Polyamide nanofiltration membrane, composite semipermeable membrane, and method for producing the composite semipermeable membrane

Abstract

The present invention provides a polyamide nanofiltration membrane, a composite semipermeable membrane, and a method for manufacturing the composite semipermeable membrane, which can achieve both high water permeability and high salt blocking properties. [Solution] A polyamide nanofiltration membrane according to one embodiment of the present invention is formed by polymerizing a monomer containing a polyfunctional amine compound and a polyfunctional acid halide, wherein the polyfunctional amine compound contains an amine compound having a hydroxyl group, and at least a portion of the ester bond formed by polycondensation between the amine compound having a hydroxyl group and the polyfunctional acid halide is hydrolyzed.

Description

[Technical Field]

[0001] This invention relates to polyamide nanofiltration membranes, composite semipermeable membranes, and methods for producing composite semipermeable membranes. [Background technology]

[0002] In fields such as seawater and brine desalination, industrial water and ultrapure water production, and wastewater recovery, membrane-based processes, which are lower in cost compared to heat-based processes, are being developed. Among membrane-based processes, reverse osmosis (RO) membranes are widely used. However, while RO membrane treatment has the advantage of being able to remove ions and low-molecular-weight organic substances to a high degree, the membrane structure is dense, so high pressure is required for permeation through the membrane.

[0003] In recent years, nanofiltration (NF) membranes have attracted attention. NF membranes require only about 1 / 10 the intermembrane pressure of RO membranes during operation, and exhibit excellent inhibitory properties against small organic molecules and polyvalent ions.

[0004] For example, Non-Patent Document 1 describes a polyamide NF film prepared by interfacial polymerization of piperazine and trimesinate chloride. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] S. Shao, et al., “Nanofiltration Membranes with Crumpled Polyamide Films: A Critical Review on Mechanisms, Performances, and Environmental Applications”, Environ. Sci. Technol., 56, pp.12811-12877(2022) [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, there is a trade-off relationship between water permeability and salt resistance, making it difficult to fabricate polyamide NF films that possess both high water permeability and high salt resistance. [Means for solving the problem]

[0007] The present invention has been made to solve at least some of the aforementioned problems and can be realized in the following embodiments or applications.

[0008] [1] One embodiment of the polyamide nanofiltration membrane according to the present invention is It is obtained by polymerizing monomers containing a polyfunctional amine compound and a polyfunctional acid halide, The polyfunctional amine compound comprises an amine compound having a hydroxyl group, At least a portion of the ester bond formed by the polycondensation of the hydroxyl group-containing amine compound and the polyfunctional acid halide is hydrolyzed.

[0009] [2] In one embodiment of the polyamide nanofiltration membrane described above, The amine compound having a hydroxyl group may be at least one selected from 3-aminophenol and 3-aminobenzyl alcohol.

[0010] [3] In any embodiment of the polyamide nanofiltration membrane described above, The aforementioned polyfunctional amine compound may contain piperazine.

[0011] [4] In the [3] aspect of the polyamide nanofiltration membrane described above, The ratio of piperazine to the hydroxyl-containing amine compound in the monomer may be, by weight, piperazine:hydroxyl-containing amine compound = 75:25 to 25:75.

[0012] [5] One embodiment of the composite semipermeable membrane according to the present invention is: A composite semipermeable membrane comprising a water-permeable substrate and a polyamide nanofiltration membrane formed on the water-permeable substrate, The polyamide nanofiltration membrane is formed by polymerizing a monomer containing a polyfunctional amine compound and a polyfunctional acid halide on the water-permeable substrate, The polyfunctional amine compound includes an amine compound having a hydroxyl group, At least a part of the ester bond formed by polycondensation of the amine compound having a hydroxyl group and the polyfunctional acid halide is hydrolyzed.

[0013] [6] In one aspect of the above composite semipermeable membrane, It may have a water permeation rate of 20 L / (m 2 ·h·bar) or more.

[0014] [7] In any aspect of the above composite semipermeable membrane, The salt rejection rate of Na2SO4 may be 60% or more.

[0015] [8] In any aspect of the above composite semipermeable membrane, The amine compound having a hydroxyl group is at least one selected from 3-aminophenol and 3-aminobenzyl alcohol, The polyfunctional amine compound may contain piperazine.

[0016] [9] One aspect of the method for producing the composite semipermeable membrane according to the present invention is, A step of preparing a water-permeable substrate, A step of applying a monomer containing a polyfunctional amine compound containing an amine compound having a hydroxyl group and a polyfunctional acid halide on the water-permeable substrate, A step of polymerizing the monomer on the water-permeable substrate to form a dense layer on the water-permeable substrate, A step of cleaving at least a part of the ester bond formed by polycondensation of the amine compound having a hydroxyl group and the polyfunctional acid halide in the dense layer by hydrolysis, including.

[0017]

[10] In one embodiment of the method for producing the composite semipermeable membrane, The amine compound having a hydroxyl group is at least one selected from 3-aminophenol and 3-aminobenzyl alcohol. The aforementioned polyfunctional amine compound may contain piperazine. [Effects of the Invention]

[0018] According to one embodiment of the polyamide nanofiltration membrane, composite semipermeable membrane, and method for producing the composite semipermeable membrane according to the present invention, it is possible to achieve both high water permeability and high salt inhibition. [Brief explanation of the drawing]

[0019] [Figure 1] A flowchart illustrating a method for manufacturing a composite semipermeable membrane according to one embodiment. [Figure 2] This figure shows the results of measuring the water permeability and salt rejection rate of samples prepared with an amine composition of 3-aminophenol:PIP(50:50). [Figure 3] This figure shows the results of measuring the water permeability and salt rejection rate of samples prepared using the amine composition 3-aminobenzyl alcohol:PIP(50:50). [Figure 4] This figure shows the results of measuring the water permeability and salt rejection rate of samples prepared using the amine composition 3-aminophenol:PIP(75:25). [Figure 5] This figure shows the results of measuring the water permeability and salt rejection rate of samples prepared using the amine composition 3-aminobenzyl alcohol:PIP(75:25). [Figure 6] This figure shows the results of measuring the water permeability and salt rejection rate of samples prepared using the amine composition 3-aminophenol:PIP(25:75). [Figure 7] This figure shows the results of measuring the water permeability and salt rejection rate of samples prepared using the amine composition of PIP+MPD for each example. [Modes for carrying out the invention]

[0020] Embodiments of the present invention will be described below. The embodiments described below are examples of the present invention. The present invention is not limited in any way to the embodiments described below, and includes various modifications that can be implemented without changing the gist of the present invention. Not all of the configurations described below are necessarily essential to the present invention.

[0021] In this specification, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively.

[0022] 1. Polyamide nanofiltration membrane A polyamide nanofiltration membrane according to one embodiment of the present invention is formed by polymerizing a monomer containing a polyfunctional amine compound and a polyfunctional acid halide, wherein the polyfunctional amine compound contains an amine compound having a hydroxyl group, and at least a portion of the ester bond formed by polycondensation between the amine compound having a hydroxyl group and the polyfunctional acid halide is hydrolyzed.

[0023] In the polyamide nanofiltration membrane according to this embodiment, the ester bonds in the main chain of the polymerized polyamide are cleaved by hydrolysis, at least partially. By cleaving the ester bonds that form the main chain of the polyamide, the network structure of the polyamide is relaxed, and carboxyl groups and hydroxyl groups are generated. This makes it possible to achieve both high water permeability and high salt blocking properties.

[0024] 1.1 Polyfunctional amine compounds The monomers constituting the polyamide nanofiltration membrane according to this embodiment include a polyfunctional amine compound. The polyfunctional amine compound is an amine compound having two or more functional groups, and having at least one amine group.

[0025] The polyfunctional amine compound is preferably present in the monomer at an amount of 30% to 80% by mass, more preferably at 40% to 70% by mass, and even more preferably at 50% to 60% by mass, relative to the total amount of monomers. The polyfunctional amine compound may be used alone or in combination of two or more types.

[0026] The polyamide nanofiltration membrane according to this embodiment contains monomer units derived from a polyfunctional amine compound. The proportion of monomer units derived from the polyfunctional amine compound is preferably 30 moles to 70 moles, more preferably 40 moles to 65 moles, and even more preferably 50 moles to 60 moles in the polyamide nanofiltration membrane.

[0027] 1.1.1 Amine compounds containing a hydroxyl group In this embodiment, the polyfunctional amine compound includes an amine compound having a hydroxyl group. Amine compounds having such hydroxyl groups can form ester bonds through polycondensation with polyfunctional acid halides.

[0028] Examples of amine compounds having a hydroxyl group include aromatic amines having a hydroxyl group, aliphatic amines having a hydroxyl group, and heterocyclic amines having a hydroxyl group.

[0029] Examples of aromatic amines having a hydroxyl group include compounds in which an amino group and a hydroxyl group are bonded to a benzene ring, such as 3-aminophenol, 2-aminophenol, and 4-aminophenol; and compounds in which an amino group and a hydroxyalkyl group are bonded to a benzene ring, such as 3-aminobenzyl alcohol, 2-aminobenzyl alcohol, 4-aminobenzyl alcohol, and 2-(aminophenyl)ethanol.

[0030] Examples of aliphatic amines having a hydroxyl group include ethanolamine, N-methylethanolamine, diethanolamine, and triethanolamine. Examples of heterocyclic amines having a hydroxyl group include 1-(2-hydroxyethyl)piperazine.

[0031] Aliphatic amines containing hydroxyl groups may be used individually or in combination of two or more.

[0032] Among these, the aliphatic amine having a hydroxyl group is preferably an aromatic amine having a hydroxyl group, more preferably at least one selected from 3-aminophenol and 3-aminobenzyl alcohol, and even more preferably one selected from 3-aminophenol and 3-aminobenzyl alcohol. When such a compound is used, water permeability and salt inhibition may be further improved.

[0033] The polyamide nanofiltration membrane according to this embodiment contains monomer units derived from an amine compound having a hydroxyl group. The proportion of monomer units derived from the amine compound having a hydroxyl group is preferably 15 moles to 35 moles, more preferably 20 moles to 33 moles, and even more preferably 25 moles to 30 moles in the polyamide nanofiltration membrane.

[0034] 1.1.2 Other Polyfunctional Amine Compounds In this embodiment, the polyfunctional amine compound may include other polyfunctional amine compounds other than amine compounds having a hydroxyl group.

[0035] Other polyfunctional amine compounds include, but are not limited to, heterocyclic amines such as piperazine (PIP) and 2,5-pyrroledicarboxylic acid; aromatic amines such as 1,2-diaminobenzene, 1,3-diaminobenzene, and 1,4-diaminobenzene; and aliphatic amines such as ethylenediamine, 1,3-diaminopropane, 1,2-diaminopropane, and hexamethylenediamine.

[0036] Other polyfunctional amine compounds may be used individually or in combination of two or more.

[0037] Among these, heterocyclic amines are preferred among the other polyfunctional amine compounds, and piperazines are more preferred. When the polyfunctional amine compound contains piperazine, water permeability and salt inhibition may be further improved.

[0038] When a polyfunctional amine compound contains piperazine, the piperazine and hydroxyl group in the monomer The ratio of piperazine to the amine compound having a hydroxyl group is preferably 75:25 to 25:75 by weight, more preferably 60:40 to 40:60, even more preferably 55:45 to 45:55, and particularly preferably 52:48 to 48:52. When the ratio of piperazine to the amine compound having a hydroxyl group is within the above range, water permeability and salt inhibition tend to improve further.

[0039] When the polyamide nanofiltration membrane according to this embodiment contains monomer units derived from polyfunctional amine compounds other than amine compounds having hydroxyl groups, the proportion of monomer units derived from polyfunctional amine compounds other than amine compounds having hydroxyl groups is preferably 15 ml to 35 ml, more preferably 20 ml to 32 ml, and even more preferably 25 ml to 30 ml in the polyamide nanofiltration membrane.

[0040] 1.2 Polyfunctional acid halides The monomer constituting the polyamide nanofiltration membrane according to this embodiment includes a polyfunctional acid halide. The polyfunctional acid halide has two or more reactive carbonyl groups in which a halogen is bonded to an acyl group. Examples of halogens include F, Cl, Br, and I, but Cl is preferred.

[0041] Examples of polyfunctional acid halides include aromatic, aliphatic, and alicyclic polyfunctional acid halides.

[0042] Examples of aromatic polyfunctional acid halides include trimecinate trichloride (TMC), terephthalic acid dichloride, isophthalic acid dichloride, biphenyldicarboxylic acid dichloride, and naphthalenedicarboxylic acid dichloride.

[0043] Examples of aliphatic polyfunctional acid halides include propanedicarboxylic acid dichloride, butanedicarboxylic acid dichloride, and pentanedicarboxylic acid dichloride.

[0044] Examples of alicyclic polyfunctional acid halides include 1,3,5-cyclohexanetricarboxylic acid trichloride, 1,2,4-cyclobutanetricarboxylic acid trichloride, and cyclohexanedicarboxylic acid chloride.

[0045] Polyfunctional acid halides may be used individually or in combination of two or more types.

[0046] Among these, polyfunctional acid halides are preferably aromatic polyfunctional acid halides, and trimesic acid trichloride (TMC) is more preferred. When such compounds are used, water permeability and salt inhibition may be further improved.

[0047] The polyfunctional acid halide is preferably present in the monomer at an amount of 20% to 70% by mass, more preferably at 30% to 60% by mass, and even more preferably at 40% to 50% by mass, relative to the total amount of monomer. The polyfunctional acid halide may be used alone or in combination of two or more types.

[0048] The polyamide nanofiltration membrane according to this embodiment contains monomer units derived from a polyfunctional acid halide. The proportion of monomer units derived from the polyfunctional acid halide is preferably 30 moles to 70 moles, more preferably 35 moles to 60 moles, and even more preferably 40 moles to 50 moles in the polyamide nanofiltration membrane.

[0049] 1.3 Other Monomers The monomers constituting the polyamide nanofiltration membrane according to this embodiment may include monomers other than those listed above. Examples include diols such as 3-methyl-1,5-pentanediol, 1,6-hexanediol, and 1,4-butanediol.

[0050] If other monomers are included, it is preferable that they be 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, relative to the total amount of monomers.

[0051] 1.4 Polymerization method Polymerization of the above monomers can be carried out by known methods such as interfacial polymerization. For example, it can be carried out by heat treatment (heating). Specific polymerization methods will be described later.

[0052] 1.5 Structural properties In the polyamide nanofiltration membrane according to this embodiment, at least a portion of the ester bonds formed by the polycondensation of an amine compound having hydroxyl groups and a polyfunctional acid halide are hydrolyzed. By cleaving the ester bonds that form the main chain of the polyamide, the network structure of the polyamide is relaxed, and carboxyl groups and hydroxyl groups are generated. As a result, the polyamide nanofiltration membrane can achieve both high water permeability and high salt blocking properties.

[0053] The degree to which the ester bond formed by the polycondensation of an amine compound having a hydroxyl group and a polyfunctional acid halide is hydrolyzed is not particularly limited, but it is preferably 5% or more hydrolyzed, more preferably 10% or more hydrolyzed, even more preferably 30% or more hydrolyzed, and particularly preferably 50% or more hydrolyzed. The degree of hydrolysis of the ester bond can be measured by infrared spectroscopy (IR).

[0054] Hydrolysis can be carried out by known methods. For example, it can be performed by base treatment using an aqueous sodium hydroxide solution. Specific treatment methods will be described later.

[0055] 2.Composite semipermeable membrane A composite semipermeable membrane according to one embodiment of the present invention is a composite semipermeable membrane comprising a water-permeable substrate and a polyamide nanofiltration membrane formed on the water-permeable substrate, wherein the polyamide nanofiltration membrane is formed by polymerizing a monomer comprising a polyfunctional amine compound and a polyfunctional acid halide on the water-permeable substrate, the polyfunctional amine compound comprises an amine compound having a hydroxyl group, and at least a portion of the ester bond formed by polycondensation between the amine compound having a hydroxyl group and the polyfunctional acid halide is hydrolyzed.

[0056] The composite semipermeable membrane according to this embodiment can achieve both high water permeability and high salt inhibition by including the polyamide nanofiltration membrane described above.

[0057] 2.1 Water-permeable substrate The composite semipermeable membrane according to this embodiment includes a water-permeable substrate.

[0058] The permeable substrate has the function of imparting mechanical strength to the polyamide nanofiltration membrane described above. Preferably, the permeable substrate has a structure in which, for example, micropores with a uniform pore size, or micropores with a gradually increasing pore size from one side to the other, and the pore size is 100 nm or less on the surface of one side. Suitable materials include polysulfone, polyaryl ethersulfone such as polyethersulfone, cellulose acetate, cellulose nitrate, polyvinyl chloride, polyimide, polyvinylidene fluoride, or blends thereof; however, polysulfone, which has high chemical, mechanical, and thermal stability, is preferred.

[0059] The pore size on the surface of the water-permeable substrate can be, for example, 100 nm or less, preferably 50 nm or less, and more preferably 10 nm or less.

[0060] Furthermore, the permeable substrate may have layers of fabrics such as nonwoven, woven, or knitted materials laminated onto it, which can increase its mechanical strength. The permeable substrate usually has a thickness of about 25 μm to 150 μm, preferably about 40 μm to 100 μm, but is not necessarily limited to these dimensions.

[0061] Furthermore, microfiltration (MF) membranes, ultrafiltration (UF) membranes, nanofiltration (NF) membranes, and reverse osmosis (RO) membranes may be used as permeable substrates.

[0062] 2.2 Polyamide nanofiltration membrane The composite semipermeable membrane according to this embodiment includes the polyamide nanofiltration membrane described above, formed on a water-permeable substrate. The polyamide nanofiltration membrane functions as a functional layer that separates water from organic matter, ions, and other substances other than water.

[0063] The polyamide nanofiltration membrane is formed by polymerizing a monomer containing a polyfunctional amine compound and a polyfunctional acid halide on a water-permeable substrate. The polyfunctional amine compound contains an amine compound having a hydroxyl group, and at least a portion of the ester bond formed by the polycondensation of the amine compound having a hydroxyl group and the polyfunctional acid halide is hydrolyzed.

[0064] The amine compound having a hydroxyl group is preferably at least one selected from 3-aminophenol and 3-aminobenzyl alcohol, and more preferably one selected from 3-aminophenol and 3-aminobenzyl alcohol. Furthermore, the polyfunctional amine compound preferably contains piperazine. This tends to further improve water permeability and salt inhibition.

[0065] As described above, the polyamide nanofiltration membrane will not be explained further.

[0066] 2.3 Performance The permeability of the composite semipermeable membrane according to this embodiment is 7.5 L / (m³). 2 Preferably, it is 10 L / (m³) or higher. 2 It is more preferable that it be 20 L / (m³) or higher. 2 It is even more preferable that it be 25 L / (m³) or higher. 2 It is particularly preferable that the permeability is ≥ 1 / h·bar. Since the composite semipermeable membrane according to this embodiment includes the polyamide nanofiltration membrane described above, high water permeability within the above range can be obtained.

[0067] The permeability is calculated using the following formula (1). Water permeability: Jv = permeate volume [L] / (membrane area [m 2 ( ) × Time [h] × Pressure [bar]) ...(1)

[0068] The salt rejection rate of Na2SO4 of the composite semipermeable membrane according to this embodiment is preferably 30% or more, more preferably 50% or more, and even more preferably 60% or more. Since the composite semipermeable membrane according to this embodiment includes the above-mentioned polyamide nanofiltration membrane, a high salt rejection rate within the above range can be obtained.

[0069] The salt rejection rate is calculated by the following formula (2). Salt rejection rate: R = (1 - C p / C b ) × 100 ···(2) C p : Solute concentration on the permeate side C b : Solute concentration on the concentrate side

[0070] Also, the salt rejection rate of NaCl of the composite semipermeable membrane according to this embodiment is preferably 5% or more, and more preferably 10% or more. Furthermore, the salt rejection rate of MgSO4 of the composite semipermeable membrane according to this embodiment is preferably 10% or more, and more preferably 20% or more.

[0071] 3. Method for manufacturing a composite semipermeable membrane The method for manufacturing a composite semipermeable membrane according to an embodiment of the present invention includes a step of preparing a water-permeable substrate, a step of applying a monomer containing a polyfunctional amine compound containing an amine compound having a hydroxyl group and a polyfunctional acid halide on the water-permeable substrate, a step of polymerizing the monomer on the water-permeable substrate to form a dense layer on the water-permeable substrate, and a step of hydrolyzing and cleaving at least a part of the ester bond formed by polycondensation of the amine compound having a hydroxyl group and the polyfunctional acid halide in the dense layer.

[0072] According to the method for manufacturing a composite semipermeable membrane according to this embodiment, the above-mentioned composite semipermeable membrane that can achieve both high water permeability and high salt blocking property can be obtained.

[0073] Figure 1 is a flowchart of a method for manufacturing a composite semipermeable membrane according to one embodiment. As shown in Figure 1, the method for manufacturing a composite semipermeable membrane according to this embodiment includes the steps of: preparing a permeable substrate (S10); applying a monomer containing a polyfunctional amine compound having a hydroxyl group and a polyfunctional acid halide to the permeable substrate (S20); polymerizing the monomer on the permeable substrate to form a dense layer on the permeable substrate (S30); and cleaving at least a portion of the ester bonds formed by polycondensation between the amine compound having a hydroxyl group and the polyfunctional acid halide in the dense layer by hydrolysis (S40). In this embodiment, an example further including a washing step (S50) after S40 will be described.

[0074] 3.1 Process for preparing the permeable substrate (S10) In this process, the permeable substrate described above is prepared. As the permeable substrate, for example, an ultrafiltration (UF) membrane is prepared.

[0075] It is preferable that the permeable substrate be cleaned. Cleaning can be performed, for example, by immersing the permeable substrate in a mixture of an organic solvent such as isopropanol and water for 5 to 60 minutes, and then immersing it in deionized water for 12 to 48 hours.

[0076] After cleaning the permeable substrate, it is preferable to remove the moisture using an air blower or similar device.

[0077] 3.2 Process of applying monomer (S20) The process of applying monomers involves applying monomers, including the polyfunctional amine compound containing the hydroxyl group-containing amine compound and the polyfunctional acid halide, to the permeable substrate prepared in S10.

[0078] The polyfunctional amine compound described above, which includes the amine compound having the hydroxyl group described above, is preferably applied to a water-permeable substrate as an aqueous solution. The concentration of the polyfunctional amine compound in the aqueous solution is not particularly limited, but is preferably 0.01% to 1.00% by mass, more preferably 0.05% to 0.50% by mass, and even more preferably 0.10% to 0.30% by mass.

[0079] The aqueous solution of the polyfunctional amine compound may contain polyfunctional amine compounds other than amine compounds having hydroxyl groups. The aqueous solution of the polyfunctional amine compound preferably contains heterocyclic amines, and piperazine is more preferably included. When piperazine is included in the aqueous solution of the polyfunctional amine compound, the ratio of piperazine to the amine compound having hydroxyl groups is preferably, by weight, 75:25 to 25:75, more preferably 60:40 to 40:60, and 55:45 to 45:55. It is even more preferable that the ratio be 52:48 to 48:52.

[0080] The amine compound having a hydroxyl group is preferably at least one selected from 3-aminophenol and 3-aminobenzyl alcohol, and more preferably one selected from 3-aminophenol and 3-aminobenzyl alcohol. Furthermore, the polyfunctional amine compound is more preferably piperazine. As a result, the composite semipermeable membrane tends to have improved water permeability and salt inhibition.

[0081] For example, monomers of the polyfunctional amine compound can be imparted to the permeable substrate by immersing it in an aqueous solution of the polyfunctional amine compound for a certain period of time. The immersion time is not particularly limited, but is preferably 10 seconds to 5 minutes, more preferably 30 seconds to 3 minutes, and even more preferably 1 to 2 minutes.

[0082] The polyfunctional acid halide described above is preferably applied as a solution to a water-permeable substrate. Since polyfunctional acid halides are prone to degradation when reacting with water, lipophilic solvents such as IP solvent, 2,2,4-trimethylpentane, 2-methylheptane, 2-methylpentane, n-hexane, n-decane, n-octane, and n-nonane are preferred as solvents. It is preferable that the solution of the polyfunctional acid halide is separate from the aqueous solution of the polyfunctional amine compound. The concentration of the polyfunctional acid halide in the solution is not particularly limited, but is preferably, for example, 0.01% to 1.50% by mass, more preferably 0.05% to 0.40% by mass, and even more preferably 0.10% to 0.20% by mass.

[0083] For example, monomers of polyfunctional amine compounds can be imparted to a permeable substrate by immersing it in a solution of polyfunctional acid halide for a certain period of time. The immersion time is not particularly limited, but is preferably 1 minute or less, more preferably 30 seconds or less, and even more preferably 15 seconds or less.

[0084] It is preferable to first apply a polyfunctional amine compound to a permeable substrate and dry it, and then apply a polyfunctional acid halide to the permeable substrate.

[0085] 3.3 Process to form a dense layer by polymerization (S30) The step of polymerizing to form a dense layer involves polymerizing the monomers provided in S20 to form a dense layer (polyamide) on a permeable substrate.

[0086] Polymerization of monomers applied to a water-permeable substrate can be carried out by known methods such as interfacial polymerization. For example, it can be carried out by heat treatment (heating). The heating temperature is preferably 80°C to 140°C, more preferably 90°C to 130°C, and particularly preferably 100°C to 120°C. The heating time is preferably 1 minute to 30 minutes, more preferably 5 minutes to 20 minutes, and even more preferably 10 minutes to 15 minutes.

[0087] 3.4 Hydrolysis process (S40) The hydrolysis step involves cleaving at least a portion of the ester bonds formed by the polycondensation of a hydroxyl-containing amine compound and a polyfunctional acid halide in the dense layer obtained in S30 by hydrolysis. This step transforms the dense layer into the polyamide nanofiltration membrane described above.

[0088] Hydrolysis of ester bonds in the polyamide main chain can be carried out by contacting a permeable substrate on which the dense layer described above is formed with an alkaline aqueous solution or an acidic aqueous solution. A non-pressurized contact method is preferred. This non-pressurized contact method is performed by immersing the membrane in a predetermined solution or by passing a predetermined solution through a membrane placed in a cell or vessel and allowing it to stand. The contact time is 1 day under conditions of a flow rate of 3.0 mL / min and a stirring speed of 1000 rpm. The above is preferable, two days or more is preferable, and three days or more is preferable.

[0089] Suitable alkaline aqueous solutions include those with a concentration of approximately 0.01N to 1N, such as NaOH and KOH. Suitable acidic aqueous solutions include those with a concentration of approximately 0.01N to 1N, such as HCl, HNO3, and H2SO4.

[0090] 3.5 Washing process (S50) The washing step involves washing the permeable substrate obtained in S40 by hydrolysis of the dense layer. Washing can remove any remaining bases or acids in the polyamide nanofiltration membrane, thus stabilizing it, but it may also reduce performance such as water permeability and salt inhibition. In contrast, the manufacturing method for the composite semipermeable membrane according to this embodiment does not significantly reduce performance such as water permeability and salt inhibition even after washing.

[0091] Washing can be performed, for example, by contact with ultrapure water, a high-purity solvent, etc. A pressurized contact method is preferred for contact. The contact time is preferably one day or more, and preferably two days or more, under conditions of a pressure of 0.3 MPa, a flow rate of 9.9 mL / min, and a stirring speed of 1000 rpm.

[0092] 4. Examples The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" below refers to mass.

[0093] 4.1 Sample Preparation [Example 1-1] <3-aminophenol: PIP (50:50), 1 day base treatment> 0.01 g of 3-aminophenol and 0.01 g of piperazine (PIP) were dissolved in Milli-Q water to prepare an amine aqueous solution (3-aminophenol:PIP = 50:50) containing 0.1% by mass of 3-aminophenol and piperazine, respectively. Additionally, 0.0150 g of trimeciate trichloride (TMC) was dissolved in hexane to prepare an acid chloride solution containing 0.15% by mass of trimeciate trichloride.

[0094] The support (ultrafiltration membrane made of polyethersulfone (PES) with a molecular weight cutoff of 300 kDa (LX; Synder, California, USA)) was immersed in a 20% by mass aqueous solution of isopropanol for 30 minutes, then immersed in Milli-Q water for 24 hours, rinsed both sides of the support with Milli-Q water, and set in a frame. Moisture was removed from the support using an air blower to prevent it from drying out too much, and then it was immediately immersed in the amine aqueous solution prepared above for 1 minute. After that, with the support set in the frame upright, an air blower was applied at a pressure of 0.05 MPa for 1 to 2 minutes to remove moisture without drying out too much. Immediately after that, it was immersed in the acid chloride solution prepared above for 15 seconds. Then, with the support upright, the acid chloride solution was discarded and it was allowed to air dry. After it was completely dry, the support was heat-treated for 10 minutes in a constant temperature and humidity chamber (ANS-113S, Isuzu Seisakusho LTD, Tokyo, Japan) at 100°C with the support upright. Afterward, the support on which the film had formed was removed, and after confirming that the film's temperature had decreased, the film was immersed in Milli-Q water in a petri dish for storage.

[0095] The above membrane was subjected to base treatment using a cross-flow type permeability test apparatus. Specifically, the support on which the above membrane was formed was placed in a stainless steel cell (homemade, effective membrane area 8.0 cm²). 2 The membrane was set up in a circular shape. Subsequently, a 0.1 mol / L NaOH aqueous solution was supplied to the membrane cell as the feed solution using a plunger pump (NPL-120, Nihon seimitsu kagaku CO.LTD, Tokyo, Japan), and the permeate and concentrate were returned to the feed solution to circulate and perform base treatment. No pressure was applied during the base treatment, and the flow rate was 3.0 m / s. The treatment was carried out under conditions of L / min and a stirring speed of 1000 rpm. The base treatment was performed for 1 day to obtain the sample according to Example 1-1.

[0096] [Examples 1-2] <3-aminophenol: PIP (50:50), 2-day base treatment> A sample according to Example 1-2 was obtained in the same manner as in Example 1-1, except that a base treatment was performed for two days.

[0097] [Examples 1-3] <3-aminophenol:PIP (50:50), 2 days of base treatment, 1 day of pure water washing> Furthermore, a sample according to Example 1-3 was obtained in the same manner as in Example 1-2, except that a pure water wash was performed for one day. The pure water wash was performed by circulating Milli-Q water in the same manner as in the base treatment, under conditions of a pressure of 0.3 MPa, a flow rate of 9.9 mL / min, and a stirring speed of 1000 rpm.

[0098] [Examples 1-4] <3-aminophenol:PIP (50:50), 2 days of base treatment, 2 days of pure water washing> A sample according to Example 1-4 was obtained in the same manner as in Example 1-3, except that a pure water wash was performed for two days.

[0099] [Example 2-1] <3-aminobenzyl alcohol: PIP (50:50), 1 day base treatment> A sample according to Example 2-1 was obtained in the same manner as in Example 1-1, except that 3-aminobenzyl alcohol was used instead of 3-aminophenol.

[0100] [Example 2-2] <3-aminobenzyl alcohol: PIP (50:50), 2-day base treatment> A sample according to Example 2-2 was obtained in the same manner as in Example 2-1, except that a base treatment was performed for two days.

[0101] [Examples 2-3] <3-aminobenzyl alcohol: PIP (50:50), 3-day base treatment> A sample according to Example 2-3 was obtained in the same manner as in Example 2-1, except that a base treatment was performed for 3 days.

[0102] [Examples 2-4] <3-aminobenzyl alcohol: PIP (50:50), 4-day base treatment> A sample according to Example 2-4 was obtained in the same manner as in Example 2-1, except that the base treatment was performed for 4 days.

[0103] [Examples 2-5] <3-aminobenzyl alcohol: PIP (50:50), 4 days of base treatment, 1 day of pure water washing> Furthermore, a sample according to Example 2-5 was obtained in the same manner as in Example 2-4, except that a pure water wash was performed for one day. The pure water wash was performed in the same manner as in Example 1-3.

[0104] [Example 3-1] <3-aminophenol: PIP (75:25), 1-day base treatment> 0.015 g of 3-aminophenol and 0.005 g of piperazine (PIP) were dissolved in Milli-Q water, resulting in a concentration of 0.15% by mass of 3-aminophenol and piperazine. A sample according to Example 3-1 was obtained in the same manner as in Example 1-1, except that an amine aqueous solution (3-aminophenol:PIP=75:25) containing 0.05% by mass was prepared and used.

[0105] [Example 3-2] <3-aminophenol: PIP (75:25), 2-day base treatment> A sample according to Example 3-2 was obtained in the same manner as in Example 3-1, except that a base treatment was performed for two days.

[0106] [Example 3-3] <3-aminophenol:PIP (75:25), 2 days of base treatment, 1 day of pure water washing> Furthermore, a sample according to Example 3-3 was obtained in the same manner as in Example 3-2, except that a pure water wash was performed for one day. The pure water wash was performed in the same manner as in Example 1-3.

[0107] [Examples 3-4] <3-aminophenol:PIP (75:25), 2 days of base treatment, 2 days of pure water washing> A sample according to Example 3-4 was obtained in the same manner as in Example 3-3, except that a pure water wash was performed for two days.

[0108] [Example 4-1] <3-aminobenzyl alcohol: PIP (75:25), 1 day base treatment> A sample according to Example 4-1 was obtained in the same manner as in Example 3-1, except that 3-aminobenzyl alcohol was used instead of 3-aminophenol.

[0109] [Example 4-2] <3-aminobenzyl alcohol: PIP (75:25), 2-day base treatment> A sample according to Example 4-2 was obtained in the same manner as in Example 4-1, except that a base treatment was performed for two days.

[0110] [Example 4-3] <3-aminobenzyl alcohol: PIP (75:25), 3-day base treatment> A sample according to Example 4-3 was obtained in the same manner as in Example 4-1, except that a base treatment was performed for 3 days.

[0111] [Example 4-4] <3-aminobenzyl alcohol: PIP (75:25), 3 days of base treatment, 1 day of pure water washing> Furthermore, a sample according to Example 4-4 was obtained in the same manner as in Example 4-3, except that a pure water wash was performed for one day. The pure water wash was performed in the same manner as in Example 1-3.

[0112] [Example 5-1] <3-aminophenol: PIP (25:75), 1-day base treatment> A sample according to Example 5-1 was obtained in the same manner as in Example 1-1, except that an amine aqueous solution (3-aminophenol:PIP = 25:75) was prepared by dissolving 0.005 g of 3-aminophenol and 0.015 g of piperazine (PIP) in Milli-Q water, resulting in a concentration of 0.05% by mass of 3-aminophenol and 0.15% by mass of piperazine.

[0113] [Example 5-2] <3-aminophenol: PIP (25:75), 2-day base treatment> A sample according to Example 5-2 was obtained in the same manner as in Example 5-1, except that a base treatment was performed for two days.

[0114] [Example 5-3] <3-aminophenol: PIP (25:75), 2 days of base treatment, 1 day of pure water washing> Furthermore, a sample according to Example 5-3 was obtained in the same manner as in Example 5-2, except that a pure water wash was performed for one day. The pure water wash was performed in the same manner as in Example 1-3.

[0115] [Example 5-4] <3-aminophenol:PIP (25:75), 2 days of base treatment, 2 days of pure water washing> A sample according to Example 5-4 was obtained in the same manner as in Example 5-3, except that a pure water wash was performed for two days.

[0116] [Example 5-5] <3-aminophenol: PIP (25:75), 2 days of base treatment, 3 days of pure water washing> A sample according to Example 5-5 was obtained in the same manner as in Example 5-3, except that pure water washing was performed for 3 days.

[0117] [Example 5-6] <3-Aminophenol:PIP(25:75), 2-day base treatment, 4-day pure water washing> A sample according to Example 5-6 was obtained in the same manner as in Example 5-3, except that pure water washing was performed for 4 days.

[0118] [Comparative Example 1] <3-Aminophenol:PIP(50:50), no base treatment> A sample according to Comparative Example 1 was obtained in the same manner as in Example 1-1, except that no base treatment was performed.

[0119] [Comparative Example 2] <3-Aminobenzyl alcohol:PIP(50:50), no base treatment> A sample according to Comparative Example 2 was obtained in the same manner as in Example 2-1, except that no base treatment was performed.

[0120] [Comparative Example 3] <3-Aminophenol:PIP(75:25), no base treatment> A sample according to Comparative Example 3 was obtained in the same manner as in Example 3-1, except that no base treatment was performed.

[0121] [Comparative Example 4] <3-Aminobenzyl alcohol:PIP(75:25), no base treatment> A sample according to Comparative Example 4 was obtained in the same manner as in Example 4-1, except that no base treatment was performed.

[0122] [Comparative Example 5-1] <PIP + MPD, no base treatment> 0.01 g of piperazine (PIP) and 0.01 g of m-phenylenediamine (MPD) were dissolved in Milli-Q water to prepare an amine aqueous solution (PIP + MPD) in which piperazine and m-phenylenediamine were each 0.1% by mass. A sample according to Comparative Example 5-1 was obtained in the same manner as in Example 1-1, except that no base treatment was performed.

[0123] [Comparative Example 5-2] <PIP + MPD, base treatment for 1 day> A sample according to Comparative Example 5-2 was obtained in the same manner as in Example 1-1, except that 0.01 g of piperazine (PIP) and 0.01 g of m-phenylenediamine (MPD) were dissolved in Milli-Q water to prepare an amine aqueous solution (PIP + MPD) in which piperazine and m-phenylenediamine were each 0.1% by mass and used.

[0124] ] [Comparative Example 5-3] <PIP + MPD, base treatment for 2 days> A sample according to Comparative Example 5-3 was obtained in the same manner as in Comparative Example 5-2, except that the base treatment was performed for 2 days.

[0125] [Comparative Example 5-4] <PIP + MPD, base treatment for 3 days> A sample according to Comparative Example 5-4 was obtained in the same manner as in Comparative Example 5-2, except that the base treatment was performed for 3 days.

[0126] [Comparative Example 5-5] <PIP + MPD, base treatment for 4 days> A sample according to Comparative Example 5-5 was obtained in the same manner as in Comparative Example 5-2, except that the base treatment was performed for 4 days. <0'000543>

[0127] [Comparative Example 5-6] <PIP + MPD, base treatment for 5 days> A sample according to Comparative Example 5-6 was obtained in the same manner as in Comparative Example 5-2, except that the base treatment was performed for 5 days.

[0128] [Comparative Example 5-7] <PIP + MPD, base treatment for 6 days> A sample according to Comparative Example 5-7 was obtained in the same manner as in Comparative Example 5-2, except that the base treatment was carried out for 6 days.

[0129] [Comparative Example 5-8] <PIP + MPD, 6-day base treatment, 1-day pure water washing> A sample according to Comparative Example 5-8 was obtained in the same manner as in Comparative Example 5-7, except that pure water washing was carried out for 1 day. The pure water washing was carried out in the same manner as in Example 1-3.

[0130] [Comparative Example 5-9] <PIP + MPD, 6-day base treatment, 2-day pure water washing> A sample according to Comparative Example 5-9 was obtained in the same manner as in Comparative Example 5-8, except that pure water washing was carried out for 2 days.

[0131] [Comparative Example 6] <3-aminophenol:PIP(25:75), no base treatment> A sample according to Comparative Example 6 was obtained in the same manner as in Example 5-1, except that no base treatment was carried out.

[0132] 4.2 Evaluation test of water permeability and salt barrier property The evaluation of the water permeability and salt barrier property of the samples according to each example obtained above was carried out using a cross-flow type water permeability test apparatus. Specifically, the sample according to each prepared example was set in a stainless steel cell (self-made, membrane effective area 8.0 cm 2 , circular). Then, the feed water was supplied to the membrane cell by a plunger pump (NPL-120, Nihon seimitsu kagaku CO.LTD, Tokyo, Japan). The pressure was adjusted to 0.30 MPa by a back pressure valve, the supply liquid amount was adjusted to 9.9 mL / min, and the water permeation amount was measured. The water permeation amounts of the samples according to each example are shown in FIGS. 2 to 7. If the water permeation amount is 7.5 [LMH / bar] or more, it can be said that the water permeability is high.

[0133] Subsequently, to measure the salt inhibition rate, 0.05 mass% aqueous solutions of NaCl, Na2SO4, and MgSO4 were used as the supplied solution, and the salt inhibition rate was measured. The pressure was set to 0.30 MPa and the flow rate to 9.9 mL / min. Furthermore, the salt inhibition rate was measured while the stirrer was rotated at 1000 rpm. The salt inhibition rates for each sample are shown in Figures 2 to 7. A salt inhibition rate of 60% or higher for at least one type of salt indicates high salt inhibition.

[0134] The laboratory temperature was maintained at approximately 25°C. The permeability was calculated by measuring the amount of permeate by weight and using the formula (1) described above. The salt rejection rate was calculated by measuring the solute concentration using an electrical conductivity meter (B-771, Horiba, Japan) and using the formula (2) described above. Note that [LMH / bar] = [L / (m³] 2 (·h·bar)). In Figures 2 to 7, "W1" indicates that the pure water washing was performed for one day, and "W2" indicates that the pure water washing was performed for two days.

[0135] 4.3 Evaluation Results The evaluation results are shown in Figures 2 to 7.

[0136] The samples in each example all exhibited high water permeability, with a water permeability of 7.5 [LMH / bar] or higher, and high salt inhibition, with a salt inhibition rate of 60% or higher for at least one type of salt (Na2SO4). In contrast, the samples in each comparative example all exhibited poor water permeability, with a water permeability of less than 7.5 [LMH / bar].

[0137] Based on the above, the samples in each example using a polyamide nanofiltration membrane, which is obtained by polymerizing a monomer containing a polyfunctional amine compound and a polyfunctional acid halide, wherein the polyfunctional amine compound contains an amine compound having a hydroxyl group, and at least a portion of the ester bond formed by the polycondensation of the amine compound having a hydroxyl group and the polyfunctional acid halide is hydrolyzed, were able to achieve both high water permeability and high salt inhibition.

[0138] In contrast, the samples in each comparative example that did not satisfy the above configuration were unable to achieve both high water permeability and high salt inhibition.

[0139] The present invention is not limited to the embodiments described above, and various modifications are possible. For example, the present invention includes configurations that are substantially identical to the configurations described in the embodiments, for example, configurations that have the same function, method and result, or configurations that have the same purpose and effect. The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. Furthermore, the present invention includes configurations that produce the same effects or achieve the same purpose as the configurations described in the embodiments. Furthermore, the present invention includes configurations that add known technology to the configurations described in the embodiments.

Claims

1. It is obtained by polymerizing monomers containing a polyfunctional amine compound and a polyfunctional acid halide, The polyfunctional amine compound comprises an amine compound having a hydroxyl group, A polyamide nanofiltration membrane in which at least a portion of the ester bond formed by polycondensation of the hydroxyl group-containing amine compound and the polyfunctional acid halide is hydrolyzed.

2. The polyamide nanofiltration membrane according to claim 1, wherein the amine compound having a hydroxyl group is at least one selected from 3-aminophenol and 3-aminobenzyl alcohol.

3. The polyamide nanofiltration membrane according to claim 2, wherein the polyfunctional amine compound comprises piperazine.

4. The polyamide nanofiltration membrane according to claim 3, wherein the ratio of piperazine to the hydroxyl-containing amine compound in the monomer is, by weight, piperazine:hydroxyl-containing amine compound = 75:25 to 25:

75.

5. A composite semipermeable membrane comprising a water-permeable substrate and a polyamide nanofiltration membrane formed on the water-permeable substrate, The polyamide nanofiltration membrane is formed by polymerizing a monomer containing a polyfunctional amine compound and a polyfunctional acid halide on the permeable substrate. The polyfunctional amine compound comprises an amine compound having a hydroxyl group, A composite semipermeable membrane in which at least a portion of the ester bond formed by polycondensation of the hydroxyl group-containing amine compound and the polyfunctional acid halide is hydrolyzed.

6. 20 L / (m ２ A composite semipermeable membrane according to claim 5, having a water permeability of 1 / h / bar or more.

7. Na ２ SO ４ A composite semipermeable membrane according to claim 5 or claim 6, wherein the salt rejection rate is 60% or more.

8. The amine compound having a hydroxyl group is at least one selected from 3-aminophenol and 3-aminobenzyl alcohol. The composite semipermeable membrane according to claim 5 or 6, wherein the polyfunctional amine compound comprises piperazine.

9. The process of preparing a water-permeable substrate, A step of applying a monomer containing a polyfunctional amine compound having a hydroxyl group and a polyfunctional acid halide onto the permeable substrate, A step of polymerizing the monomer on the permeable substrate to form a dense layer on the permeable substrate, A step of cleaving at least a portion of the ester bond formed by the polycondensation of the hydroxyl group-containing amine compound and the polyfunctional acid halide in the dense layer by hydrolysis, A method for producing a composite semipermeable membrane, including the above.

10. The amine compound having a hydroxyl group is at least one selected from 3-aminophenol and 3-aminobenzyl alcohol. The method for producing a composite semipermeable membrane according to claim 9, wherein the polyfunctional amine compound comprises piperazine.

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