Separation function layer and separation membrane

Abstract

A separation function layer 1 according to the present invention contains particles and a crosslinked polymer in which a polymer containing a carbon atom is crosslinked via a first linking group. The first linking group is a hydrocarbon group bonded to the carbon atom. The particles are bonded to the crosslinked polymer. A separation membrane 10 according to the present invention comprises: said separation function layer 1; and a porous support 3 that supports the separation function layer 1.

Description

Separation functional layer and separation membrane

[0001] The present invention relates to a separation functional layer and a separation membrane.

[0002] Membrane separation is a method developed to separate acidic gases, such as carbon dioxide, from gas mixtures containing them. Compared to absorption methods, which separate acidic gases by having an absorbent absorb them, membrane separation can efficiently separate acidic gases while keeping operating costs down.

[0003] Examples of separation membranes used in membrane separation methods include composite membranes in which a separation functional layer is formed on a porous support. Examples of materials for the separation functional layer include resins such as polyimide resin and polyether block amide resin. For example, Patent Document 1 discloses a separation membrane containing polyimide resin.

[0004] Japanese Patent Publication No. 2014-184424

[0005] There is a need for a new separation layer suitable for separating acidic gases from a gas mixture containing acidic gases.

[0006] The present invention provides a separation functional layer comprising a crosslinked polymer in which a polymer containing carbon atoms is crosslinked via a first linking group, and particles, wherein the first linking group is a hydrocarbon group bonded to the carbon atoms, and the particles are bonded to the crosslinked polymer.

[0007] Furthermore, the present invention provides a separation membrane comprising the above-mentioned separation functional layer and a porous support that supports the separation functional layer.

[0008] According to the present invention, a novel separation functional layer suitable for separating acidic gases from a gas mixture containing acidic gases can be provided.

[0009] This is a schematic cross-sectional view showing a separation functional layer according to one embodiment of the present invention. This is a schematic cross-sectional view showing a separation membrane according to one embodiment of the present invention. This is a schematic cross-sectional view of a membrane separation apparatus equipped with the separation membrane of the present invention. This is a schematic cross-sectional view of another example of a membrane separation apparatus equipped with the separation membrane of the present invention. This is a schematic perspective view showing a modified example of a membrane separation apparatus equipped with the separation membrane of the present invention.

[0010] A separation functional layer according to a first aspect of the present invention is a separation functional layer comprising a crosslinked polymer in which a polymer containing carbon atoms is crosslinked via a first linking group, and particles, wherein the first linking group is a hydrocarbon group bonded to the carbon atoms, and the particles are bonded to the crosslinked polymer.

[0011] In a second embodiment of the present invention, for example, in the separation functional layer according to the first embodiment, the hydrocarbon group is an alkylene group.

[0012] In a third aspect of the present invention, for example, in the separation functional layer according to the second aspect, the number of carbon atoms in the alkylene group is 1 to 5.

[0013] In a fourth aspect of the present invention, for example, in a separation functional layer according to any one of the first to third aspects, the polymer includes an aromatic ring, and the aromatic ring includes the carbon atom.

[0014] In a fifth embodiment of the present invention, for example, in the separation functional layer according to the fourth embodiment, the polymer contains an electron-donating group, and the electron-donating group is bonded to the aromatic ring.

[0015] In a sixth embodiment of the present invention, for example, in the separation functional layer according to any one of the first to fifth embodiments, the polymer is polyimide.

[0016] In a seventh embodiment of the present invention, for example, in the separation functional layer according to the sixth embodiment, the polyimide comprises a constituent unit A1 derived from a tetracarboxylic dianhydride having a six-membered ring acid anhydride structure and a constituent unit B derived from a diamine.

[0017] In the eighth embodiment of the present invention, for example, in the separation functional layer according to the seventh embodiment, the constituent unit B has the carbon atoms.

[0018] In the ninth embodiment of the present invention, for example, in the separation functional layer according to the seventh or eighth embodiment, the constituent unit A1 is represented by the following formula (A1). In the above formula (A1), R 1a ~R 4a These are, independently of each other, a hydrogen atom or any substituent.

[0019] In the tenth embodiment of the present invention, for example, in the separation functional layer according to any one of the first to ninth embodiments, the particles are bonded to the crosslinked polymer via a second linking group.

[0020] In the eleventh embodiment of the present invention, for example, in the separation functional layer according to the tenth embodiment, the second linking group is a hydrocarbon group.

[0021] In the twelfth aspect of the present invention, for example, in the separation functional layer according to any one of the first to eleventh aspects, the particles are porous particles.

[0022] In a thirteenth aspect of the present invention, for example, in the separation functional layer according to the twelfth aspect, the porous particles include an organic polymer.

[0023] In a fourteenth aspect of the present invention, for example, in the separation functional layer according to the thirteenth aspect, the organic polymer includes an aromatic ring.

[0024] In a 15th aspect of the present invention, for example, in the separation functional layer according to the 13th or 14th aspect, the organic polymer is a porous polymer.

[0025] In the sixteenth aspect of the present invention, for example, in the separation functional layer according to any one of the first to fifteenth aspects, the particles are surface-modified.

[0026] In the seventeenth aspect of the present invention, for example, in the separation functional layer according to any one of the first to sixteenth aspects, the content of the particles is 3 wt% or more and 50 wt% or less relative to the crosslinked polymer.

[0027] In the eighteenth aspect of the present invention, for example, a separation functional layer according to any one of the first to seventeenth aspects is used to separate an acidic gas from a mixed gas containing an acidic gas.

[0028] A separation membrane according to the 19th aspect of the present invention comprises a separation functional layer according to any one of the first to 18th aspects, and a porous support that supports the separation functional layer.

[0029] The details of the present invention will be described below, but the following description is not intended to limit the present invention to any particular embodiment.

[0030] <Embodiment of the Separation Functional Layer> Figure 1 is a schematic cross-sectional view of the separation functional layer 1 of this embodiment. The separation functional layer 1 in Figure 1 can function as a self-supporting membrane (single-layer membrane). The separation functional layer 1 preferably allows acidic gases contained in the mixed gas to permeate preferentially. Typically, the separation functional layer 1 is a dense layer (non-porous layer) in which no pores can be observed when viewed with a scanning electron microscope (SEM) at a magnification of 5000x.

[0031] The separation functional layer 1 contains a crosslinked polymer Q and particles M. The crosslinked polymer Q is a polymer G containing carbon atoms that is crosslinked via a first linking group, and this first linking group is a hydrocarbon group bonded to the carbon atoms. The particles M are bonded to the crosslinked polymer Q. That is, the crosslinked polymer Q may be a polymer G that is crosslinked not only via the first linking group, but also via particles M.

[0032] There are no linking groups or functional groups between the first linking group and the carbon atom; they are directly bonded. In this specification, "a polymer containing carbon atoms is crosslinked via a first linking group" means that polymer G (more specifically, molecules of multiple polymer Gs) reacts with a crosslinking agent to form a crosslinked structure which is a first linking group (hydrocarbon group). Therefore, in the crosslinked polymer Q, for example, two molecules of polymer G, polymer G1 and polymer G2, are crosslinked via a hydrocarbon group, such that carbon atom g1 in polymer G1 and carbon atom g2 in polymer G2 are bonded to a single hydrocarbon group.

[0033] The first linking group is a hydrocarbon group. The hydrocarbon group may be a divalent hydrocarbon group, and is preferably an alkylene group.

[0034] The number of carbon atoms in the alkylene group is preferably 1 to 10, more preferably 1 to 7, even more preferably 1 to 5, and particularly preferably 1 to 3. The alkylene group may be linear or branched. The alkylene group is, for example, a methylene group, a 1-methylmethylene group, a 1,1-dimethylmethylene group, an ethylene group, a 1-methylethylene group, a 1-ethylethylene group, a 1,1-dimethylethylene group, a 1,2-dimethylethylene group, a 1-ethyl-2-methylethylene group, a trimethylene group, a 1-methyltrimethylene group, a 2-methyltrimethylene group, a 1,1-dimethyltrimethylene group, a 1,2-dimethyltrimethylene group, a 2,2-dimethyltrimethylene group, a 1-ethyltrimethylene group, a 2-ethyltrimethylene group, a tetramethylene group, a 1-methyltetramethylene group, a 2-methyltetramethylene group, or a pentamethylene group. Preferably, it is a methylene group, an ethylene group, or a trimethylene group, and more preferably, a methylene group. The carbon atom g1 may be bonded to one end of the main chain of the alkylene group, and the carbon atom g2 may be bonded to the other end of the main chain of the alkylene group. For example, the alkylene group may be linear, with carbon atom g1 bonded to one end of the alkylene group and carbon atom g2 bonded to the other end.

[0035] Particle M is bonded to the crosslinked polymer Q. Particle M may also be bonded to the crosslinked polymer Q via a second linking group.

[0036] The second linking group is not particularly limited, but is preferably a hydrocarbon group, more preferably a divalent hydrocarbon group, and even more preferably an alkylene group. Examples of alkylene groups include those mentioned above. It is preferable that one end of the second linking group is bonded to a carbon atom of the crosslinked polymer Q. It is also preferable that the other end of the second linking group is bonded to a carbon atom of the particle M.

[0037] The second linking group and the first linking group may be different from each other, or they may be the same.

[0038] The thickness of the separation functional layer 1 is, for example, 500 μm or less, and may be 300 μm or less, 100 μm or less, 50 μm or less, 25 μm or less, 20 μm or less, or even 10 μm or less. The thickness of the separation functional layer 1 may be 0.05 μm or more, or 0.1 μm or more. The thickness of the separation functional layer 1 can be measured, for example, by observing a cross-section of the separation functional layer 1 with a scanning electron microscope.

[0039] The following details the crosslinked polymer Q and particles M contained in the separation functional layer 1.

[0040] (Crosslinked Polymer Q) Crosslinked polymer Q is a polymer G containing carbon atoms that is crosslinked via a first linking group. Polymer G contains an aromatic ring, and the aromatic ring may contain the above carbon atoms (specifically, carbon atoms g1 and g2). That is, polymer G may be crosslinked by the carbon atoms constituting the aromatic ring contained in polymer G bonding with the above hydrocarbon group. The aromatic ring may consist only of carbon atoms and hydrogen atoms, or it may be a heteroaromatic ring containing heteroatoms such as oxygen atoms, nitrogen atoms, and sulfur atoms. The aromatic ring may be polycyclic or monocyclic. The number of carbon atoms in the aromatic ring is not particularly limited, for example, 4 to 14. Specific examples of aromatic rings include benzene rings, naphthalene rings, anthracene rings, phenanthrene rings, fluorene rings, furan rings, pyrrole rings, pyridine rings, and thiophene rings.

[0041] Polymer G may further contain electron-donating groups. Typically, the electron-donating groups are bonded to the aromatic rings. The inclusion of electron-donating groups bonded to the aromatic rings in polymer G can facilitate the crosslinking reaction of polymer G in the production of crosslinked polymer Q. This allows for a higher degree of crosslinking of crosslinked polymer Q. An electron-donating group is, for example, the substituent constant σ in the Hammett equation. p This refers to substituents with a negative value. Examples of electron-donating groups include alkyl groups and alkoxy groups. Examples of alkyl groups include methyl, ethyl, and propyl groups. Examples of alkoxy groups include methoxy, ethoxy, and propoxy groups.

[0042] Polymer G is typically a polyimide. That is, crosslinked polymer Q is typically a crosslinked polyimide. The polyimide is preferably a polyimide P containing constituent units A1 derived from a tetracarboxylic dianhydride a1 having a six-membered ring acid anhydride structure S. The polyimide P further preferably contains constituent units B derived from a diamine.

[0043] The constituent unit A1 derived from tetracarboxylic dianhydride a1 is a constituent unit suitable for improving the permeability coefficient and permeability rate of acidic gases that permeate the separation functional layer 1. Tetracarboxylic dianhydride a1 has, for example, one or more, preferably two, acid anhydride structures S. The six-membered ring acid anhydride structure S is typically a glutaric acid anhydride structure represented by the following formula (1).

[0044] Tetracarboxylic acid dianhydride a1 may have a fused ring, and the fused ring may contain an acid anhydride structure S. The fused ring may contain an aromatic ring together with the acid anhydride structure S. The aromatic ring contained in the fused ring may consist only of carbon atoms and hydrogen atoms, or it may be a heteroaromatic ring containing heteroatoms such as oxygen atoms, nitrogen atoms, and sulfur atoms. The aromatic ring may be polycyclic or monocyclic. The number of carbon atoms in the aromatic ring is not particularly limited, and is, for example, 4 to 14. Specific examples of aromatic rings include benzene rings, naphthalene rings, anthracene rings, phenanthrene rings, fluorene rings, furan rings, pyrrole rings, pyridine rings, and thiophene rings.

[0045] The fused ring may or may not have substituents. Substituents of the fused ring are not particularly limited and include halogen groups and hydrocarbon groups. Examples of halogen groups include fluoro groups, chloro groups, bromo groups, and iodo groups. The number of carbon atoms in the hydrocarbon group is not particularly limited, for example, 1 to 15. Examples of hydrocarbon groups are alkyl groups such as methyl groups, ethyl groups, and propyl groups. The hydrocarbon group may also be a halogenated hydrocarbon group in which a hydrogen atom is substituted with a halogen group. When the fused ring has multiple substituents, the substituents may or may not be the same.

[0046] The tetracarboxylic dianhydride a1 is preferably represented by the following formula (a1).

[0047] In equation (a1), R 1a ~R 4a These are, independently of each other, a hydrogen atom or any substituent. The substituents are not particularly limited and include halogen groups, hydrocarbon groups, etc. Examples of halogen groups and hydrocarbon groups are those mentioned above.

[0048] In polyimide P, the constituent unit A1 derived from tetracarboxylic dianhydride a1 is preferably represented by the following formula (A1). The constituent unit A1 represented by formula (A1) is derived from the tetracarboxylic dianhydride a1 represented by the above formula (a1). In formula (A1), the nitrogen atom contained in the imide group is derived from the diamine formed by the reaction with tetracarboxylic dianhydride a1.

[0049] In equation (A1), R 1a ~R 4a These are the same as in formula (a1), and are independently hydrogen atoms or any substituent. A specific example of the constituent unit A1 represented by formula (A1) is shown in formula (A1-1) below.

[0050] In polyimide P, the ratio p1 of the amount of substance of the above-mentioned constituent unit A1 to the amount of substance of all constituent units A derived from tetracarboxylic dianhydride is, for example, 50 mol% or more, and may be 70 mol% or more, 90 mol% or more, 95 mol% or more, or even 99 mol% or more. Polyimide P may contain only the above-mentioned constituent unit A1 as the constituent unit A derived from tetracarboxylic dianhydride. However, polyimide P may further contain constituent unit A2 derived from tetracarboxylic dianhydride a2 having a five-membered ring acid anhydride structure, in addition to constituent unit A1. The tetracarboxylic dianhydride a2 is not particularly limited, and examples include pyromellitic dianhydride and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride.

[0051] As described above, polyimide P preferably further contains constituent units B derived from diamine. Diamine is a compound having two primary amino groups. Diamine may or may not contain other functional groups other than primary amino groups. Examples of other functional groups include carboxyl groups, hydroxyl groups, thiol groups, and sulfonyl groups. Diamine may have at least one functional group f selected from the group consisting of carboxyl groups, hydroxyl groups, and thiol groups.

[0052] The diamine preferably has an aromatic ring. That is, the constituent unit B preferably has an aromatic ring. The crosslinked polyimide may be formed by the carbon atoms constituting the aromatic ring contained in the constituent unit B being bonded to a hydrocarbon group (e.g., an alkylene group), thereby crosslinking the polyimide P via the hydrocarbon group. The constituent unit B may have an electron-donating group, and the electron-donating group may be bonded to the aromatic ring. Examples of electron-donating groups are those mentioned above. The polyimide P may contain a plurality of different constituent units B derived from the diamine. For example, the constituent unit B may include a constituent unit having an electron-donating group and a constituent unit not having an electron-donating group. The constituent unit not having an electron-donating group may contain a functional group f.

[0053] Examples of aromatic rings include those described above for tetracarboxylic dianhydride a1. In the diamine, the substituents of the aromatic ring include, for example, a primary amino group. The aromatic ring may have substituents other than those containing a primary amino group, or it may not have any substituents. Other substituents are not particularly limited and include groups containing the functional group f described above, halogen groups, electron-donating groups, etc. Examples of halogen groups include those described above for tetracarboxylic dianhydride a1. Examples of electron-donating groups include those described above. In the diamine, other substituents may include photopolymerizable functional groups (for example, vinyl groups).

[0054] Diamines can be represented, for example, by the following formulas (b1), (b2), (b3), (b4), or (b5).

[0055] In formulas (b1) to (b5), R 1b to R 30b are, independently of one another, a hydrogen atom or an arbitrary substituent. The arbitrary substituent is, for example, a group containing a functional group f, a halogen group, an electron-donating group, etc. Examples of the halogen group and the electron-donating group include those described above.

[0056] In formula (b3), R 10b and R 13b may be bonded to each other to form a ring, and R 12b and R 15b may be bonded to each other to form a ring. In formula (b4), R 17b and R 21b may be bonded to each other to form a ring, and R 20b and R 22b may be bonded to each other to form a ring.

[0057] In formulas (b3) and (b4), X 1 [[ID=2 nine]] and X 2 is a single bond or an arbitrary linking group. The arbitrary linking group is, for example, a divalent hydrocarbon group. Examples of the divalent hydrocarbon group include alkylene groups such as a methylene group, an ethylene group, a propane-1,3-diyl group, and a propane-2,2-diyl group. The divalent hydrocarbon group may be a halogenated hydrocarbon group in which a hydrogen atom is substituted with a halogen group. The divalent hydrocarbon group may further have an aromatic ring. Examples of the aromatic ring include those described above for the tetracarboxylic dianhydride a1. The divalent hydrocarbon group may be a fluorenediyl group. X 1 and X 2 may contain a functional group such as an ether group or an ester group together with the divalent hydrocarbon group or in place of the divalent hydrocarbon group.

[0058] The structural unit B derived from the diamine is represented by, for example, the following formula (B1), formula (B2), formula (B3), formula (B4), or formula (B5). The structural unit B represented by formulas (B1) to (B5) is derived from the diamines represented by the above formulas (b1) to (b5), respectively.

[0059] In equation (B1), R 1b ~R 4b These are, independently of each other, a hydrogen atom or any substituent. In formula (B1), any substituent is, for example, a group containing a functional group f, a halogen group, or an electron-donating group. Examples of halogen groups and electron-donating groups are those mentioned above.

[0060] Specific examples of the constituent unit B represented by formula (B1) include the following formulas (B1-1) to (B1-6).

[0061] In equation (B2), R 5b ~R 8b These are, independently of each other, a hydrogen atom or any substituent. In formula (B2), any substituent is, for example, a group containing a functional group f, a halogen group, or an electron-donating group. Examples of halogen groups and electron-donating groups are those mentioned above. Specific examples of the constituent unit B represented by formula (B2) are shown in formulas (B2-1) to (B2-2) below.

[0062] In equation (B3), R 9b ~R 16b Each is independently a hydrogen atom or any substituent, and X 1 R is a single bond or any linking group. In formula (B3), any substituent is, for example, a group containing a functional group f, a halogen group, an electron-donating group, etc. Examples of halogen groups and electron-donating groups are those mentioned above. In formula (B3), R 10b and R 13b They may be bonded to each other to form a ring, R 12b and R 15b They may be joined to each other to form a ring.

[0063] X in equation (B3) 1 In this, any linking group is, for example, a divalent hydrocarbon group. Examples of divalent hydrocarbon groups include those mentioned above. 1 It may contain a divalent hydrocarbon group, or, in place of the divalent hydrocarbon group, a functional group such as an ether group or an ester group.

[0064] Specific examples of constituent unit B represented by formula (B3) include the following formulas (B3-1) to (B3-18).

[0065] In equation (B4), R 17b ~R 24b Each is independently a hydrogen atom or any substituent, and X 2 R is a single bond or any linking group. In formula (B4), any substituent is, for example, a group containing a functional group f, a halogen group, an electron-donating group, etc. Examples of halogen groups and electron-donating groups are those mentioned above. In formula (B4), R 17b and R 21b They may be bonded to each other to form a ring, R 20b and R 22b They may be joined to each other to form a ring.

[0066] X in equation (B4) 2 In this, any linking group is, for example, a divalent hydrocarbon group. Examples of divalent hydrocarbon groups include those mentioned above. 2 It may contain a divalent hydrocarbon group, or, in place of the divalent hydrocarbon group, a functional group such as an ether group or an ester group.

[0067] Specific examples of the constituent unit B represented by formula (B4) include the following formulas (B4-1) to (B4-5).

[0068] In equation (B5), R 25b ~R 30b These are, independently of each other, a hydrogen atom or any substituent. In formula (B5), any substituent is, for example, a group containing a functional group f, a halogen group, or an electron-donating group. Examples of halogen groups and electron-donating groups are those mentioned above. The constituent unit B represented by formula (B5) is suitable for improving the rigidity of polyimide P. With polyimide P having excellent rigidity, it is possible to suppress plasticization of the separation functional layer 1 even when the pressure of the mixed gas to be separated is high.

[0069] Specific examples of constituent unit B represented by formula (B5) include the following formulas (B5-1) to (B5-2).

[0070] In polyimide P, constituent units A derived from tetracarboxylic dianhydride and constituent units B derived from diamine are arranged alternately. Examples of adjacent constituent unit combinations of A and B in polyimide P include the following formulas (A1-B3) and (A1-B5). Note that in these formulas, R 1a ~R 4a , R 9b ~R 16b , and R 25b ~R 30b The same applies to formulas (A1), (B3), and (B5) as described above. Polyimide P may include the configuration represented by the following formulas (A1-B3) and the configuration represented by the following formulas (A1-B5).

[0071] The weight-average molecular weight (Mw) of polyimide P is, for example, 30,000 or more, preferably 50,000 or more, and more preferably 75,000 or more, from the viewpoint of the mechanical strength of the separation functional layer 1. The upper limit of the weight-average molecular weight of polyimide P is not particularly limited, but is, for example, 300,000. The weight-average molecular weight of polyimide P can be calculated, for example, by measuring the molecular weight distribution of polyimide P using a gel permeation chromatograph (GPC) equipped with a differential refractive index detector (RID), and then using a calibration curve with standard polystyrene from the obtained chromatogram (chart).

[0072] The content of the crosslinked polymer Q in the separation functional layer 1 is, for example, 50 wt% or more, and may be 60 wt% or more, 70 wt% or more, or even 80 wt% or more, or 90 wt% or less. In addition to the crosslinked polymer Q, the separation functional layer 1 may also contain an uncrosslinked polymer G (for example, an uncrosslinked polyimide P). The total content of the crosslinked polymer Q and the uncrosslinked polymer G in the separation functional layer 1 is, for example, 50 wt% or more, and may be 60 wt% or more, 70 wt% or more, or even 80 wt% or more, or 90 wt% or less.

[0073] (Particle M) The separation functional layer 1 contains particles M. The particles M are dispersed in a matrix containing a crosslinked polymer Q. The particles M may be spaced apart from each other in the matrix, or they may be partially aggregated. The particles M are bonded to the crosslinked polymer Q, preferably via a second linking group (crosslinked).

[0074] The particle M is preferably a particle that can be crosslinked with a crosslinking polymer Q and a crosslinking agent, and examples include porous particles, surface-modified inorganic particles, and metal-organic frameworks (MOFs). Surface-modified inorganic particles are, for example, silica particles having a surface modified by a modifying group, the modifying group may be an aryl group, or it may have a benzene ring having an electron-donating group. The MOF may contain an organic ligand which is a benzene ring, preferably a benzene ring having an electron-donating group. The particle M preferably has a carbon atom to which the second linking group is bonded.

[0075] Particle M is preferably a porous particle. Porous particles typically contain organic materials. Preferably, porous particles contain organic polymers. Preferably, porous particles do not contain metal elements. Preferably, porous particles consist only of organic polymers. The molecular weight of the organic polymer is, for example, 10,000 or more. Typically, the bonds contained in the organic polymer consist only of covalent bonds.

[0076] The organic polymer may contain an aromatic ring. The aromatic ring may consist only of carbon atoms and hydrogen atoms, or it may be a heteroaromatic ring containing heteroatoms such as oxygen atoms, nitrogen atoms, and sulfur atoms. The aromatic ring may be polycyclic or monocyclic. The number of carbon atoms in the aromatic ring is not particularly limited, for example, 4 to 14. Specific examples of aromatic rings include benzene rings, naphthalene rings, anthracene rings, phenanthrene rings, fluorene rings, furan rings, pyrrole rings, pyridine rings, and thiophene rings. The organic polymer preferably contains a benzene ring.

[0077] The organic polymer may contain an aromatic ring and a linking group that connects two or more aromatic rings. The linking group may be, for example, a chain-like hydrocarbon group or a quaternary carbon atom. The chain-like hydrocarbon group is, for example, a divalent hydrocarbon group. Examples of divalent hydrocarbon groups include alkylene groups such as a methylene group, an ethylene group, a propane-1,3-diyl group, and a propane-2,2-diyl group, with the methylene group being preferred.

[0078] Organic polymers may have functional groups. Examples of functional groups include amino groups and hydroxyl groups. Functional groups may be bonded to aromatic rings.

[0079] Organic polymers are typically porous polymers. Therefore, porous particles are typically porous organic polymer particles. Porous particles may also be porous polymer microparticles.

[0080] The porous polymer is preferably at least one selected from the group consisting of porous aromatic frames (PAFs) and hypercrosslinked polymers (HCPs). A PAF is a porous frame composed of linked aromatic ring connectors, and has a regular structure in which multiple aromatic ring connectors are linked by direct bonding between aromatic rings via carbon-carbon covalent bonds. An HCP is a porous polymer composed of multiple aromatic rings crosslinked by hydrocarbon linking groups such as -CH2-.

[0081] PAFs are typically obtained by polymerizing monomers that are aromatic ring linkers having reactive groups. The number of reactive groups in the monomer may be, for example, 1 to 6, 2 to 5, or 3 to 4, and is preferably 4. The reactive groups are preferably halogen groups. Examples of halogen groups include fluoro groups, chloro groups, bromo groups, and iodine groups.

[0082] The monomers used in the synthesis of PAF are, for example, tetrakis(4-bromophenyl)methane, tetrakis(4-chlorophenyl)methane, and their derivatives. For example, PAF obtained by monopolymerizing or copolymerizing at least one selected from the group consisting of tetrakis(4-bromophenyl)methane and tetrakis(4-chlorophenyl)methane (hereinafter referred to as "PAF-1") has a structural unit represented by the following formula (2). PAF can be synthesized, for example, by coupling the above-mentioned group of monomers.

[0083] HCP is typically obtained by polymerizing monomers that are aromatic hydrocarbons having reactive groups. The number of reactive groups may be, for example, 1 to 6, 2 to 4, or 2 to 3, and is preferably 2. The reactive groups are preferably halogen groups. Examples of halogen groups include fluoro groups, chloro groups, bromo groups, and iodo groups. The aromatic hydrocarbon may further have other substituents besides the reactive groups. Examples of other substituents include hydrocarbon groups, amino groups, and hydroxyl groups. The number of carbon atoms in the hydrocarbon group is not particularly limited, and is, for example, 1 to 15. Examples of hydrocarbon groups are alkyl groups such as methyl groups, ethyl groups, propyl groups, and butyl groups. The number of other substituents is not particularly limited, and is, for example, 1 to 3.

[0084] The monomers used in the synthesis of HCP are, for example, α,α'-dichloro-p-xylene, α,α'-dichloro-m-xylene, α,α'-dibromo-p-xylene, α,α'-dibromo-m-xylene, benzyl chloride, and derivatives thereof. The derivatives are typically compounds in which at least one hydrogen atom of the benzene ring in the above monomer is substituted with a substituent. Examples of such substituents include those mentioned above. Examples of derivatives include 2,4-bis(chloromethyl)-1,3,5-trimethylbenzene, 4-tert-butylbenzyl chloride, and 4-(chloromethyl)benzyl alcohol. HCP may be a monopolymer of one of the above monomers, or a copolymer of two or more of them.

[0085] For example, HCP obtained by monopolymerizing or copolymerizing at least one selected from the group consisting of α,α'-dichloro-p-xylene, α,α'-dichloro-m-xylene, α,α'-dibromo-p-xylene, and α,α'-dibromo-m-xylene (hereinafter referred to as "pDCX") has a structural unit represented by the following formula (3). HCP obtained by copolymerizing at least one selected from the group consisting of α,α'-dichloro-p-xylene, α,α'-dichloro-m-xylene, α,α'-dibromo-p-xylene, and α,α'-dibromo-m-xylene with 2,4-bis(chloromethyl)-1,3,5-trimethylbenzene (hereinafter referred to as "p(DCX-co-TMDCX)") has a structural unit represented by the following formula (4). HCP (hereinafter referred to as "p(DCX-co-tBuBnC)") obtained by copolymerizing at least one selected from the group consisting of α,α'-dichloro-p-xylene, α,α'-dichloro-m-xylene, α,α'-dibromo-p-xylene, and α,α'-dibromo-m-xylene with 4-tert-butylbenzyl chloride has a constituent unit represented by the following formula (5).

[0086] In formula (3), although not shown, the C-H in the benzene ring may be linked to other structural units represented by formula (3). That is, the carbon atoms constituting the C-H may be linked to a linker (typically a methylene group) that links structural units represented by formula (3). Similarly, in formula (4), the C-H in the benzene ring may be linked to other structural units represented by formula (4). In formula (5), the C-H in the benzene ring may be linked to other structural units represented by formula (5).

[0087] The above-mentioned HCPs can be synthesized, for example, by performing a Friedel-Crafts alkylation reaction on the monomer group described above.

[0088] Porous particles may be surface-modified. That is, porous particles may have a surface modified with a modifying group. Examples of modifying groups include amino groups and hydroxyl groups. Porous particles may contain HCP having constituent units represented by the following formulas (6) to (7). Typically, the constituent units represented by the following formulas (6) to (7) are contained near the surface of the porous particles.

[0089] In this specification, HCP having a constituent unit represented by formula (6) is described as pDCX-OH, and HCP having a constituent unit represented by formula (7) is described as pDCX-NH2. pDCX-OH may have a constituent unit represented by formula (3), a constituent unit represented by formula (4), or a constituent unit represented by formula (5), and a constituent unit represented by formula (6). pDCX-NH2 may have a constituent unit represented by formula (3), a constituent unit represented by formula (4), or a constituent unit represented by formula (5), and a constituent unit represented by formula (7).

[0090] The average particle size of particle M is, for example, 1000 nm or less, preferably 500 nm or less, and more preferably 200 nm or less. The lower limit of the average particle size of particle M is, for example, 1 nm. That is, it is preferable that particle M is a nanoparticle. The average particle size of particle M can be determined by the following method. First, a cross-section of the separation functional layer 1 is observed with a scanning electron microscope. In the obtained electron microscope image, the area of ​​a specific particle M (for example, a porous particle) is calculated by image processing. The diameter of a circle having the same area as the calculated area is considered to be the particle size (diameter of the particle) of that specific particle M. The particle size of any number of particles M (at least 50) is calculated, and the average of the calculated values ​​is considered to be the average particle size of particle M.

[0091] The shape of the particle M is not particularly limited and may be spherical, ellipsoidal, flaky, or fibrous.

[0092] The specific surface area of ​​particle M is, for example, 10 m². 2 It is 100m or more / g, preferably 100m 2 It is 500m or more per g, and more preferably 500m 2It is 1000m or more per gram, and more preferably 1000m 2 It is greater than or equal to / g. The upper limit of the specific surface area of ​​particle M is, for example, 100,000 m². 2 The value is / g. The specific surface area of ​​particle M can be measured, for example, by the BET adsorption method using nitrogen gas adsorption.

[0093] The particles M in the separation functional layer 1 may be 1 wt% to 50 wt% relative to the crosslinked polymer Q, or 3 wt% to 50 wt%, 5 wt% to 30 wt%, 5 wt% to 25 wt%, and even 10 wt% to 20 wt%. The particles M in the separation functional layer 1 may be 1 wt% to 50 wt% relative to the total amount of the crosslinked polymer Q and the uncrosslinked polymer G, or 3 wt% to 50 wt%, 5 wt% to 30 wt%, 5 wt% to 25 wt%, and even 10 wt% to 20 wt%. In addition to the particles M, the separation functional layer 1 may also contain uncrosslinked particles M (for example, uncrosslinked porous particles) that are not bonded to the crosslinked polymer Q. The total content of particles M bound to the crosslinked polymer Q and uncrosslinked particles M in the separation functional layer 1 may be, for example, 5 wt% to 50 wt%, 5 wt% to 30 wt%, 5 wt% to 25 wt%, or even 10 wt% to 20 wt%.

[0094] (Other) The total content of crosslinked polymer Q (and uncrosslinked polymer G) and particles M (and uncrosslinked particles M) in the separation functional layer 1 is, for example, 50 wt% or more, and may be 60 wt% or more, 70 wt% or more, 80 wt% or more, 90 wt% or more, and even 95 wt% or more, and may be 100 wt% or less. The separation functional layer 1 may consist substantially only of crosslinked polymer Q, polymer G, and particles M, or substantially only of crosslinked polymer Q and particles M. The separation functional layer 1 may further contain other components. Other components include nanoparticles different from the particles M described above. Examples of such nanoparticles include those exemplified in the intermediate layer 2 described later. In the separation functional layer 1, the nanoparticles are dispersed in a matrix containing crosslinked polymer Q, for example. The nanoparticles may be spaced apart from each other in the matrix, or they may be partially aggregated.

[0095] (Method for manufacturing the separation functional layer) The method for manufacturing the separation functional layer 1 includes reacting the carbon atoms of polymer G with a first crosslinking agent to obtain a crosslinked polymer Q, reacting particles M and crosslinked polymer Q (or polymer G) with a second crosslinking agent to bond (crosslink) them, and producing a separation functional layer 1 containing the crosslinked polymer Q and particles M. As described above, polymer G is preferably polyimide P.

[0096] A method for manufacturing the separation functional layer 1 preferably includes applying a coating solution L1 containing polyimide P and particles M onto a substrate to form a coating film, and drying the coating film to obtain a film containing polyimide P and particles M. The film is immersed in a liquid L2 containing a first crosslinking agent and a second crosslinking agent to react the carbon atoms of polyimide P with the first crosslinking agent, and to react the crosslinked polyimide (or polyimide P) and particles M with the second crosslinking agent. After the reaction, the film is washed and dried to obtain the separation functional layer 1 containing crosslinked polyimide and particles M bonded to the crosslinked polyimide.

[0097] The order in which polymer G (polyimide P) is crosslinked to obtain crosslinked polymer Q (crosslinked polyimide) and the particles M and crosslinked polymer Q is not limited. Crosslinked polymer Q may be produced first, and then the crosslinked polymer Q and particles M may be crosslinked, or polymer G and particles M may be crosslinked first, and then polymer G is crosslinked to produce crosslinked polymer Q. Crosslinking polymer G (polyimide P) to obtain crosslinked polymer Q (crosslinked polyimide) and the crosslinking of particles M and crosslinked polymer Q may be performed simultaneously.

[0098] Polyimide P can be prepared, for example, by the following method. First, a diamine is dissolved in a solvent to obtain a solution. Examples of solvents include N-methyl-2-pyrrolidone, nitrobenzene, benzonitrile, α-chloronaphthalene, phenol, m-cresol, and p-chlorophenol.

[0099] Next, the group of tetracarboxylic dianhydrides, including the tetracarboxylic dianhydride a1 mentioned above, is gradually added to the obtained solution. This causes the monomer group, which includes tetracarboxylic dianhydride a1 and diamine, to react and form polyamic acid. The addition of the tetracarboxylic dianhydride group is carried out, for example, under stirring conditions for 3 to 20 hours in a heated environment of 140°C or higher. Polyimide P can be obtained by imidizing the polyamic acid. Examples of imidizing methods include chemical imidization and thermal imidization. Chemical imidization is a method of imidizing polyamic acid using a dehydrating condensation agent, for example, under room temperature conditions. Examples of dehydrating condensation agents include acetic anhydride, pyridine, and triethylamine. Thermal imidization is a method of imidizing polyamic acid by heat treatment. The temperature of the heat treatment is, for example, 180°C or higher. The reaction of polyamic acid formation and the imidization of polyamic acid may proceed in parallel. The reaction of polyimide P formation (imidization) may be carried out in the presence of a catalyst that promotes the formation of polyimide. Examples of such catalysts include aromatic carboxylic acids such as benzoic acid and p-hydroxybenzoic acid, and aromatic amines such as isoquinoline.

[0100] The polyimide P content in the coating solution L1 can be appropriately adjusted according to the solubility of polyimide P, for example, from 1 wt% to 30 wt%.

[0101] The content of particles M in the coating solution can be adjusted as appropriate, and is, for example, 1 wt% to 50 wt% relative to polyimide P, preferably 5 wt% to 50 wt%, and more preferably 5 wt% to 20 wt%.

[0102] The coating solution L1 preferably further contains a solvent. The solvent is typically a good solvent capable of dissolving polyimide P. Examples of solvents include amide compounds, lactone compounds, 1,3-dioxolane, nitrobenzene, benzonitrile, α-chloronaphthalene, phenol, m-cresol, p-chlorophenol, etc. The solvent preferably contains at least one selected from the group consisting of amide compounds and lactone compounds, and more preferably contains an amide compound. Examples of amide compounds include N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), and N,N-dimethylacetamide (DMAc). Examples of lactone compounds include γ-butyrolactone.

[0103] The solvent content in the coating solution L1 is not particularly limited, and is, for example, 30 wt% to 99 wt%.

[0104] The coating solution L1 may further contain a surfactant (leveling agent) to improve coating properties. However, according to the inventors' studies, when the coating solution L1 contains a surfactant, the separation performance of the prepared separation functional layer 1 tends to decrease. Therefore, it is preferable that the coating solution L1 does not contain a surfactant.

[0105] The substrate to which the coating solution L1 containing polyimide P is applied is typically a release liner or glass. Examples of substrates include soda glass; films containing resin; paper; and sheets containing metal materials such as aluminum or stainless steel. Sheets containing metal materials tend to have high heat resistance. The substrate is preferably a film containing resin, or a laminate of such film and soda glass, from the viewpoint of excellent surface smoothness. Examples of polymers contained in the resin of the substrate include polyolefins such as polyethylene, polypropylene, polybutene, polybutadiene, and polymethylpentene; polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyvinyl chloride, vinyl chloride copolymer; polyurethane; ethylene-vinyl acetate copolymer; and polyimide, with polyimide being preferred.

[0106] The surface of the substrate may be treated with a release agent. The release agent can be applied to the surface of the substrate by applying a release agent. Examples of release agents include silicone-based release agents, long-chain alkyl-based release agents, fluorine-based release agents, and molybdenum sulfide-based release agents. The release agents may be used individually or in combination of two or more. The substrate may be a polyimide film that has been treated with a release agent.

[0107] The thickness of the substrate is not particularly limited, and is, for example, 5 μm to 100 μm, preferably 10 μm to 50 μm.

[0108] Furthermore, a surface modification treatment may be performed on the substrate before applying the coating solution L1. If the substrate has been subjected to a stripping treatment, the surface modification treatment may be performed on the surface of the substrate that has been stripped. Examples of surface modification treatments include corona treatment, plasma treatment, excimer treatment, and flame treatment, with corona treatment being preferred.

[0109] Surface modification can be performed by irradiating the surface of the substrate with active energy rays. Specific examples of active energy rays include electron beams, ion beams, plasma beams, and ultraviolet rays. When corona treatment is used as a surface modification treatment, the discharge rate is, for example, 0.1 kW·min / m2 That concludes the explanation. The upper limit of the discharge rate is not particularly limited; for example, 10 kW·min / m 2 That is the case.

[0110] The method of applying the coating solution L1 to the substrate is not particularly limited, and for example, spin coating, dip coating, slot die coating, etc., can be used. The coating solution L1 may also be applied to the substrate using an applicator or wire bar. The coating solution L1 may be applied to the surface of a substrate that has undergone stripping treatment or surface modification treatment.

[0111] A coating film is formed by applying the coating solution L1 to the substrate. The thickness of the coating film can be appropriately adjusted according to the desired thickness of the separation functional layer 1, for example, from 1 μm to 100 μm.

[0112] The drying conditions for the coated film are not particularly limited; for example, the drying temperature may be 50°C to 200°C and the drying time may be 1 minute to 10 hours. The coated film can be dried using a heater or the like. As an example, the coated film may be dried by passing it through a heating section equipped with a heater. The coated film may also be dried by passing it through multiple heating sections. The set temperatures of the multiple heating sections may be the same or different.

[0113] In the method for manufacturing the separation functional layer 1 of this embodiment, it is preferable to further include removing the substrate from the laminate after drying the coating film on the substrate to obtain a laminate of polyimide P film and substrate, and before immersing the film in liquid L2 containing the first crosslinking agent and the second crosslinking agent. By removing the substrate, a self-supporting film of polyimide P can be obtained, and this self-supporting film can be immersed in liquid L2 containing the first crosslinking agent and the second crosslinking agent.

[0114] The first crosslinking agent preferably comprises a diether compound. In the production method according to this embodiment, the diether compound is of formula R 2 O-R 1 -OR 3 It is represented as R 1 , R 2 and R 3When each of these groups is an arbitrary hydrocarbon group independently of the others, the carbon atoms of polymer G (polyimide P) react with the first crosslinking agent, causing multiple polymer G (polyimide P) molecules to interact with each other. 1 Bridged via R. 1 It bonds with the carbon atoms of polymer G (polyimide P). In this way, a crosslinked polymer Q (crosslinked polyimide) can be obtained. Preferably, R 1 is a divalent hydrocarbon group, R 2 and R 3 These are monovalent hydrocarbon groups, independent of each other.

[0115] Examples of diether compounds include dimethoxymethane, methoxyethoxymethane, diethoxymethane, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1-methoxy-2-ethoxyethane, 1,2-diisopropoxyethane, 1,3-dimethoxypropane, 1,3-diethoxypropane, and 1,3-diisopropoxypropane, with dimethoxymethane being preferred.

[0116] The reaction between the carbon atoms of polymer G and the first crosslinking agent is typically carried out in the presence of a catalyst. The catalyst is preferably a Lewis acid catalyst. Examples of Lewis acid catalysts include iron(III) chloride, iron(III) bromide, and aluminum chloride.

[0117] The second crosslinking agent preferably comprises a diether compound. Examples of diether compounds include those mentioned above. The diether compound may have the formula R 2 O-R 1 -OR 3 It is represented as R 1 , R 2 and R 3 When these are any hydrocarbon groups independently of each other, by reacting, for example, the carbon atoms of the crosslinked polymer Q (or polymer G) with the second crosslinking agent and the particles M, the crosslinked polymer Q (or polymer G) and the particles M become R 1 Bridged via R. 1It is preferable that the carbon atoms of the crosslinked polymer Q (or polymer G) bond to the carbon atoms of both the crosslinked polymer Q (or polymer G) and the particles M.

[0118] The reaction between the crosslinked polymer Q (or polymer G) and particles M and the second crosslinking agent is typically carried out in the presence of a catalyst. The catalyst is preferably a Lewis acid catalyst. Examples of Lewis acid catalysts include iron(III) chloride, iron(III) bromide, aluminum chloride, and the like.

[0119] The first crosslinking agent and the second crosslinking agent may be the same. This makes it easy to simultaneously produce the crosslinked polymer Q and bond the crosslinked polymer Q and particles M, allowing for the simple production of the separation functional layer 1. Hereinafter, the first crosslinking agent and the second crosslinking agent may be collectively referred to as "crosslinking agent".

[0120] The liquid L2 containing the crosslinking agent preferably further contains a catalyst and a solvent. Examples of solvents include 1,2-dichloroethane and acetonitrile. Examples of catalysts include those mentioned above.

[0121] The crosslinking agent content in liquid L2 is, for example, 0.1 w / v% to 20 w / v% relative to the volume of the solvent.

[0122] The catalyst content in liquid L2 is not particularly limited, and is, for example, 0.1 w / v% to 20 w / v% relative to the volume of the solvent.

[0123] The conditions for immersing a film containing polyimide P and particles M in liquid L2, i.e., the conditions for the above reaction, are, for example, a temperature of 20°C to 80°C and a time of 0.2 hours to 10 hours.

[0124] After removing the reaction-resulting film from liquid L2, it is preferable to wash the film. Subsequently, by drying the film, a separation functional layer 1 that functions as a self-supporting film can be obtained.

[0125] The drying conditions are not particularly limited; for example, the drying temperature is 50°C to 200°C and the drying time is 1 minute to 10 hours. The film after the reaction can be dried, for example, by the same means as the drying of the coating film described above.

[0126] The manufacturing method of this embodiment may also include further heat treatment (annealing) of the obtained separation functional layer 1. This step tends to improve the separation performance of the separation functional layer 1 and also suppress the deterioration of the separation performance of the separation functional layer 1 over time. This step also makes it possible to obtain a separation functional layer 1 that contains almost no residual solvent by allowing the solvent to evaporate sufficiently. The annealing treatment may be performed before removing the substrate from the laminate of the separation functional layer 1 and the substrate, or after removing the substrate.

[0127] The heat treatment temperature may be higher than, for example, 200°C, 230°C or higher, or even 250°C or higher. The upper limit of the heat treatment temperature is not particularly limited and may be, for example, 350°C or lower, or 300°C or lower. The heat treatment time may be, for example, 1 minute or more, 10 minutes or more, or 30 minutes or more. The upper limit of the heat treatment time is not particularly limited and may be, for example, 24 hours or lower.

[0128] The manufacturing method of this embodiment is not limited to those described above. Instead of the coating solution L1 containing polyimide P and particles M, a coating solution containing polyamic acid, a precursor of polyimide P, and particles M may be used. A film containing polyimide P and particles M may be prepared by applying this coating solution onto a substrate and imidizing the polyamic acid to form polyimide P. Alternatively, the substrate may be immersed in liquid L2 without removing it from the laminate of the film containing polyimide P and particles M and the substrate to carry out a crosslinking reaction, and then washed and dried to form a separation functional layer 1 on the substrate. In this case, it is preferable to further include removing the substrate from the laminate of the separation functional layer 1 and the substrate. By removing the substrate, a separation functional layer 1 that functions as a self-supporting film can be obtained.

[0129] (Characteristics of the separation function layer) As described above, the separation function layer 1 preferably allows acidic gases contained in the mixed gas to permeate preferentially. As an example, when a mixed gas consisting of carbon dioxide and methane is supplied to a space adjacent to one side of the separation function layer 1 using the separation function layer 1 in its initial state, the permeation rate T1 of carbon dioxide permeating through the separation function layer 1 is, for example, 70 GPU or more, and may be 80 GPU or more, 90 GPU or more, 100 GPU or more, 150 GPU or more, or even 200 GPU or more. The upper limit of the permeation rate T1 is not particularly limited, and is, for example, 1000 GPU. Note that GPU is 10 -6 ・cm 3 (STP) / (sec・cm 2 This means (cmHg).

[0130] Furthermore, as an example, when a mixed gas consisting of carbon dioxide and methane is supplied to the space adjacent to one side of the separation functional layer 1 using the separation functional layer 1 in its initial state, the permeation coefficient C1 of carbon dioxide that permeates through the separation functional layer 1, taking into account the thickness of the separation functional layer 1, is, for example, 500 Barre or more, and may be 700 Barre or more, 1000 Barre or more, 1200 Barre or more, or even 1500 Barre or more. The upper limit of the permeation coefficient C1 is not particularly limited, and is, for example, 10000 Barre. Note that Barre is 10 -10 ・cm 3 (STP)・cm / (sec・cm 2 This means cmHg. 3 (STP) represents the volume of carbon dioxide at 1 atmosphere and 0°C. The permeability coefficient C1 [Barrer] is the value obtained by multiplying the permeability rate T1 [GPU] by the thickness (μm) of the separation functional layer 1.

[0131] The permeation coefficient C1 and permeation rate T1 can be determined by the following method. First, a mixed gas consisting of carbon dioxide and methane is supplied to a space adjacent to one side of the separation functional layer 1, and argon gas as a sweep gas is injected to a space adjacent to the other side of the separation functional layer 1. This yields a permeate fluid that has permeated through the separation functional layer 1. The weight of the permeate fluid, as well as the volume ratio of carbon dioxide and methane in the permeate fluid, are measured. The permeation coefficient C1 and permeation rate T1 can be calculated from the measurement results. In the above operation, the concentration of carbon dioxide in the mixed gas is 50 vol% under standard conditions (0°C, 101 kPa). The mixed gas supplied to the space adjacent to one side of the separation functional layer 1 has a temperature of 30°C and a pressure of 0.1 MPa.

[0132] In the above-described measurement conditions for the permeation coefficient C1 and permeation rate T1, the separation coefficient α1 of carbon dioxide relative to methane in the initial separation functional layer 1 is not particularly limited, and may be, for example, 5 or more, or 9 or more. The upper limit of the separation coefficient α1 is not particularly limited, and may be, for example, 100 or 60. The separation coefficient α1 can be calculated from the following formula. However, in the following formula, the permeation rate T1 CH4 This is the transmission rate of methane that passes through the separation functional layer 1 in its initial state under the above-described conditions for measuring transmission rate T1. Separation coefficient α1 = transmission rate T1 / transmission rate T1 CH4

[0133] As described above, the separation functional layer 1 of this embodiment contains a crosslinked polymer Q and particles M crosslinked therewith. This enables the separation functional layer 1 of this embodiment to achieve a sufficiently high permeation rate and permeation coefficient for acidic gases. In particular, the physical aging of the polyimide is suppressed in the separation functional layer 1 of this embodiment, thereby preventing a decrease in the separation performance of the separation functional layer 1 over time.

[0134] The separation performance of the separation functional layer 1 after long-term use can be evaluated by the following method. First, the separation functional layer 1 is stored in an environment of 85°C for 500 hours (durability test). After the durability test, the permeation rate T2 and permeation coefficient C2 of carbon dioxide permeating through the separation functional layer 1 are measured using the same method as for the permeation coefficient C1, when a mixed gas consisting of carbon dioxide and methane is supplied to the space adjacent to one side of the separation functional layer 1.

[0135] The transmission rate T2 after the durability test is, for example, 70 GPU or more, and may be 80 GPU or more, 90 GPU or more, 100 GPU or more, 120 GPU or more, or even 140 GPU or more. The upper limit of the transmission rate T2 is not particularly limited, and is, for example, 1000 GPU. The separation functional layer 1 can achieve a good transmission rate T2.

[0136] The permeability coefficient C2 after the durability test is, for example, 500 Barre or more, and may be 550 Barre or more, 600 Barre or more, 700 Barre or more, or even 800 Barre or more. The upper limit of the permeability coefficient C2 is not particularly limited, and is, for example, 10,000 Barre. The separation functional layer 1 can achieve a good permeability coefficient C2.

[0137] The separation coefficient α2 of carbon dioxide to methane in the separation functional layer 1 after the durability test may be, for example, 5 or more, 9 or more, or even 13 or more. The upper limit of the separation coefficient α2 after the durability test is not particularly limited and may be, for example, 100 or 60. The separation coefficient α2 after the durability test can be calculated from the following formula. However, in the following formula, the permeation rate T2 CH4 This is the transmission rate of methane that permeates through the separation functional layer 1 after the durability test under the above-described transmission rate T1 measurement conditions. Separation coefficient α2 = transmission rate T2 / transmission rate T2 CH4

[0138] (Applications of the Separation Functional Layer) One application of the separation functional layer 1 of this embodiment is to separate acidic gases from a gas mixture containing acidic gases. Examples of acidic gases in the gas mixture include carbon dioxide, hydrogen sulfide, carbonyl sulfide, sulfur oxides (SOx), hydrogen cyanide, nitrogen oxides (NOx), and preferably carbon dioxide. The gas mixture contains other gases besides acidic gases. Examples of other gases include nonpolar gases such as hydrogen, nitrogen, and methane, and inert gases such as helium, and preferably nitrogen and methane. In particular, the separation functional layer 1 of this embodiment is suitable for separating carbon dioxide from a gas mixture containing carbon dioxide and methane. However, the applications of the separation functional layer 1 are not limited to separating acidic gases from the above-mentioned gas mixture.

[0139] <Embodiment of Separation Membrane> As shown in Figure 2, the separation membrane 10 of this embodiment comprises the separation functional layer 1 described above and further comprises a porous support 3. As shown in Figure 2, it is preferable that the separation membrane 10 further includes an intermediate layer 2 disposed between the separation functional layer 1 and the porous support 3. The porous support 3 supports the separation functional layer 1. The intermediate layer 2 is in direct contact with both the separation functional layer 1 and the porous support 3. However, in some cases, the separation membrane 10 may not include the intermediate layer 2, and the porous support 3 may be in direct contact with the separation functional layer 1 and support the separation functional layer 1.

[0140] (Intermediate layer) The intermediate layer 2 preferably contains a resin, and more preferably contains nanoparticles dispersed in the resin (matrix). The nanoparticles may be spaced apart from each other in the matrix, or they may be partially aggregated. However, the intermediate layer 2 may not contain nanoparticles and may be substantially composed of resin.

[0141] The matrix material is not particularly limited, and examples thereof include silicone resins such as polydimethylsiloxane; fluorine resins such as polytetrafluoroethylene; epoxy resins such as polyethylene oxide; polyimide resins; polysulfone resins; polyacetylene resins such as polytrimethylsilylpropyne and polydiphenylacetylene; polyolefin resins such as polymethylpentene; polyurethane resins and the like. The matrix preferably contains a silicone resin and a polyurethane resin.

[0142] The nanoparticles may contain an inorganic material or an organic material. Examples of the inorganic material contained in the nanoparticles include silica, titania, and alumina. The nanoparticles preferably contain silica.

[0143] The nanoparticles may have a surface modified with a modifying group containing a carbon atom. The nanoparticles having a surface modified with this modifying group are excellent in dispersibility in the matrix. The nanoparticles are preferably silica nanoparticles that may have a surface modified with a modifying group. The modifying group preferably further contains a silicon atom. In the nanoparticles, the surface modified with the modifying group is preferably represented by the following formulas (I) to (III).

[0144] R in formulas (I) to (III) 1 ~R 6These are hydrocarbon groups that may have substituents independently of each other. The number of carbon atoms in the hydrocarbon group is not particularly limited as long as it is 1 or more. The number of carbon atoms in the hydrocarbon group may be, for example, 25 or less, 20 or less, 10 or less, or 5 or less. In some cases, the number of carbon atoms in the hydrocarbon group may be greater than 25. The hydrocarbon group may be a linear or branched chain hydrocarbon group, or an alicyclic or aromatic cyclic hydrocarbon group. In a preferred embodiment, the hydrocarbon group is a linear or branched alkyl group having 1 to 8 carbon atoms. The hydrocarbon group is, for example, a methyl group or an octyl group, and preferably a methyl group. Examples of substituents on the hydrocarbon group include an amino group and an acyloxy group. An example of an acyloxy group is a (meth)acryloyloxy group.

[0145] In another preferred form, R in formulas (I) to (III) 1 ~R 6 The hydrocarbon group which may have the substituents mentioned above is represented by the following formula (IV). Nanoparticles having a surface modified with a modifying group containing the hydrocarbon group represented by formula (IV) are suitable for improving the permeability coefficient of acidic gases in the separation membrane 10.

[0146] In equation (IV), R 7 This is an alkylene group having 1 to 5 carbon atoms, which may have substituents. The alkylene group may be linear or branched. Examples of alkylene groups include a methylene group, an ethylene group, a propane-1,3-diyl group, a butane-1,4-diyl group, and a pentane-1,5-diyl group, with the propane-1,3-diyl group being preferred. Examples of substituents on the alkylene group include an amide group and an aminoalkylene group.

[0147] In equation (IV), R 8 R is an alkyl or aryl group having 1 to 20 carbon atoms, which may have substituents. The alkyl group may be linear or branched. Examples of substituents on alkyl and aryl groups include amino groups and carboxyl groups. 8is, for example, a 3,5-diaminophenyl group.

[0148] In the nanoparticles, the surface modified by the modifying group is preferably represented by the following formula (V).

[0149] The modifying group is not limited to the structures shown in formulas (I) to (III). The modifying group may contain a polymer chain having a polyamide structure or a polydimethylsiloxane structure instead of R 1 ~R 6 . In the modifying group, it is preferable that this polymer chain is directly bonded to a silicon atom. Examples of the shape of this polymer chain include linear, dendrimer-like, and hyperbranched shapes.

[0150] The method for modifying the surface of the nanoparticles with the modifying group is not particularly limited. As an example, the surface of the nanoparticles can be modified by reacting the hydroxy groups present on the surface of the nanoparticles with a known silane coupling agent. When the modifying group contains a polyamide structure, the surface of the nanoparticles can be modified by the method disclosed in JP-A-2010-222228.

[0151] The average particle size of the nanoparticles is not particularly limited as long as it is on the nanometer order (<1000 nm), for example, 100 nm or less, preferably 50 nm or less, and more preferably 20 nm or less. The lower limit value of the average particle size of the nanoparticles is, for example, 1 nm. The average particle size of the nanoparticles can be specified by the following method. First, the cross-section of the intermediate layer 2 is observed with a transmission electron microscope. In the obtained electron microscope image, the area of a specific nanoparticle is calculated by image processing. The diameter of a circle having the same area as the calculated area is regarded as the particle size (diameter of the particle) of the specific nanoparticle. The particle sizes of an arbitrary number (at least 50) of nanoparticles are calculated respectively, and the average value of the calculated values is regarded as the average particle size of the nanoparticles. The shape of the nanoparticles is not particularly limited and may be spherical, ellipsoidal, scaly, or fibrous.

[0152] The nanoparticle content in the intermediate layer 2 is, for example, 5 wt% or more, preferably 10 wt% or more, and more preferably 15 wt% or more. The upper limit of the nanoparticle content in the intermediate layer 2 is not particularly limited, but is, for example, 30 wt%.

[0153] The thickness of the intermediate layer 2 is not particularly limited, for example, less than 50 μm, preferably 40 μm or less, and more preferably 30 μm or less. The lower limit of the thickness of the intermediate layer 2 is not particularly limited, for example, 1 μm. It is preferable that the intermediate layer 2 is a layer having a thickness of 1 μm or more and less than 50 μm.

[0154] (Porous Support) Examples of porous support 3 include nonwoven fabric; porous polytetrafluoroethylene; aromatic polyamide fiber; porous metal; sintered metal; porous ceramic; porous polyester; porous nylon; activated carbon fiber; latex; silicone; silicone rubber; permeable (porous) polymer containing at least one selected from the group consisting of polyvinyl fluoride, polyvinylidene fluoride, polyurethane, polypropylene, polyethylene, polystyrene, polycarbonate, polysulfone, polyetheretherketone, polyacrylonitrile, polyimide, and polyphenylene oxide; metal foam having open or closed cells; polymer foam having open or closed cells; silica; porous glass; mesh screen, etc. The porous support 3 may be a combination of two or more of these. As an example, the porous support 3 may be a laminate of a nonwoven fabric and a polysulfone porous layer.

[0155] Alternatively, the porous support 3 may contain a crosslinked polymer Q, or it may contain a crosslinked polymer Q and particles M. The particles M are preferably bonded to the crosslinked polymer Q. In this case, the crosslinked polymer Q and particles M contained in the porous support 3 are typically the same as the crosslinked polymer Q and particles M contained in the separation functional layer 1. The crosslinked polymer Q is preferably a crosslinked polyimide. The particles M are preferably porous particles. In particular, it is preferable that the material of the porous support 3 is the same as the material of the separation functional layer 1. As an example, the separation membrane 10 may consist only of a crosslinked polymer Q (typically a crosslinked polyimide) and particles M. In such a case, it is preferable that the separation membrane 10 does not contain an intermediate layer 2, the porous support 3 is in direct contact with the separation functional layer 1, and the separation functional layer 1 and the porous support 3 are integrated. In this specification, "integrated" means that the components cannot be separated from each other non-destructively.

[0156] The content of the crosslinked polymer Q in the porous support 3 is, for example, 50 wt% or more, and may be 60 wt% or more, 70 wt% or more, 80 wt% or more, 90 wt% or more, or even 95 wt% or more. The porous support 3 may be composed substantially of only the crosslinked polymer Q. However, the porous support 3 may also contain an uncrosslinked polymer G (for example, an uncrosslinked polyimide P) in addition to the crosslinked polymer Q. The content of the crosslinked polymer Q in the porous support 3 may be the same as the content of the crosslinked polymer Q in the separation functional layer 1.

[0157] The content of particles M in the porous support 3 may be 0 wt% to 50 wt% relative to the crosslinked polymer Q in the porous support 3, or it may be 1 wt% to 50 wt%, 3 wt% to 50 wt%, 5 wt% to 30 wt%, 5 wt% to 25 wt%, or even 10 wt% to 20 wt%. The content of particles M in the porous support 3 may be 0 wt% to 50 wt% relative to the total amount of crosslinked polymer Q and uncrosslinked polymer G in the porous support 3, or it may be 1 wt% to 50 wt%, 3 wt% to 50 wt%, 5 wt% to 30 wt%, 5 wt% to 25 wt%, or even 10 wt% to 20 wt%.

[0158] The porous support 3 has an average pore diameter of, for example, 0.01 μm to 0.4 μm. The thickness of the porous support 3 is not particularly limited, but is, for example, 10 μm or more, preferably 20 μm or more, and more preferably 50 μm or more. The thickness of the porous support 3 is, for example, 300 μm or less, preferably 200 μm or less, and more preferably 150 μm or less.

[0159] (Method for manufacturing a separation membrane) The separation membrane 10 can be manufactured by the following method. First, a laminate of a porous support 3 and an intermediate layer 2 is prepared. This laminate can be manufactured by the following method. First, a coating solution containing the material for the intermediate layer 2 is prepared. Next, the coating solution containing the material for the intermediate layer 2 is applied to the porous support 3 to form a coating film. The method of applying the coating solution is not particularly limited, and for example, a spin coating method or a dip coating method can be used. The coating solution may also be applied using a wire bar or the like. Next, the coating film is dried to form the intermediate layer 2. Drying of the coating film can be carried out under heating conditions. The heating temperature of the coating film is, for example, 50°C or higher. The heating time of the coating film is, for example, 1 minute or more, and may be 5 minutes or more. Furthermore, the surface of the intermediate layer 2 may be treated with an easy-adhesion treatment as needed. Examples of easy-adhesion treatments include surface treatments such as application of a primer, corona discharge treatment, and plasma treatment.

[0160] Next, a separation functional layer 1 is formed on the intermediate layer 2 in the laminate of the porous support 3 and the intermediate layer 2. This makes it possible to obtain a separation membrane 10. For example, first, a separation functional layer 1 is prepared on a substrate by the method described above, then a coating solution containing the material for the intermediate layer 2 is applied to the separation functional layer 1 and dried to form the intermediate layer 2, and the laminate of the intermediate layer 2 and the separation functional layer 1 is transferred to the porous support 3 to produce a separation membrane 10.

[0161] The method for producing the separation membrane 10 is not limited to the method described above. For example, the manufacturing method described above may be used for the separation functional layer 1 using a laminate of the porous support 3 and the intermediate layer 2 as a substrate. This will produce the separation membrane 10.

[0162] (Shape of the separation membrane) In this embodiment, the separation membrane 10 is typically a flat membrane. However, the separation membrane 10 may have a shape other than a flat membrane, for example, a hollow fiber membrane. The separation membrane 10 may have the configuration shown in Figure 2, and may include a separation functional layer 1 and a porous support 3, but may not include an intermediate layer 2. In this case, as described above, the separation functional layer 1 and the porous support 3 may be integrated.

[0163] <Embodiment of Membrane Separation Apparatus> Figure 3A is a schematic cross-sectional view showing an example of the membrane separation apparatus of this embodiment. As shown in Figure 3A, the membrane separation apparatus 100 of this embodiment includes a separation membrane 10 and a tank 20. In the membrane separation apparatus 100, it is also possible to use a separation functional layer 1 by itself instead of the separation membrane 10. The tank 20 includes a first chamber 21 and a second chamber 22. The separation membrane 10 is located inside the tank 20. Inside the tank 20, the separation membrane 10 separates the first chamber 21 and the second chamber 22. The separation membrane 10 extends from one of a pair of walls of the tank 20 to the other.

[0164] The first chamber 21 has an inlet 21a and an outlet 21b. The second chamber 22 has an outlet 22a. Preferably, each of the inlet 21a, outlet 21b, and outlet 22a is an opening formed in the wall surface of the tank 20.

[0165] Membrane separation using the membrane separation apparatus 100 is performed by the following method. First, a mixed gas 30 containing an acidic gas is supplied to the first chamber 21 through the inlet 21a. The concentration of the acidic gas in the mixed gas 30 is not particularly limited, but is, for example, 0.01 vol% (100 ppm) or more under standard conditions, preferably 1 vol% or more, more preferably 10 vol% or more, even more preferably 30 vol% or more, and particularly preferably 50 vol% or more. The upper limit of the concentration of the acidic gas in the mixed gas 30 is not particularly limited, but is, for example, 90 vol% under standard conditions.

[0166] The pressure inside the first chamber 21 may be increased by supplying the mixed gas 30. The membrane separation device 100 may further include a pump (not shown) for increasing the pressure of the mixed gas 30. The pressure of the mixed gas 30 supplied to the first chamber 21 is, for example, 0.1 MPa or more, preferably 0.3 MPa or more.

[0167] The second chamber 22 may be depressurized while the mixed gas 30 is supplied to the first chamber 21. The membrane separation device 100 may further include a pump (not shown) for depressurizing the second chamber 22. The second chamber 22 may be depressurized such that the space inside the second chamber 22 is, for example, 10 kPa or more, preferably 50 kPa or more, and more preferably 100 kPa or more, than the atmospheric pressure in the measurement environment.

[0168] By supplying the mixed gas 30 into the first chamber 21, a permeate fluid 35 with a higher acidic gas content than the mixed gas 30 can be obtained on the other side of the separation membrane 10. That is, the permeate fluid 35 is supplied to the second chamber 22. Preferably, the permeate fluid 35 contains acidic gas as its main component. However, the permeate fluid 35 may also contain small amounts of other gases besides acidic gas. The permeate fluid 35 is discharged to the outside of the tank 20 through the outlet 22a.

[0169] The concentration of acidic gas in the gas mixture 30 gradually decreases from the inlet 21a to the outlet 21b of the first chamber 21. The gas mixture 30 (impermeable fluid 36) treated in the first chamber 21 is discharged to the outside of the tank 20 through the outlet 21b.

[0170] The membrane separation apparatus 100 of this embodiment is suitable for a continuous flow membrane separation method. However, the membrane separation apparatus 100 of this embodiment may also be used for a batch membrane separation method.

[0171] In some cases, the second chamber 22 may also have an inlet. Figure 3B is a schematic cross-sectional view showing another example of the membrane separation apparatus of this embodiment. In the membrane separation apparatus 101 shown in Figure 3B, the separation membrane 10 is located inside the tank 20 and separates the first chamber 21 and the second chamber 22. In the membrane separation apparatus 101, it is also possible to use the separation functional layer 1 alone instead of the separation membrane 10. The first chamber 21 has an inlet 21a and an outlet 21b. The second chamber 22 has an inlet 22b and an outlet 22a. Preferably, each of the inlets 21a, 21b, 22b, and 22a are openings formed in the wall surface of the tank 20. In Figure 4, the inlets 21a and 22a are formed in the same wall surface, and the outlets 21b and 22b are formed in the same wall surface, but the configuration of the membrane separation apparatus 101 is not limited thereto. For example, inlets 21a and 22b may be formed on the same wall surface, and outlets 21b and 22a may be formed on the same wall surface. The second chamber 22 may be at atmospheric pressure, or a sweep gas may be supplied.

[0172] The membrane separation using the membrane separation device 101 is performed, for example, by a sweep method. Specifically, with the mixed gas 30 supplied to the first chamber 21, a sweep gas is supplied to the second chamber 22. This yields a permeate fluid 35 that has permeated through the separation membrane 10. The permeate fluid 35 is discharged to the outside of the tank 20 through the outlet 22a.

[0173] <Modifications of the Membrane Separation Apparatus> The membrane separation apparatuses 100 and 101 may be spiral-type membrane elements, hollow fiber membrane elements, etc. Figure 4 shows a spiral-type membrane element. The membrane separation apparatus 110 in Figure 4 comprises a central tube 41 and a laminate 42. The laminate 42 contains a separation membrane 10. The laminate 42 may contain a separation functional layer 1 by itself instead of the separation membrane 10.

[0174] The central tube 41 has a cylindrical shape. Multiple holes are formed on the surface of the central tube 41 to allow the permeable fluid 35 to flow into the interior of the central tube 41. Examples of materials for the central tube 41 include resins such as acrylonitrile butadiene styrene copolymer resin (ABS resin), polyphenylene ether resin (PPE resin), and polysulfone resin (PSF resin); and metals such as stainless steel and titanium. The inner diameter of the central tube 41 is, for example, in the range of 20 to 100 mm.

[0175] The laminate 42 further includes a supply-side channel material 43 and a permeate-side channel material 44 in addition to the separation membrane 10. The laminate 42 is wound around the central tube 41. The membrane separation device 110 may further include an outer casing material (not shown).

[0176] For the supply-side channel material 43 and the permeate-side channel material 44, for example, a resin net made of polyphenylene sulfide (PPS) or ethylene-chlorotrifluoroethylene copolymer (ECTFE) can be used.

[0177] Membrane separation using the membrane separation device 110 is performed by the following method. First, a mixed gas 30 is supplied to one end of the wound laminate 42. The permeate fluid 35 that has permeated through the separation membrane 10 of the laminate 42 moves into the center tube 41. The permeate fluid 35 is discharged to the outside through the center tube 41. The mixed gas 30 (impermeable fluid 36) processed by the membrane separation device 110 is discharged to the outside from the other end of the wound laminate 42. This makes it possible to separate acidic gas from the mixed gas 30.

[0178] The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

[0179] [Preparation of the Separation Functional Layer] (Sample 1) First, polyimide P1 was synthesized using an automated polymerization apparatus (Mettler Toledo, EasyMax 402). A Liebig condenser, stirring rod, internal thermometer, nitrogen inlet tube, and flat stopper were attached to a separable flask (capacity 400 mL) provided with the apparatus. Cooling liquid set to 10°C was circulated through the Liebig condenser chiller. N2 gas was circulated into the flask at a flow rate of 100 mL / min. The stirring speed was set to 300 rpm. Next, 42.9 g of 1-methyl-2-pyrrolidone (super-dehydrated) (NMP) as the solvent, 4.52 g (12 mmol) of 9,9-bis(4-amino-3-methylphenyl)fluorene (BAMPF) as the diamine, and 1.65 g (6 mmol) of 3,7-diamino-2,8-dimethyldibenzothiophenesulfone (DDBT) were added to the flask. The diamine was dissolved in the solvent by stirring at room temperature. To the resulting solution, 4.81 g (18 mmol) of naphthalene-1,4,5,8-tetracarboxylic dianhydride (NTDA) and 4.38 g (36 mmol) of benzoic acid were added. The jacket temperature of the apparatus was raised to 180°C and the mixture was stirred for 8 hours. After stirring, the internal temperature of the flask was cooled to 25°C and the mixture was left to stand overnight.

[0180] Next, 4.63 g (36 mmol) of isoquinoline was added, the jacket temperature was raised again to 180°C, and the mixture was stirred for 8 hours. After letting the reaction mixture stand overnight, it was diluted by adding 160.8 g of NMP. Next, using a dropping funnel, 241 mL of methanol was added dropwise to the reaction mixture over approximately 30 minutes for reprecipitation and purification. The precipitated polyimide was filtered off, and the polyimide was washed twice with 80 mL of methanol. After washing, the filtered polyimide was dried in a hot air circulating dryer at 60°C for 15 hours, and then dried in a vacuum dryer at 100°C for 8 hours. This yielded polyimide P1 in a yield of 10 g.

[0181] Next, the porous particles of Sample 1 were synthesized as follows. In an Ar glove box, 0.57 g (3.62 mmol) of 2,2'-bipyridyl as a ligand was dissolved in a mixture of 75 mL of super-dehydrated N,N-dimethylformamide and 75 mL of super-dehydrated tetrahydrofuran. 1.00 g (3.64 mmol) of bis(1,5-cyclooctadiene)nickel(0) was added as a catalyst, and the mixture was stirred for 3 minutes. Then, 0.51 g (0.81 mmol) of tetrakis(4-bromophenyl)methane was added, and the mixture was stirred at 25°C for 24 hours to allow the coupling reaction (Yamamoto coupling) to proceed. 50 mL of 6 M hydrochloric acid was added to the reaction solution, and the mixture was stirred at 25°C for 6 hours. The resulting precipitate was washed with methanol and water, and then vacuum-dried at 80°C for 6 hours to synthesize PAF-1 as a white powder. In this way, the porous particles (PAF-1) of Sample 1 were obtained. The specific surface area of ​​porous particles is 4023 m². 2 It was / g.

[0182] The porous particles described above were mixed with NMP and dispersed using an ultrasonic homogenizer for 10 minutes. The dispersion and the polyimide P1 described above were added to a 50 mL screw-cap tube to obtain a mixture. At this time, the porous particles were adjusted to 10 wt% relative to the polyimide P1. In this way, the coating solution was prepared.

[0183] Next, a substrate was prepared by attaching a release liner (manufactured by Fujiko, PI-50-SCA0) that had been corona-treated (0.5 kW, 3 m / min) to soda glass. The coating solution was placed on the release liner, and a coating film was formed using an applicator. The above coating film was dried at 130°C for 1 hour to obtain a film containing polyimide P1 and porous particles.

[0184] A liquid was prepared containing 5 w / v% dimethoxymethane as a crosslinking agent, 3 w / v% iron(III) chloride as a catalyst, and 1,2-dichloroethane as a solvent. Next, the film peeled off the release liner was immersed in the liquid. At this time, the weight of the film relative to the liquid was set to 0.5 w / v%. By immersion at 50°C for 1 hour, a crosslinking reaction was carried out, and a film containing crosslinked polyimide and porous particles crosslinked thereto was formed. After removing the film from the liquid, the film was washed by repeating immersion in methanol at 40°C for 1 hour three times. After washing, the separation functional layer (self-supporting film) of sample 1 was obtained by vacuum drying at 120°C for 4 hours.

[0185] (Sample 2) The porous particles of Sample 2 were synthesized as follows: 0.93 g (5.75 mmol) of FeCl3 (anhydrous) as a catalyst was added to 12.9 mL of 1,2-dichloroethane to obtain a FeCl3 solution. 1.00 g (5.71 mmol) of α,α'-dichloro-p-xylene was dissolved in 12.9 mL of 1,2-dichloroethane, and the above FeCl3 solution was added to this solution. pDCX was synthesized by polymerization reaction (Friedel-Crafts alkylation) at 25°C for 10 minutes. After sequential washing with water, methanol, and diethyl ether, a brown powder was obtained by vacuum drying at 60°C for 8 hours. The porous particles (pDCX) of Sample 2 were obtained in this manner. The specific surface area of ​​the porous particles is 1137 m². 2 It was / g.

[0186] The separation functional layer (self-supporting membrane) of Sample 2 was fabricated in the same manner as Sample 1, except that the porous particles described above were used.

[0187] (Sample 3) Polyimide P2 was obtained in the same manner as polyimide P1, except that the amount of 9,9-bis(4-amino-3-methylphenyl)fluorene (BAMPF) added was changed to 5.06 g (13.5 mmol) and the amount of 3,7-diamino-2,8-dimethyldibenzothiophenesulfone (DDBT) added was changed to 1.23 g (4.5 mmol).

[0188] The separation functional layer (self-supporting membrane) of Sample 3 was obtained in the same manner as Sample 2, except that polyimide P2 was used.

[0189] (Sample 4) The separation functional layer (self-supporting membrane) of Sample 4 was obtained in the same manner as Sample 2, except that the porous particles in the coating solution were made to be 15 wt% relative to the polyimide P1.

[0190] (Sample 5) The separation functional layer (self-supporting membrane) of Sample 5 was obtained in the same manner as Sample 2, except that the porous particles in the coating solution were made to be 17.5 wt% relative to the polyimide P1.

[0191] (Sample 6) The separation functional layer (self-supporting membrane) of Sample 6 was obtained in the same manner as Sample 3, except that the porous particles in the coating solution were made to be 15 wt% relative to the polyimide P2.

[0192] (Sample 7) The separation functional layer (self-supporting membrane) of Sample 7 was obtained in the same manner as in Sample 2, except that the crosslinking agent in the liquid into which the membrane was immersed was changed to 1,2-dimethoxyethane and the solvent was changed to acetonitrile.

[0193] (Sample 8) The separation functional layer (self-supporting membrane) for Sample 8 was obtained in the same manner as for Sample 7, except that the crosslinking agent was changed to 1,3-dimethoxypropane.

[0194] (Sample 9) Polyimide P3 was obtained in the same manner as polyimide P1, except that the amount of 9,9-bis(4-amino-3-methylphenyl)fluorene (BAMPF) added was changed to 3.38 g (9 mmol) and the amount of 3,7-diamino-2,8-dimethyldibenzothiophenesulfone (DDBT) added was changed to 2.46 g (9 mmol).

[0195] The separation functional layer (self-supporting membrane) of sample 9 was obtained in the same manner as sample 4, except that polyimide P3 was used.

[0196] (Sample 10) The separation functional layer (self-supporting membrane) of Sample 10 was obtained in the same manner as Sample 9, except that the porous particles in the coating solution were made to be 17.5 wt% relative to the polyimide P3.

[0197] (Sample 11) The separation functional layer (self-supporting membrane) of Sample 11 was obtained in the same manner as Sample 9, except that the porous particles in the coating solution were made to be 20 wt% relative to the polyimide P3.

[0198] (Sample 12) Polyimide P3 was prepared in the same manner as in Sample 9. Polyimide P3 was dissolved in NMP to prepare a coating solution. Next, a substrate was prepared by attaching a release liner (Fujiko, PI-50-SCA0) that had been corona treated (0.5 kW, 3 m / min) to soda glass. The coating solution was placed on the release liner and a coating film was formed using an applicator. The above coating film was dried at 130°C for 1 hour to obtain a polyimide P3 film.

[0199] A liquid containing 5 w / v% dimethoxymethane, 3 w / v% iron(III) chloride, and 1,2-dichloroethane was prepared in the same manner as in Sample 1, and the polyimide P1 film peeled off the release liner was immersed in the liquid. At this time, the weight of the film relative to the liquid was set to 0.5 w / v%. By immersion at 50°C for 1 hour, a cross-linked polyimide film was formed. After removing the film from the liquid, the film was washed by repeating immersion in methanol for 1 hour three times. After washing, the separation functional layer (self-supporting film) of Sample 9 was obtained by vacuum drying at 120°C for 10 hours. No porous particles were added in Sample 12.

[0200] (Sample 13) Polyimide P1 was prepared in the same manner as in Sample 1. The separation functional layer (self-supporting membrane) of Sample 13 was fabricated in the same manner as in Sample 12, except that polyimide P1 was used.

[0201] (Sample 14) Polyimide P2 was prepared in the same manner as in Sample 3. The separation functional layer (self-supporting membrane) of Sample 14 was fabricated in the same manner as in Sample 12, except that polyimide P2 was used.

[0202] (Sample 15) A coating solution containing polyimide P1 and 10 wt% porous particles PAF-1 relative to polyimide P1 was prepared in the same manner as in Sample 1.

[0203] Next, a substrate was prepared by attaching a release liner (Fujiko, PI-50-SCA0) that had been corona-treated (0.5 kW, 3 m / min) to soda glass. The coating solution was placed on the release liner, and a coating film was formed using an applicator. The above coating film was dried at 130°C for 1 hour to obtain a film containing polyimide P1 and porous particles. The above film, peeled off from the release liner, was washed by immersing it in methanol at 40°C for 1 hour three times. After washing, the separation functional layer (self-supporting film) of sample 15 was obtained by vacuum drying at 120°C for 4 hours. In other words, sample 15 was prepared in the same manner as sample 1, except that the crosslinking reaction was not performed.

[0204] (Sample 16) The separation functional layer (self-supporting membrane) of Sample 16 was obtained in the same manner as Sample 15, except that pDCX was used as the porous particle. In other words, Sample 16 was prepared in the same manner as Sample 2, except that the crosslinking reaction was not carried out.

[0205] (Sample 17) The separation functional layer (self-supporting membrane) of Sample 17 was obtained in the same manner as Sample 16, except that polyimide P2 was used. In other words, Sample 17 was prepared in the same manner as Sample 3, except that the crosslinking reaction was not carried out.

[0206] (Sample 18) The separation functional layer (self-supporting membrane) of Sample 18 was fabricated in the same manner as Sample 1, except that silica filler (Aerosil RX200, Nippon Aerosil Co., Ltd.) was used instead of porous particles.

[0207] (Sample 19) The separation functional layer (self-supporting membrane) for Sample 19 was fabricated in the same manner as for Sample 1, except that PTFE powder (Seishin Corporation, TFW-3000FP) was used instead of porous particles.

[0208] (Sample 20) The separation functional layer (self-supporting membrane) for Sample 20 was fabricated in the same manner as for Sample 1, except that zeolite nanoparticles (Nakamura Superhard Co., Ltd., Zeoal 4a 300nm) were used instead of porous particles.

[0209] [Characterization of the Separation Functional Layer] (Gas Permeation Test) For the separation functional layers of samples 1 to 20, the permeation rate T1 of carbon dioxide, the permeation coefficient C1, and the separation coefficient α1 of carbon dioxide relative to methane were measured by the following method. First, the separation functional layer was set in a metal cell and sealed with an O-ring to prevent leakage. Next, a mixed gas was injected into the metal cell so that the mixed gas came into contact with one main surface of the separation functional layer. The mixed gas consisted substantially of carbon dioxide and methane. The concentration of carbon dioxide in the mixed gas was 50 vol% under standard conditions. The mixed gas injected into the metal cell was at a temperature of 30°C and a pressure of 0.1 MPa. Next, a sweep gas (argon gas) was injected into the metal cell adjacent to the other main surface of the separation functional layer. This allowed permeation fluid to be obtained from the other main surface of the separation functional layer. Based on the composition and weight of the obtained permeation fluid, the permeation rate T1, the permeation coefficient C1, and the separation coefficient α1 were calculated.

[0210] (Durability Test) The separation functional layers of samples 1-13 and 15-20 were subjected to a durability test by being stored at 85°C for 500 hours. After the durability test, the carbon dioxide transmission rate T2 and transmission coefficient C2 were measured for the separation functional layers using the same method as for the transmission coefficient C1, and the separation coefficient α2 was calculated.

[0211]

[0212] The abbreviations in Table 1 are as follows: BAMPF: 9,9-bis(4-amino-3-methylphenyl)fluorene DDBT: 3,7-diamino-2,8-dimethyldibenzothiophenesulfone

[0213] As can be seen from Table 1, the separation functional layers of samples 1 to 11 had a higher permeability coefficient C2 after durability testing than the separation functional layers of samples 12 to 20, indicating superior performance. Furthermore, the separation functional layers of samples 1 to 11 also had sufficiently high permeability coefficients C1 in their initial state.

[0214] The separation layer and separation membrane of this embodiment are suitable for separating acidic gases from a gas mixture containing acidic gases. In particular, the separation layer and separation membrane of this embodiment are suitable for separating carbon dioxide from biogas.

Claims

1. A separation functional layer comprising a crosslinked polymer in which a polymer containing carbon atoms is crosslinked via a first linking group, and particles, wherein the first linking group is a hydrocarbon group bonded to the carbon atoms, and the particles are bonded to the crosslinked polymer.

2. The separation functional layer according to claim 1, wherein the hydrocarbon group is an alkylene group.

3. The separation functional layer according to claim 2, wherein the number of carbon atoms in the alkylene group is 1 to 5.

4. The separation functional layer according to claim 1, wherein the polymer comprises an aromatic ring, and the aromatic ring comprises the carbon atoms.

5. The separation functional layer according to claim 4, wherein the polymer contains an electron-donating group, and the electron-donating group is bonded to the aromatic ring.

6. The separation functional layer according to claim 1, wherein the polymer is polyimide.

7. The separation functional layer according to claim 6, wherein the polyimide comprises a constituent unit A1 derived from a tetracarboxylic dianhydride having a six-membered ring acid anhydride structure and a constituent unit B derived from a diamine.

8. The separation functional layer according to claim 7, wherein the constituent unit B has the carbon atoms.

9. The separation functional layer according to claim 7, wherein the constituent unit A1 is represented by the following formula (A1). In the above formula (A1), R 1a ~R 4a These are, independently of each other, a hydrogen atom or any substituent.

10. The separation functional layer according to claim 1, wherein the particles are bonded to the crosslinked polymer via a second linking group.

11. The separation functional layer according to claim 10, wherein the second linking group is a hydrocarbon group.

12. The separation functional layer according to claim 1, wherein the particles are porous particles.

13. The separation functional layer according to claim 12, wherein the porous particles include an organic polymer.

14. The separation functional layer according to claim 13, wherein the organic polymer includes an aromatic ring.

15. The separation functional layer according to claim 14, wherein the organic polymer is a porous polymer.

16. The separation functional layer according to claim 1, wherein the particles are surface-modified.

17. The separation functional layer according to claim 1, wherein the content of the particles is 3 wt% or more and 50 wt% or less relative to the crosslinked polymer.

18. The separation functional layer according to claim 1, used for separating an acidic gas from a gas mixture containing an acidic gas.

19. A separation membrane comprising: a separation functional layer according to claim 1; and a porous support that supports the separation functional layer.

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