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

Abstract

To provide a composite semipermeable film with good oxidation resistance, acid resistance, and alkali resistance. [Solution] A composite semipermeable membrane comprising a porous support layer, a separation functional layer containing polyamide provided on the porous support layer, and a coating layer provided on the separation functional layer, wherein the coating layer contains a copolymer of hydrophilic units and hydrophobic units having hydrogen bond acceptors with a polarization degree of 0.70e or more and 1.00e or less.

Description

[Technical Field]

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

[0002] There are various techniques for removing substances (e.g., salts) dissolved in a solvent (e.g., water), but 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 documents 1 and 2 disclose a method for forming a protective layer on the surface of a separation functional layer as a means to prevent amide bond cleavage. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2024 / 162434 [Non-patent literature]

[0007] [Non-Patent Document 1] Progress in Polymer Science,2017,Vol.72,p.1-15 [Non-Patent Document 2] JOURNAL of Membrane Science,2016,501,p.209-219 [Overview of the project] [Problems that the invention aims to solve]

[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. [Means for solving the problem]

[0010] To achieve the above objectives, the present invention includes the following configurations [1] to

[18] . [1] A composite semipermeable membrane comprising a porous support layer, a separation functional layer containing polyamide provided on the porous support layer, and a coating layer provided on the separation functional layer, wherein the coating layer contains a copolymer of hydrophilic units and hydrophobic units having hydrogen bond acceptors with a polarization degree of 0.70e or more and 1.00e or less. [2] The composite semipermeable membrane according to [1] above, wherein the hydrophilic unit has hydrogen bond acceptors with a polarization degree of 0.58e or more and 1.00e or less. [3] The composite semipermeable membrane according to [1] or [2] above, wherein the copolymer is nonionic. [4] The composite semipermeable membrane according to any one of [1] to [3] above, wherein the hydrophobic unit has a carbon chain with 4 or more carbon atoms in its main chain. [5] The composite semipermeable membrane according to [4] above, wherein the hydrophobic unit has a structure represented by the following general formula (I).

[0011] [ka]

[0012] [In general formula (I), R1 is a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted, and R2 is hydrogen, a hydrocarbon group having 2 or fewer carbon atoms, or a functional group having 2 or fewer carbon atoms.] [6] A composite semipermeable membrane according to any one of [1] to [5] above, wherein the copolymer consists only of non-halogen atoms. [7] A composite semipermeable membrane according to any of [1] to [6] above, wherein the hydrophilic unit has a structure represented by the following general formula (II).

[0013] [ka]

[0014] [In general formula (II), R3 and R4 in each repeating unit are independently hydrogen or a hydrocarbon group having 2 or fewer carbon atoms, and n is an integer of 1 or more.] [8] The composite semipermeable membrane according to any one of [1] to [7] above, wherein the hydrophilic unit has a carbon chain with 4 to 11 carbon atoms in its main chain. [9] A composite semipermeable membrane according to any of [1] to [8] above, wherein the hydrophilic unit has a structure represented by the following general formula (III).

[0015] [ka]

[0016] [In general formula (III), R5 is an optionally substituted hydrocarbon group having 4 to 11 carbon atoms.]

[10] The composite semipermeable membrane according to any one of [1] to [9] above, wherein the copolymer has a structure represented by the following general formula (V).

[0017] [Chemical formula]

[0018] [In general formula (V), R1 and R5 are each independently an optionally substituted hydrocarbon group having 4 to 11 carbon atoms, R2, R6 and R7 are each independently hydrogen or a hydrocarbon group having 2 or less carbon atoms or a functional group having 2 or less carbon atoms, X is a structure containing the above general formula (II), and r and q are each independently an integer of 1 or more.]

[11] In the surface analysis of the coating layer side by total reflection infrared absorption measurement, 1642 to 1662 cm , -1 , , 80% , , -1 , 80% , , -1 , -1 , , 80% , 80% ,

[0018] , -1 , , -1 there is a peak derived from amide I, and with respect to the maximum intensity of the peak derived from amide I, the width w of the wave number at which the peak intensity is 80% 80% is 35.8 cm -1 or more and 38.0 cm -1 or less, the composite semipermeable membrane according to any one of [1] to

[10] above.

[12] w of the composite semipermeable membrane after immersion treatment in chlorine, alkali and acid 80% and w of the composite semipermeable membrane before immersion treatment 80% The change width w of the difference between 80% is 2.0 cm -1 or less, the composite semipermeable membrane according to any one of [1] to

[11] above.

[13] In the surface analysis of the coating layer side by total reflection infrared absorption measurement, with respect to the peak area A of 1630 to 1710 cm -1 2800 to 3000 cm -1A composite semipermeable membrane according to any of the above [1] to

[12] , wherein the ratio of peak area B to A is 0.60 or more and 0.85 or less.

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

[13] above, wherein the degree of yellowing ΔDYI of the surface on the coating layer side before and after contact with Dragendorff's reagent is 43 or more and 150 or less.

[15] A composite semipermeable membrane element comprising a composite semipermeable membrane as described in any of [1] to

[14] above.

[16] A fluid separation device comprising a composite semipermeable membrane as described in any of [1] to

[14] above.

[17] A fluid separation device for use in ZLD or precision industry, comprising a composite semipermeable membrane as described in any of [1] to

[14] above.

[18] A coating agent for a composite semipermeable membrane comprising a polyamide in the separation functional layer, comprising a copolymer having a structure represented by the following general formulas (I) to (III).

[0019] [ka]

[0020] [In general formula (I), R1 is a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted, and R2 is hydrogen or a hydrocarbon group having 2 or fewer carbon atoms or a functional group having 2 or fewer carbon atoms. In general formula (II), R3 and R4 in each repeating unit are independently hydrogen or a hydrocarbon group having 2 or fewer carbon atoms, and n is an integer of 1 or more. In general formula (III), R5 is a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted.] [Effects of the Invention]

[0021] According to the present invention, it is possible to provide a composite semipermeable film with good oxidation resistance, acid resistance, and alkali resistance. [Brief explanation of the drawing]

[0022] [Figure 1] Figure 1 is a cross-sectional view of a composite semipermeable film according to one embodiment of the present invention. [Figure 2]Figure 2 is a schematic diagram showing the 80% peak obtained by surface analysis of the coating layer side by total internal reflection infrared absorption measurement in a composite semipermeable film according to one embodiment of the present invention. [Figure 3] Figure 3 is a schematic diagram showing the structure of a composite semipermeable membrane having a pleated separation functional layer and a coating layer according to one embodiment of the present invention, where (a) is a partially enlarged view and (b) is an enlarged view of Y in (a). [Figure 4] Figure 4 is an unfolded view of a composite semipermeable membrane element according to one embodiment of the present invention. [Figure 5] Figure 5 is a schematic diagram of the abrasion test. [Figure 6] Figure 6 is a schematic diagram illustrating the method of setting up the composite semipermeable membrane in the abrasion test. [Modes for carrying out the invention]

[0023] 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.

[0024] 1.Composite semipermeable membrane Figure 1 shows a cross-sectional view of a composite semipermeable membrane 1 according to 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.

[0025] 1.1 Covering layer The coating layer of the composite semipermeable membrane of this embodiment is a layer responsible for protecting the separation functional layer and is arranged on the separation functional layer. The coating layer in this embodiment is a polymer formed from two or more monomers (hereinafter also referred to as "monomer units") and includes a copolymer of hydrophilic units and hydrophobic units having hydrogen bond acceptors with a polarization degree of 0.70e to 1.00e. A monomer unit is a part derived from individual monomers within a copolymer. In other words, monomer units are units that can be linked to each other, and the linked molecules become polymers. The copolymer included in the coating layer may be a random copolymer, an alternating copolymer, or a block copolymer, and among these, a random copolymer, which is widely produced industrially, is preferred. In this specification, a structure in which a polymer consisting of one monomer unit is crosslinked with another polymer via the functional groups of its side chain is not considered a copolymer. In this specification, "polymer" means a structure in which the main chains are linked together.

[0026] A "hydrophilic unit" refers to a monomer unit from which a single polymer (weight-average molecular weight: 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.

[0027] A "hydrophobic unit" refers to a monomer unit from which a single polymer (weight-average molecular weight: 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. In other words, if the copolymer contained in the coating layer is represented as AB with A and B as monomer units, then one of the polymers consisting only of A or the polymer consisting only of B will have water solubility, while the other will not.

[0028] The hydrophobic units of the copolymer contained in the coating layer have hydrogen bond acceptors with a polarization degree of 0.70e or more and 1.00e or less. Here, "polarization degree" as used herein refers to the partial charge of an atom calculated by quantum mechanical calculation, and means the partial charge of the atom with the highest polarization degree among the hydrogen bond acceptors contained in the hydrophilic and hydrophobic units. The polarization degree is calculated by the method described in "Calculation of Polarization Degree" in the examples described later.

[0029] Hydrogen bond acceptors form hydrogen bonds with the hydrogen atoms of the amide and amino groups of the polyamide contained in the separation functional layer. Therefore, if the polarization degree of the hydrogen bond acceptors of the hydrophobic unit is 0.70e or higher, the copolymer in the coating layer can form strong hydrogen bonds with the polyamide contained in the separation functional layer, resulting in a composite semipermeable membrane with high chemical resistance. If the polarization degree is 1.00e or lower, it becomes a highly polarized hydrogen bond acceptor that is less likely to become charged. If the hydrogen bond acceptors become charged due to changes in pH, the copolymer contained in the coating layer becomes an ionic polymer, and the interaction between the coating layer and the crosslinked polyamide weakens due to changes in pH. From the above viewpoint, the polarization degree of the hydrogen bond acceptors of the hydrophobic unit is more preferably 0.75e or higher and 1.00e or lower, and more preferably 0.75e or higher and 0.95e or lower.

[0030] Examples of hydrogen bond acceptors include carboxyl groups, aldehyde groups, ester groups, amide groups, imide groups, isocyanate groups, urethane groups, urea groups, and other carbonyl groups, as well as hydroxyl groups, ether groups, thiol groups, amino groups, nitro groups, imine groups, cyano groups, thioether groups, sulfoxide groups, sulfonic acid groups, phosphonic acid groups, and phosphoryl groups. The degree of polarization of these functional groups may change depending on the surrounding structure, such as the presence of other functional groups. Furthermore, hydrophobic interactions occur between the hydrophobic portion of the hydrophobic unit and the polyamide, improving the chemical resistance of the composite semipermeable membrane. When the copolymer contained in the coating layer has two or more different hydrophobic units, it is sufficient for at least one hydrophobic unit to have a hydrogen bond acceptor with a degree of polarization of 0.70e to 1.00e, and it is more preferable for all hydrophobic units to have a hydrogen bond acceptor with a degree of polarization of 0.70e to 1.00e.

[0031] The copolymer 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 copolymer, 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, the hydrogen bond acceptors are preferably aldehyde groups, ester groups, amide groups, urethane 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 copolymer contained in the coating layer is nonionic, the copolymer does not dissociate into ions during chemical washing with water, acid, or alkali, and the copolymers are not affected by ionic repulsion with each other, thus suppressing peeling of the coating layer. By suppressing the peeling of the coating layer, the interaction between the copolymer and polyamide contained in the coating layer is maintained even in acidic and alkaline solutions, thereby improving the chemical resistance of the composite semipermeable film.

[0032] The hydrophilic units of the copolymer contained in the coating layer of the composite semipermeable membrane according to this embodiment preferably have hydrogen bond acceptors with a polarization degree of 0.58e or more and 1.00e or less. Examples of hydrogen bond acceptors with a polarization degree of 0.58e or more and 1.00e or less include functional groups having carbonyl groups such as carboxyl groups, aldehyde groups, ester groups, amide groups, urethane groups, and urea groups, as well as nitro groups, phosphoryl groups, sulfo groups, sulfoxy groups, isocyanate groups, ether groups, hydroxyl groups, and amino groups. The polarization degree of these functional groups may change depending on the surrounding structure, such as the presence of other functional groups.

[0033] The presence of hydrogen bond acceptors with a polarization degree of 0.58e to 1.00e in the hydrophilic units allows the copolymer to form strong hydrogen bonds with the polyamide, thereby improving the chemical resistance of the composite semipermeable membrane. From this viewpoint, the polarization degree of the hydrogen bond acceptors in the hydrophilic units is more preferably 0.60e to 1.00e, even more preferably 0.65e to 1.00e, even more preferably 0.70e to 1.00e, and particularly preferably 0.75e to 1.00e. If the copolymer contained in the coating layer has two or more different hydrophilic units, it is sufficient that at least one hydrophilic unit has hydrogen bond acceptors with a polarization degree of 0.58e to 1.00e, and it is more preferable that all hydrophilic units have hydrogen bond acceptors with a polarization degree of 0.58e to 1.00e.

[0034] In this embodiment, the hydrophobic units of the copolymer contained in the coating layer of the composite semipermeable membrane preferably have carbon chains with 4 or more carbon atoms in their main chain. A carbon chain is a part composed of multiple carbon atoms and hydrogen atoms, and may be optionally substituted with functional groups such as hydroxyl groups. When the carbon chain has 4 or more carbon atoms, a strong hydrophobic interaction acts between the copolymer and the polyamide, improving the chemical resistance of the composite semipermeable membrane. Furthermore, it is preferable that the carbon chain has 11 or fewer carbon atoms. When the carbon chain has 11 or fewer carbon atoms, the solubility of the copolymer in water-soluble solvents increases, making it possible to form a coating layer by contacting a water-soluble solvent containing the copolymer that forms the coating layer on the separation functional layer. The carbon chain may be linear or cyclic, and may have unsaturated bonds. If the copolymer contained in the coating layer has two or more different hydrophobic units, it is sufficient that at least one hydrophobic unit has carbon chains with 4 or more carbon atoms in its main chain, and it is more preferable that all hydrophobic units have carbon chains with 4 or more carbon atoms in their main chain.

[0035] Examples of carbon chains with 4 to 11 carbon atoms include butylene groups (-C4H8-) and pentylene groups (-C5H8-). 10 -), hexylene group (-C6H 12 -), heptylene group (-C7H 14 -), octylene group (-C8H 16 -), nonylene group (-C9H 18 -), decilen group (-C 10 H 20 -), undecylene group (-C 11 H 22 -), dodecylene group (-C 12 H 24 Hydrocarbons such as -), butenylene group (-C4H6-), pentenylene group (-C5H8-), hexenylene group (-C6H 10 Hydrocarbons having unsaturated structures such as -), cyclobutylene group (-C4H6-), cyclopentylene group (-C5H8-), cyclohexylene group (-C6H 10Examples include cyclic hydrocarbons such as (-) and aromatic hydrocarbons such as phenylene groups (-C6H4-). These carbon chains may be optionally substituted. In particular, carbon chains may include butylene groups (-C4H8-) and pentylene groups (-C5H 10 -), hexylene group (-C6H 12 -), a phenylene group (-C6H4-) is more preferred.

[0036] Furthermore, the hydrophobic unit preferably has a structure represented by the following general formula (I).

[0037] [ka]

[0038] In general formula (I), R1 is a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted, and R2 is hydrogen, a hydrocarbon group having 2 or fewer carbon atoms, or a functional group having 2 or fewer carbon atoms.

[0039] When the hydrophobic unit has a structure represented by the general formula (I) above, the hydrocarbon group represented by R1 corresponds to a hydrogen bond acceptor with a polarization degree of 0.70e to 1.00e, where the carbonyl portion of the carbon amide group is a carbon chain with 4 or more carbon atoms as described above. Therefore, hydrogen bonds are formed between the copolymer contained in the coating layer and the crosslinked polyamide, and hydrophobic interactions originating from the hydrocarbon group result in a composite semipermeable membrane with excellent chemical resistance. If the number of carbon atoms in R1 in general formula (I) is 4 or more, sufficient hydrophobic interactions are at work, and if the number of carbon atoms is 11 or less, the decrease in membrane permeation flux due to hydrophobicity can be suppressed. The number of carbon atoms in R1 in general formula (I) is preferably 4 to 10, more preferably 4 to 8, and even more preferably 4 to 6. R2 in general formula (I) is preferably hydrogen, a hydrocarbon group such as a methyl group or ethyl group, or a functional group such as a methoxymethyl group, and more preferably hydrogen. If R2 is any of the above, it is possible to suppress the inhibition of the interaction between the copolymer contained in the coating layer and the crosslinked polyamide due to steric hindrance. Furthermore, if the copolymer contained in the coating layer has two or more different hydrophobic units, it is sufficient that at least one hydrophobic unit has the structure represented by the general formula (I), and it is more preferable that all hydrophobic units have the structure represented by the general formula (I). It is even more preferable that the hydrophobic units have the structure represented by the general formula (I).

[0040] The hydrophilic unit of the copolymer contained in the coating layer of the composite semipermeable membrane according to this embodiment preferably has a structure represented by the following general formula (II).

[0041] [ka]

[0042] In general formula (II), R3 and R4 in each repeating unit are independently hydrogen or a hydrocarbon group having 2 or fewer carbon atoms, and n is an integer of 1 or more.

[0043] Since the polarization of the ether group in the structure represented by the above general formula (II) is 0.58e or more and 1.00e or less, copolymers in which the hydrophilic unit has the structure represented by the above general formula (II) are soluble in water-soluble solvents, and the copolymer and polyamide contained in the coating layer can form hydrogen bonds. From the viewpoint of the solubility of the copolymer in water-soluble solvents and the formation of hydrogen bonds between the hydrophilic unit in the copolymer and the polyamide, and the function of hydrophobic interactions, R3 and R4 are preferably hydrogen or methyl groups. Furthermore, from the viewpoint of the solubility of the copolymer in water-soluble solvents, n is preferably an integer between 5 and 500, more preferably an integer between 5 and 300, and even more preferably an integer between 10 and 250.

[0044] The hydrophilic unit preferably has a carbon chain with 4 to 11 carbon atoms in its main chain. When the carbon chain has 4 or more carbon atoms, a strong hydrophobic interaction acts between the copolymer and the polyamide, improving the chemical resistance of the composite semipermeable membrane. Furthermore, when the carbon chain has 11 or fewer carbon atoms, the copolymer's solubility in water-soluble solvents increases, making it possible to form a coating layer by contacting a water-soluble solvent containing the copolymer that forms the coating layer onto the separation functional layer. The carbon chain may be linear or cyclic, and may have unsaturated bonds.

[0045] Furthermore, the hydrophilic unit may also have a structure represented by the following general formula (III). Specifically, the hydrophilic unit may have a structure represented by general formula (III) and preferably have a hydrocarbon group with 4 to 11 carbon atoms as a carbon chain in the main chain.

[0046] [ka]

[0047] In general formula (III), R5 is a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted.

[0048] The hydrophilic unit has a structure represented by the above general formula (III), which allows for the formation of strong hydrogen bonds between the copolymer having highly polarizable carbonyl groups and the polyamide.

[0049] The number of carbon atoms in the hydrocarbon group R5 is preferably 4 to 10, more preferably 4 to 8, and even more preferably 4 to 6. When R5 is a hydrocarbon group with 4 to 11 carbon atoms, hydrophobic interactions occur between the hydrophilic units in the copolymer and the polyamide. Preferred structures for R5 include, for example, a butylene group (-C4H8-) and a pentylene group (-C5H8-). 10 -), hexylene group (-C6H 12 -), heptylene group (-C7H 14 -), octylene group (-C8H 16 -), nonylene group (-C9H 18 -), decilen group (-C 10 H 20 Hydrocarbon groups such as -), butenylene group (-C4H6-), pentenylene group (-C5H8-), hexenylene group (-C6H 10 Hydrocarbons having unsaturated structures such as -), cyclobutylene group (-C4H6-), cyclopentylene group (-C5H8-), cyclohexylene group (-C6H 10 Examples include cyclic hydrocarbons such as (-) and aromatic hydrocarbons such as phenylene groups (-C6H4-). These carbon chains may be substituted with any functional group, such as a hydroxyl group. In particular, R5 can be a butylene group (-C4H8-) or a pentylene group (-C5H 10 -), hexylene group (-C6H 12 -), a phenylene group (-C6H4-) is more preferred.

[0050] Furthermore, it is even more preferable that the hydrophilic unit has a structure represented by the following general formula (IV).

[0051] [ka]

[0052] In general formula (IV), X is a structure containing general formula (II), R5 is a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted, and R6 and R7 are each independently hydrogen, a hydrocarbon group having 2 or fewer carbon atoms, or a functional group having 2 or fewer carbon atoms. The preferred number of carbon atoms and specific examples of the hydrocarbon group R5 are as described above for general formula (III). R6 and R7 are preferably hydrogen or a hydrocarbon group with 1 carbon atom, and more preferably hydrogen, because they have good interaction with the amide group of the crosslinked polyamide of the separation functional layer and thus have less steric hindrance.

[0053] When the hydrophilic unit has the structure represented by the general formula (IV) above, strong hydrogen bonds are formed between the hydrophilic unit in the copolymer and the polyamide, and strong hydrophobic interactions are at work, resulting in a composite semipermeable film with excellent chemical resistance. If the copolymer contained in the coating layer has two or more different hydrophilic units, it is sufficient that at least one hydrophilic unit has the structure of the general formula (IV), and it is more preferable that all hydrophilic units have the structure of the general formula (IV).

[0054] The copolymer contained in the coating layer of the composite semipermeable membrane according to this embodiment preferably has a structure represented by the following general formula (V).

[0055] [ka]

[0056] In general formula (V), R1 and R5 are each independently substituted hydrocarbon groups having 4 to 11 carbon atoms, R2, R6, and R7 are each independently hydrogen or hydrocarbon groups having 2 or fewer carbon atoms or functional groups having 2 or fewer carbon atoms, X is a structure containing the above general formula (II), and r and q are each independently integers of 1 or more. The preferred forms of R1 and R2 are as described above with respect to the general formula (I). The preferred form of R5 is as described above with respect to the general formula (III). The preferred forms of R6 and R7 are as described above with respect to the general formula (IV).

[0057] In other words, the above general formula (V) is a copolymer of a hydrophilic unit having the structure represented by the above general formula (IV) and a hydrophobic unit having the structure represented by the above general formula (I). Note that different hydrophilic and hydrophobic units may be copolymerized within a range that does not impede the effects of the present invention. When the copolymer contained in the coating layer has the structure represented by general formula (V), both the hydrophilic and hydrophobic units in the copolymer form strong hydrogen bonds with the crosslinked polyamide, and hydrophobic interactions are at work, resulting in a composite semipermeable film with high chemical resistance.

[0058] In this embodiment, the coating layer of the composite semipermeable membrane is preferably immobilized so that it does not leach out when the composite semipermeable membrane is used. Examples of methods for immobilizing the coating layer include forming non-covalent bonds such as hydrogen bonds and ionic bonds between the coating layer and the polyamide and immobilizing it on the separation functional layer, forming covalent bonds between the polyamide and a crosslinking agent and immobilizing it on the separation functional layer, and forming covalent bonds between the coating layers and 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.

[0059] The copolymer 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 position near hydrogen bond acceptors affects the degree of polarization. Furthermore, halogen atoms hydrolyze in water, releasing halogen atoms into the water, which raises concerns about water pollution.

[0060] In the coating layer of the composite semipermeable membrane according to this embodiment, the proportion of copolymers of hydrophilic units and hydrophobic units having hydrogen bond acceptors with a polarization degree of 0.70e to 1.00e is preferably 1% by mass or more, more preferably 20% by mass or more, and even more preferably 50% by mass or more. It is particularly preferable that the coating layer be formed solely of copolymers of hydrophilic units and hydrophobic units having hydrogen bond acceptors with a polarization degree of 0.70e to 1.00e. When the proportion of copolymers of hydrophilic units and hydrophobic units having hydrogen bond acceptors with a polarization degree of 0.70e to 1.00e in the coating layer is 1% by mass or more, a composite semipermeable membrane with good oxidation resistance, acid resistance, and alkali resistance can be obtained.

[0061] The degree of polymerization of the copolymer 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 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.

[0062] In the coating layer of the composite semipermeable membrane according to this embodiment, the copolymer preferably has a mass ratio of hydrophilic units to hydrophobic units of 1 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 1 or more, a decrease in the 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 less, a strong hydrophobic interaction acts between the copolymer and the polyamide contained in the coating layer, 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.

[0063] The copolymer 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 copolymer being water-soluble or soluble in water-soluble solvents, a coating layer containing the copolymer 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.

[0064] In the composite semipermeable membrane according to this embodiment, the sum of the thicknesses of the separation functional layer and the coating layer is preferably 10 nm or more and 100 nm or less, more preferably 11 nm or more and 70 nm or less, and even more preferably 11 nm or more and 50 nm or less. When the sum of the thicknesses 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 sum of the thicknesses 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 sum of the thicknesses of the separation functional layer and the coating layer can be measured by observing the composite semipermeable membrane with a scanning transmission electron microscope.

[0065] The presence of the copolymer in the coating layer of a composite semipermeable membrane can be confirmed, for example, by analyzing the surface of the separation functional layer of the composite semipermeable membrane using time-of-flight secondary ion mass spectrometry, X-ray photoelectron spectroscopy, Raman spectroscopy, or infrared spectroscopy. This allows for the detection of characteristic peaks such as amide groups present in the copolymer contained in the coating layer. Furthermore, the structure of the copolymer can be identified by extracting only the coating layer and analyzing it using nuclear magnetic resonance spectroscopy, liquid chromatography-mass spectrometry, or gas chromatography-mass spectrometry.

[0066] In surface analysis of the coating layer side of the composite semipermeable film according to this embodiment, the absorption rate was 1642-1662 cm² in total internal reflection infrared absorption spectroscopy (hereinafter referred to as "ATR-IR"). -1 It is preferable that a peak originating from amide I (hereinafter also referred to as the "amide I peak") is present.

[0067] The "peak originating from amide I" refers to the peak originating from the C=O stretching of the amide bond, and is typically found in the ATR-IR spectrum under an atmosphere adjusted to 20°C and 50% RH, at 1630–1670 cm⁻¹. -1 This is a peak detected between 1664 cm² and 1664 cm². -1 A peak is detected in the vicinity.

[0068] In the composite semipermeable membrane according to this embodiment, the peak for amide I originates from the amide group of the polyamide contained in the separation functional layer. The position of this amide I peak shifts to the lower wavenumber side due to the formation of hydrogen bonds between the copolymer contained in the coating layer and the amide group of the separation functional layer.

[0069] In surface analysis of the coating layer using ATR-IR, the position of the peak originating from amide I was 1642 cm². -1 The above is 1662cm. -1 The following is preferable: 1645cm -1 The above is 1662cm. -1 More preferably, the following: 1648cm -1 The above is 1662cm. -1 It is even more preferable that the peak position of amide I is 1662 cm. -1 Under the following conditions, the amide bonds between the copolymer in the coating layer and the polyamide in the separation functional layer form hydrogen bonds, resulting in good chemical resistance. Furthermore, the peak position of amide I is 1642 cm⁻¹. -1 As described above, the formation of excessive hydrogen bonds between the copolymer contained in the coating layer and the polyamide contained in the separation functional layer is suppressed, and a good membrane permeation flux is obtained. Here, the peak position of amide I is defined as the wavenumber that shows the maximum intensity of the peak originating from amide I.

[0070] Furthermore, the composite semipermeable membrane according to this embodiment is w 80% 35.8cm -1 38.0cm or more -1 The following is preferable, w 80% 35.8cm -1 More than 37.0cm -1 It is more preferable that the following conditions be met: 35.8 cm -1 Above, 36.5cm -1 The following is even more preferable. Note that w here 80% This refers to the w before the immersion treatment described later. 80% It means...

[0071] The peak w originates from amide I. 80% For the maximum peak intensity 5 shown in Figure 2, the wavenumber width w at 80% (6) of the maximum peak intensity is the value of the peak intensity being 80% of the maximum peak intensity. 80% This is the value shown in (7).

[0072] w 80% This is an indicator that represents the degree of interaction between the carbonyl group of the amide group of the polyamide contained in the separation functional layer and other functional groups. When the carbonyl group of the amide group interacting with other functional groups increases, w 80% The peak becomes larger. Also, if the interaction between the copolymer contained in the coating layer and the carbonyl group of the amide group of the polyamide is weak, the peak originating from amide I will be broadened because it will overlap with the peak originating from the amide group contained in the copolymer contained in the coating layer, and w 80% It will get even bigger.

[0073] w 80% 35.8cm -1 As described above, an interaction occurs between the copolymer contained in the coating layer and the amide group of the polyamide, resulting in excellent chemical resistance. 80% 38.0cm -1 Under the following conditions, the interaction between the copolymer contained in the coating layer and the amide groups of the polyamide is strong, allowing the coating layer to fully function as a protective layer and exhibit excellent chemical resistance.

[0074] The peak position and w of amide I 80% This can be controlled, for example, by the structure of the copolymer contained in the coating layer, as described above. For example, when a coating layer is formed using a copolymer containing amide bonds in its repeating units, hydrogen bonds are formed between the amide groups of the polyamide and the amide groups of the copolymer contained in the coating layer, causing the peak position of amide I to shift to the lower wavenumber side. Examples of functional groups that interact with amide groups include the hydrogen bond acceptors mentioned above.

[0075] The composite semipermeable membrane according to this embodiment was subjected to the following treatments: immersion in a 100 ppm, pH 7.0, 25°C sodium hypochlorite aqueous solution for 20 hours; immersion in a sodium hydroxide aqueous solution prepared to 25°C, pH 13.0 for 20 hours; and immersion in sulfuric acid prepared to pH 1.0 at 25°C for 20 hours (immersion treatment in chlorine, alkali, and acid, hereinafter also referred to as "immersion treatment"). 80% And, w before treatment with chlorine, alkali and acid (before immersion treatment) 80% That's the difference lol 80% The change is 2.0 cm. -1 Preferably, it is 1.8 cm. -1 The following is more preferable:

[0076] Normally, when the above immersion treatment is performed on a composite semipermeable membrane containing polyamide, the amide bonds of the polyamide are cleaved, and the peak of amide I becomes broad, so the w after the immersion treatment 80% w becomes larger than before the immersion treatment. 80% The range of change represents the chemical resistance of the amide group. When the amide group of a polyamide interacts with other functional groups, the cleavage of the amide bond is suppressed, w 80% The range of change will be smaller.

[0077] w 80% The change is 2.0 cm. -1 The following conditions result in excellent chemical resistance because the copolymer contained in the coating layer interacts sufficiently with the amide groups of the polyamide. 80% The lower limit of the range of change is effectively 0 cm. -1 That is the case.

[0078] The composite semipermeable membrane according to this embodiment has a w after immersion treatment 80% of 36.0 cm -1 or more and 40.0 cm -1 or less, preferably 37.0 cm -1 or more and 39.0 cm -1 or less. When the interaction between the copolymer contained in the coating layer and the amide group of the polyamide is strong, the interaction between the copolymer contained in the coating layer and the amide group of the polyamide is maintained even after immersion treatment. Therefore, when w after immersion treatment 80% is within the above range, excellent membrane permeation flux and chemical resistance can be achieved simultaneously.

[0079] w 80% The change range and w after immersion treatment 80% can be controlled, for example, by adjusting the strength of the interaction between the copolymer contained in the coating layer and the amide group of the polyamide. Examples of the functional group that strongly interacts with the amide group of the polyamide include the above-mentioned hydrogen bond acceptor.

[0080] In the surface analysis of the coating layer side by ATR-IR, the composite semipermeable membrane according to this embodiment preferably has a ratio B / A of the peak area B at 2800 - 3000 cm -1 to the peak area A at 1630 - 1710 cm -1 of 0.60 or more and 0.85 or less, more preferably 0.60 or more and 0.80 or less, and even more preferably 0.65 or more and 0.75 or less.

[0081] Generally, in a composite semipermeable membrane provided with a separation functional layer containing polyamide on a porous support layer, the peak area B at 2800 - 3000 cm -1 derived from the hydrocarbon group is relatively small compared to the peak area A at 1630 - 1710 cm -1 derived from amide I, and the area ratio B / A is less than 0.60. By providing a coating layer, 2800 - 3000 cm -1When the peak appears, the copolymer contained in the coating layer can interact even more strongly with the crosslinked aromatic polyamide through hydrophobic interactions. Therefore, when the area ratio B / A is 0.60 or higher, excellent chemical resistance can be obtained. Also, when the area ratio B / A is 0.85 or lower, the decrease in membrane permeation flux due to the formation of the coating layer can be suppressed.

[0082] The above area ratio B / A can be controlled, for example, by using a copolymer having an alkylene moiety or other structure in the coating layer. Examples of alkylene moiety structures include aliphatic chains with 4 to 10 carbon chains, ethylene glycol moieties, propylene glycol moieties, trimethylene glycol moieties, etc., which are structures represented by the above general formula (II). If the copolymer contained in the coating layer has an alkylene moiety, it can be confirmed that the coating layer has been formed on the polyamide using a Dragendorff reagent or the like.

[0083] The composite semipermeable membrane according to this embodiment has a porous support layer containing polysulfone (hereinafter referred to as "PSf"), and surface analysis of the coating layer side by ATR-IR showed a density of 1200 to 1270 cm². -1 The peak area C derived from PSf is 1630-1710 cm², derived from amide I. -1 The ratio A / C of the peak area A is preferably 0.3 or more and 0.5 or less, and more preferably 0.3 or more and 0.35 or less.

[0084] When the above area ratio A / C is 0.3 or higher, a coating layer sufficient to interact with the amide groups of the polyamide is formed, resulting in excellent chemical resistance. Furthermore, when the above area ratio A / C is 0.5 or lower, the decrease in film permeation flux due to the formation of the coating layer can be suppressed.

[0085] The above area ratio A / C can be controlled, for example, by forming a coating layer using a copolymer having hydrogen bond acceptors, and by the thickness of the coating layer.

[0086] In addition, 1200-1270 cm derived from the above PSf -1The ratio D / C of the peak area D at 1520~1560 cm -1 to the peak area C is preferably 0.23 or more and 0.40 or less, more preferably 0.24 or more and 0.30 or less.

[0087] The peak appearing at 1520~1560 cm -1 is a peak derived from the C-N-H bending angle of the amide bond (hereinafter referred to as "amide II"). When the area ratio D / C is 0.23 or more, the amide groups of the copolymer and polyamide contained in the coating layer form an interaction, so excellent chemical resistance can be obtained. Also, when the area ratio D / C is 0.40 or less, the decrease in the membrane permeation flux due to the formation of the coating layer can be suppressed. At this time, the copolymer contained in the coating layer has sufficient primary amide and secondary amide, and the interaction with the amide bond of polyamide works sufficiently, improving the chemical resistance.

[0088] In the composite semipermeable membrane according to this embodiment, the yellowness degree ΔVYI of the surface on the coating layer side before and after contact with the vanillin solution is preferably 5 or more and 23 or less, more preferably 7 or more and 20 or less, and even more preferably 12 or more and 20 or less. Amino groups such as polyamide terminals contained in the separation functional layer form a color-developing chemical structure by chemical reaction with vanillin. That is, the yellowness degree ΔVYI of the surface on the coating layer side before and after contact with the vanillin solution reflects the amount of amino groups present in the separation functional layer. Here, as described above, since the copolymer contained in the coating layer forms a hydrogen bond with the amino groups on the surface of the separation functional layer, the amino groups that chemically react with vanillin decrease, and ΔVYI decreases. Also, when the thickness of the coating layer increases, the contact of vanillin with the separation functional layer is inhibited, so ΔVYI decreases.

[0089] When ΔVYI is 23 or less, a sufficient amount of amino groups in the separation functional layer interact with the copolymer contained in the coating layer, so the decrease in performance due to rubbing can be reduced. Also, when ΔVYI is 5 or more, the decrease in the membrane permeation flux due to the introduction of an excessive coating layer can be suppressed. The yellowness degree ΔVYI of the surface on the coating layer side is calculated by the method described in "Color development by vanillin" in the examples described later.

[0090] The value of ΔVYI can be controlled, for example, by providing a coating layer containing a copolymer having strong hydrogen bond acceptors with amino groups on the surface of the separation functional layer, as described above, or by the amount of the coating layer.

[0091] In this embodiment, the composite semipermeable membrane preferably has a degree of yellowing ΔDYI of 43 to 150 on the surface of the coating layer before and after contact with Dragendorff's reagent. Dragendorff's reagent reacts specifically with tertiary and quaternary amines and polyethylene glycol structures, resulting in coloration. Therefore, the degree of yellowing ΔDYI on the surface of the coating layer before and after contact with Dragendorff's reagent reflects the amount of tertiary and quaternary amines and polyethylene glycol structures contained in the polymer in the coating layer, i.e., the amount of the coating layer. This is particularly useful when the copolymer contains a structure represented by the above general formula (II).

[0092] When ΔDYI is 43 or higher, a sufficient amount of coating layer is formed, thereby reducing the degradation of performance due to abrasion. On the other hand, when ΔDYI is 150 or lower, the decrease in membrane permeation velocity due to the introduction of an excessive coating layer can be suppressed. From the above viewpoint, ΔDYI is more preferably between 55 and 140, and even more preferably between 60 and 120. The degree of yellowing ΔDYI of the surface on the coating layer side is calculated by the method described in "Color development with Dragendorff's reagent" in the examples described later.

[0093] In the composite semipermeable membrane according to this embodiment, when the separation functional layer is pleated, the underwater modulus of elasticity of the surface on the coating layer side (hereinafter also referred to as the "coating layer surface") is preferably 10 MPa or more and 45 MPa or less, more preferably 12 MPa or more and 40 MPa or less, and even more preferably 15 MPa or more and 35 MPa or less. "Underwater modulus" is a value that shows the relationship between stress and strain in the initial stage of elastic deformation that occurs when stress is applied to the membrane in water after immersing the composite semipermeable membrane in a 20 wt% isopropanol aqueous solution at 25°C for 20 minutes, then immersing it in distilled water at 25°C for 1 hour, and it means the slope near the origin of the stress-strain curve. If the underwater modulus of elasticity of the coating layer surface is 10 MPa or more, the coating layer has sufficient strength, so the abrasion resistance of the separation functional layer is improved. Also, if the underwater modulus of elasticity of the coating layer surface is 45 MPa or less, the coating layer does not become too hard and remains flexible, so damage due to abrasion can be reduced. The underwater modulus of elasticity of the coating layer surface is calculated by the method described in "Underwater Modulus" in the examples described later.

[0094] 1.2 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 functional layer and do not substantially possess solute separation performance themselves.

[0095] 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.

[0096] The porous support layer has numerous interconnected pores. The pore diameter and pore diameter distribution are not particularly limited, but a porous support layer is preferred in which, for example, there is a symmetric structure with uniform pore diameters, or an asymmetric structure in which the pore diameter gradually increases from one surface to the other, and the pore diameter on the surface with smaller pore diameters is 0.1 to 100 nm.

[0097] 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, polyphenylene oxide, etc., 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, polyphenylene sulfone, etc. 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.

[0098] 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.

[0099] 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 total 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.

[0100] 1.3 Separation functional layer The separation functional layer of the composite semipermeable membrane of this embodiment is a layer responsible for solute separation and contains polyamide. The separation functional layer preferably contains polyamide, and more preferably has polyamide as its main component. "Having polyamide as its main component" means that the proportion of polyamide in the separation functional layer is 50% by mass or more. More preferably, the proportion of polyamide in the separation functional layer is 80% by mass or more, and even more preferably 90% by mass or more.

[0101] The polyamide contained in the separation functional layer is a polycondensate of a polyfunctional amine and a polyfunctional acid halide. In particular, the polyamide is preferably a crosslinked polyamide and / or an aromatic polyamide.

[0102] "Cross-linked polyamide" means that the polyamide forms a cross-linked structure. For example, the polyamide may form a cross-linked structure via a cross-linking agent, or at least one of the polyfunctional amine and polyfunctional acid halide may be trifunctional or more, and the polyamide may form a network-like cross-linked structure. In particular, it is more preferable that at least one of the polyfunctional amine and polyfunctional acid halide is trifunctional or more, and the polyamide forms a network-like cross-linked structure. This results in a rigid molecular chain and a cross-linked polyamide having a good pore structure for removing fine solutes such as hydrated ions and silica.

[0103] "Aromatic polyamide" refers to a polymer of a polyfunctional amine and a polyfunctional aromatic acid halide. Specifically, examples include polymers of polyfunctional aliphatic amines and polyfunctional aromatic acid halides, and polymers of polyfunctional aromatic amines and polyfunctional aromatic acid halides. Aromatic polyamides may contain non-aromatic moieties in their molecular structure. From the viewpoint of rigidity, chemical stability, and resistance to operating pressure, crosslinked aromatic polyamides are more preferable, and crosslinked total aromatic polyamides consisting solely of aromatic polyamides are even more preferable.

[0104] A "polyfunctional amine" refers to an amine having at least two primary amino groups and / or secondary amino groups in a single molecule. Examples of polyfunctional amines include aromatic trifunctional amines such as 1,3,5-triaminobenzene and 1,2,4-triaminobenzene; aromatic difunctional amines such as o-phenylenediamine, m-phenylenediamine (hereinafter referred to as "m-PDA"), p-phenylenediamine, o-xylylenediamine, m-xylylenediamine, p-xylylenediamine, o-diaminopyridine, m-diaminopyridine, p-diaminopyridine, 3,5-diaminobenzoic acid, 2,4-diaminobenzenesulfonic acid, 3-aminobenzylamine, and 4-aminobenzylamine; and aliphatic difunctional amines such as ethylenediamine, propylenediamine, 1,4-diaminocyclohexane, piperazine, 2,5-dimethylpiperazine, 4-aminopiperidine, and aminoethylpiperazine. These polyfunctional amines may be used individually or in combination of two or more.

[0105] From the viewpoint of the separation performance, membrane permeation flux, and heat resistance of the composite semipermeable membrane, the polyfunctional amines are preferably m-PDA, p-phenylenediamine, and 1,3,5-triaminobenzene. Among these, m-PDA is particularly preferred from the viewpoint of ease of availability and ease of handling.

[0106] 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 trifunctional aromatic acid chlorides such as trimesic acid chloride (hereinafter referred to as "TMC") and trimellitic acid chloride, trifunctional aliphatic acid chlorides such as 1,3,5-cyclohexanetricarboxylic acid trichloride, bifunctional aromatic acid chlorides such as biphenyldicarboxylic acid chloride, azobenzenedicarboxylic acid dichloride, terephthalic acid chloride, isophthalic acid chloride, and 2,6-naphthalenedicarboxylic acid dichloride, and bifunctional aliphatic 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.

[0107] From the viewpoint of the separation performance and heat resistance of the composite semipermeable membrane, polyfunctional aromatic acid chlorides having 2 to 4 chlorocarbonyl groups in one molecule are preferred as the polyfunctional acid halide. Among these, TMC is particularly preferred from the viewpoint of ease of availability and ease of handling.

[0108] The shape and thickness of the separation functional layer and the coating layer affect the separation performance and membrane permeation flux. As shown in Figures 3(a) and 3(b), the separation functional layer 3 is preferably pleated, having multiple protrusions. Figure 3(b) is an enlarged view of Y in Figure 3(a), and the sum of the thicknesses of the separation functional layer and the coating layer in this specification is represented by T in Figure 3(b). Furthermore, it is more preferable that the inside of the protrusions 8 (between the separation functional layer 3 and the support membrane 2) be voids. The separation functional layer 3 has a larger surface area when it has a pleated shape than when it has a flat shape, so a high membrane permeation flux can be obtained while maintaining separation performance. The coating layer 4 may be formed thinly on the separation functional layer 3 to form a pleated shape together with the separation functional layer, or it may have a relatively large thickness that fills the pleated shape of the separation functional layer 3.

[0109] The presence of a pleated shape in the separation functional layer can be confirmed by observing a cross-section of the separation functional layer perpendicular to the surface of the composite semipermeable membrane using a transmission electron microscope (TEM). If even a slight protrusion is observed in the separation functional layer during TEM observation, it is considered to have a pleated shape.

[0110] 1.4 Composite semipermeable membrane elements 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 4.

[0111] As shown in Figure 4, the composite semipermeable membrane element 9 comprises a composite semipermeable membrane 1, a supply-side flow channel material 12, a permeable-side flow channel material 13, a water collection pipe 14, and end plates 10 and 11. The supply-side channel material 12 is positioned opposite the supply side of the composite semipermeable membrane 1 and is wrapped around the water collection pipe 14 together with the composite semipermeable membrane 1. A net is preferred as the supply-side channel material 12. The permeable-side channel material 13 is positioned opposite the permeable side of the composite semipermeable membrane 1 and is wrapped around the water collection pipe 14 together with the composite semipermeable membrane 1. For the permeable-side channel material 13, tricot or a sheet with protrusions can be used. The water collection pipe 14 is a hollow cylindrical member with multiple holes on its side. The end plates 10 and 11 are disc-shaped members equipped with multiple supply ports (or discharge ports).

[0112] The separation of fluids by the composite semipermeable membrane element 9 will now be explained. The supply water 15 is supplied to the composite semipermeable membrane element 9 from multiple supply ports on the end plate 10. The supply water 15 moves within the supply-side channel formed by the supply-side channel material 12 on the supply side of the composite semipermeable membrane 1. The fluid that permeates through the composite semipermeable membrane 1 (shown as permeate water 16 in the figure) moves within the permeate-side channel formed by the permeate-side channel material 13. The permeate water 16 that reaches the collection pipe 14 enters the inside of the collection pipe 14 through the holes in the collection pipe 14. The permeate water 16 that has flowed inside the collection pipe 14 is discharged to the outside from the end plate 11. On the other hand, the fluid that did not permeate through the composite semipermeable membrane 1 (shown as concentrated water 17 in the figure) moves within the supply-side channel and is discharged to the outside from the end plate 11. In this way, the supply water 15 is separated into permeate water 16 and concentrated water 17.

[0113] 2. Method for manufacturing composite semipermeable membranes The method for manufacturing a composite semipermeable membrane according to one embodiment of this present invention is not particularly limited as long as a composite semipermeable membrane satisfying the desired characteristics described above can be obtained, but for example, it can be manufactured by the following method.

[0114] 2.1 Formation of the support film For the method of forming the support film, known methods can be suitably used. The following description will take the case where PSf is used as the material for the porous support layer as an example.

[0115] First, PSf is dissolved in a suitable solvent to prepare a porous support layer stock solution. DMF is a preferred solvent for PSf.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] The resulting support film may be washed before the formation of the separation functional layer to remove any remaining solvent in the film.

[0120] 2.2 Process for forming the separation functional layer Regarding the formation method of a separation functional layer containing polyamide, we will describe, as an example, a method in which a polyfunctional amine and a polyfunctional acid halide are polymerized and solidified on the support film obtained in "2.1 Formation of 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.

[0121] The interfacial polymerization process comprises (a) contacting an aqueous solution containing a polyfunctional 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 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.

[0122] In step (a), the aqueous solution contains at least a polyfunctional amine. As the polyfunctional amine, for example, the polyfunctional amines described in "1.3 Separation Functional Layer" above can be used.

[0123] The concentration of the polyfunctional 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 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 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.

[0124] It is preferable to bring the polyfunctional amine aqueous solution into uniform and continuous contact with the support film. Specifically, examples include coating the support film with the polyfunctional 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.

[0125] After bringing the polyfunctional amine aqueous solution into contact with the support film, it is preferable to thoroughly drain the liquid so that no droplets remain on the support film. 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 film 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 film surface can be dried to remove some of the water from the aqueous solution.

[0126] In step (b), as the polyfunctional acid halide, for example, the polyfunctional acid halide described in "1.3 Separation Functional Layer" above can be used.

[0127] The organic solvent is preferably immiscible with water, dissolves polyfunctional acid halides, does not damage the support film, and is inert to polyfunctional 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.

[0128] 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.

[0129] It is preferable to uniformly and continuously bring the organic solvent solution of the polyfunctional acid halide into contact with the support film that has been brought into contact with the aqueous solution of the polyfunctional amine. Specifically, for example, one method is to coat the support film that has been brought into contact with the aqueous solution of the 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 the polyfunctional 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.

[0130] Furthermore, if necessary, the support film in contact with an 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.

[0131] 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, holding 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.

[0132] 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 amine or polyfunctional acid halide used.

[0133] 2.3 Process for forming the coating layer The composite semipermeable membrane processed in this process may be an unused membrane or a membrane that has deteriorated due to use or other factors. Furthermore, this process can be considered one of the manufacturing processes for composite semipermeable membranes.

[0134] The coating layer formation step comprises (e) bringing a solution containing a copolymer of hydrophilic units and hydrophobic units having hydrogen bond acceptors with a polarization degree of 0.70e or more and 1.00e or less into contact with the separation functional layer; (f) draining off excess solution; and (g) washing the composite semipermeable membrane.

[0135] In step (e), the solution containing a copolymer of a hydrophilic unit and a hydrophobic unit having a hydrogen bond acceptor with a polarization degree of 0.70e to 1.00e may optionally contain compounds such as a crosslinking agent. The crosslinking agent may crosslink the copolymers forming the coating layer with each other, or it may crosslink the copolymers forming the coating layer with the polyamide in the separation functional layer. If the copolymers 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.

[0136] 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.

[0137] It is preferable to uniformly and continuously bring a solution containing a copolymer of hydrophilic units and hydrophobic units having hydrogen bond acceptors with a polarization degree of 0.70e to 1.00e onto the separation functional layer. Specifically, for example, a method of coating the separation functional layer with the solution can be used. 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.

[0138] The concentration of the copolymer in the solution between hydrophilic units and hydrophobic units having hydrogen bond acceptors with a polarization degree of 0.70e to 1.00e is preferably 0.0001% to 10% by mass, more preferably 0.0001% to 2% by mass, and even more preferably 0.005% to 1% by mass. When the copolymer concentration is 0.0001% by mass or higher, a sufficient amount of copolymer forms a coating layer on the surface of the separation functional layer, thus exhibiting excellent high chemical resistance. On the other hand, when the copolymer concentration is 10% by mass or lower, a composite semipermeable membrane with sufficient membrane permeation flux can be obtained.

[0139] 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.

[0140] 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.

[0141] 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.

[0142] 3. Use of composite semipermeable membranes 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.

[0143] 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.

[0144] 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).

[0145] While a higher operating pressure for the fluid separation device improves the solute removal rate, it also increases the energy required for operation. 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. Furthermore, 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 a concern about membrane deterioration due to high pH operation. Therefore, operation in the neutral range is preferable.

[0146] 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 as used herein refers to a small difference in membrane performance before and after the "membrane degradation test" described in the examples. Specifically, the membrane permeation flux ratio, which is the value obtained by dividing the membrane permeation flux after the degradation test by the membrane permeation flux before the degradation test, is preferably 2.0 or less, more preferably 1.8 or less, and even more preferably 1.7 or less. Furthermore, the membrane permeation flux ratio, which is the value obtained by dividing the membrane permeation flux after the abrasion test by the membrane permeation flux before the abrasion test, is preferably 1.5 or less, more preferably 1.3 or less, and even more preferably 1.1 or less. Furthermore, the smaller the difference in membrane performance before and after the immersion treatment described in the "Immersion Treatment in Hydrogen Peroxide Solution" example, the higher the chemical resistance. Specifically, it is preferable that the SP ratio, which is the ratio of NaCl permeability before and after immersion treatment in hydrogen peroxide solution, is 7.0 or less. Also, it is preferable that the membrane permeation flux ratio, which is the value obtained by dividing the membrane permeation flux after immersion treatment in hydrogen peroxide solution by the membrane permeation flux before immersion treatment in hydrogen peroxide solution, is 1.7 or less.

[0147] 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 preceding stage 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.

[0148] 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.

[0149] 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 field, where high purity of raw materials and solvents is required; the electronic and optical materials manufacturing field, where impurity control is required to maintain optical and electrical properties; the nuclear-related field, 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 impacts analytical accuracy. For example, hydrogen peroxide, one of the chemicals used for cleaning in the semiconductor manufacturing process, is generally synthesized and then purified using 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.

[0150] 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.

[0151] 4. Treatment agents for composite semipermeable membranes As described above, copolymers having structures represented by general formulas (I) to (III) form hydrogen bonds with polyamides and also exhibit hydrophobic interactions, making them suitable for use as coating agents for composite semipermeable membranes to improve the chemical resistance of composite semipermeable membranes containing polyamides in the separation functional layer.

[0152] The copolymer used in the coating agent preferably has the structure represented by the above general formula (IV), and more preferably has the structure represented by the above general formula (V).

[0153] 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.

Example

[0154] The present invention will be described below with specific examples, but the present invention is not limited to these examples at all.

[0155] <NaCl removal rate> Evaluation water adjusted to a temperature of 25°C, pH 7.0, and NaCl concentration of 34,000 ppm was supplied as feed water to the composite semipermeable membrane, and the operating pressure was adjusted to a membrane permeation flux of 1.0 m 3 / m 2 / d and supplied, and membrane filtration treatment was performed for 1 hour. Then, the electrical conductivities of the feed water and the permeated water were measured with a multi-water quality meter MM60R (manufactured by Toa DKK Corporation) to obtain the respective practical salinity, that is, the NaCl concentration. From the obtained NaCl concentration, the NaCl removal rate was calculated according to the following formula (1). Here, the NaCl concentration (ppm) means the concentration on a mass basis. NaCl removal rate (%) = 100 × {1 - (NaCl concentration in permeated water / NaCl concentration in feed water)} ··· Formula (1) <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 the composite semipermeable membrane after adjusting the pressure to 5.50 MPa, and membrane filtration treatment was performed for 1 hour. Then, the permeated water volume (m 3 ) was measured and converted to a value per unit membrane area (m 2 ) and per unit time (d) to calculate the membrane permeation flux (m / d).

[0156] <Membrane deterioration test> After sequentially performing the following treatments (i) to (vi) on the composite semipermeable membrane, the NaCl removal rate and the membrane permeation flux were calculated by the methods described in "NaCl removal rate" and "membrane permeation flux" above. Also, the value obtained by dividing the membrane permeation flux after the membrane deterioration test by the membrane permeation flux before the membrane deterioration test was defined as the membrane permeation flux ratio. (i) Immersed in an aqueous sodium hydroxide solution adjusted to 25°C and pH 13.0 for 48 hours, and then washed with distilled water. (ii) Immersed in sulfuric acid prepared at 25°C and pH 2.0 for 3 hours, and then washed with distilled water. (iii) Immersed for 24 hours in a 20 mg / L sodium hypochlorite aqueous solution prepared at 25°C and pH 7.0. (iv) Immersed in a 1000 mg / L sodium bisulfite aqueous solution at 25°C for 10 minutes, then washed with distilled water. (v) Immersed in a sodium hydroxide aqueous solution prepared at 25°C and pH 13.0 for 48 hours, then washed with distilled water. (vi) Immersed in sulfuric acid prepared at 25°C and pH 2.0 for 3 hours, then washed with distilled water.

[0157] <Calculation of Polarization> The degree of polarization of the hydrophilic and hydrophobic units was calculated using the following process: target monomer structure modeling step S1, trimer modeling step S2, stable conformation search step S3, structure optimization calculation step S4, and charge parameter creation step S5.

[0158] [Target monomer structure modeling process S1] Using Winmoster (manufactured by CrossAbility Co., Ltd.), we modeled the three-dimensional molecular structure of each monomer unit, namely the hydrophilic and hydrophobic units. When polymers consisting of other monomer units were incorporated into the hydrophilic and hydrophobic units, the monomer units incorporated into the hydrophilic and hydrophobic units were modeled as trimers.

[0159] [Trimer Modeling Process S2] The hydrophilic and hydrophobic units modeled in the target monomer structure modeling step S1 were similarly converted into trimer models using Winmoster.

[0160] [Stable conformation search step S3] Using conformational search (Balloon), stable conformational searches were performed on the trimer models of the hydrophilic and hydrophobic units modeled in the trimer modeling step S2. This step was omitted when the stable conformation of the target structure could be determined from chemical experience.

[0161] [Structural optimization calculation process S4] If necessary, for the trimer models of hydrophilic and hydrophobic units obtained in the stable conformation search process S3, a structure optimization calculation using density functional theory was performed using the quantum chemistry calculation program Gaussian16, with Cartesian coordinates corresponding to the classical mechanics-level stable conformations of the trimer models of hydrophilic and hydrophobic units whose stable conformations had been determined, as input information, in order to determine the vacuum-optimized structure. The calculation method / basis set used was B3LYP / 6-31G(d), and the SCF convergence condition was set to "SCF=Tight".

[0162] [Charge parameter calculation process S5] To calculate the partial charge on each atom in the trimer model of hydrophilic and hydrophobic units within the vacuum-optimized structure obtained in structural optimization calculation step S4, the log file output after the structural optimization calculation using Gaussian16 described above was read, and a single-point calculation using density functional theory was performed. For this calculation, the calculation method / basis set was HF / 6-31g*, and the following were added to the root section: "geom=allcheck", "guess=read", "pop=mk", and "iop(6 / 41=10,6 / 42=17,6 / 50=1)", causing an esp file to be 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. From the obtained RESP charge, the degree of polarization of each atom was calculated using the following equation (2). For hydrophilic and hydrophobic units, the maximum value of the polarization of the atoms constituting the hydrogen-bonding acceptors, calculated for each unit, was defined as the polarization of the hydrophilic and hydrophobic units, respectively. Polarization degree = -RESP charge [e]...Equation (2)

[0163] <atr-ir> Under an atmosphere adjusted to 20°C and 50% RH, an ATR-IR spectrum was obtained by irradiating the surface of the separation functional layer of a composite semipermeable film with infrared light using a Shimadzu IRTracer-100 and a Shimadzu IRXross / IRAffinity-1 series single-reflection diamond ATR attachment (QATR10) as an accessory for total internal reflection measurement. The measurement conditions were set to a resolution of 1 cm. -1 The settings were adjusted, and the number of scans was set to 64. The composite semipermeable membrane was pre-air-dried before being used as the measurement sample. The obtained spectra were expressed as absorbance, and auto-baseline correction was performed. A Shimadzu LabSolutions IR was used for the analysis. The wavenumber and w of the peak top of amide I were determined. 80% The peaks were calculated by applying a Gaussian function approximation to the amide I peak in the spectrum obtained by ATR-IR. The area of ​​each peak was calculated by taking the spectrum at a wavenumber within a specified range and measuring 1.9 cm². -1 The area was divided into sections, approximated by trapezoidal shapes, and the areas of each section were added together to calculate the peak area A. That is, the peak area A is 1630-1710 cm². -1 Within this range, the peak area B is 2800-3000 cm². -1 Within this range, the peak area C is 1200-1270 cm². -1 Within this range, the peak area D is 1520-1560 cm². -1 Within the specified range, the peak area was calculated using the trapezoidal approximation described above. This was performed at two different points for each sample, and the average value was calculated. Similar measurements were performed on three different samples, and the average value obtained was rounded to the third decimal place and used.

[0164] <Coloring due to vanillin> A composite semipermeable membrane was washed with 85°C hot water for 2 minutes, and then the moisture on the surface of the coating layer or separation functional layer was removed by air drying. After drying, the composite semipermeable membrane was immersed in a 2% by mass ethanol solution containing vanillin at 25°C for 15 seconds, the membrane was tilted to remove excess ethanol solution from the membrane surface, and the ethanol on the membrane surface was removed by air drying. Furthermore, a vanillin-treated membrane sample was obtained by heating in a 150°C oven for 15 minutes. Alternatively, a composite semipermeable membrane was washed with 85°C hot water for 2 minutes, and then the moisture on the surface was removed by air drying. After drying, the composite semipermeable membrane was immersed in an ethanol solution for 15 seconds, the membrane was tilted to remove excess ethanol solution from the membrane surface, and the ethanol on the membrane surface was removed by air drying. Furthermore, an untreated membrane sample was obtained by heating in a 150°C oven for 15 minutes. The yellowness of the surface of the coating layer or separation functional layer was measured using a portable colorimeter (TCS-100, Time Technology Co., Ltd.) in accordance with JIS K 7373. A standard illuminant D65 light source was used, and the yellowness VYI of the vanillin-treated film sample and the yellowness VYI0 of the untreated film sample were measured from the tristimulus values ​​of the XYZ color system. The degree of yellowing ΔVYI was calculated using the following formula (3). Three measurements were performed using different samples. ΔVYI = VYI - VYI0 ... Equation (3) The degree of yellowing ΔVYI was calculated by averaging the values ​​obtained from three measurements and rounding to the first decimal place.

[0165] <Elastic modulus underwater> Under the following conditions, the deformation of the surface on the coating layer side was measured using an atomic force microscope (AFM). Based on the deformation, the elastic modulus in water was then measured. Ten different folds and protrusions were measured within each sample. Furthermore, the average value obtained from three measurements using different samples was rounded to the first decimal place and used. Observation equipment: BRUKER FastScan scanning probe microscope Probe: Cantilever (made of silicon, spring constant: 0.7 N / m, shape: conical) Scanning mode: Nanomechanical Mapping in Fluid Scanning area: 2 μm square The cantilever's bending sensitivity was measured using sapphire, and the cantilever's spring constant was determined by thermal vibration. The composite semipermeable membrane was immersed in a 20 wt% isopropanol aqueous solution at 25°C for 20 minutes, and then immersed in distilled water at 25°C for 1 hour. Subsequently, a 1 cm square piece of the composite semipermeable membrane was fixed to a sample stage, and 0.3 mL of distilled water was added dropwise. The cantilever was then pressed against the convex folds on the separation functional layer side and then released, and a curve plotting the force acting on the cantilever against the distance between the cantilever and the composite semipermeable membrane was obtained. In this specification, this curve is referred to as the force curve.

[0166] At this time, let Z be the displacement of the cantilever (Z=Z0 at the moment the cantilever and the composite semipermeable membrane come into contact, and Z=0 at the point furthest from the sample), and let Δ be the curvature of the cantilever. The amount of deformation δ when the composite semipermeable membrane, which is the sample, is deformed due to contact with the cantilever is given by the following equation (4). δ[nm]=(Z-Z0)-Δ···Equation (4) Here, the displacement Z of the cantilever is in contact with the composite semipermeable membrane. t For Z, δ, and Δ are at their maximum value Z. t , δ t , Δ t Here, by considering Δ for the cantilever displacement Z, the horizontal axis is transformed into the distance between the cantilever and the composite semipermeable membrane. At this time, the distance between the cantilever and the composite semipermeable membrane is a parameter that satisfies the following equation (5).

[0167] Distance between cantilever and composite semipermeable membrane [nm] = Δ - Z + Z t -Δ t ...Equation (5) The distance between the cantilever and the composite semipermeable membrane at the point on the force curve where the load becomes zero, i.e., Δ=0 and Z=Z0, is given by equation (5) Z t -Z0-Δ t However, the deformation amount δ at the point of maximum interaction is t From equation (4), Z t -Z0-Δ t Therefore, the distance between the cantilever and the composite semipermeable membrane at the point on the force curve where the load becomes zero is read, and the deformation amount δ when a certain load is applied is determined. t They sought it.

[0168] When the cantilever was brought close to the composite semipermeable membrane, the amount of deformation measured with the distance between the cantilever and the composite semipermeable membrane on the horizontal axis and the load on the vertical axis was used to measure the modulus of elasticity in water using the following equation (6). At that time, the curves in the load range of 3 to 21 nN were approximated to straight lines by fitting.

[0169] In the Hertz model, which assumes that the cantilever and composite semipermeable membrane are spherical, the following relationship holds between load and modulus of elasticity. Using this equation, the modulus of elasticity underwater was calculated from the resulting force curve. F=(4 / 3){E / (1-ν)}(√R)δ 3 / 2 ...Equation (6) Here, F is the load (nN), E is the modulus of elasticity in water (MPa), ν is Poisson's ratio, R is the radius of the cantilever (nm), and δ is the deformation of the composite semipermeable membrane (nm).

[0170] In this specification, the load F was set to 30 nN, the cantilever radius R to 20 nm, and the Poisson's ratio ν to 0.3.

[0171] <Color development using Dragendorff's reagent> Solution A was prepared by dissolving bismuth subnitrate in 1 mol / L hydrochloric acid to a concentration of 56 mmol / L. Next, solution B was prepared by dissolving potassium iodide in water to a concentration of 2.4 mol / L. Solution A and solution B were mixed in a 1:1 ratio, and then diluted 2.5 times with water to prepare Dragendorff's reagent. The composite semipermeable membrane was immersed in 0.05 mol / L hydrochloric acid for 15 minutes, then immersed in Dragendorff's reagent for 45 minutes, and then immersed in 0.05 mol / L hydrochloric acid for 10 minutes to remove any remaining Dragendorff's reagent from the membrane surface. After air drying overnight, a Dragendorff's reagent-treated membrane sample was obtained. Alternatively, the composite semipermeable membrane was immersed in 0.05 mol / L hydrochloric acid for 15 minutes, then immersed in 0.2 mol / L hydrochloric acid for 45 minutes, and then immersed in 0.05 mol / L hydrochloric acid for 10 minutes. The untreated film samples were then air-dried overnight to obtain the untreated film samples. The yellowness of the film samples was measured using a portable colorimeter (TCS-100, Time Technology Co., Ltd.), in accordance with JIS K 7373, using a standard illuminant D65 light source. The yellowness DYI of the Dragendorff reagent-treated film sample and the yellowness DYI0 of the untreated film sample were measured from the tristimulus values ​​of the XYZ color system, and the degree of yellowing ΔDYI was calculated using the following formula (7). ΔDYI = DYI - DYI0 ... Equation (7) The degree of yellowing ΔDYI was measured three times using the sample, and the average value obtained from the three measurements was calculated and rounded to the first decimal place.

[0172] <Abrasion Test> As shown in Figures 5 and 6, the composite semipermeable membrane 1 was cut into a 12cm x 13cm square and attached to a 5.0kg rectangular parallelepiped (base 12cm x 13cm square) weight 18 with the coating layer or separation functional layer facing outwards. The membrane surface was then deliqued by blowing a nitrogen stream from an air nozzle. A polypropylene net 19 (thickness 0.7mm, pitch width: 5.6mm x 4.5mm) was attached to a flat metal plate 20. As shown in Figure 5, the weight 18 was placed on the polypropylene net 19 attached to the metal plate 20 so that the entire coating layer or separation functional layer of the composite semipermeable membrane 1 was in contact with it. A string was attached to one end of the weight 18 in the axial direction (horizontal direction), and the other end of the string was connected to a tensile testing machine 21 (RTG-1210, manufactured by A&D Co., Ltd.). A pulley 22 was interposed between the weight 18 and the tensile testing machine 21 so that the string bent vertically. The weight 18, along with the composite semipermeable membrane 1, was pulled using the tensile testing machine 21 under the following conditions. Afterwards, the weight 18 was returned to its initial position before movement, and the weight 18, along with the composite semipermeable membrane 1, was pulled again using the same procedure. Tensile speed: 100 mm / min Tensile distance: 240mm total (120mm x 2 times) Measurement room temperature: 25℃ Furthermore, using the composite semipermeable membranes that underwent the abrasion test, the NaCl removal rate of the composite semipermeable membranes after the abrasion test was measured using the method described above for "NaCl removal rate". The NaCl removal rate was measured for all eight membranes that underwent the abrasion test, and the average value was taken as the NaCl removal rate after the abrasion test.

[0173] <Immersion treatment> The composite semipermeable membrane was immersed in a sodium hypochlorite aqueous solution prepared at 25°C, 100 ppm, and pH 7.0 for 20 hours, and then washed with distilled water. Next, it was immersed in a sodium hydroxide aqueous solution prepared at 25°C and pH 13.0 for 20 hours, then immersed in sulfuric acid prepared at 25°C and pH 1.0 for 20 hours, and then washed with distilled water.

[0174] <Immersion treatment in hydrogen peroxide solution> The composite semipermeable membrane was immersed in hydrogen peroxide solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., Wako Grade 1, product code 080-01186) at 25°C for 72 hours and then washed with distilled water. Chemical resistance was evaluated by the SP ratio and membrane permeation flux ratio before and after immersion in hydrogen peroxide solution, similar to the "immersion treatment" described above. Chemical resistance was evaluated by the membrane permeation flux ratio and SP ratio before and after the immersion treatment and the immersion in hydrogen peroxide solution treatment, and was calculated using the following equations (8) and (9). Note that in equations (8) and (9), when determining the SP ratio and membrane permeation flux ratio before and after immersion in hydrogen peroxide solution, "immersion treatment" should be read as "immersion in hydrogen peroxide solution treatment". Membrane permeation flux ratio = Membrane permeation flux after immersion treatment / Membrane permeation flux before immersion treatment ... Equation (8) SP ratio = (100 - NaCl removal rate after immersion treatment) / (100 - NaCl removal rate before immersion treatment) ... Equation (9)

[0175] <Synthesis of copolymers> [Synthesis Example 1] Copolymer 1 was obtained by heating 1 g of ε-caprolactam, 100 g of a salt consisting of polyethylene glycol with a number-average molecular weight of 600 and amino groups at both ends (hereinafter referred to as "α,ω-diaminopolyoxyethylene") and adipic acid, and 101 g of water in a heat-resistant and pressure-resistant container under a nitrogen atmosphere to 200°C and reacting for 2 hours.

[0176] [Synthesis Example 2] 100 g of ε-caprolactam, 100 g of a salt consisting of α,ω-diaminopolyoxyethylene and adipic acid, and 200 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 copolymer 2.

[0177] [Synthesis Example 3] 120 g of ε-caprolactam, 100 g of a salt consisting of α,ω-diaminopolyoxyethylene and adipic acid, and 220 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 copolymer 3.

[0178] [Synthesis Example 4] 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 copolymer 4.

[0179] [Synthesis Example 5] 10 g of α,ω-diaminopolyoxyethylene and 0.84 g of ethylenediamine were dissolved in 100 g of tetrahydrofuran, then 0.45 g of hexamethylene diisocyanate was added, and the mixture was reacted at room temperature under a nitrogen atmosphere for 2 hours to obtain copolymer 5.

[0180] [Synthesis Example 6] 10 g of 2-pyrrolidone, 100 g of a salt consisting of α,ω-diaminopolyoxyethylene and oxalic acid, and 110 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 copolymer 6.

[0181] [Synthesis Example 7] 20 g of ε-caprolactam, 100 g of a salt consisting of Jeffamine (ED-2003, manufactured by Sigma-Aldrich) and adipic acid, and 120 g of water were heated to 200°C in a heat-resistant and pressure-resistant vessel under a nitrogen atmosphere and reacted for 2 hours to obtain copolymer 7.

[0182] [Synthesis Example 8] 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 copolymer 8.

[0183] [Synthesis Example 9] 10 g of ε-caprolactam, 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 copolymer 9.

[0184] [Synthesis Example 10] 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 copolymer 10.

[0185] [Synthesis Example 11] 100 g of a salt consisting of α,ω-diaminopolyoxyethylene and oxalic 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 copolymer 11.

[0186] <Fabrication of composite semipermeable membranes> A porous support layer stock solution was prepared by dissolving 15% by mass of PSf (Udel P-3500, Mw80,000, 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. The material was then washed with hot water at 90°C for 2 minutes to obtain a support film in which a porous support layer was formed on the substrate surface. The thickness of the porous support layer in the obtained support film was 40 μm. Next, the obtained support membrane was immersed in a 3% by mass aqueous solution of m-PDA for 2 minutes. The support membrane was then slowly pulled up vertically, and excess aqueous solution was removed from the surface of the support membrane by blowing nitrogen from an air nozzle. In a controlled environment of 25°C, 20 ml of decane solution at 25°C containing 0.15% by mass of TMC was applied to the surface of the support membrane so that it was completely wetted, and it was left to stand for 1 minute. Next, the membrane was held vertically for 30 seconds to drain and remove excess solution, and then washed with 90°C hot water for 2 minutes to obtain composite semipermeable membrane 1. The separation functional layer of composite semipermeable membrane 1 had a pleated shape.

[0187] [Reference example 1] Table 3 shows the performance evaluation results for composite semipermeable membrane 1.

[0188] [Example 1] The composite semipermeable membrane 1 was brought into contact with an aqueous solution containing 0.01% by mass of copolymer 1. The aqueous solution was kept at 20°C for 5 minutes while in contact. Thereafter, with the composite semipermeable membrane held vertically, the excess aqueous solution was drained and removed, and it was washed with water at 20°C for 5 minutes to prepare a composite semipermeable membrane provided with copolymer 1 as a coating layer.

[0189] [Example 2] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymer 1 was changed to copolymer 2.

[0190] [Example 3] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymer 1 was changed to copolymer 3.

[0191] [Example 4] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymer 1 was changed to copolymer 4.

[0192] [Example 5] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymer 1 was changed to copolymer 5.

[0193] [Example 6] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymer 1 was changed to copolymer 6.

[0194] [Example 7] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymer 1 was changed to copolymer 7.

[0195] [[ID=K40]][Example 8][[ID=K41]] [[ID=K42]]A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymer 1 was changed to copolymer 8. [[ID=K43]] [[ID=K44]]

[0196] [[ID=K45]] [[ID=K46]][Example 9][[ID=K47]] [[ID=K48]]A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymer 1 was changed to copolymer 9. [[ID=K49]] [[ID=K50]]

[0197] [[ID=K51]] [[ID=K52]][Example 10][[ID=K53]] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that the copolymer 1 was changed to copolymer 10.

[0198] [Comparative Example 1] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that the copolymer 1 was changed to polyethylene glycol (weight average molecular weight: 8,000,000).

[0199] [Comparative Example 2] The composite semipermeable membrane 1 was contacted with a formic acid solution containing 0.01% by mass of 6-nylon (weight average molecular weight: 100,000). After the solution contact, the crosslinked polyamide of the composite semipermeable membrane decomposed and did not show salt removal performance.

[0200] [Comparative Example 3] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that the copolymer 1 was changed to copolymer 11.

[0201] [Comparative Example 4] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that the copolymer 1 was changed to Pluronic (registered trademark, F-68), which is a polyoxyethylene-polyoxypropylene block copolymer.

[0202] [Comparative Example 5] On the surface of the separation functional layer of the composite semipermeable membrane 1, an aqueous solution containing 2.0% by mass of ethylene-vinyl alcohol copolymer (Exceval RS-1717), 0.5% by mass of glutaraldehyde, and 0.1% by mass of sulfuric acid was brought into contact with the entire surface in an environment controlled at 20°C. While the aqueous solution remained on the surface of the separation functional layer, hot air at 70°C was blown onto the composite semipermeable membrane for 3 minutes to form a coating layer on the separation functional layer. Then, the composite semipermeable membrane was held vertically to drain and remove the excess aqueous solution, and washed with water at 20°C for 2 minutes. Finally, as a hydrophilic treatment, the composite semipermeable membrane was immersed in a 14% by mass aqueous solution of isopropanol at 20°C for 5 minutes to prepare the composite semipermeable membrane.

[0203] [Comparative Example 6] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that the aqueous solution containing copolymer 1 was an aqueous solution containing 0.01% by mass of polyacrylic acid (weight-average molecular weight: 100,000) and 0.05% by mass of DMT-MM.

[0204] [Example 11] A composite semipermeable membrane was prepared using the same method as in Example 7, except that the holding time was changed to 1 hour.

[0205] [Example 12] A composite semipermeable membrane was prepared using the same method as in Example 2, except that the holding time was changed to 5 hours.

[0206] [Example 13] A composite semipermeable membrane was prepared using the same method as in Example 11, except that the holding time was changed to 5 hours.

[0207] [Example 14] A composite semipermeable membrane was prepared using the same method as in Example 8, except that the holding time was changed to 1 hour.

[0208] [Comparative Example 7] A composite semipermeable membrane was prepared using the same method as in Comparative Example 1, except that the retention time was changed to 5 hours.

[0209] [Comparative Example 8] A composite semipermeable membrane was prepared using the same method as in Comparative Example 7, except that polyethylene glycol was replaced with polyethyl oxazoline (weight-average molecular weight: 100,000) and the retention time was changed to 5 hours.

[0210] [Comparative Example 9] A composite semipermeable membrane was prepared in the same manner as in Comparative Example 5, except that the operation of blowing 70°C hot air for 3 minutes onto 1.0% by mass of fully saponified polyvinyl alcohol (weight-average molecular weight: 100,000) containing 2.0% by mass of ethylene-vinyl alcohol copolymer was changed to an operation of holding the membrane at 20°C for 1 hour while the aqueous solution containing fully saponified polyvinyl alcohol, glutaraldehyde, and sulfuric acid remained on the surface of the separation functional layer.

[0211] [Example 15] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that the copolymer 1 was changed to copolymer 2, the concentration was changed to 10% by mass, and the retention time was changed to 30 seconds. Thereafter, a membrane deterioration test, color development due to vanillin yellowing, elastic modulus in water, and color development with Dragendorff's reagent were carried out.

[0212] [Example 16] A composite semipermeable membrane was prepared in the same manner as in Example 15, except that the concentration was changed to 1% by mass and the retention time was changed to 1 hour.

[0213] [Example 17] A composite semipermeable membrane was prepared in the same manner as in Example 15, except that the concentration was changed to 0.01% by mass. [[ID=I5]]

[0214] [Example 18] A composite semipermeable membrane was prepared in the same manner as in Example 15, except that the copolymer 2 was changed to copolymer 7, the concentration was changed to 1% by mass, and the retention time was changed to 1 hour.

[0215] [Comparative Example 10] A composite semipermeable membrane was prepared in the same manner as in Comparative Example 1, except that the concentration was changed to 1% by mass and the retention time was changed to 1 hour. Thereafter, a membrane deterioration test, color development due to vanillin yellowing, elastic modulus in water, and color development with Dragendorff's reagent were carried out.

[0216] [Comparative Example 11] A composite semipermeable membrane was prepared in the same manner as in Comparative Example 5, except that 2% by mass of an ethylene-vinyl alcohol copolymer was changed to 1% by mass of a completely saponified polyvinyl alcohol (weight average molecular weight: 100,000). Thereafter, a membrane deterioration test, color development due to vanillin yellowing, elastic modulus in water, and color development with Dragendorff's reagent were carried out.

[0217] [Reference Example 2] The composite semipermeable membrane 1 was subjected to an immersion treatment in hydrogen peroxide water.

[0218] [Example 19] The composite semipermeable membrane obtained in Example 1 was subjected to an immersion treatment in hydrogen peroxide water.

[0219] [Comparative Example 12] The composite semipermeable membrane obtained in Comparative Example 1 was subjected to immersion treatment in hydrogen peroxide solution.

[0220] Tables 1 and 2 show the structures of copolymers and other materials contained in the coating layer of the composite semipermeable membranes of the examples and comparative examples, and Table 3 shows the performance evaluation results for Examples 1-10 and Comparative Examples 1-6. Table 4 shows the performance evaluation results and ATR-IR measurement results for Examples 11-14 and Comparative Examples 7-9. Table 5 shows the performance evaluation results, ΔVYI, water modulus of elasticity, and ΔDYI for Examples 15-18 and Comparative Examples 10-11. Table 6 shows the performance evaluation results when immersion treatment in hydrogen peroxide solution was performed in Example 19 and Comparative Example 12. Note that "-" in the tables means not measured or not applicable.

[0221] [Table 1]

[0222] [Table 2]

[0223] [Table 3]

[0224] [Table 4]

[0225] [Table 5]

[0226] [Table 6]

[0227] As shown in Tables 3, 4, and 6, the composite semipermeable membrane according to this embodiment exhibits excellent chemical resistance. As shown in Table 5, the composite semipermeable membrane according to this embodiment exhibits excellent abrasion resistance. [Explanation of symbols]

[0228] 1 Composite semipermeable membrane 2 Support membrane 3 Separation functional layer 4 Covering layer 5. Peak Maximum Intensity 6. 80% of the peak maximum intensity 7. The wavewidth where the peak intensity is 80% of the maximum peak intensity w 80% 8 Inside the protruding part 9. Composite semipermeable membrane element 10 End plate 11 End plate 12 Supply side channel material 13 Permeate side channel material 14 Water collection pipe 15 Supply water 16 Permeated water 17 Concentrated water 18 weights 19 Polypropylene net 20 metal plate 21 Tensile testing machine 22 Pulleys

Claims

1. A porous support layer, A separation functional layer containing polyamide is provided on the porous support layer, The separation functional layer comprises a covering layer provided on the separation functional layer, The coating layer is a composite semipermeable membrane comprising a copolymer of a hydrophilic unit and a hydrophobic unit having a hydrogen bond acceptor with a polarization degree of 0.70 e or more and 1.00 e or less.

2. The composite semipermeable membrane according to claim 1, wherein the hydrophilic unit has hydrogen bond acceptors with a polarization degree of 0.58e or more and 1.00e or less.

3. The composite semipermeable membrane according to claim 1 or 2, wherein the copolymer is nonionic.

4. The composite semipermeable membrane according to claim 3, wherein the hydrophobic unit has a carbon chain with 4 or more carbon atoms in its main chain.

5. The composite semipermeable membrane according to claim 4, wherein the hydrophobic unit has a structure represented by the following general formula (I). 【Chemistry 1】 [In general formula (I), R １ R is a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted. ２ This is hydrogen, a hydrocarbon group having 2 or fewer carbon atoms, or a functional group having 2 or fewer carbon atoms.

6. The composite semipermeable film according to claim 4, wherein the copolymer consists only of non-halogen atoms.

7. The composite semipermeable membrane according to claim 5, wherein the hydrophilic unit has a structure represented by the following general formula (II). 【Chemistry 2】 [In general formula (II), R in each repeating unit ３ and R ４ Each of these is independently a hydrogen atom or a hydrocarbon group having 2 or fewer carbon atoms, and n is an integer of 1 or more.

8. The composite semipermeable membrane according to claim 7, wherein the hydrophilic unit has a carbon chain with 4 to 11 carbon atoms in its main chain.

9. The composite semipermeable membrane according to claim 8, wherein the hydrophilic unit has a structure represented by the following general formula (III). 【Transformation 3】 [In general formula (III), R ５ [This refers to a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted.]

10. The composite semipermeable membrane according to claim 9, wherein the copolymer has a structure represented by the following general formula (V). 【Chemistry 4】 [In General Formula (V), R １ and R ５ are each independently a hydrocarbon group having 4 to 11 carbon atoms which may be substituted, R ２ , R ６ and R ７ are each independently hydrogen, a hydrocarbon group having 2 or fewer carbon atoms, or a functional group having 2 or fewer carbon atoms, X is a structure containing the general formula (II), and r and q are each independently an integer of 1 or more.]

11. In the surface analysis of the coating layer by total internal reflection infrared absorption measurement, 1642–1662 cm －１ A peak originating from amide I is present, and The wavenumber width w is such that the peak intensity is 80% of the maximum peak intensity derived from the amide I. ８０％ 35.8 cm －１ 38.0cm or more －１ The composite semipermeable membrane according to claim 1 or 2, which is as follows:

12. w of the composite semipermeable membrane after immersion treatment in chlorine, alkali and acid ８０％ And the w of the composite semipermeable membrane before immersion treatment ８０％ That's the difference lol ８０％ The change is 2.0 cm. －１ The composite semipermeable membrane according to claim 11, which is as follows:

13. In the surface analysis of the coating layer by total internal reflection infrared absorption measurement, 1630 to 1710 cm －１ 2800-3000 cm² relative to the peak area A －１ The composite semipermeable membrane according to claim 11, wherein the ratio of peak area B to A is 0.60 or more and 0.85 or less.

14. The composite semipermeable membrane according to claim 1 or 2, wherein the degree of yellowing ΔDYI of the surface on the coating layer side before and after contact with Dragendorff's reagent is 43 or more and 150 or less.

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

16. A fluid separation device comprising a composite semipermeable membrane according to claim 1 or 2.

17. A fluid separation apparatus for use in ZLD or precision industries, comprising a composite semipermeable membrane as described in claim 1 or 2.

18. A coating agent for composite semipermeable membranes containing a polyamide in the separation functional layer, comprising a copolymer having a structure represented by the following general formulas (I) to (III). 【Transformation 5】 [In general formula (I), R １ R is a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted. ２ R is hydrogen or a hydrocarbon group having 2 or fewer carbon atoms or a functional group having 2 or fewer carbon atoms. In general formula (II), R in each repeating unit ３ and R ４ Each is independently a hydrogen atom or a hydrocarbon group having 2 or fewer carbon atoms, and n is an integer of 1 or more. In general formula (III), R ５ [This refers to a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted.]

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