Aromatic polysulfone

Abstract

To provide new aromatic polysulfone to which a polar group is introduced.SOLUTION: An aromatic polysulfone has a repeating unit including a structure represented by the following general formula (S-1), and a terminal structure represented by the following general formula (Se-1). Formula (S-1): -ph1-SO2-ph2-O-. In the formula (S-1), ph1 and ph2 are each independently phenylene groups which may have a substituent. Formula (Se-1): (Ra)x-Ar-O-. In the formula (Se-1), Ar represents an aromatic hydrocarbon group which may have a substituent. Ra is a sulfonic acid group or a salt of a sulfonic acid group. x is an integer of 2 or more, and a plurality of Ra may be the same or different.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to aromatic polysulfone.

Background Art

[0002] Aromatic polysulfone has properties such as excellent heat resistance, mechanical properties, electrical properties, and heat water resistance. Therefore, aromatic polysulfone is used in various applications such as the electric and electronic fields, mechanical fields, automotive fields, aircraft fields, and medical and food industrial fields.

[0003]

[0004] In Patent Document 1, an internal pressure type hollow fiber NF membrane using sulfonated polyethersulfone, which is a hydrophilic aromatic polysulfone, has been proposed. This Patent Document 1 discloses an internal pressure type hollow fiber NF membrane composed of a mixture containing sulfonated polyethersulfone and polyethersulfone.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] When using aromatic polysulfone as a material for forming a separation membrane, a high water permeability is required for the separation membrane formed from aromatic polysulfone. High water permeability means that the amount of water permeating through the membrane per unit time is large under a state where a predetermined pressure is applied. In order to obtain a separation membrane with high water permeability, it is necessary to enhance the hydrophilicity of aromatic polysulfone, and improvement has been demanded.

[0007] The present invention has been made in view of such circumstances, and an object thereof is to provide a novel aromatic polysulfone into which a polar group has been introduced.

Means for Solving the Problems

[0008] To solve the above problems, one aspect of the present invention includes the following aspects.

[0009] [1] An aromatic polysulfone having a repeating unit containing a structure represented by the following general formula (S-1) and a terminal structure represented by the following general formula (Se-1). -ph 1 -SO2-ph 2 -O-…(S-1) [In formula (S-1), ph 1 and ph 2 are each independently a phenylene group which may have a substituent.] (Ra) x -Ar-O-…(Se-1) [In formula (Se-1), Ar is an aromatic hydrocarbon group which may have a substituent. Ra is a sulfonic acid group or a salt of a sulfonic acid group. x is an integer of 2 or more, and a plurality of Ra may be the same as or different from each other]

[0010] [2] The aromatic polysulfone according to [1], wherein x is 2.

[0011] [3] The aromatic polysulfone according to [1] or [2], wherein the formula (Se-1) is the following formula (A-1).

Chemical Formula

[0012] [4] The aromatic polysulfone according to any one of [1] to [3], wherein the number of the terminal structures per 100 units of the repeating unit is 0.03 to 40. [Advantages of the Invention]

[0013] According to the present invention, a novel aromatic polysulfone having a polar group introduced therein can be provided. [Embodiments for Carrying Out the Invention]

[0014] [Aromatic Polysulfone] The aromatic polysulfone of the present embodiment has a repeating unit containing a structure represented by the following general formula (S-1) and a terminal structure represented by the following general formula (Se-1). -ph 1 -SO2-ph 2 -O- …(S-1) [In formula (S-1), ph 1 and ph 2 are each independently a phenylene group which may have a substituent.] (Ra) x -Ar-O- …(Se-1) [In formula (Se-1), Ar is an aromatic hydrocarbon group which may have a substituent. Ra is a sulfonic acid group or a salt of a sulfonic acid group. x is an integer of 2 or more, and a plurality of Ra may be the same as or different from each other]

[0015] That is, the aromatic polysulfone has a repeating unit whose main chain contains a structure represented by the above formula (S-1), and has a resin containing a structure represented by the above formula (Se-1) at the terminal of this main chain.

[0016] The aromatic polysulfone may be a single resin or a mixed resin of two or more kinds. When the aromatic polysulfone is a mixed resin, · A mixed resin of two or more kinds of aromatic polysulfones having a structure represented by the above formula (Se-1) at the main chain terminal · A mixed resin of an aromatic polysulfone having a structure represented by the above formula (Se-1) at the main chain terminal and an aromatic polysulfone not having a structure represented by the above formula (Se-1) at the main chain terminal may be any of them.

[0017] (Structure 1 of the main chain) ph in formula (S-1) 1 and ph 2 The phenylene group in may be a p-phenylene group, an m-phenylene group, or an o-phenylene group, but a p-phenylene group is preferred.

[0018] Examples of the substituent that the phenylene group may have include an alkyl group, an aryl group, etc. The number of substituents of the phenylene group is independently 0 to 4, preferably 0 to 2, more preferably 0 to 1, and even more preferably 0. When the phenylene group has a plurality of substituents, the plurality of substituents may be the same or different.

[0019] As the alkyl group, an alkyl group having 1 to 10 carbon atoms is preferred. Specifically, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, a t-butyl group, an n-hexyl group, a 2-ethylhexyl group, an n-octyl group, an n-decyl group, etc. are preferably exemplified.

[0020] As the aryl group, an aryl group having 6 to 20 carbon atoms is preferred. Specifically, a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, a 1-naphthyl group, a 2-naphthyl group, etc. are preferably exemplified.

[0021] More specifically, the aromatic polysulfone has a main chain structure represented by the following formula (S-1-1).

[0022] [Chemical formula] [In the formula, R 1 and R 2 are each independently an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms. n1 and n2 are each independently an integer of 0 to 4. When n1 or n2 is 2 or more, a plurality of R 1 and R2 They may be the same as or different from each other. X is a single bond or a group derived from bisphenol or biphenol. n is an integer of 1 or more.]

[0023] The group derived from bisphenol among Xs is a divalent group obtained by removing hydrogen atoms from two hydroxy groups that bisphenol has. Specifically, groups derived from bisphenol A: (2,2-bis(4-hydroxyphenyl)propane), bisphenol AF: 2,2-bis(4-hydroxyphenyl)hexafluoropropane, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxy-3-methylphenyl)sulfide, and bis(4-hydroxyphenyl)ether are exemplified. Among them, the group derived from bisphenol A is preferable.

[0024] The group derived from biphenol among Xs is a divalent group obtained by removing hydrogen atoms from two hydroxy groups that biphenol has. Specifically, groups derived from 4,4'-biphenol (4,4'-dihydroxybiphenyl), 2,2'-dihydroxybiphenyl, 3,5,3',5'-tetramethyl-4,4'-dihydroxybiphenyl, 2,2'-diphenyl-4,4'-dihydroxybiphenyl, and 4,4'-dihydroxy-p-quaterphenyl are exemplified. Among them, the group derived from 4,4'-biphenol is preferable.

[0025] X is preferably a single bond.

[0026] n is preferably from 5 to 600.

[0027] (Structure of the main chain 2) The aromatic polysulfone may have a repeating unit represented by the following formula (S-2) or a repeating unit represented by the following formula (S-3) in the main chain. -ph 3 -R-ph 4 -O- ···(S-2) -(ph 5 ) n-O- ···(S-3) [In formula (S-2), ph 3 and ph 4 are each independently a phenylene group which may have a substituent. R is an alkylidene group, an oxygen atom or a sulfur atom. In formula (S-3), ph 5 is a phenylene group which may have a substituent. n is an integer of 1 to 3. When n is 2 or more, a plurality of Ph 5 may be the same as or different from each other.]

[0028] ph 3 ph 4 and ph 5 include, respectively, the same groups as the phenylene group which may have a substituent in ph 1 and ph 2 in formula (S-1).

[0029] The above alkylidene group is preferably an alkylidene group having 1 to 5 carbon atoms, and examples thereof include a methylene group, an ethylidene group, an isopropylidene group, a 1-butylidene group and the like.

[0030] In formula (S-3), n is preferably 1 or 2.

[0031] (Structure of the main chain end) The aromatic polysulfone of this embodiment has two or more sulfonic acid groups or salts of sulfonic acid groups at the main chain end (at least one end of the main chain).

[0032] In addition, the "sulfonic acid group" in this specification is synonymous with a sulfo group and a sulfone group, and is "-SO3H".

[0033] Further, the "salt of sulfonic acid group" is a "group in which the sulfonic acid group forms a salt", and is a group in which a hydrogen atom (hydrogen ion) of the sulfonic acid group is replaced by another monovalent cation (-SO3X (X is a monovalent cation)). The "salt of sulfonic acid group" includes salts of sulfonic acid groups and bases (inorganic bases or organic bases).

[0034] In the following description, the sulfonic acid group and the salt of the sulfonic acid group may be collectively referred to as "Ra" used in formula (Se-1).

[0035] Examples of the salt of the sulfonic acid group and an inorganic base include alkali metal salts such as sodium salt and potassium salt, and ammonium salt. Examples of the salt of the sulfonic acid group and an organic base include imidazolium salt and pyridinium salt.

[0036] Examples of the imidazolium salt include N,N'-dialkylimidazolium salts such as 1-methylimidazolium salt, 1-ethyl-3-methylimidazolium salt, 1-propyl-3-methylimidazolium salt, 1-methyl-3-octylimidazolium salt, 1-decyl-3-methylimidazolium salt, 1-dodecyl-3-methylimidazolium salt, 1-methyl-3-dodecylimidazolium salt, 1-tetradecyl-3-methylimidazolium salt, 1-methyl-3-tetradecylimidazolium salt, 1-hexadecyl-3-methylimidazolium salt, 1-hexadecyl-4-methylimidazolium salt, 1-methyl-3-hexadecylimidazolium salt, and 1-dodecyl-2-methyl-3-benzylimidazolium salt.

[0037] Examples of the pyridinium salt include N-alkylpyridinium salts such as 1-methylpyridinium salt, 1-butyl-4-methylpyridinium salt, 1-laurylpyridinium salt, 1-tetradecylpyridinium salt, 1-hexadecylpyridinium salt, 1-tetradecyl-4-methylpyridinium salt, and 1-hexadecyl-4-methylpyridinium salt.

[0038] As the "salt of the sulfonic acid group", a sodium sulfonate group (-SO2ONa) or a potassium sulfonate group (-SO2OK) is preferable.

[0039] In formula (Se-1), two or more Ra's may be the same or different from each other. Also, two or more Ra's in formula (Se-1) may be only one of either a sulfonic acid group or a salt of a sulfonic acid group, or both.

[0040] The aromatic hydrocarbon group in Ar of formula (Se-1) has at least one aromatic ring. The aromatic ring is not limited as long as it is a cyclic conjugated system having 4n + 2 π electrons, and may be monocyclic or polycyclic. Further, it may be an aromatic heterocyclic ring in which a part of the carbon atoms constituting the ring is substituted with a hetero atom. Examples of the aromatic ring in the aromatic hydrocarbon group include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, and among them, a naphthalene ring is preferable.

[0041] In the terminal structure of the aromatic polysulfone, two Ra's (x = 2 in formula (Se-1)) are preferable.

[0042] Formula (Se-1) is preferably the following formula (A-1).

Chemical formula

[0043] (Amount of aromatic hydrocarbon group having a sulfonic acid group or a salt of a sulfonic acid group) In the following description, the "aromatic hydrocarbon group having a sulfonic acid group or a salt of a sulfonic acid group" possessed at the main chain terminal may be referred to as "FG". (Ra) in formula (Se-1) x -Ar is an example of FG.

[0044] In the present embodiment, the amount of FG of the aromatic polysulfone is determined as the amount of FG per 100 units of the repeating unit forming the main chain (FG ratio. Hereinafter, it may be referred to as "FG amount").

[0045] The amount of FG at the main chain terminal is that of the aromatic polysulfone 1It is calculated from the peak area of 1H-NMR. The specific calculation method is as follows (i) to (v).

[0046] (i) For aromatic polysulfone 1 Perform 1H-NMR measurement, and from the obtained 1 1H-NMR spectrum, determine the peak area A of the hydrogen atoms contained in the repeating unit of the main chain of the aromatic polysulfone. As the peak area A, the peak area of all hydrogen atoms contained in (i-1) repeating units may be determined, or only the peak area of the hydrogen atoms with easy attribution among the hydrogen atoms contained in (i-2) repeating units may be determined.

[0047] (i-2) In the case where, for example, the aromatic ring of the repeating unit is unsubstituted, the peak area of the hydrogen atom at the α-position of the sulfonyl group can be used as the peak area A. Also, when the hydrogen atoms of the aromatic ring of the repeating unit are substituted with methyl groups and the aromatic polysulfone as a whole has no other alkyl groups, the peak area of the hydrogen atoms of the methyl group can be used as the peak area A.

[0048] (ii) Divide the peak area A by the number of hydrogen atoms bonded to the aromatic ring of the main chain to calculate a value corresponding to the number of repeating units (unit number). For example, when the peak area A is the peak area attributed to 4 hydrogen atoms bonded to the aromatic ring of the main chain, divide the peak area A by 4. When the hydrogen atoms of the aromatic ring of the main chain are substituted with methyl groups and the peak area A is the peak area attributed to the hydrogen atoms of the methyl group, divide the peak area A by "3 × the number of methyl groups bonded to the aromatic ring".

[0049] (iii) From the above 1 1H-NMR spectrum, determine the peak area B attributed to the α-hydrogen of Ra in the aromatic ring at the main chain end of the aromatic polysulfone. As the peak area B, the peak area of all hydrogen atoms located at the α-position of Ra in the aromatic ring at the main chain end may be determined, or only the peak area of the hydrogen atoms with easy attribution among the hydrogen atoms located at the α-position of Ra may be determined.

[0050] (iii-2) In the case where, for example, in the aromatic ring at the main chain end, the carbon atom to which the α-hydrogen of Ra is bonded is sandwiched between the carbon atoms to which two Ra's are respectively bonded and the α-hydrogen is common to the two Ra's, the α-hydrogen is affected by the two Ra's. As a result, the peak of the α-hydrogen is considered to be separated from the peaks of other α-hydrogens and appears at a lower magnetic field, and the area of the peak appearing at this lower magnetic field can be defined as peak area B.

[0051] (iv) By dividing the peak area B by the number of α-hydrogens, a value corresponding to the number of FG's is calculated. When the peak area B is the peak area attributed to two α-hydrogens, the peak area B is divided by 2. In the example of (iii-2) above, there is one α-hydrogen common to two FG's.

[0052] (v) By dividing the value obtained in (iv) by the value obtained in (ii) and further multiplying by 100 (unit), the amount of FG per 100 units of the repeating unit forming the main chain of the aromatic polysulfone can be calculated.

[0053] 1 As the measurement solvent in the 1H-NMR measurement, any deuterated solvent capable of dissolving the aromatic polysulfone may be used, and deuterated dimethyl sulfoxide is preferred. When deuterated dimethyl sulfoxide is used as the measurement solvent 1 Examples of the measurement conditions for 1H-NMR include the following. In the NMR sample, the concentration of the aromatic polysulfone to be measured is, for example, 80 mg / mL. (Measurement conditions) Measuring device: ECZ400S (manufactured by JEOL Ltd.) Static magnetic field strength: 9.4 tesla (resonance frequency: 400 MHz ( 1 1H)) Spinning: 15 Hz Repetition time: 7.2 s Number of integrations: 64 times Temperature: Room temperature Internal standard substance: Dimethyl sulfoxide

[0054] For example, when the main chain of an aromatic polysulfone is composed of repeating units represented by the following formula (mc-1) and the main chain end has a structure represented by the following formula (e-1), the amount of FG per 100 units of the repeating units of the aromatic polysulfone is calculated by the calculation method shown below.

[0055] In the following formula, Xp is the peak area attributed to the "hydrogen atom at the α-position of the sulfonyl group" (hydrogen atom Hx) in the formula (mc-1). Also, Yp is the peak area attributed to the "hydrogen atom at the α-position of the sulfonate group" (hydrogen atom Hy) in the formula (e-1) (aromatic ring at the main chain end). Amount of FG = [Yp / (Xp / 4)] × 100 = Yp / Xp × 400

[0056]

Chemical formula

[0057]

Chemical formula

[0058] The amount of FG at the main chain end of the aromatic polysulfone is preferably 0.03 to 40, more preferably 0.06 to 20, still more preferably 0.1 to 10, and particularly preferably 2.0 to 6.0 per 100 units of the repeating units. That is, the number of aromatic hydrocarbon groups contained in the formula (Se-1) is preferably 0.03 to 40, more preferably 0.06 to 20, still more preferably 0.1 to 10, and particularly preferably 2.0 to 6.0 per 100 units of the repeating units of the aromatic polysulfone.

[0059] When the aromatic polysulfone is a mixed resin of two or more types, the amount of FG determined by the above method for the mixed resin is preferably 0.03 to 40, more preferably 0.06 to 20, still more preferably 0.1 to 10, and particularly preferably 2.0 to 6.0.

[0060] When the aromatic polysulfone is a single resin, the amount of FG can be controlled by adjusting the amount of the compound having FG used in the production method of aromatic polysulfone (described later) and the amount of the base used in the production method of aromatic polysulfone.

[0061] When the aromatic polysulfone is a mixed resin of two or more kinds, the amount of FG can be controlled by adjusting the mixing ratio of the aromatic polysulfone having FG at the main chain end and the aromatic polysulfone not having FG at the main chain end.

[0062] (Molecular weight) The weight average molecular weight (Mw) of the aromatic polysulfone is preferably from 1000 to 150000, more preferably from 8000 to 130000, still more preferably from 10000 to 70000, and even more preferably from 15000 to 22000.

[0063] The weight average molecular weight can be determined by gel permeation chromatography (GPC) analysis under the following measurement conditions. The weight average molecular weight of the aromatic polysulfone means the value determined in terms of standard polystyrene based on the calibration curve obtained by measuring the molecular weight of standard polystyrene.

[0064] (Measurement sample) Eluent: N,N-dimethylformamide solution containing 10 mmol / L lithium bromide. Preparation of sample: Dissolve the aromatic polysulfone so that it becomes 0.050 g of the aromatic polysulfone with respect to 10 mL of the eluent, and filter off the insoluble matter (potassium chloride) with a PTFE membrane filter having a pore size of 0.45 μm.

[0065] (Measurement conditions) Sample injection volume: 10 μL. Column (stationary phase): Connect two "TSKgel SuperHZM-M" (4.6 mm Φ × 150 mm) manufactured by Tosoh Corporation in series. Column temperature: 40 °C. Eluent (mobile phase): N,N-dimethylformamide solution containing 10 mmol / L lithium bromide. Eluent flow rate: 0.35 mL / min. Detector: UV detector (detection wavelength: 300 nm). Molecular weight standard: Standard polystyrene.

[0066] [Porous membrane] The aromatic polysulfone of the present embodiment is particularly suitable as a material for forming a separation membrane. By having a plurality of sulfonic acid groups or salts of sulfonic acid groups, which are polar groups, at the main chain terminals, the separation membrane formed using the above aromatic polysulfone can be expected to have higher hydrophilicity and lower surface charge compared to a separation membrane made of an aromatic polysulfone having one sulfonic acid group or a salt of sulfonic acid group at the main chain terminal.

[0067] The separation membrane formed using the aromatic polysulfone of the present embodiment is considered to have relatively improved water permeability and fouling resistance. Here, fouling means an irreversible decrease in membrane performance, for example, it means that clogging (blockage) of the separation membrane occurs.

[0068] The porous membrane can be formed, for example, by applying an 18% by mass NMP solution of aromatic polysulfone onto one surface of a 3 mm thick glass plate with a clearance of 200 μm using a film applicator in an environment of 35% humidity and room temperature of 22°C, leaving the coating film for 9.5 minutes, and then immersing it in water at 25°C.

[0069] Regarding the surface charge of the porous membrane, it can be evaluated by measuring the zeta potential by the following method.

[0070] (Measurement of zeta potential) The surface charge (zeta potential) of the porous membrane is measured by the streaming current method under the following measurement conditions. The measurement is carried out on the membrane surface that was on the air interface side during film formation. (Measurement conditions) Apparatus: Zeta potential analyzer for solid surface analysis (SurPASS3, manufactured by Anton Paar) Measurement temperature: Room temperature Measurement cell: Variable gap cell Measured pH: Around pH 7 Electrolyte: 1 mmol / L KCl Number of measurements: Measure the same sample twice

[0071] The zeta potential (ζ) is calculated by the following formula (1) and taken as the average value of the two measurement results.

[0072] [Equation] [U: Streaming potential, p: Liquid delivery pressure, η: Electrolyte viscosity, ε: Relative permittivity of the electrolyte, ε0: Vacuum permittivity, κ B : Electrical conductivity of the electrolyte]

[0073] A porous membrane with a relatively small zeta potential can be expected to be a porous membrane with excellent fouling resistance.

[0074] The material of the porous membrane may be a resin composition containing the above-mentioned aromatic polysulfone and a filler.

[0075] (Filler) Examples of the filler include fibrous fillers, plate-like fillers, spherical fillers, powdery fillers, and irregularly shaped fillers.

[0076] Examples of the fibrous filler include glass fiber, PAN-based carbon fiber, pitch-based carbon fiber, silica alumina fiber, silica fiber, alumina fiber, other ceramic fibers, liquid crystal polymer (LCP) fiber, aramid fiber, polyethylene fiber, etc. Also, whiskers such as wollastonite and potassium titanate fiber are included.

[0077] Examples of the plate-like filler include talc, mica, graphite, and wollastonite. The plate-like filler may be surface-treated or untreated. Examples of mica include natural mica such as muscovite, phlogopite, fluorophlogopite, and tetrasilicate mica, and synthetic mica manufactured artificially.

[0078] Examples of the spherical filler include glass beads and glass balloons.

[0079] Examples of the powdery filler include calcium carbonate, dolomite, clay, barium sulfate, titanium oxide, carbon black, conductive carbon, and fine silica.

[0080] Examples of the irregularly shaped filler include glass flakes and glass fibers with an irregular cross-section.

[0081] The content of the filler in the resin composition is preferably 0 to 250 parts by mass, more preferably 0 to 70 parts by mass, still more preferably 0 to 50 parts by mass, and particularly preferably 0 to 25 parts by mass, based on 100 parts by mass of the aromatic polysulfone.

[0082] (Optional component) The above resin composition may contain optional components other than the above-described aromatic polysulfone and filler. Examples of the optional components include resins other than the above-described aromatic polysulfone, organic solvents, colorants, lubricants, various surfactants, antioxidants, heat stabilizers, other various stabilizers, ultraviolet absorbers, antistatic agents, and the like.

[0083] (Resin other than aromatic polysulfone) Examples of the resin other than aromatic polysulfone include polyamide, polyester, polyphenylene sulfide, polycarbonate, polyphenylene ether, aromatic polyketone, polyetherimide, phenol resin, epoxy resin, polyimide resin, and modified products thereof.

[0084] (Organic solvent) Examples of the organic solvent include sulfoxides such as dimethyl sulfoxide; amides such as dimethylformamide, dimethylacetamide, and N-methyl-2-pyrrolidone; sulfones such as sulfolane (1,1-dioxothiolane), dimethyl sulfone, diethyl sulfone, diisopropyl sulfone, and diphenyl sulfone; and 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, and the like.

[0085] [Method for producing aromatic polysulfone] The method for producing an aromatic polysulfone includes a step of reacting an aromatic polysulfone precursor having a halogen atom at the main chain terminal with a compound having an FG to produce an aromatic polysulfone having an FG at the main chain terminal.

[0086] One embodiment of the method for producing an aromatic polysulfone includes a step of preparing an aromatic polysulfone precursor having a halogen atom at the main chain terminal (step (i)), and a step of reacting the aromatic polysulfone precursor with a compound having an FG to produce an aromatic polysulfone having an FG at the main chain terminal (step (ii)).

[0087] (Step (i)) The aromatic polysulfone precursor has a repeating unit represented by the following general formula (S-1) in the main chain and has a halogen atom at the main chain terminal. -ph 1 -SO2-ph 2 -O- …(S-1)

[0088] The aromatic polysulfone precursor may be synthesized by the method described later or may be a commercially available product.

[0089] Examples of commercially available products of the aromatic polysulfone precursor include Sumikaexcel (registered trademark) PES 3600P, 4800P, 5900P (all are polyethersulfone, all manufactured by Sumitomo Chemical Co., Ltd.), and the like.

[0090] The weight average molecular weight of the aromatic polysulfone precursor is preferably from 1,000 to 200,000, more preferably from 8,000 to 150,000, and even more preferably from 10,000 to 100,000.

[0091] The weight average molecular weight can be measured by the method described above.

[0092] (Method for producing aromatic polysulfone precursor) The aromatic polysulfone precursor can be produced by using a halogenoaromatic sulfone compound having 2 or 3 halogen atoms bonded thereto, a dihydroxyaromatic compound, etc. as monomers and subjecting these monomers to a polycondensation reaction in an organic solvent in the presence of a base.

[0093] (Monomers) The halogenoaromatic sulfone compound is a compound having an aromatic ring, a sulfonyl group, and 2 or 3 halogen atoms bonded to the aromatic ring in one molecule. The dihydroxyaromatic compound is a compound having an aromatic ring and 2 hydroxy groups bonded to the aromatic ring in one molecule. The halogenoaromatic sulfone compound and the dihydroxyaromatic compound correspond to the repeating units constituting the aromatic polysulfone precursor.

[0094] The aromatic polysulfone precursor can be produced by using a compound represented by the following formula (mx-1) as the halogenoaromatic sulfone compound and a compound represented by the following formula (my-1) as the dihydroxyaromatic compound. X 1 -ph 1 -SO2-ph 2 -(X 2 ) m ···(mx-1) HO-ph 1 -SO2-ph 2 -OH ···(my-1) [In formula (mx-1), ph 1 and ph 2is, independently of each other, a phenylene group which may have a substituent. X 1 and X 2 are, independently of each other, a halogen atom. m is 1 or 2. In formula (my-1), ph 1 and ph 2 are, independently of each other, a phenylene group which may have a substituent. ]

[0095] ph in formula (mx-1) and (my-1) 1 and ph 2 are the same as ph 1 and ph 2 in the above general formula (S-1).

[0096] In formula (mx-1), X 1 and X 2 are, independently of each other, a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a chlorine atom is preferred.

[0097] Examples of the compound represented by formula (mx-1) include 4,4'-dichlorodiphenyl sulfone, 4,4'-difluorodiphenyl sulfone, and 4-chlorophenyl-3',4'-dichlorophenyl sulfone.

[0098] Examples of the compound represented by formula (my-1) include bis(4-hydroxyphenyl) sulfone, bis(4-hydroxy-3,5-dimethylphenyl) sulfone, and bis(4-hydroxy-3-phenylphenyl) sulfone.

[0099] When the aromatic polysulfone precursor further has a repeating unit containing the structure represented by the above formula (S-2), a compound represented by the following formula (my-2) is used as the dihydroxy aromatic compound. HO-ph 3 -R-ph 4 -OH ···(my-2) [In formula (my-2), ph 3 and ph 4Each is independently a phenylene group which may have a substituent. R is an alkylidene group, an oxygen atom or a sulfur atom.

[0100] In formula (my-2), ph 3 , ph 4 and R are the same as ph 3 , ph 4 and R in formula (S-2) described above, respectively.

[0101] Examples of the compound represented by formula (my-2) include bisphenol A: (2,2-bis(4-hydroxyphenyl)propane), bisphenol AF: 2,2-bis(4-hydroxyphenyl)hexafluoropropane, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxy-3-methylphenyl)sulfide, and bis(4-hydroxyphenyl)ether.

[0102] When the aromatic polysulfone precursor further has a repeating unit containing the structure represented by formula (S-3) described above, as the dihydroxy aromatic compound, a compound represented by the following formula (my-3) is used. HO-(ph 5 ) n -OH ···(my-3) [In formula (my-3), ph 5 is a phenylene group which may have a substituent. n is an integer of 1 to 3. When n is 2 or more, a plurality of ph5 may be the same as or different from each other. ]]

[0103] In formula (my-3), ph 5 and n are the same as ph 5 and n in formula (S-3) described above, respectively.

[0104] Examples of the compound represented by formula (my-3) include hydroquinone, resorcinol, catechol, phenylhydroquinone, 4,4'-dihydroxybiphenyl, 2,2'-dihydroxybiphenyl, 3,5,3',5'-tetramethyl-4,4'-dihydroxybiphenyl, 2,2'-diphenyl-4,4'-dihydroxybiphenyl, 4,4'''-dihydroxy-p-quaterphenyl, and the like.

[0105] In the production of the aromatic polysulfone precursor, depending on the type of the target aromatic polysulfone, either one of the halogenated aromatic sulfone compound and the dihydroxy aromatic compound may be used alone, or two or more thereof may be used in combination.

[0106] (Base, organic solvent) The polycondensation of the halogenated aromatic sulfone compound and the dihydroxy aromatic compound is preferably carried out using an alkali metal salt of carbonic acid or an alkali metal hydroxide as the base. Further, the polycondensation is preferably carried out in an organic solvent. More preferably, the polycondensation is carried out using an alkali metal salt of carbonic acid or an alkali metal hydroxide as the base and in an organic solvent.

[0107] Examples of the alkali metal hydroxide include potassium hydroxide, sodium hydroxide, cesium hydroxide, etc. The hydroxide may be an anhydride, a hydrate, or a mixture thereof.

[0108] The alkali metal salt of carbonic acid may be an alkali metal carbonate, a bicarbonate (hydrogen carbonate of an alkali metal), or a mixture thereof.

[0109] Examples of the alkali metal carbonate include sodium carbonate, potassium carbonate, cesium carbonate, etc. Examples of the bicarbonate include sodium bicarbonate (sodium hydrogen carbonate), potassium bicarbonate (potassium hydrogen carbonate), cesium bicarbonate (cesium hydrogen carbonate), etc.

[0110] The organic solvent is preferably an aprotic polar solvent. The boiling point of the organic solvent is preferably 100°C or higher and 400°C or lower, and more preferably 100°C or higher and 350°C or lower.

[0111] Examples of such organic solvents include sulfoxides such as dimethyl sulfoxide; amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; sulfones such as sulfolane (1,1-dioxothiolane), dimethyl sulfone, diethyl sulfone, diisopropyl sulfone, and diphenyl sulfone; 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, and the like.

[0112] The organic solvent may be used alone or in combination of two or more.

[0113] The reaction temperature of the polycondensation is preferably 180°C or higher and 400°C or lower, and the reaction time is preferably 4 to 10 hours.

[0114] (Step (ii)) In the present embodiment, a compound represented by the following formula (A) is used as the compound having FG (hereinafter sometimes referred to as a terminal capping agent). (Ra) x -Ar-(OM) y …(A) [In formula (A), Ar is an aromatic hydrocarbon group which may have a substituent. Ra is a sulfonic acid group or a salt of a sulfonic acid group. x is an integer of 2 or more. y is 1 or 2. M is a hydrogen atom or a monovalent cation]

[0115] The compound represented by formula (A) has two or more sulfonic acid groups or salts of sulfonic acid groups in the molecule. Ra and Ar in formula (A) are the same as Ra and Ar in the above formula (Se-1).

[0116] Examples of the cation in M include alkali metal ions and cations of organic bases such as imidazolium ions and pyridinium ions.

[0117] The end-capping agent is a compound represented by formula (A), and is not particularly limited as long as FG can be introduced at the main chain ends of the aromatic polysulfone precursor. Examples of the end-capping agent include the following compounds.

[0118] · Monohydroxy compounds 2-Hydroxy-6,8-naphthalenedisulfonic acid and its salts 3-Hydroxy-2,7-naphthalenedisulfonic acid and its salts 3-Hydroxy-2,6-naphthalenedisulfonic acid and its salts 5-Hydroxy-1,3-benzenedisulfonic acid and its salts 7-Hydroxy-1,3,6-naphthalenetrisulfonic acid and its salts

[0119] · Dihydroxy compounds 6,8-Dihydroxy-1,3-pyrenedisulfonic acid and its salts 3,6-Dihydroxy-2,7-naphthalenedisulfonic acid and its salts 2,2'-Dihydroxy-1,1'-binaphthyl-6,6'-disulfonic acid and its salts 4,5-Dihydroxy-1,3-benzenedisulfonic acid and its salts

[0120] (Aprotic organic solvent) Examples of the aprotic organic solvent used in the production of the aromatic polysulfone include the aprotic polar solvents exemplified in the above (Production method of the aromatic polysulfone precursor).

[0121] (Alkali metal salts) As the alkali metal salt used in the production of aromatic polysulfone, the bases exemplified in the above (method for producing an aromatic polysulfone precursor) can be mentioned. As the alkali metal salt, sodium salt, potassium salt, and cesium salt are preferable, and potassium salt is more preferable.

[0122] (Phase transfer catalyst) The aromatic polysulfone of the present embodiment may be produced using a phase transfer catalyst when reacting the above-mentioned aromatic polysulfone precursor with a terminal capping agent. By using a phase transfer catalyst, there may be cases where even a terminal capping agent with poor reactivity can react with the aromatic polysulfone precursor.

[0123] Examples of the phase transfer catalyst include quaternary ammonium salts such as tetrabutylammonium chloride, crown ethers such as 18-crown-6-ether, and phosphonium compounds such as tetraphenylphosphonium bromide.

[0124] The reaction temperature in the step of reacting the aromatic polysulfone precursor with the terminal capping agent is preferably 100°C or higher and less than 300°C.

[0125] The reaction time of the above step is preferably 4 to 15 hours.

[0126] The amount of the terminal capping agent used in the above step is preferably 0.1 to 50 parts by mass, and more preferably 0.6 to 25 parts by mass, based on 100 parts by mass of the aromatic polysulfone precursor.

[0127] The amount of the alkali metal salt used in the above step is preferably 0.3 to 30 parts by mass, and more preferably 0.4 to 10 parts by mass, based on 100 parts by mass of the aromatic polysulfone precursor.

[0128] In step (ii), in addition to the above-described aromatic polysulfone precursor, terminal capping agent, alkali metal salt, etc., a halogenoaromatic sulfone compound or a dihydroxyaromatic compound may be added as an optional component. As the halogenoaromatic sulfone compound, the compounds exemplified by the above formula (mx-1) can be used. As the dihydroxyaromatic compound, the compounds exemplified by the formula (my-1) can be used.

[0129] As described above, according to the present invention, a novel aromatic polysulfone having a polar group introduced therein can be provided.

[0130] As described above, the preferred embodiments of the present invention have been described, but the present invention is not limited to such examples. Combinations of the respective configurations shown in the above examples are merely examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

Examples

[0131] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0132] · Polyethersulfone (PES) PES1: Manufactured by Sumitomo Chemical Co., Ltd., Sumikaexcel PES3600P PES2: Manufactured by Sumitomo Chemical Co., Ltd., Sumikaexcel PES5900P PES3: Manufactured by Sumitomo Chemical Co., Ltd., Sumikaexcel PES4100P

[0133] · Phase transfer catalyst Catalyst 1: 18-Crown-6-ether (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0134] · Alkali metal salt K2CO3: Potassium carbonate

[0135] · Solvent NMP: N-Methyl-2-pyrrolidone

[0136] ·Dihalogeno aromatic sulfone compound DCDPS: 4,4'-Dichlorodiphenyl sulfone

[0137] [Example 1] Into a polymerization tank equipped with a stirrer, a nitrogen inlet tube, a thermometer, and a condenser with a receiver at the tip, PES1 (100 g), dipotassium 2-hydroxy-6,8-naphthalenedisulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.) (7.87 g, 20 mmol), K2CO3 (1.79 g), DCDPS (1.80 g), Catalyst 1 (5.00 g) and NMP (150 g) were added and mixed. The resulting mixture was heated at 200 °C and reacted for 10 hours. Dipotassium 2-hydroxy-6,8-naphthalenedisulfonate is a terminal capping agent and is a compound represented by the above formula (A).

[0138] Next, the obtained reaction solution was cooled to room temperature (25 °C) to precipitate unreacted potassium carbonate and by-produced potassium chloride. The reaction solution (slurry) in which the salt had precipitated was dropped into water to precipitate an aromatic polysulfone, and unnecessary NMP was removed by filtration to obtain a precipitate.

[0139] The obtained precipitate was carefully washed repeatedly with methanol and water and dried by heating at 150 °C to obtain, as a product, aromatic polysulfone 1 having a polar group (a salt of a sulfonic acid group containing a sulfonic acid group and a potassium sulfonate group) derived from the capping agent used at the main chain terminals.

[0140] [Example 2] Aromatic polysulfone 2 was obtained in the same manner as in Example 1, except that PES3 was used instead of PES1, and the amounts of reagents used were 3.15 g (8.3 mmol) of dipotassium 2-hydroxy-6,8-naphthalenedisulfonate, 0.71 g of K2CO3, 0 g (not used) of DCDPS, and 2.08 g of Catalyst 1.

[0141] [Comparative Example 1] Instead of dipotassium 2-hydroxy-6,8-naphthalenedisulfonate, 4.06 g (20 mmol) of sodium 4-hydroxybenzenesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.) was used, and aromatic polysulfone C1 was obtained in the same manner as in Example 1 except that Catalyst 1 was not used. Sodium 4-hydroxybenzenesulfonate is a terminal capping agent but is not the compound represented by the above formula (A).

[0142] [Comparative Example 2] PES2 was heated and dried at 150 °C to obtain the aromatic polysulfone of Comparative Example 2.

[0143] [Comparative Example 3] Instead of dipotassium 2-hydroxy-6,8-naphthalenedisulfonate, 1.62 g (8.3 mmol) of sodium 4-hydroxybenzenesulfonate was used, and aromatic polysulfone C2 was obtained in the same manner as in Example 2 except that Catalyst 1 was not used.

[0144] [Calculation of the amount of FG per 100 units of the repeating unit of aromatic polysulfone] For the aromatic polysulfones obtained in the examples and comparative examples, a sample was prepared by dissolving them in deuterated dimethyl sulfoxide so that the concentration of the aromatic polysulfone to be measured was 80 mg / ml, and 1 1H-NMR was measured. (Measurement conditions) Measuring device: ECZ400S (manufactured by JEOL) Static magnetic field strength: 9.4 tesla (resonance frequency: 400 MHz ( 1 1H)) Spinning: 15 Hz Repetition time: 7.2 s Number of integrations: 64 times Temperature: 25 °C Chemical shift standard substance: dimethyl sulfoxide

[0145] From the obtained NMR spectrum, the following two peak areas were determined. Xp: The peak area attributed to "the hydrogen atom at the α-position of the sulfonyl group" in the general formula (S-1). The integrated value from 7.17 to 7.34 ppm. Yp: The peak area attributed to "the hydrogen atom at the α-position of the sulfonate group" in the aromatic ring at the main chain end of the aromatic polysulfone. When using dipotassium 2-hydroxy-6,8-naphthalenedisulfonate, the integrated value from 8.48 to 8.53 ppm. When using sodium 4-hydroxybenzenesulfonate, the integrated value from 7.00 to 7.07 ppm.

[0146] Using the obtained peak area, the amount of FG was calculated based on the following formulas (a1) and (a2). · Examples 1 and 2 Amount of FG = [Yp / (Xp / 4)]×100 = Yp / Xp×400 …(a1) · Comparative Examples 1 and 3 Amount of FG = [(Yp / 2) / (Xp / 4)]×100 = Yp / Xp×200 …(a2)

[0147] [Measurement of molecular weight] The weight average molecular weight (Mw) of the aromatic polysulfone based on polystyrene was measured by the method described in the above [Measurement of molecular weight].

[0148] The evaluation results are shown in Table 1 below.

[0149]

Table 1

[0150] [Preparation of porous membrane] In a heating container, a mixture with the composition shown in Table 2 below was stirred at 80 °C for 2 hours to obtain a pale yellow solution. The numerical values in Table 2 represent "parts by mass". Also, PES2 was used after being pre-heated and dried at 150 °C.

[0151]

Table 2

[0152] The obtained solution was applied to one surface of a 3-mm-thick glass plate with a clearance of 200 μm using a film applicator under an environment of 25 to 45% humidity and a room temperature of 22°C. After leaving the coating film for 9.5 minutes, it was immersed in water at 25°C to form a porous membrane of aromatic polysulfone.

[0153] The obtained porous material was peeled off from the glass plate, washed several times with water, and then stored in water.

[0154] [Measurement of zeta potential] For the prepared porous membrane, the zeta potential was measured by the method described in the above (Measurement of zeta potential).

[0155] The evaluation results are shown in Table 3 below. The FG amount shown in the table is the FG amount per 100 units of the repeating unit of the total PES used for the preparation of the porous membrane. In Example 1 and Comparative Example 1, since the aromatic polysulfone 1 and the aromatic polysulfone C1 used were diluted with PES2, respectively, the numerical values are different from those shown in Table 1.

[0156]

Table 3

[0157] The aromatic polysulfone 1 in Example 1 has more sulfonic acid groups in the terminal capping agent used than the aromatic polysulfone C1 in Comparative Example 1. Therefore, although the FG amount of the aromatic polysulfone 1 in Example 1 is smaller than that of the aromatic polysulfone C1 in Comparative Example 1, it was confirmed that the porous membrane in Example 1 shows a lower surface charge than the porous membrane in Comparative Example 1.

[0158] In addition, in the aromatic polysulfone with a terminal capping agent introduced at the molecular chain end, the molecular weight decreases as the introduction amount of the terminal capping material increases. Therefore, when increasing the FG amount in the aromatic polysulfone, the molecular weight relatively decreases, which may reduce the mechanical strength of the formed porous membrane.

[0159] Therefore, when an aromatic polysulfone with an increased amount of FG was further prepared from the aromatic polysulfone C1 of Comparative Example 1 and a porous membrane was produced, even if the surface charge became equivalent to that of the porous membrane of Example 1, it is considered that the membrane strength decreased and the porous membrane became relatively easy to break.

[0160] In contrast, although the aromatic polysulfone 1 of Example 1 has almost the same molecular weight as the aromatic polysulfone C1 of Comparative Example 1, it was confirmed that the porous membrane of Example 1 exhibits a lower surface charge than the porous membrane of Comparative Example 1. Therefore, it is considered that the porous membrane of Example 1 is a porous membrane having an excellent balance between mechanical strength and surface charge compared to the porous membrane of Comparative Example 1.

[0161] In addition, it was confirmed that the porous membrane produced using the aromatic polysulfone 1 of Example 1 also exhibits a lower surface charge compared to the porous membrane produced using PES2 of Comparative Example 2 which was not reacted with the end-capping agent.

[0162] Therefore, it is expected that the porous membrane of Example 1 has higher fouling resistance than the porous membranes of Comparative Examples 1 and 2.

[0163] Similarly, the aromatic polysulfone 2 of Example 2 has more sulfonic acid groups in the end-capping agent used than the aromatic polysulfone C2 of Comparative Example 3. Therefore, although the amount of FG in the aromatic polysulfone 2 of Example 2 is smaller than that of the aromatic polysulfone C2 of Comparative Example 3, it was confirmed that the porous membrane of Example 2 exhibits a lower surface charge than the porous membrane of Comparative Example 3.

[0164] In addition, although the aromatic polysulfone 2 of Example 2 has almost the same molecular weight as the aromatic polysulfone C2 of Comparative Example 3, it was confirmed that the porous membrane of Example 2 exhibits a lower surface charge than the porous membrane of Comparative Example 3. Therefore, it is expected that the porous membrane of Example 2 has higher fouling resistance than the porous membrane of Comparative Example 3.

[0165] From the above results, it was confirmed that the present invention is useful.

Claims

1. An aromatic polysulfone having a repeating unit containing a structure represented by the following general formula (S-1) and a terminal structure represented by the following general formula (Se-1). -ph １ -SO ２ -ph ２ -O- …(S-1) [In formula (S-1), ph １ and ph ２ are each independently a phenylene group which may have a substituent.] (Ra) ｘ -Ar-O- …(Se-1) [In formula (Se-1), Ar is an aromatic hydrocarbon group which may have a substituent. Ra is a sulfonic acid group or a salt of a sulfonic acid group. x is an integer of 2 or more, and a plurality of Ra may be the same as or different from each other.]

2. The aromatic polysulfone according to Claim 1, wherein x is 2.

3. The aromatic polysulfone according to Claim 1 or 2, wherein the formula (Se-1) is the following formula (A-1). 【Chemical Formula 1】 [In the formula, M is a hydrogen atom or a monovalent cation.]

4. The aromatic polysulfone according to Claim 1 or 2, wherein the number of the aromatic hydrocarbon groups contained in the formula (Se-1) is 0.03 to 40 per 100 units of the repeating unit.

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