Selective permeable membrane manufacturing method and water treatment method

Abstract

To suppress decrease in permeation flux due to a membrane contaminant such as protein and so on in a selective permeable membrane in which a dense layer is formed by an interfacial polymerization method.SOLUTION: A selective permeable membrane manufacturing method having a process for forming a dense layer on a support membrane by interfacial polymerization of a polyfunctional amine monomer and a polyfunctional acid halide monomer, has a membrane modification process in which an acid halide group of an unreacted polyfunctional acid halide monomer and an acrylic acid ester monomer or a methacrylic acid ester monomer are reacted. A water treatment method uses the selective permeable membrane manufactured by this selective permeable membrane manufacturing method.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for producing a selectively permeable membrane and a water treatment method using the selectively permeable membrane. [Background technology]

[0002] Reverse osmosis (RO) membranes and nanofiltration (NF) membranes are widely used as selectively permeable membranes in fields such as desalination of seawater and brackish water, production of industrial water and ultrapure water, and wastewater recovery. RO membrane treatment and NF membrane treatment have the advantage of being able to highly remove ions and low-molecular-weight organic matter, but they have the problem of a decrease in permeation flux over time due to the adsorption of membrane foulants contained in the treated water, such as nonionic surfactants, polysaccharides, proteins, and humic substances.

[0003] The mainstream method for manufacturing RO and NF membranes is to form a dense layer by interfacially polymerizing a polyfunctional amine monomer and a polyfunctional acid chloride monomer on a porous substrate. Because the reaction between the amine and the acid chloride forms an amide bond, the selectively permeable membrane manufactured in this manner is called a polyamide membrane. Because an extremely dense and thin separation layer is formed by interfacially polymerizing a polyfunctional amine monomer and a polyfunctional acid chloride monomer, this method is the most commonly used membrane manufacturing method for manufacturing NF and RO membranes.

[0004] Various attempts have been made to improve the fouling resistance of polyamide membranes. For example, methods proposed for introducing hydroxyl groups such as polyvinyl alcohol onto the surface of the dense layer of a polyamide membrane include a method for hydrophilizing the surface of an aromatic polysulfone porous membrane by uniformly adhering a water-insolubilized polyvinyl alcohol polymer to the surface (Patent Document 1), a method for coating the surface of the dense layer with an ethylene-vinyl alcohol copolymer layer (Patent Document 2), and a method for applying polyvinyl alcohol, which is insoluble in water at 25°C but soluble in water at 80°C, to the surface of an aromatic polyamide membrane (Patent Document 3). However, these methods have a problem in terms of the long-term stability of the coating layer.

[0005] To improve contamination resistance, a method has been proposed in which a covalent bond is formed by reacting a compound having at least one functional group reactive with the acid halide remaining after interfacial polymerization (Patent Document 4). Here, the water-soluble compound having at least one reactive group reactive with the acid halide is an aliphatic, aromatic, or heterocyclic compound. Any compound that is substantially soluble in water and reacts with the acid halide group to form a covalent bond is acceptable. Examples include polyethyleneimine, 2-ethanolamine, N-(3-aminopropyl)morpholine, and N,N-dimethyl-p-phenylenediamine. Of these, polyethyleneimine has been shown to produce a small decrease in permeation flux. However, polyethyleneimine is likely to result in a positively charged surface, making it unlikely to be effective against proteins or humic substances. Patent Document 4 uses amide or ester bonds as covalent bonds, which differs from the present invention, which generates carbonyl (ketone) bonds, as described below.

[0006] On the other hand, biocompatible polymers have been developed as materials that suppress the adsorption of proteins in vivo, and it has been reported that their application to selectively permeable membranes can suppress membrane fouling. Examples of such polymers that have been investigated as membrane modification materials include 2-methacryloyloxyethyl phosphorylcholine, a phosphobetaine-type zwitterionic monomer (Patent Document 5), N,N-dimethyl-γ-aminobutyric acid, a carboxybetaine-type zwitterionic monomer (Non-Patent Document 1), and [(2-methacryloyloxy)ethyl]dimethyl[3-sulfopropyl]ammonium hydroxide, a sulfobetaine-type zwitterionic monomer (Non-Patent Document 2). Biocompatible polymers that are not zwitterionic monomers include acrylic acid ester monomers and methacrylic acid ester monomers. Acrylic acid ester monomers include 2-methoxyethyl acrylate (MEA), and methacrylic acid ester monomers include 2-hydroxyethyl methacrylate (HEMA). MEA and HEMA are known to have a slower adsorption rate for albumin, a protein, than polypropylene (PP). MEA, in particular, is known to have a fast desorption rate and to be easily released (Non-Patent Document 2).

[0007] Patent Document 6 is an example of applying MEA to RO. The method described in Patent Document 6 involves forming a polyamide RO membrane and then introducing an MEA through a three-stage reaction. Although this method provides anti-fouling effects, it requires many steps and is a complicated manufacturing method. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 8-52333 [Patent Document 2] Japanese Patent Application Publication No. 4-330924 [Patent Document 3] International Publication No. 1997 / 034686 [Patent Document 4] Japanese Patent Application Laid-Open No. 2002-224546 [Patent Document 5] Japanese Patent Application Laid-Open No. 2012-55870 [Patent Document 6] Japanese Patent Application Publication No. 2023-118440 [Non-patent literature]

[0009] [Non-Patent Document 1] Matsuno et al., Membrane, 35, 86-92 (2010) [Non-patent document 2] Masaru Tanaka et al., Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 203, Issues 1-3, 25 April 2002, Pages 195-204 Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present invention is to provide a simpler and more effective technique for suppressing a decrease in permeation flux due to membrane fouling substances such as proteins in a selectively permeable membrane having a dense layer formed by interfacial polymerization. [Means for solving the problem]

[0011] The present inventors have conducted extensive research to solve the above-mentioned problems, and have found that membrane modification can be carried out simply and effectively without going through the many steps described in Patent Document 6 by forming a dense layer through interfacial polymerization of a polyfunctional amine monomer and a polyfunctional acid halide monomer, and then reacting the acid halide groups derived from the unreacted polyfunctional acid halide monomer with an acrylic acid ester monomer or a methacrylic acid ester monomer, thereby improving the fouling resistance of the selectively permeable membrane and suppressing a decrease in permeation flux. That is, the present invention is summarized as follows.

[0012] [1] A method for producing a selectively permeable membrane, which includes a step of forming a dense layer on a support membrane by interfacially polymerizing a polyfunctional amine monomer and a polyfunctional acid halide monomer, and further includes a membrane modification step of reacting an acid halide group of the unreacted polyfunctional acid halide monomer with an acrylic acid ester monomer or a methacrylic acid ester monomer.

[0013] [2] The method for producing a selectively permeable membrane according to [1], wherein the membrane modifying step is carried out using a membrane modifying solution containing 0.1 to 1.0% by weight of an acrylic acid ester monomer or a methacrylic acid ester monomer.

[0014] [3] The method for producing a selectively permeable membrane according to [1] or [2], wherein the support membrane is washed with an acid and / or an alkali after the membrane modification step.

[0015] [4] The method for producing a selectively permeable membrane according to any one of [1] to [3], wherein after the interfacial polymerization, the support membrane is washed with an organic solvent, and then the membrane modification step is carried out.

[0016] [5] The method for producing a selectively permeable membrane according to any one of [1] to [4], wherein the support membrane is washed with an organic solvent after the membrane modification step.

[0017] [6] The method for producing a selectively permeable membrane according to any one of [1] to [5], wherein the acrylic acid ester monomer or methacrylic acid ester monomer is 2-methoxyethyl acrylate.

[0018] [7] The method for producing a selectively permeable membrane according to any one of [1] to [6], wherein the selectively permeable membrane has an IR peak ratio calculated from the following (Equation 1) of 0.09[-] or more. IR peak ratio [-] = (1725 cm -1 Absorbance at -1800cm -1 absorbance) / (1670cm -1 Absorbance at -1800cm -1 absorbance) ... (Equation 1)

[0019] [8] The method for producing a selectively permeable membrane according to any one of [1] to [7], wherein the selectively permeable membrane has an XPS bond ratio 1 calculated from the following (Equation 2) of 0.17[-] or more. XPS bond ratio 1 [-] = (O-C=O ratio [%] in the C1s peak) / (N-C=O ratio [%] in the C1s peak) ... (Equation 2)

[0020] [9] A water treatment method using a selectively permeable membrane obtained by the method for producing a selectively permeable membrane according to any one of [1] to [8]. [Effects of the Invention]

[0021] According to the present invention, by modifying the surface of a dense layer formed by interfacial polymerization of a polyfunctional amine monomer and a polyfunctional acid halide monomer with an acrylic acid ester monomer or a methacrylic acid ester monomer, it is possible to prevent the adsorption of membrane foulants such as proteins, suppress the decrease in permeation flux of the selectively permeable membrane caused by these membrane foulants, reduce the frequency of membrane cleaning, and improve performance recovery through membrane cleaning, thereby enabling stable and efficient water treatment over a long period of time.

[0022] Claim 2 of the aforementioned Patent Document 6 states, "A method for producing the permselective membrane of claim 1, wherein the modification with 2-methoxyethyl acrylate is carried out via modification with 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, or a derivative thereof, followed by modification with 2-bromoisobutyryl bromide." That is, in Patent Document 6, the formed polyamide membrane is modified with 2-methoxyethyl acrylate (MEA), and in order to make the polyamide membrane more susceptible to modification, it is necessary to carry out "modification with 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, or a derivative thereof," followed by "modification with 2-bromoisobutyryl bromide." For this reason, in Patent Document 6, modification with MEA is carried out after two pre-modifications. As a result, the time and chemicals required for the three-step modification reaction are problematic.

[0023] In the present invention, modification with an acrylic acid ester monomer or a methacrylic acid ester monomer such as MEA is carried out during the formation of a polyamide membrane, thereby eliminating the need for two pre-modifications as in Patent Document 6, and enabling the production of a contamination-resistant polyamide membrane through a simpler reaction procedure. Furthermore, according to the present invention, it is possible to carry out membrane modification not only with MEA but also with acrylic acid ester monomers or methacrylic acid ester monomers other than MEA.

[0024] According to the present invention, by making the membrane modification reaction a one-step reaction, the time and chemicals required for membrane modification can be significantly reduced. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 2 is a perspective view showing a fixing frame used in the production of selectively permeable membranes in Examples and Comparative Examples. [Figure 2] 1 is a graph showing the IR peak ratio (1725 / 1670) of each polyamide membrane produced in the Examples and Comparative Examples. [Figure 3] FIG. 1 is a diagram showing the configuration of a flat membrane testing device used in Examples and Comparative Examples. [Figure 4] 1 is a graph showing the results of evaluation of basic performance of polyamide membranes produced in Examples 1-1 and 1-2 and Comparative Example 1. [Figure 5] 1 is a graph showing the results of anti-fouling tests on the polyamide membranes produced in Examples 1-1 and 1-2 and Comparative Example 1. [Figure 6] 1 is a graph showing the results of evaluation of basic performance of polyamide membranes produced in Examples 2-1, 2-2, and 2-3 and Comparative Example 2. [Figure 7] 1 is a graph showing the results of anti-fouling tests on the polyamide membranes produced in Examples 2-1, 2-2, and 2-3 and Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0026] The present invention will be described in detail below.

[0027] [Method for producing selectively permeable membrane] The method for producing a selectively permeable membrane of the present invention is a method for producing a selectively permeable membrane (hereinafter sometimes referred to as a "polyamide membrane") which includes a step of forming a dense layer on a support membrane by interfacially polymerizing a polyfunctional amine monomer and a polyfunctional acid halide monomer, and is characterized by further including a membrane modification step of reacting an acid halide group of the unreacted polyfunctional acid halide monomer with an acrylic acid ester monomer or a methacrylic acid ester monomer (hereinafter sometimes referred to as a "(meth)acrylic acid ester monomer"). In the present invention, the (meth)acrylic acid ester monomer is not limited to an acrylic acid ester monomer or a methacrylic acid ester monomer, and these may be used in combination.

[0028] [mechanism] As mentioned above, polyamide membranes can be obtained by interfacially polymerizing polyfunctional amine monomers and polyfunctional acid halide monomers on a porous support. The layer produced by this interfacial polymerization is a very dense and thin separation layer, making it the most commonly used membrane production method for NF and RO membranes. By incorporating a (meth)acrylic acid ester monomer into a dense layer formed by interfacial polymerization of a polyfunctional amine monomer and a polyfunctional acid halide monomer, a decrease in permeation flux due to adsorption of membrane fouling substances such as proteins can be suppressed. In the present invention, during the formation of the dense layer by interfacial polymerization, unreacted acid halide groups derived from the remaining unreacted polyfunctional acid halide monomer are directly reacted with the (meth)acrylic acid ester monomer, making it possible to eliminate the need for pre-membrane modification as in Patent Document 6. This mechanism is thought to be as follows.

[0029] For example, when interfacial polymerization is carried out using 1,3-phenylenediamine (MPD) as a typical polyfunctional amine monomer and 1,3,5-benzenetricarbonyl chloride (TMC) as a typical polyfunctional acid halide monomer, the reaction proceeds according to the following reaction formula I. As shown in Reaction Scheme I below, the acid chloride groups of TMC remaining after the interfacial polymerization with MPD are converted to carboxyl groups when they come into contact with water in the reaction system, resulting in the formation of an MPD-TMC polymer with some carboxyl groups rather than amide bonds.

[0030] [ka]

[0031] In Patent Document 6, an existing polyamide membrane on which a dense layer was formed by such an interfacial polymerization reaction was modified with 2-methoxyethyl acrylate (MEA). Therefore, prior to the membrane modification with MEA, a two-step pre-membrane modification was required: modification with 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, or a derivative thereof, and modification with 2-bromoisobutyryl bromide, in order to introduce reactive groups into the MPD-TMC polymer.

[0032] In the present invention, a (meth)acrylic acid ester monomer such as MEA is reacted with an MPD-TMC polymer while the acid chloride group (-C(=O)-Cl) remains, thereby directly reacting the acid chloride group of the MPD-TMC polymer with MEA, as shown in Reaction Formula II below, to perform membrane modification. This eliminates the need for a pre-reaction step for MEA membrane modification as in Patent Document 6. During this reaction process, the (meth)acrylic acid ester monomer such as MEA undergoes atom transfer radical polymerization using the unreacted acid chloride of the MPD-TMC polymer as an initiator, resulting in a structure in which the (meth)acrylic acid ester polymer is bonded to the MPD-TMC polymer.

[0033] [ka]

[0034] In the above reaction scheme II, R 1represents H2C=CH- (in the case of an acrylate ester monomer) or H2C=C(CH3)- (in the case of a methacrylate ester monomer). 2 is an ester group of a (meth)acrylic acid ester monomer, and for example, in the case of MEA, it represents -(CH2)2-OCH3, and in the case of 2-hydroxyethyl methacrylate (HEMA), it represents -(CH2)2-OH. R 3 represents the polymer body portion other than the carboxyl groups of the MPD-TMC polymer shown in Reaction Formula I above. R 1’ is a repeating unit formed by polymerization of a (meth)acrylic acid ester monomer, and represents, for example, —H2C—CH— (in the case of an acrylic acid ester monomer) or —H2C—C(CH3)— (in the case of a methacrylic acid ester monomer).

[0035] [Method for manufacturing selectively permeable membranes] The specific manufacturing procedure of the method for manufacturing a selectively permeable membrane of the present invention involves sequentially carrying out an interfacial polymerization step and a membrane modification step. However, a washing step with an organic solvent may be included between the interfacial polymerization step and the membrane modification step, and a post-treatment step including a washing step with an organic solvent and a washing step with an acid and / or alkali may be included after the membrane modification step. Furthermore, each step may include a drying step as appropriate. The materials used and the processing conditions for each step will be described below.

[0036] <Support membrane> In the present invention, the support membrane that forms the dense layer is a layer that does not substantially have separation performance and is used to impart strength to the dense layer (separation functional layer) that substantially has separation performance. The support membrane used in the present invention can be an ultrafiltration membrane made of polysulfone, and one example is "CF-30" manufactured by Nitto Denko Corporation. This membrane has polysulfone applied to a nonwoven fabric, and the total thickness of the nonwoven fabric and polysulfone layer is 150 μm. Furthermore, ultrafiltration membranes other than polysulfone can also be used as support membranes as long as they can impart strength to the dense layer.

[0037] The support membrane is preferably a porous support having a structure with uniformly sized micropores from one side to the other, or an asymmetric structure with dense micropores on one side and pores whose pore size gradually increases from that side to the other, with the micropore size being 100 nm or less. The thickness of the support membrane is preferably 10 μm or more from the viewpoint of strength, and several hundred μm or less, for example, 200 μm or less, from the viewpoint of ease of handling and module processing.

[0038] The support membrane may be made of a homopolymer or copolymer such as polysulfone, cellulose acetate, cellulose nitrate, polyvinyl chloride, polyacrylonitrile, polyphenylene sulfide, or polyphenylene sulfide sulfone, either alone or in combination. Among these materials, polysulfone is preferred because of its high chemical, mechanical, and thermal stability and ease of molding.

[0039] <Interfacial polymerization process> (Polyfunctional amine monomer) The polyfunctional amine monomer used in the interfacial polymerization may be any aliphatic or aromatic compound having two or more amino groups. Generally, aromatic amines such as 1,3-phenylenediamine (m-phenylenediamine (MPD)), p-phenylenediamine, 1,3,5-triaminobenzene, paraxylylenediamine, and diaminopyridine, and aliphatic amines such as ethylenediamine, propylenediamine, dimethylethylenediamine, piperazine, and aminomethylpiperidine are used. Among these, aromatic amines, particularly 1,3-phenylenediamine (MPD), p-phenylenediamine, and 1,3,5-triaminobenzene, are preferred in terms of reactivity and the performance of the resulting membrane. These polyfunctional amine compounds can be used alone or in combination.

[0040] (Polyfunctional acid halide monomer) Examples of polyfunctional acid halide monomers that can be used include aromatic acid halides such as trimesic acid halide (1,3,5-benzenetricarbonyl trihalide), benzophenonetetracarboxylic acid halide, trimellitic acid halide, pyromellitic acid halide, isophthalic acid halide, terephthalic acid halide, naphthalenedicarboxylic acid halide, diphenyldicarboxylic acid halide, pyridinedicarboxylic acid halide, benzenedisulfonic acid halide, and chlorosulfonylisophthalic acid halide. Aliphatic acid halides such as cyclohexanetricarboxylic acid halide and cyclohexanedicarboxylic acid halide can also be used. Among these, isophthalic acid chloride, terephthalic acid chloride, trimesic acid chloride (1,3,5-benzenetricarbonyl trichloride (TMC)), and mixtures thereof are preferred, considering solubility in membrane-forming solvents and the properties of the resulting permselective membrane.

[0041] (interfacial polymerization) The interfacial polymerization of the polyfunctional amine monomer and the polyfunctional acid halide monomer can be carried out by a conventional method. That is, the support membrane is successively contacted with an aqueous solution of a polyfunctional amine monomer and a solution of a polyfunctional acid halide monomer to cause an in-situ interfacial polycondensation reaction, thereby forming a polyamide dense layer having substantial separation performance.

[0042] The polyfunctional amine monomer concentration of the polyfunctional amine monomer aqueous solution is preferably in the range of 0.1 to 20% by weight, more preferably in the range of 0.5 to 15% by weight. If the polyfunctional amine monomer concentration is less than 0.1% by weight, the progress of the interfacial polycondensation reaction slows down, and if it exceeds 20% by weight, the film thickness of the dense layer increases and water permeability tends to decrease. In addition to the polyfunctional amine monomer, the polyfunctional amine monomer aqueous solution may contain 0.01 to 10 wt % of an alcohol such as 2-propanol or butanol to improve diffusibility during interfacial polymerization, and 0.01 to 5 wt % of a surfactant such as sodium dodecyl sulfate or sodium dodecylbenzenesulfonate to improve adhesion between the dense layer and the support film after interfacial polymerization.

[0043] The solvent for dissolving the polyfunctional acid halide monomer may be any solvent that is immiscible with water, dissolves the polyfunctional acid halide monomer, does not destroy the support film, and can form a crosslinked polymer by interfacial polycondensation. Examples of the solvent include hydrocarbon compounds, cyclohexane, and 1,1,2-trichloro-1,2,2-trifluoroethane. In view of the reaction rate and solvent volatility, n-hexane, isooctane, heptane, octane, nonane, decane, undecane, dodecane, and 1,1,2-trichloro-1,2,2-trifluoroethane are preferred.

[0044] The concentration of the polyfunctional acid halide monomer in the polyfunctional acid halide monomer solution is preferably within the range of 0.01 to 1% by weight. If the concentration of the polyfunctional acid halide monomer is less than 0.01% by weight, the formation of the dense layer is likely to be insufficient. If the concentration exceeds 1% by weight, the concentration of carboxyl groups on the surface of the dense layer becomes high, which reduces water permeability when the raw water contains cationic organic substances (e.g., cationic surfactants) and increases costs. In addition to the polyfunctional acid halide monomer, the polyfunctional acid halide monomer solution may contain 0.01 to 10% by weight of alcohol such as 2-propanol or butanol to improve diffusibility during interfacial polymerization.

[0045] The contact time of the polyfunctional amine monomer aqueous solution with the support membrane is preferably about 5 to 120 seconds, and the contact time of the polyfunctional acid halide monomer solution is preferably about 10 to 180 seconds. In either case, if the contact time is too short, the surface of the support membrane will not be uniformly contacted, and if it is too long, it will be inefficient.

[0046] After the support membrane is successively brought into contact with the polyfunctional amine monomer aqueous solution and the polyfunctional acid halide monomer solution to carry out interfacial polymerization, the solution is appropriately drained and the next step is carried out.

[0047] <Cleaning process using organic solvent> After the interfacial polymerization step, a washing step with an organic solvent may be carried out prior to the next membrane modification step. The organic solvent used for washing can be the same as the organic solvent used for preparing the polyfunctional acid halide monomer solution. This washing is not limited to one time, and may be carried out about two to five times. By carrying out such a washing step using an organic solvent, unreacted monomers and reaction residues in the dense layer can be removed.

[0048] Prior to this washing step with an organic solvent, a drying step may be carried out in which the support film after interfacial polymerization is dried at about 60 to 150° C. for about 10 to 600 seconds. By carrying out a washing step with an organic solvent after such a drying step, unreacted monomers and reaction residues in the dense layer can be removed.

[0049] <Membrane modification process> ((Meth)acrylic acid ester monomer) Examples of (meth)acrylic acid ester monomers that can be used in the membrane modification step include acrylic acid ester monomers such as 2-methoxyethyl acrylate (MEA), 2-hydroxyethyl acrylate (HEA), and 2-ethyl acrylate (EA), and methacrylic acid ester monomers such as 2-methoxyethyl methacrylate (MEMA), and 2-hydroxyethyl methacrylate (HEMA). These (meth)acrylic acid ester monomers may be used alone or in combination of two or more. Of these, it is preferable to use 2-methoxyethyl acrylate (MEA) or 2-hydroxyethyl methacrylate (HEMA), and it is particularly preferable to use MEA, because they are less likely to adsorb proteins and have excellent desorption properties.

[0050] (Membrane modification solution) Although not particularly limited, membrane modification with a (meth)acrylic acid ester monomer is preferably carried out by preparing a membrane modification solution containing a (meth)acrylic acid ester monomer and using this membrane modification solution.

[0051] Membrane modification with (meth)acrylate monomers is carried out by atom transfer radical polymerization using the acid halide groups derived from unreacted polyfunctional acid halide monomers as initiators. Therefore, the membrane modification solution is prepared using not only the (meth)acrylate monomers, but also ligands such as tris(2-pyridylmethyl)amine (TPMA) or tris[2-(dimethylamino)ethyl]amine, catalysts such as copper(II) bromide or copper(II) chloride, reducing agents such as ascorbic acid, organic solvents such as methanol, ethanol, or N,N-dimethylformamide to dissolve the (meth)acrylate monomers, and water to dissolve the ligands, catalyst, and reducing agent.

[0052] The concentration of the (meth)acrylic acid ester monomer in the membrane modification solution is preferably 0.1 to 10% by weight, particularly 0.1 to 1.0% by weight. If the (meth)acrylic acid ester monomer is less than this concentration, membrane modification does not proceed smoothly, and if it is more, excessive polymerization occurs.

[0053] The ligand concentration, catalyst concentration, and reducing agent concentration in the membrane modification solution vary depending on the type of ligand, catalyst, and reducing agent used, as well as the concentration of the (meth)acrylic acid ester monomer. Generally, however, the ligand concentration is 0.01 to 1.0 wt %, the catalyst concentration is 0.01 to 1.0 wt %, and the reducing agent concentration is 0.01 to 1.0 wt %, and it is preferable to use the ligand in an amount of 0.1 to 10 times the catalyst, and the reducing agent in an amount of 0.1 to 10 times the catalyst. In either case, if the concentration is too low, the membrane modification reaction does not proceed smoothly, and if it is too high, excessive polymerization occurs.

[0054] The concentration of the organic solvent in the membrane modifying solution may be at a level that can dissolve the (meth)acrylic acid ester monomer in the membrane modifying solution, and although it varies depending on the type of organic solvent used and the concentration of the (meth)acrylic acid ester monomer in the membrane modifying solution, it is usually about 10 to 80% by weight.

[0055] The water concentration in the membrane modifying solution may be at a level that can dissolve the ligand, catalyst, and reducing agent in the membrane modifying solution, and is usually about 10 to 80% by weight, although this varies depending on the concentrations of these in the membrane modifying solution.

[0056] (membrane modification) The membrane modification step can be carried out by bringing the membrane modification solution prepared as described above into contact with a support membrane on which a dense layer has been formed after interfacial polymerization, or with a support membrane that has subsequently been washed with an organic solvent. Specifically, the support membrane on which the dense layer has been formed is contacted with the membrane modifying solution for approximately 10 to 600 seconds, and then the membrane modifying solution is removed, followed by drying at 60 to 150°C for approximately 10 to 600 seconds, and optionally further drying at room temperature (15 to 35°C) for approximately 1 to 24 hours.

[0057] In the present invention, in the membrane modification step, it is preferable to take measures such as those described below in order to react the acid halide groups derived from the unreacted polyfunctional acid halide monomers remaining after the interfacial polymerization with the (meth)acrylic acid ester monomers before they are converted into carboxyl groups. The contact time of the membrane modification solution with the dense layer after interfacial polymerization is preferably about 10 to 600 seconds. If the contact time is short, the dense layer will not be sufficiently modified with (meth)acrylic acid ester monomers, and contamination resistance will not be achieved. If the contact time is long, the modification will be excessive, resulting in a significant decrease in basic performance. Furthermore, it is preferable to carry out a washing step using a solvent before film modification. By carrying out the washing step, reaction residues that react with the (meth)acrylic acid ester monomer can be removed. In this case, washing with water or the like may convert the acid halide groups derived from the remaining unreacted polyfunctional acid halide monomers into carboxyl groups, so it is preferable to use an organic solvent or the like.

[0058] <Post-processing process> After the membrane modification step, post-treatment steps such as a washing step of washing with an organic solvent, followed by a washing step of washing with water, and further a washing step of washing with an acid and / or alkali can be carried out.

[0059] As the organic solvent used for washing with an organic solvent in the post-treatment step, one or more of methanol, ethanol, N,N-dimethylformamide, etc. can be used. This washing may be carried out using an aqueous organic solvent solution containing about 10 to 80% by weight of a water-soluble organic solvent such as methanol, ethanol, N,N-dimethylformamide, etc. Moreover, this washing may be carried out not only once but about 2 to 5 times. By performing such washing with an organic solvent, unreacted monomers and reaction residues can be removed.

[0060] The water washing after washing with an organic solvent is appropriately carried out to remove the organic solvent remaining after washing with the organic solvent.

[0061] Washing with an acid and / or an alkali may be carried out before or after washing with an organic solvent, but is usually carried out after washing with an organic solvent. For acid washing, an acid aqueous solution such as citric acid or hydrochloric acid with a pH of about 1 to 4 is used. For alkali washing, an alkali aqueous solution such as sodium hydroxide with a pH of about 11 to 14 is used. A surfactant such as sodium dodecyl sulfate may be mixed in this acid and / or alkali aqueous solution at about 0.01 to 1.0% by weight. When both acid washing and alkali washing are carried out, there is no particular limitation on the order, but usually alkali washing is carried out after acid washing. This acid and / or alkali washing is usually carried out by immersion washing. After this acid and / or alkali washing, it is preferable to further carry out washing with water.

[0062] [(Amount of (meth)acrylate monomer introduced)] The selectivity permeation membrane produced by the production method of the selectivity permeation membrane of the present invention (hereinafter, may be referred to as "the selectivity permeation membrane of the present invention") preferably shows the following values when analyzed by the following analysis methods.

[0063] <IR peak ratio (1725 / 1670)> The selective permeation membrane of the present invention is analyzed by the method described in the section of the examples given below, and it is preferable that the IR peak ratio calculated by the following (Formula 1) (hereinafter, may be referred to as "IR peak ratio (1725 / 1670)") is 0.09 [-] or more. IR peak ratio [-] = (absorbance at 1725 cm -1 - absorbance at 1800 cm -1 ) / (absorbance at 1670 cm -1 - absorbance at 1800 cm -1 )... (Formula 1) In FT-IR, the peak at 1725 cm -1 represents the absorption of the double bond between the carbon atom and the oxygen atom constituting the ester bond, and the peak at 1670 cm -1 represents the absorption of the double bond of the amide bond. The above (Formula 1) evaluates the ratio of the ester bond sites of the (meth)acrylate monomer to the polyamide membrane which is the base. If the IR peak ratio (1725 / 1670) is 0.09 [-] or more, it is judged that a sufficient amount of the (meth)acrylate monomer is introduced into the dense layer, and the film modification effect and the effect of improving the antifouling property by film modification are high. The higher this value is, the more preferable it is because the introduction amount of the (meth)acrylate monomer is large. On the other hand, since the introduction of the (meth)acrylate monomer causes a decrease in the permeation flux, it is preferably about 0.09 to 0.10 [-]. The IR peak ratio (1725 / 1670) can be controlled according to the purpose by adjusting the weight concentration, contact time, etc. in the film modification process.

[0064] <XPS binding ratio> The selective permeation membrane of the present invention is analyzed by the method described in the section of the examples given below, and it is preferable that the XPS binding ratio calculated by the following (Formula 2) is 0.17 [-] or more. Alternatively, it is preferable that the XPS binding ratio calculated by the following formula (Formula 3) is 2.6 [-] or more. XPS binding ratio [-] = (ratio of O-C=O [%] in the C1s peak) / (ratio of N-C=O [%] in the 1s peak)... (Formula 2) XPS bond ratio 2 [-] = (Ratio of CO and CN in the C1s peak [%]) / (Ratio of NC=O in the C1s peak [%]) ... (Equation 3) In XPS analysis, CO,CN represent the CN bond of the polyamide film and the CO bond of the (meth)acrylic acid ester monomer, NC=O represents the amide bond of the polyamide film, and OC=O represents the ester bond of the carboxyl group of the polyamide film and the (meth)acrylic acid ester monomer. Therefore, OC=O / NC=O, which is the XPS bond ratio 1 calculated using the above formula (2), and CO,CN / NC=O, which is the XPS bond ratio 2 calculated using the above formula (3), evaluate the ratio of the (meth)acrylic acid ester monomer to the base polyamide film. If the XPS bond ratio 1 is 0.17[-] or more and the XPS bond ratio 2 is 2.6[-], it is judged that a sufficient amount of (meth)acrylic acid ester monomer has been introduced into the dense layer, and the membrane modification effect and the effect of improving contamination resistance due to membrane modification are high. The higher these values, the more (meth)acrylic acid ester monomer is introduced, which is preferable. However, on the other hand, the introduction of the (meth)acrylic acid ester monomer results in a decrease in the permeation flux. Therefore, it is preferable that the XPS bond ratio 1 is about 0.17 to 0.30 [-] and the XPS bond ratio 2 is about 2.6 to 4.0 [-]. Since XPS bond ratio 1 focuses on ester bonds, it serves as an index for determining the incorporation of (meth)acrylic acid ester monomers. On the other hand, XPS bond ratio 2 depends on the structure of the monomer, so the criteria are different for monomers other than (meth)acrylic acid ester monomers.

[0065] [Water treatment method] The water treatment method of the present invention is a method for performing water treatment using a selectively permeable membrane produced as described above, in which the surface of a dense layer formed by interfacial polymerization of a polyfunctional amine monomer and a polyfunctional acid halide monomer is modified with a (meth)acrylic acid ester monomer. Here, the selectively permeable membrane may be an RO membrane or an NF membrane.

[0066] There are no particular restrictions on the water to be treated that can be treated using the selectively permeable membrane of the present invention. However, the selectively permeable membrane produced by the present invention has excellent resistance to contamination, particularly against contaminants such as proteins, and is therefore effectively used to treat water with a protein concentration of 1 mg / L or more, for example, approximately 1 to 20 mg / L. Examples of such water to be treated include industrial wastewater and biologically treated sewage, but the water to be treated is not limited to these. [Example]

[0067] The present invention will be described in more detail below with reference to examples.

[0068] [Production of selectively permeable membrane] [Example 1-1] The selectively permeable membrane was prepared as follows.

[0069] <Materials used> 1. Support membrane As the support membrane, a UF membrane (CF30) manufactured by Nitto Denko was used.

[0070] 2. Reagents The reagents used are as follows:

[0071] <For interfacial polymerization> 1,3-Phenylenediamine (MPD): Tokyo Chemical Industry Co., Ltd. 1,3,5-Benzenetricarbonyl trichloride (TMC): Kishida Chemical Co., Ltd. 2,2,4-trimethylpentane (isooctane): Kishida Chemical Co., Ltd. 2-Propanol (IPA): Kishida Chemical Co., Ltd. 2-Methylheptane: Sankyo Chemical Co., Ltd. Sodium dodecyl sulfate (SDS): Fujifilm Wako Pure Chemical Industries, Ltd. Ethanol: Kishida Chemical

[0072] <For modification> Tris(2-pyridylmethyl)amine (TPMA): manufactured by Tokyo Chemical Industry Co., Ltd. Copper(II) bromide: Kishida Chemical Co., Ltd. Ascorbic acid: Kishida Chemical Co., Ltd. 2-Methoxyethyl acrylate (MEA): manufactured by Tokyo Chemical Industry Co., Ltd. 2-Hydroxyethyl methacrylate (HEMA): Tokyo Chemical Industry Co., Ltd. 2-Methoxyethyl methacrylate (MEMA): manufactured by Tokyo Chemical Industry Co., Ltd. Methanol: Kishida Chemical Co., Ltd.

[0073] <Selectively permeable membrane manufacturing method> The selectively permeable membrane was produced by the following procedure.

[0074] <Reagent preparation> (1) An aqueous amine solution was prepared with a ratio of 0.15 wt % SDS, 5.00 wt % IPA, 0.60 wt % MPD, and 92.85 wt % water. (2) The acid chloride solution was prepared with a ratio of IPA: 0.10 wt %, TMC: 0.20 wt %, and 2,2,4-trimethylpentane: 99.70 wt %. (3) The membrane modification solution was prepared with the following ratios: copper(II) bromide: 0.01 wt%, ascorbic acid: 0.19 wt%, TPMA: 0.03 wt%, MEA: 0.45 wt%, water: 55.49 wt%, and methanol: 43.83 wt%.

[0075] <Dense layer formation> (1) As shown in Figure 1, the support membrane 20 was sandwiched and fixed between PTFE fixing frames 21 and 22, and the amine aqueous solution was poured into the recess formed by the upper PTFE fixing frame 21 and the support membrane 20, thereby bringing the amine aqueous solution into contact with the support membrane 20. (2) After 60 seconds, the aqueous amine solution was drained through the notch 21A of the PTFE fixing frame 21 to remove excess aqueous amine solution. (3) After draining, the support membrane 20 was brought into contact with an acid chloride solution in the same manner as in (1) above. (4) After 60 seconds, the acid chloride solution was drained in the same manner as in (2) above to remove excess acid chloride solution. (5) After draining, the support film 20 was placed vertically together with the fixing frame, and the remaining solvent was evaporated by draining for 60 seconds.

[0076] <Membrane modification> (1) After the dense layer was formed, the membrane modifying solution was poured in and brought into contact with the support membrane 20 in the same manner as in (1) of the formation of the dense layer. (2) After 300 seconds, the membrane modifying solution was drained in the same manner as in (2) of the formation of the dense layer above, and excess membrane modifying solution was removed. (3) After draining, the support film 20 was placed vertically together with the fixing frame, and the remaining solution was evaporated by draining for 60 seconds. (4) Next, the support film 20 together with the fixing frame was placed vertically in a dryer set at 120° C. and left to stand for 120 seconds. (5) The support film 20 together with the fixing frame was taken out of the dryer and left to dry at room temperature for at least half a day.

[0077] <Post-processing> (1) After the membrane modification, excess chemicals were removed by washing with ethanol. (2) Then, the sample was immersed in running water for at least one hour.

[0078] [Example 1-2] A selectively permeable membrane was produced in the same manner as in Example 1-1, except that the following conditions were changed. The MEA concentration in the membrane modification solution was doubled to 0.9 wt%. - Changed the waiting time for (2) in membrane modification from 300 seconds to 60 seconds. After washing with running water, the membrane was post-treated by immersing it in a 2% by weight citric acid solution for 2 hours and then in a 0.15% by weight sodium hydroxide solution with a pH of 13 for 16 hours. Finally, it was washed with water to neutralize the pH of the membrane.

[0079] [Comparative Example 1] A permselective membrane was produced in the same manner as in Example 1-1, except that the steps (1) to (3) in the membrane modification were not carried out.

[0080] [Example 2-1] A selectively permeable membrane was produced in the same manner as in Example 1-1, except that the following conditions were changed. · 2,2,4-trimethylpentane was replaced with 2-methylheptane in the preparation of the acid chloride solution. The MEA concentration in the membrane modification solution was doubled to 0.9 wt%. The membrane was modified as follows: <Membrane modification> (1) After the dense layer was formed, the support film 20 together with the fixing frame was placed vertically in a dryer set at 120° C. and left to stand for 300 seconds. (2) The support membrane 20 was washed three times with 2-methylheptane. (3) The membrane modifying solution was poured into the support membrane 20 and brought into contact with the support membrane 20 . (4) After 300 seconds, the membrane modification solution was drained to remove excess membrane modification solution. (5) After draining, the support film 20 was placed vertically together with the fixing frame, and the remaining solution was evaporated by draining for 60 seconds. (6) The support membrane 20 was washed three times with a 50 wt % aqueous methanol solution.

[0081] [Example 2-2] A permselective membrane was produced in the same manner as in Example 2-1, except that the MEA in the membrane modifying solution was replaced with HEMA.

[0082] [Example 2-3] A permselective membrane was produced in the same manner as in Example 2-1, except that the MEA in the membrane modifying solution was replaced with MEMA.

[0083] Comparative Example 2 A permselective membrane was produced in the same manner as in Example 2-1, except that the steps (3) to (5) in the membrane modification were not carried out.

[0084] [Analysis of MEA introduction] [FT-IR] The introduction of MEA into the fabricated permselective membrane was confirmed by drying the fabricated membrane under reduced pressure for more than one day and then analyzing it with FT-IR (NicoletTM iN TM 10 MX Infrared Imaging Microscope, Thermo Scientific TM The measurement was performed using a FT-IR spectrometer (Fuji Electric Industries, Ltd., USA), and the IR peak ratio (1725 / 1670) was calculated using the following formula (1). IR peak ratio [-] = (1725 cm -1 Absorbance at -1800cm -1 absorbance) / (1670cm -1 Absorbance at -1800cm -1 absorbance) ... (Equation 1)

[0085] Figure 2 shows the IR peak ratio (1725 / 1670) of each film. 1725cm -1 The peak at 1670 cm is an ester bond. -1 The peak indicates the absorption of the double bond between the carbon atom and oxygen atom that constitutes the amide bond, and evaluates the ratio of ester bond sites in the MEA to the base polyamide membrane. As shown in FIG. 2, the respective values ​​are 0.06 [-] for Comparative Examples 1 and 2, 0.12 [-] for Example 1-1, 0.14 [-] for Example 1-2, and 0.09 [-] for Example 2-1. It can be seen that the unmodified membrane of the comparative example has a lower ratio of ester bond sites than the modified membrane of the example. From this, it can be said that the peak ratio at which the introduction of MEA is recognized is 0.09[-] or higher. Therefore, it can be said that the index for determining the introduction of (meth)acrylic acid ester monomers is 0.09[-] or more.

[0086] [XPS] The incorporation of MEA was confirmed by measuring the prepared membranes by XPS (PHI5000 VersaProbeII multifunctional scanning X-ray photoelectron spectroscopy, ULVAC-PHI Inc., Japan) after drying them in vacuum at 40 °C for 5 h. Table 1 shows the relationship between the waveform separation results of the C1s peaks of the membranes produced in Example 2-1 and Comparative Example 2 and the XPS bond ratio, when the C1s peak detected by XPS is set to 100%. CO,CN represents the CN bond of the polyamide membrane and the CO bond of the MEA, NC=O represents the amide bond of the polyamide membrane, and OC=O represents the ester bond of the carboxyl group of the polyamide membrane and the MEA. Therefore, the XPS bond ratio 1, OC=O / NC=O, calculated from the following (Equation 2), and the XPS bond ratio 2, CO,Cn / NC=O, calculated from the following (Equation 3), evaluate the ratio of the MEA to the base polyamide membrane. As shown in Table 1, the XPS bond ratio 1 of Comparative Example 2 is 0.14 [-] or less and the XPS bond ratio 2 is 2.3 [-] or less, while the XPS bond ratio 1 of Example 2-1 is 0.17 [-] or more and the XPS bond ratio 2 is 2.6 [-] or more. From this, it can be said that the introduction of MEA is recognized when XPS bond ratio 1 is 0.17[-] or higher or XPS bond ratio 2 is 2.6[-] or higher. In the case of XPS bond ratio 1, the focus is on ester bonds, so an XPS bond ratio of 1 of 0.17[-] or higher is used as an indicator for determining the introduction of acrylic acid ester monomers or methacrylic acid ester monomers. On the other hand, in the case of XPS bond ratio 2, it depends on the structure of the monomer, so the criteria are different for monomers other than MEA. XPS bond ratio 1 [-] = (O-C=O ratio [%] in the C1s peak) / (N-C=O ratio [%] in the C1s peak) ... (Equation 2) XPS bond ratio 2 [-] = (Ratio of CO and Cn in the C1s peak [%]) / (Ratio of N-C=O in the C1s peak [%]) ... (Equation 3)

[0087] [Table 1]

[0088] [Flat membrane test method] [Basic performance evaluation] Using the flat membrane testing device shown in Figure 3, the basic performance of the permselective membranes produced in each example was evaluated. In this test equipment, UF membrane feed water is supplied by a high-pressure pump 4 via pipe 11 to a raw water chamber 1A below a flat membrane cell 2 containing a UF membrane in a sealed vessel 1. As shown in Figure 3(b), the sealed vessel 1 is composed of a lower case 1a on the raw water chamber 1A side and an upper case 1b on the permeate chamber 1B side. A flat membrane cell 2 is fixed between the lower case 1a and the upper case 1b via an O-ring 8. The permeate side of the UF membrane 2A in the flat membrane cell 2 is supported by a porous support plate 2B. The raw water chamber 1A below the flat membrane cell 2 is agitated by rotating the agitator 5 with a stirrer 3. The UF membrane permeate passes through the permeate chamber 1B above the flat membrane cell 2 and is extracted via pipe 12. The concentrated water is extracted via pipe 13. The pressure inside the sealed vessel 1 is regulated by a pressure gauge 6 installed in the water supply pipe 11 and a pressure control valve 7 installed in the concentrated water extraction pipe 13.

[0089] The permselective membranes prepared in each example were set in this flat membrane testing device, and pure water was passed through to evaluate the pure water permeation flux. In addition, a 500 mg / L NaCl (Kishida Chemical Co., Ltd.) aqueous solution at pH 7 was passed through to evaluate the desalination performance. The inlet flow rate was set to 4.0 mL / min and the inlet pressure to 0.75 MPa while stirring at approximately 500 rpm in the flat membrane cell 2. The water temperature was set to 25°C. The corrected permeation flux was calculated from the obtained data by correcting for pressure and temperature using the following formulas (4) to (7), respectively. The effective area of ​​the membrane is 8cm 2 The reference pressure was set to 0.75 MPa. Permeation flux [m 3 / m 2 d] = permeated water volume / effective area ... (Equation 4) Pressure correction [-] = Reference pressure / Actual inlet pressure ... (Equation 5) Temperature correction at 25°C [-] = 1.024 ... (Equation 6) Corrected permeation flux [m 3 / m 2 d] = permeation flux × pressure correction × temperature correction ... (Equation 7) The results are shown in Figures 4 and 6.

[0090] [Anti-fouling test] Using the flat membrane testing device and flat membrane cell shown in Figure 3, a fouling resistance test was carried out on the permselective membranes produced in each example. The permeation flux was measured by passing a 1 mg / L aqueous solution of lysozyme (derived from chicken eggs, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) at pH 7 through the membrane. While stirring the membrane at approximately 500 rpm, the inlet flow rate was adjusted to 0.5 mL / min (for the selectively permeable membranes of Examples 1-1 and 1-2 and Comparative Example 1) or 0.7 mL / min (for the selectively permeable membranes of Examples 2-1, 2-2, and 2-3 and Comparative Example 2), and the pressure was adjusted to achieve a recovery rate of 80%. The water temperature was set to 25°C. The corrected permeation flux, corrected for pressure and temperature, was calculated from the obtained data using the above formulas (4) to (7), and the corrected permeation flux ratio was calculated using the following formula (8). Corrected flux ratio [-] = Corrected flux at each time / Initial corrected flux (Equation 8) The results are shown in Figures 5 and 7.

[0091] [Consideration] [Comparison of Examples 1-1 and 1-2 with Comparative Example 1] 5, in Comparative Example 1 at a flow rate of 0.5 mL / min, the decrease in permeation flux after 53 hours was 23%, in Example 1-1 the decrease in permeation flux after 54 hours was 14%, and in Example 1-2 the decrease in permeation flux after 96 hours was 7%. This shows that membrane fouling is suppressed in Examples 1-1 and 1-2 compared to Comparative Example 1. As described above, Example 1-2 has a higher fouling resistance due to the larger amount of MEA modification compared to Example 1-1, but it is believed that the permeation flux is significantly reduced as shown in FIG.

[0092] [Comparison of Examples 2-1, 2-2, and 2-3 with Comparative Example 2] 7, the decrease in permeation flux after 96 hours was 33% in Comparative Example 2, 20% in Example 2-1, 21% in Example 2-2, and 25% in Example 2-3. This shows that membrane fouling is suppressed in Examples 2-1, 2-2, and 2-3 compared to Comparative Example 2. The difference in fouling resistance between Example 2-1 and Comparative Example 2 is thought to be due to the same reasons as in Examples 1-1 and 1-2 and Comparative Example 1. Comparing Examples 2-1, 2-2, and 2-3, it is believed that the MEA of Example 2-1 has the best fouling resistance. [Explanation of symbols]

[0093] 1 container 2 Flat membrane cell 2A UF membrane 2B Porous support plate 3 Stirrer 4. High-pressure pump 5 Stirring bar 6. Pressure gauge 7 Pressure Regulating Valve 8 O-rings 20 Support membrane 21,22 Fixed frame

Claims

1. A method for producing a selectively permeable membrane, comprising a step of forming a dense layer on a support membrane by interfacially polymerizing a polyfunctional amine monomer and a polyfunctional acid halide monomer, The method for producing a selectively permeable membrane comprises a membrane modification step of reacting the acid halide groups of the unreacted polyfunctional acid halide monomer with an acrylic acid ester monomer or a methacrylic acid ester monomer.

2. 2. The method for producing a selectively permeable membrane according to claim 1, wherein the membrane modification step is carried out using a membrane modification solution containing 0.1 to 1.0% by weight of an acrylic acid ester monomer or a methacrylic acid ester monomer.

3. 2. The method for producing a selectively permeable membrane according to claim 1, wherein the support membrane is washed with an acid and / or an alkali after the membrane modification step.

4. 2. The method for producing a selectively permeable membrane according to claim 1, wherein the support membrane is washed with an organic solvent after the interfacial polymerization, and then the membrane modification step is carried out.

5. 2. The method for producing a selectively permeable membrane according to claim 1, wherein the support membrane is washed with an organic solvent after the membrane modification step.

6. 2. The method for producing a selectively permeable membrane according to claim 1, wherein the acrylic acid ester monomer or the methacrylic acid ester monomer is 2-methoxyethyl acrylate.

7. 2. The method for producing a selectively permeable membrane according to claim 1, wherein the selectively permeable membrane has an IR peak ratio calculated from the following (Equation 1) of 0.09 [-] or more. IR peak ratio [-] = (1725 cm －１ Absorbance of -1800 cm －１ absorbance) / (1670 cm －１ Absorbance of -1800 cm －１ absorbance) ... (Equation 1)

8. 2. The method for producing a selectively permeable membrane according to claim 1, wherein the selectively permeable membrane has an XPS bond ratio 1 calculated from the following (Equation 2) of 0.17 [-] or more. XPS bond ratio 1 [-] = (ratio [%] of O-C=O in C1s peak) / (ratio [%] of N-C=O in C1s peak) (Equation 2)

9. A water treatment method using a selectively permeable membrane obtained by the method for producing a selectively permeable membrane according to any one of claims 1 to 8.

Images