JP2015160167A - Gas separation membrane, gas separation module, gas separator, and gas separation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas separation membrane excellent in both gas permeability and gas separation selectivity, hard to have gas separation capability dropped even if used under a high pressure condition, and hard to receive the influence of an impurity component such as toluene existing in a natural gas, and a gas separation module, a gas separator, and a gas separation method using that gas separation membrane.SOLUTION: Provided are: a gas separation membrane having a gas separation layer containing a polyimide compound, where said polyimide compound contains a carbamoyl group and the polyimide compound contains the carbamoyl group in 0.1 to 3.0 mmol/g; and a gas separation module, a gas separator, and a gas separation method using that gas separation membrane.

Description

  The present invention relates to a gas separation membrane, a gas separation module, a gas separation device, and a gas separation method.

  A material made of a polymer compound has a gas permeability unique to each material. Based on the property, a desired gas component can be selectively permeated and separated by a membrane composed of a specific polymer compound. As an industrial utilization mode of this gas separation membrane, it is considered to separate and recover it from a large-scale carbon dioxide generation source in a thermal power plant, a cement plant, a steelworks blast furnace, etc. in connection with the problem of global warming. Has been. And this membrane separation technique attracts attention as a means for solving environmental problems that can be achieved with relatively small energy. On the other hand, natural gas and biogas (gas generated by fermentation and anaerobic digestion of biological waste, organic fertilizer, biodegradable substances, sewage, garbage, energy crops, etc.) are mainly mixed gases containing methane and carbon dioxide. A membrane separation method has been studied as a means for removing impurities such as carbon dioxide (Patent Document 1).

In the purification of natural gas using a membrane separation method, excellent gas permeability and separation selectivity are required in order to separate gases more efficiently. In order to realize this, various membrane materials have been studied. As a specific example, a gas separation membrane using a polyimide compound has been studied. For example, Non-Patent Document 1 describes that the separation selectivity of the gas separation membrane is improved by using a polyimide compound into which a polar group such as a carboxy group or a hydroxyl group is introduced.
In an actual plant, the membrane is plasticized due to the influence of high-pressure conditions and impurities (for example, benzene, toluene, xylene) present in natural gas, resulting in a problem of lowering separation selectivity. In order to suppress plasticization of this film, it is known that it is effective to introduce a crosslinked structure or a branched structure into the polyimide compound constituting the film (for example, Patent Documents 2 to 7).

In order to obtain a practical gas separation membrane, not only gas separation selectivity but also a sufficient gas permeability must be ensured by making the gas separation layer thin. As a technique for this, there is a method in which a polymer compound such as a polyimide compound is formed into an asymmetric membrane by a phase separation method so that a portion contributing to the separation is made into a thin layer called a dense layer or a skin layer. In this asymmetric membrane, the dense layer serves as a gas separation layer, and the portion other than the dense layer functions as a support layer that bears the mechanical strength of the membrane.
In addition to the asymmetric membrane, a composite membrane is also known in which a material responsible for gas separation and a material responsible for mechanical strength are separated. This composite membrane has a structure in which a thin gas separation layer made of a polymer compound such as polyimide is formed on a gas permeable support having mechanical strength.

JP 2007-297605 A JP 2013-188742 A JP2013-169485A JP 2013-046904 A JP 2013-046903 A JP 2013-046902 A JP 2013-027819 A

Journal of Membrane Science 2003, 211, p41-49

As described above, even when the gas separation layer is thinned to improve gas permeability, it is not easy to achieve both gas permeability and gas separation selectivity at a high level. Gas permeability or gas separation selectivity can be adjusted by adjusting the copolymer component of the polymer compound that constitutes the gas separation layer, but both are in a trade-off relationship, and both are compatible at a higher level. For this purpose, it is necessary to further improve the material of the gas separation layer itself.

  The present invention is a gas separation membrane having both good gas permeability and gas separation selectivity, and the gas separation performance hardly deteriorates even when used under high-pressure conditions. Moreover, such as toluene present in natural gas. It is an object of the present invention to provide a gas separation membrane that is hardly affected by impurity components. Another object of the present invention is to provide a gas separation module, a gas separation device, and a gas separation method using the gas separation membrane.

  The present inventors have made extensive studies in view of the above problems. As a result, by forming a gas separation layer using a polyimide compound containing a specific amount of carbamoyl groups, both gas permeability and gas separation selectivity are excellent, and gas separation is possible even when used under high pressure conditions. It has been found that a gas separation membrane is obtained that is less likely to deteriorate in performance and that is highly resistant to impurity components such as toluene. The present invention has been completed based on these findings.

The above problems have been achieved by the following means.
[1]
A gas separation membrane having a gas separation layer containing a polyimide compound,
The gas separation membrane in which the polyimide compound has a carbamoyl group, and the content of the carbamoyl group in the polyimide compound is 0.1 to 3.0 mmol / g.
[2]
The gas separation membrane according to [1], wherein the polyimide compound includes a repeating unit represented by the following formula (A) or (B).

In the formula (A), R represents a group having a structure represented by any of the following formulas (I-1) to (I-28). Here, X ^{1 to} X ³ represent a single bond or a divalent linking group, L represents —CH═CH— or —CH ₂ —, R ¹ and R ² represent a hydrogen atom or a substituent, and * represents a formula ( A binding site with the carbonyl group in A) is shown. R ⁴ represents a substituent, and l1 represents an integer of 1 to 4. When l1 is 1, R ⁴ is a group having a carbamoyl group. When l1 is 2 to ⁴ , at least one of R ⁴ is a group having a carbamoyl group.

In formula (B), R has the same meaning as R in formula (A). R ⁵ and R ⁶ represent a substituent. m1 and n1 are integers of 0 to 4, but neither m1 nor n1 is 0. When m1 is 0, at least one of R ⁶ is a group having a carbamoyl group, and when n1 is 0, at least one of R ⁵ is a group having a carbamoyl group. When m1 and n1 are both 1 or more, at least one of R ⁵ and R ⁶ is a group having a carbamoyl group. X ⁴ represents a single bond or a divalent linking group.

[3]
The gas separation membrane according to [2], wherein the repeating unit represented by the formula (A) is a repeating unit represented by the following formula (a):

In formula (a), R has the same meaning as R in formula (A). R ^4a is a hydrogen atom or a substituent having no carbamoyl group.
[4]
The gas separation membrane according to any one of [1] to [3], wherein the gas separation membrane is a gas separation composite membrane having the gas separation layer on the gas permeable support layer.
[5]
The gas separation membrane according to [4], wherein the support layer includes a porous layer on the gas separation layer side and a nonwoven fabric layer on the opposite side.
[6]
In the case where the gas to be separated is a mixed gas of carbon dioxide and methane, the permeation rate of carbon dioxide at 40 ° C. and 5 MPa exceeds 20 GPU, and the permeation rate ratio of carbon dioxide and methane (R _CO2 / R _CH4 ) Is a gas separation membrane according to any one of [1] to [5].
[7]
The gas separation membrane according to any one of [1] to [6], which is used for selectively transmitting carbon dioxide from a gas containing carbon dioxide and methane.
[8]
[1] A gas separation module comprising the gas separation membrane according to any one of [7].
[9]
[8] A gas separation device comprising the gas separation module according to [8].
[10]
A gas separation method for selectively permeating carbon dioxide from a gas containing carbon dioxide and methane, using the gas separation membrane according to any one of [1] to [7].

  In the present specification, when there are a plurality of substituents, linking groups, and the like (hereinafter referred to as substituents) indicated by specific symbols, or when a plurality of substituents are specified simultaneously or alternatively, It means that a substituent etc. may mutually be same or different. The same applies to the definition of the number of substituents and the like. Further, when there are repetitions of a plurality of partial structures represented by the same indication in the formula, each partial structure or repeating unit may be the same or different. Further, even if not specifically stated, when a plurality of substituents and the like are close (particularly adjacent), they may be connected to each other or condensed to form a ring.

In this specification, about the display of a compound, it uses in the meaning containing its salt and its ion besides the compound itself. In addition, it is meant to include derivatives in which a part of the structure is changed within the range where the desired effect is achieved.
In the present specification, a substituent that does not specify substitution / non-substitution (the same applies to a linking group) means that the group may have an arbitrary substituent as long as a desired effect is achieved. . This is also synonymous for compounds that do not specify substitution / non-substitution.
In the present specification, the substituent group Z is a preferred range unless otherwise specified.

  The gas separation membrane, gas separation module, and gas separation apparatus of the present invention have excellent gas permeability and high gas separation performance. Further, even when used under high pressure conditions or for separation of a gas containing an impurity component such as toluene, the gas separation performance is hardly lowered.

  According to the gas separation method of the present invention, gas can be separated with higher permeability and higher selectivity. Furthermore, even if the gas is separated under high pressure conditions or impurities are present in the gas, high gas separation performance is maintained.

It is sectional drawing which shows typically one Embodiment of the gas separation composite membrane of this invention. It is sectional drawing which shows typically another embodiment of the gas separation composite membrane of this invention.

Hereinafter, the present invention will be described in detail.
The gas separation membrane of the present invention includes a gas separation layer containing a specific amount of a polyimide compound having a carbamoyl group.

[Polyimide compound]
The polyimide compound used in the present invention contains a carbamoyl group (—C (═O) NH ₂ ) in its structure. The content of the carbamoyl group in the polyimide compound used in the present invention is 0.1 to 3.0 mmol / g. If the content of the carbamoyl group in the polyimide compound is less than 0.1 mmol / g, the polyimide compound cannot be imparted with sufficient polarity, and as a result, the interaction between the polyimide molecular chains is weak, and the polyimide film is sufficient. Therefore, it is difficult to obtain a desired gas separation performance because the aggregation of polyimide molecules due to the interaction between polyimide molecular chains is not sufficiently dense. Moreover, when there is more content of carbamoyl group in a polyimide compound than 3.0 mmol / g, the interaction between polyimide compounds will become strong too much, the solubility with respect to a solvent will fall, and it will become difficult to form into a film. Even when the film can be formed, sufficient gas permeability may not be exhibited. The content of the carbamoyl group in the polyimide compound used in the present invention is preferably 0.2 to 2.5 mmol / g, more preferably 0.3 to 2.0 mmol / g, More preferably, it is 1.5 mmol / g.

  There is no restriction | limiting in particular in the structure which has a carbamoyl group in the polyimide compound used for this invention. Specifically, when the polyimide compound is synthesized by a polycondensation reaction between a tetracarboxylic dianhydride and a diamine compound as described later, the tetracarboxylic dianhydride component may have a carbamoyl group. The diamine component may have a carbamoyl group, or both the tetracarboxylic dianhydride component and the diamine component may have a carbamoyl group.

  The polyimide compound used in the present invention preferably contains at least a repeating unit represented by the following formula (A) or (B).

  In the formula (A), R represents a group having a structure represented by any of the following formulas (I-1) to (I-28). In the following formulas (I-1) to (I-28), * represents a binding site with the carbonyl group of the formula (A). R in the formula (A) may be referred to as a mother nucleus, and the mother nucleus R is preferably a group represented by the formula (I-1), (I-2) or (I-4), The group represented by (I-1) or (I-4) is more preferred, and the group represented by (I-1) is particularly preferred.

In the above formulas (I-1), (I-9) and (I-18), X ^{1 to} X ³ represent a single bond or a divalent linking group. As the divalent linking group, —C (R ^x ) ₂ — (R ^x represents a hydrogen atom or a substituent. When R ^x is a substituent, they may be linked to each other to form a ring), —O—, —SO ₂ —, —C (═O) —, —S—, —NR ^Y — (R ^Y is a hydrogen atom, an alkyl group (preferably a methyl group or an ethyl group) or an aryl group (preferably phenyl). _{group)), - C 6 H 4} - ( phenylene group), or a combination thereof, more preferably a single bond or -C ^(R _{x) 2} - are more preferable. When R ^x represents a substituent, specific examples thereof include the substituent group Z described below, and an alkyl group (preferably the same as the alkyl group shown in the substituent group Z described below) is preferable. An alkyl group having a halogen atom as a substituent is more preferable, and trifluoromethyl is particularly preferable. In the present specification, when “may be linked to each other to form a ring”, it may be bonded by a single bond, a double bond or the like to form a cyclic structure, It may form a condensed ring structure. In formula (I-18), X ³ is linked to either one of the two carbon atoms described on the left side thereof and one of the two carbon atoms described on the right side thereof. Means that

In the above formulas (I-4), (I-15), (I-17), (I-20), (I-21) and (I-23), L is —CH═CH— or —CH _2. -Is shown.

In said formula (I-7), R < ¹ >, R < ² > shows a hydrogen atom or a substituent. Examples of the substituent include groups listed in the substituent group Z described later. R ¹ and R ² may be bonded to each other to form a ring.

R ¹ and R ² are preferably a hydrogen atom or an alkyl group, more preferably a hydrogen atom, a methyl group or an ethyl group, and even more preferably a hydrogen atom.

  The carbon atoms shown in the formulas (I-1) to (I-28) may further have a substituent. Specific examples of this substituent include the substituent group Z described later, and among them, an alkyl group or an aryl group is preferable.

In the above formula (A), ^{R 4} represents a substituent, l1 is an integer of 1-4. When l1 is 1, R ⁴ is a group having a carbamoyl group (—C (═O) NH ₂ ). When l1 is 2 to ⁴ , at least one of R ⁴ is a group having a carbamoyl group, and one or two of R ⁴ are preferably groups having a carbamoyl group. When R ⁴ is a substituent that does not have a carbamoyl group, specific examples of this substituent include the substituent group Z described later. Among them, an alkyl group (more preferably having 1 to 10 carbon atoms, more preferably An alkyl group having 1 to 5 carbon atoms, more preferably ethyl or methyl), a halogen atom, an alkoxy group (preferably 1 to 10 carbon atoms, more preferably an alkoxy group having 1 to 5 carbon atoms), or an aromatic group (preferably Is an aromatic group having 3 to 20 carbon atoms, more preferably an aromatic heterocyclic group having 3 to 20 carbon atoms (preferably containing a nitrogen atom as a ring constituent atom), and further preferably an aromatic hetero group having 4 to 15 carbon atoms. A ring group (preferably containing a nitrogen atom as a ring constituent atom) is preferred.
In the present specification, the “group having a carbamoyl group” is not particularly limited as long as it has a carbamoyl group, but is preferably a carbamoyl group or a carbamoylalkyl group (preferably having 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms). Carbamoylalkyl group, more preferably carbamoylethyl or carbamoylmethyl, more preferably carbamoylmethyl), among which carbamoyl group or carbamoylmethyl is preferable.

  The repeating unit represented by the above formula (A) is preferably a repeating unit represented by the following formula (a).

In formula (a), R has the same meaning as R in formula (A), and the preferred form is also the same. R ^4a is a hydrogen atom or a substituent having no carbamoyl group. Specific examples of the substituent having no carbamoyl group include the substituent group Z described below, and among them, an alkyl group (more preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 5 carbon atoms, More preferably ethyl or methyl), a halogen atom, an alkoxy group (preferably an alkoxy group having 1 to 10 carbon atoms, more preferably an alkoxy group having 1 to 5 carbon atoms), or an aromatic group (preferably an aromatic group having 3 to 20 carbon atoms). Group, more preferably an aromatic heterocyclic group having 3 to 20 carbon atoms (preferably containing a nitrogen atom as a ring constituent atom), more preferably an aromatic heterocyclic group having 4 to 15 carbon atoms (preferably an aromatic heterocyclic group having a ring constituent atom). Nitrogen atoms are preferred)). Among them, a form in which all of R ^4a are hydrogen atoms, a form in which all of R ^4a are halogen atoms, and two R ^4a located in the ortho position relative to the carbamoyl group are hydrogen atoms and are located in the para position. R ^4a is an alkyl group (more preferably having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 5 carbon atoms, more preferably ethyl or methyl), an alkoxy group (preferably having 1 to 10 carbon atoms, more preferably carbon. An alkoxy group having 1 to 5 carbon atoms) or an aromatic group (preferably an aromatic group having 3 to 20 carbon atoms, more preferably an aromatic heterocyclic group having 3 to 20 carbon atoms (preferably a nitrogen atom as a ring constituent atom). including), still preferably located ortho to it form, a carbamoyl group which aromatic Hajime Tamaki having 4 to 15 carbon atoms (preferably containing a nitrogen atom in the ring constituting atom)) R one of ^a are hydrogen atom, the remaining two R ^4a is an alkoxy group (preferably having from 1 to 10 carbon atoms, more preferably an alkoxy group having 1 to 5 carbon atoms), or an aromatic group (preferably 3 carbon atoms -20 aromatic group, more preferably an aromatic heterocyclic group having 3 to 20 carbon atoms (preferably containing a nitrogen atom in the ring constituent atoms), more preferably an aromatic heterocyclic group having 4 to 15 carbon atoms (preferably Is preferably a form in which a ring atom contains a nitrogen atom))).

In formula (B), R has the same meaning as R in formula (A). R ⁵ and R ⁶ represent a substituent. m1 and n1 are both integers of 0 to 4, but neither m1 nor n1 is 0.

When m1 is 0, at least one of R ⁶ is a group having a carbamoyl group. That is, when m1 is 0, when n1 is 1, R ⁶ is a group having a carbamoyl group, and when n1 is 2, one or two of R ⁶ is a group having a carbamoyl group, When n1 is 3, one, two or three of R ⁶ are groups having a carbamoyl group, and when n1 is 4, one, two, three or four of R ⁶ are carbamoyl. A group having a group. When m1 is 0, n1 is preferably 1.

When n1 is 0, at least one of R ⁵ is a group having a carbamoyl group. That is, when n1 is 0, when m1 is 1, R ⁵ is a group having a carbamoyl group, and when m1 is 2, one or two of R ⁵ is a group having a carbamoyl group, When m1 is 3, one, two or three of R ⁵ are groups having a carbamoyl group, and when m1 is 4, one, two, three or four of R ⁵ are carbamoyl. A group having a group. When n1 is 0, m1 is preferably 1.
When m1 and n1 are both 1 or more, at least one of R ⁵ and R ⁶ is a group having a carbamoyl group. Here, “at least one of R ⁵ and R ⁶ is a group having a carbamoyl group” means that at least one of R ⁵ is a group having a carbamoyl group and not all of R ⁶ have a carbamoyl group , And at least one of R ⁶ is a group having a carbamoyl group, and all of R ⁵ are used to include an embodiment having no carbamoyl group. When m1 and n1 are both 1 or more, it is preferable that at least one of R ⁵ is a group having a carbamoyl group and at least one of R ⁶ is a group having a carbamoyl group. Among these, it is preferable that m1 and n1 are both 1, and R ⁵ and R ⁶ are both groups having a carbamoyl group.

When R ⁵ and R ⁶ are not a group having a carbamoyl group, specific examples of the substituent that can be adopted by R ⁵ and R ⁶ include the substituent group Z described later, and among them, an alkyl group (more preferably a carbon number). 1 to 10, more preferably an alkyl group having 1 to 5 carbon atoms, more preferably ethyl or methyl) or a halogen atom.

In the formula (B), ^{X 4} has the same meaning as ^{X 1} in the formula (I-1), the same also preferable.
The polyimide compound used in the present invention may contain a repeating unit represented by the following formula (C) or (D).

In said formula (C) and (D), R is synonymous with R in formula (A), and its preferable form is also the same. R < ⁷ > -R < ⁹ > shows a substituent. Examples of the substituent include a substituent group Z described later.
In the above formula (C), R ⁷ is preferably an alkyl group, a halogen atom, a carboxy group or a hydroxy group. Although p2 that indicates the number of R ⁷ is an integer of 0 to 4, preferably 1 to 4, more preferably 2 to 4, more preferably 3 or 4. When R ⁷ is alkyl, the alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 5, more preferably 1 to 3, and still more preferably methyl or ethyl. Or trifluoromethyl.
In the formula (C), it is preferable that the two linking sites for incorporation into the polyimide compound of the diamine component (that is, the phenylene group that may have R ⁷ ) are located at the meta position or the para position.
In the present invention, the structure represented by the formula (C) does not include the structure represented by the formula (A) (that is, the structure represented by the formula (C) is a carbamoyl group. Do not have).

In the above formula (D), R ⁸ and R ⁹ preferably represent an alkyl group or a halogen atom, or are groups that are linked together to form a ring together with X ⁴ . Further, a form in which two R ⁸ are connected to form a ring and a form in which two R ⁹ are connected to form a ring are also preferred. The structure in which R ⁸ and R ⁹ are linked is not particularly limited, but a single bond, —O— or —S— is preferable. Q2 and r2 indicating the number of R ⁸ and R ⁹ are integers of 0 to 4, preferably 0 to 3, and more preferably 0 to 2. When R ⁸ and R ⁹ are alkyl groups, the alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 5, more preferably 1 to 3, and still more preferably. Is methyl, ethyl or trifluoromethyl.

In the above formula (D), ^{X 4} has the same meaning as ^{X 1} in the formula (I-1), the same also preferable.

  In the present invention, the structure represented by the formula (D) does not include the structure represented by the formula (B) (that is, the structure represented by the formula (D) is a carbamoyl group. )

Substituent group Z:
An alkyl group (preferably an alkyl group having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 10 carbon atoms, such as methyl, ethyl, iso-propyl, tert-butyl, n-octyl , N-decyl, n-hexadecyl), a cycloalkyl group (preferably a cycloalkyl group having 3 to 30 carbon atoms, more preferably 3 to 20 carbon atoms, particularly preferably 3 to 10 carbon atoms, such as cyclopropyl, Cyclopentyl, cyclohexyl, etc.), an alkenyl group (preferably an alkenyl group having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, such as vinyl, allyl, 2 -Butenyl, 3-pentenyl, etc.), alkynyl group (preferably having 2 to 30 carbon atoms, more preferably An alkynyl group having 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, such as propargyl and 3-pentynyl, and an aryl group (preferably having 6 to 30 carbon atoms, more preferably 6 carbon atoms). To 20 and particularly preferably an aryl group having 6 to 12 carbon atoms, such as phenyl, p-methylphenyl, naphthyl, anthranyl, etc.), amino group (amino group, alkylamino group, arylamino group, hetero A cyclic amino group, preferably an amino group having 0 to 30 carbon atoms, more preferably 0 to 20 carbon atoms, particularly preferably 0 to 10 carbon atoms, such as amino, methylamino, dimethylamino, diethylamino, dibenzyl Amino, diphenylamino, ditolylamino, etc.), alkoxy groups (preferably having 1 carbon atom) 30, more preferably an alkoxy group having 1 to 20 carbon atoms, particularly preferably 1 to 10 carbon atoms, such as methoxy, ethoxy, butoxy, 2-ethylhexyloxy, etc.), an aryloxy group (preferably An aryloxy group having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and particularly preferably 6 to 12 carbon atoms, and examples thereof include phenyloxy, 1-naphthyloxy, 2-naphthyloxy, and the like. Heterocyclic oxy group (preferably a heterocyclic oxy group having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include pyridyloxy, pyrazyloxy, pyrimidyloxy, quinolyloxy and the like. ),

  An acyl group (preferably an acyl group having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include acetyl, benzoyl, formyl, pivaloyl, etc.), alkoxy A carbonyl group (preferably an alkoxycarbonyl group having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonyl and ethoxycarbonyl), aryloxy A carbonyl group (preferably an aryloxycarbonyl group having 7 to 30 carbon atoms, more preferably 7 to 20 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonyl), an acyloxy group ( Preferably 2-30 carbons, more preferably 2-20 carbons, especially preferred. Or an acyloxy group having 2 to 10 carbon atoms such as acetoxy and benzoyloxy), an acylamino group (preferably having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, and particularly preferably carbon number). 2-10 acylamino groups such as acetylamino and benzoylamino).

  An alkoxycarbonylamino group (preferably an alkoxycarbonylamino group having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonylamino), aryl Oxycarbonylamino group (preferably an aryloxycarbonylamino group having 7 to 30 carbon atoms, more preferably 7 to 20 carbon atoms, particularly preferably 7 to 12 carbon atoms, and examples thereof include phenyloxycarbonylamino group). A sulfonylamino group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methanesulfonylamino and benzenesulfonylamino), a sulfamoyl group (Preferably 0 to 30 carbon atoms, more preferably 0 to 20 carbon atoms, particularly preferably a sulfamoyl group having 0 to 12 carbon atoms, for example sulfamoyl, methylsulfamoyl, dimethylsulfamoyl, and the like phenylsulfamoyl.),

  An alkylthio group (preferably an alkylthio group having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methylthio and ethylthio), an arylthio group (preferably An arylthio group having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenylthio, and a heterocyclic thio group (preferably having 1 to 30 carbon atoms). More preferably a heterocyclic thio group having 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as pyridylthio, 2-benzimidazolylthio, 2-benzoxazolylthio, 2-benzthiazolylthio and the like. ),

  A sulfonyl group (preferably a sulfonyl group having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as mesyl and tosyl), a sulfinyl group (preferably A sulfinyl group having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and particularly preferably 1 to 12 carbon atoms, such as methanesulfinyl, benzenesulfinyl, and the like, and a ureido group (preferably 1 carbon atom). -30, more preferably a ureido group having 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as ureido, methylureido, phenylureido, etc.), phosphoric acid amide group (preferably having carbon number) 1 to 30, more preferably a phosphoric acid amide group having 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms. Diethyl phosphate amide, phenyl phosphate amide, etc.), hydroxy group, mercapto group, halogen atom (for example, fluorine atom, chlorine atom, bromine atom, iodine atom, more preferably fluorine atom) ,

A cyano group, a sulfo group, a carboxy group, an oxo group, a nitro group, a hydroxamic acid group, a sulfino group, a hydrazino group, an imino group, a heterocyclic group (preferably a 3- to 7-membered heterocyclic group, even an aromatic heterocyclic ring The heteroatom may be a non-aromatic heterocycle, and examples of the heteroatom constituting the heterocycle include a nitrogen atom, an oxygen atom and a sulfur atom, preferably 0 to 30 carbon atoms, more preferably 1 to 12 carbon atoms. Specific examples thereof include imidazolyl, pyridyl, quinolyl, furyl, thienyl, piperidyl, morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl, carbazolyl, azepinyl and the like, and a silyl group (preferably). Is a silyl group having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, and particularly preferably 3 to 24 carbon atoms. For example, trimethylsilyl, triphenylsilyl, etc.), a silyloxy group (preferably a silyloxy group having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms, Examples thereof include trimethylsilyloxy and triphenylsilyloxy). These substituents may be further substituted with any one or more substituents selected from the above substituent group Z.
In the present invention, when one structural site has a plurality of substituents, these substituents are connected to each other to form a ring, or condensed with a part or all of the above structural sites to form an aromatic group. A ring or an unsaturated heterocyclic ring may be formed.

When a compound or a substituent includes an alkyl group, an alkenyl group, etc., these may be linear or branched, and may be substituted or unsubstituted. When an aryl group, a heterocyclic group, or the like is included, they may be monocyclic or condensed, and may be substituted or unsubstituted.
In the present specification, what is merely described as a substituent refers to this substituent group Z unless otherwise specified, and when the name of each group is only described ( For example, when only “alkyl group” is described), preferred ranges and specific examples of the corresponding group in the substituent group Z are applied.

In the case where the polyimide compound used in the present invention contains a repeating unit represented by the above formula (A) or (B), the content of the repeating unit represented by the above formula (A) or (B) in the polyimide compound There is no particular limitation, and it is appropriately adjusted according to the purpose of gas separation (recovery rate, purity, etc.) in consideration of gas permeability and gas separation selectivity.
The polyimide compound used in the present invention has the formula (A) or (R) with respect to the sum (100 mol%) of the repeating units represented by the formulas (A), (B), (C) and (D). The total amount of the repeating unit represented by B) is preferably 5 mol% or more, more preferably 10 to 90 mol%, further preferably 20 to 80 mol%, more preferably 30 to 70 mol%. More preferably. If the repeating unit of formula (A) or (B) has a large number of carbamoyl groups, even if the amount of the repeating unit represented by formula (A) or (B) is reduced to some extent, the carbamoyl group in the polyimide compound The amount can be within the range defined by the present invention, and a desired effect can be obtained. The polyimide compound used in the present invention preferably has a structure in which all of the repeating units are represented by the formula (A), (B), (C) or (D).

  The molecular weight of the polyimide compound used in the present invention is preferably 10,000 to 1,000,000 as a weight average molecular weight, more preferably 15,000 to 500,000, and still more preferably 20,000 to 300,000. It is.

  In the present specification, unless otherwise specified, the molecular weight and the degree of dispersion are values measured using a GPC (gel filtration chromatography) method, and the molecular weight is a weight average molecular weight in terms of polystyrene. The gel packed in the column used in the GPC method is preferably a gel having an aromatic compound as a repeating unit, and examples thereof include a gel made of a styrene-divinylbenzene copolymer. It is preferable to use 2 to 6 columns connected together. Examples of the solvent used include ether solvents such as tetrahydrofuran and amide solvents such as N-methylpyrrolidinone. The measurement is preferably performed at a solvent flow rate in the range of 0.1 to 2 mL / min, and most preferably in the range of 0.5 to 1.5 mL / min. By performing the measurement within this range, the apparatus is not loaded and the measurement can be performed more efficiently. The measurement temperature is preferably 10 to 50 ° C, most preferably 20 to 40 ° C. Note that the column and carrier to be used can be appropriately selected according to the physical properties of the polymer compound that is symmetrical to the measurement.

(Synthesis of polyimide compounds)
The polyimide compound used in the present invention can be synthesized by condensation polymerization of a specific bifunctional acid anhydride (tetracarboxylic dianhydride) and a specific diamine. As the method, a general book (for example, Ikuo Imai, edited by Rikio Yokota, “Latest Polyimide: Fundamentals and Applications”, NTS Corporation, August 25, 2010, p. 3-49, Etc.) can be appropriately selected.
In the synthesis of the polyimide compound used in the present invention, one or both of a tetracarboxylic dianhydride and a diamine compound used as a raw material have a carbamoyl group.

  In the synthesis of the polyimide compound that can be used in the present invention, at least one tetracarboxylic dianhydride used as a raw material is preferably represented by the following formula (IV). It is preferable that all tetracarboxylic dianhydrides used as raw materials are represented by the following formula (IV).

  In formula (IV), R has the same meaning as R in formula (A).

  Specific examples of tetracarboxylic dianhydrides that can be used in the present invention include the following.

  In the synthesis | combination of the polyimide compound used for this invention, it is preferable that at least 1 sort (s) of the diamine compound used as a raw material is represented by a following formula (A-1) or (B-1).

Wherein (A-1), ^{R 4} and l1 are each the same meaning as ^{R 4} and l1 in the formula (A), a preferred form also the same.

  The diamine compound represented by the above formula (A-1) is preferably a compound represented by the following formula (a-1).

In formula (a-1), R ^4a has the same meaning as R ^4a in formula (a), and the preferred form is also the same.

Wherein ^{(B-1), R 5} , R 6, X 4, m1 and n1 are respectively synonymous with ^{R 5, R 6, X 4} , m1 and n1 in the formula (B), preferred forms are also the same It is.

  Specific examples of the diamine represented by the formula (A-1) or (B-1) include those shown below.

  Moreover, in the synthesis | combination of the polyimide compound which can be used for this invention, in addition to the diamine represented by the said Formula (A-1) or (B-1) as a diamine compound used as a raw material, following formula (C-1) or A diamine represented by (D-1) may be used.

In formula (C-1), R ⁷ and p2 have the same meanings as R ⁷ and p2 in formula (C), respectively, and have the same preferred forms. The diamine represented by the formula (C-1) does not include the diamine represented by the formula (A-1).

Wherein ^{(D-1), R 8} , R 9, X 4, q2 and r2 are respectively synonymous with ^{R 8, R 9, X 4} , q2 and r2 in formula (D), preferred embodiments are also the same It is. The diamine represented by the formula (D-1) does not include the diamine represented by the formula (B-1).

  As the diamine represented by the formula (C-1) or (D-1), for example, those shown below can be used.

  The polyimide compound used in the present invention may be any of a block copolymer, a random copolymer, and a graft copolymer.

The polyimide compound used in the present invention can be obtained by mixing each of the above raw materials in a solvent and subjecting it to condensation polymerization by an ordinary method.
The solvent is not particularly limited, but ester organic solvents such as methyl acetate, ethyl acetate, and butyl acetate; aliphatics such as acetone, methyl ethyl ketone, methyl isobutyl ketone, diacetone alcohol, cyclopentanone, and cyclohexanone. Ether organic solvents such as ketone, ethylene glycol dimethyl ether, dibutyl butyl ether, tetrahydrofuran, methylcyclopentyl ether, dioxane, amide organic solvents such as N-methylpyrrolidone, 2-pyrrolidone, dimethylformamide, dimethylimidazolidinone, dimethylacetamide, dimethyl And sulfur-containing organic solvents such as sulfoxide and sulfolane. These organic solvents are appropriately selected as long as it is possible to dissolve tetracarboxylic dianhydride as a reaction substrate, diamine compound, polyamic acid as a reaction intermediate, and polyimide compound as a final product. Preferably, ester type (preferably butyl acetate), aliphatic ketone (preferably methyl ethyl ketone, methyl isobutyl ketone, diacetone alcohol, cyclopentanone, cyclohexanone), ether type (diethylene glycol monomethyl ether, methyl cyclopentyl) Ether), an amide system (preferably N-methylpyrrolidone), and a sulfur-containing system (dimethyl sulfoxide, sulfolane) are preferable. Moreover, these can be used 1 type or in combination of 2 or more types.

  There is no restriction | limiting in particular in superposition | polymerization reaction temperature, The temperature which can be employ | adopted normally in the synthesis | combination of a polyimide compound is employable. Specifically, it is preferably −40 to 60 ° C., more preferably −30 to 50 ° C.

  A polyimide compound is obtained by imidizing the polyamic acid produced by the above polymerization reaction by a dehydration ring-closing reaction in the molecule. As a method of dehydrating and ring-closing, a general book (for example, Ikuo Imai, edited by Tsutsuo Yokota, “Latest Polyimide: Fundamentals and Applications”, NTS Corporation, August 25, 2010, p. 3) -49, etc.) can be referred to. For example, acetic anhydride or dicyclohexyl is heated in the presence of a basic catalyst such as pyridine, triethylamine, or DBU by heating to 120 ° C. to 200 ° C. for reaction while removing by-product water out of the system. A technique such as so-called chemical imidization using a dehydration condensing agent such as carbodiimide and triphenyl phosphite is preferably used.

  In the present invention, the total concentration of tetracarboxylic dianhydride and diamine compound in the polymerization reaction solution of the polyimide compound is not particularly limited, but is preferably 5 to 70% by mass, more preferably 5 to 50% by mass. Is preferable, and more preferably 5 to 30% by mass.

  Specific examples of the polyimide compound used in the present invention include those in which the molar ratio of each structural unit is appropriately changed in P-01 to P-17 and P-01 to P-17 described in Examples described later. However, the present invention is not limited to these, and a wide range of polyimide compounds satisfying the provisions of the present invention can be used.

[Gas separation membrane]
(Gas separation composite membrane)
In the gas separation composite membrane which is a preferred embodiment of the gas separation membrane of the present invention, a gas separation layer containing a specific polyimide compound is formed on the upper side of the gas permeable support layer. This composite membrane is applied to the above-mentioned coating solution (dope) forming the gas separation layer on at least the surface of the porous support (in this specification, coating is meant to include an aspect in which it is attached to the surface by dipping) )) Is preferable.
FIG. 1 is a longitudinal sectional view schematically showing a gas separation composite membrane 10 which is a preferred embodiment of the present invention. Reference numeral 1 denotes a gas separation layer, and reference numeral 2 denotes a support layer (gas permeable support layer) made of a porous layer. FIG. 2 is a cross-sectional view schematically showing a gas separation composite membrane 20 which is a preferred embodiment of the present invention. In this embodiment, a nonwoven fabric layer 3 is added as a support layer in addition to the gas separation layer 1 and the porous layer 2.

  In this specification, “upper support layer” means that another layer may be interposed between the support layer and the gas separation layer. As for the upper and lower expressions, unless otherwise specified, the direction in which the gas to be separated is supplied is “upper”, and the direction in which the separated gas is emitted is “lower”.

  In the gas separation composite membrane of the present invention, a gas separation layer may be formed and disposed on the surface or inner surface of a porous support (support layer). be able to. By forming a gas separation layer on at least the surface of the porous support, a composite membrane having the advantages of having both high separation selectivity, high gas permeability, and mechanical strength can be obtained. The thickness of the separation layer is preferably a thin film as much as possible under the condition of imparting high gas permeability while maintaining mechanical strength and separation selectivity.

  In the gas separation composite membrane of the present invention, the thickness of the gas separation layer is not particularly limited, but is preferably 0.01 to 5.0 μm, more preferably 0.05 to 2.0 μm.

The porous support (porous layer) preferably applied to the gas permeable support layer is not particularly limited as long as it has the purpose of meeting the provision of mechanical strength and high gas permeability. Either an inorganic material or an inorganic material may be used, but an organic polymer porous film is preferable, and the thickness thereof is 1 to 3000 μm, preferably 5 to 500 μm, and more preferably 5 to 150 μm. The pore structure of this porous membrane usually has an average pore diameter of 10 μm or less, preferably 0.5 μm or less, more preferably 0.2 μm or less. The porosity is preferably 20 to 90%, more preferably 30 to 80%. Further, the molecular weight cut-off of the porous layer is preferably 100,000 or less. Further, the gas permeability is preferably 3 × 10 ⁻⁵ cm ³ (STP) / cm ² · sec · cmHg (30 GPU) or more at 40 ° C. and 4 MPa, and 100 GPU or more. Is more preferable, and 200 GPU or more is more preferable. Examples of porous membrane materials include conventionally known polymers such as polyolefin resins such as polyethylene and polypropylene, fluorine-containing resins such as polytetrafluoroethylene, polyvinyl fluoride, and polyvinylidene fluoride, polystyrene, cellulose acetate, and polyurethane. And various resins such as polyacrylonitrile, polyphenylene oxide, polysulfone, polyethersulfone, polyimide, and polyaramid. The shape of the porous membrane may be any shape such as a flat plate shape, a spiral shape, a tubular shape, and a hollow fiber shape.

  In the gas separation composite membrane of the present invention, it is preferable that a support is formed to further impart mechanical strength to the lower portion of the support layer forming the gas separation layer. Examples of such a support include woven fabric, non-woven fabric, and net, but a non-woven fabric is preferably used from the viewpoint of film forming property and cost. As the nonwoven fabric, fibers made of polyester, polypropylene, polyacrylonitrile, polyethylene, polyamide or the like may be used alone or in combination. The nonwoven fabric can be produced, for example, by making a main fiber and a binder fiber uniformly dispersed in water using a circular net or a long net, and drying with a dryer. Moreover, it is also preferable to apply a heat treatment by sandwiching a non-woven fabric between two rolls for the purpose of removing fluff and improving mechanical properties.

<Method for producing gas separation composite membrane>
The production method of the composite membrane of the present invention is preferably a production method including forming a gas separation layer by applying a coating solution containing the polyimide compound on a support. Although content of the polyimide compound in a coating liquid is not specifically limited, It is preferable that it is 0.1-30 mass%, and it is more preferable that it is 0.5-10 mass%. If the content of the polyimide compound is too low, when the film is formed on the porous support, it easily penetrates into the lower layer, so that there is a high possibility that defects will occur in the surface layer that contributes to separation. On the other hand, if the content of the polyimide compound is too high, the pores are filled at a high concentration when the film is formed on the porous support, and the permeability may be lowered. The gas separation membrane of the present invention can be appropriately produced by adjusting the molecular weight, structure, composition, and solution viscosity of the polymer in the separation layer.

-Organic solvent-
The organic solvent used as a medium for the coating solution is not particularly limited, but is a hydrocarbon organic solvent such as n-hexane or n-heptane, an ester organic solvent such as methyl acetate, ethyl acetate, or butyl acetate, Lower alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol and tert-butanol, aliphatic ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, diacetone alcohol, cyclopentanone and cyclohexanone, ethylene glycol , Diethylene glycol, triethylene glycol, glycerin, propylene glycol, ethylene glycol monomethyl or monoethyl ether, propylene glycol methyl ether, dipropylene glycol methyl ether, triplicate Ether-based organics such as pyrene glycol methyl ether, ethylene glycol phenyl ether, propylene glycol phenyl ether, diethylene glycol monomethyl or monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl or monoethyl ether, dibutylbutyl ether, tetrahydrofuran, methylcyclopentyl ether, dioxane Examples include solvents, N-methylpyrrolidone, 2-pyrrolidone, dimethylformamide, dimethylimidazolidinone, dimethyl sulfoxide, dimethylacetamide and the like. These organic solvents are appropriately selected as long as they do not adversely affect the substrate, such as ester-based (preferably butyl acetate), alcohol-based (preferably methanol, ethanol, isopropanol). , Isobutanol), aliphatic ketones (preferably methyl ethyl ketone, methyl isobutyl ketone, diacetone alcohol, cyclopentanone, cyclohexanone), ether type (ethylene glycol, diethylene glycol monomethyl ether, methyl cyclopentyl ether) are preferred, and more preferred are fats Group-based ketones, alcohols, and ethers. Moreover, these can be used 1 type or in combination of 2 or more types.

<Other layers between the support layer and the gas separation layer>
In the gas separation composite membrane of the present invention, another layer may exist between the support layer and the gas separation layer. A preferred example of the other layer is a siloxane compound layer. By providing the siloxane compound layer, the unevenness on the outermost surface of the support can be smoothed, and the separation layer can be easily thinned. Examples of the siloxane compound forming the siloxane compound layer include those having a main chain made of polysiloxane and compounds having a siloxane structure and a non-siloxane structure in the main chain.

-Siloxane compound whose main chain is made of polysiloxane-
Examples of the siloxane compound having a main chain made of polysiloxane that can be used in the siloxane compound layer include one or more polyorganosiloxanes represented by the following formula (1) or (2). Moreover, these polyorganosiloxanes may form a crosslinking reaction product. As the cross-linked reaction product, for example, a compound represented by the following formula (1) is cross-linked by a polysiloxane compound having groups at both ends that react with the reactive group X of the following formula (1) and connect. In the form of compounds.

In formula (1), R is a non-reactive group, and is an alkyl group (preferably an alkyl group having 1 to 18 carbon atoms, more preferably an alkyl group having 1 to 12 carbon atoms) or an aryl group (preferably 6 to 15 carbon atoms). More preferably, it is an aryl group having 6 to 12 carbon atoms, more preferably phenyl).
X is a reactive group, and is a group selected from a hydrogen atom, a halogen atom, a vinyl group, a hydroxyl group, and a substituted alkyl group (preferably an alkyl group having 1 to 18 carbon atoms, more preferably an alkyl group having 1 to 12 carbon atoms). It is preferable that
Y and Z are the above R or X.
The viscosity of the siloxane compound used in the present invention is not particularly specified, but the viscosity at 25 ° C. is preferably 10 to 100,000 mPa · s, and more preferably 20 to 50,000 mPa · s. .
m is a number of 1 or more, and preferably 1 to 100,000.
n is a number of 0 or more, preferably 0 to 100,000.

  In the formula (2), X, Y, Z, R, m and n have the same meanings as X, Y, Z, R, m and n in the formula (1), respectively.

In the above formulas (1) and (2), when the non-reactive group R is an alkyl group, examples of the alkyl group include methyl, ethyl, hexyl, octyl, decyl, and octadecyl. When the non-reactive group R is a fluoroalkyl group, examples of the fluoroalkyl group include —CH ₂ CH ₂ CF ₃ and —CH ₂ CH ₂ C ₆ F ₁₃ .

In the above formulas (1) and (2), when the reactive group X is a substituted alkyl group, examples of this alkyl group include a hydroxyalkyl group having 1 to 18 carbon atoms and an aminoalkyl group having 1 to 18 carbon atoms. A carboxyalkyl group having 1 to 18 carbon atoms, a chloroalkyl group having 1 to 18 carbon atoms, a glycidoxyalkyl group having 1 to 18 carbon atoms, a glycidyl group, an epoxycyclohexylalkyl group having 7 to 16 carbon atoms, carbon Examples thereof include (1-oxacyclobutan-3-yl) alkyl group, methacryloxyalkyl group, and mercaptoalkyl group of formula 4-18.
Preferably the number of carbon atoms of the alkyl group constituting the hydroxyalkyl groups is an integer of 1 to 10, for _example, -CH _{2 CH 2} CH ₂ OH.
Preferably preferable carbon number of the alkyl group constituting the amino alkyl group is an integer of 1 to 10, for _{example, -CH 2 CH 2 CH 2 NH 2} .
Preferably preferable carbon number of the alkyl group constituting the carboxyalkyl group is an integer of 1 to 10, for _example, -CH ₂ CH ₂ CH ₂ COOH.
Preferably preferable carbon number of the alkyl group constituting the chloroalkyl group is an integer of 1 to 10, -CH 2 _Cl can be cited as preferred examples.
The preferred carbon number of the alkyl group constituting the glycidoxyalkyl group is an integer of 1 to 10, and a preferred example is 3-glycidyloxypropyl.
The preferable carbon number of the said C7-C16 epoxy cyclohexyl alkyl group is an integer of 8-12.
A preferable carbon number of the (1-oxacyclobutan-3-yl) alkyl group having 4 to 18 carbon atoms is an integer of 4 to 10.
Preferred number of carbon atoms of the alkyl group constituting the methacryloxy group is an integer of 1 to 10, for _{example, -CH 2 CH 2 CH 2 -OOC} -C (CH 3) = CH 2 and the like.
The preferable carbon number of the alkyl group constituting the mercaptoalkyl group is an integer of 1 to 10, and examples thereof include —CH ₂ CH ₂ CH ₂ SH.
m and n are preferably numbers that give a molecular weight of 5,000 to 1,000,000.

  In the above formulas (1) and (2), a reactive group-containing siloxane unit (wherein the number is a structural unit represented by n) and a siloxane unit having no reactive group (wherein the number is m The distribution of the structural unit represented by That is, in the formulas (1) and (2), the (Si (R) (R) —O) units and the (Si (R) (X) —O) units may be randomly distributed.

-Compounds having siloxane structure and non-siloxane structure in the main chain-
Examples of the compound having a siloxane structure and a non-siloxane structure in the main chain that can be used in the siloxane compound layer include compounds represented by the following formulas (3) to (7).

In formula (3), R, m and n have the same meanings as R, m and n in formula (1), respectively. R ′ is —O— or —CH ₂ —, and R ″ is a hydrogen atom or methyl. Both ends of the formula (3) are preferably an amino group, a hydroxyl group, a carboxy group, a trimethylsilyl group, an epoxy group, a vinyl group, a hydrogen atom, or a substituted alkyl group.

  In Formula (4), m and n are synonymous with m and n in Formula (1), respectively.

  In Formula (5), m and n are synonymous with m and n in Formula (1), respectively.

  In Formula (6), m and n are synonymous with m and n in Formula (1), respectively. It is preferable that the both ends of Formula (6) have an amino group, a hydroxyl group, a carboxy group, a trimethylsilyl group, an epoxy group, a vinyl group, a hydrogen atom, or a substituted alkyl group bonded thereto.

  In Formula (7), m and n are synonymous with m and n in Formula (1), respectively. It is preferable that an amino group, a hydroxyl group, a carboxy group, a trimethylsilyl group, an epoxy, a vinyl group, a hydrogen atom, or a substituted alkyl group is bonded to both ends of the formula (7).

  In the above formulas (3) to (7), the siloxane structural unit and the non-siloxane structural unit may be randomly distributed.

  The compound having a siloxane structure and a non-siloxane structure in the main chain preferably contains 50 mol% or more of siloxane structural units, more preferably 70 mol% or more, based on the total number of moles of all repeating structural units. .

  The weight average molecular weight of the siloxane compound used for the siloxane compound layer is preferably 5,000 to 1,000,000 from the viewpoint of achieving both thinning and durability. The method for measuring the weight average molecular weight is as described above.

Furthermore, the preferable example of the siloxane compound which comprises a siloxane compound layer is enumerated below.
Polydimethylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane, polysulfone-polyhydroxystyrene-polydimethylsiloxane copolymer, dimethylsiloxane-methylvinylsiloxane copolymer, dimethylsiloxane-diphenylsiloxane-methylvinylsiloxane copolymer, methyl -3,3,3-trifluoropropylsiloxane-methylvinylsiloxane copolymer, dimethylsiloxane-methylphenylsiloxane-methylvinylsiloxane copolymer, diphenylsiloxane-dimethylsiloxane copolymer terminal vinyl, polydimethylsiloxane terminal vinyl, One or more selected from polydimethylsiloxane terminal H and dimethylsiloxane-methylhydrosiloxane copolymer. In addition, these include the form which forms the cross-linking reaction product.

In the composite film of the present invention, the thickness of the siloxane compound layer is preferably 0.01 to 5 μm, and more preferably 0.05 to 1 μm, from the viewpoint of smoothness and gas permeability.
Further, the gas permeability at 40 ° C. and 4 MPa of the siloxane compound layer is preferably 100 GPU or more, more preferably 300 GPU or more, and further preferably 1000 GPU or more in terms of carbon dioxide transmission rate.

(Gas separation asymmetric membrane)
The gas separation membrane of the present invention may be an asymmetric membrane. The asymmetric membrane can be formed by a phase change method using a solution containing a polyimide compound. The phase inversion method is a known method for forming a film while bringing a polymer solution into contact with a coagulation liquid to cause phase conversion. In the present invention, a so-called dry / wet method is suitably used. In the dry-wet method, a thin polymer layer (gas separation layer) is formed by evaporating the solution on the surface of the polymer solution in the form of a film, and then coagulating liquid (solvent is compatible with the solvent of the polymer solution and the polymer is an insoluble solvent. ) And forming a porous layer by utilizing the phase separation phenomenon that occurs at that time, and a proposal by Rob Thrillerjan et al. (For example, US Pat. No. 3,133,132) Description).

  In the gas separation asymmetric membrane of the present invention, the thickness of a surface layer (gas separation layer) that contributes to gas separation called a dense layer or a skin layer is not particularly limited. It is preferably 01 to 5.0 μm, more preferably 0.05 to 1.0 μm. On the other hand, the porous layer below the dense layer lowers the gas permeability resistance and at the same time plays a role of imparting mechanical strength, and its thickness is particularly limited as long as it is self-supporting as an asymmetric membrane. Although it is not limited, it is preferable that it is 5-500 micrometers, It is more preferable that it is 5-200 micrometers, It is further more preferable that it is 5-100 micrometers.

  The gas separation asymmetric membrane of the present invention may be a flat membrane or a hollow fiber membrane. The asymmetric hollow fiber membrane can be produced by a dry and wet spinning method. The dry-wet spinning method is a method for producing an asymmetric hollow fiber membrane by applying a dry-wet method to a polymer solution that is discharged from a spinning nozzle to have a hollow fiber-shaped target shape. More specifically, the polymer solution is discharged from a nozzle into a hollow fiber-shaped target shape, and after passing through an air or nitrogen gas atmosphere immediately after discharge, the polymer is not substantially dissolved and is compatible with the solvent of the polymer solution. In this method, an asymmetric structure is formed by immersing in a coagulating liquid containing, then dried, and further heat-treated as necessary to produce a separation membrane.

  The solution viscosity of the solution containing the polyimide compound discharged from the nozzle is 2 to 17000 Pa · s, preferably 10 to 1500 Pa · s, particularly 20 to 1000 Pa · s at the discharge temperature (for example, 10 ° C.). This is preferable because the shape after discharge can be stably obtained. For immersion in the coagulation liquid, the film is immersed in the primary coagulation liquid and solidified to such an extent that the shape of the hollow fiber or the like can be maintained. It is preferable to solidify. It is efficient to dry the coagulated film after replacing the coagulating liquid with a solvent such as hydrocarbon. The heat treatment for drying is preferably performed at a temperature lower than the softening point or secondary transition point of the used polyimide compound.

The tensile strength of the gas separation asymmetric membrane of the present invention is preferably 10 N / mm ² or more, and more preferably 12 N / mm ² or more in order to further increase the mechanical strength. There is no particular limitation on the upper limit of the tensile strength, usually is at 25 N / mm ² or less, may be 20 N / mm ² or less. Further, the compressive strength of the gas separation asymmetric membrane of the present invention is preferably 10 MPa or more, and more preferably 15 MPa or more. Although there is no restriction | limiting in particular in the upper limit of this compressive strength, Usually, it is 50 MPa or less, and 40 MPa or less may be sufficient.

  In order to provide the gas separation asymmetric membrane of the present invention with appropriate mechanical flexibility as well as the above mechanical strength, the breaking elongation of the gas separation asymmetric membrane of the present invention is preferably 12% or more, and more preferably 16% or more. The upper limit of the elongation at break is not particularly limited, but is usually 25% or less and may be 20% or less. From the same viewpoint, the tensile elastic modulus of the gas separation asymmetric membrane of the present invention is preferably 100 MPa or less, more preferably 90 MPa or less, and further preferably 80 MPa or less. The lower limit of the tensile elastic modulus is usually 10 MPa or more, 20 MPa or more, 30 MPa or more, or 40 MPa or more in order to achieve compatibility with mechanical strength. .

  In the gas separation membrane of the present invention, the content of the polyimide compound in the gas separation layer is not particularly limited as long as desired gas separation performance can be obtained. From the viewpoint of further improving the gas separation performance, the content of the polyimide compound in the gas separation layer is preferably 20% by mass or more, more preferably 40% by mass or more, and 60% by mass or more. Is preferable, and it is more preferable that it is 70 mass% or more. The content of the polyimide compound in the gas separation layer may be 100% by mass, but is usually 99% by mass or less.

(Use and characteristics of gas separation membrane)
The gas separation membrane (composite membrane and asymmetric membrane) of the present invention can be suitably used for gas separation recovery and gas separation purification. For example, hydrogen, helium, carbon monoxide, carbon dioxide, hydrogen sulfide, oxygen, nitrogen, ammonia, sulfur oxides, nitrogen oxides, hydrocarbons such as methane and ethane, unsaturated hydrocarbons such as propylene, tetrafluoroethane, etc. A gas separation membrane capable of efficiently separating a specific gas from a gas mixture containing a gas such as a perfluoro compound. In particular, a gas separation membrane that selectively separates carbon dioxide from a gas mixture containing carbon dioxide / hydrocarbon (methane) is preferable.

In particular, when the gas to be separated is a mixed gas of carbon dioxide and methane, the permeation rate of carbon dioxide at 40 ° C. and 5 MPa is preferably more than 20 GPU, more preferably more than 30 GPU, More preferably, it is 50-500 GPU. The permeation rate ratio of carbon dioxide to methane (R _CO2 / R _CH4 ) is preferably 15 or more, more preferably 20 or more, further preferably 23 or more, and preferably 25 to 50. Particularly preferred. R _CO2 represents the permeation rate of carbon dioxide, and R _CH4 represents the permeation rate of methane.
1 GPU is 1 × 10 ⁻⁶ cm ³ (STP) / cm ² · sec · cmHg.

(Other ingredients)
Various polymer compounds can be added to the gas separation layer of the gas separation membrane of the present invention in order to adjust the membrane properties. High molecular compounds include acrylic polymers, polyurethane resins, polyamide resins, polyester resins, epoxy resins, phenol resins, polycarbonate resins, polyvinyl butyral resins, polyvinyl formal resins, shellac, vinyl resins, acrylic resins, rubber resins. Waxes and other natural resins can be used. Two or more of these may be used in combination.
Further, nonionic surfactants, cationic surfactants, organic fluoro compounds, and the like can be added to adjust liquid properties.

  Specific examples of the surfactant include alkylbenzene sulfonate, alkylnaphthalene sulfonate, higher fatty acid salt, sulfonate of higher fatty acid ester, sulfate ester of higher alcohol ether, sulfonate of higher alcohol ether, higher alkyl Anionic surfactants such as alkyl carboxylates of sulfonamides, alkyl phosphates, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, ethylene oxide adducts of acetylene glycol, Nonionic surfactants such as ethylene oxide adducts of glycerin and polyoxyethylene sorbitan fatty acid esters, and other amphoteric interfaces such as alkyl betaines and amide betaines Sexual agents, silicone surface active agents, including such fluorine-based surfactant, can be appropriately selected from surfactants and derivatives thereof are known.

  In addition, a polymer dispersant may be included, and specific examples of the polymer dispersant include polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl methyl ether, polyethylene oxide, polyethylene glycol, polypropylene glycol, and polyacrylamide. Of these, polyvinylpyrrolidone is preferably used.

  Although there is no restriction | limiting in particular in the conditions which form the gas separation membrane of this invention, -30-100 degreeC is preferable, as for temperature, -10-80 degreeC is more preferable, and 5-50 degreeC is especially preferable.

  In the present invention, a gas such as air or oxygen may coexist at the time of forming the film, but it is preferably in an inert gas atmosphere.

[Separation method of gas mixture]
The gas separation method of the present invention is a method including selectively permeating carbon dioxide from a mixed gas containing carbon dioxide and methane using the gas separation membrane of the present invention. The pressure during gas separation is preferably 0.5 to 10 MPa, more preferably 1 to 10 MPa, and further preferably 2 to 7 MPa. The gas separation temperature is preferably −30 to 90 ° C., more preferably 15 to 70 ° C. In the mixed gas containing carbon dioxide and methane gas, the mixing ratio of carbon dioxide and methane gas is not particularly limited, but is preferably carbon dioxide: methane gas = 1: 99 to 99: 1 (volume ratio). Methane gas is more preferably 5:95 to 90:10.

[Gas separation module / gas separator]
A gas separation module can be prepared using the gas separation membrane of the present invention. Examples of modules include spiral type, hollow fiber type, pleated type, tubular type, plate & frame type and the like.
In addition, a gas separation apparatus having means for separating and recovering or purifying gas can be obtained using the gas separation membrane or gas separation membrane module of the present invention. The gas separation membrane of the present invention may be applied, for example, to a gas separation / recovery device as a membrane / absorption hybrid method used in combination with an absorption liquid as described in JP-A-2007-297605.

  The present invention will be described below in more detail based on examples, but the present invention is not limited to these examples.

[Synthesis example]
<Synthesis of polyimide (P-1)>
After putting 14.0 g (66 mmol) of 3,5-dinitrobenzamide (manufactured by Sigma-Aldrich) into a 2 L flask, 600 mL of methanol was added to completely dissolve it. This 3,5-dinitrobenzamide solution was transferred to a SUS pressure vessel (capacity 1.0 L, manufactured by Nitto High Pressure Co., Ltd.), and then palladium carbon (palladium content 5%, approximately 50% water wet product, Kawaken Fine Chemical Co., Ltd.) (Product made) 2.8g was added, the hydrogen pressure of 1.0-8.0MPa was applied, stirring, and catalytic hydrogenation was performed. During the catalytic hydrogenation, the hydrogen pressure and the temperature of the heater were adjusted, and stirring was continued for 7 hours while maintaining the temperature of the reaction solution at 35 to 45 ° C. The reaction solution was transferred from the pressure vessel to a 2 L flask with an aspirator and cooled rapidly through Celite to remove palladium carbon, so that the product or the like was not precipitated. Methanol was removed under reduced pressure from the reddish brown solution obtained by filtration. The obtained solid was purified by recrystallization using methanol and water to obtain 3.4 g of the desired 3,5-diaminobenzamide.
1.09 g (7.24 mmol) of 3,5-diaminobenzamide obtained by the above synthesis, 1.78 g (10.86 mmol) of 2,3,5,6-tetramethyl-1,4-phenylenediamine, N-methyl Pyrrolidone (50 mL) was placed in a 300 mL flask and stirred to dissolve completely in a nitrogen atmosphere. After the solution was cooled to −10 ° C. with ice-cold methanol, 8.04 g (18.1 mmol) of 6FDA (manufactured by Tokyo Chemical Industry Co., Ltd.) was added and washed with 6 mL of N-methylpyrrolidone. The reaction solution was heated to 40 ° C. with an oil bath and stirred for 5 hours. After adding 0.43 g (5.4 mmol) of pyridine (manufactured by Wako Pure Chemical Industries, Ltd.) and 6.10 g (59.7 mmol) of acetic anhydride (manufactured by Wako Pure Chemical Industries, Ltd.), the reaction solution was heated to 80 ° C. Stir for 3 hours. The reaction solution was cooled to room temperature, 80 mL of acetone was added, and the mixture was stirred for 30 minutes. Methanol 250 mL was added over 10 minutes to precipitate P-1 as a white powder. The white powder obtained by suction filtration was repeatedly washed four times with 250 mL of methanol to remove N-methylpyrrolidone to 0.1% or less, and then blown at 40 ° C. for 12 hours with a blower dryer. It dried and obtained 9.23 g (yield 90%) of polyimide (P-01). The content of carbamoyl group in the polyimide (P-01) was 0.71 mmol / g.

<Polyimide (P-02-17), Synthesis of Comparative Polyimide 01-04>
In accordance with the above synthesis example, polyimides (P-02 to 17, comparative polyimides 01 to 04) composed of the following structural units (repeating units) were synthesized.

<Comparative polymer>
A commercially available product (trade name: L-70, manufactured by Daicel Corporation, degree of acetylation 0.55) was used as cellulose acetate composed of the following structural units (repeating units). The degree of acetylation means the weight percentage of bound acetic acid per unit weight.

[Example 1] Production of composite membrane <Production of PAN porous membrane with smooth layer>
(Preparation of radiation curable polymer having dialkylsiloxane group)
In a 150 mL three-necked flask, 39 g of UV9300 (manufactured by Momentive), 10 g of X-22-162C (manufactured by Shin-Etsu Chemical Co., Ltd.), DBU (1,8-diazabicyclo [5.4.0] undec-7-ene). 007 g was added and dissolved in 50 g of n-heptane. This was maintained at 95 ° C. for 168 hours to obtain a radiation curable polymer solution having a poly (siloxane) group (viscosity of 22.8 mPa · s at 25 ° C.).

(Preparation of polymerizable radiation curable composition)
5 g of the radiation curable polymer solution was cooled to 20 ° C. and diluted with 95 g of n-heptane. To the obtained solution, 0.5 g of UV9380C (manufactured by Momentive) as a photopolymerization initiator and 0.1 g of organics TA-10 (manufactured by Matsumoto Fine Chemical) are added, and a polymerizable radiation-curable composition is prepared. Prepared.

(Application of polymerizable radiation curable composition to porous support, formation of smooth layer)
PAN (polyacrylonitrile) porous membrane (polyacrylonitrile porous membrane is present on the nonwoven fabric, including the nonwoven fabric, the film thickness is about 180 μm) After spin coating the above polymerizable radiation curable composition as a support, After UV treatment (Fusion UV System, Light Hammer 10, D-bulb) under UV treatment conditions with a UV intensity of 24 kW / m and a treatment time of 10 seconds, drying was performed. In this way, a smooth layer having a thickness of 1 μm and having a dialkylsiloxane group was formed on the porous support.

<Production of composite membrane>
In a 30 ml brown vial, 1.4 g of polyimide (P-01) and 8.6 g of tetrahydrofuran were mixed and stirred for 30 minutes, then spin-coated on the PAN porous membrane provided with the above smooth layer, and a composite membrane ( Example 1) was obtained. The thickness of the polyimide (P-01) layer was about 150 nm, and the thickness of the polyacrylonitrile porous film including the nonwoven fabric was about 180 μm.
These polyacrylonitrile porous membranes had a molecular weight cut-off of 100,000 or less. Further, the permeability of carbon dioxide at 40 ° C. and 5 MPa of this porous membrane was 25000 GPU.

[Examples 2 to 17] Preparation of Composite Film Examples shown in Table 1 are the same as Example 1 except that polyimide (P-01) is changed as shown in Table 1 in Example 1. 2 to 17 composite membranes were prepared.

[Comparative Examples 1-5] Production of Composite Film In Example 1 above, except that polyimide (P-01) was changed to comparative polyimide 01-04 or cellulose acetate (comparative polymer), the same as in Example 1, Composite films of Comparative Examples 1 to 5 were produced.

Example 18 Production of Asymmetric Membrane 2.5 g of methyl ethyl ketone, 2.5 g of N, N-dimethylformamide, and 0.6 g of n-butanol were added to 0.5 g of polyimide (P-01) prepared in the same manner as above. After adding and dissolving a mixed solution, it filtered with the microfiltration membrane made from PTFE with a hole diameter of 5.0 micrometers, and this was made into dope solution. A non-woven fabric made of polyester (made by Awa Paper Co., Ltd., film thickness: 95 μm) is laid on a clean glass plate, and the dope solution is developed in an environment at room temperature (20 ° C.) and allowed to stand for 30 seconds. After immersing in (0 ° C., 75 wt% methanol aqueous solution) for 1 hour, and further dipping in a secondary coagulation liquid (0 ° C., 75 wt% methanol aqueous solution) for 1 hour, an asymmetric membrane was produced. After washing the obtained asymmetric membrane with methanol, the methanol is replaced with isooctane, and further heating is carried out at 50 ° C. for 8 hours and at 110 ° C. for 6 hours to evaporate and dry isooctane, so that the dense skin layer is 0.1 μm or less. An asymmetric membrane (Example 18) having a total polyimide layer thickness of 40 μm was obtained.

[Example 19] Production of asymmetric membrane The asymmetric membrane of Example 19 was produced in the same manner as in Example 18 except that polyimide (P-01) was changed to polyimide (P-02) in Example 18 above. .

Comparative Example 6 Production of Asymmetric Membrane An asymmetric membrane of Comparative Example 6 was produced in the same manner as in Example 18 except that polyimide (P-01) was changed to comparative polyimide 01 in Example 18 above.

[Comparative Example 7] Production of Asymmetric Membrane Asymmetric membrane of Comparative Example 7 was produced in the same manner as in Example 18 except that polyimide (P-01) was changed to cellulose acetate (comparative polymer) in Example 18. .

[Test Example 1] Evaluation of gas separation membrane CO ₂ permeation rate and gas separation selectivity-1
Using the gas separation membranes (composite membranes and asymmetric membranes) of the above Examples and Comparative Examples, the gas separation performance was evaluated as follows.
The gas separation membrane was cut to a diameter of 47 mm together with the porous support (support layer) to prepare a permeation test sample. With GTR Tec Corp. gas permeability measuring apparatus, carbon dioxide _(CO 2), minute methane (CH ₄₎ is 40:60 total pressure of a mixed gas of the gas supply side (volume ratio) 4 MPa (CO ₂ The pressure was adjusted to 1.6 MPa), the flow rate was 500 mL / min, and 40 ° C. was supplied. The permeated gas was analyzed by gas chromatography. The gas permeability of the membrane was compared by calculating the gas permeation rate as gas permeability (Permeance). The unit of gas permeation rate (gas permeation rate) was expressed in GPU (GPI) unit [1 GPU = 1 × 10 ⁻⁶ cm ³ (STP) / cm ² · sec · cmHg]. The gas separation selectivity was calculated as the ratio of the CO ₂ permeation rate R _{CO2 to} the CH ₄ permeation rate R _CH4 of this membrane (R _CO2 / R _CH4 ).

[Test Example 2] Toluene exposure test A 100 ml empty beaker was allowed to stand in a glass container with a lid covered with a toluene solvent, and the gas separation membrane sections prepared in Examples and Comparative Examples were placed in the beaker. And a glass lid was applied to the glass container to make a closed system. Then, after storing for 5 hours at 40 ° C., gas separation performance was evaluated in the same manner as in [Test Example 1]. By exposure to toluene, it is possible to evaluate the plasticization resistance of the gas separation membrane against impurity components such as benzene, toluene and xylene.

[Test Example 3] Evaluation of CO ₂ permeation rate and gas separation selectivity of gas separation membrane-2
Using the gas separation membranes (composite membranes and asymmetric membranes) of Examples 1, 5, 8, 18, and 19 and Comparative Examples 2, 5, 6, and 7, the gas separation performance was evaluated as follows.
The gas separation membrane was cut to a diameter of 47 mm together with the porous support (support layer) to prepare a permeation test sample. Using a gas permeability measuring device manufactured by GTR Tech Co., Ltd., a mixed gas of 10:90 (volume ratio) of carbon dioxide (CO ₂ ) and methane (CH ₄ ) is 4 MPa (a fraction of CO ₂ ) The pressure was adjusted to 0.4 MPa), the flow rate was 500 mL / min, and 30 ° C. was supplied. The permeated gas was analyzed by gas chromatography. The CO ₂ permeation rate and gas separation selectivity were evaluated in the same manner as in Test Example 1.

  The results of the above test examples are shown in Table 1 below.

As shown in Table 1 above, the gas separation membrane produced using the polyimide compound having no carbamoyl group resulted in inferior in both CO ₂ permeation rate and gas separation selectivity under high pressure (comparison). Examples 1 and 2). Moreover, the gas separation membrane manufactured using the polyimide compound whose content of carbamoyl groups is less than that defined in the present invention was inferior in CO ₂ permeation rate and gas separation selectivity (Comparative Example 3). On the other hand, when the content of the carbamoyl group was larger than specified in the present invention, the polarity was so high that it was not dissolved in the solvent and could not be formed (Comparative Example 4). Further, when cellulose acetate was used instead of polyimide for the gas separation layer, both the CO ₂ permeation rate and the gas separation selectivity were inferior (Comparative Example 5).
On the other hand, a gas separation membrane having a gas separation layer formed using a polyimide compound containing a carbamoyl group in an amount specified in the present invention shows a CO ₂ permeation rate of 80 GPU or more in Test Example 1, and CO ₂ permeability. It was excellent. Furthermore, as for gas separation selectivity, all of Test Examples 1 had a high performance of 25 or more, and this gas separation selectivity was not greatly reduced by exposure to toluene. Furthermore, even in Test Example 3 in which the temperature of the gas to be separated and the mixing ratio of CO ₂ and CH ₄ were changed, excellent CO ₂ permeation rate and gas separation selectivity were exhibited, and stable gas separation membrane performance was exhibited. I understand.

  From the above results, it was found that the gas separation membrane of the present invention can provide an excellent gas separation method, a gas separation module, and a gas separation apparatus equipped with this gas separation module.

DESCRIPTION OF SYMBOLS 1 Gas separation layer 2 Porous layer 3 Nonwoven fabric layer 10, 20 Gas separation composite membrane

Claims (10)

A gas separation membrane having a gas separation layer containing a polyimide compound,
The gas separation membrane in which the polyimide compound has a carbamoyl group, and the content of the carbamoyl group in the polyimide compound is 0.1 to 3.0 mmol / g. The gas separation membrane according to claim 1, wherein the polyimide compound includes a repeating unit represented by the following formula (A) or (B).

In the formula (A), R represents a group having a structure represented by any of the following formulas (I-1) to (I-28). Here, X ^{1 to} X ³ represent a single bond or a divalent linking group, L represents —CH═CH— or —CH ₂ —, R ¹ and R ² represent a hydrogen atom or a substituent, and * represents a formula ( A binding site with the carbonyl group in A) is shown. R ⁴ represents a substituent, and l1 represents an integer of 1 to 4. When l1 is 1, R ⁴ is a group having a carbamoyl group. When l1 is 2 to ⁴ , at least one of R ⁴ is a group having a carbamoyl group.

In the formula (B), R has the same meaning as R in the formula (A). R ⁵ and R ⁶ represent a substituent. m1 and n1 are integers of 0 to 4, but neither m1 nor n1 is 0. When m1 is 0, at least one of R ⁶ is a group having a carbamoyl group, and when n1 is 0, at least one of R ⁵ is a group having a carbamoyl group. When m1 and n1 are both 1 or more, at least one of R ⁵ and R ⁶ is a group having a carbamoyl group. X ⁴ represents a single bond or a divalent linking group.

The gas separation membrane according to claim 2, wherein the repeating unit represented by the formula (A) is a repeating unit represented by the following formula (a):

In formula (a), R has the same meaning as R in formula (A). R ^4a is a hydrogen atom or a substituent having no carbamoyl group.   The gas separation membrane according to any one of claims 1 to 3, wherein the gas separation membrane is a gas separation composite membrane having the gas separation layer on the gas permeable support layer.   The gas separation membrane according to claim 4, wherein the support layer comprises a porous layer on the gas separation layer side and a nonwoven fabric layer on the opposite side. In the case where the gas to be separated is a mixed gas of carbon dioxide and methane, the permeation rate of carbon dioxide at 40 ° C. and 5 MPa exceeds 20 GPU, and the permeation rate ratio of carbon dioxide and methane (R _CO2 / R _CH4 ) The gas separation membrane according to any one of claims 1 to 5, wherein is 15 or more.   The gas separation membrane according to any one of claims 1 to 6, which is used to selectively permeate carbon dioxide from a gas containing carbon dioxide and methane.   A gas separation module comprising the gas separation membrane according to claim 1.   A gas separation apparatus comprising the gas separation module according to claim 8.   A gas separation method in which carbon dioxide is selectively permeated from a gas containing carbon dioxide and methane using the gas separation membrane according to claim 1.

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