Aromatic polysulfone

Abstract

Provided is an aromatic polysulfone having both a repeating unit including a structure represented by general formula (S-1) and a terminal structure represented by general formula (Se-1). (S-1): -ph1-SO2-ph2-O- [In formula (S-1), ph1 and ph2 are each independently an optionally substituted phenylene group.] (Se-1): (Ra)x-Ar-O- [In formula (Se-1), Ar is an optionally substituted aromatic hydrocarbon group, Ra is a sulfonic acid group or a salt of a sulfonic acid group, x is an integer of 2 or larger, and the plurality of Ra moieties may be the same as or different from each other.]

Description

Aromatic Polysulfone

[0001] This application claims priority from Japanese Patent Application No. 2023-205619, filed December 5, 2023, the contents of which are incorporated herein by reference.

[0002] Aromatic polysulfone has excellent properties such as heat resistance, mechanical properties, electrical properties, and hot water resistance, and is therefore used in a variety of applications in the fields of electrical and electronics, machinery, automobiles, aircraft, medical and food industries, etc.

[0003] Depending on the application, hydrophilized aromatic polysulfone is required. Specific examples of such hydrophilized aromatic polysulfone include aromatic polysulfone having a polar group.

[0004] Patent Document 1 proposes an internal pressure type hollow fiber NF membrane using sulfonated polyethersulfone, which is a hydrophilized aromatic polysulfone, and discloses an internal pressure type hollow fiber NF membrane made of a mixture containing sulfonated polyethersulfone and polyethersulfone.

[0005] JP 2013-215640 A

[0006] When aromatic polysulfone is used as a material for forming a separation membrane, the separation membrane formed from the aromatic polysulfone is required to have high water permeability. High water permeability means that a large amount of water permeates the membrane per unit time under a given applied pressure. To obtain a separation membrane with high water permeability, it is necessary to increase the hydrophilicity of the aromatic polysulfone, and improvements have been sought.

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

[0008] In order 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): １ -SO ２ -ph ２ -O-...(S-1) [In formula (S-1), ph １ and ph ２ each independently represents a phenylene group which may have a substituent.] (Ra) ｘ -Ar-O-...(Se-1) [In formula (Se-1), Ar represents an aromatic hydrocarbon group which may have a substituent. Ra represents a sulfonic acid group or a salt of a sulfonic acid group. x represents an integer of 2 or more, and multiple Ra may be the same or different.]

[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): [wherein M is a hydrogen atom or a monovalent cation]

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

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

[0014] In the following description, when a numerical range is described as, for example, "A to B," it means "A or more and B or less," including the lower limit A and the upper limit B.

[0015] [Aromatic Polysulfone] The aromatic polysulfone of the present embodiment 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): １ -SO ２ -ph ２ -O- ... (S-1) [In formula (S-1), ph １ and ph ２each independently represents a phenylene group which may have a substituent.] (Ra) ｘ —Ar—O— (Se-1) [In formula (Se-1), Ar represents an aromatic hydrocarbon group which may have a substituent. Ra represents a sulfonic acid group or a salt of a sulfonic acid group. x represents an integer of 2 or more, and multiple Ra may be the same or different.]

[0016] That is, the aromatic polysulfone has a main chain having a repeating unit containing the structure represented by the above formula (S-1), and has a resin containing the structure represented by the above formula (Se-1) at the end of this main chain.

[0017] The aromatic polysulfone may be a single type of resin or a mixed resin of two or more types. When the aromatic polysulfone is a mixed resin, it may be any of: a mixed resin of two or more types of aromatic polysulfones having the structure represented by the above formula (Se-1) at the main chain terminal; or a mixed resin of an aromatic polysulfone having the structure represented by the above formula (Se-1) at the main chain terminal and an aromatic polysulfone not having the structure represented by the above formula (Se-1) at the main chain terminal.

[0018] (Main Chain Structure 1) Ph of 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 is preferably a p-phenylene group.

[0019] Examples of the substituent that the phenylene group may have include an alkyl group, an aryl group, etc. The number of substituents that the phenylene group has is each independently 0 to 4, preferably 0 to 2, more preferably 0 to 1, and even more preferably 0. When the phenylene group has multiple substituents, the multiple substituents may be the same or different.

[0020] The alkyl group is preferably an alkyl group having 1 to 10 carbon atoms. Specific examples of suitable alkyl groups include 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, and an n-decyl group.

[0021] The aryl group may be an aryl group having 6 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, or an aryl group having 6 to 10 carbon atoms. Specific preferred examples include a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, a 1-naphthyl group, and a 2-naphthyl group.

[0022] More specifically, the aromatic polysulfone has a main chain structure represented by the following formula (S-1-1): In the repeating unit of the main chain structure represented by the following formula (S-1-1), the remainder excluding X corresponds to the structure represented by the above general formula (S-1).

[0023] [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 R ２ may be the same or different. X is a single bond or a group derived from bisphenol or biphenol. n is an integer of 1 or more.

[0024] The group derived from bisphenol in X is a divalent group obtained by removing hydrogen atoms from two hydroxy groups of bisphenol. Specific examples include 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. Of these, the group derived from bisphenol A is preferred.

[0025] Of X, the group derived from biphenol is a divalent group obtained by removing hydrogen atoms from two hydroxy groups of biphenol. Specific examples include 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. Of these, the group derived from 4,4'-biphenol is preferred.

[0026] X is preferably a single bond.

[0027] n is preferably 5 to 600.

[0028] (Main Chain Structure 2) The aromatic polysulfone may have a repeating unit containing a structure represented by the following formula (S-2) or a structure represented by the following formula (S-3) in the main chain. 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 or different from each other.

[0029] ph ３ , ph ４ and ph ５ are the ph in formula (S-1), respectively. １ and ph ２ Examples of the phenylene group include the same groups as the optionally substituted phenylene group in the above formula (1).

[0030] The 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, and a 1-butylidene group.

[0031] In formula (S-3), n is preferably 1 or 2.

[0032] (Structure of Main Chain Terminal) The aromatic polysulfone of this embodiment has two or more sulfonic acid groups or salts of sulfonic acid groups at the main chain terminal (at least one end of the main chain).

[0033] In this specification, the term "sulfonic acid group" has the same meaning as a sulfo group or a sulfone group, and "-SO ３ H".

[0034] Furthermore, a "salt of a sulfonic acid group" is a "group in which a sulfonic acid group forms a salt," and is a group in which the hydrogen atom (hydrogen ion) of the sulfonic acid group is substituted with another monovalent cation (-SO ３ X (X is a monovalent cation). The "salt of a sulfonic acid group" includes a salt of a sulfonic acid group with a base (an inorganic base or an organic base).

[0035] 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).

[0036] Examples of salts of sulfonic acid groups with inorganic bases include alkali metal salts such as sodium salts and potassium salts, and ammonium salts. Examples of salts of sulfonic acid groups with organic bases include imidazolium salts and pyridinium salts.

[0037] 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.

[0038] Examples of pyridinium salts 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.

[0039] The "salt of sulfonic acid group" includes sodium sulfonate group (-SO ２ ONa) or potassium sulfonate group (-SO ２ OK) is preferred.

[0040] The two or more Ra in formula (Se-1) may be the same or different from each other. Furthermore, the two or more Ra in formula (Se-1) may be either a sulfonic acid group or a salt of a sulfonic acid group, or both.

[0041] The aromatic hydrocarbon group for Ar in 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. It may also be an aromatic heterocycle in which some of the carbon atoms constituting the ring are substituted with heteroatoms. 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 these, a naphthalene ring is preferred.

[0042] In the terminal structure of the aromatic polysulfone, Ra is preferably two (x=2 in formula (Se-1)).

[0043] Formula (Se-1) is preferably the following formula (A-1): [wherein M is a hydrogen atom or a monovalent cation]

[0044] (Amount of aromatic hydrocarbon group having sulfonic acid group or salt of sulfonic acid group) In the following description, the "aromatic hydrocarbon group having sulfonic acid group or salt of sulfonic acid group" at the main chain terminal may be referred to as "FG". (Ra) in formula (Se-1) ｘ -Ar is an example of FG.

[0045] In this embodiment, the amount of FG in the aromatic polysulfone is determined as the amount of FG per 100 repeating units forming the main chain (FG ratio; hereinafter, sometimes referred to as "FG amount").

[0046] The amount of FG at the main chain end is determined by the amount of the aromatic polysulfone. １ It is calculated from the peak area of ​​H-NMR. Specific calculation methods are as follows (i) to (v).

[0047] (i) Aromatic polysulfone １ H-NMR measurement was carried out, and the obtained １ The peak area A of hydrogen atoms contained in the repeating units of the main chain of the aromatic polysulfone is determined from the H-NMR spectrum. As the peak area A, the peak area of ​​all hydrogen atoms contained in the repeating unit (i-1) may be determined, or only the peak area of ​​easily attributable hydrogen atoms among the hydrogen atoms contained in the repeating unit (i-2) may be determined.

[0048] In (i-2), for example, when 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 taken as the peak area A. Furthermore, when the hydrogen atom of the aromatic ring of the repeating unit is substituted with a methyl group and the aromatic polysulfone as a whole has no other alkyl groups, the peak area of ​​the hydrogen atom of the methyl group can be taken as the peak area A.

[0049] (ii) The peak area A is divided 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 (number of units). For example, if the peak area A is the peak area attributable to four hydrogen atoms bonded to the aromatic ring of the main chain, the peak area A is divided by 4. If 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 attributable to the hydrogen atoms of the methyl groups, the peak area A is divided by "3 × the number of methyl groups bonded to the aromatic ring."

[0050] (iii) the above １ From the H-NMR spectrum, the peak area B assigned to the α hydrogen of Ra in the aromatic ring at the main chain terminal of the aromatic polysulfone is determined. As the peak area B, (iii-1) the peak area of ​​all hydrogen atoms located at the α position of Ra in the aromatic ring at the main chain terminal may be determined, or (iii-2) only the peak area of ​​hydrogen atoms that are easily assigned among the hydrogen atoms located at the α position of Ra may be determined.

[0051] In (iii-2), for example, if the carbon atom to which the α-hydrogen of Ra is bonded in the aromatic ring at the end of the main chain is sandwiched between carbon atoms to which two Ra are bonded, and the α-hydrogen is common to the two Ra, the α-hydrogen is influenced by the two Ra. As a result, the peak of the α-hydrogen is thought to appear in a low magnetic field, separate from the peaks of the other α-hydrogens, and the area of ​​this peak appearing in a low magnetic field can be defined as peak area B.

[0052] (iv) The value corresponding to the number of FGs is calculated by dividing the peak area B by the number of α-hydrogens. If 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 the two FGs.

[0053] (v) The amount of FG per 100 repeating units forming the main chain of the aromatic polysulfone can be calculated by dividing the value obtained in (iv) by the value obtained in (ii) and then multiplying the result by 100 (units).

[0054] １ ​The measurement solvent in the H-NMR measurement may be any heavy solvent that can dissolve aromatic polysulfone, and deuterated dimethyl sulfoxide is preferred. １ The measurement conditions for H-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) Measurement device: ECZ400S (manufactured by JEOL) Static magnetic field strength: 9.4 Tesla (resonance frequency: 400 MHz ( １ H) Spinning: 15 Hz Repetition time: 7.2 seconds Number of accumulations: 64 Temperature: room temperature Internal standard substance: dimethyl sulfoxide

[0055] 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 terminal has a structure represented by the following formula (e-1), the FG amount per 100 repeating units of the aromatic polysulfone is calculated by the calculation method shown below.

[0056] In the following formula, Xp is the peak area assigned to the "hydrogen atom at the α-position of the sulfonyl group" (hydrogen atom Hx) in formula (mc-1). Yp is the peak area assigned to the "hydrogen atom at the α-position of the sulfonate group" (hydrogen atom Hy) in formula (e-1) (aromatic ring at the end of the main chain). FG amount = [Yp / (Xp / 4)] x 100 = Yp / Xp x 400

[0057]

[0058]

[0059] The amount of FG at the main chain terminal of the aromatic polysulfone per 100 repeating units is preferably 0.03 to 40, more preferably 0.06 to 20, even more preferably 0.1 to 10, and particularly preferably 2.0 to 6.0. That is, the number of aromatic hydrocarbon groups contained in formula (Se-1) per 100 repeating units of the aromatic polysulfone is preferably 0.03 to 40, more preferably 0.06 to 20, even more preferably 0.1 to 10, and particularly preferably 2.0 to 6.0.

[0060] In the case of a mixed resin containing two or more types of aromatic polysulfone, the FG amount of the mixed resin determined by the above-mentioned method is preferably 0.03 to 40, more preferably 0.06 to 20, even more preferably 0.1 to 10, and particularly preferably 2.0 to 6.0.

[0061] When 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.

[0062] In the case of a mixed resin containing two or more types of aromatic polysulfone, the amount of FG can be controlled by adjusting the mixing ratio of aromatic polysulfone having FG at the main chain end to aromatic polysulfone not having FG at the main chain end.

[0063] (Molecular Weight) The weight average molecular weight (Mw) of the aromatic polysulfone is preferably 1,000 to 150,000, more preferably 8,000 to 130,000, even more preferably 10,000 to 70,000, and still more preferably 15,000 to 22,000.

[0064] 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 refers to a value determined in terms of standard polystyrene based on a calibration curve obtained by measuring the molecular weight of standard polystyrene.

[0065] (Measurement sample) Eluent: N,N-dimethylformamide solution containing 10 mmol / L lithium bromide. Sample preparation: 0.050 g of aromatic polysulfone was dissolved in 10 mL of the eluent, and the insoluble matter (potassium chloride) was filtered off using a PTFE membrane filter with a pore size of 0.45 μm.

[0066] (Measurement conditions) Sample injection volume: 10 μL. Column (stationary phase): Two "TSKgel Super HZM-M" columns (4.6 mm diameter x 150 mm) manufactured by Tosoh Corporation were connected 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.

[0067] [Porous Membrane] The aromatic polysulfone of this embodiment is particularly suitable as a material for forming a separation membrane. By having a plurality of polar groups, such as sulfonic acid groups or salts of sulfonic acid groups, at the ends of the main chain, a separation membrane formed using the aromatic polysulfone is expected to have higher hydrophilicity and a lower surface charge, i.e., a more negative surface charge, than a separation membrane made from an aromatic polysulfone having one sulfonic acid group or salt of a sulfonic acid group at the end of the main chain.

[0068] It is believed that separation membranes formed using the aromatic polysulfone of this embodiment have relatively improved water permeability and fouling resistance. Here, fouling refers to an irreversible decrease in membrane performance, for example, the occurrence of blockage (clogging) of the separation membrane. Separation membranes with low surface charge, i.e., those with a relatively large negative surface charge, are expected to suppress clogging by fouling substances due to electrical interactions.

[0069] The porous membrane can be formed, for example, by applying an 18% by mass NMP solution of aromatic polysulfone to 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.

[0070] The surface charge of the porous membrane can be evaluated by measuring the zeta potential by the following method.

[0071] (Measurement of Zeta Potential) The surface charge (zeta potential) of the porous membrane is measured by a streaming current method under the following measurement conditions. The measurement is performed on the membrane surface that was on the air interface side during membrane formation. (Measurement Conditions) Apparatus: Zeta potential analyzer for solid surface analysis (SurPASS3, manufactured by Anton Paar) Measurement temperature: Room temperature (25°C) Measurement cell: Variable gap cell Measurement pH: Around pH 7 Electrolyte: KCl 1 mmol / L Number of measurements: Measure the same sample twice

[0072] The zeta potential (ζ) is calculated by the following formula (1) and is the average value of two measurements.

[0073] [U: streaming potential, p: liquid supply pressure, η: electrolyte viscosity, ε: electrolyte relative permittivity, ε ０ :Vacuum permittivity, κ Ｂ : Electrical conductivity of the electrolyte]

[0074] A porous membrane with a relatively small zeta potential and a larger negative surface charge is expected to be a porous membrane with excellent fouling resistance.

[0075] The material of the porous membrane may be a resin composition containing the above-mentioned aromatic polysulfone and a filler.

[0076] (Filler) Examples of the filler include fibrous fillers, plate-like fillers, spherical fillers, powdery fillers, irregularly shaped fillers, and the like.

[0077] Examples of fibrous fillers include glass fibers, PAN-based carbon fibers, pitch-based carbon fibers, silica-alumina fibers, silica fibers, alumina fibers, other ceramic fibers, liquid crystal polymer (LCP) fibers, aramid fibers, polyethylene fibers, etc. Also included are whiskers such as wollastonite and potassium titanate fibers.

[0078] Examples of the platy filler include talc, mica, graphite, and wollastonite. The platy filler may be surface-treated or untreated. Examples of the mica include natural micas such as muscovite, phlogopite, fluorophlogopite, and tetrasilicic mica, as well as artificially produced synthetic micas.

[0079] Examples of spherical fillers include glass beads and glass balloons.

[0080] Examples of powder fillers include calcium carbonate, dolomite, clay barium sulfate, titanium oxide, carbon black, conductive carbon, and fine silica.

[0081] Examples of irregularly shaped fillers include glass flakes and irregular cross-section glass fibers.

[0082] 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, even more preferably 0 to 50 parts by mass, and particularly preferably 0 to 25 parts by mass, per 100 parts by mass of the aromatic polysulfone.

[0083] (Optional Components) The resin composition may contain optional components other than the aromatic polysulfone and filler described above. Examples of optional components include resins other than the aromatic polysulfone described above, organic solvents, colorants, lubricants, various surfactants, antioxidants, heat stabilizers, various other stabilizers, ultraviolet absorbers, antistatic agents, etc.

[0084] (Resins Other Than Aromatic Polysulfone) Examples of resins other than aromatic polysulfone include polyamide, polyester, polyphenylene sulfide, polycarbonate, polyphenylene ether, aromatic polyketone, polyetherimide, phenolic resin, epoxy resin, polyimide resin, and modified products thereof.

[0085] (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-dioxothiane), dimethyl sulfone, diethyl sulfone, diisopropyl sulfone, and diphenyl sulfone; 1,3-dimethyl-2-imidazolidinone, and 1,3-diethyl-2-imidazolidinone.

[0086] [Method for Producing Aromatic Polysulfone] The method for producing aromatic polysulfone includes a step of reacting an aromatic polysulfone precursor having a halogen atom at the main chain terminal with a compound having FG to produce aromatic polysulfone having FG at the main chain terminal.

[0087] One embodiment of the method for producing aromatic polysulfone includes the steps of: preparing an aromatic polysulfone precursor having a halogen atom at the main chain terminal (step (i)); and reacting the aromatic polysulfone precursor with a compound having FG to produce aromatic polysulfone having FG at the main chain terminal (step (ii)).

[0088] (Step (i)) The aromatic polysulfone precursor has a repeating unit containing a structure represented by the following general formula (S-1) in its main chain and has a halogen atom at the end of the main chain: １ -SO ２ -ph ２ -O-...(S-1)

[0089] The aromatic polysulfone precursor may be one synthesized by the method described below, or may be a commercially available product.

[0090] Commercially available aromatic polysulfone precursors include, for example, Sumikaexcel (registered trademark) PES 3600P, 4800P, and 5900P (all polyethersulfones, all manufactured by Sumitomo Chemical Co., Ltd.).

[0091] The weight average molecular weight of the aromatic polysulfone precursor is preferably 1,000 to 200,000, more preferably 8,000 to 150,000, and even more preferably 10,000 to 100,000.

[0092] The weight average molecular weight can be measured by the method described above.

[0093] (Method for Producing Aromatic Polysulfone Precursor) The aromatic polysulfone precursor can be produced by using a halogenoaromatic sulfone compound having two or three halogen atoms bonded thereto, a dihydroxyaromatic compound, or the like as a monomer, and subjecting these monomers to a polycondensation reaction in an organic solvent in the presence of a base.

[0094] (Monomer) A halogenoaromatic sulfone compound is a compound having an aromatic ring, a sulfonyl group, and two or three halogen atoms bonded to the aromatic ring in one molecule. A dihydroxyaromatic compound is a compound having an aromatic ring and two 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.

[0095] The aromatic polysulfone precursor can be produced by using a compound represented by the following formula (mx-1) as the halogeno aromatic sulfone compound and a compound represented by the following formula (my-1) as the dihydroxy aromatic compound. １ -ph １ -SO ２ -ph ２ -(X ２ ) ｍ ...(mx-1) HO-ph １ -SO ２ -ph ２ -OH...(my-1) [in formula (mx-1), ph １ and ph ２ are each independently a phenylene group which may have a substituent. １ and X ２ are each independently a halogen atom, and m is 1 or 2. In formula (my-1), ph １ and ph ２ are each independently a phenylene group which may have a substituent.

[0096] Ph in formulas (mx-1) and (my-1) １ and ph２ is the ph in the above general formula (S-1). １ and ph ２ is the same as:

[0097] In formula (mx-1), X １ and X ２ are each independently 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.

[0098] 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.

[0099] 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.

[0100] 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: ３ -R-ph ４ -OH...(my-2) [in formula (my-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.

[0101] In formula (my-2), ph ３ , ph ４ and R is the ph in the above formula (S-2). ３ , ph ４ and R, respectively.

[0102] 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.

[0103] When the aromatic polysulfone precursor further has a repeating unit containing the structure represented by the above formula (S-3), a compound represented by the following formula (my-3) is used as the dihydroxy aromatic compound. 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, multiple ph5s may be the same or different.

[0104] In formula (my-3), ph ５ and n is the ph in the above formula (S-3). ５ and n, respectively.

[0105] 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, and 4,4'''-dihydroxy-p-quaterphenyl.

[0106] In the production of an aromatic polysulfone precursor, either one type of halogeno aromatic sulfone compound or one type of dihydroxy aromatic compound may be used alone or in combination, depending on the type of aromatic polysulfone desired.

[0107] (Base, Organic Solvent) The polycondensation of a halogenoaromatic sulfone compound and a dihydroxyaromatic compound is preferably carried out using an alkali metal carbonate or an alkali metal hydroxide as a base. The polycondensation is also preferably carried out in an organic solvent. It is more preferable that the polycondensation is carried out using an alkali metal carbonate or an alkali metal hydroxide as a base and in an organic solvent.

[0108] Examples of alkali metal hydroxides include potassium hydroxide, sodium hydroxide, cesium hydroxide, etc. The hydroxides may be anhydrous or hydrated, or may be a mixture thereof.

[0109] The alkali metal carbonate may be an alkali carbonate (an alkali metal carbonate), an alkali bicarbonate (an alkali metal hydrogen carbonate), or a mixture thereof.

[0110] Examples of alkali carbonates include sodium carbonate, potassium carbonate, cesium carbonate, etc. Examples of alkali bicarbonates include sodium bicarbonate (sodium hydrogen carbonate), potassium bicarbonate (potassium hydrogen carbonate), cesium bicarbonate (cesium hydrogen carbonate), etc.

[0111] The organic solvent is preferably an aprotic polar solvent, and 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.

[0112] 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-dioxothiane), dimethyl sulfone, diethyl sulfone, diisopropyl sulfone, and diphenyl sulfone; and 1,3-dimethyl-2-imidazolidinone and 1,3-diethyl-2-imidazolidinone.

[0113] The organic solvent may be used alone or in combination of two or more kinds.

[0114] The polycondensation reaction temperature is preferably 180° C. or higher and 400° C. or lower, and the reaction time is preferably 4 to 10 hours.

[0115] (Step (ii)) In this embodiment, a compound represented by the following formula (A) is used as a compound having FG (hereinafter, sometimes referred to as an end capping agent): (Ra) ｘ -Ar-(OM) ｙ ...(A) [In formula (A), Ar represents an aromatic hydrocarbon group which may have a substituent. Ra represents a sulfonic acid group or a salt of a sulfonic acid group. x represents an integer of 2 or more. y represents 1 or 2. M represents a hydrogen atom or a monovalent cation]

[0116] 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 formula (Se-1) above.

[0117] Examples of the cation in M ​​include alkali metal ions and cations of organic bases such as imidazolium ions and pyridinium ions.

[0118] The end-capping agent is a compound represented by formula (A), and is not particularly limited as long as it can introduce FG into the main chain terminal of the aromatic polysulfone precursor. Examples of the end-capping agent include the following compounds:

[0119] 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

[0120] Dihydroxy compounds 6,8-dihydroxy-1,3-pyrene disulfonic 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

[0121] (Aprotic Organic Solvent) Examples of the aprotic organic solvent used in the production of aromatic polysulfone include the aprotic polar solvents exemplified above in (Method for producing aromatic polysulfone precursor).

[0122] (Alkali Metal Salt) Examples of the alkali metal salt used in the production of aromatic polysulfone include the bases exemplified above in (Method for producing aromatic polysulfone precursor). As the alkali metal salt, sodium salt, potassium salt, and cesium salt are preferred, and potassium salt is more preferred.

[0123] (Phase Transfer Catalyst) The aromatic polysulfone of this embodiment may be produced by using a phase transfer catalyst during the reaction between the aromatic polysulfone precursor and the end-capping agent. By using a phase transfer catalyst, even an end-capping agent with poor reactivity may be able to react with the aromatic polysulfone precursor.

[0124] 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.

[0125] The reaction temperature in the step of reacting the aromatic polysulfone precursor with the end-capping agent is preferably 100°C or higher and lower than 300°C.

[0126] The reaction time for the above step is preferably 4 to 15 hours.

[0127] The amount of the end-capping agent used in the above step is preferably 0.1 to 50 parts by mass, more preferably 0.6 to 25 parts by mass, per 100 parts by mass of the aromatic polysulfone precursor.

[0128] The amount of the alkali metal salt used in the above step is preferably 0.3 to 30 parts by mass, more preferably 0.4 to 10 parts by mass, per 100 parts by mass of the aromatic polysulfone precursor.

[0129] In step (ii), in addition to the aromatic polysulfone precursor, end-capping agent, alkali metal salt, etc., a halogenoaromatic sulfone compound or a dihydroxyaromatic compound may be added as an optional component. The halogenoaromatic sulfone compound may be a compound listed in formula (mx-1) above. The dihydroxyaromatic compound may be a compound listed in formula (my-1).

[0130] As described above, according to the present invention, a novel aromatic polysulfone having a polar group introduced therein can be provided.

[0131] Although the preferred embodiment of the present invention has been described above, the present invention is not limited to these examples. The combinations of the components shown in the above examples are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention.

[0132] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0133] Polyethersulfone (PES) PES1: Sumikaexcel PES3600P, manufactured by Sumitomo Chemical Co., Ltd. PES2: Sumikaexcel PES5900P, manufactured by Sumitomo Chemical Co., Ltd. PES3: Sumikaexcel PES4100P, manufactured by Sumitomo Chemical Co., Ltd.

[0134] Phase transfer catalyst Catalyst 1: 18-crown-6-ether (Tokyo Chemical Industry Co., Ltd.)

[0135] ・Alkali metal salt K ２ CO ３ : Potassium carbonate

[0136] Solvent: NMP: N-methyl-2-pyrrolidone

[0137] Dihalogenoaromatic sulfone compounds DCDPS: 4,4'-dichlorodiphenyl sulfone

[0138] Example 1 In a polymerization vessel equipped with a stirrer, a nitrogen inlet tube, a thermometer, and a condenser with a receiver attached to the tip, PES1 (100 g), dipotassium 2-hydroxy-6,8-naphthalenedisulfonate (Tokyo Chemical Industry Co., Ltd.) (7.87 g, 20 mmol), K ２ CO ３ (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 to 200°C and reacted for 10 hours. Dipotassium 2-hydroxy-6,8-naphthalenedisulfonate is an end-capping agent and is the compound represented by formula (A) above.

[0139] The resulting reaction solution was then cooled to room temperature (25°C) to precipitate unreacted potassium carbonate and by-produced potassium chloride. The reaction solution (slurry) from which the salts had precipitated was added dropwise to water to precipitate aromatic polysulfone, and unnecessary NMP was removed by filtration to obtain a precipitate.

[0140] The obtained precipitate was thoroughly washed repeatedly with methanol and water and dried by heating at 150°C, thereby obtaining, as a product, aromatic polysulfone 1 having polar groups (sulfonic acid groups and salts of sulfonic acid groups including potassium sulfonate groups) derived from the capping agent used at the main chain terminals.

[0141] [Example 2] 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 and 3.15 g (8.3 mmol) of K ２ CO ３ An aromatic polysulfone 2 was obtained in the same manner as in Example 1, except that 0.71 g of , 0 g (not used) of DCDPS, and 2.08 g of catalyst 1 were used.

[0142] Comparative Example 1 Aromatic polysulfone C1 was obtained in the same manner as in Example 1, except that 4.06 g (20 mmol) of sodium 4-hydroxybenzenesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of dipotassium 2-hydroxy-6,8-naphthalenedisulfonate and that catalyst 1 was not used. Sodium 4-hydroxybenzenesulfonate is an end-capping agent, but is not the compound represented by formula (A) above.

[0143] Comparative Example 2 PES2 was dried by heating at 150° C. to obtain aromatic polysulfone of Comparative Example 2.

[0144] Comparative Example 3 An aromatic polysulfone C2 was obtained in the same manner as in Example 2, except that 1.62 g (8.3 mmol) of sodium 4-hydroxybenzenesulfonate was used instead of dipotassium 2-hydroxy-6,8-naphthalenedisulfonate and that catalyst 1 was not used.

[0145] [Calculation of FG amount per 100 repeating units of aromatic polysulfone] The aromatic polysulfones obtained in the examples and comparative examples were dissolved in deuterated dimethyl sulfoxide to prepare samples so that the concentration of the aromatic polysulfone to be measured was 80 mg / ml. The samples were then analyzed under the following measurement conditions: １ H-NMR was measured. (Measurement conditions) Measurement device: ECZ400S (manufactured by JEOL) Static magnetic field strength: 9.4 Tesla (resonance frequency: 400 MHz ( １ H) Spinning: 15 Hz Repetition time: 7.2 seconds Number of accumulations: 64 Temperature: 25°C Chemical shift standard: dimethyl sulfoxide

[0146] The following two peak areas were determined from the obtained NMR spectrum. Xp: Peak area assigned to the "hydrogen atom at the α-position of the sulfonyl group" in the above general formula (S-1). Integrated value from 7.17 to 7.34 ppm. Yp: Peak area assigned to the "hydrogen atom at the α-position of the sulfonate group" in the aromatic ring at the main chain terminal of the aromatic polysulfone. When dipotassium 2-hydroxy-6,8-naphthalenedisulfonate was used, the integrated value was from 8.48 to 8.53 ppm. When sodium 4-hydroxybenzenesulfonate was used, the integrated value was from 7.00 to 7.07 ppm.

[0147] The FG amount was calculated using the obtained peak area according to the following formulas (a1) and (a2): Examples 1 and 2: FG amount = [Yp / (Xp / 4)] x 100 = Yp / Xp x 400 (a1) Comparative Examples 1 and 3: FG amount = [(Yp / 2) / (Xp / 4)] x 100 = Yp / Xp x 200 (a2)

[0148] [Measurement of Molecular Weight] The weight average molecular weight (Mw) of the aromatic polysulfone based on polystyrene was measured by the method described in [Measurement of Molecular Weight] above.

[0149] The evaluation results are shown in Table 1 below.

[0150]

[0151] [Preparation of porous membrane] A mixture having the composition shown in Table 2 below was stirred in a heating vessel at 80°C for 2 hours to obtain a pale yellow solution. The values ​​in Table 2 represent "parts by mass." The PES2 used was pre-dried by heating at 150°C.

[0152]

[0153] 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 in an environment of 25 to 45% humidity and room temperature of 22° C. The coating film was left to stand for 9.5 minutes and then immersed in water at 25° C. to form a porous film of aromatic polysulfone.

[0154] The resulting porous membrane was peeled off from the glass plate, washed several times with water, and then stored in water.

[0155] [Measurement of Zeta Potential] The zeta potential of the prepared porous membrane was measured by the method described above in (Measurement of Zeta Potential).

[0156] The evaluation results are shown in Table 3 below. The FG amount shown in the table is the FG amount per 100 repeating units of the entire PES used to produce the porous membrane. In Example 1 and Comparative Example 1, the aromatic polysulfone 1 and aromatic polysulfone C1 used, respectively, were diluted with PES2, so the values ​​are different from those shown in Table 1.

[0157]

[0158] The aromatic polysulfone 1 of Example 1 has more sulfonic acid groups in the end capping agent used than the aromatic polysulfone C1 of Comparative Example 1. Therefore, although the aromatic polysulfone 1 of Example 1 has a smaller FG amount than 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.

[0159] Furthermore, in aromatic polysulfones in which an end-capping agent has been introduced at the molecular chain ends, the molecular weight decreases as the amount of the end-capping agent increases. Therefore, when the amount of FG is increased in aromatic polysulfones, the molecular weight decreases relatively, which may reduce the mechanical strength of the porous membranes formed.

[0160] Therefore, when an aromatic polysulfone having a larger amount of FG than the aromatic polysulfone C1 of Comparative Example 1 is prepared and a porous membrane is produced, even if the surface charge becomes equivalent to that of the porous membrane of Example 1, the membrane strength will be reduced and the porous membrane will be relatively more susceptible to breakage.

[0161] In contrast, although the aromatic polysulfone 1 of Example 1 has a molecular weight almost equal to that of 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 a better balance between mechanical strength and surface charge than the porous membrane of Comparative Example 1.

[0162] It was also confirmed that the porous membrane prepared using aromatic polysulfone 1 of Example 1 exhibited a lower surface charge than the porous membrane prepared using PES2 of Comparative Example 2, which was not reacted with an end-capping agent.

[0163] Therefore, the porous membrane of Example 1 is expected to have higher fouling resistance than the porous membranes of Comparative Examples 1 and 2.

[0164] 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 aromatic polysulfone 2 of Example 2 has a smaller FG amount than 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.

[0165] Furthermore, although the aromatic polysulfone 2 of Example 2 has a molecular weight almost equal to 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. Therefore, the porous membrane of Example 2 is expected to have higher fouling resistance than the porous membrane of Comparative Example 3.

[0166] 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): １ -SO ２ -ph ２ -O- ... (S-1) [In formula (S-1), ph １ and ph ２ each independently represents a phenylene group which may have a substituent. 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 multiple Ra may be the same or different.] 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): [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 repeating units.

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