Separation function layer and separation membrane

Abstract

The present invention provides a separation function layer in which a decrease in separation performance under acidic conditions is suppressed. A separation function layer 1 according to the present invention comprises a polymer P having a structural unit S derived from a thiol compound and a structural unit U derived from an epoxy compound. A separation membrane 10 according to the present invention comprises the separation functional layer 1, and a porous support 3 supporting the separation functional layer 1.

Description

Separation functional layer and separation membrane

[0001] This 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. 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. Polymers such as polyether block amides are used as materials for the separation functional layer (for example, Patent Document 1).

[0004] Special Publication No. 2020-532419

[0005] Conventional separation layers tend to lose separation performance when used or stored under acidic conditions.

[0006] Therefore, the present invention aims to provide a separation functional layer in which the deterioration of separation performance under acidic conditions is suppressed.

[0007] The present invention provides a separation functional layer comprising a polymer having structural units derived from a thiol compound and structural units derived from an epoxy compound.

[0008] 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.

[0009] According to the present invention, a separation functional layer can be provided in which the deterioration of separation performance under acidic conditions is suppressed.

[0010] 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 perspective view showing a modified example of the membrane separation apparatus equipped with the separation membrane of the present invention.

[0011] The separation functional layer according to the first aspect of the present invention comprises a polymer having structural units derived from a thiol compound and structural units derived from an epoxy compound.

[0012] In a second embodiment of the present invention, for example, in the separation functional layer according to the first embodiment, the thiol compound includes a difunctional thiol compound having two thiol groups.

[0013] In a third aspect of the present invention, for example, in the separation functional layer according to the second aspect, the difunctional thiol compound includes at least one selected from the group consisting of an oxygen atom and a silicon atom.

[0014] In a fourth embodiment of the present invention, for example, in the separation functional layer according to the second or third embodiment, the difunctional thiol compound is represented by the following formula (A1). In the above formula (A1), multiple R 1a These are independent of each other and are arbitrary linking elements, where n1 is an integer greater than or equal to 1.

[0015] In a fifth embodiment of the present invention, for example, in the separation functional layer according to the fourth embodiment, a plurality of R 1a These are, independently of each other, a divalent hydrocarbon group or a divalent silicon-containing group.

[0016] In a sixth aspect of the present invention, for example, in the separation functional layer according to the fourth or fifth aspect, a plurality of R 1a These are, independently of each other, an ethane-1,2-diyl group or a propane-1,2-diyl group.

[0017] In a seventh aspect of the present invention, for example, in the separation functional layer according to any one of the first to sixth aspects, the thiol compound includes a polyfunctional thiol compound having three or more thiol groups.

[0018] In the eighth aspect of the present invention, for example, in the separation functional layer according to any one of the first to seventh aspects, the epoxy compound includes a difunctional epoxy compound having two epoxy groups.

[0019] In a ninth aspect of the present invention, for example, in the separation functional layer according to the eighth aspect, the bifunctional epoxy compound contains at least one selected from the group consisting of an oxygen atom and a silicon atom.

[0020] In a tenth aspect of the present invention, for example, in the separation functional layer according to the eighth or ninth aspect, the bifunctional epoxy compound is represented by the following formula (B1). In the formula (B1), R 1b is an arbitrary linking group, and a plurality of R 2b are each independently an arbitrary linking group, and a plurality of R 3b are each independently a hydrogen atom or an arbitrary substituent, and m1 is an integer of 1 or more.

[0021] In an eleventh aspect of the present invention, for example, in the separation functional layer according to the tenth aspect, the R 1b is a divalent hydrocarbon group or a divalent silicon-containing group.

[0022] In a twelfth aspect of the present invention, for example, in the separation functional layer according to the tenth or eleventh aspect, the R 1b is an ethane-1,2-diyl group or a propane-1,2-diyl group.

[0023] In a thirteenth aspect of the present invention, for example, in the separation functional layer according to any one of the first to twelfth aspects, the polymer contains at least one selected from the group consisting of a structure represented by the following formula (C1) and a structure represented by the following formula (C2). In the formula (C1) and the formula (C2), R 1c is a hydrogen atom or an arbitrary substituent, a plurality of R 2c are each independently a hydrogen atom or an arbitrary substituent, and * indicates a bonding position in the main chain of the polymer.

[0024] In a fourteenth aspect of the present invention, for example, in the separation functional layer according to any one of the first to thirteenth aspects, the polymer has a crosslinked structure.

[0025] In a 15th aspect of the present invention, for example, a separation functional layer according to any one of the first to 14th aspects is used to separate an acidic gas from a mixed gas containing an acidic gas.

[0026] A separation membrane according to the sixteenth aspect of the present invention comprises a separation functional layer according to any one of the first to fifteenth aspects, and a porous support that supports the separation functional layer.

[0027] 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.

[0028] <Embodiment of the Separation Functional Layer> Figure 1 is a 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. The separation functional layer 1 is typically a dense layer (non-porous layer) in which no pores can be observed when viewed at a magnification of 5000x using a scanning electron microscope (SEM).

[0029] The separation functional layer 1 contains a polymer P having constituent units S derived from a thiol compound and constituent units U derived from an epoxy compound.

[0030] According to the inventors' studies, polymers (particularly polyether block amides) contained in conventional separation functional layers tend to hydrolyze under acidic conditions, which leads to a decrease in the separation performance of the separation functional layer. Hydrolyzed polymers (low molecular weight components) can leach out of the separation functional layer, causing defects in the layer or affecting structures located near the separation functional layer. For example, in a separation membrane equipped with a separation functional layer and a porous support, the pores of the porous support may become blocked by low molecular weight components leached from the separation functional layer. In contrast, polymer P having the above-mentioned structural units S and U is less susceptible to hydrolysis even under acidic conditions and is suitable for suppressing a decrease in the separation performance of the separation functional layer.

[0031] A thiol compound is a compound having at least one thiol group. Preferably, the thiol compound includes a difunctional thiol compound having two thiol groups. The thiol compound may also include a polyfunctional thiol compound having three or more thiol groups, either together with the difunctional thiol compound or in place of the difunctional thiol compound. In this embodiment, it is preferable that the polymer P includes both a structural unit S1 derived from the difunctional thiol compound and a structural unit S2 derived from the polyfunctional thiol compound. The thiol compound may also include a monofunctional thiol compound having one thiol group.

[0032] Examples of thiol groups contained in a bifunctional thiol compound include primary thiol groups, secondary thiol groups, and tertiary thiol groups, with primary thiol groups being preferred.

[0033] The molecular weight (or number-average molecular weight in some cases) of the difunctional thiol compound is, for example, 100 or more, and may be 150 or more. The upper limit of the molecular weight of the difunctional thiol compound is, for example, 2000 or less, and may be 1000 or less, 800 or less, 500 or less, and even 300 or less. The thiol equivalent of the difunctional thiol compound is, for example, 50 g / eq. to 1000 g / eq., and may be 80 g / eq. to 300 g / eq. In this specification, thiol equivalent means the molecular weight of the thiol compound per equivalent of thiol groups contained in the thiol compound.

[0034] The difunctional thiol compound preferably contains at least one atom selected from the group consisting of oxygen and silicon atoms, and is particularly preferably the presence of an oxygen atom. More specifically, the difunctional thiol compound preferably has a functional group containing an oxygen atom or a silicon atom. Examples of such functional groups include ether groups and silyl ether groups. In particular, a difunctional thiol compound having an ether group is suitable for improving the separation performance of the separation functional layer 1 for acidic gases. A difunctional thiol compound having a silyl ether group is suitable for improving the permeation rate of acidic gases that permeate the separation functional layer 1.

[0035] When a difunctional thiol compound contains oxygen atoms, the ratio of the number of oxygen atoms to the total number of oxygen atoms and carbon atoms in one molecule of the difunctional thiol compound is, for example, 10% or more, and may be 15% or more, 18% or more, 20% or more, or even 25% or more. The higher this ratio, the more the separation performance of the separation functional layer 1 for acidic gases tends to improve. The upper limit of this ratio is, for example, 50% or less, and may be 40% or less.

[0036] The difunctional thiol compound is preferably represented by the following formula (A1).

[0037] In the above formula (A1), multiple R 1a These are independent of each other and are arbitrary linking elements, where n1 is an integer greater than or equal to 1.

[0038] In formula (A1), multiple R 1a These may be the same as each other, or they may be different from each other. Multiple R 1a These are preferably independently divalent hydrocarbon groups or divalent silicon-containing groups. The number of carbon atoms in the divalent hydrocarbon group is, for example, 1 to 5, and may be 1 to 3. The divalent hydrocarbon group may be linear or branched. Examples of divalent hydrocarbon groups include alkylene groups such as methylene groups, ethane-1,2-diyl groups, propane-1,2-diyl groups, propane-1,3-diyl groups, and propane-2,2-diyl groups. 1a Preferably, each of them is independently of the other, an ethane-1,2-diyl group or a propane-1,2-diyl group. In formula (A1), all R 1a However, it may also be a divalent hydrocarbon group (especially an ethane-1,2-diyl group).

[0039] The divalent silicon-containing group is not particularly limited as long as it contains a silicon atom. The silicon atom contained in the silicon-containing group is R in formula (A1). 1a It may bond with an adjacent oxygen atom (O) to form a silyl ether group. In formula (A1), n1 is 2 or more, and the divalent silicon-containing group is R 1aWhen bonded to two adjacent oxygen atoms, the divalent silicon-containing group may be represented by the following formula (A2).

[0040] In the above formula (A2), multiple R 2a These are hydrocarbon groups, independently of each other, and * indicates the bond position with the oxygen atom. The number of carbon atoms in the hydrocarbon group is, for example, 1 to 5, and may be 1 to 3. The hydrocarbon group may be linear or branched. Examples of hydrocarbon groups include alkyl groups such as methyl groups and ethyl groups, and methyl groups are preferred.

[0041] In formula (A1), when a divalent silicon-containing group is bonded to an oxygen atom (O) and a sulfur atom (S), the divalent silicon-containing group may also be represented by the following formula (A3).

[0042] In the above formula (A3), multiple R 2a These are, independently of each other, hydrocarbon groups, and R 3a R is a divalent hydrocarbon group, where *1 indicates the bond position with the sulfur atom, and *2 indicates the bond position with the oxygen atom. 2a Examples of hydrocarbon groups include those described above for formula (A2), and a methyl group is preferred. 3a Examples of the divalent hydrocarbon group include those described above for formula (A1), and a propane-1,3-diyl group is preferred.

[0043] In the above formula (A1), n1 is 1 or greater as described above, and may also be 2 or greater. The upper limit of n1 is, for example, 15 or less, and may also be 13 or less, 10 or less, 8 or less, or even 5 or less.

[0044] Specific examples of difunctional thiol compounds include 3,6-dioxa-1,8-octanedithiol, tetra(ethylene glycol)dithiol, hexa(ethylene glycol)dithiol, and poly(ethylene glycol)dithiol.

[0045] In polymer P, the constituent unit S1 derived from the difunctional thiol compound is preferably represented by the following formula (A4). The constituent unit S1 represented by formula (A4) is derived from the difunctional thiol compound represented by the above formula (A1).

[0046] In formula (A4), multiple R 1a And n1 is the same as in equation (A1).

[0047] In polymer P, the ratio of the amount of substance of constituent unit S1 derived from the difunctional thiol compound to the amount of substance of all constituent units S derived from the thiol compound is, for example, 10 mol% or more, and may be 30 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, or even 80 mol% or more. The upper limit of this ratio is, for example, 95 mol% or less, and may be 90 mol% or less.

[0048] As described above, the thiol compound may include a polyfunctional thiol compound having three or more thiol groups. A polyfunctional thiol compound can be used to form a polymer P having a crosslinked structure.

[0049] Examples of thiol groups included in a polyfunctional thiol compound include primary thiol groups, secondary thiol groups, and tertiary thiol groups, with primary thiol groups being preferred. The number of thiol groups in a polyfunctional thiol compound is preferably four or more. The upper limit of the number of thiol groups is not particularly limited and may be, for example, 10 or less, 8 or less, or even 5 or less. The polyfunctional thiol compound is preferably a tetrafunctional thiol compound having four thiol groups.

[0050] The molecular weight (or number-average molecular weight in some cases) of the polyfunctional thiol compound is, for example, 200 or more, and may be 300 or more, or even 400 or more. The upper limit of the molecular weight of the polyfunctional thiol compound is, for example, 2000 or less, and may be 1000 or less, 800 or less, or even 500 or less. The thiol equivalent of the polyfunctional thiol compound is, for example, 50 g / eq. to 1000 g / eq., and may be 80 g / eq. to 300 g / eq.

[0051] Polyfunctional thiol compounds may contain oxygen atoms or silicon atoms, and may have functional groups such as ether groups or silyl ether groups. In particular, it is preferable that polyfunctional thiol compounds have ether groups. However, polyfunctional thiol compounds may not contain oxygen atoms or silicon atoms.

[0052] When a polyfunctional thiol compound contains oxygen atoms, the ratio of the number of oxygen atoms to the total number of oxygen atoms and carbon atoms in one molecule of the polyfunctional thiol compound may be, for example, 5% or more, 10% or more, or even 15% or more. The upper limit of this ratio may be, for example, 30% or less, or 20% or less.

[0053] Polyfunctional thiol compounds may or may not contain a ring structure. The ring structure may consist only of carbon atoms or may be a heterocyclic ring containing heteroatoms. The ring structure may be monocyclic or polycyclic. The number of carbon atoms in the ring structure is not particularly limited, for example, 3 to 10. Specific examples of ring structures include triazine rings and glycoluryl rings.

[0054] Specific examples of polyfunctional thiol compounds include pentaerythritol tetrapropanthol, trithiocyanuric acid, and thiol group-containing glycoluryl derivatives (for example, TS-G and C3TS-G manufactured by Shikoku Chemicals Co., Ltd.).

[0055] In polymer P, the ratio of the amount of substance of the constituent unit S2 derived from the polyfunctional thiol compound to the amount of substance of all constituent units S derived from the thiol compound is, for example, 1 mol% or more, and may be 5 mol% or more, 10 mol% or more, or even 20 mol% or more. The upper limit of this ratio is, for example, 50 mol% or less, and may be 30 mol% or less.

[0056] As described above, the thiol compound may include a monofunctional thiol compound having one thiol group. When polymer P contains a constituent unit S3 derived from a monofunctional thiol compound, the separation performance of the separation functional layer 1 tends to improve.

[0057] Examples of thiol groups contained in monofunctional thiol compounds include primary thiol groups, secondary thiol groups, and tertiary thiol groups, with primary thiol groups being preferred.

[0058] The molecular weight (or number-average molecular weight in some cases) of the monofunctional thiol compound is, for example, 100 or more, and may be 300 or more, or even 500 or more. The upper limit of the molecular weight of the monofunctional thiol compound is, for example, 10,000 or less, and may be 5,000 or less, 3,000 or less, or even 1,000 or less.

[0059] Monofunctional thiol compounds may contain oxygen atoms or silicon atoms, and may have functional groups such as ether groups, silyl ether groups, or carboxyl groups. In particular, monofunctional thiol compounds are preferably those that have an ether group.

[0060] When a monofunctional thiol compound contains oxygen atoms, the ratio of the number of oxygen atoms to the total number of oxygen atoms and carbon atoms in one molecule of the monofunctional thiol compound may be, for example, 10% or more, 15% or more, or even 20% or more. The upper limit of this ratio is, for example, 50% or less.

[0061] The monofunctional thiol compound is preferably represented by the following formula (A5).

[0062] In the above formula (A5), R 4a R is an arbitrary linking group. 5a is any substituent, and n² is a non-negative integer.

[0063] In formula (A5), if n2 is 1 or greater, multiple R 4a These may be any linking groups, independent of each other. 4a They may be the same as each other, or they may be different from each other. 4a It is preferable that is a divalent hydrocarbon group or a divalent silicon-containing group. Examples of divalent hydrocarbon groups and divalent silicon-containing groups include those described above for formula (A1). In formula (A5), when n2 is 1 or more, all R 4a However, it may also be a divalent hydrocarbon group (especially an ethane-1,2-diyl group).

[0064] R 5a In this, any substituent is, for example, a hydrocarbon group. Examples of hydrocarbon groups include those described above for formula (A2). The hydrocarbon group may further have substituents such as carboxyl groups.

[0065] In the above equation (A5), n2 is 0 or greater, as described above, and may be 1 or greater, or 2 or greater. The upper limit of n2 is not particularly limited, for example, 20 or less.

[0066] Specific examples of monofunctional thiol compounds include poly(ethylene glycol)methyl ether thiol and poly(ethylene glycol) 2-mercaptoethyl ether acetate.

[0067] In polymer P, the ratio of the amount of substance of the constituent unit S3 derived from the monofunctional thiol compound to the amount of substance of all constituent units S derived from the thiol compound is, for example, 0.1 mol% to 50 mol%, and may also be 1 mol% to 20 mol%. Polymer P may not contain any constituent units S3.

[0068] An epoxy compound is a compound having at least one epoxy group. Preferably, the epoxy compound includes a difunctional epoxy compound having two epoxy groups. The epoxy compound may also include a polyfunctional epoxy compound having three or more epoxy groups, either together with the difunctional epoxy compound or in place of the difunctional epoxy compound. In this embodiment, it is preferable that the polymer P includes a constituent unit U1 derived from the difunctional epoxy compound and does not include a constituent unit U2 derived from the polyfunctional epoxy compound. The epoxy compound may also include a monofunctional epoxy compound having one epoxy group.

[0069] The molecular weight (or number-average molecular weight, in some cases) of the difunctional epoxy compound is, for example, 100 or more, and may be 200 or more, 300 or more, 400 or more, or even 500 or more. The upper limit of the molecular weight of the difunctional epoxy compound is, for example, 2000 or less, and may be 1500 or less, 1300 or less, 1000 or less, or even 800 or less. The epoxy equivalent of the difunctional epoxy compound is, for example, 100 g / eq. to 1000 g / eq., and may be 200 g / eq. to 500 g / eq. In this specification, epoxy equivalent means the molecular weight of the epoxy compound per equivalent of epoxy groups contained in the epoxy compound.

[0070] The difunctional epoxy compound preferably contains at least one atom selected from the group consisting of oxygen atoms (more specifically, oxygen atoms other than those contained in the epoxy group) and silicon atoms, and is particularly preferably containing an oxygen atom. More specifically, the difunctional epoxy compound preferably has a functional group containing an oxygen atom or a silicon atom in addition to the epoxy group. Examples of such functional groups include ether groups and silyl ether groups. In particular, a difunctional epoxy compound having an ether group is suitable for improving the separation performance of the separation functional layer 1 for acidic gases. A difunctional epoxy compound having a silyl ether group is suitable for improving the permeation rate of acidic gases that permeate the separation functional layer 1.

[0071] In one molecule of a bifunctional epoxy compound, the ratio of the number of oxygen atoms to the total number of oxygen atoms and carbon atoms is, for example, 10% or more, and may be 20% or more, 25% or more, 30% or more, or even 35% or more. The higher this ratio, the more the separation performance of the separation functional layer 1 for acidic gases tends to improve. The upper limit of this ratio is, for example, 50% or less, and may be 40% or less.

[0072] The bifunctional epoxy compound is preferably represented by the following formula (B1).

[0073] In equation (B1), R 1b is an arbitrary linking group, and multiple R 2b These are independent of each other, arbitrary linking groups, and multiple R3b Each of the elements is independently a hydrogen atom or any substituent, and m1 is an integer of 1 or more.

[0074] In formula (B1), if m1 is 2 or more, multiple R 1b These may be any linking groups, independent of each other. 1b They may be the same as each other, or they may be different from each other. 1b It is preferable that this is a divalent hydrocarbon group or a divalent silicon-containing group. Examples of divalent hydrocarbon groups include those described above for formula (A1). 1b It is preferable that the group is an ethane-1,2-diyl group or a propane-1,2-diyl group. In formula (B1), if m1 is 2 or more, all R 1b However, it may also be a divalent hydrocarbon group (especially an ethane-1,2-diyl group).

[0075] The divalent silicon-containing group is not particularly limited as long as it contains a silicon atom. The silicon atom contained in the silicon-containing group is R in formula (B1). 1b It may bond with an adjacent oxygen atom (O) to form a silyl ether group. In formula (B1), the divalent silicon-containing group may be represented by the following formula (B2) or formula (B3).

[0076] In the above formula (B2), multiple R 4b These are hydrocarbon groups, independently of each other, and * indicates the bond position with the oxygen atom. Examples of hydrocarbon groups include those described above for formula (A2), and a methyl group is preferred.

[0077] In the above formula (B3), multiple R 4b These are, independently of each other, hydrocarbon groups, and R 5b R is a divalent hydrocarbon group, and * indicates the bond position with the oxygen atom. 4b Examples of hydrocarbon groups include those described above for formula (A2), and a methyl group is preferred. 5b Examples of the divalent hydrocarbon group in formula (A1) include those described above, and it is preferably a propane-1,3-diyl group.5b R in equation (B1) 2b It is preferable that it is bonded to an adjacent oxygen atom.

[0078] In the above formula (B1), multiple R 2b Preferably, each of these is a divalent hydrocarbon group, independently of the others. Examples of divalent hydrocarbon groups include those described above for formula (A1). In formula (B1), all R 2b It is preferable that the group is a methylene group.

[0079] Multiple R in the above formula (B1) 3b In this, any substituent is, for example, a hydrocarbon group. Examples of hydrocarbon groups include those mentioned above for formula (A2). In formula (B1), all R 3b Preferably, it is a hydrogen atom.

[0080] In the above formula (B1), m1 is 1 or greater as described above, and may be 2 or greater, 3 or greater, 4 or greater, 5 or greater, 6 or greater, 7 or greater, 8 or greater, or even 9 or greater. The upper limit of m1 is, for example, 15 or less, and may be 14 or less, 13 or less, 12 or less, 11 or less, or even 10 or less.

[0081] Specific examples of bifunctional epoxy compounds include poly(ethylene glycol) diglycidyl ether, poly(propylene glycol) diglycidyl ether, and poly(dimethylsiloxane) diglycidyl ether.

[0082] In polymer P, examples of constituent units U1 derived from a difunctional epoxy compound include those represented by formulas (B4) to (B6) below. Constituent units U1 represented by formulas (B4) to (B6) are derived from the difunctional epoxy compound represented by formula (B1) above.

[0083] In equations (B4) to (B6), R 1b , multiple R 2b , multiple R 3b And m1 is the same as in equation (B1). Multiple R 6b R are, independently of each other, hydrogen atoms or any substituent. 6bIn this, any substituent is, for example, a hydrocarbon group. Examples of hydrocarbon groups include those described above for formula (A2). Multiple R 6b R may be a methyl group. When a difunctional epoxy compound is reacted with a thiol compound, R in formulas (B4) to (B6) 6b Normally, this is a hydrogen atom, which together with the adjacent oxygen atom forms a hydroxyl group. After the above reaction, by modifying the hydroxyl group, R 6b Substituents can be introduced as such.

[0084] In polymer P, the ratio of the amount of substance of constituent unit U1 derived from the bifunctional epoxy compound to the amount of substance of all constituent unit U derived from the epoxy compound is, for example, 10 mol% or more, and may be 30 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, 95 mol% or more, or even 99 mol% or more. This ratio may also be 100 mol%.

[0085] It is preferable that polymer P has both constituent units U1a derived from a difunctional epoxy compound that does not contain silicon atoms and constituent units U1b derived from a difunctional epoxy compound that contains silicon atoms. In polymer P, the ratio of the amount of substance of constituent unit U1a to the amount of substance of all constituent units U1 derived from the difunctional epoxy compound is, for example, 50 mol% to 99 mol%, and may be 70 mol% to 95 mol%. The ratio of the amount of substance of constituent unit U1b to the amount of substance of all constituent units U1 derived from the difunctional epoxy compound is, for example, 1 mol% to 50 mol%, and may be 5 mol% to 30 mol%. It should be noted that polymer P does not necessarily have the above-mentioned constituent unit U1b.

[0086] As described above, the epoxy compound may include a polyfunctional epoxy compound having three or more epoxy groups. A polyfunctional epoxy compound can be used to form a polymer P having a crosslinked structure.

[0087] The number of epoxy groups in the polyfunctional epoxy compound may be four or more. The upper limit of the number of epoxy groups is not particularly limited and may be, for example, 10 or less, 8 or less, or even 5 or less.

[0088] The molecular weight (or number-average molecular weight, in some cases) of the polyfunctional epoxy compound is, for example, 200 to 2000, and may also be 500 to 1000. The epoxy equivalent of the polyfunctional epoxy compound is, for example, 100 g / eq. to 1000 g / eq., and may also be 200 g / eq. to 500 g / eq.

[0089] Polyfunctional epoxy compounds may contain oxygen atoms (specifically, oxygen atoms other than those contained in the epoxy group) or silicon atoms, and may have functional groups such as ether groups or silyl ether groups. It is preferable that polyfunctional epoxy compounds have ether groups.

[0090] In one molecule of polyfunctional epoxy compound, the ratio of the number of oxygen atoms to the total number of oxygen atoms and carbon atoms may be, for example, 5% to 50%, or 10% to 40%.

[0091] Polyfunctional epoxy compounds may or may not contain ring structures other than epoxy rings. The ring structures may consist only of carbon atoms or may be heterocyclic rings containing heteroatoms. The ring structures may be monocyclic or polycyclic. The number of carbon atoms in the ring structure is not particularly limited, for example, 3 to 10. Specific examples of ring structures include cyclohexane rings and benzene rings.

[0092] Specific examples of polyfunctional epoxy compounds include 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (e.g., TETRAD-C manufactured by Mitsubishi Gas Chemical Company), 4,4'-methylenebis(N,N-diglycidylaniline), and N,N-bis(2,3-epoxypropyl)-4-(2,3-epoxypropoxy)aniline. The polyfunctional epoxy compounds may also be Denacol EX-300 series, EX-400 series, EX-500 series, EX-600 series, etc., manufactured by Nagase ChemteX Corporation.

[0093] In polymer P, the ratio of the amount of substance of constituent units U2 derived from the polyfunctional epoxy compound to the amount of substance of all constituent units U derived from the epoxy compound is, for example, 0.1 mol% to 50 mol%, and may also be 1 mol% to 10 mol%. Polymer P may not contain constituent units U2.

[0094] As described above, the epoxy compound may include a monofunctional epoxy compound having one epoxy group. When polymer P contains a constituent unit U3 derived from a monofunctional epoxy compound, the separation performance of the separation functional layer 1 tends to improve.

[0095] The molecular weight (or number-average molecular weight in some cases) of the monofunctional epoxy compound is, for example, 100 or more, and may be 300 or more, or even 500 or more. The upper limit of the molecular weight of the monofunctional epoxy compound is, for example, 10,000 or less, and may be 5,000 or less, 3,000 or less, or even 1,000 or less.

[0096] Monofunctional epoxy compounds may contain oxygen atoms (specifically, oxygen atoms other than those contained in the epoxy group) or silicon atoms, and may have functional groups such as ether groups, silyl ether groups, or carboxyl groups. In particular, monofunctional epoxy compounds are preferably those that have an ether group.

[0097] When a monofunctional epoxy compound contains oxygen atoms, the ratio of the number of oxygen atoms to the total number of oxygen atoms and carbon atoms in one molecule of the monofunctional epoxy compound may be, for example, 10% or more, 15% or more, or even 20% or more. The upper limit of this ratio is, for example, 50% or less.

[0098] The monofunctional epoxy compound is preferably represented by the following formula (B7).

[0099] In the above formula (B7), R 7b R is an arbitrary linking group. 8b is an arbitrary linking group, and multiple R 9b R is a hydrogen atom or any substituent, independently of each other. 10b is any substituent, and m2 is a non-negative integer.

[0100] In formula (B7), if m² is 2 or more, multiple R 7b These may be any linking groups, independent of each other. 7b They may be the same as each other, or they may be different from each other. 7b It is preferable that this is a divalent hydrocarbon group or a divalent silicon-containing group. Examples of divalent hydrocarbon groups include those described above for formula (A1). 7b It is preferable that this is an ethane-1,2-diyl group or a propane-1,2-diyl group. In formula (B7), when m2 is 2 or more, all R 7b However, it may also be a divalent hydrocarbon group (especially an ethane-1,2-diyl group). Examples of divalent silicon-containing groups are those described above for formula (B1).

[0101] R 8b It is preferable that is a divalent hydrocarbon group. Examples of divalent hydrocarbon groups include those described above for formula (A1). In formula (B7), R 8b It is preferable that the group is a methylene group.

[0102] Multiple R 9b In this, any substituent is, for example, a hydrocarbon group. Examples of hydrocarbon groups include those mentioned above for formula (A2). In formula (B7), all R 9b Preferably, it is a hydrogen atom.

[0103] R 10b In this, any substituent is, for example, a hydrocarbon group. Examples of hydrocarbon groups include those described above for formula (A2). The hydrocarbon group may further have substituents such as carboxyl groups.

[0104] In the above formula (B7), m² is 0 or greater, as described above, and may be 1 or greater, or 2 or greater. There is no particular upper limit to m², for example, 20 or less.

[0105] In polymer P, the ratio of the amount of substance of constituent unit U3 derived from the monofunctional epoxy compound to the amount of substance of all constituent unit U derived from the epoxy compound is, for example, 0.1 mol% to 50 mol%, and may also be 1 mol% to 20 mol%. Polymer P may not contain constituent unit U3.

[0106] From the viewpoint of improving the mechanical strength of the separation functional layer 1, the polymer P preferably has a crosslinked structure. However, in some cases, the polymer P does not need to have a crosslinked or branched structure.

[0107] Polymer P is typically a reaction product of a group of compounds including thiol compounds and epoxy compounds, and may be a polymer formed by a polymerization reaction between a thiol compound and an epoxy compound. Preferably, polymer P is a crosslinked product (crosslinked material) in which a reaction product (typically a prepolymer) of a difunctional thiol compound and a difunctional epoxy compound is crosslinked with a polyfunctional thiol compound and / or a polyfunctional epoxy compound.

[0108] Polymer P typically has functional groups produced by the reaction of a thiol compound with an epoxy compound. Examples of these functional groups include sulfide groups (thioether groups) and hydroxyl groups. In polymer P, the hydroxyl groups may be modified, thereby being converted into other functional groups such as ether groups.

[0109] Polymer P may further contain other functional groups besides those produced by the reaction of the thiol compound and the epoxy compound. Examples of other functional groups include unreacted epoxy groups, thiol groups, ether groups, silyl ether groups, carboxyl groups, disulfide groups (-S-S-), sulfinyl groups (-S(=O)-), and sulfonyl groups (-S(=O)2-).

[0110] The polymer P preferably contains at least one selected from the group consisting of the structure represented by the following formula (C1) and the structure represented by the following formula (C2). These structures are typically formed by the reaction of a thiol group contained in a thiol compound with an epoxy group contained in an epoxy compound. These structures are incorporated into the main chain of polymer P.

[0111] In equations (C1) and (C2), R 1c is a hydrogen atom or any substituent, and there are multiple R 2c Each of the elements is independently a hydrogen atom or any substituent, and * indicates the bonding position in the main chain of polymer P.

[0112] R in equations (C1) and (C2) 1c In this, any substituent is, for example, a hydrocarbon group. Examples of hydrocarbon groups include those described above for formula (A2). 1c R may be a methyl group. Furthermore, when an epoxy compound is reacted with a thiol compound, 1c Normally, this is a hydrogen atom, which together with the adjacent oxygen atom forms a hydroxyl group. After the above reaction, by modifying the hydroxyl group, R 1c Substituents can be introduced as such.

[0113] Multiple Rs in formulas (C1) and (C2) 2c In this, any substituent is, for example, a hydrocarbon group. Examples of hydrocarbon groups include those described above for formula (A2). In formulas (C1) and (C2), all R 2c Preferably, it is a hydrogen atom.

[0114] The glass transition temperature (Tg) of polymer P is not particularly limited and may be, for example, 0°C or lower, and may be -70°C to -40°C, or about -55°C. In this specification, the glass transition temperature Tg is defined as the intermediate glass transition temperature (T) determined in accordance with the provisions of JIS K7121:1987. mg ) means.

[0115] The gel fraction of polymer P is preferably 50% or more. The upper limit of the gel fraction of polymer P is not particularly limited, and may be, for example, 95% or less, or 90% or less.

[0116] The polymer P content 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, or even 95 wt% or more. The separation functional layer 1 may be composed substantially of polymer P alone.

[0117] The separation functional layer 1 may further contain other components besides polymer P. Examples of other components include other polymers, oligomers, fillers, etc.

[0118] 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, 15 μm or less, 10 μm or less, 5.0 μm or less, 2.0 μm or less, 1.0 μm or less, 0.5 μm or less, and even 0.2 μm or less. The thickness of the separation functional layer 1 may be 0.05 μm or more, or 0.1 μm or more.

[0119] (Method for manufacturing the separation functional layer) In this embodiment, the method for manufacturing the separation functional layer 1 preferably includes the steps of applying a coating solution having a group of compounds including thiol compounds and epoxy compounds onto a substrate to form a coating film, and drying the coating film to form a polymer P from the group of compounds.

[0120] Examples of thiol compounds and epoxy compounds included in the compound group are those mentioned above. In the coating solution, some of the compounds may have reacted and formed reactants. These reactants make it easier to adjust the viscosity of the coating solution to a range suitable for coating.

[0121] The coating solution preferably contains a reaction product (typically a prepolymer) of a difunctional thiol compound and a difunctional epoxy compound. The manufacturing method of this embodiment may further include the steps of: reacting a difunctional thiol compound and a difunctional epoxy compound to form a prepolymer P1; and preparing a coating solution containing the prepolymer P1 and at least one selected from the group consisting of a polyfunctional thiol compound and a polyfunctional epoxy compound.

[0122] The prepolymer P1 can be formed, for example, by the following method. First, a solution A containing a difunctional thiol compound and a difunctional epoxy compound is prepared. In solution A, the content of the difunctional thiol compound is, for example, 0.1 wt% to 30 wt%, and the content of the difunctional epoxy compound is, for example, 0.1 wt% to 30 wt%. In solution A, it is preferable to set the blending ratio of the difunctional thiol compound to the difunctional epoxy compound such that the ratio of the equivalent amount of thiol groups in the difunctional thiol compound to the equivalent amount of epoxy groups in the difunctional epoxy compound is, for example, 0.5 to 1.5, preferably 0.7 to 0.9. Typically, solution A does not contain polyfunctional thiol compounds or polyfunctional epoxy compounds.

[0123] Solution A preferably further contains a solvent. The solvent is preferably one that has low reactivity with and can dissolve difunctional thiol compounds and difunctional epoxy compounds. Examples of solvents include relatively unreactive alcohol compounds such as isopropanol (IPA). The solvent may further contain water. The solvent content in solution A is not particularly limited, and is, for example, 30 wt% to 99 wt%.

[0124] Solution A may further contain additives. Examples of additives include reducing agents, bases, and curing retarders. Reducing agents can cleave the disulfide bonds in the disulfide compounds formed by the oxidation of thiol compounds, returning them to their original thiol form. Examples of reducing agents include tris(2-carboxyethyl)phosphine hydrochloride and sodium borohydride (NaBH4).

[0125] Depending on the base, a highly nucleophilic thiolate group can be formed by abstracting a proton from the thiol group contained in the thiol compound. This can accelerate the reaction between the thiol compound and the epoxy compound. Examples of bases include hydroxides such as lithium hydroxide and sodium hydroxide.

[0126] The additive content in solution A is not particularly limited, and is, for example, 0.01 wt% to 10 wt%. If solution A contains a base as an additive, the amount of base added is preferably a catalytic amount. A catalytic amount of base helps to suppress side reactions between the base and the epoxy compound. However, solution A may contain an excess amount of base.

[0127] Next, solution A is stirred to react the difunctional thiol compound with the difunctional epoxy compound. This forms prepolymer P1. During the above reaction, solution A may or may not be heated. The above reaction may be carried out at room temperature (25°C). The above reaction tends to proceed relatively quickly, with a reaction time of, for example, 10 seconds to 2 hours.

[0128] Prepolymer P1 typically does not have a cross-linked structure, and its main chain is linear. Solution A containing this prepolymer P1 tends to have high storage stability and a long pot life.

[0129] The weight-average molecular weight of prepolymer P1 is not particularly limited as long as it is greater than the molecular weight of the difunctional thiol compound or the difunctional epoxy compound, for example, 500 or more. The upper limit of the weight-average molecular weight of prepolymer P1 is, for example, 1 million or less. Preferably, the weight-average molecular weight of prepolymer P1 is 3,000 to 20,000.

[0130] The coating solution can be prepared, for example, by the following method. First, a solution B is prepared containing at least one selected from the group consisting of polyfunctional thiol compounds and polyfunctional epoxy compounds. It is preferable that solution B contains only one of the polyfunctional thiol compounds and the polyfunctional epoxy compounds, and it is particularly preferable that it contains only the polyfunctional thiol compound. In solution B, the content of the polyfunctional thiol compound is, for example, 0.1 wt% to 30 wt%, and the content of the polyfunctional epoxy compound is, for example, 0.1 wt% to 30 wt%.

[0131] Solution B preferably further contains a solvent. Examples of solvents include those described above for Solution A, with isopropanol being preferred. The solvent content in Solution B is not particularly limited, and is, for example, 30 wt% to 99 wt%.

[0132] Solution B may or may not contain additional additives. Examples of additives include those mentioned above for solution A.

[0133] Next, solution A containing prepolymer P1 and solution B are mixed. This allows the coating solution to be prepared. The coating solution prepared by this method typically contains prepolymer P1 and at least one selected from the group consisting of polyfunctional thiol compounds and polyfunctional epoxy compounds, and further contains solvents and additives derived from solutions A and B.

[0134] The method for preparing the coating solution is not limited to those described above. The coating solution may also be prepared by mixing a thiol compound, an epoxy compound, and a solvent, and adding additives as needed.

[0135] The content of the compound group (thiol compounds and epoxy compounds) in the coating solution is, for example, 0.1 wt% to 30 wt%. In the coating solution, the blending ratio of the thiol compounds and epoxy compounds is preferably set such that the ratio of the equivalent amount of thiol groups in the thiol compound to the equivalent amount of epoxy groups in the epoxy compound is, for example, 0.8 or more, preferably 1.0 or more, and more preferably 1.2 or more. The upper limit of the above ratio is, for example, 2.0 or less, and may also be 1.5 or less. In the case where a portion of the compound group reacts in the coating solution and a reactant is formed, the above content and blending ratio refer to values ​​calculated based on the thiol compounds and epoxy compounds used to form the reactant and the unreacted thiol compounds and epoxy compounds.

[0136] In the manufacturing method of this embodiment, as described above, a coating liquid is applied to a substrate to form a coating film. The substrate to which the coating liquid is applied is typically a release liner. Examples of substrates include films containing resin; paper; and sheets containing metal materials such as aluminum and stainless steel. Sheets containing metal materials tend to have high heat resistance. The substrate is preferably a film containing resin because it has 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.

[0137] 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 types.

[0138] The thickness of the substrate is not particularly limited, and is, for example, 5 to 100 μm, preferably 10 to 50 μm.

[0139] Furthermore, a surface modification treatment may be performed on the substrate before applying the coating solution. 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.

[0140] 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 / m 2 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.

[0141] The method of applying the coating solution to the substrate is not particularly limited, and for example, spin coating, dip coating, slot die coating, gravure coating, comma coating, spray coating, etc., can be used. The coating solution may also be applied to the substrate using an applicator, wire bar, non-wire bar, etc. The coating solution may be applied to the surface of a substrate that has undergone stripping treatment or surface modification treatment.

[0142] A coating film is formed by applying the coating solution 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.

[0143] In the manufacturing method of this embodiment, as described above, the coated film is dried to form polymer P from the group of compounds. This yields the separation functional layer 1. It is preferable that polymer P is formed by a reaction between the above-described prepolymer P1 and at least one selected from the group consisting of polyfunctional thiol compounds and polyfunctional epoxy compounds. In particular, this reaction is a crosslinking reaction of prepolymer P1 with a polyfunctional thiol compound and / or a polyfunctional epoxy compound. Polymer P may also be formed by a polymerization reaction between a thiol compound and an epoxy compound.

[0144] The drying conditions for the coating film are not particularly limited, as long as polymer P can be formed from the compound group. The drying temperature of the coating film may be, for example, 50°C or higher, and may be 70°C or higher. The upper limit of the drying temperature may be, for example, 150°C or lower, and may be 100°C or lower. The drying time of the coating film may be, for example, 10 seconds or more, and may be 30 seconds or more. The upper limit of the drying time may be, for example, 1 hour or less, 30 minutes or less, and even 10 minutes or less. In this embodiment, the formation of polymer P from the compound group tends to proceed relatively quickly. Therefore, the coating film tends to harden relatively quickly, and as a result, the separation functional layer 1 is easily formed uniformly.

[0145] The coating film can be dried using a heater or the like. For example, the coating film may be dried by passing it through a heating section equipped with a heater. The coating 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. In this embodiment, the separation functional layer 1 can also be formed using a roll-to-roll method.

[0146] Furthermore, if the coating solution contains a curing retarder, the separation functional layer 1 prepared by the above method also tends to contain a curing retarder. In this case, the curing retarder may be removed from the separation functional layer 1 by washing it with water or the like.

[0147] The manufacturing method of this embodiment preferably further includes 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 membrane can be obtained.

[0148] The method for manufacturing the separation functional layer 1 is not limited to those described above. For example, the method for manufacturing the separation functional layer 1 may include the steps of applying a coating solution containing polymer P onto a substrate to form a coating film, and drying the coating film to form a separation functional layer.

[0149] (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 the acidic gas. Examples of other gases include nonpolar gases such as hydrogen, nitrogen, and methane, and inert gases such as helium, and preferably nitrogen. In particular, the separation functional layer 1 of this embodiment is suitable for separating carbon dioxide from a gas mixture containing carbon dioxide and nitrogen. However, the applications of the separation functional layer 1 are not limited to separating acidic gases from the gas mixture described above.

[0150] <Embodiment of the Separation Membrane> As shown in Figure 2, the separation membrane 10 of this embodiment preferably comprises the separation functional layer 1 described above and further comprises a porous support 3 that supports the separation functional layer 1. The separation membrane 10 may further comprise an intermediate layer 2 disposed between the separation functional layer 1 and the porous support 3, and in direct contact with the separation functional layer 1 and the porous support 3, respectively.

[0151] (Intermediate layer) Intermediate layer 2 preferably contains a resin. Examples of resins include silicone resins such as polydimethylsiloxane; fluororesins such as polytetrafluoroethylene; epoxy resins such as polyethylene oxide; polyimide resins; polysulfone resins; polyacetylene resins such as polytrimethylsilylpropine and polydiphenylacetylene; polyolefin resins such as polymethylpentene; and polyurethane resins. Intermediate layer 2 preferably contains a silicone resin.

[0152] The intermediate layer 2 may further contain fillers dispersed in the resin (matrix). The fillers may be spaced apart from each other within the matrix, or they may be partially aggregated. However, the intermediate layer 2 may not contain fillers and may be substantially composed of resin.

[0153] The filler may contain inorganic materials or organic materials. Examples of inorganic materials included in the filler include silica, titania, and alumina. It is preferable that the filler contains silica.

[0154] The average particle size of the filler is not particularly limited, but is, for example, 100 nm or less, preferably 50 nm or less, and more preferably 20 nm or less. The lower limit of the average particle size of the filler is, for example, 1 nm. The average particle size of the filler can be determined 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 filler 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 filler. The particle size of any number of fillers (at least 50) is calculated, and the average of the calculated values ​​is considered to be the average particle size of the filler. The shape of the filler is not particularly limited, and may be spherical, ellipsoidal, flaky, or fibrous.

[0155] The filler 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 filler content in the intermediate layer 2 is not particularly limited, but is, for example, 30 wt%.

[0156] The thickness of the intermediate layer 2 is not particularly limited and may be, for example, 50 μm or less, but may also be 30 μm or less, 10 μm or less, 1 μm or less, or even 0.5 μm or less. The lower limit of the thickness of the intermediate layer 2 is not particularly limited and may be, for example, 0.01 μm or more, but may also be 0.1 μm or more.

[0157] The intermediate layer 2 may be formed from an emulsion resin composition. The emulsion resin composition means a liquid containing a dispersion medium and a polymer emulsified in the dispersion medium. The emulsion resin composition preferably contains water as the dispersion medium. That is, the emulsion resin composition is preferably an oil-in-water (O / W) emulsion. The emulsion resin composition may contain an organic solvent as the dispersion medium, either in place of water or together with water.

[0158] (Porous Support) The porous support 3 supports the separation functional layer 1 via the intermediate layer 2. Examples of the 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.

[0159] The porous support 3 has an average pore diameter of, for example, 0.01 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.

[0160] (Protective layer) The separation membrane 10 may further include a protective layer (not shown) for protecting the separation functional layer 1. The protective layer is preferably in direct contact with the separation functional layer 1. The separation functional layer 1 is typically located between the protective layer and the intermediate layer 2.

[0161] The protective layer preferably contains a resin. Examples of resins include those described above for the intermediate layer 2. The protective layer preferably contains a silicone resin.

[0162] The thickness of the protective layer is not particularly limited, and is, for example, 0.1 μm to 50 μm.

[0163] (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, spin coating, dip coating, slot die coating, gravure coating, comma coating, spray coating, etc., can be used. The coating solution may also be applied to the substrate using an applicator, wire bar, non-wire bar, etc. 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.

[0164] 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 allows a separation membrane 10 to be obtained. As an example, the separation membrane 10 can be produced by using the laminate of the porous support 3 and the intermediate layer 2 as a substrate and carrying out the above-described manufacturing method for the separation functional layer 1.

[0165] The method for producing the separation membrane 10 is not limited to the method described above, and the separation membrane 10 may also be produced by the following method. First, a separation functional layer 1 is prepared on a substrate such as a peelable liner by the method described above. Next, an intermediate layer 2 is formed by coating a coating solution containing the material for the intermediate layer 2 onto the separation functional layer 1 and drying it. The laminate of the intermediate layer 2 and the separation functional layer 1 is transferred to a porous support 3. This gives rise to the separation membrane 10.

[0166] (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 and may be a hollow fiber membrane. As an example, the separation membrane 10 as a hollow fiber membrane includes a separation functional layer 1 and a porous support 3, while it may not include an intermediate layer 2.

[0167] (Characteristics of the separation membrane) The separation membrane 10 of this embodiment can preferentially permeate an acidic gas contained in a mixed gas, for example. As an example, when carbon dioxide at a pressure of 0.1 MPa is supplied to a space adjacent to one surface of the separation membrane 10, the permeation rate T1 of carbon dioxide permeating through the separation membrane 10 CO2 is, for example, 10 GPU or more, 50 GPU or more, 100 GPU or more, 300 GPU or more, and even 500 GPU or more. The permeation rate T1 CO2 has no particular upper limit and may be, for example, 5000 GPU or less, or 1000 GPU or less. Note that GPU is 10 -6 ·cm 3 (STP) / (sec·cm 2 ·cmHg). cm 3 (STP) means the volume of a gas at 1 atm and 0°C.

[0168] The permeation rate T1 CO2 can be calculated by the following method. First, carbon dioxide at a pressure of 0.1 MPa and a temperature of 25°C is supplied to a space adjacent to one surface of the separation membrane 10 (for example, the main surface 11 on the separation functional layer side of the separation membrane 10). As a result, a permeated fluid (carbon dioxide) that has permeated through the separation membrane 10 is obtained from the other main surface of the separation membrane 10 (for example, the main surface 12 on the porous support side of the separation membrane 10). The flow rate of this permeated fluid is measured with a mass flow meter, and from the obtained result, the permeation rate T1 of carbon dioxide CO2 (GPU) is measured. Depending on the flow rate of the permeated fluid, a soap film flow meter may be used instead of the mass flow meter.

[0169] The separation factor α1 of carbon dioxide with respect to nitrogen of the separation membrane 10 is not particularly limited, and for example, it is 20 or more, and may be 23 or more, 25 or more, or even 28 or more. The upper limit of the separation factor α1 is not particularly limited, and for example, it may be 100 or less, or 50 or less.

[0170] The separation factor α1 is the permeation rate T1 of nitrogen permeating through the separation membrane 10 when nitrogen at a pressure of 0.1 MPa is supplied to the space adjacent to one surface of the separation membrane 10. N2 (GPU) with respect to the permeation rate T1 of carbon dioxide permeating through the separation membrane 10 when carbon dioxide at a pressure of 0.1 MPa is supplied to the space. CO2 (GPU) of the ratio T1 CO2 / T1 N2 It means. The permeation rate T1 of nitrogen N2 Except for using nitrogen at a pressure of 0.1 MPa and a temperature of 25 °C instead of carbon dioxide, it can be measured by the method described above for the permeation rate T1 of carbon dioxide. CO2

[0171] The separation functional layer 1 included in the separation membrane 10 of the present embodiment has high acid resistance, and the decrease in separation performance under acidic conditions tends to be suppressed. As an example, the ratio of the separation factor α2 of carbon dioxide with respect to nitrogen of the separation membrane 10 after the durability test to the separation factor α1 of carbon dioxide with respect to nitrogen of the separation membrane 10 before performing the following durability test is, for example, 50% or more, and may be 60% or more, 70% or more, or even 75% or more. The upper limit of this ratio may be, for example, 99% or less, or 95% or less. Durability test: A test gas in which a mixed gas composed of nitrogen and nitrogen oxides (NOx) and water vapor are mixed is brought into contact with the separation membrane 10 for 6 days. Here, the content rate of nitrogen oxides in the mixed gas is 500 volppm, and the test gas has a temperature of 25 °C and a humidity of 60% RH.

[0172] The above durability test can be carried out by the following method. First, the separation membrane 10 is placed inside the gas bag. Preferably, the gas bag is one that can permeate water vapor but hardly permeates nitrogen or nitrogen oxides. For example, the Smart Bag PA (model AAK-5) manufactured by GL Sciences can be used. Next, a mixed gas composed of nitrogen and nitrogen oxides (temperature: 25°C, pressure: 101.325 kPa, nitrogen oxide content: 500 vol ppm) is sealed inside the gas bag, and after performing the removal operation once, the mixed gas is sealed inside the gas bag again and the gas bag is sealed.

[0173] Next, the gas bag is placed in an environment with a temperature of 25°C and a humidity of 60% RH. This allows water vapor to permeate the gas bag, and the water vapor mixes with the aforementioned gas mixture inside the bag, forming a test gas (temperature: 25°C, humidity: 60% RH). A durability test can be performed by leaving the gas bag in this state for 6 days.

[0174] The separation coefficient α2 of carbon dioxide relative to nitrogen of the separation membrane 10 after durability testing is, for example, 15 or more, and may be 18 or more, 20 or more, or even 23 or more. The upper limit of the separation coefficient α2 is not particularly limited and may be, for example, 100 or less, and may be 50 or less.

[0175] The separation coefficient α2 is the nitrogen permeation rate T2 when nitrogen at a pressure of 0.1 MPa is supplied to the space adjacent to one side of the separation membrane 10 after a durability test. N2 The permeation rate T2 of carbon dioxide that permeates through the separation membrane 10 when carbon dioxide at a pressure of 0.1 MPa is supplied to the space (GPU). CO2 (GPU) ratio T2 CO2 / T2 N2 This means: Transmission velocity T2 CO2 and T2 N2 Except for using the separation membrane 10 after durability testing, the transmission rate T1 CO2 and T1 N2 This can be measured by the method described above.

[0176] Transmission rate T2 CO2For example, it may be 10 GPUs or more, 50 GPUs or more, 100 GPUs or more, or even 300 GPUs or more. Transmission velocity T2 CO2 The upper limit is, for example, 5000 GPUs or less, and may also be 1000 GPUs or less.

[0177] The permeation rate T1 of carbon dioxide that passes through the separation membrane 10 when carbon dioxide at a pressure of 0.1 MPa is supplied to the space adjacent to one side of the separation membrane 10 before the durability test is performed. CO2 The permeation rate T2 of carbon dioxide that permeates through the separation membrane 10 when carbon dioxide at a pressure of 0.1 MPa is supplied to the space adjacent to one side of the separation membrane 10 after a durability test against GPU. CO2 The GPU ratio may be, for example, 30% or more, 40% or more, or even 50% or more. The upper limit of this ratio may be, for example, 100% or less, or 80% or less.

[0178] <Embodiment of Membrane Separation Apparatus> As shown in Figure 3, the membrane separation apparatus 100 of this embodiment comprises 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 comprises 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.

[0179] The first chamber 21 has an inlet 21a and an outlet 21b. The second chamber 22 has an outlet 22a. Each of the inlet 21a, outlet 21b, and outlet 22a is, for example, an opening formed in the wall surface of the tank 20.

[0180] Membrane separation using the membrane separation apparatus 100 is performed, for example, 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, and under standard conditions, it is, for example, 0.01 vol% (100 ppm) or more, 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, and under standard conditions, it is, for example, 90 vol%.

[0181] 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.

[0182] 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.

[0183] 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. The permeate fluid 35 mainly contains, for example, an acidic gas. However, the permeate fluid 35 may also contain small amounts of other gases besides acidic gases. The permeate fluid 35 is discharged to the outside of the tank 20 through the outlet 22a.

[0184] 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.

[0185] 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.

[0186] <Modifications of the Membrane Separation Apparatus> The membrane separation apparatus 100 may be a spiral-type membrane element, a hollow fiber membrane element, 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 the separation membrane 10. The laminate 42 may contain a separation functional layer 1 by itself instead of the separation membrane 10.

[0187] 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.

[0188] 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).

[0189] 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.

[0190] Membrane separation using the membrane separation device 110 is performed, for example, 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.

[0191] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto.

[0192] (Example 1) First, an emulsion resin composition was prepared by mixing an aqueous emulsion containing a silicone polymer (POLON-MF-56 manufactured by Shin-Etsu Chemical Co., Ltd.), an aqueous emulsion containing a urethane polymer (Takelac W-6010 manufactured by Mitsui Chemicals, Inc.), and ion-exchanged water for dilution. Next, a coating film was obtained by applying the prepared emulsion resin composition onto a porous support using a non-wire bar coater (wet thickness 5 μm). As the porous support, a polysulfone porous substrate manufactured by Nitto Denko Corporation (a laminate in which a microporous layer of polysulfone is formed on a polyester nonwoven fabric) was used. The obtained coating film was dried at 130°C for 10 minutes to form an intermediate layer with a thickness of 0.2 μm. For this intermediate layer, 0.11 kW・min / m 2 Corona treatment was performed with this discharge amount.

[0193] Next, 0.9 mmol of poly(ethylene glycol) diglycidyl ether (Sigma-Aldrich, number average molecular weight 500) and 0.1 mmol of poly(dimethylsiloxane) diglycidyl ether (Sigma-Aldrich, number average molecular weight 800) as difunctional epoxy compounds, 0.8 mmol of 3,6-dioxa-1,8-octanedithiol as a difunctional thiol compound, 1 mg of tris(2-carboxyethyl)phosphine hydrochloride as a reducing agent, and 420 μL of an aqueous solution containing lithium hydroxide at a concentration of 0.25 mmol / L as a base were dissolved in 5.5 mL of isopropanol and stirred at room temperature for 30 minutes. This procedure allowed the reaction between the difunctional epoxy compounds and the difunctional thiol compounds to proceed, forming a prepolymer. This yielded solution A containing the prepolymer. The aqueous solution of lithium hydroxide was prepared using lithium hydroxide monohydrate (Fujifilm Wako Pure Chemical Industries, Ltd.) and deionized water.

[0194] Next, 0.1 mmol of pentaerythritol tetrapropanthol (Multhiol Y-4, manufactured by Sakai Chemical Industry Co., Ltd.), a tetrafunctional thiol compound, was dissolved in 5.5 mL of isopropanol to obtain solution B. Solutions A and B were mixed and stirred for 5 minutes to prepare the coating solution.

[0195] Next, a coating film was obtained by applying the prepared coating solution onto the intermediate layer described above. Then, the obtained coating film was dried in a 70°C oven for 30 seconds, causing the prepolymer to react with the tetrafunctional thiol compound and forming a separation functional layer (thickness: 0.15 μm). This obtained the separation film of Example 1.

[0196] (Example 2) The separation membrane of Example 2 was obtained by the same method as in Example 1, except that solution B was prepared by dissolving 6 mmol of tributyl borate as a curing retarder in isopropanol together with the tetrafunctional thiol compound. In Example 2, the prepared separation membrane was immersed in deionized water for 2.5 hours to remove the curing retarder from the separation functional layer. The separation membrane after immersion in deionized water was dried at 60°C for 1 hour.

[0197] (Example 3) Intermediate layer First, a resin composition containing a silicone polymer (YSR3022 from Momentive Corporation) was prepared. Next, a coating film was obtained by applying the resin composition onto a porous support using a non-wire bar coater (wet thickness 5 μm). As the porous support, a polysulfone porous substrate from Nitto Denko Corporation (a laminate in which a microporous layer of polysulfone is formed on a polyester nonwoven fabric) was used. An intermediate layer with a thickness of 0.2 μm was formed by drying the obtained coating film at 130°C for 10 minutes. For this intermediate layer, 0.11 kW・min / m 2 Corona treatment was performed with this discharge amount.

[0198] Next, RAFT reagent CTA-1 was synthesized by the following method. First, triethylamine (6.4 mL, 0.068 mol) was added to anhydrous CHCl3 (20 mL) and stirred at room temperature. Next, butanethiol (7.5 mL, 0.066 mol) and CS2 (4 mL, 0.066 mol) were added dropwise to the resulting solution to obtain a yellow-orange solution. After 30 minutes, dimethyl-2,6-dibromoheptanedioate (5 mL, 0.033 mol) was slowly added. The resulting reaction mixture was stirred for 16 hours, then diluted with CHCl3 (20 mL) and washed three times with 100 mL of water. The resulting organic phase was dried over MgSO4, concentrated, and passed through a short column packed with basic Al2O3. By evaporating the solvent with an evaporator, an orange oil (RAFT reagent CTA-1) was obtained. The structure of CTA-1 is represented by the following formula.

[0199] RAFT Oligomer Next, the RAFT oligomer was synthesized by the following method. First, tetrahydrofurfuryl acrylate (7.81 g), the above-mentioned CTA-1 (84.65 mg), and azobisisobutyronitrile (AIBN, 20.53 mg) were dissolved in ethyl acetate (130.8 g) and reacted at 70°C for 3.5 hours. After the reaction, the solvent was removed and the crude product was reprecipitation in hexane cooled with ice water. After removing the supernatant, the target product (RAFT oligomer) was obtained by removing the hexane. (Yield 49.7%). The structure of the RAFT oligomer is represented by the following formula.

[0200] Polymer P Next, RAFT oligomer (200 mg), hexylamine (24 mg), and tris(2-carboxyethyl)phosphine hydrochloride (TCEP) (2 mg) were dissolved in ethyl acetate (0.8 mL) and heated at 60°C for 3 hours to convert the trithiocarbonate group of the RAFT oligomer to a thiol group. Next, the reaction solution was reprecipitated in hexane, the residue was washed with diethyl ether, and then dried. This yielded the RAFT oligomer (SH-terminated) represented by the following formula.

[0201] Next, RAFT oligomer (SH-terminated) (168.2 mg), PEG diglycidyl ether (64.7 mg), poly(dimethylsiloxane) diglycidyl ether (Sigma-Aldrich, number-average molecular weight 800) (103.5 mg), 3,6-dioxa-1,8-octanedithiol (44.6 mg), and TCEP (1 mg) were dissolved in a 1 mL solution of THF / H2O (9:1). To the resulting solution, 0.04 mL of a 0.27 mmol / L aqueous NaOH solution was added. After heating at 70°C for 30 minutes, the reaction solution was reprecipitated in hexane, and the residue was washed with diethyl ether. Polymer P was obtained. Polymer P was dried in a vacuum oven at 60°C for 2 hours.

[0202] - Separation Functional Layer The polymer P mentioned above was dissolved in an IPA / H2O (=9 / 1) solution to prepare a 1 wt% coating solution. A coating film was obtained by applying the prepared coating solution onto the above intermediate layer. Next, the obtained coating film was dried in a 70°C oven for 30 seconds. By repeating this coating and drying operation twice, a separation functional layer with a thickness of 0.35 μm was formed. This obtained the separation film of Example 3.

[0203] (Comparative Example 1) First, a laminate was prepared by forming an intermediate layer on a porous support using the same method as in Example 1. Next, a coating solution was prepared by dissolving polyether block amide (PEBAX, manufactured by Arkema) in a mixed solvent of ethanol and water (ethanol:water = 7:3). A coating film was obtained by applying the prepared coating solution onto the intermediate layer. Next, a separation functional layer (thickness: 0.15 μm) was formed by drying the obtained coating film in an oven at 70°C for 30 seconds. This obtained the separation film of Comparative Example 1.

[0204] (Comparative Example 2) First, a laminate was prepared in which an intermediate layer was formed on a porous support using the same method as in Example 1. Next, 0.9 mmol of poly(ethylene glycol) diglycidyl ether (manufactured by Sigma-Aldrich, number average molecular weight 500) and 0.1 mmol of poly(dimethylsiloxane) diglycidyl ether (manufactured by Sigma-Aldrich, number average molecular weight 800), which are difunctional epoxy compounds, and 1.0 mmol of poly(propylene glycol) bis(2-aminopropyl ether) (manufactured by Sigma-Aldrich), which is a difunctional amine compound, were dissolved in 11.3 mL of isopropanol and stirred at 90°C for 120 minutes. Through this operation, the difunctional epoxy compounds and the difunctional amine compounds partially reacted, and a partially reacted product (partially polymerized product) was obtained. This yielded a coating solution containing the partially reacted product.

[0205] Next, a coating film was obtained by applying the prepared coating solution onto the intermediate layer described above. Since the coating solution hardens as the reaction between the difunctional epoxy compound and the difunctional amine compound progresses further, the above coating operation was carried out with due consideration to the pot life. Next, the obtained coating film was dried in a 70°C oven for 30 minutes, allowing the reaction between the difunctional epoxy compound and the difunctional amine compound to proceed further, forming a separation functional layer (thickness: 0.15 μm). This yielded the separation film of Comparative Example 2.

[0206] [Characterization of Separation Membranes] (Gas Permeation Test) Gas permeation tests were performed on the separation membranes prepared in the examples and comparative examples using the following method. First, the separation membrane was set in a metal cell and sealed with an O-ring to prevent leakage. Next, carbon dioxide was injected into the metal cell so that it came into contact with the main surface of the separation functional layer side of the separation membrane at a pressure of 0.1 MPa and a temperature of 25°C. As a result, permeated fluid (carbon dioxide) was obtained from the main surface of the porous support side of the separation membrane. The flow rate of the permeated fluid was measured, and from the obtained results, the permeation rate of carbon dioxide T1 CO2 We measured it.

[0207] Furthermore, regarding the fabricated separation membrane, the nitrogen permeation rate T1 N2 The nitrogen permeation rate T1 was measured. N2Except for using nitrogen at a pressure of 0.1 MPa and a temperature of 25°C instead of carbon dioxide, the carbon dioxide permeation rate T1 CO2 The nitrogen permeation rate T1 was measured using the method described above. Based on the results obtained, the nitrogen permeation rate T1 N2 (GPU) carbon dioxide permeation rate T1 CO2 (GPU) ratio T1 CO2 / T1 N2 The value was calculated and considered as the separation coefficient α1 of carbon dioxide relative to nitrogen.

[0208] (Durability Test) The separation membranes prepared in the examples and comparative examples were subjected to the durability tests described above. For the durability tests, a Smart Bag PA (model AAK-5, capacity 5L) manufactured by GL Sciences Co., Ltd. was used as the gas bag.

[0209] For the separation membrane after durability testing, the carbon dioxide permeation rate T2 was measured using the same method as the gas permeation test described above. CO2 And the nitrogen permeation rate T2 N2 (GPU) was measured. Based on the results obtained, the nitrogen permeation rate T2 was determined. N2 (GPU) carbon dioxide permeation rate T2 CO2 (GPU) ratio T2 CO2 / T2 N2 The following was calculated and the calculated value was considered as the separation coefficient of carbon dioxide relative to nitrogen α2. Furthermore, the permeation rate T1 CO2 Transmission rate T2 for (GPU) CO2 The ratio of GPUs and the ratio of the separation coefficient α2 to the separation coefficient α1 were also calculated.

[0210]

[0211] As can be seen from Table 1, the separation membrane of the example, which had a separation functional layer containing a polymer having structural units derived from thiol compounds and structural units derived from epoxy compounds, had a higher ratio α2 / α1 compared to the comparative example. From this result, it can be seen that the separation functional layer in the example had high acid resistance, and the decrease in separation performance under acidic conditions was suppressed.

[0212] The separation membrane in Comparative Example 1 had a low ratio α2 / α1, and furthermore, the ratio T2 CO2 / T1CO2 The result was over 100%. From this result, it is presumed that in Comparative Example 1, the polymer (polyether block amide) contained in the separation functional layer was hydrolyzed during the durability test, causing defects in the separation functional layer.

[0213] In Comparative Example 2, a long time was required between the preparation of the coating film and the formation of the separation functional layer. As a result, the separation functional layer in Comparative Example 2 was not uniformly formed, and it is estimated that this caused the separation coefficient α1 of the separation film to fall below 20.

[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 off-gas in chemical plants or thermal power plants.

Claims

1. A separation functional layer comprising a polymer having structural units derived from a thiol compound and structural units derived from an epoxy compound.

2. The separation functional layer according to claim 1, wherein the thiol compound comprises a bifunctional thiol compound having two thiol groups.

3. The separation functional layer according to claim 2, wherein the difunctional thiol compound comprises at least one selected from the group consisting of an oxygen atom and a silicon atom.

4. The separation functional layer according to claim 2, wherein the difunctional thiol compound is represented by the following formula (A1). In the above formula (A1), multiple R 1a These are independent of each other and are arbitrary linking elements, where n1 is an integer greater than or equal to 1.

5. Multiple R 1a The separation functional layer according to claim 4, wherein each of the members is independently a divalent hydrocarbon group or a divalent silicon-containing group.

6. Multiple R 1a The separation functional layer according to claim 4, wherein each of the groups is independently an ethane-1,2-diyl group or a propane-1,2-diyl group.

7. The separation functional layer according to claim 1, wherein the thiol compound comprises a polyfunctional thiol compound having three or more thiol groups.

8. The separation functional layer according to claim 1, wherein the epoxy compound comprises a bifunctional epoxy compound having two epoxy groups.

9. The separation functional layer according to claim 8, wherein the bifunctional epoxy compound comprises at least one selected from the group consisting of an oxygen atom and a silicon atom.

10. The separation functional layer according to claim 8, wherein the bifunctional epoxy compound is represented by the following formula (B1). In the above formula (B1), R 1b is an arbitrary linking group, and multiple R 2b These are independent of each other, arbitrary linking groups, and multiple R 3b Each of the elements is independently a hydrogen atom or any substituent, and m1 is an integer of 1 or more.

11. The aforementioned R 1b The separation functional layer according to claim 10, wherein is a divalent hydrocarbon group or a divalent silicon-containing group.

12. The aforementioned R 1b The separation functional layer according to claim 10, wherein is an ethane-1,2-diyl group or a propane-1,2-diyl group.

13. The separation functional layer according to claim 1, wherein the polymer contains at least one selected from the group consisting of a structure represented by the following formula (C1) and a structure represented by the following formula (C2). In the formula (C1) and the formula (C2), R 1c is a hydrogen atom or an arbitrary substituent, and a plurality of R 2c are independently of each other a hydrogen atom or an arbitrary substituent, and * indicates a bonding position in the main chain of the polymer.

14. The separation functional layer according to claim 1, wherein the polymer has a crosslinked structure.

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

16. A separation membrane comprising: a separation functional layer according to any one of claims 1 to 15; and a porous support that supports the separation functional layer.

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