Composite semipermeable membrane, composite semipermeable membrane element, fluid separation device, and coating agent for composite semipermeable membrane

Abstract

The present invention relates to a composite semipermeable membrane comprising a porous support layer, a separation function layer provided on the porous support layer, and a coating layer provided on the separation function layer, wherein: the separation function layer contains a crosslinked polyamide as a main component; the coating layer contains a polymer having a hydrogen bond acceptor; and the interaction energy between the polymer and the crosslinked polyamide is −700 cal / mol / atom to −400 cal / mol / atom.

Description

Composite semipermeable membrane, composite semipermeable membrane element, fluid separation device, and coating agent for composite semipermeable membrane

[0001] The present invention relates to a composite semipermeable membrane, a composite semipermeable membrane element equipped therewith, a fluid separation device, and a coating agent for a composite semipermeable membrane.

[0002] There are various techniques for removing substances (e.g., salts) dissolved in a solvent (e.g., water). In recent years, the use of membrane separation methods using semipermeable membranes such as reverse osmosis membranes has been expanding as a process for saving energy and resources.

[0003] Currently, commercially available reverse osmosis membranes and nanofiltration membranes are generally composite semipermeable membranes having a support membrane and a separation functional layer laminated on the support membrane. As the separation functional layer, cross-linked polyamides obtained by the polycondensation reaction of polyfunctional amines and polyfunctional acid halides are known.

[0004] One of the challenges in membrane separation is the fouling phenomenon. Fouling is a phenomenon in which substances contained in the water being treated are adsorbed onto the surface or pores of a semipermeable membrane, inhibiting the permeability of the solution and reducing the membrane permeation flux of the composite semipermeable membrane. Fouling phenomena are classified according to the type of adsorbed substance, including chemical fouling due to the adsorption of organic matter and biofouling due to the adsorption of microorganisms. To restore the water permeability performance reduced by fouling, the membrane is washed with chemical solutions containing acids and alkalis. However, even if the water permeability performance is restored by washing, the removal performance of the composite semipermeable membrane may decrease as a result of contact with the chemical solution.

[0005] Non-patent document 1 reports that amide bond cleavage is a factor in the degradation of composite semipermeable membranes. Patent document 1 and non-patent document 2 disclose a method of forming a protective layer on the surface of a separation functional layer as a means of preventing amide bond cleavage.

[0006] International Publication No. 2024 / 162434

[0007] Progress in Polymer Science, 2017, Vol. 72, p. 1-15 JOURNAL of Membrane Science, 2016, 501, p. 209-219

[0008] In various water treatment facilities such as water desalination plants, pretreatment such as ultrafiltration may be performed before reverse osmosis filtration or nanofiltration. If oxidizing agents used to wash the ultrafiltration membranes used in pretreatment leak and come into contact with the reverse osmosis membrane or nanofiltration membrane, these membranes may undergo oxidative degradation. In addition, since reverse osmosis membranes and nanofiltration membranes are generally washed with acid and alkali chemicals, it is important that these membranes have acid and alkali resistance.

[0009] Therefore, the present invention aims to provide a composite semipermeable film with good oxidation resistance, acid resistance, and alkali resistance.

[0010] To solve the above problems, the present invention includes the following configurations [1] to

[16] . [1] A composite semipermeable membrane comprising a porous support layer, a separation function layer provided on the porous support layer, and a coating layer provided on the separation function layer, wherein the separation function layer mainly contains a crosslinked polyamide, and the coating layer contains a polymer having hydrogen bond acceptors, and the interaction energy between the polymer and the crosslinked polyamide is -700 cal / mol / atom or more and -400 cal / mol / atom or less. [2] The composite semipermeable membrane according to [1], wherein the van der Waals interaction energy between the polymer and the crosslinked polyamide is -450 cal / mol / atom or more and -150 cal / mol / atom or less. [3] A composite semipermeable membrane according to [1] or [2], wherein the Coulomb interaction energy between the polymer and the crosslinked polyamide is -300 cal / mol / atom or more and -150 cal / mol / atom or less. [4] A composite semipermeable membrane according to any one of [1] to [3], wherein the interaction energy between the polymer and water molecules is -2000 cal / mol / atom or more and -1000 cal / mol / atom or less. [5] A composite semipermeable membrane according to any one of [1] to [4], wherein the crosslinked polyamide is a crosslinked aromatic polyamide. [6] A composite semipermeable membrane according to any one of [1] to [5], wherein the polymer consists only of non-halogen atoms. [7] A composite semipermeable membrane according to any one of [1] to [6], wherein the polymer contains monomer units having hydrogen bond acceptors with a polarization degree of 0.68 e or more and 1.00 e or less. [8] A composite semipermeable membrane according to any one of [1] to [7] above, wherein the polymer is nonionic. [9] A composite semipermeable membrane according to any one of [1] to [8] above, wherein the polymer has a structure represented by the following general formula (I).

[0011]

[0012] [In general formula (I), R in the repeating unit] １ and R ２is each independently hydrogen or a hydrocarbon group having 2 or less carbon atoms, and n is an integer of 1 or more. ]

[10] The polymer-containing composite semipermeable membrane according to any one of [1] to [9] above, having a monomer unit having a hydrocarbon group having 4 or more and 12 or less carbon atoms in the main chain.

[11] The polymer-containing composite semipermeable membrane according to any one of [1] to

[10] above, including a monomer unit having at least one structure selected from the group consisting of structures represented by the following general formulas (II) to (VI).

[0013]

[0014] [In general formulas (II) to (VI), R ３ , R ４ , R ７ , R ９ and R １０ are each independently a hydrocarbon group having 4 or more and 12 or less carbon atoms which may be substituted, and R ５ , R ６ and R ８ are each independently hydrogen, a hydrocarbon group having 2 or less carbon atoms, or a functional group having 2 or less carbon atoms. ]

[12] The composite semipermeable membrane according to any one of [1] to

[11] above, wherein the hydrogen bond acceptor is a functional group having a carbonyl group.

[13] The polymer-containing composite semipermeable membrane according to any one of [9] to

[12] above, wherein the polymer is a copolymer and includes at least one of the structures represented by the following general formulas (VII) and (VIII).

[0015]

[0016] [In general formulas (VII) and (VIII), R １１ ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​２５

[14] A composite semipermeable membrane element comprising a composite semipermeable membrane according to any one of [1] to

[13] above.

[15] A fluid separation device comprising a composite semipermeable membrane according to any one of [1] to

[13] above.

[16] A coating agent for a composite semipermeable membrane comprising a porous support layer and a separation functional layer provided on the porous support layer and mainly comprising a crosslinked polyamide, wherein the coating agent for a composite semipermeable membrane comprises a polymer having an interaction energy with the crosslinked polyamide of -700 cal / mol / atom or more and -400 cal / mol / atom or less.

[0017] According to the present invention, it is possible to provide a composite semipermeable film with good oxidation resistance, acid resistance, and alkali resistance.

[0018] Figure 1 is a cross-sectional view of a composite semipermeable membrane in one embodiment of the present invention. Figure 2 is an unfolded view of a composite semipermeable membrane element in one embodiment of the present invention. Figure 3 is a flowchart of the method for calculating the interaction energy.

[0019] Embodiments of the present invention will be described in detail below, but the present invention is not limited thereto. In this specification, for example, "mass%" and "weight%" are synonymous, and "parts by mass" and "parts by weight" are synonymous.

[0020] 1. Composite Semipermeable Membrane Figure 1 shows a cross-sectional view of the structure of a composite semipermeable membrane 1 in one embodiment of the present invention. The composite semipermeable membrane 1 according to this embodiment comprises a support membrane 2 which is a composite of a substrate and a porous support layer, a separation function layer 3, and a coating layer 4. The composite semipermeable membrane is preferably a reverse osmosis membrane or a nanofiltration membrane in which the pore size of the separation function layer is fine.

[0021] 1.1 Porous Support Layer The composite semipermeable membrane of this embodiment includes a porous support layer. The porous support layer may be formed on a substrate, and the composite of the substrate and the porous support layer is also referred to as the support membrane. The porous support layer and the substrate may each consist of one layer or two or more layers. The porous support layer and the substrate are for providing strength to the separation function layer and do not substantially possess solute separation performance themselves.

[0022] Examples of base materials include fabrics made from polyester polymers, polyamide polymers, polyolefin polymers, and mixtures or copolymers thereof. Among these, fabrics made from polyester polymers, which have high mechanical and thermal stability, are preferred. The fabric can preferably be in the form of a long-fiber nonwoven fabric, a short-fiber nonwoven fabric, or a woven or knitted fabric.

[0023] The porous support layer has numerous interconnected pores. The pore diameter and pore diameter distribution are not particularly limited. For example, a porous support layer is preferred that has a symmetrical structure with uniform pore diameters, or an asymmetrical structure in which the pore diameter gradually increases from one surface to the other, with the pore diameter on the surface with smaller pores being 0.1 to 100 nm.

[0024] As the material for the porous support layer, homopolymers (homopolymers) or copolymers of polysulfone (hereinafter referred to as "PSf"), polyethersulfone, polyamide, polyester, cellulose polymers, vinyl polymers, polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfone, and polyphenylene oxide can be used alone or in blends. Here, examples of cellulose polymers include cellulose acetate and cellulose nitrate. Examples of vinyl polymers include polyethylene, polypropylene, polyvinyl chloride, and polyacrylonitrile. Among these, homopolymers or copolymers of PSf, polyamide, polyester, cellulose acetate, cellulose nitrate, polyvinyl chloride, polyacrylonitrile, polyphenylene sulfide, polyphenylene sulfide sulfone, and polyphenylene sulfone are preferred, with PSf, cellulose acetate, polyphenylene sulfide sulfone, or polyphenylene sulfone being more preferred. PSf is particularly preferred because it has high chemical, mechanical, and thermal stability and is easy to mold.

[0025] The weight-average molecular weight (hereinafter referred to as "Mw") of PSf is preferably 10,000 to 200,000, and more preferably 15,000 to 100,000. When the Mw of PSf is 10,000 or more, desirable mechanical strength and heat resistance can be obtained as a porous support layer. On the other hand, when the Mw of PSf is 200,000 or less, the viscosity of the porous support layer stock solution is within an appropriate range, and good moldability can be achieved.

[0026] The thickness of the substrate and the porous support layer affects the strength of the composite semipermeable membrane and the packing density when it is used as a composite semipermeable membrane element. To obtain good mechanical strength and packing density, the combined thickness of the substrate and the porous support layer is preferably 50 μm to 300 μm, and more preferably 100 μm to 250 μm. Furthermore, the thickness of the porous support layer is preferably 20 μm to 100 μm. The thickness of the substrate and the porous support layer is the average value of 20 thicknesses measured at 20 μm intervals in a direction perpendicular to the thickness direction (the surface direction of the membrane) during cross-sectional observation.

[0027] 1.2 Separation Functional Layer The separation functional layer of the composite semipermeable membrane of this embodiment is provided on a porous support layer and contains cross-linked polyamide as its main component. "Main component" means a component that accounts for 50% by mass or more of the components constituting the separation functional layer. By containing 50% by mass or more of cross-linked polyamide, the separation functional layer can exhibit high removal performance. Furthermore, the cross-linked polyamide content in the separation functional layer is more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0028] "Cross-linked polyamide" means that the polyamide formed by the polycondensation reaction of a polyfunctional aromatic amine and a polyfunctional acid halide has a cross-linked structure. For example, the polyamide may have a cross-linked structure via a cross-linking agent, and at least one of the polyfunctional aromatic amine and the polyfunctional acid halide may be trifunctional or more, and the polyamide may have a network-like cross-linked structure. In particular, it is preferable that at least one of the polyfunctional aromatic amine and the polyfunctional acid halide is trifunctional or more. This results in rigid molecular chains and the formation of a pore structure suitable for the removal of fine solutes such as hydrated ions and boron. Furthermore, it is preferable that the cross-linked polyamide contained in the separation functional layer is a cross-linked aromatic polyamide formed by the polycondensation reaction of a polyfunctional aromatic amine and a polyfunctional aromatic acid halide.

[0029] A "polyfunctional aromatic amine" refers to an aromatic amine having at least two primary and / or secondary amino groups in one molecule. Examples of polyfunctional aromatic amines include polyfunctional aromatic amines in which two amino groups are bonded to the aromatic ring at the ortho, meta, or para position, such as o-phenylenediamine, m-phenylenediamine (hereinafter referred to as "m-PDA"), p-phenylenediamine, o-xylylenediamine, m-xylylenediamine, p-xylylenediamine, o-diaminopyridine, m-diaminopyridine, and p-diaminopyridine; and polyfunctional aromatic amines such as 1,3,5-triaminobenzene, 1,2,4-triaminobenzene, 3,5-diaminobenzoic acid, 3-aminobenzylamine, and 4-aminobenzylamine. These polyfunctional aromatic amines may be used individually or in combination.

[0030] In particular, m-PDA, p-phenylenediamine, or 1,3,5-triaminobenzene are preferably used from the viewpoint of selective separation, permeability, and heat resistance of the membrane. Furthermore, m-PDA is more preferred due to its ease of availability and handling. These polyfunctional aromatic amines may be used individually or in combination of two or more.

[0031] A "polyfunctional acid halide" refers to an acid halide having at least two halogenated carbonyl groups in one molecule. Examples of polyfunctional acid halides include aromatic trifunctional acid chlorides such as trimesic acid chloride (hereinafter referred to as "TMC") and trimellitic acid chloride, aliphatic trifunctional acid chlorides such as 1,3,5-cyclohexanetricarboxylic acid trichloride, aromatic difunctional acid chlorides such as biphenyldicarboxylic acid chloride, azobenzenedicarboxylic acid dichloride, terephthalic acid chloride, isophthalic acid chloride, and 2,6-naphthalenedicarboxylic acid dichloride, and aliphatic difunctional acid chlorides such as adipoyl chloride, sebacoyl chloride, and 1,4-cyclohexanedicarboxylic acid dichloride. These polyfunctional acid halides may be used individually or in combination of two or more.

[0032] From the viewpoint of the separation performance and heat resistance of the composite semipermeable membrane, polyfunctional acid halides are preferably polyfunctional aromatic acid chlorides having 2 to 4 chlorocarbonyl groups in one molecule. Among these, TMC is particularly preferred from the viewpoint of ease of availability and ease of handling.

[0033] 1.3 Coating Layer The coating layer of the composite semipermeable membrane of this embodiment is a layer that protects the separation function layer and is placed on the separation function layer.

[0034] 1.3.1 Interaction energy between polymer contained in coating layer and crosslinked polyamide The coating layer of the composite semipermeable membrane of this embodiment contains a polymer having hydrogen bond acceptors, and the interaction energy between the polymer and the crosslinked polyamide contained in the separation functional layer is -700 cal / mol / atom or more and -400 cal / mol / atom or less.

[0035] The polymer containing hydrogen bond acceptors in the coating layer (hereinafter also simply referred to as "polymer") is a polymer obtained by linking together a large number of monomer units. A "monomer unit" is a part within the polymer that originates from individual monomers. In other words, monomer units are units that can be linked together, and the linked molecules become polymers. Furthermore, the polymer containing hydrogen bond acceptors is preferably a copolymer formed from two or more types of monomer units, and may be a random copolymer, an alternating copolymer, or a block copolymer.

[0036] The coating layer may contain other components besides polymers having hydrogen bond acceptors, to the extent that they do not hinder the effects of the present invention. In particular, it is preferable that the main component of the coating layer be a polymer having hydrogen bond acceptors. Here, "main component" means a component that accounts for 50% by mass or more of the components constituting the coating layer. It is more preferable that the content of polymers having hydrogen bond acceptors in the coating layer be 80% by mass or more, even more preferable that be 90% by mass or more, and it is especially preferable that the coating layer is formed solely of polymers having hydrogen bond acceptors.

[0037] The "interaction energy between a polymer having hydrogen bond acceptors and a cross-linked polyamide (hereinafter also simply referred to as "interaction energy")" is an indicator that represents the strength of the interaction between the polymer and the cross-linked polyamide. In other words, the lower the interaction energy, the higher the adhesion between the polymer and the cross-linked polyamide. As a result of diligent research, the inventors have found that when the interaction energy between the polymer having hydrogen bond acceptors contained in the coating layer and the cross-linked polyamide is between -700 cal / mol / atom and -400 cal / mol / atom, swelling and decomposition of the cross-linked polyamide due to chemical contact are suppressed, and the removal performance can be maintained even after chemical contact.

[0038] When the interaction energy between the polymer and the crosslinked polyamide is less than -700 cal / mol / atom, swelling and decomposition of the crosslinked polyamide due to chemical contact can be suppressed. However, excessive adhesion between the crosslinked polyamide and the polymer reduces water permeability and causes a decrease in removal performance. Also, when the interaction energy is greater than -400 cal / mol / atom, the adhesion between the polymer and the crosslinked polyamide is insufficient, and the removal performance cannot be maintained after chemical contact. The interaction energy is more preferably between -700 cal / mol / atom and -450 cal / mol / atom, and even more preferably between -700 cal / mol / atom and -500 cal / mol / atom.

[0039] One method for controlling the interaction energy within the above range is to design the polymer molecules, as described in "1.3.3 Structure of Polymers Contained in the Coating Layer" below.

[0040] Interaction energy is generally expressed as the sum of van der Waals (hereinafter, "vdw") interaction energy and Coulomb interaction energy. Coulomb interaction energy represents the interaction due to hydrogen bonding. vdw interaction energy represents the degree of increase in physical contact area.

[0041] In the composite semipermeable film according to this embodiment, the Coulomb interaction energy between the polymer contained in the coating layer and the crosslinked polyamide is preferably -300 cal / mol / atom or more and -150 cal / mol / atom or less, more preferably -300 cal / mol / atom or more and -200 cal / mol / atom or less, and even more preferably -300 cal / mol / atom or more and -220 cal / mol / atom or less.

[0042] Furthermore, in the composite semipermeable film according to this embodiment, the vdw interaction energy between the polymer contained in the coating layer and the crosslinked polyamide is preferably -450 cal / mol / atom or more and -150 cal / mol / atom or less, more preferably -400 cal / mol / atom or more and -250 cal / mol / atom or less, and even more preferably -380 cal / mol / atom or more and -280 cal / mol / atom or less.

[0043] When the Coulomb interaction energy and the VDW interaction energy are within the above ranges, swelling and decomposition of the crosslinked polyamide due to chemical contact are suppressed, and the removeability can be maintained even after chemical contact.

[0044] One method for controlling the Coulomb interaction energy and the vdw interaction energy is to design the polymer molecule, as described in "1.3.3 Structure of the Polymer Contained in the Coating Layer". The interaction energy, Coulomb interaction energy, and vdw interaction energy are calculated using the method described in "Interaction Energy" in the examples below.

[0045] In this embodiment, the composite semipermeable membrane preferably contains monomer units in the coating layer that have hydrogen bond acceptors with a polarization degree of 0.68e or more and 1.00e or less, and more preferably has a polarization degree of 0.78e or more and 0.98e or less. Here, "polarization degree" refers to the partial charge of an atom calculated by quantum chemical calculations, and means the partial charge of the atom with the lowest polarization among the hydrogen bond acceptors contained in the monomer unit. The polarization degree is calculated by the method described in the "interaction energy" of the examples described later.

[0046] When the degree of polarization of the hydrogen bond acceptors of the polymer is 0.68e or higher, the Coulomb interaction between the polymer and the amide group of the crosslinked polyamide contained in the separation functional layer becomes stronger, resulting in a composite semipermeable film with high chemical resistance. Furthermore, when the degree of polarization is 1.00e or lower, the decrease in water permeability due to excessive adhesion between the crosslinked polyamide and the polymer can be suppressed. Examples of hydrogen bond acceptors with a degree of polarization of 0.68e or higher and 1.00e or lower include carboxyl groups, aldehyde groups, ester groups, amide groups, imide groups, isocyanate groups, urethane groups, urea groups and other carbonyl groups, nitro groups, phosphonic acid groups, phosphoryl groups, sulfo groups, sulfoxide groups, thiol groups, thioether groups, cyano groups, ether groups, hydroxyl groups, and amino groups. Note that the degree of polarization of these functional groups may change depending on the surrounding structure, such as the presence of other functional groups.

[0047] If the polymer contained in the coating layer is a copolymer, it is preferable that at least one monomer unit has a hydrogen bond acceptor with a polarization degree of 0.68e or more and 1.00e or less, more preferably that two or more monomer units have a hydrogen bond acceptor with a polarization degree of 0.68e or more and 1.00e or less, and even more preferably that all monomer units have a hydrogen bond acceptor with a polarization degree of 0.68e or more and 1.00e or less.

[0048] The polymer contained in the coating layer of the composite semipermeable membrane according to this embodiment preferably consists only of non-halogen atoms. Since halogen atoms usually act as electron-withdrawing groups, their proximity to hydrogen-bonding functional groups can affect the degree of polarization. Furthermore, halogen atoms hydrolyze in water, releasing halogen atoms into the water, which raises concerns about water pollution.

[0049] The polymer contained in the coating layer of the composite semipermeable membrane according to this embodiment is preferably nonionic. Here, "nonionic" means that, other than the ends of the polymer, it does not have functional groups that dissociate into ions in hydrochloric acid at pH 2 to 7 or in an aqueous sodium hydroxide solution at pH 7 to 13. Therefore, hydrogen bond acceptors are preferably aldehyde groups, ester groups, amide groups, imide groups, isocyanate groups, urethane groups, urea groups, hydroxyl groups, ether groups, thiol groups, nitro groups, cyano groups, thioether groups, sulfoxide groups, etc. Among these, functional groups having carbonyl groups such as aldehyde groups, ester groups, amide groups, urethane groups, and urea groups, and ether groups are more preferred, and amide groups and urea groups are even more preferred. When the polymer contained in the coating layer is nonionic, the polymer does not dissociate into ions during chemical washing with water, acids, or alkalis, and the polymers are not affected by ionic repulsion, thus suppressing peeling of the coating layer. By suppressing the peeling of the coating layer, the interaction between the polymer contained in the coating layer and the cross-linked polyamide is maintained even in acidic and alkaline solutions, thereby improving the chemical resistance of the composite semipermeable film.

[0050] 1.3.2 Interaction Energy Between Polymers and Water Molecules in the Coating Layer The composite semipermeable membrane according to this embodiment preferably has an interaction energy between polymers and water molecules in the coating layer of -2000 cal / mol / atom or more and -1000 cal / mol / atom or less, more preferably -1900 cal / mol / atom or more and -1100 cal / mol / atom or less, and even more preferably -1800 cal / mol / atom or more and -1200 cal / mol / atom or less. When the interaction energy between polymers and water molecules is within the above range, both the solubility of the polymer in water-soluble solvents and adhesion to crosslinked polyamides can be achieved. Therefore, it becomes easy to form a coating layer on a crosslinked polyamide by bringing a water-soluble solvent containing the polymer that forms the coating layer into contact with the separation functional layer.

[0051] The interaction energy between a polymer and water molecules can be calculated by, for example, designing the polymer molecule as described in "1.3.3 Structure of Polymers Contained in the Coating Layer" below. The interaction energy between the polymer and water molecules is calculated by the method described in "Interaction Energy" in the examples below.

[0052] 1.3.3 Structure of Polymers Contained in the Coating Layer The polymers contained in the coating layer of the composite semipermeable membrane according to this embodiment have hydrogen bond acceptors. As described above, examples of hydrogen bond acceptors include aldehyde groups, ester groups, amide groups, imide groups, isocyanate groups, urethane groups, urea groups, hydroxyl groups, ether groups, thiol groups, nitro groups, cyano groups, thioether groups, sulfoxide groups, phosphonic acid groups, and phosphoryl groups. From the viewpoint of setting the polarization degree of the hydrogen bond acceptors to 0.68e or more and 1.00e or less and making the polymer nonionic, the hydrogen bond acceptors are more preferably functional groups having carbonyl groups such as aldehyde groups, ester groups, amide groups, urethane groups, and urea groups, and even more preferably amide groups and urea groups. By increasing the polarization degree and ratio of hydrogen bond acceptors contained in the polymer, the Coulomb interaction of the crosslinked polyamide can be strengthened.

[0053] The polymer contained in the coating layer of the composite semipermeable membrane according to this embodiment preferably has a structure represented by the following general formula (I).

[0054]

[0055] In general formula (I), R in the repeating unit １ and R ２ Each of these is independently a hydrogen atom or a hydrocarbon group having 2 or fewer carbon atoms, and n is an integer of 5 or more.

[0056] When a polymer has the structure represented by the general formula (I) above, its affinity for water-soluble solvents improves, and vdw interactions act between the ether group and the crosslinked polyamide, resulting in a stronger interaction between the polymer and the crosslinked polyamide. In other words, the vdw interaction energy with the crosslinked polyamide can be controlled by the content of the structure represented by general formula (I) in the polymer.

[0057] R １ and R ２ R is more preferably hydrogen or a hydrocarbon group having 1 carbon atom. １ and R ２ When n is a hydrogen atom or a hydrocarbon group with one carbon atom, steric hindrance is small, and the contact area between the polymer and the crosslinked polyamide increases, thus strengthening the vdw interaction. Furthermore, n is preferably an integer between 5 and 500, more preferably between 5 and 300, and even more preferably between 10 and 250. When n is an integer of 5 or more, in addition to the vdw interaction, more hydrogen bonds are formed between the ether group of the polymer and the crosslinked polyamide, thus strengthening the Coulomb interaction and lowering the interaction energy. When n is an integer of 500 or less, the structure represented by general formula (I) and other interacting sites are more easily dispersed uniformly within the polymer contained in the coating layer of the composite semipermeable film. As a result, strong vdw interactions are more easily formed between the crosslinked polyamide and the polymer.

[0058] The polymer contained in the coating layer of the composite semipermeable membrane according to this embodiment preferably has a carbon chain with four or more carbon atoms in its main chain. A carbon chain is a part composed of multiple carbon atoms and hydrogen atoms, and may be arbitrarily substituted with functional groups such as hydroxyl groups. When the carbon chain has four or more carbon atoms, a strong vdw interaction acts between the polymer and the crosslinked polyamide, improving the chemical resistance of the composite semipermeable membrane. Furthermore, it is preferable that the carbon chain has 12 or fewer carbon atoms. When the carbon chain has 12 or fewer carbon atoms, the solubility of the polymer in water-soluble solvents increases. Therefore, it is possible to form a coating layer by contacting a water-soluble solvent containing the polymer that forms the coating layer on the separation functional layer. In other words, by controlling the carbon chain of the main chain in the polymer, the vdw interaction energy with the crosslinked polyamide and the interaction energy with water can be controlled. Specifically, the polymer contained in the coating layer of the composite semipermeable membrane is more preferably a carbon chain with four to 12 carbon atoms in its main chain, even more preferably a carbon chain with four to 10 carbon atoms, and even more preferably a carbon chain with four to 6 carbon atoms. The carbon chain may be linear or cyclic, and may have unsaturated bonds. If the polymer contained in the coating layer is a copolymer having two or more different monomer units, at least one monomer unit may have a carbon chain with four or more carbon atoms in its main chain. It is more preferable that all monomer units have a carbon chain with four or more carbon atoms in their main chain.

[0059] Examples of carbon chains with 4 to 12 carbon atoms include butylene groups (-C ４ H ８ -), pentylene group (-C ５ H １０ -), hexylene group (-C ６ H １２ -), heptylene group (-C ７ H １４ -), octylene group (-C ８ H １６ -), nonylene group (-C) ９ H １８ -), decilen group (-C １０ H ２０ -), undecylene group (-C １１ H ２２-), dodecylene group (-C １２ H ２４ Hydrocarbons such as -), butenylene group (-C) ４ H ６ -), pentenylene group (-C ５ H ８ -), hexenylene group (-C ６ H １０ Hydrocarbons having an unsaturated structure such as -), cyclobutylene group (-C) ４ H ６ -), cyclopentylene group (-C ５ H ８ -), cyclohexylene group (-C ６ H １０ Cyclic hydrocarbons such as -), phenylene group (-C) ６ H ４ Examples include aromatic ring hydrocarbons such as (-C). These carbon chains may be optionally substituted. In particular, the carbon chain may have a butylene group (-C). ４ H ８ -), pentylene group (-C ５ H １０ -), hexylene group (-C ６ H １２ -), phenylene group (-C ６ H ４ -) is preferable.

[0060] The polymer contained in the coating layer of the composite semipermeable membrane according to this embodiment preferably contains monomer units having at least one structure selected from the group consisting of structures represented by the following general formulas (II) to (VI).

[0061]

[0062] In general formulas (II) to (VI), R ３ , R ４ , R ７ , R ９ and R １０ Each of these is a hydrocarbon group having 4 to 12 carbon atoms, which may be independently substituted, and R ５ , R ６ and R ８ Each of these is independently a hydrogen atom, a hydrocarbon group having 2 or fewer carbon atoms, or a functional group having 2 or fewer carbon atoms.

[0063] Since the structures represented by the above general formulas (II) to (VI) all have a carbonyl group which is a hydrogen bond acceptor, when the polymer contains monomer units having the structures represented by the above general formulas (II) to (VI), the Coulomb interaction between the polymer contained in the coating layer and the crosslinked polyamide becomes stronger. Also, due to the hydrocarbon groups represented by R ３ , R ４ , R ７ , R ９ , and R １０ , the vdW interaction between the polymer and the crosslinked polyamide becomes stronger. That is, the Coulomb interaction energy and the vdW interaction energy between the polymer and the crosslinked polyamide can be controlled by the content of the structures represented by the general formulas (II) to (VI) in the polymer.

[0064] From the above viewpoints, the carbon number of R ３ , R ４ , R ７ , R ９ , and R １０ is preferably 4 or more and 11 or less, more preferably 4 or more and 10 or less, still more preferably 4 or more and 8 or less, and even more preferably 4 or more and 6 or less. R ５ , R ６ , and R ８ are preferably hydrogen, a methyl group, an ethyl group, or a methoxymethyl group from the viewpoint of suppressing the inhibition of the interaction between the polymer and the crosslinked polyamide by steric hindrance.

[0065] Also, the polymer contained in the coating layer of the composite semipermeable membrane according to the present embodiment is preferably a copolymer and contains at least one of the structures represented by the following general formulas (VII) and (VIII). <000028o>In general formulas (VII) and (VIII), R

[0067]

[0068] [[ID=4l]]In general formulas (VII) and (VIII), R １１ , R １２, R １４ , R １６ , R １７ , R １８ , R ２０ , R ２１ , R ２３ , R ２４ and R ２６ are each independently hydrogen, a hydrocarbon group having 2 or fewer carbon atoms, or a functional group having 2 or fewer carbon atoms. R １３ and R １５ are each independently a hydrocarbon group having 4 to 12 carbon atoms, which may be substituted. R １９ , R ２２ , R ２５ is a hydrocarbon group having 2 to 12 carbon atoms, which may be substituted. X is a structure containing the general formula (I), and r, q, y, and z are each independently an integer of 5 or more.

[0069] By the polymer containing at least one of the structures represented by the general formulas (VII) and (VIII), the Coulomb interaction and vdW interaction between the polymer and the crosslinked polyamide become stronger, and excellent chemical resistance is obtained.

[0070] In the general formulas (II) to (VI), R ３ , R ４ , R ７ , R ９ and R １０ are the same as R １３ and R １５ , and the number of carbon atoms of R

[0071] In the general formulas (III) and (IV), R ５ , R ６ and R ８ are the same as R １１ , R １２ , R １４ , R １６ , R １７ , R １８ , R ２０ , R ２１ , R ２３ , R ２４ and R ２６ are preferably hydrogen, a methyl group, an ethyl group, a methoxymethyl group, etc.

[0072] R １９ , R ２５ The number of carbon atoms is preferably 2 to 11, more preferably 4 to 10, and even more preferably 6 to 10. 2 to 11 is preferred, R ２２ The number of carbon atoms is more preferably 2 to 10, and even more preferably 2 to 6. ２２ Preferred examples include ethylene groups, propylene groups, butylene groups, pentylene groups, and hexylene groups. Each of r, q, y, and z is an integer of 5 or greater, and integers of 10 or greater are more preferred. When r, q, y, and z are integers of 5 or greater, a vdw interaction acts between the polymer and the crosslinked polyamide, resulting in a lower interaction energy.

[0073] The polymer contained in the coating layer of the composite semipermeable membrane according to this embodiment is preferably a copolymer of hydrophilic units and hydrophobic units. By using a copolymer of hydrophilic and hydrophobic units, it is easier to achieve both Coulomb interaction and VDW interaction.

[0074] A "hydrophilic unit" refers to a monomer unit from which a single polymer (Mw: 10,000 g / mol) is water-soluble. Here, "water-soluble" means that it dissolves in water at 25°C at a concentration of 0.05% by mass or more.

[0075] A "hydrophobic unit" refers to a monomer unit from which a single polymer (Mw: 10,000 g / mol) obtained from the monomer unit does not have water solubility. Here, "does not have water solubility" means that it does not dissolve in water at 25°C at a concentration of 0.05% by mass or less.

[0076] In other words, when the copolymer contained in the coating layer is a copolymer represented as A-B, where A and B are monomer units, it is preferable that one of the polymers consisting only of A and the polymer consisting only of B is water-soluble, while the other is not water-soluble.

[0077] In the case of a copolymer of hydrophilic units and hydrophobic units, it is preferable that both the hydrophilic and hydrophobic units have hydrogen bond acceptors from the viewpoint of strengthening Coulomb interactions. The degree of polarization of the hydrogen bond acceptors of the hydrophilic units is preferably 0.68e or more and 1.00e or less, and more preferably 0.78e or more and 0.98e or less, as described above. The degree of polarization of the hydrogen bond acceptors of the hydrophobic units is more preferably 0.75e or more and 1.00e or less, and more preferably 0.75e or more and 0.95e or less.

[0078] The hydrophobic unit preferably has a structure represented by the above general formula (III). The hydrophilic unit preferably has a structure represented by the above general formula (I), and more preferably has a structure represented by the above general formula (II) and / or (IV).

[0079] The copolymer preferably has a mass ratio of hydrophilic units to hydrophobic units of 0.5 to 100, more preferably 1 to 50, and even more preferably 1 to 20. When the mass ratio of hydrophilic units to hydrophobic units is 0.5 or higher, the decrease in membrane permeation flux of the composite semipermeable membrane can be suppressed. Furthermore, when the mass ratio of hydrophilic units to hydrophobic units is 100 or lower, the hydrophobic interaction between the copolymer and polyamide contained in the coating layer becomes stronger, and the vdw interaction energy decreases, thus improving chemical resistance. The mass ratio of hydrophilic units to hydrophobic units can be controlled, for example, by the mass ratio of monomer units during the synthesis of the copolymer.

[0080] As described above, by designing polymers that include structures that affect Coulomb interactions and VDW interactions, the interaction energy between the polymer and the crosslinked polyamide can be controlled within a desirable range.

[0081] In this embodiment, the coating layer of the composite semipermeable membrane is preferably insolubilized so that it does not leach out when the composite semipermeable membrane is used. Methods for insolubilizing the coating layer include, for example, a method of forming non-covalent bonds such as hydrogen bonds or ionic bonds between the coating layer and a crosslinked polyamide and immobilizing it on the separation functional layer; a method of forming covalent bonds between the crosslinked polyamide and a crosslinking agent and immobilizing it on the separation functional layer; and a method of forming covalent bonds between the coating layers with a crosslinking agent and immobilizing them as a three-dimensional structure. Among these, from the viewpoint of being able to continue stable operation over a long period of time, the method of forming covalent bonds between the coating layer and a crosslinking agent and immobilizing it on the separation functional layer is more preferable.

[0082] The degree of polymerization of the polymer contained in the coating layer of the composite semipermeable membrane according to this embodiment is preferably 100 to 4,000, more preferably 120 to 3,500, and even more preferably 150 to 3,000. When the degree of polymerization is 100 or higher, the polymer contained in the coating layer is less likely to dissolve from the polyamide separation functional layer into water. When the degree of polymerization is 4,000 or lower, a decrease in the membrane permeation flux of the composite semipermeable membrane can be suppressed.

[0083] The polymer contained in the coating layer of the composite semipermeable membrane according to this embodiment is preferably water-soluble or soluble in water-soluble solvents. By the polymer being water-soluble or soluble in water-soluble solvents, a coating layer containing the polymer can be formed on the composite semipermeable membrane using a solvent that does not alter the composite semipermeable membrane. Here, "water-soluble" means dissolving in water at 25°C at a concentration of 0.05% by mass or more. Furthermore, "solubility in water-soluble solvents" means dissolving in a solvent at 25°C that has the above-mentioned "water-soluble" properties at a concentration of 0.05% by mass or more. Examples of water-soluble solvents include acetic acid, acetone, acetonitrile, N,N-dimethylformamide (hereinafter referred to as "DMF"), dimethyl sulfoxide, dioxane, methanol, ethanol, propanol, tetrahydrofuran, dimethylacetamide, and N-methylpyrrolidone.

[0084] In this embodiment, the combined thickness of the separation functional layer and the coating layer in the composite semipermeable membrane is preferably 10 nm to 100 nm, more preferably 11 nm to 70 nm, and even more preferably 11 nm to 50 nm. When the combined thickness of the separation functional layer and the coating layer is 10 nm or more, a composite semipermeable membrane with good separation performance can be obtained. On the other hand, when the combined thickness of the separation functional layer and the coating layer is 100 nm or less, a composite semipermeable membrane with good membrane permeation flux can be obtained. The combined thickness of the separation functional layer and the coating layer can be measured by observing the composite semipermeable membrane with a scanning transmission electron microscope.

[0085] The presence of a polymer having the above-described structure in the coating layer of a composite semipermeable membrane makes it possible, for example, to detect characteristic peaks such as amide groups of the polymer contained in the coating layer by time-of-flight secondary ion mass spectrometry, X-ray photoelectron spectroscopy, Raman spectroscopy, or infrared spectroscopy on the surface of the separation functional layer of the composite semipermeable membrane. Furthermore, the structure of the polymer can also be identified by extracting only the coating layer and analyzing it by nuclear magnetic resonance spectroscopy, liquid chromatography-mass spectrometry, or gas chromatography-mass spectrometry.

[0086] 1.4 Composite Semipermeable Membrane Element The composite semipermeable membrane element according to this embodiment comprises the composite semipermeable membrane according to this embodiment. An example of the configuration of the composite semipermeable membrane element will be described with reference to Figure 2.

[0087] As shown in Figure 2, the composite semipermeable membrane element 5 comprises a composite semipermeable membrane 1, a supply-side channel material 8, a permeable-side channel material 9, a water collection pipe 10, and end plates 6 and 7. The supply-side channel material 8 is positioned opposite the supply side of the composite semipermeable membrane 1 and is wrapped around the water collection pipe 10 together with the composite semipermeable membrane 1. For the supply-side channel material 8, a net is preferred, for example. The permeable-side channel material 9 is positioned opposite the permeable side of the composite semipermeable membrane 1 and is wrapped around the water collection pipe 10 together with the composite semipermeable membrane 1. For the permeable-side channel material 9, tricot or a protrusion-fixing sheet can be used, for example. The water collection pipe 10 is a hollow cylindrical member with multiple holes on its side. The end plates 6 and 7 are disc-shaped members with multiple supply ports (or discharge ports).

[0088] The separation of fluids by the composite semipermeable membrane element 5 will now be explained. The supply water 11 is supplied to the composite semipermeable membrane element 5 from multiple supply ports on the end plate 6. The supply water 11 moves within the supply-side flow channel formed by the supply-side flow channel material 8 on the supply side of the composite semipermeable membrane 1. The fluid that permeates through the composite semipermeable membrane 1 (shown as permeate water 12 in the figure) moves within the permeate-side flow channel formed by the permeate-side flow channel material 9. The permeate water 12 that reaches the collection pipe 10 enters the interior through its holes, and the permeate water 12 that flows inside the collection pipe 10 is discharged to the outside from the end plate 7. On the other hand, the fluid that does not permeate through the composite semipermeable membrane 1 (shown as concentrated water 13 in the figure) moves within the supply-side flow channel and is discharged to the outside from the end plate 7. In this way, the supply water 11 is separated into permeate water 12 and concentrated water 13.

[0089] 2. Method for Manufacturing a Composite Semipermeable Film 2.1 Support Film Formation Process Known methods can be suitably used for forming the support film. The following description will take the case where PSf is used as the material for the porous support layer as an example.

[0090] First, PSf is dissolved in a suitable solvent to prepare a porous support layer stock solution. DMF is a preferred suitable solvent for PSf.

[0091] The concentration of PSf in the porous support layer stock solution is preferably 10% to 25% by mass, and more preferably 12% to 20% by mass. When the concentration of PSf in the porous support layer stock solution is within the above range, both the strength and membrane permeation flux of the resulting porous support layer can be achieved. The preferred range of material concentration in the porous support layer stock solution can be appropriately adjusted depending on the material used, the good solvent, etc.

[0092] Next, the obtained porous support layer stock solution is applied to the substrate surface and immersed in a solidification solution containing a non-solvent of PSf. Water is preferred as the non-solvent of PSf in the solidification solution. By bringing the porous support layer stock solution applied to the substrate surface into contact with the solidification solution containing a non-solvent of PSf, the porous support layer stock solution solidifies through non-solvent-induced phase separation, and a support film with a porous support layer is obtained on the substrate surface.

[0093] The coagulation solution may consist solely of non-solvent PSf, but it may also contain a good solvent for PSf to the extent that it can coagulate the porous support layer stock solution.

[0094] The resulting support film may be washed before the formation of the separation functional layer to remove any remaining solvent in the film.

[0095] 2.2 Formation Process of the Separation Functional Layer A method for forming a separation functional layer containing crosslinked polyamide will be described using as an example a method in which a polyfunctional aromatic amine and a polyfunctional acid halide are polymerized and solidified on the support film obtained in "2.1 Formation Process of the Support Film". From the viewpoint of productivity and performance, interfacial polymerization is the most preferred polymerization method. The interfacial polymerization process will be described below.

[0096] The interfacial polymerization process comprises: (a) contacting an aqueous solution containing a polyfunctional aromatic amine with a support film; (b) contacting an organic solvent solution containing a polyfunctional acid halide with the support film that has been contacted with the aqueous solution containing the polyfunctional aromatic amine; (c) draining the organic solvent solution after contact; and (d) washing the composite semipermeable film from which the organic solvent solution has been drained with hot water.

[0097] In step (a), the aqueous solution contains at least a polyfunctional aromatic amine. As the polyfunctional aromatic amine, for example, the polyfunctional aromatic amines described in "1.2 Separation Functional Layer" above can be used.

[0098] The concentration of the polyfunctional aromatic amine in the aqueous solution is preferably 0.1% by mass or more and 20% by mass or less, more preferably 0.5% by mass or more and 15% by mass or less, and even more preferably 1.0% by mass or more and 10% by mass or less. When the concentration of the polyfunctional aromatic amine is 0.1% by mass or more, a separation functional layer having solute separation performance can be formed. On the other hand, when the concentration of the polyfunctional aromatic amine is 20% by mass or less, a separation functional layer having good membrane permeation flux can be formed. Furthermore, the aqueous solution may contain compounds such as surfactants and antioxidants as needed, as long as they do not inhibit polymerization.

[0099] It is preferable to bring the polyfunctional aromatic amine aqueous solution into uniform and continuous contact with the support film. Specifically, examples include coating the support film with the polyfunctional aromatic amine aqueous solution or immersing the support film in the aqueous solution. The contact time between the support film and the aqueous solution is preferably 1 second to 10 minutes, and more preferably 3 seconds to 3 minutes.

[0100] After contacting the polyfunctional aromatic amine aqueous solution with the support membrane, it is preferable to thoroughly drain the liquid so that no droplets remain on the support membrane. Thorough draining prevents residual droplets from becoming membrane defects and reducing separation performance after the formation of the composite semipermeable membrane. Methods for draining include, for example, holding the support membrane vertically after contact with the aqueous solution to allow excess solution to flow naturally, or forcibly draining the liquid by blowing a stream of air such as nitrogen from an air nozzle. Alternatively, after draining, the membrane surface can be dried to remove some of the water from the aqueous solution.

[0101] In step (b), as the polyfunctional acid halide, for example, the polyfunctional acid halide described in "1.2 Separation Functional Layer" above can be used.

[0102] The organic solvent is preferably immiscible with water, dissolves polyfunctional acid halides, does not damage the support film, and is inert to polyfunctional aromatic amines and polyfunctional acid halides. Examples of organic solvents include hydrocarbon compounds such as n-nonane, n-decane, n-undecane, n-dodecane, isooctane, isodecane, and isododecane, as well as mixed solvents thereof.

[0103] The concentration of the polyfunctional acid halide in the organic solvent solution is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.02% by mass or more and 4% by mass or less, and even more preferably 0.03% by mass or more and 2% by mass or less. When the concentration of the polyfunctional acid halide is 0.01% by mass or more, polymerization can proceed at a sufficient reaction rate. On the other hand, when the concentration of the polyfunctional acid halide is 10% by mass or less, the occurrence of side reactions during polymerization can be suppressed. Furthermore, the organic solvent solution may contain compounds such as surfactants as needed, as long as they do not inhibit polymerization.

[0104] It is preferable to uniformly and continuously bring the organic solvent solution of the polyfunctional acid halide into contact with a support film that has been brought into contact with an aqueous solution of a polyfunctional aromatic amine. Specifically, for example, one method is to coat the support film that has been brought into contact with an aqueous solution of a polyfunctional acid halide with the organic solvent solution of the polyfunctional acid halide. The contact time between the support film that has been brought into contact with the aqueous solution of a polyfunctional aromatic amine and the organic solvent solution of the polyfunctional acid halide is preferably 3 seconds to 10 minutes, and more preferably 5 seconds to 3 minutes.

[0105] Furthermore, if necessary, the support film in contact with the organic solvent solution of the polyfunctional acid halide may be heat-treated. When heat-treated, the heating temperature is preferably 35°C to 180°C, more preferably 50°C to 160°C, and even more preferably 60°C to 150°C. The optimal heating time varies depending on the temperature of the film surface, which is the reaction site, but is preferably 5 seconds or more, and more preferably 10 seconds or more.

[0106] In step (c), the organic solvent solution on the composite semipermeable membrane after the polymerization reaction is removed by dewatering. Methods for dewatering include, for example, gripping the membrane vertically and allowing the excess organic solvent solution to flow down naturally; blowing air with a fan to dry and remove the organic solvent; or removing the excess organic solvent solution with a mixed fluid of water and air.

[0107] In step (d), the composite semipermeable membrane from which the organic solvent has been removed is washed with hot water. The temperature of the hot water is preferably 40°C to 95°C, and more preferably 60°C to 95°C. If the temperature of the hot water is 40°C or higher, unreacted substances and oligomers remaining in the membrane can be sufficiently removed. On the other hand, if the temperature of the hot water is 95°C or lower, the degree of shrinkage of the composite semipermeable membrane does not increase, and a good membrane permeation flux can be maintained. The preferred range of the hot water temperature can be appropriately adjusted depending on the polyfunctional aromatic amine or polyfunctional acid halide used.

[0108] 2.3 Formation of the coating layer The composite semipermeable film processed in this step may be an unused film or a film that has deteriorated due to use or other factors. Furthermore, this step can be considered one of the manufacturing steps for the composite semipermeable film.

[0109] The process for forming the coating layer comprises (e) bringing a solution containing a polymer having an interaction energy with the crosslinked polyamide of -700 cal / mol / atom or more and -400 cal / mol / atom or less (hereinafter referred to as "polymer solution") into contact with the separation functional layer; (f) draining off excess solution; and (g) washing the composite semipermeable membrane.

[0110] In step (e), the polymer solution may optionally contain compounds such as a crosslinking agent. The crosslinking agent may crosslink the polymers forming the coating layer with each other, or it may crosslink the polymers forming the coating layer with the polyamide in the separation functional layer. When the polymers forming the coating layer are fixed to the polyamide in the separation functional layer by the crosslinking agent, further improvement in chemical resistance can be expected. Examples of crosslinking agents include molecules having multiple glycidyl groups in the molecule, such as ethylene glycol diglycidyl ether, and methyl vinyl ether / maleic anhydride copolymer.

[0111] The solution contains water and at least one solvent selected from the water-soluble solvents mentioned above. In other words, the solution may contain two or more solvents.

[0112] It is preferable to bring the polymer solution into uniform and continuous contact with the separation functional layer. Specifically, for example, one method is to coat the separation functional layer with the solution. The contact time between the separation functional layer and the solution is preferably 5 seconds to 10 hours, and more preferably 10 seconds to 1 hour.

[0113] The concentration of the polymer solution is preferably 0.0001% by mass or more and 10% by mass or less, more preferably 0.0001% by mass or more and 2% by mass or less, and even more preferably 0.005% by mass or more and 1% by mass or less. When the concentration of the polymer solution is 0.0001% by mass or more, a sufficient amount of polymer that forms a coating layer comes into contact with the surface of the separation functional layer, so excellent chemical resistance can be achieved. On the other hand, when the concentration of the polymer solution is 10% by mass or less, a composite semipermeable membrane with sufficient membrane permeation flux can be obtained.

[0114] In step (f), the solution on the composite semipermeable membrane is removed by dewatering. Methods of dewatering include, for example, gripping the membrane vertically and allowing the excess solution to flow down naturally, or blowing air with a fan to dry and remove the solvent.

[0115] In step (g), the composite semipermeable membrane from which the solution has been removed is washed with water. The water temperature is preferably 15°C to 95°C, and more preferably 20°C to 90°C. If the water temperature is 15°C or higher, unreacted substances and catalysts remaining in the membrane can be sufficiently removed. On the other hand, if the water temperature is 95°C or lower, the degree of shrinkage of the composite semipermeable membrane does not increase, and a good membrane permeation flux can be maintained. The preferred range of water temperature can be appropriately adjusted depending on the water-soluble polymer and crosslinking agent used.

[0116] Furthermore, the composite semipermeable membrane may be hydrophilized if necessary. Examples of hydrophilization methods include contacting the composite semipermeable membrane with aqueous solutions of surfactants such as polyoxyethylene octylphenyl ether and sodium n-decylbenzenesulfonate, or aqueous solutions of alcohols such as methanol, ethanol, isopropanol, and glycerin.

[0117] 3. Method of Using the Composite Semipermeable Membrane The composite semipermeable membrane according to this embodiment is preferably used as a spiral-type composite semipermeable membrane element, wound around a cylindrical water collection pipe with numerous holes, together with a water supply channel material such as a plastic net, a permeable water channel material such as tricot, and a film to enhance pressure resistance as needed. Furthermore, a composite semipermeable membrane module can be formed by connecting these elements in series or parallel and housing them in a pressure vessel.

[0118] Furthermore, the composite semipermeable membranes, their elements, and modules can be combined with pumps that supply water to them, and devices that pre-treat the supply water to constitute a fluid separation system. By using this separation system, the supply water can be separated into permeate (such as drinking water) and concentrated water that did not permeate the membrane, thereby obtaining water suitable for the purpose.

[0119] From the viewpoint of reducing environmental impact and effectively utilizing water resources, it is preferable that the fluid separation device is applicable to zero-liquid discharge systems (hereinafter referred to as "ZLD") and resource recovery applications. In ZLD, wastewater is concentrated using membrane separation technology, and then subjected to evaporation and drying treatment. Because the wastewater is concentrated to the extreme, foulants in the feedwater are concentrated, making fouling likely to occur. Furthermore, since fouling is eliminated by frequent chemical cleaning, it is preferable to use a composite semipermeable membrane with excellent chemical resistance. In ZLD, it is preferable to equip the upstream with a UF membrane device, as this allows for efficient removal of foulants. Industries in which ZLD is introduced include, for example, semiconductor and electronic component manufacturing, chemical industry, thermal power plants, and dyeing and textile factories. Since the wastewater from these industries may have a temperature of 35°C or higher, it is preferable that the fluid separation device used in ZLD can be used under conditions where the feedwater temperature is 35°C or higher. When the feedwater is at a high temperature of 35°C or higher, the deterioration of the composite semipermeable membrane equipped in the fluid separation device is accelerated, which is a problem. In resource recovery applications, useful components are concentrated from factory wastewater and other sources using membrane separation technology, and then recovered by sedimentation or adsorption. In this process, the treated water may contain acidic or alkaline substances and oxidizing agents, making composite semipermeable membranes prone to degradation. Therefore, it is preferable to use composite semipermeable membranes with excellent chemical resistance.

[0120] The composite semipermeable membrane according to this embodiment has excellent oxidation resistance, acid resistance, and alkali resistance, and can suppress degradation by chemicals, which is a concern in ZLD and resource recovery applications. Therefore, it can be preferably used in fluid separation devices for ZLD and resource recovery.

[0121] Furthermore, from the viewpoint of improving yield and reliability in the manufacturing process, fluid separation devices are preferably applicable to precision industries that use high-purity water and chemicals, such as semiconductor manufacturing. Examples of precision industries include the pharmaceutical and biopharmaceutical manufacturing fields where high purity of raw materials and solvents is required; the electronic and optical materials manufacturing fields where impurity control is required to maintain optical and electrical properties; the nuclear-related fields where the purity of chemicals and water affects the behavior of radioactive materials; and high-precision analytical fields such as mass spectrometry and chromatography, where the purity of reagents and solvents directly affects analytical accuracy. For example, hydrogen peroxide, one of the chemicals used for cleaning in the semiconductor manufacturing process, is generally synthesized and then purified by a method that utilizes the oxidation-reduction reaction of anthraquinones in an organic solvent. Impurities remaining in these manufacturing processes cause a decrease in semiconductor manufacturing yield, so it is preferable that they be removed in the purification process.

[0122] The composite semipermeable membrane according to this embodiment has excellent oxidation resistance, acid resistance, and alkali resistance, making it less susceptible to degradation caused by chemicals present in the liquid supplied to the composite semipermeable membrane. Therefore, it can effectively separate water, hydrogen peroxide, and other chemicals from impurities, and the quality of the permeate remains stable during operation. As a result, it can be preferably used in fluid separation devices for the purification of water and chemicals used in precision industries.

[0123] Examples of feedwater treated by the composite semipermeable membrane according to this embodiment include liquid mixtures containing 500 mg / L to 100 g / L of TDS (Total Dissolved Solids), such as seawater, brine, and wastewater. Generally, TDS refers to the total amount of dissolved solids and is expressed as "mass / volume" or "mass ratio". According to the definition, it can be calculated from the weight of the residue after evaporating a solution filtered through a 0.45 μm filter at a temperature of 39.5 to 40.5°C, but a simpler method is to convert it from the practical salinity (S).

[0124] While a higher operating pressure for the fluid separation device improves the solute removal rate, it also increases the energy required for operation. Furthermore, considering the durability of the composite semipermeable membrane, the operating pressure when the treated water is permeated through the composite semipermeable membrane is preferably between 0.5 MPa and 10 MPa. Although a higher feedwater temperature reduces the solute removal rate, a lower temperature reduces the membrane permeation flux, so a temperature between 5°C and 45°C is preferable. If the feedwater pH is high, there is a risk of scale formation, such as magnesium, in the case of feedwater with high solute concentrations such as seawater, and there is also a concern about membrane deterioration due to high pH operation, so operation in the neutral range is preferable.

[0125] When a composite semipermeable membrane is used as a reverse osmosis membrane, the NaCl removal rate is preferably 99.0% or higher, more preferably 99.30% or higher, and even more preferably 99.50% or higher. The membrane permeation flux is preferably 0.5 m / d or more and 1.8 m / d or less, more preferably 0.7 m / d or more and 1.8 m / d or less, and even more preferably 1.0 m / d or more and 1.8 m / d or less. The chemical resistance of the composite semipermeable membrane in this specification refers to a small difference in membrane performance before and after the membrane degradation test in the "membrane degradation test" described in the examples. Specifically, the NaCl removal rate after the membrane degradation test is preferably 98.5% or higher, more preferably 98.7% or higher, and even more preferably 99.0% or higher. The membrane permeation flux ratio, which is the value obtained by dividing the membrane permeation flux after the membrane degradation test by the membrane permeation flux before the membrane degradation test, is preferably 2.0 or less, more preferably 1.8 or less, and even more preferably 1.7 or less. Furthermore, a smaller difference in membrane performance before and after the immersion treatment described in the "Immersion Treatment in Hydrogen Peroxide Solution" section of the Examples indicates higher chemical resistance. Specifically, the membrane permeation flux ratio, which is the value obtained by dividing the membrane permeation flux after the immersion treatment by the membrane permeation flux before the immersion treatment, is preferably 1.7 or less, more preferably 1.6 or less, and even more preferably 1.5 or less. The NaCl removal rate is calculated using the method described in "NaCl Removal Rate" in the Examples described later. The membrane permeation flux is also calculated using the method described in "Membrane Permeation Flux" in the Examples described later.

[0126] 4. Coating Agents for Composite Semipermeable Membranes As described above, a solution containing a polymer whose interaction energy with crosslinked polyamide is between -700 cal / mol / atom and -400 cal / mol / atom forms hydrogen bonds with the crosslinked polyamide, and improves the chemical resistance of the composite semipermeable membrane through VDW interactions and Coulomb interactions. Therefore, it can be used as a coating agent for composite semipermeable membranes containing crosslinked polyamide in the separation functional layer.

[0127] The structure of the polymer used in the coating agent preferably has at least one structure selected from the structures represented by the above general formulas (I) to (VI), and more preferably has at least one of the structures represented by the above general formulas (VII) and (VIII).

[0128] The coating agent may contain other components, such as crosslinking agents, to the extent that they do not interfere with the effects of the present invention.

[0129] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited thereto.

[0130] <Interaction Energy> Figure 3 shows a flowchart of the method for calculating interaction energy. The calculation of interaction energy is performed in the following order: target monomer structure modeling step S1, trimer modeling step S2, stable conformation search step S3, structure optimization calculation step S4, charge parameter creation step S5, polymer structure modeling step S6, force field parameter creation step S7, solvation system creation step S8, molecular dynamics calculation step S9, and calculation result analysis step S10.

[0131] [Target monomer structure modeling process S1] The three-dimensional molecular structure of the target monomer for which the interaction energy is calculated was modeled using Winmonster (manufactured by CrossAbility Co., Ltd.).

[0132] [Trimer Modeling Step S2] A trimer model of the target monomer modeled in step S1 was prepared. When the polymer is a copolymer consisting of multiple monomer units, for example, molecules consisting of trimers of monomer units A and / or B, such as AAA, AAB, ABB, ABA, BAA, BAB, BBA, and BBB, were modeled. If monomer unit A is a structure represented by (ab) consisting of structure a and structure b, then ABA becomes "(ab)B(ab)". If a polymer consisting of another monomer unit is incorporated into monomer units A and / or B, and that monomer unit is C, then when modeling a molecule consisting of trimers of monomer units A and / or B, monomer unit C incorporated into monomer units A and / or B was modeled as a trimer. If the number of atoms in the trimers of monomer units A and B exceeds 350, monomer units A and B may be divided at any position so that the number of atoms is 100 or more and less than 300, and then modeled.

[0133] [Stable Conformation Search Process S3] A stable conformation search was performed on the trimer model modeled in process S2 using conformational search (Balloon). This process may be omitted if the stable conformation of the target molecule can be determined from chemical experience.

[0134] [Structural Optimization Calculation Process S4] If necessary, the optimized structure in a vacuum was calculated for the trimer model obtained in the stable conformation search process S3. Specifically, the Cartesian coordinates corresponding to the classical mechanics-level stable conformation of the trimer model were used as input information, and structural optimization calculations were performed using the density functional method with the quantum chemistry calculation program Gaussian16. The calculation method / basis set used was B3LYP / 6-31G(d), and the SCF calculation convergence condition was set to "SCF = tight". The optimized structure obtained in this process will be used to calculate the partial charge on each atom in the next charge parameter creation process S5.

[0135] [Charge Parameter Creation Process S5] The partial charge on each atom in the optimized structure of the trimer model obtained in the structural optimization calculation process S4 was calculated. To calculate the partial charge on each atom in the vacuum optimized structure, the log file output after the structural optimization calculation by Gaussian 16 described above was read, and a single-point calculation using the density functional theory was performed. In this case, the calculation method / basis function was HF / 6-31g*, "geom=allcheck", "guess=read", "pop=mk", and "iop(6 / 41=10, 6 / 42=17, 6 / 50=1)" were added to the root section, and an esp file was output. The output esp file was used as input information, and the antechamber module (antechamber command) included with Amber Tools 16.0 was used to convert the ESP charge to RESP charge. The necessary command references used were "-fi gesp" for reading the esp file, "-c resp" for converting to RESP charge, and "-at gaff2" for indicating the reference force field parameters. If there was force field information not available in the GAFF2 force field, which served as the reference force field, it was supplemented with the Draiding force field. Through these steps, a force field parameter file (top file) and a PDB file for the optimized structure were generated.

[0136] [Polymer Structure Modeling Process S6] Using the "Random Block Polymer" function of Winmonster, a polymer structure was modeled by linking the target monomers together. The partial charges of the polymer structure were assigned from the partial charges of the trimer model calculated in process S5. The modeled structure was output as a mol2 file. The number of atoms in the polymer to be modeled was set to between 350 and 500 atoms. Within this range, the time required for molecular dynamics calculations can be kept within a practical range, and sufficient statistical data can be obtained for the polymer structure. Furthermore, when assigning partial charges, for example, to a polymer consisting of units X, Y, and Z (XXXYYXYZ), the partial charge of the central unit of the trimer model was assigned to the polymer from the partial charges calculated for the trimers XXX, XXY, XYY, YYX, YXY, and XYZ. For the units at both ends of the polymer, the partial charges of the trimer model were assigned directly. The degree of polarization was calculated from the partial charge of the trimers AAA and BBB of monomer units A or B using the following formula: Degree of polarization [e] = -Partial charge of hydrogen bond acceptors in the polymer [e]

[0137] [Force Field Parameter Creation Process S7] A GAFF2 force field was created using acpype in AmberTools 16.0. If there was force field information not available in the reference force field GAFF2 force field, it was supplemented with a Draiding force field. Through the above process, a force field parameter file (top file) and a structure file (PDB file) of the optimized structure were generated. Note that the crosslinked polyamide structure is described in Fig. 1 of Polymer JOURNAL, 2018, vol. 50, pp. 327-336 (C １９５ H １４２ N ３２ O ４０ The same procedure was followed for the following:

[0138] [Solvation System Preparation Process S8] A solvation system was created by placing the target molecule in a cubic virtual space using Packmol, and then placing water molecules around the target molecule within the virtual space. Specifically, box-shaped basic cells (virtual spaces) were prepared with spacing of 12 nm, 12 nm, and 12 nm along the X, Y, and Z axes, respectively. 10,000 water molecules, 1 cross-linked polyamide structure molecule, and 1 target polymer molecule were randomly placed within these virtual spaces. The water model used here was TIP3P. The length of one side of the cube was adjusted to achieve a low density in the solvation system. Furthermore, considering periodic boundary conditions, the space must be sufficiently large relative to the polymer to prevent interaction between adjacent virtual spaces and the polymer.

[0139] [Molecular Dynamics Calculation Process S9] In order to create an equilibrium state of the solvation system under normal temperature and pressure conditions, molecular dynamics calculations were performed in the following order. The total calculation time was set appropriately according to the equilibrium state based on the target molecules. (1) Energy minimization of the solvation system was performed using GROMACS. This calculation aims to minimize energy because if the initial arrangement of the target molecules created in the solvation system creation process S8 is inappropriate, unnaturally high forces may be generated. (2) An NPT ensemble was constructed by controlling the temperature to 600K and the pressure to 1000bar, using the final coordinates obtained in (1) as input information. At this time, the short-range Lennard-Johns interaction was handled by applying a switch function from 1.0 nm and cutting off at 1.2 nm. The long-range electrostatic interaction was calculated using the Particle Mesh Ewald method. Molecular dynamics calculations were performed with a constant pressure and temperature ensemble until the density became constant. The purpose of this calculation is to quickly relax polymers with higher-order structural properties. (3) Using the final coordinates, velocities, and basic cell data obtained in (2) above as input information, a molecular dynamics calculation was performed in the same manner as in (2), except that an NPT ensemble was constructed by controlling the temperature to 300K and the pressure to 1 bar. The purpose of this calculation is to adjust the density of the solvation system to a normal temperature and pressure state. (4) Using the final coordinates, velocities, and basic cell data obtained in (3) above as input information, a molecular dynamics calculation was performed in the same manner as in (3), except that an NVT ensemble was constructed under the condition that the temperature was gradually changed from 300K → 600K → 300K over a molecular dynamics calculation time of 20ns. The purpose of this calculation is to perform an annealing molecular dynamics calculation for temperature after (3) above. (5) Using the final coordinates, velocity, and basic cell data obtained in (4) above as input information, a molecular dynamics calculation was performed in the same manner as in (4), except that an NVT ensemble was constructed under the conditions of temperature 300 K and pressure 1 bar for a molecular dynamics calculation time of 30 ns. The purpose of this calculation is to obtain the equilibrium state of the solvation system under normal temperature and pressure conditions by performing a molecular dynamics calculation under the conditions of temperature 300 K and pressure 1 bar after (4) above.

[0140] [Calculation Result Analysis Process S10] The interaction energy of the solute-solvent pair was calculated by free energy calculation based on the energy representation method for the equilibrium state in step S9 (5) above. Here, "solute" refers to the polymer being calculated, and "solvent" refers to the cross-linked polyamide or water molecule. Specifically, a trajectory file consisting of a total of 200,000 snapshots was generated from the trajectory obtained in step S9 (5) above, starting from the latter 20ns. The obtained snapshots were analyzed using the free energy calculation software ERmod 0.3.5. The files necessary for calculating the energy histogram (SltInfo, MolPrm1, MDinfo, LJTable) were automatically generated by assigning the topology file of the hydration system using the gen_structure command of the ERmod module. The parameter file "parameters_er" for the calculation conditions was automatically generated, and "ecdmin" was manually set to -400. The ermod command, an ERmod module, was used to perform the analysis. The interaction energy between the cross-linked polyamide and the target polymer, and the interaction energy between the water molecule and the target polymer, were calculated by taking the arithmetic mean of the values ​​in the second column (interaction energy between the cross-linked polyamide and the target polymer) and the third column (interaction energy between the water molecule and the target polymer) of the aveuv.tt file obtained by the above analysis. Next, in order to calculate the vdw interaction energy, all values ​​in the third column of SltInfo were set to 0, and the analysis was performed again using the ermod command. The vdw interaction energy between the cross-linked polyamide and the target polymer was calculated by taking the arithmetic mean of the values ​​in the second column (vdw interaction energy between the cross-linked polyamide and the target polymer) of the aveuv.tt file obtained by the above analysis, and dividing by the number of atoms in the modeled polymer. The Coulomb interaction energy was calculated from the difference between the obtained interaction energy and the vdw interaction energy.

[0141] Steps S8 to S10 were repeated 10 times, and the Coulomb interaction energy was calculated from the difference between the obtained interaction energy and the vdw interaction energy. The arithmetic mean of these values ​​was used as the various energies.

[0142] <NaCl Removal Rate> A composite semipermeable membrane was used with evaluation water adjusted to a temperature of 25°C, pH 7.0, and sodium chloride concentration of 34,000 ppm as the supply water, with a membrane permeation flux of 1.0 m. ３ / m ２ The operating pressure was adjusted to 1 / d and the water was supplied, and membrane filtration treatment was performed for 1 hour. After that, the electrical conductivity of the feedwater and permeate was measured using a multi-water quality meter MM60R (manufactured by Toa DKK Co., Ltd.) to obtain the practical salinity, i.e., the NaCl concentration, of each. From the obtained NaCl concentration, the NaCl removal rate was calculated using the following formula. Here, sodium chloride concentration (ppm) means the concentration on a mass basis. NaCl removal rate (%) = 100 × {1 - (NaCl concentration in permeate / NaCl concentration in feedwater)}

[0143] <Membrane Permeation Flux> Evaluation water, adjusted to a temperature of 25°C, pH 7.0, and sodium chloride concentration of 34,000 ppm, was supplied to a composite semipermeable membrane at a pressure of 5.50 MPa, and membrane filtration was performed for 1 hour. The permeate volume (m³) over 20 minutes was then measured. ３ ) was measured, and the unit membrane area (m²) was measured. ２ The values ​​were converted to values ​​per unit time (d) and to calculate the membrane permeation flux (m / d). The membrane permeation flux ratio was defined as the value obtained by dividing the membrane permeation flux after the membrane degradation test by the membrane permeation flux before the membrane degradation test.

[0144] <Membrane Degradation Test> The composite semipermeable membranes of Examples 1 to 7 and Comparative Examples 1 to 6 described later were subjected to the following membrane degradation tests, and the membrane performance before and after the membrane degradation test was evaluated. After sequentially performing the following treatments (i) to (vi) on the composite semipermeable membrane, the NaCl removal rate and membrane permeation flux ratio were calculated using the methods described above for "NaCl removal rate" and "membrane permeation flux". A NaCl removal rate (%) of 98.5% or higher after the membrane degradation test is considered good. Furthermore, a membrane permeation flux ratio of 2.0 or lower in the membrane degradation test is considered good. (i) Immersed in an aqueous sodium hydroxide solution prepared at 25°C and pH 13.0 for 48 hours, then washed with distilled water. (ii) Immersed in sulfuric acid prepared at 25°C and pH 2.0 for 3 hours, then washed with distilled water. (iii) Immersed in a 20 mg / L aqueous sodium hypochlorite solution prepared at 25°C and pH 7.0 for 24 hours. (iv) Immerse in a 1000 mg / L sodium bisulfite aqueous solution at 25°C for 10 minutes, then wash with distilled water. (v) Immerse in a sodium hydroxide aqueous solution prepared to pH 13.0 at 25°C for 48 hours, then wash with distilled water. (vi) Immerse in sulfuric acid prepared to pH 2.0 at 25°C for 3 hours, then wash with distilled water.

[0145] <Immersion Treatment in Hydrogen Peroxide Solution> The composite semipermeable membranes of Example 8 and Comparative Example 7, described later, were subjected to the following immersion treatment in hydrogen peroxide solution, and the membrane performance before and after the treatment was evaluated. The composite semipermeable membrane was immersed in hydrogen peroxide solution at 25°C (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., Wako Grade 1, product code 080-01186) for 72 hours (immersion treatment), and then washed with distilled water. After this immersion treatment, the NaCl removal rate and membrane permeation flux ratio were calculated using the methods described above for "NaCl removal rate" and "membrane permeation flux". The evaluation of chemical resistance to hydrogen peroxide solution was determined by the membrane permeation flux ratio, which is the value obtained by dividing the membrane permeation flux after the immersion treatment by the membrane permeation flux before the immersion treatment. Furthermore, a membrane permeation flux ratio of 1.7 or less in the hydrogen peroxide solution immersion treatment test is considered good.

[0146] <Preparation of Composite Semipermeable Membrane> A porous support layer stock solution was prepared by dissolving 15% by mass of PSf (Udel P-3500, Mw: 80,000, manufactured by Solvay Specialty Polymers Japan Ltd.) and 85% by mass of DMF at 100°C. This porous support layer stock solution was then mixed with a polyester long-fiber nonwoven fabric (thickness 90 μm, density 0.42 g / cm³). ３ The material was applied to the surface of the substrate at 25°C, and after 3 seconds, it was immersed in a solidification solution consisting of distilled water at 25°C for 30 seconds to solidify. Next, a support film was obtained in which a porous support layer was formed on the substrate surface by washing with hot water at 90°C for 2 minutes. The thickness of the porous support layer in the obtained support film was 40 μm. Next, the obtained support film was immersed in a 3 mass% aqueous solution of m-PDA for 2 minutes, and the support film was slowly pulled up vertically, and excess aqueous solution was removed from the surface of the support film by blowing nitrogen from an air nozzle. In an environment controlled at 25°C, 20 ml of decane solution at 25°C containing 0.15 mass% TMC was applied to the surface of the support film so that it was completely wet, and it was left to stand for 1 minute. Next, the film was held vertically for 30 seconds to drain and remove excess solution, and then washed with hot water at 90°C for 2 minutes to obtain composite semipermeable film 1.

[0147] [Example 1] 50 g of ε-caprolactam, 100 g of a salt consisting of N-(2-aminoethyl)piperazine and adipic acid, and 150 g of water were heated to 200°C in a heat-resistant and pressure-resistant container under a nitrogen atmosphere and reacted for 2 hours to obtain polyamide 1. An aqueous solution containing 0.01% by mass of the obtained polyamide 1 was brought into contact with the composite semipermeable membrane 1 and held at 20°C for 5 minutes. After that, the composite semipermeable membrane was held vertically to remove excess aqueous solution, washed with 20°C water for 5 minutes, and a composite semipermeable membrane with a coating layer formed on the separation functional layer was obtained.

[0148] [Example 2] 10 g of ε-caprolactam, 100 g of a salt consisting of polyethylene glycol with a number-average molecular weight of 600 having amino groups at both ends (hereinafter referred to as "α,ω-diaminopolyoxyethylene", n=13-14) and terephthalic acid, and 300 g of water were heated to 200°C in a heat-resistant and pressure-resistant container under a nitrogen atmosphere and reacted for 2 hours to obtain polyamide 2. A composite semipermeable film was obtained by forming a coating layer in the same manner as in Example 1, except that polyamide 2 was used.

[0149] [Example 3] 10 g of p-aminobenzoic acid, 100 g of a salt consisting of α,ω-diaminopolyoxyethylene and terephthalic acid, and 300 g of water were heated to 200°C in a heat-resistant and pressure-resistant container under a nitrogen atmosphere and reacted for 2 hours to obtain polyamide 3. A composite semipermeable film was obtained by forming a coating layer in the same manner as in Example 1, except that polyamide 3 was used.

[0150] [Example 4] 100 g of a salt consisting of α,ω-diaminopolyoxyethylene and adipic acid and 100 g of water were heated to 200°C in a heat-resistant and pressure-resistant container under a nitrogen atmosphere and reacted for 2 hours to obtain polyamide 4. A composite semipermeable film was obtained by forming a coating layer in the same manner as in Example 1, except that polyamide 4 was used.

[0151] [Example 5] 30 g of ε-caprolactam, 100 g of a salt consisting of α,ω-diaminopolyoxyethylene and oxalic acid, and 130 g of water were heated to 200°C in a heat-resistant and pressure-resistant container under a nitrogen atmosphere and reacted for 2 hours to obtain polyamide 5. A composite semipermeable film was obtained by forming a coating layer in the same manner as in Example 1, except that polyamide 5 was used.

[0152] [Example 6] 10 g of α,ω-diaminopolyoxyethylene and 0.6 g of ethylenediamine were dissolved in 100 g of tetrahydrofuran, then 1.1 g of hexamethylene diisocyanate was added, and the mixture was reacted at room temperature under a nitrogen atmosphere for 2 hours to obtain polyurea 1. A composite semipermeable membrane was obtained by forming a coating layer in the same manner as in Example 1, except that polyurea 1 was used.

[0153] [Example 7] 10 g of α,ω-diaminopolyoxyethylene was dissolved in 100 g of tetrahydrofuran, then 2.8 g of hexamethylene diisocyanate was added, and the mixture was reacted at room temperature under a nitrogen atmosphere for 2 hours to obtain polyurea 2. A composite semipermeable membrane was obtained by forming a coating layer in the same manner as in Example 1, except that polyurea 2 was used.

[0154] [Comparative Example 1] A composite semipermeable film was obtained by forming a coating layer in the same manner as in Example 1, except that polyethylene glycol (PEG) (Mw: 8,000,000) was used instead of polyamide 1.

[0155] [Comparative Example 2] A composite semipermeable film was obtained by forming a coating layer in the same manner as in Example 1, except that "Pluronic" (registered trademark, F-68, manufactured by Sigma-Aldrich) was used instead of polyamide 1.

[0156] [Comparative Example 3] An aqueous solution containing 2.0% by mass of ethylene-vinyl alcohol copolymer (Exceval RS-1717, manufactured by Kuraray Co., Ltd.), 0.5% by mass of glutaraldehyde, and 0.1% by mass of sulfuric acid was brought into contact with the entire surface of the composite semipermeable membrane 1. With the aqueous solution remaining on the surface of the separation functional layer, a composite semipermeable membrane was obtained by blowing 70°C hot air onto the composite semipermeable membrane for 3 minutes to form a coating layer on the separation functional layer.

[0157] [Comparative Example 4] A composite semipermeable film was obtained by forming a coating layer in the same manner as in Example 1, except that poly(2-ethyl-2-oxazoline) (hereinafter referred to as "PEOX", manufactured by Sigma-Aldrich) (Mw: 500,000) was used instead of polyamide 1.

[0158] [Comparative Example 5] A composite semipermeable film was obtained by forming a coating layer in the same manner as in Example 1, except that PEOX having poly(ethylene oxide) diglycidyl ether (PEGDE) was used instead of polyamide 1.

[0159] [Comparative Example 6] A polymer solution was prepared by dissolving 4-(4,6-dimethoxy-1,3,5-triazine-2-yl)-4-methylmorpholinium chloride as a condensing agent to a concentration of 1% by mass in 3% by mass of Jeffamine (ED-2003, manufactured by Sigma-Aldrich) and 1% by mass of octafluoroadipic acid, and stirring at 25°C for 24 hours. The polymer solution was separated and purified by gel permeation chromatography to remove components with a dextran equivalent molecular weight of 5000 or less. The obtained polymer was dissolved in pure water to a concentration of 4000 ppm, and the condensing agent was further dissolved to a concentration of 1000 ppm. This was then applied to the separation functional layer side surface of composite semipermeable membrane 1, allowed to stand at 25°C for 10 minutes, and then washed with pure water to prepare a composite semipermeable membrane with a coated layer.

[0160] [Example 8] The composite semipermeable membrane obtained in Example 1 was subjected to immersion treatment in hydrogen peroxide solution.

[0161] [Comparative Example 7] The composite semipermeable membrane obtained in Comparative Example 1 was subjected to immersion treatment in hydrogen peroxide solution.

[0162] Tables 1 to 4 show the structure, interaction energy, and performance of the composite semipermeable membranes of each polymer used in the examples and comparative examples. In Table 1, monomer unit A corresponds to a hydrophilic unit, and monomer unit B corresponds to a hydrophobic unit.

[0163]

[0164]

[0165]

[0166]

[0167] As shown in Tables 1 to 4, the composite semipermeable membrane according to this embodiment exhibits excellent chemical resistance.

[0168] The composite semipermeable membrane of the present invention can be used for seawater desalination, brine desalination, drinking water production, industrial ultrapure water production, wastewater treatment, and recovery of valuable materials.

[0169] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2024-229609, filed on 26 December 2024, the contents of which are incorporated herein by reference.

[0170] 1. Composite semipermeable membrane 2. Support membrane 3. Separation functional layer 4. Coating layer 5. Composite semipermeable membrane element 6. End plate 7. End plate 8. Supply side channel material 9. Permeation side channel material 10. Water collection pipe 11. Supply water 12. Permeate water 13. Concentrated water

Claims

1. A composite semipermeable membrane comprising: a porous support layer; a separation function layer provided on the porous support layer; and a coating layer provided on the separation function layer, wherein the separation function layer mainly contains a crosslinked polyamide; the coating layer contains a polymer having hydrogen bond acceptors; and the interaction energy between the polymer and the crosslinked polyamide is between -700 cal / mol / atom and -400 cal / mol / atom.

2. The composite semipermeable membrane according to claim 1, wherein the van der Waals interaction energy between the polymer and the crosslinked polyamide is between -450 cal / mol / atom and -150 cal / mol / atom.

3. The composite semipermeable membrane according to claim 1 or 2, wherein the Coulomb interaction energy between the polymer and the crosslinked polyamide is -300 cal / mol / atom or more and -150 cal / mol / atom or less.

4. The composite semipermeable membrane according to claim 1 or 2, wherein the interaction energy between the polymer and water molecules is -2000 cal / mol / atom or more and -1000 cal / mol / atom or less.

5. The composite semipermeable membrane according to claim 1 or 2, wherein the crosslinked polyamide is a crosslinked aromatic polyamide.

6. The composite semipermeable film according to claim 5, wherein the polymer consists only of non-halogen atoms.

7. The composite semipermeable membrane according to claim 5, wherein the polymer comprises monomer units having hydrogen bond acceptors with a polarization degree of 0.68e or more and 1.00e or less.

8. The composite semipermeable membrane according to claim 5, wherein the polymer is nonionic.

9. The composite semipermeable membrane according to claim 5, wherein the polymer has a structure represented by the following general formula (I). [In general formula (I), R in the repeating unit] １ and R ２ Each of these is independently either hydrogen or a hydrocarbon group having 2 or fewer carbon atoms, and n is an integer of 5 or more.

10. The composite semipermeable membrane according to claim 9, wherein the polymer comprises monomer units having hydrocarbon groups with 4 to 12 carbon atoms in the main chain.

11. The composite semipermeable membrane according to claim 9, wherein the polymer contains monomer units having at least one structure selected from the group consisting of structures represented by the following general formulas (II) to (VI). [In general formulas (II) to (VI), R ３ , R ４ , R ７ , R ９ and R １０ are each independently a hydrocarbon group having 4 to 12 carbon atoms which may be substituted, and R ５ , R ６ and R ８ are each independently hydrogen, a hydrocarbon group having 2 or fewer carbon atoms, or a functional group having 2 or fewer carbon atoms. ] 12. The composite semipermeable membrane according to claim 10, wherein the hydrogen bond acceptor is a functional group having a carbonyl group.

13. The composite semipermeable membrane according to claim 10, wherein the polymer is a copolymer and comprises at least one of the structures represented by the following general formulas (VII) and (VIII). [In general formulas (VII) and (VIII), R １１ , R １２ , R １４ , R １６ , R １７ , R １８ , R ２０ , R ２１ , R ２３ , R ２４ and R ２６ Each is independently a hydrogen atom or a hydrocarbon group having 2 or fewer carbon atoms or a functional group having 2 or fewer carbon atoms, R １３ and R １５ Each of these is a hydrocarbon group having 4 to 12 carbon atoms, which may be independently substituted, and R １９ , R ２２ , R ２５ is a hydrocarbon group having 2 to 12 carbon atoms, which may be substituted; X is a structure containing the general formula (I); and r, q, y, and z are each independently integers of 5 or more.

14. A composite semipermeable membrane element comprising the composite semipermeable membrane described in claim 1 or 2.

15. A fluid separation apparatus comprising a composite semipermeable membrane according to claim 1 or 2.

16. A coating agent for a composite semipermeable membrane comprising a porous support layer and a separation functional layer provided on the porous support layer and mainly containing a crosslinked polyamide, wherein the coating agent contains a polymer whose interaction energy with the crosslinked polyamide is -700 cal / mol / atom or more and -400 cal / mol / atom or less.

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