JP2022002839A - Porous membrane - Google Patents

Abstract

To provide a porous membrane where water permeability is enhanced.SOLUTION: A porous membrane contains aromatic polysulfone having an amino group.SELECTED DRAWING: None

Description

The present invention relates to a porous membrane.

Aromatic polysulfone has excellent heat resistance, flame retardancy, creep resistance, dimensional stability, heat resistance and water resistance, chemical resistance, durability (high strength and high elongation), and biocompatibility. Therefore, aromatic polysulfone is used in various applications such as electrical and electronic fields, mechanical fields, automobile fields, aircraft fields, and medical food industry fields.
The aromatic polysulfone is also used as a material for a porous membrane (aromatic polysulfone porous membrane).

For example, Patent Document 1 discloses a porous polyether sulfone membrane having a macrovoid layer. The porous polyether sulfone membrane is described as having good material permeability due to its high porosity.

Japanese Patent No. 6624294

In recent years, the applications of aromatic polysulfone porous membranes have further expanded, and the performance required for each application has also increased. For example, there is a demand for an aromatic polysulfone porous membrane having higher water permeability.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a porous membrane having higher water permeability.

As a result of diligent studies to solve the above problems, the present inventors have found that the porous membrane formed of aromatic polysulfone having an amino group is a porous membrane formed of aromatic polysulfone having no amino group. It has been found that the water permeability can be enhanced as compared with the above, and the present invention has been completed.

That is, the present invention has the following aspects.
[1] A porous membrane containing an aromatic polysulfone having an amino group.
[2] The porous membrane according to [1], wherein the aromatic polysulfone having an amino group has an amino group in a part or all of the terminal of the main chain.
[3] The porous membrane according to [1] or [2], further containing an aromatic polysulfone having no amino group.

According to the present invention, it is possible to provide a porous membrane having higher water permeability.

(Porous membrane)
The porous membrane of this embodiment is a membrane having a large number of pores.
The porous membrane of the present embodiment is, for example, a separation membrane that allows molecules smaller than the pore size of the pores to permeate and does not allow molecules larger than the pore size of the pores to permeate. The separation membrane is used, for example, as a separation membrane for artificial dialysis, a separation membrane for treating (filtering) a liquid for water treatment (purification) or the like.

The shape of the porous membrane of the present embodiment is not particularly limited, and for example, a flat membrane, a flat membrane supported by a base material (nonwoven fabric, etc.), a hollow fiber membrane, a tubular membrane, a spiral membrane, a thin film (film), and the like. Can be mentioned.

The membrane structure of the porous membrane of the present embodiment is not particularly limited, and may be, for example, an asymmetric membrane having a macrovoid or a finger-like (finger-like) structure in the center of the membrane, or the entire membrane may be spongy. It may be a film having a uniform structure.

The pore size of the porous membrane of the present embodiment is not particularly limited and is determined by the size of the substance that does not allow permeation.
For example, when the porous membrane of the present embodiment is used as a separation membrane for artificial dialysis, the pore size of the porous membrane is designed to be large enough to prevent erythrocytes, leukocytes, platelets, albumin, complement and the like from permeating. In that case, the pore size of the porous membrane is, for example, 10 nm or less.

When the porous membrane of the present embodiment is used as a separation membrane for liquid treatment, reverse osmosis (RO) membrane, nanofiltration (NF) membrane, and ultrafiltration (ultrafiltration) can be obtained by changing the pore size of the porous membrane. It can be used as a UF) membrane or an ultrafiltration (MF) membrane.

-Reverse osmosis (RO) membrane In the reverse osmosis (RO) membrane, the concentrated solution and the dilute solution are separated by a membrane, and by applying a pressure larger than the osmotic pressure to the concentrated solution side, only water molecules are diluted from the concentrated solution side through the membrane. It is a membrane that is transferred to the solution side to separate ions and low molecular weight organic substances.
When the porous membrane of the present embodiment is a reverse osmosis (RO) membrane, the pore size of the porous membrane is, for example, about 0.002 μm or less.

-Nanofiltration (NF) membrane The nanofiltration (NF) membrane is an intermediate membrane between the reverse osmosis (RO) membrane and the ultrafiltration (UF) membrane described later, and has a hardness component such as calcium and magnesium and a molecular weight. It is a membrane capable of removing more than 200 organic substances such as trihalomethane and pesticides.
When the porous membrane of the present embodiment is a nanofiltration (NF) membrane, the pore size of the porous membrane is, for example, about 0.002 to 0.01 μm.

-Ultrafiltration (UF) membrane An ultrafiltration (UF) membrane is a membrane that separates, fractionates, concentrates, and purifies solutes by sieving at the molecular level according to the pore size of the membrane and the size of the solute molecule. It can isolate polymers such as bacteria, viruses, enzymes and proteins.
When the porous membrane of the present embodiment is an ultrafiltration (UF) membrane, the pore size of the porous membrane is, for example, about 0.01 to 0.1 μm.

-Microfiltration (MF) membrane A microfiltration (MF) membrane is a membrane used to accurately and efficiently separate and purify suspended matter and colloidal particles contained in a liquid.
When the porous membrane of the present embodiment is a microfiltration (MF) membrane, the pore size of the porous membrane is, for example, about 0.01 to 10 μm.

<Aromatic polysulfone with amino group>
The porous membrane of this embodiment contains an aromatic polysulfone having an amino group (hereinafter, also referred to as “PN0”).

The PN0 in the porous membrane of the present embodiment is typically a divalent aromatic group (residue obtained by removing two hydrogen atoms bonded to the aromatic ring from the aromatic compound) and a sulfonyl group (-). It is a resin having a repeating unit containing SO ₂ −) and an oxygen atom (−O−), and has an amino group (−NH ₂ ) in the main chain or at the end of the main chain of the resin.

PN0 preferably has a repeating unit including a structure represented by the following formula (S-1).
−ph ¹ −SO ₂ −ph ² −O − ・ ・ ・ (S-1)
[In the formula, ph ¹ and ph ² are phenylene groups which may independently have a substituent. ]

The phenylene group in ph ¹ and ph ² may be a p-phenylene group, an m-phenylene group, an o-phenylene group, or a p-phenylene group. Is preferable.

Examples of the substituent that the phenylene group may have include an alkyl group, an aryl group, and a halogen atom.
The alkyl group is preferably an alkyl group having 1 to 10 carbon atoms, and 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, and the like. Preferable examples include t-butyl group, n-hexyl group, 2-ethylhexyl group, n-octyl group, n-decyl group and the like.

The aryl group is preferably an aryl group having 6 to 20 carbon atoms, and specifically, a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, a 1-naphthyl group, or a 2-naphthyl group. Etc. are preferably mentioned.

Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

When the hydrogen atom of the phenylene group is substituted with the above-mentioned functional group, the number thereof is preferably 2 or less, more preferably 1 for each phenylene group independently. ..
The hydrogen atom of the phenylene group may or may not be substituted. In this embodiment, it is particularly preferable that it is not substituted.
When PN0 has an amino group in the main chain, the phenylene group has an amino group as a substituent.

In addition to the structure represented by the above formula (S-1), PN0 includes a repeating unit including a structure represented by the following formula (S-2) or a structure represented by the following formula (S-3). But it may be.
−ph ³ −R−ph ⁴ −O− ・ ・ ・ (S-2)
− (Ph ⁵ ) _n −O − ・ ・ ・ (S-3)
[In the formula (S-2), ph ³ and ph ⁴ are phenylene groups which may independently 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, Ph ⁵ there are a plurality, it may be the same or different from each other. ]

Examples of ph ³ , ph ⁴ and ph ⁵ include those similar to the phenylene group which may have a substituent in ^{ph 1} and ph ² in the formula (S-1), respectively.

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.

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

The amino group contained in PN0 may be a group partially composed of an amine derivative. Examples of the group composed of the amine derivative include a group in which an amino group of PN0 and a compound having a carboxy group are condensed to form an amide bond.

PN0 may have an amino group in the main chain and may have an amino group at the end of the main chain, but it is preferable to have an amino group in a part or all of the end of the main chain.
More specifically, PN0 is an aromatic polysulfone having a repeating unit represented by the following formula (S-1-1) and a terminal unit represented by the following formula (Se-1-1). Is preferred.

［式中、Ｒ^１及びＲ^２は、それぞれ独立に、炭素原子数１〜１０のアルキル基、又は炭素原子数６〜２０のアリール基である。ｎ１及びｎ２は、それぞれ独立に、０〜４の整数であり、ｎ１又はｎ２が２以上である場合、複数個のＲ^１及びＲ^２は互いに同一でも異なっていてもよい。Ｘは、単結合又はビスフェノール若しくはビフェノールから誘導される基である。ｎは１以上の整数である。］

[In the formula, R ¹ and R ² are 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, plural ^{R 1} and ^{R 2} may be the same 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. ]

［式中、Ａｒは、置換基を有してもよい芳香族炭化水素基である。Ｒ^１及びＲ^２は、それぞれ独立に、炭素原子数１〜１０のアルキル基、又は炭素原子数６〜２０のアリール基である。ｎ１及びｎ２は、それぞれ独立に、０〜４の整数であり、ｎ１又はｎ２が２以上である場合、複数個のＲ^１及びＲ^２は互いに同一でも異なっていてもよい。＊は結合手を示す。］

[In the formula, Ar is an aromatic hydrocarbon group which may have a substituent. R ¹ and R ² are 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, plural ^{R 1} and ^{R 2} may be the same or different from each other. * Indicates a bond. ]

The alkyl group having 1 to 10 carbon atoms and the aryl group having 6 to 20 carbon atoms in ^{R 1} and R ² in the formulas (S-1-1) and (Se-1-1) are represented by the formula (S). -1) ^{Examples of substituents that the phenylene group in ph 1} and ph ² may have, and similar ones can be mentioned.
In the formulas (S-1-1) and (Se-1-1), n1 and n2 are independently, preferably 0 to 2, more preferably 0 to 1, and even more preferably 0, respectively.

Specifically, the group derived from bisphenol is a divalent group excluding one hydroxy group and the hydrogen atom of the other hydroxy group among the two hydroxy groups of bisphenol. Specifically, bisphenol A: (2,2-bis (4-hydroxyphenyl) propane), bisphenol AF: 2,2-bis (4-hydroxyphenyl) hexafluoropropane, bis (4-hydroxyphenyl) sulfide, Examples thereof include groups derived from bis (4-hydroxy-3-methylphenyl) sulfide and bis (4-hydroxyphenyl) ether, respectively, and among them, a group derived from bisphenol A, that is, two hydroxy groups of bisphenol A. Of the groups, a divalent group excluding one hydroxy group and the hydrogen atom of the other hydroxy group is preferable.

Groups derived from biphenols include 4,4'-biphenol (4,4'-dihydroxybiphenyl), 2,2'-dihydroxybiphenyl, 3,5,3', 5'-tetramethyl-4,4'. Groups derived from -dihydroxybiphenyl, 2,2'-diphenyl-4,4'-dihydroxybiphenyl and 4,4'''-dihydroxy-p-quarterphenyl are listed, respectively, from 4,4'-biphenol. Of the two hydroxy groups of the derived group, that is, 4,4'-biphenol, a divalent group excluding one hydroxy group and the hydrogen atom of the other hydroxy group is preferable.

X is preferably a single bond.

n is preferably 5 to 600.

In the formula (Se-1-1), Ar is the same as Ar in the formula (Se-1).

[Number average absolute molecular weight]
The number average absolute molecular weight of PN0 is preferably 1000 or more, more preferably 2000 or more, and even more preferably 4000 or more.
The number average absolute molecular weight of PN0 is preferably 30,000 or less, more preferably 25,000 or less, and even more preferably 15,000 or less.

When the number average absolute molecular weight of PN0 is at least the above-mentioned preferable lower limit value, the mechanical strength of the porous membrane of the present embodiment is further improved.
Further, for example, when PN0 has an amino group at the end of the main chain, the amount of the terminal amino group per mass can be increased if the number average absolute molecular weight of PN0 is equal to or less than the above-mentioned preferable upper limit value. It becomes easier to increase the water permeability.

For example, the number average absolute molecular weight of PN0 is preferably 1000 or more and 30,000 or less, more preferably 2000 or more and 25,000 or less, and further preferably 4000 or more and 15,000 or less.

As used herein, the number average absolute molecular weight is calculated by gel permeation chromatography (GPC) analysis. The specific calculation method is as follows.
[Measurement condition]
Sample: Add 0.002 g of PN0 to 1 mL of N, N-dimethylformamide solution containing 10 mM lithium bromide.
Sample injection amount: 100 μL.
Column (stationary phase): Two "TSKgel GMHHR-H" (Φ7.8 mm x 300 mm) manufactured by Tosoh Corporation are connected in series.
Column temperature: 40 ° C
Eluent (mobile phase): N, N-dimethylformamide containing 10 mM lithium bromide Eluent flow rate: 0.8 mL / min Detector: Differential refractometer (RI) + multi-angle light scattering photometer (MALS)
Standard reagent: Polystyrene Molecular weight calculation method: Absolute molecular weight is calculated from a multi-angle light scattering photometer (MALS).

[Amino acid group amount]
When PN0 has an amino group at the end of the main chain, the amount of amino groups at the end of the main chain (hereinafter referred to as "amino group amount") calculated from the peak area ratio of ^{1 H-NMR forms PN0.} Per 100 units of repeating units, 0.1 or more is preferable, 0.5 or more is more preferable, 0.7 or more is further preferable, and 1 or more is particularly preferable.
The amount of amino groups is preferably 40 or less, more preferably 10 or less, still more preferably 8 or less, per 100 repeating units forming the main chain of PN0.

In PN0, when the amount of amino groups is at least the above-mentioned preferable lower limit value, the water permeability of the porous membrane of the present embodiment is further improved.
Further, when the amount of amino groups is not more than the above-mentioned preferable upper limit value, the mechanical strength of the porous membrane of the embodiment is further improved.

For example, in PN0, the ^{amount of amino groups calculated from the peak area ratio of 1} H-NMR is preferably 0.1 or more and 40 or less per 100 repeating units forming the main chain of PN0. 5 or more and 10 or less are more preferable, 0.7 or more and 8 or less are further preferable, and 1 or more and 8 or less are particularly preferable.

The amount of amino groups is ^{calculated by 1 1} H-NMR measurement. The specific calculation method is as follows.
(I) In the repeating unit of the main chain of PN0, the peak area A assigned to the hydrogen atom bonded to the aromatic ring of the main chain whose number of hydrogen atoms is already known is ^{determined by 1} H-NMR measurement. ..
(Ii) The number of repeating units (number of units) can be calculated by dividing the peak area A by the number of hydrogen atoms bonded to the aromatic ring of the main chain of PN0 (for example, the peak area A is: If it is the peak area attributed to the four hydrogen atoms bonded to the aromatic ring of the main chain, divide by 4).
(Iii) The peak area B assigned to the hydrogen atom bonded to the carbon atom adjacent to the carbon atom to which the amino group is bonded in the aromatic ring at the end of the main chain of PN0 is ^{determined by 1} H-NMR measurement. ..
(Iv) The number of amino groups can be calculated by dividing the peak area B by the number of hydrogen atoms bonded to the carbon atom adjacent to the carbon atom to which the amino group is bonded (for example, peak). If area B is the peak area attributed to two hydrogen atoms bonded to a carbon atom adjacent to the carbon atom to which the amino group is bonded, divide by 2).
(V) The number of amino groups determined in (iv) is divided by the number of repeating units (number of units) determined in (ii), and further multiplied by 100 (100 units) to form the main chain of PN0. The amount of amino groups per 100 units of repeating units can be calculated.

^{As the} measurement solvent in ¹ H-NMR measurement, 1 H-NMR measurement is possible, any solvent may be used as long as it can dissolve PN0, and deuterated dimethylsulfoxide is preferable.
When heavy dimethyl sulfoxide is used as the measuring solvent ^{, the following 1} H-NMR measuring device and measuring conditions can be mentioned.

[measuring device]
NMR equipment: Varian NMR System PS400WB
Magnetic field strength: 9.4T (400MHz)
Probe: Varian 400 DB AutoX WB Probe
(5 mm)

[ ^{Measurement conditions for solution 1 1} H-NMR]
Measurement nucleus: ¹ H
Measurement method: Single pulse method Measurement temperature: 50 ° C
Deuterated solvent: d6-DMSO (containing TMS)
Waiting time: 10 sec
Pulse irradiation time: 11.9 μsec (90 ° C pulse)
Number of integrations: 64 times External standard: TMS (0ppm)

A more specific method for calculating the amino group amount of PN0 is as follows (calculation examples 1 to 3).

-Calculation example 1 of amino group amount
When the main chain of PN0 is composed of repeating units represented by the following formula (mc-1) and the end of the main chain has a structure represented by the following formula (e-1), the following formula (mc-1) is used. The amount of amino groups per 100 units of the repeating unit represented by) is calculated by the calculation method shown below. In the following equation, Xp is the peak area assigned to the hydrogen atom (Hx) in the equation (mc-1), and Yp is assigned to the hydrogen atom (Hy) in the equation (e-1). The peak area to be.

Number of units n01 = Xp / 4
Amino cardinal number = Yp / 2
Amino group amount = (Yp / 2) / (Xp / 4) × 100
= Yp / Xp × 200

-Calculation example 2 of amino group amount
The main chain of PN0 is composed of a repeating unit represented by the following formula (mc-1) and a repeating unit represented by (mc-2), and the end of the main chain is represented by the following formula (e-1). The amino group amount per 100 units of the repeating unit represented by the following formula (mc-1) and the repeating unit represented by the following formula (mc-2) is calculated by the calculation method shown below. To. In the following equation, Xp is the peak area assigned to the hydrogen atom (Hx) in the equation (mc-1), and Zp is assigned to the hydrogen atom (Hz) in the equation (mc-2). Yp is the peak area attributed to the hydrogen atom (Hy) in the formula (e-1).

Number of units n02 + n03 = Xp / 4 + Zp / 4
Amino cardinal number = Yp / 2
Amino group amount = (Yp / 2) / (Xp / 4 + Zp / 4) × 100
= Yp / (Xp + Zp) x 200

-Calculation example 3 of amino group amount
When the main chain of PN0 is composed of repeating units represented by the following formula (mc-3) and the end of the main chain has a structure represented by the following formula (e-1), the following formula (mc-3) is used. The amount of amino groups per 100 units of the repeating unit represented by) is calculated by the calculation method shown below. In the following formula, CH ₃ p is the peak area assigned to the methyl group in the formula (mc-3), and Yp is assigned to the hydrogen atom (Hy) in the formula (e-1). Peak area.

Number of units n04 = CH ₃ p / 24
Amino cardinal number = Yp / 2
Amino group amount _{= (Yp / 2) / (} CH 3 p / 24) × 100
= Yp / CH ₃ p × 1200

The porous membrane of the present embodiment may contain two or more kinds of PN0, or may contain a mixed resin of PN0 and one or more kinds of resins other than PN0.
The porous membrane of the present embodiment may contain a mixed resin of PN0 and an aromatic polysulfone having no amino group (hereinafter referred to as “PS0”).
In the mixed resin, the ^{amount of amino groups calculated from the peak area ratio of 1} H-NMR described above is preferably 0.1 or more per 100 repeating units forming the main chain of PN0 and PS0. 0.5 or more is more preferable, 0.7 or more is further preferable, 1 or more is particularly preferable, 40 or less is preferable, 10 or less is more preferable, 8 or less is further preferable, and 5 or less is more preferable. Is particularly preferable.
In the mixed resin, the amount of the amino groups is preferably 0.1 or more and 40 or less, and more preferably 0.5 or more and 10 or less, per 100 units of repeating units forming the main chain of PN0 and PS0. , 0.7 or more and 8 or less are more preferable, and 1 or more and 5 or less are particularly preferable.
The amino group amount in the mixed resin can be calculated based on the amino group amount of PN0 and the blending ratio of PN0 and PS0.

The amount of the amino group of PN0 is, for example, the amount of the compound having an amino group used in the method for producing PN0 described later; the amount of the base added in the method for producing PN0 described later; the degree of polymerization of PN0 and the like are appropriately adjusted. Can be controlled.
Further, the amount of amino groups in the porous membrane of the present embodiment can also be controlled by adjusting the mixing ratio of PN0 and PS0. The amount of amino groups in the porous membrane can be calculated from the mixing ratio of PN0 and PS0. It can also be calculated by measuring the porous membrane in ¹ H-NMR as described above and dividing the number of amino groups by the total number of units of PNO and PS0 based on the obtained results.

The porous membrane of the present embodiment preferably contains a mixed resin of PN0 and PS0 from the viewpoint of further improving the membrane characteristics (particularly, water permeability) of the porous membrane.

<Aromatic polysulfone without amino group>
As PS0, specifically, an aromatic polysulfone having a repeating unit represented by the above general formula (S-1-1) and having, for example, a halogen atom, a hydroxy group, a methoxy group or a phenyl group at the end of the main chain. Can be mentioned.

Examples of commercially available products of PS0 include Sumika Excel (registered trademark) PES 3600P, 4100P, 4800P, 5200P and 5900P, which are polyether sulfones manufactured by Sumitomo Chemical Co., Ltd.
The number average absolute molecular weight of PS0 is preferably larger than the above-mentioned number average absolute molecular weight of PN0.

[Glass-transition temperature]
The glass transition temperature (Tg) of PS0 is preferably 222 ° C. or higher, more preferably 223 ° C. or higher, and particularly preferably 224 ° C. or higher.
The upper limit of the glass transition temperature of PS0 is not particularly limited, and for example, it is 250 ° C. or lower, 240 ° C. or lower, and 230 ° C. or lower.
The glass transition temperature can be measured, for example, by a method according to JIS-K7121.

[Reduced viscosity]
The reduction viscosity (unit: dL / g) of PS0 is preferably 0.32 or more, more preferably 0.35 or more.
The upper limit of the reduction viscosity is not particularly limited, and for example, it is 0.80 or less, 0.75 or less, 0.7 or less.

The total content of PN0 and PS0 in the porous membrane of the present embodiment is preferably 50% by mass or more, more preferably 80% by mass or more, and 90% by mass or more, based on the total amount of the porous membrane of the present embodiment. More preferably, it may be 100% by mass.
The blending ratio of PN0 and PS0 (mass% of PN0: mass% of PS0) is preferably 5:95 to 95: 5, more preferably 10:90 to 90:10, and 20:80 to 80:20. It may be 40:60 to 60:40.

<Arbitrary ingredient>
The porous membrane of the present embodiment may contain arbitrary components other than the above-mentioned PN0 and PS0. Optional components include resins other than the above-mentioned PN0 and PS0, organic solvents, colorants, lubricants, various surfactants, antioxidants, heat stabilizers, various other stabilizers, ultraviolet absorbers, antistatic agents and the like. Can be mentioned.

≪Resin other than aromatic polysulfone≫
Examples of the resin other than PN0 and PS0 include polyamide, polyester, polyphenylene sulfide, polycarbonate, polyphenylene ether, aromatic polyketone, polyetherimide, phenol resin, epoxy resin, polyimide resin and modified products thereof.

<Method for producing aromatic polysulfone having an amino group>
Aromatic polysulfone having an amino group in the main chain can be produced, for example, by modifying a part of the monomer as a raw material of the aromatic polysulfone with an amino group and then performing a polycondensation reaction. Further, as a raw material, a monomer substituted with an amino group may be used.

On the other hand, aromatic polysulfone having an amino group at the end of the main chain can be produced, for example, by reacting an aromatic polysulfone precursor having a halogen atom at the end of the main chain with an amino compound.

One embodiment of the method for producing aromatic polysulfone having an amino group at the end of the main chain includes a step (i) of preparing an aromatic polysulfone precursor having a halogen atom at the end of the main chain (hereinafter referred to as “PSP”).
It said PSP, by reacting an amino compound, comprising an aromatic polysulfone having an amino group in the main chain terminal (hereinafter, referred to as "PN0 ^1") and the step of generating (ii), the.

Step (i):
The PSP may be synthesized by the method described later, or may be a commercially available product.
Examples of commercially available PSP products include Sumika Excel (registered trademark) PES 3600P, 4100P, 4800P, 5200P and 5900P, which are polyether sulfones manufactured by Sumitomo Chemical Co., Ltd.

The number average absolute molecular weight of the PSP is preferably 1000 or more and 30,000 or less, more preferably 2000 or more and 25,000 or less, and further preferably 4000 or more and 15,000 or less.

<Manufacturing method of PSP>
The PSP in the present embodiment can be produced by using a dihalogeno aromatic sulfone compound, a dihydroxyaromatic compound and the like as monomers, and polycondensing these monomers in an organic solvent in the presence of a base.

≪Monomer≫
The dihalogeno aromatic sulfone compound is a compound having an aromatic ring, a sulfonyl group, and two 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 dihalogeno aromatic sulfone compound and the dihydroxy aromatic compound correspond to the repeating units constituting the PSP.

When the PSP in the present embodiment has a repeating unit containing the structure represented by the above formula (S-1), the compound represented by the following formula (mx-1) is used as the dihalogenoaromatic sulfone compound. , The dihydroxyaromatic compound can be produced by using a compound represented by the following formula (my-1).
X ^1- ph ^1- SO _2- ph ^2- X ² ... (mx-1)
HO-ph ^1- SO ₂ ^{-ph 2-} OH ... (my-1)
[In the formula (mx-1), ph ¹ and ph ² are phenylene groups which may independently have a substituent. X ¹ and X ² are independent halogen atoms.
In the formula (my-1), ph ¹ and ph ² are phenylene groups which may independently have a substituent. ]

Wherein (mx-1) and ^(my-1), ph 1 and ph ² are the same as ph ¹ and ph ² in each above-mentioned formula (S-1).

In the formula (mx-1), X ¹ and X ² are independent halogen atoms. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and a chlorine atom is preferable.

Examples of the compound represented by the formula (mx-1) include bis (4-chlorophenyl) sulfone, 4-chlorophenyl-3', 4'-dichlorophenyl sulfone and the like.

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

When the PSP in the present embodiment has a repeating unit containing a structure represented by the above-mentioned formula (S-1) and a structure represented by the above-mentioned formula (S-2), it is used as a dihalogeno aromatic sulfone compound. By using the compound represented by the above formula (mx-1) and using the compound represented by the following formula (my-2) as the aromatic dihydroxy compound, it is represented by the above formula (S-1). A PSP having a structure and a repeating unit including the structure represented by the above formula (S-2) can be produced.
HO-ph ^3- R-ph ^4- OH ... (my-2)
[In the formula (my-2), ph ³ and ph ⁴ are phenylene groups which may independently have a substituent. R is an alkylidene group, an oxygen atom or a sulfur atom. ]

Wherein ^{(my-2), ph 3} , ph 4 and R are each identical to ^ph 3, ph ⁴ and R in the above-mentioned formula (S-2).

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

When the PSP in the present embodiment has a repeating unit containing the structure represented by the above-mentioned formula (S-1) and the above-mentioned structure represented by the formula (S-3), it is designated as a dihalogenoaromatic sulfone compound. By using the compound represented by the above formula (mx-1) and using the compound represented by the following formula (my-3) as the dihydroxyaromatic compound, it is represented by the above formula (S-1). A PSP having a structure and a repeating unit including the structure represented by the above formula (S-3) can be produced.

HO- (ph ⁵ ) _n- OH ... (my-3)
[In the 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, ph ⁵ there are a plurality, it may be the same or different from each other. ]

Wherein (my-3), ph ⁵ and n are each identical to ph ⁵ and n in the above-mentioned formula (S-3).

Examples of the compound represented by the formula (my-3) include hydroquinone, resorcin, catechol, phenylhydroquinone, 4,4'-dihydroxybiphenyl, 2,2'-dihydroxybiphenyl, 3,5,3', 5'-tetra. Examples thereof include methyl-4,4'-dihydroxybiphenyl, 2,2'-diphenyl-4,4'-dihydroxybiphenyl and 4,4'''-dihydroxy-p-quarterphenyl.

In the present embodiment, one of the dihalogeno aromatic sulfone compound and the dihydroxy aromatic compound may be used alone or in combination of two or more, depending on the type of the target aromatic polysulfone. May be.

≪Base, organic solvent≫
The polycondensation of the dihalogeno aromatic sulfone compound and the dihydroxy aromatic compound is preferably carried out using an alkali metal salt of carbonic acid as a base. Further, the polycondensation is preferably performed in an organic solvent. It is more preferable that the polycondensation is carried out using an alkali metal salt of carbonic acid as a base and in an organic solvent.

The alkali metal salt of carbonic acid may be alkali carbonate (alkali metal carbonate), bicarbonate alkali (hydrogencarbonate, alkali metal hydrogen carbonate), or a mixture thereof. May be.
Examples of the alkali carbonate include sodium carbonate, potassium carbonate and the like.
Examples of the alkali bicarbonate include sodium bicarbonate (sodium hydrogencarbonate) and potassium bicarbonate (potassium hydrogencarbonate).

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.

Examples of such an organic solvent include sulfoxides such as dimethyl sulfoxide; amides such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methyl-2-pyrrolidone; sulfolanes (1,1-dioxotyran) and dimethyl sulfones. , Dethyl sulfone, diisopropyl sulfone, diphenyl sulfone and the like; 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone and the like.

As the organic solvent, one kind may be used alone, or two or more kinds may be used in combination.

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.

Process (ii)
<Amino compound>
The amino compound as the terminal cap agent is not particularly limited as long as it is a compound capable of substituting the halogen atom at the end of the main chain of the PSP with an amino group.
Specific examples of the amino compound include 4-aminophenol, 3-aminophenol, 2,4-diaminophenol, 2,5-diaminophenol, 3-aminopropanol, 4- (2-aminoethyl) phenol and the like. Among them, 4-aminophenol and 3-aminophenol are preferable.

The step (ii) may be performed in an organic solvent in the presence of a base, and examples of the organic solvent and base include the same organic solvent and base as described in the above-mentioned method for producing PSP.

The reaction temperature for reacting the PSP with the amino compound is preferably 100 to 400 ° C, preferably 100 to 300 ° C, and the reaction time is preferably 1 to 50 hours, preferably 2 to 30. It is more preferable that it is time.

The amount of the amino compound used in the step (ii) is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass with respect to 100 parts by mass of PSP.

The amount of the base used in the step (ii) is preferably 0.1 to 10 parts by mass, more preferably 0.3 to 5 parts by mass with respect to 100 parts by mass of PSP.

The porous membrane of the present embodiment described above contains aromatic polysulfone having an amino group. Since the aromatic polysulfone has an amino group which is a hydrophilic group, the porous membrane of the present embodiment is highly hydrophilic. Therefore, the porous membrane of this embodiment has high water permeability.
Further, when the porous membrane of the present embodiment contains an aromatic polysulfone having an amino group at the end of the main chain, a robust structure can be obtained without weakening the interaction between the aromatic rings of the aromatic polysulfone. Since the amino group can be maintained and the amino group is arranged on the surface of the porous membrane, the porous membrane of the present embodiment has higher water permeability and higher mechanical strength.

(Manufacturing method of porous membrane)
As a method for producing the porous film of the present embodiment, PN0 is dissolved in a solvent, the obtained solution is extruded into a predetermined shape, and the solution is dry-wet through an air gap or wet without an air gap. It can be produced by introducing it into a coagulating solution, phase separation and desolvation.
Further, separately from this method, PN0 may be dissolved in a solvent, the obtained solution may be cast on a substrate having a predetermined shape, immersed in a coagulating liquid, and phase-separated and desolved. ..

When a hollow fiber membrane is produced as a porous membrane, a solution in which PN0 is dissolved in a solvent is used as a spinning stock solution, and a double annular nozzle is used. Specifically, the porous hollow fiber membrane is manufactured by discharging the solution from the outside and discharging a coagulating liquid (hereinafter, may be referred to as “internal coagulating liquid”) or a gas from the inside. It is preferable to introduce these into a coagulating liquid (hereinafter, may be referred to as "external coagulating liquid") with or without an air gap.

When producing a thin film (film) as a porous film, PN0 is dissolved in a solvent, the obtained solution is applied to one surface of a glass plate using a film applicator, and then immersed in water to be used from the glass plate. It can be manufactured by peeling it off.

Examples of the good solvent for the aromatic polysulfone used in the preparation of the solution (hereinafter, may be simply referred to as “good solvent”) include N-methylpyrrolidone, N, N-dimethylformamide and N, N-dimethylacetamide. Can be mentioned.

Further, the solution may further contain a swelling agent.
Examples of the swelling agent include ethylene glycols such as ethylene glycol, diethylene glycol, and triethylene glycol, and ethylene glycol is preferable because it is easy to remove.

As the coagulation liquid, a poor solvent or a mixed solvent of a poor solvent and a good solvent can be used. As the coagulant, it is preferable to use a mixed solvent of a poor solvent and a good solvent. By adjusting the mixing ratio of the poor solvent and the good solvent, the pore size and the pore size distribution of the obtained porous membrane can be adjusted.

Further, the porous membrane obtained by the above-mentioned production method may be heat-treated or radiation-treated, if necessary.
The heating temperature when the heat treatment is performed is, for example, 150 to 190 ° C.
The radiation used for radiation treatment is, for example, α-rays, β-rays, γ-rays, X-rays or electron beams.

Further, when the hollow fiber membrane is produced as the porous membrane, the hollow fiber membrane may be sterilized by steam using an autoclave or the like.

Further, the amino group in PN0 may be chemically reacted (modified) before and after forming the porous film.

Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the examples shown below.

<Measurement method of amino group amount>
^{The amount of amino groups (A 01} ) at the end of the main chain per 100 units of repeating units forming the main chain of aromatic polysulfone in the porous membrane of each example was calculated by NMR measurement.
Specifically, in ¹ H-NMR measurement, in the main chain of aromatic polysulfone (-ph ^1- SO _2- ph ^2- O-), two atoms adjacent to the carbon atom of ^{ph 1 bonded to S are adjacent to each other.} It is attributed to two hydrogen atoms bonded to each carbon atom and two hydrogen atoms bonded to ^{two carbon atoms adjacent to the ph 2 carbon atom bonded to S (a total of four hydrogen atoms).} Peak area (Xp ⁰¹ ) and the peak area assigned to two hydrogen atoms bonded to two carbon atoms adjacent to the carbon atom to which the amino group is bonded in the aromatic ring at the end of the main chain of the aromatic polysulfone. It was calculated based on the following formula (a1) using (Yp ^{01).
A 01 = (Yp 01/2} ) / (Xp 01/4) × 100
= Yp ⁰¹ / Xp ⁰¹ × 200 ... (a1)
As Xp ⁰¹ , an integrated value of 7.9 to 8.1 ppm was adopted. Further, as Yp ⁰¹ , an integrated value of 6.6 to 6.7 ppm was adopted.

[measuring device]
NMR equipment: Varian NMR System PS400WB
Magnetic field strength: 9.4T (400MHz)
Probe: Varian 400 DB AutoX WB Probe
(5 mm)

[Measurement condition]
Measurement nucleus: ¹ H
Measurement method: Single pulse method Measurement temperature: 50 ° C
Deuterated solvent: d6-DMSO (containing TMS)
Waiting time: 10 sec
Pulse irradiation time: 11.9 μsec (90 ° C pulse)
Number of integrations: 64 times External standard: TMS (0ppm)

The amount of the amino group is a value calculated from the aromatic polysulfone used as a raw material. The porous membranes of Examples 1 to 3 are a mixture of an aromatic polysulfone having an amino group and an aromatic polysulfone having no amino group, and the amount of the amino group in the mixture is an aromatic having an amino group. After calculating the amino group amount of the polysulfone, it is a value calculated from the mixing ratio of the mixture (for example, in Example 1, the value obtained by dividing the amino group amount of PN1 by 1/10).

<Measurement method of number average absolute molecular weight of aromatic polysulfone>
The number average absolute molecular weight (Mn) of aromatic polysulfone was determined by GPC measurement. In addition, Mn was measured twice in each case, and the average value was calculated.
[Measurement condition]
Sample: 0.002 g of aromatic polysulfone was added to 1 mL of a 10 mM lithium bromide-containing N, N-dimethylformamide solution.
Sample injection amount: 100 μL.
Column (stationary phase): Two "TSKgel GMHHR-H" (7.8 mmφ x 300 mm) manufactured by Tosoh Corporation are connected in series.
Column temperature: 40 ° C
Eluent (mobile phase): N, N-dimethylformamide containing 10 mM lithium bromide Eluent flow rate: 0.8 mL / min Detector: Differential refractometer (RI) + multi-angle light scattering photometer (MALS)
Standard reagent: Polystyrene Molecular weight calculation method: Absolute molecular weight was calculated from a multi-angle light scattering photometer (MALS).

<Manufacturing of Amino Group-Containing Aromatic Polysulfone>
<< Manufacturing Example 1 >>
3.57 parts by mass of potassium carbonate, 5.13 parts by mass of bis (4-chlorophenyl) sulfone and N-methyl in a polymerization tank equipped with a stirrer, a nitrogen introduction tube, a thermometer, and a condenser with a receiver at the tip. After mixing 120 parts by mass of -2-pyrrolidone and raising the temperature to 100 ° C., 120 parts by mass of polyether sulfone (Sumika Excel (registered trademark) PES 3600P manufactured by Sumitomo Chemical Co., Ltd.) was added. After the polyether sulfone is dissolved, the temperature is raised to 190 ° C., then 4.53 parts by mass of 4-aminophenol and 60 parts by mass of N-methyl-2-pyrrolidone are mixed, added dropwise, and the temperature is raised to 200 ° C. to 10 Reacted for time.
The resulting reaction mixture was then diluted with NMP and cooled to room temperature to precipitate unreacted potassium carbonate and by-produced potassium chloride. The reaction mixture solution after the above-mentioned precipitation operation was dropped into water to precipitate aromatic polysulfone, and unnecessary NMP was removed by filtration to obtain a precipitate. The obtained precipitate was carefully washed repeatedly with water and dried by heating at 150 ° C. to obtain an amino group-containing aromatic polysulfone PN1 having an amino group at at least one of the ends of the main chain. The number average absolute molecular weight of the obtained PN1 was 6600, and the amino group weight of PN1 was 7.4 (pieces / 100 units).

<< Manufacturing Example 2 >>
In a polymerization tank equipped with a stirrer, a nitrogen introduction tube, a thermometer, and a condenser with a receiver at the tip, 1.22 parts by mass of 4-aminophenol, 1.24 parts by mass of potassium carbonate, and N-methyl-2- 180 parts by mass of pyrrolidone was mixed, and after raising the temperature to 100 ° C., 120 parts by mass of polyether sulfone (Sumika Excel (registered trademark) PES 3600P manufactured by Sumitomo Chemical Co., Ltd.) was added. After the polyether sulfone was dissolved, the mixture was heated to 200 ° C. and reacted for 10 hours.
The resulting reaction mixture was then diluted with NMP and cooled to room temperature to precipitate unreacted potassium carbonate and by-produced potassium chloride. The reaction mixture solution after the above-mentioned precipitation operation was dropped into water to precipitate aromatic polysulfone, and unnecessary NMP was removed by filtration to obtain a precipitate. The obtained precipitate was carefully washed repeatedly with water and dried by heating at 150 ° C. to obtain an amino group-containing aromatic polysulfone PN2 having an amino group at at least one of the ends of the main chain. The number average absolute molecular weight of the obtained PN2 was 12400, and the amino group weight of PN2 was 2.1 (pieces / 100 units).

<< Manufacturing Example 3 >>
In a polymerization tank equipped with a stirrer, a nitrogen introduction tube, a thermometer, and a condenser with a receiver at the tip, 0.405 parts by mass of 4-aminophenol, 0.618 parts by mass of potassium carbonate, and N-methyl-2- 180 parts by mass of pyrrolidone was mixed, the temperature was raised to 100 ° C., and then 120 parts by mass of polyether sulfone (Sumika Excel (registered trademark) PES 4800P manufactured by Sumitomo Chemical Co., Ltd.) was added. After the polyether sulfone was dissolved, the mixture was heated to 200 ° C. and reacted for 10 hours.
The resulting reaction mixture was then diluted with NMP and cooled to room temperature to precipitate unreacted potassium carbonate and by-produced potassium chloride. The reaction mixture solution after the above-mentioned precipitation operation was dropped into water to precipitate aromatic polysulfone, and unnecessary NMP was removed by filtration to obtain a precipitate. The obtained precipitate was carefully washed repeatedly with water and dried by heating at 150 ° C. to obtain an amino group-containing aromatic polysulfone PN3 having an amino group at at least one of the ends of the main chain. The number average absolute molecular weight of the obtained PN3 was 21,800, and the amino group weight of PN3 was 0.6 (pieces / 100 units).

<Manufacturing of porous membrane>
<Example 1>
In the heating container, 1.8 parts by mass of PN1, 16.2 parts by mass of polyether sulfone PS1 (Sumitomo Chemical Co., Ltd., Sumika Excel (registered trademark) PES 5900P), and 82 parts by mass of NMP, respectively. The mixture was mixed and stirred at 80 ° C. for 2 hours to obtain a pale yellow solution. This solution was applied to one surface of a glass plate having a thickness of 3 mm using a film applicator and then immersed in water to form a porous film having a film thickness of 140 to 170 μm.
The porous membrane of each example was peeled off from the glass plate, washed with water multiple times, and then the membrane was stored in water until the start of measurement.

<Example 2>
Porous medium of Example 2 in the same manner as in Example 1 except that 5.4 parts by mass of PN1, 12.6 parts by mass of PS1 and 82 parts by mass of NMP were mixed in the heating container. Obtained a membrane.

<Example 3>
A porous membrane of Example 3 was obtained in the same manner as in Example 1 except that 9 parts by mass of PN2, 9 parts by mass of PS1 and 82 parts by mass of NMP were mixed in the heating container. ..

<Example 4>
A porous membrane of Example 4 was obtained in the same manner as in Example 1 except that 18 parts by mass of PN3 and 82 parts by mass of NMP were mixed in the heating container.

<Comparative Example 1>
A porous film of Comparative Example 1 was obtained in the same manner as in Example 1 except that 18 parts by mass of PS1 and 82 parts by mass of NMP were mixed in the heating container.

[Measurement of permeability rate]
Using a pressure cell having a diameter of 47 mm, the porous membranes of each example were cut out in a circular shape so that they could be attached to the pressure cell, and test membranes of each example were prepared. The test membranes of each example were attached to the pressure cells, and pure water was filtered through the test membranes of each example at a pressure of 23 ° C. and 0.2 bar (20 kPa), and 9 minutes and 30 seconds from the start of filtration. the amount of pure water which has passed through the test membrane of the examples from the time elapsed 10 minutes elapsed o'clock (30 seconds) was measured to determine the water permeation rate ^{(L / m 2 / h /} 10 5 Pa). The results are shown in Table 1.

Table 1 shows the aromatic polysulfone contained in the porous membrane of each example, the mixing ratio (parts by mass) of the aromatic polysulfone having an amino group and the aromatic polysulfone having no amino group, and the porous membrane of each example. The amount of amino groups per 100 units of repeating units of aromatic polysulfone contained in is shown, and the water permeation rate of the porous membrane of each example is shown.

As shown in Table 1, the porous membrane formed by using the aromatic polysulfone of the example has a higher permeation rate and is excellent in water permeability than the porous membrane formed by using the aromatic polysulfone of the comparative example. Was confirmed.

Claims (3)

A porous membrane containing an aromatic polysulfone having an amino group. The porous membrane according to claim 1, wherein the aromatic polysulfone having an amino group has an amino group in a part or all of the end of the main chain. The porous membrane according to claim 1 or 2, further containing an aromatic polysulfone having no amino group.