JP2003062439A - Gas separation membrane and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a gas separation membrane having excellent permeability while keeping practically high selectivity preferably with respect to acidic gas, and the gas separation membrane obtained thereby. SOLUTION: The method for manufacturing the gas separation membrane includes a process for developing a film forming liquid, which contains 3-40 wt.% of a fluorine-containing polyimide resin, 40-95 wt.% of a glycol-based solvent with a boiling point of 120 deg.C or higher, 1-40 wt.% of a non-alcoholic solvent with a boiling point of 85 deg.C or lower and 1-40 wt.% of an alcoholic solvent, in a hollow or flat membrane form, a process for evaporating the solvent component from the surface of the film forming liquid and a process for immersing the developed membrane in a coagulation liquid to perform desolvation.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a gas separation membrane of a fluorine-containing polyimide resin according to a so-called dry-wet phase conversion membrane production method, and a gas separation membrane obtained by the production method. Particularly, it is useful as a method for producing a gas separation membrane for selectively separating a specific acidic gas from a gas mixture containing an acidic gas.

[0002]

2. Description of the Related Art In recent years, as a technique for separating and recovering a specific gas from a mixed gas, the use of a gas separation membrane having a selective permeation function has attracted attention from the viewpoint of energy saving and low environmental load. Cellulose acetate, ethyl cellulose, polycarbonate, polyimide, polysulfone, polyamide and the like are known as polymer materials used for such gas separation membranes. Specifically, for example, the gas separation membranes described in JP-A-61-110210 and JP-A-61-14507 have been proposed.

On the other hand, a technique for efficiently separating an acidic gas such as carbon dioxide from a mixed gas generated in the natural gas refining industry or a thermal power plant is required, and a method using a gas separation membrane is also being studied. .

[0004]

However, most of the conventional gas separation membranes are still insufficient in selectivity / permeability to acidic gas, and are not yet widely used.

On the other hand, fluorine-containing polyimide is known as a membrane separation material having excellent heat resistance and gas separation property. For example, JP-A-5-7749 and US Pat. No. 3,822.
202, US Pat. No. 3,899,309, US Pat. No. 4
532041, US Pat. No. 4,645,824, US Pat. No. 4,705,540, US Pat. No. 4,717,393,
U.S. Pat. No. 4,717,394, U.S. Pat.
No. 0, US Pat. No. 4,897,092, US Pat. No. 493.
No. 2982, U.S. Pat. No. 4,929,405, U.S. Pat. No. 4,981,497, U.S. Pat. No. 5,042,992 and the like disclose gas separation membranes made of a fluorine-containing aromatic polyimide. However, none of the production methods disclosed in these documents carry out a dry-wet phase conversion film-forming method using a fluorine-containing polyimide resin as an appropriate film-forming liquid, and gas separation with sufficient selectivity / permeability to acidic gas. The membrane could not be manufactured.

Therefore, an object of the present invention is to preferably produce a gas separation membrane having excellent permeability with respect to acidic gas while having practically high selectivity, and a method for producing the gas separation membrane. It is to provide a gas separation membrane obtained by.

[0007]

The inventors of the present invention have found that a skin layer formed by a dry-wet phase conversion film-forming method generally has a semi-solid state film on the surface of a polymer solution formed by solvent evaporation. As a result of diligent study, we found that it is deeply involved in the balance between the growth rate and the diffusion rate of the polymer solvent into the coagulation liquid during gelation and the penetration rate of the coagulation liquid into the polymer solution during the gelation. A skin layer suitable as a gas separation membrane can be formed by performing a dry-wet phase conversion film-forming method using a polyimide resin as a film-forming solution having a specific composition, and by using a specific fluorine-containing polyimide resin, it is particularly acidic. Finding that high selectivity and permeability for gas can be obtained,
The present invention has been completed.

That is, the method for producing a gas separation membrane of the present invention is
Fluorine-containing polyimide resin 3-40% by weight, boiling point 12
Glycol-based solvent having a temperature of 0 ° C. or higher 40-95% by weight, non-alcoholic organic solvent having a boiling point of 85 ° C. or lower 1-40
A step of developing a film-forming solution containing 1% to 40% by weight of an alcoholic solvent into a hollow or flat film, and a step of partially evaporating a solvent component from the surface of the film-forming solution, And a step of removing the solvent by bringing it into contact with a coagulation liquid.

In the above, the fluorine-containing polyimide resin has a projected cross-sectional maximum width of a cubic structure of repeating unit molecular chains determined by a molecular orbital method of 10 Å or more, and the obtained gas separation membrane is for selective separation of acidic gas. Is preferred. The maximum width of the projected cross section of the three-dimensional structure of the repeating unit molecular chain obtained by the molecular orbital method is the repeating unit of the polymer determined by the molecular structure optimization calculation in the ab initio molecular orbital method or the semi-empirical molecular orbital method. In the three-dimensional structure of the molecular chain, it corresponds to the maximum diameter when the unit molecular chain is rotated about the axis connecting both ends of the main chain in a straight line. The molecular structure optimization calculation is specifically Gaus
sian Inc. It can be executed by using a computational chemistry program such as Gaussian series manufactured by FUJITSU LIMITED or MOPAC series manufactured by FUJITSU LIMITED.

On the other hand, the gas separation membrane of the present invention can be obtained by the above method for producing a gas separation membrane, and the maximum projected cross-sectional width of the three-dimensional structure of the repeating unit molecular chain determined by the molecular orbital method is 10 Å or more. It is a gas separation membrane for selective separation of acidic gas which has an asymmetric membrane layer of a fluorine-containing polyimide resin.

As the fluorine-containing polyimide resin,
Those having a repeating unit represented by the following general formula (I) can be used.

[0012]

[Chemical 3] (In the formula, R represents any of the following divalent organic groups.)

[Chemical 4] [Operation and Effect] According to the production method of the present invention, the fluorine-containing polyimide resin is used as a film-forming liquid having a specific composition to perform the dry-wet phase-conversion film-forming method, so that it is possible to suppress defects in the skin layer portion and reduce the thickness. As shown by the results of Examples, a gas separation membrane having high selectivity and permeability can be manufactured. The reason is considered as follows. That is, since the boiling point of the glycol-based solvent is 120 ° C. or higher, the rate of diffusion of the glycol-based solvent into the coagulation liquid becomes appropriate, and the probability of causing defects in the surface-side skin layer having a gas separation function is reduced. In addition, since the boiling point of the non-alcoholic organic solvent is 85 ° C. or less, the evaporation rate of the volatile solvent increases during film formation, and the film in a semi-solid state is formed on the surface of the film forming liquid within the practical film forming operation time. It becomes easy to form a suitable skin layer. Furthermore, since the film-forming solution contains an appropriate amount of alcohol solvent, it is effective in suppressing excessive growth of the skin layer during the phase separation process.

The fluorine-containing polyimide resin is
When the projected cross-sectional maximum width of the three-dimensional structure of the repeating unit molecular chain determined by the molecular orbital method is 10 Å or more, the packing property of the molecular chain becomes appropriate and the acid gas permeability becomes good. It is speculated that, together with the skin layer, it will exhibit high selectivity and permeability as a gas separation membrane for selective separation of acidic gas.

On the other hand, the gas separation membrane of the present invention exhibits high selectivity and permeability as a gas separation membrane for selective separation of acidic gas as described above.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. The production method of the present invention, after partially evaporating the solvent in the solution of the polymer as the membrane material, the polymer is not dissolved, but becomes a liquid compatible with the solvent of the polymer in the polymer solution (hereinafter referred to as coagulation liquid). This is based on a so-called dry-wet phase conversion film-forming method in which the polymer is gelled by bringing the polymer solvent and the coagulating liquid into contact with each other to cause the polymer to gel. In order to obtain a membrane having a practical gas separation performance by this membrane formation method, the skin layer portion exhibiting the separation function is made as thin as possible to reduce the gas permeation resistance and reduce the defects in the skin layer. This is very important.

Therefore, in the present invention, 3 to 40% by weight of the fluorine-containing polyimide resin, 40 to 95% by weight of the glycol solvent having a boiling point of 120 ° C. or higher, and 1 to the non-alcohol organic solvent having a boiling point of 85 ° C. or lower. A film forming solution containing 40% by weight and 1 to 40% by weight of an alcohol solvent is used. From the viewpoint of reliably obtaining a gas separation membrane exhibiting high selectivity and permeability, the composition of the membrane-forming liquid is such that the fluorine-containing polyimide resin is 10 to 30% by weight, the glycol solvent is 60 to 90% by weight, and the non-alcohol organic solvent 5 is used. It is preferable to contain -30 wt% and alcohol solvent 5-20 wt%.

In addition, when using the fluorine-containing polyimide resin having the repeating unit represented by the above general formula (I), in obtaining a gas separation membrane for acidic gas selective separation having high selectivity and permeability, The composition of the film forming liquid contains 10 to 30% by weight of a fluorine-containing polyimide resin, 60 to 90% by weight of a glycol solvent, 5 to 30% by weight of a non-alcoholic organic solvent, and 5 to 20% by weight of an alcohol solvent. Is preferred.

The fluorine-containing polyimide resin may be any one having at least one fluorine in the repeating unit, and preferably has at least one --CF ₃ group. Examples of such a fluorine-containing polyimide resin include those having a repeating unit represented by the following general formula (II). The weight average molecular weight of the fluorine-containing polyimide resin is preferably about 30,000 to 800,000.

[0019]

[Chemical 5] (However, A ₁ and A ₂ represent the same or different tetravalent organic groups, R ₁ and R ₂ represent the same or different divalent organic groups,
At least one organic group of A ₁ or A ₂ is an organic group having three or more fluorine atoms, and at least one organic group of A ₁ , A ₂ , R ₁ or R ₂ is a —CF ₃ group. Is an organic group having at least one, and m and n represent a molar ratio of repeating units, but may be a homopolymer of n = 0. ) Specific examples of the fluorine-containing polyimide resin having a repeating unit represented by the general formula (II) include JP-A-5-7749.
U.S. Pat. No. 3,822,202, U.S. Pat. No. 38
99309, US Pat. No. 4,532,041, US Pat. No. 4,645,824, US Pat. No. 4,705,540, US Pat. No. 4,717,393, US Pat. No. 4,717,394.
U.S. Pat. No. 4,838,900, U.S. Pat. No. 4,897.
092, US Pat. No. 4,932,982, US Pat. No. 4
Any of those exemplified in 929405, US Pat. No. 4,981,497, US Pat. No. 5,042,992, etc. can be used.

When the tetravalent organic group represented by A ₁ or A _{2 in} the general formula (II) has three or more fluorine atoms, the proton of the aromatic hydrocarbon or the aliphatic hydrocarbon combines with the fluorine atom or the fluorine atom. For example, the one replaced with the base is exemplified. Preferably, the tetravalent organic group of A ₁ or A ₂ is
Those in which at least one proton is replaced with one —CF ₃ group are used, and examples thereof include a tetravalent organic group represented by the following formula (Formula 6).

[0021]

[Chemical 6] In the present invention, when a gas separation membrane for selective separation of acidic gas is obtained, a fluorine-containing polyimide resin having a projected cross-section maximum width of 10 Å or more of a three-dimensional structure of a repeating unit molecular chain obtained by a molecular orbital method is used. . This is because if the maximum width of the projected cross section is less than 10Å, the filling property of the molecular chains becomes excessively high, and the gas permeability of the acid gas becomes too small. As such a fluorine-containing polyimide resin, one having a repeating unit represented by the above general formula (I) is preferable.

That is, R ₁ or R ₂ of the general formula (II)
The divalent organic group of is preferably a structure containing phenylene in the main chain, but in order to set the projected cross-section maximum width to 10 Å or more, the divalent organic group represented by the following formula (Formula 7) It is preferably used.

[0023]

[Chemical 7] The fluorine-containing polyimide resin used in the present invention may be used alone as a homopolymer or a copolymer as described above, but may be used as a mixture of two or more kinds. Further, if it is 50 mol% or less, it may be a copolymer or a mixture with a polymer such as polysulfone or polyether sulfone other than the fluorine-containing polyimide resin.

The fluorine-containing polyimide resin used in the present invention can be obtained by using a tetracarboxylic dianhydride and a diamine component by a known polymerization method as described in, for example, US Pat. No. 3,959,350. For example, polycarboxylic acid is polymerized by using tetracarboxylic dianhydride and diamine compound in approximately equimolar amounts in a polar solvent at a temperature of about 80 ° C. or less, preferably at 0 to 60 ° C.
The polar solvent used here is not particularly limited, but N-
Methyl 2-pyrrolidone, pyridine, dimethylacetamide, dimethylformamide, dimethylsulfoxide, tetramethylurea, phenol, cresol and the like are preferably used.

A tertiary amine compound such as trimethylamine, triethylamine and pyridine, and an imidization promoter such as acetic anhydride, thionyl chloride and carbodiimide are added to a solution of the obtained polyamic acid in a polar solvent, and the mixture is added at a temperature of 5 to 150 ° C. Stir and imidize. When performing the imidization reaction,
The polyamic acid solution is added at 100 to 400 ° C., preferably 120 to 30 without adding an imidization accelerator.
You may heat at 0 degreeC and may be imidized.

After the imidization reaction, in order to remove the polar solvent and imidization promoter during the polymerization, the solution is dropped into a large amount of a solution of acetone, alcohol, water or the like and purified to obtain a polyimide resin suitable as a film material. can get.

When the imidization reaction is carried out without adding an imidization accelerator, a polyamic acid powder or a polyamic acid solution obtained by dropping the polyamic acid solution into a large amount of a solution of acetone, alcohol or the like. By imidizing the polyamic acid solid obtained by evaporating the solvent from (from which a polyamic acid powder may be formed by adding a precipitating agent or the like during evaporation and filtered off) at 100 to 400 ° C. A polyimide resin suitable as a film material can be obtained.

The glycol solvent in the film-forming solution of the present invention is not particularly limited as long as it has a boiling point of 120 ° C. or higher. Diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether,
Diethylene glycol monoethyl ether acetate,
Diethylene glycol monobutyl ether acetate,
Examples include triethylene glycol dimethyl ether and triethylene glycol monoethyl ether.

The non-alcoholic organic solvent in the film-forming solution of the present invention is not particularly limited as long as it has a boiling point of 85 ° C. or lower, and examples thereof include benzene, acetone, methyl ethyl ketone, tetrahydrofuran and methylene chloride.

The alcoholic solvent is not particularly limited, but for example, methanol, ethanol, propanol, butanol, pentanol, heptanol,
Hexanol and the like can be mentioned. The film-forming liquid in the present invention may further contain a swelling agent, a dispersant, a thickener, etc., if necessary.

The production method of the present invention includes the step of developing the film-forming solution as described above into a hollow or flat film form. That is, the shape of the membrane of the present invention is not particularly limited, and the membrane-forming solution is expanded into a hollow shape to form a hollow fiber membrane alone, or expanded into a hollow or flat membrane shape to obtain various shapes. It can be formed on the surface of a porous support. The porous support is not particularly limited, and examples thereof include flat plates and tubes of glass, metal, plastic, etc., or supports having a porous structure made of woven fabric, non-woven fabric and the like.

As a method of developing the film-forming solution, for example,
Casting is performed using a doctor knife, doctor plate, applicator, etc., or a method using a double-tube type spinning nozzle according to the spinning method of a hollow fiber membrane or a known tubular membrane forming method is performed. There is a method. 2
When forming a hollow fiber membrane using a heavy tube type spinning nozzle,
Coagulating liquid, gas, etc. are usually discharged during the development of the film-forming liquid.

The thickness at the time of developing the film-forming solution depends on the shape of the film, but the thickness of the obtained asymmetric film layer is 20 to 100 μm.
It is preferable that it is m.

The production method of the present invention includes a step of partially evaporating the solvent component from the surface of the developed film-forming solution. that time,
The highly volatile solvent preferentially evaporates, the concentration of the resin can be locally increased on the surface of the film-forming solution, and a skin layer suitable for gas separation can be finally obtained.

Evaporation can be carried out either at room temperature or under heating. When heating, for example, a method of allowing it to stay in a heated atmosphere, contacting it with warm air, or heating the film-forming solution can be mentioned. To be The evaporation time is preferably 0.5 to 600 seconds, more preferably 1 to 30 seconds. The evaporation atmosphere is
Any of air, dry air, nitrogen gas, inert gas, etc. may be used, but dry air is preferable in consideration of evaporation efficiency and cost.

The production method of the present invention includes a step of contacting a partially evaporated solvent component with a coagulating liquid to remove the solvent (solvent replacement). The contacting method may be a method of spraying a coagulating liquid, etc., but dipping in a coagulating liquid is usually performed. As a result, desolvation (solvent substitution) from the film-forming solution occurs, phase conversion (phase separation) occurs, and gelation of the fluorine-containing polyimide resin occurs.

The coagulating liquid used is not particularly limited as long as it does not dissolve the fluorine-containing polyimide resin and is compatible with the solvent in the polymer solution. Specifically, for example, water, alcohols such as ethanol, methanol, and inpropyl alcohol, and mixed solutions thereof are preferably used. The temperature of the coagulating liquid at the time of dipping is not particularly limited, but it is preferably performed at a temperature of 0 to 50 ° C.

The production method of the present invention may include a defoaming step of the film-forming solution, a film washing step, a drying step, an aging step and the like in addition to the above steps.

The gas separation membrane of the present invention can be obtained by the above-mentioned production method, and fluorine having a projected cross-sectional maximum width of the cubic structure of the repeating unit molecular chain determined by the molecular orbital method is 10 Å or more. It is a gas separation membrane for acidic gas selective separation which has an asymmetric membrane layer of a containing polyimide resin.

The gas separation membrane of the present invention preferably has a carbon dioxide permeation rate of 0.1 to 0.1 according to the measuring method of Examples.
It is 5.0 [Nm ³ (STP) / m ² hatm] and the separation coefficient of carbon dioxide and nitrogen is 25 to 80.

[0041]

EXAMPLES Examples and the like specifically showing the constitution and effects of the present invention will be described below.

Example 1 0.0761 mol of 5,5'-2,2,2-trifluoro-1- (trifluoromethyl) ethylidene-bis-1,3-isobenzofurandione (6FDA) and 1,5
-Naphthalenediamine (1,5-ND) 0.0761m
and N-methyl-2-pyrrolidone (N
MP) was added, and the mixture was stirred at room temperature under a nitrogen atmosphere and stirred to prepare a polyamic acid solution. At this time, the polyamic acid solution was 15 wt% of polyamic acid. Next, 0.305 mol of acetic anhydride was added to this polyamic acid solution together with a small amount of pyridine, and the mixture was stirred at room temperature under a nitrogen atmosphere,
An imidization reaction was performed. After the reaction is complete, cool to room temperature,
The polymerization solution was dropped into an excess amount of water under high speed stirring to precipitate and purify. Further, it was purified with methanol to obtain a fluorine-containing polyimide resin composed of a repeating molecular structural unit represented by the following formula (Formula 8).

[0043]

[Chemical 8] Next, 18 parts by weight of this fluorine-containing polyimide resin was added to diethylene glycol dimethyl ether (boiling point: 162 ° C.).
64 parts by weight, 10 parts by weight of tetrahydrofuran (boiling point: 65 ° C.) and 8 parts by weight of n-butanol were added, and the mixture was stirred for 6 hours at room temperature under a nitrogen gas atmosphere and dissolved. Then, it filtered, left still and deaerated sufficiently, and it was set as the polymer solution for film forming. next,
This polymer solution was passed through the outer tube of a cylindrical double-tube spinning nozzle (inner tube diameter 0.35 mm, outer tube diameter 1.0 mm) from 2 to 2.
Discharge at a flow rate of 5 ml / min, and at the same time add pure water from the inner tube to 1
Discharged at a flow rate of ~ 1.5 ml / min. A hollow fiber membrane made of a fluorine-containing polyimide is formed by exposing each discharge liquid to air at a temperature of about 25 ° C. and a humidity of RH of about 35% for 3 seconds and then immersing it in pure water at 20 ° C. for gelation. Got Thoroughly wash this membrane with pure water, and then in air at 80 ° C for 2
By heating for 0 hour, a dry hollow fiber membrane having an inner diameter of 0.3 to 0.4 mm and an outer diameter of 0.5 to 0.6 mm was obtained.

Next, the MOPA of a commercially available semi-empirical molecular orbital method program (MOPAC series manufactured by Fujitsu Ltd.)
The steric structure of the repeating unit molecular chain of the fluorine-containing polyimide resin represented by the formula (Formula 8) was determined by the CAM1 method, and the maximum width of the projected cross section was determined to be 11Å.

Next, with respect to the obtained membrane, carbon dioxide 50 mol% / nitrogen 50 at 25 ° C. and a supply pressure of 1 atm.
The results of evaluating the separation performance and the permeation performance of the mol% mixed gas are summarized in Table 1 below.

Example 2 In the same manner as in Example 1 except that α, α′-bis (4-aminophenyl) -1,4-diisopropylbenzene was used in place of 1,5-naphthalenediamine, the following formula A dry hollow fiber membrane made of a fluorine-containing polyimide resin having a repeating unit structure of 9) was obtained.

[0047]

[Chemical 9] Next, in the same manner as in Example 1, the three-dimensional structure of the repeating unit molecular chain of the fluorine-containing polyimide resin represented by the formula (Formula 9) was obtained, and the maximum width of the projected cross section was obtained.
It was Å. Carbon dioxide of this hollow fiber membrane 50 mol% /
The results of evaluation of the separation performance and permeation performance of a mixed gas of 50 mol% nitrogen in the same manner as in Example 1 are shown later in Table 1.

Comparative Example 1 In Example 1, as a solvent for the fluorine-containing polyimide resin, N-methyl-2-pyrrolidone (boiling point 202 ° C.) was used instead of diethylene glycol dimethyl ether.
A hollow fiber membrane made of a fluorine-containing polyimide resin was obtained in the same manner as in Example 1 except that parts by weight were used. About the obtained hollow fiber membrane, in the same manner as in Example 1, carbon dioxide 50mo
The results of evaluating the separation performance and the permeation performance of the 1% / nitrogen 50 mol% mixed gas are summarized in Table 1 below.

Comparative Example 2 A fluorine-containing polyimide resin was prepared in the same manner as in Example 2 except that 72 parts by weight of tetrahydrofuran was added to 18 parts by weight of the fluorine-containing polyimide resin to prepare a film-forming solution. A hollow fiber membrane was obtained. About the obtained hollow fiber membrane, in the same manner as in Example 1, carbon dioxide 50 m
The results of evaluating the separation performance and the permeation performance of the ol% / nitrogen 50 mol% mixed gas are summarized in Table 1 below.

Comparative Example 3 In the same manner as in Example 1 except that 30 parts by weight of diethylene glycol dimethyl ether and 70 parts by weight of tetrahydrofuran were added to 18 parts by weight of the fluorine-containing polyimide resin to prepare a film-forming solution. A hollow fiber membrane made of a fluorine-containing polyimide resin was obtained. About the obtained hollow fiber membrane, as in Example 1, carbon dioxide 50 mol
The results of evaluating the separation performance and the permeation performance of the 50% / nitrogen 50 mol% mixed gas are collectively shown in Table 1 below.

[0051]

[Table 1] PCO ₂ at 25 ° C. and 1 atm, carbon dioxide 50 mo
Permeation rate of carbon dioxide [Nm ³ (STP) / m ² hatm] when 1% / 50 mol% nitrogen gas is supplied
Is. α (CO ₂ / N ₂ ) at 25 ° C, latm,
It is a separation coefficient [-] of carbon dioxide and nitrogen when a mixed gas of 50 mol% carbon dioxide / 50 mol% nitrogen is supplied.

As shown in Table 1, the products of Examples of the present invention are
It was confirmed that it has a high selectivity (separation coefficient) and high permeability for carbon dioxide as compared with the comparative example product, and is excellent as an acidic gas separation membrane.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4D006 GA41 MA01 MA03 MA25 MA30                       MA40 MB04 MC58X MC79X                       MC81 NA04 NA10 NA16 NA50                       NA52 NA62 PB18 PB19 PB64                 4J043 PA02 PC145 PC146 QB15                       QB26 QB31 RA02 RA04 RA35                       SA06 SA47 SB01 SB02 SB03                       SB04 SB05 TA22 TA71 TB01                       UA131 UA132 UA151 UA261                       UA672 UB011 UB062 UB131                       UB301 UB401 VA011 ZB13

Claims (4)

[Claims] 1. A glycol-based solvent having a fluorine-containing polyimide resin content of 3 to 40% by weight and a boiling point of 120 ° C. or higher.
95% by weight, 1 to 40% by weight of a non-alcoholic organic solvent having a boiling point of 85 ° C. or less, and an alcoholic solvent 1 to 40
Performing a step of developing a film-forming solution containing 1% by weight into a hollow or flat film, a step of partially evaporating a solvent component from the surface of the film-forming solution, and contacting this with a coagulating solution to desolvate A method of manufacturing a gas separation membrane, the method including: 2. The fluorine-containing polyimide resin has a projected cross-sectional maximum width of a cubic structure of repeating unit molecular chains determined by a molecular orbital method of 10 Å or more, and the obtained gas separation membrane is for selective separation of acidic gas. A method for producing a gas separation membrane according to claim 1. 3. A fluorine-containing polyimide resin which can be obtained by the method for producing a gas separation membrane according to claim 1, and has a projected cross-sectional maximum width of 10 Å or more of a three-dimensional structure of a repeating unit molecular chain obtained by a molecular orbital method. A gas separation membrane for selective separation of acidic gas having an asymmetric membrane layer. 4. The fluorine-containing polyimide resin has a repeating unit represented by the following general formula (I).
A gas separation membrane for selective separation of acidic gas as described. [Chemical 1] (In the formula, R represents any of the following divalent organic groups.)