JP2009006230A - Polymeric porous hollow fiber membrane - Google Patents

Polymeric porous hollow fiber membrane Download PDF

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JP2009006230A
JP2009006230A JP2007168646A JP2007168646A JP2009006230A JP 2009006230 A JP2009006230 A JP 2009006230A JP 2007168646 A JP2007168646 A JP 2007168646A JP 2007168646 A JP2007168646 A JP 2007168646A JP 2009006230 A JP2009006230 A JP 2009006230A
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hollow fiber
fiber membrane
membrane
film
polymer
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Junsuke Morita
純輔 森田
Noriaki Kato
典昭 加藤
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Toyobo Co Ltd
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Toyobo Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a polymeric porous hollow membrane with high durability which reduces the crush of a hollow fiber membrane against an external pressure in a porous hollow fiber membrane utilized for mainly treating an aqueous fluid. <P>SOLUTION: The polymeric porous hollow fiber membrane is disclosed in which 0.1≤Δd/ID≤0.5 is expressed wherein an inner diameter of the hollow fiber membrane is ID (mm) and a membrane thickness is Δd (mm) respectively, in which both the thickness deviation and the roundness of the hollow fiber membrane are 0.75 or more, and in which a dense layer is on the outer surface of the hollow fiber membrane and also when the external pressure of 0.4 MPa is applied for 30 min from the outer side of the hollow fiber membrane the number of the crushes generated in the hollow fiber membrane is one or less per km of the hollow fiber membrane and the water permeability of the hollow fiber membrane is 500 L/hr/m<SP>2</SP>/bar. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は、高分子多孔質中空糸膜に関するものである。さらに詳しくは、主として水性流体の処理に利用される高分子多孔質中空糸膜において、逆洗等の外圧に対する中空糸膜の潰れを低減した、耐圧性、耐久性の高い高分子多孔質中空糸膜に関するものである。   The present invention relates to a polymer porous hollow fiber membrane. More specifically, in a polymer porous hollow fiber membrane mainly used for treatment of an aqueous fluid, a polymer porous hollow fiber having high pressure resistance and durability, in which collapse of the hollow fiber membrane against an external pressure such as backwashing is reduced. It relates to membranes.

今日、高分子多孔質膜はさまざまな分野において利用されており、中でも中空糸膜はその容積効率の高さから、精密濾過、限外濾過といった工業用途から血液透析、血液透析濾過といった医療用途まで広く利用されている。   Today, polymer porous membranes are used in various fields. Among them, hollow fiber membranes have high volumetric efficiency, from industrial applications such as microfiltration and ultrafiltration to medical applications such as hemodialysis and hemodiafiltration. Widely used.

一般に、これらの高分子多孔質中空糸膜に要求される特性として、透過性能および機械的強度が高いこと、化学的安定性などが挙げられるが、高い透過性能を発現させるためには、中空糸膜中の空孔率や孔径を上げる必要があるために機械的強度が犠牲になってしまうことが少なくない。この課題を解決するために中空糸膜素材の適正選択や構造の改善など、さまざまな対応がなされ、今日では幾分過酷な条件にでも耐えうる高分子多孔質中空糸膜が提供されるようになってきた。   In general, the properties required for these polymer porous hollow fiber membranes include high permeation performance and mechanical strength, chemical stability, etc. In order to develop high permeation performance, hollow fibers Since it is necessary to increase the porosity and the hole diameter in the film, mechanical strength is often sacrificed. In order to solve this problem, various measures such as appropriate selection of the hollow fiber membrane material and improvement of the structure have been made, and today, a polymer porous hollow fiber membrane that can withstand even severe conditions is provided. It has become.

例えば、特許文献１では、ポリアクリロニトリル系高分子を用いて、透水性と機械的強度の両立を可能にした技術を開示している。また特許文献２では、コストアップやコンパクト性の喪失につながるが、補強用繊維を用いることによって、機械的強度を補う技術を開示している。
特開２００６−０００８１０号公報 特開２０００−２８７０４４号公報 For example, Patent Document 1 discloses a technique that makes it possible to achieve both water permeability and mechanical strength using a polyacrylonitrile-based polymer. Patent Document 2 discloses a technique for supplementing mechanical strength by using reinforcing fibers, although this leads to cost increase and loss of compactness.
Japanese Patent Laid-Open No. 2006-000810 JP 2000-287044 A

これらの高分子多孔質中空糸膜の中でも主に水性流体処理に用いられるものは、使用の際に、中空糸膜の内側から処理流体を通過させる順ろ過と、一定期間使用後、外側からの加圧を行い、膜内のつまりや汚れを除去する逆洗と呼ばれる処理を繰り返し行っている。しかしながら、この順ろ過と逆洗を繰り返す過程において、外圧に耐えきれず、部分的に潰れが生じ、これに起因した膜の破損が起こることがある。このような現象は、実際のフィールドにて長期使用してみて初めて分かることが多いので、中空糸膜の品質評価時や短期のラボテストにおいては確認が困難であり、現実的には効果的な解決策が見出されておらず、今後の改善が強く期待されていた。   Among these polymer porous hollow fiber membranes, those mainly used for aqueous fluid treatment are, in use, forward filtration that allows the treatment fluid to pass from the inside of the hollow fiber membrane, and after a certain period of use, from the outside. A process called back washing for removing clogging and dirt in the film is repeatedly performed by applying pressure. However, in the process of repeating this forward filtration and backwashing, it may not be able to withstand the external pressure and may be partially crushed, resulting in damage to the membrane. Such a phenomenon is often found only after long-term use in an actual field, so it is difficult to confirm at the time of hollow fiber membrane quality evaluation or in a short-term laboratory test. No measures were found, and future improvements were strongly expected.

そこで本発明は、こういった従来技術に鑑み、主として水性流体の処理に利用される高分子多孔質中空糸膜において、外圧に対する中空糸膜の潰れを低減した耐久性の高い高分子多孔質中空糸膜を提供することを目的とする。   Therefore, in view of such conventional technology, the present invention is a highly porous polymer hollow fiber that reduces collapse of the hollow fiber membrane against external pressure in a polymer porous hollow fiber membrane mainly used for treatment of aqueous fluids. An object is to provide a yarn membrane.

上記の課題を解決することができる本発明の高分子多孔質中空糸膜は、以下の構成よりなる。
（１）（a）中空糸膜の内径をID(mm)、膜厚をΔd(mm)としたとき、0.25≦Δd／ID≦0.5であり、
（b）中空糸膜の偏肉度が0.75以上であり、
（c）中空糸膜の真円度が0.75以上であり、
（d）中空糸膜の外側より30分間0.4MPaの外圧をかけたとき、中空糸膜に生じる潰れの個数が、中空糸膜1kmあたり1個以下であり、
（e）中空糸膜の透水性が500L/hr/m2/bar以上である
ことを特徴とする高分子多孔質中空糸膜。
（２）中空糸膜が非対称構造を有することを特徴とする高分子多孔質中空糸膜。
（３）中空糸膜が主として疎水性高分子からなることを特徴とする高分子多孔質中空糸膜。
（４）疎水性高分子がポリスルホン系高分子であることを特徴とする高分子多孔質中空糸膜。
（５）中空糸膜の外表面に緻密層を持つことを特徴とする高分子多孔質中空糸膜。
（６）中空糸膜の内表面および外表面に緻密層を持ち、内表面から膜内部に向かって当初孔径が次第に増大し、少なくとも一つの極大部を通過後、外表面に向かって孔径が次第に減少することを特徴とする高分子多孔質中空糸膜。
（７）中空糸膜の外径をOD(mm)としたとき、0.4≦ODであることを特徴とする高分子多孔質中空糸膜。 The polymer porous hollow fiber membrane of the present invention capable of solving the above-mentioned problems has the following configuration.
(1) (a) When the inner diameter of the hollow fiber membrane is ID (mm) and the film thickness is Δd (mm), 0.25 ≦ Δd / ID ≦ 0.5,
(B) The uneven thickness of the hollow fiber membrane is 0.75 or more,
(C) The roundness of the hollow fiber membrane is 0.75 or more,
(D) When an external pressure of 0.4 MPa is applied for 30 minutes from the outside of the hollow fiber membrane, the number of crushes generated in the hollow fiber membrane is 1 or less per 1 km of the hollow fiber membrane,
(E) A polymer porous hollow fiber membrane, wherein the water permeability of the hollow fiber membrane is 500 L / hr / m 2 / bar or more.
(2) A polymer porous hollow fiber membrane, wherein the hollow fiber membrane has an asymmetric structure.
(3) A polymer porous hollow fiber membrane characterized in that the hollow fiber membrane is mainly composed of a hydrophobic polymer.
(4) A polymer porous hollow fiber membrane, wherein the hydrophobic polymer is a polysulfone polymer.
(5) A polymer porous hollow fiber membrane having a dense layer on the outer surface of the hollow fiber membrane.
(6) Having a dense layer on the inner and outer surfaces of the hollow fiber membrane, the initial pore diameter gradually increases from the inner surface toward the inside of the membrane, and after passing through at least one local maximum, the pore diameter gradually increases toward the outer surface. A polymer porous hollow fiber membrane characterized by decreasing.
(7) A polymeric porous hollow fiber membrane, wherein 0.4 ≦ OD when the outer diameter of the hollow fiber membrane is OD (mm).

本発明の高分子多孔質中空糸膜は、洗浄プロセスにおける中空糸膜の部分的な潰れを抑制しているので、膜の破損を防ぎ、耐久性の高い長期間使用可能な高分子多孔質中空糸膜を提供することが可能である。   The polymer porous hollow fiber membrane of the present invention suppresses partial crushing of the hollow fiber membrane in the washing process, so that the membrane is prevented from being damaged and is highly durable and can be used for a long period of time. It is possible to provide a yarn membrane.

以下に本発明の高分子多孔質中空糸膜について詳細に説明する。   The polymer porous hollow fiber membrane of the present invention will be described in detail below.

本発明者らは、従来の高分子多孔質中空糸膜に生じる外圧による潰れについて詳細に検討を実施した。従来の評価方法では、20cm程度の中空糸膜10本程度から評価用の小規模のモジュール（以下ミニモジュールと呼ぶ）を作製し、耐圧性を評価することがほとんどであったが、水処理等の実際のフィールドで用いられるモジュールの規模を考え、より精度よく評価できるよう、1m前後の中空糸膜150本程度をモジュール化し、評価できる方法を確立した。その結果、驚くべきことに、ミニモジュールでの評価では外圧による潰れがまったく見られなかった中空糸膜においても同圧力の外圧によって潰れる部分が確認できることが明らかになった。   The inventors of the present invention have studied in detail the collapse due to the external pressure generated in the conventional polymer porous hollow fiber membrane. In the conventional evaluation method, it was almost possible to produce a small module for evaluation (hereinafter referred to as a mini module) from about 10 hollow fiber membranes of about 20 cm and evaluate pressure resistance. Considering the scale of the modules used in the actual field, we have established a method that can modularize and evaluate about 150 hollow fiber membranes of around 1m so that they can be evaluated more accurately. As a result, it was surprisingly found that even in hollow fiber membranes that were not crushed by external pressure in the mini-module evaluation, a portion that was crushed by the external pressure at the same pressure could be confirmed.

すなわち、中空糸膜には外圧に対して弱い部分が存在し、その外圧耐性の違いから、中空糸膜全体に同じ圧力がかかっているとき、多くの部分は潰れに至らないが、一部の弱い部分が潰れとなってあらわれることがあるということを発見した。すなわち、従来のミニモジュールでの評価では、長さの短さや糸本数の少なさのために上記の弱い部分をピックアップできる確率が低く、外圧に対する潰れを検出しにくいが、モジュールの規模を大きくすることで検出できるようになったと考えられる。言い換えれば、製膜条件の最適化や製膜技術の向上により、中空糸膜に含まれる欠点は飛躍的に減少しているが、非常に少ないながらも現在でもなお生じているということである。ここで外圧による潰れとは、中空糸膜外側より圧力をかけたとき、中空糸膜の一部または大部分が変形し、外径の最小部が最大部の半分以下になった部分を対象とする。   That is, the hollow fiber membrane has a portion that is weak against external pressure, and due to the difference in external pressure resistance, when the same pressure is applied to the entire hollow fiber membrane, many portions do not collapse, I discovered that the weak parts could be crushed. That is, in the evaluation with the conventional mini-module, the probability of picking up the weak part is low due to the short length and the small number of yarns, and it is difficult to detect crushing against external pressure, but the scale of the module is increased. It is thought that it became possible to detect by this. In other words, the defects contained in the hollow fiber membranes have been dramatically reduced by optimizing the membrane production conditions and improving the membrane production technology, but it still occurs even though it is very small. Here, crushing due to external pressure refers to a portion where a part or most of the hollow fiber membrane is deformed when pressure is applied from the outside of the hollow fiber membrane and the minimum part of the outer diameter is less than half of the maximum part. To do.

そこで、該潰れの発生についてさらに検討を進めた。中空糸膜にこのような部分的に弱い部分が生じてしまう原因を突き止めるため、膜原料が均一に混合・溶解されていることは勿論のこととして、ノズルより吐出され製膜されていく過程から最終的に巻き上げられるまで、外圧による潰れの発生状況を詳細に調査した。その結果、なんと中空糸膜を巻き上げる際の糸のまとめ方によって、潰れの発生状況に大きな差異があらわれることを見出した。この結果をもとにさらに深く検討を実施したところ、巻き上げ前に多数の中空糸膜をまとめてしまうと、中空糸膜同士に捩れが生じてしまうことが分かり、これが巻き上げ時のテンションによって固定または増幅され、中空糸膜に局部的なストレスやダメージを与えているのではないかとの推察に至った。従って、巻き上げ直前まで極力捩れを生じさせないように配慮し、テンションが付与される巻き上げ時の中空糸膜の不規則な重なりを防止する一方、中空糸膜へのテンションを低減させることで大幅に外圧による潰れの発生を低減できることを見出した。特に外径の大きい中空糸膜においてはこの傾向が顕著であった。また、巻き上げ機にはテンションを一定に保つために、ダンサローラーと呼ばれる小径のローラーが備えられており、このローラーを通って中空糸膜が巻き上げられるが、このローラー径を大きくすることにより中空糸膜の屈曲を低減することも効果を期待できる。   Therefore, further investigation was made on the occurrence of the collapse. In order to find out the cause of such a weak part in the hollow fiber membrane, it goes without saying that the membrane raw material is uniformly mixed and dissolved, as well as from the process of being discharged from the nozzle and formed into a film Until it was finally wound up, the occurrence of crushing due to external pressure was investigated in detail. As a result, it has been found that there is a great difference in the occurrence of crushing depending on how the yarns are bundled when winding the hollow fiber membrane. Further investigation based on this result revealed that twisting of the hollow fiber membranes would occur if a large number of hollow fiber membranes were put together before winding, and this would be fixed by the tension during winding. As a result of amplification, the hollow fiber membrane was presumed to be locally stressed or damaged. Therefore, care must be taken not to cause twisting as much as possible immediately before winding, preventing irregular overlap of the hollow fiber membranes during winding when tension is applied, while reducing the tension on the hollow fiber membranes to significantly reduce external pressure. It has been found that the occurrence of crushing due to can be reduced. This tendency was particularly remarkable in the hollow fiber membrane having a large outer diameter. In order to keep the tension constant, the hoisting machine is equipped with a small-diameter roller called a dancer roller, and the hollow fiber membrane is wound up through this roller. An effect can also be expected by reducing the bending of the film.

そこで本発明者らは上記のような外圧による潰れ発生の状況やメカニズムから該方策を鋭意検討し、本発明を完成した。   Therefore, the present inventors diligently studied the measures from the situation and mechanism of occurrence of crushing due to the external pressure as described above, and completed the present invention.

すなわち、本発明においては、中空糸膜の内径をID(mm)、膜厚をΔd(mm)としたとき、0.25≦Δd／ID≦0.5であり、かつ中空糸膜の偏肉度が0.75以上かつ真円度が0.75以上である中空糸膜において、中空糸膜の透水性が500L/hr/m2/bar以上であり、かつ中空糸膜の外側より30分間0.4MPaの外圧をかけたときに中空糸膜に生じる潰れの個数が中空糸膜1kmあたり1個以下である。 That is, in the present invention, when the inner diameter of the hollow fiber membrane is ID (mm) and the film thickness is Δd (mm), 0.25 ≦ Δd / ID ≦ 0.5, and the uneven thickness of the hollow fiber membrane is 0.75 or more. In addition, in a hollow fiber membrane having a roundness of 0.75 or more, the water permeability of the hollow fiber membrane is 500 L / hr / m 2 / bar or more, and an external pressure of 0.4 MPa is applied for 30 minutes from the outside of the hollow fiber membrane. In addition, the number of collapses generated in the hollow fiber membrane is 1 or less per 1 km of the hollow fiber membrane.

本発明において、中空糸膜の内径IDと膜厚Δdの関係は、0.25≦Δd／ID≦0.5であるが、0.25未満であると内径に比して膜厚の割合が小さくなるため、外圧に対する耐久度が本質的に低くなり、本発明を適用しても透水性と潰れ耐性を両立させることが難しくなる。また、0.5を超えると膜厚が太くなることで中空糸膜が本質的に丈夫なものとなるため、本発明の適用効果が小さい。さらには膜厚を太くするために多くの膜原料が必要となるためコスト的なデメリットが大きい上、内径基準の中空糸膜の有効膜面積に対して外径が大きくなってしまうため中空糸膜モジュールとしたときのコンパクト性が損なわれてしまう。したがって、より好ましくは0.25≦Δd／ID≦0.4であり、さらに好ましくは0.25≦Δd／ID≦0.3である。   In the present invention, the relationship between the inner diameter ID and the film thickness Δd of the hollow fiber membrane is 0.25 ≦ Δd / ID ≦ 0.5, but if it is less than 0.25, the ratio of the film thickness is smaller than the inner diameter, The durability is essentially low, and it is difficult to achieve both water permeability and crush resistance even when the present invention is applied. On the other hand, if the ratio exceeds 0.5, the hollow fiber membrane is essentially strong because the film thickness becomes thick, so that the application effect of the present invention is small. Furthermore, since many membrane raw materials are required to increase the film thickness, the cost disadvantage is large, and the outer diameter becomes larger than the effective membrane area of the hollow fiber membrane based on the inner diameter. The compactness of the module is lost. Therefore, more preferably, 0.25 ≦ Δd / ID ≦ 0.4, and further preferably 0.25 ≦ Δd / ID ≦ 0.3.

上記の関係を満たせば中空糸膜の外径OD(mm)については特段の限定は必要ないが、ODが大きくなるほど屈曲部での変化度合いが大きくなるし、物理的に中空糸膜同士の重なりが増加してしまうために捩れが生じやすく、局部的なストレス・ダメージをより高い確率で受けやすくなる。したがって、ODがあまりに小さい場合には本発明の効果が現れにくくなるため、本発明の効果をより享受しやすいという観点から、好ましくは0.4≦ODである。また、ODがあまりにも大きくなりすぎると、中空糸膜モジュールとしての機能を損なうおそれがあるため、より好ましくは、0.4≦OD≦5である。   If the above relationship is satisfied, there is no particular limitation on the outer diameter OD (mm) of the hollow fiber membrane, but the greater the OD, the greater the degree of change at the bent part, and the physical overlap between the hollow fiber membranes. Therefore, twisting is likely to occur, and local stress and damage are more likely to occur. Therefore, when the OD is too small, the effect of the present invention is difficult to appear. From the viewpoint that the effect of the present invention is more easily enjoyed, 0.4 ≦ OD is preferable. Further, if the OD is too large, the function as the hollow fiber membrane module may be impaired. Therefore, 0.4 ≦ OD ≦ 5 is more preferable.

本発明における中空糸膜の偏肉度は0.75以上が好ましいが、0.75未満と偏肉度がひどくなると、膜厚の薄い部分と厚い部分との差が大きくなるため、膜厚の薄い部分で外圧に対する耐性がもともと低い状態となってしまうため、本発明を適用しても効果が得られないことがある。よって、より好ましい偏肉度は0.8以上であり、さらに好ましくは0.85以上である。   The thickness deviation of the hollow fiber membrane in the present invention is preferably 0.75 or more, but if the thickness deviation is less than 0.75, the difference between the thin portion and the thick portion becomes large. As a result, the effect of the present invention may not be obtained even if the present invention is applied. Therefore, a more preferable uneven thickness is 0.8 or more, and more preferably 0.85 or more.

また、本発明における中空糸膜の真円度は0.75以上が好ましいが、真円度が0.75未満というような楕円もしくは偏平に近い状態となると、中空糸膜に外圧をかけたときの圧力のかかり方がより偏平に近づけようとする向きに働くため、こちらも本発明を適用しても効果が得られないことがある。よって、より好ましい真円度は0.8以上であり、さらに好ましくは0.85以上である。   In addition, the roundness of the hollow fiber membrane in the present invention is preferably 0.75 or more. However, when the roundness is less than 0.75, when the roundness is close to an ellipse or flat, the pressure applied when external pressure is applied to the hollow fiber membrane. Since this works in a direction to make it closer to flatness, the effect may not be obtained even if the present invention is applied. Therefore, a more preferable roundness is 0.8 or more, and further preferably 0.85 or more.

本発明における中空糸膜の透水性は500L/hr/m2/bar以上が好ましいが、透水性が500L/hr/m2/bar未満であると、中空糸膜中の空孔率や孔径が小さいか、または孔数が少ないために本質的に中空糸膜の強度（剛性）が高いことが多く、本発明によっても顕著な効果を得られにくい。また逆に透水性が高すぎる場合には根本的に膜基材が脆弱となってしまっている可能性があるため、より好ましい中空糸膜の透水性は600L/hr/m2/bar以上3000L/hr/m2/bar以下である。 The water permeability of the hollow fiber membrane in the present invention is preferably 500 L / hr / m 2 / bar or more, but if the water permeability is less than 500 L / hr / m 2 / bar, the porosity and pore diameter in the hollow fiber membrane are Since it is small or has a small number of pores, the strength (rigidity) of the hollow fiber membrane is often high, and it is difficult to obtain a remarkable effect even by the present invention. On the other hand, if the water permeability is too high, the membrane substrate may be fundamentally fragile, so the water permeability of the more preferable hollow fiber membrane is 600 L / hr / m 2 / bar or more and 3000 L. / hr / m 2 / bar or less.

本発明において、中空糸膜の外側より30分間0.4MPaの外圧をかけたときの中空糸膜に生じる潰れの個数は、中空糸膜長さ1kmあたり1個以下であるのが好ましい。用途や運転方法により違いはあるが、中空糸膜が水性流体処理時の逆洗で受ける外圧は最大で0.1〜0.2MPa程度であり、この外圧に対する耐性が中空糸膜に求められる重要な特性の1つである。外圧に対する耐性が低いと、逆洗によって中空糸膜に潰れが発生し、その後の使用で十分な性能が得られなくなるばかりか、膜の破損を引き起こす原因となる。従って本発明では、逆洗による外圧への耐性を規定できる指標を検討し、30分間0.4MPaの外圧をかけたときの中空糸膜に生じる潰れの個数で表記する。すなわち、実使用時には逆洗は繰り返し行われるため、出荷においては最大外圧よりも高い圧力で検査を行い長期使用における耐性を検証する必要があることから、中空糸膜にかける外圧は通常逆洗時の圧力の2〜4倍となる0.4MPaに設定し、また、ある程度の時間をかけて潰れが生じることがあるため、適正な時間を検討した結果、30分間で十分な検出力があることを確認した。潰れの個数が多いと、外圧に対する耐性が弱い点が多く存在することを意味するので、すなわち実使用時の膜破損を引き起こす可能性が高くなる。また、モジュール1本当たりの中空糸膜の総長さは凡そ2〜20kmであるが、言うまでも無く中空糸膜潰れの個数は少ないほど好ましく、より好ましくは0.5個／km以下、さらに好ましくは0.1個／km以下である。   In the present invention, it is preferable that the number of collapses generated in the hollow fiber membrane when an external pressure of 0.4 MPa is applied for 30 minutes from the outside of the hollow fiber membrane is 1 or less per 1 km of the hollow fiber membrane length. Although there are differences depending on the application and operation method, the external pressure that the hollow fiber membrane receives by backwashing during aqueous fluid treatment is about 0.1 to 0.2 MPa at the maximum, and the resistance to this external pressure is an important characteristic required for hollow fiber membranes. One. If the resistance to external pressure is low, the hollow fiber membrane will be crushed by backwashing, and sufficient performance will not be obtained with subsequent use, and it will cause damage to the membrane. Therefore, in this invention, the index which can prescribe | regulate the tolerance to the external pressure by backwashing is examined, and it describes with the number of crushing which arises in a hollow fiber membrane when an external pressure of 0.4 MPa is applied for 30 minutes. In other words, since backwashing is repeatedly performed during actual use, it is necessary to verify the durability in long-term use by inspecting at a pressure higher than the maximum external pressure at the time of shipment. The pressure is set to 0.4MPa, which is 2 to 4 times the pressure, and crushing may occur over a certain amount of time. confirmed. When the number of crushing is large, it means that there are many points with low resistance to external pressure, that is, there is a high possibility of causing film breakage during actual use. The total length of the hollow fiber membranes per module is about 2 to 20 km. Needless to say, the smaller the number of hollow fiber membranes crushed, the more preferable, more preferably 0.5 pieces / km or less, and still more preferably 0.1 No more than pieces / km.

また、中空糸膜の構造について説明する。膜の内表面から外表面にかけて膜基材の粗密度合いが大幅に変化する構造を非対称構造と呼び、逆に変化が少ない構造を均質構造と呼ぶ。本発明における中空糸膜の構造は、均質構造でも構わないが、より本発明の効果が得られやすいという観点から、非対称構造であることが好ましい。つまり、非対称構造を有する膜では、中空糸膜を屈曲させたときの歪みのかかり方が膜厚方向で異なるため、これによって中空糸膜に対して局部的なストレスやダメージが発生しやすく、外圧をかけたときに部分的な潰れが生じやすいと考えられるためである。また非対称構造の中でも、中空糸膜外表面に緻密な層を持ち、膜内部が疎な構造を有する場合には、外圧を受けたときに膜内部に向けて凹みやすい構造であると考えられるため、より本発明の効果を享受しやすいため好ましい。さらに、かかる観点から、内表面および外表面に緻密な層を持ち、内表面と外表面の間の膜内部に比較的孔径の大きな疎な部分が存在するような膜構造を持つ中空糸膜に対して本発明を適用するとより好ましい。   The structure of the hollow fiber membrane will be described. A structure in which the degree of coarse density of the film substrate changes greatly from the inner surface to the outer surface of the film is called an asymmetric structure, and conversely, a structure with little change is called a homogeneous structure. The structure of the hollow fiber membrane in the present invention may be a homogeneous structure, but is preferably an asymmetric structure from the viewpoint that the effects of the present invention are more easily obtained. In other words, in a membrane having an asymmetric structure, the strain applied when the hollow fiber membrane is bent differs depending on the film thickness direction, which tends to cause local stress and damage to the hollow fiber membrane. This is because it is considered that partial crushing is likely to occur when applying. In addition, among the asymmetric structures, when the hollow fiber membrane has a dense layer on the outer surface and the membrane has a sparse structure, it is considered that the structure tends to dent toward the inside of the membrane when subjected to external pressure. It is preferable because the effect of the present invention can be easily enjoyed. Furthermore, from this point of view, a hollow fiber membrane having a membrane structure having a dense layer on the inner surface and the outer surface and a sparse portion having a relatively large pore diameter in the membrane between the inner surface and the outer surface. On the other hand, it is more preferable to apply the present invention.

本発明の高分子多孔質中空糸膜は、内表面が緻密であることにより、クロスフロー濾過による内表面でのせん断力の効果も効いて、膜特性が保持されやすい。さらに、密−疎−密構造の内表面が緻密層であるため、逆洗時に被除去物質が外れやすく、膜特性の回復性に優れる。外面緻密層においても被除去物質のトラップは行われていると考えられるが、逆洗時には孔径小→孔径大方向に洗浄液が流れるので、前記トラップされた被除去物質が外れやすい。また、詳細な機構は不明だが、恐らくは密−疎−密の構造のため、膜壁内部での洗浄液の流れが非直線的にランダム化することで、洗浄効果がより高まるものと考えられる。   In the polymer porous hollow fiber membrane of the present invention, since the inner surface is dense, the effect of shearing force on the inner surface by cross flow filtration is also effective, and the membrane characteristics are easily maintained. Furthermore, since the inner surface of the dense-sparse-dense structure is a dense layer, the substance to be removed is easily removed during backwashing, and the film characteristics are highly recoverable. Although it is considered that the substance to be removed is also trapped in the outer dense layer, the cleaning substance flows easily in the direction of small pore diameter → large pore diameter during backwashing, so that the trapped substance to be removed tends to come off. Further, although the detailed mechanism is unknown, it is probably a dense-sparse-dense structure, and it is considered that the cleaning effect is further enhanced by non-linearly randomizing the flow of the cleaning liquid inside the membrane wall.

本発明の高分子多孔質中空糸膜の径は、使用される用途に応じて適宜設定すればよく、特に制限されないが、内径は100〜1500μmが好ましく、より好ましくは200〜1300μm、さらに好ましくは250〜1200μmである。内径が小さすぎると、用途によっては被処理液中の成分により内腔の閉塞などが生じる可能性がある。また、内径が大きすぎると、中空糸膜の潰れ、ゆがみなどが生じやすくなる。   The diameter of the polymeric porous hollow fiber membrane of the present invention may be appropriately set according to the intended use, and is not particularly limited, but the inner diameter is preferably 100-1500 μm, more preferably 200-1300 μm, still more preferably 250-1200 μm. If the inner diameter is too small, depending on the application, the lumen may be blocked by components in the liquid to be treated. If the inner diameter is too large, the hollow fiber membrane is liable to be crushed or distorted.

本発明の高分子多孔質中空糸膜においては、膜厚は40〜400μmであるのが好ましい。膜厚が小さすぎると、中空糸膜の潰れ、ゆがみなどが生じやすくなる。膜厚が大きすぎると、処理流体が膜壁を通過する際の抵抗が大きくなり、透過性が低下する可能性がある。したがって、膜厚は60〜400μmがより好ましく、75〜380μmがさらに好ましい。   In the polymer porous hollow fiber membrane of the present invention, the film thickness is preferably 40 to 400 μm. When the film thickness is too small, the hollow fiber membrane is liable to be crushed or distorted. If the film thickness is too large, the resistance when the processing fluid passes through the film wall increases, and the permeability may decrease. Therefore, the film thickness is more preferably 60 to 400 μm, and further preferably 75 to 380 μm.

本発明の高分子多孔質中空糸膜の内表面における孔径は、0.001〜1μmであることが好ましく、0.01〜0.3μmがより好ましく、0.03〜0.08μmがさらに好ましい。これよりも孔径が小さいと透過性が低くなることがある。また、これよりも大きいと膜の強度が低下することがある。また、内表面における空孔率は5〜30％が好ましく、7〜25％がより好ましく、10〜20％がさらに好ましい。空孔率が小さすぎると透過性が低くなることがある。また、空孔率が大きすぎると膜の強度が低下することがある。   The pore diameter on the inner surface of the polymer porous hollow fiber membrane of the present invention is preferably 0.001 to 1 μm, more preferably 0.01 to 0.3 μm, and further preferably 0.03 to 0.08 μm. If the pore diameter is smaller than this, the permeability may be lowered. On the other hand, if it is larger than this, the strength of the film may be lowered. Further, the porosity on the inner surface is preferably 5 to 30%, more preferably 7 to 25%, and further preferably 10 to 20%. If the porosity is too small, the permeability may be lowered. Moreover, when the porosity is too large, the strength of the film may be lowered.

本発明の高分子多孔質中空糸膜は膜壁部分に空孔率が極大となる部位が存在するのが特徴のひとつであるが、この極大部における孔径は、内表面、外表面での孔径よりも大きく、かつ、0.1〜5μmであることが好ましく、0.2〜3μmであることがより好ましく、0.25〜1.5μmであることがさらに好ましい。極大部における孔径が小さすぎると膜構造の傾斜が緩やかとなるため、膜特性、膜特性の保持性、膜特性の回復性が低下することがある。また、極大部における孔径が大きすぎると膜の強度が低下する可能性がある。
また、極大部における空孔率は、内表面、外表面での空孔率よりも大きく、かつ、40〜80％であることが好ましく、45〜70％であることがより好ましく、45〜63％がさらに好ましい。空孔率が小さすぎると膜構造の傾斜が緩やかとなるため、膜特性、膜特性の保持性、膜特性の回復性が低下することがある。極大部における空孔率が大きすぎると膜の強度が低下する可能性がある。 The polymer porous hollow fiber membrane of the present invention is characterized in that there is a portion where the porosity is maximized in the membrane wall portion. The pore diameter at this maximum portion is the pore diameter at the inner surface and the outer surface. It is preferably 0.1 to 5 μm, more preferably 0.2 to 3 μm, and still more preferably 0.25 to 1.5 μm. If the pore diameter in the maximum portion is too small, the inclination of the film structure becomes gentle, so that the film characteristics, the retention of the film characteristics, and the recoverability of the film characteristics may deteriorate. Moreover, when the pore diameter in the maximum portion is too large, the strength of the film may be lowered.
Further, the porosity in the maximum portion is larger than the porosity on the inner surface and the outer surface, and is preferably 40 to 80%, more preferably 45 to 70%, and more preferably 45 to 63. % Is more preferable. If the porosity is too small, the inclination of the film structure becomes gentle, so that the film characteristics, the retention of the film characteristics, and the recoverability of the film characteristics may deteriorate. If the porosity in the maximum portion is too large, the strength of the film may decrease.

外表面における孔径は特に制限されないが、0.02〜2μmが好ましく、0.04〜1μmがより好ましく、0.06〜0.3μmがさらに好ましい。孔径が小さすぎると透過性が低くなることがあり、大きすぎると膜の強度が低下する可能性がある。
外表面における空孔率は特に制限されないが、5〜30％であることが好ましく、7〜25％であることがより好ましく、10〜20％がさらに好ましい。空孔率が小さすぎると透過性が低く、隣接する中空糸膜同士の固着がおこりやすくなり、大きすぎると膜の強度が低下する可能性がある。 The pore diameter on the outer surface is not particularly limited, but is preferably 0.02 to 2 μm, more preferably 0.04 to 1 μm, and further preferably 0.06 to 0.3 μm. If the pore size is too small, the permeability may be lowered, and if it is too large, the strength of the membrane may be lowered.
The porosity in the outer surface is not particularly limited, but is preferably 5 to 30%, more preferably 7 to 25%, and further preferably 10 to 20%. If the porosity is too small, the permeability is low, and the adjoining hollow fiber membranes are likely to stick together. If the porosity is too large, the strength of the membrane may be reduced.

本発明の高分子多孔質中空糸膜の用途は特に限定されず、精密ろ過（MF）や限外ろ過（UF）、細菌・微粒子の除去フィルターなどが挙げられるが、本発明によって得られる高い耐外圧特性を十分に発揮するため、実使用時に高い外圧が中空糸膜に付加される水処理用高分子多孔質中空糸膜に対して特に好適に使用できる。   The use of the polymer porous hollow fiber membrane of the present invention is not particularly limited, and examples thereof include microfiltration (MF), ultrafiltration (UF), bacteria / fine particle removal filter, and the like. In order to sufficiently exhibit the external pressure characteristics, it can be particularly suitably used for a polymer porous hollow fiber membrane for water treatment in which a high external pressure is applied to the hollow fiber membrane during actual use.

以下、本発明の高分子多孔質中空糸膜の製造方法について具体的に説明する。
本発明において、疎水性高分子としては、例えば、ポリエステル、ポリカーボネート、ポリウレタン、ポリアミド、ポリスルホン（以下PSfと略記する）、ポリエーテルスルホン（以下PESと略記する）、ポリメチルメタクリレート、ポリプロピレン、ポリエチレン、ポリフッ化ビニリデン、セルロース（トリ）アセテートなどが例示される。中でも、下記の式［１］、［２］で示される繰返し単位を有するPSf、PESなどのポリスルホン系高分子は高い透水性の膜を得るのに有利であり、好ましい。ここで言うポリスルホン系高分子は、官能基やアルキル基などの置換基を含んでいてもよく、炭化水素骨格の水素原子はハロゲンなど他の原子や置換基で置換されていてもよい。また、これらは単独で使用しても、2種以上を混合して使用してもよい。
Hereafter, the manufacturing method of the polymeric porous hollow fiber membrane of this invention is demonstrated concretely.
In the present invention, examples of the hydrophobic polymer include polyester, polycarbonate, polyurethane, polyamide, polysulfone (hereinafter abbreviated as PSf), polyethersulfone (hereinafter abbreviated as PES), polymethyl methacrylate, polypropylene, polyethylene, polyfluoride. Examples thereof include vinylidene chloride and cellulose (tri) acetate. Among these, polysulfone polymers such as PSf and PES having repeating units represented by the following formulas [1] and [2] are advantageous and preferable for obtaining a highly water-permeable membrane. The polysulfone polymer referred to here may contain a substituent such as a functional group or an alkyl group, and the hydrogen atom of the hydrocarbon skeleton may be substituted with another atom such as halogen or a substituent. These may be used alone or in combination of two or more.

本発明において、高分子多孔質中空糸膜は、疎水性高分子と親水性高分子を含んでなることが好ましく、親水性高分子としては、例えば、ポリエチレングリコール、ポリビニルアルコール、ポリビニルピロリドン（以下PVPと略記する）、カルボキシメチルセルロース、デンプンなどの高分子炭水化物などが例示される。中でも、ポリスルホンとの相溶性、水性流体処理膜としての使用実績から、PVPが好ましい。これらは単独で使用しても、2種以上を混合して使用してもよい。PVPの分子量としては重量平均分子量10000〜1500000のものが好ましく用いられ得る。具体的には、BASF社より市販されている分子量9000のもの（K17）、以下同様に45000（K30）、450000（K60）、900000（K80）、1200000（K90）を用いるのが好ましい。   In the present invention, the polymer porous hollow fiber membrane preferably comprises a hydrophobic polymer and a hydrophilic polymer. Examples of the hydrophilic polymer include polyethylene glycol, polyvinyl alcohol, polyvinyl pyrrolidone (hereinafter referred to as PVP). Abbreviated to carboxymethylcellulose, starch and other high-molecular-weight carbohydrates. Among these, PVP is preferable from the viewpoint of compatibility with polysulfone and its use as an aqueous fluid treatment membrane. These may be used alone or in combination of two or more. As the molecular weight of PVP, those having a weight average molecular weight of 10,000 to 1,500,000 can be preferably used. Specifically, those having a molecular weight of 9000 (K17) commercially available from BASF, and 45000 (K30), 450,000 (K60), 900000 (K80), and 1200000 (K90) are preferably used in the same manner.

本発明の高分子多孔質中空糸膜の製造方法はなんら限定されるものではなく、疎水性高分子、親水性高分子、溶媒、非溶媒を混合溶解し、脱泡したものを製膜溶液として芯液とともに二重管ノズルの環状部、中心部から同時に吐出し、空走部（エアギャップ部）を経て凝固浴中に導いて中空糸膜を形成し（乾湿式紡糸法）、水洗後巻き取り、乾燥する方法が例示される。   The production method of the polymer porous hollow fiber membrane of the present invention is not limited in any way, and a hydrophobic polymer, a hydrophilic polymer, a solvent, and a non-solvent are mixed and dissolved, and then defoamed as a membrane forming solution. It is discharged from the annular part and center part of the double pipe nozzle together with the core liquid, and is guided to the coagulation bath through the idle running part (air gap part) to form a hollow fiber membrane (dry and wet spinning method). The method of taking and drying is illustrated.

製膜溶液に使用される溶媒は、N−メチル−2−ピロリドン（以下NMPと略記する）、N，N−ジメチルホルムアミド（以下DMFと略記する）、N，N−ジメチルアセトアミド（以下DMAcと略記する）、ジメチルスルホキシド（以下DMSOと略記する）、ε−カプロラクタムなど、使用される疎水性高分子、親水性高分子の良溶媒であれば広く使用することが可能であるが、疎水性高分子としてPSf、PESなどのポリスルホン系高分子を使用する場合には、NMP、DMF、DMAcなどのアミド系アプロティック溶媒が好ましく、NMPが特に好ましい。なお、本発明においてアミド系溶媒とは、構造中にN−C（＝O）のアミド結合を含有する溶媒を意味し、アプロティック溶媒とは、構造中において炭素原子以外のヘテロ原子に直接結合した水素原子を含有していない溶媒を意味する。   Solvents used in the film-forming solution are N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP), N, N-dimethylformamide (hereinafter abbreviated as DMF), N, N-dimethylacetamide (hereinafter abbreviated as DMAc). ), Dimethyl sulfoxide (hereinafter abbreviated as DMSO), ε-caprolactam, etc., can be widely used as long as it is a good solvent for hydrophobic polymers and hydrophilic polymers. When a polysulfone polymer such as PSf or PES is used, an amide aprotic solvent such as NMP, DMF, or DMAc is preferable, and NMP is particularly preferable. In the present invention, the amide solvent means a solvent containing an N—C (═O) amide bond in the structure, and the aprotic solvent is directly bonded to a hetero atom other than a carbon atom in the structure. Means a solvent containing no hydrogen atom.

また、製膜溶液には高分子の非溶媒を添加することも可能である。使用される非溶媒としては、例えば、エチレングリコール、プロピレングリコール、ジエチレングリコール（以下DEGと略記する）、トリエチレングリコール（以下TEGと略記する）、ポリエチレングリコール200、400（以下PEG200、PEG400と略記する）、グリセリン、水などが例示されるが、疎水性高分子としてPSf、PESなどのポリスルホン系高分子、親水性高分子としてPVPを使用する場合には、DEG、TEG、PEG200（400）などのエーテルポリオールが好ましく、TEGが特に好ましい。なお、本発明においてエーテルポリオールとは、構造中に少なくともひとつのエーテル結合と、ふたつ以上の水酸基を有する物質を意味する。   It is also possible to add a polymer non-solvent to the film forming solution. Examples of the non-solvent used include ethylene glycol, propylene glycol, diethylene glycol (hereinafter abbreviated as DEG), triethylene glycol (hereinafter abbreviated as TEG), polyethylene glycol 200 and 400 (hereinafter abbreviated as PEG200 and PEG400). Glycerin, water, etc., but when using a polysulfone polymer such as PSf or PES as a hydrophobic polymer and PVP as a hydrophilic polymer, an ether such as DEG, TEG or PEG200 (400) Polyols are preferred and TEG is particularly preferred. In the present invention, the ether polyol means a substance having at least one ether bond and two or more hydroxyl groups in the structure.

詳細な機構は不明であるが、これらの溶媒、非溶媒を使用して調製した製膜原液を使用することで、紡糸工程における相分離（凝固）が制御され、本発明の好ましい膜構造を形成するのに有利になると考えられる。なお、相分離の制御には、後述の芯液組成や凝固浴中の液（外部凝固液）の組成も重要になる。   Although the detailed mechanism is unknown, phase separation (coagulation) in the spinning process is controlled by using a membrane forming stock solution prepared using these solvents and non-solvents, and the preferred membrane structure of the present invention is formed. It is thought that it becomes advantageous to do. For controlling the phase separation, the composition of the core liquid described later and the composition of the liquid in the coagulation bath (external coagulation liquid) are also important.

製膜原液における疎水性高分子の濃度は、該原液からの製膜が可能であれば特に制限されないが、10〜35重量％が好ましく、10〜30重量％がより好ましい。高い透過性を得るには疎水性高分子の濃度は低いほうが好ましいが、過度に低いと強度の低下や、分画特性の悪化を招く可能性があるので、15重量％以上が好ましい。
親水性高分子の添加量は、中空糸膜に親水性を付与し、水性流体処理時の非特異的吸着を抑制するのに十分な量であれば特に制限されないが、疎水性高分子に対する親水性高分子の比率として10〜30重量％が好ましく、10〜20重量％がより好ましい。親水性高分子の添加量が少なすぎると、膜への親水性付与が不十分となり、膜特性の保持性が低下する可能性がある。また、親水性高分子の添加量が多すぎると、親水性付与効果が飽和してしまい効率がよくなく、また、製膜原液の相分離（凝固）が過度に進行しやすくなり、本発明の好ましい膜構造を形成するのに不利になることがある。 The concentration of the hydrophobic polymer in the film-forming stock solution is not particularly limited as long as film formation from the stock solution is possible, but is preferably 10 to 35% by weight, more preferably 10 to 30% by weight. In order to obtain high permeability, the concentration of the hydrophobic polymer is preferably low. However, if it is too low, the strength may be lowered and the fractionation characteristics may be deteriorated.
The amount of hydrophilic polymer added is not particularly limited as long as it is sufficient to impart hydrophilicity to the hollow fiber membrane and suppress nonspecific adsorption during aqueous fluid treatment. The proportion of the conductive polymer is preferably 10 to 30% by weight, more preferably 10 to 20% by weight. If the amount of the hydrophilic polymer added is too small, the imparting of hydrophilicity to the film may be insufficient, and the retention of film characteristics may be reduced. If the amount of the hydrophilic polymer added is too large, the effect of imparting hydrophilicity is saturated and the efficiency is not good, and the phase separation (coagulation) of the film forming stock solution tends to proceed excessively. It may be disadvantageous to form a preferred membrane structure.

製膜原液中における溶媒／非溶媒の比は、紡糸工程における相分離（凝固）の制御に重要な要因となる。具体的には、溶媒／非溶媒の含有量が重量比で30／70〜70／30であることが好ましく、35／65〜60／40であることがより好ましく、35／65〜55／45であることがさらに好ましい。溶媒の含有量が少なすぎると、凝固が進行しやすくなり、膜構造が緻密化しすぎて透過性が低下することがある。また、溶媒含有量が多すぎると、相分離の進行が過度に抑制され、大孔径の空孔が生じやすくなり、分画特性や強度の低下を招く可能性が高くなる。   The ratio of solvent / non-solvent in the film-forming stock solution is an important factor for controlling phase separation (coagulation) in the spinning process. Specifically, the solvent / non-solvent content is preferably 30/70 to 70/30 by weight, more preferably 35/65 to 60/40, and 35/65 to 55/45. More preferably. When the content of the solvent is too small, solidification tends to proceed, the membrane structure becomes too dense, and the permeability may be lowered. On the other hand, if the solvent content is too large, the progress of phase separation is excessively suppressed, and pores having a large pore diameter are likely to be generated, which increases the possibility of causing a decrease in fractionation characteristics and strength.

製膜原液は、疎水性高分子、親水性高分子、溶媒、非溶媒を混合、攪拌して溶解することで得られる。この際、適宜温度をかけることで効率的に溶解を行うことができるが、過度の加熱は高分子の分解を招く危険があるので、好ましくは30〜100℃、より好ましくは40〜80℃である。また、親水性高分子としてPVPを使用する場合、PVPは空気中の酸素の影響により酸化分解を起こすことから、紡糸溶液の溶解は不活性気体封入下で行うのが好ましい。不活性気体としては、窒素、アルゴンなどが上げられるが、窒素を用いるのが好ましい。このとき、溶解タンク内の残存酸素濃度は3％以下であることが好ましい。窒素封入圧力を高めてやれば溶解時間短縮が望めるが、高圧にするには設備費用が嵩む点と、作業安全性の面から大気圧以上2.0kgf/cm2以下が好ましい。 The film-forming stock solution is obtained by mixing a hydrophobic polymer, a hydrophilic polymer, a solvent, and a non-solvent, and dissolving them by stirring. At this time, the solution can be efficiently dissolved by appropriately applying the temperature, but excessive heating may cause decomposition of the polymer, so it is preferably 30 to 100 ° C, more preferably 40 to 80 ° C. is there. In addition, when PVP is used as the hydrophilic polymer, it is preferable to dissolve the spinning solution in an inert gas enclosure since PVP undergoes oxidative degradation due to the influence of oxygen in the air. Nitrogen, argon, etc. are raised as the inert gas, but nitrogen is preferably used. At this time, the residual oxygen concentration in the dissolution tank is preferably 3% or less. If the nitrogen filling pressure is increased, the melting time can be shortened. However, in order to increase the pressure, the equipment cost increases, and from the viewpoint of work safety, it is preferably from atmospheric pressure to 2.0 kgf / cm 2 .

製膜を行うに際しては、中空糸膜への異物混入による膜構造の欠陥の発生を回避するために、異物を排除した製膜原液を使用することが好ましい。具体的には、異物の少ない原料を用いる、製膜原液を濾過し異物を低減する方法等が有効である。本発明では、中空糸膜の膜厚よりも小さな孔径のフィルターを用いて製膜原液を濾過してからノズルより吐出するのが好ましく、具体的には均一溶解した紡糸溶液を溶解タンクからノズルまで導く間に設けられた孔径10〜50μmの焼結フィルターを通過させる。濾過処理は少なくとも1回行えば良いが、ろ過処理を何段階かにわけて行う場合は後段になるに従いフィルターの孔径を小さくしていくのが濾過効率およびフィルター寿命を延ばす意味で好ましい。フィルターの孔径は10〜45μmがより好ましく、10〜40μmがさらに好ましい。フィルター孔径が小さすぎると背圧が上昇し、生産性が落ちることがある。   When film formation is performed, it is preferable to use a film-forming stock solution from which foreign matters are excluded in order to avoid the occurrence of defects in the membrane structure due to foreign matters mixed into the hollow fiber membrane. Specifically, a method of reducing a foreign material by filtering a film forming stock solution using a raw material with few foreign materials is effective. In the present invention, it is preferable to filter the membrane forming stock solution using a filter having a pore size smaller than the film thickness of the hollow fiber membrane and then discharge from the nozzle. Specifically, the uniformly dissolved spinning solution is discharged from the dissolution tank to the nozzle. It passes through a sintered filter having a pore diameter of 10 to 50 μm provided during the introduction. The filtration process may be performed at least once. However, when the filtration process is performed in several stages, it is preferable to reduce the pore diameter of the filter as it is in the latter stage in order to extend the filtration efficiency and the filter life. The pore size of the filter is more preferably 10 to 45 μm, further preferably 10 to 40 μm. If the filter pore size is too small, the back pressure may increase and productivity may decrease.

また、製膜原液からは予め気泡を排除しておくのが欠陥のない中空糸膜を得るのに有効である。気泡混入を抑える方法としては、製膜原液の脱泡を行うのが有効である。製膜原液の粘度にもよるが、静置脱泡や減圧脱泡を用いることができる。この場合、溶解タンク内を常圧から−100〜−750mmHg減圧した後、タンク内を密閉し30〜180分間静置する。この操作を数回繰り返し脱泡処理を行う。減圧度が低すぎる場合には、脱泡の回数を増やす必要があるため処理に長時間を要することがある。また減圧度が高すぎると、系の密閉度を上げるためのコストが高くなることがある。トータルの処理時間は5分〜5時間とするのが好ましい。処理時間が長すぎると、減圧の影響により製膜原液の構成成分が分解、劣化することがある。処理時間が短すぎると脱泡の効果が不十分になることがある。   In addition, it is effective to obtain a hollow fiber membrane free from defects by eliminating bubbles in advance from the membrane forming stock solution. As a method for suppressing the mixing of bubbles, it is effective to defoam the film forming stock solution. Depending on the viscosity of the film-forming stock solution, stationary defoaming or vacuum defoaming can be used. In this case, after the pressure in the dissolution tank is reduced from normal pressure to −100 to −750 mmHg, the tank is sealed and allowed to stand for 30 to 180 minutes. This operation is repeated several times to perform defoaming treatment. If the degree of vacuum is too low, the treatment may take a long time because it is necessary to increase the number of defoaming times. On the other hand, when the degree of vacuum is too high, the cost for increasing the degree of sealing of the system may increase. The total treatment time is preferably 5 minutes to 5 hours. If the treatment time is too long, the constituent components of the film-forming stock solution may be decomposed and deteriorated due to the effect of reduced pressure. If the treatment time is too short, the defoaming effect may be insufficient.

中空糸膜の製膜時に使用される芯液の組成は、製膜原液に含まれる溶媒および非溶媒と、水との混合液を使用することが好ましい。この際、芯液中に含まれる該溶媒と該非溶媒の比率は、製膜原液の溶媒／非溶媒比率と同一とすることが好ましい。製膜原液に使用されるのと同一の溶媒および非溶媒を、製膜原液中の比率と同一にして混合し、これに水を添加して希釈したものが好ましく用いられる。芯液中の水の含量は、10〜40重量％が好ましく、より好ましくは15〜30重量％である。水の含有量が多すぎると凝固が進行しやすくなり、膜構造が緻密化しすぎて透過性が低下することがある。また、水含有量が少なすぎると相分離の進行が過度に抑制され、大孔径の空孔が生じやすくなり、分画特性や強度の低下を招く可能性がある。   As the composition of the core liquid used at the time of forming the hollow fiber membrane, it is preferable to use a mixed solution of a solvent and a non-solvent contained in the membrane forming stock solution and water. At this time, the ratio of the solvent and the non-solvent contained in the core liquid is preferably the same as the solvent / non-solvent ratio of the film-forming stock solution. Preferably, the same solvent and non-solvent used in the film-forming stock solution are mixed in the same ratio as in the film-forming stock solution and then diluted by adding water. The content of water in the core liquid is preferably 10 to 40% by weight, more preferably 15 to 30% by weight. If the water content is too high, solidification tends to proceed, the membrane structure becomes too dense, and the permeability may decrease. On the other hand, if the water content is too small, the progress of phase separation is excessively suppressed and pores having a large pore diameter are likely to be generated, which may lead to a decrease in fractionation characteristics and strength.

外部凝固液の組成は、製膜原液に含まれる溶媒および非溶媒と、水との混合液を使用することが好ましい。この際、芯液中に含まれる該溶媒と該非溶媒との比率は、製膜原液の溶媒／非溶媒比率と同一であることが好ましい。製膜原液に使用されるのと同一の溶媒および非溶媒を、製膜原液中の比率と同一にして混合し、これに水を添加して希釈したものが好ましく用いられる。外部凝固液中の水の含量は、30〜85重量％が好ましく、より好ましくは40〜80重量％である。水の含有量が多すぎると凝固が進行しやすくなり、膜構造が緻密化しすぎて透過性が低下することがある。また、水含有量が少なすぎると相分離の進行が過度に抑制され、大孔径の空孔が生じやすくなり、分画特性や強度の低下を招く可能性がある。また、外部凝固液の温度は、低すぎると凝固が進行しやすくなり、膜構造が緻密化しすぎて透過性が低下することがある。また、高すぎると相分離の進行が過度に抑制され、大孔径の空孔が生じやすくなり、分画特性や強度の低下を招く可能性があるので、30〜80℃が好ましく、より好ましくは40〜70℃である。   As the composition of the external coagulation liquid, it is preferable to use a mixed liquid of a solvent and a non-solvent contained in the film-forming stock solution and water. At this time, the ratio of the solvent and the non-solvent contained in the core liquid is preferably the same as the solvent / non-solvent ratio of the film-forming stock solution. Preferably, the same solvent and non-solvent used in the film-forming stock solution are mixed in the same ratio as in the film-forming stock solution and then diluted by adding water. The content of water in the external coagulation liquid is preferably 30 to 85% by weight, more preferably 40 to 80% by weight. If the water content is too high, solidification tends to proceed, the membrane structure becomes too dense, and the permeability may decrease. On the other hand, if the water content is too small, the progress of phase separation is excessively suppressed and pores having a large pore diameter are likely to be generated, which may lead to a decrease in fractionation characteristics and strength. On the other hand, if the temperature of the external coagulation liquid is too low, the coagulation tends to proceed, the membrane structure becomes too dense, and the permeability may decrease. In addition, if it is too high, the progress of phase separation is excessively suppressed, and pores with a large pore diameter are likely to be generated, which may lead to a decrease in fractionation characteristics and strength. 40-70 ° C.

本発明において、膜構造を制御する因子のひとつには、ノズルの温度が挙げられる。ノズルの温度は、低すぎると凝固が進行しやすくなり、膜構造が緻密化しすぎて透過性が低下することがある。また、高すぎると相分離の進行が過度に抑制され、大孔径の空孔が生じやすくなり、分画特性や強度の低下を招く可能性があるので、30〜90℃が好ましく、より好ましくは40〜80℃である。   In the present invention, one of the factors controlling the film structure is the temperature of the nozzle. If the temperature of the nozzle is too low, solidification tends to proceed, the membrane structure becomes too dense, and the permeability may decrease. Further, if it is too high, the progress of phase separation is excessively suppressed, and pores having a large pore diameter are likely to be generated, which may lead to a decrease in fractionation characteristics and strength. 40-80 ° C.

本発明の高分子多孔質中空糸膜を得るために好ましい製造方法としては、芯液とともに二重管ノズルから吐出した製膜原液を、エアギャップ部分を経て外部凝固液を満たした凝固浴中に導いて中空糸膜を形成する乾湿式紡糸法が例示されるが、ノズルから吐出された製膜原液の、エアギャップ部分での滞留時間が膜構造を制御する因子のひとつとなり得る。滞留時間が短すぎると、エアギャップ部分での相分離による凝集粒子の成長が抑制された状態で外部凝固液によりクエンチされるので、外表面構造が緻密になりすぎて透過性が低下することがある。また、外表面が緻密になりすぎると、得られた中空糸膜が固着しやすい傾向がある。滞留時間が長すぎると、大孔径の空孔が生じやすくなり、分画特性や強度の低下を招く可能性がある。エアギャップにおける滞留時間の好ましい範囲は0.05〜4秒であり、0.1〜3秒がより好ましい。   As a preferred production method for obtaining the polymer porous hollow fiber membrane of the present invention, the membrane forming stock solution discharged from the double tube nozzle together with the core solution is placed in a coagulation bath filled with an external coagulation solution through an air gap portion. The dry and wet spinning method in which the hollow fiber membrane is formed by guiding is exemplified, but the residence time in the air gap portion of the membrane forming stock solution discharged from the nozzle can be one of the factors controlling the membrane structure. If the residence time is too short, it is quenched by the external coagulation liquid in a state where the growth of aggregated particles due to phase separation in the air gap portion is suppressed, so that the outer surface structure becomes too dense and the permeability may decrease. is there. Moreover, when the outer surface becomes too dense, the obtained hollow fiber membrane tends to be fixed. When the residence time is too long, pores having a large pore diameter are likely to be generated, and there is a possibility that the fractionation characteristics and the strength are reduced. A preferable range of the residence time in the air gap is 0.05 to 4 seconds, and more preferably 0.1 to 3 seconds.

上記、比較的滞留時間の短いエアギャップ部分を経て、凝固浴に導かれた中空糸膜は、芯液からの凝固が進行しながら、外部からの凝固はある程度抑制された状態で、比較的凝固性のマイルドな外部凝固液と接触する。すなわち、凝固浴内に突入した直後の中空糸膜は未だ完全に構造が決定しない「生きた」状態にあるが、この「生きた」中空糸膜が凝固浴内で完全に凝固し、構造が決定されて引き上げられる。前述のとおり、外部凝固液の凝固性は比較的マイルドであるので、凝固浴内での滞留時間は完全に凝固が完了するまで十分にとる必要がある。具体的には、5〜20秒が好ましく、10〜20秒がより好ましい。凝固浴内での滞留時間が短すぎると凝固が不十分となる可能性があり、長すぎると製膜速度の低下や凝固浴の大型化が必要となることがある。   The hollow fiber membrane guided to the coagulation bath through the air gap portion having a relatively short residence time is relatively coagulated in a state in which coagulation from the core liquid proceeds while coagulation from the outside is suppressed to some extent. Contact with a mild external clotting solution. That is, the hollow fiber membrane immediately after entering the coagulation bath is in a “live” state in which the structure is not yet completely determined, but this “live” hollow fiber membrane is completely solidified in the coagulation bath, and the structure is Determined and raised. As described above, since the coagulability of the external coagulation liquid is relatively mild, the residence time in the coagulation bath needs to be sufficient until the coagulation is completely completed. Specifically, 5 to 20 seconds is preferable, and 10 to 20 seconds is more preferable. If the residence time in the coagulation bath is too short, coagulation may be insufficient, and if it is too long, the film-forming speed may be reduced or the coagulation bath may need to be enlarged.

本発明の高分子多孔質膜は、内表面および外表面に緻密層を有し、内表面における孔径が外表面における孔径よりも小さく、内表面から外表面に向かって当初空孔率が増大し、少なくともひとつの極大部を通過後、再び外表面側で空孔率が減少する構造を持つのが大きな特徴であるが、このような構造を実現するには、上記の製膜原液を使用し、上記の紡糸条件によって中空糸膜を得る方法を採るのが好適である。内表面から外表面に向かって密−疎−密の非対称構造を構成させるには、中空糸膜の内側からの凝固（主として芯液による相分離・凝固）と外側からの凝固（主としてエアギャップ、外部凝固液での相分離・凝固）のバランスをとり、両者を拮抗させることで内外両表面から膜壁内部に向かっての凝固を制御しなければならない。そのための有効な制御手段が、上記芯液の組成、外部凝固液の組成・温度、エアギャップ部分での滞留時間、凝固浴内での滞留時間である。これらを上記の範囲に設定することによって、本発明の特徴的な膜構造を得ることができる。   The porous polymer membrane of the present invention has a dense layer on the inner surface and the outer surface, the pore diameter on the inner surface is smaller than the pore diameter on the outer surface, and the initial porosity increases from the inner surface toward the outer surface. The main feature is that after passing through at least one local maximum, the porosity decreases again on the outer surface side, but in order to realize such a structure, the above film forming stock solution is used. It is preferable to adopt a method for obtaining a hollow fiber membrane under the above spinning conditions. To form a dense-sparse-dense asymmetric structure from the inner surface to the outer surface, solidification from the inside of the hollow fiber membrane (mainly phase separation / coagulation by the core liquid) and solidification from the outside (mainly the air gap, It is necessary to control the coagulation from the inner and outer surfaces toward the inside of the membrane wall by balancing the phases and coagulating them. Effective control means for that purpose are the composition of the core liquid, the composition / temperature of the external coagulation liquid, the residence time in the air gap portion, and the residence time in the coagulation bath. By setting these within the above range, the characteristic film structure of the present invention can be obtained.

本発明の高分子多孔質中空糸膜を得るには、内外両表面からの凝固進行を微妙に制御する必要があるが、その際に注意しなければならない点として、中空糸膜の凝固浴中における屈曲がある。乾湿式紡糸においては、通常、下向きに配列したノズルから製膜原液を重力方向に吐出、エアギャップ部分を経て凝固浴に導き、凝固浴内で進行方向を上向きに変更して凝固浴から引き上げ、水洗浴での洗浄を経て巻き取るのが一般的である。本発明の高分子多孔質中空糸膜は、凝固浴内突入直後には完全に構造が決定しない「生きた」状態にあるので、凝固浴内での方向転換が急激に行われると、膜構造の欠陥や破壊を招く可能性がある。具体的には、方向転換時の曲率半径が20〜300mm、より好ましくは30〜200mm、さらに好ましくは40〜100mm、さらにより好ましくは40〜70mmである。また、多点ガイドを使用し、複数のポイントで徐々に方向を転換する方法も好ましい。   In order to obtain the polymer porous hollow fiber membrane of the present invention, it is necessary to delicately control the progress of solidification from both the inner and outer surfaces. There is a bend. In dry-wet spinning, the film-forming stock solution is usually discharged from the nozzles arranged downward in the direction of gravity, led to the coagulation bath through the air gap part, the direction of travel is changed upward in the coagulation bath, and pulled up from the coagulation bath. It is common to wind up after washing in a water bath. Since the polymer porous hollow fiber membrane of the present invention is in a “live” state in which the structure is not completely determined immediately after entering the coagulation bath, the membrane structure is changed when the direction is rapidly changed in the coagulation bath. May lead to defects or destruction. Specifically, the radius of curvature at the time of turning is 20 to 300 mm, more preferably 30 to 200 mm, still more preferably 40 to 100 mm, and even more preferably 40 to 70 mm. Also preferred is a method of gradually changing direction at a plurality of points using a multipoint guide.

本発明の高分子多孔質中空糸膜の製造において、完全に中空糸膜構造が固定される以前に実質的に延伸をかけないことが好ましい。実質的に延伸を掛けないとは、ノズルから吐出された製膜原液に弛みや過度の緊張が生じないように、紡糸工程中のローラー速度をコントロールすることを意味する。吐出線速度／凝固浴第一ローラー速度比（ドラフト比）は0.7〜1.8が好ましい範囲である。前記比が0.7未満では、走行する中空糸膜に弛みが生じ生産性の低下につながることがあるので、ドラフト比は0.8以上がより好ましく、0.9以上がさらに好ましく、0.95以上がさらにより好ましい。1.8を超える場合には中空糸膜の緻密層が裂けるなど膜構造が破壊されることがある。そのため、ドラフト比は、より好ましくは1.7以下、さらに好ましくは1.6以下、さらにより好ましくは1.5以下、特に好ましくは1.4以下である。ドラフト比をこの範囲に調整することにより細孔の変形や破壊を防ぐことができ、膜性能の保持性やシャープな分画特性を発現することが可能となる。   In the production of the polymer porous hollow fiber membrane of the present invention, it is preferable that stretching is not substantially applied before the hollow fiber membrane structure is completely fixed. The fact that the film is not substantially stretched means that the roller speed during the spinning process is controlled so that the film-forming stock solution discharged from the nozzle is not loosened or excessively tensioned. The discharge linear speed / coagulation bath first roller speed ratio (draft ratio) is preferably in the range of 0.7 to 1.8. When the ratio is less than 0.7, the traveling hollow fiber membrane may be loosened, leading to a decrease in productivity. Therefore, the draft ratio is more preferably 0.8 or more, further preferably 0.9 or more, and even more preferably 0.95 or more. If it exceeds 1.8, the membrane structure may be destroyed, for example, the dense layer of the hollow fiber membrane is torn. Therefore, the draft ratio is more preferably 1.7 or less, still more preferably 1.6 or less, even more preferably 1.5 or less, and particularly preferably 1.4 or less. By adjusting the draft ratio within this range, it is possible to prevent the deformation and destruction of the pores, and to maintain the membrane performance and to exhibit sharp fractionation characteristics.

製膜速度（紡速）については、欠陥のない中空糸膜が得られ、生産性が確保できれば特に制限されないが、好ましくは、5〜40m/min、より好ましくは7〜30m/min、さらに好ましくは7〜20m/minである。紡速が低すぎると、生産性が低下することがある。紡速が高すぎると、上記の紡糸条件、特にエアギャップ部分での滞留時間や、凝固浴内での滞留時間を確保するのが困難となる可能性がある。   The film-forming speed (spinning speed) is not particularly limited as long as a hollow fiber membrane having no defect can be obtained and productivity can be ensured, but is preferably 5 to 40 m / min, more preferably 7 to 30 m / min, still more preferably Is 7-20 m / min. If the spinning speed is too low, the productivity may decrease. If the spinning speed is too high, it may be difficult to ensure the above spinning conditions, particularly the residence time in the air gap portion and the residence time in the coagulation bath.

中空糸膜は製膜後、洗浄工程を経て過剰の溶媒、非溶媒を除去する。中空糸膜の洗浄方法は特に制限されないが、洗浄効果、安全性、簡便性から、温水を満たした洗浄浴内に製膜された中空糸膜をそのままオンラインで走行させ、しかる後に巻き取るのが好ましい。この際使用される温水の温度は、20〜100℃が好ましく、30〜90℃がより好ましい。温度が低すぎると洗浄効果が不十分になり、温度が高すぎると洗浄液として水が使用できない。   After forming the hollow fiber membrane, excess solvent and non-solvent are removed through a washing step. The method for cleaning the hollow fiber membrane is not particularly limited, but from the viewpoint of cleaning effect, safety, and simplicity, the hollow fiber membrane formed in the cleaning bath filled with warm water can be run online as it is, and then wound up. preferable. The temperature of the hot water used at this time is preferably 20 to 100 ° C, more preferably 30 to 90 ° C. If the temperature is too low, the cleaning effect is insufficient, and if the temperature is too high, water cannot be used as the cleaning liquid.

製膜後、洗浄を経て得られた高分子多孔質中空糸膜は、使用中や洗浄操作による膜特性の変化を抑制し、膜特性の保持性・安定性、膜特性の回復性を確保する目的で、加熱処理を施すのが好ましい。この加熱処理を熱水への浸漬処理とすることで、同時に、中空糸膜に残存する溶媒や非溶媒などを洗浄・除去する効果も期待できる。   The polymer porous hollow fiber membrane obtained after film formation and washing suppresses changes in membrane properties during use and washing operations, and ensures membrane property retention / stability and membrane property recovery. For the purpose, heat treatment is preferably performed. By making this heat treatment an immersion treatment in hot water, the effect of washing and removing the solvent, non-solvent, etc. remaining in the hollow fiber membrane can be expected at the same time.

本発明の高分子多孔質中空糸膜を得るには、この熱水中への浸漬処理に先立ち、溶媒／非溶媒の水溶液と中空糸膜とを接触させた状態で、しばらくエージングするのが好ましい。このエージングを施すことによって、膜中の親水性高分子の含量、存在状態が最適化される。この工程における溶媒／非溶媒の水溶液の濃度は、有機成分濃度として20〜70重量％、温度は20〜40℃、時間は0.1〜10minが好ましい。   In order to obtain the polymer porous hollow fiber membrane of the present invention, it is preferable to perform aging for a while in a state where the solvent / non-solvent aqueous solution and the hollow fiber membrane are in contact with each other prior to the immersion treatment in hot water. . By applying this aging, the content and existence state of the hydrophilic polymer in the film are optimized. The concentration of the solvent / non-solvent aqueous solution in this step is preferably 20 to 70% by weight as the organic component concentration, the temperature is 20 to 40 ° C., and the time is 0.1 to 10 min.

上記エージングを実施するには、完全に有機成分を除去した中空糸膜を再度溶媒／非溶媒の水溶液に浸漬してもよいが、紡糸後のオンラインでの洗浄条件を調整することで、芯液中の有機成分濃度を上記の好ましい範囲とし、そのまま上記好ましい温度、時間でエージングするのが簡便である。具体的には、
Ｓ ＝ 中空糸膜の内半径の2乗［mm2］×芯液の有機成分濃度［％］÷100
Ｈ ＝ 水洗浴中での中空糸膜の滞留時間［min］×水洗浴の水温［Ｋ］
（水洗浴が複数個ある場合は、それぞれについて上記Ｈを算出し、その合計をもってＨとする。）
で規定されるＳ、Ｈの値が、下記を満足する条件で水洗を実施するのがよい。
Ｈ／Ｓ ＝ 500〜50000
ただし、水洗浴中の有機成分濃度は、常に上記有機成分濃度の1／10以下となるよう適宜液更新を実施するのが好ましい。 In order to perform the above aging, the hollow fiber membrane from which the organic components have been completely removed may be immersed again in a solvent / non-solvent aqueous solution. However, by adjusting the on-line washing conditions after spinning, the core solution It is convenient to set the concentration of the organic component in the above preferable range and perform aging as it is at the above preferable temperature and time. In particular,
S = square of inner radius of hollow fiber membrane [mm 2 ] x organic component concentration of core liquid [%] ÷ 100
H = residence time of the hollow fiber membrane in the washing bath [min] x water temperature of the washing bath [K]
(When there are a plurality of washing baths, the above H is calculated for each, and the sum is taken as H.)
It is preferable to carry out the water washing under the condition that the values of S and H defined by the following conditions are satisfied.
H / S = 500-50000
However, it is preferable to renew the liquid appropriately so that the concentration of the organic component in the washing bath is always 1/10 or less of the concentration of the organic component.

上記エージングを経た中空糸膜の加熱処理に使用される熱水の温度は、60〜100℃が好ましく、より好ましくは70〜90℃、処理時間は30〜120min、より好ましくは40〜90min、さらに好ましくは50〜80minである。温度がこれよりも低く、処理時間がこれよりも短いと中空糸膜にかかる熱履歴が不十分となり、膜特性の保持性・安定性が低下する可能性があり、また、洗浄効果が不十分となり溶出物が増加する可能性が高くなる。温度がこれよりも高く、処理時間がこれよりも長いと、水が沸騰したり、処理に長時間を要し生産性が低下することがある。熱水に対する中空糸膜の浴比は、中空糸膜が十分に浸る量の熱水を使用すれば、特に制限されないが、あまり多量の熱水を使用するのは、生産性が低下する可能性がある。   The temperature of the hot water used for the heat treatment of the hollow fiber membrane subjected to the aging is preferably 60 to 100 ° C, more preferably 70 to 90 ° C, the treatment time is 30 to 120 minutes, more preferably 40 to 90 minutes, Preferably it is 50-80min. If the temperature is lower than this and the processing time is shorter than this, the heat history applied to the hollow fiber membrane may be insufficient, and the retention and stability of the membrane characteristics may be lowered, and the cleaning effect is insufficient. Therefore, there is a high possibility that the amount of eluate increases. If the temperature is higher than this and the treatment time is longer than this, water may boil or the treatment may take a long time and productivity may be reduced. The bath ratio of the hollow fiber membrane to hot water is not particularly limited as long as the hollow fiber membrane is sufficiently immersed in the hot water, but using too much hot water may reduce productivity. There is.

製膜、加熱処理を完了した中空糸膜は、乾燥することによって、最終的に完成する。乾燥方法は、風乾、減圧乾燥、熱風乾燥など通常利用される乾燥方法が広く利用できる。最近、血液処理膜の乾燥などで利用されているマイクロ波乾燥なども利用可能であるが、簡便な装置で効率的に大量の中空糸膜を乾燥できる点で、熱風乾燥が好ましく利用され得る。乾燥に先立って、上記の加熱処理を施しておくことで、熱風乾燥による膜特性の変化も抑制することができる。熱風乾燥時の熱風温度は特に制限されないが、好ましくは40〜100℃、より好ましくは50〜80℃である。これよりも温度が低いと乾燥までに長時間を要し、これよりも温度が高いと熱風生成のためのエネルギーコストが高くなることがある。熱風の温度は、上記の熱水加熱処理を超えると膜の劣化を促進してしまい、特性の低下を招く可能性があるので、熱水加熱処理の温度よりも低いことが好ましい。   The hollow fiber membrane that has been subjected to film formation and heat treatment is finally completed by drying. As a drying method, commonly used drying methods such as air drying, reduced pressure drying, and hot air drying can be widely used. Recently, microwave drying, which has been used for drying blood treatment membranes, can be used. However, hot air drying can be preferably used in that a large amount of hollow fiber membranes can be efficiently dried with a simple apparatus. By performing the above heat treatment prior to drying, changes in film properties due to hot air drying can also be suppressed. The hot air temperature during hot air drying is not particularly limited, but is preferably 40 to 100 ° C, more preferably 50 to 80 ° C. If the temperature is lower than this, it takes a long time to dry, and if the temperature is higher than this, the energy cost for generating hot air may be increased. If the temperature of the hot air exceeds the hot water heat treatment described above, the deterioration of the film is promoted and there is a possibility that the characteristics will be lowered. Therefore, the temperature of the hot air is preferably lower than the temperature of the hot water heat treatment.

製膜後の中空糸膜は、巻き上げ機によって巻き取られるが、先述のとおり、この際の条件・態様が本発明の中空糸膜の外圧耐性に大きな影響をも与えることを見出し、巻き取り条件・態様に工夫をすることで本発明を完成した。   The hollow fiber membrane after film formation is wound up by a winder, and as described above, the conditions and aspects at this time also have a great influence on the external pressure resistance of the hollow fiber membrane of the present invention, and the winding conditions -The present invention was completed by devising aspects.

中空糸膜の製造において、製膜工程中は単糸で走行させることもあるが、巻き取り時には複数の中空糸膜を合糸して巻き上げられることが多い。特に、外径の大きな中空糸膜では、まとめる本数が多くなるほど、巻き取り時に中空糸膜に捩れが生じやすくなり、加えて巻取り時に受けるテンションの影響によって局部的なストレスを受けやすくなるため、注意が必要である。   In the production of a hollow fiber membrane, the yarn may be run with a single yarn during the membrane formation process, but at the time of winding, a plurality of hollow fiber membranes are often combined and wound up. In particular, in the hollow fiber membrane having a large outer diameter, as the number of bundles increases, the hollow fiber membrane tends to be twisted at the time of winding, and in addition, it is likely to be subjected to local stress due to the influence of the tension received at the time of winding, Caution must be taken.

巻き取り時のテンションは可能な限り低く設定した上で、合糸本数を少なくすることが好ましい。しかし、巻き取り時のテンションを低くしすぎると、中空糸膜に弛みが生じやすくなり整然と巻き取ることができないことがある。テンションについては、巻き取る中空糸膜の径や糸質、巻き取り速度、合糸本数などによって都度設定する必要があり、巻き取り性に不具合が生じない程度に低く設定することが好ましい。   It is preferable that the tension at the time of winding is set as low as possible and the number of combined yarns is reduced. However, if the tension at the time of winding is too low, the hollow fiber membrane is liable to be loosened and cannot be wound up in an orderly manner. The tension needs to be set each time depending on the diameter of the hollow fiber membrane to be wound, the yarn quality, the winding speed, the number of combined yarns, and the like, and is preferably set to a low value that does not cause a problem in winding.

また、合糸本数については、単糸で巻き取るのが理想だが、そうすると単糸当たりにかかるテンションが大きくなるため中空糸膜にダメージを与える可能性がある。合糸した状態でも径があまり大きくならない場合には複数本まとめてもよい。こちらも中空糸膜の強伸度等によって、外圧耐性に弊害のない合糸本数は変わってくるため試行錯誤により最適値を設定する必要があり、経験的には合糸した状態での全体径が5mm以下であることが好ましい。   As for the number of combined yarns, it is ideal to wind up with a single yarn. However, if this is done, the tension applied to each single yarn increases, which may damage the hollow fiber membrane. If the diameter does not become too large even in the combined state, a plurality of yarns may be collected. Here too, the number of combined yarns that do not adversely affect the external pressure resistance changes depending on the strength of the hollow fiber membrane, etc., so it is necessary to set an optimum value by trial and error, and empirically the overall diameter in the combined state Is preferably 5 mm or less.

また、巻上げ前から巻き上げに至るまでの中空糸膜の走行状態については、走行中に不必要な捩れが生じないよう、極力直線的な糸道とすることが好ましい。したがって、同時に複数本の中空糸膜を巻き上げる場合には、先述の好ましい合糸本数も加味し、紡糸走行中から巻き取りまで、複数の中空糸膜を完全に平行に走行せしめるのが最も好ましい実施態様である。   The traveling state of the hollow fiber membrane from before winding to winding is preferably a straight yarn path as much as possible so that unnecessary twisting does not occur during traveling. Therefore, when simultaneously winding a plurality of hollow fiber membranes, it is most preferable to allow the plurality of hollow fiber membranes to run completely in parallel from spinning to winding, taking into account the preferred number of combined yarns described above. It is an aspect.

また、巻き上げ機には、ダンサローラーと呼ばれる小型のローラーが備えられている。巻き取り中の中空糸膜にかかるテンションが一定に保たれるように工夫しており、中空糸膜はこのローラーを通って進路を変更して走行し巻き上げ機に至る。したがって、このダンサローラーもあまりに径が小さすぎると、中空糸膜が走行中に大きく屈曲することになりダメージを与えることがある。逆に径を大きくしすぎると、ローラーが重くなることにより、結果として巻き取り時のテンションが増大してしまうため、巻き取られた中空糸膜にストレスを与える可能性がある。よって、ダンサローラーは軽量性と入手のしやすさ、加工性などからアルミニウム製とするのが好ましく、ローラー径は30〜100mmφとするのが好ましい。   The hoisting machine is provided with a small roller called a dancer roller. It is devised so that the tension applied to the hollow fiber membrane being wound is kept constant, and the hollow fiber membrane travels through this roller while changing the course to reach the winding machine. Therefore, if the diameter of the dancer roller is too small, the hollow fiber membrane may be bent greatly during travel, which may cause damage. On the other hand, if the diameter is too large, the roller becomes heavier and, as a result, the tension at the time of winding is increased, so that the wound hollow fiber membrane may be stressed. Therefore, the dancer roller is preferably made of aluminum from the viewpoint of lightness, availability, and workability, and the roller diameter is preferably 30 to 100 mmφ.

巻き取られた中空糸膜は、巻き取りが進むにつれ捲き太りにより捲き束として径が大きくなっていくが、捲き径が大きくなりすぎると、中空糸膜が捩れたり中空糸膜同士の不規則な重なりが生じたりする可能性が高くなるため、中空糸膜に局部的なストレスがかかることになる。したがって、捲き厚みとしては50mm以下となるように巻き取ることが好ましい。   As the winding progresses, the wound hollow fiber membrane increases in diameter as a wound bundle due to the thickening, but if the winding diameter becomes too large, the hollow fiber membrane is twisted or the hollow fiber membranes are irregular. Since there is a high possibility that overlap will occur, local stress is applied to the hollow fiber membrane. Therefore, it is preferable to wind up the winding thickness to be 50 mm or less.

本願発明においては、上記したような中空糸膜巻き取り時の条件・態様に配慮をしているので、中空糸膜に与えるダメージを極力排除することが可能となり、したがって、該中空糸膜を用いて作製された中空糸膜モジュールは逆洗等による中空糸膜潰れや折れなどの発生を効果的に抑制することが可能となっている。   In the present invention, since consideration is given to the conditions and modes at the time of winding the hollow fiber membrane as described above, it is possible to eliminate damage to the hollow fiber membrane as much as possible, and therefore the hollow fiber membrane is used. The hollow fiber membrane module produced in this way can effectively suppress the occurrence of hollow fiber membrane crushing or breaking due to backwashing or the like.

以下、実施例にて本発明の好ましい実施態様を説明する。ただし、本発明はこれらに限定されるものではない。   Hereinafter, preferred embodiments of the present invention will be described with reference to Examples. However, the present invention is not limited to these.

（中空糸膜の電子顕微鏡による構造観察・解析）
乾燥した中空糸膜を切断し、内表面、外表面、断面の走査型電子顕微鏡（SEM）写真を、倍率10000倍または2000倍で撮影した。SEM写真を466dpiの解像度でコンピュータに取り込み、画像解析ソフトを使用して解析を行い、空孔率と平均細孔面積、細孔分布を求めた。具体的には、まず、取り込んだ画像を二値化処理し、空孔部が黒、構成ポリマー部分が白となった画像を得た。この画像を解析することにより、空孔部分の個数、各空孔部分の面積、空孔部分の面積の総和を得た。読み込んだ画像の総面積と、空孔項部分の面積の総和から、次式［１］により空孔率を算出した。
空孔率［％］＝100×（空孔部分の面積の総和／読み込んだ画像の総面積） ［１］
空孔部分の面積の総和と、空孔部分の個数から平均空孔面積を算出し、さらに空孔の形状を円と近似して、平均空孔面積から平均孔径を算出した。（次式［２］および［３］）
空孔の面積（平均空孔面積）［μm2］＝空孔部分の面積の総和／空孔部分の個数 ［２］
孔径（平均孔径）［μm］＝（平均空孔面積／π）1／2 ［３］
さらに、各空孔部分の面積から上記同様、空孔の形状を円と近似した場合の孔径を算出し、その結果を表計算ソフトに取り込んでヒストグラムを作成して、細孔分布としてまとめた。 (Structural observation and analysis of hollow fiber membranes by electron microscope)
The dried hollow fiber membrane was cut, and scanning electron microscope (SEM) photographs of the inner surface, outer surface, and cross section were taken at a magnification of 10,000 or 2000 times. SEM photographs were imported into a computer at a resolution of 466 dpi and analyzed using image analysis software to determine the porosity, average pore area, and pore distribution. Specifically, first, the captured image was binarized to obtain an image in which the hole portion was black and the constituent polymer portion was white. By analyzing this image, the total number of holes, the area of each hole, and the area of the holes was obtained. From the total area of the read image and the total area of the pore term portion, the porosity was calculated by the following equation [1].
Porosity [%] = 100 x (total area of holes / total area of scanned image) [1]
The average hole area was calculated from the total area of the hole portions and the number of the hole portions, and the shape of the holes was approximated to a circle, and the average hole diameter was calculated from the average hole area. (Formulas [2] and [3])
Hole area (average hole area) [μm 2 ] = total area of holes / number of holes [2]
Pore diameter (average pore diameter) [μm] = (average pore area / π) 1/2 [3]
Further, as described above, the hole diameter when the hole shape was approximated to a circle was calculated from the area of each hole portion, and the result was taken into spreadsheet software to create a histogram and summarize it as a pore distribution.

（中空糸膜の内径、膜厚の測定方法）
中空糸膜断面のサンプルは以下のようにして得ることができる。測定には芯液を洗浄、除去した後、中空糸膜を乾燥させた形態で観察することが好ましい。乾燥方法は問わないが、乾燥により著しく形態が変化する場合には中空形成材を洗浄、除去したのち、純水で完全に置換した後、湿潤状態で形態を観察することが好ましい。中空糸膜の内径（ID）、外径（OD）および膜厚（Δd）は、中空糸膜をスライドグラスの中央に開けられた穴に中空糸膜が抜け落ちない程度に適当本数通し、スライドグラスの上下面でカミソリによりカットし、中空糸膜断面サンプルを得た後、投影機Nikon-12Aを用いて中空糸膜断面の短径、長径を測定することにより得られる。中空糸膜断面1個につき2方向の短径、長径を測定し、それぞれの算術平均値を中空糸膜断面1個の内径および外径とし、膜厚は（外径−内径）／2で算出した。5断面について同様に測定を行い、平均値を内径、膜厚とした。 (Measurement method of hollow fiber membrane inner diameter and film thickness)
A sample of the cross section of the hollow fiber membrane can be obtained as follows. For the measurement, it is preferable to observe in a form in which the hollow fiber membrane is dried after washing and removing the core liquid. There is no limitation on the drying method. However, when the shape changes remarkably by drying, it is preferable to clean and remove the hollow forming material and then completely replace with pure water, and then observe the shape in a wet state. The inner diameter (ID), outer diameter (OD), and film thickness (Δd) of the hollow fiber membrane are appropriately adjusted so that the hollow fiber membrane does not fall out into the hole formed in the center of the slide glass. It is obtained by measuring the minor axis and major axis of the hollow fiber membrane cross section using a projector Nikon-12A after cutting with a razor on the upper and lower surfaces of the sample to obtain a hollow fiber membrane cross section sample. Measure the short axis and long axis in two directions for each cross section of hollow fiber membrane, and calculate the arithmetic average value of each as the inner diameter and outer diameter of one hollow fiber membrane cross section. The film thickness is calculated as (outer diameter-inner diameter) / 2. did. The same measurement was performed on five cross sections, and the average value was defined as the inner diameter and film thickness.

（中空糸膜の偏肉度の測定方法）
中空糸膜の偏肉度とは中空糸膜断面における中空糸膜厚の最薄部/最厚部の比のことであり、例えば膜厚が全部分で同じであれば偏肉度は１である。中空糸膜の内径、膜厚測定と同様に中空糸膜断面サンプルを得た後、投影機Nikon-12Aを用いて中空糸膜断面1つにつき膜厚の最薄部と最厚部を測定し、（最薄部膜厚）／（最厚部膜厚）を偏肉度とした。 (Measurement method of thickness deviation of hollow fiber membrane)
The thickness deviation of the hollow fiber membrane is the ratio of the thinnest part / thickest part of the hollow fiber film thickness in the cross section of the hollow fiber film. For example, if the film thickness is the same in all parts, the thickness deviation is 1 is there. After obtaining the hollow fiber membrane cross-section sample in the same way as measuring the inner diameter and film thickness of the hollow fiber membrane, the thinnest part and the thickest part of the film thickness are measured for each hollow fiber membrane cross section using the projector Nikon-12A. , (Thinnest film thickness) / (thickest film thickness) was defined as the thickness deviation.

（中空糸膜の真円度の測定方法）
中空糸膜の偏平度合いを評価するために、中空糸膜の真円度を測定した。真円度とは中空糸膜断面における中空糸内径の短軸/長軸比のことであり、例えば真円であれば真円度は1である。画像解析ソフト「Image-Pro Plus」（Media Cybernetics社）によって、ミニモジュール端面中任意の100個の中空糸膜断面に関して測定を実施し、その平均値を求めた。 (Measurement method of roundness of hollow fiber membrane)
In order to evaluate the flatness of the hollow fiber membrane, the roundness of the hollow fiber membrane was measured. Roundness is the ratio of the minor axis / major axis of the inner diameter of the hollow fiber in the cross section of the hollow fiber membrane. For example, the circularity is 1 for a perfect circle. Using an image analysis software “Image-Pro Plus” (Media Cybernetics), measurement was performed on any 100 hollow fiber membrane cross sections in the end face of the mini-module, and the average value was obtained.

（中空糸膜に生じる潰れの個数の測定方法）
まず、50〜200cmの中空糸膜を70〜300本束ね、接着により片側端部のみ開口させたモジュールを作製した。圧力容器内にモジュールを収納し、開口端をチューブに接続してチューブ反対側が圧力容器外に出るようにセットした。その際、作製したモジュールが傷つかないよう注意してセットする。圧力容器内に水を満たした後、容器を密閉して容器内を0.4MPaにて加圧した。チューブより容器内の水が放出された後、30分間0.4MPaをキープし、その後モジュールを容器より取り出し、中空糸膜に生じた潰れの個数を全中空糸膜についてもれなく計測した。その後、中空糸膜の本数と有効長から中空糸膜1kmあたりの潰れの個数を算出した。なお、作製するモジュールの中空糸膜の本数・長さについては、使用する圧力容器の大きさにより適宜設定し、かつ測定精度の観点から（中空糸膜の本数）×（有効長）の値が100mを超えるように決め、モジュール5本以上について測定する。 (Measuring method of the number of crushing in the hollow fiber membrane)
First, a module in which 70 to 300 hollow fiber membranes of 50 to 200 cm were bundled and only one end portion was opened by adhesion was produced. The module was housed in a pressure vessel, and the open end was connected to a tube and set so that the opposite side of the tube would come out of the pressure vessel. At that time, set the module carefully so as not to damage it. After filling the pressure vessel with water, the vessel was sealed and the inside of the vessel was pressurized at 0.4 MPa. After the water in the container was released from the tube, 0.4 MPa was kept for 30 minutes, and then the module was taken out from the container, and the number of collapses generated in the hollow fiber membranes was measured for all the hollow fiber membranes. Thereafter, the number of collapses per 1 km of the hollow fiber membrane was calculated from the number of hollow fiber membranes and the effective length. The number and the length of the hollow fiber membranes of the module to be produced are appropriately set according to the size of the pressure vessel to be used, and the value of (the number of hollow fiber membranes) × (effective length) from the viewpoint of measurement accuracy is Determine to exceed 100m and measure more than 5 modules.

（中空糸膜の透水性の測定方法）
中空糸膜を3〜100本充填し、接着により両端部を開口させた、有効長10〜30cmの中空糸膜ミニモジュールを作製する。中空糸膜ミニモジュールは、有効膜面積（A）が0.002〜0.02［m2］になるよう、中空糸膜本数と長さを決めて作製する。なお、中空糸膜の有効膜面積（A）は、中空糸内径（ID）基準とし、接着部分を除いた有効長（L）から有効膜面積を計算する。予め純水を中空糸膜内部（中空部）、中空糸膜外部（モジュール内）の順に通水し、空気を除去する。中空糸膜内部（中空部）に通じるモジュール出口を封止し、モジュール入口から22℃の純水によって0.5〜2.0barの所定圧力をかけて、入口圧力（Pin）と出口（封止）部圧力（Pout）を測定しつつ、1分間に膜を通して膜外側に出てくる純水の量（Ｗ）を測定した。次に下記式により中空糸膜の透水性［L/hr/m2/bar］を計算した。
（透水性）＝Ｗ［L/min］×60［min/hr］／Ａ［m2］／（（Pin［bar］+Pout［bar］）／2）
ここで、Ａ［m2］＝ID［m］×π×Ｌ［m］×中空糸膜本数 (Measurement method of water permeability of hollow fiber membrane)
A hollow fiber membrane mini-module having an effective length of 10 to 30 cm is prepared by filling 3 to 100 hollow fiber membranes and opening both ends by adhesion. The hollow fiber membrane mini-module is manufactured by determining the number and length of the hollow fiber membranes so that the effective membrane area (A) is 0.002 to 0.02 [m 2 ]. The effective membrane area (A) of the hollow fiber membrane is based on the hollow fiber inner diameter (ID), and the effective membrane area is calculated from the effective length (L) excluding the bonded portion. Pure water is passed through the hollow fiber membrane (hollow part) and the hollow fiber membrane outside (inside the module) in advance in this order to remove air. Seal the module outlet leading to the inside (hollow part) of the hollow fiber membrane, apply a predetermined pressure of 0.5 to 2.0 bar with pure water at 22 ° C from the module inlet, inlet pressure (Pin) and outlet (sealing) part pressure While measuring (Pout), the amount (W) of pure water that came out of the membrane through the membrane in 1 minute was measured. Next, the water permeability [L / hr / m 2 / bar] of the hollow fiber membrane was calculated by the following formula.
(Water permeability) = W [L / min] × 60 [min / hr] / A [m 2 ] / ((Pin [bar] + Pout [bar]) / 2)
Here, A [m 2 ] = ID [m] × π × L [m] × number of hollow fiber membranes

（実施例１）
PES（住友ケムテック社製スミカエクセル（登録商標）4800P）18.9重量％、BASF社製PVP（コリドン（登録商標）K-30）3.1重量％、非溶媒として三菱化学社製TEG42.9重量％、溶媒に三菱化学社製NMP35.1重量％を均一に溶解したものを紡糸原液として用い、TEG42.9重量％、NMP35.1％、水22.0重量％の均一混合溶液を芯液とした。2重管構造の紡糸用口金を用い、外側から紡糸原液を、内側から芯液を、垂直下方に向け吐出し、中空糸膜を形成した。20mmの蒸気雰囲気中を通過させた後、凝固浴に浸漬させ、水洗浴、熱水浴を経た後、ドラム型カセによって巻取り速度8.3m/minで巻き取った。この際、中空糸膜は巻き取り直前まで捩れが生じないよう、単糸にて走行させた。また、巻き上げ機のダンサローラーは80mmφを用いた。
ノズル温度は75℃、外部凝固液温度は55℃に設定した。凝固浴内では径50mmの円筒状ガイドを3個使用して中空糸膜の進行方向を徐々に変え、凝固浴から引き出した。（図３参照）。凝固浴内における中空糸膜の浸漬深さは最大で800mm、凝固浴内での中空糸膜の走行距離は2000mmであった。
エージング条件は、Ｓ＝0.178、Ｈ＝1515、Ｈ／Ｓ＝8516であった。
巻き取られた中空糸膜の束を、80℃のRO水に60分間浸漬して加熱処理を行った。その後、60℃で10時間にわたり熱風乾燥を実施した。得られた中空糸膜を用いて種々の評価を行った。中空糸膜のIDは1.193mm、Δdは0.358mmであった（巻き取り時の径：2mm）。
結果を表1に示す。 Example 1
PES (Sumitomo Chemtec Co., Ltd. Sumika Excel (registered trademark) 4800P) 18.9 wt%, BASF PVP (Collidon (registered trademark) K-30) 3.1 wt%, non-solvent Mitsubishi Chemical TEG 42.9 wt%, solvent A solution obtained by uniformly dissolving 35.1% by weight of NMP manufactured by Mitsubishi Chemical Co., Ltd. was used as the spinning dope, and a uniform mixed solution of 42.9% by weight of TEG, 35.1% of NMP and 22.0% by weight of water was used as a core solution. Using a spinneret with a double-pipe structure, a spinning stock solution was discharged from the outside, and a core solution was discharged from the inside in a vertically downward direction to form a hollow fiber membrane. After passing through a 20 mm steam atmosphere, it was immersed in a coagulation bath, passed through a washing bath and a hot water bath, and then wound up with a drum type cassette at a winding speed of 8.3 m / min. At this time, the hollow fiber membrane was run with a single yarn so as not to twist until just before winding. The dancer roller of the hoisting machine used 80 mmφ.
The nozzle temperature was set to 75 ° C and the external coagulating liquid temperature was set to 55 ° C. In the coagulation bath, three cylindrical guides having a diameter of 50 mm were used, and the traveling direction of the hollow fiber membrane was gradually changed and pulled out from the coagulation bath. (See FIG. 3). The maximum immersion depth of the hollow fiber membrane in the coagulation bath was 800 mm, and the travel distance of the hollow fiber membrane in the coagulation bath was 2000 mm.
Aging conditions were S = 0.178, H = 1515, and H / S = 8516.
The wound bundle of hollow fiber membranes was immersed in RO water at 80 ° C. for 60 minutes for heat treatment. Thereafter, hot air drying was performed at 60 ° C. for 10 hours. Various evaluation was performed using the obtained hollow fiber membrane. The ID of the hollow fiber membrane was 1.193 mm, and Δd was 0.358 mm (diameter at winding: 2 mm).
The results are shown in Table 1.

（実施例２）
実施例１と同様にして中空糸膜を製造し、ドラム型カセによって巻取り速度8.3m/minで巻き取った。この際、中空糸膜は熱水浴途中まで単糸にて走行させ、熱水浴出口にて4本ごとに合糸して走行させた。エージング条件は、Ｓ＝0.180、Ｈ＝783、Ｈ／Ｓ＝4347であった。
巻き取られた中空糸膜の束を、60℃のRO水に120分間浸漬して加熱処理を行った。その後、60℃で10時間にわたり熱風乾燥を実施した。得られた中空糸膜を用いて種々の評価を行った。中空糸膜のIDは1.200mm、Δdは0.355mmであり、巻き取り時の合糸状態での全体径は4mmであった。
結果を表1に示す。 (Example 2)
A hollow fiber membrane was produced in the same manner as in Example 1, and wound with a drum type cassette at a winding speed of 8.3 m / min. At this time, the hollow fiber membrane was allowed to run with a single yarn part way through the hot water bath, and was run with four yarns joined at the hot water bath outlet. The aging conditions were S = 0.180, H = 783, and H / S = 4347.
The wound bundle of hollow fiber membranes was immersed in RO water at 60 ° C. for 120 minutes for heat treatment. Thereafter, hot air drying was performed at 60 ° C. for 10 hours. Various evaluation was performed using the obtained hollow fiber membrane. The hollow fiber membrane had an ID of 1.200 mm and a Δd of 0.355 mm, and the overall diameter in the combined state at the time of winding was 4 mm.
The results are shown in Table 1.

（実施例３）
PES（住友ケムテック社製スミカエクセル（登録商標）4800P）16.8重量％、BASF社製PVP（コリドン（登録商標）K-90）1.0重量％、非溶媒として三菱化学社製TEG45.2重量％、溶媒に三菱化学社製NMP37.0重量％を均一に溶解したものを紡糸原液として用い、TEG38.5重量％、NMP31.5％、水30.0重量％の均一混合溶液を芯液とした。2重管構造の紡糸用口金を用い、外側から紡糸原液を、内側から芯液を、垂直下方に向け吐出し、中空糸膜を形成した。30mmの蒸気雰囲気中を通過させた後、凝固浴に浸漬させ、水洗浴、熱水浴を経た後、3点カセによって巻取り速度20m/minで巻き取った。この際、中空糸膜は熱水浴途中まで単糸にて走行させ、熱水浴出口にて24本ごとに合糸して走行させた。また、巻き上げ機のダンサローラーは60mmφを用いた。
ノズル温度は70℃、外部凝固液温度は60℃に設定した。凝固浴内では径50mmの円筒状ガイドを3個使用して中空糸膜の進行方向を徐々に変え、凝固浴から引き出した。凝固浴内における中空糸膜の浸漬深さは最大で300mm、凝固浴内での中空糸膜の走行距離は1000mmであった。
エージング条件は、Ｓ＝0.00497、Ｈ＝149、Ｈ／Ｓ＝29980であった。
巻き取られた中空糸膜の束を、85℃のRO水に40min浸漬して加熱処理を行った。その後、60℃で10hにわたり熱風乾燥を実施した。得られた中空糸膜を用いて種々の評価を行った。中空糸膜のIDは0.282mm、Δdは0.079mmであり、24本まとめても巻き取り時の合糸状態での全体径は4mmと小さめであった。
結果を表1に示す。 (Example 3)
16.8% by weight of PES (Sumitomo Chemtec (registered trademark) 4800P manufactured by Sumitomo Chemtech), 1.0% by weight of PVP (Koridon (registered trademark) K-90) manufactured by BASF, 45.2% by weight of TEG manufactured by Mitsubishi Chemical Corporation as a non-solvent, solvent A solution obtained by uniformly dissolving 37.0% by weight of NMP manufactured by Mitsubishi Chemical Co., Ltd. was used as a spinning stock solution, and a uniform mixed solution of 38.5% by weight of TEG, 31.5% of NMP and 30.0% by weight of water was used as a core solution. Using a spinneret with a double-pipe structure, a spinning stock solution was discharged from the outside, and a core solution was discharged from the inside in a vertically downward direction to form a hollow fiber membrane. After passing through a 30 mm steam atmosphere, it was immersed in a coagulation bath, passed through a washing bath and a hot water bath, and then wound up at a winding speed of 20 m / min with a three-point casserole. At this time, the hollow fiber membrane was run with a single yarn halfway through the hot water bath, and run with 24 yarns joined at the hot water bath outlet. The dancer roller of the hoisting machine used 60 mmφ.
The nozzle temperature was set to 70 ° C, and the external coagulating liquid temperature was set to 60 ° C. In the coagulation bath, three cylindrical guides having a diameter of 50 mm were used, and the traveling direction of the hollow fiber membrane was gradually changed and pulled out from the coagulation bath. The maximum immersion depth of the hollow fiber membrane in the coagulation bath was 300 mm, and the travel distance of the hollow fiber membrane in the coagulation bath was 1000 mm.
The aging conditions were S = 0.00497, H = 149, H / S = 29980.
The wound bundle of hollow fiber membranes was immersed in RO water at 85 ° C. for 40 minutes and subjected to heat treatment. Thereafter, hot air drying was performed at 60 ° C. for 10 hours. Various evaluation was performed using the obtained hollow fiber membrane. The ID of the hollow fiber membrane was 0.282 mm and Δd was 0.079 mm. Even when 24 were combined, the overall diameter in the combined yarn state at the time of winding was as small as 4 mm.
The results are shown in Table 1.

（実施例４）
実施例３と同様の紡糸原液を用い、TEG44.0重量％、NMP36.0％、水20.0重量％の均一混合溶液を芯液とした。2重管構造の紡糸用口金を用い、外側から紡糸原液を、内側から芯液を、垂直下方に向け吐出し、中空糸膜を形成した。30mmの蒸気雰囲気中を通過させた後、凝固浴に浸漬させ、水洗浴、熱水浴を経た後、3点カセによって巻取り速度20m/minで巻き取った。この際、中空糸膜は熱水浴途中まで単糸にて走行させ、熱水浴出口にて12本ごとに合糸して走行させた。また、巻き上げ機のダンサローラーは60mmφを用いた。
ノズル温度は70℃、外部凝固液温度は60℃に設定した。凝固浴内では径50mmの円筒状ガイドを3個使用して中空糸膜の進行方向を徐々に変え、凝固浴から引き出した。凝固浴内における中空糸膜の浸漬深さは最大で300mm、凝固浴内での中空糸膜の走行距離は1000mmであった。
エージング条件は、Ｓ＝0.00812、Ｈ＝303、Ｈ／Ｓ＝37320であった。
巻き取られた中空糸膜の束を、80℃のRO水に60min浸漬して加熱処理を行った。その後、60℃で10hにわたり熱風乾燥を実施した。得られた中空糸膜を用いて種々の評価を行った。中空糸膜のIDは0.285mm、Δdは0.075mmであり、巻き取り時の合糸状態での全体径は3mmと小さいものであった。
結果を表１に示す。 Example 4
The same spinning stock solution as in Example 3 was used, and a uniform mixed solution of TEG 44.0% by weight, NMP 36.0%, and water 20.0% by weight was used as the core solution. Using a spinneret with a double-pipe structure, a spinning stock solution was discharged from the outside, and a core solution was discharged from the inside in a vertically downward direction to form a hollow fiber membrane. After passing through a 30 mm steam atmosphere, it was immersed in a coagulation bath, passed through a washing bath and a hot water bath, and then wound up at a winding speed of 20 m / min with a three-point casserole. At this time, the hollow fiber membrane was allowed to run with a single yarn partway through the hot water bath, and was run with every 12 yarns joined at the hot water bath outlet. The dancer roller of the hoisting machine used 60 mmφ.
The nozzle temperature was set to 70 ° C, and the external coagulating liquid temperature was set to 60 ° C. In the coagulation bath, three cylindrical guides having a diameter of 50 mm were used, and the traveling direction of the hollow fiber membrane was gradually changed and pulled out from the coagulation bath. The maximum immersion depth of the hollow fiber membrane in the coagulation bath was 300 mm, and the travel distance of the hollow fiber membrane in the coagulation bath was 1000 mm.
The aging conditions were S = 0.00812, H = 303, H / S = 37320.
The wound bundle of hollow fiber membranes was immersed in RO water at 80 ° C. for 60 minutes for heat treatment. Thereafter, hot air drying was performed at 60 ° C. for 10 hours. Various evaluation was performed using the obtained hollow fiber membrane. The ID of the hollow fiber membrane was 0.285 mm, Δd was 0.075 mm, and the overall diameter in the combined yarn state at the time of winding was as small as 3 mm.
The results are shown in Table 1.

（実施例５）
実施例３と同様の紡糸原液を用い、TEG42.9重量％、NMP35.1％、水22.0重量％の均一混合溶液を芯液とした。2重管構造の紡糸用口金を用い、外側から紡糸原液を、内側から芯液を、垂直下方に向け吐出し、中空糸膜を形成した。20mmの蒸気雰囲気中を通過させた後、凝固浴に浸漬させ、水洗浴、熱水浴を経た後、3点カセによって巻取り速度18m/minで巻き取った。この際、中空糸膜は熱水浴途中まで単糸にて走行させ、熱水浴出口にて12本ごとに合糸して走行させた。また、巻き上げ機のダンサローラーは60mmφを用いた。
ノズル温度は65℃、外部凝固液温度は55℃に設定した。凝固浴内では径50mmの円筒状ガイドを3個使用して中空糸膜の進行方向を徐々に変え、凝固浴から引き出した。凝固浴内における中空糸膜の浸漬深さは最大で300mm、凝固浴内での中空糸膜の走行距離は1000mmであった。
また、エージング条件としてＳ＝0.00644、Ｈ＝231、Ｈ／Ｓ＝35870であった。
巻き取られた中空糸膜の束を、90℃のRO水に60min浸漬して加熱処理を行った。その後、60℃で10hにわたり熱風乾燥を実施した。得られた中空糸膜を用いて種々の評価を行った。中空糸膜のIDは0.290mm、Δdは0.148mmであり、巻き取り時の合糸状態での全体径は4mmと小さめであった。
結果を表１に示す。 (Example 5)
The same spinning stock solution as in Example 3 was used, and a uniform mixed solution of 42.9% by weight of TEG, 35.1% of NMP, and 22.0% by weight of water was used as a core solution. Using a spinneret with a double-pipe structure, a spinning stock solution was discharged from the outside, and a core solution was discharged from the inside in a vertically downward direction to form a hollow fiber membrane. After passing through a 20 mm steam atmosphere, it was immersed in a coagulation bath, passed through a washing bath and a hot water bath, and then wound up at a winding speed of 18 m / min with a three-point casserole. At this time, the hollow fiber membrane was allowed to run with a single yarn partway through the hot water bath, and was run with every 12 yarns joined at the hot water bath outlet. The dancer roller of the hoisting machine used 60 mmφ.
The nozzle temperature was set to 65 ° C and the external coagulating liquid temperature was set to 55 ° C. In the coagulation bath, three cylindrical guides having a diameter of 50 mm were used, and the traveling direction of the hollow fiber membrane was gradually changed and pulled out from the coagulation bath. The maximum immersion depth of the hollow fiber membrane in the coagulation bath was 300 mm, and the travel distance of the hollow fiber membrane in the coagulation bath was 1000 mm.
The aging conditions were S = 0.00644, H = 231, and H / S = 35870.
The wound bundle of hollow fiber membranes was immersed in RO water at 90 ° C. for 60 minutes for heat treatment. Thereafter, hot air drying was performed at 60 ° C. for 10 hours. Various evaluation was performed using the obtained hollow fiber membrane. The ID of the hollow fiber membrane was 0.290 mm and Δd was 0.148 mm, and the overall diameter in the combined yarn state during winding was as small as 4 mm.
The results are shown in Table 1.

（比較例１）
実施例１と同様にして中空糸膜を形成し、ドラム型カセによって巻取り速度8.3m/minで巻き取った。この際、中空糸膜は熱水浴途中まで単糸にて走行させ、熱水浴出口にて12本ごとに合糸して走行させた。
巻き取られた中空糸膜の束を乾燥処理し、その後前述の評価を行った。中空糸膜のIDは1.198mm、Δdは0.353mmであり、巻き取り時の合糸状態での全体径は10mmと非常に太くなった。その結果、外圧潰れ数は14.8個/kmとなった。これは、巻き取り時の合糸本数が多く太かったために、中空糸膜に捩れが生じたことと、巻取り時に受けるテンションの影響によって局部的なストレスを受けたためと推測する。
結果を表1に示す。 (Comparative Example 1)
A hollow fiber membrane was formed in the same manner as in Example 1, and wound with a drum type cassette at a winding speed of 8.3 m / min. At this time, the hollow fiber membrane was allowed to run with a single yarn partway through the hot water bath, and was run with every 12 yarns joined at the hot water bath outlet.
The wound bundle of hollow fiber membranes was dried and then evaluated as described above. The ID of the hollow fiber membrane was 1.198 mm and Δd was 0.353 mm, and the overall diameter in the combined yarn state at the time of winding was as extremely thick as 10 mm. As a result, the number of external crushing was 14.8 / km. This is presumably because the number of combined yarns at the time of winding was large and thick, so that the hollow fiber membrane was twisted and was subjected to local stress due to the influence of the tension applied at the time of winding.
The results are shown in Table 1.

（比較例２）
実施例１と同様にして中空糸膜を形成し、ドラム型カセによって巻取り速度8.3m/minで巻き取った。この際、中空糸膜は熱水浴途中まで単糸にて走行させ、熱水浴出口にて10本ごとに合糸して走行させた。
巻き取られた中空糸膜の束を乾燥処理し、その後前述の評価を行った。中空糸膜のIDは1.205mm、Δdは0.353mmであり、巻き取り時の合糸状態での全体径は8mmであった。その結果、外圧潰れ数は6.6個/kmとなった。
結果を表1に示す。 (Comparative Example 2)
A hollow fiber membrane was formed in the same manner as in Example 1, and wound with a drum type cassette at a winding speed of 8.3 m / min. At this time, the hollow fiber membrane was allowed to run with a single yarn part way through the hot water bath, and was run with 10 yarns combined at the hot water bath outlet.
The wound bundle of hollow fiber membranes was dried and then evaluated as described above. The ID of the hollow fiber membrane was 1.205 mm, Δd was 0.353 mm, and the overall diameter in the combined yarn state at the time of winding was 8 mm. As a result, the number of external crushing was 6.6 / km.
The results are shown in Table 1.

（比較例３）
実施例１と同様にして中空糸膜を形成し、ドラム型カセによって巻取り速度8.3m/minで巻き取った。この際、中空糸膜は熱水浴途中まで単糸にて走行させ、熱水浴出口にて3本ごとに合糸して走行させた。
巻き取られた中空糸膜の束を乾燥処理し、その後前述の評価を行った。中空糸膜のIDは1.275mm、Δdは0.308mmであり、巻き取り時の合糸状態での全体径は3mmであった。その結果、外圧潰れ数は62.8個/kmと非常に多くなった。これは、径の太い糸であるにもかかわらず、Δd／IDが0.242と小さいために、外圧に対する耐久度が低くなってしまったことが主な要因であると考えられる。
結果を表1に示す。 (Comparative Example 3)
A hollow fiber membrane was formed in the same manner as in Example 1, and wound with a drum type cassette at a winding speed of 8.3 m / min. At this time, the hollow fiber membrane was made to run with a single yarn part way through the hot water bath, and was run with the yarn spliced every three at the hot water bath outlet.
The wound bundle of hollow fiber membranes was dried and then evaluated as described above. The ID of the hollow fiber membrane was 1.275 mm, Δd was 0.308 mm, and the total diameter in the combined yarn state at the time of winding was 3 mm. As a result, the number of external crushing increased to 62.8 / km. This is considered to be mainly due to the fact that the durability against external pressure is low because Δd / ID is as small as 0.242 despite the fact that the yarn has a large diameter.
The results are shown in Table 1.

（比較例４）
実施例３と同様にして中空糸膜を形成し、3点カセによって巻取り速度20m/minで巻き取った。この際、中空糸膜は熱水浴途中まで単糸にて走行させ、熱水浴出口にて24本ごとに合糸して走行させた。
巻き取られた中空糸膜の束を乾燥処理し、その後前述の評価を行った。中空糸膜のIDは0.280mm、Δdは0.079mmであり、巻き取り時の合糸状態での全体径は4mmであった。その結果、外圧潰れ数は1.7個/kmとなった。これは、中空糸膜の偏肉度が0.63と低いために、膜厚の薄い部分で外圧に対する耐性が弱い状態となっていたためと考えられる。
結果を表1に示す。 (Comparative Example 4)
A hollow fiber membrane was formed in the same manner as in Example 3, and wound with a three-point cassette at a winding speed of 20 m / min. At this time, the hollow fiber membrane was run with a single yarn halfway through the hot water bath, and run with 24 yarns joined at the hot water bath outlet.
The wound bundle of hollow fiber membranes was dried and then evaluated as described above. The ID of the hollow fiber membrane was 0.280 mm, Δd was 0.079 mm, and the overall diameter in the combined yarn state at the time of winding was 4 mm. As a result, the number of external crushing was 1.7 / km. This is presumably because the thickness of the hollow fiber membrane was as low as 0.63, so that the resistance to external pressure was weak at the thin portion.
The results are shown in Table 1.

（比較例５）
実施例４と同様にして中空糸膜を形成し、3点カセによって巻取り速度20m/minで巻き取った。この際、中空糸膜は熱水浴途中まで単糸にて走行させ、熱水浴出口にて24本ごとに合糸して走行させた。
巻き取られた中空糸膜の束を乾燥処理し、その後前述の評価を行った。中空糸膜のIDは0.280mm、Δdは0.062mmであり、巻き取り時の合糸状態での全体径は4mmであった。その結果、外圧潰れ数は2.3個/kmとなった。これは、Δd／IDが0.221と小さいことと、中空糸膜の真円度が0.71と低いために外圧をかけたときに偏平に近づきやすくなっていたことの双方の要因によるものと推測する。
結果を表１に示す。 (Comparative Example 5)
A hollow fiber membrane was formed in the same manner as in Example 4, and was wound up at a winding speed of 20 m / min with a three-point cassette. At this time, the hollow fiber membrane was run with a single yarn halfway through the hot water bath, and run with 24 yarns joined at the hot water bath outlet.
The wound bundle of hollow fiber membranes was dried and then evaluated as described above. The ID of the hollow fiber membrane was 0.280 mm, Δd was 0.062 mm, and the overall diameter in the combined yarn state at the time of winding was 4 mm. As a result, the number of external crushing was 2.3 / km. This is presumably due to both the fact that Δd / ID is as small as 0.221 and that the roundness of the hollow fiber membrane is as low as 0.71, and that it is easy to approach flatness when external pressure is applied.
The results are shown in Table 1.

実施例、比較例より明らかなように、本発明により、高分子多孔質中空糸膜が外圧による潰れ発生を抑制できるので、膜の破損を防ぎ、耐久性の高い長期間使用可能な高分子多孔質中空糸膜を提供するできることがわかる。   As is clear from the examples and comparative examples, according to the present invention, the polymer porous hollow fiber membrane can suppress the occurrence of crushing due to external pressure. It can be seen that a hollow fiber membrane can be provided.

本発明の高分子多孔質中空糸膜によれば、中空糸膜の外圧に対する耐性を向上させることができ、より品質の高い高分子多孔質中空糸膜を得ることができる。また、外圧によって中空糸膜に潰れが発生すると、膜の破損を招き、大きな問題となることがあるが、本発明の高分子多孔質中空糸膜により潰れの発生を抑制できるので、膜の破損を防止することが可能となる。従って、特に水性流体処理プロセスにおける洗浄など、高圧での外圧負荷を中空糸膜にかける必要がある場合などに好適に利用でき、産業界に大きな貢献が可能である。   According to the polymer porous hollow fiber membrane of the present invention, the resistance of the hollow fiber membrane to the external pressure can be improved, and a higher quality polymer porous hollow fiber membrane can be obtained. In addition, if the hollow fiber membrane is crushed by external pressure, the membrane may be damaged, which may be a serious problem, but the occurrence of crushing can be suppressed by the polymer porous hollow fiber membrane of the present invention. Can be prevented. Therefore, it can be suitably used when a high-pressure external pressure load needs to be applied to the hollow fiber membrane, such as washing in an aqueous fluid treatment process, and can greatly contribute to the industry.

外圧により生じた中空糸膜の潰れ部位の拡大写真。The enlarged photograph of the crushing part of the hollow fiber membrane produced by the external pressure. 外圧により生じた中空糸膜の潰れ部位と正常部位の断面拡大写真。The cross-sectional enlarged photograph of the crushing part and normal part of a hollow fiber membrane which arose by external pressure. 本願発明における凝固浴中での中空糸膜の走行状態の一例を示す模式図。The schematic diagram which shows an example of the running state of the hollow fiber membrane in the coagulation bath in this invention. 従来技術の凝固浴中での中空糸膜の走行状態を示す模式図。The schematic diagram which shows the running state of the hollow fiber membrane in the coagulation bath of a prior art.

符号の説明Explanation of symbols

１：中空糸膜
２：外圧により生じた中空糸膜の潰れ部位
３：外圧により生じた中空糸膜の潰れ部位
1: Hollow fiber membrane 2: Collapsed portion of hollow fiber membrane caused by external pressure 3: Collapsed portion of hollow fiber membrane caused by external pressure

Claims (7)

（ａ）中空糸膜の内径をID(mm)、膜厚をΔd(mm)としたとき、0.25≦Δd／ID≦0.5であり、
（ｂ）中空糸膜の偏肉度が0.75以上であり、
（ｃ）中空糸膜の真円度が0.75以上であり、
（ｄ）中空糸膜の外側より30分間0.4MPaの外圧をかけたとき、中空糸膜に生じる潰れの個数が、中空糸膜1kmあたり1個以下であり、
（ｅ）中空糸膜の透水性が500L/hr/m2/bar以上である
ことを特徴とする高分子多孔質中空糸膜。 (A) When the inner diameter of the hollow fiber membrane is ID (mm) and the film thickness is Δd (mm), 0.25 ≦ Δd / ID ≦ 0.5,
(B) The hollow fiber membrane has an uneven thickness of 0.75 or more,
(C) The roundness of the hollow fiber membrane is 0.75 or more,
(D) When an external pressure of 0.4 MPa is applied for 30 minutes from the outside of the hollow fiber membrane, the number of crushes generated in the hollow fiber membrane is 1 or less per 1 km of the hollow fiber membrane,
(E) A polymer porous hollow fiber membrane, wherein the water permeability of the hollow fiber membrane is 500 L / hr / m 2 / bar or more. 中空糸膜が非対称構造を有することを特徴とする請求項１記載の高分子多孔質中空糸膜。   The polymer porous hollow fiber membrane according to claim 1, wherein the hollow fiber membrane has an asymmetric structure. 中空糸膜が主として疎水性高分子からなることを特徴とする請求項１または２記載の高分子多孔質中空糸膜。   3. The polymer porous hollow fiber membrane according to claim 1, wherein the hollow fiber membrane is mainly composed of a hydrophobic polymer. 疎水性高分子がポリスルホン系高分子であることを特徴とする請求項３記載の高分子多孔質中空糸膜。   The polymer porous hollow fiber membrane according to claim 3, wherein the hydrophobic polymer is a polysulfone polymer. 中空糸膜が外表面に緻密層を有することを特徴とする請求項１〜４いずれか記載の高分子多孔質中空糸膜。   5. The polymer porous hollow fiber membrane according to claim 1, wherein the hollow fiber membrane has a dense layer on the outer surface. 中空糸膜の内表面および外表面に緻密層を持ち、内表面から膜内部に向かって当初孔径が次第に増大し、少なくとも一つの極大部を通過後、外表面に向かって孔径が次第に減少することを特徴とする請求項１〜５いずれか記載の高分子多孔質中空糸膜。   It has a dense layer on the inner and outer surfaces of the hollow fiber membrane, the initial pore diameter gradually increases from the inner surface toward the inside of the membrane, and after passing through at least one local maximum, the pore diameter gradually decreases toward the outer surface. The polymer porous hollow fiber membrane according to any one of claims 1 to 5. 中空糸膜の外径をOD(mm)としたとき、0.4≦ODであることを特徴とする請求項１〜６いずれか記載の高分子多孔質中空糸膜。
The polymer porous hollow fiber membrane according to any one of claims 1 to 6, wherein 0.4? OD when the outer diameter of the hollow fiber membrane is OD (mm).
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