JP4050606B2 - Method for producing three-layer composite hollow fiber membrane - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、例えば、ガス分離、逆浸透、透析、限界ろ過等に用いられる高能率な三層複合中空糸膜を、歩留り良く製造する方法に関する。
【０００２】
【従来の技術】
従来より、非多孔質の超薄膜層（中間層）を、多孔質の支持層（最内層および最外層）でサンドイッチした構造を有する三層複合中空糸膜が知られている。このような三層複合中空糸膜において、中間層はガス分離等の分離機能を有し、最内層と最外層は中間層を補強・支持する機能を有する。
【０００３】
このような三層複合中空糸膜を製造する為の方法として、例えば、特許文献１に記載の方法がある。具体的には、まず、紡糸ノズルの同心円状に配置された三つの吐出口（最内層用、中間層用、最外層用）から、溶融状態の各原料ポリマーを同時に吐出し、巻き取り、未延伸糸を得る。そして、この未延伸糸を延伸して、最内層と最外層を多孔化することにより、所望の三層複合中空糸膜を得ることができる。
【０００４】
しかし、紡糸ノズルから溶融ポリマーを吐出させて巻き取り、未延伸を得る工程、いわゆる紡糸工程において、ポリマーの種類によっては、吐出する溶融ポリマー中に加熱に起因する発泡が生じる場合がある。そして、中間層に気泡が存在すると、その中間層を延伸等により薄膜化する際にもミクロボイドが残存し、微小欠陥によりガス分離等の機能を発現できなくなる。さらに発泡以外の問題、例えば、初期の吐出状態が不安定で、これが中間層の性能に悪影響を及ぼすという問題もある。このような発泡およびその他の問題は、得られる三層複合中空糸膜の欠陥の原因となり、その結果、製品歩留りの低下の原因となる。
【０００５】
【特許文献１】
特開昭６２−１４０４号公報
【０００６】
【発明が解決しようとする課題】
本発明は、上述した従来技術の課題を解決するためになされたものである。すなわち本発明の目的は、中間層に欠陥が無く、分離機能を良好に発現する三層複合中空糸膜を、歩留り良く製造できる方法を提供することにある。
【０００７】
【課題を解決するための手段】
本発明は、ノズルから溶融ポリマーを吐出して紡糸する工程を有する三層複合中空糸膜の製造方法において、中間層用のポリマーの吐出を先に開始し、その後、支持層用のポリマーの吐出を開始することを特徴とする三層複合中空糸膜の製造方法である。
【０００８】
【発明の実施の形態】
本発明において、三層複合中空糸膜とは、代表的には、分離機能を有する非多孔質の中間層と、これを内側および外側から支持する多孔質の支持層（最内層および最外層）からなる中空糸膜である。
【０００９】
中間層を構成するポリマーは、ガス分離機能を有する薄膜を形成可能なものが好ましい。例えば、ポリウレタン系重合体、ポリエチレン、ポリプロピレン等に代表されるポリオレフィン系重合体、シリコン系重合体、セルロース系重合体、ポリスルホン系重合体、ＰＶＡ系重合体、ポリエステル系重合体、ポリエーテル系重合体、ポリアミド系重合体、ポリイミド系重合体等が挙げられる。なかでも、ポリウレタン系重合体、ポリオレフィン系重合体が好ましく、ポリウレタン系重合体が特に好ましい。
【００１０】
支持層を構成するポリマーとしては、延伸により多孔化するポリマーが好ましい。例えば、ポリエチレン、ポリプロピレン等に代表されるポリオレフィン系重合体、ポリカーボネート系重合体、ポリエステル系重合体等が挙げられる。なかでも、ポリオレフィン系重合体が好ましい。また、溶出物をブンレンドしたポリマーを使用し、三層複合中空糸膜として成形した後に、溶出物を溶出させて多孔化する、いわゆる溶出法も目的に応じて使用可能である。
【００１１】
最終製品としての三層複合中空糸膜の内径は１００〜５０００μｍが好ましく、中間層の厚さは１０μｍ以下が好ましく、全膜厚は１０〜１０００μｍが好ましい。中間層の位置は、膜厚方向の中心部に設けてもよいし、最外層側や最内層側に近い位置に偏心させて設けてもよい。
【００１２】
本発明においては、まず、これら原料ポリマーを紡糸ノズルから吐出して、最内層、中間層、最外層からなる三層構造の未延伸糸（中空糸膜）を得る。そして、例えば、この未延伸糸を延伸することにより、最内層と最外層を多孔化して三層複合中空糸膜を得る。以下の説明においては、前者の工程を紡糸工程、後者の工程を延伸工程と称す。
【００１３】
紡糸工程に用いるノズルとしては、通常は、同心円状に配置された三つの吐出口（最内層用吐出口、中間層用吐出口、最外層用吐出口）を有するノズルを使用する。この三つの吐出口から各原料ポリマーを溶融吐出し、これを冷却して巻き取れば、三層構造の未延伸糸が得られる。
【００１４】
本発明の紡糸工程においては、中間層用のポリマーの吐出を先に開始し、その後、支持層（最内層および最外層）用のポリマーの吐出を開始する。
【００１５】
ここで、例えば、ポリマー中およびホッパー内等のポリマー供給系内に水分が存在すると、ポリマーの種類によっては、吐出する溶融ポリマー中に加熱に起因する発泡が生じる場合がある。しかし、本発明においては、中間層用のポリマーの吐出を先に開始するので、吐出する中間層用のポリマー中の気泡が無くなったことを目視にて確認することができる。さらに、発泡以外の問題の有無の確認、例えば、吐出初期において、吐出されるポリマーの廻り込みが均一か否かの確認、安定した吐出状態になっているかどうかの確認も目視で行うことができる。これらの確認後に、支持層用のポリマーの吐出を開始すれば、中間層に欠陥が無い三層複合中空糸膜を歩留り良く製造できる。
【００１６】
これに対し、中間層用のポリマーと支持層用のポリマーの吐出を同時に開始すると、中間層用のポリマー中の気泡の有無やその他の問題の確認を行うことができず、最終的な製品歩留りが著しく低下してしまう。
【００１７】
特に、三層複合中空糸膜において、中間層の欠陥は主として分離機能に直接影響を与える欠陥なので、本発明のように中間層用のポリマー中の気泡等の問題の有無を確認することは非常に効果的である。また、支持層は中間層に比べて厚い膜なので、支持層用のポリマーの吐出量は中間層用のポリマーの吐出量よりも多量である。したがって、問題が無いことを確認できるまで中間層用のポリマーのみ吐出することは、支持層用のポリマーのロス抑制等の点からも効果的である。
【００１８】
通常、吸湿性のポリマーを溶融してノズルから連続的に吐出する場合、発泡が無くなるまで吐出し続けること、いわゆる泡抜けの時間は、ポリマーの種類や中間層の厚みに応じて適宜調整する。ここで、中間層を薄膜化する場合は、吐出の為に極微量のギアポンプ（０.０５ｃｃ／ｒｅｖ）を使用するのが一般的であり、泡抜けの時間は９０分程度必要である。
【００１９】
上述した問題が無いことを確認した後、中間層用のポリマーの吐出を継続しつつ、支持層用のポリマーの吐出を開始する。そして、例えば、吐出直後に冷却して巻取ることにより、３層構造の未延伸糸が得られる。さらに、この未延伸糸の最内層および最外層を延伸処理等で多孔化することによって、三層複合中空糸膜が得られる。
【００２０】
延伸処理による多孔化は、従来よりポリオレフィン等で行われている公知の延伸方法を用いることができる。すなわち、低温から常温の範囲内の温度において少量の延伸を行い白化・開裂させ、続いて加熱延伸によって孔の拡大と孔形状の安定化を図る。これら延伸処理においては、中間層も同時に延伸されるので、この場合、中間層は、延伸では破壊しないことが必要である。
【００２１】
また、本発明においては、紡糸工程を行う前に、前処理としてペレット状等のポリマーを乾燥しておくことが好ましい。例えば、ポリウレタン系重合体等の吸湿性ポリマーを用いる場合、吸湿性ポリマーのペレットの乾燥処理を行っておけば、使用するポリマー内の水分が除去されるので、紡糸時の発泡をさらに抑制することができる。乾燥方法としては、例えば真空乾燥等が挙げられる。
【００２２】
さらに、ノズルへのポリマーの供給系内を、ポリマー装入後、吐出前に乾燥窒素で置換することが好ましい。例えば、吸湿性ポリマーのペレットを吐出装置のホッパーに投入した後、ホッパー内を乾燥窒素で置換しておけば、供給するポリマー内の水分が除去されるので、紡糸時の発泡をさらに抑制することができる。
【００２３】
【実施例】
＜実施例１＞
本実施例では、中間層用の吸湿性ポリマーとしてセグメント化ポリウレタン［Thermedics社製、商品名Tecoflex EG80A、吸水率０.７２％（６５％ＲＨ、２０℃×２４ｈｒ）］のペレット、支持層用の撥水性ポリマーとして高密度ポリエチレン（三井住友ポリオレフィン社製、商品名Hizex 2200J）のペレットを用意した。また、セグメント化ポリウレタンは吸湿性ポリマーなので、紡糸前に、真空乾燥機にて６０℃で８時間以上乾燥した。
【００２４】
これらペレットを、紡糸装置のホッパーに投入し、密閉系とし、系内を乾燥窒素でパージした。この紡糸装置の紡糸ノズルには、最内層、中間層、最外層と、同心円状に配置された三重環状の吐出口が形成されている。
【００２５】
そして、まず、この紡糸ノズルの中間層用の吐出口から、中間層用ポリマーを１６５℃にて吐出した。この吐出の際は、極微量のギアポンプ（０.０５ｃｃ／ｒｅｖ）を使用し、最大ギアポンプ回転数（約４０ｒｐｍ）で押し出した。
【００２６】
吐出初期においては、ポリマー中に気泡が含まれている事が目視にて確認された。そのまま吐出を継続したところ、吐出開始から約９０分後には、気泡が無い事を確認できた。この時点で、紡糸ノズルの最内層用の吐出口および最外層用の吐出口から、支持層用のポリマーを１６５℃にて吐出した。この吐出した３層構造の押出し繊維は冷却風区間に通されることにより冷却固化され、これを紡糸速度１７０ｍ／分にて巻き取り、３層構造の未延伸糸を得た。
【００２７】
この未延伸糸に対して、従来より行われているアニール処理、冷延伸、熱延伸熱セットを行うことにより、多孔質の支持層（最内層、最外層）の間に、気体分離可能な非多孔質の超薄膜層（中間層）をサンドイッチした構造を有する三層複合中空糸膜を得た。この三層複合中空糸膜の内径は２００μｍ、最内層の厚さは２０μｍ、中間層の厚さは１μｍ、最外層の厚さは２０μｍであった。
【００２８】
この三層複合中空糸膜のガス透過性能（透過速度［Ｏ2Ｆｌｕｘ］、分離係数［α］）を測定したところ、紡糸初期から最後まで、中間層ポリマー物性に問題がないことを裏付ける数値［Ｏ2Ｆｌｕｘ＝０.２８ｍ3／ｍ2・ｈｒ・ＭＰａ、α（Ｏ2／Ｎ2）＝２.７］を維持し、ミクロボイド等の微小欠陥が無い、正常な膜であった。
【００２９】
＜比較例１＞
ポリマーを吐出する際、中間層用および支持層用のポリマーを同時に吐出させたこと以外は、実施例１と同様にして三層複合中空糸膜を製造した。この三層複合中空糸膜のうち、初期紡糸品は、ガス透過性能は、透過速度が高く、分離係数が低下しており、適正なガス分離性能を有しておらず、規格外の不良品であった。これは、中間層部の気泡含有によるミクロボイド欠陥によるものと推定される。なお、初期紡糸品ではなくそれ以降の時点での紡糸品については、紡糸継続時間の経過と共に次第に透過性能は正常な値に復帰していた。
【００３０】
＜参考例１＞
中間層ポリマーのペレットを、紡糸前に真空乾燥せずにホッパーに投入したこと以外は、実施例１と同様にして三層複合中空糸膜を製造した。この三層複合中空糸膜のガス透過性能は、紡糸初期から最後まで透過速度が高く、分離係数が低下しており、適正なガス分離性能を有しておらず、規格外の不良品であった。これは、中間層部の気泡含有によるミクロボイド欠陥によるものと推定される。
【００３１】
＜参考例２＞
真空乾燥した中間層ポリマーのペレットをホッパーに投入後、乾燥窒素をパージしなかったこと以外は、実施例１と同様にして三層複合中空糸膜を製造した。この三層複合中空糸膜のガス透過性能は、紡糸初期から最後まで、透過速度が高く、分離係数が低下しており、適正なガス分離性能を有しておらず、規格外の不良品であった。これは、中間層部の気泡含有によるミクロボイド欠陥によるものと推定される。
【００３２】
【発明の効果】
以上説明したように、本発明によれば、中間層に欠陥が無く、ガス分離機能を良好に発現する三層複合中空糸膜を、歩留り良く製造できる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a high-efficiency three-layer composite hollow fiber membrane used in, for example, gas separation, reverse osmosis, dialysis, ultrafiltration and the like with high yield.
[0002]
[Prior art]
Conventionally, a three-layer composite hollow fiber membrane having a structure in which a non-porous ultra-thin layer (intermediate layer) is sandwiched between porous support layers (innermost layer and outermost layer) is known. In such a three-layer composite hollow fiber membrane, the intermediate layer has a separation function such as gas separation, and the innermost layer and the outermost layer have a function of reinforcing and supporting the intermediate layer.
[0003]
As a method for producing such a three-layer composite hollow fiber membrane, for example, there is a method described in Patent Document 1. Specifically, first, each raw polymer in a molten state is simultaneously discharged from three discharge ports (for the innermost layer, for the intermediate layer, and for the outermost layer) arranged concentrically with the spinning nozzle, wound up, A drawn yarn is obtained. And by stretching this undrawn yarn and making the innermost layer and the outermost layer porous, a desired three-layer composite hollow fiber membrane can be obtained.
[0004]
However, in a process of discharging a molten polymer from a spinning nozzle and winding it to obtain unstretched, a so-called spinning process, foaming due to heating may occur in the discharged molten polymer depending on the type of polymer. If air bubbles are present in the intermediate layer, microvoids remain even when the intermediate layer is thinned by stretching or the like, and functions such as gas separation cannot be expressed due to minute defects. Further, there are problems other than foaming, for example, the initial discharge state is unstable, which adversely affects the performance of the intermediate layer. Such foaming and other problems cause defects in the resulting three-layer composite hollow fiber membrane and, as a result, reduce product yield.
[0005]
[Patent Document 1]
JP-A-62-1404 [0006]
[Problems to be solved by the invention]
The present invention has been made to solve the above-described problems of the prior art. That is, an object of the present invention is to provide a method capable of producing a three-layer composite hollow fiber membrane having no defects in an intermediate layer and exhibiting a good separation function with high yield.
[0007]
[Means for Solving the Problems]
The present invention provides a method for producing a three-layer composite hollow fiber membrane comprising a step of discharging a molten polymer from a nozzle and spinning, starting the discharge of the polymer for the intermediate layer first, and then discharging the polymer for the support layer. Is a method for producing a three-layer composite hollow fiber membrane.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the three-layer composite hollow fiber membrane is typically a non-porous intermediate layer having a separation function and a porous support layer (the innermost layer and the outermost layer) that supports the inner layer and the outer side. A hollow fiber membrane made of
[0009]
The polymer constituting the intermediate layer is preferably one that can form a thin film having a gas separation function. For example, polyurethane polymer, polyolefin polymer represented by polyethylene, polypropylene, etc., silicon polymer, cellulose polymer, polysulfone polymer, PVA polymer, polyester polymer, polyether polymer , Polyamide polymers, polyimide polymers, and the like. Of these, polyurethane polymers and polyolefin polymers are preferable, and polyurethane polymers are particularly preferable.
[0010]
The polymer constituting the support layer is preferably a polymer that becomes porous by stretching. Examples thereof include polyolefin polymers typified by polyethylene and polypropylene, polycarbonate polymers, polyester polymers, and the like. Of these, polyolefin polymers are preferred. Further, a so-called elution method in which a polymer obtained by blending an eluate is used to form a three-layer composite hollow fiber membrane and then the eluate is eluted to make it porous can be used depending on the purpose.
[0011]
The inner diameter of the three-layer composite hollow fiber membrane as the final product is preferably 100 to 5000 μm, the thickness of the intermediate layer is preferably 10 μm or less, and the total thickness is preferably 10 to 1000 μm. The position of the intermediate layer may be provided at the center in the film thickness direction, or may be provided eccentric to a position close to the outermost layer side or the innermost layer side.
[0012]
In the present invention, first, these raw material polymers are discharged from a spinning nozzle to obtain a three-layer undrawn yarn (hollow fiber membrane) comprising an innermost layer, an intermediate layer, and an outermost layer. Then, for example, by stretching the undrawn yarn, the innermost layer and the outermost layer are made porous to obtain a three-layer composite hollow fiber membrane. In the following description, the former process is called a spinning process, and the latter process is called a drawing process.
[0013]
As the nozzle used in the spinning process, a nozzle having three discharge ports (the innermost layer discharge port, the intermediate layer discharge port, and the outermost layer discharge port) arranged concentrically is usually used. If each raw material polymer is melted and discharged from these three discharge ports, and cooled and wound up, an undrawn yarn having a three-layer structure can be obtained.
[0014]
In the spinning process of the present invention, the discharge of the polymer for the intermediate layer is started first, and then the discharge of the polymer for the support layer (the innermost layer and the outermost layer) is started.
[0015]
Here, for example, when water is present in the polymer and in the polymer supply system such as in the hopper, foaming due to heating may occur in the discharged molten polymer depending on the type of the polymer. However, in the present invention, since the discharge of the polymer for the intermediate layer is started first, it can be visually confirmed that there are no bubbles in the polymer for the intermediate layer to be discharged. In addition, it is possible to visually check whether there is a problem other than foaming, for example, whether the wrapping of the discharged polymer is uniform in the initial stage of discharge, and whether it is in a stable discharge state. . If the discharge of the polymer for the support layer is started after these confirmations, a three-layer composite hollow fiber membrane having no defects in the intermediate layer can be produced with a high yield.
[0016]
On the other hand, if the discharge of the polymer for the intermediate layer and the polymer for the support layer is started at the same time, the presence or absence of bubbles in the polymer for the intermediate layer and other problems cannot be confirmed, and the final product yield Will drop significantly.
[0017]
In particular, in a three-layer composite hollow fiber membrane, the defect in the intermediate layer is a defect that directly affects the separation function, so it is very important to confirm whether there is a problem such as bubbles in the polymer for the intermediate layer as in the present invention. It is effective. Further, since the support layer is a thicker film than the intermediate layer, the discharge amount of the polymer for the support layer is larger than the discharge amount of the polymer for the intermediate layer. Therefore, discharging only the polymer for the intermediate layer until it can be confirmed that there is no problem is also effective from the viewpoint of suppressing the loss of the polymer for the support layer.
[0018]
In general, when a hygroscopic polymer is melted and continuously discharged from a nozzle, the discharge time until foaming disappears, the so-called bubble removal time, is appropriately adjusted according to the type of polymer and the thickness of the intermediate layer. Here, when the intermediate layer is made thin, it is common to use a very small amount of gear pump (0.05 cc / rev) for discharging, and the bubble removal time needs to be about 90 minutes.
[0019]
After confirming that there is no problem described above, the discharge of the polymer for the support layer is started while continuing the discharge of the polymer for the intermediate layer. For example, a three-layer undrawn yarn can be obtained by cooling and winding immediately after discharge. Furthermore, a three-layer composite hollow fiber membrane is obtained by making the innermost layer and the outermost layer of the undrawn yarn porous by a drawing treatment or the like.
[0020]
For the pore formation by the stretching treatment, a known stretching method that has been conventionally performed with polyolefin or the like can be used. That is, a small amount of stretching is performed at a temperature within a range from low temperature to normal temperature to whiten and cleave, and subsequently, expansion of the hole and stabilization of the hole shape are achieved by heat stretching. In these stretching processes, the intermediate layer is also stretched at the same time. In this case, the intermediate layer must not be broken by stretching.
[0021]
In the present invention, it is preferable to dry a polymer such as a pellet as a pretreatment before performing the spinning step. For example, when using a hygroscopic polymer such as a polyurethane polymer, moisture in the polymer to be used is removed if the hygroscopic polymer pellets are dried, thus further suppressing foaming during spinning. Can do. Examples of the drying method include vacuum drying.
[0022]
Furthermore, it is preferable to replace the inside of the polymer supply system to the nozzle with dry nitrogen after the charging of the polymer and before discharging. For example, after the hygroscopic polymer pellets are put into the hopper of the discharge device, if the inside of the hopper is replaced with dry nitrogen, the water in the supplied polymer is removed, so foaming during spinning is further suppressed. Can do.
[0023]
【Example】
<Example 1>
In this example, pellets of segmented polyurethane [Thermedics, trade name Tecoflex EG80A, water absorption 0.72% (65% RH, 20 ° C. × 24 hr)] as a hygroscopic polymer for the intermediate layer, for the support layer As water-repellent polymer, pellets of high-density polyethylene (trade name Hizex 2200J, manufactured by Sumitomo Mitsui Polyolefin Co., Ltd.) were prepared. Since segmented polyurethane is a hygroscopic polymer, it was dried at 60 ° C. for 8 hours or more in a vacuum dryer before spinning.
[0024]
These pellets were put into a hopper of a spinning device to form a closed system, and the inside of the system was purged with dry nitrogen. The spinning nozzle of this spinning device is formed with an innermost layer, an intermediate layer, an outermost layer, and triple annular discharge ports arranged concentrically.
[0025]
First, the polymer for the intermediate layer was discharged at 165 ° C. from the discharge port for the intermediate layer of this spinning nozzle. At the time of discharge, a very small amount of gear pump (0.05 cc / rev) was used, and the pump was pushed out at the maximum gear pump speed (about 40 rpm).
[0026]
At the initial stage of discharge, it was visually confirmed that bubbles were contained in the polymer. When the discharge was continued as it was, it was confirmed that there were no bubbles about 90 minutes after the start of the discharge. At this time, the polymer for the support layer was discharged at 165 ° C. from the discharge port for the innermost layer and the discharge port for the outermost layer of the spinning nozzle. The discharged extruded fibers having a three-layer structure were cooled and solidified by passing through a cooling air section, and this was wound at a spinning speed of 170 m / min to obtain an undrawn yarn having a three-layer structure.
[0027]
This undrawn yarn is subjected to annealing treatment, cold drawing, and hot drawing heat setting that have been conventionally performed, so that gas separation between the porous support layers (innermost layer and outermost layer) is possible. A three-layer composite hollow fiber membrane having a structure in which a porous ultrathin layer (intermediate layer) was sandwiched was obtained. The three-layer composite hollow fiber membrane had an inner diameter of 200 μm, an innermost layer thickness of 20 μm, an intermediate layer thickness of 1 μm, and an outermost layer thickness of 20 μm.
[0028]
When the gas permeation performance (permeation rate [O 2 Flux], separation factor [α]) of this three-layer composite hollow fiber membrane was measured, numerical values supporting that there was no problem in the physical properties of the intermediate layer polymer from the beginning to the end of spinning [ O 2 Flux = 0.28 m 3 / m 2 · hr · MPa, α (O 2 / N 2 ) = 2.7], and it was a normal film free from micro defects such as microvoids.
[0029]
<Comparative Example 1>
A three-layer composite hollow fiber membrane was produced in the same manner as in Example 1 except that the polymer for the intermediate layer and the support layer were simultaneously discharged when the polymer was discharged. Of these three-layer composite hollow fiber membranes, the initial spun product has a high gas permeation performance, a high permeation rate, a low separation factor, an inadequate gas separation performance, and a nonstandard defective product. Met. This is presumably due to microvoid defects due to the inclusion of bubbles in the intermediate layer. For the spun product at a later time than the initial spun product, the permeation performance gradually returned to a normal value as the spinning duration time passed.
[0030]
<Reference Example 1>
A three-layer composite hollow fiber membrane was produced in the same manner as in Example 1 except that the intermediate layer polymer pellets were put into a hopper without vacuum drying before spinning. The gas permeation performance of this three-layer composite hollow fiber membrane is high in permeation speed from the beginning of spinning to the end, the separation factor is lowered, does not have proper gas separation performance, and is a non-standard defective product. It was. This is presumably due to microvoid defects due to the inclusion of bubbles in the intermediate layer.
[0031]
<Reference Example 2>
A three-layer composite hollow fiber membrane was produced in the same manner as in Example 1 except that vacuum-dried intermediate layer polymer pellets were put into a hopper and dry nitrogen was not purged. The gas permeation performance of this three-layer composite hollow fiber membrane is high from the beginning of spinning to the end, the permeation rate is high, the separation factor is low, it does not have proper gas separation performance, and it is a non-standard defective product. there were. This is presumably due to microvoid defects due to the inclusion of bubbles in the intermediate layer.
[0032]
【The invention's effect】
As described above, according to the present invention, it is possible to produce a three-layer composite hollow fiber membrane having no defects in the intermediate layer and exhibiting a good gas separation function with a high yield.
Claims (4)
中間層用のポリマーの吐出を先に開始し、その後、支持層用のポリマーの吐出を開始することを特徴とする三層複合中空糸膜の製造方法。In the method for producing a three-layer composite hollow fiber membrane having a step of discharging and spinning a molten polymer from a nozzle,
A method for producing a three-layer composite hollow fiber membrane, wherein the discharge of the polymer for the intermediate layer is started first, and then the discharge of the polymer for the support layer is started.
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