WO2024053691A1 - Film poreux et film composite - Google Patents

Film poreux et film composite Download PDF

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WO2024053691A1
WO2024053691A1 PCT/JP2023/032588 JP2023032588W WO2024053691A1 WO 2024053691 A1 WO2024053691 A1 WO 2024053691A1 JP 2023032588 W JP2023032588 W JP 2023032588W WO 2024053691 A1 WO2024053691 A1 WO 2024053691A1
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porous membrane
group
membrane
polymer
acid
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PCT/JP2023/032588
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English (en)
Japanese (ja)
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竣介 水野
貴亮 安田
貴史 小川
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東レ株式会社
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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
    • B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • 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
    • 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

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
  • OSU organic solvent ultrafiltration
  • Koch's SelRO membrane is manufactured using polydimethylsiloxane (hereinafter referred to as ⁇ PDMS'') and polyacrylonitrile (hereinafter referred to as ⁇ PAN'') as raw materials. It enables membrane separation in polar solvents such as hydrocarbons such as tetrohydrofuran, ethyl acetate, and acetonitrile.
  • polar solvents such as hydrocarbons such as tetrohydrofuran, ethyl acetate, and acetonitrile.
  • Other solvent-resistant separation membranes made of PDMS and PAN include AMS's Nanopro membrane and Ultrapro membrane.
  • solvent-resistant films made mainly of polymers include polyimide films, polyamide-imide films, polyetherimide films, and the like.
  • phase separation methods are a method in which a polymer is intentionally changed from a solution state to a solid state.
  • a non-solvent organic phase separation method in which a polymer solution comes into contact with a liquid that is a poor solvent for the polymer, mixes and precipitates
  • TIPS non-solvent organic phase separation method
  • phase inversion processes and the polymer forms a membrane with a porous structure.
  • Such a porous structure is permeable to liquids and gases. Separation membranes can separate and purify impurities in liquids and gases by utilizing differences in pore size and dissolution/diffusivity of gases.
  • polymer membranes It is common for these polymer membranes to be crosslinked in order to acquire organic solvent resistance. Since the above-mentioned imide group-containing polymers have the property of being stable against chemicals and heat, their crosslinking is mainly carried out using a polyvalent amine compound as typified by Patent Document 1.
  • the polymer is crosslinked by cleaving the imide group with a polyvalent amine compound and forming a covalent bond, resulting in a stable film even in a polar solvent, which is a good solvent.
  • Patent Document 2 discloses a method of ensuring stability by capping reactive terminal functional groups.
  • a polyimide film crosslinked using a polyamine is treated with an acid halide compound or an acid anhydride to convert amino groups into functional groups with low reactivity, such as beta-propiolactone (hereinafter referred to as ""
  • EO ethylene oxide
  • CO carbon monoxide
  • BPL BPL
  • Non-Patent Document 1 As a crosslinking method using other than a polyvalent amine compound, a method using a coordination crosslinking reaction between a carboxy group and a metal ion, as listed in Non-Patent Document 1, has been reported in recent years. This method prevents structural changes in the main chain structure of polyimide due to ring opening of imide bonds and maintains permeability and mechanical properties, thereby achieving the production of a separation membrane for OSNs with high performance. .
  • Examples of methods for crosslinking a polymer membrane made of a polymer containing imide groups derived from phenol groups include methods using UV crosslinking and thermal crosslinking as listed in Patent Document 3.
  • a soluble polyimide is synthesized using a phenol group-containing diamine monomer, and a polyimide solution prepared is applied to a certain thickness and then dried to obtain a polyimide film.
  • intermolecular crosslinking is achieved by UV crosslinking using a UV lamp with a wavelength of 254 nm and thermal crosslinking at a high temperature of about 450°C.
  • Crosslinking using a polyvalent amine compound as typified by Patent Document 1 leaves reactive functional groups such as amino groups in the membrane, so there is concern that problems may arise in some applications and processes in organic solvent separation. .
  • reactive functional groups such as amino groups in the membrane
  • problems may arise in some applications and processes in organic solvent separation.
  • a catalyst consisting of a metal complex is present as a valuable substance in the liquid to be treated, interaction with a reactive functional group occurs.
  • the liquid to be treated contains other electrophilic substances that react with nucleophilic functional groups, they may be deposited on the membrane surface by interaction with the membrane or retained within the membrane. There is a concern that separation efficiency and separation performance may deteriorate.
  • the polymer membrane disclosed in Patent Document 3 is not a composite membrane integrated with a base material such as a nonwoven fabric.
  • a porous membrane such as a nonwoven fabric
  • porous films Most polymer films with solvent resistance are porous films, and the porous structure has domains in the film with a size that scatters light.
  • the membrane produced by the method shown in Patent Document 3 is presumed to have a film shape because it is not produced through phase separation. It is presumed that crosslinking by UV light proceeds only on the surface of these porous membranes. A porous membrane that is crosslinked only on its surface may swell and dissolve in areas where crosslinking has not progressed sufficiently when an organic solvent passes through the membrane, and it may not function as a separation membrane.
  • an object of the present invention is to provide a porous membrane and a composite membrane that are used for selective separation of liquid mixtures and have particularly excellent solvent resistance.
  • the present inventors have found that the degree of swelling in an organic solvent can be adjusted by allowing a porous membrane to contain an aromatic polymer that has units with a specific structure and a crosslinked structure that connects the units.
  • the present inventors have discovered that a porous membrane and a composite membrane with solvent resistance can be obtained, and have completed the present invention.
  • the present embodiment is characterized by the following (1) to (8).
  • (1) Between a plurality of units represented by the following formula (1) forming the main chain of the polymer and any two or more of the units through at least one of R 1 to R 10 in the units.
  • R 1 to R 10 may be the same or different, and include a hydrocarbon group having 1 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, and a fluoroalkyl group having 1 to 30 carbon atoms. , an imide group, an amide group, a hydroxy group, a hydrogen atom, a halogen atom, a carboxy group, a carboxylic acid ester group, a phenyl group, a sulfone group, a nitro group, a cyano group, and a group that binds to the crosslinked structure.
  • At least one of R 1 to R 5 and at least one of R 6 to R 10 is an imide group or amide group forming the main chain of the aromatic polymer.
  • At least one of ⁇ R 10 is a hydroxy group, and a hydrogen atom is bonded to at least one carbon atom adjacent to the carbon atom to which the hydroxy group is bonded.
  • the crosslinked structure is at least one structure selected from the group consisting of the following formulas (3-1) to (3-3),
  • P, Q, and R represent crosslinking agent residues.
  • the macrovoid has a long axis in the thickness direction of the membrane and has an aspect ratio of 2.0 or more.
  • crosslinking agent is at least one crosslinking agent selected from the group consisting of an epoxy crosslinking agent, a methylol crosslinking agent, and a polycarboxylic acid crosslinking agent. manufacturing method.
  • FIG. 1 shows an electron microscope image of a composite membrane containing a dense layer, a coarse layer, and a nonwoven fabric.
  • ⁇ 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 and composite membrane (1-1)
  • the porous membrane described below includes a plurality of units represented by the following formula (1) forming the main chain of a polymer, and R 1 to N-methyl-2-pyrrolidone (hereinafter referred to as "NMP"), which contains an aromatic polymer having a crosslinked structure that connects any two or more of the units through at least one of R10 . It exhibits a degree of swelling of 100-200% in the medium.
  • NMP N-methyl-2-pyrrolidone
  • R 1 to R 10 may be the same or different, and include a hydrocarbon group having 1 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, a fluoroalkyl group having 1 to 30 carbon atoms, A group selected from the group consisting of an imide group, an amide group, a hydroxy group, a hydrogen atom, a halogen atom, a carboxy group, a carboxylic acid ester group, a phenyl group, a sulfone group, a nitro group, a cyano group, and a group that binds to the crosslinked structure. shows.
  • At least one of R 1 to R 5 and at least one of R 6 to R 10 are imide groups or amide groups forming the main chain of the aromatic polymer. Furthermore, at least one of R 1 to R 10 is a hydroxy group, and a hydrogen atom is bonded to at least one of the carbon atoms adjacent to the carbon atom to which the hydroxy group is bonded.
  • X represents a direct bond or a bond structure selected from the group consisting of the following formulas (2-1) to (2-11). * in formulas (2-1) to (2-11) is a bond with two aromatic rings within the unit.
  • the porous membrane of this embodiment contains the crosslinked aromatic polymer as described above to form a three-dimensional network structure, so it becomes stable even in NMP and maintains separation performance. Moreover, it is presumed that the porous membrane of this embodiment functions as a membrane having high permeability and high removability due to the above swelling degree. When the above degree of swelling is satisfied in NMP, it is assumed that the separation performance is similarly maintained in other organic solvents, and that the material has high water permeability and high removability.
  • Aromatic polymer The porous membrane of this embodiment includes a plurality of units represented by the above formula (1) forming the main chain of the polymer, and among R 1 to R 10 in the units. an aromatic polymer having a crosslinked structure that connects any two or more of the units through at least one of the following.
  • R 1 and R 6 may be the same or different; from the viewpoint of monomer productivity, R 1 and R 6 are hydrocarbon groups having 1 to 30 carbon atoms; A group selected from the group consisting of an alkoxy group, a fluoroalkyl group having 1 to 30 carbon atoms, a hydrogen atom, a halogen atom, a carboxy group, a carboxylic acid ester group, a phenyl group, a sulfone group, a nitro group, and a cyano group is preferred; Atoms are particularly preferred.
  • R 2 and R 10 may be the same or different, and from the viewpoint of monomer productivity and steric hindrance, R 2 and R 10 are an imide group forming the main chain of the aromatic polymer or An amide group is preferred, and an imide group is particularly preferred.
  • R 3 and R 9 may be the same or different, and from the viewpoint of monomer productivity, R 3 and R 9 are preferably hydroxy groups.
  • R 4 and R 8 may be the same or different, and from the viewpoint of forming a crosslinked structure, R 4 and R 8 are preferably groups that bond to the crosslinked structure.
  • R 5 and R 7 may be the same or different, and from the viewpoint of monomer productivity and steric hindrance, R 5 and R 7 are preferably hydrogen atoms.
  • X in the above formula (1) is a bond selected from the group consisting of (2-1), (2-2), (2-3) and (2-5) from the viewpoint of solubility of the aromatic polymer. structure is preferred, and the bond structure (2-2) is particularly preferred.
  • Examples of the unit represented by the above formula (1) include 3,3'-dihydroxybenzidine, 4,4'-dihydroxy-3,3'-diaminophenylpropane, 4,4'-dihydroxy-3,3' -diaminophenylhexafluoropropane, 4,4'-dihydroxy-3,3'-diaminophenyl sulfone, 4,4'-dihydroxy-3,3'-diaminophenyl ether, 4,4'-dihydroxy-3,3' Examples include units derived from -diaminophenylpropanemethane, 4,4'-dihydroxy-3,3'-diaminobenzophenone, 9,9-bis(3-amino-4-hydroxyphenyl)fluorene, and the like.
  • 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane or 4,4'-dihydroxy-3,3'-diaminophenyl sulfone is preferred.
  • it is a unit derived from
  • the crosslinked structure connects one unit to at least one other unit represented by the above formula (1) via at least one of R 1 to R 10 in the unit. .
  • R 1 to R 10 in the unit.
  • the crosslinked structure between the units represented by the above formula (1) is preferably at least one structure selected from the group consisting of the following formulas (3-1) to (3-3).
  • the aromatic rings at both ends of the structure shown in the following formulas (3-1) to (3-3) are aromatic rings in the unit represented by the above formula (1).
  • P, Q and R are crosslinking agent residues, for example, direct bonds, hydrocarbon groups having 1 to 30 carbon atoms, or hydrocarbon groups having 1 to 30 carbon atoms.
  • Preferred examples include an alkoxy group having 30 carbon atoms, a fluoroalkyl group having 1 to 30 carbon atoms, a halogen atom, a carboxylic acid ester group, a phenyl group, a sulfonyl group, and an amino group.
  • the crosslinking agent residue is derived from the crosslinking agent described below, and means a portion excluding the bonding portion between the crosslinking agent and the unit.
  • the structure represented by the formula (3-1) or the formula (3-2) is preferable, and the structure represented by the formula The structure represented by (3-1) is more preferred.
  • P is preferably a hydrocarbon group having 1 to 30 carbon atoms including a benzyl group
  • Q is a hydrocarbon group having 1 to 30 carbon atoms.
  • R is preferably a hydrocarbon group having 1 to 30 carbon atoms.
  • formulas (3-1) to (3-3) include structures in which P is a benzyl group, Q is a carbon atom, and R is a carbon atom.
  • the above aromatic polymer may have a unit derived from a diamine compound other than the unit represented by the above formula (1).
  • units derived from such diamine compounds include p-phenylenediamine, m-phenylenediamine, 2,5-diaminotoluene, 2,4-diaminotoluene, 3,5-diaminobenzoic acid, and 2,6-diaminotoluene.
  • Diaminobenzoic acid 2-methoxy-1,4-phenylenediamine, 4,4'-diaminobenzanilide, 3,4'-diaminobenzanilide, 3,3'-diaminobenzanilide, 3,3'-dimethyl-4 , 4'-diaminobenzanilide, 2,5-diaminophenol, 3,5-diaminophenol, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4' - Diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminobenzophen
  • the molar ratio between the content of units derived from a diamine compound other than the units represented by formula (1) and the content of units represented by formula (1) in the aromatic polymer is such that post-crosslinking is possible.
  • the ratio is preferably 90:10 to 0:100 based on the amount of units.
  • the aromatic polymer may have a unit derived from an acid dianhydride.
  • units derived from such acid dianhydrides 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'-biphenyl Tetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, 2,3,3', 4'-diphenyl ether tetracarboxylic dianhydride, 2,2',3,3'-diphenyl ether tetrac
  • the molar ratio between the content of units derived from acid dianhydride and the content of units represented by formula (1) is 45:55 from the viewpoint of the molecular weight of the resulting aromatic polymer. ⁇ 55:45 is preferred.
  • the aromatic polymer may have a unit derived from a polyfunctional acid halide.
  • units derived from polyfunctional acid halides include trimellitic acid chloride, pyromellitic acid chloride, isophthalic acid chloride, terephthalic acid chloride, trimesic acid chloride, 4,4'-oxybisbenzoyl chloride, 2,2- Examples include units derived from bis(4-chloroformyloxyphenyl)propane and the like.
  • the molar ratio of the unit represented by the above formula (1) and/or the unit derived from other diamine compounds to the unit derived from the acid dianhydride and/or the unit derived from the polyfunctional acid halide is as follows: The ratio is preferably 80:100 to 100:80.
  • the unit represented by the above formula (1) and/or a unit derived from another diamine compound, and the unit derived from an acid dianhydride and/or the unit derived from a polyfunctional acid halide are mixed in approximately equimolar amounts. By doing so, the molecular weight of the aromatic polymer can be increased. On the other hand, by biasing the molar ratio to one side, the molecular weight of the polymer can be reduced.
  • aromatic polymer having a unit represented by the above formula (1) examples include aromatic polyamic acid, aromatic polyamide, aromatic polyamideimide, aromatic polyimide, aromatic polyetherimide, aromatic polymaleimide, etc. Can be mentioned. From the viewpoint of heat resistance and versatility, the aromatic polymer is preferably an aromatic polyimide.
  • the weight average molecular weight (hereinafter referred to as "Mw") of the aromatic polyimide is preferably 8,000 to 200,000, and preferably 12,000 to 100,000. It is more preferable.
  • Mw of the aromatic polyimide is 8,000 or more, separation performance, mechanical strength, and heat resistance that are 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 moldability can be achieved.
  • the Mw of a 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 degree of imidization of the aromatic polyimide having a crosslinked structure is preferably 0.2 to 1.2, and 0. It is more preferably from .3 to 1.2, and even more preferably from 0.4 to 1.2.
  • a degree of imidization of the crosslinked polymer of 0.2 or more separation performance and permeation performance can be maintained stably and continuously for processing liquids containing organic solvents such as NMP and high temperature processing liquids. It is possible to obtain a porous membrane that can maintain the
  • the degree of imidization of aromatic polyimide can be measured using a Fourier transform infrared spectrophotometer.
  • the degree of imidization is calculated by dividing the peak intensity derived from the aromatic ring from the peak intensity derived from the imide group obtained by measuring the surface of the porous membrane using infrared total reflection absorption measurement (ATR method). It is a value.
  • 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.
  • a method for suppressing imidization there is a method such as adding water to polyamic acid.
  • the porous membrane may contain a polymer other than the aromatic polymer having the unit represented by the above formula (1) that forms the main chain of the polymer, as long as the effects of the present embodiment are not impaired.
  • the degree of swelling in NMP of the porous membrane of this embodiment is 100 to 200%, preferably 105 to 150%, and more preferably 110 to 130%.
  • the degree of swelling can be calculated by dividing the thickness of the porous membrane after reaching an equilibrium swelling state in NMP by the thickness of the porous membrane before being immersed in NMP.
  • the degree of swelling of the porous membrane can be controlled by the type and concentration of the crosslinking agent and the conditions of the crosslinking reaction.
  • the porous membrane by leaving the porous membrane in NMP for 24 hours or more, it enters an equilibrium swelling state.
  • the swelling degree is less than 100%, the affinity between the porous membrane and an organic solvent such as NMP is low, and the permeability tends to be low.
  • the degree of swelling exceeds 200%, the affinity with organic solvents such as NMP is too high and the driving pressure in membrane separation tends to be high, that is, the permeability tends to be low.
  • the organic solvent may be a good solvent for the aromatic polymer before crosslinking.
  • 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 of this embodiment can be appropriately selected depending on the application.
  • the average surface pore diameter of the porous membrane should be 0.25 to 0.8 nm. It is preferably 0.4 to 0.7 nm, more preferably 0.4 to 0.7 nm.
  • the average surface pore diameter of the porous membrane is preferably 0.7 to 4 nm, preferably 0.75 to 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 membrane permeation flux of organic solvents such as NMP through a porous membrane is 0.1 L/m 2 /h when the porous membrane or composite membrane is OSRO (molecular weight cut off less than 200). /bar or more is preferable.
  • 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 1.0 L/m 2 /h/bar or more. More preferably, it is 2.0 L/m 2 /h/bar or more.
  • the porous membrane or composite membrane is OSU (molecular weight cut off 1,000 or more), it is preferably 2.0 L/m 2 /h/bar or more, and 10.0 L/m 2 /h/bar or more. It is more preferable that there be.
  • Membrane permeation flux is determined by measuring the amount of permeated liquid (L) by dead-end filtration or cross-flow filtration, etc., and converting it into a value per unit membrane area (m 2 ), unit time (hour), and unit pressure (bar). It can be calculated by
  • the rejection rate of the porous membrane is preferably 90% or more from the viewpoint of industrial value. Sufficient solvent purification is possible when the rejection rate is 90% or more, and if the rejection rate is lower than 90%, further purification is required.
  • the rejection rate can be calculated by subtracting the value obtained by dividing the solute concentration (ppm) in the permeate by the solute concentration in the stock solution from 1 and then multiplying by 100.
  • 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 membrane exhibits sufficient mechanical properties against pressure and becomes a highly permeable membrane.
  • the upper limit of 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 the porous membrane is a method of adding additives to the membrane forming solution.
  • the porous membrane is a polyimide membrane
  • organic solvents in which polyimide is soluble include acetone, acetonitrile, dimethyl sulfoxide, dimethylacetamide, dimethylformamide, N-methylpyrrolidone, dichloromethane, and chloroform.
  • 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 such as NMP and liquids to be treated at high temperatures.
  • polysulfide 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 long fiber nonwoven fabric refers to a nonwoven fabric with an average fiber length of 300 mm or more 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 basis weight of the base material affects the separation performance and physical stability of the composite membrane.
  • the basis weight of the base material is preferably 70 to 200 g/m 2 , more preferably 90 to 160 g/m 2 , even more preferably 100 to 140 g/m 2 .
  • the basis weight of the base material is 70 g/m2 or more , defects due to bleed-through are 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 composite material with good separation performance. membrane can be obtained.
  • the basis weight of the base material is 200 g/ m2 or less, a portion of the polymer solution impregnates the base material, improving the adhesion between the porous membrane and the base material, resulting in good physical stability.
  • a composite membrane having the following properties can be obtained.
  • 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, resulting in good performance.
  • 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, so it will be good.
  • 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 preferred values of the membrane permeation flux and rejection rate in the composite membrane are the same as the preferred values in the porous membrane described above.
  • the method for producing porous membranes and composite membranes of this embodiment is not particularly limited as long as a 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). (i) Polymerizing an aromatic polymer having a unit represented by the above formula (1). (ii) Crosslinking the aromatic polymer obtained in (i) above with a crosslinking agent.
  • Examples of the compound having the structure represented by the above formula (1) include 3,3'-dihydroxybenzidine, 4,4'-dihydroxy-3,3'-diaminophenylpropane, 4,4'-dihydroxy-3 , 3'-diaminophenylhexafluoropropane, 4,4'-dihydroxy-3,3'-diaminophenyl sulfone, 4,4'-dihydroxy-3,3'-diaminophenyl ether, 4,4'-dihydroxy-3 , 3'-diaminophenylpropanemethane, 4,4'-dihydroxy-3,3'-diaminobenzophenone, 9,9-bis(3-amino-4-hydroxyphenyl)fluorene, and the like.
  • 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane or 4,4'-dihydroxy-3,3'-diaminophenyl sulfone is preferred from the viewpoint of solubility and polymer film-forming properties. It is preferable to use
  • diamines include, for example, p-phenylenediamine, m-phenylenediamine, 2,5-diaminotoluene, 2,4-diaminotoluene, 3,5-diaminobenzoic acid, 2,6-diaminobenzoic acid, 2- Methoxy-1,4-phenylenediamine, 4,4'-diaminobenzanilide, 3,4'-diaminobenzanilide, 3,3'-diaminobenzanilide, 3,3'-dimethyl-4,4'-diaminobenz Anilide, 2,5-diaminophenol, 3,5-diaminophenol, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3 , 3'-diamin
  • acid dianhydrides 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 ether tetracarboxylic dianhydride, 2,3,3',4'-diphenyl ether tetracarboxylic acid Dianhydride, 2,2',3,3'-diphenyl ethertetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarbox
  • polyfunctional acid halides examples include trimellitic acid chloride, pyromellitic acid chloride, isophthalic acid chloride, terephthalic acid chloride, trimesic acid chloride, 4,4'-oxybisbenzoyl chloride, 2,2-bis(4- Examples include chloroformyloxyphenyl)propane.
  • the molar ratio of the compound having the structure represented by the above formula (1) and/or other diamine to the acid dianhydride and/or polyfunctional acid halide should be 80:100 to 100:80. is preferred.
  • the molecular weight of the aromatic polymer can be reduced. can be increased.
  • the molecular weight of the polymer can be reduced.
  • a terminal capping agent may be added 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, mechanical strength, and heat resistance that are 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 moldability can be achieved.
  • the Mw of a 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 compound having the structure represented by formula (1) above and/or other diamine is dissolved in a solvent, an acid dianhydride and/or a polyfunctional acid halide is added thereto, and the mixture is heated at 0 to 100°C.
  • a polyamic acid solution is obtained by stirring for 10 minutes to 100 hours.
  • the temperature is raised to 120 to 300°C and stirred for 10 minutes to 100 hours to advance imidization and dissolve the polyimide solution. obtain.
  • 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.
  • 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.
  • 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.
  • a solid aromatic polymer having a unit represented by the above formula (1) can be obtained by drying a polymer whose purity has been increased by a reprecipitation method.
  • NIPS method non-solvent induced phase separation method
  • NIPS method thermally induced phase separation method
  • TIPS method thermally induced phase separation method
  • the polymer obtained in "(2-1) Polymerization of polymer” and a crosslinking agent are dissolved in a solvent to obtain a polymer solution.
  • the polymer solution may contain a polymer other than the aromatic polymer having the unit represented by the above formula (1) within a range that does not impair the effects of the present embodiment.
  • 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.
  • 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.
  • 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 polymer crosslinking agent needs to be dissolved in the polymer solution, and is preferably an epoxy crosslinking agent, a methylol crosslinking agent, or a polyhydric carboxylic acid crosslinking agent.
  • 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 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").
  • polyhydric carboxylic acid crosslinking agents examples include aconitic acid, adipic acid, aspartic acid, acetylene dicarboxylic acid, acetone dicarboxylic acid, azelaic acid, adamantane dicarboxylic acid, ⁇ -aminoadipic acid, and 2-amino-3-carboximucone.
  • 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 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.
  • 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, particularly NMP 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.
  • 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 the polymer solution impregnated into the base material can be adjusted as appropriate by adjusting the time from coating the polymer solution onto the base material to immersing it in a coagulation bath, the viscosity of the polymer solution, the basis weight of the base material, and the like.
  • 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 composite membrane having organic solvent resistance, particularly NMP 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 composite membrane having organic solvent resistance, particularly NMP 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 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 can be classified into flat plate type, spiral type, pleat 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.
  • Weight average molecular weight The weight average molecular weight (polystyrene equivalent) of the polymer was measured using gel permeation chromatography (manufactured by Tosoh Corporation; HLC-8022). The specific measurement conditions were as follows. Column: 2 TSK gel SuperHM-H (manufactured by Tosoh Corporation; 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°C
  • the degree of imidization of the crosslinked polymer was measured using a Fourier transform infrared spectrophotometer (manufactured by Shimadzu Corporation; IRTracer-100).
  • the porous membrane or composite membrane was cut into a size of 3 cm x 3 cm, and the porous membrane side was measured by infrared total reflection absorption measurement (ATR method) using Micrometer Vision (manufactured by S.T. Japan Co., Ltd.).
  • the surface was measured (incident angle: 48 degrees, prism: diamond, resolution: 4 cm -1 , number of integrations: 64 times), and the peak intensity C derived from the aromatic ring detected at 1490 to 1520 cm -1 , 1760 to 1790 cm -1
  • the degree of imidization was calculated from the peak intensity D derived from the imide group detected by the following formula II.
  • Imidization degree (%) D/C (Formula II)
  • 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 from 200 to 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 is a filtration method that suppresses the accumulation of impurities on the membrane surface by flowing the filtrate parallel to the membrane surface.
  • Membrane structure A porous membrane or composite membrane was cut into a size of 10 cm 2 , 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 was cut in a direction perpendicular to the surface of the porous membrane.
  • 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. Find the length and the length in the horizontal direction to the porous membrane surface, divide the length in the vertical direction to the porous membrane surface by the length in the horizontal direction to the porous membrane surface, 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.
  • Thickness of the membrane The thickness of the obtained porous membrane, porous membrane and composite membrane after reaching the equilibrium swelling state was measured using a dial thickness gauge (manufactured by Techlock Co., Ltd., constant pressure thickness measuring instrument PG-01A). This was done using Measurements were taken at 10 points evenly from both ends of the membrane, and the average value was taken as the thickness of the membrane.
  • Example 1 Porous membrane (without base material) Dissolve 9.2% by mass of 4,4'-dihydroxy-3,3'-diaminophenylhexafluoropropane, 0.18% by mass of 3-aminophenol, and 82% by mass of NMP, and dissolve 3,3',4,4'- 8.6% by weight of diphenyl ether tetracarboxylic dianhydride was added. By stirring at 20° C. for 3 hours, an aromatic polyamic acid solution was obtained. Subsequently, imidization was progressed by reacting at 200° C. for 3 hours, and the aromatic polyimide was purified by a reprecipitation method using water as a poor solvent.
  • the weight average molecular weight of the obtained aromatic polyimide was 31,000. 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 to coagulate and dry, thereby obtaining a porous membrane. Subsequently, the obtained porous membrane was heated at 200° C. for 2 hours to crosslink the aromatic polyimide. Thereafter, the porous membrane was immersed in NMP to bring it into an equilibrium swelling state. The thickness of the obtained porous membrane was about 50 ⁇ m. Table 1 shows the results of evaluating the obtained porous membrane.
  • Example 2 Composite membrane in which a porous membrane is laminated on a base material
  • the polymer solution obtained in Example 1 was applied at 25°C to a PPS short fiber nonwoven fabric with an air permeability of 0.6 cm 3 /cm 2 /s.
  • a composite membrane was obtained by immersing it in a coagulation bath consisting of distilled water at 25° C. for 30 seconds to coagulate it and drying it. Subsequently, the resulting composite membrane was heated at 200° C. for 2 hours to crosslink the aromatic polyimide. Thereafter, the composite membrane was immersed in NMP to bring it into an equilibrium swollen state. The thickness of the obtained composite membrane was 150 ⁇ m. Table 1 shows the results of evaluating the obtained composite membrane.
  • Example 4 Composite membrane (2) in which a porous membrane containing high molecular weight aromatic polyimide is laminated on a base material 22% by mass of the aromatic polyimide obtained in Example 3, 2% by mass of GMOM, 58% by mass of NMP, and 18% 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 composite membrane was immersed in NMP to bring it into an equilibrium swollen state.
  • the thickness of the obtained composite membrane was 165 ⁇ m. Table 1 shows the results of evaluating the obtained composite membrane. Compared to the membrane obtained in Example 3, the permeability was lower.
  • Comparative Example 1 Porous membrane manufactured without using a crosslinking agent 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 form a polymer solution. was prepared. Thereafter, a porous membrane was obtained in the same process as in Example 1, but because the porous membrane was dissolved when immersed in NMP, it could not be used as a separation membrane for a liquid to be treated containing NMP.
  • a polyimide film was produced based on the method described in Example 2 of Japanese Patent Publication No. 2012-521873.
  • 4.0 g of polyimide obtained based on the method described in Example 1 of the above-mentioned Japanese Patent Publication No. 2012-521873 was dissolved in a mixed solvent of 12.0 g of NMP and 12.0 g of 1,3-dioxolane, and a dope solution was prepared. I got it. After degassing the dope solution, it was coated on a glass plate to a thickness of 300 ⁇ m.
  • the membrane along with the glass plate was placed in a vacuum oven. The membrane was vacuum dried at 200° C. for 48 hours to completely remove the residual solvent and obtain a polymer membrane.
  • Example 4 Polymer membrane prepared by UV crosslinking and heat treatment according to a known method A polyimide membrane was produced based on the method described in Example 3 of Japanese Patent Publication No. 2012-521873. The obtained film was subjected to UV irradiation using UV light having a wavelength of 254 nm at 50° C. for an irradiation time of 20 minutes. The UV crosslinked membrane was heated from 50°C to 450°C at a heating rate of 3°C/min under a nitrogen atmosphere. The membrane was held at 450°C for 1 hour and then cooled to 50°C at a rate of 3°C/min in a nitrogen stream. A UV crosslinked and then heat treated-UV crosslinked membrane was obtained.
  • Composite membrane (3) in which a porous membrane containing high molecular weight aromatic polyimide is laminated on a base material 22% by mass of the aromatic polyimide obtained in Example 3, 0.2% by mass of GMOM, 38.9% by mass of NMP, and 38.9% 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 0.55.
  • the composite membrane was immersed in NMP to bring it into an equilibrium swollen state.
  • the thickness of the obtained composite membrane was 177 ⁇ m. Table 1 shows the results of evaluating the obtained composite membrane. Compared to the membrane obtained in Example 3, the swelling degree was higher and the permeability was lower.
  • Example 1 and the composite membranes of Examples 2 and 3 have solvent resistance and, as shown in Table 1, have high membrane permeation flux and high The inhibition rate was shown.
  • Example 4 had a lower transmittance than Example 3.
  • the porous membrane of Comparative Example 1 and the composite membrane of Comparative Example 2 dissolved when the membranes were immersed in NMP, and therefore could not be used as a separation membrane for a liquid to be treated containing NMP.
  • the polymer membranes of Comparative Examples 3 and 4 did not exhibit sufficient permeability to liquids for evaluating the separation efficiency of membrane separation.
  • the membrane of Comparative Example 5 had a high degree of swelling due to the low content of the crosslinking agent, and had a lower permeability than the membrane of Example 3.
  • the porous membrane and composite membrane of the present invention have a porous structure and exhibit high solvent resistance. Thereby, the porous membrane and composite membrane of the present invention can separate solutes and impurities in various organic solvents with high efficiency. Furthermore, the porous membrane and composite membrane of the present invention can be used in various applications such as gas separation, water treatment, and battery separators.

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Abstract

Un film poreux selon la présente invention contient un polymère aromatique comprenant : une pluralité d'unités formant une chaîne principale d'un polymère et représentée par la formule (1) ; et une structure réticulée qui se lie à deux unités quelconques ou plus par l'intermédiaire d'au moins l'un parmi R1 à R10 dans les unités, le film poreux présentant un degré de gonflement dans la N-méthyl-2-pyrrolidone de 100 à 200 %. (les définitions de R1-R10 et X dans la formule (1) sont telles que décrites dans la description.)
PCT/JP2023/032588 2022-09-09 2023-09-06 Film poreux et film composite WO2024053691A1 (fr)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10156157A (ja) * 1996-12-03 1998-06-16 Ube Ind Ltd 芳香族ポリイミド気体分離膜
JP2004224994A (ja) * 2003-01-27 2004-08-12 Teijin Ltd 二軸配向ポリイミドフィルムおよびその製造方法
WO2006104228A1 (fr) * 2005-03-28 2006-10-05 Teijin Limited Film de polyimide aromatique et procédé servant à produire celui-ci
CN106977719A (zh) * 2017-04-14 2017-07-25 大连理工大学 一种多长支链聚醚砜/酮阴离子交换膜及其制备方法
WO2018105338A1 (fr) * 2016-12-08 2018-06-14 東レ株式会社 Composition de liant pour éléments de stockage d'électricité, composition de bouillie pour éléments de stockage d'électricité, électrode, procédé de production d'électrode, batterie secondaire et condensateur à double couche électrique
JP2018165819A (ja) * 2017-03-28 2018-10-25 東レ株式会社 感光性樹脂組成物、感光性シート、ならびにそれらの硬化膜およびその製造方法

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10156157A (ja) * 1996-12-03 1998-06-16 Ube Ind Ltd 芳香族ポリイミド気体分離膜
JP2004224994A (ja) * 2003-01-27 2004-08-12 Teijin Ltd 二軸配向ポリイミドフィルムおよびその製造方法
WO2006104228A1 (fr) * 2005-03-28 2006-10-05 Teijin Limited Film de polyimide aromatique et procédé servant à produire celui-ci
WO2018105338A1 (fr) * 2016-12-08 2018-06-14 東レ株式会社 Composition de liant pour éléments de stockage d'électricité, composition de bouillie pour éléments de stockage d'électricité, électrode, procédé de production d'électrode, batterie secondaire et condensateur à double couche électrique
JP2018165819A (ja) * 2017-03-28 2018-10-25 東レ株式会社 感光性樹脂組成物、感光性シート、ならびにそれらの硬化膜およびその製造方法
CN106977719A (zh) * 2017-04-14 2017-07-25 大连理工大学 一种多长支链聚醚砜/酮阴离子交换膜及其制备方法

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