Separation membrane

Abstract

To provide a separation membrane with reduced change over time in the permeation rate of an acidic gas.SOLUTION: A separation membrane 10 of the present invention includes a separation functional layer 1 containing a polyimide, and a protective layer 2 that protects the separation functional layer 1. The hardness of the protective layer 2 is 10 MPa or more as measured by the following Test A. Test A: a laminate is prepared by forming a test layer, identical in composition to the protective layer 2, on a substrate; the hardness of the test layer of the laminate is measured by a nanoindentation method; and the measured hardness is taken as the hardness of the protective layer 2.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] As a method for separating an acidic gas from a mixed gas containing an acidic gas such as carbon dioxide, a membrane separation method has been developed. The membrane separation method can efficiently separate the acidic gas while suppressing the operation cost as compared with an absorption method in which the acidic gas contained in the mixed gas is absorbed by an absorbent.

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

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Conventional separation membranes have room for improvement from the viewpoint of the change over time in the separation function of acidic gases. Therefore, the present invention provides a separation membrane in which the change over time in the permeation rate of acidic gases is reduced.

Means for Solving the Problems

[0006] The present invention provides a separation functional layer containing polyimide, and a protective layer for protecting the separation functional layer, wherein the hardness of the protective layer measured by Test A is 10.0 MPa or more, and provides a separation membrane. Test A: Prepare a laminate in which a test layer having the same composition as the protective layer is formed on a substrate, measure the hardness of the test layer of the laminate by the nanoindentation method, and regard it as the hardness of the protective layer.

Advantages of the Invention

[0007] According to the present invention, a separation membrane with a reduced change over time in the permeation rate of acidic gas can be provided.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0009] The separation membrane according to the first aspect of the present invention is provided with a separation functional layer containing polyimide and a protective layer for protecting the separation functional layer, wherein the hardness of the protective layer measured by Test A is 10.0 MPa or more, separation membrane. Test A: Prepare a laminate in which a test layer having the same composition as the protective layer is formed on a substrate, measure the hardness of the test layer of the laminate by the nanoindentation method, and regard it as the hardness of the protective layer.

[0010] In the second aspect of the present invention, for example, in the separation membrane according to the first aspect, the protective layer contains a silicone resin.

[0011] In a third aspect of the present invention, for example, in the separation membrane according to the first or second aspect, the protective layer is formed from a composition containing a silicone-based polymer having an organic group.

[0012] In a fourth aspect of the present invention, for example, in the separation membrane according to the third aspect, the organic group has 2 or more carbon atoms.

[0013] In a fifth aspect of the present invention, for example, in the separation membrane according to the third or fourth aspect, the organic group contains an oxygen atom.

[0014] In a sixth aspect of the present invention, for example, in the separation membrane according to any one of the first to fifth aspects, the hardness of the protective layer is 30.0 MPa or more.

[0015] In a seventh aspect of the present invention, for example, in the separation membrane according to any one of the first to sixth aspects, the polyimide contains a structural unit A1 derived from a tetracarboxylic dianhydride having a 6-membered ring acid anhydride structure.

[0016] In an eighth aspect of the present invention, for example, in the separation membrane according to the seventh aspect, the structural unit A1 is represented by the following formula (A1).

Chemical formula

[0017] In a ninth aspect of the present invention, for example, the separation membrane according to any one of the first to eighth aspects further includes a porous support that supports the separation functional layer.

[0018] In a tenth aspect of the present invention, for example, the separation membrane according to the ninth aspect further includes an intermediate layer disposed between the separation functional layer and the porous support.

[0019] In an eleventh aspect of the present invention, for example, the separation membrane according to any one of the first to tenth aspects is used to separate carbon dioxide from a mixed gas containing carbon dioxide and nitrogen.

[0020] Hereinafter, the present invention will be described in detail, but the following description is not intended to limit the present invention to specific embodiments.

[0021] <Embodiments of the separation membrane> FIG. 1 is a cross-sectional view schematically showing a separation membrane according to an embodiment of the present invention. The separation membrane 10 of the present embodiment includes a separation functional layer 1 and a protective layer 2 that protects the separation functional layer 1. The separation functional layer 1 contains polyimide. The hardness of the protective layer 2 measured by the following Test A is 10.0 MPa or more. Test A: Prepare a laminate in which a test layer having the same composition as the protective layer 2 is formed on a substrate, measure the hardness of the test layer of the laminate by nanoindentation method, and regard it as the hardness of the protective layer 2.

[0022] (Separation functional layer) The separation functional layer 1 preferably preferentially permeates the acidic gas contained in the mixed gas. The separation functional layer 1 is typically a dense layer (non-porous layer) in which pores cannot be confirmed when observed at a magnification of 5000 times using a scanning electron microscope (SEM).

[0023] The separation functional layer 1 contains polyimide. The polyimide is typically a polyimide P containing a structural unit A1 derived from a tetracarboxylic dianhydride a1 having a six-membered ring acid anhydride structure S. The polyimide P preferably further contains a structural unit B1 derived from diamine. In some cases, the separation functional layer 1 may contain other polyimides other than the polyimide P.

[0024] The structural unit A1 derived from the tetracarboxylic dianhydride a1 is a structural unit suitable for improving the permeation coefficient and permeation rate of the acidic gas permeating through the separation functional layer 1. The tetracarboxylic dianhydride a1 has, for example, one or more, preferably two, acid anhydride structures S. The six-membered ring acid anhydride structure S is typically a glutaric anhydride structure represented by the following formula (1).

Chemical formula

[0025] Tetracarboxylic dianhydride a1 may have a condensed ring, and the condensed ring may contain an acid anhydride structure S. The condensed ring may contain an aromatic ring together with the acid anhydride structure S. The aromatic ring contained in the condensed ring may be composed of only carbon atoms, or may be a heteroaromatic ring containing heteroatoms such as oxygen atoms, nitrogen atoms, and sulfur atoms. The aromatic ring may be polycyclic or monocyclic. The number of carbon atoms in the aromatic ring is not particularly limited, and is, for example, 4 to 14. Specific examples of the aromatic ring include benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, fluorene ring, furan ring, pyrrole ring, pyridine ring, and thiophene ring.

[0026] The condensed ring may or may not have a substituent. The substituent of the condensed ring is not particularly limited, and examples thereof include a halogen group and a hydrocarbon group. Examples of the halogen group include a fluorine group, a chlorine group, a bromine group, and an iodine group. The number of carbon atoms in the hydrocarbon group is not particularly limited, and is, for example, 1 to 15. The hydrocarbon group is, for example, an alkyl group such as a methyl group, an ethyl group, or a propyl group. The hydrocarbon group may be a halogenated hydrocarbon group in which a hydrogen atom is substituted with a halogen group. When the condensed ring has a plurality of substituents, the plurality of substituents may be the same as each other or different from each other.

[0027] Tetracarboxylic dianhydride a1 is preferably represented by the following formula (a1). [Chemical formula]

[0028] In formula (a1), R 1a ~R 4a are each independently a hydrogen atom or an arbitrary substituent. The arbitrary substituent is not particularly limited, and examples thereof include a halogen group and a hydrocarbon group. Examples of the halogen group and the hydrocarbon group are as described above.

[0029] In polyimide P, the structural unit A1 derived from the tetracarboxylic dianhydride a1 is preferably represented by the following formula (A1). The structural unit A1 represented by the formula (A1) is derived from the tetracarboxylic dianhydride a1 represented by the above formula (a1). In the formula (A1), the nitrogen atom contained in the imide group is derived from the diamine that has reacted with the tetracarboxylic dianhydride a1. [Chemical formula]

[0030] In the formula (A1), R 1a ~R 4a are the same as those in the formula (a1) and are, independently of each other, a hydrogen atom or an arbitrary substituent. Specific examples of the structural unit A1 represented by the formula (A1) include the following formula (A1-1). [Chemical formula]

[0031] In polyimide P, the ratio p1 of the amount of substance of the above structural unit A1 to the total amount of substance of all the structural units A derived from the tetracarboxylic dianhydride is, for example, 50 mol% or more, and may be 70 mol% or more, 90 mol% or more, 95 mol% or more, or even 99 mol% or more. Polyimide P may contain only the above structural unit A1 as the structural unit A derived from the tetracarboxylic dianhydride. However, polyimide P may further contain, in addition to the structural unit A1, a structural unit A2 derived from a tetracarboxylic dianhydride a2 having a 5-membered ring acid anhydride structure. The tetracarboxylic dianhydride a2 is not particularly limited, and examples thereof include pyromellitic dianhydride and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride.

[0032] As described above, polyimide P further contains a structural unit B derived from diamine. The diamine is a compound having two primary amino groups. The diamine may or may not contain other functional groups other than the primary amino group. Examples of other substituents include a carboxyl group, a hydroxyl group, a thiol group, a sulfonyl group, and the like. The diamine may have at least one functional group f selected from the group consisting of a carboxyl group, a hydroxyl group, and a thiol group.

[0033] The diamine may further have an aromatic ring. Examples of the aromatic ring include those described above for the tetracarboxylic dianhydride a1. In the diamine, the substituent of the aromatic ring contains, for example, a primary amino group. The aromatic ring may or may not have other substituents other than the substituent containing the primary amino group. Other substituents are not particularly limited, and examples include groups containing the above functional group f, halogen groups, hydrocarbon groups, and the like. Examples of the halogen group and the hydrocarbon group include those described above for the tetracarboxylic dianhydride a1. Note that in the diamine, other substituents may contain a photopolymerizable functional group (for example, a vinyl group).

[0034] The diamine is represented by, for example, the following formula (b1), formula (b2), formula (b3), formula (b4), or formula (b5). [Chemical formula]

[0035] In formulas (b1) to (b5), R 1b ~R 30b are each independently a hydrogen atom or an arbitrary substituent. The arbitrary substituent is, for example, a group containing the functional group f, a halogen group, a hydrocarbon group, and the like. Examples of the halogen group and the hydrocarbon group include those described above for the tetracarboxylic dianhydride a1.

[0036] In formulas (b3) and (b4), X 1 and X 2is a single bond or any linking group. Any linking group is, for example, a divalent hydrocarbon group. Examples of the divalent hydrocarbon group include alkylene groups such as a methylene group, an ethylene group, a propane-1,3-diyl group, and a propane-2,2-diyl group. The divalent hydrocarbon group may be a halogenated hydrocarbon group in which a hydrogen atom is substituted with a halogen group. The divalent hydrocarbon group may further have an aromatic ring. Examples of the aromatic ring include those described above for the tetracarboxylic dianhydride a1. The divalent hydrocarbon group may be a fluorenediyl group. X 1 and X 2 may contain a functional group such as an ether group or an ester group together with or in place of the divalent hydrocarbon group.

[0037] The structural unit B derived from the diamine may have at least one functional group F selected from the group consisting of a carboxyl group, a hydroxyl group, a thiol group, and metal salts thereof. The metal contained in the metal salt as the functional group F is not particularly limited, and examples thereof include Li, Na, K, Be, Mg, Ca, Ba, Sc, Y, Ti, Zr, V, Cr, Mo, Mn, Fe, Co, Ni, Cu, Ag, Zn, B, Al, Ga, In, Pb, and the like. In the metal salt as the functional group F, the metal is present as a cation in detail. The valence of this metal cation is, for example, 1 or more, preferably 2 or more, and more preferably 3 or more.

[0038] When the structural unit B contains a metal salt as the functional group F, a plurality of polyimides P can coordinate to the metal cation contained in the metal salt via a functional group such as a carboxyl group. As a result, the plurality of polyimides P are crosslinked to each other via the metal cation. By forming such a crosslinked structure, physical aging of the polyimide P is suppressed, and thus, there is a tendency to suppress a decrease in the separation performance of the separation functional layer 1 over time. When the polyimide P contains a metal salt as the functional group F, the separation performance of the separation functional layer 1 also tends to improve. The metal salt as the functional group F can be formed, for example, by exchanging a dissociable proton with a metal cation for the functional group f contained in the polyimide P obtained from a monomer group containing a tetracarboxylic dianhydride a1 and a diamine.

[0039] The structural unit B derived from the diamine is represented by, for example, the following formula (B1), formula (B2), formula (B3), formula (B4), or formula (B5). The structural units B represented by formula (B1) to formula (B5) are each derived from the diamines represented by the above formula (b1) to formula (b5).

Chemical formula

[0040] In formula (B1), R 1b ~R 4b are each independently a hydrogen atom or an arbitrary substituent. In formula (B1), the arbitrary substituent is, for example, a group containing the above functional group F, a halogen group, a hydrocarbon group, or the like. Examples of the halogen group and the hydrocarbon group include those described above for the tetracarboxylic dianhydride a1.

[0041] Specific examples of the structural unit B represented by formula (B1) include the following formulas (B1-1) to (B1-7). In these formulas, M is an arbitrary metal cation.

Chemical formula

[0042] In formula (B2), R 5b ~R 8b are, independently of one another, a hydrogen atom or an arbitrary substituent. In formula (B2), the arbitrary substituent is, for example, a group containing a functional group F, a halogen group, a hydrocarbon group, etc. Examples of the halogen group and the hydrocarbon group include those described above for the tetracarboxylic dianhydride a1. Specific examples of the structural unit B represented by formula (B2) include the following formula (B2-1).

Chemical formula

[0043] In formula (B3), R 9b ~R 16b are, independently of one another, a hydrogen atom or an arbitrary substituent, and X 1 is a single bond or an arbitrary linking group. In formula (B3), the arbitrary substituent is, for example, a group containing a functional group F, a halogen group, a hydrocarbon group, etc. Examples of the halogen group and the hydrocarbon group include those described above for the tetracarboxylic dianhydride a1.

[0044] In X 1 of formula (B3), the arbitrary linking group is, for example, a divalent hydrocarbon group. Examples of the divalent hydrocarbon group include those described above. X 1 may contain a functional group such as an ether group or an ester group together with the divalent hydrocarbon group, or in place of the divalent hydrocarbon group.

[0045] Specific examples of the structural unit B represented by formula (B3) include the following formulas (B3-1) to (B3-15). In these formulas, M is an arbitrary metal cation.

Chemical formula

[0046] In formula (B4), R 17b ~R 24b are, independently of one another, a hydrogen atom or an arbitrary substituent, and X 2is a single bond or any linking group. In formula (B4), any substituent is, for example, a group containing a functional group F, a halogen group, a hydrocarbon group, etc. Examples of the halogen group and the hydrocarbon group are the same as those described above for the tetracarboxylic dianhydride a1.

[0047] X in formula (B4) 2 In, any linking group is, for example, a divalent hydrocarbon group. Examples of the divalent hydrocarbon group are the same as those described above. X 2 may contain a functional group such as an ether group or an ester group together with or in place of the divalent hydrocarbon group.

[0048] Specific examples of the structural unit B represented by formula (B4) include the following formulas (B4-1) to (B4-6). In these formulas, M is any metal cation.

Chemical formula

[0049] In formula (B5), R 25b ~R 30b are each independently a hydrogen atom or any substituent. In formula (B5), any substituent is, for example, a group containing a functional group F, a halogen group, a hydrocarbon group, etc. Examples of the halogen group and the hydrocarbon group are the same as those described above for the tetracarboxylic dianhydride a1. The structural unit B represented by formula (B5) is suitable for improving the rigidity of the polyimide P. According to the polyimide P having excellent rigidity, even when the pressure of the mixed gas to be separated is high, the separation membrane 10 tends to be suppressed from being plasticized.

[0050] Specific examples of the structural unit B represented by formula (B5) include the following formulas (B5-1) to (B5-2).

Chemical formula

[0051] In polyimide P, the structural unit A derived from tetracarboxylic dianhydride and the structural unit B derived from diamine are arranged alternately. In polyimide P, examples of the combination of adjacent structural units A and B include the following formula (A1-B1), formula (A1-B3), formula (A1-B5), etc. In these formulas, R 1a ~R 4a 、R 1b ~R 4b 、R 9b ~R 16b 、and R 25b ~R 30b are the same as those described above for formula (A1), formula (B1), formula (B3), and formula (B5).

Chemical formula

[0052] From the viewpoint of the mechanical strength of the separation functional layer 1, the weight average molecular weight (Mw) of polyimide P is, for example, 30,000 or more, preferably 50,000 or more, and more preferably 75,000 or more. The upper limit value of the weight average molecular weight of polyimide P is not particularly limited and is, for example, 1,000,000. The weight average molecular weight of polyimide P can be calculated, for example, by measuring the molecular weight distribution of polyimide P using gel permeation chromatography (GPC) equipped with a differential refractive index detector (RID) and using a calibration curve with standard polystyrene from the obtained chromatogram (chart).

[0053] In the present embodiment, the separation functional layer 1 may contain a crosslinked polyimide in which polyimide P is crosslinked via a covalent bond.

[0054] The content of polyimide P 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 substantially composed of only polyimide P.

[0055] The separation functional layer 1 may further contain other components in addition to the polyimide P. Examples of the other components include nanoparticles. Examples of the nanoparticles include those exemplified for the intermediate layer 4 described later. In the separation functional layer 1, the nanoparticles are dispersed, for example, in a matrix containing the polyimide P. The nanoparticles may be separated from each other within the matrix or may be partially aggregated.

[0056] 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, and further may be 2.0 μm or less. The thickness of the separation functional layer 1 may be 0.05 μm or more, and may be 0.1 μm or more.

[0057] (Protective layer) The protective layer 2 is a layer that protects the separation functional layer 1.

[0058] From the viewpoint of the acid gas permeation performance of the separation membrane 10, the protective layer 2 preferably contains a silicone resin, and more preferably contains a silicone resin as the main component. "Main component" means the component contained most in the protective layer 2 by mass ratio. The protective layer 2 may contain 50% by mass or more of the silicone resin, and may contain 80% by mass or more, 90% by mass or more, 95% by mass or more, and further may contain 99% by mass or more. The protective layer 2 may be substantially composed of only the silicone resin.

[0059] The protective layer 2 is preferably formed from a composition containing a silicone-based polymer having an organic group. The protective layer 2 is formed, for example, by reacting the above composition, and the reaction is typically a curing reaction.

[0060] The carbon number of the organic group is preferably 2 or more, and may be 3 or more, 5 or more, 6 or more. The upper limit of the carbon number is not particularly limited, and may be 30 or less, 25 or less, and further may be 20 or less.

[0061] The organic group may contain an oxygen atom. Examples of the organic group containing an oxygen atom include an epoxy group, an organic group having an epoxy group, an organic group having an ester bond, and the like.

[0062] In the composition, the silicone-based polymer may have two or more kinds of organic groups.

[0063] The silicone-based polymer may be at least one selected from the group consisting of a partial condensate of a silane compound C1 represented by the following formula (2), a partial condensate of a silane compound C2 represented by the following formula (3), and a condensate of the silane compound C1 and the silane compound C2. The silicone-based polymer is preferably at least one selected from the group consisting of a partial condensate of the silane compound C1 and a partial condensate of the silane compound C2.

[0064]

Chemical formula

[0065]

Chemical formula

[0066] In formula (2), the monovalent organic group having one or more epoxy groups of X is not particularly limited. For example, γ-glycidoxypropyl group, 3,4-epoxycyclopentyl group, 3,4-epoxycyclohexyl group, (3,4-epoxycyclopentyl)methyl group, (3,4-epoxycyclohexyl)methyl group, 2-(3,4-epoxycyclopentyl)ethyl group, 2-(3,4-epoxycyclohexyl)ethyl group, 2-(3,4-epoxycyclopentyl)propyl group, 2-(3,4-epoxycyclohexyl)propyl group, 3-(3,4-epoxycyclopentyl)propyl group, 3-(3,4-epoxycyclohexyl)propyl group, etc. Groups having 5 to 20 carbon atoms can be mentioned.

[0067] Among these monovalent organic groups having one or more epoxy groups, the above monovalent organic groups containing γ-glycidoxypropyl group, 2-(3,4-epoxycyclohexyl)ethyl group, and epoxycyclohexyl group are preferred, and particularly preferred is 2-(3,4-epoxycyclohexyl)ethyl group.

[0068] In formula (2), Y 1 represents a chlorine atom, a bromine atom, an iodine atom or a linear, branched or cyclic alkoxyl group having 1 to 20 carbon atoms. These groups generate silanol groups in the process of hydrolysis and condensation reaction in the presence of an organic base and water, and cause a condensation reaction between the silanol groups or a condensation reaction between the silanol group and a silicon atom having a chlorine atom, a bromine atom, an iodine atom or the alkoxyl group, thereby forming a siloxane bond.

[0069] In formula (2), Y 1Examples of the linear, branched or cyclic alkoxyl group having 1 to 20 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, an i-butoxy group, a sec-butoxy group, a t-butoxy group, an n-pentyloxy group, an n-hexyloxy group, a cyclopentyloxy group, a cyclohexyloxy group and the like.

[0070] Y in formula (2) 1 is preferably a chlorine atom, a methoxy group or an ethoxy group.

[0071] In formula (2), R 1 Examples of the linear, branched or cyclic alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a t-butyl group, an n-pentyl group, an n-hexyl group, a cyclopentyl group, a cyclohexyl group and the like.

[0072] Further, R 1Examples of the linear, branched or cyclic substituted alkyl group having 1 to 20 carbon atoms include fluoroalkyl groups such as fluoromethyl group, trifluoromethyl group, 2-fluoroethyl group, (trifluoromethyl)methyl group, pentafluoroethyl group, 3-fluoro-n-propyl group, 2-(trifluoromethyl)ethyl group, (pentafluoroethyl)methyl group, heptafluoro-n-propyl group, 4-fluoro-n-butyl group, 3-(trifluoromethyl)-n-propyl group, 2-(pentafluoroethyl)ethyl group, (heptafluoro-n-propyl)methyl group, nonafluoro-n-butyl group, 5-fluoro-n-pentyl group, 4-(trifluoromethyl)-n-butyl group, 3-(pentafluoroethyl)-n-propyl group, 2-(heptafluoro-n-propyl)ethyl group, (nonafluoro-n-butyl)methyl group, perfluoro-n-pentyl group, 6-fluoro-n-hexyl group, 5-(trifluoromethyl)-n-pentyl group, 4-(pentafluoroethyl)-n-butyl group, 3-(heptafluoro-n-propyl)-n-propyl group, 2-(nonafluoro-n-butyl)ethyl group, (perfluoro-n-pentyl)methyl group, perfluoro-n-hexyl group, 7-(trifluoromethyl)-n-heptyl group, 6-(pentafluoroethyl)-n-hexyl group, 5-(heptafluoro-n-propyl)-n-pentyl group, 4-(nonafluoro-n-butyl)-n-butyl group, 3-(perfluoro-n-pentyl)-n-propyl group, 2-(perfluoro-n-hexyl)ethyl group, (perfluoro-n-heptyl)methyl group, perfluoro-n-octyl group, 9-(trifluoromethyl)-n-nonyl group, 8-(pentafluoroethyl)-n-octyl group, 7-(heptafluoro-n-propyl)-n-heptyl group, 6-(nonafluoro-n-butyl)-n-hexyl group, 5-(perfluoro-n-pentyl)-n-pentyl group, 4-(perfluoro-n-hexyl)-n-butyl group, 3-(perfluoro-n-heptyl)-n-propyl group, 2-(perfluoro-n-octyl)ethyl group, (perfluoro-n-nonyl)methyl group, perfluoro-n-decyl group, 4-fluorocyclopentyl group, 4-fluorocyclohexyl group;Chloromethyl group, 2-chloroethyl group, 3-chloro-n-propyl group, 4-chloro-n-butyl group, 3-chlorocyclopentyl group, 4-chlorocyclohexyl group, hydroxymethyl group, 2-hydroxyethyl group, 3-hydroxycyclopentyl group, 4-hydroxycyclohexyl group; 3-(meth)acryloxypropyl group, 3-mercaptopropyl group and the like can be mentioned.

[0073] Also, R 1 As the linear, branched or cyclic alkenyl group having 2 to 20 carbon atoms of R, for example, vinyl group, 1-methylvinyl group, 1-propenyl group, allyl group (2-propenyl group), 2-methyl-2-propenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 3-cyclopentenyl group, 3-cyclohexenyl group and the like can be mentioned.

[0074] Also, R 1 As the aryl group having 6 to 20 carbon atoms of R, for example, phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, 2,3-xylyl group, 2,4-xylyl group, 2,5-xylyl group, 2,6-xylyl group, 3,4-xylyl group, 3,5-xylyl group, 1-naphthyl group and the like can be mentioned.

[0075] Also, R 1 As the aralkyl group having 7 to 20 carbon atoms of R, for example, benzyl group, phenethyl group and the like can be mentioned.

[0076] R in formula (2) 1 is preferably a methyl group, an ethyl group or the like.

[0077] Specific examples of the silane compound C1 include, as the compound with n = 0, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and the like; As the compound with n = 1, (γ-glycidoxypropyl)(methyl)dimethoxysilane, (γ-glycidoxypropyl)(ethyl)dimethoxysilane, (γ-glycidoxypropyl)(methyl)diethoxysilane, (γ-glycidoxypropyl)(ethyl)diethoxysilane, [2-(3,4-epoxycyclohexyl)ethyl](methyl)dimethoxysilane, [2-(3,4-epoxycyclohexyl)ethyl](ethyl)dimethoxysilane, [2-(3,4-epoxycyclohexyl)ethyl](methyl)diethoxysilane, [2-(3,4-epoxycyclohexyl)ethyl](ethyl)diethoxysilane, etc.; As the compound with n = 2, (γ-glycidoxypropyl)(methoxy)dimethylsilane, (γ-glycidoxypropyl)(methoxy)diethylsilane, (γ-glycidoxypropyl)(ethoxy)dimethylsilane, (γ-glycidoxypropyl)(ethoxy)diethylsilane, [2-(3,4-epoxycyclohexyl)ethyl](methoxy)dimethylsilane, [2-(3,4-epoxycyclohexyl)ethyl](methoxy)diethylsilane, [2-(3,4-epoxycyclohexyl)ethyl](ethoxy)dimethylsilane, [2-(3,4-epoxycyclohexyl)ethyl](ethoxy)diethylsilane, etc. Each can be listed respectively.

[0078] In formula (3), Y 2 represents a chlorine atom, a bromine atom, an iodine atom or a linear, branched or cyclic alkoxyl group having 1 to 20 carbon atoms. These groups generate silanol groups in the process of hydrolysis and condensation reaction in the presence of an organic base and water, and a condensation reaction occurs between the silanol groups or a condensation reaction occurs between the silanol group and a silicon atom having a chlorine atom, a bromine atom, an iodine atom or the alkoxyl group, thereby forming a siloxane bond.

[0079] In formula (3), Y 2 Examples of the linear, branched or cyclic alkoxyl group having 1 to 20 carbon atoms of Y 1Groups similar to those exemplified for the corresponding groups can be cited.

[0080] Y in formula (3) 2 is preferably a chlorine atom, a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, a sec-butoxy group, a t-butoxy group, etc.

[0081] In formula (3), R 2 Examples of the linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, the linear, branched or cyclic substituted alkyl group having 1 to 20 carbon atoms, the linear, branched or cyclic alkenyl group having 2 to 20 carbon atoms, the aryl group having 6 to 20 carbon atoms and the aralkyl group having 7 to 20 carbon atoms include, for example, the groups similar to those exemplified for the corresponding groups of R in formula (2). 1 Groups similar to those exemplified for the corresponding groups can be cited.

[0082] R in formula (3) 2 is preferably a fluorine atom, a methyl group, an ethyl group, a 2-(trifluoromethyl)ethyl group, a 2-(perfluoro-n-hexyl)ethyl group, a 2-(perfluoro-n-octyl)ethyl group, a hydroxymethyl group, a 2-hydroxyethyl group, a 3-(meth)acryloxypropyl group, a 3-mercaptopropyl group, a vinyl group, an allyl group, a phenyl group, etc.

[0083] Specific examples of the silane compound C2 include As the compound with m = 0, tetrachlorosilane, tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetra-i-propoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, etc.; As the compound with m = 1, trichlorosilane, trimethoxysilane, triethoxysilane, tri - n - propoxysilane, tri - i - propoxysilane, tri - n - butoxysilane, tri - sec - butoxysilane, fluorotrichlorosilane, fluorotrimethoxysilane, fluorotriethoxysilane, fluorotri - n - propoxysilane, fluorotri - i - propoxysilane, fluorotri - n - butoxysilane, fluorotri - sec - butoxysilane, methyltrichlorosilane, methyltrimethoxysilane, methyltriethoxysilane, methyltri - n - propoxysilane, methyltri - i - propoxysilane, methyltri - n - butoxysilane, methyltri - sec - butoxysilane, 2 - (trifluoromethyl)ethyltrichlorosilane, 2 - (trifluoromethyl)ethyltrimethoxysilane, 2 - (trifluoromethyl)ethyltriethoxysilane, 2 - (trifluoromethyl)ethyltri - n - propoxysilane, 2 - (trifluoromethyl)ethyltri - i - propoxysilane, 2 - (trifluoromethyl)ethyltri - n - butoxysilane, 2 - (trifluoromethyl)ethyltri - sec - butoxysilane, 2 - (perfluoro - n - hexyl)ethyltrichlorosilane, 2 - (perfluoro - n - hexyl)ethyltrimethoxysilane, 2 - (perfluoro - n - hexyl)ethyltriethoxysilane, 2 - (perfluoro - n - hexyl)ethyltri - n - propoxysilane, 2 - (perfluoro - n - hexyl)ethyltri - i - propoxysilane, 2 - (perfluoro - n - hexyl)ethyltri - n - butoxysilane, 2 - (perfluoro - n - hexyl)ethyltri - sec - butoxysilane, 2 - (perfluoro - n - octyl)ethyltrichlorosilane, 2 - (perfluoro - n - octyl)ethyltrimethoxysilane, 2 - (perfluoro - n - octyl)ethyltriethoxysilane, 2 - (perfluoro - n - octyl)ethyltri - n - propoxysilane, 2 - (perfluoro - n - octyl)ethyltri - i - propoxysilane, 2 - (perfluoro - n - octyl)ethyltri - n - butoxysilane, 2 - (perfluoro - n - octyl)ethyltri - sec - butoxysilane, hydroxymethyltrichlorosilane, hydroxymethyltrimethoxysilane,Hydroxyethyltrimethoxysilane, hydroxymethyltri-n-propoxysilane, hydroxymethyltri-i-propoxysilane, hydroxymethyltri-n-butoxysilane, hydroxymethyltri-sec-butoxysilane, 3-(meth)acryloxypropyltrichlorosilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropyltri-n-propoxysilane, 3-(meth)acryloxypropyltri-i-propoxysilane, 3-(meth)acryloxypropyltri-n-butoxysilane, 3-(meth)acryloxypropyltri-sec-butoxysilane, 3-mercaptopropyltrichlorosilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltri-n-propoxysilane, 3-mercaptopropyltri-i-propoxysilane, 3-mercaptopropyltri-n-butoxysilane, 3-mercaptopropyltri-sec-butoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri-n-propoxysilane, vinyltri-i-propoxysilane, vinyltri-n-butoxysilane, vinyltri-sec-butoxysilane, allyltrichlorosilane, allyltrimethoxysilane, allyltriethoxysilane, allyltri-n-propoxysilane, allyltri-i-propoxysilane, allyltri-n-butoxysilane, allyltri-sec-butoxysilane, phenyltrichlorosilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltri-n-propoxysilane, phenyltri-i-propoxysilane, phenyltri-n-butoxysilane, phenyltri-sec-butoxysilane, etc.: As the compound with m = 2, methyl dichlorosilane, methyl dimethoxysilane, methyl diethoxysilane, methyl di-n-propoxysilane, methyl di-i-propoxysilane, methyl di-n-butoxysilane, methyl di-sec-butoxysilane, dimethyl dichlorosilane, dimethyl dimethoxysilane, dimethyl diethoxysilane, dimethyl di-n-propoxysilane, dimethyl di-i-propoxysilane, dimethyl di-n-butoxysilane, dimethyl di-sec-butoxysilane, (methyl)[2-(perfluoro-n-octyl)ethyl]dichlorosilane, (methyl)[2-(perfluoro-n-octyl)ethyl]dimethoxysilane, (methyl)[2-(perfluoro-n-octyl)ethyl]diethoxysilane, (methyl)[2-(perfluoro-n-octyl)ethyl]di-n-propoxysilane, (methyl)[2-(perfluoro-n-octyl)ethyl]di-i-propoxysilane, (methyl)[2-(perfluoro-n-octyl)ethyl]di-n-butoxysilane, (methyl)[2-(perfluoro-n-octyl)ethyl]di-sec-butoxysilane, (methyl)(γ-glycidoxypropyl)dichlorosilane, (methyl)(γ-glycidoxypropyl)dimethoxysilane, (methyl)(γ-glycidoxypropyl)diethoxysilane, (methyl)(γ-glycidoxypropyl)di-n-propoxysilane, (methyl)(γ-glycidoxypropyl)di-i-propoxysilane, (methyl)(γ-glycidoxypropyl)di-n-butoxysilane, (methyl)(γ-glycidoxypropyl)di-sec-butoxysilane, (methyl)(3-mercaptopropyl)dichlorosilane, (methyl)(3-mercaptopropyl)dimethoxysilane, (methyl)(3-mercaptopropyl)diethoxysilane, (methyl)(3-mercaptopropyl)di-n-propoxysilane, (methyl)(3-mercaptopropyl)di-i-propoxysilane, (methyl)(3-mercaptopropyl)di-n-butoxysilane, (methyl)(3-mercaptopropyl)di-sec-butoxysilane, (methyl)(vinyl)dichlorosilane, (methyl)(vinyl)dimethoxysilane, (methyl)(vinyl)diethoxysilane, (methyl)(vinyl)di-n-propoxysilane, (methyl)(vinyl)di-i-propoxysilane,(Methyl)(vinyl)di-n-butoxysilane, (methyl)(vinyl)di-sec-butoxysilane, divinyldichlorosilane, divinyldimethoxysilane, divinyldiethoxysilane, divinyldi-n-propoxysilane, divinyldi-i-propoxysilane, divinyldi-n-butoxysilane, divinyldi-sec-butoxysilane, diphenyldichlorosilane, diphenyldimethoxysilane, diphenyldiethoxysilane, diphenyldi-n-propoxysilane, diphenyldi-i-propoxysilane, diphenyldi-n-butoxysilane, diphenyldi-sec-butoxysilane, etc.; As the compound with m = 3, chlorodimethylsilane, methoxydimethylsilane, ethoxydimethylsilane, chlorotrimethylsilane, bromotrimethylsilane, iodotrimethylsilane, methoxytrimethylsilane, ethoxytrimethylsilane, n-propoxytrimethylsilane, i-propoxytrimethylsilane, n-butoxytrimethylsilane, sec-butoxytrimethylsilane, t-butoxytrimethylsilane, (chloro)(vinyl)dimethylsilane, (methoxy)(vinyl)dimethylsilane, (ethoxy)(vinyl)dimethylsilane, (chloro)(methyl)diphenylsilane, (methoxy)(methyl)diphenylsilane, (ethoxy)(methyl)diphenylsilane, etc. can be respectively listed.

[0084] Among these silane compounds C2, tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, etc. are preferred.

[0085] The protective layer 2 may be formed from at least one selected from the group consisting of a composition containing polydimethylsiloxane (PDMS), a composition containing a silicone-based polymer containing a methyl group, a composition containing a silicone-based polymer containing a methyl group and a phenyl group, a composition containing an epoxy resin-modified silicone-based polymer, and a composition containing a polyester resin-modified silicone-based polymer. The protective layer 2 is preferably formed from at least one selected from the group consisting of a composition containing a silicone-based polymer containing a methyl group and a phenyl group, a composition containing an epoxy resin-modified silicone-based polymer, and a composition containing a polyester resin-modified silicone-based polymer. The polyester resin-modified silicone-based polymer also includes an alkyd resin-modified silicone-based polymer.

[0086] Examples of the composition containing PDMS include, by trade name, for example, DOWSIL TM SE1817CV, DOWSIL TM SE1816CV, DOWSIL TM SH850, DOWSIL TM EE9100, DOWSIL TM EE9000, DOWSIL TM 3140, DOWSIL TM 3145, DOWSIL TM 7091, DOWSIL TM SE9120, DOWSIL TM SE9152HT, DOWSIL TM SE9168, DOWSIL TM SE9185, DOWSIL TM SE9186, DOWSIL TM SE9186L, DOWSIL TM SE9187L, DOWSIL TM EA-3001, DOWSIL TM SE9188, DOWSIL TM SE9189L, DOWSIL TM SE4486, DOWSIL TM SE4485L, DOWSIL TM SE4485, DOWSIL TM SE9184, DOWSIL TMEA4900, DOWSIL TM SE4402, DOWSIL TM SE4450 (above, manufactured by Dow Corning Toray Co., Ltd.); YSR3022 (manufactured by Nisshoku Sangyo Co., Ltd.); RTV615 (manufactured by Ge Silicones); UV9300 (manufactured by Momentive); X-22-162C (manufactured by Shin-Etsu Chemical Co., Ltd.), etc. can be listed.

[0087] Examples of the composition containing a silicone polymer containing a methyl group, by trade name, include, for example, KR251 (manufactured by Shin-Etsu Chemical Co., Ltd.), DOWSIL TM SR2400 (manufactured by Dow Corning Toray Co., Ltd.), etc. can be listed.

[0088] Examples of the composition containing a silicone polymer containing a methyl group and a phenyl group, by trade name, include, for example, KR255, KR300, KR112, KR271, KR282, KR311, X-48-1030D, X-40-2667A, X-40-2756 (above, manufactured by Shin-Etsu Chemical Co., Ltd.); DOWSIL TM RSN-0804, DOWSIL TM RSN-0805, DOWSIL TM RSN-0806, DOWSIL TM RSN-0808, DOWSIL TM RSN-0840 (above, manufactured by Dow Corning Toray Co., Ltd.), etc. can be listed.

[0089] Examples of the composition containing an epoxy resin-modified silicone polymer, by trade name, include, for example, ES1023, ES1002T, ES1001N, X-41-1610 (above, manufactured by Shin-Etsu Chemical Co., Ltd.), etc. can be listed.

[0090] Examples of the composition containing a polyester resin-modified silicone polymer, by trade name, include, for example, KR5230, KR5206, KR5235, KR52340 (above, manufactured by Shin-Etsu Chemical Co., Ltd.), etc. can be listed.

[0091] The protective layer 2 is preferably a silicone resin film formed from the above-described composition. The silicone resin film is obtained by a curing reaction. The curing reaction is, for example, a condensation reaction. The silicone resin may be of one kind or two or more kinds.

[0092] The hardness of the protective layer 2 measured by the nanoindentation method is 10.0 MPa or more. Thereby, in the separation membrane of the present embodiment, the change over time in the permeation rate of the acid gas is reduced.

[0093] The hardness of the protective layer 2 can be measured by the following Test A. Test A: Prepare a laminate in which a test layer having the same composition as the protective layer 2 is formed on a substrate, measure the hardness of the test layer of the laminate by the nanoindentation method, and regard it as the hardness of the protective layer 2.

[0094] The nanoindentation method is performed according to the following procedure. Using a commercially available nanoindenter (for example, Triboindenter manufactured by Hysitron), a indenter is pressed into the surface of the test layer of the laminate under the following conditions to obtain a load-displacement curve. Measurement temperature: 25 °C Indenter: Berkovich (triangular pyramid) type diamond indenter Measurement mode: Single indentation measurement Maximum indentation depth: 300 nm Indentation speed: 200 nm / s

[0095] Next, the maximum load Pmax (the load acting on the indenter at the maximum displacement) is specified from the obtained load-displacement curve. Based on this maximum load Pmax and the contact projected area Ap (the area where the indenter and the test layer are in contact at the maximum displacement), the hardness (Pmax / Ap) at the position where the indenter is pressed is calculated. The above measurement is repeated at any plurality of points (at least three points) on the surface of the test layer, and the average value of the obtained values can be regarded as the hardness of the protective layer 2.

[0096] The thickness of the test layer may be any thickness that is not affected by the substrate in the nanoindentation method. The thickness of the test layer may be 1 μm or more, or may be 1 μm.

[0097] The substrate is not particularly limited and may be a polyimide release liner.

[0098] The thickness of the substrate may be 10 μm or more and 100 μm or less.

[0099] The laminate may be the separation film 10.

[0100] The hardness of the protective layer 2 may be 20.0 MPa or more, may be 30.0 MPa or more, 33.0 MPa or more, or even 40.0 MPa or more. The upper limit value of the hardness of the protective layer 2 is not particularly limited, for example, it is 200 MPa.

[0101] The thickness of the protective layer 2 is not particularly limited. For example, it is 10 μm or less, preferably 5 μm or less, more preferably 1 μm or less, still more preferably 0.5 μm or less, and particularly preferably 0.3 μm or less. The thickness of the protective layer 2 is, for example, 0.001 μm or more, preferably 0.01 μm or more, more preferably 0.1 μm or more, and still more preferably 0.15 μm or more.

[0102] The thickness of the protective layer 2 can be measured by observing the cross-section of the separation film 10 with SEM. For example, it can be obtained by measuring the thickness of the protective layer 2 at a plurality of arbitrary locations (for example, 5 or more points) on the cross-section of the separation film 10 and calculating their average value. When it is difficult to directly measure the thickness of the protective layer, such as when the separation functional layer and the protective layer cannot be distinguished by SEM, the average value of the total thickness of the separation functional layer and the protective layer can be calculated, and the value obtained by subtracting the thickness of the separation functional layer from the average value can be regarded as the thickness of the protective layer.

[0103] The protective layer 2 may further contain a filler. The protective layer 2 containing a filler can improve the effect of reducing the change over time in the permeation rate of acidic gas through the separation membrane 10 of the present embodiment. The filler may contain an inorganic material or an organic material.

[0104] (Porous support) As shown in FIG. 2, the separation membrane of the present embodiment preferably further includes a porous support 3. The porous support 3 supports the separation functional layer 1. In the separation membrane 20 shown in FIG. 2, the porous support 3 supports the separation functional layer 1 via an intermediate layer 4.

[0105] Examples of the porous support 3 include non-woven fabric; porous polytetrafluoroethylene; aromatic polyamide fiber; porous metal; sintered metal; porous ceramic; porous polyester; porous nylon; activated carbon fiber; latex; silicone; silicone rubber; a 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; a metal foam having continuous or closed cells; a polymer foam having continuous or closed cells; silica; porous glass; a mesh screen, etc. The porous support 3 may be a combination of two or more of these. Typically, the porous support 3 is a non-woven fabric.

[0106] The porous support 3 has an average pore diameter of, for example, 0.01 μm to 0.4 μm. The thickness of the porous support 3 is not particularly limited, and is, for example, 10 μm or more, preferably 20 μm or more, 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, more preferably 150 μm or less.

[0107] (Intermediate layer) As shown in FIG. 2, the separation membrane of the present embodiment preferably further includes an intermediate layer 4. The intermediate layer 4 is disposed between the separation functional layer 1 and the porous support 3 and is in direct contact with each of the separation functional layer 1 and the porous support 3.

[0108] The intermediate layer 4 contains, for example, a resin. The intermediate layer 4 is typically formed from an adhesive composition, particularly an adhesive composition containing a silicone-based polymer. In this specification, an adhesive composition containing a silicone-based polymer may be referred to as a "silicone-based adhesive". In some cases, the intermediate layer 4 may not be formed from an adhesive composition.

[0109] Examples of the silicone-based adhesive include a peroxide-crosslinked silicone-based adhesive, an addition-reaction-type silicone-based adhesive, and an active energy ray-curable silicone-based adhesive. The peroxide-crosslinked silicone-based adhesive contains an organic peroxide (e.g., benzoyl peroxide). Radical crosslinking occurs due to this organic peroxide. Examples of the addition-reaction-type silicone-based adhesive include a hydrosilylation-type silicone-based adhesive. The hydrosilylation-type silicone-based adhesive contains a SiH group-containing siloxane crosslinking agent and a platinum-based catalyst. Crosslinking occurs by a hydrosilylation reaction using this platinum-based catalyst. In the active energy ray-curable silicone-based adhesive, the crosslinking reaction proceeds by light such as ultraviolet rays or electron beams. In particular, the addition-reaction-type silicone-based adhesive, for example, the hydrosilylation-type silicone-based adhesive, is preferable in terms of being less likely to leave residues in the intermediate layer 4, enabling reaction at low temperatures, and the reaction rate.

[0110] The silicone-based adhesive preferably contains a silicone resin component and a silicone gum component as the silicone-based polymer because it is easy to control adhesiveness, peelability, and cohesiveness.

[0111] The silicone resin component is not particularly limited, but is preferably a branched polyorganosiloxane containing a hydroxyl group bonded to a silicon atom in the molecule, and is an M unit (R3SiO 1 / 2) units of Q (SiO2), units of T (RSiO 3 / 2 ) and at least one unit selected from the group consisting of units of D (R2SiO) is more preferably a polyorganosiloxane. In the above units, R is, independently of one another, a monovalent hydrocarbon group or a hydroxyl group. Examples of the monovalent hydrocarbon group include an alkyl group (e.g., methyl group, ethyl group, propyl group, etc.), an alkenyl group (e.g., vinyl group, etc.), and an aryl group (e.g., phenyl group, etc.). In particular, the silicone resin component is preferably an MQ resin composed of units of M (R3SiO 1 / 2 ). The silicone resin component may be used alone or in combination of two or more.

[0112] The silicone gum component is not particularly limited, but is preferably a linear polyorganosiloxane represented by the following formula (4).

Chemical formula

[0113] In formula (4), R is, independently of one another, a methyl group, a phenyl group or an alkenyl group. n is from 100 to 10,000. The silicone gum component may be used alone or in combination of two or more.

[0114] In the peroxide-crosslinkable silicone-based pressure-sensitive adhesive, the above silicone gum component preferably contains a methyl group. In the peroxide-crosslinkable silicone-based pressure-sensitive adhesive, the methyl group of the silicone gum component is radically crosslinked. In the hydrosilylation-type silicone-based pressure-sensitive adhesive, the above silicone gum component preferably contains an alkenyl group, particularly a vinyl group. In the hydrosilylation-type silicone-based pressure-sensitive adhesive, the alkenyl group of the silicone gum component is crosslinked by a hydrosilylation reaction.

[0115] The pressure-sensitive adhesive composition (silicone-based pressure-sensitive adhesive) may contain additives other than the silicone resin component and the silicone gum component. Examples of the additives include materials for promoting the crosslinking reaction (organic peroxides, SiH group-containing siloxane crosslinking agents, platinum-based catalysts, etc.), adhesion improvers (e.g., X-92-185 manufactured by Shin-Etsu Chemical Co., Ltd.), silane coupling agents, fillers, plasticizers, antioxidants, antistatic agents, colorants (pigments, dyes), fillers described later, and the like. The additives may be used alone or in combination of two or more kinds.

[0116] The pressure-sensitive adhesive composition (silicone-based pressure-sensitive adhesive) may further contain an organic solvent (e.g., toluene, xylene, etc.).

[0117] Specific examples of the pressure-sensitive adhesive composition (silicone-based pressure-sensitive adhesive) include "KR-3700", "KR-3701", "KR-3704", etc. manufactured by Shin-Etsu Chemical Co., Ltd. These commercially available products are provided as products in a form containing both a silicone gum component and a silicone resin component. The silicone-based pressure-sensitive adhesive may contain a mixture of these commercially available products.

[0118] The intermediate layer 4 formed from the silicone-based pressure-sensitive adhesive contains, for example, a crosslinked product of a silicone-based polymer. The content of the crosslinked product of the silicone-based polymer in the intermediate layer 4 is not particularly limited, and is, for example, 60 wt% or more, preferably 70 wt% or more, and more preferably 90 wt% or more. The intermediate layer 4 may be substantially composed of a crosslinked product of a silicone-based polymer.

[0119] The intermediate layer 4 may further contain the above-mentioned additives, particularly fillers. The intermediate layer 4 containing fillers is suitable for improving the permeation rate of acidic gas in the separation membrane 10. The filler may contain an inorganic material or an organic material. Examples of the inorganic material contained in the filler include zeolite, silica, titania, alumina, etc. Examples of the organic material include (meth)acrylic polymers, etc. In this specification, "(meth)acrylic polymer" means an acrylic polymer and / or a methacrylic polymer.

[0120] The filler may contain a Metal-Organic-Framework (MOF). The Metal-Organic-Framework is also called a Porous Coordination Polymer (PCP). The Metal-Organic-Framework contains, for example, metal ions and organic ligands. Examples of the metal ions include Cu ions, Zn ions, etc. The organic ligand contains, for example, an aromatic ring. Examples of the aromatic ring contained in the organic ligand include a benzene ring, an imidazole ring, etc. Examples of the organic ligand include trimesic acid, 2-methylimidazole, etc. Specific examples of the Metal-Organic-Framework include HKUST-1, ZIF-8, etc.

[0121] The shape of the filler is typically particulate. In this specification, particulate includes spherical, ellipsoidal, scaly, fibrous, etc.

[0122] The average particle diameter of the filler is not particularly limited, and for example, it may be 5 μm or less, 1 μm or less, 800 nm or less, 600 nm or less, 500 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, and even 100 nm or less. The lower limit value of the average particle diameter of the filler is, for example, 1 nm. The average particle diameter of the filler can be specified by the following method. First, the cross section of the intermediate layer 4 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 regarded as the particle diameter (diameter of the particle) of the specific filler. The particle diameters of an arbitrary number (at least 50) of fillers are calculated respectively, and the average value of the calculated values is regarded as the average particle diameter of the filler.

[0123] From the viewpoint of suppressing an increase in the storage modulus of the intermediate layer 4, the filler content in the intermediate layer 4 is, for example, 40 wt% or less, and may be 30 wt% or less, 20 wt% or less, and even 10 wt% or less. The lower limit value of the filler content in the intermediate layer 4 is not particularly limited, but from the viewpoint of improving the permeation rate of the acidic gas, it is, for example, 1 wt%.

[0124] The thickness of the intermediate layer 4 is not particularly limited, and for example, it is less than 50 μm, preferably 40 μm or less, more preferably 30 μm or less, still more preferably 10 μm or less, and particularly preferably 5 μm or less. The lower limit value of the thickness of the intermediate layer 4 is not particularly limited, and for example, it may be 0.1 μm or 1.0 μm.

[0125] (Shape of the separation membrane) In the present embodiment, the separation membranes 10 and 20 are typically flat membranes. However, the separation membranes 10 and 20 may have a shape other than a flat membrane, and for example, they may be hollow fiber membranes. As an example, the separation membrane as a hollow fiber membrane includes the separation functional layer 1, the protective layer 2, and the porous support 3, while it may not include the intermediate layer 4.

[0126] (Method for manufacturing the separation membrane) In this embodiment, the method for manufacturing the separation membrane 10 includes, for example, a step I of forming the separation functional layer 1 by applying a coating liquid L1 (dispersion or solution) containing the material of the separation functional layer 1 onto a substrate and drying it, and a step II of forming the protective layer 2 by applying a coating liquid L2 (dispersion or solution) containing the material of the protective layer 2 onto the separation functional layer 1 and drying it.

[0127] [Step I] In step I, in a preferred form, the coating liquid L1 contains polyimide P as the material of the separation functional layer 1.

[0128] The polyimide P can be produced, for example, by the following method. First, a diamine is dissolved in a solvent to obtain a solution. Examples of the solvent include polar organic solvents such as N-methyl-2-pyrrolidone and 1,3-dioxolane.

[0129] Next, a group of tetracarboxylic dianhydrides containing the above tetracarboxylic dianhydride a1 is gradually added to the obtained solution. Thereby, a monomer group containing tetracarboxylic dianhydride a1 and diamine reacts to form a polyamic acid. The addition of the group of tetracarboxylic dianhydrides is carried out, for example, under a heating environment of 140 °C or higher for 3 to 20 hours under stirring conditions.

[0130] Next, polyimide P can be obtained by imidizing the polyamic acid. Examples of the imidization method include a chemical imidization method and a thermal imidization method. The chemical imidization method is a method of imidizing polyamic acid using a dehydration condensing agent, for example, under room temperature conditions. Examples of the dehydration condensing agent include acetic anhydride, pyridine, and triethylamine. The thermal imidization method is a method of imidizing polyamic acid by heat treatment. The temperature of the heat treatment is, for example, 180 °C or higher.

[0131] The content of polyimide P in the coating liquid L1 can be appropriately adjusted according to the solubility of polyimide P, and is, for example, 1 wt% to 30 wt%.

[0132] The coating solution L1 may further contain organic solvents with high polarity such as N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), and 1,3-dioxolane. Such organic solvents are suitable for dissolving the material of the separation functional layer 1, particularly the polyimide P.

[0133] The coating solution L1 may further contain a surfactant (leveling agent) for improving the coatability of the coating solution L1. However, according to the studies by the present inventors, when the coating solution L1 contains a surfactant, the separation performance of the produced separation membrane 10 tends to decrease. Therefore, it is preferable that the coating solution L1 does not contain a surfactant.

[0134] The coating solution L1 may further contain a compound containing a metal cation. According to this compound, in the coating solution L1, the dissociable proton of the functional group f contained in the polyimide P can be exchanged with the metal cation, thereby forming a polyimide P having a metal salt as the above functional group F. Examples of the metal cation include those described above as the metal contained in the metal salt as the above functional group F. Specific examples of the compound containing a metal cation are Al(acac)3, Fe(acac)2, Ga(acac)3, Mg(acac)2, and the like.

[0135] The coating solution L1 may further contain a cross-linking agent. Examples of the cross-linking agent include epoxy-based cross-linking agents, amine-based cross-linking agents, isocyanate-based cross-linking agents, and the like.

[0136] In Project I, the substrate is typically a release liner. Examples of the substrate include a film containing a resin; paper; a sheet containing a metal material such as aluminum or stainless steel. The sheet containing a metal material tends to have high heat resistance. The substrate is preferably a film containing a resin in terms of excellent surface smoothness. In the substrate, examples of the polymer contained in the resin include polyolefins such as polyethylene, polypropylene, polybutene, polybutadiene, and polymethylpentene; polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyvinyl chloride and vinyl chloride copolymers; polyurethane; ethylene-vinyl acetate copolymer; polyimide, etc., and polyimide is preferred.

[0137] The surface of the substrate may be subjected to a release treatment. The release treatment can be performed by applying a release treatment agent to the surface of the substrate. Examples of the release treatment agent include silicone-based release treatment agents, long-chain alkyl-based release treatment agents, fluorine release treatment agents, molybdenum sulfide-based release treatment agents, etc. The release treatment agent may be used alone or in combination of two or more. The substrate is preferably a polyimide film subjected to a release treatment.

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

[0139] Note that before applying the coating liquid L1, a surface modification treatment may be performed on the substrate. When the substrate is subjected to a release treatment, the surface modification treatment may be performed on the surface of the substrate subjected to the release treatment. Examples of the surface modification treatment include corona treatment, plasma treatment, excimer treatment, flame treatment, etc., and corona treatment is preferred.

[0140] The surface modification treatment can be performed by irradiating the surface of the substrate with active energy rays. Specific examples of the active energy rays are electron beams, ion beams, plasma beams, ultraviolet rays, etc. When performing corona treatment as the surface modification treatment, the discharge amount is, for example, 0.1 kW·min / m2 The above is the case. The upper limit value of the discharge amount is not particularly limited, for example, 10 kW·min / m 2 is the case.

[0141] The method of applying the coating liquid L1 to the substrate is not particularly limited. For example, a spin coating method, a dip coating method, a slot die coating method, etc. can be used. The coating liquid L1 may be applied to the substrate using an applicator, a wire bar, or the like. The coating liquid L1 may be applied on the surface of a substrate that has been subjected to a peeling treatment or a surface modification treatment.

[0142] By applying the coating liquid L1 to the substrate, a coating film is formed. The thickness of the coating film can be appropriately adjusted according to the thickness of the target separation functional layer 1, for example, it is 1 μm to 100 μm.

[0143] In step I, the separation functional layer 1 can be obtained by drying the coating film. The drying conditions of the coating film are not particularly limited. For example, the drying temperature is 50°C to 200°C, and the drying time is 1 minute to 10 hours. The drying of the coating film can be performed using, for example, a heater. As an example, the coating film may be dried by passing it through a heating section equipped with a heater. The drying of the coating film may also be performed by passing it through a plurality of heating sections. The set temperatures of the plurality of heating sections may be the same as each other or different from each other.

[0144] Step I is not limited to the above method. For example, a coating liquid L1 containing polyamic acid, which is a precursor of polyimide P, may be applied onto a substrate, and the polyamic acid may be imidized to form polyimide P, thereby producing the separation functional layer 1.

[0145] The manufacturing method of this embodiment may further include performing a heat treatment (annealing treatment) on the obtained separation functional layer 1. According to this step, the separation performance of the separation functional layer 1 is improved, and there is also a tendency to suppress the decrease in the separation performance of the separation functional layer 1 over time. According to this step, by sufficiently volatilizing the solvent, it is also possible to obtain a separation functional layer 1 that contains almost no residual solvent. The annealing treatment may be performed before the formation of the protective layer 2, that is, before step II described below, or after step II.

[0146] The temperature of the heat treatment may be, for example, 130 °C or higher, 150 °C or higher, 200 °C or higher, or even 250 °C or higher. The upper limit of the temperature of the heat treatment is not particularly limited, and may be, for example, 350 °C or lower, or 300 °C or lower. The time of the heat treatment may be, for example, 1 minute or longer, 10 minutes or longer, or 30 minutes or longer. The upper limit of the time of the heat treatment is not particularly limited, and may be, for example, 24 hours or shorter.

[0147] [Step II] In step II, in a preferred form, the coating liquid L2 includes a composition containing a silicone-based polymer having an organic group. As the composition, the composition described above for the separation membrane of this embodiment can be used. The coating liquid L2 may include a silicone-based polymer and a solvent. The coating liquid L2 may further include components other than the silicone-based polymer and the solvent, and may include, for example, a curing agent. As the silicone-based polymer, those described above for the separation membrane of this embodiment can be used. The solvent is, for example, toluene.

[0148] The content of the silicone-based polymer in the coating liquid L2 can be appropriately adjusted according to the thickness of the protective layer 2, and may be, for example, 0.1 wt% to 50 wt%, 1 wt% to 40 wt%, 2 wt% to 30 wt%, 3 wt% to 30 wt%, or 5 wt% to 30 wt%.

[0149] The method of applying the coating liquid L2 onto the separation functional layer 1 is not particularly limited, and for example, a spin coating method, a dip coating method, a slot die coating method, a bar coating method, etc. can be used.

[0150] In Step II, preferably, the coating film obtained by applying the coating liquid L2 is cured by drying. The drying conditions (curing conditions) are not particularly limited and can be appropriately set according to the composition of the coating liquid L2. The curing temperature may be, for example, 100°C to 180°C, or may be 130°C to 150°C. The curing time may be, for example, 3 minutes to 10 hours, or may be 5 minutes to 3 hours. Thus, the protective layer 2 is obtained.

[0151] The manufacturing method of this embodiment preferably further includes removing the base material from the laminate composed of the protective layer 2, the separation functional layer 1, and the base material. By removing the base material, the separation membrane 10 composed of the separation functional layer 1 and the protective layer 2 can be obtained. Here, the annealing treatment described above in Step I may be performed before the formation of the protective layer 2, may be performed after the formation of the protective layer 2 and before removing the base material from the laminate, or may be performed after removing the base material.

[0152] When the separation membrane includes the porous support 3, by using the porous support 3 as the above-mentioned base material, forming the separation functional layer 1 on the porous support 3, and further forming the protective layer 2, a separation membrane including the porous support can be manufactured.

[0153] When the separation membrane includes a porous support 3 and an intermediate layer 4 as shown in Fig. 2, for example, it can be produced by the following method. First, a laminate of the porous support 3 and the intermediate layer 4 is prepared. This laminate can be produced, for example, by the following method. First, a coating solution containing the material of the intermediate layer 4 is prepared. Next, the coating solution containing the material of the intermediate layer 4 is applied onto the porous support 3 to form a coating film. The coating method of the coating solution is not particularly limited, and for example, a spin coating method, a dip coating method, etc. can be used. The coating solution may be applied using a wire bar or the like. Next, the coating film is dried to form the intermediate layer 4. The drying of the coating film can be performed, for example, 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 longer, and may be 5 minutes or longer. Further, an easy adhesion treatment may be performed on the surface of the intermediate layer 4 as needed. Examples of the easy adhesion treatment include surface treatments such as application of a primer, corona discharge treatment, and plasma treatment.

[0154] Next, a separation functional layer 1 is formed on the intermediate layer 4 in the laminate of the porous support 3 and the intermediate layer 4, and a protective layer 2 is further formed. Thereby, the separation membrane 20 can be obtained. As an example, the separation membrane 20 can be produced by performing the above-described Step I and Step II using a laminate of the porous support 3 and the intermediate layer 4 as a substrate.

[0155] Note that the method for manufacturing the separation membrane 20 is not limited to the above method. For example, the separation membrane 20 may be manufactured by the following method. First, prepare a separation membrane 10 having a separation functional layer 1 and a protective layer 2 formed on a base material such as a release liner by the above method. Next, an intermediate layer 4 is formed by applying a coating liquid containing the material of the intermediate layer 4 on the separation functional layer 1 and drying it. The laminate of the intermediate layer 4, the separation functional layer 1, and the protective layer 2 is transferred onto the porous support 3. Thereby, the separation membrane 20 is obtained. Alternatively, first, prepare a separation functional layer 1 formed on a base material such as a release liner by the above-described step I. Next, an intermediate layer 4 is formed by applying a coating liquid containing the material of the intermediate layer 4 on the separation functional layer 1 and drying it. The laminate of the intermediate layer 4 and the separation functional layer 1 is transferred onto the porous support 3. Thereafter, the protective layer 2 is formed on the separation functional layer 1 by the above-described step II. Also thereby, the separation membrane 20 is obtained.

[0156] (Properties of the separation membrane) Hereinafter, matters to be described about the separation membrane 10 are also applicable to the separation membrane 20 unless otherwise specified.

[0157] The separation membrane 10 can preferentially permeate the acid gas contained in the mixed gas. As an example, when using the separation membrane 10 in its initial state and supplying a mixed gas composed of carbon dioxide and nitrogen to the space adjacent to one surface of the separation membrane 10, the permeation rate T1 of carbon dioxide permeating through the separation membrane 10 is, for example, 10 GPU or more, and may be 20 GPU or more, 30 GPU or more, and even 40 GPU or more. The upper limit value of the permeation rate T1 is not particularly limited, and is, for example, 300 GPU. Note that GPU is 10 -6 ·cm 3 (STP) / (sec·cm 2 ·cmHg), which means (STP) per second per square centimeter of the membrane surface under a pressure difference of 1 cmHg. cm 3 (STP) means the volume of carbon dioxide at 1 atmosphere and 0°C.

[0158] The permeation rate T1 can be determined by the following method. First, a mixed gas composed of carbon dioxide and nitrogen is supplied to the space adjacent to one surface of the separation membrane 10, and the space adjacent to the other surface of the separation membrane 10 is depressurized. Thereby, a permeated fluid that has permeated through the separation membrane 10 is obtained. Measure the weight of the permeated fluid and the volume ratios of carbon dioxide and nitrogen in the permeated fluid. The permeation rate T1 can be calculated from the measurement results. In the above operation, the concentration of carbon dioxide in the mixed gas is 50 vol% under standard conditions (0 °C, 101 kPa). The mixed gas supplied to the space adjacent to one surface of the separation membrane 10 has a temperature of 30 °C and a pressure of 0.1 MPa. The space adjacent to the other surface of the separation membrane 10 is depressurized so that the pressure in the space is 0.1 MPa lower than the atmospheric pressure in the measurement environment.

[0159] Under the measurement conditions of the permeation rate T1 described above, the separation factor α1 of carbon dioxide with respect to nitrogen of the separation membrane 10 is, for example, 15 or more, and may be 20 or more, and further 25 or more. The upper limit value of the separation factor α1 is not particularly limited, and may be, for example, 100 or 60. The separation factor α1 can be calculated from the following formula. However, in the following formula, X A and X B are the volume ratios of carbon dioxide and nitrogen in the mixed gas, respectively. Y A and Y B are the volume ratios of carbon dioxide and nitrogen in the permeated fluid that has permeated through the separation membrane 10, respectively. Separation factor α1 = (Y A / Y B ) / (X A / X B )

[0160] Since the separation membrane 10 of the present embodiment includes the protective layer 2 having a predetermined hardness, the molecular motion of the polyimide in the separation functional layer 1 is suppressed, and the relaxation of the unrelaxed volume is suppressed. That is, the decrease in the free volume of the polyimide is suppressed. Therefore, in the separation membrane 10 of the present embodiment, the decrease in the permeation rate of the acid gas when stored for a long time is suppressed, and the change over time in the permeation rate of the acid gas is reduced.

[0161] The degradation of the separation performance of the separation membrane 10 due to long-term use can be evaluated by the following storage test. First, the separation membrane 10 is stored at 25°C. The storage time is, for example, 2000 hours. For the separation membrane 10 after storage, the permeation rate TN of carbon dioxide is measured by the same method as the permeation rate T1. Based on the ratio TN / T1 (maintenance rate of the permeation rate) of the permeation rate TN to the permeation rate T1, the degradation of the separation performance can be evaluated.

[0162] In the separation membrane 10, the maintenance rate TN / T1 of the permeation rate when stored for 2000 hours is, for example, 60% or more, and may be 65% or more, 70% or more, or even 74% or more. The upper limit value of the maintenance rate TN / T1 of the permeation rate when stored for 2000 hours is, for example, 110%.

[0163] The permeation rate TN after storage for 2000 hours is, for example, 10 GPU or more, and may be 20 GPU or more, or even 20 GPU or more. The upper limit value of the permeation rate TN after storage for 2000 hours is not particularly limited, and is, for example, 300 GPU.

[0164] In addition, the separation factor α of carbon dioxide with respect to nitrogen in the separation functional layer 1 after storage for 2000 hours is, for example, 15 or more, and may be 20 or more, or even 25 or more. The upper limit value of the separation factor α after storage for 2000 hours is not particularly limited, and is, for example, 100, or may be 60. The separation factor α after the storage test can be specified by the same method as α1 described above, except that the separation membrane 10 after the storage test is used.

[0165] (Use of the separation membrane) As an application of the separation membrane 10 of the present embodiment, an application for separating an acid gas from a mixed gas containing the acid gas can be mentioned. Examples of the acid gas in the mixed gas include carbon dioxide, hydrogen sulfide, carbonyl sulfide, sulfur oxides (SOx), hydrogen cyanide, nitrogen oxides (NOx), etc., and carbon dioxide is preferable. The mixed gas contains other gases in addition to the acid gas. Examples of the other gases include non-polar gases such as hydrogen, nitrogen, methane, and inert gases such as helium, and nitrogen, methane, etc. are preferable. In particular, the separation membrane 10 of the present embodiment is suitable for the application of separating carbon dioxide from a mixed gas containing carbon dioxide and nitrogen. However, the application of the separation membrane 10 is not limited to the application of separating an acid gas from the above mixed gas.

[0166] <Embodiment of the membrane separation device> As shown in FIG. 3, the membrane separation device 100 of the present embodiment includes a separation membrane 20 and a tank 30. In the membrane separation device 100, it is also possible to use the separation membrane 10 instead of the separation membrane 20. The tank 30 includes a first chamber 31 and a second chamber 32. The separation membrane 20 is disposed inside the tank 30. Inside the tank 30, the separation membrane 20 separates the first chamber 31 and the second chamber 32. The separation membrane 20 extends from one of the pair of wall surfaces of the tank 30 to the other.

[0167] The first chamber 31 has an inlet 31a and an outlet 31b. The second chamber 32 has an outlet 32a. Each of the inlet 31a, the outlet 31b, and the outlet 32a is preferably an opening formed in the wall surface of the tank 30.

[0168] The membrane separation using the membrane separation device 100 is carried out by the following method. First, a mixed gas 40 containing an acidic gas is supplied to the first chamber 31 through the inlet 31a. The concentration of the acidic gas in the mixed gas 40 is not particularly limited, and at standard conditions, for example, it is 0.01 vol% (100 ppm) or more, preferably 1 vol% or more, more preferably 10 vol% or more, still more preferably 30 vol% or more, and particularly preferably 50 vol% or more. The upper limit value of the concentration of the acidic gas in the mixed gas 40 is not particularly limited, and at standard conditions, for example, it is 90 vol%.

[0169] Due to the supply of the mixed gas 40, the pressure inside the first chamber 31 may be increased. The membrane separation device 100 may further include a pump (not shown) for increasing the pressure of the mixed gas 40. The pressure of the mixed gas 40 supplied to the first chamber 31 is, for example, 0.1 MPa or more, preferably 0.3 MPa or more.

[0170] With the mixed gas 40 supplied to the first chamber 31, the pressure inside the second chamber 32 may be reduced. The membrane separation device 100 may further include a pump (not shown) for reducing the pressure inside the second chamber 32. The second chamber 32 may be depressurized so that the space inside the second chamber 32 is, for example, 10 kPa or more, preferably 50 kPa or more, more preferably 100 kPa or more lower than the atmospheric pressure in the measurement environment.

[0171] By supplying the mixed gas 40 into the first chamber 31, a permeate fluid 45 with a higher content of acidic gas than the mixed gas 40 can be obtained on the other side of the separation membrane 20. That is, the permeate fluid 45 is supplied to the second chamber 32. The permeate fluid 45 preferably contains an acidic gas as the main component. However, the permeate fluid 45 may contain a small amount of other gases besides the acidic gas. The permeate fluid 45 is discharged to the outside of the tank 30 through the outlet 32a.

[0172] The concentration of the acid gas in the mixed gas 40 gradually decreases from the inlet 31a to the outlet 31b of the first chamber 21. The mixed gas 40 (non-permeating fluid 46) processed in the first chamber 31 is discharged to the outside of the tank 30 through the outlet 31b.

[0173] The membrane separation device 100 of the present embodiment is suitable for a flow-through (continuous) membrane separation method. However, the membrane separation device 100 of the present embodiment may also be used for a batch-type membrane separation method.

[0174] <Modification Example of Membrane Separation Device> The membrane separation device 100 may be a spiral-type membrane element, a hollow fiber membrane element, etc. FIG. 4 shows a spiral-type membrane element. The membrane separation device 110 in FIG. 4 includes a central tube 51 and a laminate 52. The laminate 52 includes the separation membrane 20. The laminate 52 may include the separation membrane 10 instead of the separation membrane 20.

[0175] The central tube 51 has a cylindrical shape. A plurality of holes are formed on the surface of the central tube 51 for allowing the permeating fluid 45 to flow into the inside of the central tube 51. Examples of the material of the central tube 51 include resins such as acrylonitrile-butadiene-styrene copolymer resin (ABS resin), polyphenylene ether resin (PPE resin), polysulfone resin (PSF resin); metals such as stainless steel and titanium. The inner diameter of the central tube 51 is, for example, in the range of 20 to 100 mm.

[0176] The laminate 52 further includes a supply-side flow path member 53 and a permeation-side flow path member 54 in addition to the separation membrane 20. The laminate 52 is wound around the central tube 51. The membrane separation device 110 may further include an exterior member (not shown).

[0177] As the supply-side flow path member 53 and the permeation-side flow path member 54, for example, a resin net made of polyphenylene sulfide (PPS) or ethylene-chlorotrifluoroethylene copolymer (ECTFE) can be used.

[0178] Membrane separation using the membrane separation device 110 is performed by the following method. First, the mixed gas 40 is supplied to one end of the wound laminate 52. The permeated fluid 35 that has permeated through the separation membrane 20 of the laminate 52 moves inside the central tube 51. The permeated fluid 45 is discharged to the outside through the central tube 51. The mixed gas 40 (non-permeated fluid 46) processed by the membrane separation device 110 is discharged to the outside from the other end of the wound laminate 52. Thereby, the acidic gas can be separated from the mixed gas 40.

Example

[0179] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

[0180] [Production of Separation Membrane] (Example 1) First, polyimide was synthesized using an automatic polymerization apparatus (manufactured by Metrohm AG, EasyMax402). A separable flask (capacity 400 mL) attached to the apparatus was equipped with a Dimroth condenser, a stirring bar, an internal thermometer, a nitrogen inlet tube, and a flat stopper. A coolant set at 10 °C was circulated through the chiller of the Dimroth condenser. N2 gas was passed through the flask at a flow rate of 100 mL / min. The stirring speed was set at 300 rpm. Next, 167.79 g of 1-methyl-2-pyrrolidone (ultra-dehydrated) as a solvent, 3.57 g (23.75 mmol) of 2,4,6-trimethyl-1,3-phenylenediamine (TrMPD), 6.52 g (23.75 mmol) of 3,7-diamino-2,8-dimethyldibenzothiophene sulfone (DDBT), and 0.72 g (2.50 mmol) of 5,5'-methylenebis(2-aminobenzoic acid) (MBAA) were added to the flask as diamines. These were stirred at room temperature to dissolve the diamines in the solvent. To the resulting solution, 13.61 g (50.75 mmol) of naphthalene-1,4,5,8-tetracarboxylic dianhydride (NTDA) and 12.21 g (100.00 mmol) of benzoic acid were further added as tetracarboxylic dianhydrides. The jacket temperature of the apparatus was raised to 180 °C and stirred for 8 hours. At this time, the internal temperature of the flask was 172 - 175 °C. After stirring, the internal temperature of the flask was cooled to 25 °C and allowed to stand overnight.

[0181] Next, 12.92 g (100.00 mmol) of isoquinoline was added, the jacket temperature was raised to 180 °C again, and stirred for 8 hours. After allowing the reaction solution to stand overnight, the reaction solution was diluted by adding 295.99 g of 1-methyl-2-pyrrolidone. Next, 1000 mL of methanol was added dropwise to the reaction solution using a dropping funnel over about 30 minutes, and reprecipitation purification was performed. The precipitated polyimide was filtered off, and the operation of washing the polyimide with 500 mL of methanol was carried out twice. After washing, the filtered polyimide was dried in a hot air circulation dryer at 60 °C for 15 hours, and further dried in a vacuum dryer at 100 °C for 8 hours. As a result, 28.28 g of polyimide was obtained.

[0182] Next, the above polyimide was added with N-methyl-2-pyrrolidone (NMP) and acetylacetone and subjected to a stirring operation to obtain Solution A. Next, Al(acac)3 and NMP were added and subjected to a stirring operation to obtain Solution B. Solution A and Solution B were mixed, and the stirring operation and the defoaming operation were repeated twice to prepare a coating solution L1 containing polyimide. The ratio of polyimide in the coating solution L1 was 4 wt%. In the coating solution L1, the ratio of the weight of Al(acac)3 to the weight of polyimide was 6 wt%. In the coating solution L1, the dissociable protons of the carboxyl groups contained in the polyimide were exchanged with aluminum cations. That is, the polyimide had an aluminum salt of the carboxyl group.

[0183] Next, the coating solution L1 was coated onto a release liner (manufactured by Fujicol Co., Ltd., SCA0) using a die, and heated and dried in an oven at 130 °C for about 5 minutes to form a coating film (thickness 1 μm). Then, it was further heated and dried in an oven at 150 °C for 30 minutes to form a separation functional layer on the release liner. The release liner is one in which a release layer formed from a release agent composition containing a silicone-based release agent is disposed on a main body portion made of polyimide. Also, the release liner was subjected to corona treatment under the above conditions and used. 2 The one subjected to corona treatment under the above conditions was used.

[0184] Next, a coating solution containing a silicone-based adhesive (manufactured by Momentive Performance Materials Inc., YSR-3022) and a crosslinking agent (benzoyl peroxide) was spin-coated (1000 rpm, 20 seconds) onto the separation functional layer prepared above. The coating of the coating solution was carried out under the condition that the coating thickness was 0.2 μm. Next, the obtained coating film was dried at 130 °C for 5 minutes. Thereby, a laminate of a release liner, a separation functional layer, and an intermediate layer was obtained.

[0185] Next, the silicone-based adhesive surface (i.e., the surface on the intermediate layer side) in the laminate was adhered to the porous support (manufactured by Nitto Denko Corporation, CF-30C). The thickness of the porous support was 130 μm. Thereafter, by peeling off the release liner, a laminate of the porous support, the intermediate layer, and the separation functional layer was obtained.

[0186] Next, a coating solution L2 containing the material for the protective layer was prepared. The coating solution L2 was a solution obtained by diluting an epoxy resin-modified silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., ES1023) as the material for the protective layer to 5 wt% with toluene. The coating solution L2 was applied onto the separation functional layer using a bar coater (wet film thickness: 1.5 μm) to form a coating film. The coating film was cured by heating at 130°C for 1 hour, and a protective layer was formed.

[0187] As described above, the separation membrane of Example 1 was produced.

[0188] (Example 2) A separation membrane of Example 2 was produced in the same manner as in Example 1, except that the material for the protective layer was changed to a methyl / phenyl silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., KR255).

[0189] (Example 3) A separation membrane of Example 3 was produced in the same manner as in Example 1, except that the material for the protective layer was changed to a polyester resin-modified silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., KR5206).

[0190] (Comparative Example 1) In the same manner as in Example 1, a separation functional layer was formed on the laminate of the porous support and the intermediate layer. The laminate composed of the porous support, the intermediate layer, and the separation functional layer was heated at 130°C for 1 hour, and this was used as the separation membrane of Comparative Example 1. That is, Comparative Example 1 was produced in the same manner as in Example 1, except that the coating solution L2 was not applied.

[0191] (Comparative Example 2) As the coating solution L2, PDMS (rubbery) (manufactured by Dow Corning Toray Co., Ltd., DOWSIL TMA toluene solution containing 30 wt% of SE1817CV) was used, and the separation membrane of Comparative Example 2 was produced in the same manner as in Example 1 except that the heating time of the coating film of the coating solution L2 was 5 minutes.

[0192] (Comparative Example 3) The material of the protective layer was changed to PDMS (rubbery) (manufactured by Dow Corning Toray Co., Ltd., DOWSIL TM SE1817CV), and the separation membrane of Comparative Example 3 was produced in the same manner as in Example 1 except that the heating time of the coating film of the coating solution L2 was 5 minutes. That is, Comparative Example 3 was produced in the same manner as Comparative Example 2 except for the concentration of the coating solution L2.

[0193] (Comparative Example 4) In the same manner as in Example 1, a separation functional layer was formed on the laminate of the porous support and the intermediate layer. The laminate composed of the porous support, the intermediate layer, and the separation functional layer was heated at 130 °C for 5 minutes, and this was used as the separation membrane of Comparative Example 4. That is, Comparative Example 4 was produced in the same manner as Comparative Example 2 except that the coating solution L2 was not applied.

[0194] [Thickness of protective layer] Next, the thicknesses of the protective layers in the separation membranes of Examples 1 to 3 and Comparative Examples 2 to 3 were measured as follows. Using a scanning electron microscope (SU3800 manufactured by Hitachi High-Technologies Corporation), SEM images of the cross-sections of the separation membranes of Examples 1 to 3 and Comparative Examples 1 to 3 were obtained. From the obtained SEM images, the total thicknesses of the separation functional layer and the protective layer at any plurality of points were measured, and the average value was calculated. Also, for the separation membrane of Comparative Example 1, the average value of the thicknesses of the separation functional layer at any plurality of points was calculated, and this was regarded as the thickness of the separation functional layer. All of Examples 1 to 4 and Comparative Examples 1 to 3 were measured at 5 or more points. The numerical values obtained by subtracting the thickness of the separation functional layer obtained from Comparative Example 1 from the respective average values of Examples 1 to 3 and Comparative Examples 2 to 3 were regarded as the thicknesses of the protective layers, respectively.

[0195] The thickness of the protective layer in the separation membrane of Example 1 was 0.21 μm.

[0196] The thickness of the protective layer in the separation membrane of Example 2 was 0.20 μm.

[0197] The thickness of the protective layer in the separation membrane of Example 3 was 0.28 μm.

[0198] The thickness of the protective layer in the separation membrane of Comparative Example 2 was 1.71 μm.

[0199] The thickness of the protective layer in the separation membrane of Comparative Example 3 was 0.34 μm.

[0200] [Hardness measurement] For Examples 1 to 3 and Comparative Examples 2 and 3, the hardness of the protective layer was measured according to the following procedure.

[0201] (Examples 1 to 3) A toluene solution containing 30 wt% of the same protective layer material as in each of Examples 1 to 3 was coated on a polyimide release liner (manufactured by Fujicor Co., Ltd., SCA0) (thickness 50 μm) with a corona-treated surface using a bar coater (wet film thickness 1.5 μm) to form a coated film. The conditions of the corona treatment were a power density of 0.1 kW / cm 2 , and a conveyance speed of 3 m / min. By heat-treating the coated film at 130°C for 1 hour, a test layer having a thickness of about 1 μm and the same composition as the protective layer in each of Examples 1 to 3 was formed. For any three points on the surface of the test layer, the hardness was measured by the above-described nanoindentation method, and the average value of the obtained values was taken as the hardness of the protective layer. A nanoindenter manufactured by Hysitron Co., Ltd., Triboindenter was used.

[0202] (Comparative Examples 2 and 3) A toluene solution containing 30 wt% of the same protective layer material as in each of Comparative Examples 2 and 3 was coated on the above-described polyimide release liner with a corona-treated surface using a bar coater (wet film thickness 1.5 μm) to form a coated film. By heat-treating the coated film at 130°C for 5 minutes, a test layer having a thickness of about 1 μm and the same composition as the protective layer in each of Comparative Examples 2 and 3 was formed. For the test layer, measurements were carried out in the same manner as in Examples 1 to 3 to determine the hardness of the protective layer.

[0203] [Characteristics Evaluation of Separation Membrane] (Gas Permeation Test) For the separation membranes of Examples 1 to 3 and Comparative Examples 1 to 4 in the initial state, the carbon dioxide permeation rate T1 and the carbon dioxide separation factor α1 (CO2 / N2) with respect to nitrogen were measured by the following method. The measurement of the permeation rate T1 and the separation factor α1 of the separation membrane in the initial state was carried out within 24 hours after the production of the separation membrane. First, the separation membrane was set in a metal cell and sealed with an O-ring so that no leakage occurred. Next, a mixed gas was injected into the metal cell so that the mixed gas contacted the main surface on the protective layer side of the separation membrane. The mixed gas consisted substantially of carbon dioxide and nitrogen. The concentration of carbon dioxide in the mixed gas was 50 vol% under standard conditions. The mixed gas injected into the metal cell had a temperature of 30 °C and a pressure of 0.1 MPa. Next, the space in the metal cell adjacent to the main surface on the porous support side of the separation membrane was evacuated with a vacuum pump. At this time, this space was evacuated so that the pressure in the space was 0.1 MPa lower than the atmospheric pressure in the measurement environment. Thereby, a permeated fluid was obtained from the main surface on the porous support side of the separation membrane. Based on the composition of the obtained permeated fluid, the weight of the permeated fluid, etc., the permeation rate T1 and the separation factor α1 were calculated. The results are shown in Table 1.

[0204] (Storage Test) For the separation membranes of Examples 1 to 3 and Comparative Examples 1 to 4, a storage test was conducted by storing them at 25 °C for a long period. For those stored for 190 hours, the carbon dioxide permeation rate T2 and the carbon dioxide separation factor α2 with respect to nitrogen were measured by the same method as the permeation rate T1 and the separation factor α1. Also, for those stored for 1300 hours, the permeation rate T3 and the separation factor α3 were measured in the same manner. Also, for those stored for 2000 hours, the permeation rate T4 and the separation factor α4 were measured in the same manner. From the obtained results, as the maintenance rate [%] of the permeation rate, the ratio T3 / T2 of the permeation rate T3 to the permeation rate T2, the ratio T3 / T1 of the permeation rate T3 to the permeation rate T1, and the ratio T4 / T1 of the permeation rate T4 to the permeation rate T1 were calculated. The results are shown in Table 1.

[0205]

Table 1

[0206] As can be seen from Table 1, the separation membranes of Examples 1 to 3 having a protective layer with a hardness of 10 MPa or more had a higher maintenance rate of the permeation rate than the separation membranes of Comparative Examples 1 and 4 without a protective layer and the separation membranes of Comparative Examples 2 and 3 with a protective layer hardness of less than 10 MPa. The separation membranes of Examples 1 to 3 had particularly higher values of the ratio T4 / T1, which is the maintenance rate after storage for 2000 hours, than Comparative Examples 1 to 4. From this result, it can be said that the separation membrane of the present embodiment has a reduced change over time in the acidic gas permeation rate.

[0207] From the comparison between Comparative Examples 2 and 3, it can be read that as the thickness of the protective layer increases, the permeation rate decreases while the maintenance rate tends to improve.

Industrial Applicability

[0208] The separation functional layer and the separation membrane of the present embodiment are suitable for separating acidic gas from a mixed gas containing acidic gas. In particular, the separation functional layer and the separation membrane of the present embodiment are suitable for separating carbon dioxide from off-gas of a chemical plant or a thermal power plant.

Explanation of Reference Numerals

[0209] 1 Separation functional layer 2 Protective layer 3 Porous support 4 Intermediate layer 10, 20 Separation membrane 100, 110 Membrane separation device

Claims

1. A separation functional layer containing polyimide, and a protective layer for protecting the separation functional layer, wherein the hardness of the protective layer measured by Test A is 10.0 MPa or more, a separation membrane. Test A: Prepare a laminate in which a test layer having the same composition as the protective layer is formed on a substrate, measure the hardness of the test layer of the laminate by nanoindentation method, and regard it as the hardness of the protective layer.

2. The separation membrane according to claim 1, wherein the protective layer contains a silicone resin.

3. The separation membrane according to claim 1, wherein the protective layer is formed from a composition containing a silicone-based polymer having an organic group.

4. The separation membrane according to claim 3, wherein the organic group has 2 or more carbon atoms.

5. The separation membrane according to claim 3, wherein the organic group contains an oxygen atom.

6. The separation membrane according to claim 1, wherein the hardness of the protective layer is 30.0 MPa or more.

7. The separation membrane according to claim 1, wherein the polyimide contains a structural unit A1 derived from a tetracarboxylic dianhydride having a 6-membered ring acid anhydride structure.

8. The separation membrane according to claim 7, wherein the structural unit A1 is represented by the following formula (A1). 【Chemical 1】

9. The separation membrane according to claim 1, further comprising a porous support supporting the separation functional layer.

10. The separation membrane according to claim 9, further comprising an intermediate layer disposed between the separation functional layer and the porous support.

11. The separation membrane according to claim 1, which is used for separating carbon dioxide from a mixed gas containing carbon dioxide and nitrogen.

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