimethylformamide, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphoramide).

(Production and Evaluation of Gas Separation Membrane) Production and evaluation of the gas separation membrane were performed in the same manner as in Example 1. Even if the obtained film was folded in two, it was so strong that no crack was required. The permeation coefficient and selective separation property of each gas of this membrane are shown in Tables 1 and 2 below.

[Example 3] (Production of polyimide resin) Diamine was 1,3-bis (4-
Polyimide was polymerized in the same manner as in Example 1 except that the amount of aminophenoxy) propane was changed to 10 g (38.7 mmol). The acid dianhydride used in the reaction, 6FDA, was equimolar to the diamine, and the imidizing agent used was 3.5 times the molar amount of the diamine.

The obtained polyimide resin was in the form of a pale yellow flake, and the yield was 24.8 g (96.1%). The intrinsic viscosity of the polyimide resin is 0.83 (dL / g) (NMP, 30
° C). As a result of analysis, the structure of this polyimide resin was found to be NMR spectrum (FIG. 5) and IR spectrum (FIG. 6).
Confirmed that the structure was as follows.

[0051]

Embedded image

The average degree of polymerization m of the obtained polyimide resin was 440. This polyimide resin is an organic solvent (N-
Methyl-2-pyrrolidone, N, N-dimethylacetamide, dimethylsulfoxide, N, N-dimethylformamide, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphoramide).

(Production and Evaluation of Gas Separation Membrane) Production and evaluation of the gas separation membrane were performed in the same manner as in Example 1. Even if the obtained film was folded in two, it was so strong that no crack was required. The permeation coefficient and selective separation property of each gas of this membrane are shown in Tables 1 and 2 below.

Example 4 (Production of polyimide resin) Diamine was 1,4-bis (4-
Polyimide was polymerized in the same manner as in Example 1 except that the amount of aminophenoxy) butane was changed to 19 g (69.8 mmol). The acid dianhydride used in the reaction, 6FDA, was equimolar to the diamine, and the imidizing agent used was 3.5 times the molar amount of the diamine.

The obtained polyimide resin was in the form of a pale yellow flake, and the yield was 43.7 g (91.9%). The intrinsic viscosity of the polyimide resin is 2.30 (dL / g) (NMP, 30
° C). As a result of the analysis, the structure of the polyimide resin was found to be NMR spectrum (FIG. 7) and IR spectrum (FIG. 8).
Confirmed the following structure.

[0056]

Embedded image

The average degree of polymerization m of the obtained polyimide resin was 800. This polyimide resin is an organic solvent (N-
Methyl-2-pyrrolidone, N, N-dimethylacetamide, dimethylsulfoxide, N, N-dimethylformamide, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphoramide).

(Production and Evaluation of Gas Separation Membrane) The production and evaluation of the gas separation membrane were performed in the same manner as in Example 1. Even if the obtained film was folded in two, it was so strong that no crack was required. Tables 1 and 2 show the permeability coefficient and the selective separation property of each gas of this membrane.

[Example 5] (Production of polyimide resin) Diamine was 1,5-bis (4-
Polyimide was polymerized in the same manner as in Example 1 except that the amount of aminophenoxy) pentane was changed to 19 g (66.4 mmol). The acid dianhydride used in the reaction, 6FDA, was equimolar to the diamine, and the imidizing agent used was 3.5 times the molar amount of the diamine.

The obtained polyimide resin was in the form of a pale yellow flake, and the yield was 42.0 g (91.2%). The intrinsic viscosity of the polyimide resin is 2.29 (dL / g) (NMP, 30
° C). As a result of the analysis, the structure of this polyimide resin was confirmed by NMR spectrum (FIG. 9) and IR spectrum (FIG. 1).
From 0), the following structure was confirmed.

[0061]

Embedded image

The average degree of polymerization m of the obtained polyimide resin was 790. This polyimide resin is an organic solvent (N-
Methyl-2-pyrrolidone, N, N-dimethylacetamide, dimethylsulfoxide, N, N-dimethylformamide, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphoramide).

(Production and Evaluation of Gas Separation Membrane) Production and evaluation of the gas separation membrane were performed in the same manner as in Example 1. Even if the obtained film was folded in two, it was so strong that no crack was required. Tables 1 and 2 show the permeability coefficient and the selective separation property of each gas of this membrane.

Example 6 (Production of polyimide resin) Diamine was 1,6-bis (4-
10.0 g of aminophenoxy) hexane (33.3 mmol
A polyimide was polymerized in the same manner as in Example 1 except that the method was changed to l). The acid dianhydride used in the reaction, 6FDA, was equimolar to the diamine, and the imidizing agent used was 3.5 times the molar amount of the diamine.

The obtained polyimide resin was in the form of a pale yellow flake, and the yield was 23.0 g (97.5%). The intrinsic viscosity of the polyimide resin is 1.51 (dL / g) (NMP, 30
° C). As a result of analysis, the structure of this polyimide resin was confirmed to be the following structure from the NMR spectrum (FIG. 11) and the IR spectrum (FIG. 12).

[0066]

Embedded image

The average degree of polymerization m of the obtained polyimide resin was 680. This polyimide resin is an organic solvent (N-
Methyl-2-pyrrolidone, N, N-dimethylacetamide, dimethylsulfoxide, N, N-dimethylformamide, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphoramide).

(Production and Evaluation of Gas Separation Membrane) The production and evaluation of the gas separation membrane were performed in the same manner as in Example 1. Even if the obtained film was folded in two, it was so strong that no crack was required. Tables 1 and 2 show the permeability coefficient and the selective separation property of each gas of this membrane.

Example 7 (Preparation of polyimide resin) Diamine was 1,8-bis (4
-Aminophenoxy) octane 5.0 g (15.3 mmol)
A polyimide was polymerized in the same manner as in Example 1 except that the method was changed to l). The acid dianhydride used in the reaction, 6FDA, was equimolar to the diamine, and the imidizing agent used was 3.5 times the molar amount of the diamine.

The obtained polyimide resin was in the form of a pale yellow flake, and the yield was 11.1 g (98.4%). The intrinsic viscosity of the polyimide resin is 1.13 (dL / g) (NMP, 30
° C). As a result of the analysis, the structure of this polyimide resin was confirmed to be the following structure from the NMR spectrum (FIG. 13) and the IR spectrum (FIG. 14).

[0071]

Embedded image

The average degree of polymerization m of the obtained polyimide resin was 610. This polyimide resin is an organic solvent (N-
Methyl-2-pyrrolidone, N, N-dimethylacetamide, dimethylsulfoxide, N, N-dimethylformamide, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphoramide).

(Production and Evaluation of Gas Separation Membrane) Production and evaluation of the gas separation membrane were performed in the same manner as in Example 1. Even if the obtained film was folded in two, it was so strong that no crack was required. Tables 1 and 2 show the permeability coefficient and the selective separation property of each gas of this membrane.

[0074]

[Table 1] Gas permeability coefficient

[0075]

[Table 2] Selective gas separation

[0076]

The gas separation membrane made of the polyimide resin of the present invention has excellent permeation performance, heat resistance, chemical resistance, film forming properties, and the like.

[Brief description of the drawings]

FIG. 1 is an NMR spectrum of the polyimide obtained in Example 1.

FIG. 2 is an IR spectrum of the polyimide obtained in Example 1.

FIG. 3 is an NMR spectrum of the polyimide obtained in Example 2.

FIG. 4 is an IR spectrum of the polyimide obtained in Example 2.

FIG. 5 is an NMR spectrum of the polyimide obtained in Example 3.

FIG. 6 is an IR spectrum of the polyimide obtained in Example 3.

FIG. 7 is an NMR spectrum of the polyimide obtained in Example 4.

FIG. 8 is an IR spectrum of the polyimide obtained in Example 4.

FIG. 9 is an NMR spectrum of the polyimide obtained in Example 5.

FIG. 10 is an IR spectrum of the polyimide obtained in Example 5.

FIG. 11 is an NMR spectrum of the polyimide obtained in Example 6.

FIG. 12 is an IR spectrum of the polyimide obtained in Example 6.

FIG. 13 is an NMR spectrum of the polyimide obtained in Example 7.

FIG. 14 is an IR spectrum of the polyimide obtained in Example 7.

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 4D006 GA41 MA01 MA03 MA06 MB04 MB11 MB15 MC54X NA05 NA10 NA62 NA64 PB17 PB18 PB19 4F071 AA60 AF02 AF08 AF45 AH02 BA02 BB02 BC01 BC17 4J043 PA04 PA10 PB08 PB14 PB15 Q0231 TA47 TA71 TB01 UA122 UA131 UA132 UA142 UA152 UB012 UB121 UB122 UB152 UB222 UB242 UB282 UB292 UB302 UB382 VA011 VA012 VA051 VA091 XA16 YA06 YA23 ZB13

Claims (3)

[Claims] 1. The following formula (1): (Wherein, R is a tetravalent organic group, n is an integer of 1 to 8, m is 5
It means an integer of 0 to 800. A) a polyimide resin having a repeating structural unit represented by 2. The following formula (2): (Wherein, R represents a tetravalent organic group) and a tetracarboxylic dianhydride represented by the following formula (3): The method for producing a polyimide resin according to claim 1, wherein the diamine represented by the following formula (where n represents an integer of 1 to 8) is polycondensed. 3. A gas separation membrane comprising the polyimide resin according to claim 1.