WO2024053690A1 - Porous film and composite film - Google Patents

Porous film and composite film Download PDF

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Publication number
WO2024053690A1
WO2024053690A1 PCT/JP2023/032587 JP2023032587W WO2024053690A1 WO 2024053690 A1 WO2024053690 A1 WO 2024053690A1 JP 2023032587 W JP2023032587 W JP 2023032587W WO 2024053690 A1 WO2024053690 A1 WO 2024053690A1
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Prior art keywords
aromatic
porous membrane
polymer
monomer
membrane
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PCT/JP2023/032587
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French (fr)
Japanese (ja)
Inventor
貴亮 安田
竣介 水野
貴史 小川
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東レ株式会社
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Publication of WO2024053690A1 publication Critical patent/WO2024053690A1/en

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    • 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
    • B01D69/10—Supported membranes; Membrane supports
    • 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
    • B01D69/12—Composite membranes; Ultra-thin membranes
    • 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
    • B01D71/58—Other polymers having nitrogen in the main chain, with or without oxygen or carbon only
    • B01D71/62—Polycondensates having nitrogen-containing heterocyclic rings in the main chain
    • B01D71/64—Polyimides; Polyamide-imides; Polyester-imides; Polyamide acids or similar polyimide precursors
    • 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
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/30—Low-molecular-weight compounds
    • C08G18/34—Carboxylic acids; Esters thereof with monohydroxyl compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
    • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
    • C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
    • 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
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/04—Reinforcing macromolecular compounds with loose or coherent fibrous material
    • 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
    • C08J9/28—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum

Definitions

  • the present invention relates to porous membranes and composite membranes.
  • Membrane separation methods are widely used to separate liquid mixtures as a process for saving energy and resources.
  • the main target of membrane separation methods is water treatment applications, but in recent years, separation applications targeting organic solvents have expanded.
  • separation applications targeting organic solvents have expanded.
  • wastewater containing organic solvents remove solutes from organic solvents, recover valuables from organic solvents, and use mixed organic solvents.
  • Membrane separation methods are being used for separation and recovery.
  • OSRO organic solvent reverse osmosis
  • OSN organic solvent reverse osmosis
  • Polymer membranes generally used for water treatment cannot maintain stability because they swell or dissolve in organic solvents, resulting in an extremely low separation efficiency. Therefore, for separation of liquid mixtures containing organic solvents, it is necessary to use membranes that are resistant to organic solvents.
  • Patent Document 1 discloses a composite semipermeable membrane in which a polyamide-based separation functional layer is laminated on a porous layer containing a polymer selected from fluoropolymers and imide group-containing polymers. Patent Document 1 states that this provides a separation membrane that has excellent oil resistance and sufficient desalting performance.
  • Non-Patent Document 1 discloses an aromatic polymer obtained by polymerizing an aromatic diamine monomer or aromatic diisocyanate monomer containing a fluorine atom and an acid anhydride monomer, but this aromatic polymer has poor mechanical properties. It is known that due to the poor quality of membranes, cracks may occur during the production and crosslinking of porous membranes and composite membranes, making them unusable as separation membranes.
  • the composite semipermeable membrane described in Patent Document 1 has resistance to non-polar organic solvents such as hydrocarbon oil, it does not have sufficient resistance to polar organic solvents. Ta. Furthermore, although the composite semipermeable membrane described in Patent Document 1 has desalination treatment performance due to the polyamide-based separation functional layer, desalination treatment performance is poor at high temperatures above the glass transition temperature of polyamide (approximately 40 to 50 degrees Celsius). There was a problem in that the value decreased significantly.
  • Non-Patent Document 1 has the problem that it may not be usable as a separation membrane due to cracks occurring during film formation and crosslinking of porous membranes and composite membranes. , it was necessary to improve film formability.
  • an object of the present invention is to provide a porous membrane and a composite membrane that have high film formability, organic solvent resistance, and excellent separation performance and permeation performance.
  • the porous membrane contains a crosslinked polymer in which aromatic polymers are crosslinked, and that the aromatic polymer includes at least an aromatic diamine monomer containing a fluorine atom and an aromatic diamine monomer containing a fluorine atom. At least one fluorine-based aromatic monomer selected from the group consisting of diisocyanate monomers, and at least one non-fluorine selected from the group consisting of aromatic diamine monomers that do not contain fluorine atoms and aromatic diisocyanate monomers that do not contain fluorine atoms.
  • the present embodiment is characterized by the following (1) to (10).
  • (1) Contains a crosslinked polymer in which aromatic polymers are crosslinked,
  • the aromatic polymer contains at least one fluorine-based aromatic monomer selected from the group consisting of an aromatic diamine monomer containing a fluorine atom and an aromatic diisocyanate monomer containing a fluorine atom, and an aromatic compound containing no fluorine atom.
  • the aromatic polymer contains aromatic polyimide.
  • the degree of imidization of the crosslinked polymer is 0.2 to 1.2.
  • the aromatic polymers are crosslinked with each other by at least one crosslinking agent selected from the group consisting of an epoxy crosslinking agent, a methylol crosslinking agent, an alkoxymethyl crosslinking agent, and a diamine crosslinking agent.
  • a fluid separation device comprising the module according to (12) above.
  • a method for producing a porous membrane including the steps (i) and (ii) below.
  • crosslinking agent is at least one crosslinking agent selected from the group consisting of an epoxy crosslinking agent, a methylol crosslinking agent, an alkoxymethyl crosslinking agent, and a diamine crosslinking agent.
  • the porous film has high film-forming properties and can continuously and stably maintain separation performance and permeation performance for liquids to be treated containing organic solvents and liquids to be treated at high temperatures. Both membranes and composite membranes can be provided.
  • ⁇ in a numerical range is a range that includes the numbers before and after it; for example, "0-100” means a range that is 0 or more and 100 or less.
  • Porous membrane and composite membrane (1-1) Porous membrane
  • the porous membrane of this embodiment contains a crosslinked polymer in which aromatic polymers are crosslinked, and the aromatic polymer contains at least a fluorine atom.
  • At least one fluorinated aromatic monomer selected from the group consisting of an aromatic diamine monomer and an aromatic diisocyanate monomer containing a fluorine atom, an aromatic diamine monomer that does not contain a fluorine atom, and an aromatic diisocyanate monomer that does not contain a fluorine atom.
  • Aromade-based aromatic monomer examples include 1,4-diamino-2,3,5,6-tetrafluorobenzene, 1,3-diamino- 2,4,5,6-tetrafluorobenzene, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2'-bis(trifluoromethyl)benzidine, octafluorobenzidine, 4,4'-dihydroxy -3,3'-diaminophenylhexafluoropropane, 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether, 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene , 9,9-bis(3-amino-4-hydroxyphenyl)fluorene.
  • aromatic diisocyanate monomers containing fluorine atoms examples include 2,2-bis(4-isocyanatophenyl)hexafluoropropane.
  • the fluorine-based aromatic monomer is preferably an aromatic diamine monomer containing a fluorine atom, and among them, 2,2-bis(4-aminophenyl)hexafluoropropane, or , 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane is preferably used.
  • Non-fluorinated aromatic monomer An aromatic polymer formed by copolymerizing a fluorinated aromatic monomer and an acid anhydride monomer is further copolymerized with a non-fluorinated aromatic monomer. This makes it possible to achieve both solubility and mechanical properties of the aromatic polymer, thereby improving film formability.
  • aromatic diamine monomers that do not contain fluorine atoms examples include 4,4'-diaminodiphenyl ether and 3,3'-oxydianiline
  • aromatic diisocyanate monomers that do not contain fluorine atoms include, for example, bis(4 -isocyanatophenyl)methane.
  • aromatic diamine monomers that do not contain fluorine atoms are preferred from the viewpoint of monomer availability and mechanical properties of the aromatic polymer, and among them, 4,4'-diaminodiphenyl ether is preferably used.
  • the copolymerization ratio of the fluorine-based aromatic monomer and the non-fluorine-based aromatic monomer is in the range of 25:75 to 70:30 in terms of molar ratio.
  • the copolymerization ratio of the fluorine-based aromatic monomer and the non-fluorine-based aromatic monomer is (25 or more): (75 or less)
  • an aromatic polymer with excellent solubility can be obtained.
  • the copolymerization ratio is (70 or less):(30 or more)
  • an aromatic polymer with excellent mechanical properties can be obtained.
  • the copolymerization ratio is preferably in the range of 25:75 to 65:35, more preferably in the range of 25:75 to 60:40, even more preferably in the range of 25:75 to 50:50. .
  • Acid anhydride monomer examples include pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2' dimethyl -3,3',4,4'-biphenyltetracarboxylic dianhydride, 5,5'dimethyl-3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3', 4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl ethertetracarboxylic dianhydride, 2,3 , 3',4'-diphenyl ether tetracarboxylic dianhydride, 2,2',3,3'-diphenyl ether tetracarboxylic dianhydride, 3,3', 3,3',4,4'-diphen
  • the molar ratio of the total of the fluorinated aromatic monomer and non-fluorinated aromatic monomer to the acid anhydride monomer is preferably 80:100 to 100:80.
  • the fluorinated aromatic monomer, non-fluorinated aromatic monomer, and acid anhydride monomer used in the aromatic polymer include 2-bis(4-aminophenyl)hexafluoropropane or 4,4'-dihydroxy-3, A combination of 3'-diaminophenylhexafluoropropane, 4,4'-diaminodiphenyl ether, and 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride is preferred.
  • Aromatic polymer is at least one fluorinated aromatic polymer selected from the group consisting of an aromatic diamine monomer containing a fluorine atom and an aromatic diisocyanate monomer containing a fluorine atom.
  • a monomer, at least one non-fluorine-based aromatic monomer selected from the group consisting of an aromatic diamine monomer that does not contain a fluorine atom and an aromatic diisocyanate monomer that does not contain a fluorine atom, and an acid anhydride monomer are copolymerized. It becomes.
  • the aromatic polymer include aromatic polyamic acid, aromatic polyamideimide, aromatic polyimide, aromatic polyetherimide, aromatic polymaleimide, and the like.
  • the aromatic polymer is preferably an aromatic polyimide from the viewpoint of versatility.
  • the above-mentioned aromatic polymer may contain other components in addition to the above-mentioned components within a range that does not impair the effects of the present invention.
  • Other components include polyamide, polyamine, and the like.
  • the manufacturing method of the aromatic polymer is not particularly limited as long as an aromatic polymer satisfying the above characteristics can be obtained, but for example, it can be manufactured by the manufacturing method described below.
  • the weight average molecular weight (hereinafter referred to as "Mw") of the aromatic polymer is preferably 5,000 to 300,000 from the viewpoint of achieving separation performance, mechanical strength, and film formability.
  • the aromatic polymer is an aromatic polyimide
  • the Mw of the aromatic polyimide is preferably 8,000 to 200,000, more preferably 12,000 to 100,000.
  • the Mw of the aromatic polyimide is 8,000 or more, separation performance and mechanical strength preferable for porous membranes and composite membranes can be obtained.
  • the Mw of the aromatic polyimide is 200,000 or less, the viscosity of the polymer solution falls within an appropriate range, and good film formability can be achieved.
  • the weight average molecular weight of the aromatic polymer can be measured by gel permeation chromatography, and is a value converted to the molecular weight of polystyrene used as a standard substance.
  • the crosslinked polymer is a polymer in which the above-mentioned aromatic polymers are crosslinked with each other.
  • the crosslinked polymer is a polymer in which the aromatic polymers described above are crosslinked with at least one crosslinking agent selected from the group consisting of an epoxy crosslinking agent, a methylol crosslinking agent, an alkoxymethyl crosslinking agent, and a diamine crosslinking agent. It is preferable that there be.
  • the degree of imidization of the crosslinked polymer is preferably from 0.2 to 1.2, more preferably from 0.3 to 1.2, and more preferably from 0.4 to 1.2. More preferably, it is 1.2.
  • the degree of imidization of the crosslinked polymer is 0.2 or more, it is possible to continuously and stably maintain separation performance and permeation performance for processed liquids containing organic solvents and high-temperature processed liquids. A porous membrane can be obtained.
  • the degree of imidization of the crosslinked polymer can be measured using a Fourier transform infrared spectrophotometer.
  • the degree of imidization of the crosslinked polymer can be adjusted by the degree of progress of the heating dehydration reaction after polyamic acid synthesis.
  • methods for promoting imidization include distilling off water, which is a byproduct of the imidization reaction, and adding additives such as acetic anhydride, isoquinoline, imidazole, and pyridine to a polyamic acid solution, followed by heating.
  • One method is to do so.
  • a method for suppressing imidization there is a method such as adding water to polyamic acid.
  • porous membrane contains a crosslinked polymer.
  • the above aromatic polymer is soluble in an organic solvent, a polymer having organic solvent resistance can be obtained by crosslinking the above aromatic polymers. This makes it possible to fabricate a porous membrane using a polymer solution, and by crosslinking it afterwards, it consistently and stably maintains separation and permeation performance for treated liquids containing organic solvents. A maintainable porous membrane can be obtained.
  • the porous membrane has a three-dimensional network structure.
  • the term "three-dimensional network structure" as used herein refers to a structure in which the linear polymers constituting the porous membrane are three-dimensionally spread out in a network shape.
  • the three-dimensional network structure has pores partitioned by solid stripes forming the network, and has excellent separation performance.
  • the porous membrane preferably has at least two layers, a dense layer and a coarse layer, and more preferably at least two layers, a dense layer and a coarse layer, in the thickness direction.
  • the term "dense layer” refers to a layer with an average pore size of less than 50 nm
  • the term “coarse layer” refers to a layer with an average pore size of 50 nm or more.
  • the average surface pore diameter of the porous membrane can be appropriately selected depending on the application.
  • the average surface pore diameter of the porous membrane is preferably 0.25 to 0.8 nm, and More preferably, the thickness is from .4 to 0.7 nm.
  • the average surface pore diameter of the porous membrane is preferably 0.7 to 4 nm, and preferably 0.75 to 4 nm. More preferably, the thickness is 2 nm.
  • the average surface pore diameter of the porous membrane is preferably 2 to 100 nm, more preferably 4 to 50 nm. preferable.
  • the thickness of the porous membrane is preferably 20 to 300 ⁇ m, more preferably 30 to 250 ⁇ m, and even more preferably 40 to 200 ⁇ m.
  • the thickness of the porous membrane can be determined by calculating the average value of the thickness at 20 points measured at 20 ⁇ m intervals in a direction perpendicular to the thickness direction (in the plane direction of the membrane) during cross-sectional observation.
  • the porosity of the porous membrane is preferably 25 to 85%, more preferably 30 to 75%. Porosity is defined as the ratio of the volume of space to the total volume of a material. When the porosity of the porous membrane is 25% or more, a porous membrane having good permeability can be obtained. On the other hand, when the porosity of the porous membrane is 85% or less, a porous membrane having sufficient mechanical strength can be obtained.
  • the method for measuring the porosity (%) of a porous membrane is, for example, to calculate it using the following formula 2 from the membrane volume (cm 3 ) and mass (g) calculated by measuring the membrane thickness of the porous membrane. Can be done.
  • the density for calculating the porosity can be set depending on the type of aromatic polymer. For example, if the aromatic polymer is an aromatic polyimide, the density may be 1.42 g/cm 3 .
  • Porosity (%) ⁇ 1-mass/(density x membrane volume) ⁇ x 100 (Formula 2)
  • the porous membrane of this embodiment preferably has macrovoids in its cross section. Further, the area ratio of macrovoids to the cross section of the porous membrane is preferably 3 to 60%, more preferably 5 to 55%, and even more preferably 10 to 50%. When the area ratio of macrovoids to the cross section of the porous membrane is 3% or more, liquid and gas easily flow into the macrovoids, resulting in high permeability of the membrane. On the other hand, when the area ratio of macrovoids to the cross section of the porous membrane is 60% or less, the membrane exhibits sufficient mechanical properties against pressure and is therefore easy to handle.
  • macro void refers to a hole having a length of 0.5 ⁇ m or more.
  • Typical shapes of macrovoids include, for example, a spherical structure with a diameter of 0.5 ⁇ m or more, a teardrop with a length of 0.5 ⁇ m or more, a pear-like or pear-shaped shape, and two or more bell-like shapes. or a finger-like structure having a length of 0.5 ⁇ m or more and an aspect ratio of 3 or more.
  • the “aspect ratio” refers to a value obtained by dividing the length of a macrovoid in a direction perpendicular to the porous membrane surface by the length of the macrovoid in a direction horizontal to the porous membrane surface.
  • the aspect ratio of the macrovoid is preferably 2.0 or more, preferably 2.5 or more, and more preferably 3.0 or more.
  • the aspect ratio of the macrovoids is 3.0 or more, the membrane exhibits sufficient mechanical properties against pressure and becomes a highly permeable membrane.
  • the aspect ratio is preferably 6.0 or less.
  • the aspect ratio is 6.0 or less, sufficient mechanical properties are exhibited even in the tensile direction. That is, it is preferable that the macrovoids have their long axes in the thickness direction of the film.
  • cross section refers to a cross section cut in a direction perpendicular to the surface of the porous membrane.
  • An example of a method for appropriately controlling the area ratio and aspect ratio of macrovoids in the cross section of a porous membrane is a method of adding additives to the membrane forming solution.
  • the porous membrane is a polyimide membrane
  • an organic solvent in which polyimide is soluble by using a mixture of an organic solvent in which polyimide is soluble and an organic solvent that promotes penetration of the coagulation bath into the polyimide solution, macroscopic particles can be added to the polyimide membrane. Voids can be formed.
  • organic solvents in which polyimide is soluble include acetone, acetonitrile, dimethyl sulfoxide, dimethylacetamide, dimethylformamide, N-methylpyrrolidone, dichloromethane, and chloroform.
  • the degree of swelling in the porous membrane of this embodiment is preferably 100 to 200%, more preferably 105 to 150%, and even more preferably 110 to 130%.
  • the porous membrane has an appropriate affinity for the solvent and exhibits high removability and high permeability.
  • “Degree of swelling” refers to the thickness of the porous membrane after immersion in NMP and reaching an equilibrium swelling state, compared to the thickness of the porous membrane before immersion in N-methyl-2-pyrrolidone (hereinafter referred to as ⁇ NMP''). means the ratio of
  • the porous membrane of this embodiment may be composed only of the above-mentioned porous membrane, but the porous membrane forms a composite membrane in which the porous membrane is laminated on at least one side of the base material. You may do so.
  • the base material supports the porous membrane to provide strength to the entire composite membrane, and itself does not have substantial separation performance.
  • an arbitrary layer having substantially no separation performance may be provided between the porous membrane and the base material and laminated.
  • the base material examples include fabrics made of polyester polymers, polyamide polymers, polyolefin polymers, polysulfide polymers, and mixtures or copolymers thereof. Fabrics made of polysulfide polymers are particularly preferred because they have excellent stability against liquids to be treated containing organic solvents and liquids to be treated at high temperatures.
  • polysulfide-based polymers include polyphenylene sulfide (hereinafter referred to as "PPS").
  • the fabric is preferably a long fiber nonwoven fabric, a short fiber nonwoven fabric, or a woven or knitted fabric.
  • the short fiber nonwoven fabric refers to a nonwoven fabric with an average fiber length of less than 300 mm and an average fiber diameter of 3 to 30 ⁇ m. That is, the base material preferably contains polyphenylene sulfide as a main component.
  • the term "main component” preferably means, for example, 50 to 100% by mass of the entire base material.
  • the thickness of the base material affects the strength of the composite membrane and the packing density when it is made into an element.
  • the thickness of the base material is preferably 30 to 250 ⁇ m, more preferably 50 to 180 ⁇ m. Note that the thickness of the base material can be determined in the same manner as the thickness of the porous membrane.
  • the air permeability of the base material affects the separation performance and physical stability of the composite membrane.
  • the air permeability of the base material is preferably 0.2 to 4 cm 3 /cm 2 /s, more preferably 0.25 to 3 cm 3 /cm 2 /s, and 0.3 to 1 cm 3 /cm. More preferably, it is 2 /s.
  • the air permeability of the base material is 0.2 cm 3 /cm 2 /s or more, a portion of the polymer solution impregnates the base material, improving the adhesion between the porous membrane and the base material and providing a good result.
  • Composite membranes with physical stability can be obtained.
  • the air permeability of the base material is 4 cm 3 /cm 2 /s or less, defects due to bleed through will be less likely to occur when applying the polymer solution, which is the raw material for the porous membrane, to the base material, making it a good material.
  • a composite membrane with excellent separation performance can be obtained.
  • the porous membrane is preferably placed on the surface side of the composite membrane, and more preferably placed on the primary filtration side.
  • the membrane permeation flux of the porous membrane or composite membrane is 0.1 L/m 2 /h/bar or more if the porous membrane or composite membrane is OSRO (molecular weight cut off less than 200).
  • the porous membrane or composite membrane is OSN (molecular weight cut off 200 to 1,000), it is preferably 0.5 L/m 2 /h/bar or more, and the porous membrane or composite membrane
  • the membrane is OSU (molecular weight cut off 1,000 or more)
  • it is preferably 2.0 L/m 2 /h/bar or more.
  • the rejection rate of the porous membrane or composite membrane is preferably 80% or more from the viewpoint of industrial value.
  • the rejection rate (%) can be calculated from the solute concentration C (ppm) in the feed solution (undiluted solution) and the solute concentration D (ppm) in the permeate using the following formula 4.
  • Rejection rate (%) (1-D/C) x 100 (Formula 4)
  • Method for producing porous membrane and composite membrane The method for producing porous membrane and composite membrane of this embodiment is not particularly limited as long as porous membrane and composite membrane satisfying the above-mentioned desired characteristics can be obtained. It can be manufactured by the method.
  • the porous membrane and composite membrane of this embodiment can be manufactured, for example, by a method including the following steps (i) and (ii).
  • the monomers include at least one fluorine-based aromatic monomer selected from the group consisting of the above-mentioned fluorine atom-containing aromatic diamine monomers and fluorine atom-containing aromatic diisocyanate monomers, and the above-mentioned fluorine-containing aromatic monomers.
  • the acid anhydride monomer and at least one non-fluorine aromatic monomer selected from the group consisting of diamine monomers and aromatic diisocyanate monomers containing no fluorine atoms are used.
  • the molar ratio of the total of the fluorinated aromatic monomer and non-fluorinated aromatic monomer to the acid anhydride monomer is preferably 80:100 to 100:80.
  • the molecular weight of the aromatic polymer can be increased by making the total of the fluorinated aromatic monomer and the non-fluorinated aromatic monomer and the acid anhydride monomer about equimolar. On the other hand, by biasing the molar ratio to one side, the molecular weight of the polymer can be reduced.
  • a terminal capping agent may be added in order to control the molecular weight and molecular weight distribution of the aromatic polymer.
  • the terminal capping agent include phthalic anhydride, 2,3-naphthalenedicarboxylic anhydride, 1,2-naphthalenedicarboxylic anhydride, 4-methylphthalic anhydride, 3-methylphthalic anhydride, and 4-chlorophthalic anhydride.
  • Acid anhydrides acid anhydrides such as 4-tert-butylphthalic anhydride and 4-fluorophthalic anhydride, aniline, 1-naphthylamine, 2-chloroaniline, 4-chloroaniline, 3-aminophenol, 4-amino Examples include amines such as pyridine, and isocyanates such as n-butyl isocyanate, isopropylisocyanate, phenyl isocyanate, and benzyl isocyanate.
  • the Mw of the aromatic polyimide is preferably 8,000 to 200,000, more preferably 12,000 to 100,000.
  • the Mw of the aromatic polyimide is 8,000 or more, separation performance and mechanical strength preferable for porous membranes and composite membranes can be obtained.
  • the Mw of the aromatic polyimide is 200,000 or less, the viscosity of the polymer solution falls within an appropriate range, and good film formability can be achieved.
  • the weight average molecular weight of the polymer can be measured using gel permeation chromatography, and is a value converted to the molecular weight of polystyrene used as a standard substance.
  • the polymerization process will be described using the case of polymerizing aromatic polyimide as an example.
  • a fluorinated aromatic monomer and a non-fluorinated aromatic monomer are dissolved in a solvent, an acid anhydride is added thereto, and the polyamic acid solution is obtained by stirring at 0 to 100°C for 10 minutes to 100 hours. .
  • the temperature is raised to 120-300°C and stirred for 10 minutes to 100 hours to advance imidization and create an aromatic Obtain a polyimide solution.
  • toluene, o-xylene, m-xylene, p-xylene, etc. may be added to the reaction solution, and water generated in the imidization reaction may be removed by azeotroping with these solvents.
  • Examples of the solvent include dimethyl sulfoxide, dimethylformamide, dimethylacetamide, NMP, 2-pyrrolidone, ⁇ -butyrolactone (hereinafter referred to as "GBL”), 1,4-dioxane, 1,3-dimethyl-imidazolidinone, or A mixed solvent of these may be mentioned.
  • the polymerized polymer is purified.
  • a reprecipitation method is preferred. Water is preferred as a poor solvent for the polymer used in the reprecipitation method.
  • By drying the polymer whose purity has been increased by the reprecipitation method it is possible to obtain a solid aromatic polymer in which a fluorinated aromatic monomer, a non-fluorinated aromatic monomer, and an acid anhydride monomer are copolymerized. .
  • NIPS method Non-solvent induced phase separation method
  • TIPS method thermally induced phase separation method
  • a film forming method using the NIPS method will be described as an example.
  • the polymer and crosslinking agent obtained in "(2-1) Polymerization of polymer” are dissolved in a solvent to obtain a polymer solution.
  • a good solvent for the polymer is preferred.
  • the term “good solvent” refers to a solvent that can dissolve 5% by mass or more of a polymer even in a low temperature range of 60° C. or lower.
  • good solvents for polymers include dimethyl sulfoxide, dimethylformamide, dimethylacetamide, NMP, 2-pyrrolidone, GBL, 1,4-dioxane, 1,3-dimethyl-imidazolidinone, or a mixed solvent thereof. It will be done.
  • the concentration of the polymer in the polymer solution is preferably 8 to 30% by mass, more preferably 12 to 26% by mass.
  • concentration of the polymer in the polymer solution is 8% by mass or more, it is possible to form a porous membrane or a composite membrane that has strength and separation performance that can be used as a separation membrane.
  • concentration of the polymer in the polymer solution is 30% by mass or less, a porous membrane or a composite membrane having good permeability can be formed. Note that the preferable range of the concentration of the polymer in the polymer solution can be adjusted as appropriate depending on the polymer, solvent, base material, etc. used.
  • the polymer solution contains a polymer crosslinking agent.
  • the crosslinking agent for the polymer needs to be dissolved in the polymer solution, and at least one crosslinking agent selected from the group consisting of an epoxy crosslinking agent, a methylol crosslinking agent, an alkoxymethyl crosslinking agent, and a diamine crosslinking agent. It is preferable that
  • epoxy crosslinking agent examples include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, pentylene glycol diglycidyl ether, hexylene glycol diglycidyl ether, and cyclohexanedimethanol diglycidyl ether.
  • Ether resorcinol glycidyl ether, glycerol diglycidyl ether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, sorbitol diglycidyl ether, sorbitol polyglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether , polytetramethylene glycol diglycidyl ether, di(2,3-epoxypropyl) ether, 1,3-butadiene diepoxide, 1,5-hexadiene diepoxide, 1,2,7,8-diepoxyoctane, 1, Examples include 2,5,6-diepoxycyclooctane, 4-vinylcyclohexene diepoxide, bisphenol A diglycidyl ether, and maleimide-epoxy compounds.
  • methylol-based crosslinking agent examples include bisphenol A/formaldehyde polycondensate.
  • alkoxymethyl crosslinking agents examples include hexamethoxymethylmelamine, tetramethoxymethylglycoluril, 3,3',5,5'-tetrakis(methoxymethyl)-[1,1'-biphenyl]-4,4' -diol, 4,4',4''-ethylidene tris[2,6-(methoxymethyl)phenol] (hereinafter referred to as "GMOM").
  • diamine crosslinking agents examples include ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, 1,8-diamino-3,6-dioxaoctane, 1 , 4-cyclohexanediamine, 4,4'-diaminodicyclohexylmethane, and bis(aminomethyl)norbornane.
  • the concentration of the crosslinking agent in the polymer solution is preferably 1 to 20% by mass, more preferably 2 to 15% by mass.
  • concentration of the crosslinking agent in the polymer solution is 1% by mass or more, a porous membrane or a composite membrane having organic solvent resistance and good separation performance can be formed.
  • concentration of the crosslinking agent in the polymer solution is 20% by mass or less, a porous membrane or a composite membrane having good permeability can be formed.
  • the polymer solution may contain additives for adjusting pore diameter, porosity, hydrophilicity, elastic modulus, etc., as necessary.
  • additives for adjusting pore size and porosity include water, alcohols, water-soluble polymers such as polyethylene glycol, polyvinylpyrrolidone, polyvinyl alcohol, diethylene glycol, and polyacrylic acid, or salts thereof, and lithium chloride and chloride.
  • examples include inorganic salts such as sodium, calcium chloride, and lithium nitrate, and formamide.
  • Various surfactants can be mentioned as additives for adjusting hydrophilicity and elastic modulus.
  • the porous membrane For analysis of components such as monomers and crosslinking agents constituting the porous membrane, in the case of a composite membrane with a base material, etc., it is sufficient to first obtain only the porous membrane portion by peeling, and then perform various analyses.
  • the porous membrane is aromatic polyimide
  • the polyimide portion obtained by peeling is hydrolyzed with an alkali and then analyzed by nuclear magnetic resonance, liquid chromatography mass spectrometry, gas chromatography mass spectrometry, etc. By doing so, it is possible to identify the monomers that constitute the aromatic polyimide.
  • the porous membrane has chemical crosslinking using a crosslinking agent
  • the crosslinking agent can be identified by the method described above.
  • the porous membrane has a crosslinked structure that is not hydrolyzed by alkali
  • the crosslinked structure can be identified by analyzing the monomer reacted with the crosslinking agent using nuclear magnetic resonance or the like.
  • a polymer solution is applied or discharged and immersed in a coagulation bath to solidify.
  • a polymer solution is applied onto a flat metal plate or glass plate.
  • a polymer solution is applied to at least one surface of the base material.
  • a spin coater for the step of applying the polymer solution in the form of a flat film, a spin coater, flow coater, roll coater, spray, comma coater, bar coater, gravure coater, slit die coater, doctor blade, etc. can be used, for example.
  • a polymer solution is simultaneously discharged from the outer periphery of a double tube mouthpiece, and a core liquid is discharged from the center.
  • the hollow fiber base material is passed through a coating nozzle storing a polymer solution, and the polymer solution is applied to the outer surface of the base material.
  • a portion of the polymer solution is impregnated into the substrate.
  • the amount of polymer solution impregnated into the base material can be adjusted as appropriate depending on the time from coating the polymer solution onto the base material to immersing it in the coagulation bath, the viscosity of the polymer solution, the air permeability of the base material, etc. .
  • the time from application of the polymer solution to immersion in the coagulation bath is preferably 0.1 to 5 seconds.
  • the time for immersion in the coagulation bath is 0.1 seconds or more, the polymer solution can be sufficiently impregnated into the base material.
  • the time for immersion in the coagulation bath is set to 5 seconds or less, it is possible to suppress solidification of the polymer solution due to moisture in the air. Note that the preferred range of time until immersion in the coagulation bath can be adjusted as appropriate depending on the viscosity of the polymer solution used.
  • the coagulation bath preferably contains a non-solvent for the polymer solution.
  • non-solvent refers to a solvent that neither dissolves nor swells the polymer up to the melting point of the polymer or the boiling point of the solvent.
  • nonsolvent for the polymer include water, methanol, ethanol, trichlorethylene, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butylene glycol, pentanediol, hexanediol, or a mixed solvent thereof. Water is generally used.
  • the porous structure of the porous membrane is formed through a phase separation process induced by a nonsolvent.
  • a porous structure such as a three-dimensional network structure is formed due to phase separation, with a coarse layer near the surface of the membrane and a dense layer on the outermost surface. It is formed.
  • the solvent of the polymer solution is mixed with the non-solvent in a coagulation bath in which the polymer solution and non-solvent are brought into contact, increasing the concentration of the solvent derived from the polymer solution. do. Therefore, it is preferable to replace the coagulation bath as appropriate so that the composition of the liquid in the coagulation bath is maintained within a certain range.
  • concentration of the good solvent in the coagulation bath the faster the polymer solution coagulates, so the structure of the porous membrane or composite membrane becomes more homogeneous, and excellent separation performance can be exhibited.
  • the concentration of the good solvent in the coagulation bath is preferably 20% or less, more preferably 15% or less, and even more preferably 10% or less.
  • the obtained porous membrane or composite membrane may be washed with hot water or the like to remove the solvent remaining in the membrane.
  • the porous membrane or composite membrane is crosslinked in "(2-3) Crosslinking of the porous membrane or composite membrane" described later, the polymer crosslinking agent remaining in the porous membrane or composite membrane will not be eluted too much. Therefore, it is necessary to adjust the cleaning conditions accordingly. Further, the obtained porous membrane or composite membrane may be dried as necessary.
  • thermal crosslinking As a crosslinking method for porous membranes or composite membranes, thermal crosslinking, UV crosslinking, etc. can be used, but thermal crosslinking can be used to uniformly crosslink the inside of the porous membrane or composite membrane regardless of its coloring or thickness. Crosslinking is preferred.
  • a crosslinking method using thermal crosslinking will be described as an example.
  • Thermal crosslinking is preferably carried out in air.
  • the temperature of thermal crosslinking needs to be lower than the heat resistance temperature of the polymer and the base material, and is preferably 90 to 300°C, more preferably 120 to 250°C, and even more preferably 160 to 230°C.
  • the temperature of thermal crosslinking is 90° C. or higher, a porous membrane or a composite membrane having organic solvent resistance and good separation performance can be formed.
  • the temperature of thermal crosslinking is 300° C. or less, the porous structure formed by the NIPS method is maintained, and a porous membrane or composite membrane having good separation performance and permeation performance can be formed.
  • the thermal crosslinking time is preferably 30 seconds to 20 hours, more preferably 1 minute to 10 hours, and even more preferably 3 minutes to 4 hours.
  • the thermal crosslinking time is 30 seconds or more, a porous membrane or a composite membrane having organic solvent resistance and good separation performance can be formed.
  • the thermal crosslinking time is 20 hours or less, the porous structure formed by the NIPS method is maintained, and a porous membrane or composite membrane having good separation performance and permeation performance can be formed.
  • the main chain of the aromatic polymer that makes up the porous membrane is crosslinked, forming a three-dimensional network structure, which becomes stable even in organic solvents. It is assumed that separation performance is maintained.
  • the aromatic polymer is an aromatic polyimide
  • imidization of the polyamic acid remaining during this step progresses. Therefore, the degree of imidization of the aromatic polyimide can be adjusted not only by the imidization step in "(2-1) Polymerization of polymer” but also by the temperature and time of this step.
  • the obtained porous membrane or composite membrane may be washed with hot water or the like to remove the crosslinking agent of the polymer remaining in the membrane.
  • the obtained porous membrane or composite membrane may be immersed in a solvent to swell it.
  • a solvent By swelling the porous membrane or composite membrane with a solvent, it is possible to restore the permeation performance of the porous membrane or composite membrane that was completely dried and airlocked during crosslinking.
  • porous Membranes and composite membranes of this embodiment are made of a feed liquid channel material such as a plastic net, a permeate channel material such as tricot, and, if necessary, a material for increasing pressure resistance. It is wound together with a film around a cylindrical liquid collecting pipe with a large number of holes, and is suitably used as a spiral type element. Furthermore, these elements can be connected in series or in parallel to form a porous membrane or composite membrane module housed in a pressure vessel. It is preferable to use materials for these elements and module parts that are resistant to the supply liquid.
  • porous membranes and composite membranes can be combined with a pump that supplies a feed liquid, a device that pre-treats the feed water, etc. to configure a fluid separation device. Can be done.
  • this fluid separation device it is possible to separate the feed liquid into a permeate liquid from which solutes, impurities, etc. have been removed, and a concentrate liquid that has not passed through the membrane, thereby obtaining a liquid suitable for the purpose.
  • the element may be classified into flat plate type, spiral type, pleated type, tubular type, hollow fiber type, etc. depending on the form of the porous membrane and composite membrane, but any form may be used.
  • a plurality of modules may be used depending on the purity of the liquid to be supplied and the purity required after separation.
  • the membrane permeation flux of the porous membrane or composite membrane was evaluated according to the membrane type.
  • OSRO molecular weight cut off less than 200
  • a cross-flow membrane filtration test was performed by supplying a 20 ppm standard polystyrene (Mw 162)/NMP solution at an operating pressure of 30 bar.
  • OSN molecular weight cut off 200-1,000
  • a cross-flow membrane filtration test was conducted by supplying a 20 ppm standard polystyrene (Mw 580)/NMP solution at an operating pressure of 15 bar.
  • a cross-flow membrane filtration test was conducted by supplying a 20 ppm standard polystyrene (Mw 100,000)/NMP solution at an operating pressure of 2 bar. From the amount of permeated liquid (L), unit membrane area (m 2 ) and unit time (h), calculate the membrane permeation flux (L/m 2 /h/bar) of the porous membrane or composite membrane using equation 3 below. Calculated. Further, the rejection rate (%) of the porous membrane or composite membrane was calculated from the standard polystyrene concentration C (ppm) in the stock solution and the standard polystyrene concentration D (ppm) in the permeate using the following formula 4.
  • copolymerization ratio of the fluorinated aromatic monomer and the non-fluorinated aromatic monomer was calculated using proton nuclear magnetic resonance method (JNM-ECZ400R (manufactured by JEOL Ltd. (JEOL)).
  • JNM-ECZ400R proton nuclear magnetic resonance method
  • diamine monomers 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane is used as a fluorinated aromatic monomer, 4,4'-diaminodiphenyl ether is used as a non-fluorinated aromatic monomer, and 4,4'-diaminodiphenyl ether is used as an acid anhydride monomer.
  • test piece with a width of 25 mm and a length of 200 mm.
  • the test piece was adhered to the ground 100 mm from one end using Kapton double-sided tape (manufactured by Teraoka Seisakusho Co., Ltd.). After that, the end of the unbonded specimen was fixed with the grip of the tensile tester so that the specimen on the unbonded side was at a constant angle of 90 degrees with the ground, and the tensile strength was 30 g at a tensile speed of 20 mm/min. Alternatively, a tensile test was performed until a load of 50 g was applied.
  • test piece was adhered to the ground using Kapton double-sided tape to prevent the adhesive surface from peeling off.
  • This test was performed 5 times using different test pieces to check the presence or absence of breaks and cracks, and a case where neither breaks nor cracks were observed in all 5 tests was rated as " ⁇ ".
  • the aspect ratio of the macrovoids was determined by randomly selecting 10 macrovoids in one image and using the image processing software "ImageJ" to calculate the aspect ratio of each macrovoid in the direction perpendicular to the porous membrane surface.
  • the length and the length in the horizontal direction to the porous membrane surface were determined, and the aspect ratio was calculated. This was performed using five images, and the average value of the aspect ratios of the obtained 50 macrovoids was taken as the aspect ratio of the porous membrane.
  • Aromatic diamine monomer containing fluorine atom 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane (manufactured by Tokyo Kasei Kogyo)
  • Aromatic diamine monomer containing fluorine atom 2,2-bis(4-aminophenyl)hexafluoropropane (manufactured by Tokyo Chemical Industry Co., Ltd.)
  • Terminal capping agent 3-aminophenol (manufactured by Tokyo Kasei Kogyo)
  • Example 1 4.4% by mass of 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane, 4.8% by mass of 4,4'-diaminodiphenyl ether, 0.18% by mass of 3-aminophenol, and 82% by mass of NMP.
  • An aromatic polyamic acid solution was obtained by dissolving at 20°C, adding 8.6% by mass of 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, and stirring at 20°C for 3 hours. . Subsequently, imidization was progressed by stirring at 200° C. for 3 hours, and the aromatic polyimide was purified by reprecipitation using water as a poor solvent. The Mw of the obtained aromatic polyimide was 28,000.
  • the obtained porous membrane was heated at 200° C. for 2 hours to crosslink the aromatic polyimide.
  • the degree of imidization of the obtained crosslinked polymer was 0.45.
  • the thickness of the obtained porous membrane was 50 ⁇ m. Table 1 shows the results of evaluating the obtained porous membrane.
  • Example 2 The polymer solution obtained in Example 1 was applied to a PPS short fiber nonwoven fabric with an air permeability of 0.6 cm 3 /cm 2 /s at 25°C, and after 3 seconds, it was immersed in a coagulation bath consisting of distilled water at 25°C for 30 seconds. A composite membrane was obtained by solidifying and drying.
  • the resulting composite membrane was heated at 200°C for 2 hours to crosslink the aromatic polyimide.
  • the degree of imidization of the obtained crosslinked polymer was 0.45.
  • the thickness of the obtained composite membrane was 180 ⁇ m. Table 1 shows the results of evaluating the obtained composite membrane.
  • Example 3 3.9% by mass of 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane, 4.2% by mass of 4,4'-diaminodiphenyl ether, and 82% by mass of NMP were dissolved at 20°C, and 3,3' , 9.9% by mass of 4,4'-diphenyl ether tetracarboxylic dianhydride was added and stirred at 20°C for 3 hours to obtain an aromatic polyamic acid solution. Subsequently, imidization was progressed by stirring at 200° C. for 3 hours, and the aromatic polyimide was purified by reprecipitation using water as a poor solvent. The Mw of the obtained aromatic polyimide was 65,000, and the copolymerization ratio of the fluorine-based aromatic monomer and the non-fluorine-based aromatic monomer was 33:67.
  • the resulting composite membrane was heated at 200°C for 2 hours to crosslink the aromatic polyimide.
  • the degree of imidization of the obtained crosslinked polymer was 0.53.
  • the thickness of the obtained composite membrane was 165 ⁇ m. Table 1 shows the results of evaluating the obtained composite membrane.
  • Example 4 3.4% by mass of 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane, 4.6% by mass of 4,4'-diaminodiphenyl ether, and 82% by mass of NMP were dissolved at 20°C, and 3,3' , 4,4'-diphenyl ether tetracarboxylic dianhydride (10% by mass) was added thereto, and the mixture was stirred at 20° C. for 3 hours to obtain an aromatic polyamic acid solution. Subsequently, imidization was progressed by stirring at 200° C. for 3 hours, and the aromatic polyimide was purified by reprecipitation using water as a poor solvent. The Mw of the obtained aromatic polyimide was 54,000, and the copolymerization ratio of the fluorinated aromatic monomer and the non-fluorinated aromatic monomer was 29:71.
  • the obtained porous membrane was heated at 200° C. for 2 hours to crosslink the aromatic polyimide.
  • the degree of imidization of the obtained crosslinked polymer was 0.54.
  • the thickness of the obtained porous membrane was 41 ⁇ m. Table 1 shows the results of evaluating the obtained porous membrane.
  • Example 5 5.6% by mass of 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane, 3.0% by mass of 4,4'-diaminodiphenyl ether, and 82% by mass of NMP were dissolved at 20°C, and 3,3' , 9.4% by mass of 4,4'-diphenyl ether tetracarboxylic dianhydride was added and stirred at 20°C for 3 hours to obtain an aromatic polyamic acid solution. Subsequently, imidization was progressed by stirring at 200° C. for 3 hours, and the aromatic polyimide was purified by reprecipitation using water as a poor solvent. The Mw of the obtained aromatic polyimide was 58,000, and the copolymerization ratio of the fluorine-based aromatic monomer and the non-fluorine-based aromatic monomer was 50:50.
  • the obtained porous membrane was heated at 200° C. for 2 hours to crosslink the aromatic polyimide.
  • the degree of imidization of the obtained crosslinked polymer was 0.53.
  • the thickness of the obtained porous membrane was 43 ⁇ m. Table 1 shows the results of evaluating the obtained porous membrane.
  • Example 6 6.0% by mass of 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane, 2.7% by mass of 4,4'-diaminodiphenyl ether, and 82% by mass of NMP were dissolved at 20°C, and 3,3' , 9.3% by mass of 4,4'-diphenyl ether tetracarboxylic dianhydride was added and stirred at 20°C for 3 hours to obtain an aromatic polyamic acid solution. Subsequently, imidization was progressed by stirring at 200° C. for 3 hours, and the aromatic polyimide was purified by reprecipitation using water as a poor solvent. The Mw of the obtained aromatic polyimide was 56,000, and the copolymerization ratio of the fluorine-based aromatic monomer and the non-fluorine-based aromatic monomer was 55:45.
  • the obtained porous membrane was heated at 200° C. for 2 hours to crosslink the aromatic polyimide.
  • the degree of imidization of the obtained crosslinked polymer was 0.58.
  • the thickness of the obtained porous membrane was 46 ⁇ m. Table 1 shows the results of evaluating the obtained porous membrane.
  • Example 7 20% by mass of the aromatic polyimide obtained in Example 3, 2% by mass of GMOM, 54% by mass of NMP, and 24% by mass of 1,4-dioxane were dissolved at 25° C. to prepare a polymer solution.
  • This polymer solution was applied to a PPS short fiber nonwoven fabric with an air permeability of 0.6 cm 3 /cm 2 /s at 25°C, and after 3 seconds, it was immersed in a coagulation bath consisting of distilled water at 25°C for 30 seconds to coagulate.
  • a composite membrane was obtained by drying.
  • the resulting composite membrane was heated at 200°C for 2 hours to crosslink the aromatic polyimide.
  • the degree of imidization of the obtained crosslinked polymer was 0.54.
  • the thickness of the obtained composite membrane was 165 ⁇ m. Table 1 shows the results of evaluating the obtained composite membrane.
  • Comparative example 1 22% by mass of the aromatic polyimide obtained in Example 1, 39% by mass of NMP, and 39% by mass of 1,4-dioxane were dissolved at 25° C. to prepare a polymer solution. Thereafter, a porous membrane was obtained in the same process as in Example 1, but when the porous membrane was immersed in NMP, it dissolved, so it could not be used as a separation membrane for a liquid to be treated containing an organic solvent.
  • Example 2 A composite membrane was obtained in the same manner as in Example 2 until heating. The obtained composite membrane was heated at 80° C. for 2 hours, but when the composite membrane was immersed in NMP, the porous membrane dissolved, so it could not be used as a separation membrane for a liquid to be treated containing an organic solvent.
  • the obtained porous membrane was heated at 200° C. for 2 hours to crosslink the aromatic polyimide.
  • the degree of imidization of the obtained crosslinked polymer was 0.56.
  • the thickness of the obtained porous membrane was 40 ⁇ m. Table 1 shows the results of evaluating the obtained porous membrane.
  • the obtained porous membrane had lower mechanical properties than the porous membrane of the example.
  • the present invention by improving film formability, it is possible to continuously and stably maintain separation performance and permeation performance for liquids to be treated containing organic solvents and liquids to be treated at high temperatures. , porous membranes and composite membranes.

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Abstract

A porous film and a composite film according to the present invention each contain a crosslinked polymer in which aromatic polymers are crosslinked together. The aromatic polymers are obtained by copolymerizing at least a fluorine-based aromatic monomer that is at least one selected from the group consisting of fluorine-atom-containing aromatic diamine monomers and fluorine-atom-containing aromatic diisocyanate monomers, a non-fluorine-based aromatic monomer that is at least one selected from the group consisting of fluorine-atom-free aromatic diamine monomers and fluorine-atom-free aromatic diisocyanate monomers, and an acid anhydride monomer. The copolymerization ratio of the fluorine-based aromatic monomer and the non-fluorine-based aromatic monomer in the aromatic polymer is 25:75 to 70:30 in terms of molar ratio.

Description

多孔質膜及び複合膜Porous membrane and composite membrane
　本発明は、多孔質膜及び複合膜に関する。 The present invention relates to porous membranes and composite membranes.
　液状混合物の分離には、省エネルギーおよび省資源のためのプロセスとして、膜分離法が広く利用されている。膜分離法のターゲットは水処理用途が主であるが、近年、有機溶媒を対象とした分離用途が拡大している。具体的には、化成品、医薬、食品、繊維、電子材料等の製造において、有機溶媒を含んだ排水の濃縮、有機溶媒中の溶質除去、有機溶媒中からの有価物回収、混合有機溶媒の分離回収等に膜分離法が利用されつつある。 Membrane separation methods are widely used to separate liquid mixtures as a process for saving energy and resources. The main target of membrane separation methods is water treatment applications, but in recent years, separation applications targeting organic solvents have expanded. Specifically, in the production of chemical products, medicines, foods, textiles, electronic materials, etc., we concentrate wastewater containing organic solvents, remove solutes from organic solvents, recover valuables from organic solvents, and use mixed organic solvents. Membrane separation methods are being used for separation and recovery.
　これらは対象とする分離物の大きさによって名称が異なり、分子量２００未満の低分子を分離する場合ＯＳＲＯ（ｏｒｇａｎｉｃ　ｓｏｌｖｅｎｔ　ｒｅｖｅｒｓｅ　ｏｓｍｏｓｉｓ）、分子量２００～１，０００の分子を除去する場合、ＯＳＮ（ｏｒｇａｎｉｃ　ｓｏｌｖｅｎｔ　ｎａｎｏｆｉｌｔｒａｔｉｏｎ）、それ以上の分子、不純物を除去する場合、ＯＳＵ（ｏｒｇａｎｉｃ　ｓｏｌｖｅｎｔ　ｕｌｔｒａｆｉｌｔｒａｔｉｏｎ）等と呼称される。 These have different names depending on the size of the target substance to be separated; OSRO (organic solvent reverse osmosis) is used to separate low molecules with a molecular weight of less than 200, and OSN (organic solvent reverse osmosis) is used to remove molecules with a molecular weight of 200 to 1,000. When removing more molecules and impurities, it is called OSU (organic solvent ultrafiltration).
　一般的に水処理用として使用される高分子膜は、有機溶媒中で膨潤もしくは溶解するため安定性を維持することが出来ず、分離効率が極端に低下してしまう。そのため有機溶媒を含む液状混合物の分離には、耐有機溶媒性を有する膜を用いる必要がある。 Polymer membranes generally used for water treatment cannot maintain stability because they swell or dissolve in organic solvents, resulting in an extremely low separation efficiency. Therefore, for separation of liquid mixtures containing organic solvents, it is necessary to use membranes that are resistant to organic solvents.
　有機溶媒を含有した液体中での使用を主な目的とした分離膜としては種々のものが開示されている。例えば特許文献１には、フルオロポリマー及びイミド基含有ポリマーから選択されるポリマーを含む多孔質層に、ポリアミド系分離機能層を積層した、複合半透膜が開示されている。特許文献１には、これによって、耐油性に優れ、且つ、十分な脱塩処理性能を有する分離膜が得られると記載されている。 Various separation membranes have been disclosed that are primarily intended for use in liquids containing organic solvents. For example, Patent Document 1 discloses a composite semipermeable membrane in which a polyamide-based separation functional layer is laminated on a porous layer containing a polymer selected from fluoropolymers and imide group-containing polymers. Patent Document 1 states that this provides a separation membrane that has excellent oil resistance and sufficient desalting performance.
　非特許文献１には、フッ素原子を含有する芳香族ジアミンモノマー又は芳香族ジイソシアネートモノマーと、酸無水物モノマーと、が重合した芳香族ポリマーが開示されているが、この芳香族ポリマーは力学物性に劣るため、多孔質膜及び複合膜の製膜時及び架橋時にひび割れが発生し、分離膜として使用できない場合があることが知られている。 Non-Patent Document 1 discloses an aromatic polymer obtained by polymerizing an aromatic diamine monomer or aromatic diisocyanate monomer containing a fluorine atom and an acid anhydride monomer, but this aromatic polymer has poor mechanical properties. It is known that due to the poor quality of membranes, cracks may occur during the production and crosslinking of porous membranes and composite membranes, making them unusable as separation membranes.
日本国特開２０２１－１０７０７１号公報Japanese Patent Application Publication No. 2021-107071
　しかしながら、特許文献１に記載されている複合半透膜は、炭化水素油のような非極性有機溶媒に対しては耐性を有するものの、極性有機溶媒に対する十分な耐性は有さないという問題があった。さらに、特許文献１に記載されている複合半透膜は、ポリアミド系分離機能層により脱塩処理性能を有するものの、ポリアミドのガラス転移温度（４０～５０℃程度）以上の高温では脱塩処理性能が著しく低下するという問題があった。 However, although the composite semipermeable membrane described in Patent Document 1 has resistance to non-polar organic solvents such as hydrocarbon oil, it does not have sufficient resistance to polar organic solvents. Ta. Furthermore, although the composite semipermeable membrane described in Patent Document 1 has desalination treatment performance due to the polyamide-based separation functional layer, desalination treatment performance is poor at high temperatures above the glass transition temperature of polyamide (approximately 40 to 50 degrees Celsius). There was a problem in that the value decreased significantly.
　また上述のように、非特許文献１に記載の芳香族ポリマーは、多孔質膜及び複合膜の製膜時並びに架橋時にひび割れが発生して分離膜として使用できない場合があるという問題があることから、製膜性を向上させる必要があった。 Furthermore, as mentioned above, the aromatic polymer described in Non-Patent Document 1 has the problem that it may not be usable as a separation membrane due to cracks occurring during film formation and crosslinking of porous membranes and composite membranes. , it was necessary to improve film formability.
　そこで本発明は、製膜性が高く、耐有機溶媒性を備えつつ、分離性能と透過性能に優れた多孔質膜及び複合膜を提供することを目的とする。 Therefore, an object of the present invention is to provide a porous membrane and a composite membrane that have high film formability, organic solvent resistance, and excellent separation performance and permeation performance.
　本発明者らは、多孔質膜が、芳香族ポリマー同士が架橋された架橋ポリマーを含有し、前記芳香族ポリマーが、少なくとも、フッ素原子を含有する芳香族ジアミンモノマー及びフッ素原子を含有する芳香族ジイソシアネートモノマーからなる群から選択される少なくとも１つのフッ素系芳香族モノマーと、フッ素原子を含有しない芳香族ジアミンモノマー及びフッ素原子を含有しない芳香族ジイソシアネートモノマーからなる群から選択される少なくとも１つの非フッ素系芳香族モノマーと、酸無水物モノマーと、を共重合させてなるポリマーであり、芳香族ポリマーにおける前記フッ素系芳香族モノマーと、非フッ素系芳香族モノマーとの共重合比が、モル比で、２５：７５～７０：３０の範囲であることにより、製膜性が向上し、耐有機溶媒性を備えつつ、分離性能と透過性能に優れた多孔質膜及び複合膜が得られることを見出し、本発明を完成するに至った。 The present inventors have proposed that the porous membrane contains a crosslinked polymer in which aromatic polymers are crosslinked, and that the aromatic polymer includes at least an aromatic diamine monomer containing a fluorine atom and an aromatic diamine monomer containing a fluorine atom. At least one fluorine-based aromatic monomer selected from the group consisting of diisocyanate monomers, and at least one non-fluorine selected from the group consisting of aromatic diamine monomers that do not contain fluorine atoms and aromatic diisocyanate monomers that do not contain fluorine atoms. It is a polymer formed by copolymerizing an aromatic monomer and an acid anhydride monomer, and the copolymerization ratio of the fluorinated aromatic monomer and the non-fluorinated aromatic monomer in the aromatic polymer is a molar ratio , in the range of 25:75 to 70:30, it was found that porous membranes and composite membranes with improved membrane formability, organic solvent resistance, and excellent separation performance and permeation performance could be obtained. , we have completed the present invention.
　上記課題を解決するため、本実施形態は、次の（１）～（１０）を特徴とする。
（１）　芳香族ポリマー同士が架橋された架橋ポリマーを含有し、
　前記芳香族ポリマーが、少なくとも、フッ素原子を含有する芳香族ジアミンモノマー及びフッ素原子を含有する芳香族ジイソシアネートモノマーからなる群から選択される少なくとも１つのフッ素系芳香族モノマーと、フッ素原子を含有しない芳香族ジアミンモノマー及びフッ素原子を含有しない芳香族ジイソシアネートモノマーからなる群から選択される少なくとも１つの非フッ素系芳香族モノマーと、酸無水物モノマーと、を共重合させてなるポリマーであり、
　前記芳香族ポリマーにおける、前記フッ素系芳香族モノマーと前記非フッ素系芳香族モノマーとの共重合比が、モル比で、２５：７５～７０：３０の範囲である、多孔質膜。
（２）　前記フッ素系芳香族モノマーと前記非フッ素系芳香族モノマーとの共重合比が、モル比で、２５：７５～５０：５０の範囲である、上記（１）記載の多孔質膜。
（３）　前記芳香族ポリマーが、芳香族ポリイミドを含有する、上記（１）又は（２）記載の多孔質膜。
（４）　前記架橋ポリマーのイミド化度が０．２～１．２である、上記（３）記載の多孔質膜。
（５）　前記架橋ポリマーが、エポキシ系架橋剤、メチロール系架橋剤、アルコキシメチル系架橋剤、及びジアミン系架橋剤からなる群から選択される少なくとも１つの架橋剤により、前記芳香族ポリマー同士が架橋されたポリマーである、上記（１）～（４）のいずれか１つに記載の多孔質膜。
（６）　前記多孔質膜が、少なくとも緻密層と粗大層の２層を有する、上記（１）～（５）のいずれか１つに記載の多孔質膜。
（７）　前記多孔質膜の断面に占めるマクロボイドの面積割合が３～６０％である、上記（１）～（６）のいずれか１つに記載の多孔質膜。
（８）　前記マクロボイドが膜の厚み方向に長軸を有し、且つ、アスペクト比が２．０以上である、上記（７）に記載の多孔質膜。
（９）　上記（１）～（８）のいずれか１つに記載の多孔質膜が、基材の少なくとも一方の面側に積層された複合膜。
（１０）　前記基材が、ポリフェニレンスルファイドを主成分とする、上記（９）記載の複合膜。
（１１）　上記（１）～（８）のいずれか１つに記載の多孔質膜を備えるモジュール。
（１２）　上記（９）に記載の複合膜を備えるモジュール。
（１３）　上記（１２）に記載のモジュールを備える流体分離装置。
（１４）　下記（ｉ）及び（ｉｉ）の工程を含む、多孔質膜を製造する方法。
（ｉ）少なくとも、フッ素原子を含有する芳香族ジアミンモノマー及びフッ素原子を含有する芳香族ジイソシアネートモノマーからなる群から選択される少なくとも１つのフッ素系芳香族モノマーと、フッ素原子を含有しない芳香族ジアミンモノマー及びフッ素原子を含有しない芳香族ジイソシアネートモノマーからなる群から選択される少なくとも１つの非フッ素系芳香族モノマーと、酸無水物モノマーと、を共重合して芳香族ポリマーを得ること。
（ｉｉ）架橋剤によって上記（ｉ）で得られた芳香族ポリマーを架橋すること。
（１５）　前記架橋剤が、エポキシ系架橋剤、メチロール系架橋剤、アルコキシメチル系架橋剤、及びジアミン系架橋剤からなる群から選択される少なくとも一つの架橋剤である、上記（１４）に記載の多孔質膜を製造する方法。 In order to solve the above problems, the present embodiment is characterized by the following (1) to (10).
(1) Contains a crosslinked polymer in which aromatic polymers are crosslinked,
The aromatic polymer contains at least one fluorine-based aromatic monomer selected from the group consisting of an aromatic diamine monomer containing a fluorine atom and an aromatic diisocyanate monomer containing a fluorine atom, and an aromatic compound containing no fluorine atom. A polymer obtained by copolymerizing at least one non-fluorine-based aromatic monomer selected from the group consisting of diamine monomers and aromatic diisocyanate monomers containing no fluorine atoms, and an acid anhydride monomer,
A porous membrane, wherein a copolymerization ratio of the fluorinated aromatic monomer and the non-fluorinated aromatic monomer in the aromatic polymer is in the range of 25:75 to 70:30 in molar ratio.
(2) The porous membrane according to (1) above, wherein the copolymerization ratio of the fluorinated aromatic monomer and the non-fluorinated aromatic monomer is in the range of 25:75 to 50:50 in molar ratio.
(3) The porous membrane according to (1) or (2) above, wherein the aromatic polymer contains aromatic polyimide.
(4) The porous membrane according to (3) above, wherein the degree of imidization of the crosslinked polymer is 0.2 to 1.2.
(5) In the crosslinked polymer, the aromatic polymers are crosslinked with each other by at least one crosslinking agent selected from the group consisting of an epoxy crosslinking agent, a methylol crosslinking agent, an alkoxymethyl crosslinking agent, and a diamine crosslinking agent. The porous membrane according to any one of (1) to (4) above, which is a polymer made of
(6) The porous membrane according to any one of (1) to (5) above, wherein the porous membrane has at least two layers, a dense layer and a coarse layer.
(7) The porous membrane according to any one of (1) to (6) above, wherein the area ratio of macrovoids in the cross section of the porous membrane is 3 to 60%.
(8) The porous membrane according to (7) above, wherein the macrovoid has a long axis in the thickness direction of the membrane and has an aspect ratio of 2.0 or more.
(9) A composite membrane in which the porous membrane according to any one of (1) to (8) above is laminated on at least one surface of a base material.
(10) The composite membrane according to (9) above, wherein the base material contains polyphenylene sulfide as a main component.
(11) A module comprising the porous membrane according to any one of (1) to (8) above.
(12) A module comprising the composite membrane according to (9) above.
(13) A fluid separation device comprising the module according to (12) above.
(14) A method for producing a porous membrane, including the steps (i) and (ii) below.
(i) At least one fluorine-based aromatic monomer selected from the group consisting of an aromatic diamine monomer containing a fluorine atom and an aromatic diisocyanate monomer containing a fluorine atom, and an aromatic diamine monomer containing no fluorine atom. and at least one non-fluorine-based aromatic monomer selected from the group consisting of aromatic diisocyanate monomers containing no fluorine atoms, and an acid anhydride monomer to obtain an aromatic polymer.
(ii) Crosslinking the aromatic polymer obtained in (i) above with a crosslinking agent.
(15) As described in (14) above, wherein the crosslinking agent is at least one crosslinking agent selected from the group consisting of an epoxy crosslinking agent, a methylol crosslinking agent, an alkoxymethyl crosslinking agent, and a diamine crosslinking agent. A method of manufacturing a porous membrane.
　本発明によれば、製膜性が高いことにより、有機溶媒を含有する被処理液及び高温の被処理液に対して、継続的に安定して分離性能と透過性能とを維持可能な、多孔質膜及び複合膜を提供することができる。 According to the present invention, the porous film has high film-forming properties and can continuously and stably maintain separation performance and permeation performance for liquids to be treated containing organic solvents and liquids to be treated at high temperatures. Both membranes and composite membranes can be provided.
　以下に、本発明の実施形態について詳細に説明するが、本発明はこれらによって何ら限定されるものではない。
　数値範囲の「～」は、その前後の数値を含む範囲であり、例えば、「０～１００」は、０以上であり、且つ、１００以下である範囲を意味する。 Embodiments of the present invention will be described in detail below, but the present invention is not limited thereto.
"~" in a numerical range is a range that includes the numbers before and after it; for example, "0-100" means a range that is 0 or more and 100 or less.
　１．多孔質膜及び複合膜
　（１－１）多孔質膜
　本実施形態の多孔質膜は、芳香族ポリマー同士が架橋された架橋ポリマーを含有し、前記芳香族ポリマーが、少なくとも、フッ素原子を含有する芳香族ジアミンモノマー及びフッ素原子を含有する芳香族ジイソシアネートモノマーからなる群から選択される少なくとも１つのフッ素系芳香族モノマーと、フッ素原子を含有しない芳香族ジアミンモノマー及びフッ素原子を含有しない芳香族ジイソシアネートモノマーからなる群から選択される少なくとも１つの非フッ素系芳香族モノマーと、酸無水物モノマーと、を共重合させてなるポリマーであり、前記芳香族ポリマーにおけるフッ素系芳香族モノマーと、非フッ素系芳香族モノマーとの共重合比が、モル比で、２５：７５～７０：３０の範囲であることを特徴とする。 1. Porous membrane and composite membrane (1-1) Porous membrane The porous membrane of this embodiment contains a crosslinked polymer in which aromatic polymers are crosslinked, and the aromatic polymer contains at least a fluorine atom. At least one fluorinated aromatic monomer selected from the group consisting of an aromatic diamine monomer and an aromatic diisocyanate monomer containing a fluorine atom, an aromatic diamine monomer that does not contain a fluorine atom, and an aromatic diisocyanate monomer that does not contain a fluorine atom. A polymer obtained by copolymerizing at least one non-fluorinated aromatic monomer selected from the group consisting of an acid anhydride monomer, and a fluorinated aromatic monomer in the aromatic polymer and a non-fluorinated aromatic monomer. It is characterized in that the copolymerization ratio with the group monomer is in the range of 25:75 to 70:30 in terms of molar ratio.
（１－１－１）フッ素系芳香族モノマー
　フッ素原子を含有する芳香族ジアミンモノマーとしては、例えば、１，４－ジアミノ－２，３，５，６－テトラフルオロベンゼン、１，３－ジアミノ－２，４，５，６－テトラフルオロベンゼン、２，２－ビス（４－アミノフェニル）ヘキサフルオロプロパン、２，２’－ビス（トリフルオロメチル）ベンジジン、オクタフルオロベンジジン、４，４’－ジヒドロキシ－３，３’－ジアミノフェニルヘキサフルオロプロパン、２，２’－ビス（トリフルオロメチル）－４，４’－ジアミノジフェニルエーテル、１，４－ビス（４－アミノ－２－トリフルオロメチルフェノキシ）ベンゼン、９，９－ビス（３－アミノ－４－ヒドロキシフェニル）フルオレンが挙げられる。 (1-1-1) Fluorine-based aromatic monomer Examples of aromatic diamine monomers containing fluorine atoms include 1,4-diamino-2,3,5,6-tetrafluorobenzene, 1,3-diamino- 2,4,5,6-tetrafluorobenzene, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2'-bis(trifluoromethyl)benzidine, octafluorobenzidine, 4,4'-dihydroxy -3,3'-diaminophenylhexafluoropropane, 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether, 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene , 9,9-bis(3-amino-4-hydroxyphenyl)fluorene.
　また、フッ素原子を含有する芳香族ジイソシアネートモノマーとしては、例えば、２，２－ビス（４－イソシアナトフェニル）ヘキサフルオロプロパンが挙げられる。 Furthermore, examples of aromatic diisocyanate monomers containing fluorine atoms include 2,2-bis(4-isocyanatophenyl)hexafluoropropane.
　中でも、芳香族ポリマーの溶解性等の観点から、フッ素系芳香族モノマーとしては、フッ素原子を含有する芳香族ジアミンモノマーが好ましく、中でも２，２－ビス（４－アミノフェニル）ヘキサフルオロプロパン、又は、４，４’－ジヒドロキシ－３，３’－ジアミノフェニルヘキサフルオロプロパンを用いることが好ましい。 Among them, from the viewpoint of the solubility of the aromatic polymer, the fluorine-based aromatic monomer is preferably an aromatic diamine monomer containing a fluorine atom, and among them, 2,2-bis(4-aminophenyl)hexafluoropropane, or , 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane is preferably used.
　上記フッ素系芳香族モノマーを用いることで、重合後の芳香族ポリマーの溶解性が良好になるため、ポリマー溶液を用いた多孔質膜及び複合膜の製膜が容易になる。 By using the above-mentioned fluorine-based aromatic monomer, the solubility of the aromatic polymer after polymerization becomes good, so it becomes easy to form porous membranes and composite membranes using polymer solutions.
（１－１－２）非フッ素系芳香族モノマー
　フッ素系芳香族モノマーと、酸無水物モノマーと、を共重合させてなる芳香族ポリマーが、さらに非フッ素系芳香族モノマーを共重合していることで、芳香族ポリマーの溶解性と力学物性とを両立することができ、製膜性が向上する。 (1-1-2) Non-fluorinated aromatic monomer An aromatic polymer formed by copolymerizing a fluorinated aromatic monomer and an acid anhydride monomer is further copolymerized with a non-fluorinated aromatic monomer. This makes it possible to achieve both solubility and mechanical properties of the aromatic polymer, thereby improving film formability.
　フッ素原子を含有しない芳香族ジアミンモノマーとしては、例えば、４，４’－ジアミノジフェニルエーテル、３，３’－オキシジアニリンが挙げられ、フッ素原子を含有しない芳香族ジイソシアネートモノマーとしては、例えばビス（４－イソシアナトフェニル）メタンが挙げられる。中でも、モノマーの入手性や芳香族ポリマーの力学物性等の観点から、フッ素原子を含有しない芳香族ジアミンモノマーが好ましく、中でも４，４’－ジアミノジフェニルエーテルを用いることが好ましい。 Examples of aromatic diamine monomers that do not contain fluorine atoms include 4,4'-diaminodiphenyl ether and 3,3'-oxydianiline, and examples of aromatic diisocyanate monomers that do not contain fluorine atoms include, for example, bis(4 -isocyanatophenyl)methane. Among these, aromatic diamine monomers that do not contain fluorine atoms are preferred from the viewpoint of monomer availability and mechanical properties of the aromatic polymer, and among them, 4,4'-diaminodiphenyl ether is preferably used.
　本実施形態の多孔質膜において、フッ素系芳香族モノマーと、非フッ素系芳香族モノマーとの共重合比は、モル比で、２５：７５～７０：３０の範囲である。フッ素系芳香族モノマーと、非フッ素系芳香族モノマーとの共重合比が（２５以上）：（７５以下）であることで、溶解性に優れた芳香族ポリマーが得られる。一方、上記共重合比が（７０以下）：（３０以上）であることで、力学物性に優れた芳香族ポリマーが得られる。上記共重合比は、２５：７５～６５：３５の範囲であることが好ましく、２５：７５～６０：４０の範囲であることがより好ましく、２５：７５～５０：５０であることがさらに好ましい。 In the porous membrane of this embodiment, the copolymerization ratio of the fluorine-based aromatic monomer and the non-fluorine-based aromatic monomer is in the range of 25:75 to 70:30 in terms of molar ratio. When the copolymerization ratio of the fluorine-based aromatic monomer and the non-fluorine-based aromatic monomer is (25 or more): (75 or less), an aromatic polymer with excellent solubility can be obtained. On the other hand, when the copolymerization ratio is (70 or less):(30 or more), an aromatic polymer with excellent mechanical properties can be obtained. The copolymerization ratio is preferably in the range of 25:75 to 65:35, more preferably in the range of 25:75 to 60:40, even more preferably in the range of 25:75 to 50:50. .
（１－１－３）酸無水物モノマー
　酸無水物モノマーとしては、例えば、ピロメリット酸二無水物、３，３’，４，４’－ビフェニルテトラカルボン酸二無水物、２，２’ジメチル－３，３’，４，４’－ビフェニルテトラカルボン酸二無水物、５，５’ジメチル－３，３’，４，４’－ビフェニルテトラカルボン酸二無水物、２，３，３’，４’－ビフェニルテトラカルボン酸二無水物、２，２’，３，３’－ビフェニルテトラカルボン酸二無水物、３，３’，４，４’－ジフェニルエーテルテトラカルボン酸二無水物、２，３，３’，４’－ジフェニルエーテルテトラカルボン酸二無水物、２，２’，３，３’－ジフェニルエーテルテトラカルボン酸二無水物、３，３’，４，４’－ベンゾフェノンテトラカルボン酸二無水物、２，２’，３，３’－ベンゾフェノンテトラカルボン酸二無水物、２，３，３’，４’－ベンゾフェノンテトラカルボン酸二無水物、３，３’，４，４’－ジフェニルスルホンテトラカルボン酸二無水物、２，３，３’，４’－ジフェニルスルホンテトラカルボン酸二無水物、３，３’，４，４’－ジフェニルスルホキシドテトラカルボン酸二無水物、３，３’，４，４’－ジフェニルスルフィドテトラカルボン酸二無水物、３，３’，４，４’－ジフェニルメチレンテトラカルボン酸二無水物、４，４’－イソプロピリデンジフタル酸無水物、４，４’－（ヘキサフルオロイソプロピリデン）ジフタル酸無水物、３，４，９，１０－ペリレンテトラカルボン酸二無水物、２，３，６，７－ナフタレンテトラカルボン酸二無水物、１，４，５，８－ナフタレンテトラカルボン酸二無水物、１，２，５，６－ナフタレンテトラカルボン酸二無水物、２，３，６，７－アントラセンテトラカルボン酸二無水物、１，２，３，４－シクロブタンテトラカルボン酸二無水物、１，２，３，４－シクロペンタンテトラカルボン酸二無水物、１，２，３，５－シクロペンタンテトラカルボン酸二無水物、１，２，４，５－ビシクロヘキセンテトラカルボン酸二無水物、１，２，４，５－シクロヘキサンテトラカルボン酸二無水物等が挙げられる。中でも、芳香族ポリマーの溶解性や力学物性等の観点から、３，３’，４，４’－ジフェニルエーテルテトラカルボン酸二無水物を用いることが好ましい。 (1-1-3) Acid anhydride monomer Examples of acid anhydride monomers include pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2' dimethyl -3,3',4,4'-biphenyltetracarboxylic dianhydride, 5,5'dimethyl-3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3', 4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl ethertetracarboxylic dianhydride, 2,3 , 3',4'-diphenyl ether tetracarboxylic dianhydride, 2,2',3,3'-diphenyl ether tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride , 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 2,3,3',4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfone tetra Carboxylic dianhydride, 2,3,3',4'-diphenylsulfonetetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfoxide tetracarboxylic dianhydride, 3,3',4 , 4'-diphenylsulfidetetracarboxylic dianhydride, 3,3',4,4'-diphenylmethylenetetracarboxylic dianhydride, 4,4'-isopropylidene diphthalic anhydride, 4,4'- (Hexafluoroisopropylidene) diphthalic anhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8 -Naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,3,4-cyclobutane Tetracarboxylic dianhydride, 1,2,3,4-cyclopentane tetracarboxylic dianhydride, 1,2,3,5-cyclopentane tetracarboxylic dianhydride, 1,2,4,5-bi Examples include cyclohexenetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, and the like. Among them, it is preferable to use 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride from the viewpoint of solubility and mechanical properties of the aromatic polymer.
　フッ素系芳香族モノマー及び非フッ素系芳香族モノマーの合計と、酸無水物モノマーとのモル比は、８０：１００～１００：８０であることが好ましい。フッ素系芳香族モノマー及び非フッ素系芳香族モノマーの合計と、酸無水物モノマーとを等モル程度にすることで、分子量の高い芳香族ポリマーが得られる。一方、上記モル比を一方に偏らせることで、分子量の低い芳香族ポリマーが得られる。 The molar ratio of the total of the fluorinated aromatic monomer and non-fluorinated aromatic monomer to the acid anhydride monomer is preferably 80:100 to 100:80. By setting the sum of the fluorine-based aromatic monomer and the non-fluorine-based aromatic monomer and the acid anhydride monomer to approximately equimolar amounts, an aromatic polymer with a high molecular weight can be obtained. On the other hand, by biasing the molar ratio to one side, an aromatic polymer with a low molecular weight can be obtained.
　上記芳香族ポリマーに用いられる、フッ素系芳香族モノマー、非フッ素系芳香族モノマー及び酸無水物モノマーとしては、２－ビス（４－アミノフェニル）ヘキサフルオロプロパン又は４，４’－ジヒドロキシ－３，３’－ジアミノフェニルヘキサフルオロプロパン、４，４’－ジアミノジフェニルエーテル、及び、３，３’，４，４’－ジフェニルエーテルテトラカルボン酸二無水物の組み合わせが好ましい。 The fluorinated aromatic monomer, non-fluorinated aromatic monomer, and acid anhydride monomer used in the aromatic polymer include 2-bis(4-aminophenyl)hexafluoropropane or 4,4'-dihydroxy-3, A combination of 3'-diaminophenylhexafluoropropane, 4,4'-diaminodiphenyl ether, and 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride is preferred.
（１－１－４）芳香族ポリマー
　芳香族ポリマーは、少なくとも、フッ素原子を含有する芳香族ジアミンモノマー及びフッ素原子を含有する芳香族ジイソシアネートモノマーからなる群から選択される少なくとも１つのフッ素系芳香族モノマーと、フッ素原子を含有しない芳香族ジアミンモノマー及びフッ素原子を含有しない芳香族ジイソシアネートモノマーからなる群から選択される少なくとも１つの非フッ素系芳香族モノマーと、酸無水物モノマーと、を共重合させてなる。
　上記芳香族ポリマーとしては、例えば、芳香族ポリアミック酸、芳香族ポリアミドイミド、芳香族ポリイミド、芳香族ポリエーテルイミド、芳香族ポリマレイミド等が挙げられる。芳香族ポリマーは、汎用性の観点から、芳香族ポリイミドが好ましい。 (1-1-4) Aromatic polymer The aromatic polymer is at least one fluorinated aromatic polymer selected from the group consisting of an aromatic diamine monomer containing a fluorine atom and an aromatic diisocyanate monomer containing a fluorine atom. A monomer, at least one non-fluorine-based aromatic monomer selected from the group consisting of an aromatic diamine monomer that does not contain a fluorine atom and an aromatic diisocyanate monomer that does not contain a fluorine atom, and an acid anhydride monomer are copolymerized. It becomes.
Examples of the aromatic polymer include aromatic polyamic acid, aromatic polyamideimide, aromatic polyimide, aromatic polyetherimide, aromatic polymaleimide, and the like. The aromatic polymer is preferably an aromatic polyimide from the viewpoint of versatility.
　上記芳香族ポリマーは、上記成分以外に本発明の効果を損なわない範囲において他の成分を含有してもよい。その他の成分としてはポリアミド、ポリアミン等が挙げられる。 The above-mentioned aromatic polymer may contain other components in addition to the above-mentioned components within a range that does not impair the effects of the present invention. Other components include polyamide, polyamine, and the like.
　芳香族ポリマーは、上記した特徴を満たす芳香族ポリマーが得られればその製法は特に限定されないが、例えば、後述する製造方法により製造できる。 The manufacturing method of the aromatic polymer is not particularly limited as long as an aromatic polymer satisfying the above characteristics can be obtained, but for example, it can be manufactured by the manufacturing method described below.
　芳香族ポリマーの重量平均分子量（以下、「Ｍｗ」）は、分離性能、機械的強度及び製膜性を両立する観点から、５，０００～３００，０００であることが好ましい。上記芳香族ポリマーが芳香族ポリイミドである場合、芳香族ポリイミドのＭｗは、８，０００～２００，０００であることが好ましく、１２，０００～１００，０００であることがより好ましい。芳香族ポリイミドのＭｗが８，０００以上であることで、多孔質膜及び複合膜として好ましい分離性能、機械的強度を得ることができる。一方、芳香族ポリイミドのＭｗが２００，０００以下であることで、ポリマー溶液の粘度が適切な範囲となり、良好な製膜性を実現することができる。
　芳香族ポリマーの重量平均分子量は、ゲル浸透クロマトグラフィーによって測定でき、標準物質として使用するポリスチレンの分子量に換算した値である。 The weight average molecular weight (hereinafter referred to as "Mw") of the aromatic polymer is preferably 5,000 to 300,000 from the viewpoint of achieving separation performance, mechanical strength, and film formability. When the aromatic polymer is an aromatic polyimide, the Mw of the aromatic polyimide is preferably 8,000 to 200,000, more preferably 12,000 to 100,000. When the Mw of the aromatic polyimide is 8,000 or more, separation performance and mechanical strength preferable for porous membranes and composite membranes can be obtained. On the other hand, when the Mw of the aromatic polyimide is 200,000 or less, the viscosity of the polymer solution falls within an appropriate range, and good film formability can be achieved.
The weight average molecular weight of the aromatic polymer can be measured by gel permeation chromatography, and is a value converted to the molecular weight of polystyrene used as a standard substance.
（１－１－５）架橋ポリマー
　架橋ポリマーは、上記芳香族ポリマー同士が架橋されたポリマーである。架橋ポリマーは、エポキシ系架橋剤、メチロール系架橋剤、アルコキシメチル系架橋剤、及びジアミン系架橋剤からなる群から選択される少なくとも１つの架橋剤により、上記芳香族ポリマー同士が架橋されたポリマーであることが好ましい。 (1-1-5) Crosslinked Polymer The crosslinked polymer is a polymer in which the above-mentioned aromatic polymers are crosslinked with each other. The crosslinked polymer is a polymer in which the aromatic polymers described above are crosslinked with at least one crosslinking agent selected from the group consisting of an epoxy crosslinking agent, a methylol crosslinking agent, an alkoxymethyl crosslinking agent, and a diamine crosslinking agent. It is preferable that there be.
　上記芳香族ポリマーが芳香族ポリイミドである場合、架橋ポリマーのイミド化度は０．２～１．２であることが好ましく、０．３～１．２であることがより好ましく、０．４～１．２であることがさらに好ましい。架橋ポリマーのイミド化度が０．２以上であることで、有機溶媒を含有する被処理液、及び高温の被処理液に対して、継続的に安定して分離性能と透過性能とを維持可能な、多孔質膜を得ることができる。 When the aromatic polymer is an aromatic polyimide, the degree of imidization of the crosslinked polymer is preferably from 0.2 to 1.2, more preferably from 0.3 to 1.2, and more preferably from 0.4 to 1.2. More preferably, it is 1.2. By setting the degree of imidization of the crosslinked polymer to 0.2 or more, it is possible to continuously and stably maintain separation performance and permeation performance for processed liquids containing organic solvents and high-temperature processed liquids. A porous membrane can be obtained.
　架橋ポリマーのイミド化度はフーリエ変換赤外分光光度計を用いて測定することができる。イミド化度は、赤外全反射吸収測定法（ＡＴＲ法）にて、多孔質膜表面を測定して得た、芳香環由来のピーク強度Ａ及びイミド基由来のピーク強度Ｂから、下記式１により算出する値である。
　イミド化度＝Ｂ／Ａ　　　・・・（式１） The degree of imidization of the crosslinked polymer can be measured using a Fourier transform infrared spectrophotometer. The degree of imidization is determined by the following formula 1 from the peak intensity A derived from the aromatic ring and the peak intensity B derived from the imide group obtained by measuring the porous membrane surface by infrared total reflection absorption measurement method (ATR method). This is the value calculated by
Imidization degree = B/A (Formula 1)
　架橋ポリマーのイミド化度は、ポリアミック酸合成後の加熱脱水反応の進行度により調整できる。イミド化を促進する方法としては、例えば、イミド化反応の副生成物である水を留去する方法、ポリアミック酸溶液中に無水酢酸、イソキノリン、イミダゾール、ピリジン等の添加剤を加えた後、加熱する方法が挙げられる。一方でイミド化を抑制する方法としては、ポリアミック酸に水を加える等の方法がある。 The degree of imidization of the crosslinked polymer can be adjusted by the degree of progress of the heating dehydration reaction after polyamic acid synthesis. Examples of methods for promoting imidization include distilling off water, which is a byproduct of the imidization reaction, and adding additives such as acetic anhydride, isoquinoline, imidazole, and pyridine to a polyamic acid solution, followed by heating. One method is to do so. On the other hand, as a method for suppressing imidization, there is a method such as adding water to polyamic acid.
（１－１－６）多孔質膜
　多孔質膜は、架橋ポリマーを含有する。上記芳香族ポリマーは有機溶媒に溶解するが、上記芳香族ポリマー同士を架橋することで耐有機溶媒性を有するポリマーが得られる。これにより、ポリマー溶液を用いた多孔質膜の製膜を実現しつつ、その後架橋することで、有機溶媒を含有する被処理液に対して、継続的に安定して分離性能と透過性能とを維持可能な、多孔質膜を得ることができる。 (1-1-6) Porous membrane The porous membrane contains a crosslinked polymer. Although the above aromatic polymer is soluble in an organic solvent, a polymer having organic solvent resistance can be obtained by crosslinking the above aromatic polymers. This makes it possible to fabricate a porous membrane using a polymer solution, and by crosslinking it afterwards, it consistently and stably maintains separation and permeation performance for treated liquids containing organic solvents. A maintainable porous membrane can be obtained.
　多孔質膜は、三次元網目構造を有することが好ましい。ここで「三次元網目構造」とは、多孔質膜を構成する筋状のポリマーが、三次元的に、網目状に広がった構造をいう。三次元網目構造は、網目を形成する筋状の固形物に仕切られた細孔を有し、分離性能に優れる。 It is preferable that the porous membrane has a three-dimensional network structure. The term "three-dimensional network structure" as used herein refers to a structure in which the linear polymers constituting the porous membrane are three-dimensionally spread out in a network shape. The three-dimensional network structure has pores partitioned by solid stripes forming the network, and has excellent separation performance.
　多孔質膜は、少なくとも緻密層と粗大層の２層を有することが好ましく、厚み方向に少なくとも緻密層と粗大層の２層を有することがさらに好ましい。ここで「緻密層」とは、平均孔径５０ｎｍ未満の層をいい、「粗大層」とは、平均孔径５０ｎｍ以上の層をいう。厚み方向に少なくとも緻密層と粗大層の２層を有することで、分離性能と透過性能とが両立した多孔質膜を得ることができる。また、多孔質膜は、孔径が厚み方向で傾斜的に変化する非対称構造であることがより好ましい。 The porous membrane preferably has at least two layers, a dense layer and a coarse layer, and more preferably at least two layers, a dense layer and a coarse layer, in the thickness direction. Here, the term "dense layer" refers to a layer with an average pore size of less than 50 nm, and the term "coarse layer" refers to a layer with an average pore size of 50 nm or more. By having at least two layers, a dense layer and a coarse layer, in the thickness direction, a porous membrane having both separation performance and permeation performance can be obtained. Moreover, it is more preferable that the porous membrane has an asymmetric structure in which the pore diameter changes gradiently in the thickness direction.
　多孔質膜は、用途に応じて適宜平均表面孔径を選択することができる。有機溶媒を含んだ排水の濃縮や、混合有機溶媒の分離回収等、有機溶媒を分離対象とする場合、多孔質膜の平均表面孔径は、０．２５～０．８ｎｍであることが好ましく、０．４～０．７ｎｍであることがより好ましい。有機溶媒中からの有価物回収等、例えば、分子量２００～１０００程度の分子を分離対象とする場合、多孔質膜の平均表面孔径は、０．７～４ｎｍであることが好ましく、０．７５～２ｎｍであることがより好ましい。有機溶媒中の高分子成分の除去等、例えば分子量１０００以上の分子を分離対象とする場合、多孔質膜の平均表面孔径は、２～１００ｎｍであることが好ましく、４～５０ｎｍであることがより好ましい。一般に、分離性能と透過性能とは平均表面孔径に応じてトレードオフの関係にある。そのため、分離性能と透過性能とを高いレベルで両立させるべく、分離対象に適した平均表面孔径を選択することが好ましい。 The average surface pore diameter of the porous membrane can be appropriately selected depending on the application. When organic solvents are to be separated, such as concentrating wastewater containing organic solvents or separating and recovering mixed organic solvents, the average surface pore diameter of the porous membrane is preferably 0.25 to 0.8 nm, and More preferably, the thickness is from .4 to 0.7 nm. For example, when separating molecules with a molecular weight of about 200 to 1000, such as recovering valuables from an organic solvent, the average surface pore diameter of the porous membrane is preferably 0.7 to 4 nm, and preferably 0.75 to 4 nm. More preferably, the thickness is 2 nm. When separating molecules with a molecular weight of 1000 or more, such as removing a polymer component in an organic solvent, the average surface pore diameter of the porous membrane is preferably 2 to 100 nm, more preferably 4 to 50 nm. preferable. Generally, there is a trade-off relationship between separation performance and permeation performance depending on the average surface pore diameter. Therefore, in order to achieve both separation performance and permeation performance at a high level, it is preferable to select an average surface pore diameter suitable for the separation target.
　多孔質膜の厚みは、２０～３００μｍであることが好ましく、３０～２５０μｍであることがより好ましく、４０～２００μｍであることがさらに好ましい。多孔質膜の厚みが２０μｍ以上であることで、良好な分離性能を有する多孔質膜を得ることができる。一方、多孔質膜の厚みが３００μｍ以下であることで、良好な透過性能を有する多孔質膜を得ることができる。なお、多孔質膜の厚みは、断面観察で厚み方向に直交する方向（膜の面方向）に２０μｍ間隔で測定した、２０点の厚みの平均値を算出することで求めることができる。 The thickness of the porous membrane is preferably 20 to 300 μm, more preferably 30 to 250 μm, and even more preferably 40 to 200 μm. When the thickness of the porous membrane is 20 μm or more, a porous membrane having good separation performance can be obtained. On the other hand, when the thickness of the porous membrane is 300 μm or less, a porous membrane having good permeability can be obtained. The thickness of the porous membrane can be determined by calculating the average value of the thickness at 20 points measured at 20 μm intervals in a direction perpendicular to the thickness direction (in the plane direction of the membrane) during cross-sectional observation.
　多孔質膜の空隙率は、２５～８５％であることが好ましく、３０～７５％であることがより好ましい。空隙率とは、物質の全体積に占める空間の体積の割合で定義される。多孔質膜の空隙率が２５％以上であることで、良好な透過性能を有する多孔質膜を得ることができる。一方、多孔質膜の空隙率が８５％以下であることで、十分な機械的強度を有する多孔質膜を得ることができる。 The porosity of the porous membrane is preferably 25 to 85%, more preferably 30 to 75%. Porosity is defined as the ratio of the volume of space to the total volume of a material. When the porosity of the porous membrane is 25% or more, a porous membrane having good permeability can be obtained. On the other hand, when the porosity of the porous membrane is 85% or less, a porous membrane having sufficient mechanical strength can be obtained.
　多孔質膜の空隙率（％）の測定方法は、例えば、多孔質膜の膜厚を測定して算出した膜体積（ｃｍ３）と質量（ｇ）から、下記式２を用いて算出することができる。なお、空隙率算出のための密度は、芳香族ポリマーの種類に応じて設定しうる。例えば、芳香族ポリマーが芳香族ポリイミドである場合、密度は１．４２ｇ／ｃｍ３としてもよい。
　空隙率（％）＝｛１－質量／（密度×膜体積）｝×１００　　　・・・（式２） The method for measuring the porosity (%) of a porous membrane is, for example, to calculate it using the following formula 2 from the membrane volume (cm 3 ) and mass (g) calculated by measuring the membrane thickness of the porous membrane. Can be done. Note that the density for calculating the porosity can be set depending on the type of aromatic polymer. For example, if the aromatic polymer is an aromatic polyimide, the density may be 1.42 g/cm 3 .
Porosity (%) = {1-mass/(density x membrane volume)} x 100 (Formula 2)
　本実施形態の多孔質膜は、断面にマクロボイドを有することが好ましい。また、多孔質膜の断面に占めるマクロボイドの面積割合は３～６０％であることが好ましく、５～５５％であることがさらに好ましく、１０～５０％であることがさらに好ましい。多孔質膜の断面に占めるマクロボイドの面積割合が３％以上である場合、マクロボイド内は液体や気体が容易に流入するため、膜は高透過となる。一方で、多孔質膜の断面に占めるマクロボイドの面積割合が６０％以下である場合、膜は圧力に対して十分な機械特性を示すため、取り扱いが容易となる。 The porous membrane of this embodiment preferably has macrovoids in its cross section. Further, the area ratio of macrovoids to the cross section of the porous membrane is preferably 3 to 60%, more preferably 5 to 55%, and even more preferably 10 to 50%. When the area ratio of macrovoids to the cross section of the porous membrane is 3% or more, liquid and gas easily flow into the macrovoids, resulting in high permeability of the membrane. On the other hand, when the area ratio of macrovoids to the cross section of the porous membrane is 60% or less, the membrane exhibits sufficient mechanical properties against pressure and is therefore easy to handle.
　ここで、「マクロボイド」とは、０．５μｍ以上の長さを有する孔をいう。マクロボイドの典型的な形状としては、例えば、直径０．５μｍ以上の球状構造、０．５μｍ以上の長さを有する涙滴、洋ナシ様又は梨状形状、及びベル様形状等の２つ以上の明確に異なる特徴的な長さを有する構造、又は、０．５μｍ以上の長さを有し、アスペクト比が３以上のフィンガー状構造等が挙げられる。ここで、「アスペクト比」とは、マクロボイドにおいて多孔質膜表面に対して垂直な方向の長さを多孔質膜表面に対して水平な方向の長さで除した値をいう。 Here, "macro void" refers to a hole having a length of 0.5 μm or more. Typical shapes of macrovoids include, for example, a spherical structure with a diameter of 0.5 μm or more, a teardrop with a length of 0.5 μm or more, a pear-like or pear-shaped shape, and two or more bell-like shapes. or a finger-like structure having a length of 0.5 μm or more and an aspect ratio of 3 or more. Here, the "aspect ratio" refers to a value obtained by dividing the length of a macrovoid in a direction perpendicular to the porous membrane surface by the length of the macrovoid in a direction horizontal to the porous membrane surface.
　マクロボイドのアスペクト比は２．０以上であることが好ましく、２．５以上であることが好ましく、３．０以上であることがさらに好ましい。マクロボイドのアスペクト比が３．０以上であることで膜は圧力に対して十分な機械特性を示し、且つ、高透過な膜となる。
　一方で、アスペクト比は６．０以下であることが好ましい。アスペクト比が６．０以下であることで、引張方向に対しても十分な機械特性を示す。すなわち、マクロボイドが膜の厚み方向に長軸を有することが好ましい。 The aspect ratio of the macrovoid is preferably 2.0 or more, preferably 2.5 or more, and more preferably 3.0 or more. When the aspect ratio of the macrovoids is 3.0 or more, the membrane exhibits sufficient mechanical properties against pressure and becomes a highly permeable membrane.
On the other hand, the aspect ratio is preferably 6.0 or less. When the aspect ratio is 6.0 or less, sufficient mechanical properties are exhibited even in the tensile direction. That is, it is preferable that the macrovoids have their long axes in the thickness direction of the film.
　また、上記断面とは、多孔質膜表面に対して垂直な方向に切断した断面をいう。 Furthermore, the above-mentioned cross section refers to a cross section cut in a direction perpendicular to the surface of the porous membrane.
　多孔質膜の断面に占めるマクロボイドの面積割合及びアスペクト比を適切に制御する方法として、例えば、製膜溶液に添加物を加える方法が挙げられる。具体的な例として多孔質膜がポリイミド膜である場合、ポリイミドが可溶な有機溶剤とポリイミド溶液に対して凝固浴の浸入を促進させる有機溶剤を混合して用いることで、ポリイミド膜中にマクロボイドを形成することができる。ポリイミドが可溶な有機溶剤としては、例えば、アセトン、アセトニトリル、ジメチルスルホキシド、ジメチルアセトアミド、ジメチルホルムアミド、Ｎ―メチルピロリドン、ジクロロメタン、クロロホルム等が挙げられる。ポリイミド溶液に対して凝固浴の浸入を促進させる有機溶剤としては、例えば、１，４－ジオキサン、テトラヒドロフラン、１，３－ジオキソラン、ジメチルエーテル、ジエチルエーテル等のエーテル系溶媒が主に挙げられる。 An example of a method for appropriately controlling the area ratio and aspect ratio of macrovoids in the cross section of a porous membrane is a method of adding additives to the membrane forming solution. As a specific example, when the porous membrane is a polyimide membrane, by using a mixture of an organic solvent in which polyimide is soluble and an organic solvent that promotes penetration of the coagulation bath into the polyimide solution, macroscopic particles can be added to the polyimide membrane. Voids can be formed. Examples of organic solvents in which polyimide is soluble include acetone, acetonitrile, dimethyl sulfoxide, dimethylacetamide, dimethylformamide, N-methylpyrrolidone, dichloromethane, and chloroform. Examples of organic solvents that promote penetration of the coagulation bath into the polyimide solution include ether solvents such as 1,4-dioxane, tetrahydrofuran, 1,3-dioxolane, dimethyl ether, and diethyl ether.
　本実施形態の多孔質膜における膨潤度は１００～２００％であることが好ましく、１０５～１５０％がより好ましく、１１０～１３０％がさらに好ましい。多孔質膜の膨潤度を１００～２００％の範囲とすることで、多孔質膜は溶媒に対して適度な親和性を有し、高除去性や高透過性を示す。
　「膨潤度」とは、Ｎ－メチル－２－ピロリドン（以下、「ＮＭＰ」）に浸漬する前の多孔質膜の厚みに対する、ＮＭＰに浸漬し平衡膨潤状態に達した後の多孔質膜の厚みの比率を意味する。 The degree of swelling in the porous membrane of this embodiment is preferably 100 to 200%, more preferably 105 to 150%, and even more preferably 110 to 130%. By setting the degree of swelling of the porous membrane in the range of 100 to 200%, the porous membrane has an appropriate affinity for the solvent and exhibits high removability and high permeability.
"Degree of swelling" refers to the thickness of the porous membrane after immersion in NMP and reaching an equilibrium swelling state, compared to the thickness of the porous membrane before immersion in N-methyl-2-pyrrolidone (hereinafter referred to as ``NMP''). means the ratio of
　（１－２）複合膜
　本実施形態の多孔質膜は、上記多孔質膜のみで構成されていてもよいが、多孔質膜が基材の少なくとも一方の面側に積層された複合膜を形成していてもよい。基材は、多孔質膜を支持することで複合膜全体に強度を付与するためのものであり、それ自体は実質的に分離性能を有しない。
　多孔質膜が基材の少なくとも一方の面側に積層された複合膜は、基材の少なくとも一方の面側に多孔質膜が存在していればよく、多孔質膜が基材上に直接積層されていてもよく、多孔質膜と基材の間に実質的に分離性能を有しない任意の層を設けて積層されていてもよい。 (1-2) Composite membrane The porous membrane of this embodiment may be composed only of the above-mentioned porous membrane, but the porous membrane forms a composite membrane in which the porous membrane is laminated on at least one side of the base material. You may do so. The base material supports the porous membrane to provide strength to the entire composite membrane, and itself does not have substantial separation performance.
A composite membrane in which a porous membrane is laminated on at least one side of a base material only needs to have a porous membrane on at least one side of the base material, and the porous membrane is laminated directly on the base material. Alternatively, an arbitrary layer having substantially no separation performance may be provided between the porous membrane and the base material and laminated.
　基材としては、例えば、ポリエステル系重合体、ポリアミド系重合体、ポリオレフィン系重合体、ポリスルファィド系重合体、及びこれらの混合物又は共重合体からなる布帛が挙げられる。有機溶媒を含有する被処理液、及び高温の被処理液に対して安定性に優れることから、ポリスルファィド系重合体の布帛が特に好ましい。ポリスルファィド系重合体としては、例えば、ポリフェニレンスルファイド（以下、「ＰＰＳ」）が挙げられる。布帛としては、長繊維不織布や短繊維不織布、又は織編物が好ましい。ここで、短繊維不織布とは、平均繊維長３００ｍｍ未満、且つ、平均繊維径３～３０μｍの不織布のことを指す。すなわち、基材としては、ポリフェニレンスルファイドを主成分とすることが好ましい。主成分であるとは、例えば、基材全体に対して質量基準で５０～１００％であることが好ましい。 Examples of the base material include fabrics made of polyester polymers, polyamide polymers, polyolefin polymers, polysulfide polymers, and mixtures or copolymers thereof. Fabrics made of polysulfide polymers are particularly preferred because they have excellent stability against liquids to be treated containing organic solvents and liquids to be treated at high temperatures. Examples of polysulfide-based polymers include polyphenylene sulfide (hereinafter referred to as "PPS"). The fabric is preferably a long fiber nonwoven fabric, a short fiber nonwoven fabric, or a woven or knitted fabric. Here, the short fiber nonwoven fabric refers to a nonwoven fabric with an average fiber length of less than 300 mm and an average fiber diameter of 3 to 30 μm. That is, the base material preferably contains polyphenylene sulfide as a main component. The term "main component" preferably means, for example, 50 to 100% by mass of the entire base material.
　基材の厚みは、複合膜の強度及びそれをエレメントにしたときの充填密度に影響を与える。良好な機械的強度及び充填密度を得るため、基材の厚みは、３０～２５０μｍであることが好ましく、５０～１８０μｍであることがより好ましい。なお、基材の厚みは、上記多孔質膜の厚みと同様にして求めることができる。 The thickness of the base material affects the strength of the composite membrane and the packing density when it is made into an element. In order to obtain good mechanical strength and packing density, the thickness of the base material is preferably 30 to 250 μm, more preferably 50 to 180 μm. Note that the thickness of the base material can be determined in the same manner as the thickness of the porous membrane.
　基材の通気度は、複合膜の分離性能や、物理的安定性に影響を与える。基材の通気度は、０．２～４ｃｍ３／ｃｍ２／ｓであることが好ましく、０．２５～３ｃｍ３／ｃｍ２／ｓであることがより好ましく、０．３～１ｃｍ３／ｃｍ２／ｓであることがさらに好ましい。基材の通気度が０．２ｃｍ３／ｃｍ２／ｓ以上であることで、ポリマー溶液の一部が基材に含浸するため、多孔質膜と基材との接着性が向上し、良好な物理的安定性を有する複合膜を得ることができる。一方、基材の通気度が４ｃｍ３／ｃｍ２／ｓ以下であることで、多孔質膜の原料であるポリマー溶液を基材に塗布する際、裏抜けによる欠点が発生しにくくなるため、良好な分離性能を有する複合膜を得ることができる。 The air permeability of the base material affects the separation performance and physical stability of the composite membrane. The air permeability of the base material is preferably 0.2 to 4 cm 3 /cm 2 /s, more preferably 0.25 to 3 cm 3 /cm 2 /s, and 0.3 to 1 cm 3 /cm. More preferably, it is 2 /s. When the air permeability of the base material is 0.2 cm 3 /cm 2 /s or more, a portion of the polymer solution impregnates the base material, improving the adhesion between the porous membrane and the base material and providing a good result. Composite membranes with physical stability can be obtained. On the other hand, if the air permeability of the base material is 4 cm 3 /cm 2 /s or less, defects due to bleed through will be less likely to occur when applying the polymer solution, which is the raw material for the porous membrane, to the base material, making it a good material. A composite membrane with excellent separation performance can be obtained.
　分離対象物質が複合膜内部に浸透することを防ぐため、多孔質膜は、複合膜の表面側に配置されていることが好ましく、且つ、ろ過一次側に配置されていることがより好ましい。 In order to prevent the substance to be separated from permeating inside the composite membrane, the porous membrane is preferably placed on the surface side of the composite membrane, and more preferably placed on the primary filtration side.
　多孔質膜又は複合膜の膜透過流束は、工業的価値の観点から、多孔質膜又は複合膜がＯＳＲＯ（分画分子量２００未満）である場合、０．１Ｌ／ｍ２／ｈ／ｂａｒ以上であることが好ましく、多孔質膜又は複合膜がＯＳＮ（分画分子量２００～１，０００）である場合、０．５Ｌ／ｍ２／ｈ／ｂａｒ以上であることが好ましく、多孔質膜又は複合膜がＯＳＵ（分画分子量１，０００以上）である場合、２．０Ｌ／ｍ２／ｈ／ｂａｒ以上であることが好ましい。 From the viewpoint of industrial value, the membrane permeation flux of the porous membrane or composite membrane is 0.1 L/m 2 /h/bar or more if the porous membrane or composite membrane is OSRO (molecular weight cut off less than 200). When the porous membrane or composite membrane is OSN (molecular weight cut off 200 to 1,000), it is preferably 0.5 L/m 2 /h/bar or more, and the porous membrane or composite membrane When the membrane is OSU (molecular weight cut off 1,000 or more), it is preferably 2.0 L/m 2 /h/bar or more.
　膜透過流束は、クロスフロー膜ろ過試験によって算出することができる。例えば、透過液量（Ｌ）、単位膜面積（ｍ２）、単位時間（ｈ）及び操作圧力（ｂａｒ）から、下記式３を用いて多孔質膜又は複合膜の膜透過流束（Ｌ／ｍ２／ｈ／ｂａｒ）を算出することができる。
　膜透過流束＝透過液量／（単位膜面積×単位時間）／操作圧力　　　・・・（式３） Membrane permeation flux can be calculated by a cross-flow membrane filtration test. For example, from the amount of permeated liquid (L), unit membrane area (m 2 ), unit time (h), and operating pressure (bar), the membrane permeation flux (L/ m 2 /h/bar) can be calculated.
Membrane permeation flux = permeate volume / (unit membrane area x unit time) / operating pressure ... (Formula 3)
　多孔質膜又は複合膜の阻止率は、工業的価値の観点から、８０％以上であることが好ましい。 The rejection rate of the porous membrane or composite membrane is preferably 80% or more from the viewpoint of industrial value.
　阻止率（％）は、供給液（原液）中の溶質濃度Ｃ（ｐｐｍ）及び透過液中の溶質濃度Ｄ（ｐｐｍ）から、下記式４を用いて算出することができる。
　阻止率（％）＝（１－Ｄ／Ｃ）×１００　　　・・・（式４） The rejection rate (%) can be calculated from the solute concentration C (ppm) in the feed solution (undiluted solution) and the solute concentration D (ppm) in the permeate using the following formula 4.
Rejection rate (%) = (1-D/C) x 100 (Formula 4)
　２．多孔質膜及び複合膜の製造方法
　本実施形態の多孔質膜及び複合膜の製造方法は、上述した所望の特徴を満たす多孔質膜及び複合膜が得られれば特に限定されないが、例えば、以下の方法で製造することができる。 2. Method for producing porous membrane and composite membrane The method for producing porous membrane and composite membrane of this embodiment is not particularly limited as long as porous membrane and composite membrane satisfying the above-mentioned desired characteristics can be obtained. It can be manufactured by the method.
　本実施形態の多孔質膜及び複合膜は、例えば下記（ｉ）及び（ｉｉ）の工程を含む方法によって製造することができる。
（ｉ）少なくとも、フッ素原子を含有する芳香族ジアミンモノマー及びフッ素原子を含有する芳香族ジイソシアネートモノマーからなる群から選択される少なくとも１つのフッ素系芳香族モノマーと、フッ素原子を含有しない芳香族ジアミンモノマー及びフッ素原子を含有しない芳香族ジイソシアネートモノマーからなる群から選択される少なくとも１つの非フッ素系芳香族モノマーと、酸無水物モノマーと、を共重合して芳香族ポリマーを得ること。
（ｉｉ）架橋剤によって上記（ｉ）で得られた芳香族ポリマーを架橋すること。 The porous membrane and composite membrane of this embodiment can be manufactured, for example, by a method including the following steps (i) and (ii).
(i) At least one fluorine-based aromatic monomer selected from the group consisting of an aromatic diamine monomer containing a fluorine atom and an aromatic diisocyanate monomer containing a fluorine atom, and an aromatic diamine monomer containing no fluorine atom. and at least one non-fluorine-based aromatic monomer selected from the group consisting of aromatic diisocyanate monomers containing no fluorine atoms, and an acid anhydride monomer to obtain an aromatic polymer.
(ii) Crosslinking the aromatic polymer obtained in (i) above with a crosslinking agent.
　（２－１）ポリマーの重合
　まず、芳香族ポリマーを作製する。モノマーとしては、少なくとも、上記フッ素原子を含有する芳香族ジアミンモノマー及びフッ素原子を含有する芳香族ジイソシアネートモノマーからなる群から選択される少なくとも１つのフッ素系芳香族モノマーと、上記フッ素原子を含有しない芳香族ジアミンモノマー及びフッ素原子を含有しない芳香族ジイソシアネートモノマーからなる群から選択される少なくとも１つの非フッ素系芳香族モノマーと、上記酸無水物モノマーとを用いる。 (2-1) Polymerization of polymer First, an aromatic polymer is produced. The monomers include at least one fluorine-based aromatic monomer selected from the group consisting of the above-mentioned fluorine atom-containing aromatic diamine monomers and fluorine atom-containing aromatic diisocyanate monomers, and the above-mentioned fluorine-containing aromatic monomers. The acid anhydride monomer and at least one non-fluorine aromatic monomer selected from the group consisting of diamine monomers and aromatic diisocyanate monomers containing no fluorine atoms are used.
　フッ素系芳香族モノマー及び非フッ素系芳香族モノマーの合計と、酸無水物モノマーとのモル比は、８０：１００～１００：８０であることが好ましい。フッ素系芳香族モノマー及び非フッ素系芳香族モノマーの合計と、酸無水物モノマーとを等モル程度にすることで、上記芳香族ポリマーの分子量を増加させることができる。一方、上記モル比を一方に偏らせることで、ポリマーの分子量を低減させることができる。 The molar ratio of the total of the fluorinated aromatic monomer and non-fluorinated aromatic monomer to the acid anhydride monomer is preferably 80:100 to 100:80. The molecular weight of the aromatic polymer can be increased by making the total of the fluorinated aromatic monomer and the non-fluorinated aromatic monomer and the acid anhydride monomer about equimolar. On the other hand, by biasing the molar ratio to one side, the molecular weight of the polymer can be reduced.
　また、上記芳香族ポリマーの分子量及び分子量分布を制御するため、末端封止剤を添加してもよい。末端封止剤としては、例えば、無水フタル酸、２，３－ナフタレンジカルボン酸無水物、１，２－ナフタレンジカルボン酸無水物、４－メチルフタル酸無水物、３－メチルフタル酸無水物、４－クロロフタル酸無水物、４－ｔｅｒｔ－ブチルフタル酸無水物及び４－フルオロフタル酸無水物等の酸無水物、アニリン、１－ナフチルアミン、２－クロロアニリン、４－クロロアニリン、３－アミノフェノール、４－アミノピリジン等のアミン、ｎ－ブチルイソシアネート、イソプロピルイソシアネート、フェニルイソシアネート、ベンジルイソシアネート等のイソシアネート等が挙げられる。 Additionally, a terminal capping agent may be added in order to control the molecular weight and molecular weight distribution of the aromatic polymer. Examples of the terminal capping agent include phthalic anhydride, 2,3-naphthalenedicarboxylic anhydride, 1,2-naphthalenedicarboxylic anhydride, 4-methylphthalic anhydride, 3-methylphthalic anhydride, and 4-chlorophthalic anhydride. Acid anhydrides, acid anhydrides such as 4-tert-butylphthalic anhydride and 4-fluorophthalic anhydride, aniline, 1-naphthylamine, 2-chloroaniline, 4-chloroaniline, 3-aminophenol, 4-amino Examples include amines such as pyridine, and isocyanates such as n-butyl isocyanate, isopropylisocyanate, phenyl isocyanate, and benzyl isocyanate.
　上記芳香族ポリマーが芳香族ポリイミドである場合、芳香族ポリイミドのＭｗは、８，０００～２００，０００であることが好ましく、１２，０００～１００，０００であることがより好ましい。芳香族ポリイミドのＭｗが８，０００以上であることで、多孔質膜及び複合膜として好ましい分離性能、機械的強度を得ることができる。一方、芳香族ポリイミドのＭｗが２００，０００以下であることで、ポリマー溶液の粘度が適切な範囲となり、良好な製膜性を実現することができる。 When the aromatic polymer is an aromatic polyimide, the Mw of the aromatic polyimide is preferably 8,000 to 200,000, more preferably 12,000 to 100,000. When the Mw of the aromatic polyimide is 8,000 or more, separation performance and mechanical strength preferable for porous membranes and composite membranes can be obtained. On the other hand, when the Mw of the aromatic polyimide is 200,000 or less, the viscosity of the polymer solution falls within an appropriate range, and good film formability can be achieved.
　ポリマーの重量平均分子量は、ゲル浸透クロマトグラフィーを用いて測定することができ、標準物質として使用するポリスチレンの分子量に換算した値である。 The weight average molecular weight of the polymer can be measured using gel permeation chromatography, and is a value converted to the molecular weight of polystyrene used as a standard substance.
　ポリマーの重合工程について、芳香族ポリイミドを重合する場合を例にとって述べる。まず、フッ素系芳香族モノマーと、非フッ素系芳香族モノマーを溶媒に溶解させ、そこに酸無水物を添加し、０～１００℃で１０分～１００時間攪拌することで、ポリアミック酸溶液を得る。 The polymerization process will be described using the case of polymerizing aromatic polyimide as an example. First, a fluorinated aromatic monomer and a non-fluorinated aromatic monomer are dissolved in a solvent, an acid anhydride is added thereto, and the polyamic acid solution is obtained by stirring at 0 to 100°C for 10 minutes to 100 hours. .
　次に、得られる芳香族ポリイミドが溶媒に可溶である場合は、ポリアミック酸重合後、そのまま温度を１２０～３００℃に上げて１０分～１００時間攪拌することで、イミド化を進行させ、芳香族ポリイミド溶液を得る。この時、トルエン、ｏ－キシレン、ｍ－キシレン、ｐ－キシレン等を反応溶液中に添加し、イミド化反応で発生する水をこれら溶媒と共沸させて除去してもよい。なお、イミド化は後述する「（２－３）多孔質膜又は複合膜の架橋」でも進行させることができるため、本工程により得られる芳香族ポリイミドのイミド化度は、後述する「（２－２）多孔質膜又は複合膜の製膜」に適するよう、重合温度、重合時間、水分率等により適宜調整すればよい。 Next, if the resulting aromatic polyimide is soluble in the solvent, after polyamic acid polymerization, the temperature is raised to 120-300°C and stirred for 10 minutes to 100 hours to advance imidization and create an aromatic Obtain a polyimide solution. At this time, toluene, o-xylene, m-xylene, p-xylene, etc. may be added to the reaction solution, and water generated in the imidization reaction may be removed by azeotroping with these solvents. In addition, since imidization can also proceed in "(2-3) Crosslinking of porous membrane or composite membrane" described later, the degree of imidization of the aromatic polyimide obtained by this step is determined by "(2-3) Crosslinking of porous membrane or composite membrane" described later. 2) Formation of porous membrane or composite membrane", the polymerization temperature, polymerization time, moisture content, etc. may be adjusted as appropriate.
　溶媒としては、例えば、ジメチルスルホキシド、ジメチルホルムアミド、ジメチルアセトアミド、ＮＭＰ、２－ピロリドン、γ－ブチロラクトン（以下、「ＧＢＬ」）、１，４－ジオキサン、１，３－ジメチル－イミダゾリジノン、又は、これらの混合溶媒が挙げられる。 Examples of the solvent include dimethyl sulfoxide, dimethylformamide, dimethylacetamide, NMP, 2-pyrrolidone, γ-butyrolactone (hereinafter referred to as "GBL"), 1,4-dioxane, 1,3-dimethyl-imidazolidinone, or A mixed solvent of these may be mentioned.
　次に、重合したポリマーを精製する。精製方法としては、再沈殿法が好ましい。再沈殿法で用いるポリマーの貧溶媒としては、水が好ましい。再沈殿法により純度を高めたポリマーを乾燥させることで、フッ素系芳香族モノマーと、非フッ素系芳香族モノマーと、酸無水物モノマーと、が共重合した芳香族ポリマーの固体を得ることができる。 Next, the polymerized polymer is purified. As the purification method, a reprecipitation method is preferred. Water is preferred as a poor solvent for the polymer used in the reprecipitation method. By drying the polymer whose purity has been increased by the reprecipitation method, it is possible to obtain a solid aromatic polymer in which a fluorinated aromatic monomer, a non-fluorinated aromatic monomer, and an acid anhydride monomer are copolymerized. .
　（２－２）多孔質膜又は複合膜の製膜
　多孔質膜又は複合膜の製膜方法としては、非溶媒誘起相分離法（ＮＩＰＳ法）や熱誘起相分離法（ＴＩＰＳ法）等を用いることができるが、分離性能と透過性能とを両立できる三次元網目構造且つ非対称構造を有する多孔質膜又は複合膜を得られることから、ＮＩＰＳ法を用いることが好ましい。以下、ＮＩＰＳ法による製膜方法を例にとって述べる。 (2-2) Formation of porous membrane or composite membrane Non-solvent induced phase separation method (NIPS method), thermally induced phase separation method (TIPS method), etc. are used as a method for manufacturing porous membranes or composite membranes. However, it is preferable to use the NIPS method because it can provide a porous membrane or a composite membrane having a three-dimensional network structure and an asymmetric structure that can achieve both separation performance and permeation performance. Hereinafter, a film forming method using the NIPS method will be described as an example.
　まず、「（２－１）ポリマーの重合」で得られたポリマー及び架橋剤を溶媒に溶解させ、ポリマー溶液を得る。溶媒としては、ポリマーの良溶媒が好ましい。ここで「良溶媒」とは、６０℃以下の低温領域でもポリマーを５質量％以上溶解させることができる溶媒をいう。ポリマーの良溶媒としては、例えば、ジメチルスルホキシド、ジメチルホルムアミド、ジメチルアセトアミド、ＮＭＰ、２－ピロリドン、ＧＢＬ、１，４－ジオキサン、１，３－ジメチル－イミダゾリジノン、又は、これらの混合溶媒が挙げられる。 First, the polymer and crosslinking agent obtained in "(2-1) Polymerization of polymer" are dissolved in a solvent to obtain a polymer solution. As the solvent, a good solvent for the polymer is preferred. Here, the term "good solvent" refers to a solvent that can dissolve 5% by mass or more of a polymer even in a low temperature range of 60° C. or lower. Examples of good solvents for polymers include dimethyl sulfoxide, dimethylformamide, dimethylacetamide, NMP, 2-pyrrolidone, GBL, 1,4-dioxane, 1,3-dimethyl-imidazolidinone, or a mixed solvent thereof. It will be done.
　ポリマー溶液中のポリマーの濃度は、８～３０質量％であることが好ましく、１２～２６質量％であることがより好ましい。ポリマー溶液中のポリマーの濃度が８質量％以上であることで、分離膜として使用できる強度や分離性能を有する多孔質膜又は複合膜を形成することができる。一方、ポリマー溶液中のポリマーの濃度が３０質量％以下であることで、良好な透過性能を有する多孔質膜又は複合膜を形成することができる。なお、ポリマー溶液中のポリマーの濃度の好ましい範囲は、用いるポリマー、溶媒、基材等によって適宜調整することができる。 The concentration of the polymer in the polymer solution is preferably 8 to 30% by mass, more preferably 12 to 26% by mass. When the concentration of the polymer in the polymer solution is 8% by mass or more, it is possible to form a porous membrane or a composite membrane that has strength and separation performance that can be used as a separation membrane. On the other hand, when the concentration of the polymer in the polymer solution is 30% by mass or less, a porous membrane or a composite membrane having good permeability can be formed. Note that the preferable range of the concentration of the polymer in the polymer solution can be adjusted as appropriate depending on the polymer, solvent, base material, etc. used.
　ポリマー溶液は、ポリマーの架橋剤を含有する。ポリマーの架橋剤は、ポリマー溶液に溶解することが必要であり、エポキシ系架橋剤、メチロール系架橋剤、アルコキシメチル系架橋剤、及びジアミン系架橋剤からなる群から選択される少なくとも一つの架橋剤であることが好ましい。 The polymer solution contains a polymer crosslinking agent. The crosslinking agent for the polymer needs to be dissolved in the polymer solution, and at least one crosslinking agent selected from the group consisting of an epoxy crosslinking agent, a methylol crosslinking agent, an alkoxymethyl crosslinking agent, and a diamine crosslinking agent. It is preferable that
　エポキシ系架橋剤としては、例えば、エチレングリコールジグリシジルエーテル、プロピレングリコールジグリシジルエーテル、１，４－ブタンジオールジグリシジルエーテル、ペンチレングリコールジグリシジルエーテル、ヘキシレングリコールジグリシジルエーテル、シクロヘキサンジメタノールジグリシジルエーテル、レゾルシノールグリシジルエーテル、グリセロールジグリシジルエーテル、グリセロールポリグリシジルエーテル、ジグリセロールポリグリシジルエーテル、トリメチロールプロパンポリグリシジルエーテル、ソルビトールジグリシジルエーテル、ソルビトールポリグリシジルエーテル、ポリエチレングリコールジグリシジルエーテル、ポリプロピレングリコールジグリシジルエーテル、ポリテトラメチレングリコールジグリシジルエーテル、ジ（２，３－エポキシプロピル）エーテル、１，３－ブタジエンジエポキシド、１，５－ヘキサジエンジエポキシド、１，２，７，８－ジエポキシオクタン、１，２，５，６－ジエポキシシクロオクタン、４－ビニルシクロヘキセンジエポキシド、ビスフェノールＡジグリシジルエーテル、マレイミド－エポキシ化合物が挙げられる。 Examples of the epoxy crosslinking agent include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, pentylene glycol diglycidyl ether, hexylene glycol diglycidyl ether, and cyclohexanedimethanol diglycidyl ether. Ether, resorcinol glycidyl ether, glycerol diglycidyl ether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, sorbitol diglycidyl ether, sorbitol polyglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether , polytetramethylene glycol diglycidyl ether, di(2,3-epoxypropyl) ether, 1,3-butadiene diepoxide, 1,5-hexadiene diepoxide, 1,2,7,8-diepoxyoctane, 1, Examples include 2,5,6-diepoxycyclooctane, 4-vinylcyclohexene diepoxide, bisphenol A diglycidyl ether, and maleimide-epoxy compounds.
　メチロール系架橋剤としては、例えば、ビスフェノールＡ・ホルムアルデヒド重縮合物が挙げられる。 Examples of the methylol-based crosslinking agent include bisphenol A/formaldehyde polycondensate.
　アルコキシメチル系架橋剤としては、例えば、ヘキサメトキシメチルメラミン、テトラメトキシメチルグリコールウリル、３，３’，５，５’－テトラキス（メトキシメチル）－［１，１’－ビフェニル］－４，４’－ジオール、４，４’，４”－エチリデントリス［２，６－（メトキシメチル）フェノール］（以下、「ＧＭＯＭ」）が挙げられる。 Examples of alkoxymethyl crosslinking agents include hexamethoxymethylmelamine, tetramethoxymethylglycoluril, 3,3',5,5'-tetrakis(methoxymethyl)-[1,1'-biphenyl]-4,4' -diol, 4,4',4''-ethylidene tris[2,6-(methoxymethyl)phenol] (hereinafter referred to as "GMOM").
　ジアミン系架橋剤としては、例えば、エチレンジアミン、トリメチレンジアミン、テトラメチレンジアミン、ペンタメチレンジアミン、ヘキサメチレンジアミン、ヘプタメチレンジアミン、オクタメチレンジアミン、１，８－ジアミノ－３，６－ジオキサオクタン、１，４－シクロヘキサンジアミン、４，４’－ジアミノジシクロヘキシルメタン、ビス（アミノメチル）ノルボルナンが挙げられる。 Examples of diamine crosslinking agents include ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, 1,8-diamino-3,6-dioxaoctane, 1 , 4-cyclohexanediamine, 4,4'-diaminodicyclohexylmethane, and bis(aminomethyl)norbornane.
　ポリマー溶液中の架橋剤の濃度は、１～２０質量％であることが好ましく、２～１５質量％であることがより好ましい。ポリマー溶液中の架橋剤の濃度が１質量％以上であることで、耐有機溶媒性及び良好な分離性能を有する多孔質膜又は複合膜を形成することができる。一方、ポリマー溶液中の架橋剤の濃度が２０質量％以下であることで、良好な透過性能を有する多孔質膜又は複合膜を形成することができる。 The concentration of the crosslinking agent in the polymer solution is preferably 1 to 20% by mass, more preferably 2 to 15% by mass. When the concentration of the crosslinking agent in the polymer solution is 1% by mass or more, a porous membrane or a composite membrane having organic solvent resistance and good separation performance can be formed. On the other hand, when the concentration of the crosslinking agent in the polymer solution is 20% by mass or less, a porous membrane or a composite membrane having good permeability can be formed.
　ポリマー溶液は、必要に応じて、孔径、空隙率、親水性、弾性率等を調整するための添加剤を含有してもよい。孔径及び空隙率を調節するための添加剤としては、例えば、水、アルコール類、ポリエチレングリコール、ポリビニルピロリドン、ポリビニルアルコール、ジエチレングリコール、ポリアクリル酸等の水溶性高分子またはその塩、さらに塩化リチウム、塩化ナトリウム、塩化カルシウム、硝酸リチウム等の無機塩、ホルムアミド等が挙げられる。親水性や弾性率を調整するための添加剤としては、種々の界面活性剤が挙げられる。 The polymer solution may contain additives for adjusting pore diameter, porosity, hydrophilicity, elastic modulus, etc., as necessary. Examples of additives for adjusting pore size and porosity include water, alcohols, water-soluble polymers such as polyethylene glycol, polyvinylpyrrolidone, polyvinyl alcohol, diethylene glycol, and polyacrylic acid, or salts thereof, and lithium chloride and chloride. Examples include inorganic salts such as sodium, calcium chloride, and lithium nitrate, and formamide. Various surfactants can be mentioned as additives for adjusting hydrophilicity and elastic modulus.
　多孔質膜を構成するモノマーや架橋剤等の成分の分析は、基材等との複合膜である場合、まず剥離により多孔質膜部位のみを得た後、種々の分析を行えばよい。例えば、多孔質膜が芳香族ポリイミドである場合、剥離により得られたポリイミド部位をアルカリにより加水分解した後、核磁気共鳴法、液体クロマトグラフィー質量分析法、又はガスクロマトグラフィー質量分析法等で分析することにより、芳香族ポリイミドを構成するモノマーを同定することが可能である。また、多孔質膜が架橋剤を用いた化学架橋を有する場合は上記の方法で架橋剤を同定することができる。多孔質膜が、アルカリにより、加水分解されない架橋構造を有する場合、架橋剤と反応したモノマーを核磁気共鳴法などで分析することで、架橋構造を同定することができる。 For analysis of components such as monomers and crosslinking agents constituting the porous membrane, in the case of a composite membrane with a base material, etc., it is sufficient to first obtain only the porous membrane portion by peeling, and then perform various analyses. For example, when the porous membrane is aromatic polyimide, the polyimide portion obtained by peeling is hydrolyzed with an alkali and then analyzed by nuclear magnetic resonance, liquid chromatography mass spectrometry, gas chromatography mass spectrometry, etc. By doing so, it is possible to identify the monomers that constitute the aromatic polyimide. Furthermore, when the porous membrane has chemical crosslinking using a crosslinking agent, the crosslinking agent can be identified by the method described above. When the porous membrane has a crosslinked structure that is not hydrolyzed by alkali, the crosslinked structure can be identified by analyzing the monomer reacted with the crosslinking agent using nuclear magnetic resonance or the like.
　次に、ポリマー溶液を塗布又は吐出し、凝固浴に浸漬させて固化させる。平膜状で単層の多孔質膜を製膜する場合、例えば、平坦な金属板上やガラス板上にポリマー溶液を塗布する。平膜状で基材を有する複合膜を製膜する場合、基材の少なくとも一方の面側にポリマー溶液を塗布する。 Next, a polymer solution is applied or discharged and immersed in a coagulation bath to solidify. When forming a flat single-layer porous membrane, for example, a polymer solution is applied onto a flat metal plate or glass plate. When forming a flat composite membrane having a base material, a polymer solution is applied to at least one surface of the base material.
　平膜状にポリマー溶液を塗布する工程には、例えば、スピンコーター、フローコーター、ロールコーター、スプレー、コンマコーター、バーコーター、グラビアコーター、スリットダイコーター、ドクターブレード等が利用できる。 For the step of applying the polymer solution in the form of a flat film, a spin coater, flow coater, roll coater, spray, comma coater, bar coater, gravure coater, slit die coater, doctor blade, etc. can be used, for example.
　一方、中空糸膜状で単層の多孔質膜を製膜する場合、例えば、二重管口金の外周部からポリマー溶液を、中心部から芯液を、同時に吐出する。中空糸膜状で基材を有する複合膜を製膜する場合、例えば、ポリマー溶液を貯留したコーティングノズルに中空糸状の基材を通過させ、基材の外表面にポリマー溶液を塗布する。 On the other hand, when forming a single-layer porous membrane in the form of a hollow fiber membrane, for example, a polymer solution is simultaneously discharged from the outer periphery of a double tube mouthpiece, and a core liquid is discharged from the center. When forming a composite membrane having a base material in the form of a hollow fiber membrane, for example, the hollow fiber base material is passed through a coating nozzle storing a polymer solution, and the polymer solution is applied to the outer surface of the base material.
　基材上にポリマー溶液を塗布する場合、ポリマー溶液の一部は基材中に含浸する。ポリマー溶液の基材中への含浸量は、基材上にポリマー溶液を塗布した後、凝固浴に浸漬させるまでの時間、ポリマー溶液の粘度、基材の通気度等によって適宜調整することができる。 When applying a polymer solution onto a substrate, a portion of the polymer solution is impregnated into the substrate. The amount of polymer solution impregnated into the base material can be adjusted as appropriate depending on the time from coating the polymer solution onto the base material to immersing it in the coagulation bath, the viscosity of the polymer solution, the air permeability of the base material, etc. .
　ポリマー溶液を塗布した後、凝固浴に浸漬させるまでの時間は、０．１～５秒であることが好ましい。凝固浴に浸漬させるまでの時間が０．１秒以上であることで、ポリマー溶液を基材中に十分含浸させることができる。一方、凝固浴に浸漬させるまでの時間が５秒以下であることで、空気中の水分によってポリマー溶液が固化するのを抑制することができる。なお、凝固浴に浸漬させるまでの時間の好ましい範囲は、用いるポリマー溶液の粘度等によって適宜調整することができる。 The time from application of the polymer solution to immersion in the coagulation bath is preferably 0.1 to 5 seconds. By setting the time for immersion in the coagulation bath to be 0.1 seconds or more, the polymer solution can be sufficiently impregnated into the base material. On the other hand, by setting the time for immersion in the coagulation bath to 5 seconds or less, it is possible to suppress solidification of the polymer solution due to moisture in the air. Note that the preferred range of time until immersion in the coagulation bath can be adjusted as appropriate depending on the viscosity of the polymer solution used.
　凝固浴は、ポリマー溶液の非溶媒を含むことが好ましい。ここで「非溶媒」とは、ポリマーの融点又は溶媒の沸点まで、ポリマーを溶解も膨潤もさせない溶媒をいう。ポリマーの非溶媒としては、例えば、水、メタノール、エタノール、トリクロルエチレン、エチレングリコール、ジエチレングリコール、トリエチレングリコール、プロピレングリコール、ブチレングリコール、ペンタンジオール、ヘキサンジオール、又は、これらの混合溶媒が挙げられる。一般的には水が用いられる。 The coagulation bath preferably contains a non-solvent for the polymer solution. The term "non-solvent" as used herein refers to a solvent that neither dissolves nor swells the polymer up to the melting point of the polymer or the boiling point of the solvent. Examples of the nonsolvent for the polymer include water, methanol, ethanol, trichlorethylene, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butylene glycol, pentanediol, hexanediol, or a mixed solvent thereof. Water is generally used.
　なお、多孔質膜の多孔構造は、非溶媒により誘起される相分離過程で形成される。薄層状にコートされたポリマー溶液をそのポリマーの非溶媒中に浸漬させた際、相分離により三次元網目構造等の多孔構造が形成され、膜の表面付近に粗大層、最表面に緻密層が形成される。 Note that the porous structure of the porous membrane is formed through a phase separation process induced by a nonsolvent. When a polymer solution coated in a thin layer is immersed in the polymer's non-solvent, a porous structure such as a three-dimensional network structure is formed due to phase separation, with a coarse layer near the surface of the membrane and a dense layer on the outermost surface. It is formed.
　連続的に多孔質膜又は複合膜の形成を行う場合には、ポリマー溶液と非溶媒とを接触させる凝固浴において、ポリマー溶液の溶媒が非溶媒と混合され、ポリマー溶液由来の溶媒の濃度が上昇する。そのため、凝固浴中の液体の組成が一定範囲に保たれるように、適宜凝固浴を入れ替えることが好ましい。凝固浴中の良溶媒の濃度が低いほど、ポリマー溶液の凝固が速くなるため、多孔質膜又は複合膜の構造が均質化され、優れた分離性能を発現させることができる。また、ポリマー溶液の凝固が速くなるため、製膜速度を上げることができ、多孔質膜又は複合膜の生産性を向上させることができる。凝固浴中の良溶媒の濃度は、２０％以下が好ましく、１５％以下がより好ましく、１０％以下がさらに好ましい。 When continuously forming a porous membrane or a composite membrane, the solvent of the polymer solution is mixed with the non-solvent in a coagulation bath in which the polymer solution and non-solvent are brought into contact, increasing the concentration of the solvent derived from the polymer solution. do. Therefore, it is preferable to replace the coagulation bath as appropriate so that the composition of the liquid in the coagulation bath is maintained within a certain range. The lower the concentration of the good solvent in the coagulation bath, the faster the polymer solution coagulates, so the structure of the porous membrane or composite membrane becomes more homogeneous, and excellent separation performance can be exhibited. Furthermore, since the polymer solution solidifies faster, the film forming rate can be increased, and the productivity of porous membranes or composite membranes can be improved. The concentration of the good solvent in the coagulation bath is preferably 20% or less, more preferably 15% or less, and even more preferably 10% or less.
　必要に応じて、得られた多孔質膜又は複合膜を熱水等により洗浄し、膜中に残存する溶媒を除去してもよい。ただし、後述する「（２－３）多孔質膜又は複合膜の架橋」で多孔質膜又は複合膜を架橋するため、多孔質膜又は複合膜中に残留したポリマーの架橋剤が溶出しすぎないよう、洗浄条件を適宜調整する必要がある。
　また、必要に応じて、得られた多孔質膜又は複合膜を乾燥させてもよい。 If necessary, the obtained porous membrane or composite membrane may be washed with hot water or the like to remove the solvent remaining in the membrane. However, since the porous membrane or composite membrane is crosslinked in "(2-3) Crosslinking of the porous membrane or composite membrane" described later, the polymer crosslinking agent remaining in the porous membrane or composite membrane will not be eluted too much. Therefore, it is necessary to adjust the cleaning conditions accordingly.
Further, the obtained porous membrane or composite membrane may be dried as necessary.
　（２－３）多孔質膜又は複合膜の架橋
　続いて、得られた多孔質膜又は複合膜を架橋することで、耐有機溶媒性を付与するとともに、分離性能を調整する。架橋には、「（２－２）多孔質膜又は複合膜の製膜」でポリマー溶液に溶解させ、凝固後の多孔質膜又は複合膜中に残留した、ポリマーの架橋剤を用いる。 (2-3) Crosslinking of porous membrane or composite membrane Subsequently, the obtained porous membrane or composite membrane is crosslinked to impart organic solvent resistance and adjust separation performance. For crosslinking, a polymer crosslinking agent that is dissolved in a polymer solution in "(2-2) Formation of porous membrane or composite membrane" and remains in the porous membrane or composite membrane after solidification is used.
　多孔質膜又は複合膜の架橋方法としては、熱架橋やＵＶ架橋等を用いることができるが、多孔質膜又は複合膜の着色の有無や膜厚によらず内部まで均一に架橋できることから、熱架橋が好ましい。以下、熱架橋による架橋方法を例にとって述べる。 As a crosslinking method for porous membranes or composite membranes, thermal crosslinking, UV crosslinking, etc. can be used, but thermal crosslinking can be used to uniformly crosslink the inside of the porous membrane or composite membrane regardless of its coloring or thickness. Crosslinking is preferred. Hereinafter, a crosslinking method using thermal crosslinking will be described as an example.
　熱架橋は空気中で行うことが好ましい。熱架橋の温度は、ポリマー及び基材の耐熱温度以下である必要があるが、９０～３００℃が好ましく、１２０～２５０℃がより好ましく、１６０～２３０℃がさらに好ましい。熱架橋の温度が９０℃以上であることで、耐有機溶媒性及び良好な分離性能を有する多孔質膜又は複合膜を形成することができる。一方、熱架橋の温度が３００℃以下であることで、ＮＩＰＳ法により形成された多孔構造が維持され、良好な分離性能及び透過性能を有する多孔質膜又は複合膜を形成することができる。 Thermal crosslinking is preferably carried out in air. The temperature of thermal crosslinking needs to be lower than the heat resistance temperature of the polymer and the base material, and is preferably 90 to 300°C, more preferably 120 to 250°C, and even more preferably 160 to 230°C. When the temperature of thermal crosslinking is 90° C. or higher, a porous membrane or a composite membrane having organic solvent resistance and good separation performance can be formed. On the other hand, when the temperature of thermal crosslinking is 300° C. or less, the porous structure formed by the NIPS method is maintained, and a porous membrane or composite membrane having good separation performance and permeation performance can be formed.
　また、熱架橋の時間は、３０秒～２０時間が好ましく、１分～１０時間がより好ましく、３分～４時間がさらに好ましい。熱架橋の時間が３０秒以上であることで、耐有機溶媒性及び良好な分離性能を有する多孔質膜又は複合膜を形成することができる。一方、熱架橋の時間が２０時間以下であることで、ＮＩＰＳ法により形成された多孔構造が維持され、良好な分離性能及び透過性能を有する多孔質膜又は複合膜を形成することができる。 Further, the thermal crosslinking time is preferably 30 seconds to 20 hours, more preferably 1 minute to 10 hours, and even more preferably 3 minutes to 4 hours. When the thermal crosslinking time is 30 seconds or more, a porous membrane or a composite membrane having organic solvent resistance and good separation performance can be formed. On the other hand, when the thermal crosslinking time is 20 hours or less, the porous structure formed by the NIPS method is maintained, and a porous membrane or composite membrane having good separation performance and permeation performance can be formed.
　上記のように、得られた多孔質膜に対して架橋を行うことで、多孔質膜を構成する芳香族ポリマーの主鎖が架橋され、３次元網目構造を形成するため有機溶媒中でも安定となり、分離性能を保持すると推測される。 As mentioned above, by crosslinking the obtained porous membrane, the main chain of the aromatic polymer that makes up the porous membrane is crosslinked, forming a three-dimensional network structure, which becomes stable even in organic solvents. It is assumed that separation performance is maintained.
　前記芳香族ポリマーが芳香族ポリイミドである場合、本工程中に残留したポリアミック酸のイミド化が進行する。そのため、芳香族ポリイミドのイミド化度は、「（２－１）ポリマーの重合」におけるイミド化工程の他に、本工程の温度及び時間によっても調整することができる。 When the aromatic polymer is an aromatic polyimide, imidization of the polyamic acid remaining during this step progresses. Therefore, the degree of imidization of the aromatic polyimide can be adjusted not only by the imidization step in "(2-1) Polymerization of polymer" but also by the temperature and time of this step.
　必要に応じて、得られた多孔質膜又は複合膜を熱水等により洗浄し、膜中に残存するポリマーの架橋剤等を除去してもよい。 If necessary, the obtained porous membrane or composite membrane may be washed with hot water or the like to remove the crosslinking agent of the polymer remaining in the membrane.
　また、必要に応じて、得られた多孔質膜又は複合膜を溶媒に浸漬し、膨潤させてもよい。多孔質膜又は複合膜を溶媒により膨潤させることで、架橋時に絶乾しエアロックした多孔質膜又は複合膜の透過性能を回復させることができる。多孔質膜又は複合膜全体を平衡膨潤させるため、溶媒としては、前駆体のポリマーの良溶媒を用いることが好ましい。 Furthermore, if necessary, the obtained porous membrane or composite membrane may be immersed in a solvent to swell it. By swelling the porous membrane or composite membrane with a solvent, it is possible to restore the permeation performance of the porous membrane or composite membrane that was completely dried and airlocked during crosslinking. In order to cause equilibrium swelling of the entire porous membrane or composite membrane, it is preferable to use a good solvent for the precursor polymer as the solvent.
　３．多孔質膜及び複合膜の利用
　本実施形態の多孔質膜及び複合膜は、プラスチックネット等の供給液流路材と、トリコット等の透過液流路材と、必要に応じて耐圧性を高めるためのフィルムと共に、多数の孔を穿設した筒状の集液管の周りに巻回され、スパイラル型のエレメントとして好適に用いられる。さらに、このエレメントを直列又は並列に接続して圧力容器に収納した多孔質膜又は複合膜モジュールとすることもできる。これらエレメントやモジュールの部品は供給液に対して耐性のある素材を用いることが好まれる。
　また、上記の多孔質膜及び複合膜並びにこれらを用いたエレメント及びモジュールは、それらに供給液を供給するポンプや、その供給水を前処理する装置等と組み合わせて、流体分離装置を構成することができる。この流体分離装置を用いることにより、供給液を溶質や不純物等が除去された透過液と膜を透過しなかった濃縮液とに分離して、目的にあった液を得ることができる。
　なお、エレメントは多孔質膜及び複合膜の形態によって、平板型、スパイラル型、プリーツ型、管状型、中空糸型等に分けられるが、いずれの形態でもよい。モジュールは供給される液の純度や分離後に必要な純度に応じて複数段用いてもよい。 3. Utilization of Porous Membranes and Composite Membranes The porous membranes and composite membranes of this embodiment are made of a feed liquid channel material such as a plastic net, a permeate channel material such as tricot, and, if necessary, a material for increasing pressure resistance. It is wound together with a film around a cylindrical liquid collecting pipe with a large number of holes, and is suitably used as a spiral type element. Furthermore, these elements can be connected in series or in parallel to form a porous membrane or composite membrane module housed in a pressure vessel. It is preferable to use materials for these elements and module parts that are resistant to the supply liquid.
In addition, the above porous membranes and composite membranes, as well as elements and modules using them, can be combined with a pump that supplies a feed liquid, a device that pre-treats the feed water, etc. to configure a fluid separation device. Can be done. By using this fluid separation device, it is possible to separate the feed liquid into a permeate liquid from which solutes, impurities, etc. have been removed, and a concentrate liquid that has not passed through the membrane, thereby obtaining a liquid suitable for the purpose.
The element may be classified into flat plate type, spiral type, pleated type, tubular type, hollow fiber type, etc. depending on the form of the porous membrane and composite membrane, but any form may be used. A plurality of modules may be used depending on the purity of the liquid to be supplied and the purity required after separation.
　以下に具体的な実施例を挙げて本発明を説明するが、本発明はこれらの実施例により何ら限定されるものではない。
　本実施形態の多孔質膜及び複合膜に関する物性値は、以下の方法で測定した。 The present invention will be described below with reference to specific examples, but the present invention is not limited to these examples in any way.
Physical property values regarding the porous membrane and composite membrane of this embodiment were measured by the following method.
　（１）重量平均分子量
　ポリマーのＭｗ（ポリスチレン換算）を、ゲル浸透クロマトグラフィー（東ソー製；ＨＬＣ－８０２２）を用いて測定した。具体的な測定条件は以下のとおりとした。
　カラム：ＴＳＫ　ｇｅｌ　ＳｕｐｅｒＨＭ－Ｈ（東ソー製；内径６．０ｍｍ、長さ１５ｃｍ）２本
　溶離液：ＬｉＢｒ／ＮＭＰ溶液（１０ｍＭ）
　サンプル濃度：０．１質量％
　流量：０．５ｍＬ／ｍｉｎ
　温度：４０℃ (1) Weight average molecular weight The Mw (polystyrene equivalent) of the polymer was measured using gel permeation chromatography (manufactured by Tosoh; HLC-8022). The specific measurement conditions were as follows.
Column: 2 TSK gel SuperHM-H (manufactured by Tosoh; inner diameter 6.0 mm, length 15 cm) Eluent: LiBr/NMP solution (10 mM)
Sample concentration: 0.1% by mass
Flow rate: 0.5mL/min
Temperature: 40℃
　（２）イミド化度
　架橋ポリマーのイミド化度を、フーリエ変換赤外分光光度計（島津製作所製；ＩＲＴｒａｃｅｒ－１００）を用いて測定した。多孔質膜又は複合膜を３ｃｍ×３ｃｍ切り出し、マイクロメータービジョン（株式会社エス・ティ・ジャパン製）を用いて赤外全反射吸収測定法（ＡＴＲ法）にて、多孔質膜表面を測定し（入射角：４８度、プリズム：ダイヤモンド、分解能：４ｃｍ－１、積算回数：６４回）、１４９０～１５２０ｃｍ－１に検出される芳香環由来のピーク強度Ａ、１７６０～１７９０ｃｍ－１に検出されるイミド基由来のピーク強度Ｂから、下記式１によりイミド化度を算出した。
　イミド化度＝Ｂ／Ａ　　　・・・（式１） (2) Degree of imidization The degree of imidization of the crosslinked polymer was measured using a Fourier transform infrared spectrophotometer (manufactured by Shimadzu Corporation; IRTracer-100). A 3 cm x 3 cm piece of porous membrane or composite membrane was cut out, and the surface of the porous membrane was measured by infrared total reflection absorption measurement (ATR method) using Micrometer Vision (manufactured by S.T. Japan Co., Ltd.). Incident angle: 48 degrees, prism: diamond, resolution: 4 cm -1 , number of integrations: 64 times), peak intensity A derived from aromatic ring detected at 1490 to 1520 cm -1 , imide detected at 1760 to 1790 cm -1 The degree of imidization was calculated from the group-derived peak intensity B using the following formula 1.
Imidization degree = B/A (Formula 1)
　（３）空隙率
　後述する「（８）膜厚」に記載の方法で多孔質膜の膜厚を測定して算出した膜体積（ｃｍ３）と質量（ｇ）から、下記式２を用いて多孔質膜の空隙率（％）を算出した。なお、空隙率算出の密度は、芳香族ポリマーの種類に応じて該ポリマーの一般的な密度を用いた。例えば、芳香族ポリマーが芳香族ポリイミドである場合、密度は１．４２ｇ／ｃｍ３とした。
　空隙率（％）＝｛１－質量／（密度×膜体積）｝×１００　　　・・・（式２） (3) Porosity From the membrane volume (cm 3 ) and mass (g) calculated by measuring the membrane thickness of the porous membrane using the method described in "(8) Membrane thickness" described below, use the following formula 2. The porosity (%) of the porous membrane was calculated. Note that, as the density for calculating the porosity, a general density of the aromatic polymer was used depending on the type of the polymer. For example, when the aromatic polymer is an aromatic polyimide, the density is 1.42 g/cm 3 .
Porosity (%) = {1-mass/(density x film volume)} x 100 (Formula 2)
　（４）膜透過流束、阻止率
　多孔質膜又は複合膜の膜透過流束を、膜種類に応じて評価した。多孔質膜又は複合膜がＯＳＲＯ（分画分子量２００未満）である場合、２０ｐｐｍ標準ポリスチレン（Ｍｗ１６２）／ＮＭＰ溶液を操作圧力３０ｂａｒで供給して、クロスフロー膜ろ過試験を行った。多孔質膜又は複合膜がＯＳＮ（分画分子量２００～１，０００）である場合、２０ｐｐｍ標準ポリスチレン（Ｍｗ５８０）／ＮＭＰ溶液を操作圧力１５ｂａｒで供給して、クロスフロー膜ろ過試験を行った。多孔質膜又は複合膜がＯＳＵ（分画分子量１，０００以上）である場合、２０ｐｐｍ標準ポリスチレン（Ｍｗ１００，０００）／ＮＭＰ溶液を操作圧力２ｂａｒで供給して、クロスフロー膜ろ過試験を行った。透過液量（Ｌ）、単位膜面積（ｍ２）及び単位時間（ｈ）から、下記式３を用いて多孔質膜又は複合膜の膜透過流束（Ｌ／ｍ２／ｈ／ｂａｒ）を算出した。また、原液中の標準ポリスチレン濃度Ｃ（ｐｐｍ）及び透過液中の標準ポリスチレン濃度Ｄ（ｐｐｍ）から、下記式４を用いて多孔質膜又は複合膜の阻止率（％）を算出した。
　膜透過流束（Ｌ／ｍ２／ｈ／ｂａｒ）＝透過液量／（単位膜面積×単位時間）／操作圧力　　　・・・（式３）
　阻止率（％）＝（１－Ｄ／Ｃ）×１００　　　・・・（式４） (4) Membrane permeation flux, rejection rate The membrane permeation flux of the porous membrane or composite membrane was evaluated according to the membrane type. When the porous membrane or composite membrane was OSRO (molecular weight cut off less than 200), a cross-flow membrane filtration test was performed by supplying a 20 ppm standard polystyrene (Mw 162)/NMP solution at an operating pressure of 30 bar. When the porous membrane or composite membrane was OSN (molecular weight cut off 200-1,000), a cross-flow membrane filtration test was conducted by supplying a 20 ppm standard polystyrene (Mw 580)/NMP solution at an operating pressure of 15 bar. When the porous membrane or composite membrane was OSU (molecular weight cut off 1,000 or more), a cross-flow membrane filtration test was conducted by supplying a 20 ppm standard polystyrene (Mw 100,000)/NMP solution at an operating pressure of 2 bar. From the amount of permeated liquid (L), unit membrane area (m 2 ) and unit time (h), calculate the membrane permeation flux (L/m 2 /h/bar) of the porous membrane or composite membrane using equation 3 below. Calculated. Further, the rejection rate (%) of the porous membrane or composite membrane was calculated from the standard polystyrene concentration C (ppm) in the stock solution and the standard polystyrene concentration D (ppm) in the permeate using the following formula 4.
Membrane permeation flux (L/m 2 /h/bar) = permeate volume/(unit membrane area x unit time)/operating pressure (Formula 3)
Rejection rate (%) = (1-D/C) x 100 (Formula 4)
　（５）共重合比
　フッ素系芳香族モノマーと非フッ素系芳香族モノマーの共重合比は、プロトン核磁気共鳴法（ＪＮＭ－ＥＣＺ４００Ｒ（日本電子株式会社（ＪＥＯＬ）製））を用いて算出した。ジアミンモノマーの中でフッ素系芳香族モノマーとして４，４’－ジヒドロキシ－３，３’－ジアミノフェニルヘキサフルオロプロパン、非フッ素系芳香族モノマーとして４，４’－ジアミノジフェニルエーテルを、酸無水物モノマーとして３，３’，４，４’－ジフェニルエーテルテトラカルボン酸二無水物を用いてポリイミドを合成した場合、重ジメチルスルホキシドを溶媒としてポリイミドを溶解させた後、プロトン核磁気共鳴のシグナルの中で３，３’，４，４’－ジフェニルエーテルテトラカルボン酸二無水物由来の８．０ｐｐｍ付近のピークの面積（Ｓ１）と４，４’－ジヒドロキシ－３，３’－ジアミノフェニルヘキサフルオロプロパン由来の１０．５ｐｐｍ付近のピークの面積（Ｓ２）を算出する。上述の酸無水物モノマーと上述のジアミンモノマーは等モル反応していると近似し、下記式５を用いてフッ素系芳香族モノマーと非フッ素系芳香族モノマーの共重合比を得た。
　フッ素系芳香族モノマーと非フッ素系芳香族モノマーの共重合比＝Ｓ２：（Ｓ１－Ｓ２）　　　・・・（式５） (5) Copolymerization ratio The copolymerization ratio of the fluorinated aromatic monomer and the non-fluorinated aromatic monomer was calculated using proton nuclear magnetic resonance method (JNM-ECZ400R (manufactured by JEOL Ltd. (JEOL)). Among the diamine monomers, 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane is used as a fluorinated aromatic monomer, 4,4'-diaminodiphenyl ether is used as a non-fluorinated aromatic monomer, and 4,4'-diaminodiphenyl ether is used as an acid anhydride monomer. When polyimide is synthesized using 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, after dissolving the polyimide in deuterium dimethyl sulfoxide as a solvent, 3, The area (S1) of the peak around 8.0 ppm derived from 3',4,4'-diphenyl ether tetracarboxylic dianhydride and 10.0 ppm derived from 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane. The area (S2) of the peak near 5 ppm is calculated. It was approximated that the above-mentioned acid anhydride monomer and the above-mentioned diamine monomer reacted in equimolar amounts, and the copolymerization ratio of the fluorine-based aromatic monomer and the non-fluorine-based aromatic monomer was obtained using the following formula 5.
Copolymerization ratio of fluorinated aromatic monomer and non-fluorinated aromatic monomer = S2: (S1-S2) (Formula 5)
　（６）９０度負荷試験
　多孔質膜の力学物性に関する評価は、テンシロン試験機（株式会社エイ・アンド・デイ製　ＲＴＧ－１２１０）を用いて測定した。各実施例、比較例にて得られた芳香族ポリマー２２質量％、ＧＭＯＭ２質量％、ＮＭＰ３８質量％、１，４－ジオキサン３８質量％を２５℃で溶解し、ポリマー溶液を調製した。このポリマー溶液を、ガラス板に２５℃で塗布し、３秒後、２５℃の蒸留水からなる凝固浴に３０秒浸漬して凝固させ、多孔質膜を作製した。得られた多孔質膜を２５℃の水に２４時間浸漬させた後、風乾し、幅２５ｍｍ、長さ２００ｍｍの試験片を作製した。カプトン両面テープ（株式会社寺岡製作所製）を用いて、片方の端部から１００ｍｍの位置まで試験片を地面と接着させた。その後、接着していない側の試験片が地面と９０度の定角となるように、接着していない試験片の端部を引張試験機のつかみ具で留め、引っ張り速度毎分２０ｍｍで、３０ｇまたは５０ｇの負荷がかかるまで引っ張り試験を行った。この間、接着面が剥離しないように試験片をカプトン両面テープで地面に接着した。この試験を異なる試験片で５回行い、破断及びひび割れの有無を確認し、５回すべての試験において、破断及びひび割れのいずれも観測されない場合を、「○」とした。 (6) 90 degree load test The mechanical properties of the porous membrane were evaluated using a Tensilon tester (RTG-1210, manufactured by A&D Co., Ltd.). A polymer solution was prepared by dissolving 22% by mass of the aromatic polymer, 2% by mass of GMOM, 38% by mass of NMP, and 38% by mass of 1,4-dioxane obtained in each Example and Comparative Example at 25°C. This polymer solution was applied to a glass plate at 25°C, and after 3 seconds, it was immersed in a coagulation bath consisting of distilled water at 25°C for 30 seconds to coagulate, thereby producing a porous membrane. The obtained porous membrane was immersed in water at 25° C. for 24 hours and then air-dried to prepare a test piece with a width of 25 mm and a length of 200 mm. The test piece was adhered to the ground 100 mm from one end using Kapton double-sided tape (manufactured by Teraoka Seisakusho Co., Ltd.). After that, the end of the unbonded specimen was fixed with the grip of the tensile tester so that the specimen on the unbonded side was at a constant angle of 90 degrees with the ground, and the tensile strength was 30 g at a tensile speed of 20 mm/min. Alternatively, a tensile test was performed until a load of 50 g was applied. During this time, the test piece was adhered to the ground using Kapton double-sided tape to prevent the adhesive surface from peeling off. This test was performed 5 times using different test pieces to check the presence or absence of breaks and cracks, and a case where neither breaks nor cracks were observed in all 5 tests was rated as "○".
　（７）多孔質膜の断面に占めるマクロボイドの面積割合及びマクロボイドのアスペクト比
　多孔質膜又は複合膜を１０ｃｍ２の大きさに切り出し、９０℃の蒸留水で１０分洗浄し、乾燥させた。次に液体窒素を用いて膜を凍結後、破断させることで多孔質膜の断面観察試料を作製した。スパッタリング装置により試料に白金粒子によるコーティングを行った後、走査型電子顕微鏡（日立ハイテクノロジーズ社製、Ｓ－５５００）を用いて、倍率５００倍で多孔質膜断面の画像を撮影した。ここで、多孔質膜の断面は、多孔質膜表面に対して垂直の方向に切断したものである。 (7) Area ratio of macrovoids in the cross section of porous membrane and aspect ratio of macrovoids A porous membrane or a composite membrane was cut into a size of 10cm2 , washed with distilled water at 90°C for 10 minutes, and dried. . Next, a cross-sectional observation sample of the porous membrane was prepared by freezing the membrane using liquid nitrogen and breaking it. After the sample was coated with platinum particles using a sputtering device, a cross-sectional image of the porous membrane was photographed at a magnification of 500 times using a scanning electron microscope (manufactured by Hitachi High-Technologies, S-5500). Here, the cross section of the porous membrane is cut in a direction perpendicular to the surface of the porous membrane.
　走査型電子顕微鏡での観察により得られた多孔質膜の断面構造の中で、多孔質膜断面の面積（Ｓ３）及び多孔質膜断面に存在するマクロボイド部分の面積の和（Ｓ４）を算出した。面積の算出は画像処理ソフト「ＩｍａｇｅＪ」で多孔質膜部分及びマクロボイドの外周をプロットし、面積を算出した。プロットは１つのマクロボイドに対して少なくとも３０点以上とした。下記式６を用いて、多孔質膜の断面に占めるマクロボイドの面積割合を算出した。異なる５枚の多孔質膜断面の画像で同様に算出し、その平均値を多孔質膜の断面に占めるマクロボイドの面積割合とした。
　多孔質膜の断面に占めるマクロボイドの面積割合（％）＝Ｓ４／Ｓ３×１００　　　・・・（式６） In the cross-sectional structure of the porous membrane obtained by observation with a scanning electron microscope, calculate the area of the cross-section of the porous membrane (S3) and the sum of the areas of the macrovoid portions present in the cross-section of the porous membrane (S4). did. The area was calculated by plotting the porous membrane portion and the outer periphery of the macrovoid using image processing software "ImageJ". The plot included at least 30 points for one macrovoid. Using Equation 6 below, the area ratio of macrovoids to the cross section of the porous membrane was calculated. The calculation was performed in the same manner using five different cross-sectional images of the porous membrane, and the average value was taken as the area ratio of macrovoids in the cross-section of the porous membrane.
Area ratio (%) of macrovoids in the cross section of the porous membrane = S4/S3×100 (Formula 6)
　また、マクロボイドのアスペクト比は、１枚の画像において無作為に１０個のマクロボイドを選択し、画像処理ソフト「ＩｍａｇｅＪ」を用いて、各マクロボイドについて多孔質膜表面に対して垂直な方向の長さと多孔質膜表面に対して水平な方向の長さを求め、アスペクト比を算出した。これを５枚の画像で行い、得られた５０個のマクロボイドのアスペクト比の平均値を多孔質膜のアスペクト比とした。 In addition, the aspect ratio of the macrovoids was determined by randomly selecting 10 macrovoids in one image and using the image processing software "ImageJ" to calculate the aspect ratio of each macrovoid in the direction perpendicular to the porous membrane surface. The length and the length in the horizontal direction to the porous membrane surface were determined, and the aspect ratio was calculated. This was performed using five images, and the average value of the aspect ratios of the obtained 50 macrovoids was taken as the aspect ratio of the porous membrane.
　（８）膜厚
　得られた多孔質膜、平衡膨潤状態に達した後の多孔質膜及び複合膜の厚みは、ダイヤルシックネスゲージ（株式会社テクロック製、定圧厚さ測定器ＰＧ－０１Ａ）を用いて測定した。膜の両端から均等に１０点測定し、その平均値を膜厚とした。 (8) Film thickness The thickness of the obtained porous film, the porous film after reaching the equilibrium swelling state, and the composite film was measured using a dial thickness gauge (manufactured by Techrock Co., Ltd., constant pressure thickness measuring device PG-01A). It was measured using Measurements were taken at 10 points evenly from both ends of the film, and the average value was taken as the film thickness.
　（９）膨潤度
　上述の「（８）膜厚」で得られた多孔質膜及び平衡膨潤状態に達した後の多孔質膜の厚みから、下記式７を用いて多孔質膜の膨潤度を算出した。
　膨潤度（％）＝（平衡膨潤状態に達した後の多孔質膜の厚み／多孔質膜の厚み）×１００　　　・・・（式７） (9) Swelling degree From the porous membrane obtained in "(8) Membrane thickness" above and the thickness of the porous membrane after reaching the equilibrium swelling state, use the following formula 7 to calculate the swelling degree of the porous membrane. Calculated.
Swelling degree (%) = (Thickness of porous membrane after reaching equilibrium swelling state/Thickness of porous membrane) × 100 (Formula 7)
　実施例及び比較例で用いた多孔質膜及び複合膜の原料を、以下にまとめる。
フッ素原子を含有する芳香族ジアミンモノマー：４，４’－ジヒドロキシ－３，３’－ジアミノフェニルヘキサフルオロプロパン（東京化成工業製）
フッ素原子を含有する芳香族ジアミンモノマー：２，２－ビス（４－アミノフェニル）ヘキサフルオロプロパン（東京化成工業製）
フッ素原子を含有しない芳香族ジアミンモノマー：４，４’－ジアミノジフェニルエーテル（東京化成工業製）
末端封止剤：３－アミノフェノール（東京化成工業製）
溶媒：ＮＭＰ（富士フイルム和光純薬製）
溶媒：１，４－ジオキサン（富士フイルム和光純薬製）
酸無水物モノマー：３，３’，４，４’－ジフェニルエーテルテトラカルボン酸二無水物（東京化成工業製）
架橋剤：ＧＭＯＭ（群栄化学工業製） The raw materials for the porous membranes and composite membranes used in Examples and Comparative Examples are summarized below.
Aromatic diamine monomer containing fluorine atom: 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane (manufactured by Tokyo Kasei Kogyo)
Aromatic diamine monomer containing fluorine atom: 2,2-bis(4-aminophenyl)hexafluoropropane (manufactured by Tokyo Chemical Industry Co., Ltd.)
Aromatic diamine monomer that does not contain fluorine atoms: 4,4'-diaminodiphenyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.)
Terminal capping agent: 3-aminophenol (manufactured by Tokyo Kasei Kogyo)
Solvent: NMP (manufactured by Fujifilm Wako Pure Chemical Industries)
Solvent: 1,4-dioxane (manufactured by Fujifilm Wako Pure Chemical Industries)
Acid anhydride monomer: 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride (manufactured by Tokyo Kasei Kogyo)
Crosslinking agent: GMOM (manufactured by Gunei Chemical Industry)
　（実施例１）
　４，４’－ジヒドロキシ－３，３’－ジアミノフェニルヘキサフルオロプロパン４．４質量％、４，４’－ジアミノジフェニルエーテル４．８質量％、３－アミノフェノール０．１８質量％、ＮＭＰ８２質量％を２０℃で溶解し、３，３’，４，４’－ジフェニルエーテルテトラカルボン酸二無水物８．６質量％を添加し、２０℃で３時間攪拌することで、芳香族ポリアミック酸溶液を得た。続いて、２００℃で３時間攪拌することでイミド化を進行させ、水を貧溶媒とした再沈殿法により芳香族ポリイミドを精製した。得られた芳香族ポリイミドのＭｗは２８，０００であった。 (Example 1)
4.4% by mass of 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane, 4.8% by mass of 4,4'-diaminodiphenyl ether, 0.18% by mass of 3-aminophenol, and 82% by mass of NMP. An aromatic polyamic acid solution was obtained by dissolving at 20°C, adding 8.6% by mass of 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, and stirring at 20°C for 3 hours. . Subsequently, imidization was progressed by stirring at 200° C. for 3 hours, and the aromatic polyimide was purified by reprecipitation using water as a poor solvent. The Mw of the obtained aromatic polyimide was 28,000.
　次に、得られた芳香族ポリイミド２２質量％、ＧＭＯＭ２質量％、ＮＭＰ３８質量％、１，４－ジオキサン３８質量％を２５℃で溶解し、ポリマー溶液を調製した。このポリマー溶液を、ガラス板に２５℃で塗布し、３秒後、２５℃の蒸留水からなる凝固浴に３０秒浸漬して凝固させ、乾燥させることで、多孔質膜を得た。 Next, 22% by mass of the obtained aromatic polyimide, 2% by mass of GMOM, 38% by mass of NMP, and 38% by mass of 1,4-dioxane were dissolved at 25° C. to prepare a polymer solution. This polymer solution was applied to a glass plate at 25° C., and after 3 seconds, it was immersed in a coagulation bath of distilled water at 25° C. for 30 seconds to coagulate and dry, thereby obtaining a porous membrane.
　続いて、得られた多孔質膜を２００℃で２時間加熱することで、芳香族ポリイミドを架橋させた。得られた架橋ポリマーのイミド化度は０．４５であった。得られた多孔質膜の厚みは５０μｍであった。得られた多孔質膜を評価した結果を、表１に示す。 Subsequently, the obtained porous membrane was heated at 200° C. for 2 hours to crosslink the aromatic polyimide. The degree of imidization of the obtained crosslinked polymer was 0.45. The thickness of the obtained porous membrane was 50 μm. Table 1 shows the results of evaluating the obtained porous membrane.
　（実施例２）
　実施例１で得たポリマー溶液を、通気度０．６ｃｍ３／ｃｍ２／ｓのＰＰＳ短繊維不織布に２５℃で塗布し、３秒後、２５℃の蒸留水からなる凝固浴に３０秒浸漬して凝固させ、乾燥させることで、複合膜を得た。 (Example 2)
The polymer solution obtained in Example 1 was applied to a PPS short fiber nonwoven fabric with an air permeability of 0.6 cm 3 /cm 2 /s at 25°C, and after 3 seconds, it was immersed in a coagulation bath consisting of distilled water at 25°C for 30 seconds. A composite membrane was obtained by solidifying and drying.
　続いて、得られた複合膜を２００℃で２時間加熱することで、芳香族ポリイミドを架橋させた。得られた架橋ポリマーのイミド化度は０．４５であった。得られた複合膜の厚みは１８０μｍであった。得られた複合膜を評価した結果を、表１に示す。 Subsequently, the resulting composite membrane was heated at 200°C for 2 hours to crosslink the aromatic polyimide. The degree of imidization of the obtained crosslinked polymer was 0.45. The thickness of the obtained composite membrane was 180 μm. Table 1 shows the results of evaluating the obtained composite membrane.
　（実施例３）
　４，４’－ジヒドロキシ－３，３’－ジアミノフェニルヘキサフルオロプロパン３．９質量％、４，４’－ジアミノジフェニルエーテル４．２質量％、ＮＭＰ８２質量％を２０℃で溶解し、３，３’，４，４’－ジフェニルエーテルテトラカルボン酸二無水物９．９質量％を添加し、２０℃で３時間攪拌することで、芳香族ポリアミック酸溶液を得た。続いて、２００℃で３時間攪拌することでイミド化を進行させ、水を貧溶媒とした再沈殿法により芳香族ポリイミドを精製した。得られた芳香族ポリイミドのＭｗは６５，０００であり、フッ素系芳香族モノマーと、非フッ素系芳香族モノマーとの共重合比は、３３：６７であった。 (Example 3)
3.9% by mass of 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane, 4.2% by mass of 4,4'-diaminodiphenyl ether, and 82% by mass of NMP were dissolved at 20°C, and 3,3' , 9.9% by mass of 4,4'-diphenyl ether tetracarboxylic dianhydride was added and stirred at 20°C for 3 hours to obtain an aromatic polyamic acid solution. Subsequently, imidization was progressed by stirring at 200° C. for 3 hours, and the aromatic polyimide was purified by reprecipitation using water as a poor solvent. The Mw of the obtained aromatic polyimide was 65,000, and the copolymerization ratio of the fluorine-based aromatic monomer and the non-fluorine-based aromatic monomer was 33:67.
　また、得られた芳香族ポリイミド２０質量％、ＧＭＯＭ２質量％、ＮＭＰ３９質量％、１，４－ジオキサン３９質量％を２５℃で溶解し、ポリマー溶液を調製した。このポリマー溶液を、通気度０．６ｃｍ３／ｃｍ２／ｓのＰＰＳ短繊維不織布に２５℃で塗布し、３秒後、２５℃の蒸留水からなる凝固浴に３０秒浸漬して凝固させ、乾燥させることで、複合膜を得た。 Further, 20% by mass of the obtained aromatic polyimide, 2% by mass of GMOM, 39% by mass of NMP, and 39% by mass of 1,4-dioxane were dissolved at 25° C. to prepare a polymer solution. This polymer solution was applied to a PPS short fiber nonwoven fabric with an air permeability of 0.6 cm 3 /cm 2 /s at 25°C, and after 3 seconds, it was immersed in a coagulation bath consisting of distilled water at 25°C for 30 seconds to coagulate. A composite membrane was obtained by drying.
　続いて、得られた複合膜を２００℃で２時間加熱することで、芳香族ポリイミドを架橋させた。得られた架橋ポリマーのイミド化度は０．５３であった。得られた複合膜の厚みは１６５μｍであった。得られた複合膜を評価した結果を、表１に示す。 Subsequently, the resulting composite membrane was heated at 200°C for 2 hours to crosslink the aromatic polyimide. The degree of imidization of the obtained crosslinked polymer was 0.53. The thickness of the obtained composite membrane was 165 μm. Table 1 shows the results of evaluating the obtained composite membrane.
（実施例４）
　４，４’－ジヒドロキシ－３，３’－ジアミノフェニルヘキサフルオロプロパン３．４質量％、４，４’－ジアミノジフェニルエーテル４．６質量％、ＮＭＰ８２質量％を２０℃で溶解し、３，３’，４，４’－ジフェニルエーテルテトラカルボン酸二無水物１０質量％を添加し、２０℃で３時間攪拌することで、芳香族ポリアミック酸溶液を得た。続いて、２００℃で３時間攪拌することでイミド化を進行させ、水を貧溶媒とした再沈殿法により芳香族ポリイミドを精製した。得られた芳香族ポリイミドのＭｗは５４，０００であり、フッ素系芳香族モノマーと、非フッ素系芳香族モノマーとの共重合比は、２９：７１であった。 (Example 4)
3.4% by mass of 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane, 4.6% by mass of 4,4'-diaminodiphenyl ether, and 82% by mass of NMP were dissolved at 20°C, and 3,3' , 4,4'-diphenyl ether tetracarboxylic dianhydride (10% by mass) was added thereto, and the mixture was stirred at 20° C. for 3 hours to obtain an aromatic polyamic acid solution. Subsequently, imidization was progressed by stirring at 200° C. for 3 hours, and the aromatic polyimide was purified by reprecipitation using water as a poor solvent. The Mw of the obtained aromatic polyimide was 54,000, and the copolymerization ratio of the fluorinated aromatic monomer and the non-fluorinated aromatic monomer was 29:71.
　次に、得られた芳香族ポリイミド２２質量％、ＧＭＯＭ２質量％、ＮＭＰ３８質量％、１，４－ジオキサン３８質量％を２５℃で溶解し、ポリマー溶液を調製した。このポリマー溶液を、ガラス板に２５℃で塗布し、３秒後、２５℃の蒸留水からなる凝固浴に３０秒浸漬して凝固させ、乾燥させることで、多孔質膜を得た。 Next, 22% by mass of the obtained aromatic polyimide, 2% by mass of GMOM, 38% by mass of NMP, and 38% by mass of 1,4-dioxane were dissolved at 25° C. to prepare a polymer solution. This polymer solution was applied to a glass plate at 25° C., and after 3 seconds, it was immersed in a coagulation bath of distilled water at 25° C. for 30 seconds to coagulate and dry, thereby obtaining a porous membrane.
　続いて、得られた多孔質膜を２００℃で２時間加熱することで、芳香族ポリイミドを架橋させた。得られた架橋ポリマーのイミド化度は０．５４であった。得られた多孔質膜の厚みは４１μｍであった。得られた多孔質膜を評価した結果を、表１に示す。 Subsequently, the obtained porous membrane was heated at 200° C. for 2 hours to crosslink the aromatic polyimide. The degree of imidization of the obtained crosslinked polymer was 0.54. The thickness of the obtained porous membrane was 41 μm. Table 1 shows the results of evaluating the obtained porous membrane.
（実施例５）
　４，４’－ジヒドロキシ－３，３’－ジアミノフェニルヘキサフルオロプロパン５．６質量％、４，４’－ジアミノジフェニルエーテル３．０質量％、ＮＭＰ８２質量％を２０℃で溶解し、３，３’，４，４’－ジフェニルエーテルテトラカルボン酸二無水物９．４質量％を添加し、２０℃で３時間攪拌することで、芳香族ポリアミック酸溶液を得た。続いて、２００℃で３時間攪拌することでイミド化を進行させ、水を貧溶媒とした再沈殿法により芳香族ポリイミドを精製した。得られた芳香族ポリイミドのＭｗは５８，０００であり、フッ素系芳香族モノマーと、非フッ素系芳香族モノマーとの共重合比は、５０：５０であった。 (Example 5)
5.6% by mass of 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane, 3.0% by mass of 4,4'-diaminodiphenyl ether, and 82% by mass of NMP were dissolved at 20°C, and 3,3' , 9.4% by mass of 4,4'-diphenyl ether tetracarboxylic dianhydride was added and stirred at 20°C for 3 hours to obtain an aromatic polyamic acid solution. Subsequently, imidization was progressed by stirring at 200° C. for 3 hours, and the aromatic polyimide was purified by reprecipitation using water as a poor solvent. The Mw of the obtained aromatic polyimide was 58,000, and the copolymerization ratio of the fluorine-based aromatic monomer and the non-fluorine-based aromatic monomer was 50:50.
　次に、得られた芳香族ポリイミド２２質量％、ＧＭＯＭ２質量％、ＮＭＰ３８質量％、１，４－ジオキサン３８質量％を２５℃で溶解し、ポリマー溶液を調製した。このポリマー溶液を、ガラス板に２５℃で塗布し、３秒後、２５℃の蒸留水からなる凝固浴に３０秒浸漬して凝固させ、乾燥させることで、多孔質膜を得た。 Next, 22% by mass of the obtained aromatic polyimide, 2% by mass of GMOM, 38% by mass of NMP, and 38% by mass of 1,4-dioxane were dissolved at 25° C. to prepare a polymer solution. This polymer solution was applied to a glass plate at 25° C., and after 3 seconds, it was immersed in a coagulation bath of distilled water at 25° C. for 30 seconds to coagulate and dry, thereby obtaining a porous membrane.
　続いて、得られた多孔質膜を２００℃で２時間加熱することで、芳香族ポリイミドを架橋させた。得られた架橋ポリマーのイミド化度は０．５３であった。得られた多孔質膜の厚みは４３μｍであった。得られた多孔質膜を評価した結果を、表１に示す。 Subsequently, the obtained porous membrane was heated at 200° C. for 2 hours to crosslink the aromatic polyimide. The degree of imidization of the obtained crosslinked polymer was 0.53. The thickness of the obtained porous membrane was 43 μm. Table 1 shows the results of evaluating the obtained porous membrane.
（実施例６）
　４，４’－ジヒドロキシ－３，３’－ジアミノフェニルヘキサフルオロプロパン６．０質量％、４，４’－ジアミノジフェニルエーテル２．７質量％、ＮＭＰ８２質量％を２０℃で溶解し、３，３’，４，４’－ジフェニルエーテルテトラカルボン酸二無水物９．３質量％を添加し、２０℃で３時間攪拌することで、芳香族ポリアミック酸溶液を得た。続いて、２００℃で３時間攪拌することでイミド化を進行させ、水を貧溶媒とした再沈殿法により芳香族ポリイミドを精製した。得られた芳香族ポリイミドのＭｗは５６，０００であり、フッ素系芳香族モノマーと、非フッ素系芳香族モノマーとの共重合比は、５５：４５であった。 (Example 6)
6.0% by mass of 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane, 2.7% by mass of 4,4'-diaminodiphenyl ether, and 82% by mass of NMP were dissolved at 20°C, and 3,3' , 9.3% by mass of 4,4'-diphenyl ether tetracarboxylic dianhydride was added and stirred at 20°C for 3 hours to obtain an aromatic polyamic acid solution. Subsequently, imidization was progressed by stirring at 200° C. for 3 hours, and the aromatic polyimide was purified by reprecipitation using water as a poor solvent. The Mw of the obtained aromatic polyimide was 56,000, and the copolymerization ratio of the fluorine-based aromatic monomer and the non-fluorine-based aromatic monomer was 55:45.
　次に、得られた芳香族ポリイミド２２質量％、ＧＭＯＭ２質量％、ＮＭＰ３８質量％、１，４－ジオキサン３８質量％を２５℃で溶解し、ポリマー溶液を調製した。このポリマー溶液を、ガラス板に２５℃で塗布し、３秒後、２５℃の蒸留水からなる凝固浴に３０秒浸漬して凝固させ、乾燥させることで、多孔質膜を得た。 Next, 22% by mass of the obtained aromatic polyimide, 2% by mass of GMOM, 38% by mass of NMP, and 38% by mass of 1,4-dioxane were dissolved at 25° C. to prepare a polymer solution. This polymer solution was applied to a glass plate at 25° C., and after 3 seconds, it was immersed in a coagulation bath of distilled water at 25° C. for 30 seconds to coagulate and dry, thereby obtaining a porous membrane.
　続いて、得られた多孔質膜を２００℃で２時間加熱することで、芳香族ポリイミドを架橋させた。得られた架橋ポリマーのイミド化度は０．５８であった。得られた多孔質膜の厚みは４６μｍであった。得られた多孔質膜を評価した結果を、表１に示す。 Subsequently, the obtained porous membrane was heated at 200° C. for 2 hours to crosslink the aromatic polyimide. The degree of imidization of the obtained crosslinked polymer was 0.58. The thickness of the obtained porous membrane was 46 μm. Table 1 shows the results of evaluating the obtained porous membrane.
（実施例７）
　実施例３で得たれた芳香族ポリイミド２０質量％、ＧＭＯＭ２質量％、ＮＭＰ５４質量％、１，４－ジオキサン２４質量％を２５℃で溶解し、ポリマー溶液を調製した。このポリマー溶液を、通気度０．６ｃｍ３／ｃｍ２／ｓのＰＰＳ短繊維不織布に２５℃で塗布し、３秒後、２５℃の蒸留水からなる凝固浴に３０秒浸漬して凝固させ、乾燥させることで、複合膜を得た。 (Example 7)
20% by mass of the aromatic polyimide obtained in Example 3, 2% by mass of GMOM, 54% by mass of NMP, and 24% by mass of 1,4-dioxane were dissolved at 25° C. to prepare a polymer solution. This polymer solution was applied to a PPS short fiber nonwoven fabric with an air permeability of 0.6 cm 3 /cm 2 /s at 25°C, and after 3 seconds, it was immersed in a coagulation bath consisting of distilled water at 25°C for 30 seconds to coagulate. A composite membrane was obtained by drying.
　続いて、得られた複合膜を２００℃で２時間加熱することで、芳香族ポリイミドを架橋させた。得られた架橋ポリマーのイミド化度は０．５４であった。得られた複合膜の厚みは１６５μｍであった。得られた複合膜を評価した結果を、表１に示す。 Subsequently, the resulting composite membrane was heated at 200°C for 2 hours to crosslink the aromatic polyimide. The degree of imidization of the obtained crosslinked polymer was 0.54. The thickness of the obtained composite membrane was 165 μm. Table 1 shows the results of evaluating the obtained composite membrane.
　（比較例１）
　実施例１で得た芳香族ポリイミド２２質量％、ＮＭＰ３９質量％、１，４－ジオキサン３９質量％を２５℃で溶解し、ポリマー溶液を調製した。その後、実施例１と同様の工程で多孔質膜を得たが、多孔質膜をＮＭＰ中に浸漬させたところ溶解したため、有機溶媒を含有する被処理液に対する分離膜として使用できなかった。 (Comparative example 1)
22% by mass of the aromatic polyimide obtained in Example 1, 39% by mass of NMP, and 39% by mass of 1,4-dioxane were dissolved at 25° C. to prepare a polymer solution. Thereafter, a porous membrane was obtained in the same process as in Example 1, but when the porous membrane was immersed in NMP, it dissolved, so it could not be used as a separation membrane for a liquid to be treated containing an organic solvent.
　（比較例２）
　加熱前まで実施例２と同様にして複合膜を得た。得られた複合膜を８０℃で２時間加熱したが、複合膜をＮＭＰ中に浸漬させたところ多孔質膜が溶解したため、有機溶媒を含有する被処理液に対する分離膜として使用できなかった。 (Comparative example 2)
A composite membrane was obtained in the same manner as in Example 2 until heating. The obtained composite membrane was heated at 80° C. for 2 hours, but when the composite membrane was immersed in NMP, the porous membrane dissolved, so it could not be used as a separation membrane for a liquid to be treated containing an organic solvent.
　（比較例３）
　４，４’－ジヒドロキシ－３，３’－ジアミノフェニルヘキサフルオロプロパン９．７質量％、ＮＭＰ８２質量％を２０℃で溶解し、３，３’，４，４’－ジフェニルエーテルテトラカルボン酸二無水物８．３質量％を添加し、２０℃で３時間攪拌することで、芳香族ポリアミック酸溶液を得た。続いて、２００℃で３時間攪拌することでイミド化を進行させ、水を貧溶媒とした再沈殿法により芳香族ポリイミドを精製した。得られた芳香族ポリイミドのＭｗは７２，０００であった。 (Comparative example 3)
9.7% by mass of 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane and 82% by mass of NMP were dissolved at 20°C to form 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride. An aromatic polyamic acid solution was obtained by adding 8.3% by mass and stirring at 20° C. for 3 hours. Subsequently, imidization was progressed by stirring at 200° C. for 3 hours, and the aromatic polyimide was purified by reprecipitation using water as a poor solvent. The Mw of the obtained aromatic polyimide was 72,000.
　次に、得られた芳香族ポリイミド２２質量％、ＧＭＯＭ２質量％、ＮＭＰ３８質量％、１，４－ジオキサン３８質量％を２５℃で溶解し、ポリマー溶液を調製した。このポリマー溶液を、ガラス板に２５℃で塗布し、３秒後、２５℃の蒸留水からなる凝固浴に３０秒浸漬して凝固させ、乾燥させたところ、多孔質膜にひび割れが発生したため、分離膜として使用できなかった。 Next, 22% by mass of the obtained aromatic polyimide, 2% by mass of GMOM, 38% by mass of NMP, and 38% by mass of 1,4-dioxane were dissolved at 25° C. to prepare a polymer solution. This polymer solution was applied to a glass plate at 25°C, and after 3 seconds, it was immersed in a coagulation bath consisting of distilled water at 25°C for 30 seconds to solidify and dry. When the porous membrane cracked, It could not be used as a separation membrane.
　（比較例４）
　４，４’－ジアミノジフェニルエーテル７．１質量％、ＮＭＰ８２質量％を２０℃で溶解し、３，３’，４，４’－ジフェニルエーテルテトラカルボン酸二無水物１０．９質量％を添加し、２０℃で３時間攪拌することで、芳香族ポリアミック酸溶液を得た。続いて、２００℃で３時間攪拌することでイミド化を進行させたところ、芳香族ポリイミドが析出した。得られた芳香族ポリイミドは有機溶媒への溶解性を示さなかったため、ポリマー溶液を用いた多孔質膜及び複合膜の製膜ができなかった。 (Comparative example 4)
7.1% by mass of 4,4'-diaminodiphenyl ether and 82% by mass of NMP were dissolved at 20°C, 10.9% by mass of 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride was added, and 20% by mass of NMP was dissolved. By stirring at ℃ for 3 hours, an aromatic polyamic acid solution was obtained. Subsequently, imidization was advanced by stirring at 200° C. for 3 hours, and aromatic polyimide was precipitated. Since the obtained aromatic polyimide did not exhibit solubility in organic solvents, it was not possible to form porous membranes and composite membranes using polymer solutions.
（比較例５）
　４，４’－ジヒドロキシ－３，３’－ジアミノフェニルヘキサフルオロプロパン７．５質量％、４，４’－ジアミノジフェニルエーテル１．６質量％、ＮＭＰ８２質量％を２０℃で溶解し、３，３’，４，４’－ジフェニルエーテルテトラカルボン酸二無水物８．９質量％を添加し、２０℃で３時間攪拌することで、芳香族ポリアミック酸溶液を得た。続いて、２００℃で３時間攪拌することでイミド化を進行させ、水を貧溶媒とした再沈殿法により芳香族ポリイミドを精製した。得られた芳香族ポリイミドのＭｗは５５，０００であり、フッ素系芳香族モノマーと、非フッ素系芳香族モノマーとの共重合比は、７２：２８であった。 (Comparative example 5)
7.5% by mass of 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane, 1.6% by mass of 4,4'-diaminodiphenyl ether, and 82% by mass of NMP were dissolved at 20°C, and 3,3' , 8.9% by mass of 4,4'-diphenyl ether tetracarboxylic dianhydride was added and stirred at 20°C for 3 hours to obtain an aromatic polyamic acid solution. Subsequently, imidization was progressed by stirring at 200° C. for 3 hours, and the aromatic polyimide was purified by reprecipitation using water as a poor solvent. The Mw of the obtained aromatic polyimide was 55,000, and the copolymerization ratio of the fluorine-based aromatic monomer and the non-fluorine-based aromatic monomer was 72:28.
　次に、得られた芳香族ポリイミド２２質量％、ＧＭＯＭ２質量％、ＮＭＰ３８質量％、１，４－ジオキサン３８質量％を２５℃で溶解し、ポリマー溶液を調製した。このポリマー溶液を、ガラス板に２５℃で塗布し、３秒後、２５℃の蒸留水からなる凝固浴に３０秒浸漬して凝固させ、乾燥させることで、多孔質膜を得た。 Next, 22% by mass of the obtained aromatic polyimide, 2% by mass of GMOM, 38% by mass of NMP, and 38% by mass of 1,4-dioxane were dissolved at 25° C. to prepare a polymer solution. This polymer solution was applied to a glass plate at 25° C., and after 3 seconds, it was immersed in a coagulation bath of distilled water at 25° C. for 30 seconds to coagulate and dry, thereby obtaining a porous membrane.
　続いて、得られた多孔質膜を２００℃で２時間加熱することで、芳香族ポリイミドを架橋させた。得られた架橋ポリマーのイミド化度は０．５６であった。得られた多孔質膜の厚みは４０μｍであった。得られた多孔質膜を評価した結果を、表１に示す。得られた多孔質膜は、実施例の多孔質膜に比べて力学物性が低い結果であった。 Subsequently, the obtained porous membrane was heated at 200° C. for 2 hours to crosslink the aromatic polyimide. The degree of imidization of the obtained crosslinked polymer was 0.56. The thickness of the obtained porous membrane was 40 μm. Table 1 shows the results of evaluating the obtained porous membrane. The obtained porous membrane had lower mechanical properties than the porous membrane of the example.
（比較例６）
　４，４’－ジヒドロキシ－３，３’－ジアミノフェニルヘキサフルオロプロパン２．４質量％、４，４’－ジアミノジフェニルエーテル５．３質量％、ＮＭＰ８２質量％を２０℃で溶解し、３，３’，４，４’－ジフェニルエーテルテトラカルボン酸二無水物１０．３質量％を添加し、２０℃で３時間攪拌することで、芳香族ポリアミック酸溶液を得た。続いて、２００℃で３時間攪拌することでイミド化を進行させたところ、芳香族ポリイミドが析出した。得られた芳香族ポリイミドは有機溶媒への溶解性を示さなかったため、ポリマー溶液を用いた多孔質膜及び複合膜の製膜ができなかった。 (Comparative example 6)
2.4% by mass of 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane, 5.3% by mass of 4,4'-diaminodiphenyl ether, and 82% by mass of NMP were dissolved at 20°C, and 3,3' , 10.3% by mass of 4,4'-diphenyl ether tetracarboxylic dianhydride was added and stirred at 20°C for 3 hours to obtain an aromatic polyamic acid solution. Subsequently, imidization was advanced by stirring at 200° C. for 3 hours, and aromatic polyimide was precipitated. Since the obtained aromatic polyimide did not exhibit solubility in organic solvents, it was not possible to form porous membranes and composite membranes using polymer solutions.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　本発明を特定の態様を参照して詳細に説明したが、本発明の精神と範囲を離れることなく様々な変更および修正が可能であることは、当業者にとって明らかである。なお、本出願は、２０２２年９月９日付けで出願された日本特許出願（特願２０２２－１４４１９４）に基づいており、その全体が引用により援用される。また、ここに引用されるすべての参照は全体として取り込まれる。 Although the invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application (Japanese Patent Application No. 2022-144194) filed on September 9, 2022, and is incorporated by reference in its entirety. Additionally, all references cited herein are incorporated in their entirety.
　本発明によれば、製膜性が向上することで、有機溶媒を含有する被処理液、及び高温の被処理液に対して、継続的に安定して分離性能と透過性能とを維持可能な、多孔質膜及び複合膜を提供することができる。 According to the present invention, by improving film formability, it is possible to continuously and stably maintain separation performance and permeation performance for liquids to be treated containing organic solvents and liquids to be treated at high temperatures. , porous membranes and composite membranes.

Claims (15)

  1. 　芳香族ポリマー同士が架橋された架橋ポリマーを含有し、
    　前記芳香族ポリマーが、少なくとも、フッ素原子を含有する芳香族ジアミンモノマー及びフッ素原子を含有する芳香族ジイソシアネートモノマーからなる群から選択される少なくとも１つのフッ素系芳香族モノマーと、フッ素原子を含有しない芳香族ジアミンモノマー及びフッ素原子を含有しない芳香族ジイソシアネートモノマーからなる群から選択される少なくとも１つの非フッ素系芳香族モノマーと、酸無水物モノマーと、を共重合させてなるポリマーであり、
    　前記芳香族ポリマーにおける、前記フッ素系芳香族モノマーと前記非フッ素系芳香族モノマーとの共重合比が、モル比で、２５：７５～７０：３０の範囲である、多孔質膜。     Contains a crosslinked polymer in which aromatic polymers are crosslinked,
    The aromatic polymer contains at least one fluorine-based aromatic monomer selected from the group consisting of an aromatic diamine monomer containing a fluorine atom and an aromatic diisocyanate monomer containing a fluorine atom, and an aromatic compound containing no fluorine atom. A polymer obtained by copolymerizing at least one non-fluorine-based aromatic monomer selected from the group consisting of diamine monomers and aromatic diisocyanate monomers containing no fluorine atoms, and an acid anhydride monomer,
    A porous membrane, wherein a copolymerization ratio of the fluorinated aromatic monomer and the non-fluorinated aromatic monomer in the aromatic polymer is in the range of 25:75 to 70:30 in molar ratio.
  2. 　前記フッ素系芳香族モノマーと前記非フッ素系芳香族モノマーとの共重合比が、モル比で、２５：７５～５０：５０の範囲である、請求項１記載の多孔質膜。 The porous membrane according to claim 1, wherein the copolymerization ratio of the fluorinated aromatic monomer and the non-fluorinated aromatic monomer is in the range of 25:75 to 50:50 in molar ratio.
  3. 　前記芳香族ポリマーが、芳香族ポリイミドを含有する、請求項１または２記載の多孔質膜。 The porous membrane according to claim 1 or 2, wherein the aromatic polymer contains aromatic polyimide.
  4. 　前記架橋ポリマーのイミド化度が０．２～１．２である、請求項３記載の多孔質膜。 The porous membrane according to claim 3, wherein the degree of imidization of the crosslinked polymer is 0.2 to 1.2.
  5. 　前記架橋ポリマーが、エポキシ系架橋剤、メチロール系架橋剤、アルコキシメチル系架橋剤、及びジアミン系架橋剤からなる群から選択される少なくとも１つの架橋剤により、前記芳香族ポリマー同士が架橋されたポリマーである、請求項１または２記載の多孔質膜。 The crosslinked polymer is a polymer in which the aromatic polymers are crosslinked with at least one crosslinking agent selected from the group consisting of an epoxy crosslinking agent, a methylol crosslinking agent, an alkoxymethyl crosslinking agent, and a diamine crosslinking agent. The porous membrane according to claim 1 or 2.
  6. 　前記多孔質膜が、少なくとも緻密層と粗大層の２層を有する、請求項１または２記載の多孔質膜。 The porous membrane according to claim 1 or 2, wherein the porous membrane has at least two layers: a dense layer and a coarse layer.
  7. 　前記多孔質膜の断面に占めるマクロボイドの面積割合が３～６０％である、請求項１または２に記載の多孔質膜。 The porous membrane according to claim 1 or 2, wherein the area ratio of macrovoids in the cross section of the porous membrane is 3 to 60%.
  8. 　前記マクロボイドが膜の厚み方向に長軸を有し、且つ、アスペクト比が２．０以上である、請求項７に記載の多孔質膜。 The porous membrane according to claim 7, wherein the macrovoid has a long axis in the thickness direction of the membrane and has an aspect ratio of 2.0 or more.
  9. 　請求項１または２記載の多孔質膜が、基材の少なくとも一方の面側に積層された複合膜。 A composite membrane in which the porous membrane according to claim 1 or 2 is laminated on at least one side of a base material.
  10. 　前記基材が、ポリフェニレンスルファイドを主成分とする、請求項９記載の複合膜。 The composite membrane according to claim 9, wherein the base material contains polyphenylene sulfide as a main component.
  11. 　請求項１または２記載の多孔質膜を備えるモジュール。 A module comprising the porous membrane according to claim 1 or 2.
  12. 　請求項９に記載の複合膜を備えるモジュール。 A module comprising the composite membrane according to claim 9.
  13. 　請求項１２に記載のモジュールを備える流体分離装置。 A fluid separation device comprising the module according to claim 12.
  14. 　下記（ｉ）及び（ｉｉ）の工程を含む、多孔質膜を製造する方法。
    （ｉ）少なくとも、フッ素原子を含有する芳香族ジアミンモノマー及びフッ素原子を含有する芳香族ジイソシアネートモノマーからなる群から選択される少なくとも１つのフッ素系芳香族モノマーと、フッ素原子を含有しない芳香族ジアミンモノマー及びフッ素原子を含有しない芳香族ジイソシアネートモノマーからなる群から選択される少なくとも１つの非フッ素系芳香族モノマーと、酸無水物モノマーと、を共重合して芳香族ポリマーを得ること。
    （ｉｉ）架橋剤によって上記（ｉ）で得られた芳香族ポリマーを架橋すること。     A method for manufacturing a porous membrane, including the steps (i) and (ii) below.
    (i) At least one fluorine-based aromatic monomer selected from the group consisting of an aromatic diamine monomer containing a fluorine atom and an aromatic diisocyanate monomer containing a fluorine atom, and an aromatic diamine monomer containing no fluorine atom. and at least one non-fluorine-based aromatic monomer selected from the group consisting of aromatic diisocyanate monomers containing no fluorine atoms, and an acid anhydride monomer to obtain an aromatic polymer.
    (ii) Crosslinking the aromatic polymer obtained in (i) above with a crosslinking agent.
  15. 　前記架橋剤が、エポキシ系架橋剤、メチロール系架橋剤、アルコキシメチル系架橋剤、及びジアミン系架橋剤からなる群から選択される少なくとも一つの架橋剤である、請求項１４に記載の多孔質膜を製造する方法。 The porous membrane according to claim 14, wherein the crosslinking agent is at least one crosslinking agent selected from the group consisting of an epoxy crosslinking agent, a methylol crosslinking agent, an alkoxymethyl crosslinking agent, and a diamine crosslinking agent. How to manufacture.
PCT/JP2023/032587 2022-09-09 2023-09-06 Porous film and composite film WO2024053690A1 (en)

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JPS55162311A (en) * 1979-06-04 1980-12-17 Nitto Electric Ind Co Ltd Manufacture of selective permeable membrane
JP2016081835A (en) * 2014-10-21 2016-05-16 東京応化工業株式会社 Porous film, method for manufacturing the same, porous separator for secondary battery, and secondary battery
JP2017068262A (en) * 2015-09-30 2017-04-06 東京応化工業株式会社 Production method for purified liquid chemical product for lithography, and method for forming resist pattern
CN110028670A (en) * 2019-04-11 2019-07-19 明士新材料有限公司 Low-dielectric loss negative light-sensitive poly amic acid ester resin, resin combination, preparation method and application
WO2021132399A1 (en) * 2019-12-23 2021-07-01 東レ株式会社 Separation membrane and method for producing separation membrane
JP2022098454A (en) * 2020-12-21 2022-07-01 東レ株式会社 Fluid separation membrane module, fluid separation membrane plant and purified fluid

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS55162311A (en) * 1979-06-04 1980-12-17 Nitto Electric Ind Co Ltd Manufacture of selective permeable membrane
JP2016081835A (en) * 2014-10-21 2016-05-16 東京応化工業株式会社 Porous film, method for manufacturing the same, porous separator for secondary battery, and secondary battery
JP2017068262A (en) * 2015-09-30 2017-04-06 東京応化工業株式会社 Production method for purified liquid chemical product for lithography, and method for forming resist pattern
CN110028670A (en) * 2019-04-11 2019-07-19 明士新材料有限公司 Low-dielectric loss negative light-sensitive poly amic acid ester resin, resin combination, preparation method and application
WO2021132399A1 (en) * 2019-12-23 2021-07-01 東レ株式会社 Separation membrane and method for producing separation membrane
JP2022098454A (en) * 2020-12-21 2022-07-01 東レ株式会社 Fluid separation membrane module, fluid separation membrane plant and purified fluid

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