Composite semipermeable membrane, and spiral-type membrane element

Abstract

The present invention provides: a composite semipermeable membrane with which desired blocking performance is achieved and in which both contamination resistance and high water permeability are exhibited; and a spiral-type membrane element in which the composite semipermeable membrane is used. The present invention is a composite semipermeable membrane comprising a porous support, a separation function layer formed of a polyamide-based resin on the porous support, and a coating layer that covers the separation function layer and contains a cationic polymer, the composite semipermeable membrane being characterized in that: the polyamide-based resin contains a constituent component derived from m-phenylenediamine (MPD) and trimesic acid chloride (TMC), the molar ratio (TMC / MPD) of the TMC to the MPD being within the range of 0.65-1.00; and the separation function layer in a state of being covered by the coating layer has a surface roughness Ra1 of 85-150 nm as measured in a region measuring 5 μm × 5 μm using an atomic force microscope (AFM) in water.

Description

Composite semipermeable membrane and spiral membrane element

[0001] The present invention relates to a composite semipermeable membrane comprising a porous support and a separation functional layer, and a spiral-wound membrane element (hereinafter sometimes abbreviated as "membrane element") using the same.

[0002] RO (reverse osmosis) membranes use pressure as the driving force for separation and are used in a wide range of fields, such as seawater desalination, the production of ultrapure water, pure water, and sterile water, wastewater treatment and recovery from factories and buildings, and the separation, concentration, and purification of products from various processes in the food and pharmaceutical industries, etc. Reverse osmosis is a technology that works by applying a pressure greater than the osmotic pressure to the liquid to be treated, so it necessarily requires high-pressure operation.

[0003] Therefore, in recent years, there has been a demand for composite semipermeable membranes with improved water permeability in order to reduce running costs and environmental loads. However, there is generally a trade-off between blocking performance and water permeability, and it is difficult to obtain a composite semipermeable membrane that achieves both blocking performance and water permeability.

[0004] Conventionally, a known method for increasing the permeation flux (Flux) of a composite semipermeable membrane to reduce the operating pressure is to increase the effective membrane area of ​​the membrane by controlling the surface irregularities of the separation functional layer, as described in Patent Document 1. Furthermore, since the permeation flux of a composite semipermeable membrane shows a negative correlation with desalination performance, it is also possible to reduce operating energy by adjusting the desalination performance, but there is a demand for a composite semipermeable membrane with a relatively increased permeation flux relative to the target desalination performance.

[0005] Furthermore, since the operating energy of the membrane element and the frequency of chemical cleaning also have a large impact on the environmental load, the development of membranes with fouling resistance is also desired from the perspective of reducing the environmental load. As a method for imparting fouling resistance to RO membranes, for example, as described in Patent Document 2, a method of coating the surface of the separation functional layer with a polymer such as polyvinyl alcohol (PVA) is known.

[0006] However, when a coating such as PVA is applied to the membrane surface in order to impart fouling resistance, the flux tends to decrease, and therefore, the reality is that no composite semipermeable membrane that combines fouling resistance and high water permeability has been reported so far.

[0007] On the other hand, Patent Document 3 proposes coating the separating functional layer of a composite semipermeable membrane with a cationic polymer in order to improve the resistance to contamination by cationic substances.

[0008] International Publication WO 2024 / 122107 Publication JP 11-47566 Publication Patent No. 6526894 Publication

[0009] According to the investigations of the present inventors, it was found that in the case of conventional composite semipermeable membranes, the concave portions are easily filled by the polymer coating because the surface irregularities of the separation functional layer are not sufficiently large (see Figure 4), which causes a decrease in flux. Furthermore, it was found that even in the case of composite semipermeable membranes in which the surface irregularities of the separation functional layer are made larger, coating with a nonionic polymer such as PVA tends to decrease flux.

[0010] Therefore, an object of the present invention is to provide a composite semipermeable membrane that can obtain the desired blocking performance while simultaneously achieving both contamination resistance and high water permeability, and a spiral membrane element using the same.

[0011] As a result of extensive research aimed at solving the above-mentioned problems, the present inventors have found that by using a composite semipermeable membrane in which a separation functional layer is formed at a specific composition ratio and whose surface roughness is greater than that of conventional membranes, and by forming a coating layer with a cationic polymer, it is possible to obtain the desired blocking performance while also achieving both contamination resistance and high water permeability, and have completed the present invention. That is, the present invention includes the following aspects.

[0012] [1] A composite semipermeable membrane comprising a porous support, a separation functional layer formed on the porous support from a polyamide resin, and a coating layer covering the separation functional layer and containing a cationic polymer, wherein the polyamide resin contains components derived from m-phenylenediamine (MPD) and trimesoyl chloride (TMC), and the molar ratio of TMC to MPD (TMC / MPD) is in the range of 0.65 to 1.00, and the separation functional layer in a state covered with the coating layer has a surface roughness Ra1 of 85 to 150 nm when measured in a 5 μm × 5 μm area in water with an atomic force microscope (AFM).

[0013] The composite semipermeable membrane of the present invention can achieve the desired blocking performance while simultaneously achieving both contamination resistance and high water permeability. While the details of the reasons for this are unclear, it is believed to be as follows: Because the molar ratio of TMC to MPD (TMC / MPD) constituting the polyamide resin forming the separation functional layer is 0.65 to 1.00, the crosslinked structure can be loosened while maintaining the desired blocking performance. This loose crosslinked structure is thought to contribute to increasing the surface roughness of the separation functional layer while improving the permeability performance of the material. Furthermore, because the surface roughness in water after coating is 85 nm or more, the membrane area due to the increased roughness can be maintained. Furthermore, by forming a coating layer containing a cationic polymer, the coating state improves due to interaction with the separation functional layer, which is thought to enhance water permeability.

[0014] [2] The composite semipermeable membrane according to [1], wherein the cationic polymer is at least one selected from the group consisting of a diallyldimethylammonium chloride polymer, a copolymer thereof, and a cationized cellulose.

[0015] Among cationic polymers, these cationic polymers are easy to coat with a coating layer, and it is thought that the coating state becomes better due to interaction with the separation functional layer, thereby increasing water permeability.

[0016] [3] The rejection rate is 97.0% or more at an operating pressure of 0.48 MPa and a NaCl concentration of 500 ppm, and the flux is 0.6 m３ / m ２ / d or more.

[0017] With this configuration, the NaCl rejection rate is set lower than that of conventional RO membranes, so that the membrane can be used for a wide range of applications while improving its permeation performance as a material, and by reducing operating energy, it can contribute to reducing the environmental load. Furthermore, it is possible to achieve both rejection performance and permeation performance, which are in a trade-off relationship, and the higher permeation performance can further reduce operating energy.

[0018] [4] A composite semipermeable membrane according to any one of [1] to [3], wherein the flux maintenance rate after exposure to an aqueous solution of a nonionic surfactant having a concentration of 50 ppm by volume for 30 minutes is 50% or more.

[0019] According to this configuration, the stain resistance against nonionic surfactants is improved, and it becomes easier to obtain sufficient stain resistance against other charged substances.

[0020] [5] The composite semipermeable membrane according to any one of [1] to [4], wherein the separation functional layer before being coated with the coating layer has a surface roughness Ra0 of 90 nm or more when measured in an area of ​​5 μm × 5 μm in water with an atomic force microscope (AFM).

[0021] According to this configuration, the surface roughness of the separation functional layer before coating is sufficiently large, so that even after coating, it is easy to make the surface roughness Ra1 85 nm or more, and water permeability can be more reliably increased.

[0022] [6] A spiral membrane element having the composite semipermeable membrane according to any one of [1] to [5].

[0023] The spiral wound membrane element of the present invention has the composite semipermeable membrane of the present invention as described above, and therefore can provide a spiral wound membrane element that not only has the desired blocking performance but also has good fouling resistance and high water permeability.

[0024] According to the present invention, it is possible to provide a composite semipermeable membrane that not only has the desired blocking performance but also has good fouling resistance and high water permeability, and a spiral membrane element using the same.

[0025] 1 is a conceptual diagram schematically illustrating the difference between a separation functional layer of a composite semipermeable membrane in air and a separation functional layer of a composite semipermeable membrane in water. 2 is a partially cutaway perspective view showing an example of a spiral membrane element. 3 is a scanning electron microscope (SEM) photograph showing the composite semipermeable membrane obtained in Example 1, where the photograph on the left shows the state before a coating layer is formed (two locations), and the photograph on the right shows the state after formation (two locations). 4 is a scanning electron microscope (SEM) photograph showing the composite semipermeable membrane obtained in Reference Experimental Example 1, where the photograph on the left shows the state before a coating layer is formed (two locations), and the photograph on the right shows the state after formation (two locations).

[0026] Hereinafter, an embodiment of the present invention will be described.

[0027] (Composite semipermeable membrane) The composite semipermeable membrane of the present invention comprises a porous support, a separation functional layer formed on the porous support from a polyamide resin, and a coating layer covering the separation functional layer and containing a cationic polymer. The polyamide resin forming the separation functional layer contains components derived from m-phenylenediamine (MPD) and trimesoyl chloride (TMC).

[0028] The separation functional layer can be formed by interfacial polymerization of a polyamide resin, and is particularly preferably a separation functional layer containing a polyamide resin obtained by polymerizing a polyfunctional amine component and a polyfunctional acid halogen component. In the present invention, the polyfunctional amine component contains m-phenylenediamine, and the polyfunctional acid halogen component contains trimesoyl chloride, but other polyfunctional amine components or other polyfunctional acid halogen components may also be used.

[0029] The polyfunctional amine component is a polyfunctional amine having two or more reactive amino groups, and examples thereof include aromatic, aliphatic, and alicyclic polyfunctional amines. In the present invention, at least a divalent polyfunctional amine is used as the polyfunctional amine component.

[0030] Examples of aromatic polyfunctional amines other than m-phenylenediamine (MPD) include p-phenylenediamine, o-phenylenediamine, 1,3,5-triaminobenzene, 1,2,4-triaminobenzene, 3,5-diaminobenzoic acid, 2,4-diaminotoluene, 2,6-diaminotoluene, N,N'-dimethyl-m-phenylenediamine, 2,4-diaminoanisole, amidol, and xylylenediamine.

[0031] Examples of the aliphatic polyfunctional amine include ethylenediamine, propylenediamine, tris(2-aminoethyl)amine, and n-phenyl-ethylenediamine.

[0032] Examples of the alicyclic polyfunctional amine include 1,3-diaminocyclohexane, 1,2-diaminocyclohexane, 1,4-diaminocyclohexane, piperazine, 2,5-dimethylpiperazine, and 4-aminomethylpiperazine.

[0033] These polyfunctional amines may be used alone or in combination of two or more. In order to obtain a separating functional layer with the desired blocking performance, it is preferable to use an aromatic polyfunctional amine.

[0034] In particular, from the viewpoint of achieving a rejection rate of 97.0% or more at an operating pressure of 0.48 MPa and an NaCl concentration of 500 ppm, it is preferable to use m-phenylenediamine in an amount of 20 to 100 mol%, more preferably 50 to 100 mol%, and most preferably 100 mol%, in the polyfunctional amine component. This allows the separation functional layer to be formed from a polyamide-based resin containing a component derived from m-phenylenediamine.

[0035] The polyfunctional acid halide component is a polyfunctional acid halide having two or more reactive carbonyl groups. Examples of the polyfunctional acid halide include aromatic, aliphatic, and alicyclic polyfunctional acid halides. In the present invention, at least trimesoyl chloride (TMC) is used as the polyfunctional acid halide component.

[0036] Examples of aromatic polyfunctional acid halides other than TMC include terephthalic acid dichloride, isophthalic acid dichloride, biphenyldicarboxylic acid dichloride, naphthalenedicarboxylic acid dichloride, benzenetrisulfonic acid trichloride, benzenedisulfonic acid dichloride, and chlorosulfonylbenzenedicarboxylic acid dichloride.

[0037] Examples of the aliphatic polyfunctional acid halides include propanedicarboxylic acid dichloride, butanedicarboxylic acid dichloride, pentanedicarboxylic acid dichloride, propanetricarboxylic acid trichloride, butanetricarboxylic acid trichloride, pentanetricarboxylic acid trichloride, glutaryl halide, and adipoyl halide.

[0038] Examples of alicyclic polyfunctional acid halides include cyclopropanetricarboxylic acid trichloride, cyclobutanetetracarboxylic acid tetrachloride, cyclopentanetricarboxylic acid trichloride, cyclopentanetetracarboxylic acid tetrachloride, cyclohexanetricarboxylic acid trichloride, tetrahydrofurantetracarboxylic acid tetrachloride, cyclopentanedicarboxylic acid dichloride, cyclobutanedicarboxylic acid dichloride, cyclohexanedicarboxylic acid dichloride, and tetrahydrofurandicarboxylic acid dichloride.

[0039] These polyfunctional acid halides may be used alone or in combination of two or more. To obtain a separation functional layer with high salt rejection performance, it is preferable to use an aromatic polyfunctional acid halide. It is also preferable to use a trivalent or higher polyfunctional acid halide as at least a part of the polyfunctional acid halide component to form a crosslinked structure, and it is preferable to use at least trimesoyl chloride (TMC).

[0040] In particular, from the viewpoint of achieving a rejection rate of 97.0% or more at an operating pressure of 0.48 MPa and an NaCl concentration of 500 ppm, trimesoyl chloride (TMC) is preferably used in an amount of 20 to 100 mol %, more preferably 50 to 100 mol %, and most preferably 100 mol % in the polyfunctional acid halide component. This allows the separation functional layer to be formed from a polyamide-based resin containing a component derived from trimesoyl chloride.

[0041] In the present invention, from the viewpoint of achieving a rejection rate of 97.0% or more at an operating pressure of 0.48 MPa and a NaCl concentration of 500 ppm, the molar ratio of TMC to MPD (TMC / MPD) is preferably 0.65 or more, more preferably 0.7 or more, and even more preferably 0.8 or more. ３ / m ２ From the viewpoint of achieving a TMC / MPD ratio of 1.00 or more, the molar ratio of TMC to MPD (TMC / MPD) is preferably 1.00 or less, more preferably 0.95 or less, and even more preferably 0.9 or less. Such a molar ratio can be adjusted by increasing or decreasing the concentration or amount of each component.

[0042] The molar ratio of TMC to MPD (TMC / MPD) can be calculated from the peak area value by removing the substrate and porous resin layer from the composite semipermeable membrane, hydrolyzing the resulting separation functional layer in a strong alkaline heavy water solution, filtering the hydrolyzed heavy water solution, and measuring it by 1H-NMR, and analyzing the data obtained by the measurement.

[0043] It was found that when the molar ratio of the trivalent or higher polyfunctional acid halide to the divalent polyfunctional amine is less than 1.5, unreacted terminal carboxylic acids are present, but when the molar ratio is 1.0 or less, the crosslinked structure becomes loose and water permeability is improved.

[0044] In order to improve the performance of the separating functional layer containing a polyamide resin, it may be copolymerized with polymers such as polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, and polyhydric alcohols such as sorbitol and glycerin.

[0045] The porous support supporting the separation functional layer may be any one having a porous resin layer, and may be formed only from a porous resin layer, but is preferably one that is reinforced by a backing made of a substrate such as a woven fabric, a nonwoven fabric, etc. The porous support having a porous resin layer is not particularly limited as long as it can support the separation functional layer on its upper surface, and typically, an ultrafiltration membrane with an average pore size of about 10 to 500 Å is preferably used.

[0046] Examples of materials for forming the porous resin layer include polysulfone-based resins such as polysulfone, polyethersulfone, and polyphenylsulfone, polyimide, polyetherimide, and polyvinylidene fluoride, but polysulfone-based resins are preferably used because they are particularly chemically, mechanically, and thermally stable.

[0047] The total thickness of the porous support having the porous resin layer is, for example, about 50 to 200 μm, preferably about 80 to 150 μm. The thickness of the porous resin layer is, for example, 10 to 50 μm, preferably 20 to 40 μm. The porosity of the porous resin layer is, for example, 50 to 80%, preferably 60 to 70%.

[0048] Preferred methods for forming a separation functional layer containing a polyamide resin on the surface of a porous support include interfacial condensation. Specifically, the interfacial condensation method involves contacting an aqueous amine solution containing a polyfunctional amine component with an organic solution containing a polyfunctional acid halide component to form a separation functional layer by interfacial polymerization, and then placing the separation functional layer on a porous support. Alternatively, the interfacial polymerization on the porous support is used to directly form a separation functional layer of a polyamide resin on the porous support. Details of the conditions for such interfacial condensation methods are described in JP-A-58-24303 and JP-A-1-180208, and known techniques from these methods can be used as appropriate.

[0049] The separation functional layer formed on the porous support has fine irregularities, and the size of the irregularities can be measured using the surface roughness Ra as an index when a 5 μm × 5 μm area is measured in water with an atomic force microscope (AFM). In this specification, the surface roughness of the separation functional layer before being coated with the coating layer is defined as Ra0, and the surface roughness of the separation functional layer after being coated with the coating layer is defined as Ra1.

[0050] In the present invention, from the viewpoint of ensuring that the surface roughness Ra1 of the separation functional layer after being coated with the coating layer is 85 nm or more, the surface roughness Ra0 of the separation functional layer before being coated with the coating layer is preferably 90 nm or more, more preferably 95 nm or more, even more preferably 100 nm or more, and particularly preferably 105 nm or more.

[0051] Furthermore, from the viewpoint of preventing defects in the separation functional layer and durability, the surface roughness Ra0 is preferably 150 nm or less, more preferably 140 nm or less, even more preferably 130 nm or less, and particularly preferably 125 nm or less.

[0052] The degree of the fine irregularities of the separation functional layer can be known to some extent from the surface roughness Ra when a 5 μm x 5 μm area is measured in air using an atomic force microscope (AFM). However, compared to this case, using the surface roughnesses Ra0 and Ra1 measured in water as indicators allows for a more appropriate measurement of the fine irregularities of the separation functional layer under conditions closer to those actually used in membrane separation.

[0053] In other words, as shown in Figure 1, the separation function layer 1a formed on the porous support 1b of the composite semipermeable membrane 1 in the atmosphere tends to be observed in a collapsed or crushed state with fine irregularities in the separation function layer 1a compared to the state in which it is actually used for membrane separation, and by using the surface roughness Ra measured in water as an indicator, it becomes possible to more accurately measure the size of the fine irregularities in the separation function layer in a state close to the state in which it is actually used for membrane separation.

[0054] In this specification, the surface roughnesses Ra0 and Ra1 measured in water refer to the planar surface roughness Ra defined by the following formula (Mathematical Formula 1).

[0055]

[0056] Planar surface roughness can be calculated using values ​​measured using an atomic force microscope (AFM). The average surface roughness (Ra) is a three-dimensional extension of the centerline average roughness Ra defined in JIS B0601 so that it can be applied to measurement surfaces, and is the average value of the absolute values ​​of the deviations from the reference surface to the specified surface. Here, the measurement surface refers to the surface indicated by all measurement data, the specified surface refers to the surface that is the target of roughness measurement, and refers to a specific portion of the measurement surface designated by a clip (designated area is 5 μm × 5 μm), and the reference surface refers to the average height of the designated surface, calculated by Z ０ Then, Z = Z ０ This refers to a plane represented by

[0057] Methods for producing composite semipermeable membranes capable of adjusting the surface roughness Ra measured in air are described in, for example, Japanese Patent Application Laid-Open Nos. 9-85068 and 7-8770. In accordance with such production methods, the present invention also makes it possible to adjust the surface roughness Ra while checking the surface roughness Ra measured in water.

[0058] In particular, in a method for producing a composite semipermeable membrane by forming a polyamide-based skin layer (separation functional layer) by a means including a step of coating a porous support with a solution A containing a polyfunctional amine component and a step of contacting the solution A phase with a solution B containing a polyfunctional acid halide component, it is preferable to add an interfacial conditioner such as an alkanolamine compound, an alkyl ketone compound, or an alkyl ester compound to the solution A.

[0059] Examples of the alkanolamine compound include ethanolamine, methanolamine, propanolamine, butanolamine, etc., and may be any of monoalkanolamine, dialkanolamine, and trialkanolamine. In addition, the hydrogen atom bonded to the nitrogen atom of the alkanolamine compound may be substituted with an alkyl group, an alkenyl group, an alkynyl group, a phenyl group, etc. Among these, monoethanolamine, diethanolamine, and triethanolamine are preferred, and monoethanolamine and triethanolamine are more preferred.

[0060] Examples of the alkyl ketone compound include acetone, diisopropyl ketone, and cyclohexanone, and examples of the alkyl ester compound include ethyl acetate, propyl acetate, and butyl acetate.

[0061] The concentration of the interfacial conditioner in the solution A is preferably 0.1 to 10.0% by mass, more preferably 1.0 to 5.0% by mass, from the viewpoint of producing a composite semipermeable membrane having the above-mentioned surface roughness Ra0.

[0062] The surface roughness Ra0 can also be adjusted by the difference in solubility parameter between the solution A and the solution B, or the solubility parameter of a compound added to the solution A and / or the solution B. When producing a composite semipermeable membrane having the above-mentioned surface roughness Ra0, it is preferable to add a compound having a solubility parameter of 8 to 17 (cal / cm) to at least one selected from the solution A, the solution B, and the microporous support. ３ ) １／２ It is preferred that a compound of the formula:

[0063] Examples of the solubility parameter adjuster include alcohols such as ethanol, propanol, butanol, and pentanol, and nitrogen compounds such as ethylamine, triethylamine, and n-butylamine. The solubility parameter can also be adjusted by the type and concentration of the polyfunctional amine component or polyfunctional acid halogen component used.

[0064] In order to improve the salt blocking property, water permeability, and contamination resistance of the composite semipermeable membrane, various conventionally known treatments may be carried out before forming the coating layer.

[0065] (Coating Layer) The composite semipermeable membrane of the present invention is provided with a coating layer that coats the separation functional layer and contains a cationic polymer, and the separation functional layer in a state coated with the coating layer is characterized in that the surface roughness Ra1, when measured in an area of ​​5 μm × 5 μm in water with an atomic force microscope (AFM), is 85 to 150 nm.

[0066] Examples of the cationic polymer contained in the coating layer include polymers having cationic groups such as linear or cyclic quaternary ammonium groups or quaternary phosphonium groups. Among these, cationic polymers such as polymers of halide salts of diallylammonium compounds or copolymers thereof, or polysaccharides having cationic groups are preferred, and one or more cationic polymers selected from the group consisting of diallyldimethylammonium chloride polymers, copolymers thereof, and cationized cellulose are more preferred.

[0067] The polymer of the halide salt of the diallylammonium compound or the copolymer thereof may be a polymer having a repeating unit represented by the following formula (1):

[0068]

[0069] In formula (1), N + is a nitrogen atom constituting a quaternary ammonium cation. 1 and R 2 are each independently a substituent containing a carbon atom bonded to a nitrogen atom. When a polymer having a repeating unit represented by formula (1) is contained in the coating layer, the quaternary ammonium cation is always positively charged, regardless of the pH of the raw water. Therefore, adhesion of cationic substances to the surface of the composite semipermeable membrane is prevented. This effect is particularly remarkable when using a polymer having a repeating unit represented by formula (1).

[0070] In formula (1), N + The counter ion of N is not particularly limited. + The counter ion of is a monovalent anion. The monovalent anion is, for example, F - , Cl - ,Br - , I -These are halogen ions such as:

[0071] In formula (1), R 1 and R 2 may be an alkyl group. Examples of the alkyl group include a methyl group, an ethyl group, and a propyl group. Preferably, R 1 and R 2 is a methyl group. 1 and R 2 When R is an alkyl group such as a methyl group, the coating layer can sufficiently suppress the decrease in water permeability of the composite semipermeable membrane. 1 and R 2 When is an alkyl group such as a methyl group, the coating layer is less likely to affect the permeation flux of the composite semipermeable membrane.

[0072] In formula (1), R 1 may be a methyl group, and R 2 may be a 3-chloro-2-hydroxypropyl group. In this case, the repeating unit of the polymer is represented by the following formula (2):

[0073]

[0074] In formula (1), R 1 may be a methyl group, and R 2 may be a 2,3-epoxypropyl group. In this case, the repeating unit of the polymer is represented by the following formula (3):

[0075]

[0076] When an alkali is applied to the repeating unit represented by formula (2), a cyclization reaction of the 3-chloro-2-hydroxypropyl group proceeds, thereby converting the repeating unit represented by formula (2) into a repeating unit represented by formula (3).

[0077] The polymer contained in the coating layer may be a copolymer of a first monomer and a second monomer. The first monomer may be a monomer containing a quaternary ammonium cation and may be a monomer forming a repeating unit represented by formula (1). The first monomer may be 3-chloro-2-hydroxypropylmethyldiallylammonium chloride. When the second monomer is diallylmethylamine hydrochloride, the copolymer may be represented by formula (4):

[0078]

[0079] In formula (4), m and n each independently represent an integer of 1 or greater. Some or all of the multiple 3-chloro-2-hydroxypropyl groups contained in the polymer of formula (4) may be 2,3-epoxypropyl groups, as shown in formula (3).

[0080] In the copolymer represented by formula (4), the 3-chloro-2-hydroxypropyl group and / or the 2,3-epoxypropyl group contained in the first monomer may be a reactive substituent capable of chemically bonding to the separation functional layer.

[0081] The reactive substituent strengthens the bonding force between the separation functional layer and the coating layer. Specifically, at least a portion of the multiple reactive substituents form covalent bonds with the terminal amino groups, residual amino groups, or residual carbonyl groups of the separation functional layer. This fixes the coating layer to the separation functional layer, thereby providing a composite semipermeable membrane whose water permeability is less likely to decrease even after long-term use. The terminal amino groups and residual amino groups of the separation functional layer are derived from polyfunctional amines. The residual carbonyl groups of the separation functional layer are derived from polyfunctional acid halides. The reactive substituent may be used for intramolecular crosslinking and / or intermolecular crosslinking of the polymer. This can improve the mechanical strength, heat resistance, etc. of the coating layer.

[0082] The reactive substituent may be contained in the second monomer. When the first monomer has a quaternary ammonium cation structure, there are fewer restrictions on the second monomer. In other words, there is a greater degree of freedom in the selection of the second monomer.

[0083] The reactive substituent is not limited to a 3-chloro-2-hydroxypropyl group. Examples of the reactive substituent include an epoxy group, a hydroxyl group, an amino group, and an amide group. The polymer may contain only one type selected from these reactive substituents, or two or more types selected from these reactive substituents may be contained in the polymer.

[0084] When the reactive substituent is contained in the second monomer, the second monomer is, for example, allylamine. The polymer is represented by the following formula (5).

[0085]

[0086] In formula (5), m and n are each independently an integer of 1 or more.

[0087] When the reactive substituent is contained in the second monomer, the second monomer is, for example, acrylamide. The polymer is represented by the following formula (6).

[0088]

[0089] In formula (6), m and n are each independently an integer of 1 or more.

[0090] When the reactive substituent is contained in the second monomer, the second monomer is, for example, 3-chloro-2-hydroxypropyldiallylamine hydrochloride. The polymer is represented by the following formula (7):

[0091]

[0092] In formula (7), m and n are each independently an integer of 1 or more.

[0093] As the second monomer, only one selected from 3-chloro-2-hydroxypropyldiallylamine hydrochloride, allylamine, and acrylamide may be used, or two or more selected from the group consisting of 3-chloro-2-hydroxypropyldiallylamine hydrochloride, allylamine, and acrylamide may be used.

[0094] The copolymer may be a random copolymer or a block copolymer.

[0095] The ratio of the first monomer to the second monomer is not particularly limited. For example, the ratio of the first monomer to the second monomer may be 5:95 to 95:5, or may be 30:70 to 70:30. Within the above range, a composite semipermeable membrane with a small decrease in water permeability can be provided. The weight-average molecular weight of the polymer or copolymer is not particularly limited, and is, for example, 10,000 to 100,000.

[0096] On the other hand, examples of polysaccharides having cationic groups include cationic polymers in which cationic groups such as quaternary ammonium groups having a structure as shown in the following formula (8) have been introduced into polysaccharides such as cellulose, starch, and guar gum.

[0097]

[0098] In the above formula (8), R ３ , R ４ , R ５ are each independently an alkyl group, an aryl group, or an aralkyl group having 10 or less carbon atoms; R ６ is an alkylene or hydroxyalkylene group, and X is F - , Cl - ,Br - , I - Also, R ３ , R ４ , R ５ In one embodiment of the present invention, a quaternary ammonium group having the structure shown in formula (8) is bonded to a polyalkyloxy chain bonded to a hydroxyl group not involved in the formation of the cellulose skeleton, and the polyalkyloxy chain is introduced into the anhydroglucose unit in such a manner that the quaternary ammonium group has the structure shown in formula (8).

[0099] The number of cationic groups to be introduced into the water-soluble polymer (B) can be appropriately adjusted. For example, when cationic groups are introduced into a polysaccharide, reaction conditions may be used such that the degree of cationic substitution (the average number of cationic groups per anhydroglucose molecule) is 0.01 or more and 1 or less, preferably 0.02 or more and 0.5 or less.

[0100] The coating layer can be formed by contacting an aqueous solution containing a cationic polymer with the separation functional layer to form a cationic polymer-containing layer, and then drying the cationic polymer-containing layer. The method for contacting the aqueous solution with the separation functional layer is not particularly limited. The separation functional layer may be immersed in the aqueous solution together with the porous support, or the aqueous solution may be applied to the surface of the separation functional layer. The contact time between the separation functional layer and the aqueous solution is, for example, 10 seconds to 5 minutes. After contacting the separation functional layer with the aqueous solution, a step of removing excess aqueous solution from the separation functional layer may be carried out. The aqueous solution may contain, in addition to water, a polar solvent other than water, such as alcohol. A polar solvent other than water, such as alcohol, may be used instead of water.

[0101] The concentration of the cationic polymer solution prepared using the above solvent is, for example, 0.01 to 20% by weight, preferably 0.05 to 5% by weight, and more preferably 0.1 to 1.0% by weight. The coating layer may contain a crosslinking agent for crosslinking the cationic polymer, a surfactant, a drying accelerator, etc.

[0102] Next, the polymer-containing layer is heated and dried. Heat-treating the polymer-containing layer can increase the mechanical strength, heat resistance, and the like of the coating layer. The heating temperature is, for example, 80 to 150°C. The heating time is, for example, 30 to 300 seconds. After the drying step is performed at room temperature, a further drying step may be performed using a dryer at an ambient temperature higher than room temperature.

[0103] The separation functional layer in a coated state has a surface roughness Ra1 of 85 to 150 nm when measured in a 5 μm × 5 μm area with an atomic force microscope (AFM) in water, but from the viewpoint of obtaining high water permeability while obtaining the desired blocking performance, the surface roughness Ra1 is preferably 100 nm or more, more preferably 110 nm or more, and even more preferably 120 nm or more. Furthermore, from the viewpoint of preventing defects in the separation functional layer and durability, the surface roughness Ra1 is preferably 150 nm or less, more preferably 140 nm or less, and even more preferably 130 nm or less.

[0104] The surface roughness Ra1 of the separation functional layer in a state coated with the coating layer can be adjusted by adjusting the surface roughness Ra0 of the separation functional layer before the coating layer is coated, but it can also be adjusted by the amount of coating layer and the coating state. For example, if a composite semipermeable membrane having a relatively large surface roughness Ra0 is used and as little coating layer as possible is applied within a range in which sufficient contamination resistance is obtained, the surface roughness Ra1 will be relatively large compared to the surface roughness Ra0, which is preferable from the viewpoint of obtaining high water permeability while obtaining the desired blocking performance.

[0105] Therefore, the larger the ratio R = Ra1 / Ra0, the more advantageous it is for obtaining high water permeability while maintaining the desired blocking performance. Therefore, from the viewpoint of obtaining high water permeability while maintaining the desired blocking performance, the ratio R = Ra1 / Ra0 is preferably 0.5 or more, more preferably 0.6 or more, and even more preferably 0.7 or more. This is more effective in controlling the surface roughness after coating and the amount of coating layer coverage using the surface roughness Ra1 as an index in the present invention. If the ratio R = Ra1 / Ra0 is too large, the coating state of the coating layer is likely to become non-uniform. Therefore, the ratio R = Ra1 / Ra0 is preferably 0.95 or less, more preferably 0.9 or less.

[0106] The composite semipermeable membrane of the present invention preferably has a rejection of 97.0% or more at an operating pressure of 0.48 MPa and an NaCl concentration of 500 ppm, but the rejection can be made 98% or more or 99% or more depending on the application.

[0107] In particular, when the rejection rate is 97.0% or more at an operating pressure of 0.48 MPa and a NaCl concentration of 500 ppm, the composite semipermeable membrane of the present invention has a flux of 0.60 m at an operating pressure of 0.48 MPa and a NaCl concentration of 500 ppm. ３ / m ２ / d or more, and preferably the flux is 0.65 m ３ / m ２ / d or more, and more preferably, the flux is 0.70 m ３ / m ２ / d or more, and more preferably, the flux is 0.75 m ３ / m２ / d or more.

[0108] The composite semipermeable membrane of the present invention preferably has a flux retention rate of 50% or more after 30 minutes of exposure to a nonionic surfactant aqueous solution having a concentration of 50 ppm by volume, but from the viewpoint of making it easier to obtain higher contamination resistance against other charged substances, the flux retention rate is more preferably 55% or more, and even more preferably 57% or more. As described above, the composite semipermeable membrane of the present invention is one in which the separation functional layer is formed at a specific composition ratio, and when using a composite semipermeable membrane whose surface roughness is larger than conventional ones, the separation functional layer is coated with a cationic polymer, and the coating state is controlled using the surface roughness in water after coating as an indicator, thereby achieving both contamination resistance and high water permeability while maintaining the desired blocking performance.

[0109] (Spiral-type membrane element) The spiral-type membrane element of the present invention is characterized by having the composite semipermeable membrane as described above, and any of the conventional membrane element configurations can be adopted for the parts other than the composite semipermeable membrane.

[0110] The spiral membrane element of the present invention comprises, for example, a perforated central tube 5 and a wound body R wound around the central tube 5 and including a separation membrane 1, as shown in FIG.

[0111] 2 , the device includes a plurality of membrane leaves L, each having a permeate-side channel material 3 interposed between opposing separation membranes 1, a feed-side channel material 2 interposed between the membrane leaves L, a perforated central tube 5 around which the membrane leaves L and the feed-side channel material 2 are wound, and a sealing portion 12 that prevents mixing of the feed-side channel and the permeate-side channel. In this case, the permeate-side channel within the membrane leaf L can be formed by the permeate-side channel material 3 (also referred to as a permeate-side spacer).

[0112] It is also possible to form the feed-side flow path and / or the permeate-side flow path in the separation membrane 1 itself by providing irregularities or grooves on the surface of the separation membrane 1, and in this case, it is possible to omit the feed-side flow path material 2 and / or the permeate-side flow path material 3.

[0113] 2 shows an example in which the sealed portion includes both end sealed portions and an outer peripheral sealed portion 12. Of the sealed portions, the both end sealed portions are formed by sealing two edge portions on both sides of the membrane leaf L in the axial direction A1 with an adhesive. The outer peripheral sealed portion 12 is formed by sealing the edge portion at the outer peripheral tip of the membrane leaf L with an adhesive. The region surrounded by the opposing separation membranes 1, the both end sealed portions, and the outer peripheral sealed portion 12 forms a permeate-side flow path, which is structured to communicate with the openings 5a of the central tube 5.

[0114] It is also preferable to have a central sealing portion in which the perforated central tube 5 and the base end sides of both end sealing portions of the membrane leaf L are sealed with an adhesive. The membrane leaf L and the feed-side channel material 2 are wound around the central tube 5 via such a central sealing portion to form a wound body R. The adhesive is not particularly limited, and any conventionally known adhesive such as a urethane adhesive or an epoxy adhesive can be used.

[0115] A first end member 10 having a function such as a seal carrier may be provided on the upstream side of the membrane element wound body R, and a second end member 20 having a function such as an anti-telescope material may be provided on the downstream side.

[0116] In a typical 8-inch diameter spiral membrane element, about 15 to 30 sets of membrane leaves L are wound. When the membrane element is in use, it is housed in a pressure vessel, and a feed liquid 7 is supplied from one end face of the membrane element. The supplied feed liquid 7 flows along the feed-side flow path material 2 in a direction parallel to the axial direction A1 of the central tube 5, and is discharged from the other end face of the membrane element as a concentrated liquid 9. In addition, permeated liquid 8, which has permeated through the separation membrane 1 while the feed liquid 7 flows along the permeation-side flow path material 3, flows through the permeation-side flow path material 3, and then flows into the central tube 5 through the openings 5a and is discharged from the end of the central tube 5.

[0117] The feed-side channel material 2 generally serves to ensure gaps for uniformly supplying the fluid to the membrane surface. For example, nets, knitted fabrics, textured sheets, etc. can be used as such feed-side channel material 2, and those with a maximum thickness of approximately 0.1 to 3 mm can be used as needed. Furthermore, when channel materials are installed on both sides of the separation membrane 1, different channel materials are generally used as the feed-side channel material 2 on the feed liquid side and the permeate-side channel material 3 on the permeate side. It is preferable to use a thick, coarse-mesh net-like channel material for the feed-side channel material 2, while using a fine-mesh woven or knitted channel material for the permeate-side channel material 3.

[0118] When RO membranes or NF membranes are used in applications such as seawater desalination and wastewater treatment, the permeate-side channel material 3 is provided so as to be interposed between opposing separation membranes 1 in the membrane leaf L. This permeate-side channel material 3 is required to support the pressure applied to the membrane from the back side of the membrane and to ensure a channel for the permeate 8.

[0119] In order to ensure such a function, the permeate side channel material 3 is preferably formed of a tricot knit fabric, and more preferably, the tricot knit fabric is subjected to a resin impregnation reinforcement or fusion treatment after the knit fabric is formed.

[0120] The composite semipermeable membrane of the present invention described above is used as separation membrane 1. That is, the spiral membrane element of the present invention is a composite semipermeable membrane comprising a porous support, a separation functional layer formed on the porous support from a polyamide resin, and a coating layer containing a cationic polymer and covering the separation functional layer, wherein the polyamide resin contains components derived from m-phenylenediamine (MPD) and trimesoyl chloride (TMC), the molar ratio of TMC to MPD (TMC / MPD) is in the range of 0.65 to 1.00, and the separation functional layer in a state coated with the coating layer has a surface roughness Ra1 of 85 to 150 nm when measured in water over a 5 μm × 5 μm area with an atomic force microscope (AFM).

[0121] In the case of a typical spiral membrane element, an outer periphery of the wound body R is provided with an exterior material 15. The exterior material 15 is not particularly limited, and examples thereof include various sheets, films, tapes, etc., and, if necessary, a fiber-reinforced resin (FRP) or the like is used for reinforcement. A preferred method for forming the fiber-reinforced resin is to use roving, in which fibers are impregnated with a curable resin, and wrap this around the outer periphery of the wound body R.

[0122] (Applications) The composite semipermeable membrane and spiral-wound separation membrane element of the present invention can reduce the environmental load, which has been in increasing demand in recent years, particularly by reducing the operating pressure and the number of cleaning cycles, and can therefore be widely used in various membrane separation applications, such as the production of drinking water, the treatment of wastewater, and the concentration of foodstuffs and pharmaceuticals.

[0123] The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In the examples, physical properties were measured or evaluated by the following methods. The physical properties in the present invention are specifically values ​​measured by the following methods.

[0124] (1) Molar ratio (TMC / MPD) The prepared composite semipermeable membrane was immersed in cyclohexanone, and the polyamide resin in the skin layer was recovered. The recovered polyamide resin was then collected in a stainless steel tube, and methanol and an alkali were added thereto. The mixture was heated at 240°C for 1 hour to decompose the polyamide resin. After that, the mixture was allowed to cool to room temperature, and the decomposition liquid was collected. １ H-NMR measurement (measurement conditions: apparatus BRUKER Biospin, AVANCE III-600, measurement solvent: DMSO-d6, chemical shift reference: 2.50 ppm (deuterated DMSO), integration 64 times, chemical shifts: metaphenylenediamine (7.56 ppm), trimesoyl chloride (8.60 ppm) was performed. The data obtained by the measurement was analyzed, and the molar ratio of trimesoyl chloride (TMC) to m-phenylenediamine (MPD) (TMC / MPD) was calculated from the peak area values.

[0125] (2) Surface Roughness Ra1 Measured by AFM in Water In this specification, the surface roughness Ra means the roughness of a flat surface, and is defined by the following equation (Equation 2).

[0126]

[0127] The surface roughness Ra defined by the above formula was calculated using values ​​measured using an atomic force microscope (AFM) (AFM5300E, manufactured by Hitachi High-Tech Science Corporation). The average surface roughness (Ra) is a three-dimensional extension of the centerline average roughness Ra defined in JIS B0601 so that it can be applied to the measurement surface, and is the average value of the absolute value of the deviation from the reference surface to the designated surface. Here, the measurement surface refers to the surface indicated by all measurement data, the designated surface refers to a specific portion of the measurement surface that is the target of roughness measurement and is designated by a clip (designated area is 5 μm × 5 μm), and the reference surface refers to the average height of the designated surface, Z ０ Then, Z = Z ０ This refers to a plane represented by

[0128] For the prepared composite semipermeable membranes, measurements were performed with the composite semipermeable membranes on which a coating layer was formed immersed in ultrapure water. For commercially available products, a dry membrane was purchased, a coating layer was formed, and the membrane was temporarily hydrophilized by passing water under pressure. Then, measurements were performed using the composite semipermeable membrane immersed in ultrapure water. The sample immersed in ultrapure water was placed in a holder for liquid measurement while maintaining the wet state, and the liquid holder was filled with ultrapure water to perform AFM measurements. AFM measurements in water were performed on three samples each, and the average value of the surface roughness Ra1 was calculated.

[0129] (3) Surface roughness Ra0 before coating The surface roughness Ra0 of the composite semipermeable membrane before coating with a coating layer was measured by AFM in water in the same manner as in (2) above, except that the measurement sample was changed. That is, for the prepared composite semipermeable membrane, the measurement sample was a composite semipermeable membrane obtained after the drying step before the formation of the coating layer, which was temporarily hydrophilized by passing water under pressure, and stored immersed in ultrapure water to be in a wet state, and the measurement was performed using this. For commercially available products, a dried membrane was purchased, temporarily hydrophilized by passing water under pressure, and then immersed in ultrapure water, and the measurement was performed using this composite semipermeable membrane.

[0130] The ratio (-) of the surface roughness Ra1 after coating with the coating layer to the surface roughness Ra0 before coating with the coating layer was calculated by Ra1 / Ra0.

[0131] (4) Flux and Rejection of NaCl Aqueous Solution An aqueous solution of NaCl was prepared by dissolving NaCl in RO water at a concentration of 500 ppm. The flat composite semipermeable membrane was cut to a predetermined shape and size and placed in a cell (effective membrane surface area: 44.2 cm) of a cross-flow test system for flat membrane evaluation. ２ ) was set. An aqueous NaCl solution (temperature: 25°C) was allowed to permeate through the composite semipermeable membrane at an operating pressure of 0.48 MPa for 30 minutes. Thereafter, a membrane separation operation was carried out, and the permeation rate of the permeated water was measured, and the permeation flux (m ３ / m ２ / d) was calculated.

[0132] The conductivity of the permeate, concentrate, and feed solution was measured using a conductivity measuring device, and the NaCl rejection rate was calculated from the results and the calibration curve (concentration - conductivity) according to the following formula: NaCl rejection rate (%) = (1 - (NaCl concentration in permeate solution / (NaCl concentration in feed solution + NaCl concentration in concentrate) / 2)) x 100

[0133] (5) Evaluation of anti-fouling properties by nonionic surfactants The permeation flux of the obtained composite semipermeable membrane was measured as follows. First, a flat composite semipermeable membrane was cut into a predetermined shape and size, and placed in a cell (effective membrane surface area: 44.2 cm) of a cross-flow test system for flat membrane evaluation. ２ ) The pressure was set to 1.5 MPa. RO water (temperature 25°C) was allowed to permeate through the composite semipermeable membrane for 30 minutes. The permeation rate of the permeated water obtained by this operation for 30 minutes was measured, and the permeation flux was calculated.

[0134] Next, an aqueous solution (temperature 25°C) containing 50 ppm by volume of a nonionic surfactant (NCW1002, manufactured by Fujifilm Electronic Materials Co., Ltd.) was subjected to membrane separation at an operating pressure of 1.5 MPa, and the aqueous solution was contacted with the composite semipermeable membrane for 30 minutes. Then, RO water (temperature 25°C) was subjected to membrane separation at an operating pressure of 1.5 MPa for 30 minutes. The permeation rate of the permeated water obtained by this operation for 30 minutes was measured, and the permeation flux was calculated. The permeation flux maintenance rate was calculated using the following formula. The results are shown in Table 1.

[0135] Flux maintenance rate (%) = 100 × (flux of RO water after contact with nonionic surfactant) / (flux of RO water before contact with nonionic surfactant). When the flux maintenance rate is 50% or more, the contamination resistance against various contaminants is sufficient.

[0136] (Reference Experimental Example 1) A composite semipermeable membrane obtained by disassembling a commercially available NF membrane element (NF90-400, manufactured by DuPont) was used to examine the change in the surface irregularities and the change in separation performance depending on whether or not a coating layer was present.

[0137] That is, 0.1% by mass of polyvinyl alcohol (PVA) (JC-25 manufactured by Japan Vinyl Acetate & Poval Co., Ltd., saponification degree ≧ 99%, solution viscosity (4%, 20 ° C) 62.0 to 72.0 mPa s), 10% by mass of isopropyl alcohol (IPA), and 89.9% by mass of water were uniformly mixed and dissolved to obtain a coating solution. The surface of the separation functional layer of the composite semipermeable membrane was immersed in this coating solution for 10 seconds. Thereafter, the separation functional layer was air-dried for 30 seconds and further held in a hot air dryer at 120 ° C for 2 minutes to form a coating layer. Scanning electron microscope (SEM) photographs of the composite semipermeable membrane before and after application of the coating layer are shown in Figure 4. From this photograph, it can be seen that when the fine irregularities of the separation functional layer before application of the coating layer are small, as in the case of commercially available NF membranes, the fine depressions in the separation functional layer are easily filled when the coating layer is applied.

[0138] Regarding separation performance, although the rejection rate of the NaCl aqueous solution decreased slightly after applying the coating layer, the flux of the NaCl aqueous solution decreased to less than 1 / 10. In other words, it was confirmed that if the surface irregularities of the separation functional layer are not large enough, the concave portions are easily filled by the polymer coating, which causes the flux to decrease.

[0139] Example 1: An aqueous amine solution containing 2.5% by mass of m-phenylenediamine (MPD), 0.1% by mass of sodium dodecyl sulfate, 2.6% by mass of triethylamine, 1.7% by mass of monoethanolamine, 0.03% by mass of sodium hydroxide, 6% by mass of camphorsulfonic acid, 1.5% by mass of magnesium nitrate, and 4% by mass of isopropyl alcohol was applied to a polysulfone porous support formed on a polyester nonwoven fabric, and then excess amine aqueous solution was removed to form an aqueous solution coating layer. Next, the surface of the aqueous solution coating layer was immersed for 7 seconds in an acid chloride solution prepared by dissolving 0.2% by mass of trimesoyl chloride (TMC) and 0.2% by mass of 2-methyl-2-butanol in a naphthenic solvent (Exxsol D40, manufactured by ExxonMobil Corporation). Thereafter, excess solution on the surface of the aqueous solution coating layer was removed, followed by air drying for 20 seconds and then holding in a hot air dryer at 140°C for 3 minutes to form a separating function layer containing a polyamide resin on the porous polysulfone support layer, thereby forming a composite semipermeable membrane having a nonwoven fabric substrate, a polysulfone porous support layer, and a polyamide separating function layer arranged in this order. The surface roughness Ra0 of this composite semipermeable membrane before the formation of the coating layer was as shown in Table 1.

[0140] Next, 0.1% by mass of diallyldimethylammonium chloride polymer (Unisense FPA100L, manufactured by Senka Corporation) and 99.9% by mass of water were uniformly mixed and dissolved to obtain a coating solution. The surface of the separation functional layer of the composite semipermeable membrane produced above was immersed in this coating solution for 10 seconds. The separation functional layer was then air-dried for 30 seconds and further held in a hot air dryer at 120°C for 2 minutes to form a coating layer. The evaluation results of the composite semipermeable membrane with the coating layer formed are shown in Table 1, along with the coating conditions.

[0141] A scanning electron microscope (SEM) photograph of the obtained composite semipermeable membrane is shown in Figure 3. This photograph shows that in the composite semipermeable membrane of the present invention, the fine irregularities of the separating functional layer before the coating layer is applied are sufficiently large, and by forming the coating layer on this in an appropriate application state, the fine irregularities of the separating functional layer are sufficiently maintained.

[0142] Example 2 A composite semipermeable membrane was produced under the same conditions as in Example 1, except that the surface conditioner used in Example 1 was changed from monoethanolamine to diethanolamine.

[0143] (Example 3) A composite semipermeable membrane was produced under the same conditions as in Example 1, except that the monoethanolamine used as the interface conditioner was changed to triethanolamine and the concentration was changed to 2.0 mass%. The evaluation results are shown in Table 1.

[0144] (Example 4) A composite semipermeable membrane was produced under the same conditions as in Example 1, except that a diallyldimethylammonium chloride-acrylamide copolymer (Unisense FCA1000L, manufactured by Senka Corporation) was used instead of the diallyldimethylammonium chloride polymer in Example 1. The evaluation results are shown in Table 1.

[0145] (Example 5) A composite semipermeable membrane was produced under the same conditions as in Example 1, except that cationized cellulose (manufactured by Toho Chemical Industry Co., Ltd., HC-200) was used instead of the diallyldimethylammonium chloride polymer in Example 1. The evaluation results are shown in Table 1.

[0146] Comparative Example 1 A composite semipermeable membrane was produced under the same conditions as in Example 1, except that the concentrations of monoethanolamine and trimesoyl chloride (TMC) as the interface conditioner were changed so that the molar ratio (TMC / MPD) and Ra1 after coating would be the values ​​shown in Table 1. The evaluation results are shown in Table 1.

[0147] Comparative Example 2 A composite semipermeable membrane was produced under the same conditions as in Example 1, except that the concentrations of monoethanolamine and trimesoyl chloride (TMC) as the interface conditioner were changed so that the molar ratio (TMC / MPD) and Ra1 after coating would be the values ​​shown in Table 1. The evaluation results are shown in Table 1.

[0148] (Comparative Example 3) A composite semipermeable membrane was produced under the same conditions as in Example 1, except that anion-modified polyvinyl alcohol (T-330H, manufactured by Mitsubishi Chemical Corporation) was used instead of the diallyldimethylammonium chloride polymer in Example 1. The evaluation results are shown in Table 1.

[0149] Comparative Example 4 A composite semipermeable membrane was produced under the same conditions as in Example 1, except that polyvinyl alcohol (PVA) (JC-25 manufactured by Nippon Vinyl Acetate & Poval Co., Ltd., saponification degree ≥ 99%, solution viscosity (4%, 20°C) 62.0 to 72.0 mPa s) was used instead of the diallyldimethylammonium chloride polymer in Example 1. The evaluation results are shown in Table 1.

[0150] Comparative Example 5 A composite semipermeable membrane was produced under the same conditions as in Example 1, except that a zwitterionic polymer (LAMBIC-1000W, manufactured by Osaka Organic Chemical Industry Ltd.) was used instead of the diallyldimethylammonium chloride polymer in Example 1. The evaluation results are shown in Table 1.

[0151] Comparative Example 6 The composite semipermeable membrane before being coated with the coating layer was used in Example 1. The evaluation results are shown in Table 1.

[0152] FPA100L: Diallyldimethylammonium chloride polymer FCA1000L: Diallyldimethylammonium chloride-acrylamide copolymer HC-200: Cationic cellulose T-330H: Anion-modified polyvinyl alcohol PVA(JC-25): Polyvinyl alcohol LAMBIC-1000W: Zwitterionic polymer

[0153] As shown in the results in Table 1, in Examples 1 to 5, the desired blocking performance was obtained, and composite semipermeable membranes that were both anti-fouling and had high water permeability were obtained.

[0154] In contrast, Comparative Example 1, in which the surface roughness Ra1 after the formation of the coating layer was small, had insufficient water permeability, and Comparative Example 2, in which the molar ratio (TMC / MPD) was too low, had even lower water permeability. Comparative Examples 3 to 5, in which the coating layer was formed using a polymer other than a cationic polymer, had low water permeability and insufficient stain resistance. Comparative Example 6, in which no coating layer was formed, had insufficient stain resistance.

[0155] According to the present invention, it is possible to provide a composite semipermeable membrane that not only achieves the desired blocking performance but also combines fouling resistance with high water permeability, and a spiral membrane element using the same.

[0156] In recent years, composite semipermeable membranes with improved water permeability have been desired in order to reduce running costs and environmental loads, and the composite semipermeable membrane of the present invention is particularly effective as a technology for reducing running costs and environmental loads.

[0157] 1: Separation membrane 1a: Separation functional layer 1b: Porous support 5: Center tube A1: Axial direction R: Wound body

Claims

1. A composite semipermeable membrane comprising a porous support, a separation functional layer formed on the porous support from a polyamide resin, and a coating layer covering the separation functional layer and containing a cationic polymer, wherein the polyamide resin contains components derived from m-phenylenediamine (MPD) and trimesoyl chloride (TMC), and the molar ratio of TMC to MPD (TMC / MPD) is in the range of 0.65 to 1.00, and the separation functional layer in a state coated with the coating layer has a surface roughness Ra1 of 85 to 150 nm when measured in a 5 μm x 5 μm area in water with an atomic force microscope (AFM).

2. The composite semipermeable membrane according to claim 1, wherein the cationic polymer is at least one member selected from the group consisting of diallyldimethylammonium chloride polymers, copolymers thereof, and cationic cellulose.

3. The rejection rate is 97.0% or more at an operating pressure of 0.48 MPa and a NaCl concentration of 500 ppm, and the flux is 0.6 m ３ / m ２ The composite semipermeable membrane according to claim 1, wherein the ρ is 0.1 / d or more.

4. The composite semipermeable membrane according to claim 1, which has a flux retention rate of 50% or more after being exposed to an aqueous solution of a nonionic surfactant having a concentration of 50 ppm by volume for 30 minutes.

5. The composite semipermeable membrane according to claim 1, wherein the separation functional layer before being coated with the coating layer has a surface roughness Ra0 of 90 nm or more when measured in an area of ​​5 μm × 5 μm in water with an atomic force microscope (AFM).

6. A spiral-wound membrane element having the composite semipermeable membrane according to any one of claims 1 to 5.

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