Composite semipermeable membrane, composite semipermeable membrane element, and fluid separation device

Abstract

To provide a composite semipermeable film with good oxidation resistance, acid resistance, and alkali resistance. [Solution] The system comprises 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 1642~1662 cm² -1 A peak originating from amide I exists, and the wavenumber width w is 80% of the peak intensity relative to the maximum intensity of the peak originating from amide I. 80% 35.8cm -1 More than 38.0cm -1 The following is a composite semipermeable membrane.

Description

[Technical Field]

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

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

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

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

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

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

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

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

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

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

[13] . [1] 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 showed 1642 to 1662 cm² -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% 35.8cm -138.0 cm or more -1 The following composite semipermeable membrane. [2] In the surface analysis of the coating layer side by total reflection infrared absorption measurement, 1630 to 1710 cm -1 The area ratio B / A of the peak area B at 2800 to 3000 cm -1 to the peak area A is 0.60 or more and 0.85 or less, the composite semipermeable membrane according to [1] above. [3] The porous support layer contains polysulfone, and in the surface analysis of the coating layer side by total reflection infrared absorption measurement, 1200 to 1270 cm -1 The area ratio A / C of the peak area A derived from amide I at 1630 to 1710 cm -1 to the peak area C derived from polysulfone at is 0.30 or more and 0.50 or less, the composite semipermeable membrane according to [1] or [2] above. [4] In the surface analysis of the coating layer side by total reflection infrared absorption measurement, 1200 to 1270 cm -1 The area ratio D / C of the peak area D at 1520 to 1560 cm -1 to the peak area C derived from polysulfone at is 0.23 or more and 0.40 or less, the composite semipermeable membrane according to [3] above. [5] The 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% The w change width, which is the difference between them 80% is 2.0 cm -1 or less, the composite semipermeable membrane according to any one of [1] to [4] above. [6] The 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% The w change width, which is the difference between them 80% is 2.0 cm -1 or less, the composite semipermeable membrane according to [4] above. [7] The w of the composite semipermeable membrane after immersion treatment in chlorine, alkali and acid 80% is 36.0 cm -1 or more and 40.0 cm -1 or less, the composite semipermeable membrane according to any one of [1] to [6] above. [8] A composite semipermeable membrane according to any one of [1] to [7] above, wherein the coating layer contains a polymer having a structure represented by the following general formula (I).

[0011] [ka]

[0012] [In general formula (I), R1 is a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted, and R2 is hydrogen, a hydrocarbon group having 2 or fewer carbon atoms, or a functional group having 2 or fewer carbon atoms.] [9] A composite semipermeable membrane according to any one of [1] to [8] above, wherein the coating layer comprises a polymer having a structure represented by the following general formula (II).

[0013] [ka]

[0014] [In general formula (II), R3 and R4 in each repeating unit are independently hydrogen or a hydrocarbon group having 2 or fewer carbon atoms, and n is an integer of 1 or more.]

[10] The composite semipermeable membrane according to [9] above, wherein the coating layer comprises a polymer having a structure represented by the following general formula (III).

[0015] [ka]

[0016] [In general formula (III), X is a structure containing the above general formula (II), R5 is a hydrocarbon group having 4 to 11 carbon atoms which may be substituted, and R6 and R7 are each independently hydrogen or a hydrocarbon group having 2 or fewer carbon atoms or a functional group having 2 or fewer carbon atoms].

[11] The composite semipermeable membrane according to

[10] above, wherein the coating layer contains a polymer having a structure represented by the following general formula (IV).

[0017] [ka]

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

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

[11] above.

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

[11] above. [Effects of the Invention]

[0019] According to the present invention, it is possible to provide a composite semipermeable film with good oxidation resistance, acid resistance, and alkali resistance. [Brief explanation of the drawing]

[0020] [Figure 1] Figure 1 is a schematic diagram showing the w80% peak obtained by surface analysis of the coating layer side using total internal reflection infrared absorption measurement. [Modes for carrying out the invention]

[0021] Embodiments of the present invention will be described in detail below, but the present invention is not limited thereto.

[0022] 1.Composite semipermeable membrane The composite semipermeable membrane of the present invention comprises a porous support layer, a separation functional layer 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.

[0023] 1.1 Covering 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 disposed on the separation functional layer. The coating layer of the present invention 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 the present invention is a polymer formed from two or more types of monomer units. The polymer forming the coating layer may be a random copolymer, an alternating copolymer, or a block copolymer. Furthermore, the coating layer may contain other components as long as they do not hinder the effects of the present invention.

[0024] In surface analysis of the coating layer side of the composite semipermeable film according to this embodiment, the absorption rate was 1642-1662 cm² in total internal reflection infrared absorption spectroscopy (hereinafter referred to as "ATR-IR"). -1 A peak originating from amide I (hereinafter also referred to as the "amide I peak") is present.

[0025] The "peak originating from amide I" refers to the peak originating from the C=O stretching of the amide bond, and is typically found in the ATR-IR spectrum under an atmosphere adjusted to 20°C and 50% RH, at 1630–1670 cm⁻¹. -1 This is a peak detected between 1664 cm² and 1664 cm². -1 A peak is detected in the vicinity. The peak position of amide I shifts to the lower wavenumber side due to hydrogen bonding between the polymer contained in the coating layer and the amide group in the separation functional layer.

[0026] 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 using ATR-IR, the position of the peak originating from amide I was found to be 1642 cm². -1 The above is 1662cm. -1 We found that by doing the following, a composite semipermeable film with good oxidation resistance, acid resistance, and alkali resistance can be obtained.

[0027] The peak position of Amido I is 1662 cm. -1Under the following conditions, the amide bonds between the polymer in the coating layer and the cross-linked aromatic 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 polymer contained in the coating layer and the amide bonds of the cross-linked aromatic polyamide contained in the separation functional layer is suppressed, resulting in good water permeability. From the above viewpoint, the peak position of amide I is 1645 cm⁻¹. -1 The above is 1662cm. -1 The following is preferable: 1648cm -1 The above is 1662cm. -1 The following is more preferable. Here, the peak position of amide I is the wavenumber that shows the maximum intensity of the peak originating from amide I.

[0028] Furthermore, as shown in Figure 1, 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% 35.8cm -1 More than 38.0cm -1 The following is the case. 80% 35.8cm -1 More than 37.0cm -1 The following is preferable: 35.8 cm -1 Above, 36.5cm -1 The following are preferable.

[0029] w 80% This is an index that represents the degree of interaction between the carbonyl group of the amide group of the crosslinked aromatic 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 polymer contained in the coating layer and the carbonyl group of the amide group of the crosslinked aromatic polyamide is weak, the peak originating from the polymer contained in the coating layer overlaps, causing the peak originating from amide I to become broader, and w 80% It will get even bigger.

[0030] w 80% 35.8cm -1As described above, an interaction occurs between the polymer contained in the coating layer and the amide group of the crosslinked aromatic polyamide, resulting in excellent chemical resistance. 80% 38.0cm -1 Under the following conditions, the interaction between the polymer contained in the coating layer and the amide groups of the crosslinked aromatic polyamide is strong, allowing the coating layer to fully function as a protective layer and exhibit excellent chemical resistance.

[0031] 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 functional groups having carbonyl groups, nitro groups, phosphoryl groups, sulfo groups, sulfoxy groups, etc.

[0032] 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.

[0033] Normally, when a composite semipermeable membrane containing a cross-linked aromatic polyamide is subjected to immersion treatment, the amide bonds of the cross-linked aromatic polyamide are cleaved, and the peak of amide I becomes broad, so the w after immersion treatment 80% w becomes larger than before processing. 80%The range of change represents the chemical resistance of the amide group. When the amide group of a crosslinked aromatic polyamide interacts with other functional groups, the cleavage of the amide bond is suppressed, w 80% The range of change will be smaller.

[0034] w 80% The change is 2.0 cm. -1 The following conditions are met, as the polymer contained in the coating layer interacts sufficiently with the amide groups of the cross-linked aromatic polyamide, resulting in excellent chemical resistance. 80% The lower limit of the range of change is effectively 0 cm. -1 That is the case.

[0035] The composite semipermeable membrane according to this embodiment is obtained after immersion treatment with chlorine, alkali and acid. 80% 36.0cm -1 More than 40.0cm -1 Preferably, it is 37.0 cm. -1 39.0cm or more -1 The following is more preferable: If the interaction between the polymer contained in the coating layer and the amide groups of the crosslinked aromatic polyamide is strong, the interaction between the polymer contained in the coating layer and the amide groups of the crosslinked aromatic polyamide will be maintained even after the immersion treatment. Therefore, after the immersion treatment 80% If the values ​​are within the above range, it is possible to achieve both excellent water permeability and chemical resistance.

[0036] w 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.

[0037] In surface analysis of the coating layer side of the composite semipermeable film according to this embodiment, a reading of 1630-1710 cm² was obtained.-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, even more preferably 0.65 or more and 0.80 or less, and particularly preferably 0.65 or more and 0.75 or less.

[0038] Typically, in composite semipermeable membranes with a separation functional layer containing crosslinked aromatic polyamide on a porous support layer, the hydrocarbon groups produce 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 polymers in the coating layer can interact more strongly with the cross-linked 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 water permeability due to the formation of the coating layer can be suppressed.

[0039] The above area ratio B / A can be controlled, for example, by using a polymer having a structure such as an alkylene moiety 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. If the polymer contained in the coating layer has an alkylene glycol moiety, it can be confirmed that the coating layer is formed on the crosslinked aromatic polyamide by using a Dragendorff reagent or the like.

[0040] The composite semipermeable membrane according to this embodiment has a porous support layer containing polysulfone (hereinafter referred to as "PSf"), and surface analysis of the coating layer side by ATR-IR showed a density of 1200 to 1270 cm². -1 The peak area C derived from PSf is 1630-1710 cm², derived from amide I. -1The 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.

[0041] When the above area ratio A / C is 0.30 or higher, a coating layer sufficient to interact with the amide groups of the crosslinked aromatic polyamide is formed, resulting in excellent chemical resistance. Furthermore, when the above area ratio A / C is 0.50 or lower, the decrease in water permeability due to the formation of the coating layer can be suppressed.

[0042] The above area ratio A / C can be controlled, for example, by forming a coating layer using a polymer having a structure such as an aldehyde group, ketone group, carboxylic acid group, ester group, amide group, enone group, urea group, or urethane group, which are functional groups from which a peak originating from amide I is detected, or by the thickness of the coating layer.

[0043] In addition, 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.

[0044] 1520~1560cm -1 The peak that appears is a peak originating from the CNH angle change of the amide bond (hereinafter referred to as "amide II"). When the above area ratio D / C is 0.23 or higher, the polymer contained in the coating layer and the amide group of the crosslinked aromatic 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 water permeability due to the formation of the coating layer can be suppressed. In this case, the polymer contained in the coating layer has sufficient primary and secondary amides, and the interaction with the amide bond of the crosslinked aromatic polyamide works sufficiently, improving chemical resistance.

[0045] The above area ratio D / C can be controlled by forming a coating layer using a polymer having a structure such as a primary or secondary amide, which is a functional group from which a peak derived from amide II is detected, and by the thickness of the coating layer, etc.

[0046] 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.

[0047] 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, "soluble 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.

[0048] 1.1.1 Polymers contained in the coating layer The coating layer of the composite semipermeable film according to this embodiment preferably contains a polymer having a structure represented by the following general formula (I).

[0049] [ka]

[0050] In general formula (I), R1 is a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted, and R2 is hydrogen, a hydrocarbon group having 2 or fewer carbon atoms, or a functional group having 2 or fewer carbon atoms.

[0051] 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 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 formula can be controlled. When the polymer has a structure represented by the above general formula (I), as described above, not only does a hydrophobic interaction by hydrocarbon groups act between the coating layer and the crosslinked aromatic polyamide, but hydrogen bonds are also formed between the carbonyl of the amide group and the crosslinked aromatic polyamide, so a composite semipermeable membrane with excellent chemical resistance can be obtained. If the number of carbon atoms of R1 in the above general formula (I) is 4 or more, sufficient hydrophobic interaction acts, and if the number of carbon atoms is 11 or less, the decrease in membrane permeation flux due to hydrophobicity can be suppressed. The number of carbon atoms of R1 in the general formula (I) is more preferably 4 to 10, even more preferably 4 to 8, and particularly preferably 4 to 6. R2 in the general formula (I) is preferably hydrogen, a hydrocarbon group such as a methyl group or ethyl group, or a functional group such as a methoxymethyl group, and more preferably hydrogen. If R2 is any of the above, it is possible to suppress the inhibition of the interaction between the polymer contained in the coating layer and the crosslinked aromatic polyamide due to steric hindrance.

[0052] The coating layer of the composite semipermeable film according to this embodiment preferably contains a polymer having a structure represented by the following general formula (II).

[0053] [ka]

[0054] In general formula (II), R3 and R4 in each repeating unit are independently hydrogen or a hydrocarbon group having 2 or fewer carbon atoms, and n is an integer of 1 or more.

[0055] 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, 1630~1710 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.

[0056] A 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 can form hydrogen bonds with the polyamide. From the viewpoint of the polymer's solubility in water-soluble solvents and the formation of hydrogen bonds between the polymer and the polyamide, as well as the function of hydrophobic interactions, R3 and R4 are preferably hydrogen or methyl groups. Furthermore, n is preferably an integer between 5 and 500, more preferably between 5 and 300, and even more preferably between 10 and 250. When n is an integer of 5 or more, in addition to hydrophobic interactions, more hydrogen bonds are formed between the ether groups of the polymer and the crosslinked aromatic polyamide, thus improving chemical resistance.

[0057] Furthermore, the composite semipermeable membrane according to this embodiment preferably contains a polymer having a structure represented by the following general formula (III).

[0058] [ka]

[0059] In general formula (III), X is a structure containing general formula (II), R5 is a hydrocarbon group having 4 to 11 carbon atoms which may be substituted, and R6 and R7 are each independently hydrogen or a hydrocarbon group having 2 or fewer carbon atoms or a functional group having 2 or fewer carbon atoms.

[0060] When the polymer has the structure represented by the above general formula (III), since it has a primary amide and a secondary amide, the ratio A / C of the peak area A derived from amide I at 1630 - 1710 cm -1 to the peak area C derived from PSf at 1200 - 1270 cm -1 and the ratio D / C of the peak area D at 1520 - 1560 cm -1 to the peak area C derived from PSf at 1200 - 1270 cm -1 can be controlled. Since the polymer has a primary amide, a secondary amide, and an alkylene moiety, a strong hydrogen bond and a strong hydrophobic interaction are formed between the polymer contained in the coating layer and the crosslinked aromatic polyamide, and a composite semipermeable membrane having excellent chemical resistance can be obtained.

[0061] The number of carbon atoms of the hydrocarbon group of R5 is preferably 4 or more and 10 or less, more preferably 4 or more and 8 or less, and even more preferably 4 or more and 6 or less. When R5 is a hydrocarbon group having 4 or more and 10 or less carbon atoms, a hydrophobic interaction occurs between the polymer and the polyamide. Preferred structures of R5 include, for example, a butylene group (-C4H8-), a pentylene group (-C5H 10 -), a hexylene group (-C6H 12 -), a heptylene group (-C7H 14 -), an octylene group (-C8H 16 -), a nonylene group (-C9H 18 -), a decylene group (-C 10 H 20 -), etc. hydrocarbon groups, hydrocarbon groups having an unsaturated structure such as a butenylene group (-C4H6-), a pentenylene group (-C5H8-), a hexenylene group (-C6H 10 -), etc., hydrocarbon groups having a cyclic structure such as a cyclobutylene group (-C4H6-), a cyclopentylene group (-C5H8-), a cyclohexylene group (-C6H 10 -), etc., and hydrocarbon groups of an aromatic ring such as a phenylene group (-C6H4-), etc. These carbon chains may be substituted with any functional group such as a hydroxyl group. Among them, R5 is preferably a butylene group (-C4H8-), a pentylene group (-C5H 10 -), a hexylene group (-C6H 12-), a phenylene group (-C6H4-) is more preferred.

[0062] R6 and R7 are each independently hydrogen, a hydrocarbon group having 2 or fewer carbon atoms, or a functional group having 2 or fewer carbon atoms. Because they interact well with the amide group of the crosslinked polyamide of the functional layer, hydrogen or a hydrocarbon group having 1 carbon atom, which has less steric hindrance, is more preferred, and hydrogen is even more preferred.

[0063] In other words, when the polymer has a structure represented by the above general formula (III), hydrogen bonding between the alkylene moiety and the polyamide, and hydrophobic interactions between the hydrocarbon group and the polyamide, work simultaneously to obtain a composite semipermeable film with excellent chemical resistance.

[0064] In this embodiment, it is even more preferable that the coating layer of the composite semipermeable film contains a polymer having a structure represented by the following general formula (IV).

[0065] [ka]

[0066] In general formula (IV), R1 and R5 are each independently substituted hydrocarbon groups having 4 to 11 carbon atoms, R2, R6, and R7 are each independently hydrogen or hydrocarbon groups having 2 or fewer carbon atoms or functional groups having 2 or fewer carbon atoms, X is a structure containing the above general formula (II), and r and q are each independently integers of 1 or more. The preferred forms of R1 and R2 are as described above with respect to the general formula (I). The preferred forms of R5, R6, and R7 are as described above with respect to the general formula (III).

[0067] When the polymer contained in the coating layer has the structure represented by general formula (IV), it possesses all the structures represented by general formulas (I) to (III). 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.

[0068] 1.2 Porous support layer The composite semipermeable membrane of the present invention 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.

[0069] 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.

[0070] The porous support layer has numerous interconnected pores. The pore diameter and pore diameter distribution are not particularly limited, but a porous support layer is preferred in which, for example, it has a symmetrical structure with uniform pore diameters, or an asymmetrical structure in which the pore diameter gradually increases from one surface to the other, and the pore diameter on the surface with smaller pore diameters is 0.1 to 100 nm.

[0071] As the material for the porous support layer, homopolymers (hompolymers) or copolymers of 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, and 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.

[0072] 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.

[0073] 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 separation 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. 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.

[0074] 1.3 Separation functional layer The separation functional layer of the composite semipermeable membrane of the present invention is a layer responsible for solute separation 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.

[0075] A "crosslinked aromatic polyamide" is a polycondensate of a polyfunctional amine and a polyfunctional aromatic acid halide, meaning that the polyamide forms a crosslinked structure. Specifically, examples include polymers of polyfunctional aliphatic amines and polyfunctional aromatic acid halides, and polymers of polyfunctional aromatic amines and polyfunctional aromatic acid halides. Crosslinked aromatic polyamides may contain non-aromatic moieties in their molecular structure. The crosslinked structure may be formed by the polyamide via a crosslinking agent, for example, 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 crosslinked 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 crosslinked structure. This results in a rigid molecular chain and a crosslinked aromatic polyamide having a good pore structure for removing fine solutes such as hydrated ions and silica. Crosslinked aromatic polyamides are preferably crosslinked total aromatic polyamides, which are polymers of polyfunctional aromatic amines and polyfunctional aromatic acid halides, in terms of rigidity, chemical stability, and chemical resistance to operating pressure.

[0076] A "polyfunctional amine" refers to an amine having at least two primary amino groups and / or secondary amino groups in one molecule. Specific examples of polyfunctional amines include aromatic trifunctional amines such as 1,3,5-triaminobenzene and 1,2,4-triaminobenzene, as well as 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. These polyfunctional amines may be used individually or in combination of two or more.

[0077] Considering the separation performance, water permeability, 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 handling.

[0078] A "polyfunctional aromatic acid halide" refers to an aromatic acid halide having at least two halogenated carbonyl groups in one molecule. Examples of polyfunctional aromatic acid halides include trifunctional aromatic acid chlorides such as trimesic acid chloride (hereinafter referred to as "TMC") and trimellitic acid chloride, and difunctional aromatic acid chlorides such as biphenyldicarboxylic acid chloride, azobenzenedicarboxylic acid dichloride, terephthalic acid chloride, isophthalic acid chloride, and 2,6-naphthalenedicarboxylic acid dichloride. These polyfunctional aromatic acid halides may be used individually or in combination of two or more.

[0079] From the viewpoint of the separation performance and heat resistance of the composite semipermeable membrane, TMC is particularly preferred among the polyfunctional aromatic acid halides, given its availability and ease of handling.

[0080] 2. Method for manufacturing composite semipermeable membranes The method for manufacturing a composite semipermeable membrane according to one embodiment 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.

[0081] 2.1 Film Formation Process for Support Film For the method of forming the support film, known methods can be suitably used. The following description will take the case where PSf is used as the material for the porous support layer as an example.

[0082] First, PSf is dissolved in a suitable solvent to prepare a porous support layer stock solution. DMF is a preferred solvent for PSf.

[0083] 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, it is possible to achieve both strength and water permeability in the resulting porous support layer. The preferred range of material concentration in the porous support layer stock solution can be appropriately adjusted depending on the material used, a suitable solvent, etc.

[0084] 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.

[0085] The coagulation solution may consist solely of non-solvent PSf, or it may contain a good solvent for PSf to the extent that it can coagulate the porous support layer stock solution.

[0086] The resulting support film may be washed before the formation of the separation functional layer to remove any remaining solvent in the film.

[0087] 2.2 Process for forming the separation functional layer Regarding the formation method of a separation functional layer containing polyamide, we will describe, as an example, a method in which a polyfunctional amine and a polyfunctional aromatic acid halide are polymerized and solidified on the support film obtained in "2.1 Support Film Formation Process". From the viewpoint of productivity and performance, interfacial polymerization is the most preferred polymerization method. The interfacial polymerization process will be described below.

[0088] 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 aromatic 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.

[0089] 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" can be used.

[0090] 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 with good water permeability 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.

[0091] 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.

[0092] 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.

[0093] In step (b), as the polyfunctional aromatic acid halide, for example, the polyfunctional aromatic acid halide described in "1.3 Separation Functional Layer" above can be used.

[0094] The organic solvent is preferably immiscible with water, dissolves polyfunctional aromatic acid halides, does not damage the support film, and is inert to polyfunctional 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.

[0095] The concentration of the polyfunctional aromatic 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 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. Furthermore, the organic solvent solution may contain compounds such as surfactants as needed, as long as they do not inhibit polymerization.

[0096] It is preferable to uniformly and continuously bring the organic solvent solution of the polyfunctional aromatic acid halide into contact with a support film that has been brought into contact with an aqueous solution of a polyfunctional amine. Specifically, for example, one method is to coat the support film that has been brought into contact with an aqueous solution of a polyfunctional aromatic acid halide with the organic solvent solution of the polyfunctional aromatic acid halide. The contact time between the support film that has been brought into contact with the aqueous solution of a polyfunctional amine and the organic solvent solution of the polyfunctional aromatic acid halide is preferably 3 seconds to 10 minutes, and more preferably 5 seconds to 3 minutes.

[0097] Furthermore, if necessary, the support film in contact with an organic solvent solution of the polyfunctional aromatic 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.

[0098] In step (c), the organic solvent solution on the composite semipermeable membrane after the polymerization reaction is removed by dewatering. Methods for dewatering include, for example, holding the membrane vertically and allowing the excess organic solvent solution to flow down naturally; blowing air with a fan to dry and remove the organic solvent; or removing the excess organic solvent solution with a mixed fluid of water and air.

[0099] 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 aromatic acid halide used.

[0100] 2.3 Process for forming the coating layer The composite semipermeable membrane processed in this process may be an unused membrane or a membrane that has deteriorated due to use or other factors. Furthermore, this process can be considered one of the manufacturing processes for composite semipermeable membranes.

[0101] The coating layer formation step comprises (e) bringing a solution containing a polymer that forms the coating layer into contact with the separation functional layer, (f) draining off excess solution, and (g) washing the composite semipermeable membrane.

[0102] In step (e), the solution containing the polymer forming the coating layer may optionally contain compounds such as a crosslinking agent. The crosslinking agent may crosslink the polymers forming the coating layer with each other, or it may crosslink the polymers forming the coating layer with the polyamide in the separation functional layer. When the polymers forming the coating layer are fixed to the crosslinked aromatic 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.

[0103] The solution contains water and at least one solvent selected from the water-soluble solvents described in "1.1 Coating Layer" above. In other words, the solution may contain two or more solvents.

[0104] It is preferable that the solution containing the polymer forming the coating layer be brought into uniform and continuous contact with the separation functional layer. Specifically, for example, a method of coating the separation functional layer with the solution can be used. The contact time between the separation functional layer and the solution is preferably 5 seconds to 10 hours, and more preferably 10 seconds to 1 hour. The thickness of the coating layer can be adjusted by the contact time.

[0105] 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.

[0106] 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 crosslinking agents 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.

[0107] 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.

[0108] 3. Use of composite semipermeable membranes The composite semipermeable membrane according to this embodiment is preferably used as a spiral-type composite semipermeable membrane element, wound around a cylindrical water collection pipe with numerous holes, together with a water supply channel material such as a plastic net, a permeable water channel material such as tricot, and a film to enhance pressure resistance as needed. Furthermore, a composite semipermeable membrane module can be formed by connecting these elements in series or parallel and housing them in a pressure vessel.

[0109] 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.

[0110] From the viewpoint of reducing environmental impact and effectively utilizing water resources, it is preferable that the fluid separation device is applicable to zero-liquid discharge systems (hereinafter referred to as "ZLD") and resource recovery applications. In ZLD, wastewater is concentrated using membrane separation technology, and then subjected to evaporation and drying treatment. Because the wastewater is concentrated to the extreme, foulants in the feedwater are concentrated, making fouling likely to occur. Furthermore, since fouling is eliminated by frequent chemical cleaning, it is preferable to use a composite semipermeable membrane with excellent chemical resistance. In ZLD, it is preferable to equip the preceding stage with a UF membrane device, as this allows for efficient removal of foulants. Industries in which ZLD is introduced include, for example, semiconductor and electronic component manufacturing, chemical industry, thermal power plants, and dyeing and textile factories. Since the wastewater from these industries may have a temperature of 35°C or higher, it is preferable that the fluid separation device used in ZLD can be used under conditions where the feedwater temperature is 35°C or higher. When the feedwater is at a high temperature of 35°C or higher, the deterioration of the composite semipermeable membrane equipped in the fluid separation device is accelerated, which is a problem. In resource recovery applications, useful components are concentrated from factory wastewater and other sources using membrane separation technology, and then recovered by sedimentation or adsorption. In this process, the treated water may contain acidic or alkaline substances and oxidizing agents, making composite semipermeable membranes prone to degradation. Therefore, it is preferable to use composite semipermeable membranes with excellent chemical resistance.

[0111] The composite semipermeable membrane according to this embodiment has excellent oxidation resistance, acid resistance, and alkali resistance, and can suppress degradation by chemicals, which is a concern in ZLD and resource recovery applications. Therefore, it can be preferably used in fluid separation devices for ZLD and resource recovery.

[0112] Furthermore, from the viewpoint of improving yield and reliability in the manufacturing process, fluid separation devices are preferably applicable to precision industries that use high-purity water and chemicals, such as semiconductor manufacturing. Examples of precision industries include the pharmaceutical and biopharmaceutical manufacturing field, where high purity of raw materials and solvents is required; the electronic and optical materials manufacturing field, where impurity control is required to maintain optical and electrical properties; the nuclear-related field, where the purity of chemicals and water affects the behavior of radioactive materials; and high-precision analytical fields, such as mass spectrometry and chromatography, where the purity of reagents and solvents directly impacts analytical accuracy. For example, hydrogen peroxide, one of the chemicals used for cleaning in the semiconductor manufacturing process, is generally synthesized and then purified using a method that utilizes the oxidation-reduction reaction of anthraquinones in an organic solvent. Impurities remaining in these manufacturing processes cause a decrease in semiconductor manufacturing yield, so it is preferable that they be removed in the purification process.

[0113] The composite semipermeable membrane according to this embodiment has excellent oxidation resistance, acid resistance, and alkali resistance, making it less susceptible to degradation caused by chemicals present in the liquid supplied to the composite semipermeable membrane. Therefore, it can effectively separate water, hydrogen peroxide, and other chemicals from impurities, and the quality of the permeate remains stable during operation. As a result, it can be preferably used in fluid separation devices for the purification of water and chemicals used in precision industries.

[0114] 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).

[0115] A higher operating pressure for the fluid separation device improves the solute removal rate. However, considering the increased energy required for operation and 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. While 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.

[0116] When a composite semipermeable membrane 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 to 1.8 m / d, more preferably 0.7 m / d to 1.8 m / d, and even more preferably 0.8 m / d to 1.8 m / d.

[0117] In this specification, the chemical resistance of a 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" section of the examples 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 more 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 more preferably 1.5 or less. Also, in the "immersion treatment in hydrogen peroxide solution" of the examples, the smaller the difference in membrane performance before and after the immersion treatment, the higher the chemical resistance. Specifically, the SP ratio, which is the ratio of the NaCl permeability before and after the 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. Also, the membrane permeation flux ratio, which is the value obtained by dividing the membrane permeation flux after the immersion treatment by the membrane permeation flux before the immersion treatment, is preferably 1.7 or less, more preferably 1.6 or less, and even more preferably 1.5 or less.

Examples

[0118] The present invention will be described below with specific examples, but the present invention is not limited to these examples in any way.

[0119] <NaCl removal rate> Evaluation water adjusted to a temperature of 25°C, pH 7.0, and NaCl concentration of 34,000 ppm was supplied as feed water to the composite semipermeable membrane, and the operating pressure was adjusted so that the membrane permeation flux was 1.0 m 3 / m 2 / d, and the membrane filtration treatment was performed for 1 hour. Then, the electrical conductivity of the feed water and the permeate water was measured with a multi-water quality meter MM60R (manufactured by Toa DKK Corporation) to obtain the practical salinity of each, that is, the NaCl concentration. The NaCl removal rate was calculated from the obtained NaCl concentration by the following formula (1). Here, the NaCl concentration (ppm) means the concentration on a mass basis. NaCl removal rate (%) = 100 × {1 - (NaCl concentration in permeate water / NaCl concentration in feed water)} ··· Formula (1)

[0120] <Membrane permeation flux> Evaluation water adjusted to a temperature of 25°C and pH 7.0 and NaCl concentration of 34,000 ppm was supplied to the composite semipermeable membrane after adjusting the pressure to 5.50 MPa, and the membrane filtration treatment was performed for 1 hour. Then, the amount of permeate water (m 3 ) was measured for 20 minutes, and it was converted to a value per unit membrane area (m 2 ) and per unit time (d) to calculate the membrane permeation flux (m / d).

[0121] <Immersion treatment> The composite semipermeable membranes of Examples 1 to 7 and Comparative Examples 1 to 4, described later, were subjected to the following immersion treatment tests, and the membrane performance before and after the immersion treatment tests was evaluated. The composite semipermeable membrane was immersed in a sodium hypochlorite aqueous solution prepared at 25°C, 100 ppm, and pH 7.0 for 20 hours and washed with distilled water. Next, it was immersed in a sodium hydroxide aqueous solution prepared at 25°C and pH 13.0 for 20 hours, then immersed in sulfuric acid prepared at 25°C and pH 1.0 for 20 hours and washed with distilled water. For the resulting composite semipermeable membrane 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 calculated using the following formulas (2) and (3). Membrane permeation flux ratio = Membrane permeation flux after immersion treatment / Membrane permeation flux before immersion treatment ... Equation (2) SP ratio = (100 - NaCl removal rate after immersion treatment) / (100 - NaCl removal rate before immersion treatment) ... Equation (3) A membrane permeation flux ratio of 1.7 or less before and after immersion treatment is considered good. Furthermore, an SP ratio of 5.0 or less before and after immersion treatment is also considered good.

[0122] <Immersion treatment in hydrogen peroxide solution> The composite semipermeable membranes of Example 8 and Comparative Examples 5-6, described later, were subjected to the following immersion treatment in hydrogen peroxide solution, and the membrane performance before and after the treatment was evaluated. The composite semipermeable membrane was immersed in hydrogen peroxide solution at 25°C (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., Wako Grade 1, product code 080-01186) for 72 hours (hydrogen peroxide immersion treatment) and washed with distilled water. After this hydrogen peroxide immersion treatment, the SP ratio and membrane permeation flux ratio were calculated using the same method as described in the "Immersion Treatment" section above. The evaluation of chemical resistance to hydrogen peroxide was determined by the SP ratio and membrane permeation flux ratio before and after the hydrogen peroxide immersion treatment, as described in the "Immersion Treatment" section above. A membrane permeation flux ratio of 1.7 or less before and after immersion in hydrogen peroxide solution is considered good. Furthermore, an SP ratio of 7.0 or less before and after immersion in hydrogen peroxide solution is also considered good.

[0123] <atr-ir> Under an atmosphere adjusted to 20°C and 50% RH, an ATR-IR spectrum was obtained by irradiating the surface of the separation functional layer of a composite semipermeable film with infrared light using a Shimadzu IRTracer-100 and a Shimadzu IRXross / IRAffinity-1 series single-reflection diamond ATR attachment (QATR10) as an accessory for total internal reflection measurement. The measurement conditions were set to a resolution of 1 cm. -1 The settings were adjusted, and the number of scans was set to 64. The composite semipermeable membrane was pre-air-dried before being used as the measurement sample. The obtained spectra were expressed as absorbance, and auto-baseline correction was performed. A Shimadzu LabSolutions IR was used for the analysis. The wavenumber and w of the peak top of amide I were determined. 80% The peaks were calculated by applying a Gaussian function approximation to the amide I peak in the spectrum obtained by ATR-IR. The area of ​​each peak was calculated by taking the spectrum at a wavenumber within a specified range and measuring 1.9 cm². -1 The area was divided into sections, approximated by trapezoidal shapes, and the area of ​​each section was summed up to calculate the result. Measurements were taken at two different points for each sample, and the average value was used.

[0124] <Synthesis of polymers> [Synthesis Example 1] 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 1.

[0125] [Synthesis Example 2] 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 2.

[0126] [Synthesis Example 3] 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 container under a nitrogen atmosphere and reacted for 2 hours to obtain copolymer polyamide 3.

[0127] [Synthesis Example 4] 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 4.

[0128] [Synthesis Example 5] 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 5.

[0129] <Fabrication of composite semipermeable membranes> 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 used to fill a polyester long-fiber nonwoven fabric (thickness 90 μm, density 0.42 g / cm³). 3 The material was applied to the surface at 25°C, solidified for 3 seconds, then immersed in a solidification bath of 25°C distilled water for 30 seconds, and 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% by mass aqueous solution of m-PDA for 2 minutes, and the support film was slowly pulled up vertically. Excess aqueous solution was removed from the surface of the support film by blowing nitrogen from an air nozzle. In a controlled environment of 25°C, 20 ml of decane solution at 25°C containing 0.14% by mass of TMC was applied to the surface of the support film so that it was completely wetted, and it was left to stand for 1 minute. Next, the film was held vertically for 30 seconds to drain and remove the excess solution, and then washed with hot water at 90°C for 2 minutes to obtain composite semipermeable film 1.

[0130] [Reference example 1] Performance evaluation was performed using composite semipermeable membrane 1.

[0131] [Example 1] A composite semipermeable membrane 1 was brought into contact with an aqueous solution containing 1% by mass of copolymerized polyamide 1. 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 excess aqueous solution, and washed with 20°C water for 5 minutes to prepare a composite semipermeable membrane with copolymerized polyamide 1 as a coating layer.

[0132] [Example 2] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that the concentration of copolymerized polyamide 1 was changed to 0.01% by mass.

[0133] [Example 3] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymerized polyamide 1 was replaced with copolymerized polyamide 2.

[0134] [Example 4] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymerized polyamide 1 was replaced with copolymerized polyamide 3.

[0135] [Example 5] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymerized polyamide 1 was replaced with copolymerized polyamide 4.

[0136] [Example 6] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymerized polyamide 1 was replaced with copolymerized polyamide 5.

[0137] [Example 7] A composite semipermeable membrane was prepared in the same manner as in Example 6, except that the concentration of copolymerized polyamide 5 was changed to 0.01% by mass.

[0138] [Comparative Example 1] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymer polyamide 1 was replaced with polyethylene glycol (weight-average molecular weight: 100,000).

[0139] [Comparative Example 2] A composite semipermeable membrane was prepared in the same manner as in Example 1, except that copolymerized polyamide 1 was replaced with polyethyl oxazoline (weight-average molecular weight: 100,000).

[0140] [Comparative Example 3] 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 1 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 prepare a composite semipermeable membrane.

[0141] [Comparative Example 4] Composite semipermeable membrane 1 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. Subsequently, it was immersed in a 10% by mass aqueous solution of isopropanol at 20°C for 20 minutes to hydrophilize it and prepare a composite semipermeable membrane.

[0142] [Example 8] The composite semipermeable membrane obtained in Example 1 was subjected to immersion treatment in hydrogen peroxide solution.

[0143] [Comparative Example 5] The composite semipermeable membrane obtained in Reference Example 1 was subjected to immersion treatment in hydrogen peroxide solution. [Comparative Example 6] The composite semipermeable membrane obtained in Comparative Example 1 was subjected to immersion treatment in hydrogen peroxide solution.

[0144] Table 1 shows the structure of the polymer obtained in the synthesis example, Table 2 shows the parameters obtained from ATR-IR of the obtained composite semipermeable membrane, and Table 3 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.

[0145] [Table 1]

[0146] [Table 2]

[0147] [Table 3]

[0148] [Table 4]

[0149] As shown in Tables 3 and 4, the composite semipermeable membrane according to this embodiment exhibits an effect of improving chemical resistance. [Industrial applicability]

[0150] The composite semipermeable membrane of the present invention can be used for seawater desalination, brine desalination, drinking water production, industrial ultrapure water production, wastewater treatment, and recovery of valuable materials. [Explanation of Symbols]

[0151] 1. Peak maximum intensity 2. 80% of the peak maximum intensity 3. The wavewidth where the peak intensity is 80% of the maximum peak intensity w 80%

Claims

1. A porous support layer, A separation functional layer containing a crosslinked aromatic polyamide is provided on the porous support layer, The separation functional layer comprises a covering layer provided on the separation functional layer, In the surface analysis of the coating layer by total internal reflection infrared absorption measurement, 1642–1662 cm －１ A peak originating from amide I is present, and The wavenumber width w is such that the peak intensity is 80% of the maximum peak intensity derived from the amide I. ８０％ 35.8 cm －１ 38.0cm or more －１ The following is a composite semipermeable membrane.

2. 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 1, wherein the area ratio B / A of the peak area B is 0.60 or more and 0.85 or less.

3. The porous support layer contains polysulfone, In the surface analysis of the coating layer 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 membrane according to claim 1 or 2, wherein the area ratio A / C of the peak area A is 0.30 or more and 0.50 or less.

4. In the surface analysis of the coating layer side by total reflection infrared absorption measurement, the area ratio D / C of the peak area D at 1520 to 1560 cm －１ to the peak area C derived from polysulfone at 1200 to 1270 cm －１ is 0.23 or more and 0.40 or less. The composite semipermeable membrane according to claim 3.

5. 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 1, which is as follows:

6. 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 4 is as follows:

7. 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 claim 6, which is as follows:

8. The composite semipermeable membrane according to claim 7, wherein the coating layer comprises a polymer having a structure represented by the following general formula (I). 【Chemistry 1】 [In general formula (I), R １ R is a hydrocarbon group having 4 to 11 carbon atoms, which may be substituted. ２ This is hydrogen, a hydrocarbon group having 2 or fewer carbon atoms, or a functional group having 2 or fewer carbon atoms.

9. The composite semipermeable membrane according to claim 8, wherein the coating layer comprises a polymer having a structure represented by the following general formula (II). 【Chemistry 2】 [In general formula (II), R in each repeating unit ３ and R ４ Each of these is independently a hydrogen atom or a hydrocarbon group having 2 or fewer carbon atoms, and n is an integer of 1 or more.

10. The composite semipermeable membrane according to claim 9, wherein the coating layer comprises a polymer having a structure represented by the following general formula (III). 【Transformation 3】 [In general formula (III), X is a structure that includes 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 hydrogen, a hydrocarbon group having 2 or fewer carbon atoms, or a functional group having 2 or fewer carbon atoms.

11. The composite semipermeable membrane according to claim 10, wherein the coating layer contains a polymer having a structure represented by the following general formula (IV). 【Chemistry 4】 [In general formula (IV), 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 these 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 general formula (II), and r and q are each independently an integer of 1 or more.

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

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

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