Composite semi-permeable membrane, composite semi-permeable membrane element, fluid separation device, and coating agent for composite semi-permeable membrane

Abstract

One embodiment of the present invention relates to a composite semi-permeable membrane comprising: a porous support layer; a separation function layer that is provided on the porous support layer and that contains a polyamide; and a coating layer provided on the separation function layer. The coating layer contains a copolymer of a hydrophilic unit having a hydrogen bond acceptor with a polarization degree of from 0.70 e to 1.00 e.

Description

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

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

[0002] There are various techniques for removing substances (e.g., salts) dissolved in a solvent (e.g., water), 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.

[0006] International Publication No. 2024 / 162434

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

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

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

[0010] To achieve the above objectives, a first aspect of 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 comprises a copolymer of hydrophilic units and hydrophobic units having hydrogen bond acceptors with a polarization degree of 0.70e to 1.00e. [2] The composite semipermeable membrane according to [1], wherein the hydrophilic units have hydrogen bond acceptors with a polarization degree of 0.58e to 1.00e. [3] The composite semipermeable membrane according to [1] or [2], wherein the copolymer is nonionic. [4] The composite semipermeable membrane according to any one of [1] to [3], wherein the hydrophobic units have carbon chains with 4 or more carbon atoms in the main chain. [5] The composite semipermeable membrane according to [4], wherein the hydrophobic units have a structure represented by the following general formula (I).

[0011]

[0012] [In general formula (I), R １ R is a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted. ２ [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 one of [1] to [6] above, wherein the hydrophilic unit has a structure represented by the following general formula (II).

[0013]

[0014] [In general formula (II), R in each repeating unit ３ and R ４ are each independently hydrogen or a hydrocarbon group having 2 or less 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 having 4 to 11 carbon atoms in the main chain. [9] The composite semipermeable membrane according to any one of [1] to [8] above, wherein the hydrophilic unit has a structure represented by the following general formula (III).

[0015]

[0016] [In general formula (III), R ５ is a hydrocarbon group having 4 to 11 carbon atoms which may be substituted. ]

[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]

[0018] [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 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 on the coating layer side by total reflection infrared absorption measurement, a peak derived from amide I exists at 1642 to 1662 cm<00000l1>, and with respect to the maximum intensity of the peak derived from amide I, the width w ８０％ of the wave number at which the peak intensity is 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 difference w８０％ The change is 2.0 cm. －１ The composite semipermeable film described in any of [1] to

[11] above, which is as follows:

[13] 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 [1] A composite semipermeable membrane according to any one of [1] to

[12] above, wherein the ratio B / A of the peak area B 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 reagent is 43 or more and 150 or less.

[15] A composite semipermeable membrane element comprising the composite semipermeable membrane according to any one of [1] to

[14] above.

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

[14] above.

[17] A fluid separation device for use in ZLD or precision industry comprising the composite semipermeable membrane according to any one of [1] to

[14] above.

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

[0019]

[0020] [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.]

[0021] According to a first aspect of the present invention, a composite semipermeable film with good oxidation resistance, acid resistance, and alkali resistance can be provided.

[0022] Figure 1 is a cross-sectional view of a composite semipermeable film according to one embodiment of the present invention. Figure 2 shows the peaks 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. ８０％ 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 is an unfolded view of a composite semipermeable membrane element according to one embodiment of the present invention. Figure 5 is a schematic diagram of a scraping test. Figure 6 is a schematic diagram showing the method of setting up the composite semipermeable membrane in a scraping test.

[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] The first, second, and third embodiments of the present invention will be described in order below.

[0025] (First Embodiment) First, the first embodiment of the present invention will be described in detail. The composite semipermeable membrane according to the first embodiment of the present invention comprises 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.

[0026] 1. Composite Semipermeable Membrane Figure 1 shows a cross-sectional view of a composite semipermeable membrane 1 according to one embodiment of this model. 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.

[0027] 1.1 Coating Layer The coating layer of the composite semipermeable membrane of this embodiment is a layer responsible for protecting the separation functional layer and is disposed 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 0.70 e or more and 1.00 e or less. 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.

[0028] 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.

[0029] 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 an A-B copolymer 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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, 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.

[0034] 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.

[0035] 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.

[0036] The hydrophobic units of the copolymer contained in the coating layer of the composite semipermeable membrane according to this embodiment preferably have carbon chains with four 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 four 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 four or more carbon atoms in its main chain, and it is more preferable that all hydrophobic units have carbon chains with four or more carbon atoms in their main chain.

[0037] Examples of carbon chains with 4 to 11 carbon atoms include butylene groups (-C ４ H ８ -), pentylene group (-C ５ H １０ -), hexylene group (-C ６ H １２ -), heptylene group (-C ７ H １４ -), octylene group (-C) ８ H １６ -), nonylene group (-C ９ H １８ -), decilen group (-C １０ H ２０ -), undecylene group (-C １１ H ２２ -), dodecylene group (-C １２ H ２４ Hydrocarbons such as -), butenylene group (-C) ４ H ６ -), pentenylene group (-C ５ H ８ -), hexenylene group (-C ６ H １０ Hydrocarbons having an unsaturated structure such as -), cyclobutylene group (-C)４ H ６ -), cyclopentylene group (-C ５ H ８ -), cyclohexylene group (-C ６ H １０ Cyclic hydrocarbons such as -), phenylene group (-C) ６ H ４ Examples include aromatic ring hydrocarbons such as (-C). These carbon chains may be optionally substituted. In particular, the carbon chain may have a butylene group (-C). ４ H ８ -), pentylene group (-C ５ H １０ -), hexylene group (-C ６ H １２ -), phenylene group (-C ６ H ４ -) is preferable.

[0038] Furthermore, the hydrophobic unit preferably has a structure represented by the following general formula (I).

[0039]

[0040] In general formula (I), R １ R is a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted. ２ is hydrogen, a hydrocarbon group having 2 or fewer carbon atoms, or a functional group having 2 or fewer carbon atoms.

[0041] If the hydrophobic unit has a structure represented by the above general formula (I), R １ The hydrocarbon group represented by corresponds to the carbon chain with four or more carbon atoms and the carbonyl portion of the amide group, which are hydrogen bond acceptors with a polarization degree of 0.70e to 1.00e. 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 film with excellent chemical resistance. R in general formula (I) １ If the number of carbon atoms is 4 or more, sufficient hydrophobic interaction is 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. R in general formula (I) １ The number of carbon atoms is preferably 4 to 10, more preferably 4 to 8, and even more preferably 4 to 6. R in general formula (I)２ The functional group is preferably hydrogen, a hydrocarbon group such as a methyl group or ethyl group, or a methoxymethyl group, with hydrogen being more preferred. ２ If the above conditions are met, 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. 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). Furthermore, it is even more preferable that the hydrophobic units have the structure represented by the general formula (I).

[0042] 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).

[0043]

[0044] 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.

[0045] 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 from the viewpoint of forming hydrogen bonds between the hydrophilic unit in the copolymer and the polyamide, and of hydrophobic interaction being at work, R ３ and R ４ Hydrogen or a methyl group is preferred. 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.

[0046] The hydrophilic unit preferably has a carbon chain with 4 to 11 carbon atoms in the main chain. When the number of carbon atoms in the carbon chain is 4 or more, a strong hydrophobic interaction occurs between the copolymer and the polyamide, improving the chemical resistance of the composite semipermeable membrane. Also, when the number of carbon atoms in the carbon chain is 11 or less, the solubility of the copolymer in a water-soluble solvent increases, and it becomes 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 either linear or cyclic and may have an unsaturated bond.

[0047] Further, it is also preferable that the hydrophilic unit has a structure represented by the following general formula (III). That is, as the structure represented by the general formula (III), the hydrophilic unit preferably has a hydrocarbon group with 4 to 11 carbon atoms as a carbon chain in the main chain.

[0048]

[0049] In the general formula (III), R ５ is a hydrocarbon group with 4 to 11 carbon atoms that may be substituted.

[0050] By having the structure represented by the above general formula (III), a strong hydrogen bond can be formed between the copolymer having a highly polar carbonyl group and the polyamide.

[0051] R ５ preferably has 4 to 10 carbon atoms in the hydrocarbon group, more preferably 4 to 8 carbon atoms, and even more preferably 4 to 6 carbon atoms. When R ５ is a hydrocarbon group with 4 to 11 carbon atoms, a hydrophobic interaction occurs between the hydrophilic unit in the copolymer and the polyamide. Preferred structures of R ５ include, for example, a butylene group (—C ４ H ８ —), a pentylene group (—C ５ H １０ —), a hexylene group (—C ６ H １２ —), a heptylene group (—C ７ H １４ —), an octylene group (—C ８ H １６ —), a nonylene group (—C９ H １８ -), hydrocarbon groups such as decylene group (-C １０ H ２０ -), hydrocarbon having an unsaturated structure such as butenylene group (-C ４ H ６ -), pentenylene group (-C ５ H ８ -), hexenylene group (-C ６ H １０ -), cyclic hydrocarbon such as cyclobutylene group (-C ４ H ６ -), cyclopentylene group (-C ５ H ８ -), cyclohexylene group (-C ６ H １０ -), aromatic ring hydrocarbon such as phenylene group (-C ６ H ４ -). These carbon chains may be substituted with any functional group such as a hydroxyl group. Among them, R ５ is preferably a butylene group (-C ４ H ８ -), pentylene group (-C ５ H １０ -), hexylene group (-C ６ H １２ -), or phenylene group (-C ６ H ４ -).

[0052] Furthermore, the hydrophilic unit is more preferably a structure represented by the following general formula (IV).

[0053]

[0054] In the general formula (IV), X is a structure including the above general formula (II), R ５ is a hydrocarbon group having 4 to 11 carbon atoms which may be substituted, and R ６ and R ７ are each independently hydrogen, a hydrocarbon group having 2 or less carbon atoms, or a functional group having 2 or less carbon atoms. The preferred carbon number and specific examples of the hydrocarbon group of R ５ are as described above for the general formula (III). R ６ and R ７Because the interaction with the amide group of the crosslinked polyamide in the separation functional layer is good, hydrogen or a C1 hydrocarbon group with low steric hindrance is preferred, and hydrogen is more preferred.

[0055] 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).

[0056] 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).

[0057]

[0058] In general formula (V), R １ and R ５ Each of these is a hydrocarbon group having 4 to 11 carbon atoms, which may be independently substituted, and R ２ , R ６ and R ７ Each of them is independently a hydrogen atom or a hydrocarbon group having 2 or fewer carbon atoms or a functional group having 2 or fewer carbon atoms, X is a structure containing the above general formula (II), and r and q are each independently an integer of 1 or more. １ and R ２ The preferred form is as described above for the general formula (I). ５ The preferred form is as described above for the general formula (III). ６ and R ７ The preferred form is as described above with respect to the general formula (IV).

[0059] 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 hinder the effects of this embodiment. 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.

[0060] 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.

[0061] 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, if halogen atoms are located near hydrogen bond acceptors, they affect the degree of polarization. In addition, halogen atoms hydrolyze in water, releasing halogen atoms into the water, which raises concerns about water pollution.

[0062] 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.

[0063] 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 into water from the polyamide separation functional layer. 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.

[0064] The copolymer contained in the coating layer of the composite semipermeable membrane according to this embodiment preferably has a mass ratio of hydrophilic units to hydrophobic units of 1 or more and 100 or less, more preferably 1 or more and 50 or less, and even more preferably 1 or more and 20 or less. 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 contained in the coating layer and the polyamide, 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] The composite semipermeable film according to this embodiment exhibits a surface analysis of the coating layer side by total internal reflection infrared absorption measurement (hereinafter referred to as "ATR-IR"), with a reading of 1642 to 1662 cm⁻¹. －１It is preferable that a peak originating from amide I (hereinafter also referred to as the "amide I peak") is present.

[0069] 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 The peak is detected between these two points, mainly at 1664 cm. －１ A peak is detected in the vicinity.

[0070] In the composite semipermeable membrane according to this embodiment, the peak of 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.

[0071] 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: 1645 cm －１ The above is 1662cm. －１ More preferably, the following is true: 1648 cm －１ The above is 1662cm. －１ It is even more preferable that the peak position of amide I is 1662 cm. －１ When the following conditions are met, 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.

[0072] Furthermore, the composite semipermeable membrane according to this embodiment is w ８０％ 35.8 cm －１ 38.0cm or more －１ The following is preferable, w ８０％ 35.8 cm －１ 37.0cm or more－１ It is more preferable that the following be the case: 35.8 cm －１ Above, 36.5cm －１ The following is even more preferable. Note that the lol here ８０％ This refers to the saturation process described later. ８０％ It means...

[0073] Peak originating from amide I ８０％ Regarding the maximum peak intensity 5 shown in Figure 2, the wavenumber width w at 80% of the maximum peak intensity (6) is the value where the peak intensity is 80% of the maximum peak intensity. ８０％ This is the value shown in (7).

[0074] lol 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 become broader 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.

[0075] lol ８０％ 35.8 cm －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. Also, w ８０％ 38.0 cm －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.

[0076] 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.

[0077] The composite semipermeable membrane according to this embodiment is subjected to the following treatments: immersion in a 100 ppm, pH 7.0, 25°C sodium hypochlorite aqueous solution for 20 hours; then immersion in a sodium hydroxide aqueous solution prepared to 25°C, pH 13.0 for 20 hours; and finally 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") after the 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:

[0078] 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 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.

[0079] lol ８０％ The change is 2.0 cm. －１ The following conditions are met, as the copolymer contained in the coating layer interacts sufficiently with the amide groups of the polyamide, resulting in excellent chemical resistance. ８０％ The lower limit of the range of change is effectively 0 cm. －１ That is the case.

[0080] The composite semipermeable membrane according to this embodiment is w after immersion treatment. ８０％ 36.0 cm －１ 40.0cm or more－１ Preferably, it is 37.0 cm. －１ 39.0cm or more －１ The following is more preferable: If the interaction between the copolymer contained in the coating layer and the amide groups of the polyamide is strong, the interaction between the copolymer contained in the coating layer and the amide groups of the polyamide is maintained even after the immersion treatment. Therefore, w after the immersion treatment ８０％ If the range is within the above limits, it is possible to achieve both excellent membrane permeation flux and chemical resistance.

[0081] lol ８０％ The range of change and w after immersion treatment ８０％ This 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 functional groups that strongly interact with the amide group of the polyamide include the hydrogen bond acceptors mentioned above.

[0082] The composite semipermeable film according to this embodiment showed a surface analysis of the coating layer side by ATR-IR, with a value of 1630 to 1710 cm². －１ 2800-3000 cm² relative to the peak area A －１ The ratio of peak area B to A in the given region, B / A, is preferably 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.

[0083] Typically, in composite semipermeable membranes with a separation functional layer containing polyamide on a porous support layer, the hydrocarbon groups cause a 2800-3000 cm⁻¹ －１ The peak area B in this region is 1630–1710 cm², which originates from amide I. －１ It is relatively small compared to the peak area A, and the area ratio B / A is less than 0.60. By providing a covering layer, it is 2800-3000 cm －１ When 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.

[0084] 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 is formed on the polyamide by using a Dragendorff reagent or the like.

[0085] 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 shows a density of 1200 to 1270 cm². －１ The peak area C derived from PSf is 1630–1710 cm², which is 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.

[0086] 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.

[0087] 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.

[0088] In addition, the above PSf is 1200-1270 cm －１ 1520–1560 cm² relative to the peak area C －１ The ratio D / C of the peak area D is preferably 0.23 or more and 0.40 or less, and more preferably 0.24 or more and 0.30 or less.

[0089] 1520-1560cm －１The peak that appears is a peak originating from the C-N-H bending angle of the amide bond (hereinafter referred to as "amide II"). When the above area ratio D / C is 0.23 or higher, the copolymer contained in the coating layer and the amide groups of the polyamide form an interaction, resulting in excellent chemical resistance. Furthermore, when the above area ratio D / C is 0.40 or lower, the decrease in membrane permeation flux due to the formation of the coating layer can be suppressed. In this case, the copolymer contained in the coating layer has sufficient primary and secondary amides, and the interaction with the amide bonds of the polyamide works sufficiently, improving chemical resistance.

[0090] In the composite semipermeable membrane according to this embodiment, the degree of yellowing ΔVYI of the surface on the coating layer side before and after contact with the vanillin solution is preferably 5 to 23, more preferably 7 to 20, and even more preferably 12 to 20. The amino groups such as polyamide terminals contained in the separation functional layer form a color-developing chemical structure through a chemical reaction with vanillin. That is, the degree of yellowing 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, the copolymer contained in the coating layer forms hydrogen bonds with the amino groups on the surface of the separation functional layer, which reduces the number of amino groups that chemically react with vanillin and thus reduces ΔVYI. Also, as the thickness of the coating layer increases, contact of vanillin with the separation functional layer is inhibited, so ΔVYI decreases.

[0091] 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, thus reducing the performance degradation due to abrasion. Furthermore, when ΔVYI is 5 or more, the reduction in film permeation flux due to the introduction of an excessive coating layer can be suppressed. The degree of yellowing ΔVYI on the surface of the coating layer is calculated using the method described in "Coloring with Vanillin" in the examples described later.

[0092] 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.

[0093] In this embodiment, the composite semipermeable membrane preferably has a degree of yellowing ΔDYI of the surface on the coating layer side before and after contact with Dragendorff's reagent of 43 or more and 150 or less. Dragendorff's reagent reacts specifically with tertiary and quaternary amines and polyethylene glycol structures, resulting in coloration. Therefore, the degree of yellowing ΔDYI of the surface on the coating layer side 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).

[0094] When ΔDYI is 43 or higher, a sufficient amount of coating layer is formed, thereby reducing the deterioration 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 55 to 140, and even more preferably 60 to 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.

[0095] 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 of elasticity" 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 elastic modulus of the surface of the coating layer is calculated using the method described in "Underwater Elastic Modulus" in the examples described later.

[0096] 1.2 Porous Support Layer The composite semipermeable membrane of this embodiment comprises 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.

[0097] 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.

[0098] The porous support layer has a large number of 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.

[0099] As the material for the porous support layer, homopolymers (homopolymers) or copolymers of polysulfone (hereinafter referred to as "PSf"), polyethersulfone, polyamide, polyester, cellulose polymers, vinyl polymers, polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfone, and polyphenylene oxide can be used alone or in blends. Here, examples of cellulose polymers include cellulose acetate and cellulose nitrate. Examples of vinyl polymers include polyethylene, polypropylene, polyvinyl chloride, and polyacrylonitrile. Among these, homopolymers or copolymers of PSf, polyamide, polyester, cellulose acetate, cellulose nitrate, polyvinyl chloride, polyacrylonitrile, polyphenylene sulfide, polyphenylene sulfide sulfone, and polyphenylene sulfone are preferred, with PSf, cellulose acetate, polyphenylene sulfide sulfone, or polyphenylene sulfone being more preferred. PSf is particularly preferred because it has high chemical, mechanical, and thermal stability and is easy to mold.

[0100] 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.

[0101] The thickness of the substrate and the porous support layer affects the strength of the composite semipermeable membrane and the packing density when it is used as a composite semipermeable membrane element. To obtain good mechanical strength and packing density, the combined thickness of the substrate and the porous support layer is preferably 50 μm to 300 μm, and more preferably 100 μm to 250 μm. Furthermore, the thickness of the porous support layer is preferably 20 μm to 100 μm. The thickness of the substrate and the porous support layer is the average value of 20 thicknesses measured at 20 μm intervals in a direction perpendicular to the thickness direction (the surface direction of the membrane) during cross-sectional observation.

[0102] 1.3 Separation Functional Layer The separation functional layer of the composite semipermeable membrane of this embodiment is a layer responsible for the separation of solutes 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. The proportion of polyamide in the separation functional layer is more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0103] 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.

[0104] "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.

[0105] "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.

[0106] A "polyfunctional amine" refers to an amine having at least two primary amino groups and / or secondary amino groups in one 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.

[0107] 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.

[0108] 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.

[0109] From the viewpoint of the separation performance and heat resistance of the composite semipermeable membrane, polyfunctional acid halides are preferably polyfunctional aromatic acid chlorides having 2 to 4 chlorocarbonyl groups in one molecule. Among these, TMC is particularly preferred from the viewpoint of ease of availability and ease of handling.

[0110] 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.

[0111] 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.

[0112] 1.4 Composite Semipermeable Membrane Element The composite semipermeable membrane element according to this embodiment comprises the composite semipermeable membrane according to this embodiment. An example of the configuration of the composite semipermeable membrane element will be described with reference to Figure 4.

[0113] As shown in Figure 4, the composite semipermeable membrane element 9 comprises a composite semipermeable membrane 1, a supply-side channel material 12, a permeable-side 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. For the supply-side channel material 12, a net is preferred, for example. 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 protrusion-fixing sheet can be used, for example. The water collection pipe 14 is a hollow cylindrical member having a plurality of holes on its side. The end plates 10 and 11 are disc-shaped members having a plurality of supply ports (or discharge ports).

[0114] 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 has permeated 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 has not permeated 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.

[0115] 2. Method for Manufacturing a Composite Semipermeable Film The method for manufacturing a composite semipermeable film according to one embodiment of this embodiment is not particularly limited as long as a composite semipermeable film satisfying the desired features described above can be obtained, but for example, it can be manufactured by the following method.

[0116] 2.1 Formation of the Support Film Known methods can be suitably used for forming the support film. The following description will take the case where PSf is used as the material for the porous support layer as an example.

[0117] First, PSf is dissolved in a suitable solvent to prepare a porous support layer stock solution. DMF is a preferred suitable solvent for PSf.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] The resulting support film may be washed before the formation of the separation functional layer to remove any remaining solvent in the film.

[0122] 2.2 Formation Process of the Separation Functional Layer A method for forming a separation functional layer containing polyamide will be described using 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 the Support Film". As a polymerization method, interfacial polymerization is the most preferred method from the viewpoint of productivity and performance. The interfacial polymerization process will be described below.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] Furthermore, if necessary, the support film in contact with the organic solvent solution of the polyfunctional acid halide may be heat-treated. When heat-treated, the heating temperature is preferably 35°C to 180°C, more preferably 50°C to 160°C, and even more preferably 60°C to 150°C. The optimal heating time varies depending on the temperature of the film surface, which is the reaction site, but is preferably 5 seconds or more, and more preferably 10 seconds or more.

[0133] In step (c), the organic solvent solution on the composite semipermeable membrane after the polymerization reaction is removed by dewatering. Methods for dewatering include, for example, gripping the membrane vertically and allowing the excess organic solvent solution to flow down naturally; blowing air with a fan to dry and remove the organic solvent; or removing the excess organic solvent solution with a mixed fluid of water and air.

[0134] 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.

[0135] 2.3 Formation of the coating layer The composite semipermeable film processed in this step may be an unused film or a film that has deteriorated due to use or other factors. Furthermore, this step can be considered as one of the manufacturing steps for the composite semipermeable film.

[0136] The process for forming the coating layer 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.

[0137] 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.

[0138] 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.

[0139] It is preferable to uniformly and continuously bring a 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 onto the separation functional layer. Specifically, for example, one method is to coat the separation functional layer with the solution. The contact time between the separation functional layer and the solution is preferably 5 seconds to 10 hours, and more preferably 10 seconds to 1 hour.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] 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, these elements can be connected in series or parallel and housed in a pressure vessel to form a composite semipermeable membrane module.

[0145] 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.

[0146] 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).

[0147] 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.

[0148] When a composite semipermeable membrane is used as a reverse osmosis membrane, the NaCl removal rate is preferably 99.0% or higher, more preferably 99.30% or higher, and even more preferably 99.50% or higher. The membrane permeation flux is preferably 0.5 m / d or more and 1.8 m / d or less, more preferably 0.7 m / d or more and 1.8 m / d or less, and even more preferably 1.0 m / d or more and 1.8 m / d or less. The chemical resistance of the composite semipermeable membrane in this specification refers to a small difference in membrane performance before and after the degradation test in 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, the SP ratio, which is the ratio of NaCl permeability before and after immersion treatment in hydrogen peroxide solution, is preferably 7.0 or less, more preferably 6.5 or less, and even more preferably 6.0 or less. In addition, 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 preferably 1.7 or less, more preferably 1.6 or less, and even more preferably 1.5 or less.

[0149] From the viewpoint of reducing environmental impact and effectively utilizing water resources, it is preferable that the fluid separation device be applicable to zero-liquid discharge systems (hereinafter referred to as "ZLD") and resource recovery applications. In ZLD, wastewater is concentrated using membrane separation technology, and then subjected to evaporation and drying treatment. Because the wastewater is concentrated to the extreme, foulants in the feedwater are concentrated, making fouling likely to occur. Furthermore, since fouling is eliminated by frequent chemical cleaning, it is preferable to use a composite semipermeable membrane with excellent chemical resistance. In ZLD, it is preferable to equip the upstream with a UF membrane device, as this allows for efficient removal of foulants. Industries in which ZLD is introduced include, for example, semiconductor and electronic component manufacturing, chemical industry, thermal power plants, and dyeing and textile factories. Since the wastewater from these industries may have a temperature of 35°C or higher, it is preferable that the fluid separation device used in ZLD can be used under conditions where the feedwater temperature is 35°C or higher. When the feedwater is at a high temperature of 35°C or higher, the deterioration of the composite semipermeable membrane equipped in the fluid separation device is accelerated, which is a problem. In resource recovery applications, useful components are concentrated from factory wastewater and other sources using membrane separation technology, and then recovered by sedimentation or adsorption. In this process, the treated water may contain acidic or alkaline substances and oxidizing agents, making composite semipermeable membranes prone to degradation. Therefore, it is preferable to use composite semipermeable membranes with excellent chemical resistance.

[0150] 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, and is therefore preferably used in fluid separation devices for ZLD and resource recovery.

[0151] Furthermore, from the viewpoint of improving yield and reliability in the manufacturing process, fluid separation devices are preferably applicable to precision industries that use high-purity water and chemicals, such as semiconductor manufacturing. Examples of precision industries include the pharmaceutical and biopharmaceutical manufacturing fields where high purity of raw materials and solvents is required; the electronic and optical materials manufacturing fields where impurity control is required to maintain optical and electrical properties; the nuclear-related fields where the purity of chemicals and water affects the behavior of radioactive materials; and high-precision analytical fields such as mass spectrometry and chromatography, where the purity of reagents and solvents directly affects analytical accuracy. For example, hydrogen peroxide, one of the chemicals used for cleaning in the semiconductor manufacturing process, is generally synthesized and then purified by a method that utilizes the oxidation-reduction reaction of anthraquinones in an organic solvent. Impurities remaining in these manufacturing processes cause a decrease in semiconductor manufacturing yield, so it is preferable that they be removed in the purification process.

[0152] The composite semipermeable membrane according to this embodiment has excellent oxidation resistance, acid resistance, and alkali resistance, and is therefore less susceptible to degradation caused by chemicals present in the liquid supplied to the composite semipermeable membrane. As a result, water and chemicals such as hydrogen peroxide can be effectively separated from impurities in the composite semipermeable membrane, and the quality of the permeate during operation is stable, making it suitable for use in fluid separation equipment for the purification of water and chemicals used in precision industries.

[0153] 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, so they can be used as coating agents for composite semipermeable membranes to improve the chemical resistance of composite semipermeable membranes containing polyamides in the separation functional layer.

[0154] 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).

[0155] The coating agent may contain other components, such as crosslinking agents, to the extent that they do not interfere with the effects of this embodiment.

[0156] (Second aspect) Next, a second aspect of the present invention will be described in detail.

[0157] A second aspect of the present invention aims to provide a composite semipermeable film with good oxidation resistance, acid resistance, and alkali resistance.

[0158] To achieve the above objective, a second aspect of the present invention includes the following configurations [B1] to [B13]: [B1] comprising a porous support layer, a separation functional layer containing a crosslinked aromatic polyamide provided on the porous support layer, and a coating layer provided on the separation functional layer, wherein surface analysis of the coating layer side by total internal reflection infrared absorption measurement shows 1642 to 1662 cm⁻¹ －１ A peak originating from amide I exists, and the wavenumber width w is such that the peak intensity is 80% of the maximum intensity of the peak originating from amide I. ８０％ 35.8 cm －１ 38.0cm or more －１ The following is a composite semipermeable film. [B2] In surface analysis of the above 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 film according to [B1] above, wherein the area ratio B / A of the peak area B is 0.60 or more and 0.85 or less. [B3] The porous support layer contains polysulfone, and in surface analysis of the coating layer side by total internal reflection infrared absorption measurement, 1200 to 1270 cm －１ The peak area C derived from the polysulfone is 1630-1710 cm², while the peak area C derived from the amide I is 1630-1710 cm². －１ The composite semipermeable film according to [B1] or [B2] above, wherein the area ratio A / C of the peak area A is 0.30 or more and 0.50 or less. [B4] Surface analysis of the coating layer side by total internal reflection infrared absorption measurement, 1200 to 1270 cm －１ The peak area C derived from polysulfone is 1520–1560 cm². －１ The composite semipermeable membrane described in [B3] above, wherein the area ratio D / C of the peak area D is 0.23 or more and 0.40 or less. [B5] The composite semipermeable membrane after immersion treatment in chlorine, alkali and acid w ８０％ And the w of the above composite semipermeable membrane before immersion treatment ８０％ That's the difference lol８０％ The change is 2.0 cm. －１ The composite semipermeable membrane described in any of [B1] to [B4] above, which is as follows: [B6] The composite semipermeable membrane after immersion treatment in chlorine, alkali and acid. ８０％ And the w of the above composite semipermeable membrane before immersion treatment ８０％ That's the difference lol ８０％ The change is 2.0 cm. －１ The composite semipermeable membrane described in [B4] above is as follows: [B7] w of the composite semipermeable membrane after immersion treatment in chlorine, alkali and acid. ８０％ 36.0 cm －１ 40.0cm or more －１ The composite semipermeable membrane according to any of [B1] to [B6] above, which is as follows: [B8] The composite semipermeable membrane according to any of [B1] to [B7] above, wherein the coating layer contains a polymer having a structure represented by the following general formula (I).

[0159]

[0160] [In general formula (I), R １ R is a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted. ２ [B9] The composite semipermeable membrane according to any one of [B1] to [B8] above, wherein the coating layer contains a polymer having a structure represented by the following general formula (II).

[0161]

[0162] [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. [B10] The composite semipermeable membrane according to [B9] above, wherein the coating layer contains a polymer having a structure represented by the following general formula (IV).

[0163]

[0164] [In general formula (IV), X is a structure that includes the above general formula (II), and R ５ R is a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted. ６ and R７ Each of these is independently hydrogen or a hydrocarbon group having 2 or fewer carbon atoms or a functional group having 2 or fewer carbon atoms. [B11] The composite semipermeable membrane according to [B10], wherein the coating layer contains a polymer having a structure represented by the following general formula (V).

[0165]

[0166] [In general formula (V), R １ and R ５ Each of these is a hydrocarbon group having 4 to 11 carbon atoms, which may be independently substituted, and R ２ , R ６ and R ７ Each is independently hydrogen or 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 above general formula (II), and r and q are each independently an integer of 1 or more. ] [B12] A composite semipermeable membrane element comprising the composite semipermeable membrane described in any of [B1] to [B11] above. [B13] A fluid separation device comprising the composite semipermeable membrane described in any of [B1] to [B11] above.

[0167] B1. Composite semipermeable membrane The composite semipermeable membrane of this embodiment comprises a porous support layer, a separation function layer provided on the porous support layer, and a coating layer provided on the separation function layer. 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.

[0168] B1.1 Coating Layer The coating layer of the composite semipermeable membrane according to this embodiment is a layer responsible for protecting the separation function layer and is arranged on the separation function layer. The coating layer of this embodiment contains a polymer in which a large number of monomers (hereinafter also referred to as "monomers") are linked together. A monomer unit is a part derived from individual monomers within a polymer. The polymer forming the coating layer of this embodiment is a polymer (polymer) formed from two or more monomer units. The polymer forming the coating layer may be a random copolymer, an alternating copolymer, or a block copolymer. In addition, the coating layer may contain other components to the extent that it does not hinder the effects of this embodiment.

[0169] The composite semipermeable film according to this embodiment exhibits a surface analysis of the coating layer side by total internal reflection infrared absorption measurement (hereinafter referred to as "ATR-IR"), with a reading of 1642 to 1662 cm⁻¹.－１ A peak originating from amide I (hereinafter also referred to as the "amide I peak") is present.

[0170] As a result of diligent research, the inventors provided a coating layer on a separation functional layer containing a crosslinked aromatic polyamide, and in surface analysis of the coating layer side by ATR-IR, the position of the peak originating from amide I was 1642 cm². －１ The above is 1662cm. －１ We found that by following the procedure described below, a composite semipermeable film with good oxidation resistance, acid resistance, and alkali resistance can be obtained. The technical explanation regarding the "peak derived from amide I," as well as the preferred range of peak positions and the reasons for this, can be directly applied from the information provided for the first embodiment.

[0171] Furthermore, as shown in Figure 2, the composite semipermeable membrane has a wavenumber width w where the peak intensity is 80% of the maximum peak intensity derived from amide I. ８０％ 35.8 cm －１ 38.0cm or more －１ It is as follows: w ８０％ 35.8 cm －１ 37.0cm or more －１ The following is preferable: 35.8 cm －１ Above, 36.5cm －１ The following is preferable. Note that w ８０％ The technical explanation, preferred scope, and reasons therefor regarding this matter can be directly applied to the matters described in the first embodiment.

[0172] The peak position and w of amide I ８０％ This can be controlled, for example, by the structure of the polymer contained in the coating layer. For example, when a coating layer is formed using a polymer containing amide bonds in its repeating units, hydrogen bonds are formed between the amide groups of the crosslinked aromatic polyamide and the amide groups of the polymer forming 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 carboxyl groups, aldehyde groups, ester groups, amide groups, urethane groups, urea groups and other carbonyl groups, nitro groups, phosphoryl groups, sulfo groups, and sulfoxy groups.

[0173] The composite semipermeable membrane according to this embodiment is a 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 Preferably, it is 1.8 cm. －１ The following is more preferable: Immersion treatment in chlorine, alkali and acid (hereinafter also referred to as "immersion treatment") means 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. ８０％ The technical explanation regarding the range of change, as well as the preferred range and the reasons therefor, can be directly applied from the information provided for the first embodiment.

[0174] lol ８０％ The range of change and w after immersion treatment with chlorine, alkali and acid ８０％ This can be controlled, for example, by designing the polymer contained in the coating layer and adjusting the strength of the interaction between the polymer contained in the coating layer and the amide group of the crosslinked aromatic polyamide. Examples of functional groups that strongly interact with the amide group of the crosslinked aromatic polyamide include carboxyl groups, aldehyde groups, ester groups, amide groups, urethane groups, urea groups and other carbonyl groups, nitro groups, phosphoryl groups, sulfo groups, sulfoxy groups, and the like.

[0175] Furthermore, the composite semipermeable membrane according to this embodiment preferably satisfies one or more of the following requirements, in the same manner as the composite semipermeable membrane according to the first embodiment. (2-1) The composite semipermeable membrane according to this embodiment has a surface analysis of the coating layer side by ATR-IR, with a density of 1630 to 1710 cm². －１ 2800-3000 cm² relative to the peak area A －１The ratio of peak area B in the above region, B / A, is preferably 0.60 or more and 0.85 or less, more preferably 0.60 or more and 0.80 or less, even more preferably 0.65 or more and 0.80 or less, and particularly preferably 0.65 or more and 0.75 or less. (2-2) 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 shows that 1200 to 1270 cm －１ The peak area C derived from PSf is 1630–1710 cm², which is derived from amide I. －１ The ratio A / C of the peak area A is preferably 0.30 or more and 0.50 or less, and more preferably 0.30 or more and 0.35 or less.

[0176] (2-3) 1200-1270 cm derived from the above PSf －１ 1520–1560 cm² relative to the peak area C －１ The area ratio D / C of the peak area D is preferably 0.23 or more and 0.40 or less, more preferably 0.24 or more and 0.35 or less, and even more preferably 0.24 or more and 0.30 or less. (2-4) The coating layer of the composite semipermeable membrane according to this embodiment is preferably insolubilized so as not to leach out when the composite semipermeable membrane is used.

[0177] The polymer contained in the coating layer of the composite semipermeable membrane according to this embodiment is preferably water-soluble or soluble in water-soluble solvents. By the polymer being water-soluble or soluble in water-soluble solvents, a coating layer containing the 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.

[0178] B1.1.1 Polymer contained in the coating layer The coating layer of the composite semipermeable membrane according to this embodiment preferably contains a polymer having a structure represented by the following general formula (I).

[0179]

[0180] In general formula (I), R １ R is a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted. ２ is hydrogen, a hydrocarbon group having 2 or fewer carbon atoms, or a functional group having 2 or fewer carbon atoms.

[0181] When the polymer contained in the coating layer has the structure represented by the above general formula (I), it has hydrocarbon groups with 4 to 11 carbon atoms, so the temperature is 1630 to 1710 cm. －１ 2800-3000 cm² relative to the peak area A －１ The ratio B / A of the peak area B in the above can be controlled. When the polymer has the structure represented by the above general formula (I), not only does hydrophobic interaction by hydrocarbon groups act between the coating layer and the crosslinked aromatic polyamide as described above, but hydrogen bonds are also formed between the carbonyl of the amide group and the crosslinked aromatic polyamide, so a composite semipermeable film with excellent chemical resistance can be obtained. Note that R in the above general formula (I) １ and R ２ The preferred embodiments and the reasons therefor can be found by directly applying the explanation in the first embodiment.

[0182] The coating layer of the composite semipermeable membrane according to this embodiment preferably contains a polymer having a structure represented by the following general formula (II).

[0183]

[0184] 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.

[0185] When the polymer contained in the coating layer has the structure represented by the above general formula (II), the alkylene portion has one of the following: ethylene glycol portion, propylene glycol portion, or trimethylene glycol portion, therefore, 1630 to 1710 cm－１ 2800-3000 cm² relative to the peak area A －１ The area ratio B / A of the peak area B can be controlled.

[0186] The polymer having the structure represented by the above general formula (II) is soluble in water-soluble solvents, and the polymer contained in the coating layer and the polyamide can form hydrogen bonds. Note that R in the above general formula (II) ３ and R ４ The preferred embodiments and reasons for each can be found by directly applying the explanation in the first embodiment. Here, when n is an integer of 5 or more, in addition to hydrophobic interactions, more hydrogen bonds are formed between the ether group of the polymer and the crosslinked aromatic polyamide, thus improving chemical resistance.

[0187] Furthermore, the composite semipermeable membrane according to this embodiment preferably contains a polymer having a structure represented by the following general formula (IV).

[0188]

[0189] In general formula (IV), X is a structure that includes the above general formula (II), and R ５ R is a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted. ６ , R ７ Each of these is independently a hydrogen atom, a hydrocarbon group having 2 or fewer carbon atoms, or a functional group having 2 or fewer carbon atoms. １ and R ２ The preferred form is as described above for the general formula (I). ５ , R ６ and R ７ A preferred form is as described above for general formula (III) as explained in the first embodiment.

[0190] When the polymer has the structure represented by the above general formula (IV), it has a primary amide and a secondary amide, so the range is 1200 to 1270 cm. －１ The peak area C derived from PSf is 1630–1710 cm², which is derived from amide I. －１ The ratio of peak area A to C and the 1200–1270 cm² derived from PSf －１1520–1560 cm² relative to the peak area C －１ The ratio D / C of the peak area D can be controlled. Because the polymer has primary and secondary amides and also has alkylene moieties, strong hydrogen bonds are formed between the polymer contained in the coating layer and the crosslinked aromatic polyamide, and strong hydrophobic interactions occur, resulting in a composite semipermeable film with excellent chemical resistance.

[0191] In this embodiment, it is even more preferable that the coating layer contains a polymer having a structure represented by the following general formula (V).

[0192]

[0193] In general formula (V), R １ and R ５ Each of these is a hydrocarbon group having 4 to 11 carbon atoms, which may be independently substituted, and R ２ , R ６ and R ７ Each of them is independently a hydrogen atom or a hydrocarbon group having 2 or fewer carbon atoms or a functional group having 2 or fewer carbon atoms, X is a structure containing the above general formula (II), and r and q are each independently an integer of 1 or more. １ and R ２ The preferred form is as described above for the general formula (I). ５ , R ６ and R ７ The preferred form is as described above with respect to the general formula (IV).

[0194] When the polymer contained in the coating layer has the structure represented by general formula (V), it possesses all the structures represented by general formulas (I), (II), and (IV). As a result, the hydrogen bonding and hydrophobic interactions between the polymer contained in the coating layer and the crosslinked aromatic polyamide become even stronger, and a composite semipermeable film with high chemical resistance is obtained.

[0195] B1.2 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 function layer and do not substantially have solute separation performance themselves. The details of the porous support layer in this embodiment are the same as the details of the porous support layer in the first embodiment described above.

[0196] B1.3 Separation Functional Layer The separation functional layer of the composite semipermeable membrane of this embodiment is a layer responsible for the separation of solutes and contains a crosslinked aromatic polyamide. It is more preferable that the separation functional layer is mainly composed of a crosslinked aromatic polyamide. "Mainly composed of a crosslinked aromatic polyamide" means that the proportion of crosslinked aromatic polyamide in the separation functional layer is 50% by mass or more. It is more preferable that the proportion of crosslinked aromatic polyamide in the separation functional layer is 80% by mass or more, and even more preferable that it is 90% by mass or more.

[0197] "Cross-linked aromatic polyamide" refers to a polycondensate of a polyfunctional amine and a polyfunctional aromatic acid halide, meaning that the polyamide forms a cross-linked structure. For further details, the matters described in the first embodiment can be appropriately referenced.

[0198] B2. Method for Manufacturing a Composite Semipermeable Membrane The method for manufacturing the composite semipermeable membrane according to this embodiment 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.

[0199] B2.1 Support film formation process Known methods can be suitably used for the support film formation process, and specifically, the method described in detail in the first embodiment can be applied in the same manner.

[0200] B2.2 Formation process of the separation functional layer The method specifically described in the first embodiment can be applied in the same manner to the formation process of the separation functional layer.

[0201] B2.3 Process for Forming the Coating Layer The process for forming the coating layer can be similarly applied to the method specifically described in the first embodiment. However, in this embodiment, the polymer used to form the coating layer is the polymer described in the "B1.1 Coating Layer" section above.

[0202] B3. Use of Composite Semipermeable Membranes The matters described in the first embodiment can be appropriately applied to the use of composite semipermeable membranes according to this embodiment.

[0203] When the composite semipermeable membrane in this embodiment is used as a reverse osmosis membrane, the NaCl removal rate is preferably 99.4% or higher, more preferably 99.60% or higher, and even more preferably 99.70% or higher. Furthermore, the membrane permeation flux is preferably 0.6 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 0.8 m / d or more and 1.8 m / d or less.

[0204] In this embodiment, the chemical resistance of the composite semipermeable membrane indicates that the difference in membrane performance before and after immersion treatment is small. Specifically, it is calculated by the method described in the "immersion treatment" of the example described later. The SP ratio, which is the ratio of NaCl permeability before and after immersion treatment, is preferably 5.0 or less, more preferably 4.5 or less, and still preferably 4.0 or less. In addition, the membrane permeation flux ratio, which is the value obtained by dividing the membrane permeation flux after immersion treatment by the membrane permeation flux before immersion treatment, is preferably 1.7 or less, more preferably 1.6 or less, and still preferably 1.5 or less. Furthermore, in the "immersion treatment in hydrogen peroxide solution" of the example, the smaller the difference in membrane performance before and after immersion treatment, the higher the chemical resistance. The specific indicators are the same as those described in the first embodiment.

[0205] (Third aspect) Next, a third aspect of the present invention will be described in detail.

[0206] A third aspect of the present invention aims to provide a composite semipermeable film having excellent abrasion resistance.

[0207] To achieve the above objectives, a third aspect of the present invention includes the following configurations [C1] to [C11]. [C1] A composite semipermeable membrane comprising a porous support layer, a separation functional layer containing a crosslinked polyamide provided on the porous support layer, and a coating layer containing a polymer having a structure represented by the following general formula (I) provided on the separation functional layer, wherein the degree of yellowing ΔVYI of the surface on the coating layer side before and after contact with a vanillin solution is 5 or more and 23 or less.

[0208]

[0209] [In general formula (I), R １ R is a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted. ２ [C2] The composite semipermeable film according to [C1], wherein the underwater elastic modulus of the surface on the coating layer side is 10 MPa or more and 45 MPa or less. [C3] Surface analysis of the coating layer side by total internal reflection infrared absorption measurement, 1642 to 1662 cm －１ The peak intensity derived from amide I that appears is 1600–1610 cm². －１ A composite semipermeable membrane according to [C1] or [C2] above, wherein the intensity ratio of the maximum intensity of the peaks appearing is 0.86 or more and 1.20 or less. [C4] A composite semipermeable membrane according to any one of [C1] to [C3] above, wherein the degree of yellowing ΔDYI of the surface on the coating layer side before and after contact with Dragendorff reagent is 43 or more and 150 or less. [C5] In surface analysis of the coating layer side by total internal reflection infrared absorbance measurement, 1642 to 1662 cm －１ The maximum intensity of the peak originating from amide I that appears is 2800–2900 cm. －１ A composite semipermeable membrane according to any one of [C1] to [C4] above, wherein the intensity ratio of the maximum intensity of the peaks appearing is 0.20 or more and 0.30 or less. [C6] A composite semipermeable membrane according to any one of [C1] to [C5] above, wherein the polymer consists only of non-halogen atoms. [C7] A composite semipermeable membrane according to any one of [C1] to [C6] above, wherein the polymer has hydrophilic units. [C8] A composite semipermeable membrane according to [C7] above, wherein the hydrophilic units have a structure represented by the following general formula (II).

[0210]

[0211] [In general formula (II), R in each repeating unit ３ and R ４ Each is independently hydrogen or a hydrocarbon group having 2 or fewer carbon atoms, and n is an integer of 1 or more. ] [C9] A composite semipermeable membrane element comprising a composite semipermeable membrane according to any one of [C1] to [C8] above. [C10] A fluid separation device comprising a composite semipermeable membrane according to any one of [C1] to [C8] above. [C11] A method for producing a composite semipermeable membrane comprising the following steps (A) and (B): (A) A step of contacting a porous support layer with a polyfunctional amine aqueous solution, and then contacting the surface of the porous support layer with a water-immiscible organic solvent solution containing a polyfunctional acid halide to form a separation functional layer containing a crosslinked polyamide on the porous support layer by interfacial polymerization. (B) A step of contacting the separation functional layer with a solution containing a polymer having a structure represented by the following general formula (I).

[0212]

[0213] [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.

[0214] 1. Composite Semipermeable Membrane The composite semipermeable membrane of this embodiment comprises 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. The composite semipermeable membrane is preferably a reverse osmosis membrane or a nanofiltration membrane in which the pore size of the separation functional layer is fine.

[0215] 1.1 Coating Layer The coating layer of the composite semipermeable membrane according to 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 one or more monomers (hereinafter also referred to as "monomer units"), and monomer units are units that can be linked together and whose linked molecules form a polymer. When the polymer is a copolymer consisting of two or more monomer units, it may be a random copolymer, an alternating copolymer, or a block copolymer. Among these, random copolymers, which are widely produced industrially, are preferred.

[0216] The composite semipermeable membrane according to this embodiment comprises a coating layer containing a polymer having a structure represented by the following general formula (I).

[0217]

[0218] In general formula (I), R １ R is a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted. ２ is hydrogen, a hydrocarbon group having 2 or fewer carbon atoms, or a functional group having 2 or fewer carbon atoms.

[0219] The polymer contained in the coating layer has a structure represented by general formula (I), which allows hydrogen bonds to be formed between the polymer and the amide groups, amino groups, etc., of the crosslinked polyamide contained in the separation functional layer, and hydrophobic interactions originating from hydrocarbon groups to occur. Through the interaction between the polymer contained in the coating layer and the separation functional layer, the coating layer acts as a sacrificial layer, resulting in a composite semipermeable film with excellent abrasion resistance. From the above viewpoint, it is preferable that the polymer contained in the coating layer has a structure represented by general formula (I) as a repeating unit.

[0220] R in general formula (I) １ If the number of carbon atoms is 4 or more, sufficient hydrophobic interaction is 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. R in general formula (I) １ The number of carbon atoms is more preferably 4 to 10, even more preferably 4 to 8, and particularly preferably 4 to 6. R in general formula (I) ２ The functional group is preferably hydrogen, a hydrocarbon group such as a methyl group or ethyl group, or a methoxymethyl group, with hydrogen being more preferred. ２ If any of the above conditions are met, it is possible to suppress the inhibition of the interaction between the polymer contained in the coating layer and the cross-linked polyamide due to steric hindrance.

[0221] The composite semipermeable membrane according to this embodiment has a degree of yellowing ΔVYI of 5 to 23 on the surface of the coating layer side (hereinafter also referred to as the "coating layer surface") before and after contact with the vanillin solution. The technical explanation, preferred range and reasons, and control factors for the degree of yellowing ΔVYI of the surface of the coating layer side before and after contact with the vanillin solution can be directly applied from the information provided for the first embodiment.

[0222] 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 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. The details of "underwater modulus of elasticity" are as described in the first embodiment.

[0223] The underwater elastic modulus of the coating layer surface can be controlled, for example, by the underwater elastic modulus of the separation functional layer surface of the composite semipermeable membrane, the structure of the polymer described in "C1.1.1 Polymers forming the coating layer" below, the amount of the coating layer, etc.

[0224] When the underwater elastic modulus of the separation functional layer surface of the composite semipermeable membrane before the coating layer is formed is less than 10 MPa, it is preferable that the interaction between the polymer contained in the coating layer and the cross-linked polyamide of the separation functional layer is strong. When the polymer contained in the coating layer and the cross-linked polyamide of the separation functional layer interact strongly, the underwater elastic modulus of the coating layer surface becomes higher than the underwater elastic modulus of the separation functional layer surface, thus improving abrasion resistance.

[0225] Furthermore, if the underwater modulus of elasticity of the separation functional layer surface of the composite semipermeable membrane before the coating layer is formed exceeds 45 MPa, it is preferable that the polymer contained in the coating layer is highly hydrophilic and interacts with the cross-linked polyamide of the separation functional layer. When the polymer contained in the coating layer is highly hydrophilic, the underwater modulus of elasticity of the coating layer surface becomes lower than that of the separation functional layer surface, and the coating layer functions as a sacrificial layer against stress, resulting in excellent abrasion resistance.

[0226] The composite semipermeable film according to this embodiment exhibits a surface analysis of the coating layer side by total internal reflection infrared absorption measurement (hereinafter referred to as "ATR-IR"), with a reading of 1642 to 1662 cm⁻¹. －１The peak intensity derived from amide I that appears is 1600–1610 cm². －１ It is preferable that the intensity ratio of the maximum intensity of the peak appearing is 0.86 or more and 1.20 or less. Generally, 1642 to 1662 cm. －１ The peaks that appear are amide I peaks, which originate from the C=O expansion and contraction of amide groups contained in the separation functional layer and coating layer. Also, 1600–1610 cm －１ The peaks that appear originate from the benzene rings contained in the separation functional layer, coating layer, and porous support layer. Therefore, the intensity ratio of the amide I peak to the peak derived from the benzene rings is the value obtained by standardizing the absorption peaks derived from the separation functional layer and coating layer with the absorption peak derived from the composite semipermeable membrane. When the intensity ratio of the above peaks is 0.86 or higher, the separation functional layer is sufficiently protected by the coating layer, resulting in excellent abrasion resistance. Furthermore, when the intensity ratio of the above peaks is 1.20 or lower, the decrease in membrane permeation flux due to the introduction of an excessive coating layer can be suppressed. From the above viewpoint, the intensity ratio of the above peaks is more preferably 0.90 to 1.15, and even more preferably 0.95 to 1.10. The above peaks are calculated by the method described in "ATR-IR" in the examples described later. The intensity ratio of the above peaks can be controlled, for example, by the polymer concentration during coating layer formation, coating time, etc.

[0227] In this embodiment, the composite semipermeable membrane preferably has a yellowing degree ΔDYI of the surface on the coating layer side before and after contact with the Dragendorff reagent of 43 to 150. Details regarding the Dragendorff reagent, the preferred range of ΔDYI, and the reasons therefor are as described in the first embodiment. The ΔDYI of the coating layer surface can be controlled, for example, by the polymer concentration and coating time during coating layer formation.

[0228] The composite semipermeable film according to this embodiment showed a surface analysis of the coating layer side by ATR-IR, with a yield of 1642 to 1662 cm². －１ The maximum intensity of the peak originating from amide I that appears is 2800–2900 cm. －１ Preferably, the intensity ratio of the maximum intensity of the peak appearing is 0.20 or more and 0.30 or less. Typically, in a composite semipermeable membrane having a separation functional layer containing cross-linked polyamide on a porous support layer, the range is 2800 to 2900 cm.－１ The intensity of the peak appearing at 2800–2900 cm is relatively small compared to the intensity of the peak originating from amide I, with an intensity ratio of less than 0.20. －１ If peaks originating from hydrocarbon groups appear, it means that the polymer contained in the coating layer has hydrocarbon groups. When the polymer contained in the coating layer has hydrocarbon groups, hydrophobic interactions act between the polymer contained in the coating layer and the crosslinked polyamide, making it difficult for the coating layer to peel off from the crosslinked polyamide during abrasion.

[0229] When the intensity ratio of the above peaks is 0.20 or higher, sufficient hydrophobic interaction occurs between the polymer contained in the coating layer and the cross-linked polyamide, and the coating layer acts as a sacrificial layer, resulting in excellent abrasion resistance. On the other hand, when the intensity ratio of the above peaks is 0.30 or lower, the decrease in membrane permeation flux due to the introduction of an excessive coating layer can be suppressed. The above peaks are calculated using the method described in "ATR-IR" in the examples described later.

[0230] The intensity ratio of the above peaks can be controlled, for example, by using a method that gives the polymer contained in the coating layer a structure with an alkyl chain which is a hydrophobic group, or by the polymer concentration during coating layer formation, coating time, etc.

[0231] C1.1.1 Polymer forming the coating layer The polymer contained in the coating layer of this embodiment preferably has a hydrophilic unit in addition to the structure represented by the general formula (I) above. The hydrophilic unit is as described in the first embodiment.

[0232] Polymers having hydrophilic units are soluble in water-soluble solvents. "Soluble in water-soluble solvents" means that they dissolve in a solvent that is "water-soluble" at 25°C, at a concentration of 0.05% by mass or more. Because the polymer is water-soluble or soluble in water-soluble solvents, a coating layer containing the polymer can be formed on the composite semipermeable membrane using a solvent that does not alter the composite semipermeable membrane.

[0233] The hydrophilic polymer unit 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).

[0234]

[0235] 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.

[0236] When the polymer has the structure represented by the above general formula (II), the polymer's affinity for water-soluble solvents is improved, and hydrophobic interactions act between the ether group and the crosslinked polyamide, strengthening the interaction between the polymer and the crosslinked polyamide, thereby adequately protecting the crosslinked polyamide and resulting in a composite semipermeable film with excellent abrasion resistance. Furthermore, from a viewpoint that is basically the same as described in the first embodiment, R ３ and R ４ Hydrogen or a methyl group is preferred. Furthermore, 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.

[0237] 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 polymer and the polyamide, causing the coating layer to act as a sacrificial layer and improving the abrasion resistance of the composite semipermeable film. The reason why the carbon chain is preferable to have 11 or fewer carbon atoms is basically the same as described in the first embodiment. The carbon chain may be linear or cyclic, and may have unsaturated bonds.

[0238] Furthermore, the hydrophilic unit may also have a structure represented by the following general formula (III). Specifically, the hydrophilic unit preferably has a structure represented by general formula (III) in which the main chain has hydrocarbon groups with 4 to 11 carbon atoms as a carbon chain.

[0239]

[0240] In general formula (III), R ５ is a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted.

[0241] The hydrophilic unit has a structure represented by the above general formula (III), which allows for the formation of strong hydrogen bonds between the polymer having highly polarizable carbonyl groups and the polyamide. ５ The preferred forms are the same as those described in the first embodiment.

[0242] Furthermore, it is even more preferable that the hydrophilic unit has a structure represented by the following general formula (IV).

[0243]

[0244] In general formula (IV), X is a structure that includes the above general formula (II), and R ５ R is a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted. ６ and R ７ Each of these is independently a hydrogen atom, a hydrocarbon group having 2 or fewer carbon atoms, or a functional group having 2 or fewer carbon atoms.

[0245] When the hydrophilic unit has the structure represented by the general formula (IV) above, strong hydrogen bonds are formed between the polymer and the polyamide, and strong hydrophobic interactions are at work, and the coating layer acts as a sacrificial layer, resulting in a composite semipermeable film with excellent abrasion resistance. If the polymer 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).

[0246] R ５ The preferred number of carbon atoms and specific examples of the hydrocarbon group are as described above for the general formula (III). ６ and R ７ Because the interaction with the amide group of the crosslinked polyamide in the separation functional layer is good, hydrogen or a C1 hydrocarbon group with low steric hindrance is preferred, and hydrogen is more preferred.

[0247] The polymer contained in the coating layer of the composite semipermeable membrane according to this embodiment preferably has a structure represented by the following general formula (V).

[0248]

[0249] In the 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 less carbon atoms or a functional group having 2 or less carbon atoms, X is a structure including the above general formula (II), and r and q are each independently an integer of 1 or more.

[0250] That is, the above general formula (V) is a copolymer of a hydrophilic unit having a structure represented by the above general formula (IV) and a unit having a structure represented by the above general formula (I). When the polymer contained in the coating layer has a structure represented by the general formula (V), a strong hydrogen bond is formed with the crosslinked polyamide and a hydrophobic interaction acts, so that the coating layer is difficult to peel off from the crosslinked polyamide, and a composite semipermeable membrane having high abrasion resistance can be obtained. Incidentally, the preferred forms of R １ and R ２ are as described above for the above general formula (I). The preferred form of R ５ is as described above for the above general formula (III). The preferred forms of R ６ and R ７ are as described above for the above general formula (IV).

[0251] For the same reason as described for the first aspect, it is preferable that the coating layer of the composite semipermeable membrane according to this aspect is insolubilized so as not to elute when using the composite semipermeable membrane. Further, it is preferable that the copolymer contained in the coating layer of the composite semipermeable membrane according to this aspect consists of only non-halogen atoms. Furthermore, it is preferable that the polymer contained in the coating layer of the composite semipermeable membrane according to this aspect shows solubility in water or a water-soluble solvent.

[0252] For the same reason as described for the first aspect, the total thickness of the separation functional layer and the coating layer in the composite semipermeable membrane according to this aspect is preferably 10 nm or more and 100 nm or less, more preferably 11 nm or more and 70 nm or less, and still more preferably 11 nm or more and 50 nm or less.

[0253] The presence of the above-mentioned polymer in the coating layer of the composite semipermeable membrane can be confirmed by the method described in the first embodiment.

[0254] C1.2 Porous Support Layer The composite semipermeable membrane according to this embodiment comprises a porous support layer. The porous support layer may be formed on a substrate, and the composite of the substrate and the porous support layer is also referred to as the support membrane. The porous support layer and the substrate may each consist of one layer or two or more layers. The porous support layer and the substrate are for providing strength to the separation function layer and do not substantially have solute separation performance themselves. The details of the porous support layer in this embodiment are the same as the details of the porous support layer in the first embodiment described above.

[0255] 1.3 Separation Functional Layer The separation functional layer of the composite semipermeable membrane according to this embodiment is a layer that performs solute separation and contains cross-linked polyamide. It is more preferable that the separation functional layer is mainly composed of cross-linked polyamide. "Mainly composed of cross-linked polyamide" means that the proportion of cross-linked polyamide in the separation functional layer is 50% by mass or more. It is more preferable that the proportion of cross-linked polyamide in the separation functional layer is 80% by mass or more, and even more preferable that it is 90% by mass or more.

[0256] The crosslinked polyamide contained in the separation functional layer is a polycondensate of a polyfunctional amine and a polyfunctional acid halide. In particular, the crosslinked polyamide is preferably a crosslinked aromatic polyamide.

[0257] Furthermore, preferred or specific forms of the separation functional layer in this embodiment are the same as those of the separation functional layer in the first embodiment, except that the separation functional layer in this embodiment contains a crosslinked polyamide.

[0258] Generally, composite semipermeable membranes are subjected to cleaning with acidic and alkaline chemicals in water treatment facilities, so it is desirable that they possess acid and alkali resistance. Furthermore, if pretreatment using an ultrafiltration membrane or the like is performed before the composite semipermeable membrane, oxidizing agents such as chlorine used to clean the pretreatment membrane may leak and come into contact with the composite semipermeable membrane, causing oxidative degradation. Therefore, it is preferable that composite semipermeable membranes also possess chlorine resistance.

[0259] In the composite semipermeable membrane according to this embodiment, the crosslinked polyamide is stabilized by the formation of hydrogen bonds and hydrophobic interactions between the polymer contained in the coating layer and the crosslinked aromatic polyamide contained in the separation functional layer. Therefore, the composite semipermeable membrane exhibits excellent abrasion resistance as well as high acid resistance, alkali resistance, and chlorine resistance. Due to these properties, the composite semipermeable membrane according to this embodiment can maintain good performance before and after chemical cleaning and oxidizing agent cleaning.

[0260] C1.4 Composite Semipermeable Membrane Element The composite semipermeable membrane element according to this embodiment comprises a composite semipermeable membrane according to this embodiment. Preferred or specific embodiments of the composite semipermeable membrane element according to this embodiment are the same as those relating to the composite semipermeable membrane element according to the first embodiment.

[0261] C2. Method for Manufacturing a Composite Semipermeable Film The method for manufacturing a composite semipermeable film according to one embodiment of this embodiment is not particularly limited as long as a composite semipermeable film satisfying the desired features described above can be obtained, but for example, it can be manufactured by the following method.

[0262] C2.1 Film Formation of Support Film Known methods can be suitably used for forming the support film, and specifically, the method described in detail in the first embodiment can be applied in the same manner.

[0263] C2.2 Formation process of the separation functional layer The method for forming the separation functional layer can be similarly applied to the method specifically described in the first embodiment.

[0264] C2.3 Process for Forming the Coating Layer The process for forming the coating layer can be similarly applied to the method specifically described in the first embodiment. However, in this embodiment, as the polymer forming the coating layer, a polymer having a structure represented by the following general formula (I) can be used, as described in the section "C1.1 Coating Layer" above.

[0265] The concentration of the polymer forming the coating layer in the solution is preferably 0.0002% by mass or more and 10% by mass or less, more preferably 0.0002% by mass or more and 2% by mass or less, and even more preferably 0.005% by mass or more and 1% by mass or less. When the concentration of the polymer forming the coating layer is 0.0002% by mass or more, a sufficient amount of the polymer forming the coating layer comes into contact with the surface of the separation functional layer, so the coating layer acts as a sacrificial layer and excellent abrasion resistance can be obtained. On the other hand, when the concentration of the polymer forming the coating layer is 10% by mass or less, a composite semipermeable membrane with sufficient water permeability can be obtained.

[0266] C3. Use of Composite Semipermeable Membranes The matters described in the first embodiment can be appropriately applied to the use of composite semipermeable membranes according to this embodiment.

[0267] In this embodiment, when the composite semipermeable membrane is used as a reverse osmosis membrane, the preferred range for the NaCl removal rate and the preferred range for the membrane permeation flux are the same as those described in the first embodiment. In this specification, the abrasion resistance of the composite semipermeable membrane refers to a small difference in membrane performance before and after the abrasion test in the "abrasion test" described in the examples. Specifically, the difference in NaCl removal rate, which is the value obtained by subtracting the NaCl removal rate after the abrasion test from the initial performance NaCl removal rate, is preferably 0.4% or less, more preferably 0.2% or less, and even more preferably 0.1% 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.

[0268] In this embodiment, the chemical resistance of the composite semipermeable membrane refers to a small difference in membrane performance before and after the "immersion treatment" described in the examples. Specifically, the SP ratio, which is the ratio of NaCl permeability before and after the immersion treatment, is preferably 5.0 or less, more preferably 4.5 or less, and still more preferably 4.0 or less. Furthermore, the membrane permeation flux ratio, which is the value obtained by dividing the membrane permeation flux after the immersion treatment by the membrane permeation flux before the immersion treatment, is preferably 1.7 or less, more preferably 1.6 or less, and still more preferably 1.5 or less. In addition, a smaller difference in membrane performance before and after the immersion treatment described in the "immersion treatment in hydrogen peroxide solution" of the examples indicates higher chemical resistance. The specific indicators are the same as those described in the first embodiment.

[0269] C4. Treatment agents for composite semipermeable membranes As described above, polymers having structures represented by general formulas (I) and (II) form hydrogen bonds with crosslinked polyamides and also exhibit hydrophobic interactions, so they can be used as coating agents to improve the abrasion resistance of composite semipermeable membranes containing polyamides in the separation functional layer. The coating agent may also contain other components such as crosslinking agents, to the extent that they do not interfere with the effects of this embodiment.

[0270] The present invention will be described below with reference to specific examples, but the present invention is not limited in any way by these examples.

[0271] First, an example relating to the first embodiment will be described.

[0272] <NaCl Removal Rate> A composite semipermeable membrane was used with evaluation water adjusted to a temperature of 25°C, pH 7.0, and NaCl concentration of 34,000 ppm as the supply water, with a membrane permeation flux of 1.0 m. ３ / m ２The operating pressure was adjusted to 1 / d and the water was supplied, and membrane filtration treatment was performed for 1 hour. After that, the electrical conductivity of the supplied water and permeate was measured with a multi-water quality meter MM60R (manufactured by Toa DKK Co., Ltd.) to obtain the practical salinity, i.e., NaCl concentration of each. From the obtained NaCl concentration, the NaCl removal rate was calculated using the following formula (1). Here, NaCl concentration (ppm) means the concentration on a mass basis. NaCl removal rate (%) = 100 × {1 - (NaCl concentration in permeate / NaCl concentration in supplied water)} ... formula (1) <Membrane permeate flux> Evaluation water adjusted to a temperature of 25°C, pH 7.0, and sodium chloride concentration of 34,000 ppm was supplied to a composite semipermeable membrane at a pressure of 5.50 MPa and membrane filtration treatment was performed for 1 hour. After that, the amount of permeate (m) over 20 minutes was calculated. ３ ) was measured, and the unit membrane area (m²) was measured. ２ The membrane permeation flux (m / d) was calculated by converting the values ​​to values ​​per unit time (d).

[0273] <Membrane Degradation Test> After sequentially performing the following treatments (i) to (vi) on the composite semipermeable membrane, the NaCl removal rate and membrane permeation flux were calculated using the methods described above for "NaCl removal rate" and "membrane permeation flux". The membrane permeation flux ratio was defined as the value obtained by dividing the membrane permeation flux after the membrane degradation test by the membrane permeation flux before the membrane degradation test. (i) Immersed in a sodium hydroxide aqueous solution prepared at 25°C and pH 13.0 for 48 hours, then washed with distilled water. (ii) Immersed in sulfuric acid prepared at 25°C and pH 2.0 for 3 hours, then washed with distilled water. (iii) Immersed in a 20 mg / L sodium hypochlorite aqueous solution prepared at 25°C and pH 7.0 for 24 hours. (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 an aqueous sodium hydroxide solution prepared at 25°C and pH 13.0 for 48 hours, and washed with distilled water. (vi) Immersed in sulfuric acid prepared at 25°C and pH 2.0 for 3 hours, and washed with distilled water.

[0274] <Calculation of Polarization Degree> The polarization degrees of the hydrophilic and hydrophobic units were 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.

[0275] [Target Monomer Structure Modeling Process S1] Using Winmonster (manufactured by CrossAbility Co., Ltd.), the three-dimensional molecular structure of each monomer unit, hydrophilic and hydrophobic units, was modeled. 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.

[0276] [Trimer Modeling Process S2] Trimer models were created from the hydrophilic and hydrophobic units modeled in the target monomer structure modeling process S1, respectively, using Winmonster.

[0277] [Stable Conformation Search Process S3] Using conformational search (Balloon), stable conformation searches were performed on the trimer models of the hydrophilic unit and hydrophobic unit modeled in the trimer modeling process S2. This process was omitted when the stable conformation of the target structure could be determined from chemical experience.

[0278] [Structural Optimization Calculation Process S4] If necessary, for the trimer models of hydrophilic and hydrophobic units obtained in the stable conformation search process S3, structural optimization calculations were performed using density functional theory with the quantum chemical calculation program Gaussian16, using the 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".

[0279] [Charge Parameter Calculation Process S5] In order to calculate the partial charge on each atom in the trimer model of hydrophilic and hydrophobic units in the vacuum-optimized structure obtained in the structural optimization calculation process S4, the log file output after the structural optimization calculation by Gaussian 16 described above was read, and a single-point calculation using density functional theory was performed. At that time, the calculation method / basis function was HF / 6-31g*, and "geom=allcheck", "guess=read", "pop=mk", and "iop(6 / 41=10, 6 / 42=17, 6 / 50=1)" were added to the root section to output an esp file. The output esp file was used as input information, and the antechamber module (antechamber command) included with Amber Tools 16.0 was used to convert the ESP charge to RESP charge. The degree of polarization of each atom was calculated from the obtained RESP charge using the following equation (2). For the hydrophilic and hydrophobic units, the maximum value of the polarization of the atoms constituting the hydrogen bonding acceptors, respectively, was taken as the degree of polarization of the hydrophilic and hydrophobic units. Degree of polarization = -RESP charge [e] ... Equation (2)

[0280] <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. －１The area was divided into sections, approximated by trapezoidal shapes, and the areas of each section were added together to calculate the peak area A. Specifically, 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.

[0281] <Coloring with Vanillin> After washing the composite semipermeable membrane with 85°C hot water for 2 minutes, the moisture on the surface of the coating layer or separation functional layer was removed by air drying. The dried composite semipermeable membrane was immersed in an ethanol solution containing 2% by mass of 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, after washing the composite semipermeable membrane with 85°C hot water for 2 minutes, the moisture on the surface was removed by air drying. The dried 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 on the coating layer or separation function layer side 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, and the yellowness VYI of the vanillin-treated film sample and the yellowness VYI of the untreated film sample were determined from the tristimulus values ​​of the XYZ color system. ０ The degree of yellowing ΔVYI was calculated using the following formula (3). Three measurements were performed using different samples. ΔVYI = VYI - VYI ０ ...Equation (3) Note that the degree of yellowing ΔVYI was calculated by taking the average of the values ​​obtained from three measurements and rounding to the first decimal place.

[0282] <Elastic modulus in water>The amount of deformation on the surface of the coating layer side was measured using an atomic force microscope (AFM) under the following conditions. Then, the elastic modulus in water was measured based on the amount of deformation. Ten different fold protrusions in one sample were measured. Also, using different measurement samples, the value obtained by rounding the first decimal place of the average value of the values measured three times was used. Observation device: Scanning probe microscope FastScan manufactured by BRUKER Probe: Cantilever (made of silicon, spring constant: 0.7 N / m, shape: conical) Scanning mode: Nanomechanical Mapping in Fluid Scanning range: 2 μm square The deflection sensitivity of the cantilever was measured with sapphire, and the spring constant of the cantilever was measured by thermal vibration. The composite semipermeable membrane was immersed in a 20 wt% aqueous isopropanol solution at 25°C for 20 minutes, and then immersed in distilled water at 25°C for 1 hour. Then, the composite semipermeable membrane cut into 1 cm square was fixed to the sample stage, and 0.3 mL of distilled water was dropped. Then, the operation of pressing the cantilever against the fold protrusion on the separation functional layer side and then separating it was performed, and a curve plotting the force acting on the cantilever with respect to the distance between the cantilever and the composite semipermeable membrane was obtained. In this specification, this curve is referred to as a force curve.

[0283] At this time, the displacement of the cantilever is Z (the moment when the cantilever and the composite semipermeable membrane come into contact is Z = Z ０ , and at the place farthest from the sample, Z = 0), and the deflection of the cantilever is Δ. When the composite semipermeable membrane, which is the sample, is deformed due to contact with the cantilever, the following formula (4) holds for the amount of deformation δ. δ [nm] = (Z - Z ０ ) - Δ... Formula (4) Here, for the displacement Z of the cantilever when the composite semipermeable membrane and the cantilever are in contact, Z, δ, and Δ take the maximum values Z ｔ , δ ｔ , δ ｔ , Δ ｔ . Here, by considering Δ with respect to the displacement Z of the cantilever, the horizontal axis was converted to 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 formula (5).

[0284] Distance between cantilever and composite semipermeable membrane [nm] = Δ - Z + Z ｔ - Δｔ ...Equation (5) The point on the force curve where the load becomes 0, i.e., Δ = 0, Z = Z ０ The distance between the cantilever and the composite semipermeable membrane is given by equation (5) Z ｔ -Z ０ -Δ ｔ However, the deformation amount δ at the point of maximum interaction is ｔ From equation (4), Z ｔ -Z ０ -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.

[0285] 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.

[0286] 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 in water was calculated from the obtained 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).

[0287] 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.

[0288] <Color development using Dragendorff's reagent> Solution A was prepared by dissolving bismuth subnitrate in 1 mol / L hydrochloric acid solution 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 that, the membrane was air-dried overnight to obtain a Dragendorff's reagent treated membrane sample. Furthermore, the composite semipermeable membrane was immersed in 0.05 mol / L hydrochloric acid for 15 minutes, then in 0.2 mol / L hydrochloric acid for 45 minutes, and then in 0.05 mol / L hydrochloric acid for 10 minutes. After that, it was air-dried overnight to obtain an untreated membrane sample. The yellowness of the membrane 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, and the yellowness DYI of the Dragendorff reagent-treated membrane sample and the yellowness DYI of the untreated membrane sample were determined from the tristimulus values ​​of the XYZ color system. ０ The degree of yellowing ΔDYI was calculated using the following formula (7): ΔDYI = DYI - DYI ０ ...Equation (7) Note that 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.

[0289] <Abrasion Test> As shown in Figures 5 and 6, the composite semipermeable membrane 1 was cut into a 12 cm x 13 cm square and attached to a 5.0 kg rectangular parallelepiped (base 12 cm x 13 cm square) weight 18 with the coating layer or separation functional layer facing outwards. The membrane surface was then scraped by blowing a nitrogen stream from an air nozzle. A polypropylene net 19 (thickness 0.7 mm, pitch width: 5.6 mm x 4.5 mm) 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 was pulled together with the composite semipermeable membrane 1 using a tensile testing machine 21 under the following conditions. Afterwards, the weight 18 was returned to its initial position before movement, and the weight 18 was pulled again together with the composite semipermeable membrane 1 using the same procedure. Tensile speed: 100 mm / min Tensile distance: 240 mm in total (120 mm x 2 times) Measurement room temperature: 25°C In addition, the NaCl removal rate of the composite semipermeable membrane after the abrasion test was measured using the method described in "NaCl removal rate" above, using the composite semipermeable membrane that underwent the abrasion test. The NaCl removal rate was measured for all eight sheets that underwent the abrasion test, and the average value was taken as the NaCl removal rate after the abrasion test.

[0290] <Immersion Treatment> The composite semipermeable membrane was immersed for 20 hours in a sodium hypochlorite aqueous solution prepared at 25°C, 100 ppm, and pH 7.0, and then washed with distilled water. Next, it was immersed for 20 hours in a sodium hydroxide aqueous solution prepared at 25°C and pH 13.0, then immersed for 20 hours in sulfuric acid prepared at 25°C and pH 1.0, and then washed with distilled water.

[0291] <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 treatment in hydrogen peroxide solution, as in the "immersion treatment" described above. Chemical resistance was evaluated by the membrane permeation flux ratio and SP ratio before and after immersion treatment and immersion treatment in hydrogen peroxide solution, and was calculated using the following formulas (8) and (9). Note that in formulas (8) and (9), when determining the SP ratio and membrane permeation flux ratio before and after immersion treatment in hydrogen peroxide solution, "immersion treatment" should be read as "immersion treatment in hydrogen peroxide solution". 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)

[0292] <Synthesis of Copolymers> [Synthesis Example 1] 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 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 1.

[0293] [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.

[0294] [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.

[0295] [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.

[0296] [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.

[0297] [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.

[0298] [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.

[0299] [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 vessel under a nitrogen atmosphere and reacted for 2 hours to obtain copolymer 8.

[0300] [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.

[0301] [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.

[0302] [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.

[0303] <Preparation of Composite Semipermeable Membrane> A porous support layer stock solution was prepared by dissolving 15% by mass of PSf (Udel P-3500, Mw 80,000, manufactured by Solvay Specialty Polymers Japan Ltd.) and 85% by mass of DMF at 100°C. This porous support layer stock solution was then mixed with a polyester long-fiber nonwoven fabric (thickness 90 μm, density 0.42 g / cm³). ３ The film was applied to the surface of the substrate at 25°C, solidified for 3 seconds by immersion in a solidification solution consisting of distilled water at 25°C for 30 seconds, and 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 film was immersed in a 3 mass% aqueous solution of m-PDA for 2 minutes, the support film was slowly pulled up vertically, and excess aqueous solution was removed from the surface of the support film by blowing nitrogen from an air nozzle. In an environment controlled at 25°C, 20 ml of decane solution containing 0.15 mass% TMC at 25°C was applied so that the surface of the support film was completely wetted and left to stand for 1 minute. Next, the film was held vertically for 30 seconds to drain and remove excess solution, and then washed with hot water at 90°C for 2 minutes to obtain a composite semipermeable membrane 1. The separation functional layer of the composite semipermeable membrane 1 had a pleated shape.

[0304] [Reference Example 1] Table 3 shows the performance evaluation results of composite semipermeable membrane 1.

[0305] [Example 1] A composite semipermeable membrane 1 was brought into contact with an aqueous solution containing 0.01% by mass of copolymer 1. The membrane was kept in contact with the aqueous solution at 20°C for 5 minutes. After that, the composite semipermeable membrane was held vertically to drain off the excess aqueous solution, and washed with 20°C water for 5 minutes to prepare a composite semipermeable membrane with copolymer 1 as a coating layer.

[0306] [Example 2] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymer 1 was replaced with copolymer 2.

[0307] [Example 3] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymer 1 was replaced with copolymer 3.

[0308] [Example 4] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymer 1 was replaced with copolymer 4.

[0309] [Example 5] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymer 1 was replaced with copolymer 5.

[0310] [Example 6] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymer 1 was replaced with copolymer 6.

[0311] [Example 7] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymer 1 was replaced with copolymer 7.

[0312] [Example 8] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymer 1 was replaced with copolymer 8.

[0313] [Example 9] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymer 1 was replaced with copolymer 9.

[0314] [Example 10] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymer 1 was replaced with copolymer 10.

[0315] [Comparative Example 1] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymer 1 was polyethylene glycol (weight-average molecular weight: 8,000,000).

[0316] [Comparative Example 2] A formic acid solution containing 0.01% by mass of 6-nylon (weight-average molecular weight: 100,000) was brought into contact with composite semipermeable membrane 1. After contact with the solution, the crosslinked polyamide of the composite semipermeable membrane decomposed and did not exhibit salt removal properties.

[0317] [Comparative Example 3] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymer 1 was replaced with copolymer 11.

[0318] [Comparative Example 4] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymer 1 was changed to Pluronic (registered trademark, F-68), which is a polyoxyethylene-polyoxypropylene block copolymer.

[0319] [Comparative Example 5] 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 of the separation functional layer of composite semipermeable membrane 1 in an environment controlled at 20°C. With the aqueous solution remaining on the surface of the separation functional layer, a coating layer was formed on the separation functional layer by blowing 70°C hot air onto the composite semipermeable membrane for 3 minutes. After that, the composite semipermeable membrane was held vertically to drain off the excess aqueous solution and washed with 20°C water for 2 minutes. Finally, as a hydrophilization treatment, the composite semipermeable membrane was immersed in a 14% by mass aqueous solution of isopropanol at 20°C for 5 minutes to produce a composite semipermeable membrane.

[0320] [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 contained 0.01% by mass of polyacrylic acid (weight-average molecular weight: 100,000) and 0.05% by mass of DMT-MM.

[0321] [Example 11] A composite semipermeable membrane was prepared in the same manner as in Example 7, except that the holding time was changed to 1 hour.

[0322] [Example 12] A composite semipermeable membrane was prepared in the same manner as in Example 2, except that the holding time was changed to 5 hours.

[0323] [Example 13] A composite semipermeable membrane was prepared in the same manner as in Example 11, except that the holding time was changed to 5 hours.

[0324] [Example 14] A composite semipermeable membrane was prepared in the same manner as in Example 8, except that the holding time was changed to 1 hour.

[0325] [Comparative Example 7] A composite semipermeable membrane was prepared in the same manner as in Comparative Example 1, except that the holding time was changed to 5 hours.

[0326] [Comparative Example 8] A composite semipermeable membrane was prepared in the same manner as in Comparative Example 7, except that polyethylene glycol was replaced with polyethyl oxazoline (weight-average molecular weight: 100,000) and the holding time was changed to 5 hours.

[0327] [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) with 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.

[0328] [Example 15] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymer 1 was changed to copolymer 2, the concentration was changed to 10% by mass, and the holding time was changed to 30 seconds. Subsequently, a membrane degradation test, color change due to vanillin yellowing, elastic modulus in water, and color change with Dragendorff's reagent were performed.

[0329] [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 to 1 hour.

[0330] [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.

[0331] [Example 18] A composite semipermeable membrane was prepared in the same manner as in Example 15, except that copolymer 2 was changed to copolymer 7, the concentration was changed to 1% by mass, and the retention time was changed to 1 hour.

[0332] [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 to 1 hour. Subsequently, membrane degradation tests, color development by vanillin yellowing, elastic modulus in water, and color development by Dragendorff's reagent were performed.

[0333] [Comparative Example 11] A composite semipermeable membrane was prepared in the same manner as in Comparative Example 5, except that 2% by mass of ethylene-vinyl alcohol copolymer was replaced with 1% by mass of fully saponified polyvinyl alcohol (weight-average molecular weight: 100,000). Subsequently, membrane degradation tests, color development by vanillin yellowing, elastic modulus in water, and color development by Dragendorff's reagent were performed.

[0334] [Reference Example 2] A composite semipermeable membrane 1 was subjected to immersion treatment in hydrogen peroxide solution.

[0335] [Example 19] The composite semipermeable membrane obtained in Example 1 was subjected to immersion treatment in hydrogen peroxide solution.

[0336] [Comparative Example 12] The composite semipermeable membrane obtained in Comparative Example 1 was subjected to immersion treatment in hydrogen peroxide solution.

[0337] 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 to 10 and Comparative Examples 1 to 6. Table 4 shows the performance evaluation results and ATR-IR measurement results for Examples 11 to 14 and Comparative Examples 7 to 9. Table 5 shows the performance evaluation results, ΔVYI, water modulus of elasticity, and ΔDYI for Examples 15 to 18 and Comparative Examples 10 to 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.

[0338]

[0339]

[0340]

[0341]

[0342]

[0343]

[0344] 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.

[0345] Next, an example relating to the second embodiment will be described.

[0346] <NaCl Removal Rate> The NaCl removal rate was calculated in the same manner as in the example relating to the first embodiment.

[0347] <Membrane Permeation Flux> The membrane permeation flux was calculated in the same manner as in the example relating to the first embodiment.

[0348] <Immersion Treatment> For the composite semipermeable membranes of Examples B1 to B7 and Comparative Examples B1 to B4 described later, immersion treatment (immersion in chlorine, alkali, and acid) was performed in the same manner as in the examples relating to the first embodiment, and the membrane performance before and after immersion treatment was evaluated. For the obtained composite semipermeable membranes after immersion treatment, the NaCl removal rate and membrane permeation flux were calculated using the methods described above for "NaCl removal rate" and "membrane permeation flux". Chemical resistance was evaluated by the membrane permeation flux ratio and SP ratio before and after immersion treatment, and were calculated using the following formulas (8) and (9). Membrane permeation flux ratio = membrane permeation flux after immersion treatment / membrane permeation flux before immersion treatment ... Formula (8) SP ratio = (100 - NaCl removal rate after immersion treatment) / (100 - NaCl removal rate before immersion treatment) ... Formula (9) A membrane permeation flux ratio of 1.7 or less before and after immersion treatment is considered good. Furthermore, a SP ratio of 5.0 or less before and after immersion treatment is considered good.

[0349] <Immersion Treatment in Hydrogen Peroxide Solution> The composite semipermeable membranes of Example B8 and Comparative Examples B5-B6, described later, were subjected to the same hydrogen peroxide solution immersion treatment as in the example relating to the first embodiment, and the membrane performance before and after the hydrogen peroxide solution immersion treatment was evaluated. A membrane permeation flux ratio of 1.7 or less before and after the hydrogen peroxide solution immersion treatment is considered good. In addition, an SP ratio of 7.0 or less before and after the hydrogen peroxide solution immersion treatment is considered good.

[0350] <ATR-IR> An ATR-IR spectrum is obtained in the same manner as described in the first embodiment, and the wavenumber and w of the peak top of amide I are determined. ８０％ The result was calculated.

[0351] <Synthesis of Polymers> [Synthesis Example B1] 30 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 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 polyamide B1.

[0352] [Synthesis Example B2] 50 g of ε-caprolactam, 100 g of a salt consisting of α,ω-diaminopolyoxyethylene 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 polyamide B2.

[0353] [Synthesis Example B3] 5 g of ε-caprolactam, 100 g of a salt consisting of α,ω-diaminopolyoxyethylene and adipic acid, and 105 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 polyamide B3.

[0354] [Synthesis Example B4] 10 g of ε-caprolactam, 100 g of a salt consisting of α,ω-diaminopolyoxyethylene and terephthalic 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 polyamide B4.

[0355] [Synthesis Example B5] 10 g of ε-caprolactam, 100 g of a salt consisting of N-(2-aminoethyl)piperazine and adipic acid, and 110 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 polyamide B5.

[0356] <Preparation of Composite Semipermeable Membrane> A porous support layer stock solution was prepared by dissolving 15% by mass of PSf (Solvay Specialty Polymers; Udel P-3500, Mw: 80,000) 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). ３The film was coated onto the surface at 25°C, solidified for 3 seconds by immersion in a solidification bath of 25°C distilled water for 30 seconds, and then washed with 90°C hot water 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 film was immersed in a 2.6 mass% m-PDA aqueous solution for 2 minutes, the support film was slowly pulled up vertically, and excess aqueous solution was removed from the surface of the support film by blowing nitrogen from an air nozzle. In an environment controlled at 25°C, 20 ml of decane solution containing 0.14 mass% TMC at 25°C was applied so that the surface of the support film was completely wetted and left to stand for 1 minute. Next, the film was held vertically for 30 seconds to drain and remove excess solution, and then washed with 90°C hot water for 2 minutes to obtain a composite semipermeable film B1.

[0357] [Reference Example B1] Performance evaluation was performed using composite semipermeable membrane B1.

[0358] [Example B1] A composite semipermeable membrane B1 was brought into contact with an aqueous solution containing 1% by mass of copolymerized polyamide B1. The membrane was kept in contact with the aqueous solution at 20°C for 1 hour. After that, the composite semipermeable membrane was held vertically to drain off the excess aqueous solution, and washed with 20°C water for 5 minutes to prepare a composite semipermeable membrane with copolymerized polyamide B1 as a coating layer.

[0359] [Example B2] A composite semipermeable membrane was prepared in the same manner as in Example B1, except that the concentration of copolymerized polyamide B1 was changed to 0.01% by mass.

[0360] [Example B3] A composite semipermeable membrane was prepared in the same manner as in Example B1, except that copolymerized polyamide B1 was replaced with copolymerized polyamide 2.

[0361] [Example B4] A composite semipermeable membrane was prepared in the same manner as in Example B1, except that copolymerized polyamide B1 was replaced with copolymerized polyamide B3.

[0362] [Example B5] A composite semipermeable membrane was prepared in the same manner as in Example 1B, except that copolymerized polyamide B1 was replaced with copolymerized polyamide B4.

[0363] [Example B6] A composite semipermeable membrane was prepared in the same manner as in Example B1, except that copolymerized polyamide B1 was replaced with copolymerized polyamide B5.

[0364] [Example B7] A composite semipermeable membrane was prepared in the same manner as in Example B6, except that the concentration of copolymerized polyamide B5 was changed to 0.01% by mass.

[0365] [Comparative Example B1] A composite semipermeable membrane was prepared in the same manner as in Example B1, except that copolymer polyamide B1 was replaced with polyethylene glycol (weight-average molecular weight: 100,000).

[0366] [Comparative Example B2] A composite semipermeable membrane was prepared in the same manner as in Example B1, except that copolymerized polyamide B1 was replaced with polyethyl oxazoline (weight-average molecular weight: 100,000).

[0367] [Comparative Example B3] An aqueous solution containing 1.0% by mass of fully saponified polyvinyl alcohol (weight-average molecular weight: 100,000), 0.25% by mass of glutaraldehyde, and 0.1% by mass of sulfuric acid was brought into contact with the entire surface of the separation functional layer of composite semipermeable membrane B1 in an environment controlled at 20°C. The membrane was kept at 20°C for 1 hour with the aqueous solution remaining on the surface of the separation functional layer. After that, the composite semipermeable membrane was held vertically to drain off the excess aqueous solution and washed with 20°C water for 2 minutes. Finally, the composite semipermeable membrane was immersed in a 14% by mass aqueous solution of isopropanol at 20°C for 5 minutes to hydrophilize it and produce a composite semipermeable membrane.

[0368] [Comparative Example B4] The composite semipermeable membrane B1 was contacted with an aqueous solution containing 2% by mass of polyethyl oxazoline (weight-average molecular weight: 100,000) at 20°C for 1 hour. After contact with the aqueous solution, it was held at 70°C for 10 minutes. Then, the composite semipermeable membrane was held vertically to drain off excess aqueous solution and washed with 20°C water for 2 minutes. After that, it was immersed in a 10% by mass aqueous solution of isopropanol at 20°C for 20 minutes to hydrophilize it and produce a composite semipermeable membrane.

[0369] [Example B8] The composite semipermeable membrane obtained in Example B1 was subjected to immersion treatment in hydrogen peroxide solution.

[0370] [Comparative Example B5] The composite semipermeable membrane obtained in Comparative Example B1 was subjected to immersion treatment in hydrogen peroxide solution. [Comparative Example B6] The composite semipermeable membrane obtained in Comparative Example B1 was subjected to immersion treatment in hydrogen peroxide solution.

[0371] Table B1 shows the structure of the polymer obtained in the synthesis example, Table B2 shows the parameters obtained from the ATR-IR of the obtained composite semipermeable membrane, and Table B3 shows the performance evaluation results. Monomer unit A is a monomer unit having a hydrophilic structure represented by the above general formula (II), and monomer unit B is a monomer unit having a structure represented by the above general formula (I). The mass ratio A / B is the mass ratio of monomer unit A constituting the polymer to monomer unit B.

[0372]

[0373]

[0374]

[0375]

[0376] As shown in Tables B3 and B4, the composite semipermeable film according to this embodiment exhibits an effect of improving chemical resistance.

[0377] Next, an example relating to the third embodiment will be described.

[0378] <NaCl Removal Rate> The NaCl removal rate was calculated in the same manner as in the example relating to the first embodiment.

[0379] <Membrane Permeation Flux> The membrane permeation flux was calculated in the same manner as in the example relating to the first embodiment.

[0380] <Immersion Treatment> The composite semipermeable membranes of Reference Example C3, Example C10, and Comparative Example C7, described later, were subjected to the same immersion treatment (immersion in chlorine, alkali, and acid) as in the examples relating to the second embodiment, and the membrane performance before and after the immersion treatment was evaluated.

[0381] <Immersion Treatment in Hydrogen Peroxide Solution> The composite semipermeable membranes of Reference Example C3, Example C10, and Comparative Example C7, described later, were subjected to the same hydrogen peroxide solution immersion treatment as in the examples relating to the second embodiment, and the membrane performance before and after the hydrogen peroxide solution immersion treatment was evaluated.

[0382] <Coloring with Vanillin> In the same manner as in the example relating to the first embodiment, coloring was performed with vanillin, and the degree of yellowing ΔVYI was calculated.

[0383] <Modulus of elasticity in water> The modulus of elasticity in water was measured in the same manner as in the embodiment relating to the first aspect.

[0384] <Color development using Dragendorff's reagent> Color development using Dragendorff's reagent was performed in the same manner as in the example relating to the first embodiment, and the degree of yellowing ΔDYI was calculated.

[0385] <Abrasion Test> An abrasion test was performed in the same manner as in the embodiment of the first aspect. Using the composite semipermeable membranes that underwent the abrasion test, the NaCl removal rate of the composite semipermeable membrane 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. In addition, the difference in NaCl removal rate and the membrane permeation flux ratio were calculated from the following formulas (13) and (14). A difference in NaCl removal rate, which is the value obtained by subtracting the NaCl removal rate after the abrasion test from the NaCl removal rate of the initial performance, is considered good if it is 0.4% or less. In addition, a 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 considered good if it is 1.5 or less. NaCl removal rate difference (%) = NaCl removal rate before the abrasion test (initial performance) - NaCl removal rate after the abrasion test ... Equation (13) Membrane permeation flux ratio (-) = Membrane permeation flux after the abrasion test / Membrane permeation flux before the abrasion test (initial performance) ... Equation (14)

[0386] <ATR-IR> An ATR-IR spectrum was obtained in the same manner as in the embodiment of the first aspect. However, the resolution was 4 cm. －１ I set it to, for example, 1600-1610 cm. －１ Or 2800-2900 cm －１If multiple peaks were present, the intensity of the peak with the highest intensity among the detected peaks was used.

[0387] <Synthesis of Polymers> [Synthesis Example C1] 30 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 130 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 polyamide C1.

[0388] [Synthesis Example C2] 10 g of p-aminobenzoic acid, 100 g of a salt consisting of α,ω-diaminopolyoxyethylene with a number average molecular weight of 600 and adipic acid, and 200 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 polyamide C2.

[0389] [Synthesis Example C3] 10 g of ε-caprolactam, 100 g of a salt consisting of α,ω-diaminopolyoxyethylene with a number average molecular weight of 600 and terephthalic acid, and 200 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 polyamide C3.

[0390] [Synthesis Example C4] 20 g of ε-caprolactam, 100 g of a salt consisting of α,ω-diaminopolyoxyethylene with a number average molecular weight of 4,000 and oxalic 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 polyamide C4.

[0391] [Synthesis Example C5] 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 polyamide C5.

[0392] [Synthesis Example C6] 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 vessel under a nitrogen atmosphere and reacted for 2 hours to obtain copolymer polyamide C6.

[0393] [Synthesis Example C7] 100 g of a salt consisting of α,ω-diaminopolyoxyethylene with a number-average molecular weight of 600, having amino groups at both ends, and adipic acid, and 100 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 polyamide C7.

[0394] <Preparation of Composite Semipermeable Membrane C1> A porous support layer stock solution was prepared by dissolving 15% by mass of PSf (Udel P-3500, Mw: 80,000, manufactured by Solvay Specialty Polymers Japan Ltd.) and 85% by mass of DMF at 100°C. This porous support layer stock solution was then mixed with a polyester long-fiber nonwoven fabric (thickness 90 μm, density 0.42 g / cm³). ３ The film was coated onto the surface of the substrate at 25°C, solidified for 3 seconds by immersion in a solidification solution consisting of distilled water at 25°C for 30 seconds, and 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.

[0395] Next, the obtained support membrane was immersed in a 1.5% by mass aqueous solution of m-PDA for 1 minute, and the support membrane was slowly pulled up vertically. Excess aqueous solution was removed from the surface of the support membrane by blowing nitrogen from an air nozzle. In an environment controlled at 25°C, 20 mL of decane solution at 25°C containing 0.1% 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 30 seconds. Next, the membrane was held vertically for 30 seconds to drain and remove the excess solution, and then washed with 90°C hot water for 2 minutes to obtain a composite semipermeable membrane C1. The separation functional layer of the composite semipermeable membrane C1 had a pleated shape.

[0396] <Preparation of composite semipermeable membrane C2> Composite semipermeable membrane C2 was obtained in the same manner as composite semipermeable membrane C1, except that the m-PDA concentration was changed to 1.2 mass% and the TMC concentration to 0.08 mass%. The separation functional layer of composite semipermeable membrane C2 had a pleated shape.

[0397] [Reference Example C1] The evaluation results of composite semipermeable membrane C1 are shown in Table C1.

[0398] [Reference Example C2] A composite semipermeable membrane C1 was brought into contact with an aqueous solution containing 0.001% by mass of copolymerized polyamide C1. The membrane was kept in contact with the aqueous solution at 20°C for 30 seconds. After that, the composite semipermeable membrane was held vertically to drain off the excess aqueous solution, and washed with 20°C water for 10 minutes to prepare a composite semipermeable membrane with copolymerized polyamide C1 as a coating layer.

[0399] [Example C1] A composite semipermeable membrane C1 was brought into contact with an aqueous solution containing 10% by mass of copolymerized polyamide C1. The membrane was kept in contact with the aqueous solution at 20°C for 1 hour. After that, the composite semipermeable membrane was held vertically to drain off the excess aqueous solution, and washed with 20°C water for 10 minutes to prepare a composite semipermeable membrane having copolymerized polyamide C1 as a coating layer.

[0400] [Example C2] A composite semipermeable membrane was prepared in the same manner as in Example C1, except that the concentration of copolymerized polyamide C1 was changed to 1% by mass and the holding time to 17 hours.

[0401] [Example C3] A composite semipermeable membrane was prepared in the same manner as in Example C1, except that the concentration of copolymerized polyamide C1 was changed to 0.01% by mass and the holding time was changed to 30 seconds.

[0402] [Example C4] A composite semipermeable membrane was prepared in the same manner as in Example C2, except that copolymerized polyamide C1 was replaced with copolymerized polyamide C2.

[0403] [Example C5] A composite semipermeable membrane was prepared in the same manner as in Example C2, except that copolymerized polyamide C1 was changed to copolymerized polyamide C3.

[0404] [Example C6] A composite semipermeable membrane was prepared in the same manner as in Example C2, except that copolymerized polyamide C1 was replaced with copolymerized polyamide C4.

[0405] [Example C7] A composite semipermeable membrane was prepared in the same manner as in Example C2, except that copolymerized polyamide C1 was replaced with copolymerized polyamide C5.

[0406] [Example C8] A composite semipermeable membrane was prepared in the same manner as in Example C2, except that copolymerized polyamide C1 was replaced with copolymerized polyamide C6.

[0407] [Comparative Example C1] A composite semipermeable membrane C1 was brought into contact with an aqueous solution containing 1% by mass of polyethylene glycol (weight-average molecular weight: 8,000,000). The membrane was kept in contact with the aqueous solution at 20°C for 24 hours. After that, the composite semipermeable membrane was held vertically to drain off excess aqueous solution, and the membrane was washed with 20°C water for 10 minutes to prepare a composite semipermeable membrane.

[0408] [Comparative Example C2] A formic acid solution containing 0.01% by mass of 6-nylon (weight-average molecular weight: 100,000) was brought into contact with the composite semipermeable membrane C1. After contact with the solution, the crosslinked polyamide of the composite semipermeable membrane decomposed and did not exhibit salt removal properties.

[0409] [Comparative Example C3] An aqueous solution containing 2.0% by mass of fully saponified polyvinyl alcohol (molecular weight: 100,000), 0.5% by mass of glutaraldehyde, and 0.1% by mass of sulfuric acid was brought into contact with the entire surface of the separation functional layer of composite semipermeable membrane C1 in an environment controlled at 20°C. With the aqueous solution remaining on the surface of the separation functional layer, a coating layer was formed on the separation functional layer by blowing 70°C hot air onto the composite semipermeable membrane for 3 minutes. After that, the composite semipermeable membrane was held vertically to drain off the excess aqueous solution and washed with 20°C water for 2 minutes. Finally, the composite semipermeable membrane was immersed in a 14% by mass aqueous solution of isopropanol at 20°C for 5 minutes to hydrophilize it and produce a composite semipermeable membrane.

[0410] [Comparative Example C4] A composite semipermeable film was prepared in the same manner as in Example C2, except that copolymerized polyamide C1 was replaced with copolymerized polyamide C7 and the holding time was changed to 10 hours.

[0411] Table C1 shows the performance evaluation results of the composite semipermeable membranes of Reference Examples C1-C2, Examples C1-C8, and Comparative Examples C1-C4.

[0412]

[0413] [Reference Example C3] A composite semipermeable membrane was prepared in the same manner as in Example C1, except that composite semipermeable membrane C1 was replaced with composite semipermeable membrane C2 and the holding time was changed to 17 hours.

[0414] [Reference Example C4] The evaluation results for composite semipermeable membrane C2 are shown in Table 2.

[0415] [Example C9] A composite semipermeable membrane was prepared in the same manner as in Example C3, except that composite semipermeable membrane C1 was replaced with composite semipermeable membrane 2, and the holding time was changed to 17 hours.

[0416] Table C2 shows the performance evaluation results of the composite semipermeable membranes of Reference Examples C3-C4 and Example C9.

[0417]

[0418] [Reference Example C5] Using the composite semipermeable membrane C1, immersion treatment and immersion treatment in hydrogen peroxide solution were performed, respectively.

[0419] [Example C10] Using the composite semipermeable membrane obtained in Example C2, immersion treatment and immersion treatment in hydrogen peroxide solution were performed, respectively.

[0420] [Comparative Example C5] Using the composite semipermeable membrane obtained in Comparative Example C1, immersion treatment and immersion treatment in hydrogen peroxide solution were performed, respectively.

[0421] Table C3 shows the performance evaluation results for Reference Examples C2, C4, C5, Example C10, and Comparative Example C5.

[0422]

[0423] Table C4 shows the structure of the polymer contained in the coating layer of each example and comparative example.

[0424]

[0425] As shown in Tables C1 and C2, the composite semipermeable film according to this embodiment showed high abrasion resistance. Furthermore, as shown in Table C3, the composite semipermeable film according to this embodiment showed high chemical resistance. Reference examples C2 and C4 showed low abrasion resistance but high chemical resistance.

[0426] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications are possible without departing from the spirit and scope of the invention. Furthermore, the elements of the first, second, and third embodiments described above can be combined in any way. This application is based on Japanese Patent Application No. 2024-229607, Japanese Patent Application No. 2024-229610, and Japanese Patent Application No. 2024-229611, filed on December 26, 2024, which are incorporated herein by reference in their entirety.

[0427] 1. Composite semipermeable membrane 2. Support membrane 3. Separation functional layer 4. Coating layer 5. Maximum peak intensity 6. 80% of the maximum peak intensity 7. Wavewidth w at which the peak intensity is 80% of the maximum peak intensity ８０％ 8. Inside of the protrusion 9. Composite semipermeable membrane element 10. End plate 11. End plate 12. Supply side channel material 13. Permeation side channel material 14. Water collection pipe 15. Supply water 16. Permeate water 17. Concentrated water 18. Weight 19. Polypropylene net 20. Metal plate 21. Tensile testing machine 22. Pulley

Claims

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 0.70 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). [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). [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). [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). In the 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 less carbon atoms or a functional group having 2 or less 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 exists, and the wavenumber width w is such that the peak intensity is 80% of the maximum intensity of the peak originating from 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 according to claim 1 or 2.

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

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

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