WO2022065457A1 - Porous film and method for producing same - Google Patents

Porous film and method for producing same Download PDF

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Publication number
WO2022065457A1
WO2022065457A1 PCT/JP2021/035193 JP2021035193W WO2022065457A1 WO 2022065457 A1 WO2022065457 A1 WO 2022065457A1 JP 2021035193 W JP2021035193 W JP 2021035193W WO 2022065457 A1 WO2022065457 A1 WO 2022065457A1
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film
membrane
polymer
porous
porous membrane
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PCT/JP2021/035193
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French (fr)
Japanese (ja)
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憲樹 赤松
真一 中尾
誠弥 大野
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学校法人工学院大学
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Priority to CN202180064161.5A priority Critical patent/CN116194198A/en
Publication of WO2022065457A1 publication Critical patent/WO2022065457A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/40—Polymers of unsaturated acids or derivatives thereof, e.g. salts, amides, imides, nitriles, anhydrides, esters
    • B01D71/401—Polymers based on the polymerisation of acrylic acid, e.g. polyacrylate
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/08—Polysaccharides
    • B01D71/12—Cellulose derivatives
    • B01D71/14—Esters of organic acids
    • B01D71/16—Cellulose acetate
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/30—Polyalkenyl halides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/30—Polyalkenyl halides
    • B01D71/301—Polyvinylchloride
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/30—Polyalkenyl halides
    • B01D71/32—Polyalkenyl halides containing fluorine atoms
    • B01D71/34—Polyvinylidene fluoride
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/40—Polymers of unsaturated acids or derivatives thereof, e.g. salts, amides, imides, nitriles, anhydrides, esters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/40—Polymers of unsaturated acids or derivatives thereof, e.g. salts, amides, imides, nitriles, anhydrides, esters
    • B01D71/42—Polymers of nitriles, e.g. polyacrylonitrile
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/40—Polymers of unsaturated acids or derivatives thereof, e.g. salts, amides, imides, nitriles, anhydrides, esters
    • B01D71/42—Polymers of nitriles, e.g. polyacrylonitrile
    • B01D71/421—Polyacrylonitrile
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/56—Polyamides, e.g. polyester-amides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/66—Polymers having sulfur in the main chain, with or without nitrogen, oxygen or carbon only
    • B01D71/68—Polysulfones; Polyethersulfones
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/26—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a solid phase from a macromolecular composition or article, e.g. leaching out

Definitions

  • This disclosure relates to a porous membrane and a method for producing the same.
  • a membrane treatment technique for separating a solute such as a polymer dissolved in a liquid or a pollutant contained in the liquid with a porous membrane.
  • water treatment using membrane treatment technology include water purification treatment, sewage treatment, seawater desalination treatment, and industrial water treatment.
  • sample treatment containing a biomolecule can be mentioned.
  • the size of water treatment facilities using membrane treatment technology is rapidly increasing, and the utilization of membrane treatment technology in a wider range is expected in the future.
  • Fowling raises the power cost in membrane treatment, as well as the cost of cleaning and replacement, and has become a major problem in membrane treatment technology.
  • a film that suppresses fouling (low fouling film) is being actively developed.
  • (a) physical adhesion for example, Non-Patent Document 1.
  • (B) Grafts using ultraviolet rays or plasma for example, Non-Patent Document 2)
  • (c) ATRP: Atom transfer radical polymerization for example, Non-Patent Document 3
  • phase separation-induced film-forming has been proposed (for example, Non-Patent Document 4).
  • Non-Patent Document 1 K. Akamatsu et al, Ind. Eng. Chem. Res., 50 (2011) 12281-12284
  • Non-Patent Document 2 K. Akamatsu et al, Sep. Purif. Technol., 204 (2016) 298-303
  • Non-Patent Document 3 Y.C. Chiang et al, J. Membr. Sci., 339 (2009) 151-159
  • Non-Patent Document 4 G.V. Dizon et al, J. Membr. Sci., 550 (2018) 45-58
  • a technique for physically or chemically fixing a polymer having low fouling property to a porous membrane to the membrane surface (a) a technique for physically adhering the polymer is often a simple method, but the modified polymer is easily peeled off. .. Further, (b) a graft using ultraviolet rays or plasma, and (c) a method using ATRP have high film stability, but require a plurality of modification steps and are not practical. Further, in (d) phase separation-induced film formation, blending of various polymers has been studied, but expensive polymers are often used, which poses a problem in terms of cost.
  • the present disclosure aims to provide a porous membrane which can be manufactured inexpensively and easily and has high fouling resistance and a method for manufacturing the same.
  • the means for solving the above problems include the following aspects.
  • ⁇ 1> A porous membrane containing a blend polymer containing a base polymer and poly (2-methoxyethyl acrylate) and having a porous structure.
  • ⁇ 2> The porous structure according to ⁇ 1>, wherein the porous structure is an asymmetric porous structure in which the porosity increases as the pore diameter increases from one surface side to the other surface side of the porous membrane.
  • Quality membrane is one or more polymers selected from the group consisting of polyvinylidene fluoride, polysulfone, polyethersulfone, polyvinyl chloride, polyacrylonitrile, cellulose acetate, and polyamide.
  • the base polymer is one or more polymers selected from the group consisting of polyvinylidene fluoride, polysulfone, polyethersulfone, polyvinyl chloride, polyacrylonitrile, cellulose acetate, and polyamide ⁇ 4>.
  • ⁇ 6> The method for producing a porous membrane according to ⁇ 4> or ⁇ 5>, wherein the phase separation method is a non-solvent-induced phase separation method.
  • a porous membrane which can be manufactured inexpensively and easily and has high fouling resistance and a method for manufacturing the same are provided.
  • FIG. 3 It is a schematic diagram which shows an example of the manufacturing method of the porous membrane which concerns on this disclosure. It is a figure which shows the FT-IR (ATR method) spectrum of the membrane surface of the porous membrane produced in the Example and the comparative example. 3 is an FE-SEM image showing the surface of the porous membrane produced in Examples and Comparative Examples. 3 is an FE-SEM image showing a cross section of the porous membrane produced in Examples and Comparative Examples. It is a graph which shows the relationship between the pure water permeability coefficient and the film thickness with respect to the PMEA blend ratio. It is a graph which shows the bovine serum albumin (BSA) permeation test result.
  • BSA bovine serum albumin
  • the present inventors focused on the MEA polymer developed as a biomaterial material, and modified the porous membrane with the MEA polymer by a plasma graft polymerization method. , It has been found that a porous film having excellent fouling suppression can be produced.
  • the plasma graft polymerization method has a problem that the modification process is complicated and it is difficult to scale up. Therefore, as a result of repeated studies on a method for more easily producing a porous film having excellent fouling suppression, a film-forming solution in which a base polymer and poly (2-methoxyethyl acrylate) were dissolved in a specific good solvent was used. It has been found that when a porous membrane is produced by a phase separation-induced membrane-forming method, a porous membrane having high fouling resistance can be produced inexpensively and easily.
  • the porous membrane according to the present disclosure is a porous membrane containing a blend polymer containing a base polymer and poly (2-methoxyethyl acrylate) and having a porous structure.
  • the base polymer has the highest content (% by mass) in the porous membrane according to the present disclosure, and is the polymer that is the base of the porous membrane.
  • the base polymer is not particularly limited as long as it can form a porous membrane as a blend polymer with the MEA polymer.
  • Examples of the base polymer include polyvinylidene fluoride, polysulfone, polyethersulfone, polyvinyl chloride, polyacrylonitrile, cellulose acetate, polyamide and the like.
  • the base polymer contained in the porous membrane may be one kind or two or more kinds.
  • PVDF polyvinylidene fluoride
  • As the base polymer polyvinylidene fluoride (PVDF) is preferable from the viewpoints of film forming property, compatibility with MEA polymer, film strength, availability and the like.
  • PVDF has excellent film-forming properties and excellent mechanical and chemical durability, and is therefore suitable as a material for the porous film according to the present disclosure.
  • homopolymers or copolymers of PVDF can be used.
  • the copolymer include polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride-chlorotrifluoroethylene copolymer and the like.
  • the molecular weight of PVDF is not particularly limited, but for example, a polymer having a weight average molecular weight of 10,000 to 10 million can be used.
  • the content (% by mass) of the base polymer in the porous membrane according to the present disclosure depends on the type of the base polymer, but when PVDF is used, for example, it is 55 to 95 mass from the viewpoint of film forming property, film strength and the like. %, which may be 65 to 85% by mass.
  • MEA polymer Poly (2-methoxyethyl acrylate)
  • MEA polymer Poly (2-methoxyethyl acrylate
  • MEA polymer is a polymer obtained by polymerizing 2-methoxyethyl acrylate.
  • MEA polymers are inexpensive materials and are also available on the market.
  • the MEA polymer may be a homopolymer of 2-methoxyethyl acrylate or a copolymer of 2-methoxyethyl acrylate and another monomer.
  • the molecular weight of the MEA polymer is not particularly limited, but for example, a MEA polymer having a weight average molecular weight of 10,000 to 5 million can be used.
  • the content (mass%) of the MEA polymer in the porous membrane according to the present disclosure is, for example, 5 to 45% by mass, and 15 to 45% from the viewpoint of film forming property, film strength, etc., although it depends on the type of the base polymer. It may be 35% by mass.
  • the porous membrane according to the present disclosure may contain components (other components) other than the base polymer and the MEA polymer as long as the fouling resistance is not significantly impaired.
  • Other components include polymers other than base polymers and MEA polymers and additives. Examples of other components include ethylene glycol, diethylene glycol, tetraethylene glycol, polyethylene glycol, polyvinylpyrrolidone, glycerin and the like as hydrophilic substances for controlling the pore size, and one or more of these may be contained. ..
  • the shape, size, distribution, and morphology of the pores of the porous structure of the porous membrane according to the present disclosure are not particularly limited. Although it depends on the use of the porous membrane, for example, when it is used as a separation membrane, the porosity increases as the pore diameter (average) increases from one surface side to the other surface side of the porous membrane.
  • An asymmetric porous membrane having an asymmetric porous structure is preferable.
  • the asymmetric porous membrane is typically a porous membrane having a sponge-like porous structure on one side and a dense porous structure with small pores on the other side. By making the dense layer function as a separation surface, it can be used as a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane or a reverse osmosis membrane.
  • the pore diameter is not particularly limited, but one surface side of the asymmetric porous membrane is 1 to 1000 ⁇ m, and the other surface side is 0.001 to 50 ⁇ m.
  • the pore size is measured by observing each surface of the porous film with a field emission scanning electron microscope (FE-SEM), measuring the maximum diameter of each of 50 randomly selected holes, and calculating by number averaging. Will be done.
  • FE-SEM field emission scanning electron microscope
  • the porosity of the porous membrane according to the present disclosure is not particularly limited.
  • the porosity greatly changes between the dense layer that functions as a separation surface and the support layer that functions as a support portion on the opposite side of the dense layer. Therefore, the porosity cannot be unequivocally determined, but the average porosity of the entire film is, for example, 25 to 85%.
  • the thickness of the porous membrane according to the present disclosure is not particularly limited, but if the film thickness is too thin, it is easily damaged during manufacturing, film installation, or use, and if it is too thick, it becomes difficult for the solution to permeate, resulting in power costs. It can be high.
  • the film thickness of the porous membrane according to the present disclosure may be selected depending on the intended use of the membrane and the like, and is, for example, 10 ⁇ m to 1.0 mm. The film thickness is calculated as an average value of the thickness measured at five randomly selected points.
  • the method for producing a porous membrane according to the present disclosure includes a step of preparing a membrane-forming solution containing a base polymer, poly (2-methoxyethyl acrylate), and a solvent, and a step of preparing a membrane-forming solution. It comprises a step of precipitating a porous membrane by a phase separation method using the membrane-forming solution.
  • Step to prepare the film-forming solution First, a film-forming solution containing a base polymer, poly (2-methoxyethyl acrylate), and a solvent is prepared.
  • a base polymer and poly (2-methoxyethyl acrylate) used as the film material the above-mentioned materials can be used.
  • the solvent is not particularly limited as long as it can dissolve the base polymer and poly (2-methoxyethyl acrylate).
  • the solvent when PVDF is used as the base polymer, the solvent is limited because PVDF has excellent physical and chemical durability, but N-methyl-2-pyrrolidone (NMP) is a good solvent in which both PVDF and PMEA are dissolved. ) Can be preferably used.
  • NMP N-methyl-2-pyrrolidone
  • a good solvent can be selected based on the Hansen solubility parameter.
  • the solvent other than NMP include dimethylacetamide.
  • the solution may contain the above-mentioned "other components" as components other than the base polymer and poly (2-methoxyethyl acrylate).
  • the mass ratio of the base polymer to the MEA polymer (base polymer: MEA polymer) in the film-forming solution is preferably 30: 1 to 1: 1 and more preferably 5: 1 to 2: 1.
  • the content of the base polymer in the film-forming solution is, for example, 10 to 30% by mass, preferably 15 to 25% by mass.
  • the content of the MEA polymer in the film-forming solution is, for example, 1 to 10% by mass, preferably 3 to 8% by mass.
  • Step of precipitating a porous membrane by the phase separation method The porous membrane is precipitated by the phase separation method using the membrane-forming solution.
  • the phase separation method is a film-forming technique for producing an asymmetric film, and examples thereof include the following methods.
  • NIPS Non-solvent Induced Phase Separation
  • TIPS Thermally Induced Phase Separation
  • VIPS Vapor Induced Phase Separation
  • VIPS Vapor Induced Phase Separation
  • FIG. 1 shows an example of a method for producing a porous membrane according to the present disclosure by NIPS.
  • a film-forming solution (cast liquid) 14 composed of a base polymer (film material polymer), a MEA polymer, a solvent (good solvent), an additive and the like is applied to a glass plate 10.
  • a coater 12 to thinly stretch (cast) on a flat surface such as.
  • the thin film 16 formed on the glass plate 10 When the thin film 16 formed on the glass plate 10 is left in this state for a certain period of time (about several seconds to several minutes), evaporation of a good solvent proceeds only on the surface, the polymer concentration on the surface increases, and the thin film becomes stretched.
  • the thin film 16 is immersed in the coagulating solution (poor solvent) together with the glass plate 10 at once from this state, and the poor solvent enters from the film surface to be in a mixed state with the good solvent.
  • the solubility of the polymer decreases and it solidifies (phase separation induction).
  • the good solvent escapes toward the poor solvent, and holes are formed in the solidified polymer.
  • a sponge-like porous structure is formed on the surface layer side because the polymer concentration is high when it is dried and the solidification progresses at once on the surface layer side, and a dense layer is formed on the inner layer side. Asymmetric film is formed. Then, as shown in FIG. 1 (D), the whitened porous membrane 20 can be recovered after a few minutes.
  • the method when the porous film is precipitated by NIPS, the method is not limited to the above method, and for example, a method of continuously casting on a roll-shaped non-woven fabric, allowing it to slip through a poor solvent and winding it up is adopted. Can be mass-produced.
  • the poor solvent for precipitating the porous film according to the present disclosure may be selected according to the type of the base polymer and the good solvent. For example, when PVDF is used as the base polymer and NMP is used as the good solvent, water can be used as the poor solvent.
  • porous membrane low fouling membrane
  • the use of the porous membrane according to the present disclosure is not particularly limited, but for example, fouling can be effectively suppressed by using it for water treatment, and not only the membrane formation cost but also the running cost and the membrane replacement cost are suppressed. Can also make a great contribution to.
  • porous membrane and the method for producing the porous membrane according to the present disclosure will be described in more detail with reference to examples. However, each of these examples does not limit the present invention.
  • the reagents used in the examples are as follows. Poly (vinylidene fluoride) [PVDF] (Solef (registered trademark) 6010., SOLVAY., Mw: 300,000-320,000 [Da] powerer) 1-Methyl-2-pyrrolidone [NMP] (Wako Special Grade, Fujifilm Wako Pure Chemical Industries, Ltd.) -Deionized water [DI-water (pure water)] (Elix (registered trademark) Essential 5 (UV)., Millipore.) ⁇ 2-Methoxyethyl Acrylate [MEA] (Wako First Class, Wako Pure Chemical Industries, Ltd.) ⁇ 2,2'-Azobis (isobutyronirile) [AIBN] (Wako Special Grade, Fujifilm Wako Pure Chemical Industries, Ltd.) ⁇ 1,4-Dioxane [1,4-dioxane] (special grade reagent, Wako Pure Chemical Industries, Ltd.) ⁇
  • PVDF polyvinylidene fluoride
  • PMEA Poly (2-methoxyethyl acrylate)
  • Distilled MEA monomer 20 [g] and 1,4-dioxane 100 [g] were placed in an eggplant-shaped flask, and nitrogen bubbling was performed for 30 [min]. After the bubbling was completed, AIBN 0.08 [g] and a small stirrer were added, and radical polymerization was carried out at a polymerization temperature of 75 [° C.] and a polymerization time of 24 [h].
  • the polymer insoluble in hexane was precipitated by pouring the polymerized solution into a beaker containing 500 [mL] of hexane. At this time, the entire mixed solution became cloudy, but since a white precipitate having a high polymerization amount was present at the bottom of the beaker, the precipitate was obtained as the target polymer.
  • the cloudy solution containing hexane and 1,4-dioxane other than the precipitate (polymer) was removed, and the polymer was completely dissolved in THF10 [mL]. If it did not dissolve in 10 [mL], another 10 [mL] was added. Hexane, which was 15 times the amount of THF required to dissolve the polymer, was placed in the solution to precipitate the polymer again. By repeating this operation a total of 3 times, a MEA polymer (PMEA) was obtained.
  • FIG. 3 is an FE-SEM image showing the surface of each film (the side opposite to the glass substrate at the time of casting)
  • FIG. 4 is an FE-SEM image showing a cross section of each film.
  • Each film has an asymmetric porous structure in which the porous structure differs between one surface side (the side opposite to the glass substrate at the time of casting) and the other surface side. Further, as can be seen in FIG. 4, it can be seen that the void portion of the film blended with PMEA is larger than that of the film not blended with PMEA.
  • FIG. 5 is a graph showing the relationship between the pure water permeability coefficient Lp and the film thickness with respect to the PMEA blend ratio. The higher the Lp, the smaller the membrane resistance, and the lower the pressure, the more water permeates, which is advantageous for membrane separation.
  • the water permeability of the membrane is significantly improved by blending PMEA.
  • PMEA3 has the largest pure water permeability coefficient Lp
  • PMEA5 and PMEA7 have a lower pure water permeability coefficient Lp. It is presumed that this is not due to the increase in the proportion of PMEA blend, but due to the high total polymer content (blended polymer content).
  • the film blended with PMEA can exhibit high water permeability without reducing the film thickness, that is, without lowering the film strength. It is considered that the change in the internal structure of the membrane (Fig. 4) greatly affected the increase in the pure water permeability coefficient by blending PMEA.
  • BSA Bovine serum albumin
  • FIG. 6 is a graph showing the results of the BSA permeation test. It can be seen that by exchanging pure water with a 1000 ppm BSA aqueous solution after the start of the test, the water permeability of the membrane not blended with PMEA is sharply lowered, and the low fouling property is low. On the other hand, although the water permeability of the membrane blended with PMEA, particularly PMEA3, 5 and 7, was slightly deteriorated, it was almost constant until the end of the test, and it can be seen that the membrane has excellent low fouling property. Further, it can be seen that as the proportion of the PMEA blend increases, the low fouling property becomes higher.
  • the blending of PMEA showed a change in the internal structure of the membrane and an improvement in water permeability. Furthermore, it was clarified that the increase in the PMEA / PVDF blend ratio contributed to the presence of a large amount of PMEA on the film surface. Therefore, the PMEA-blended PVDF porous membrane can be expected to suppress fouling.
  • the porous membrane according to the present disclosure can suppress fouling in various applications, and may open up new applications such as protein fractionation in addition to water treatment.
  • it is considered to be excellent in low fouling property against protein-like substances or polysaccharide-like substances.

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  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
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  • Separation Using Semi-Permeable Membranes (AREA)
  • Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)

Abstract

Provided is a porous film that has a porous structure and contains a polymer blend comprising a base polymer and poly(2-methoxyethyl acrylate). Also provided is a method for producing a porous film, the method comprising a step for preparing a film-producing solution containing a base polymer, poly(2-methoxyethyl acrylate), and a solvent, and a step for depositing a porous film by phase separation using the film-producing solution.

Description

多孔質膜及びその製造方法Porous membrane and its manufacturing method
　本開示は、多孔質膜及びその製造方法に関する。 This disclosure relates to a porous membrane and a method for producing the same.
　液体に溶解した高分子などの溶質又は液体に含まれる汚濁物などを多孔質膜によって分離する膜処理技術がある。膜処理技術を利用した水処理として、例えば、浄水処理、下排水処理、海水淡水化処理、工業用水処理など挙げられる。水処理以外に、例えば生体分子を含有するサンプル処理が挙げられる。
　現在、膜処理技術を用いた水処理施設の大型化が急速に進んでおり、今後より広い範囲における膜処理技術の活用が有望視されている。
　一方で、膜を長期間用いることにより膜が汚れて膜性能の劣化（ファウリング）が生じる。ファウリングは膜処理における動力費、さらに洗浄及び交換のコストを押し上げ、膜処理技術において大きな問題となっている。 There is a membrane treatment technique for separating a solute such as a polymer dissolved in a liquid or a pollutant contained in the liquid with a porous membrane. Examples of water treatment using membrane treatment technology include water purification treatment, sewage treatment, seawater desalination treatment, and industrial water treatment. In addition to water treatment, for example, sample treatment containing a biomolecule can be mentioned.
At present, the size of water treatment facilities using membrane treatment technology is rapidly increasing, and the utilization of membrane treatment technology in a wider range is expected in the future.
On the other hand, when the film is used for a long period of time, the film becomes dirty and the film performance deteriorates (fouling). Fowling raises the power cost in membrane treatment, as well as the cost of cleaning and replacement, and has become a major problem in membrane treatment technology.
　そこで、ファウリングを抑制する膜（低ファウリング膜）の開発が盛んに行われている。例えば、多孔質膜にファウリングを抑制する性質（低ファウリング性）を有するポリマーを物理的又は化学的に膜面に固定する技術として、（ａ）物理的付着（例えば非特許文献１）、（ｂ）紫外線又はプラズマを利用したグラフト（例えば非特許文献２）、（ｃ）ＡＴＲＰ：原子移動ラジカル重合（例えば非特許文献３）による方法が提案されている。
　また、膜原料に低ファウリングポリマーを含有させる製膜技術として、（ｄ）相分離誘起製膜が提案されている（例えば非特許文献４）。 Therefore, a film that suppresses fouling (low fouling film) is being actively developed. For example, as a technique for physically or chemically fixing a polymer having a property of suppressing fouling (low fouling property) to a porous film, (a) physical adhesion (for example, Non-Patent Document 1). (B) Grafts using ultraviolet rays or plasma (for example, Non-Patent Document 2), (c) ATRP: Atom transfer radical polymerization (for example, Non-Patent Document 3) have been proposed.
Further, as a film-forming technique for incorporating a low fouling polymer into a film raw material, (d) phase separation-induced film-forming has been proposed (for example, Non-Patent Document 4).
　非特許文献１：K. Akamatsu et al, Ind. Eng. Chem. Res., 50 (2011) 12281-12284
　非特許文献２：K. Akamatsu et al, Sep. Purif. Technol., 204 (2018) 298-303
　非特許文献３：Y. C. Chiang et al, J. Membr. Sci., 339 (2009) 151-159
　非特許文献４：G. V. Dizon et al, J. Membr. Sci., 550 (2018) 45-58 Non-Patent Document 1: K. Akamatsu et al, Ind. Eng. Chem. Res., 50 (2011) 12281-12284
Non-Patent Document 2: K. Akamatsu et al, Sep. Purif. Technol., 204 (2018) 298-303
Non-Patent Document 3: Y.C. Chiang et al, J. Membr. Sci., 339 (2009) 151-159
Non-Patent Document 4: G.V. Dizon et al, J. Membr. Sci., 550 (2018) 45-58
　多孔質膜に低ファウリング性を有するポリマーを物理的又は化学的に膜面に固定する技術として、（ａ）物理的に付着させる技術は、簡便な手法が多いが、修飾ポリマーが剥離し易い。また、（ｂ）紫外線又はプラズマを利用したグラフト、（ｃ）ＡＴＲＰによる方法は、膜の安定性は高いが、複数の改質ステップを要し、実用性に乏しい。
　また、（ｄ）相分離誘起製膜は、様々なポリマーのブレンドが検討されているが、高価なポリマーを使用する場合が多く、コスト面の課題がある。 As a technique for physically or chemically fixing a polymer having low fouling property to a porous membrane to the membrane surface, (a) a technique for physically adhering the polymer is often a simple method, but the modified polymer is easily peeled off. .. Further, (b) a graft using ultraviolet rays or plasma, and (c) a method using ATRP have high film stability, but require a plurality of modification steps and are not practical.
Further, in (d) phase separation-induced film formation, blending of various polymers has been studied, but expensive polymers are often used, which poses a problem in terms of cost.
　本開示は、上記課題に鑑み、安価にかつ簡便に製造することが可能であり、ファウリング耐性の高い多孔質膜及びその製造方法を提供することを目的とする。 In view of the above problems, the present disclosure aims to provide a porous membrane which can be manufactured inexpensively and easily and has high fouling resistance and a method for manufacturing the same.
　上記課題を解決するための手段には、以下の態様が含まれる。
＜１＞　ベースポリマーとポリ（２－メトキシエチルアクリレート）とを含むブレンドポリマーを含有し、多孔構造を有する多孔質膜。
＜２＞　前記多孔構造が、前記多孔質膜の一方の面側から他方の面側に向けて孔径が大きくなるに伴い空隙率が大きくなっている非対称多孔構造である＜１＞に記載の多孔質膜。
＜３＞　前記ベースポリマーが、ポリフッ化ビニリデン、ポリスルホン、ポリエーテルスルホン、ポリ塩化ビニル、ポリアクリロニトリル、酢酸セルロース、及びポリアミドからなる群より選ばれる１種又は２種以上のポリマーである＜１＞又は＜２＞に記載の多孔質膜。
＜４＞　ベースポリマーと、ポリ（２－メトキシエチルアクリレート）と、溶媒と、を含む製膜溶液を準備する工程と、
　前記製膜溶液を用い、相分離法によって多孔質膜を析出させる工程と、
　を含む多孔質膜の製造方法。
＜５＞　前記ベースポリマーが、ポリフッ化ビニリデン、ポリスルホン、ポリエーテルスルホン、ポリ塩化ビニル、ポリアクリロニトリル、酢酸セルロース、及びポリアミドからなる群より選ばれる１種又は２種以上のポリマーである＜４＞に記載の多孔質膜の製造方法。
＜６＞　前記相分離法が、非溶媒誘起相分離法である＜４＞又は＜５＞に記載の多孔質膜の製造方法。 The means for solving the above problems include the following aspects.
<1> A porous membrane containing a blend polymer containing a base polymer and poly (2-methoxyethyl acrylate) and having a porous structure.
<2> The porous structure according to <1>, wherein the porous structure is an asymmetric porous structure in which the porosity increases as the pore diameter increases from one surface side to the other surface side of the porous membrane. Quality membrane.
<3> The base polymer is one or more polymers selected from the group consisting of polyvinylidene fluoride, polysulfone, polyethersulfone, polyvinyl chloride, polyacrylonitrile, cellulose acetate, and polyamide. <1> or The porous film according to <2>.
<4> A step of preparing a film-forming solution containing a base polymer, poly (2-methoxyethyl acrylate), and a solvent, and
A step of precipitating a porous membrane by a phase separation method using the membrane-forming solution, and
A method for producing a porous membrane including.
<5> The base polymer is one or more polymers selected from the group consisting of polyvinylidene fluoride, polysulfone, polyethersulfone, polyvinyl chloride, polyacrylonitrile, cellulose acetate, and polyamide <4>. The method for producing a porous membrane according to the above.
<6> The method for producing a porous membrane according to <4> or <5>, wherein the phase separation method is a non-solvent-induced phase separation method.
　本開示によれば、安価にかつ簡便に製造することが可能であり、ファウリング耐性の高い多孔質膜及びその製造方法が提供される。 According to the present disclosure, a porous membrane which can be manufactured inexpensively and easily and has high fouling resistance and a method for manufacturing the same are provided.
本開示に係る多孔質膜の製造方法の一例を示す概略図である。It is a schematic diagram which shows an example of the manufacturing method of the porous membrane which concerns on this disclosure. 実施例及び比較例で製造した多孔質膜の膜表面のＦＴ－ＩＲ（ＡＴＲ法）スペクトルを示す図である。It is a figure which shows the FT-IR (ATR method) spectrum of the membrane surface of the porous membrane produced in the Example and the comparative example. 実施例及び比較例で製造した多孔質膜の表面を示すＦＥ－ＳＥＭ画像である。3 is an FE-SEM image showing the surface of the porous membrane produced in Examples and Comparative Examples. 実施例及び比較例で製造した多孔質膜の断面を示すＦＥ－ＳＥＭ画像である。3 is an FE-SEM image showing a cross section of the porous membrane produced in Examples and Comparative Examples. ＰＭＥＡブレンド比に対する純水透過係数と膜厚の関係を示すグラフである。It is a graph which shows the relationship between the pure water permeability coefficient and the film thickness with respect to the PMEA blend ratio. ウシ血清アルブミン（ＢＳＡ）透過試験結果を示すグラフである。It is a graph which shows the bovine serum albumin (BSA) permeation test result.
　以下、本開示の実施形態について図面を参照しながら説明する。
　なお、本明細書において「～」を用いて表される数値範囲は、「～」の前後に記載される数値を下限値及び上限値として含む範囲を意味する。
　また、本明細書中の「工程」の用語は、独立した工程だけではなく、他の工程と明確に区別できない場合であっても、その工程の所期の目的が達成されれば本用語に含まれる。
　本開示において、ポリ（２－メトキシエチルアクリレート）を、「ＭＥＡポリマー」又は「ＰＭＥＡ」と称する場合がある。 Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.
In addition, the numerical range represented by using "-" in this specification means the range including the numerical values before and after "-" as the lower limit value and the upper limit value.
In addition, the term "process" in the present specification is not limited to an independent process, and even if it cannot be clearly distinguished from other processes, the term "process" will be used as long as the intended purpose of the process is achieved. included.
In the present disclosure, poly (2-methoxyethyl acrylate) may be referred to as "MEA polymer" or "PMEA".
　本発明者らは、本開示に係る多孔質膜の発明に先立ち、バイオマテリアル素材として開発されてきたＭＥＡポリマーに着目し、多孔質膜に対してプラズマグラフト重合法によってＭＥＡポリマーを修飾することで、ファウリング抑制に優れた多孔質膜を製造することができることを見出した。
　しかし、プラズマグラフト重合法は、修飾工程が複雑でスケールアップが困難といった問題がある。そこで、より簡便にファウリング抑制に優れた多孔質膜を製造する方法について検討を重ねた結果、ベースポリマーとポリ（２－メトキシエチルアクリレート）を特定の良溶媒に溶解させた製膜溶液を用い、相分離誘起製膜手法により多孔質膜を作製すると、安価にかつ簡便にファウリング耐性の高い多孔質膜を製造することができることを見出した。 Prior to the invention of the porous membrane according to the present disclosure, the present inventors focused on the MEA polymer developed as a biomaterial material, and modified the porous membrane with the MEA polymer by a plasma graft polymerization method. , It has been found that a porous film having excellent fouling suppression can be produced.
However, the plasma graft polymerization method has a problem that the modification process is complicated and it is difficult to scale up. Therefore, as a result of repeated studies on a method for more easily producing a porous film having excellent fouling suppression, a film-forming solution in which a base polymer and poly (2-methoxyethyl acrylate) were dissolved in a specific good solvent was used. It has been found that when a porous membrane is produced by a phase separation-induced membrane-forming method, a porous membrane having high fouling resistance can be produced inexpensively and easily.
＜多孔質膜＞
　本開示に係る多孔質膜は、ベースポリマーとポリ（２－メトキシエチルアクリレート）とを含むブレンドポリマーを含有し、多孔構造を有する多孔質膜である。 <Porous membrane>
The porous membrane according to the present disclosure is a porous membrane containing a blend polymer containing a base polymer and poly (2-methoxyethyl acrylate) and having a porous structure.
　ベースポリマーは、本開示に係る多孔質膜において含有量（質量％）が最も多く、多孔質膜のベースとなるポリマーである。ベースポリマーは、ＭＥＡポリマーとのブレンドポリマーとして多孔質膜を構成することができれば特に限定されない。ベースポリマーとして、例えば、ポリフッ化ビニリデン、ポリスルホン、ポリエーテルスルホン、ポリ塩化ビニル、ポリアクリロニトリル、酢酸セルロース、ポリアミドなどが挙げられる。多孔質膜に含まれるベースポリマーは１種でも２種以上でもよい。ベースポリマーとしては、製膜性、ＭＥＡポリマーとの相溶性、膜強度、入手性などの観点からポリフッ化ビニリデン（ＰＶＤＦ）が好ましい。 The base polymer has the highest content (% by mass) in the porous membrane according to the present disclosure, and is the polymer that is the base of the porous membrane. The base polymer is not particularly limited as long as it can form a porous membrane as a blend polymer with the MEA polymer. Examples of the base polymer include polyvinylidene fluoride, polysulfone, polyethersulfone, polyvinyl chloride, polyacrylonitrile, cellulose acetate, polyamide and the like. The base polymer contained in the porous membrane may be one kind or two or more kinds. As the base polymer, polyvinylidene fluoride (PVDF) is preferable from the viewpoints of film forming property, compatibility with MEA polymer, film strength, availability and the like.
　ＰＶＤＦは、製膜性に優れ、かつ、機械的および化学的な耐久性に優れているので、本開示に係る多孔質膜の素材として好適である。
　ＰＶＤＦとしては、ＰＶＤＦのホモポリマー又はコポリマーを用いることができる。コポリマーとしては、ポリビニリデンフルオライド－ヘキサフルオロプロピレン共重合体、ポリビニリデンフルオライド－クロロトリフルオロエチレン共重合体などを挙げることができる。
　ＰＶＤＦの分子量は特に限定されないが、例えば、重量平均分子量で１万～１０００万のポリマーを使用することができる。 PVDF has excellent film-forming properties and excellent mechanical and chemical durability, and is therefore suitable as a material for the porous film according to the present disclosure.
As PVDF, homopolymers or copolymers of PVDF can be used. Examples of the copolymer include polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride-chlorotrifluoroethylene copolymer and the like.
The molecular weight of PVDF is not particularly limited, but for example, a polymer having a weight average molecular weight of 10,000 to 10 million can be used.
　本開示に係る多孔質膜におけるベースポリマーの含有量（質量％）は、ベースポリマーの種類にもよるが、例えばＰＶＤＦを用いる場合は、製膜性、膜強度などの観点から、５５～９５質量％であり、６５～８５質量％でもよい。 The content (% by mass) of the base polymer in the porous membrane according to the present disclosure depends on the type of the base polymer, but when PVDF is used, for example, it is 55 to 95 mass from the viewpoint of film forming property, film strength and the like. %, Which may be 65 to 85% by mass.
（ポリ（２－メトキシエチルアクリレート））
　ポリ（２－メトキシエチルアクリレート）（以下、ＭＥＡポリマー）は、２－メトキシエチルアクリレートを重合させたポリマーである。
　ＭＥＡポリマーは安価な材料であり、市場で入手することも可能である。ＭＥＡポリマーは、２－メトキシエチルアクリレートの単独重合体でもよいし、２－メトキシエチルアクリレートと、他のモノマーとの共重合体であってもよい。 (Poly (2-methoxyethyl acrylate))
Poly (2-methoxyethyl acrylate) (hereinafter, MEA polymer) is a polymer obtained by polymerizing 2-methoxyethyl acrylate.
MEA polymers are inexpensive materials and are also available on the market. The MEA polymer may be a homopolymer of 2-methoxyethyl acrylate or a copolymer of 2-methoxyethyl acrylate and another monomer.
　ＭＥＡポリマーの分子量は特に限定されないが、例えば、重量平均分子量で１万～５００万のＭＥＡポリマーを使用することができる。 The molecular weight of the MEA polymer is not particularly limited, but for example, a MEA polymer having a weight average molecular weight of 10,000 to 5 million can be used.
　本開示に係る多孔質膜におけるＭＥＡポリマーの含有量（質量％）は、ベースポリマーの種類にもよるが、製膜性、膜強度などの観点から、例えば５～４５質量％であり、１５～３５質量％でもよい。 The content (mass%) of the MEA polymer in the porous membrane according to the present disclosure is, for example, 5 to 45% by mass, and 15 to 45% from the viewpoint of film forming property, film strength, etc., although it depends on the type of the base polymer. It may be 35% by mass.
（その他の成分）
　本開示に係る多孔質膜は、ファウリング耐性を著しく損なわない範囲でベースポリマー及びＭＥＡポリマー以外の成分（その他の成分）を含んでもよい。
　その他の成分としては、ベースポリマー及びＭＥＡポリマー以外のポリマー並びに添加剤が挙げられる。
　その他の成分としては、例えば、孔径制御のための親水性物質として、エチレングリコール、ジエチレングリコール、テトラエチレングリコール、ポリエチレングリコール、ポリビニルピロリドン、グリセリン等が挙げられ、これらを１種又は２種以上含んでもよい。 (Other ingredients)
The porous membrane according to the present disclosure may contain components (other components) other than the base polymer and the MEA polymer as long as the fouling resistance is not significantly impaired.
Other components include polymers other than base polymers and MEA polymers and additives.
Examples of other components include ethylene glycol, diethylene glycol, tetraethylene glycol, polyethylene glycol, polyvinylpyrrolidone, glycerin and the like as hydrophilic substances for controlling the pore size, and one or more of these may be contained. ..
（多孔構造）
　本開示に係る多孔質膜の多孔構造の孔の形状、大きさ、分布、形態は特に限定されない。多孔質膜の用途にもよるが、例えば、分離膜として使用する場合、多孔質膜の一方の面側から他方の面側に向けて孔径（平均）が大きくなるに伴い空隙率が大きくなっている非対称多孔構造を有する非対称多孔質膜が好ましい。非対称多孔質膜は、典型的には、一方の面側はスポンジ状の多孔構造を持ち、他方の面側は孔の小さい緻密な多孔構造を持った多孔質膜である。緻密な層を分離面として機能させることで精密ろ過膜、限外ろ過膜、ナノろ過膜又は逆浸透膜として用いることができる。 (Porosity structure)
The shape, size, distribution, and morphology of the pores of the porous structure of the porous membrane according to the present disclosure are not particularly limited. Although it depends on the use of the porous membrane, for example, when it is used as a separation membrane, the porosity increases as the pore diameter (average) increases from one surface side to the other surface side of the porous membrane. An asymmetric porous membrane having an asymmetric porous structure is preferable. The asymmetric porous membrane is typically a porous membrane having a sponge-like porous structure on one side and a dense porous structure with small pores on the other side. By making the dense layer function as a separation surface, it can be used as a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane or a reverse osmosis membrane.
　孔径は特に限定されないが、非対称多孔質膜の一方の面側は１～１０００μｍであり、他方の面側は０．００１～５０μｍである。なお、孔径の測定は、多孔質膜の各面を電界放出型走査電子顕微鏡（ＦＥ－ＳＥＭ）で観察し、無作為に選んだ５０個の各孔の最大径を測定して数平均によって算出される。 The pore diameter is not particularly limited, but one surface side of the asymmetric porous membrane is 1 to 1000 μm, and the other surface side is 0.001 to 50 μm. The pore size is measured by observing each surface of the porous film with a field emission scanning electron microscope (FE-SEM), measuring the maximum diameter of each of 50 randomly selected holes, and calculating by number averaging. Will be done.
　また、本開示に係る多孔質膜の空隙率は特に限定されない。なお、本開示に係る多孔質膜が非対称多孔質膜の場合、分離面として機能する緻密層と緻密層の反対側で支持部として機能する支持層とでは空隙率が大きく変化する。そのため、空隙率は一概に言えないが、膜全体の平均空隙率として、例えば、２５～８５％が挙げられる。 Further, the porosity of the porous membrane according to the present disclosure is not particularly limited. When the porous membrane according to the present disclosure is an asymmetric porous membrane, the porosity greatly changes between the dense layer that functions as a separation surface and the support layer that functions as a support portion on the opposite side of the dense layer. Therefore, the porosity cannot be unequivocally determined, but the average porosity of the entire film is, for example, 25 to 85%.
（膜厚）
　本開示に係る多孔質膜の厚みは特に限定されないが、膜厚が薄過ぎると、製造中、膜設置中、又は使用中に破損し易く、厚過ぎると溶液が透過し難くなり、動力費が高くなる可能性がある。本開示に係る多孔質膜の膜厚は、膜の用途などに応じて選択すればよいが、例えば、１０μｍ～１．０ｍｍである。なお、膜厚は、無作為に選んだ５箇所で測定した厚みの平均値として算出される。 (Film thickness)
The thickness of the porous membrane according to the present disclosure is not particularly limited, but if the film thickness is too thin, it is easily damaged during manufacturing, film installation, or use, and if it is too thick, it becomes difficult for the solution to permeate, resulting in power costs. It can be high. The film thickness of the porous membrane according to the present disclosure may be selected depending on the intended use of the membrane and the like, and is, for example, 10 μm to 1.0 mm. The film thickness is calculated as an average value of the thickness measured at five randomly selected points.
＜多孔質膜の製造方法＞
　本開示に係る多孔質膜の製造方法は、ベースポリマーと、ポリ（２－メトキシエチルアクリレート）と、溶媒と、を含む製膜溶液を準備する工程と、
　前記製膜溶液を用い、相分離法によって多孔質膜を析出させる工程と、を含む。 <Manufacturing method of porous membrane>
The method for producing a porous membrane according to the present disclosure includes a step of preparing a membrane-forming solution containing a base polymer, poly (2-methoxyethyl acrylate), and a solvent, and a step of preparing a membrane-forming solution.
It comprises a step of precipitating a porous membrane by a phase separation method using the membrane-forming solution.
（製膜溶液を準備する工程）
　まず、ベースポリマーと、ポリ（２－メトキシエチルアクリレート）と、溶媒と、を含む製膜溶液を準備する。
　膜素材となるベースポリマー及びポリ（２－メトキシエチルアクリレート）としては、前述した材料を用いることができる。 (Step to prepare the film-forming solution)
First, a film-forming solution containing a base polymer, poly (2-methoxyethyl acrylate), and a solvent is prepared.
As the base polymer and poly (2-methoxyethyl acrylate) used as the film material, the above-mentioned materials can be used.
　溶媒は、ベースポリマー及びポリ（２－メトキシエチルアクリレート）を溶解することができれば特に限定されない。例えば、ベースポリマーとしてＰＶＤＦを用いる場合は、ＰＶＤＦは物理的及び化学的耐久性に優れるため、溶媒は限られるが、ＰＶＤＦとＰＭＥＡがともに溶解する良溶媒として、Ｎ－メチル－２－ピロリドン（ＮＭＰ）を好適に用いることができる。
　なお、ベースポリマーとして、ＰＶＤＦ以外のポリマーを用いる場合、例えば、ハンセン溶解度パラメータに基づいて良溶媒を選択することができる。
　ＮＭＰ以外の溶媒として、例えば、ジメチルアセトアミドが挙げられる。
　溶液には、ベースポリマー及びポリ（２－メトキシエチルアクリレート）以外の成分として、既述の「その他の成分」を含んでもよい。 The solvent is not particularly limited as long as it can dissolve the base polymer and poly (2-methoxyethyl acrylate). For example, when PVDF is used as the base polymer, the solvent is limited because PVDF has excellent physical and chemical durability, but N-methyl-2-pyrrolidone (NMP) is a good solvent in which both PVDF and PMEA are dissolved. ) Can be preferably used.
When a polymer other than PVDF is used as the base polymer, for example, a good solvent can be selected based on the Hansen solubility parameter.
Examples of the solvent other than NMP include dimethylacetamide.
The solution may contain the above-mentioned "other components" as components other than the base polymer and poly (2-methoxyethyl acrylate).
　製膜溶液は、ＭＥＡポリマーのブレンド比が大きいほど、膜中のＭＥＡポリマーの割合が大きくなり、透水性能が高い多孔質膜を製造し易い。ただし、ベースポリマーの割合が低くなると膜強度が低下する。また、製膜溶液における総ポリマー濃度が低すぎると膜強度が低下し、高すぎると透過性能が低い多孔質膜となる。
　よって製膜溶液におけるベースポリマーとＭＥＡポリマーの質量比（ベースポリマー：ＭＥＡポリマー）は、３０：１～１：１が好ましく、５：１～２：１がより好ましい。
　また、製膜溶液におけるベースポリマーの含有量は、例えば、１０～３０質量％であり、望ましくは１５～２５質量％である。また、製膜溶液におけるＭＥＡポリマーの含有量は、例えば、１～１０質量％であり、望ましくは３～８質量％である。 In the membrane-forming solution, the larger the blend ratio of the MEA polymer, the larger the proportion of the MEA polymer in the membrane, and it is easy to produce a porous membrane having high water permeability. However, the lower the proportion of the base polymer, the lower the film strength. Further, if the total polymer concentration in the membrane-forming solution is too low, the membrane strength is lowered, and if it is too high, the permeation performance is low, resulting in a porous membrane.
Therefore, the mass ratio of the base polymer to the MEA polymer (base polymer: MEA polymer) in the film-forming solution is preferably 30: 1 to 1: 1 and more preferably 5: 1 to 2: 1.
The content of the base polymer in the film-forming solution is, for example, 10 to 30% by mass, preferably 15 to 25% by mass. The content of the MEA polymer in the film-forming solution is, for example, 1 to 10% by mass, preferably 3 to 8% by mass.
（相分離法によって多孔質膜を析出させる工程）
　前記製膜溶液を用い、相分離法によって多孔質膜を析出させる。
　相分離法は非対称膜を作製するための製膜技術であり、例えば、以下の方法が挙げられる。
（Ａ）非溶媒誘起相分離法（Ｎｏｎ－ｓｏｌｖｅｎｔ　Ｉｎｄｕｃｅｄ　Ｐｈａｓｅ　Ｓｅｐａｒａｔｉｏｎ：ＮＩＰＳ）
　ＮＩＰＳは、非溶媒（溶媒：可溶、ポリマー：不溶）中で溶液の相互拡散によって相分離を誘発する方法である。
（Ｂ）熱誘起相分離法（Ｔｈｅｒｍａｌｌｙ　Ｉｎｄｕｃｅｄ　Ｐｈａｓｅ　Ｓｅｐａｒａｔｉｏｎ：ＴＩＰＳ）
　ＴＩＰＳは、キャスト後の溶液を加温または冷却することにより相分離を誘発する方法である。
（Ｃ）水蒸気誘起相分離法（Ｖａｐｏｒ　Ｉｎｄｕｃｅｄ　Ｐｈａｓｅ　Ｓｅｐａｒａｔｉｏｎ：ＶＩＰＳ）
　ＶＩＰＳは、湿度調整可能な空間でキャスト液と水蒸気を接触させ、相分離を誘発する方法である。 (Step of precipitating a porous membrane by the phase separation method)
The porous membrane is precipitated by the phase separation method using the membrane-forming solution.
The phase separation method is a film-forming technique for producing an asymmetric film, and examples thereof include the following methods.
(A) Non-solvent Induced Phase Separation (NIPS)
NIPS is a method of inducing phase separation by mutual diffusion of solutions in a non-solvent (solvent: soluble, polymer: insoluble).
(B) Thermally Induced Phase Separation (TIPS)
TIPS is a method of inducing phase separation by heating or cooling the cast solution.
(C) Vapor Induced Phase Separation (VIPS)
VIPS is a method of inducing phase separation by bringing the cast liquid and water vapor into contact with each other in a humidity-adjustable space.
　本開示に係る多孔質膜の製造方法では、相分離法として、ＮＩＰＳ、ＴＩＰＳ、又はＶＩＰＳのいずれの方法を採用してもよい。ここで、ＮＩＰＳの一例について説明する。図１は、本開示に係る多孔質膜をＮＩＰＳによって製造する方法の一例を示している。
　図１（Ａ）及び（Ｂ）に示すように、まず、ベースポリマー（膜素材ポリマー）、ＭＥＡポリマー、溶媒（良溶媒）、添加剤等からなる製膜溶液（キャスト液）１４をガラス板１０等の平たんな面上にコーター１２を用いて薄く引き延ばす（キャスト）。
　ガラス板１０上に形成した薄膜１６を一定時間（数秒～数分程度）この状態に置いておくと表面だけ良溶媒の蒸発が進み、表面のポリマー濃度が高まり薄膜が張った状態になる。
　次いで、図１（Ｃ）に示すように、この状態から一気にガラス板１０とともに薄膜１６を凝固液（貧溶媒）に漬け込み、膜表面から貧溶媒が進入し良溶媒と混合状態になることで、ポリマーの溶解性が低下し固化する（相分離誘起）。
　また、良溶媒は貧溶媒の方へ抜け出していき、固化した高分子ポリマーに抜け孔ができる。表層側には乾燥状態にしたときにポリマー濃度が濃くなっていることと、表層側で一気に固化が進行することから緻密な層ができ、内部の方はゆっくり固化することからスポンジ状の多孔構造の非対称膜ができる。そして、図１（Ｄ）に示すように、数分後には白色化した多孔質膜２０を回収できる。 In the method for producing a porous membrane according to the present disclosure, any method of NIPS, TIPS, or VIPS may be adopted as the phase separation method. Here, an example of NIPS will be described. FIG. 1 shows an example of a method for producing a porous membrane according to the present disclosure by NIPS.
As shown in FIGS. 1 (A) and 1 (B), first, a film-forming solution (cast liquid) 14 composed of a base polymer (film material polymer), a MEA polymer, a solvent (good solvent), an additive and the like is applied to a glass plate 10. Use a coater 12 to thinly stretch (cast) on a flat surface such as.
When the thin film 16 formed on the glass plate 10 is left in this state for a certain period of time (about several seconds to several minutes), evaporation of a good solvent proceeds only on the surface, the polymer concentration on the surface increases, and the thin film becomes stretched.
Next, as shown in FIG. 1 (C), the thin film 16 is immersed in the coagulating solution (poor solvent) together with the glass plate 10 at once from this state, and the poor solvent enters from the film surface to be in a mixed state with the good solvent. The solubility of the polymer decreases and it solidifies (phase separation induction).
In addition, the good solvent escapes toward the poor solvent, and holes are formed in the solidified polymer. A sponge-like porous structure is formed on the surface layer side because the polymer concentration is high when it is dried and the solidification progresses at once on the surface layer side, and a dense layer is formed on the inner layer side. Asymmetric film is formed. Then, as shown in FIG. 1 (D), the whitened porous membrane 20 can be recovered after a few minutes.
　本開示においてＮＩＰＳによって多孔質膜を析出させる場合、上記方法に限定されず、例えば、ロール状の不織布上に連続的にキャストし、貧溶媒中を潜り抜けさせて巻き取る方法を採用することで大量生産することができる。
　また、本開示に係る多孔質膜を析出させる際の貧溶媒としては、ベースポリマー、良溶媒の種類に応じて選択すればよい。例えば、ベースポリマーとしてＰＶＤＦ、良溶媒としてＮＭＰを用いる場合、貧溶媒としては水を用いることができる。 In the present disclosure, when the porous film is precipitated by NIPS, the method is not limited to the above method, and for example, a method of continuously casting on a roll-shaped non-woven fabric, allowing it to slip through a poor solvent and winding it up is adopted. Can be mass-produced.
Further, the poor solvent for precipitating the porous film according to the present disclosure may be selected according to the type of the base polymer and the good solvent. For example, when PVDF is used as the base polymer and NMP is used as the good solvent, water can be used as the poor solvent.
　上記方法により、安価にかつ簡便に、低ファウリング性に優れた多孔質膜（低ファウリング膜）を製造することができる。
　本開示に係る多孔質膜の用途は特に限定されないが、例えば、水処理に用いることでファウリングを効果的に抑制することができ、製膜コストだけでなく、ランニングコスト、膜交換コストの抑制にも大きく貢献できる。 By the above method, a porous membrane (low fouling membrane) having excellent low fouling property can be produced inexpensively and easily.
The use of the porous membrane according to the present disclosure is not particularly limited, but for example, fouling can be effectively suppressed by using it for water treatment, and not only the membrane formation cost but also the running cost and the membrane replacement cost are suppressed. Can also make a great contribution to.
　以下、本開示に係る多孔質膜及びその製造方法について、実施例を挙げてさらに具体的に説明する。ただし、これら各実施例は、本発明を制限するものではない。 Hereinafter, the porous membrane and the method for producing the porous membrane according to the present disclosure will be described in more detail with reference to examples. However, each of these examples does not limit the present invention.
（試薬）
　実施例で使用した試薬は以下のとおりである。
・Ｐｏｌｙ（ｖｉｎｙｌｉｄｅｎｅ　ｆｌｕｏｒｉｄｅ）［ＰＶＤＦ］（Ｓｏｌｅｆ（登録商標）６０１０．，ＳＯＬＶＡＹ．，Ｍｗ：３００，０００－３２０，０００［Ｄａ］　ｐｏｗｄｅｒ）
・１－Ｍｅｔｈｙｌ－２－ｐｙｒｒｏｌｉｄｏｎｅ［ＮＭＰ］（和光特級、富士フイルム和光純薬株式会社）
・Ｄｅｉｏｎｉｚｅｄ　ｗａｔｅｒ［ＤＩ－ｗａｔｅｒ（純水）］（Ｅｌｉｘ（登録商標）Ｅｓｓｅｎｔｉａｌ　５（ＵＶ）．，Ｍｉｌｌｉｐｏｒｅ．）
・２－Ｍｅｔｈｏｘｙｅｔｈｙｌ　Ａｃｒｙｌａｔｅ［ＭＥＡ］（和光一級、富士フイルム和光純薬株式会社）
・２，２’－Ａｚｏｂｉｓ（ｉｓｏｂｕｔｙｒｏｎｉｔｒｉｌｅ）［ＡＩＢＮ］（和光特級、富士フイルム和光純薬株式会社）
・１，４－Ｄｉｏｘａｎｅ［１，４－ジオキサン］（試薬特級、富士フイルム和光純薬株式会社）
・Ｔｅｔｒａｈｙｄｒｏｆｕｒａｎ［ＴＨＦ］（試薬特級、富士フイルム和光純薬株式会社）
・Ｈｅｘａｎｅ［ヘキサン］（試薬特級、富士フイルム和光純薬株式会社）
・Ｂｏｖｉｎｅ　Ｓｅｒｕｍ　Ａｌｂｕｍｉｎ［ＢＳＡ］（ｐＨ５．２、ＳＩＧＭＡ－ＡＬＤＲＩＣＨ） (reagent)
The reagents used in the examples are as follows.
Poly (vinylidene fluoride) [PVDF] (Solef (registered trademark) 6010., SOLVAY., Mw: 300,000-320,000 [Da] powerer)
1-Methyl-2-pyrrolidone [NMP] (Wako Special Grade, Fujifilm Wako Pure Chemical Industries, Ltd.)
-Deionized water [DI-water (pure water)] (Elix (registered trademark) Essential 5 (UV)., Millipore.)
・ 2-Methoxyethyl Acrylate [MEA] (Wako First Class, Wako Pure Chemical Industries, Ltd.)
・ 2,2'-Azobis (isobutyronirile) [AIBN] (Wako Special Grade, Fujifilm Wako Pure Chemical Industries, Ltd.)
・ 1,4-Dioxane [1,4-dioxane] (special grade reagent, Wako Pure Chemical Industries, Ltd.)
・ Tetrahydrofuran [THF] (special grade reagent, Wako Pure Chemical Industries, Ltd.)
・ Hexane [hexane] (special grade reagent, Wako Pure Chemical Industries, Ltd.)
-Bovine Serum Albumin [BSA] (pH 5.2, SIGMA-ALDRICH)
＜膜素材の準備＞
　ベースポリマーは、市販のポリフッ化ビニリデン（ＰＶＤＦ）を用いた。
　ポリ（２－メトキシエチルアクリレート）（ＰＭＥＡ）は、以下の手順により合成した。
　蒸留したＭＥＡモノマー２０［ｇ］と１，４－ジオキサン１００［ｇ］をナス型フラスコに入れ、窒素バブリングを３０［ｍｉｎ］行った。バブリング終了後、ＡＩＢＮ０．０８［ｇ］と小型攪拌子を入れ、重合温度７５［℃］、重合時間２４［ｈ］でラジカル重合を行った。
　ラジカル重合終了後、ヘキサン５００［ｍＬ］が入ったビーカーに重合後の溶液を流し込むことで、ヘキサンに不溶なポリマーが析出した。このとき、混合溶液全体が白濁するが、ビーカーの底には高い重合量の白色沈殿物が存在するため、その沈殿物を目的ポリマーとして得られた。
　沈殿物（ポリマー）以外のヘキサン及び１，４－ジオキサンを含んだ白濁溶液は除去し、ＴＨＦ１０［ｍＬ］でポリマーを完全に溶解させた。１０［ｍＬ］で溶解しなかった場合はさらに１０［ｍＬ］ずつ加えた。ポリマーの溶解に要したＴＨＦの１５倍量のヘキサンを溶液に入れて再度ポリマーを析出させた。この操作を合計３回繰り返すことでＭＥＡポリマー（ＰＭＥＡ）が得られた。 <Preparation of membrane material>
As the base polymer, commercially available polyvinylidene fluoride (PVDF) was used.
Poly (2-methoxyethyl acrylate) (PMEA) was synthesized by the following procedure.
Distilled MEA monomer 20 [g] and 1,4-dioxane 100 [g] were placed in an eggplant-shaped flask, and nitrogen bubbling was performed for 30 [min]. After the bubbling was completed, AIBN 0.08 [g] and a small stirrer were added, and radical polymerization was carried out at a polymerization temperature of 75 [° C.] and a polymerization time of 24 [h].
After the radical polymerization was completed, the polymer insoluble in hexane was precipitated by pouring the polymerized solution into a beaker containing 500 [mL] of hexane. At this time, the entire mixed solution became cloudy, but since a white precipitate having a high polymerization amount was present at the bottom of the beaker, the precipitate was obtained as the target polymer.
The cloudy solution containing hexane and 1,4-dioxane other than the precipitate (polymer) was removed, and the polymer was completely dissolved in THF10 [mL]. If it did not dissolve in 10 [mL], another 10 [mL] was added. Hexane, which was 15 times the amount of THF required to dissolve the polymer, was placed in the solution to precipitate the polymer again. By repeating this operation a total of 3 times, a MEA polymer (PMEA) was obtained.
＜多孔質膜の製造＞
（製膜溶液の作製）
　表１に示すように、ＰＶＤＦ：ＰＭＥＡのブレンド比を１５：０、１５：１、１５：３、１５：５、１５：７とし、溶媒としてＮ－メチル－２－ピロリドン（ＮＭＰ）を用いて７０℃で１～４時間攪拌し、製膜溶液（キャスト溶液）を作製した。 <Manufacturing of porous membrane>
(Preparation of film-forming solution)
As shown in Table 1, the PVDF: PMEA blend ratio was 15: 0, 15: 1, 15: 3, 15: 5, 15: 7, and N-methyl-2-pyrrolidone (NMP) was used as the solvent. A film-forming solution (cast solution) was prepared by stirring at 70 ° C. for 1 to 4 hours.
Figure JPOXMLDOC01-appb-T000001
 
Figure JPOXMLDOC01-appb-T000001
 
（相分離法による製膜）
　作製したキャスト溶液を室温まで自然冷却した後、ガラス板上に広げ、厚み２００μｍのギャップナイフで薄く均一に延ばした。
　３０秒経過後、ガラス板ごと非溶媒（純水）中に浸漬させることで、相分離により多孔質膜（ＰＭＥＡ０～ＰＭＥＡ７）を析出させた。 (Film formation by phase separation method)
The prepared cast solution was naturally cooled to room temperature, spread on a glass plate, and spread thinly and uniformly with a gap knife having a thickness of 200 μm.
After 30 seconds had passed, the porous film (PMEA0 to PMEA7) was precipitated by phase separation by immersing the glass plate in a non-solvent (pure water).
［評価］
＜ＦＴ－ＩＲ分析＞
　作製した膜に対し、ＦＴ－ＩＲ（ＡＴＲ）表面スペクトル測定を行い、ＰＭＥＡが膜表面に存在するか確認した。各膜の膜表面のＦＴ－ＩＲ（フーリエ変換赤外分光法）スペクトルを図２に示す。ＰＭＥＡをブレンドした膜（ＰＭＥＡ１、３、５、７）にはＰＭＥＡ特有のＣ＝Ｏに由来するピークが１７４０ｃｍ－１付近に確認できた。
　また、ＰＭＥＡのＣ＝Ｏピーク強度とＰＶＤＦのピーク強度の比は、ＰＭＥＡ／ＰＶＤＦブレンド比の増加に伴い大きくなることが確認できた。したがって、ＰＭＥＡ／ＰＶＤＦブレンド比の増加は、膜表面へのＰＭＥＡ存在割合の増加に寄与することが裏付けられた。 [evaluation]
<FT-IR analysis>
An FT-IR (ATR) surface spectrum measurement was performed on the prepared film to confirm whether PMEA was present on the film surface. The FT-IR (Fourier transform infrared spectroscopy) spectrum of the film surface of each film is shown in FIG. In the membranes blended with PMEA ( PMEA 1, 3, 5, 7), a peak derived from C = O peculiar to PMEA was confirmed in the vicinity of 1740 cm -1 .
It was also confirmed that the ratio of the C = O peak intensity of PMEA to the peak intensity of PVDF increases as the PMEA / PVDF blend ratio increases. Therefore, it was supported that the increase in the PMEA / PVDF blend ratio contributed to the increase in the abundance ratio of PMEA on the film surface.
＜ＦＥ－ＳＥＭ観察＞
　ＦＥ－ＳＥＭを用いて、膜表面及び膜断面の構造を観察した。図３は、各膜の表面（キャスト時のガラス基板と逆側）を示すＦＥ－ＳＥＭ画像であり、図４は、各膜の断面を示すＦＥ－ＳＥＭ画像である。
　いずれの膜も一方の面側（キャスト時のガラス基板と逆側）と他方の面側で多孔構造が異なる非対称多孔構造となっている。また、図４に見られるように、ＰＭＥＡをブレンドしていない膜に比べ、ＰＭＥＡをブレンドした膜の空隙部分が大きくなっていることがわかる。 <FE-SEM observation>
The structure of the membrane surface and the membrane cross section was observed using FE-SEM. FIG. 3 is an FE-SEM image showing the surface of each film (the side opposite to the glass substrate at the time of casting), and FIG. 4 is an FE-SEM image showing a cross section of each film.
Each film has an asymmetric porous structure in which the porous structure differs between one surface side (the side opposite to the glass substrate at the time of casting) and the other surface side. Further, as can be seen in FIG. 4, it can be seen that the void portion of the film blended with PMEA is larger than that of the film not blended with PMEA.
＜純水透過実験＞
　流量２Ｌ／分、供給温度２５℃とし、クロスフロー方式で純水透過試験を行い、純水透過係数（Ｌｐ）を求め、膜の透水性能を比較した。さらに、マイクロメーターを用いて膜面５箇所を無作為に計測し、その平均値を膜厚として評価した。
　図５は、ＰＭＥＡブレンド比に対する純水透過係数Ｌｐと膜厚の関係を示すグラフである。Ｌｐが高いほど膜抵抗が小さく、低い圧力で水が透過するため、膜分離に有利である。ＰＭＥＡをブレンドしたことで膜の透水性能が大幅に向上していることが分かる。なお、ＰＭＥＡ３が最も純水透過係数Ｌｐが大きく、ＰＭＥＡ５及びＰＭＥＡ７では、純水透過係数Ｌｐが低下している。これは、ＰＭＥＡブレンドの割合が増加したことによるものではなく、総ポリマー含有量（ブレンドポリマー含有量）が高いことに起因していると推測される。
　また、膜厚に大きな違いはなく、ＰＭＥＡをブレンドした膜は、膜厚を薄くせずに、すなわち、膜強度を下げずに、高い透水性能を発揮できることがわかる。ＰＭＥＡをブレンドしたことで、膜の内部構造変化（図４）が純水透過係数の増加に大きく影響を及ぼしたと考えられる。 <Pure water permeation experiment>
A pure water permeability test was conducted by a cross-flow method at a flow rate of 2 L / min and a supply temperature of 25 ° C., a pure water permeability coefficient (Lp) was obtained, and the permeability of the membrane was compared. Further, 5 points on the film surface were randomly measured using a micrometer, and the average value was evaluated as the film thickness.
FIG. 5 is a graph showing the relationship between the pure water permeability coefficient Lp and the film thickness with respect to the PMEA blend ratio. The higher the Lp, the smaller the membrane resistance, and the lower the pressure, the more water permeates, which is advantageous for membrane separation. It can be seen that the water permeability of the membrane is significantly improved by blending PMEA. In addition, PMEA3 has the largest pure water permeability coefficient Lp, and PMEA5 and PMEA7 have a lower pure water permeability coefficient Lp. It is presumed that this is not due to the increase in the proportion of PMEA blend, but due to the high total polymer content (blended polymer content).
Further, there is no big difference in the film thickness, and it can be seen that the film blended with PMEA can exhibit high water permeability without reducing the film thickness, that is, without lowering the film strength. It is considered that the change in the internal structure of the membrane (Fig. 4) greatly affected the increase in the pure water permeability coefficient by blending PMEA.
＜ウシ血清アルブミン（ＢＳＡ）透過試験＞
　純水透過係数算出後、フラックスを４×１０－６［ｍ３ｍ－２ｓ－１］一定で１０［ｍｉｎ］間隔（透過液の採取時間は約５［ｍｉｎ］）、合計３０［ｍｉｎ］測定した。
　純水透過後、供給液全体がＢＳＡ１０００［ｐｐｍ］になるよう調製し、ＢＳＡ透過試験を合計１８０［ｍｉｎ］行った。ＢＳＡ透過試験中、透過液は純水透過試験時同様１０［ｍｉｎ］間隔で５［ｍｉｎ］採取した。 <Bovine serum albumin (BSA) permeation test>
After calculating the pure water permeability coefficient, the flux is 4 × 10 -6 [m 3 m -2 s -1 ] at constant 10 [min] intervals (permeate sampling time is about 5 [min]), for a total of 30 [min]. It was measured.
After permeation with pure water, the total amount of the feed solution was adjusted to BSA 1000 [ppm], and a total BSA permeation test was performed for 180 [min]. During the BSA permeation test, the permeate was collected at 5 [min] intervals at 10 [min] intervals as in the pure water permeation test.
　また、阻止率を求めるためにバイアルを用いて、供給液を３０［ｍｉｎ］間隔で採取しＴＯＣ－Ｖ（島津製作所社製）を用いて、予め作製していたＢＳＡ検量線を用いてＢＳＡ濃度を求めた。透過液は３０［ｍｉｎ］おきに採取したが、低フラックスの場合はバイアルに十分な量の透過液が採取できないため、純水で希釈して希釈倍率をＴＯＣの測定結果に掛け合わせ、濃度を補正した。ＴＯＣ測定結果で得た供給液濃度と透過液濃度を下記式を用いて見かけの阻止率を算出した。
　Ｒｏｂｓ＝（１－Ｃｐ／Ｃｂ）
　Ｒｏｂｓ：見かけの阻止率
　Ｃｐ：透過液濃度（ｍｏｌ／ｍ３）
　Ｃｂ：供給液濃度（ｍｏｌ／ｍ３） In addition, a vial was used to determine the inhibition rate, and the supply liquid was collected at intervals of 30 [min], and TOC-V (manufactured by Shimadzu Corporation) was used to prepare the BSA concentration using the BSA calibration curve prepared in advance. Asked. The permeate was collected every 30 [min], but in the case of low flux, a sufficient amount of permeate could not be collected in the vial, so dilute it with pure water and multiply the dilution ratio by the TOC measurement result to determine the concentration. Corrected. The apparent inhibition rate was calculated using the following formula for the supply liquid concentration and the permeation liquid concentration obtained from the TOC measurement results.
Robs = (1-C p / C b )
Robs : Apparent blocking rate C p : Permeate concentration (mol / m 3 )
C b : Supply liquid concentration (mol / m 3 )
　図６は、ＢＳＡ透過試験結果を示すグラフである。試験開始後、純水からＢＳＡ１０００ｐｐｍ水溶液に交換することで、ＰＭＥＡをブレンドしていない膜では透水性能が急激に低下し、低ファウリング性が低いことがわかる。一方、ＰＭＥＡをブレンドした膜、特にＰＭＥＡ３、５、７では透水性能が若干低下したものの、試験終了時までほぼ一定であり、低ファウリング性に優れることが分かる。また、ＰＭＥＡブレンドの割合が大きくなるにつれ、低ファウリング性が高くなっていることがわかる。 FIG. 6 is a graph showing the results of the BSA permeation test. It can be seen that by exchanging pure water with a 1000 ppm BSA aqueous solution after the start of the test, the water permeability of the membrane not blended with PMEA is sharply lowered, and the low fouling property is low. On the other hand, although the water permeability of the membrane blended with PMEA, particularly PMEA3, 5 and 7, was slightly deteriorated, it was almost constant until the end of the test, and it can be seen that the membrane has excellent low fouling property. Further, it can be seen that as the proportion of the PMEA blend increases, the low fouling property becomes higher.
　上記のように、ＰＭＥＡをブレンドしたことで膜の内部構造変化及び透水性能の向上が見られた。さらに、ＰＭＥＡ／ＰＶＤＦブレンド比の増加が膜表面にＰＭＥＡを多く存在させることに寄与することが明らかとなった。したがって、ＰＭＥＡブレンドＰＶＤＦ多孔質膜は、ファウリングを抑制することが期待できる。 As described above, the blending of PMEA showed a change in the internal structure of the membrane and an improvement in water permeability. Furthermore, it was clarified that the increase in the PMEA / PVDF blend ratio contributed to the presence of a large amount of PMEA on the film surface. Therefore, the PMEA-blended PVDF porous membrane can be expected to suppress fouling.
　本開示に係る多孔質膜は、様々な用途においてファウリングを抑制することができ、水処理以外にも、タンパク分画など新しい用途を開拓できる可能性がある。特にタンパク様物質又は多糖様物質に対する低ファウリング性に優れると考えられる。 The porous membrane according to the present disclosure can suppress fouling in various applications, and may open up new applications such as protein fractionation in addition to water treatment. In particular, it is considered to be excellent in low fouling property against protein-like substances or polysaccharide-like substances.
　２０２０年９月２４日に出願された日本特許出願特願２０２０－１５９８６４の開示はその全体が参照により本明細書に取り込まれる。本明細書に記載された全ての文献、特許出願、および技術規格は、個々の文献、特許出願、および技術規格が具体的かつ個々に記された場合と同程度に、本明細書中に参照により取り込まれる。 The entire disclosure of Japanese Patent Application No. 2020-159864 filed on September 24, 2020 is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are referenced herein to the same extent as if individual documents, patent applications, and technical standards were specifically and individually described. Is taken in by.

Claims (6)

  1. 　ベースポリマーとポリ（２－メトキシエチルアクリレート）とを含むブレンドポリマーを含有し、多孔構造を有する多孔質膜。 A porous membrane containing a blend polymer containing a base polymer and poly (2-methoxyethyl acrylate) and having a porous structure.
  2. 　前記多孔構造が、前記多孔質膜の一方の面側から他方の面側に向けて孔径が大きくなるに伴い空隙率が大きくなっている非対称多孔構造である請求項１に記載の多孔質膜。 The porous film according to claim 1, wherein the porous structure is an asymmetric porous structure in which the porosity increases as the pore diameter increases from one surface side to the other surface side of the porous film.
  3. 　前記ベースポリマーが、ポリフッ化ビニリデン、ポリスルホン、ポリエーテルスルホン、ポリ塩化ビニル、ポリアクリロニトリル、酢酸セルロース、及びポリアミドからなる群より選ばれる１種又は２種以上のポリマーである請求項１又は請求項２に記載の多孔質膜。 Claim 1 or claim 2 where the base polymer is one or more polymers selected from the group consisting of polyvinylidene fluoride, polysulfone, polyethersulfone, polyvinyl chloride, polyacrylonitrile, cellulose acetate, and polyamide. The porous membrane according to.
  4. 　ベースポリマーと、ポリ（２－メトキシエチルアクリレート）と、溶媒と、を含む製膜溶液を準備する工程と、
    　前記製膜溶液を用い、相分離法によって多孔質膜を析出させる工程と、
    　を含む多孔質膜の製造方法。     A step of preparing a film-forming solution containing a base polymer, poly (2-methoxyethyl acrylate), and a solvent, and
    A step of precipitating a porous membrane by a phase separation method using the membrane-forming solution, and
    A method for producing a porous membrane including.
  5. 　前記ベースポリマーが、ポリフッ化ビニリデン、ポリスルホン、ポリエーテルスルホン、ポリ塩化ビニル、ポリアクリロニトリル、酢酸セルロース、及びポリアミドからなる群より選ばれる１種又は２種以上のポリマーである請求項４に記載の多孔質膜の製造方法。 The porosity according to claim 4, wherein the base polymer is one or more polymers selected from the group consisting of polyvinylidene fluoride, polysulfone, polyethersulfone, polyvinyl chloride, polyacrylonitrile, cellulose acetate, and polyamide. Method for manufacturing a quality membrane.
  6. 　前記相分離法が、非溶媒誘起相分離法である請求項４又は請求項５に記載の多孔質膜の製造方法。
          The method for producing a porous membrane according to claim 4 or 5, wherein the phase separation method is a non-solvent-induced phase separation method.
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Citations (5)

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JP2001323030A (en) * 2000-05-17 2001-11-20 Terumo Corp Copolymer and blood filter made thereof
JP2017214450A (en) * 2016-05-30 2017-12-07 Dic株式会社 Polymer composite
WO2018181365A1 (en) * 2017-03-27 2018-10-04 三菱ケミカル株式会社 Porous membrane, membrane module, water treatment device, and method for manufacturing porous membrane
WO2018212269A1 (en) * 2017-05-17 2018-11-22 旭化成メディカル株式会社 Phosphorus adsorbent for blood treatment, blood treatment system, and blood treatment method
WO2019059397A1 (en) * 2017-09-25 2019-03-28 三菱ケミカル株式会社 Hollow fiber membrane

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001323030A (en) * 2000-05-17 2001-11-20 Terumo Corp Copolymer and blood filter made thereof
JP2017214450A (en) * 2016-05-30 2017-12-07 Dic株式会社 Polymer composite
WO2018181365A1 (en) * 2017-03-27 2018-10-04 三菱ケミカル株式会社 Porous membrane, membrane module, water treatment device, and method for manufacturing porous membrane
WO2018212269A1 (en) * 2017-05-17 2018-11-22 旭化成メディカル株式会社 Phosphorus adsorbent for blood treatment, blood treatment system, and blood treatment method
WO2019059397A1 (en) * 2017-09-25 2019-03-28 三菱ケミカル株式会社 Hollow fiber membrane

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