Composite semipermeable membrane, composite semipermeable membrane element, and method for producing composite semipermeable membrane

Abstract

The present invention relates to a composite semipermeable membrane comprising a porous support layer and a separation functional layer that is provided on the porous support layer, wherein: the separation functional layer contains a crosslinked aromatic polyamide which includes a structure represented by general formula (I) disclosed in the specification; and, in a TOF-SIMS surface analysis of the surface side of the separation functional layer, the ratio B / A of the peak intensity B of a fragment having the maximum peak intensity among peaks of fragments derived from the structure including R4 in general formula (I) to the peak intensity A of m / z=75.02 is 1.5×10-2 to 50.0×10-2.

Description

Composite semipermeable membrane, composite semipermeable membrane element, and method for manufacturing a composite semipermeable membrane

[0001] The present invention relates to a composite semipermeable membrane, a composite semipermeable membrane element, and a method for producing a composite semipermeable membrane, which are useful for the selective separation of liquid mixtures.

[0002] Regarding the separation of liquid mixtures, various techniques exist for removing substances (e.g., salts) dissolved in a solvent (e.g., water). In particular, the use of membrane separation methods has been expanding in recent years as a process for saving energy and resources. Membranes used in membrane separation methods include microfiltration membranes, ultrafiltration membranes, nanofiltration membranes, and reverse osmosis membranes. These membranes are used, for example, to obtain drinking water from water containing salts or harmful substances, to produce industrial ultrapure water, to treat wastewater, and to recover valuable materials.

[0003] Most reverse osmosis membranes and nanofiltration membranes currently on the market are composite semipermeable membranes in which a separation functional layer having the ability to separate salts and other substances is coated on a support membrane. There are two types of composite semipermeable membranes: those having an active layer formed by crosslinking a gel layer and a polymer on a support membrane, and those having an active layer formed by polycondensation of monomers on a support membrane. Among the latter type of composite semipermeable membrane, composite semipermeable membranes having a separation functional layer containing a crosslinked polyamide obtained by the polycondensation reaction of a polyfunctional amine and a polyfunctional acid halide are widely used as separation membranes with high permeability and selective separation (Patent Document 1). These composite semipermeable membranes require higher salt removal capabilities so that treated water of higher quality can be obtained from saline water.

[0004] As a means of improving the salt removal properties of composite semipermeable membranes, post-treatment methods are known that involve converting the amine ends of crosslinked aromatic polyamides by means of a diazo coupling reaction, contact with a bromine-containing free chlorine aqueous solution, or contact with a low-temperature aqueous solution containing aldehydes or epoxides (see Patent Documents 2, 3, and 4).

[0005] Furthermore, in various water treatment processes such as water desalination plants, operations are designed so that the chlorine added in the pretreatment process does not come into contact with the composite semipermeable membrane. However, there is a risk that chlorine leaks due to operational errors and comes into contact with the composite semipermeable membrane, causing oxidative degradation of the membrane. Therefore, studies are being conducted to improve the chlorine resistance of composite semipermeable membranes in order to reduce the risk of membrane degradation due to chlorine leakage and to extend the membrane lifespan. As methods for improving chlorine resistance, for example, a method using sodium m-phenylenediamine-4-sulfonate as a polyfunctional amine which is a monomer component that forms the separation functional layer (see Patent Document 5), and a method in which the terminal amino group of the polyamide that forms the separation functional layer is reacted with a carboxylic acid (see Patent Document 6).

[0006] International Publication No. 2010 / 096563, Japanese Patent Publication No. 2007-090192, Japanese Patent Publication No. 2001-259388, International Publication No. 2006 / 051888, Japanese Patent Publication No. 63-137704, International Publication No. 2020 / 091007

[0007] However, while the composite semipermeable membranes described in Patent Documents 5 and 6 have high chlorine resistance, no membrane has been obtained that also possesses high water-recycling and salt-removing properties. Therefore, the present invention aims to provide a composite semipermeable membrane that combines chlorine resistance, salt-removing properties, and water-recycling properties.

[0008] To achieve the above objective, the present invention comprises the following configurations [1] to [5]: [1] A porous support layer and a separation functional layer provided on the porous support layer, wherein the separation functional layer contains a crosslinked aromatic polyamide having a structure represented by the following general formula (I), and in surface analysis of the surface layer of the separation functional layer by TOF-SIMS, a peak intensity A at m / z = 75.02 and R in the general formula (I) ４ The ratio B / A of the peak intensity of the fragment with the highest peak intensity among the peaks of the fragments derived from the structure containing the structure is 1.5 × 10 －２ The above 50.0 x 10 －２ The following is a composite semipermeable membrane.

[0009]

[0010] [In general formula (I), Ar １ to Ar ３ are each independently an optionally substituted aromatic ring having 5 to 14 carbon atoms, and Ar １ to Ar ３ has at least one substituted benzene ring. R １ to R ３ are each independently a hydrogen atom or an optionally substituted aliphatic chain having 1 to 10 carbon atoms. R ４ is a structure represented by the following general formula (II). n is an integer of 1 or greater.]]

[0011]

[0012] [In general formula (II), X １ to X ４ are each independently a hydrogen atom, an optionally substituted hydrocarbon group having 1 to 4 carbon atoms, an optionally substituted ester group having 1 to 4 carbon atoms, an optionally substituted alkoxy group having 1 to 4 carbon atoms, or a halogen; and the total number of carbon atoms in X １ to X ４ is 16 or less. Further, X １ to X ４ may be bonded directly or indirectly to form a cyclic structure. The wavy line represents the bonding site to Ar １ in the above general formula (I).] [2] The composite semipermeable membrane according to [1] above, wherein the surface zeta potential of the separation functional layer at pH 3.0 is −10.0 mV or more and 10.0 mV or less. [3] In a surface analysis of the separation functional layer on the porous support layer side by TOF-SIMS, the peak intensity C at m / z=75.02, and R in the above general formula (I) ４A composite semipermeable membrane according to [1] or [2] above, wherein the ratio E of the ratio B / A to the ratio D / C of the peak intensity D of the fragment with the highest peak intensity among the peaks of the fragments derived from the structure containing is 1.5 or more. [4] A composite semipermeable membrane element comprising the composite semipermeable membrane according to any one of [1] to [3] above. [5] A method for producing a composite semipermeable membrane according to any one of [1] to [3] above, comprising the following steps (a) and (b). Step (a): A step of forming the separation functional layer containing the crosslinked aromatic polyamide on the porous support layer. Step (b): A step of contacting the separation functional layer with a processing solution containing a compound represented by the following general formula (III) at 45°C or higher.

[0013]

[0014] [In general formula (III), Z １ Z ２ Each of these is independently a formyl group, an acetal group, a hemiacetal group, a hemiaminal group, or an aminal group. １ ~X ４ Each is independently a hydrogen atom, an optionally substituted hydrocarbon group having 1 to 4 carbon atoms, an optionally substituted ester group having 1 to 4 carbon atoms, an optionally substituted alkoxy group having 1 to 4 carbon atoms, or a halogen, X １ ~X ４ The total number of carbon atoms is 16 or less. Also, X １ ~X ４ They may be directly or indirectly connected to form a ring structure.

[0015] According to the present invention, a composite semipermeable membrane possessing chlorine resistance, salt removal properties, and water-forming properties can be obtained.

[0016] Embodiments of the present invention will be described in detail below, but the present invention is not limited thereto.

[0017] In this specification, for example, "mass%" and "weight%" are synonymous, and "parts by mass" and "parts by weight" are synonymous.

[0018] 1. Composite Semipermeable Membrane The composite semipermeable membrane according to this embodiment comprises a porous support layer and a separation function layer provided on the porous support layer. Hereinafter, the "up and down" direction refers to the thickness direction of the composite semipermeable membrane. The separation function layer is positioned "on top" of the porous support layer.

[0019] The porous support layer of the composite semipermeable membrane according to this embodiment may be formed on a substrate. In this case, the configuration including the substrate and the porous support layer formed on the substrate is also referred to as the "support membrane".

[0020] The separation functional layer substantially possesses separation capabilities, while the porous support layer substantially does not possess separation capabilities for ions, etc., and can provide strength to the separation functional layer.

[0021] 1.1 Support film As described above, the support film includes a substrate and a porous support layer formed on the substrate.

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

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

[0024] Examples of materials for the porous support layer include homopolymers or copolymers such as polysulfone (hereinafter referred to as "PSf"), polyethersulfone, polyamide, polyester, cellulose polymers, vinyl polymers, polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfone, and polyphenylene oxide, which can be used individually or in blends. Examples of cellulose polymers include cellulose acetate and cellulose nitrate, and examples of vinyl polymers include polyethylene, polypropylene, polyvinyl chloride, and polyacrylonitrile. Among these, PSf, cellulose acetate, polyphenylene sulfide sulfone, or polyphenylene sulfone are preferred, with PSf being particularly preferred due to its high chemical, mechanical, and thermal stability and ease of molding.

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

[0026] The sum of the thicknesses of the substrate and the porous support layer, i.e., the thickness of the support film, affects the strength of the composite semipermeable membrane and the packing density when it is used as an element. To obtain good mechanical strength and packing density, the thickness of the support film is preferably 30 μm to 300 μm, and more preferably 100 μm to 220 μm. The thickness of the porous support layer is preferably 20 μm to 100 μm. The thickness of the support film and the porous support layer are determined by measuring the thickness at 20 μm intervals in a direction perpendicular to the thickness direction (the surface direction of the film) during cross-sectional observation, and taking the average value of the thicknesses obtained at 20 points.

[0027] 1.2 Separation Functional Layer The separation functional layer of the composite semipermeable membrane according to this embodiment is a layer responsible for the solute separation function and contains a crosslinked aromatic polyamide having a structure represented by the following general formula (I). Furthermore, it is preferable that the separation functional layer has a crosslinked aromatic polyamide as its main component.

[0028] "Mainly composed of crosslinked aromatic polyamide" means that the proportion of crosslinked aromatic polyamide in the separation functional layer is 50% by mass or more. Preferably, the proportion of crosslinked aromatic polyamide in the separation functional layer is 80% by mass or more, more preferably 90% by mass or more, and even more preferably the separation functional layer is substantially made up of only crosslinked aromatic polyamide. "The separation functional layer is substantially made up of only crosslinked aromatic polyamide" means that the proportion of crosslinked aromatic polyamide in the separation functional layer is 99% by mass or more.

[0029]

[0030] In the above general formula (I), Ar １ ~Ar ３ Each of these is an aromatic ring having 5 to 14 carbon atoms, and Ar １ ~Ar ３ At least one of them is a benzene ring having a substituent. １ ~R ３ Each of these is an aliphatic chain with 1 to 10 hydrogen atoms or optionally substituted carbon atoms. ４ The structure is represented by the following general formula (II), where n is an integer greater than or equal to 1.

[0031]

[0032] X in general formula (II) １ ~X ４ Each is independently a hydrogen atom, an optionally substituted hydrocarbon group having 1 to 4 carbon atoms, an optionally substituted ester group having 1 to 4 carbon atoms, an optionally substituted alkoxy group having 1 to 4 carbon atoms, or a halogen, X １ ~X ４ The total number of carbon atoms is 16 or less. １ ~X ４ These may be directly or indirectly connected to form a ring structure. The dashed line represents Ar in general formula (I). １ It refers to the point of connection with.

[0033] "Cross-linked aromatic polyamide" means that the aromatic polyamide, which is a polymer of a polyfunctional aromatic amine and a polyfunctional aromatic acid halide, forms a cross-linked structure. For example, the aromatic polyamide may form a cross-linked structure via a cross-linking agent, and at least one of the polyfunctional aromatic amine and the polyfunctional aromatic acid halide may be trifunctional or more, and the aromatic polyamide may form a network-like cross-linked structure. In particular, it is more preferable that at least one of the polyfunctional aromatic amine and the polyfunctional aromatic acid halide is trifunctional or more, and the aromatic polyamide forms a network-like cross-linked structure. It is especially preferable that at least one of the polyfunctional aromatic amine or the polyfunctional aromatic acid halide contains a benzene ring and forms a cross-linked structure via the benzene ring.

[0034] A "polyfunctional aromatic amine" refers to an aromatic amine that has two or more amino groups, at least one of either a primary amino group or a secondary amino group, in a single molecule, and at least one of these amino groups is a primary amino group. The aromatic ring derived from the polyfunctional aromatic amine is represented by Ar in general formula (I). １ and Ar ３ It corresponds to this.

[0035] Examples of polyfunctional aromatic amines include o-phenylenediamine, m-phenylenediamine (hereinafter referred to as "m-PDA"), p-phenylenediamine, o-xylylenediamine, m-xylylenediamine, p-xylylenediamine, o-diaminopyridine, m-diaminopyridine, p-diaminopyridine, and other polyfunctional aromatic amines in which two amino groups are bonded to the aromatic ring in an ortho, meta, or para position; 1,3,5-triaminobenzene, 1,2,4-triaminobenzene, 3,5-diaminobenzoic acid, 3-aminobenzylamine, and 4-aminobenzylamine.

[0036] In particular, considering the selective separation, permeability, and heat resistance of the membrane, m-PDA, p-phenylenediamine, and 1,3,5-triaminobenzene are preferred as polyfunctional aromatic amines. The polyfunctional aromatic amine constituting the aromatic polyamide may be one type or two or more types.

[0037] A "polyfunctional aromatic acid halide" refers to an aromatic acid halide having at least two halogenated carbonyl groups in one molecule. The aromatic ring derived from the polyfunctional aromatic acid halide is represented by Ar in general formula (I). ２ It corresponds to this.

[0038] Examples of trifunctional aromatic acid halides include trimesic acid chloride, and examples of bifunctional aromatic acid halides include biphenyldicarboxylic acid dichloride, azobenzenedicarboxylic acid dichloride, terephthalic acid chloride, isophthalic acid chloride, and naphthalenedicarboxylic acid chloride. Among acid halides, acid chlorides are preferred. In particular, trimesic acid chloride (hereinafter referred to as "TMC"), an acid halogen of 1,3,5-benzenetricarboxylic acid, isophthalic acid chloride, an acid halogen of 1,3-benzenedicarboxylic acid, and terephthalic acid chloride, an acid halogen of 1,4-benzenedicarboxylic acid, are preferred in terms of economy, availability, ease of handling, and reactivity.

[0039] Ar in the above general formula (I) １ ~Ar ３ From the viewpoint of chemical stability and steric hindrance, the Ar in the general formula (I) is preferably an aromatic ring having 5 to 14 carbon atoms, preferably an aromatic ring having 6 to 10 carbon atoms, and more preferably an aromatic ring having 6 carbon atoms, i.e., a benzene ring. Furthermore, from the viewpoint of ensuring an appropriate free volume for water permeation in the separation functional layer, １ ~Ar ３ Preferably, at least one of the rings is a C6 aromatic ring, i.e., a benzene ring, and more preferably, all of them are benzene rings. The aromatic rings, such as benzene rings, having 5 to 14 carbon atoms may be unsubstituted or may have substituents. Examples of substituents on aromatic rings, such as benzene rings, having 5 to 14 carbon atoms include amino groups, carboxyl groups, methyl groups, chloro groups, and bromo groups, and other substituents may be present as long as they do not hinder the effects of the present invention. Furthermore, the aromatic polyamide may form a crosslinked structure via substituents. Note that Ar in the above general formula (I) １ ~Ar ３At least one of them is a benzene ring having a substituent.

[0040] In the above general formula (I), R １ ~R ３ If the aliphatic chain may be substituted, the number of carbon atoms is preferably 1 to 4 from the viewpoint of steric hindrance, and more preferably 1 carbon atom. Also, in the above general formula (I), R １ ~R ３ From the viewpoint of forming hydrogen bonds between the crosslinked aromatic polyamides constituting the separation functional layer and contributing to improved selective permeability, it is preferable that at least one of them be a hydrogen atom, and more preferably that all of them be hydrogen atoms.

[0041] The structure represented by the above general formula (II), that is, R in general formula (I) ４ The nitrogen atom in this structure originates from the amino group at the crosslinked aromatic polyamide terminus. In other words, the structure represented by general formula (II) is obtained by the reaction of the amino group at the crosslinked aromatic polyamide terminus with the compound represented by general formula (III), which will be described later, and contributes to improved salt removal and chlorine resistance.

[0042] X in the above general formula (II) １ ~X ４ Examples of hydrocarbon groups having 1 to 4 carbon atoms that may be substituted include methyl groups and ethyl groups. Examples of ester groups having 1 to 4 carbon atoms that may be substituted include acetoxy groups. Examples of alkoxy groups having 1 to 4 carbon atoms that may be substituted include methoxy groups. Examples of halogens include fluoro groups, chloro groups, and bromo groups. X １ ~X ４ However, in the case of hydrocarbon groups, ester groups, or alkoxy groups, it is preferable that they do not have substituents from the viewpoint of chemical stability and steric hindrance. Examples of substituents when these hydrocarbon groups, ester groups, or alkoxy groups are substituted with substituents include fluoro groups, chloro groups, bromo groups, and methoxy groups.

[0043] Also, X １ ~X ４The total number of carbon atoms is preferably 4 or less, and more preferably 2 or less, from the viewpoint of steric hindrance. In particular, X １ ~X ４ It is preferable that X is a hydrogen atom. １ ~X ４ It is particularly preferable that all of them are hydrogen atoms.

[0044] In the above general formula (I), R ４ That is, the presence or absence and abundance of the structure represented by general formula (II) can be evaluated by TOF-SIMS. In TOF-SIMS, Bi is applied to the surface of the sample under vacuum as a primary ion beam. ３ ＋＋ When irradiated, secondary ions are emitted from a region several nanometers deep from the surface of the sample. By introducing these secondary ions into a time-of-flight (TOF) mass spectrometer, information about the chemical structure of the sample surface can be obtained. Mass spectrometry is performed on the positive secondary ions.

[0045] Bi is found on the separation functional layer surface of the composite semipermeable membrane, which is the measurement sample. ３ ＋＋ When irradiated, some of the covalent bonds of the crosslinked aromatic polyamide constituting the separation functional layer are cleaved, yielding fragments. Here, R in general formula (I) ４ That is, fragments derived from structures containing the structure represented by general formula (II) are mainly obtained, and fragments represented by the following general formula (IV) are obtained. Depending on the presence or absence of peaks in these fragments, the crosslinked aromatic polyamide of the separation functional layer is R ４ It can be confirmed that it contains the structure of

[0046]

[0047] In the above general formula (IV), Ar １ X is an aromatic ring having 5 to 14 carbon atoms, which may be substituted. １ ~X ４ Each is independently a hydrogen atom, an optionally substituted hydrocarbon group having 1 to 4 carbon atoms, an optionally substituted ester group having 1 to 4 carbon atoms, an optionally substituted alkoxy group having 1 to 4 carbon atoms, or a halogen, X １ ~X ４ The total number of carbon atoms is 16 or less. Also, X１ ~X ４ These may be directly or indirectly bonded to form a cyclic structure. The dot in the upper right corner represents a radical.

[0048] For example, Ar in general formula (I) １ If the benzene ring is unsubstituted, and the structure represented by general formula (II) originates from the reaction of the terminal amino group of the crosslinked aromatic polyamide with o-phthalaldehyde, then m / z = 208.08; if it originates from the reaction of the terminal amino group of the crosslinked aromatic polyamide with 3-methylphthalaldehyde, then m / z = 222.09; and if it originates from the reaction of the terminal amino group of the crosslinked aromatic polyamide with 4-bromophthalaldehyde, then m / z = 285.99. A peak is obtained at m / z = 266.08 when the reaction originates from the terminal amino group of a fragrance polyamide with methyl 3,4-diformylbenzoate, at m / z = 252.07 when the reaction originates from the terminal amino group of a crosslinked aromatic polyamide with benzo[d][1,3]dioxol-4,5-dicarbaldehyde, and at m / z = 258.09 when the reaction originates from the terminal amino group of a crosslinked aromatic polyamide with naphthalene-2,3-dicarbaldehyde.

[0049] In surface analysis of the separation functional layer on the surface side of the composite semipermeable membrane according to this embodiment, a peak intensity A at m / z = 75.02 and R in the above general formula (I) were observed. ４ Among the peaks of fragments originating from the structure containing the above, the ratio B / A of the peak intensity of the fragment with the highest peak intensity to the peak intensity B of the fragment with the highest peak intensity is 1.5 × 10 －２ The above 50.0 x 10 －２ The following applies. Here, "the surface of the separation functional layer on the surface side" refers to the surface of the separation functional layer that is opposite to the surface in contact with the porous support layer.

[0050] Analysis of the separation functional layer surface of a composite semipermeable membrane having a separation functional layer containing a crosslinked aromatic polyamide by TOF-SIMS revealed fragments (C) derived from the benzene ring, which is the backbone of the crosslinked aromatic polyamide. ６ H ３ ＋ ) is obtained as a peak at m / z = 75.02. Specifically, C６ H ３ ＋ fragment is derived from a benzene ring having a substituent or a benzene ring that forms a crosslinked structure of a crosslinked aromatic polyamide described later. That is, the ratio B / A is R in general formula (I) relative to the crosslinked structure of the crosslinked aromatic polyamide in the separation functional layer ４ which reflects the proportion of the structure represented by general formula (II). When the ratio B / A is 1.5×10 －２ or more, a sufficient amount of the structure represented by general formula (II) is contained, and the pore diameter of the separation functional layer is reduced, so that the salt removal performance of the composite semipermeable membrane is improved. In addition, when the ratio B / A is 50.0×10 －２ or less, the decrease in water permeability caused by excessive introduction of the structure represented by general formula (II) can be suppressed. From the above viewpoint, the ratio B / A is 2.0×10 －２ or more and 10.0×10 －２ or less is more preferable, 3.0×10 －２ or more and 5.0×10 －２ or less is even more preferable.

[0051] The ratio B / A can be controlled, for example, by the introduction amount of R in general formula (I) into the crosslinked aromatic polyamide ４ Specifically, it can be controlled by the contact time, the temperature of the treatment liquid, pH, the concentration of the compound and the like when the separation functional layer is brought into contact with a treatment liquid containing the compound represented by general formula (III) described in "2.2.2 Modification step of separation functional layer" mentioned later.

[0052] In the composite semipermeable membrane according to the present embodiment, the surface zeta potential of the separation functional layer at pH 3.0 is preferably -10.0 mV or more and 10.0 mV or less, more preferably 0 mV or more and 6.0 mV or less, and even more preferably 0 mV or more and 3.7 mV or less. Zeta potential is a measure of the net fixed charge on the surface of a flat plate sample. The crosslinked aromatic polyamide contained in the separation functional layer mainly has amino groups and carboxy groups as terminal functional groups, and the dissociation degree of these groups depends on pH. Under the condition of pH 3.0, amino groups are mainly positively charged, and carboxy groups are mainly neutral. Therefore, the surface zeta potential of the separation functional layer at pH 3.0 is considered to mainly depend on the amount of amino groups. The structure represented by general formula (II) is introduced in a form that modifies the terminal amino groups of the crosslinked aromatic polyamide, so the amount of amino groups decreases as the introduction amount increases. That is, the surface zeta potential of the separation functional layer at pH 3.0 can be controlled by the introduction amount of the structure represented by general formula (II). Therefore, when the surface zeta potential of the separation functional layer at pH 3.0 is 10.0 mV or less, the structure represented by general formula (II) is sufficiently introduced into the separation functional layer, and the salt rejection rate is further improved. In addition, when the surface zeta potential of the separation functional layer at pH 3.0 is -10.0 mV or more, the decrease in water productivity caused by excessive introduction of the structure represented by general formula (II) can be suppressed.

[0053] The surface zeta potential of the separation functional layer at pH 3.0 is, for example, R in general formula (I) for crosslinked aromatic polyamides ４ can be controlled by the introduction amount of . Specifically, it can be controlled by the contact time when the separation functional layer is brought into contact with a treatment liquid containing a compound represented by general formula (III) described in "2.2.2 Step of modifying a separation functional layer" which will be described later, the temperature of the treatment liquid, pH, the concentration of the compound, and the like.

[0054] In the composite semipermeable membrane according to the present embodiment, in the surface analysis of the separation functional layer on the porous support layer side performed by TOF-SIMS, the peak intensity C at m / z = 75.02 and R in general formula (I) ４It is preferable that the ratio E of the ratio B / A to the ratio D / C of the peak intensity D of the fragment with the highest peak intensity among the peaks of the fragments derived from the structure containing the (i.e., (ratio B / A) / (ratio D / C)) is 1.5 or more, more preferably 1.5 or more and 10.0 or less, even more preferably 2.0 or more and 7.0 or less, and particularly preferably 3.0 or more and 5.0 or less.

[0055] A ratio E greater than 1.0 means that more of the structure represented by general formula (II) is introduced to the surface of the separation functional layer than to the surface on the porous support layer side of the separation functional layer. When the ratio E is 1.5 or higher, the structure represented by general formula (II) is sufficiently introduced to the surface side of the separation functional layer, exhibiting high salt removal performance due to the steric hindrance of the structure represented by general formula (II), and the amount of the structure represented by general formula (II) introduced to the cross-linked aromatic polyamide on the surface of the separation functional layer on the porous support layer side and inside the separation functional layer is small, resulting in less steric hindrance due to the structure represented by general formula (II) and higher water desiccation. On the other hand, if the amount of the structure represented by general formula (II) introduced to the surface side of the separation functional layer becomes too large, there is a risk of decreased water desiccation. When the ratio E is 10.0 or lower, sufficient chlorine resistance and water desiccation are easily obtained.

[0056] Furthermore, the ratio D / C is 0.1 × 10 －２ The above 30.0 x 10 －２ The following is preferable: 0.3 × 10 －２ The above 5.0 x 10 －２ The following is more preferable: 0.6 × 10 －２ The above 1.5 x 10 －２ The following is even more preferable: a ratio D / C of 30.0 × 10 －２ When the following conditions are met, the amount of structure represented by general formula (II) introduced into the crosslinked aromatic polyamide on the porous support layer side of the separation functional layer and inside the separation functional layer is reduced, the steric hindrance caused by the structure represented by general formula (II) is reduced, and higher water-purifying properties are obtained. Also, when the ratio D / C is 0.1 × 10⁻⁶ －２ As described above, the introduction of the structure represented by general formula (II) within the separation functional layer provides chlorine resistance.

[0057] Surface analysis of the separation functional layer on the porous support layer side can be performed by transferring the separation functional layer onto a silicon wafer and then performing TOF-SIMS on it. Specifically, the measurement is performed using the method described in "TOF-SIMS" in the examples described later.

[0058] Ratio E is, for example, R in general formula (I) to crosslinked aromatic polyamide in the vertical direction of the separation functional layer. ４ This can be controlled by creating a gradient in the amount introduced. Specifically, as described in "2.2.2 Modification process of the separation functional layer," it can be controlled by the method of contacting the processing solution containing the compound represented by general formula (III) with the separation functional layer, the contact time, the concentration of the compound, etc.

[0059] To prevent the substance to be separated from penetrating into the interior of the composite semipermeable membrane, the separation functional layer is preferably located on the surface side of the composite semipermeable membrane, and more preferably on the primary side of filtration.

[0060] 2. Method for Manufacturing a Composite Semipermeable Membrane The method for manufacturing a composite semipermeable membrane of the present invention is not particularly limited as long as a composite semipermeable membrane satisfying the desired characteristics described above can be obtained, but for example, it can be manufactured by the following method.

[0061] 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.

[0062] First, PSf is dissolved in a suitable solvent to prepare a porous support layer stock solution. A suitable solvent for PSf is, for example, N,N-dimethylformamide (hereinafter referred to as "DMF").

[0063] The PSf concentration in the porous support layer stock solution is preferably 12% to 25% by mass, and more preferably 14% to 23% by mass. The higher the polymer concentration (i.e., solid content concentration) in the porous support layer stock solution, the higher the number density of particles on the surface of the porous support layer that can be obtained. As a result, the number density of protrusions in the separation function layer also increases, enabling the realization of a protrusion structure that can withstand pressure fluctuations. Furthermore, by lowering the polymer concentration, the surface pore diameter of the porous support layer can be adjusted to the extent that the monomer supply rate during separation function layer formation does not become too low. This allows for the formation of protrusions with appropriate height during separation function layer formation. When the PSf concentration in the porous support layer stock solution is within the above range, both the strength and permeability of the resulting porous support layer can be achieved. The preferred range of polymer concentration in the porous support layer stock solution can be appropriately adjusted depending on the materials used, the good solvent, etc.

[0064] Next, the obtained porous support layer stock solution is applied to the substrate surface and immersed in a coagulation bath containing a non-solvent of PSf. Water is preferred as the non-solvent of PSf in the coagulation bath. By bringing the porous support layer stock solution applied to the substrate surface into contact with the coagulation bath containing a non-solvent of PSf, the porous support layer stock solution coagulates through non-solvent-induced phase separation, and a support film with a porous support layer formed on the substrate surface can be obtained. The coagulation bath may consist only of a non-solvent of PSf, or it may contain a good solvent of PSf to the extent that the porous support layer stock solution can coagulate. The obtained support film may be washed before the formation of the separation functional layer to remove any remaining solvent in the film.

[0065] 2.2 Preparation of the Separation Functional Layer The method for producing a composite semipermeable membrane according to this embodiment comprises the following steps (a) and (b). Step (a): A step of forming a separation functional layer containing a crosslinked aromatic polyamide on a porous support layer. Step (b): A step of bringing the separation functional layer into contact with a treatment solution containing a compound represented by the following general formula (III) at a temperature of 45°C or higher.

[0066]

[0067] In the above general formula (III), Z １ Z ２Each of these is independently a formyl group, an acetal group, a hemiacetal group, a hemiaminal group, or an aminal group. １ ~X ４ Each is independently a hydrogen atom, an optionally substituted hydrocarbon group having 1 to 4 carbon atoms, an optionally substituted ester group having 1 to 4 carbon atoms, an optionally substituted alkoxy group having 1 to 4 carbon atoms, or a halogen, X １ ~X ４ The total number of carbon atoms is 16 or less. Also, X １ ~X ４ They may be directly or indirectly bonded to form a ring structure.

[0068] 2.2.1 Formation of the Separation Functional Layer A method for forming a separation functional layer containing crosslinked aromatic polyamide will be described using as an example a method in which a polyfunctional aromatic amine and a polyfunctional aromatic acid halide are polycondensed on the support film obtained in "2.1 Formation of the Support Film" to form a separation functional layer containing crosslinked aromatic polyamide. From the viewpoint of productivity and performance, interfacial polymerization is the most preferred polymerization method. The interfacial polymerization process will be described below.

[0069] In the method for producing a composite semipermeable membrane according to this embodiment, the step (a) for forming the separation functional layer preferably includes the steps of: (a1) contacting an aqueous solution containing a polyfunctional aromatic amine with a support membrane; (a2) contacting an organic solvent solution containing a polyfunctional aromatic acid halide with the support membrane that has been contacted with the aqueous solution containing the polyfunctional aromatic amine; (a3) ​​draining the organic solvent solution after contact; and (a4) washing the composite semipermeable membrane. Even before carrying out step (b) described later, the layer containing the crosslinked aromatic polyamide may be referred to as the separation functional layer. Furthermore, a composite membrane having a substrate, a porous support layer, and a layer containing the crosslinked aromatic polyamide may be referred to as a composite semipermeable membrane.

[0070] Examples of porous support layers, polyfunctional aromatic amines, and polyfunctional aromatic acid halides include those mentioned above, and the same applies to preferred materials. In particular, from the viewpoint of easily forming crosslinked aromatic polyamides, it is preferable to use m-PDA as the polyfunctional aromatic amine and TMC as the polyfunctional aromatic acid halide.

[0071] In step (a1), the concentration of the polyfunctional aromatic amine in the aqueous solution containing the polyfunctional aromatic amine (hereinafter referred to as "amine aqueous solution") is preferably 0.1% by mass or more and 20% by mass or less, and more preferably 0.5% by mass or more and 15% by mass or less. When the concentration of the polyfunctional aromatic amine is within the above range, sufficient salt removal performance and water formation performance can be obtained. Two or more types of polyfunctional aromatic amines may be used.

[0072] In step (a1), it is preferable that the aqueous solution be brought into uniform and continuous contact with the support film. Specifically, examples include surface coating of the amine aqueous solution onto the support film (on the porous support layer) and immersion of 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.

[0073] After the aqueous solution has come into contact with the support film, it is preferable to remove any remaining droplets from the film. Removing the liquid helps to suppress the occurrence of defects in the separation layer. Methods for removing the liquid include, for example, holding the support film vertically after contact with the aqueous solution to allow excess solution to flow naturally, or forcibly removing the liquid by blowing a stream of air such as nitrogen from an air nozzle. After removing the liquid, the film surface can also be dried to remove some of the water from the aqueous solution.

[0074] In step (a2), examples of polyfunctional aromatic acid halides include TMC, biphenyldicarboxylic acid dichloride, azobenzenedicarboxylic acid dichloride, terephthalic acid chloride, isophthalic acid chloride, naphthalenedicarboxylic acid chloride, and 2,5-franzicarboxylic acid chloride. These polyfunctional aromatic acid chlorides may be used individually or in combination of two or more.

[0075] The organic solvent is preferably immiscible with water, dissolves polyfunctional aromatic acid halides, does not damage the support film, and is inert to polyfunctional aromatic amines and polyfunctional aromatic 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.

[0076] The concentration of the polyfunctional aromatic acid halide in the organic solvent solution containing the polyfunctional aromatic acid halide (hereinafter referred to as "acid halide 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 aromatic 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 aromatic acid halide is 10% by mass or less, the occurrence of side reactions during polymerization can be suppressed.

[0077] The amine aqueous solution and the acid halide solution may contain, if necessary, compounds such as surfactants, antioxidants, and metal salts, as long as they do not inhibit polymerization.

[0078] The method for bringing an acid halide solution into contact with a support film that has been in contact with an amine aqueous solution can be carried out in the same manner as the method for bringing the amine aqueous solution into contact with the support film.

[0079] In step (a2), it is preferable to heat-treat the film after contacting the support film, which has been in contact with the amine aqueous solution, with the acid halide solution. By promoting the reaction through heat treatment and increasing the molecular weight, it is possible to reduce the low molecular weight components and suppress changes in performance when in contact with chlorine. Furthermore, even if the reaction between the polyfunctional aromatic acid halide and the polyfunctional aromatic amine is suppressed by the hydrolysis of additives or the polyfunctional aromatic acid halide, the polymerization can be sufficiently carried out by accelerating the reaction through heat treatment. The temperature for heat-treating the film is preferably 50°C to 180°C, more preferably 60°C to 160°C, and even more preferably 80°C to 150°C. If the heating temperature is 180°C or lower, it is possible to suppress the decrease in water production due to the thickening of the separation functional layer.

[0080] In step (a3), the organic solvent is removed by draining the acid halide solution after the reaction. For example, the organic solvent can be removed by grasping the film vertically and allowing excess organic solvent to flow down naturally, by blowing air with a fan to dry out the organic solvent, or by using a mixed fluid of water and air to remove excess organic solvent.

[0081] In step (a4), the composite semipermeable membrane is washed with hot water. Washing with hot water removes unreacted monomers and oligomers. The temperature of the hot water used for washing is preferably 40°C to 100°C, and more preferably 60°C to 100°C. By going through these steps (a1) to (a4), a separation functional layer containing a crosslinked aromatic polyamide having the substructure of the following general formula (V) is formed.

[0082]

[0083] In the above formula (V), Ar １ ~Ar ３ Each of these is an aromatic ring having 5 to 14 carbon atoms, and Ar １ ~Ar ３ At least one of them is a benzene ring having a substituent. １ ~R ３ Each is an aliphatic chain with 1 to 10 hydrogen atoms or optionally substituted carbon atoms, and n is an integer of 1 or more. １ ~Ar ３ and R １ ~R ３ Preferred embodiments are the same as those described in the general formula (I) above.

[0084] 2.2.2 Modification Step of Separation Functional Layer The method for producing a composite semipermeable membrane according to this embodiment includes a modification step of the separation functional layer, which comprises step (b): bringing the separation functional layer into contact with a processing solution containing the compound represented by the general formula (III) (hereinafter referred to as "processing solution") at 45°C or higher. In this step, the terminal amino groups of the crosslinked aromatic polyamide are modified by the compound represented by the general formula (III), and a structure represented by the general formula (I) is formed.

[0085] Specific examples of compounds represented by general formula (III) include, for example, phthalaldehyde, 3-methylphthalaldehyde, 4-chlorophthalaldehyde, 4-bromophthalaldehyde, 4,5-dimethoxyphthalaldehyde, 3,4-diformylmethyl benzoate, benzene-1,2,4,5-tetracarbaldehyde, benzo[d][1,3]dioxol-4,5-dicarbaldehyde, naphthalene-2,3-dicarbaldehyde, 1,2-bis(dimethoxymethyl)benzene, 1,2-bis(dimethoxymethyl)-3-methylbenzene, 4-chloro-1,2-bis(dimethoxymethyl)benzene, 4-bromo-1,2-bis(dimethoxymethyl)benzene, 1,2-bis(dimethoxymethyl)-4,5-dimethoxybenzene, 3,4-bis(dimethoxymethyl)methyl benzoate, and 1,2,4,5-tetrakis(dimethoxymethyl) Methyl)benzene, 4,5-bis(dimethoxymethyl)benzo[d][1,3]dioxol, 2,3-bis(dimethoxymethyl)naphthalene, 1,2-di(1,3-dioxolan-2-yl)benzene, 1,2-di(1,3-dioxolan-2-yl)-3-methylbenzene, 4-chloro-1,2-di(1,3-dioxolan-2-yl)benzene, 4-bromo-1,2-di(1,3-dioxolan-2- Examples include 1,2-di(1,3-dioxolan-2-yl)-4,5-dimethoxybenzene, 3,4-di(1,3-dioxolan-2-yl)methyl benzoate, 1,2,4,5-tetra(1,3-dioxolan-2-yl)benzene, 4,5-di(1,3-dioxolan-2-yl)benzo[d][1,3]dioxol, and 2,3-di(1,3-dioxolan-2-yl)naphthalene. １ Z ２ It is preferable that it is a formyl group. １ Z ２ If the group is a formyl group, the structure represented by general formula (I) can be obtained without side reactions.

[0086] In step (b), if the temperature at which the separation functional layer and the processing liquid are brought into contact is 45°C or higher, the reaction between the terminal amino groups of the crosslinked aromatic polyamide and the compound represented by general formula (III) proceeds sufficiently, and the amount of structure represented by general formula (II) introduced increases. Furthermore, if the processing liquid is an aqueous solution, a temperature of 100°C or lower is preferable because it prevents the processing liquid from boiling and also suppresses the thermal contraction of the composite semipermeable membrane, thus preventing a decrease in the amount of water produced. From the above viewpoint, the temperature at which the separation functional layer and the processing liquid are brought into contact is 45°C or higher, preferably 45°C to 100°C, more preferably 60°C to 100°C, and even more preferably 80°C to 100°C. As for methods of controlling the temperature, for example, a method of bringing a processing liquid adjusted to a predetermined temperature into contact with the separation functional layer, or a method of heating after bringing the processing liquid into contact with the separation functional layer. From the viewpoint of being easier to carry out, the method of bringing a processing liquid adjusted to a predetermined temperature into contact with the separation functional layer is preferred.

[0087] The processing solution may be a solution of the compound dissolved in a solvent and brought into contact with the separation functional layer, or a liquid in which the compound is molten may be brought into contact with the layer. When the solution is brought into contact with the separation functional layer, water is preferably used as the solvent. The contact method is the same as the amine aqueous solution in step (a1), including surface coating or immersion. Among these, the contact method by surface coating is more preferable because the solution or molten liquid penetrates only from the surface side of the separation functional layer, resulting in a larger ratio E, that is, more structures represented by general formula (II) can be introduced into the surface side of the separation functional layer. Examples of methods for surface coating include using a spray, a roll coater, or a spin coater.

[0088] When the treatment solution is applied by surface coating, the film surface may be heated in an oven as needed. In this case, if necessary, the film surface may be covered with a heat-resistant film to suppress evaporation of the treatment solution. The amount of treatment solution to be applied should be an amount that can be evenly coated on the separation functional layer, for example, 100 cm². ２ Approximately 1 mL is preferred for the composite semipermeable membrane.

[0089] When the processing liquid is a solution, the appropriate reaction time depends on the concentration and temperature of the compound in the solution, but a reaction time of 10 seconds to 30 minutes is preferable, 10 seconds to 10 minutes is more preferable, and 10 seconds to 2 minutes is even more preferable. Furthermore, the surface on the surface side of the separation functional layer is more likely to come into contact with the processing liquid than the surface on the porous support layer side, and the shorter the reaction time, the less the processing liquid penetrates into the interior, the more selectively the reaction proceeds on the surface side, and the larger the ratio E becomes, so a reaction time of 10 seconds to 1 minute is particularly preferable.

[0090] If the treatment solution is a solution, the concentration of the compound in the solution is preferably 0.1 mmol / L or more and 10 mmol / L or less, and more preferably 0.1 mmol / L or more and 1 mmol / L or less. Since the reaction between the compound represented by general formula (III) and the amino group at the polyamide terminus is accelerated by an acid catalyst, the pH of the treatment solution is preferably 7.0 or less, and more preferably 2.0 or less.

[0091] Furthermore, in another embodiment, when the treatment solution is a solution, the concentration of the compound in the solution is preferably 20 ppm to 1000 ppm, more preferably 20 ppm to 500 ppm, and even more preferably 50 ppm to 100 ppm, from the viewpoint of easily adjusting the amount of structure represented by general formula (II) introduced. Since the reaction between the compound represented by general formula (III) and the amino group at the polyamide terminus is accelerated by an acid catalyst, the pH of the treatment solution is preferably 7.0 or lower, and more preferably 2.0 or lower.

[0092] Furthermore, various processes may be performed after process (b) or between process (a) and process (b).

[0093] 3. Use of Composite Semipermeable Membranes Composite semipermeable membranes are suitably used as spiral-type composite semipermeable membrane elements wound around a cylindrical water collection pipe with numerous perforations, along 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.

[0094] Furthermore, the composite semipermeable membrane, composite semipermeable membrane element, and composite semipermeable membrane module described above can be combined with a pump to supply water to them, a device to pre-treat the supply water, etc., to constitute a fluid separation device. By using this fluid separation device, the supply water can be separated into permeate water such as drinking water and concentrated water that did not permeate the membrane, thereby obtaining water suitable for the purpose.

[0095] In other words, the above-mentioned composite semipermeable membrane can be used in a water treatment system that separates supply water into concentrated water and fresh water using a composite semipermeable membrane element incorporating it.

[0096] Examples of feedwater treated by the composite semipermeable membrane according to this embodiment include liquid mixtures containing a total dissolved solids content (hereinafter referred to as "TDS") of 500 mg / L to 100 g / L, such as seawater, brine, or wastewater. Generally, TDS refers to the total dissolved solids content and is expressed as "mass / volume" or "mass ratio". According to the definition of TDS, it is calculated from the mass of the residue after evaporating a solution filtered through a 0.45 micron filter at a temperature of 39.5 to 40.5°C, but in this specification, it is calculated more simply by converting it from the practical salinity (S).

[0097] A higher operating pressure for the fluid separation device improves the solute removal rate. Considering the increased energy required for operation and the durability of the composite semipermeable membrane, the operating pressure when supplying feedwater to the composite semipermeable membrane is preferably between 0.5 MPa and 10 MPa. If the feedwater temperature is high, the solute removal rate decreases, and if the feedwater temperature is low, the amount of water produced decreases, so the feedwater temperature is preferably between 5°C and 45°C. In addition, if the pH of the feedwater is high, in the case of feedwater with a high solute concentration such as seawater, scale such as magnesium is likely to form and there is a concern that the composite semipermeable membrane may deteriorate, so the pH of the feedwater is preferably in the neutral range.

[0098] The salt removal rate of the composite semipermeable membrane is preferably 99.90% or higher, more preferably 99.93% or higher, and even more preferably 99.95% or higher. The water production volume is 0.85 m³. ３ / m ２ / day or more 1.8m ３ / m ２ Preferably less than 0.93 m / day. ３ / m ２ / day or more 1.8m ３ / m ２ / day or less is more preferable, and 0.95m ３ / m ２ / day or more 1.8m ３ / m ２ Less than / days is even preferable.

[0099] Furthermore, the salt removal rate after the chlorine degradation test is preferably 99.85% or higher, more preferably 99.90% or higher, and even more preferably 99.93% or higher. The ratio of water produced before the chlorine degradation test to the water produced after the chlorine degradation test is preferably 1.00 or more and 1.20 or less, more preferably 1.00 or more and 1.15 or less, and even more preferably 1.00 or more and 1.10 or less. The closer the water produced ratio is to 1.00, the less degradation is caused by chlorine.

[0100] 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.

[0101] <Salt Removal Rate> Seawater (TDS concentration 3.5%) adjusted to a temperature of 25°C and pH 6.5 was supplied at an operating pressure of 5.5 MPa to obtain permeate. The salt removal rate was calculated from the TDS of the obtained permeate using the following formula: Salt removal rate (%) = 100 × {1 - (TDS concentration in permeate / TDS concentration in supply water)}

[0102] <Water Production Volume> The amount of permeate obtained under the conditions described in "Salt Removal Rate" above is calculated as the permeate rate per square meter of membrane surface per day (m³). ３ Convert to (m³), which is an indicator of water production capacity. ３ / m ２ It represented (day).

[0103] <TOF-SIMS> The composite semipermeable membrane was immersed in ethanol for one day, the membrane surface was washed with ultrapure water, and then the composite semipermeable membrane was washed again by immersion in ultrapure water for one day. The washed composite semipermeable membrane was dried in a vacuum dryer for 24 hours. The surface of the separation functional layer on the surface side of the dried composite semipermeable membrane was analyzed under the following conditions. In addition, the measurement sample used for surface analysis of the separation functional layer on the porous support layer side was prepared by transferring the separation functional layer as follows. A 10% polyvinyl alcohol aqueous solution was spin-coated onto a research-grade high-purity silicon wafer, and with the surface side of the separation functional layer of the dried composite semipermeable membrane in close contact with the silicon wafer, it was heated and dried at 50°C for 20 minutes to insoluble polyvinyl alcohol. Subsequently, if the material of the porous support layer was PSf, dichloromethane was added to dissolve the porous support layer, and the substrate was removed to prepare a measurement sample in which the separation functional layer was transferred onto the silicon wafer. If the porous support layer material is other than PSf, a solvent that dissolves the porous support layer but not the separation function layer may be used as appropriate. The obtained sample was analyzed under the same conditions as described below. Measurements were taken at two different locations in the separation function layer, the average value was calculated, and the value was rounded to the fourth decimal place. [Measurement conditions] Measurement device: TOF. SIMS ５ (Manufactured by ION-TOF) Secondary ion polarity: positive Mass range (m / z): 0-1500 Raster size: 300 μm Number of scans: 16 Number of pixels (per side): 256 pixels Measurement vacuum level (before sample introduction): 4 × 10 －７ Primary ion species below Pa: Bi ３ ＋＋ Primary ion acceleration voltage: 25 kV, Pulse width: 3.9 ns, Bunching: Yes, Charge neutralization: Yes, Substage acceleration: 9.5 kV

[0104] <Surface Zeta Potential> A composite semipermeable membrane was cut into 10 cm x 10 cm squares and washed with distilled water. The washed composite semipermeable membrane was set in a plate sample cell, and the surface of the separation functional layer was used as the measurement surface. The surface zeta potential of the separation functional layer at pH 3.0 was measured using an electrophoretic light scattering photometer ELSZneo (manufactured by Otsuka Electronics Co., Ltd.) under the following conditions. Five measurement points were randomly selected, and the average of these values ​​was taken as the zeta potential. [Measurement Conditions] Monitor particle: Polystyrene latex (hydroxypropyl cellulose coated) Measurement solution: NaCl aqueous solution (10 mmol / L) pH 3.0 Particle concentration: 0.1 mass% Average particle size: 500 nm Temperature: 25°C Light source: He-Ne laser

[0105] <Chlorine Degradation Test> A composite semipermeable membrane was immersed in a sodium hypochlorite aqueous solution with a NaCl concentration of 3.4% by mass, an effective chlorine concentration of 25 ppm, and a pH of 8.0, and left to stand at 25°C for 24 hours. After that, the composite semipermeable membrane, which had been washed with pure water, was used to calculate the salt removal rate and water production volume using the methods described above for "salt removal rate" and "water production volume". In addition, the ratio of water production volume before and after the chlorine degradation test was calculated using the following formula. The ratio of water production volume was rounded to the third decimal place. Ratio of water production volume before and after the chlorine degradation test = Water production volume after the chlorine degradation test / Water production volume before the chlorine degradation test

[0106] [Example 1] Polyester nonwoven fabric (air permeability 2.0 cc / cm²) ２A support film was prepared by casting an 18.0 mass% DMF solution of PSf to a thickness of 200 μm onto the surface and immediately immersing it in pure water for 5 minutes. This support film was immersed in a 3.0 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 40°C, an n-decane solution containing 0.16 mass% TMC at 40°C was applied so that the surface was completely wetted. Next, the support film was heated in an oven at 120°C, and then the film was drained vertically to remove excess solution from the film. The resulting film was washed with 85°C hot water for 2 minutes to obtain composite semipermeable film 1. A 100 ppm aqueous solution of o-phthalaldehyde, adjusted to pH 1.0 using dilute sulfuric acid, was evenly applied to the surface of the separation functional layer of the obtained composite semipermeable membrane 1. The surface of the separation functional layer was then covered with a heat-resistant film made of polyvinylidene chloride, and the membrane was heated in an oven at a surface temperature of 85°C for 1 minute. After that, the membrane was washed with pure water to obtain a composite semipermeable membrane.

[0107] [Example 2] A composite semipermeable film was obtained by the same method as in Example 1, except that o-phthalaldehyde was replaced with 4,5-dimethoxyphthalaldehyde.

[0108] [Example 3] A composite semipermeable membrane was obtained by the same method as in Example 1, except that o-phthalaldehyde was replaced with 4-chlorophthalaldehyde.

[0109] [Example 4] A composite semipermeable membrane was obtained in the same manner as in Example 1, except that instead of surface coating, the composite semipermeable membrane 1 was immersed in a treatment solution at 85°C for 1 minute. Because the composite semipermeable membrane was immersed in the treatment solution, the reaction proceeded even inside the separation functional layer, resulting in a smaller ratio E compared to Example 1, and a smaller initial water production volume during manufacturing.

[0110] [Example 5] A composite semipermeable membrane was obtained in the same manner as in Example 4, except that the concentration of the treatment solution was 200 ppm and the immersion time was 30 seconds.

[0111] [Example 6] A composite semipermeable membrane was obtained in the same manner as in Example 4, except that the concentration of the processing solution was 500 ppm and the immersion time was 12 seconds. Compared to Example 4, shortening the immersion time suppressed the reaction inside the separation functional layer, resulting in a larger ratio E and a larger initial water production capacity during manufacturing.

[0112] [Example 7] A composite semipermeable membrane was obtained in the same manner as in Example 6, except that the immersion time was 5 minutes.

[0113] [Example 8] A composite semipermeable membrane was obtained in the same manner as in Example 4, except that the concentration of the treatment solution was 80 ppm.

[0114] [Example 9] A composite semipermeable membrane was obtained in the same manner as in Example 4, except that the concentration of the treatment solution was 50 ppm.

[0115] [Example 10] A composite semipermeable membrane was obtained in the same manner as in Example 4, except that the concentration of the treatment solution was 20 ppm.

[0116] [Example 11] A composite semipermeable membrane was obtained in the same manner as in Example 4, except that the pH of the treatment solution was set to 7.0.

[0117] [Example 12] A composite semipermeable membrane was obtained in the same manner as in Example 4, except that the concentration of the treatment solution was 500 ppm and the temperature was 45°C.

[0118] [Comparative Example 1] The composite semipermeable membrane 1 obtained in Example 1 was used as is.

[0119] [Comparative Example 2] A composite semipermeable membrane was obtained by the same method as in Example 4, except that o-phthalaldehyde was replaced with glutaraldehyde. The structure represented by general formula (II) could not be obtained, and the effect of improving the salt removal rate was smaller compared to Example 4.

[0120] [Comparative Example 3] A composite semipermeable membrane was obtained by the same method as in Example 4, except that o-phthalaldehyde was replaced with succinaldehyde. The structure represented by general formula (II) could not be obtained, and the effect of improving the salt removal rate was smaller compared to Example 4.

[0121] [Comparative Example 4] A composite semipermeable membrane was obtained by the same method as in Example 4, except that o-phthalaldehyde was replaced with cyclopentane-1,3-dicarboxylaldehyde. The structure represented by general formula (II) could not be obtained, and the effect of improving the salt removal rate was smaller compared to Example 4.

[0122] [Comparative Example 5] A composite semipermeable membrane was obtained in the same manner as in Example 1, except that the concentration of the treatment solution was 50,000 ppm. Due to the high concentration of the treatment solution, the ratio B / A was large, and the amount of water produced during manufacturing was small.

[0123] [Comparative Example 6] A composite semipermeable membrane was obtained using the same method as in Example 1, except that the concentration of the treatment solution was 10,000 ppm and the immersion time was 60 minutes. Due to the high concentration of the treatment solution, the ratio B / A was large, and the amount of water produced during manufacturing was small.

[0124] [Comparative Example 7] A composite semipermeable membrane was obtained in the same manner as in Example 11, except that the concentration of the treatment solution was 10,000 ppm, the temperature was 25°C, and the immersion time was 60 minutes. Although the temperature was low, the concentration of the treatment solution was high and the immersion time was long, resulting in a large B / A ratio and a small amount of water produced during manufacturing.

[0125] [Comparative Example 8] A composite semipermeable membrane was obtained in the same manner as in Example 4, except that the concentration of the treatment solution was 10,000 ppm and the immersion time was 60 minutes. Due to the high concentration of the treatment solution and the long immersion time, the ratio B / A was large, and the amount of water produced during manufacturing was small.

[0126] Table 1 shows the performance of the composite semipermeable membranes obtained in Examples 1 to 12 and Comparative Examples 1 to 8.

[0127]

[0128] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2025-055403 filed on 28 March 2025, the contents of which are incorporated herein by reference.

Claims

1. A composite semipermeable membrane comprising: a porous support layer; and a separation functional layer provided on the porous support layer, wherein the separation functional layer contains a crosslinked aromatic polyamide including a structure represented by the following general formula (I), and in a surface analysis of the surface layer side of the separation functional layer by TOF-SIMS, a ratio B / A of a peak intensity B of a fragment having the maximum peak intensity among peaks of fragments derived from a structure including R in the general formula (I) to a peak intensity A at m / z = 75.02 is ４ 1.5×10 －２ or more and 50.0×10 －２ or less. [In general formula (I), Ar １ to Ar ３ each independently represent an optionally substituted aromatic ring having 5 to 14 carbon atoms, and at least one of Ar １ to Ar ３ is a substituted benzene ring. R １ to R ３ each independently represent a hydrogen atom or an optionally substituted aliphatic chain having 1 to 10 carbon atoms. R ４ is a structure represented by the following general formula (II). n is an integer of 1 or greater.] [In general formula (II), X １ to X ４ each independently represent a hydrogen atom, an optionally substituted hydrocarbon group having 1 to 4 carbon atoms, an optionally substituted ester group having 1 to 4 carbon atoms, an optionally substituted alkoxy group having 1 to 4 carbon atoms, or a halogen, and the total number of carbon atoms in X １ to X ４ is 16 or less. Further, X １ to X ４ may be bonded directly or indirectly to each other to form a cyclic structure. The wavy line indicates a bonding site to Ar １ in the general formula (I).] 2. The composite semipermeable membrane according to claim 1, wherein the surface zeta potential of the separation functional layer at pH 3.0 is -10.0 mV or more and 10.0 mV or less.

3. The peak intensity C at m / z = 75.02 in the surface analysis of the separation functional layer on the porous support layer side by TOF-SIMS, and R in the general formula (I). ４ A composite semipermeable membrane according to claim 1 or 2, wherein the ratio E of the ratio B / A to the ratio D / C of the peak intensity D of the fragment with the highest peak intensity among the peaks of the fragments derived from the structure containing is 1.5 or more.

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

5. A method for producing a composite semipermeable membrane according to claim 1 or 2, comprising the following steps (a) and (b). Step (a): A step of forming the separation functional layer containing the crosslinked aromatic polyamide on the porous support layer. Step (b): A step of bringing the separation functional layer into contact with a processing solution containing a compound represented by the following general formula (III) at a temperature of 45°C or higher. [In general formula (III), Z １ Z ２ Each of these is independently a formyl group, an acetal group, a hemiacetal group, a hemiaminal group, or an aminal group. １ ~X ４ Each is independently a hydrogen atom, an optionally substituted hydrocarbon group having 1 to 4 carbon atoms, an optionally substituted ester group having 1 to 4 carbon atoms, an optionally substituted alkoxy group having 1 to 4 carbon atoms, or a halogen, X １ ~X ４ The total number of carbon atoms is 16 or less. Also, X １ ~X ４ They may be directly or indirectly connected to form a ring structure.

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