JPH0364176B2

JPH0364176B2 -

Info

Publication number: JPH0364176B2
Application number: JP58101253A
Authority: JP
Inventors: Hirotoshi Ishizuka; Tsukasa Ochiumi; Masahiro Kamibayashi; Keisuke Nakagome
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 1983-06-07
Filing date: 1983-06-07
Publication date: 1991-10-04
Also published as: JPS59228016A

Description

[Detailed description of the invention]

本発明は、機械的強度と透水性のいずれにもす
ぐれた芳香族ポリスルホン中空糸状半透膜及びそ
の製造方法に関する。芳香族ポリスルホンは耐熱性及び耐薬品性にす
ぐれているため、従来よりこれを素材とする中空
糸状半透膜が種々提案されている。例えば、特開
昭49−23183号公報には、内表面に緻密な層を有
し、外表面には重合体が欠落した径10μ以上の空
洞が開口している中空糸状半透膜が提案さている
が、かかる構造によれば特に機械的強度が小さ
い。このため、特開昭54−145379号公報には、内
表面及び外表面に共に緻密な層を有し、この緻密
な表面から連続する多孔質重合体層が膜表面から
孔径が連続的に大きくなるような構造の芳香族ポ
リスルホン中空糸状半透膜が提案されている。し
かし、この膜は、透水性の膜厚依存性が大きく、
特に、膜厚が200μを越えるとき、透水性が著し
く悪くなる。本発明は上記した種々の問題を解決するために
なされたものであつて、構造が上記したような従
来の中空糸状半透膜とは基本的に異なり、その結
果、機械的強度及び透水性のいずれにもすぐれる
芳香族ポリスルホン中空糸状半透膜を提供するこ
とを目的とし、また、かかる中空糸状半透膜を製
造する方法を提供することを目的とする。本発明による芳香族ポリスルホン中空糸状半透
膜は、実質的に10〜100Åの孔径の微孔を有する
一方の緻密な表面と、上記微孔よりも孔径が大き
く、且つ、実質的に0.02〜2μｍの範囲の孔径の微
孔を有する他方の緻密な表面と、上記いずれの表
面の有する微孔より孔径が大きく、且つ、実質的
に0.05〜5μｍの範囲にある細孔を有すると共に、
上記各表面にそれぞれ連続する厚み５〜50μｍの
網状多孔質層と、この網状多孔質層に連続してほ
ぼ膜の中間に位置すると共に、膜のほぼ半径方向
に延びる空洞を有する指状構造層とからなり、膜
厚が50〜450μｍの範囲にあることを特徴とする。第１図は、本発明による芳香族ポリスルホン中
空糸状半透膜の一実施例であつて、内表面がより
小さい孔径の微孔を有し、外表面がより大きい孔
径の微孔を有する膜の断面の電子顕微鏡写真を示
す。より詳細には、第１図に示す中空糸状膜にお
いては、外表面の有する微孔孔径は実質的に0.02
〜2μｍ、通常、0.1〜1μｍの範囲にある。また、
膜厚は、通常、50〜450μｍである。このように、膜の緻密は内外表面における微孔
孔径が異なるため、本発明の膜によれば、小さい
孔径の微孔を有する表面側に処理すべき液体を供
給すれば、大きい孔径の微孔を有する他方の表面
は流体の通過抵抗を形成しないので、透水性の膜
厚依存性が小さく、後述する実施例にみるよう
に、膜厚が200μを越える膜においても大きい透
水性を有する。本発明の中空糸状膜においては、この膜の内外
の表面に連続して、孔径が実質的に0.05〜5μｍの
範囲であつて、且つ、いずれの表面の微孔孔径よ
り大きい細孔を有する網状多孔質層がそれぞれ形
成されており、各表面を一体的に支持している。
この多孔質層の厚みは、通常、５〜50μである。
本発明の中空糸状半透膜においては、緻密な表面
に連続するこの網状多孔質層が存在するために、
膜は機械的強度にすぐれると共に、耐圧密化性に
もすぐれる。更に、この網状多孔質層に連続する
膜のほぼ中間には、実質的に独立した指状空洞が
ほぼ膜の半径方向に延びて形成され、指状構造層
をなしている。尚、網状多孔質層及び指状構造層の有する細孔
や空洞の径の大きさは電子顕微鏡写真により評価
されるが、緻密層の微孔孔径はポリエチレングリ
コール、デキストラン、種々の分子量を有するタ
ンパク質等に対する除去率から評価される。本発明において、芳香族ポリスルホンは代表的
には次のような繰返し単位を有する。又は但し、X₁〜X₆はメチル基、エチル基等のアル
キル基、塩素、臭素等のハロゲンに例示される非
解離性の置換基を示し、ｌ、ｍ、ｎ、ｏ、ｐ及び
ｑは０〜４の整数を示す。一般的には、ｌ、ｍ、
ｎ、ｏ、ｐ及びｐのすべてが０であるポリスルホ
ンが入手しやすく、本発明においても好ましく用
いられる。しかし、本発明で用いるポリスルホン
は上記に限定されるものではない。本発明の中空糸状半透膜は、本発明に従つて、
芳香族ポリスルホンを溶解する極性有機溶剤と、
この溶剤と混合するが、芳香族ポリスルホンを溶
解しない溶剤であつて、エチレングリコール、ジ
エチレングリコール及びプロピレングリコールか
ら選ばれる溶剤（以下、非溶剤という。）との混
合剤に芳香族ポリスルホンを溶解して製膜溶液と
し、二重管型ノズルの外管から押出してポリスル
ホンを凝固させる際に、一方の表面に相対湿度60
％以上の空気を接触させ、他方の表面には凝固液
を接触させ、この後に水中に浸漬して脱溶剤する
ことによつて得ることができる。即ち、本発明によれば、一方の表面が接触する
空気雰囲気の相対湿度を60％以上、好ましくは80
％以上とすることにより、凝固液側に実質的に10
〜100Åの孔径の微孔を有する緻密な表面を形成
し、空気側に実質的に0.02〜2μｍ、通常は0.1〜
1μｍの範囲の孔径の微孔を有する他方の緻密な
表面を形成し、更に、上記いずれの表面の有する
微孔よりも大きく、且つ、孔径が実質的に0.05〜
5μの範囲にある細孔を有して、上記各表面にそ
れぞれ連続する網状多孔質層と、この網状多孔質
層に連続してほぼ膜の中間に位置すると共に、膜
のほぼ半径方向に延びる空洞を有する指状構造層
とからなる機械的強度にすぐれる芳香族ポリスル
ホン中空糸状半透膜を得ることができる。尚、空気の相対湿度が20〜60％の間にあるとき
は、理由は明らかではないが、一般に得られる中
空糸状膜の物性、特に機械的強度が均一性に欠
け、部分的に強度が劣る場合がある。また、透水
速度や除去率にもかなりのばらつきが生じること
がある。従つて、本発明においては、安定した物
性を有する中空糸状膜を得ることができるよう
に、空気の相対湿度を前記したように60％以上と
する。通常の方法においては、製膜溶液を二重管型ノ
ズルの外管から空気中に押出し、内管から凝固液
を流出させ、内表面に外表面よりも緻密な表面を
有する中空糸状膜を得るので、以下においては、
製膜溶液を空気中に押出す場合について説明す
る。本発明による方法においては、芳香族ポリスル
ホンを溶解する極性有機溶剤と、この溶剤と混和
する芳香族ポリスルホンを溶解しない非溶剤との
混合溶剤に芳香族ポリスルホンを溶解して製膜溶
液とし、二重管型ノズルの外管から空気中に押出
して中空糸状半透膜を凝固させる際に、上記空気
の相対湿度をを60％以上とし、内表面には凝固液
を接触させ、次いで、水中に浸漬して中空糸に残
存する溶剤を脱溶剤する。この方法においては、
二重管型ノズルから押出されたポリスルホンは、
内表面は凝固液との置換によつて凝固され、外表
面は高湿度空気中の水分によつて凝固されるが、
しかし、外表面は完全に凝固する必要がなく、こ
の後に水中に浸漬されることによつて、外表面も
完全に凝固されると共に、残存する溶剤が脱溶剤
されて、本発明による中空糸状膜を得ることがで
きる。反対にポリスルホン製膜溶液を凝固液中に押出
すと共に、内管から所定の湿度の空気を流出させ
れば、外表面により緻密な表面を有する中空糸状
膜を得ることができることは明らかであろう。尚、網状多孔質層は外表面よりも粗大な多孔質
層であつて、網状多孔質層の有する細孔の孔径
は、通常、外表面の有する微孔の孔径の約10倍又
はそれ以上である。本発明の方法において、上記のような芳香族ポ
リスルホンを溶解して製膜溶液を調製するための
極性有機溶剤としては、Ｎ−メチル−２−ピロリ
ドン、ジメチルホルムアミド、ジメチルアセトア
ミド等が好ましく用いられる。また、上記極性有
機溶剤と混和するが、芳香族ポリスルホンを溶解
しない非溶剤としては、エチレングリコール、ジ
エチレングリコール又はプロピレングリコールが
用いられる。混合溶剤中の非溶剤の含有量は、得
られる混合溶剤が均一である限りは特に制限され
ないが、通常、５〜50重量％、好ましくは20〜45
重量％である。製膜溶液における非溶剤は、上記
の凝固過程において、網状多孔質層及び／又は空
洞の形成に寄与して、膜の透水性を高めるのに効
果があり、通常、混合溶剤中の非溶剤の割合を高
める程、得られる中空糸状半透膜の透水性が高ま
る。反対に、製膜溶液に非溶剤を用いない場合
は、得られる膜の透水性は、本発明の膜の1/2乃
至至1/10程度である。製膜溶液中の芳香族ポリスルホンの濃度は、通
常、５〜35重量％、好ましくは10〜30重量％であ
る。35重量％を越えるときは、得られる半透膜の
透水性が実用的には小さすぎるからであり、一
方、５重量％より少ないときは、得られる膜が機
械的強度に劣るようになるからである。次に、二重管型ノズルの内管に流出させる凝固
液としては、一般的には水が用いられるが、前記
したように、芳香族ポリスルホンを溶解しない
が、前記極性有機溶剤と混和する溶剤であれば任
意に用いることができ、例えば、前記した非溶剤
又はこれと水との混合溶剤であつてもよい。更
に、芳香族ポリスルホンを単独では溶解する溶剤
であつても、他の溶剤と混合することにより、ポ
リスルホンを溶解しない範囲であれば、凝固液と
して用いることができる。このように、製膜溶液
が二重管型ノズルから空気中に押出されてから水
中に浸漬されるまでの凝固時間は、製膜溶液の組
成やノズルから押出される際の製膜溶液の厚みに
もよるが、通常、２秒以上、好ましくは３〜10秒
である。このようにして得られる中空糸状半透膜は、前
記したように、全体の膜厚は通常、50〜450μｍ
であり、このうち、網状多孔質層は通常５〜50μ
ｍ、殆どの場合、20〜40μｍの厚みの層であつ
て、この層にはポリスルホンが欠落した空洞は全
く依存しない。この多孔質層が5μｍよりも薄い
ときは、膜が実用上十分な機械的強度及び耐圧密
化性を有しないので好ましくない。また、指状構
造層の有する空洞の横断方向の径は、通常、10μ
ｍ以上である。第１図は、本発明の方法による芳香族ポリスル
ホン中空糸状半透膜の一実施例であつて、内表面
がより小さい孔径の微孔を有し、外表面がより大
きい孔径の微孔を有する膜の断面の電子顕微鏡写
真（200倍）を示す。第２図は内表面（10000倍）
を示し、第３図は外表面（5000倍）を示す電子顕
微鏡写真である。このように、本発明の膜によれば、膜の緻密な
内外表面における微孔孔径が異なるため、小さい
孔径の微孔を有する表面側に処理すべき液体を供
給すれば、大きい孔径の微孔を有する他方の表面
は流体の通過抵抗を形成しないので、透水性の膜
厚依存性が小さく、後述する実施例にみるよう
に、膜厚が200μを越える膜においても大きい透
水性を有する。一般に、中空糸状半透膜は、空洞を有しないと
きに機械的強度及び耐圧密化性にすぐれるといわ
れているが、本発明の中空糸状半透膜は上記した
ように、空洞を有しながら機械的強度及び耐圧密
化性にすぐれている。これは、前記網状多孔質層
が比較的厚いことに基づくのであろう。同時に、
本発明の中空糸状半透膜は、このような従来にな
い構造を有するために、特に厚みが大きい場合に
も透水性にもすぐれている特徴を有する。以下に実施例を挙げて本発明を説明するが、本
発明はこれら実施例により何ら限定されるもので
はない。実施例１Ｎ−メチル−２−ピロリドン58重量部とジエチ
レングリコール29重量部との混合溶剤に、式で表わされる繰返し単位を有する芳香族ポリスル
ホン芳香族ポリスルホン13重量部を溶解して製膜
溶液を得た。相対湿度80％、温度24℃の雰囲気において、二
重管型ノズルの外管から上記製膜溶液を押出すと
共に、内管から水を流出させて、５秒間上記雰囲
気に保ち、その両表面から凝固させ、次に、水中
に浸漬、脱溶剤して、内径0.5mm、外径0.9mmの中
空糸状半透膜を得た。この半透膜は、純水透水速度25.1m³／m²・日・
気圧であり、分子量10万のデキストランに対する
除去率は75％であつた。また、一端を封止した中
空糸状半透膜内に常温の水を圧入して、破裂強度
を測定したところ、18Kg／cm²であつた。また、上で得た中空糸状半透膜の断面の電子顕
微鏡写真（200倍）を第１図に、内表面の電子顕
微鏡写真（10000倍）を第２図に、外表面の電子
顕微鏡写真（5000倍）を第３図に示す。実施例２〜４実施例１と同じ混合溶剤にポリスルホンを溶解
し、ポリスルホン濃度の異なる製膜溶液を得た。
これらを実施例１と同様の方法で同一寸法の中空
糸状半透膜を得た。これらの膜物性を第１表に示
す。 The present invention relates to an aromatic polysulfone hollow fiber semipermeable membrane having excellent mechanical strength and water permeability, and a method for producing the same. Since aromatic polysulfone has excellent heat resistance and chemical resistance, various hollow fiber semipermeable membranes made from it have been proposed. For example, Japanese Patent Application Laid-Open No. 49-23183 proposes a hollow fiber semipermeable membrane having a dense layer on the inner surface and a cavity with a diameter of 10 μ or more in which the polymer is missing on the outer surface. However, such a structure has particularly low mechanical strength. For this reason, JP-A No. 54-145379 discloses that a porous polymer layer has a dense layer on both the inner and outer surfaces, and that the porous polymer layer that continues from this dense surface has pores that continuously increase in pore size from the membrane surface. An aromatic polysulfone hollow fiber semipermeable membrane with the following structure has been proposed. However, the water permeability of this membrane is highly dependent on the membrane thickness.
In particular, when the film thickness exceeds 200μ, water permeability becomes significantly poor. The present invention was made to solve the various problems described above, and its structure is fundamentally different from that of the conventional hollow fiber semipermeable membranes as described above. The object of the present invention is to provide an aromatic polysulfone hollow fiber semipermeable membrane that is excellent in both cases, and also to provide a method for manufacturing such a hollow fiber semipermeable membrane. The aromatic polysulfone hollow fiber semipermeable membrane according to the present invention has one dense surface having micropores with a pore diameter of substantially 10 to 100 Å, and one having a pore diameter larger than the above micropores and substantially 0.02 to 2 μm. The other dense surface has micropores with a pore size in the range of , and the other surface has pores with a pore diameter larger than that of any of the above surfaces and substantially in the range of 0.05 to 5 μm,
A network porous layer with a thickness of 5 to 50 μm continuous to each of the above surfaces, and a finger-like structure layer continuous to the network porous layer and having a cavity located approximately in the middle of the membrane and extending approximately in the radial direction of the membrane. It is characterized by having a film thickness in the range of 50 to 450 μm. FIG. 1 shows an embodiment of an aromatic polysulfone hollow fiber semipermeable membrane according to the present invention, in which the inner surface has micropores with a smaller pore diameter and the outer surface has micropores with a larger pore diameter. An electron micrograph of a cross section is shown. More specifically, in the hollow fiber membrane shown in FIG. 1, the diameter of the micropores on the outer surface is substantially 0.02.
~2 μm, typically in the range 0.1-1 μm. Also,
The film thickness is usually 50 to 450 μm. As described above, the density of the membrane is such that the diameter of the micropores on the inner and outer surfaces is different. Since the other surface having a . In the hollow fiber membrane of the present invention, the membrane has a network-like pore having a pore diameter substantially in the range of 0.05 to 5 μm and larger than the micropore diameter on either surface, continuously on the inner and outer surfaces of the membrane. A porous layer is formed in each case and integrally supports each surface.
The thickness of this porous layer is usually 5 to 50 microns.
In the hollow fiber semipermeable membrane of the present invention, since this reticulated porous layer exists continuously on the dense surface,
The membrane has excellent mechanical strength and compaction resistance. Further, substantially independent finger-like cavities are formed approximately in the middle of the membrane continuous with the network porous layer, extending approximately in the radial direction of the membrane, forming a finger-like structured layer. The diameters of the pores and cavities in the network porous layer and the finger-like structure layer are evaluated using electron micrographs, but the micropore diameter in the dense layer can be measured using polyethylene glycol, dextran, and proteins with various molecular weights. It is evaluated from the removal rate against etc. In the present invention, the aromatic polysulfone typically has the following repeating units. or However, X ₁ to _{X 6} represent a non-dissociable substituent such as an alkyl group such as a methyl group or an ethyl group, or a halogen such as chlorine or bromine, and l, m, n, o, p and q are 0. Indicates an integer of ~4. Generally, l, m,
Polysulfone in which n, o, p and p are all 0 is easily available and is preferably used in the present invention. However, the polysulfone used in the present invention is not limited to the above. According to the present invention, the hollow fiber semipermeable membrane of the present invention includes:
a polar organic solvent that dissolves aromatic polysulfone;
Aromatic polysulfone is dissolved in a mixture with a solvent selected from ethylene glycol, diethylene glycol, and propylene glycol (hereinafter referred to as non-solvent), which is a solvent that mixes with this solvent but does not dissolve the aromatic polysulfone. When solidifying the polysulfone by extruding it as a membrane solution through the outer tube of a double-tube nozzle, one surface was exposed to a relative humidity of 60°C.
% or more of air, and the other surface is brought into contact with a coagulating liquid, and then immersed in water to remove the solvent. That is, according to the present invention, the relative humidity of the air atmosphere with which one surface is in contact is set to 60% or more, preferably 80% or more.
% or more, substantially 10
Forms a dense surface with micropores of ~100 Å pore size, with substantially 0.02-2 μm on the air side, typically 0.1-2 μm
The other dense surface has micropores with a pore size in the range of 1 μm, and is larger than the micropores on any of the above surfaces and has a pore size of substantially 0.05 to 0.05 μm.
A network porous layer having pores in the range of 5μ and continuous to each surface, and a network porous layer continuous to the network porous layer located approximately in the middle of the membrane and extending approximately in the radial direction of the membrane. It is possible to obtain an aromatic polysulfone hollow fiber semipermeable membrane having excellent mechanical strength and having a finger-like structure layer having cavities. Furthermore, when the relative humidity of the air is between 20% and 60%, the physical properties of the hollow fiber membrane obtained generally lack uniformity, especially the mechanical strength, and the strength is inferior in some parts, although the reason is not clear. There are cases. Also, there may be considerable variation in water permeation rate and removal rate. Therefore, in the present invention, the relative humidity of the air is set to 60% or more as described above so that a hollow fiber membrane having stable physical properties can be obtained. In the usual method, the membrane-forming solution is extruded into the air from the outer tube of a double-tube nozzle, and the coagulated liquid is allowed to flow out from the inner tube, thereby obtaining a hollow fiber-like membrane whose inner surface is denser than the outer surface. Therefore, in the following,
The case where the membrane forming solution is extruded into the air will be explained. In the method according to the present invention, aromatic polysulfone is dissolved in a mixed solvent of a polar organic solvent that dissolves aromatic polysulfone and a non-solvent that does not dissolve aromatic polysulfone that is miscible with this solvent to form a membrane forming solution. When coagulating the hollow fiber semipermeable membrane by extruding it into the air from the outer tube of the tubular nozzle, the relative humidity of the air is set to 60% or more, the inner surface is brought into contact with the coagulating liquid, and then immersed in water. to remove the solvent remaining in the hollow fibers. In this method,
Polysulfone extruded from a double tube nozzle is
The inner surface is coagulated by displacement with a coagulating liquid, and the outer surface is coagulated by moisture in high-humidity air.
However, the outer surface does not need to be completely coagulated, and by being immersed in water after this, the outer surface is also completely coagulated and the remaining solvent is removed, so that the hollow fiber membrane according to the present invention can be obtained. On the other hand, it is clear that if the polysulfone membrane forming solution is extruded into the coagulation solution and air at a predetermined humidity is allowed to flow out from the inner tube, a hollow fiber membrane having a denser outer surface can be obtained. . Note that the network porous layer is a porous layer that is coarser than the outer surface, and the pore diameter of the pores in the network porous layer is usually about 10 times or more than the diameter of the micropores in the outer surface. be. In the method of the present invention, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, etc. are preferably used as the polar organic solvent for dissolving the aromatic polysulfone as described above to prepare a membrane forming solution. Ethylene glycol, diethylene glycol, or propylene glycol is used as a non-solvent that is miscible with the polar organic solvent but does not dissolve the aromatic polysulfone. The content of the non-solvent in the mixed solvent is not particularly limited as long as the resulting mixed solvent is uniform, but it is usually 5 to 50% by weight, preferably 20 to 45% by weight.
Weight%. The non-solvent in the membrane-forming solution contributes to the formation of a network porous layer and/or cavities in the above-mentioned coagulation process, and is effective in increasing the water permeability of the membrane. The higher the ratio, the higher the water permeability of the resulting hollow fiber semipermeable membrane. On the other hand, when a non-solvent is not used in the membrane forming solution, the water permeability of the membrane obtained is about 1/2 to 1/10 that of the membrane of the present invention. The concentration of aromatic polysulfone in the membrane forming solution is usually 5 to 35% by weight, preferably 10 to 30% by weight. If it exceeds 35% by weight, the water permeability of the resulting semipermeable membrane will be too low for practical use, while if it is less than 5% by weight, the resulting membrane will have poor mechanical strength. It is. Next, water is generally used as the coagulating liquid flowing into the inner pipe of the double pipe nozzle, but as mentioned above, a solvent that does not dissolve the aromatic polysulfone but is miscible with the polar organic solvent is used. Any solvent can be used, for example, the above-mentioned non-solvent or a mixed solvent of this and water. Furthermore, even if a solvent dissolves aromatic polysulfone alone, it can be used as a coagulating liquid by mixing it with another solvent as long as it does not dissolve polysulfone. In this way, the solidification time from when the membrane-forming solution is extruded into the air through the double pipe nozzle until it is immersed in water depends on the composition of the membrane-forming solution and the thickness of the membrane-forming solution when it is extruded from the nozzle. Although it depends on the situation, it is usually 2 seconds or more, preferably 3 to 10 seconds. As mentioned above, the hollow fiber semipermeable membrane obtained in this way usually has a total thickness of 50 to 450 μm.
Among these, the network porous layer usually has a thickness of 5 to 50μ.
m, in most cases a 20-40 .mu.m thick layer, on which no cavities lacking polysulfone depend. When this porous layer is thinner than 5 μm, it is not preferable because the membrane does not have practically sufficient mechanical strength and consolidation resistance. In addition, the diameter of the cavity in the finger-like structure layer in the transverse direction is usually 10 μm.
m or more. FIG. 1 shows an example of an aromatic polysulfone hollow fiber semipermeable membrane according to the method of the present invention, in which the inner surface has micropores with a smaller pore diameter and the outer surface has micropores with a larger pore diameter. An electron micrograph (200x magnification) of a cross section of the membrane is shown. Figure 2 is the inner surface (10000x magnification)
Figure 3 is an electron micrograph showing the outer surface (5000x magnification). As described above, according to the membrane of the present invention, the diameters of the micropores on the dense inner and outer surfaces of the membrane are different. Since the other surface having a . It is generally said that hollow fiber semipermeable membranes have excellent mechanical strength and consolidation resistance when they do not have cavities, but as described above, the hollow fiber semipermeable membranes of the present invention have cavities. However, it has excellent mechanical strength and consolidation resistance. This is probably because the network porous layer is relatively thick. at the same time,
Since the hollow fiber semipermeable membrane of the present invention has such an unprecedented structure, it is characterized by excellent water permeability, especially when the membrane is thick. The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples in any way. Example 1 In a mixed solvent of 58 parts by weight of N-methyl-2-pyrrolidone and 29 parts by weight of diethylene glycol, the formula Aromatic polysulfone having a repeating unit represented by 13 parts by weight of aromatic polysulfone was dissolved to obtain a membrane forming solution. In an atmosphere with a relative humidity of 80% and a temperature of 24°C, the above film forming solution was extruded from the outer tube of the double tube type nozzle, and water was allowed to flow out from the inner tube, and the above atmosphere was maintained for 5 seconds, and then from both surfaces. This was solidified, and then immersed in water to remove the solvent to obtain a hollow fiber semipermeable membrane with an inner diameter of 0.5 mm and an outer diameter of 0.9 mm. This semi-permeable membrane has a pure water permeation rate of 25.1 m ³ /m ^{2 /} day /
The removal rate for dextran with a molecular weight of 100,000 was 75%. In addition, water at room temperature was injected into the hollow fiber semipermeable membrane with one end sealed, and the burst strength was measured to be 18 Kg/cm ² . In addition, an electron micrograph (200x) of the cross section of the hollow fiber semipermeable membrane obtained above is shown in Figure 1, an electron micrograph (10,000x) of the inner surface is shown in Figure 2, and an electron micrograph of the outer surface ( 5000x) is shown in Figure 3. Examples 2 to 4 Polysulfone was dissolved in the same mixed solvent as in Example 1 to obtain membrane forming solutions with different polysulfone concentrations.
A hollow fiber semipermeable membrane of the same size was obtained using the same method as in Example 1. The physical properties of these films are shown in Table 1.

【表】実施例５ジメチルホルムアミド63重量部とエチレングリ
コール20重量部との混合溶剤に実施例１と同じポ
リスルホン17重量部を溶解して製膜溶液を得た。
この製膜溶液を用いて、実施例１と同様にして同
じ寸法の中空糸状半透膜を得た。この膜は、純水
透水速度11.5m³／m²・日・気圧であり、分子量10
万のデキストランに対する除去率は83％であつ
た。実施例６実施例１と同じ製膜溶液を用い、ノズルの径を
変えた以外は、実施例１と全く同じ方法によつて
中空糸状半透膜を得た。これら膜の純水透水速度
と膜厚の関係を第４図に示す。本発明の中空糸状半透膜は、透水性の膜厚依存
性が小さく、200μｍの厚みの膜も従来の膜に比
べて著しく大きい透水性を有する。実施例７実施例１において、芳香族ポリスルホンとしてで表わされる繰返し単位を有するものを用いた以
外は、実施例１と同様にして同じ寸法の中空糸状
半透膜を得た。この膜は、純水透水速度30.0m³／
m²・日・気圧、分子量10万のデキストランに対す
る除去率は77％であつて、破裂強度は18Kg／cm²で
あつた。比較例１実施例１において、紡糸雰囲気を相対湿度40％
とすると共に、この雰囲気下での凝固時間を２秒
間とした以外は、実施例１と全く同様にして中空
糸状半透膜を得た。この膜は、純水透水速度29.3m³／m²・日・気圧
であり、分子量10万のデキストランに対する除去
率は74％であつて、これらの膜性能は実施例１の
膜と同じであつたが、部分的に破壊強度が10Kg／
cm²の箇所が認められた。尚、この膜における破壊
は、外表面側の網状多孔質層と指状空洞構造層と
の間の部分的な層間剥離に基づくものであつて、
膜構造の不均一性によるのと考えられる。比較例２Ｎ−メチル−２−ピロリドン87重量部に実施例
１と同じポリスルホン13重量部を溶解して製膜溶
液を調製した。実施例１と同様にして同じ寸法の
中空糸状半透膜を得た。この膜は、純水透水速度
3.0m³／m²・日・気圧、分子量10万のデキストラ
ンに対する除去率は70％であつて、破裂強度は18
Kg／cm²であつて、透水性に著しく劣る。[Table] Example 5 A membrane forming solution was obtained by dissolving 17 parts by weight of the same polysulfone as in Example 1 in a mixed solvent of 63 parts by weight of dimethylformamide and 20 parts by weight of ethylene glycol.
Using this membrane forming solution, a hollow fiber semipermeable membrane with the same dimensions as in Example 1 was obtained. This membrane has a pure water permeability rate of 11.5 m ³ /m ² ·day·atmosphere and a molecular weight of 10
The removal rate against 10,000 dextran was 83%. Example 6 A hollow fiber semipermeable membrane was obtained in exactly the same manner as in Example 1, except that the same membrane forming solution as in Example 1 was used and the diameter of the nozzle was changed. The relationship between the pure water permeability rate and the membrane thickness of these membranes is shown in FIG. The hollow fiber semipermeable membrane of the present invention has a small dependence of water permeability on membrane thickness, and even a membrane with a thickness of 200 μm has significantly greater water permeability than conventional membranes. Example 7 In Example 1, as aromatic polysulfone A hollow fiber semipermeable membrane having the same dimensions as in Example 1 was obtained in the same manner as in Example 1, except that a membrane having a repeating unit represented by was used. This membrane has a pure water permeation rate of 30.0m ³ /
The removal rate for dextran with a molecular weight of ^100,000 m2/day/atm was 77%, and the bursting strength was 18 Kg/ ^cm2 . Comparative Example 1 In Example 1, the spinning atmosphere was set to a relative humidity of 40%.
A hollow fiber semipermeable membrane was obtained in exactly the same manner as in Example 1, except that the coagulation time in this atmosphere was 2 seconds. This membrane has a pure water permeability rate of 29.3 m ³ /m ² ·day · atmospheric pressure and a removal rate of 74% for dextran with a molecular weight of 100,000, which is the same as the membrane of Example 1. However, the breaking strength was partially 10Kg/
A ^cm2 area was observed. Incidentally, the fracture in this membrane is due to partial delamination between the reticulated porous layer and the finger-like cavity structure layer on the outer surface side,
This is thought to be due to the non-uniformity of the film structure. Comparative Example 2 A membrane forming solution was prepared by dissolving 13 parts by weight of the same polysulfone as in Example 1 in 87 parts by weight of N-methyl-2-pyrrolidone. A hollow fiber semipermeable membrane having the same dimensions as in Example 1 was obtained. This membrane has a pure water permeation rate of
The removal rate for dextran with a molecular weight of 100,000 at 3.0 m ³ /m ² / day / atm is 70%, and the bursting strength is 18
Kg/cm ² and extremely poor in water permeability.

[Brief explanation of drawings]

第１図乃至第３図は、本発明による高湿度法実
施例１で得た中空糸状半透膜の構造を示す走査型
電子顕微鏡写真を示し、第１図は断面（200倍）、
第２図は内表面（10000倍）、第３図は外表面
（5000倍）である。第４図は、本発明の方法によ
つて得た中空糸状膜における膜厚と透水性との関
係を示すグラフである。 Figures 1 to 3 show scanning electron micrographs showing the structure of the hollow fiber semipermeable membrane obtained in Example 1 of the high humidity method according to the present invention, and Figure 1 is a cross section (200x);
Figure 2 shows the inner surface (10,000x), and Figure 3 shows the outer surface (5,000x). FIG. 4 is a graph showing the relationship between membrane thickness and water permeability in hollow fiber membranes obtained by the method of the present invention.

Claims

[Scope of Claims] 1. One dense surface having micropores with a diameter of substantially 10 to 100 Å, and a pore having a diameter larger than that of the micropores,
and the other dense surface having micropores with a pore diameter substantially in the range of 0.02 to 2 μm, and the other dense surface having a pore diameter larger than that of any of the above surfaces, and substantially
A network porous layer with a thickness of 5 to 50 μm that has pores in the range of 0.05 to 5 μm and is continuous to each of the above surfaces, and a network porous layer that is continuous to the network porous layer and located approximately in the middle of the membrane; 1. An aromatic polysulfone hollow fiber semipermeable membrane comprising a finger-like structure layer having cavities extending substantially in the radial direction, and having a membrane thickness in the range of 50 to 450 μm. 2. Adding aromatic polysulfone to a mixture of a polar organic solvent that dissolves aromatic polysulfone and a solvent that is miscible with this solvent but does not dissolve aromatic polysulfone and is selected from ethylene glycol, diethylene glycol, and propylene glycol. When dissolving the polysulfone into a film-forming solution and extruding it from the outer tube of a double-tube nozzle to solidify the polysulfone, one surface is brought into contact with air with a relative humidity of 60% or more, and the other surface is brought into contact with the coagulation liquid. After that, by immersing it in water to remove the solvent, a dense surface with pores with a pore size of 10 to 100 Å is formed on the coagulation liquid side, and a pore size larger than the above pores is formed on the air side. , and form a dense surface having micropores with a pore diameter substantially in the range of 0.02 to 2 μm, and the pore diameter is larger than the micropores of any of the above surfaces and substantially in the range of 0.05 to 5 μm. A reticular porous layer having a thickness of 5 to 50 μm and having pores located at approximately 5 to 50 μm in thickness and continuous to each of the above surfaces, and a reticular porous layer located approximately in the middle of the membrane and located approximately in the middle of the membrane and approximately at the radius of the membrane. 1. A method for producing an aromatic polysulfone hollow fiber semipermeable membrane, the method comprising forming a finger-like structure layer having cavities extending in the direction to obtain a hollow fiber membrane having a thickness in the range of 50 to 450 μm.