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

Abstract

The present invention provides a composite semipermeable membrane having excellent chemical resistance and little performance deterioration. This composite semipermeable membrane is provided with a support membrane and a separation function layer that is positioned on the support membrane and contains a crosslinked polyamide. The separation function layer contains an azo group, and the chromaticity b* is 0 to 20 (inclusive) when the composite semipermeable membrane is measured from the surface on the separation function layer side.

Description

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

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

[0002] Regarding the separation of mixtures, there are various techniques for removing substances (e.g., salts) dissolved in a solvent (e.g., water). In recent years, membrane separation has been increasingly used as an energy- and resource-saving process.

[0003] Membranes used in membrane separation include microfiltration membranes, ultrafiltration membranes, nanofiltration membranes, and reverse osmosis membranes. These membranes are used, for example, to obtain drinking water from seawater, brackish water, or water containing harmful substances, to produce ultrapure water for industrial use, to treat wastewater, and to recover valuable resources.

[0004] The invention described in Patent Document 1 aims to provide a semipermeable membrane that has high removal performance even for substances such as boric acid that do not dissociate in the neutral range, and that also exhibits high durability. Patent Document 1 discloses that azo groups are formed in a semipermeable membrane having a porous support membrane and an aromatic polyamide layer formed thereon by treating the aromatic polyamide layer with an aqueous nitrite solution. The yellowness index of the resulting separation functional layer, which is an aromatic polyamide layer having azo groups, is 10 or more and 40 or less.

[0005] International Publication No. 2011 / 078131

[0006] In various water treatment facilities such as water production plants, composite semipermeable membranes may come into contact with various chemicals such as acids, alkalis, and oxidizing agents. When a composite semipermeable membrane comes into contact with these chemicals, its performance is likely to deteriorate, so the composite semipermeable membrane is required to have a comprehensive durability against these chemicals.

[0007] Therefore, an object of the present invention is to provide a composite semipermeable membrane that is excellent in chemical resistance and suffers little deterioration in performance.

[0008] One aspect of the present invention is a composite semipermeable membrane comprising a support membrane and a separation functional layer containing a crosslinked polyamide located on the support membrane, wherein the separation functional layer contains an azo group, and the composite semipermeable membrane has a chromaticity b ＊ is 0 or more and 20 or less.

[0009] Another aspect of the present invention is a method for producing a composite semipermeable membrane comprising a support membrane and a separation functional layer provided on the support membrane, wherein the step of forming the separation functional layer comprises: (a) a step of carrying out an interfacial polycondensation reaction on the support membrane using a solution containing a polyfunctional amine and a solution containing a polyfunctional acid halide to form a laminate of the support membrane and a polyamide-containing layer; and (b) a step of adjusting the amount of the polyfunctional amine contained in the laminate to 10 mg / m ２ 80mg / m or more ２ (c) a step of contacting the polyamide-containing layer with a compound (I) that reacts with a primary amino group to produce a diazonium salt or a derivative thereof; and (d) after the step (c), a step of contacting the polyamide-containing layer with a water-soluble compound (II) that is reactive with the compound (I) to form an azo group.

[0010] Another aspect of the present invention relates to a water treatment method including a reverse osmosis step of filtering raw water using the composite semipermeable membrane.

[0011] Another aspect of the present invention relates to a composite semipermeable membrane element comprising the above composite semipermeable membrane.

[0012] Another aspect of the present invention relates to a composite semipermeable membrane module comprising the above composite semipermeable membrane element.

[0013] According to the present invention, it is possible to provide a composite semipermeable membrane that combines high water permeability, initial removability performance, and high durability.

[0014] The present invention will be described in detail below. In this specification, "mass" has the same meaning as "weight".

[0015] (1) Composite Semipermeable Membrane The composite semipermeable membrane of the present invention comprises a support membrane and a separating functional layer located on the support membrane.

[0016] (1-1) Support membrane The support membrane has at least a porous support layer. The support membrane may further have a substrate. The support membrane does not substantially have the ability to separate ions or the like, and can provide strength to the separation functional layer.

[0017] The porous support layer is a layer that serves as a scaffold for forming the separation functional layer, and itself does not substantially have the ability to separate ions, etc. The size and distribution of the pores in the porous support layer are not particularly limited, but for example, a porous support layer having uniform fine pores or gradually larger fine pores from the surface on which the separation functional layer is formed to the other surface is preferred, and the size of the fine pores on the surface on which the separation functional layer is formed is 0.1 nm or more and 100 nm or less.

[0018] Porous support layer materials include homopolymers or copolymers such as polysulfone, polyethersulfone, polyamide, polyester, cellulose-based polymers, vinyl polymers, polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfone, and polyphenylene oxide, and these can be used alone or in blends. Cellulose-based polymers include cellulose acetate and cellulose nitrate, and vinyl polymers include polyethylene, polypropylene, polyvinyl chloride, and polyacrylonitrile. Among these, homopolymers or copolymers of polysulfone, polyamide, polyester, cellulose acetate, cellulose nitrate, polyvinyl chloride, polyacrylonitrile, polyphenylene sulfide, and polyphenylene sulfide sulfone are preferred. More preferred porous support layer materials include cellulose acetate, polysulfone, polyphenylene sulfide sulfone, and polyphenylene sulfone. Among these materials, polysulfone is generally preferred due to its high chemical, mechanical, and thermal stability and ease of molding.

[0019] The morphology of the porous support layer can be observed using a scanning electron microscope, a transmission electron microscope, or an atomic force microscope. For example, when observing the porous support layer using a scanning electron microscope, the porous support layer is peeled off from the substrate and then cut using a freeze-fracturing method to obtain a sample for cross-sectional observation. This sample is thinly coated with platinum, platinum-palladium, or ruthenium tetrachloride, preferably ruthenium tetrachloride, and observed using a high-resolution field-emission scanning electron microscope (UHR-FE-SEM) at an accelerating voltage of 3 to 15 kV. The high-resolution field-emission scanning electron microscope that can be used is, for example, the S-900 electron microscope manufactured by Hitachi, Ltd.

[0020] The thickness of the porous support layer is preferably 20 μm or more and 100 μm or less. When the thickness of the porous support layer is 20 μm or more, good pressure resistance can be obtained and a uniform support membrane without any defects can be obtained, and a composite semipermeable membrane including such a porous support layer can exhibit good salt removal performance. When the thickness of the porous support layer is 100 μm or less, the amount of amine monomer remaining after polyamide synthesis can be reduced. The thickness range of the porous support layer that achieves both removal performance and a reduction in the amount of amine remaining in the porous support layer is more preferably 20 μm or more and 45 μm or less, and the range in which the amount of remaining amine is optimized for membrane durability is even more preferably 20 μm or more and 31 μm or less, and particularly preferably 24 μm or more and 31 μm or less.

[0021] The substrate is a member that supports the porous support layer. Examples of the material for the substrate include polyester polymers, polyamide polymers, polyolefin polymers, and mixtures or copolymers thereof. Among these, polyester polymer fabrics, which have high mechanical and thermal stability, are particularly preferred.

[0022] As the form of the fabric, a long-fiber nonwoven fabric, a short-fiber nonwoven fabric, or even a woven or knitted fabric can be preferably used. Here, "long-fiber nonwoven fabric" means a nonwoven fabric made of fibers having an average fiber length of 300 mm or more and an average fiber diameter of 3 μm to 30 μm.

[0023] The air permeability of the substrate is 0.5 cc / cm ２ / s or more 5.0cc / cm ２When the air permeability of the substrate is within the above range, the polymer solution that forms the porous support layer can easily impregnate the substrate, improving the adhesion between the substrate and the porous support layer and increasing the physical stability of the resulting porous support membrane.

[0024] When the support film has a substrate, the thickness of the support film is preferably 30 μm or more and 300 μm or less, and more preferably 100 μm or more and 220 μm or less.

[0025] (1-2) Separation Functional Layer Among the components of the composite semipermeable membrane of the present invention, the separation functional layer substantially has the ability to separate solutes. The separation functional layer contains a crosslinked polyamide, and preferably contains a crosslinked polyamide as a main component.

[0026] In this specification, the phrase "X contains Y as a main component" means that Y is contained in 50% by mass or more of X, preferably 80% by mass or more, and more preferably 90% by mass or more, and also includes the case where X is composed of only Y.

[0027] The crosslinked polyamide is a polycondensation product of a polyfunctional amine and a polyfunctional acid halide. The polyfunctional amine and the polyfunctional acid halide constituting the crosslinked polyamide may each be one type or multiple types.

[0028] Here, the term "polyfunctional amine" refers to an amine having at least two primary amino groups and / or secondary amino groups in one molecule, at least one of which is a primary amino group. Examples of polyfunctional amines include polyfunctional aromatic amines such as phenylenediamine, xylylenediamine, 1,3,5-triaminobenzene, 1,2,4-triaminobenzene, 3,5-diaminobenzoic acid, 3-aminobenzylamine, and 4-aminobenzylamine, in which two amino groups are bonded to a benzene ring at the ortho, meta, or para positions; aliphatic amines such as ethylenediamine and propylenediamine; and alicyclic polyfunctional amines such as 1,2-diaminocyclohexane, 1,4-diaminocyclohexane, 4-aminopiperidine, and 4-aminoethylpiperazine.

[0029] The polyfunctional amine is preferably a polyfunctional aromatic amine having two to four primary amino groups and / or secondary amino groups per molecule. Examples of such polyfunctional aromatic amines include m-phenylenediamine (hereinafter also referred to as "m-PDA"), p-phenylenediamine, and 1,3,5-triaminobenzene, with m-PDA being particularly preferred. In order to achieve high selectivity, permeability, and heat resistance, it is preferred that the polyfunctional aromatic amine account for 80% by mass or more of the polyfunctional amine-derived moieties constituting the crosslinked polyamide.

[0030] The term "polyfunctional acid halide" refers to an acid halide having at least two halocarbonyl groups in one molecule. Examples of trifunctional acid halides include trimesoyl chloride (hereinafter also referred to as "TMC"), 1,3,5-cyclohexanetricarboxylic acid trichloride, and 1,2,4-cyclobutanetricarboxylic acid trichloride. Examples of bifunctional acid halides include aromatic bifunctional acid halides such as biphenyldicarboxylic acid dichloride, azobenzenedicarboxylic acid dichloride, terephthalic acid chloride, isophthalic acid chloride, and naphthalenedicarboxylic acid chloride; aliphatic bifunctional acid halides such as adipoyl chloride and sebacoyl chloride; and alicyclic bifunctional acid halides such as cyclopentanedicarboxylic acid dichloride, cyclohexanedicarboxylic acid dichloride, and tetrahydrofurandicarboxylic acid dichloride.

[0031] Considering the reactivity with polyfunctional amines, the polyfunctional acid halide is preferably a polyfunctional acid chloride, more preferably a polyfunctional aromatic acid chloride having 2 to 4 carbonyl chloride groups in one molecule, and even more preferably TMC.

[0032] The crosslinked polyamide may contain at least one compound selected from the various polyfunctional acid halides described above.

[0033] The separation functional layer preferably has a pleated structure. In order to obtain sufficient separation performance and permeate amount, the thickness of the separation functional layer in the pleated structure is preferably, for example, 8 nm to 20 nm, more preferably 9 nm to 13 nm.

[0034] (1-3) Characteristics The composite semipermeable membrane of the present invention contains an azo group (-N=N-) in the separation functional layer. The presence of the azo group in the separation functional layer is caused by chemical conversion of the amino group at the terminal of the polyamide. When the crosslinked polyamide in the separation functional layer contains an azo group, the pore structure of the composite semipermeable membrane can be optimized while improving hydrophilicity, and the water permeability and removability of the composite semipermeable membrane can be improved.

[0035] The azo groups in the separation functional layer were detected by peeling the substrate from the composite semipermeable membrane and then dissolving the porous support layer to isolate the separation functional layer. １３ Measurements are performed using C solid-state NMR to identify the carbon peak to which the azo group is bonded. The area of ​​the carbon peak to which the azo group is bonded, which appears near a chemical shift of 152 ppm, is calculated by drawing a baseline between 149 ppm and 155 ppm and taking the integral value within that range. If this value is 0.30 or greater, it is determined that the separation functional layer contains azo groups.

[0036] The composite semipermeable membrane of the present invention has a chromaticity b ＊ In the crosslinked polyamide of the separating functional layer, the amino group at the polyamide terminal is chemically converted to an azo group, so that the chromaticity b ＊ The chromaticity of the composite semipermeable membrane b ＊ and membrane performance are not simply proportional to each other above a certain level, and the chromaticity b ＊ If there are azo groups in an amount such that the chromaticity b is 0 or more, the membrane performance is sufficiently improved. On the other hand, when the amino groups at the polyamide terminals of the separating functional layer are chemically converted to azo groups, the amino groups of low molecular weight components such as monomers and oligomers remaining in the composite semipermeable membrane are also chemically converted to azo groups. Such low molecular weight components are decomposed and eluted by contact with multiple chemicals, resulting in a decrease in membrane performance. The present inventors have found that the chromaticity b＊ It has been found that when the color b of the composite semipermeable membrane is within the above range, the composite semipermeable membrane exhibits high initial performance in water permeability and removal property, and exhibits little change in performance due to contact with multiple chemicals, i.e., exhibits high durability. ＊ is preferably 1 or more and 16 or less, more preferably 2 or more and 11 or less, and even more preferably 2 or more and 7 or less.

[0037] Chromaticity b when measuring the composite semipermeable membrane from the surface on the separating functional layer side ＊ Is, L ＊ a ＊ b ＊ Color space (CIE 1976L ＊ a ＊ b ＊ The chromaticity is based on the color space, and the reflected color is measured from the surface of the separating functional layer side of the composite semipermeable membrane using a colorimeter conforming to JIS Z 8722:2009 condition c (color measurement method). ＊ For the measurement, the moisture on the composite semipermeable membrane is wiped off with a Kimtowel, and the composite semipermeable membrane is air-dried for 8 hours in an environment at a temperature of 25°C and a humidity of 40%. Note that the measurement is performed by the SCI (including specular reflection) method, since a consistent value can be obtained regardless of whether the composite semipermeable membrane is in a dry or wet state.

[0038] The composite semipermeable membrane according to this embodiment has a viscosity of 0.27 g / cm ２After immersing the composite semipermeable membrane in an amount of ethanol equivalent to 0.01% for 19 hours at 25°C, the absorbance of the ethanol at 435 nm is preferably 0 or more and 0.10 or less. Hereinafter, the ethanol after immersion is also referred to as the ethanol extract. The absorbance of the ethanol extract also represents the amount of compounds having azo groups in the separation functional layer. When the absorbance of the ethanol extract at 435 nm is 0 or more, the low-molecular-weight components containing azo groups in the membrane fill the coarse pores that allow solutes to permeate and act as charged components, thereby improving salt removal. On the other hand, when the absorbance of the ethanol extract at 435 nm is 0.10 or less, the impact of decomposition and elution due to chemical contact on membrane performance is minimal, so the composite semipermeable membrane can achieve both high initial performance and minimal performance change due to chemical contact, thereby achieving high durability. The absorbance of the ethanol extract at 435 nm is more preferably 0.01 or more and 0.08 or less, and even more preferably 0.02 or more and 0.07 or less.

[0039] The composite semipermeable membrane according to this embodiment has a viscosity of 0.27 g / cm ２ After immersing the composite semipermeable membrane in an amount of ethanol that satisfies the formula (I) for 19 hours at 25°C, the absorbance of the ethanol at 370 nm is preferably 0 to 0.20. If the absorbance of the ethanol extract at 370 nm is 0 or more, the low-molecular-weight components containing diazo groups in the membrane can fill the coarse pores that allow solutes to permeate, and if it is 0.20 or less, the impact of decomposition and elution due to chemical contact on membrane performance is minimal, thereby achieving both higher initial performance and higher durability. The absorbance of the ethanol extract at 370 nm is more preferably 0.01 to 0.20, and even more preferably 0.02 to 0.15.

[0040] The ethanol extract used for measuring absorbance was prepared so that the amount of ethanol per unit area of ​​the composite semipermeable membrane was 0.27 g / cm ２ The composite semipermeable membrane is immersed in ethanol as described above and allowed to stand for 19 hours at 25° C. The transmittance absorbance of the ethanol extract is measured using a spectrophotometer after correcting the absorbance of ethanol in which the composite semipermeable membrane is not immersed to be 0.

[0041] Furthermore, in the composite semipermeable membrane according to this embodiment, the amount of negative charge on the surface on the separation functional layer side increases due to the conversion reaction of the amino groups. Specifically, the zeta potential of the composite semipermeable membrane measured from the surface on the separation functional layer side is preferably in the range of -70 mV to -35 mV in a 10 mM NaCl aqueous solution at pH 7. When the negative charge is in this range under neutral conditions, salt removal is significantly improved. The zeta potential of the surface on the separation functional layer side in a 10 mM NaCl aqueous solution at pH 7 is more preferably -70 mV to -40 mV, and even more preferably -65 mV to -45 mV.

[0042] Furthermore, the zeta potential of the composite semipermeable membrane measured from the surface on the separation functional layer side is preferably in the range of -45 mV or more and -15 mV or less in a 10 mM NaCl aqueous solution at pH 3. A negative charge in the above range even under acidic conditions means that the terminal amino groups of the polyamide have been sufficiently converted, which contributes to improving membrane performance under neutral conditions. The zeta potential of the surface on the separation functional layer side in a 10 mM NaCl aqueous solution at pH 3 is more preferably -42 mV or more and -20 mV or less, and even more preferably -40 mV or more and -25 mV or less.

[0043] In the composite semipermeable membrane according to this embodiment, it is preferable that the amount of terminal amino groups A, the amount of terminal carboxyl groups B, and the amount of amide groups C of the crosslinked polyamide in the separating functional layer satisfy C / (A+B)≧1.0. C / (A+B) means the ratio of amide groups to the amount of terminal groups. If this value is 1.0 or more, excess azo groups are generated in the terminal groups, resulting in a chromaticity of b ＊ The increase in the water content can be suppressed. Furthermore, when C / (A+B) is 1.0 or more, the density of the polyamide is improved, making it suitable for removing salts and neutral solutes. C / (A+B) is more preferably in the range of 1.2 or more and 2.2 or less, i.e., 1.2≦C / (A+B)≦2.2, and even more preferably in the range of 1.5 or more and 2.0 or less, i.e., 1.5≦C / (A+B)≦2.0. When C / (A+B) is 2.2 or less, good water permeability is easily obtained. C / (A+B) can be controlled by the concentration of the monomers constituting the polyamide, the polymerization time, etc.

[0044] The amount of terminal amino groups A, the amount of terminal carboxyl groups B, and the amount of amide groups C are determined by the same method as in the above-mentioned method for detecting azo groups in the separating functional layer. １３ It can be determined by C solid state NMR measurement.

[0045] The composite semipermeable membrane according to this embodiment has a surface of a separation functional layer that is analyzed by time-of-flight secondary ion mass spectrometry (hereinafter also referred to as "TOF-SIMS"), and has a C ６ H ５ NO － The secondary ion intensity γ of the fragment peak derived from C ６ H ３ － The ratio γ / δ of the secondary ion intensity δ of the fragment peak derived from －２ 9.5 x 10 －２ It is preferable that the following is true: C ６ H ５ NO － The fragment peak derived from C is derived from the phenol structure of the polyamide separating functional layer. ６ H ３ － The fragment peak derived from the main skeleton of the polyamide separating functional layer is derived from the main skeleton. That is, γ / δ means the ratio of the phenol structure to the main skeleton. When γ / δ is 1.0 × 10 －２ When γ / δ is 9.5×10 or more, a sufficient amount of amino groups is chemically converted, and both high initial performance and high durability can be achieved. －２ When γ / δ is 3.0×10 or less, the decrease in chemical resistance due to the phenol structure can be suppressed. －２ Above 9.0 x 10 －２ More preferably, 6.0 x 10 －２ 8.5 x 10 －２ The following is even more preferred:

[0046] In TOF-SIMS analysis, the composite semipermeable membrane is vacuum-dried for at least two hours, and then pulsed ions (primary ions) are irradiated onto the surface of the separation functional layer of the composite semipermeable membrane placed in an ultra-high vacuum. The ions (secondary ions) released from the surface of the separation functional layer acquire a certain kinetic energy and are guided to a time-of-flight mass spectrometer, and the mass distribution of the secondary ions, i.e., the mass spectrum (fragment peaks), is obtained by precisely measuring the distribution of the flight times. γ / δ can be controlled by the monomer concentration, polymerization time, reaction conditions for converting amino groups to azo groups, and other factors.

[0047] (2) Manufacturing Method (2-1) Step of Forming Support Membrane The composite semipermeable membrane according to this embodiment comprises at least a porous support layer as a support membrane. The step of forming the porous support layer includes a step of applying a polymer solution to a substrate or a base, and a step of immersing the base coated with the solution in a coagulation bath to coagulate the polymer. When the porous support layer is formed on a substrate, the substrate is peeled off from the porous support layer. When a substrate is used, the substrate and the porous support layer together constitute the support membrane.

[0048] The step of forming the porous support layer may further include the step of preparing a polymer solution by dissolving the polymer in a good solvent for the polymer.

[0049] The porous support layer can be formed by any known method.

[0050] The temperature of the polymer solution during application is preferably 10°C or higher and 60°C or lower. If the temperature of the polymer solution is within this range, the polymer does not precipitate, and the polymer solution is sufficiently impregnated into the spaces between the fibers of the substrate and then solidifies. As a result, the porous support layer is firmly bonded to the substrate due to the anchor effect, and a good support film can be obtained. The preferred temperature range of the polymer solution can be adjusted as appropriate depending on the type of polymer used, the desired solution viscosity, etc.

[0051] The time period from when the polymer solution is applied to the substrate until the substrate is immersed in the coagulation bath is preferably 0.1 seconds or more and 5 seconds or less. If the time period until the substrate is immersed in the coagulation bath is within this range, the organic solvent solution containing the polymer is sufficiently impregnated into the spaces between the fibers of the substrate and then solidified. The preferred range of the time period until the substrate is immersed in the coagulation bath can be appropriately adjusted depending on the type of polymer solution used, the desired solution viscosity, etc.

[0052] Water is generally used as the coagulation bath, but any solution that does not dissolve the polymers that are components of the porous support layer is acceptable, and is not particularly limited. The composition of the coagulation bath changes the membrane morphology of the resulting support membrane, which in turn changes the resulting composite semipermeable membrane. The temperature of the coagulation bath is preferably -20°C or higher and 100°C or lower, and more preferably 10°C or higher and 50°C or lower. If the temperature of the coagulation bath is within this range, the vibration of the coagulation bath surface due to thermal motion does not become severe, and the smoothness of the membrane surface after membrane formation is maintained. Furthermore, if the temperature is within this range, the coagulation rate is appropriate and membrane formability is good.

[0053] Next, the support membrane thus obtained is washed with hot water to remove the solvent remaining in the membrane. The temperature of the hot water at this time is preferably 40°C or higher and 100°C or lower, and more preferably 60°C or higher and 95°C or lower. Within this range, the shrinkage of the support membrane does not increase and the amount of permeated water is good. Furthermore, within this temperature range, the washing effect is sufficient.

[0054] The above specific conditions are suitable when polysulfone is used as the material.

[0055] (2-2) Step of Forming Separation Functional Layer The step of forming the separation functional layer in the method of the present invention for producing a composite semipermeable membrane comprising a support membrane and a separation functional layer provided on the support membrane includes the following steps: (a) a step of carrying out an interfacial polycondensation reaction on the support membrane using a solution containing a polyfunctional amine and a solution containing a polyfunctional acid halide to form a laminate of the support membrane and the polyamide-containing layer; (b) a step of adjusting the amount of polyfunctional amine contained in the laminate to 10 mg / m ２ 80mg / m or more ２(c) contacting the polyamide-containing layer with a compound (I) that reacts with a primary amino group to form a diazonium salt or a derivative thereof; and (d) after step (c), contacting the polyamide-containing layer with a water-soluble compound (II) that is reactive with compound (I) to form an azo group.

[0056] In the step (a), preferred embodiments of the polyfunctional amine and the polyfunctional acid halide are the same as those described above.

[0057] The concentration of the solution containing the polyfunctional amine (hereinafter also referred to as "polyfunctional amine 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. Examples of the solvent in the polyfunctional amine solution include water and highly hydrophilic organic solvents, and among these, water is preferred.

[0058] The polyfunctional amine solution may contain surfactants, organic solvents, alkaline compounds, antioxidants, etc., as long as they do not inhibit the reaction between the polyfunctional amine and the polyfunctional acid halide.

[0059] Hereinafter, the process will be described using an example in which a polyfunctional aromatic amine is used as the polyfunctional amine and a polyfunctional aromatic acid chloride is used as the polyfunctional acid halide.

[0060] The organic solvent for dissolving the polyfunctional acid halide may be any solvent that is immiscible with water, does not destroy the support film, and does not inhibit the crosslinked aromatic polyamide production reaction. Examples of organic solvents for dissolving the polyfunctional acid halide include hydrocarbons such as octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, heptadecane, hexadecane, cyclooctane, ethylcyclohexane, 1-octene, and 1-decene, and halogenated hydrocarbons such as trichlorotrifluoroethane. These solvents can be used alone or in combination of two or more.

[0061] In step (a), in order to carry out interfacial polycondensation on the support membrane, first, the surface of the porous support layer of the support membrane is coated with an aqueous solution of a polyfunctional aromatic amine.

[0062] The method for coating the surface of the porous support layer with the aqueous polyfunctional aromatic amine solution may be any method that uniformly and continuously coats the surface of the porous support layer with the aqueous solution, and may be carried out by a known application means, such as a method of coating the surface of the porous support layer with the aqueous solution or a method of immersing the porous support layer in the aqueous solution.

[0063] The contact time between the porous support layer and the aqueous polyfunctional aromatic amine solution is preferably within a range of 5 seconds to 10 minutes, more preferably within a range of 10 seconds to 3 minutes.

[0064] Next, it is preferable to remove the excess applied aqueous solution by a draining step. For example, the method of draining the solution may include holding the membrane surface vertically and allowing the solution to flow naturally. After draining the solution, the membrane surface may be dried to remove all or part of the water in the aqueous solution.

[0065] Thereafter, the above-mentioned polyfunctional aromatic acid chloride solution is applied to the porous support layer coated with the polyfunctional aromatic amine aqueous solution, and a crosslinked aromatic polyamide is formed by interfacial polycondensation.

[0066] The time for carrying out the interfacial polycondensation is preferably from 0.1 seconds to 3 minutes, more preferably from 0.1 seconds to 1 minute.

[0067] The concentration of the polyfunctional aromatic acid chloride in the polyfunctional aromatic acid chloride solution is not particularly limited, but from the viewpoint of forming a separation functional layer sufficiently without defects and from the viewpoint of cost, it is preferably, for example, 0.01 mass % or more and 1.0 mass % or less.

[0068] Next, the organic solvent remaining after the reaction is preferably removed by a draining step. The organic solvent can be removed, for example, by a method in which the membrane is held vertically and excess organic solvent is removed by gravity flow. In this case, the vertical holding time is preferably 1 minute or more and 5 minutes or less, more preferably 1 minute or more and 3 minutes or less. Holding the membrane for 1 minute or more makes it easier to obtain a crosslinked aromatic polyamide having the desired functionality, while holding the membrane for 5 minutes or less can prevent defects due to excessive drying of the organic solvent, thereby preventing performance degradation.

[0069] This results in a laminate in which a polyamide-containing layer is laminated on a support film.

[0070] In step (b), the amount of polyfunctional amine contained in the laminate was 10 mg / m ２ 80mg / m or more ２ The amount of polyfunctional amine is preferably adjusted to the above range by washing with hot water. Specifically, the temperature of the hot water used to wash the laminate of the support film and the polyamide-containing layer is preferably 50°C or higher and 150°C or lower, and more preferably 70°C or higher and 130°C or lower. The time for washing the laminate is preferably 1 second or higher and 10 minutes or lower, and more preferably 1 minute or higher and 8 minutes or lower. Washing with hot water can be performed, for example, by immersing the laminate in hot water or by exposing it to running hot water.

[0071] The amount of polyfunctional aromatic amine remaining in the laminate (hereinafter also referred to as the "amount of amine in the film") is ２ The amount of amine in the film is 10 mg / m or more and 80 mg or less, and preferably 10 mg or more and 60 mg or less. ２ If the chromaticity b is 0 or more, a preferable amount of azo groups is generated by the subsequent treatment. ＊ The composite semipermeable membrane has a high removal performance. ２ If the chromaticity of the film is less than 100%, the generation of unnecessary azo groups is suppressed, and the chromaticity of the film is ＊ is 20 or less, and high durability against contact with multiple chemicals can be achieved.

[0072] To adjust the amount of amine in the film, a step of contacting the polyamide-containing layer with an aqueous solution containing at least one compound selected from the group consisting of alcohols, ethers, amides, inorganic acids, and organic acids may be carried out prior to the hot water washing. Such a compound can temporarily relax the structure of the polyamide and cleave the interaction between the residual amine and the polyamide, thereby significantly improving the efficiency of the subsequent hot water washing.

[0073] Examples of compounds used in the above process include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, and glycerin. Examples of ethers include ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol butyl methyl ether, diethylene glycol isopropyl methyl ether, diethylene glycol diacetate, diethylene glycol dibenzoate, diethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate, diethylene glycol bis(p-toluenesulfonic acid), diethylene glycol bis(3-aminopropyl)ether, 1,2-bis(2-aminoethoxy)ethane, dipropylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and tetraethylene glycol diethyl ether. Examples of amides include N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, etc. Examples of inorganic acids include hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, etc. Examples of organic acids include acetic acid, citric acid, oxalic acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, 10-camphorsulfonic acid, aminoethylsulfonic acid, etc.

[0074] That is, step (b) preferably includes: (b1) a step of contacting the polyamide-containing layer with an aqueous solution containing at least one compound selected from the group consisting of alcohols, ethers, amides, inorganic acids, and organic acids; and (b2) a step of washing the laminate with hot water after step (b1).

[0075] The concentration of the compound in the aqueous solution is not particularly limited as long as it is effective in relaxing the structure of the polyamide, is not excessive, and does not damage the support film, but is preferably 1% by mass or more and 50% by mass or less.

[0076] From the viewpoint of sufficiently promoting structural relaxation of the polyamide and suppressing a decrease in membrane performance due to structural relaxation of the polyamide, the contact time with the aqueous solution containing the compound is preferably 3 seconds or more and 60 seconds or less.

[0077] The temperature of the aqueous solution containing the compound when brought into contact with the polyamide-containing layer is preferably 70° C. or lower. When the temperature is 70° C. or lower, activation of molecular motion of the polyamide due to heat is suppressed, and excessive acceleration of structural relaxation by the compound can be suppressed.

[0078] The method for producing a composite semipermeable membrane of the present invention includes, after step (b), a step (c) of contacting the polyamide-containing layer with compound (I) that reacts with primary amino groups on the separating functional layer to produce a diazonium salt or a derivative thereof, and, after step (c), a step (d) of contacting the polyamide-containing layer with a water-soluble compound (II) that is reactive with compound (I). By performing the above steps (c) and (d), the removal performance and water permeability of the composite semipermeable membrane can be further improved.

[0079] Examples of the compound (I) that reacts with a primary amino group to produce a diazonium salt or a derivative thereof include aqueous solutions of nitrous acid and its salts, nitrosyl compounds, etc. Since aqueous solutions of nitrous acid and nitrosyl compounds tend to generate gas and decompose, it is preferable to sequentially produce nitrous acid, for example, by reacting a nitrite with an acidic solution. Generally, nitrite reacts with hydrogen ions to produce nitrous acid (HNO ２ Nitrous acid can be efficiently produced when the pH of the aqueous solution is 7 or less, preferably 5 or less, and more preferably 4 or less. Among these, an aqueous solution of sodium nitrite reacted with hydrochloric acid or sulfuric acid in an aqueous solution is particularly preferred from the viewpoint of ease of handling.

[0080] The concentration of the compound (I), e.g., sodium nitrite, which reacts with the primary amino group to form a diazonium salt or a derivative thereof, is preferably 0.3% by mass or more and 0.5% by mass or less. Within this concentration range, sufficient production of the diazonium salt or a derivative thereof is achieved, generation of nitrous acid gas and the like can be suppressed, and industrial handling of the solution becomes easy.

[0081] The temperature of compound (I) is preferably 15° C. or higher and 45° C. or lower. Within this range, the reaction does not take too long, and the decomposition of nitrous acid is not too rapid, making it easy to handle.

[0082] The contact time between the polyamide-containing layer and compound (I) may be sufficient as long as it takes for a diazonium salt and / or its derivative to be produced. When the concentration of compound (I) is high, a short treatment time is possible, whereas when the concentration is low, a long treatment time is sufficient. For example, when using a solution with a sodium nitrite concentration of 0.3% by mass or more and 0.5% by mass or less, the contact time is preferably within 10 minutes, more preferably within 3 minutes. The contact method is not particularly limited; for example, the compound (I) solution may be applied (coated), or the composite semipermeable membrane may be immersed in the compound (I) solution. Any solvent may be used to dissolve compound (I) as long as it dissolves compound (I) and does not erode the composite semipermeable membrane. The solution may also contain surfactants, acidic compounds, alkaline compounds, etc., as long as they do not interfere with the reaction between the primary amino group and the reagent.

[0083] Next, the composite semipermeable membrane containing the diazonium salt or its derivative is contacted with a water-soluble compound (II) reactive with compound (I), i.e., a water-soluble compound (II) that reacts with the diazonium salt or its derivative. Examples of the water-soluble compound (II) reactive with compound (I) include chloride ions, bromide ions, cyanide ions, iodide ions, fluoroboric acid, hypophosphorous acid, sodium bisulfite, sulfite ions, hydrogen sulfide, and thiocyanic acid. These compounds may be used alone or in combination, or may be contacted with different compounds multiple times. The water-soluble compound (II) is preferably sodium bisulfite or sulfite ions. When the composite semipermeable membrane containing the diazonium salt or its derivative is reacted with sodium bisulfite, sulfite ions, or the like, a substitution reaction occurs instantly, ultimately replacing the amino groups at the polyamide terminals with sulfo groups.

[0084] The concentration and time for contacting the polyamide-containing layer with the water-soluble compound (II) reactive with compound (I) can be appropriately adjusted to obtain the desired effect.

[0085] The temperature at which the polyamide-containing layer is brought into contact with the water-soluble compound (II) reactive with compound (I) is preferably 10° C. or higher and 90° C. or lower. Within this temperature range, the reaction proceeds easily, while a decrease in the amount of permeated water due to shrinkage of the polymer does not occur.

[0086] (3) Use of Composite Semipermeable Membrane The composite semipermeable membrane according to this embodiment is wound around a cylindrical water collection pipe having many holes, together with a raw water flow path material such as a plastic net, a permeate water flow path material such as tricot, and, if necessary, a film for increasing pressure resistance, and is suitably used as a spiral composite semipermeable membrane element. Furthermore, this element can be connected in series or in parallel and housed in a pressure vessel to form a composite semipermeable membrane module.

[0087] Furthermore, the composite semipermeable membranes, their elements, and modules can be combined with a pump that supplies raw water to them, a device that pretreats the raw water, etc. to form a fluid separation device. By using this separation device, raw water can be separated into permeated water such as drinking water and concentrated water that did not permeate the membrane, thereby obtaining water suitable for the intended purpose.

[0088] The salt rejection rate improves as the operating pressure of the fluid separation device increases, but the energy required for operation also increases. Also, taking into consideration the durability of the composite semipermeable membrane, the operating pressure when the water to be treated passes through the composite semipermeable membrane is preferably 0.1 MPa or more and 10 MPa or less. As the feed water temperature increases, the salt rejection rate decreases, but as the temperature decreases, the amount of permeated water also decreases. Therefore, a temperature of 5°C or more and 45°C or less is preferred. Furthermore, as the pH of the feed water increases, there is a risk of magnesium scale formation in the case of high-salt feed water such as seawater, and there is also concern about membrane degradation due to high-pH operation. Therefore, operation in the neutral region is preferred.

[0089] Examples of raw water to be treated by the composite semipermeable membrane according to the embodiment of the present invention include liquid mixtures such as seawater, brine, and wastewater containing 500 mg / L to 100 g / L of total dissolved solids (hereinafter also referred to as "TDS") and 0.1 mg / L to 1000 mg / L of nonionic substances. Generally, TDS is expressed as "mass / volume" or "mass ratio." According to definition, it can be calculated from the weight of the residue obtained by evaporating a solution filtered through a 0.45 micron filter at a temperature of 39.5°C to 40.5°C, but it can be more simply calculated from the practical salinity (S).

[0090] The composite semipermeable membrane according to this embodiment preferably has a NaCl rejection rate of 99.50% or more and 99.90% or less, more preferably 99.60% or more and 99.90% or less, when feed water containing 2,000 ppm of NaCl, pH 7, and 25°C is passed through it at an operating pressure of 1.55 MPa, as measured by the method described below in "NaCl rejection rate." From the viewpoint of reducing energy consumption during membrane operation, the amount of permeated water under the above conditions is 1.15 m ３ / m ２It is preferable that the number of days is 1 or more.

[0091] As described above, the present invention includes the following configurations (1) to (16): (1) A composite semipermeable membrane comprising a support membrane and a separation functional layer containing a crosslinked polyamide located on the support membrane, wherein the separation functional layer contains an azo group, and the composite semipermeable membrane has a chromaticity b ＊ (2) 0.27 g / cm ２ The composite semipermeable membrane according to (1), wherein the composite semipermeable membrane has an absorbance of 0 or more and 0.10 or less at 435 nm after immersing the composite semipermeable membrane in an amount of ethanol in a range of 0.27 g / cm at 25°C for 19 hours. ２ (4) The composite semipermeable membrane according to any one of (1) to (3), wherein the zeta potential of the surface of the separation functional layer is in the range of -70 mV to -35 mV in a 10 mM NaCl aqueous solution at pH 7. (5) The composite semipermeable membrane according to any one of (1) to (4), wherein the zeta potential of the surface of the separation functional layer is in the range of -45 mV to -15 mV in a 10 mM NaCl aqueous solution at pH 3. (6) The composite semipermeable membrane according to any one of (1) to (5), wherein the amount of terminal amino groups A, the amount of terminal carboxy groups B, and the amount of amide groups C of the crosslinked polyamide satisfy C / (A+B)≧1.0. (7) The composite semipermeable membrane according to any one of (1) to (6), wherein the support membrane has a substrate and a porous support layer, and the thickness of the porous support layer is 20 μm or more and 31 μm or less. (8) When the surface of the separation functional layer is analyzed by time-of-flight secondary ion mass spectrometry, ６ H ５ NO － The secondary ion intensity γ of the fragment peak derived from C ６ H ３ － The ratio γ / δ of the secondary ion intensity δ of the fragment peak derived from －２ 9.5 x 10 －２(9) A composite semipermeable membrane according to any one of (1) to (7) above, which is as follows: (9) A method for producing a composite semipermeable membrane comprising a support membrane and a separation functional layer provided on the support membrane, wherein the step of forming the separation functional layer comprises: (a) a step of carrying out an interfacial polycondensation reaction on the support membrane using a solution containing a polyfunctional amine and a solution containing a polyfunctional acid halide to form a laminate of the support membrane and a polyamide-containing layer; and (b) a step of increasing the amount of the polyfunctional amine contained in the laminate to 10 mg / m ２ 80mg / m or more ２ (c) a step of contacting the polyamide-containing layer with a compound (I) that reacts with a primary amino group to produce a diazonium salt or a derivative thereof, and (d) a step of forming an azo group after the step (c) by contacting the polyamide-containing layer with a water-soluble compound (II) that is reactive with compound (I). (10) A method for producing the composite semipermeable membrane according to (9) above, wherein the step (b) comprises a step of washing the laminate with hot water. (11) A method for producing the composite semipermeable membrane according to (10) above, wherein the step (b) comprises: (b1) a step of contacting the polyamide-containing layer with an aqueous solution containing at least one compound selected from the group consisting of alcohols, ethers, amides, inorganic acids, and organic acids, and (b2) a step of washing the laminate with hot water after the step (b1). (12) A method for producing a composite semipermeable membrane according to any one of (9) to (11) above, wherein the polyfunctional amine is m-phenylenediamine. (13) A method for producing a composite semipermeable membrane according to any one of (9) to (12) above, wherein the water-soluble compound (II) is sodium hydrogensulfite or sulfite ions. (14) A water treatment method comprising a reverse osmosis step of filtering raw water using the composite semipermeable membrane according to any one of (1) to (7) above. (15) A composite semipermeable membrane element comprising the composite semipermeable membrane according to any one of (1) to (7) above. (16) A composite semipermeable membrane module comprising the composite semipermeable membrane element according to (15) above.

[0092] The present invention will be described below with reference to examples, but the present invention is not limited to these examples in any way.

[0093] 1. Measurement of Characteristics (NaCl Rejection Rate) An aqueous NaCl solution (hereinafter also referred to as "evaluation water") adjusted to a temperature of 25°C, pH 7, and a NaCl concentration of 2000 ppm was supplied to a composite semipermeable membrane at an operating pressure of 1.55 MPa to perform membrane filtration. The electrical conductivity of the feed water and permeate water was measured using an electrical conductivity meter manufactured by Toa Denpa Kogyo Co., Ltd. to obtain their respective practical salinities, i.e., NaCl concentrations. The NaCl rejection rate was calculated from the thus obtained NaCl concentrations according to the following formula. Here, NaCl concentration (ppm) refers to the concentration on a mass basis. NaCl rejection rate (%) = 100 × {1 - (NaCl concentration in permeate water / NaCl concentration in feed water)}

[0094] (Permeated Water Amount) In the test in the preceding paragraph, the permeated water amount of the evaluation water was measured, and the value converted into the permeated water amount (cubic meters) per square meter of membrane surface per day was defined as the permeated water amount (m ３ / m ２ / day).

[0095] (Composite Deterioration Test) After three sets of tests in the order of (a) → (b) below, the following (c) was performed once, and then three sets of tests in the order of (a) → (b) were performed. Then, the composite semipermeable membrane was used to measure the NaCl rejection rate (%) and the permeation rate (m ) of the composite semipermeable membrane by the method described in the above-mentioned "NaCl rejection rate" and "permeation rate." ３ / m ２ / day) was determined. (a) The composite semipermeable membrane was immersed for 24 hours in an aqueous solution at 30°C that had been adjusted to pH 12.4 using sodium hydroxide. (b) The composite semipermeable membrane was immersed for 1 hour in an aqueous solution at 30°C that had been adjusted to pH 2 using sulfuric acid. (c) The composite semipermeable membrane was immersed for 96 hours in an aqueous solution at 25°C that had been adjusted to a free chlorine concentration of 5 ppm using sodium hypochlorite and to pH 7 using potassium dihydrogen phosphate. Thereafter, the composite semipermeable membrane was immersed for 10 minutes in a 0.1 mass% aqueous sodium hydrogen sulfite solution at 25°C.

[0096] (Amount of amine in membrane) The moisture on the surface of the separating functional layer of the composite semipermeable membrane was wiped off with a Kimtowel. ２The composite semipermeable membrane was immersed in 20 g of ethanol in a polypropylene container. After standing at 25 ° C. for 19 hours, the composite semipermeable membrane was removed and the absorbance of the ethanol at 288 nm was measured using a spectrophotometer (Shimadzu Corporation UV-2450). When measuring, the spectrophotometer was corrected so that the absorbance of the ethanol at 288 nm before immersion in the composite semipermeable membrane was 0. A calibration curve was created from the absorbance at 288 nm of ethanol in which the polyfunctional amine used to form the separation functional layer was dissolved to a predetermined concentration, and the absorbance of 1 m of the composite semipermeable membrane was calculated from the obtained absorbance. ２ Amount of amine per unit (mg / m ２ ) was calculated.

[0097] (Presence or absence of azo group in the separating functional layer) Composite semipermeable membrane 5m ２ The substrate was physically peeled off from the substrate, and the porous support layer and separation function layer were recovered. After leaving to dry at 25°C for 24 hours, the mixture was added in small amounts to a beaker containing dichloromethane and stirred to dissolve the polymer that constitutes the porous support layer, and the insoluble matter in the beaker was recovered with filter paper. The recovered insoluble matter was placed in a beaker containing dichloromethane and stirred, and the insoluble matter in the beaker was recovered again. This process was repeated until no elution of the polymer that forms the porous support layer could be detected in the dichloromethane solution. The recovered insoluble matter was dried in a vacuum dryer to remove any remaining dichloromethane. The obtained insoluble matter was freeze-pulverized to form a powder sample, which was sealed in a sample tube used for solid-state NMR measurement and analyzed by DD / MAS method. １３ C solid state NMR measurement was carried out. １３ For the C solid-state NMR measurement, an AVANCE 400 manufactured by Bruker Biospin was used. The measurement conditions are as follows: Reference material: silicone rubber (internal reference: 1.56 ppm), Sample rotation speed: 14 kHz, Pulse repetition time: 120 s (DD / MAS method).

[0098] From the obtained spectrum, peak division was performed for each peak derived from the carbon atom to which each functional group was bonded, and the area of ​​the carbon peak to which the azo group was bonded, appearing at a chemical shift of 152 ppm, was calculated. If the value was 0.30 or more, it was determined that the azo group was contained in the separation functional layer (azo group contained "present"), and if it was less than 0.30, it was determined that the azo group was not contained in the separation functional layer (azo group contained "absent").

[0099] (Ratio of amide groups to the amount of terminal groups in the separating functional layer) The same method as for confirming the presence of azo groups in the separating functional layer was used. １３C solid-state NMR measurement was performed, and the obtained spectrum was divided into peaks derived from the carbon atoms to which each functional group was bonded. The functional group ratio was then quantified from the area of ​​the divided peaks. C / (A+B) was calculated from the amount of terminal amino groups A, the amount of terminal carboxyl groups B, and the amount of amide groups C of the crosslinked polyamide in the separation functional layer. More specifically, when the separation functional layer was formed by interfacial polycondensation of m-PDA and TMC, the calculation was performed as follows. The area D of the carboxylic acid skeleton unit derived from TMC and the area E of the amine skeleton unit derived from m-PDA were calculated using the following formulas: Carboxylic acid skeleton unit area D = (peak area at 166 ppm) / 3 Amine skeleton unit area E = (sum of peak areas at 156, 152, 148, and 145 to 100 ppm) / 6 - (peak area at 166 ppm) / 3 Then, the number of hydroxyl groups F, the number of azo groups G, the number of amino groups H, and the number of amide groups I in the amine skeleton unit were calculated using the following formulas. Number of hydroxyl groups in an amine skeleton unit F = (peak area at 156 ppm) / E Number of azo groups in an amine skeleton unit G = (peak area at 152 ppm) / E Number of amino groups in an amine skeleton unit H = (peak area at 148 ppm) / E Number of amide groups in an amine skeleton unit I = 2 - (F + G + H) Furthermore, the number of amide groups J and the number of carboxy groups K in a carboxylic acid skeleton unit are calculated based on the following formulas: Number of amide groups in a carboxylic acid skeleton unit J = I x E / D Number of carboxy groups in a carboxylic acid skeleton unit K = 3 - I From the above results, the amount of terminal amino groups A and the amount of terminal carboxy groups B are calculated using the following formulas: Amount of terminal amino groups A = (F + G + H) / I Amount of terminal carboxy groups B = K / J Note that A and B represent the amount of each functional group per amide group, and in this case, the amount of amide groups C is 1.

[0100] (Film chromaticity b ＊ The moisture on the surface of the separating functional layer of the composite semipermeable membrane was wiped off with a Kimtowel and air-dried for 8 hours in an environment of 25°C and 40% humidity. The dried composite semipermeable membrane was measured on a black laboratory bench using a colorimeter (Konica Minolta CM-25d) in SCI mode under the conditions of a measuring diameter of 8 mm from the surface of the separating functional layer, a 2° field of view, and a light source of D65. ＊The same film was measured at 10 different points, and the average value was taken as the chromaticity b ＊ It was decided.

[0101] (Absorbance) The moisture on the surface of the separating functional layer of the composite semipermeable membrane was wiped off with a Kimtowel, and the composite semipermeable membrane was ２ The composite semipermeable membrane was immersed in 80 g of ethanol in a polypropylene container and allowed to stand at 25°C for 19 hours. The absorbance of the ethanol at 435 nm and 370 nm after immersion of the composite semipermeable membrane was measured using a spectrophotometer (Shimadzu Corporation, UV-2450). When measuring, the spectrophotometer was corrected so that the absorbance of the ethanol at the measurement target wavelength before immersion in the composite semipermeable membrane was 0.

[0102] (Zeta potential) After immersing the composite semipermeable membrane in ultrapure water for 10 minutes to wash it, it was placed in a flat sample cell so that the surface of the separation functional layer of the composite semipermeable membrane was in contact with the monitor particle solution, and measurement was performed using an ELSZneo manufactured by Otsuka Electronics Co., Ltd. The monitor particle solution used was a solution in which hydroxypropyl cellulose-coated polystyrene latex monitor particles with an average particle size of 500 nm were dispersed at 0.1 mass % in a 10 mM NaCl aqueous solution adjusted to pH 7 and pH 3, respectively. Using the above monitor particle solution, the surface zeta potential α (pH 7, NaCl 10 mM) and surface zeta potential β (pH 3, NaCl 10 mM) of the separation functional layer were measured.

[0103] (C ６ H ５ NO － and a fragment peak γ derived from C ６ H ３ －The composite semipermeable membrane was washed by immersing it in ultrapure water for 10 minutes, the moisture on the surface of the separation functional layer was wiped off with a Kim towel, and the membrane was dried in a vacuum for 2 hours. The surface of the separation functional layer of the dried composite semipermeable membrane was analyzed using a TOF.SIMS5 (manufactured by ION-TOF) under the following conditions. γ / δ was calculated from the secondary ion intensity of each fragment peak obtained. Secondary ion polarity: negative Mass range (m / z): 0 to 1500 Raster size: 300 μm Number of scans: 32 Number of pixels (one side): 256 pixels Measurement vacuum level (before sample introduction): 4 x 10 －７ Pa or less Primary ion species: Bi ３ ＋＋ Primary ion acceleration voltage: 25 kV Pulse width: 10.9 ns Bunching: Yes Charge neutralization: Yes Post-acceleration: 9.5 kV

[0104] 2. Preparation of composite semipermeable membrane (Reference Example 1) A polyester nonwoven fabric (air permeability 2.0 cc / cm) made of long fibers was used. ２ A 15.0 mass % DMF solution of polysulfone was cast onto the porous support membrane (polysulfone / s) at 25°C, and the membrane was immediately immersed in pure water and left for 5 minutes to prepare a support membrane with a porous support layer thickness of 40 µm.

[0105] Reference Example 2 In the same manner as in Reference Example 1, a support membrane having a porous support layer thickness of 30 μm was produced by adjusting the clearance when a 15.0 mass % DMF solution of polysulfone was cast.

[0106] Reference Example 3 In the same manner as in Reference Example 1, a support membrane having a porous support layer with a thickness of 25 μm was produced by adjusting the clearance when a 15.0 mass % DMF solution of polysulfone was cast.

[0107] Reference Example 4 In the same manner as in Reference Example 1, a support membrane having a porous support layer thickness of 19 μm was produced by adjusting the clearance when a 15.0 mass % DMF solution of polysulfone was cast.

[0108] (Comparative Example 1) The support membrane obtained in Reference Example 1 was immersed in a 3.5% by mass aqueous solution of m-PDA, after which excess aqueous solution was removed, and then an n-decane solution in which TMC was dissolved to a concentration of 0.15% by mass was applied so that the surface of the porous support layer was completely wet. Next, in order to remove excess solution from the membrane, the membrane was vertically drained, and dried by blowing air at 25°C using a fan, followed by washing with hot water at 85°C for 2 minutes to obtain a composite semipermeable membrane. The amount of amine in the obtained membrane was 122 mg / m ２ It was.

[0109] (Comparative Example 2) The composite semipermeable membrane obtained in Comparative Example 1 was immersed in a 0.4 mass% aqueous sodium nitrite solution at 35°C and pH 3 for 40 seconds, and then immersed in a 0.1 mass% aqueous sodium sulfite solution for 2 minutes to obtain a composite semipermeable membrane.

[0110] (Comparative Example 3) The composite semipermeable membrane obtained in Comparative Example 1 was immersed in a 0.1 mass% aqueous sodium nitrite solution at 35°C and pH 3 for 40 seconds, and then immersed in a 0.1 mass% aqueous sodium sulfite solution for 2 minutes to obtain a composite semipermeable membrane.

[0111] (Comparative Example 4) A composite semipermeable membrane was obtained by the same procedure as in Comparative Example 1, except that the concentration of the m-PDA aqueous solution was 2.5% by mass. The amount of amine in the obtained membrane was 98 mg / m ２ Thereafter, the membrane was immersed in a 0.4 mass % aqueous sodium nitrite solution at 35° C. and pH 3 for 40 seconds, and then in a 0.1 mass % aqueous sodium sulfite solution for 2 minutes to obtain a composite semipermeable membrane.

[0112] (Comparative Example 5) A composite semipermeable membrane was obtained by the same procedure as in Comparative Example 1, except that it was washed with hot water at 85°C for 10 minutes. The amount of amine in the obtained membrane was 85 mg / m ２ Thereafter, the membrane was immersed in a 0.4 mass % aqueous sodium nitrite solution at 35° C. and pH 3 for 40 seconds, and then in a 0.1 mass % aqueous sodium sulfite solution for 2 minutes to obtain a composite semipermeable membrane.

[0113] (Comparative Example 6) The composite semipermeable membrane obtained in Comparative Example 1 was immersed in a 0.4 mass% sodium nitrite aqueous solution of pH 3 at 35°C for 40 seconds, and then immersed in a 0.01 mass% m-PDA aqueous solution at 80°C for 1 minute to obtain a composite semipermeable membrane.

[0114] (Comparative Example 7) A composite semipermeable membrane was obtained by the same procedure as in Comparative Example 1, except that the membrane was immersed in a 10% by mass aqueous solution of isopropanol at 25°C for 10 seconds before being washed with hot water at 85°C for 2 minutes. The amount of amine in the obtained membrane was 51 mg / m ２ It was.

[0115] (Comparative Example 8) The composite semipermeable membrane obtained in Comparative Example 7 was immersed in a 0.4 mass% sodium nitrite aqueous solution at 35°C and pH 3 for 40 seconds, and then immersed in a 0.01 mass% m-PDA aqueous solution at 80°C for 1 minute to obtain a composite semipermeable membrane.

[0116] (Comparative Example 9) A composite semipermeable membrane was obtained by the same procedure as in Example 1, except that the support membrane obtained in Reference Example 4 (porous support layer thickness: 19 μm) was used. The amount of amine in the obtained membrane was 7 mg / m ２ Thereafter, the membrane was immersed in a 0.4 mass % aqueous sodium nitrite solution at 35° C. and pH 3 for 40 seconds, and then in a 0.1 mass % aqueous sodium sulfite solution for 2 minutes to obtain a composite semipermeable membrane.

[0117] (Example 1) The composite semipermeable membrane obtained in Comparative Example 7 was immersed in a 0.4 mass% aqueous sodium nitrite solution at 35°C and pH 3 for 40 seconds, and then immersed in a 0.1 mass% aqueous sodium sulfite solution for 2 minutes to obtain a composite semipermeable membrane.

[0118] (Example 2) A composite semipermeable membrane was obtained by the same procedure as in Comparative Example 1, except that the membrane was immersed in a 10% by mass aqueous solution of ethylene glycol at 25°C for 10 seconds before being washed with hot water at 85°C for 2 minutes. The amount of amine in the obtained membrane was 44 mg / m ２ Thereafter, the membrane was immersed in a 0.4 mass % aqueous sodium nitrite solution at 35° C. and pH 3 for 40 seconds, and then in a 0.1 mass % aqueous sodium sulfite solution for 2 minutes to obtain a composite semipermeable membrane.

[0119] (Example 3) A composite semipermeable membrane was obtained by the same procedure as in Comparative Example 1, except that the membrane was immersed in a 10% by mass aqueous solution of glycerin at 25°C for 10 seconds before being washed with hot water at 85°C for 2 minutes. The amount of amine in the obtained membrane was 46 mg / m ２Thereafter, the membrane was immersed in a 0.4 mass % aqueous sodium nitrite solution at 35° C. and pH 3 for 40 seconds, and then in a 0.1 mass % aqueous sodium sulfite solution for 2 minutes to obtain a composite semipermeable membrane.

[0120] (Example 4) A composite semipermeable membrane was obtained by the same procedure as in Comparative Example 1, except that the membrane was immersed in a 10% by mass aqueous solution of diethylene glycol at 25°C for 10 seconds before being washed with hot water at 85°C for 2 minutes. The amount of amine in the obtained membrane was 35 mg / m ２ Thereafter, the membrane was immersed in a 0.4 mass % aqueous sodium nitrite solution at 35° C. and pH 3 for 40 seconds, and then in a 0.1 mass % aqueous sodium sulfite solution for 2 minutes to obtain a composite semipermeable membrane.

[0121] (Example 5) A composite semipermeable membrane was obtained by the same procedure as in Comparative Example 1, except that the membrane was immersed in a 10% by mass aqueous solution of diethylene glycol diacetate at 25°C for 10 seconds before being washed with hot water at 85°C for 2 minutes. The amount of amine in the obtained membrane was 32 mg / m ２ Thereafter, the membrane was immersed in a 0.4 mass % aqueous sodium nitrite solution at 35° C. and pH 3 for 40 seconds, and then in a 0.1 mass % aqueous sodium sulfite solution for 2 minutes to obtain a composite semipermeable membrane.

[0122] (Example 6) A composite semipermeable membrane was obtained by the same procedure as in Comparative Example 1, except that the membrane was immersed for 10 seconds in a 70°C aqueous solution of pH 2 adjusted with sulfuric acid before being washed with 85°C hot water for 2 minutes. The amount of amine in the obtained membrane was 40 mg / m ２ Thereafter, the membrane was immersed in a 0.4 mass % aqueous sodium nitrite solution at 35° C. and pH 3 for 40 seconds, and then in a 0.1 mass % aqueous sodium sulfite solution for 2 minutes to obtain a composite semipermeable membrane.

[0123] (Example 7) A composite semipermeable membrane was obtained by the same procedure as in Comparative Example 1, except that the membrane was immersed in a 10% by mass aqueous solution of N-methylpyrrolidone at 25°C for 10 seconds before being washed with hot water at 85°C for 2 minutes. The amount of amine in the obtained membrane was 23 mg / m ２ Thereafter, the membrane was immersed in a 0.4 mass % aqueous sodium nitrite solution at 35° C. and pH 3 for 40 seconds, and then in a 0.1 mass % aqueous sodium sulfite solution for 2 minutes to obtain a composite semipermeable membrane.

[0124] (Example 8) A composite semipermeable membrane was obtained by the same procedure as in Example 1, except that the support membrane (porous support layer thickness: 30 μm) obtained in Reference Example 2 was used. The amount of amine in the obtained membrane was 33 mg / m ２ Thereafter, the membrane was immersed in a 0.4 mass % aqueous sodium nitrite solution at 35° C. and pH 3 for 40 seconds, and then in a 0.1 mass % aqueous sodium sulfite solution for 2 minutes to obtain a composite semipermeable membrane.

[0125] (Example 9) A composite semipermeable membrane was obtained by the same procedure as in Example 1, except that the support membrane obtained in Reference Example 3 (porous support layer thickness: 25 μm) was used. The amount of amine in the obtained membrane was 21 mg / m ２ Thereafter, the membrane was immersed in a 0.4 mass % aqueous sodium nitrite solution at 35° C. and pH 3 for 40 seconds, and then in a 0.1 mass % aqueous sodium sulfite solution for 2 minutes to obtain a composite semipermeable membrane.

[0126] (Example 10) The support membrane obtained in Reference Example 1 was immersed in an aqueous solution of 1.5 mass % m-PDA and 1.5 mass % ε-caprolactam, after which excess aqueous solution was removed, and then an n-decane solution in which TMC was dissolved to a concentration of 0.06 mass % was applied so that the surface of the porous support layer was completely wet. Next, in order to remove excess solution from the membrane, the membrane was vertically drained, and dried by blowing air at 25°C using a fan, and then washed with hot water at 85°C for 2 minutes. The amount of amine in the obtained membrane was 71 mg / m ２ Thereafter, the membrane was immersed in a 0.4 mass % aqueous sodium nitrite solution at 35°C and pH 3 for 40 seconds, and then immersed in hot water at 50°C for 2 minutes. Thereafter, the membrane was immersed in a 0.1 mass % aqueous sodium sulfite solution for 2 minutes to obtain a composite semipermeable membrane.

[0127] Example 11 A composite semipermeable membrane was obtained in the same manner as in Example 7, except that the concentration of the aqueous sodium nitrite solution was changed to 0.1% by mass.

[0128] The structures of the membranes obtained in Comparative Examples 1 to 9 and Examples 1 to 11 are shown in Table 1, and the performances thereof are shown in Table 2.

[0129]

[0130]

[0131] The separation functional layer contains an azo group, and the chromaticity is b ＊ The composite semipermeable membranes of Examples 1 to 11, in which γ / δ was 0 or more and 20 or less, were characterized by both high initial performance and extremely small performance degradation after composite degradation. －２ 9.5 x 10 －２ The composite semipermeable membranes described below exhibited a more remarkable effect of suppressing performance degradation due to the combined deterioration test.

[0132] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2023-050190) filed on March 27, 2023, the entire contents of which are incorporated by reference.

[0133] The composite semipermeable membrane of the present invention can be suitably used, for example, as a membrane used in a water treatment facility for desalination of seawater or brackish water.

Claims

1. A composite semipermeable membrane comprising a support membrane and a separation functional layer containing a crosslinked polyamide located on the support membrane, the separation functional layer containing an azo group, The chromaticity b when measured from the surface of the composite semipermeable membrane on the separating functional layer side ＊ A composite semipermeable membrane, wherein the molecular weight is 0 or more and 20 or less.

2. 0.27 g / cm ２ The composite semipermeable membrane according to claim 1, wherein the composite semipermeable membrane has an absorbance at 435 nm of 0 to 0.10 after immersing the composite semipermeable membrane in an amount of ethanol of 0 to 0.10 at 25°C for 19 hours.

3. 0.27 g / cm ２ The composite semipermeable membrane according to claim 1 or 2, wherein the composite semipermeable membrane has an absorbance at 370 nm of 0 to 0.20 after immersing the composite semipermeable membrane in an amount of ethanol of 0 to 0.20 at 25° C. for 19 hours.

4. 3. The composite semipermeable membrane according to claim 1, wherein the zeta potential of the surface of the separation functional layer is in the range of -70 mV to -35 mV in a 10 mM NaCl aqueous solution at pH 7.

5. 3. The composite semipermeable membrane according to claim 1, wherein the zeta potential of the surface of the separation functional layer is in the range of -45 mV or more and -15 mV or less in a 10 mM NaCl aqueous solution at pH 3.

6. 3. The composite semipermeable membrane according to claim 1, wherein the amount A of terminal amino groups, the amount B of terminal carboxy groups and the amount C of amide groups of the crosslinked polyamide satisfy C / (A+B) ≥ 1.

0.

7. 3. The composite semipermeable membrane according to claim 1, wherein the support membrane has a substrate and a porous support layer, and the thickness of the porous support layer is 20 μm or more and 31 μm or less.

8. When the surface of the separation functional layer was analyzed by time-of-flight secondary ion mass spectrometry, ６ H ５ NO － The secondary ion intensity γ of the fragment peak derived from C ６ H ３ － The ratio γ / δ of the secondary ion intensity δ of the fragment peak derived from －２ Above 9.5 x 10 －２ 3. The composite semipermeable membrane according to claim 1 or 2, wherein:

9. A method for producing a composite semipermeable membrane comprising a support membrane and a separation functional layer provided on the support membrane, The step of forming the separation functional layer comprises: (a) carrying out an interfacial polycondensation reaction on the support film using a solution containing a polyfunctional amine and a solution containing a polyfunctional acid halide to form a laminate of the support film and a polyamide-containing layer; (b) a step (b1) of contacting the polyamide-containing layer with an aqueous solution containing at least one compound selected from the group consisting of alcohols, ethers, amides, inorganic acids, and organic acids, and a step (b2) of washing the laminate with hot water after the step (b1), wherein the amount of the polyfunctional amine contained in the laminate is 10 mg / m ２ 80mg / m or more ２ The steps of: (c) contacting the polyamide-containing layer with a compound (I) that reacts with primary amino groups to form a diazonium salt or a derivative thereof; (d) after step (c), contacting the polyamide-containing layer with a water-soluble compound (II) reactive with compound (I) to form an azo group; A method for producing a composite semipermeable membrane, comprising:

10. The method for producing a composite semipermeable membrane according to claim 9, wherein the polyfunctional amine is m-phenylenediamine.

11. The method for producing a composite semipermeable membrane according to claim 9, wherein the water-soluble compound (II) is sodium hydrogen sulfite or a sulfite ion.

12. A water treatment method comprising a reverse osmosis step of filtering raw water using the composite semipermeable membrane according to claim 1 or 2.

13. A composite semipermeable membrane element comprising the composite semipermeable membrane according to claim 1 or 2.

14. A composite semipermeable membrane module comprising the composite semipermeable membrane element according to claim 13.