Composite separation membrane and method for producing same

Abstract

The purpose of the present invention is to provide: a composite separation membrane which has excellent organic solvent resistance and exhibits excellent filtration performance in both an aqueous system and an organic-solvent-based system; and a method for producing said composite separation membrane. A composite separation membrane according to the present invention is: characterized by having a support film, and a polyamide layer on one surface or on each surface of the support film; and characterized in that the support film contains a modified polyphenylene oxide having a specific structural unit. A method for producing a composite separation membrane according to the present invention is characterized by including: a step for substituting, with a specific amine compound, a halogeno group of a support film that contains a polyphenylene oxide in which the 2nd and 6th positions of the benzyl are partially substituted with said halogeno group; and a step for laminating a polyamide layer on one surface or on each surface of the support film that contains a polyphenylene oxide in which the 2nd and 6th positions of the benzyl are partially substituted with a halogeno group or the specific amine compound.

Description

Composite separation membrane and method for manufacturing the same

[0001] The present invention relates to a composite separation membrane that has excellent resistance to organic solvents and enables stable separation even in organic solvents, a method for producing the same, a composite membrane that has excellent resistance to organic solvents and enables stable separation even in organic solvents, and a method for separating target substances using the composite membrane.

[0002] Membrane separation, compared to distillation, has the advantage of significantly reducing the energy required for separation because it does not involve phase transition. Furthermore, since membrane separation does not require heating, it is suitable for purifying substances that are susceptible to thermal degradation. Therefore, membrane technology is applied in a wide range of industrial fields, including seawater desalination, drinking water treatment, sewage treatment, and blood purification. However, conventional membrane separation often targets water as the medium.

[0003] In industrial sectors such as the chemical, pharmaceutical, and petrochemical industries, separation operations using organic solvents as a medium are essential, and distillation processes are often employed. While distillation is a highly reliable technology, its high energy consumption and significant carbon dioxide emissions have become social issues.

[0004] In order to apply membrane separation methods to separation processes such as the fractionation and purification of low molecular weight molecules using organic solvents as a medium, or the fractionation and purification of the organic solvent itself, it is necessary to develop nanofiltration membranes and reverse osmosis membranes that can perform stably for long periods of time in organic solvents.

[0005] Separation membranes formed from polyphenylene oxide (PPO) or its derivatives are relatively inexpensive and possess high mechanical strength, alkali resistance, and acid resistance. Furthermore, such PPO separation membranes may be resistant to aprotic polar solvents such as N-methyl-2-pyrrolidone (NMP) and dimethyl sulfoxide (DMSO), making them potentially applicable to filtration processes using these pure solvents as media, as well as organic solvent filtration processes containing alkalis and acids.

[0006] For example, Patent Document 1 discloses a method for producing separation membranes and composite membranes using PPO, and states that these membranes are insoluble in NMP and DMSO at room temperature and exhibit resistance.

[0007] Patent No. 5578300

[0008] However, PPO may dissolve in aprotic polar solvents such as NMP and DMSO depending on the conditions. Even if it does not dissolve in aprotic polar solvents, PPO swells significantly in nonpolar solvents, reducing its strength and making it unsuitable for high-pressure filtration. Furthermore, PPO may not have sufficient resistance to protic polar solvents such as ethanol. The object of the present invention has been made in view of the above circumstances, and is to provide a composite separation membrane having excellent resistance to organic solvents and exhibiting excellent filtration performance in both aqueous and organic solvent systems, a method for producing the same, a composite membrane having excellent resistance to organic solvents and enabling stable separation even in organic solvents, and a method for separating target substances using the composite membrane.

[0009] The inventors diligently conducted research to solve the above problems. As a result, they discovered that by laminating a polyamide layer onto a support membrane of amine-modified polyphenylene oxide, a composite separation membrane can be obtained that has excellent resistance to organic solvents and exhibits excellent filtration performance in both aqueous and organic solvent systems, thus completing the present invention. The present invention is described below.

[0010] [1] A composite separation membrane comprising a support membrane and a polyamide layer on one or both sides of the support membrane, wherein the support membrane contains a modified polyphenylene oxide having a structural unit represented by formula (I). [In the formula, R 1 and R 2 R independently represents a halogen group selected from the group consisting of chloro, bromo, and iodine, or H, and R 3 ~R 8 It is independently, -NR 9 R 10 A halogen group selected from the group consisting of a group, chloro, bromo, and iodine, or a group showing H, R 3 ~R 8 If any one or more of the following apply, then -NR9 R 10 represents a group, -CR 3 R 4 R 5 group and -CR 6 R 7 R 8 group may be covalently bonded to the polyamide layer, and R 9 and R 10 are independently H, a C 1-6 aliphatic hydrocarbon group which may have a substituent α, or a C 6-12 aromatic hydrocarbon group which may have a substituent β, or nitrogen atom, R 9 and R 10 may together form a saturated heterocyclic group which may have a substituent β; the substituent α represents a substituent selected from a hydroxyl group and an amino group; the substituent β represents a substituent selected from a C 1-6 alkyl group, a C 1-6 alkoxy group, a hydroxyl group, an amino group, and a C 1-6 aliphatic hydrocarbon group having an amino group. ] [2] The composite separation membrane according to [1], wherein the support membrane and the polyamide layer are covalently bonded. [3] The composite separation membrane according to [1] or [2], wherein the -NR 9 R 10 group is -NH-(C 1-6 alkanediyl)-substituent α. [4] The composite separation membrane according to [1] or [2], wherein the -NR 9 R 10 group is -NHR 10 group (wherein R 10 represents a C 1-6 aromatic hydrocarbon group having a substituent selected from a hydroxyl group, an amino group, and a C 6-12 aliphatic hydrocarbon group having an amino group).

[0011] [5] A method for producing a composite separation membrane, comprising the step of substituting the halogeno group of a support membrane containing a polyphenylene oxide in which the benzyl positions at the 2- and 6-positions are partially substituted with halogeno groups with an amine compound represented by the following formula (II): NR 9 R 10 ··· (II) [In the formula, R9 and R 10 These are independently H and C which may have a substituent α. 1-6 C may have an aliphatic hydrocarbon group or a substituent β. 6-12 This indicates an aromatic hydrocarbon group, or a nitrogen atom, R 9 and R 10 These may together form a saturated heterocyclic group which may have substituent β, wherein substituent α represents a substituent selected from a hydroxyl group and an amino group, and substituent β is C 1-6 Alkyl alkyl group, C 1-6 Alkoxy group, hydroxyl group, amino group, and C having an amino group 1-6 [1] A method characterized by comprising the step of laminating a polyamide layer on one or both sides of a support film containing a polyphenylene oxide in which the benzyl positions at positions 2 and 6 are partially substituted with halogen groups or an amine compound represented by formula (II). [2] The method according to [5], wherein the polyamide layer is laminated on one or both sides of the support film by reacting a polyfunctional amine compound with a polyfunctional acid chloride. [3] The method according to [5] or [6], wherein the polyphenylene oxide is a polyphenylene oxide in which the benzyl positions at positions 2 and 6 are partially substituted with bromo groups. [4] The method according to any one of [5] to [7], wherein the amine compound represented by formula (II) is monoethanolamine. [5] The method according to any one of [5] to [7], wherein the amine compound represented by formula (II) is phenylenediamine or xylylenediamine.

[0012]

[10] A composite membrane for use as a separation membrane, wherein the composite membrane comprises a support membrane and a polyamide layer, the polyamide layer is laminated on one or both sides of the support membrane, and the support membrane comprises a modified polyphenylene oxide having a structural unit represented by formula (I).

[11] The composite membrane according to

[10] , wherein the support membrane and the polyamide layer are covalently bonded.

[12] The composite membrane according to

[10] or

[11] , for use as a separation membrane in an organic solvent.

[13] The -NR 9 R 10 The group is -NH-(C 1-6 The composite film according to any one of the above

[10] to

[12] , wherein the alkanediyl substituent α is

[14] -NR 9 R 10 The base is NHR 10 group (in the formula, R 10 This includes a hydroxyl group, an amino group, and a C having an amino group. 1-6 C having substituents selected from aliphatic hydrocarbon groups 6-12 A composite film according to any one of the above

[10] to

[13] , wherein the composite film is an aromatic hydrocarbon group.

[0013]

[15] A method for separating a target substance, comprising the step of supplying a liquid sample containing the target substance to a composite membrane, wherein the composite membrane comprises a support membrane and a polyamide layer, the polyamide layer is laminated on one or both sides of the support membrane, and the support membrane contains a modified polyphenylene oxide having a structural unit represented by formula (I).

[16] The method according to

[15] , wherein the support membrane and the polyamide layer are covalently bonded.

[17] The method according to

[15] or

[16] , wherein the liquid contains an organic solvent.

[18] -NR 9 R 10 The group is -NH-(C 1-6 The method according to any one of the above

[15] to

[17] , wherein the alkanediyl) substituent α.

[19] The above -NR 9 R 10 The base is NHR 10 group (in the formula, R 10This includes a hydroxyl group, an amino group, and a C having an amino group. 1-6 C having substituents selected from aliphatic hydrocarbon groups 6-12 The method according to any one of the above

[15] to

[18] , wherein the member is an aromatic hydrocarbon group.

[0014] In this disclosure, "C 1-6 As for "aliphatic hydrocarbon group", C 1-6 Alkyl alkyl group, C 2-6 Alkenyl group and C 2-6 An example is the alkynyl group. 1-6 An "alkyl group" refers to a linear or branched monovalent saturated aliphatic hydrocarbon group having 1 to 6 carbon atoms. Examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, n-hexyl, etc. Preferably C 1-4 It is an alkyl group, more preferably C 1-2 It is an alkyl group.

[0015] "C 2-6 An "alkenyl group" refers to a linear or branched monounsaturated aliphatic hydrocarbon group having 2 to 6 carbon atoms and at least one carbon-carbon double bond. Examples include ethenyl (vinyl), 1-propenyl, 2-propenyl (allyl), isopropenyl, 2-butenyl, 3-butenyl, isobutenyl, pentenyl, hexenyl, etc. Preferably C 2-4 It is an alkenyl, more preferably ethenyl (vinyl) or 2-propenyl (allyl).

[0016] "C 2-6 An "alkynyl group" refers to a linear or branched monounsaturated aliphatic hydrocarbon group having 2 to 6 carbon atoms and at least one carbon-carbon triple bond. Examples include ethynyl, 1-propynyl, 2-propynyl, 2-butynyl, 3-butynyl, pentynyl, hexynyl, etc. Preferably C 2-4 An alkynyl group, more preferably C 2-3 It is an alkynyl group.

[0017] An "aromatic hydrocarbon group" refers to a monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms. Examples include phenyl, naphthyl, indenyl, and biphenyl, with phenyl being preferred.

[0018] A "saturated heterocyclic group" refers to a saturated heterocyclic group that contains at least one nitrogen atom as a heteroatom. Examples include azilidinyl, azetidinyl, pyrrolidinyl, piperidinyl, pyrazolidinyl, imidazolidinyl, morpholinyl, and piperazinyl. Saturated heterocyclic groups include pyrazolidinyl, imidazolidinyl, piperazinyl, and other saturated heterocyclic groups containing an -NH- group, as well as hydroxyl groups, amino groups, and C groups having an amino group. 1-6 A saturated heterocyclic group having a substituent γ selected from aliphatic hydrocarbon groups is preferred.

[0019] The term "amino group" includes primary amino groups (-NH2 groups), secondary amino groups (-NH- groups), and tertiary amino groups (>N- groups), with primary amino groups and / or secondary amino groups being preferred, and primary amino groups being more preferred.

[0020] The secondary amino group is mono-C. 1-6 This refers to an alkylamino group. Examples include methylamino, ethylamino, propylamino, isopropylamino, etc., and mono-C 1-4 Alkylamino groups are preferred, monoC 1-3 Alkylamino groups are more preferred, monoC 1-2 Alkylamino groups are even more preferred.

[0021] The tertiary amino group is diC 1-6 This refers to an alkylamino group. Examples include dimethylamino, diethylamino, ethylmethylamino, di-n-propylamino, diisopropylamino, di-n-butylamino, diisobutylamino, di-s-butylamino, di-t-butylamino, etc. 1-4 Alkylamino groups are preferred, diC 1-3 Alkylamino groups are more preferred, diC 1-2 Alkylamino groups are even more preferred.

[0022] "C 1-6An "alkanediyl group" refers to a linear or branched divalent saturated aliphatic hydrocarbon group having 1 to 6 carbon atoms. Examples include methylene, ethylene, n-propylene, methylethylene, n-butylene, methylpropylene, dimethylethylene, n-pentylene, n-hexylene, etc. Preferably C 2-6 An alkanediyl group, more preferably C 2-6 It is an alkanediyl group, and more preferably ethylene.

[0023] The number of substituents is not particularly limited as long as they are substituted, and can be, for example, 1 or more and 5 or less. Preferably, the number of substituents is 4 or less, more preferably 3 or less or 2 or less, and even more preferably 1.

[0024] In the present invention, a composite separation membrane having an amine-modified PPO membrane with an amine compound introduced at the benzyl position as a support membrane and a polyamide layer as a separation layer has excellent solvent resistance and enables stable separation operations in both aqueous and organic solvent systems.

[0025] Figure 1 shows an example of a scanning electron microscope (SEM) image of the surface of the polyamide layer of the composite separation membrane according to the present invention.

[0026] The composite separation membrane according to the present invention has a support membrane and a polyamide layer on one or both sides of the support membrane. In this disclosure, "composite separation membrane" means a composite membrane used in a separation operation, and "composite separation membrane" and "composite membrane" are substantially the same. The present invention will be described below, but the present invention is not limited to the following specific examples. In addition, "compound represented by formula (x)" may be written as "compound (x)" and "y represented by formula (x)" may be written as "y (x)", and as stated above, "composite separation membrane" and "composite membrane" are substantially synonymous.

[0027] The support membrane plays a role in supporting the polyamide layer having separation function in the composite separation membrane, and preferably has solvent resistance, pressure resistance, acid resistance, and alkali resistance. The support membrane contains modified PPO having structural unit (I). The proportion of the modified PPO in the support membrane can be, for example, 50% by mass or more. The proportion can also be 60% by mass or 70% by mass or more. There is no particular upper limit to the proportion, and the support membrane may consist substantially only of the modified PPO, excluding unavoidable impurities and unavoidable contaminants. That is, the proportion may be 100% by mass or less. The proportion may also be 90% by mass or less, or 80% by mass or less.

[0028] Other support film components besides modified PPO include, for example, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polyphenylene sulfide (PPS), polysulfone (PSU), polyethersulfone (PES), polyvinylidene fluoride (PVDF), polyetherimide (PEI), sulfonated polyarylene ether (SPAE), and copolymers thereof. Furthermore, the support film may be a nonwoven fabric or porous film made of a resin other than PPO, or a resin with a relatively low PPO content, coated with the modified PPO.

[0029] The pore size and porosity of the support membrane and polyamide layer can be adjusted as appropriate depending on the application of the composite separation membrane. Possible applications of composite separation membranes include, for example, microfiltration membranes, ultrafiltration membranes, dialysis membranes, nanofiltration membranes, and reverse osmosis membranes. Generally, the pore size of nanofiltration membranes is 0.5 nm or more and 1.5 nm or less, the pore size of reverse osmosis membranes (RO membranes) is 0.5 nm or less, the pore size of ultrafiltration membranes is 10 nm or more and 0.1 μm or less, and the pore size of microfiltration membranes is 0.1 μm or more and 10 μm or less. In addition, the pore size of standard dialysis membranes is 2 nm or more and 10 nm or less, the pore size of high-permeability dialysis membranes is 10 nm or more and 20 nm or less, and the pore size of ultra-high-permeability membranes is approximately 30 nm. For example, the pore size of the support membrane can be adjusted to 5 nm or more and 1 μm or less, the porosity to 20% or more and 90% or less, and the film thickness to 1.0 μm or more and 200 μm or less.

[0030] In the structural unit (I), from the production conditions, the benzene ring may be directly halogenated, but R 1 and R 2 are preferably H.

[0031] In the structural unit (I), for R 3 to R 5 and R 6 to R 8 there may be introduced two or more —NR 9 R 10 groups, but usually one —NR 9 R 10 group is introduced. The number of —NR 9 R 10 groups in the structural unit (I) may be 1 or more and 4 or less, may be 1 or more and 3 or less, may be 1, or may be 2.

[0032] The polyamide that makes up the polyamide layer is a polymer in which a polyfunctional amine compound having two or more amino groups and a polyfunctional carboxylic acid compound having two or more carboxyl groups are linked by amide bonds.Examples of polyfunctional amine compounds that make up polyamides include phenylenediamine, naphthylenediamine, diaminodiphenylmethane, diaminodiethylphenylmethane, 2,2-bis(4-aminophenyl)propane, 4,4'-diaminodiphenyl ether, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylsulfone, 2,2'-dimethyl-4,4'-diaminodiphenylmethane, 2,4'-diaminobiphenyl, and 2,3'-dimethyl-4,4'-diaminodiphenylmethane. Aromatic diamine compounds such as nobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, bis(aminomethyl)naphthalene, bis(aminoethyl)naphthalene, o-xylylenediamine, m-xylylenediamine, p-xylylenediamine, bis(aminoalkyl)benzene, bis(aminoalkyl)naphthalene; methylenediamine, ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminopropyl Aliphatic diamine compounds such as minoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, and trimethylhexamethylenediamine; saturated hydrocarbon ring diamine compounds such as 1,4-cyclohexanediamine, 4,4'-methylenebiscyclohexylamine, 4,4'-isopropylidenebiscyclohexylamine, norbornadiamine, bis(aminomethyl)cyclohexane, diaminodicyclohexylmethane, isophoronediamine, and mensendiamine; piperazine, 1,4-bis-(8-a Examples include saturated heterocyclic diamine compounds such as minopropyl)-piperazine, 4-diazacycloheptane, 1-(2'-aminoethylpiperazine), 1-[2'-(2''-aminoethylamino)ethyl]piperazine, and tricyclodecanediamine; triamine compounds such as diethylenetriamine, dipropylenetriamine, and bishexamethylenetriamine; and tetraamine compounds such as triethylenetetramine, tripylenetetramine, tetra(aminomethyl)methane, and tetrakis(2-aminoethylaminomethyl)methane.

[0033] Examples of polyfunctional carboxylic acid compounds that constitute polyamides include aliphatic dicarboxylic acid compounds such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dimethylmalonic acid, 3,3-diethylsuccinic acid, 2,2-dimethylglutaric acid, 2-methyladipic acid, and trimethyladipic acid; saturated hydrocarbon ring dicarboxylic acid compounds such as 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid; and isophthalic acid and 2,6-naphthalenedicarbon. Examples include acids, aromatic dicarboxylic acid compounds such as 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,4-phenylenedioxydiacetic acid, 1,3-phenylenedioxydiacetic acid, diphenic acid, 4,4'-biphenyldicarboxylic acid, 4,4'-oxydibenzoic acid, diphenylmethane-4,4'-dicarboxylic acid, and diphenylsulfone-4,4'-dicarboxylic acid; aromatic tricarboxylic acid compounds such as trimellitic acid and trimesic acid; and aromatic tetracarboxylic acid compounds such as pyromellitic acid. As polyfunctional carboxylic acid compounds, compounds in which the carboxyl group has been activated, such as polyfunctional carboxylic acid halides, may also be used.

[0034] The polyamide layer may be formed on both sides of the support film, but it is preferable that it be formed on one side. The polyamide may penetrate into the pores of the support film, but it is necessary that at least some of the communication pores between the support film and the composite separation film are maintained. The thickness of the polyamide layer is preferably 0.01 μm or more and 1 μm or less, and more preferably 0.02 μm or more and 0.3 μm or less. The thickness of the polyamide layer refers to the distance from the top of the support film to the surface of the polyamide layer when the cross-section of the composite separation film is observed under magnification. Furthermore, for example, the pore diameter of the polyamide layer can be adjusted to 0.2 nm or more and 1.5 nm or less.

[0035] The surface of the polyamide layer may be smooth, but it may also have a pleated structure from the viewpoint of increasing the filtration surface area.

[0036] -CR in structural unit (I) 3 R 4 R 5 base and -CR 6 R 7 R8 The base is preferably covalently bonded to the polyamide layer. Such covalent bonding increases the adhesion between the support film and the polyamide layer, and consequently increases the durability of the composite separation film. Specifically, -NR 9 R 10 The -NH2 group or -NH- group possessed by the group may be covalently bonded to the polyfunctional amino compound constituting the polyamide layer via the polyfunctional carboxylic acid compound constituting the polyamide layer. -CR 3 R 4 R 5 base and -CR 6 R 7 R 8 If the group has a halogen group, when forming a polyamide layer by interfacial polymerization, -CR 3 R 4 R 5 base and -CR 6 R 7 R 8 The halogen group of the group can covalently bond with the polyamide layer. Unreacted amino groups and unreacted carboxyl groups, such as terminal reactive groups of the polyamide, can bond to the support film. 3 R 4 R 5 base or -CR 6 R 7 R 8 Covalent bonds can also be formed between the halogeno group, -NH2 group, or -NH- group within the group. 3 R 4 R 5 base and -CR 6 R 7 R 8 Hydrogen bonds are formed between the >NH or hydroxyl groups in the polyamide and the nitrogen or oxygen atoms in the polyamide.

[0037] The following describes a method for producing a composite separation membrane according to the present invention. 1. Halogeno group introduction step In this step, a halogeneno group selected from chloro, bromo, and iodine is introduced to the methyl group of the raw material polyphenylene oxide (PPO, poly-2,6-dimethyl-1,4-phenylene oxide). PPO is generally represented by the following formula (III).

[0038] [In the formula, n represents an integer of 1 or more, preferably an integer of 2 or more, and more preferably an integer between 40 and 5000.]

[0039] The raw material, PPO, can be selected as appropriate. For example, the weight-average molecular weight of the PPO is preferably 5,000 or more and 500,000 or less, from the viewpoint of imparting sufficient viscosity to the film-forming solution to improve coating properties and stringability, and ensuring the strength of the film.

[0040] In this step, in order to perform modification with the amine compound (II) described later, the hydrogen atoms of the methyl groups at the 2 and 6 positions of PPO(III) are replaced with halogen groups using a known method. That is, the benzyl position (Ph-C) of PPO(III) is halogenated. Bromo is preferably used as the halogen group because it has high leaving ability, is inexpensive, and is easy to handle.

[0041] In the present invention, during the process of halogenating the benzyl position of PPO, a portion of the benzene rings at the 3 and 5 positions may be substituted with a halogen group. However, the halogen group of the benzene ring is S N To avoid a type II nucleophilic substitution reaction, it is preferable to use known reaction conditions that selectively halogenate the benzyl position. Specifically, it is preferable to use carbon tetrachloride or chlorobenzene as the reaction solvent. This is because using these solvents, which have low halogen solubility, keeps the halogen concentration in the reaction system low, resulting in preferential halogenation at the benzyl position. For example, it is known that using polar solvents such as acetonitrile results in halogenation only at the benzene ring. From the viewpoint of ease of handling, it is preferable to avoid carbon tetrachloride and use chlorobenzene.

[0042] For halogenation, known halogenating agents such as elemental halogens and N-halogenated succinimide can be used as halogen sources. The reaction conditions for halogenation are preferably under an inert atmosphere such as argon or nitrogen, at a reaction temperature of 110°C or higher, and for at least 3 hours. Higher reaction temperatures increase the selectivity for halogenation to the benzylic position. However, at temperatures above 140°C, side reactions such as polymer crosslinking may occur; therefore, the reaction is more preferably carried out at 115°C or higher and below 135°C.

[0043] After the reaction, general post-treatment can be carried out. For example, a poor solvent such as methanol, ethanol, or acetone can be added to the reaction solution to precipitate the halogenated PPO, which can then be filtered off. The filtered halogenated PPO can then be washed with a poor solvent and dried. Methanol is preferred as the poor solvent.

[0044] In this invention, the degree of halogenation at the benzyl position of halogenated PPO can be determined, for example, by nuclear magnetic resonance (NMR) using deuterated chloroform as a solvent. The generalized structural unit of halogenated PPO is shown in chemical formula (IV). Depending on the degree of halogenation of the benzene ring and the benzyl position, various structural units n i (i=1 to k) can be generated, but the relative abundance of each structural unit can be determined based on the characteristic peaks in NMR. Detailed structural units can also be identified, for example, using heteronuclide single quantum coherence (HSQC).

[0045]

[0046] In formula (IV), R 1 and R 2 R independently represents a halogen group selected from the group consisting of chloro, bromo, and iodine, or H, and R 11 ~R 16 This independently represents a halogen group selected from the group consisting of chloro, bromo, and iodine, or H. i This represents the mole fraction (n) of k structural units identified by NMR, expressed as i = 1 to k (where k is an integer greater than or equal to 2). i (This represents a value between 0 and 1, inclusive.)

[0047] Among the k types of structural units, there may be structural unit A below which no halogen group is introduced, but most structural units have one or more halogen groups introduced, and structural units B to D below are considered to be the most common, with structural units B to C below being even more common. In at least one type of structural unit, R 11 ~R 16One or more of these represent a halogeno group at the benzyl position. In the formula, X represents a halogeno group selected from the group consisting of chloro, bromo, and iodine.

[0048]

[0049] In this invention, the degree of halogenation DBr is defined by the average value of the number of halogen groups substituted at the benzyl position per structural unit, and is expressed by the following formula (1). PPO has two methyl groups at positions 2 and 6 in its structural unit, and there are 6 hydrogen atoms at the benzyl position where substitution can occur, so DBr can take values ​​from 0 to 6.0. However, to the best of the inventors' knowledge, in most cases one hydrogen atom is substituted for one halogen group per methyl group, and there are also a certain number of cases where two hydrogen atoms are substituted for halogen groups. On the other hand, no cases were observed where three hydrogen atoms were substituted for one halogen group per methyl group.

[0050] [In the formula, N i_BzBr This represents the number of halogen groups substituted at the benzyl position in structural unit i.

[0051] The average number of halogen groups substituted on the benzene ring per structural unit is expressed by the following formula (2). [In the formula, N i_ArBr This represents the number of halogen groups substituted on the benzene ring in structural unit i.

[0052] The degree of halogenation at the benzyl position, DBr, is preferably 0.5 or higher and 2.0 or lower. If DBr is 0.5 or higher, the benzyl group can be sufficiently modified with amine compound (II), thus more reliably imparting sufficient solvent resistance and hydrophilicity to the composite separation membrane. Furthermore, if DBr is 2.0 or lower, excessive use of halogenating agents can be more reliably avoided, and side reactions such as crosslinking during the reaction process can be more reliably suppressed.

[0053] There are no particular restrictions on the degree of halogenation of the benzene ring, DBr2, but it is preferably between 0 and 1.0. If DBr2 is 1.0 or less, the degree of halogenation at the benzyl position, DBr, is relatively sufficiently high, which can more reliably avoid excessive consumption of halogenating agents and can impart sufficient solvent resistance to the support film. Note that halogenation of the benzene ring is not required, but it can inevitably occur. That is, depending on the reaction conditions, both halogenation of the benzene ring and halogenation at the benzyl position can occur.

[0054] 2. Film Forming Process In this process, halogenated PPO is formed into a film to obtain a support film. The film form is not particularly limited, and can be a flat film or a hollow fiber film. Since halogenated PPO is soluble in NMP, DMF, etc., solution film formation is preferable. In this process, a certain amount of non-solvent can be added to a good solvent such as NMP to control phase separation. For example, the pore size and porosity of the halogenated PPO film and the support film can be adjusted by the type of good solvent, whether or not a non-solvent is used, the type of non-solvent, the concentration of the halogenated PPO solution, etc. Examples of non-solvents include polyethylene glycol, glycerin, polypropylene glycol, nonionic surfactants, and ionic surfactants.

[0055] To the best of our knowledge, PPO modified at the benzyl position with amine compound (II) or the like is insoluble in any solvent, making it difficult to mold. Therefore, it is preferable to mold halogenated PPO into a film and then modify the halogenated PPO film with amine compound (II).

[0056] When preparing halogenated PPO flat membranes, for example, a halogenated PPO film-forming stock solution can be applied to a nonwoven fabric or porous membrane made of a material with excellent solvent resistance, such as polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polyphenylene sulfide (PPS), polysulfone (PSU), polyethersulfone (PES), polyvinylidene fluoride (PVDF), polyetherimide (PEI), sulfonated polyarylene ether (SPAE), and copolymers thereof, using a doctor blade or the like, and then immersed in a coagulation bath of a non-solvent such as water to obtain a halogenated PPO flat membrane. Polyphenylene sulfide (PPS) is preferred as the nonwoven fabric material. PPS has excellent solvent resistance and also excellent resistance to alkalis and acids. Hollow fiber membranes can be obtained by extruding the halogenated PPO film-forming stock solution together with the inner liquid from a double cylindrical nozzle and immersing it in a coagulation bath.

[0057] In this process, conditions such as the halogenated PPO concentration of the film-forming stock solution, the discharge temperature, the temperature and composition of the coagulation bath, and the transport speed can be appropriately set based on known knowledge. For example, the halogenated PPO concentration and amount used in the film-forming stock solution can be appropriately adjusted within the range in which the support film has interconnected pores.

[0058] The resulting halogenated PPO film is preferably completely dry by natural air drying or vacuum drying. If a large amount of moisture remains in the film, the nucleophilic substitution reaction with the amine-based nucleophile described later may not proceed sufficiently.

[0059] 3. Amine Modification Process In this process, the halogen groups of the support film containing halogenated PPO are replaced with amine compound (II) to amine-modify the PPO in the support film.

[0060] The dried support film undergoes a nucleophilic substitution reaction by immersion in a solution containing an amine nucleophile, i.e., amine compound (II). The halogen group substituted at the benzyl position of halogenated PPO is readily substituted by the amine nucleophile.

[0061] Polyfunctional amine compounds (II), i.e., R 9 and / or R 10A C group having an aliphatic hydrocarbon group with substituent α, or a hydroxyl group, an amino group, or a C group having an amino group as substituent β. 1-6 It is an aromatic hydrocarbon group having an aliphatic hydrocarbon group, or a nitrogen atom, R 9 and R 10 When these are combined and a saturated heterocyclic group having a hydroxyl group and / or an amino group is used as substituent β, it is possible to introduce covalent crosslinks between PPO molecular chains. Amino groups are preferred as substituents α and β, and -NH2 groups are more preferred.

[0062] The polyfunctional amine compound (II) can be any polyfunctional amine compound that constitutes the polyamide layer, such as an aliphatic diamine compound, a saturated hydrocarbon ring diamine compound, a saturated heterocyclic diamine compound, a triamine compound, or a tetraamine compound. However, the polyfunctional amine compound that constitutes the polyamide layer and the polyfunctional amine compound (II) that constitutes the modified PPO support film may be the same or different.

[0063] As the polyfunctional amine compound (II), an alkanolamine may be used. The hydrocarbon group contained in the alkanolamine is C 2-6 Examples include alkanediyl groups. As alkanolamines, monoethanolamine represented by formula (V) or N-C 1-6 By using alkylaminoethanol, high solvent resistance can be imparted to PPO films. Although the detailed mechanism of how alkanolamine substitution results in solvent resistance is not entirely clear, the side chains substituted with these alkanolamines readily form hydrogen bonds between molecules via hydroxyl groups, resulting in an extremely hydrophilic structure. In contrast, the main chain PPO is a hydrophobic and highly strong aromatic polymer. It is believed that the combination of hydrophilicity and hydrophobicity within the molecular structure results in insolubility to organic solvents across a wide range of solubility parameters. Furthermore, by having a high density of hydroxyl groups in the side chains, the resulting modified PPO film exhibits good hydrophilicity, allowing for repeated drying and wetting without the need for wetting treatment with alcohol, and making it suitable for composite film formation such as interfacial polymerization.

[0064] [In the formula, R 17 is H or C 1-6 This indicates an alkyl group.

[0065] The structural unit of the amine-modified PPO constituting the amine-modified PPO support film according to the present invention is represented by formula (I). [In the formula, R 1 ~R 8 This indicates the same meaning as above.

[0066] In the structural units of amine-modified PPO, the halogen group X is -NR in structural units A to J of halogenated PPO. 9 R 10 The structural units in which the group is substituted can be listed, and in structural units B to D, the halogen group X is -NR 9 R 10 Many structural units are substituted with other groups, and in structural units B to C, the halogen group X is -NR 9 R 10 It is thought that a larger number of structural units have been substituted for the base.

[0067] In the amine-modified PPO constituting the composite separation membrane according to the present invention, the average number of amine compounds (II) substituted at the benzyl position per structural unit is preferably 0.5 or more and 2.0 or less. If this value is 0.5 or more, the solvent resistance of the amine-modified PPO can be sufficiently improved. On the other hand, since it may be difficult to introduce three or more amine compounds into a structural unit, this value is preferably 2.0 or less.

[0068] By introducing a polyfunctional amine compound (II), particularly a polyfunctional amine compound (II) having two or more amino groups, into PPO, the hydrophilicity and mechanical strength are increased. Examples of polyfunctional amine compounds (II) that can be used include alicyclic diamines such as piperazine; aliphatic triamines such as diethylenetriamine; and aromatic diamines such as phenylenediamine and xylylenediamine.

[0069] The concentration of amine compound (II) in the nucleophilic substitution reaction can be adjusted as appropriate, but it is preferably between 1% by mass and 10% by mass. Furthermore, an organic solvent in which the halogenated PPO film does not dissolve is preferred as the solvent. For example, methanol, ethanol, acetonitrile, dimethyl sulfoxide, etc., can be used, with methanol and acetonitrile being preferred. The reaction time is preferably adjusted appropriately within the range of 1 hour to 24 hours. Additionally, it is preferable to refresh the amine compound (II) solution during the reaction to increase the degree of substitution.

[0070] The amine-modified PPO film, after the nucleophilic substitution reaction has been completed in this step, is preferably washed. Suitable washing solvents include, for example, alcoholic solvents such as methanol, ethanol, and 2-propanol, and water. The amine-modified PPO may be stored while immersed in the washing solvent.

[0071] 4. Lamination Process In this process, a polyamide layer is laminated on one or both sides of a support film containing polyphenylene oxide in which the benzyl positions at positions 2 and 6 are partially substituted with halogen groups or amine compounds represented by formula (II). The order in which this process is performed and the amine modification process 3 is irrelevant. That is, the PPO may be amine-modified after the polyamide layer is laminated on the halogenated PPO film by this process, or the polyamide layer may be laminated on the amine-modified PPO film by this process, or the amine modification of the halogenated PPO film and the lamination of the polyamide layer may be performed simultaneously.

[0072] The polyamide layer may be laminated by thermal compression bonding of the polyamide film onto a halogenated PPO film or an amine-modified PPO film, but it is preferable to form it by interfacial polymerization on the halogenated PPO film or the amine-modified PPO film.

[0073] If this step is performed following the amine modification step 3, and interfacial polymerization is carried out on the amine-modified PPO film, the polyfunctional carboxylic acid compound constituting the polyamide reacts with the amine compound (II), particularly the polyfunctional amine compound (II), introduced into the amine-modified PPO, and the amine-modified PPO and the polyamide layer are covalently bonded, which may significantly improve the durability of the composite separation film.

[0074] Even when the amine modification step 3 is performed following this step, and interfacial polymerization is carried out on the amine-modified PPO film, there is a possibility that the polyfunctional amine compound constituting the polyamide may react with the benzyl position of the halogenated PPO, or that the terminal carboxyl group of the polyamide may react with the amine compound (II) introduced into the amine-modified PPO to form a covalent bond. The carboxyl group may also be its carboxylic acid halide.

[0075] Even when the amine modification step 3 and this step are performed simultaneously, there is a possibility that a covalent bond may be formed by the polyfunctional carboxylic acid compound constituting the polyamide reacting with the amine compound (II) introduced into the amine-modified PPO, or by the polyfunctional amine compound constituting the polyamide reacting with the benzyl position of the halogenated PPO, or by the terminal carboxyl group of the polyamide reacting with the amine compound (II) introduced into the amine-modified PPO.

[0076] Interfacial polymerization of polyamides can be carried out by conventional methods. For example, after impregnating a support film with a solution of a polyfunctional amine compound, excess solution is removed to form an amine phase in which the surface pores of the support film are filled with the polyfunctional amine compound solution, and then the interfacial polymerization reaction can be carried out by contacting this amine phase with an immiscible polyfunctional carboxylic acid compound solution. The method of contact between the amine phase and the polyfunctional carboxylic acid compound solution is not particularly limited, but for example, after pouring the polyfunctional amine compound solution onto a support film fixed in a frame, excess solution can be removed by draining or decantation, and then the polyfunctional carboxylic acid compound solution can be poured on top to allow the reaction to proceed. The concentration and amount of the solution should be adjusted as appropriate so that the pores of the support film are not completely filled and the film can be used for separation.

[0077] The reaction conditions can be adjusted as needed, but for example, the reaction should be carried out at room temperature, more specifically between 10°C and 35°C, for at least 10 seconds and no more than 1 hour. After the reaction, the composite separation membrane should be washed with water or similar.

[0078] The composite separation membrane according to the present invention may be used for separation as is, but it is preferable to thoroughly wet it beforehand with the solvent of the solution or suspension to be separated.

[0079] The composite separation membrane according to the present invention exhibits excellent solvent resistance to both aqueous and organic solvent systems because the solvent resistance of the PPO constituting the support membrane is improved by amine modification, and a layer containing polyamide, which has relatively excellent solvent resistance, is laminated on top of it. Furthermore, when the polyamide layer and the amine-modified PPO support membrane are covalently bonded, the interlayer adhesion is very high, and defects such as delamination are unlikely to occur. Therefore, the composite separation membrane according to the present invention is applicable not only to aqueous membrane separation but also to organic solvent membrane separation, and is extremely useful.

[0080] 5. Separation Method The composite membrane according to this disclosure is useful as a separation membrane because it has excellent resistance to organic solvents. The composite membrane according to this disclosure can be used, for example, in a separation method for a target substance that includes the following steps.

[0081] In this process, a liquid sample containing the substance to be separated is supplied to the composite membrane according to this disclosure. The pore size of the composite membrane, i.e., the pore size of the polyamide layer, is preferably 0.2 nm or more and 1.5 nm or less. The molecular weight of the substance to be separated corresponding to such pore size is approximately 30 or more and 2000 or less, and the molecular size is approximately 0.3 nm or more and 2.0 nm or less.

[0082] Since the composite film according to this disclosure exhibits resistance not only to water but also to organic solvents, the solvent for the liquid sample is not limited to water but may also be an organic solvent. Examples of organic solvents include water-soluble organic solvents and water-insoluble organic solvents. The solvent for the liquid sample may also be a mixed solvent of water and a water-soluble organic solvent. The water-soluble organic solvent may be an organic solvent that is miscible with water without restriction. Examples of water-soluble organic solvents include alcohol-based solvents such as methanol, ethanol, and 2-propanol; amide-based solvents such as dimethylformamide, dimethylacetamide, and γ-butyrolactone; sulfoxide-based solvents such as dimethyl sulfoxide; and ketone-based solvents such as acetone. Examples of water-insoluble solvents include aromatic hydrocarbon solvents such as benzene, toluene, and chlorobenzene; aliphatic hydrocarbon solvents such as hexane and cyclohexane; and halogenated hydrocarbon solvents such as chloroform.

[0083] The substance to be separated in the liquid sample is not particularly limited, but a chemical substance with a larger molecular size than the solvent is preferred. The substance to be separated may be, for example, a biological sample such as oligopeptides, nucleic acids, DNA, or antibodies.

[0084] The liquid sample is supplied from a container such as a tank to the supply side of the composite membrane, i.e., the polyamide layer side, under pressure from a high-pressure pump, and the separation operation is performed using the pressure as the driving force. Filtration may be total filtration by dead end, or it may be cross-flow filtration in which a portion of the supply flow rate is permeated through the membrane and the remainder is returned to the tank and circulated on the supply side. The separation operation may be a solvent recovery operation aimed at recovering water or organic solvent by permeating only the solvent, water or organic solvent, through the membrane and retaining other solutes on the supply side of the membrane, or a concentration operation aimed at concentrating a specific solute on the supply side. It may also be a solvent exchange or solvent purification operation that increases the purity of water or organic solvent by separating organic solvents from other organic solvents, or water from other organic solvents. Furthermore, in a liquid sample containing two or more solutes, it may be an operation aimed at purification, where the purity of a specific solute is increased by separating solutes with smaller molecular sizes from solutes with larger molecular sizes. For purification purposes, a diafiltration operation can be performed, in which the amount of solvent lost on the supply side as water or an organic solvent permeates the membrane is replenished in the tank, thereby maintaining a constant solute concentration on the supply side while repeatedly filtering. The pressure on the supply side can generally be adjusted between 3 atmospheres and 100 atmospheres.

[0085] In the separation operation, a so-called osmotically assisted reverse osmosis method can be performed by adding a solution containing a certain concentration of solute not only to the feed solution side but also to the permeate side, thereby adjusting the osmotic pressure difference between the membranes to a desired value while increasing the solute concentration on the feed side.

[0086] This application claims the benefit of priority based on Japanese Patent Application No. 2024-189036, filed on 28 October 2024. The entire specification of Japanese Patent Application No. 2024-189036, filed on 28 October 2024, is incorporated herein by reference.

[0087] The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

[0088] Example 1: Preparation of Modified Polyphenylene Oxide Separation Membrane (1) Synthesis of Brominated Polyphenylene Oxide Polyphenylene oxide ("181781", manufactured by Sigma Aldrich) (40 g) was packed into a 500 mL four-necked flask fitted with a reflux tubing, nitrogen inlet, and stirring blade. Chlorobenzene (240 mL) was added and dissolved under nitrogen purging. When a homogeneous, clear solution was obtained, N-bromosuccinimide (107 g) and azobisisobutyronitrile (2.0 g) as a radical initiator were added. Under strong stirring, the reaction was carried out for 6.5 hours while monitoring the rate of heating of the reaction solution in an oil bath, raising the liquid temperature to 120°C and maintaining it thereafter. After the reaction solution was allowed to cool, 2 L of methanol was added. The flake-like polymer that precipitated due to the addition of methanol was finely crushed with a blender, and then the polymer was thoroughly washed while refreshing with methanol. Subsequently, the polymer was vacuum-dried at 60°C to obtain powdered brominated polyphenylene oxide (BrPPO).

[0089] (2) Chemical structure evaluation of brominated polyphenylene oxide The obtained BrPPO was subjected to a nuclear magnetic resonance apparatus ( 1 H-NMR, 13 The analysis was performed using C-NMR under the following conditions, particularly 1 By analyzing the peak group originating from benzene ring hydrogens in 1H-NMR, the degree of bromination at the benzylic position (DBr) and the degree of bromination at the benzene ring (DBr2) were determined. In order to identify trace amounts of the unit structure in detail, 1313C-NMR and heteronuclide single quantum coherence (HSQC) were also used. Apparatus: Fourier transform nuclear magnetic resonance spectrometer ("AVANCE500", Bruker BioSpin). Samples: 5–50 mg of each sample was dissolved in 1.0 mL of deuterated chloroform.

[0090] (3) Preparation of brominated polyphenylene oxide (BrPPO) film A predetermined amount of BrPPO, NMP, and polyethylene glycol (PEG400) with a molecular weight of 400 were kneaded and dissolved at 60°C for 6 hours to prepare a film-forming stock solution with a concentration of 25% by mass. After degassing this film-forming stock solution under reduced pressure, a film with a width of 300 mm, a thickness of 120 μm, and a basis weight of 108 g / m² was prepared. 2 The material was applied to a polyphenylene sulfide (PPS) nonwoven fabric using a doctor blade and solidified in a 40°C water bath for 10 minutes. After the solidification was complete, the film was thoroughly washed with water and air-dried to obtain a BrPPO film.

[0091] (4) Amine modification treatment of BrPPO membranes The BrPPO membranes were immersed in a 3% by mass methanol solution of monoethanolamine at room temperature for 48 hours, and bromin and amines were introduced by nucleophilic substitution reaction. The amine-introduced samples were evaluated by immersion in water or methanol or stored until the next step.

[0092] (5) Polyamide interfacial polymerization A rectangular film sample of a BrPPO film or amine-modified PPO film was placed on a glass plate of the same size, and a rectangular silicone rubber gasket and stainless steel frame were placed on the surface side of the film and fixed in place with clamps. Next, a 2% by mass aqueous solution of m-phenylenediamine was poured onto the film surface inside the frame and left for 1 minute, after which the solution was drained. No droplets that would cause defects remained on the film surface, and a smooth surface was quickly formed. After that, a 0.15% by mass hexane solution of 1,3,5-trimesinate chloride (TMC) was gently poured into the frame and left for 1 minute to carry out interfacial polymerization. After the reaction was complete, the TMC solution was drained and washed with water.

[0093] (6) After coating the surface of the obtained film with platinum, it was observed using a scanning electron microscope ("S-4800" manufactured by Hitachi High-Technologies Corporation) at an acceleration voltage of 5 kV. The results are shown in Figure 1. As shown in the SEM image in Figure 1, the polyamide layer formed on the surface of the amine-modified PPO film has a structure with a typical pleated structure and there are no pinholes, so it is considered that a composite separation film with high permeability selectivity has been obtained.

[0094] Example 2 An oven-dried BrPPO film was prepared in the same manner as in Examples 1(1) to (3). The BrPPO film was immersed in pure water for 24 hours, and polyamide interfacial polymerization was carried out according to Example 1(5). However, in order to improve the wettability of the highly hydrophobic BrPPO film to the amine aqueous solution, 1% by mass of 10-camphor sulfonic acid was dissolved in the amine aqueous solution. The amine aqueous solution was poured onto the surface of the BrPPO film, left for 5 minutes, and then drained. Since droplets formed on the film surface, the excess solution was removed using an air knife. Subsequently, the composite separation film was subjected to amine modification treatment according to Example 1(4). Using monoethanolamine stock solution as the amine, the reaction was carried out at room temperature for 6 hours under solvent-free conditions, and then washed with water and subjected to evaluation.

[0095] Example 3 A composite separation membrane was prepared in the same manner as in Example 2, except that in the amine modification treatment of the BrPPO membrane in Example 1 (4), a 3% by mass methanol solution of piperazine was used instead of a 3% by mass methanol solution of monoethanolamine, and in the interfacial polymerization in Example 1 (5), a 2% by mass aqueous solution of piperazine was used instead of a 2% by mass aqueous solution of m-phenylenediamine.

[0096] Example 4 A composite separation membrane was prepared in the same manner as in Example 2, except that in the amine modification treatment of the BrPPO membrane in Example 1 (4), a 3% by mass methanol solution of m-xylylenediamine was used instead of a 3% by mass methanol solution of monoethanolamine, and in the interfacial polymerization in Example 1 (5), a 3.0% by mass aqueous solution of m-xylylenediamine was used instead of a 2% by mass aqueous solution of m-phenylenediamine.

[0097] Example 5 An oven-dried BrPPO film was prepared in the same manner as in Examples 1(1) to (3), except that the amount of N-bromosuccinimide used was changed from 107 g to 60 g. Subsequently, amine modification treatment of the BrPPO film and interfacial polymerization were carried out simultaneously according to Examples 1(4) and (5). Specifically, a 3% by mass acetonitrile solution of m-phenylenediamine was poured onto the surface of the BrPPO film, and the acetonitrile solution was drained after 5 minutes. A smooth surface without droplets was obtained, and this surface was brought into contact with a 0.15% by mass cyclohexane solution of trimesic acid chloride to perform interfacial polymerization for 1 minute. After rinsing the film surface with hexane, the obtained composite separation film was sealed in a polyethylene container filled with a 3% by mass acetonitrile solution of m-phenylenediamine and subjected to crosslinking treatment for 48 hours, washed with methanol and water, and then subjected to evaluation.

[0098] Comparative Example 1 (1) Preparation of an unmodified polyphenylene oxide support film Polyphenylene oxide (PPO, "181781" manufactured by Sigma Aldrich) was prepared. NMP was added so that the PPO content was 25% by mass, and the mixture was kneaded overnight at 130°C to dissolve it and obtain a homogeneous film-forming stock solution. Subsequently, an NMP aqueous solution was appropriately impregnated onto a 5 mm thick, 30 cm square glass substrate with a basis weight of 108 g / m². 2 A fixed polyphenylene sulfide (PPS) nonwoven fabric was preheated to 80°C on a hot plate. The film-forming solution at 80°C was then cast onto it, and the film was quickly applied using an applicator also preheated to 80°C. After obtaining the coating, it was immediately immersed in a solidification bath of 35% NMP aqueous solution at 40°C to obtain a flat support film. The film was thoroughly washed with water, then impregnated in a 70% glycerin aqueous solution and dried. The thickness of the support film, excluding the polyester papermaking portion, was 45 μm.

[0099] (2) Polyamide interfacial polymerization After immersing the above PPO film in ultrapure water overnight, a rectangular film sample was placed on a glass plate of the same size, and a rectangular silicone rubber gasket and stainless steel frame were placed on the surface side of the film and secured with clamps. Next, a 2% by mass aqueous solution of metaphenylenediamine was poured onto the film surface inside the frame, and after 5 minutes, the solution was drained and the excess amine solution was removed with an air knife. Then, a 0.15% by mass hexane solution of trimesic acid chloride was gently poured into the frame and allowed to stand for 1 minute to carry out interfacial polymerization. After the reaction was complete, the acid chloride solution was drained and the film was rinsed with hexane. After air-drying the film for 1 minute, it was thoroughly washed with water and stored in water until evaluation.

[0100] Comparative Example 2 (1) Preparation of Polysulfone (PSU) Film As a polymer for the support film of a general polyamide composite film, polysulfone ("Udel P3500" manufactured by Solvay Specialty Polymers Japan) was prepared. NMP was added so that the PSU content was 18%, and the mixture was kneaded overnight at 100°C to dissolve it and obtain a homogeneous film-forming stock solution. Subsequently, an NMP aqueous solution was appropriately impregnated onto a 5 mm thick, 30 cm square glass substrate with a basis weight of 108 g / m². 2 A polyphenylene sulfide (PPS) nonwoven fabric was fixed, and the film-forming solution was cast over it and then applied with an applicator. After obtaining the coating film, it was immediately immersed in a coagulation bath of 35% NMP aqueous solution at 40°C to obtain a flat support film. The film was thoroughly washed with water, then impregnated in a 70% glycerin aqueous solution and dried. The thickness of the support film, excluding the polyester papermaking portion, was 40 μm.

[0101] (2) Polyamide interfacial polymerization After immersing the PSU film in ultrapure water overnight, a rectangular film sample was placed on a glass plate of the same size, and a rectangular silicone rubber gasket and stainless steel frame were placed on the surface side of the film and secured with clamps. Next, a 2% by mass aqueous solution of metaphenylenediamine was poured onto the film surface inside the frame, and after 5 minutes, the solution was drained and the excess amine solution was removed with an air knife. Then, a 0.15% by mass hexane solution of trimesic acid chloride was gently poured into the frame and allowed to stand for 1 minute to carry out interfacial polymerization. After the reaction was complete, the acid chloride solution was drained and the film was rinsed with hexane. After air-drying the film for 1 minute, it was thoroughly washed with water and stored in water until evaluation.

[0102] Comparative Example 3: The amine-modified BrPPO film of Example 1 (4) was used as a separation film without polyamide interface polymerization on it.

[0103] Table 1 summarizes the film compositions of Examples 1-5 and Comparative Examples 1-3.

[0104]

[0105] Test Example 1: The separation performance of the composite separation membranes of Examples 1-5 and Comparative Examples 1-3, which were sufficiently wetted with aqueous water, was evaluated using an evaluation apparatus consisting of a stainless steel pressure vessel, a supply water tank, and a pump.

[0106] (1) An aqueous NaCl solution adjusted to a concentration of 1500 mg / L for measuring the NaCl rejection rate was supplied to a composite separation membrane at 25°C and a pressure of 15 bar for 1 hour. The permeate was collected and its weight was measured using an electronic balance. The permeate weight was converted to the permeate volume at 25°C using the following formula: Permeate volume (L) = Permeate weight (kg) / 0.99704 (kg / L) Furthermore, the amount of permeate of the filtrate per unit time, unit membrane area, and unit pressure is expressed as permeance (A). The permeability A of water was evaluated using pure water at a pressure of 5 bar or 15 bar and was calculated using the following formula: A [L / (m³)] 2 [h bar] = Permeate volume [L] / Membrane area [m²] 2 ] / Sampling time [h] / Measured pressure [bar]

[0107] The NaCl rejection rate was evaluated as follows. The conductivity of the membrane permeate water collected during the above water permeability measurement and the supply water was measured using an electrical conductivity meter ("CM-25R," manufactured by Toa DKK Co., Ltd.). The rejection rate was calculated using the following formula. The results are shown in Table 2. NaCl rejection rate [%] = (1 - Membrane permeate water conductivity [μS / cm] / Supply aqueous solution conductivity [μS / m]) × 100

[0108] Furthermore, each composite separation membrane from Examples 1-5 and Comparative Examples 1-3 was immersed in ethanol with a purity of 99.5% or higher at room temperature and pressure for 7 days, then thoroughly washed with pure water, and the NaCl rejection rate was measured in the same manner. The results are shown in Table 2.

[0109] Test Example 2: Permeability Test with Organic Solvents A composite separation membrane, thoroughly washed with N-methyl-2-pyrrolidone (NMP), was loaded into a stainless steel pressure vessel sealed with FFKM sealing material. Organic solvents were then transferred from a 500 mL HPLC screw-cap bottle to the pressure vessel using an HPLC preparative pump, and the permeability of the organic solvents was evaluated. The permeability A of the NMP solvent was measured at 15 bar and calculated using the following formula. The results are shown in Table 2. A [L / (m³)] 2 [h bar] = Permeate volume [L] / Membrane area [m²] 2 ] / Sampling time [h] / Measured pressure [bar]

[0110] Test Example 3: Separation Test in Organic Solvents Diol-type polypropylene glycol (PPG400) with a molecular weight of 400 (manufactured by Fujifilm Wako Pure Chemical Industries) was used as a marker for membrane separation tests in NMP. For the PPG400 separation test, NMP containing PPG400 was supplied to the membrane at 25°C and a pressure of 30 bar for 6 hours, and the permeate was collected. Peak analysis of PPG400 in the feed solution and permeate was performed by high-performance liquid chromatography (HPLC), and the rejection rate of PPG400 was determined from the area ratio of the peak top molecular weight components before and after permeation. The results are shown in Table 2. Rejection rate [%] = 100 × [1 - (peak area of ​​peak top molecular weight component in permeate) / (peak area of ​​peak top molecular weight component in feed solution)] The HPLC measurement conditions are shown below. [HPLC Conditions] Instrument: Thermo Fisher Scientific Vanquish Column: Waters BEH C18 2.1 × 150 mm Mobile phase: A. Ultrapure water, B. Acetonitrile 0–15 min (5% B) 15–20 min (60% B) 20–25 min (100% B) Flow rate: 0.25 mL / min Column temperature: 40°C Injection volume: 5 μL Detection: Charged particle detector (CAD) Drying tube temperature: 35°C

[0111]

[0112] As shown in Table 2, the composite separation membrane of Comparative Example 1, which consisted only of an unmodified polyphenylene oxide (PPO) support membrane and a polysulfone (PSU) support membrane laminated with a polyamide interface polymerization layer, swelled or dissolved significantly in NMP, an organic solvent, indicating that it could not be used in organic solvent systems. Furthermore, the NaCl rejection rate also decreased after ethanol immersion treatment, indicating that it was not even resistant to relatively polar ethanol. The separation membrane of Comparative Example 3, which was an amine-modified BrPPO membrane but lacked a polyamide interface polymerization layer, was found to have relatively poor filtration performance in both aqueous and organic solvent systems. In contrast, the composite separation membrane according to the present invention, in which a polyamide interface polymerization layer was laminated onto an amine-modified PPO membrane, showed resistance to both ethanol and NMP, and exhibited good permeability and separation performance in both aqueous and organic solvent systems. Although the composite separation membrane of Example 3 had excellent pure water permeability, its NaCl rejection rate was low, and its PPG400 rejection rate in NMP solvent was also slightly low. Therefore, the pore size of the polyamide layer is thought to be slightly larger than that of the aromatic amine layer, making it more suitable for fractionation of higher molecular weight components. In the data shown in Table 2, the NaCl rejection rate based on electrical conductivity has an accuracy of three significant figures when it is 98% or higher, but there is a relatively large margin of error in the range of 10-90%, so it is shown with two significant figures.

[0113] The present invention provides a composite separation membrane that has excellent resistance to organic solvents and exhibits excellent filtration performance in both aqueous and organic solvent systems, as well as a method for producing the same, and therefore has industrial applicability.

Claims

1. A composite separation membrane comprising a support membrane and a polyamide layer on one or both sides of the support membrane, wherein the support membrane contains a modified polyphenylene oxide having a structural unit represented by formula (I). [In the formula, R 2 and R 3 to R 8 each independently represent a halogeno group selected from the group consisting of chloro, bromo and iodo, or H, 9 R 10 to R 3 to R 8 any one or more of which represent a -NR 9 R 10 group, a halogeno group selected from the group consisting of chloro, bromo and iodo, or H, and the -CR 3 R 4 R 5 group and the -CR 6 R 7 R 8 group may be covalently bonded to the polyamide layer, 9 R 10 and R 1-6 each independently represent H, a C 6-12 aliphatic hydrocarbon group which may have a substituent α, or a C 9 aromatic hydrocarbon group which may have a substituent β, or nitrogen atom, R 10 and R 1-6 together may form a saturated heterocyclic group which may have a substituent β, 1-6 the substituent α represents a substituent selected from a hydroxyl group and an amino group, 1-6 the substituent β represents a substituent selected from a C 9 alkyl group, a C 10 alkoxy group, a hydroxyl group, an amino group, and a C 1-6 aliphatic hydrocarbon group having an amino group. ] 2. The composite separation membrane according to claim 1, wherein the support membrane and the polyamide layer are covalently bonded.

3. The aforementioned -NR 9 R 10 The group is -NH-(C 1-6 The composite separation membrane according to claim 1, wherein the substituent is an alkanediyl substituent α.

4. The aforementioned -NR 9 R 10 The base is NHR 10 group (in the formula, R 10 This includes a hydroxyl group, an amino group, and a C having an amino group. 1-6 C having substituents selected from aliphatic hydrocarbon groups 6-12 The composite separation membrane according to claim 1, wherein the membrane is an aromatic hydrocarbon group.

5. A method for producing a composite separation membrane, comprising the step of substituting the halogen groups of a support membrane containing polyphenylene oxide in which the benzyl positions at positions 2 and 6 are partially substituted with halogen groups, with an amine compound represented by the following formula (II), NR 9 R 10 ... (II) [wherein, R 9 and R 10 These are independently H and C which may have a substituent α. 1-6 C may have an aliphatic hydrocarbon group or a substituent β. 6-12 This indicates an aromatic hydrocarbon group, or a nitrogen atom, R 9 and R 10 These may together form a saturated heterocyclic group which may have substituent β, wherein substituent α represents a substituent selected from a hydroxyl group and an amino group, and substituent β is C 1-6 Alkyl alkyl group, C 1-6 Alkoxy group, hydroxyl group, amino group, and C having an amino group 1-6 A method characterized by comprising the step of laminating a polyamide layer on one or both sides of a support film containing a polyphenylene oxide in which the benzyl positions at positions 2 and 6 are partially substituted with halogen groups or amine compounds represented by formula (II).

6. The method according to claim 5, wherein the polyamide layer is laminated by reacting a polyfunctional amine compound with a polyfunctional acid chloride on one or both sides of the support film.

7. The method according to claim 5, wherein the polyphenylene oxide is a polyphenylene oxide in which the benzyl positions at positions 2 and 6 are partially substituted with bromo groups.

8. The method according to claim 5, wherein the amine compound represented by formula (II) is monoethanolamine.

9. The method according to claim 5, wherein the amine compound represented by formula (II) is phenylenediamine or xylylenediamine.

10. A composite membrane for use as a separation membrane, wherein the composite membrane comprises a support membrane and a polyamide layer, the polyamide layer is laminated on one or both sides of the support membrane, and the support membrane comprises a modified polyphenylene oxide having a structural unit represented by formula (I). [In the formula, R 1 and R 2 R independently represents a halogen group selected from the group consisting of chloro, bromo, and iodine, or H, and R 3 ~R 8 It is independently, -NR 9 R 10 A halogen group selected from the group consisting of a group, chloro, bromo, and iodine, or a group showing H, R 3 ~R 8 If any one or more of the following apply, then -NR 9 R 10 The base is indicated by -CR 3 R 4 R 5 base and -CR 6 R 7 R 8 The group may be covalently bonded to the polyamide layer, R 9 and R 10 These are independently H and C which may have a substituent α. 1-6 C may have an aliphatic hydrocarbon group or a substituent β. 6-12 This indicates an aromatic hydrocarbon group, or a nitrogen atom, R 9 and R 10 These may together form a saturated heterocyclic group which may have substituent β, wherein substituent α represents a substituent selected from a hydroxyl group and an amino group, and substituent β is C 1-6 Alkyl alkyl group, C 1-6 Alkoxy group, hydroxyl group, amino group, and C having an amino group 1-6 This indicates substituents selected from aliphatic hydrocarbon groups.

11. The composite film according to claim 10, wherein the support film and the polyamide layer are covalently bonded.

12. The composite membrane according to claim 10, which is used as a separation membrane in an organic solvent.

13. The aforementioned -NR 9 R 10 The group is -NH-(C 1-6 The composite film according to claim 10, wherein the substituent is alkanediyl-α.

14. The aforementioned -NR 9 R 10 The base is NHR 10 group (in the formula, R 10 This includes a hydroxyl group, an amino group, and a C having an amino group. 1-6 C having substituents selected from aliphatic hydrocarbon groups 6-12 The composite film according to claim 10, which is an aromatic hydrocarbon group.

15. A method for separating a target substance, comprising the step of supplying a liquid sample containing the target substance to a composite membrane, wherein the composite membrane includes a support membrane and a polyamide layer, the polyamide layer is laminated on one or both sides of the support membrane, and the support membrane contains a modified polyphenylene oxide having a structural unit represented by formula (I). [In the formula, 1 R 2 and R 3 independently represent a halogeno group selected from the group consisting of chloro, bromo and iodo, or H, and R 8 to R 9 independently represent a -NR 10 R 3 group, a halogeno group selected from the group consisting of chloro, bromo and iodo, or H, and any one or more of R 8 represent a -NR 9 R 10 group, and the -CR 3 R 4 R 5 [[ID=?]] group and the -CR 6 R 7 R 8 group may be covalently bonded to the polyamide layer, and R 9 and R 10 independently represent H, a C 1-6 aliphatic hydrocarbon group which may have a substituent α, or a C 6-12 for the sake of clarity, the formula should be corrected as follows: 5 5 5 5 [[ID=2?]] 5 [[ID=2?]] 5 [[ID=2?]] 5 [[ID=2?]] 5 [[ID=2?]] 5 [[ID=2?]] 5 [[ID=2?]] 5 [[ID=2?]] 5 [[ID=2?]] 5 [[ID=2?]] 5 [[ID=2?]]<? 5 [[ID=2?]] 5 [[ID=2?]] 5 [[ID=2?]] 5 [[ID=2?]] 5 [[ID=2?]] 5 [[ID=2?]] 5 [[ID=2?]] 5 [[ID=2?]] 5 [[ID=2?]] 5 [[ID=2?]] 5 [[ID=2?]] 5 [[ID=?]] 5 [[ID=?]] 5 [[ID=?]] 5 [[ID=?]] 5 [[ID=?]] 5 [[ID=?]] 5 [[ID=?]] 5 [[ID=?]] 5 [[ID=?]] 5 [[ID=?]] 5 [[ID=?]] 5 [[ID=?]] 5 [[ID=?]] 5 [[ID=?]] 5 [[ID=?]] 5 [[ID=?]] 5 [[ID=?]] 5 [[ID=?]] 5 [[ID=?]] 5 [[ID=?]] 5 [[ID=?]] 5 [[ID=?]] 5 16. The method according to claim 15, wherein the support film and the polyamide layer are covalently bonded.

17. The method according to claim 15, wherein the liquid contains an organic solvent.

18. The aforementioned -NR 9 R 10 The group is -NH-(C 1-6 The method according to claim 15, wherein the substituent is alkanediyl-α.

19. The above-NR 9 R 10 The base is NHR 10 group (in the formula, R 10 This includes a hydroxyl group, an amino group, and a C having an amino group. 1-6 C having substituents selected from aliphatic hydrocarbon groups 6-12 The method according to claim 15, wherein the aromatic hydrocarbon group is represented.

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