JP2009226397A - Hollow fiber membrane for humidification and membrane module for humidification - Google Patents

Hollow fiber membrane for humidification and membrane module for humidification Download PDF

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JP2009226397A
JP2009226397A JP2009041906A JP2009041906A JP2009226397A JP 2009226397 A JP2009226397 A JP 2009226397A JP 2009041906 A JP2009041906 A JP 2009041906A JP 2009041906 A JP2009041906 A JP 2009041906A JP 2009226397 A JP2009226397 A JP 2009226397A
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hollow fiber
fiber membrane
humidifying
membrane
humidification
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Masahiro Osabe
真博 長部
Hiroyuki Sugaya
博之 菅谷
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Toray Industries Inc
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Toray Industries Inc
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hollow fiber membrane for humidification, which has a humidification performance (steam permeability) as well and has a small air leakage amount, as the hollow fiber membrane for the humidification. <P>SOLUTION: By controlling the growing speed of a membrane hole diameter (phase separation speed), when a membrane structure in a cross sectional direction vertical to the longitudinal direction of the hollow fiber membrane is observed at the magnification of 1,000 times using an electron microscope, the hollow fiber membrane for the humidification has a finger void structure, the steam permeation coefficient is ≥0.4 g/min/cm<SP>2</SP>/MPa, and the air leakage amount is ≤0.1 L/min. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明は、加湿用中空糸膜および加湿用膜モジュールに関するものである。さらに詳しくは、燃料電池自動車などに使用される加湿装置に好適に用いられる加湿用中空糸膜および加湿用膜モジュールに関するものである。   The present invention relates to a humidifying hollow fiber membrane and a humidifying membrane module. More specifically, the present invention relates to a humidifying hollow fiber membrane and a humidifying membrane module that are preferably used in a humidifying device used in a fuel cell vehicle or the like.

近年、加湿用膜を用いて加湿を行う方法、さらに加湿用中空糸膜を用いて加湿を行う方法が注目されている。加湿用中空糸膜を用いた加湿方式は、メンテナンスフリーであるばかりではなく、従来のバブリングを用いた加湿方式のような駆動に電源を必要としないなどの多くの利点を有している。   In recent years, attention has been focused on a method of performing humidification using a humidifying membrane and a method of performing humidification using a humidifying hollow fiber membrane. The humidification method using the humidifying hollow fiber membrane is not only maintenance-free, but also has many advantages such as not requiring a power source for driving like the conventional humidification method using bubbling.

加湿用中空糸膜は、燃料電池スタックの隔膜加湿等に用いられるが、燃料電池の場合、車載用では４０００ＮＬ／分程度の多量の空気流量に対しての加湿が必要であるため、水蒸気透過性が高いことが求められている。また、定置用では加湿の駆動源に温水が使用される場合が多く、加湿用中空糸膜への耐久性と耐熱性の付与が特に必要とされている。実際に、固体高分子型燃料電池の場合、実稼動温度は約６０〜９０℃で水蒸気飽和状態での雰囲気となる。   The humidifying hollow fiber membrane is used for membrane humidification of a fuel cell stack. However, in the case of a fuel cell, since it is necessary to humidify a large amount of air flow of about 4000 NL / min in a vehicle, water vapor permeability is required. Is required to be high. Further, in the case of stationary use, warm water is often used as a driving source for humidification, and it is particularly necessary to impart durability and heat resistance to the humidifying hollow fiber membrane. Actually, in the case of a polymer electrolyte fuel cell, the actual operating temperature is about 60 to 90 ° C., and the atmosphere is in a steam saturated state.

水蒸気を選択的に透過させる加湿用中空糸膜として、現在数種類のものが特許文献などで知られている。加湿用中空糸膜として、上記の必要特性に加え、これらは中空糸膜の内側中空部から中空糸外部へのエアリークを防ぐため、中空糸膜としてガスバリア性が必要でありながら、水蒸気透過性を有しておらねばならず、非常に微細な孔径にし、加圧することによって所望の水蒸気透過量を得ようとするものであった。   Several types of humidifying hollow fiber membranes that allow water vapor to permeate selectively are currently known in patent literature. As a humidifying hollow fiber membrane, in addition to the above-mentioned required characteristics, in order to prevent air leakage from the hollow inside of the hollow fiber membrane to the outside of the hollow fiber, the hollow fiber membrane has a gas barrier property while requiring a gas barrier property. In order to obtain a desired water vapor permeation amount, the pore diameter must be very fine and pressurized.

加湿用中空糸膜として多種のポリマーを用いた膜が開発されている。一例として、ポリイミド樹脂を素材として用いた加湿用中空糸膜がある。該膜の特徴としては、耐熱性、耐久性およびガスバリア性にはすぐれているが、水蒸気透過性が低いという欠点がみられる。   Membranes using various polymers have been developed as humidifying hollow fiber membranes. As an example, there is a humidifying hollow fiber membrane using a polyimide resin as a material. The film has excellent heat resistance, durability, and gas barrier properties, but has a drawback of low water vapor permeability.

また、フッ素系イオン交換膜を用いた加湿用膜は、ポリイミド樹脂を素材とした加湿用中空糸膜よりは水蒸気透過性、ガスバリア性は高いものの、加湿用中空糸膜として実際に使用する程の水蒸気透過性が備わっておらず、さらに耐熱性にも乏しい。中空糸膜自体も非常に高価なものとなってしまう。   In addition, the humidifying membrane using a fluorine-based ion exchange membrane has higher water vapor permeability and gas barrier properties than the humidifying hollow fiber membrane made of polyimide resin, but it is actually used as a humidifying hollow fiber membrane. It does not have water vapor permeability and has poor heat resistance. The hollow fiber membrane itself is very expensive.

近年、ポリエーテルイミド樹脂を素材とした加湿用中空糸膜が報告されており、フッ素系イオン交換膜と同等の水蒸気透過性、さらに耐熱性の両立が図られてきているが、いずれにせよ、現状の加湿用中空糸膜では、ガスバリア性を重視した結果、本来の加湿用膜に必要な加湿性能は不十分であった。   In recent years, a hollow fiber membrane for humidification made of polyetherimide resin has been reported, and water vapor permeability equivalent to that of a fluorine-based ion exchange membrane and further heat resistance have been achieved, but in any case, In the present humidifying hollow fiber membrane, as a result of emphasizing the gas barrier property, the humidifying performance necessary for the original humidifying membrane was insufficient.

膜素材としては、ポリフェニルスルホン樹脂および親水性ポリビニルピロリドンの水溶性有機溶媒溶液よりなる紡糸原液を用い、Ｎ−メチル−２−ピロリドン水溶液を芯液として乾湿式紡糸し、多孔質ポリフェニルスルホン樹脂中空糸膜を得る方法は、既に提案されている。しかし、ここで得られた中空糸膜は油水分離用限外ロ過膜等に好適に使用されると述べられており、水蒸気透過を目的とするものではなかった。（特許文献１）
また、ポリフェニルスルホン系の加湿用中空糸膜が提案されているが十分な加湿性能が得られなかった（特許文献２）。 As a membrane material, a spinning stock solution comprising a polyphenylsulfone resin and a water-soluble organic solvent solution of hydrophilic polyvinyl pyrrolidone is used, and a wet polysulphone resin is obtained by spin-drying with an N-methyl-2-pyrrolidone aqueous solution as a core solution. A method for obtaining a hollow fiber membrane has already been proposed. However, it has been stated that the hollow fiber membrane obtained here is suitably used for an ultrafiltration membrane for oil-water separation and the like, and was not intended for water vapor permeation. (Patent Document 1)
Further, a polyphenylsulfone-based humidifying hollow fiber membrane has been proposed, but sufficient humidifying performance was not obtained (Patent Document 2).

また、ポリスルホン系の加湿用中空糸膜として非対称構造の中空糸膜も知られているが、非対称膜では水蒸気が透過（拡散）する場合の膜抵抗が大きく、十分な加湿性能が得られなかった（特許文献３）。   A hollow fiber membrane with an asymmetric structure is also known as a polysulfone-based humidifying hollow fiber membrane, but the asymmetric membrane has a large membrane resistance when water vapor permeates (diffuses), and sufficient humidification performance cannot be obtained. (Patent Document 3).

特開２００１−２１９０４３号公報JP 2001-219043 A 特開２００４−２９０７５１号公報Japanese Patent Application Laid-Open No. 2004-290751 特開２００７−２８９９４４号公報JP 2007-289944 A

本発明の目的は、加湿用中空糸膜において、加湿性能（水蒸気透過性）を兼ね備え、空気漏洩量の少ない加湿用中空糸膜を提供するものである。   An object of the present invention is to provide a humidifying hollow fiber membrane that has a humidifying performance (water vapor permeability) and has a small amount of air leakage in the humidifying hollow fiber membrane.

本発明の課題は、以下の手段によって解決される。
１．電子顕微鏡を用いて、中空糸膜の長手に垂直な断面方向の膜構造を、１０００倍の倍率で観察を行った時に、フィンガーボイド構造を有し、水蒸気透過係数が０．４ｇ／ｍｉｎ／ｃｍ２／ＭＰａ以上であり、空気漏洩量が０．１Ｌ／ｍｉｎ以下である加湿用中空糸膜。
２．面積９５００μｍ２あたりに、フィンガーボイドが２つ以上ある１記載の加湿用中空糸膜。
３．該加湿用中空糸膜の内径が３００μｍ以上１５００μｍ以下、膜厚が５０μｍ以上２００μｍ以下である１または２に記載の加湿用中空糸膜。
４．該加湿用中空糸膜がポリスルホンを含む１〜３のいずれかに記載の加湿用中空糸膜。
５．該加湿用中空糸膜が親水性高分子を含む１〜４のいずれかに記載の加湿用中空糸膜。
６．該親水性高分子がポリビニルピロリドンであり、該ポリビニルピロリドンの分子量が４０００００以下である５に記載の加湿用膜。
７．該ポリビニルピロリドンがポリスルホンに対して３０〜７０重量％である５に記載の加湿用膜。
８．１〜７のいずれかに記載の加湿用中空糸膜を内蔵した加湿用膜モジュール。 The problems of the present invention are solved by the following means.
1. When the membrane structure in the cross-sectional direction perpendicular to the length of the hollow fiber membrane is observed at an magnification of 1000 times using an electron microscope, it has a finger void structure and a water vapor transmission coefficient of 0.4 g / min / cm. A humidifying hollow fiber membrane having a rate of 2 / MPa or more and an air leakage amount of 0.1 L / min or less.
2. 2. The humidifying hollow fiber membrane according to 1, wherein there are two or more finger voids per area of 9500 μm 2 .
3. 3. The humidifying hollow fiber membrane according to 1 or 2, wherein the humidifying hollow fiber membrane has an inner diameter of 300 μm to 1500 μm and a film thickness of 50 μm to 200 μm.
4). The humidifying hollow fiber membrane according to any one of 1 to 3, wherein the humidifying hollow fiber membrane contains polysulfone.
5. The humidifying hollow fiber membrane according to any one of 1 to 4, wherein the humidifying hollow fiber membrane contains a hydrophilic polymer.
6). The humidifying membrane according to 5, wherein the hydrophilic polymer is polyvinylpyrrolidone, and the molecular weight of the polyvinylpyrrolidone is 400,000 or less.
7). 6. The humidifying membrane according to 5, wherein the polyvinyl pyrrolidone is 30 to 70% by weight based on polysulfone.
A humidifying membrane module including the humidifying hollow fiber membrane according to any one of 8.1 to 7.

本発明により得られる加湿用中空糸膜は、加湿性能（水蒸気透過性）を兼ね備え、空気漏洩量の少ない加湿用中空糸膜として有効に使用することができる。   The humidifying hollow fiber membrane obtained by the present invention has a humidifying performance (water vapor permeability) and can be effectively used as a humidifying hollow fiber membrane with a small amount of air leakage.

フィンガーボイドの縦横比の測定方法の例を示す図である。It is a figure which shows the example of the measuring method of the aspect ratio of a finger void. 加湿用中空糸膜の壁厚中央部に空隙部分が存在する中空糸の断面（全体）である。It is the cross section (whole) of the hollow fiber in which a space | gap part exists in the wall thickness center part of the hollow fiber membrane for humidification. 加湿用中空糸膜の壁厚中央部に空隙部分が存在する中空糸の断面（拡大）である。It is a cross section (enlargement) of the hollow fiber in which a void portion exists in the central portion of the wall thickness of the humidifying hollow fiber membrane. 水蒸気透過性能を測定する方法である。This is a method for measuring water vapor transmission performance. 空気漏洩量を測定する方法である。This is a method for measuring the amount of air leakage. 加湿用中空糸膜の壁厚中央部に空隙部分が存在しない非対称構造の中空糸の断面（拡大）である。It is a cross section (expansion) of the hollow fiber of the asymmetrical structure in which a space | gap part does not exist in the wall thickness center part of the hollow fiber membrane for humidification.

本発明の加湿用中空糸膜は、電子顕微鏡を用いて中空糸膜の長手に垂直な断面方向の膜構造を１０００倍の倍率で観察を行った時に、フィンガーボイド構造を有することが必須である。フィンガーボイドとは、人が拇印を押した跡の様な孔のことを示し、詳しくは、上記観察を行った際に、内表面部分および外表面部分の最も大きな空隙部分の面積（中空糸膜の長手に垂直な断面写真の空隙部分最大長を直径とした時の円面積）と比べて１０倍以上の面積の空隙が存在する孔のこととする。さらにこのフィンガーボイドを持っている中空糸膜構造をフィンガーボイド構造とする。   The humidifying hollow fiber membrane of the present invention must have a finger void structure when the membrane structure in the cross-sectional direction perpendicular to the length of the hollow fiber membrane is observed at a magnification of 1000 times using an electron microscope. . Finger void means a hole like a mark that a person has pressed a thumbprint. Specifically, when the above observation is made, the area of the largest void portion of the inner surface portion and the outer surface portion (hollow fiber membrane) It is assumed that the hole has a void having an area of 10 times or more compared to the circular area when the maximum length of the void portion in the cross-sectional photograph perpendicular to the length is taken as the diameter. Furthermore, let the hollow fiber membrane structure which has this finger void be a finger void structure.

フィンガーボイドの形状としては、例えば図１に示すように、一つのフィンガーボイドを内表面から外表面に向かって２分割した線をＸ軸１０とし、この時のＸ軸の長さと、Ｘ軸に対して垂線を引いたＹ軸２０の長さが、Ｙ軸に対してＸ軸の長さが、１．１倍以上が好ましく、１．５倍以上がさらに好ましい。   As the shape of the finger void, for example, as shown in FIG. 1, a line obtained by dividing one finger void into two from the inner surface to the outer surface is defined as the X axis 10, and the length of the X axis at this time and the X axis On the other hand, the length of the Y axis 20 with a perpendicular line drawn is preferably 1.1 times or more, and more preferably 1.5 times or more, with respect to the Y axis.

加湿用中空糸膜の横手断面の膜構造としては、内表面から外表面、もしくは外表面から内表面へと順次膜孔径が大きくなる非対称構造では、水蒸気の透過（拡散）抵抗が大きくなり、水蒸気透過性は低下する。さらに、内表面から外表面へ同じ膜孔径の対象構造（均質膜）に関しては選択透過性（空気遮断性）が低く、水蒸気透過性と空気遮断性を兼ね揃えることは困難である。本発明の加湿用中空糸膜は、（最内表面部分と最外表面部分はフィンガーボイド部分と比べて孔経が小さく、中央部分のフィンガーボイド構造を有することで、水蒸気透過性と空気遮断性を兼ね揃えるものである。   As the membrane structure of the transverse cross section of the humidifying hollow fiber membrane, the permeation (diffusion) resistance of water vapor increases in the asymmetric structure in which the membrane pore diameter increases sequentially from the inner surface to the outer surface or from the outer surface to the inner surface. Permeability decreases. Further, the target structure (homogeneous membrane) having the same membrane pore diameter from the inner surface to the outer surface has low selective permeability (air barrier property), and it is difficult to achieve both water vapor permeability and air barrier property. The humidifying hollow fiber membrane of the present invention is (the innermost surface portion and the outermost surface portion have a smaller diameter than the finger void portion, and has a finger void structure in the central portion, so that water vapor permeability and air barrier properties are achieved. It is a thing that serves as both.

加湿用中空糸膜の横手断面のフィンガーボイド数としては、電子顕微鏡の倍率１０００倍で観察し、観察視野の９５００μｍ２あたりに、２個以上あることが好ましく、さらに、４個以上がより好ましい。フィンガーボイドが２個未満の場合は、中空糸膜製膜時のフィンガーボイド構造の特徴である、水蒸気透過性の向上を期待できなくなる場合がある。 The number of finger voids in the transverse cross section of the humidifying hollow fiber membrane is preferably 2 or more, more preferably 4 or more per 9500 μm 2 of the observation field when observed with an electron microscope magnification of 1000 times. When the number of finger voids is less than 2, it may not be possible to expect an improvement in water vapor permeability, which is a feature of the finger void structure at the time of hollow fiber membrane formation.

中空糸膜の加湿性能、すなわち水蒸気透過性能は中空糸の中空部に線速１０００ｃｍ／ｓｅｃの空気を流したときの加湿性能が０．４ｇ／ｍｉｎ／ｃｍ２／ＭＰａ以上であることが必要である。この０．４ｇ／ｍｉｎ／ｃｍ２／ＭＰａ以上の加湿性能だと、燃料電池スタックに最適な加湿を行うことができ、安定して水と酸素を供給する事が可能である。一方、０．４ｇ／ｍｉｎ／ｃｍ２／ＭＰａ未満であると、燃料電池スタックに十分な加湿を行うことができず、スタックの電解質膜性能を十分発揮できない。 The humidification performance of the hollow fiber membrane, that is, the water vapor transmission performance, is required to be 0.4 g / min / cm 2 / MPa or more when the air at a linear speed of 1000 cm / sec is passed through the hollow portion of the hollow fiber. is there. When the humidification performance is 0.4 g / min / cm 2 / MPa or more, it is possible to optimally humidify the fuel cell stack, and it is possible to stably supply water and oxygen. On the other hand, when it is less than 0.4 g / min / cm 2 / MPa, the fuel cell stack cannot be sufficiently humidified, and the electrolyte membrane performance of the stack cannot be sufficiently exhibited.

さらに、中空糸膜１本辺りの空気漏洩量は５０ｋＰａの空気を中空糸膜中空部から外に５０ｋＰａの圧力をかけたときに０．１Ｌ／ｍｉｎ以下であることが必要である。これは、中空糸膜の内側から外側、もしくは外側から内側に空気を流したときの空気漏洩量で、０．１Ｌ／ｍｉｎを超える場合には空気を加湿するにあたり、乾燥空気が混合してしまうため、実質的に加湿性能が低下することになる。   Furthermore, the amount of air leakage per hollow fiber membrane needs to be 0.1 L / min or less when 50 kPa of air is applied with a pressure of 50 kPa from the hollow portion of the hollow fiber membrane. This is the amount of air leakage when air flows from the inside to the outside of the hollow fiber membrane, or from the outside to the inside. If it exceeds 0.1 L / min, dry air will be mixed when humidifying the air Therefore, the humidification performance is substantially reduced.

中空糸膜の糸径に関しては中空糸膜内径が３００μｍ以上、１５００μｍ以下であることが好ましい。３００μｍ未満の場合は、高流量の空気を流したときに空気入りから出にかけての圧力が上昇し、中空糸膜切れが起こる場合がある。一方、１５００μｍを超える場合は、中空糸膜モジュールにした時、空気の流れが偏って、中空糸膜を有効に使用できない場合がある。その為、中空糸膜内径は３００μｍ以上、１５００μｍ以下であることが好ましい。   Regarding the yarn diameter of the hollow fiber membrane, the inner diameter of the hollow fiber membrane is preferably 300 μm or more and 1500 μm or less. In the case of less than 300 μm, when a high flow rate of air is flowed, the pressure from entry to exit increases, and the hollow fiber membrane may be broken. On the other hand, when it exceeds 1500 μm, when a hollow fiber membrane module is used, the air flow is uneven and the hollow fiber membrane may not be used effectively. Therefore, the inner diameter of the hollow fiber membrane is preferably 300 μm or more and 1500 μm or less.

中空糸膜厚は５０μｍ以上、２００μｍ以下であることが好ましい。５０μｍ以下の場合は、中空糸膜断面の中央部に空隙部分が存在するため中空糸膜の破断強力が低下し、高空気流量を与えた時に中空糸膜切れが起こる場合がある。２００μｍを超える場合は、中空糸膜の製膜時の構造制御安定性に欠け、中空糸空隙部分の製膜再現性が乏しくなる場合がある。   The hollow fiber film thickness is preferably 50 μm or more and 200 μm or less. In the case of 50 μm or less, since the void portion exists in the center of the cross section of the hollow fiber membrane, the breaking strength of the hollow fiber membrane is lowered, and the hollow fiber membrane may be broken when a high air flow rate is applied. When it exceeds 200 μm, the structure control stability at the time of forming the hollow fiber membrane is lacking, and the film formation reproducibility of the hollow fiber gap portion may be poor.

本発明の加湿用膜を構成する材料は特に限定されるものではないが、ポリアミド、ポリイミド、ポリフェニルエーテル、ポリスルホン等があげられ、中でもポリスルホンが好ましい。これは、ポリマー耐熱性考慮した結果と、エンプラとして使用させるポリスルホンは比較的安価で購入することが可能なポリマーであり、汎用性が高いポリマーであるため実用化に向いている。   The material constituting the humidifying membrane of the present invention is not particularly limited, and examples thereof include polyamide, polyimide, polyphenyl ether, polysulfone, etc. Among them, polysulfone is preferable. This is the result of considering the heat resistance of the polymer, and the polysulfone used as the engineering plastic is a polymer that can be purchased at a relatively low cost, and is suitable for practical use because it is a highly versatile polymer.

本発明のフィンガーボイド構造は膜孔径が成長する速度（相分離速度）をコントロールすることで設けることができる。具体的には、製膜時のポリマー原液の濃度、製膜時の製膜温度を変更し口金吐出時のポリマーの流動性（粘度）を高くする方法や、注入液の溶媒の比率を少なくすることが重要である。また同じポリマーを使用したとしても、ポリマーの分子量、添加量によってもポリマー粘度が異なってくるので、原液設計が重要である。   The finger void structure of the present invention can be provided by controlling the rate at which the pore size grows (phase separation rate). Specifically, the concentration of the polymer stock solution during film formation and the film formation temperature during film formation are changed to increase the fluidity (viscosity) of the polymer during discharge of the die, and the solvent ratio of the injection solution is reduced. This is very important. Even if the same polymer is used, since the polymer viscosity varies depending on the molecular weight and addition amount of the polymer, the stock solution design is important.

本発明の加湿用膜には親水性高分子が含まれていることが好ましい。親水性高分子としては、ポリアルキレンオキサイド、ポリビニルアルコール、ポリエチレングリコール、ポリビニルピロリドン等があげられ、この中でも、ガラス転移点が１５０℃よりも高い親水性高分子が加湿用膜としての耐熱性が優れているため用いられる。例に挙げたポリビニルピロリドンはガラス転移点が１８０℃と高いため加湿用膜用途として好ましい。   The humidifying membrane of the present invention preferably contains a hydrophilic polymer. Examples of the hydrophilic polymer include polyalkylene oxide, polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, etc. Among them, a hydrophilic polymer having a glass transition point higher than 150 ° C. has excellent heat resistance as a humidifying film. Because it is used. The polyvinyl pyrrolidone mentioned as an example is preferable as a film for humidification because of its high glass transition point of 180 ° C.

親水性高分子物質として添加されるポリビニルピロリドンとしては、重量平均分子量が約１００００（Ｋ−１５相当）〜１２０００００（Ｋ−９０相当）の物が存在し、好ましくはポリスルホン系樹脂１００重量％当り２０〜１００重量％、より好ましくは３０〜７０重量％の割合で用いられる。ポリスルホン樹脂に対して２０重量％よりも少ない場合は、親水性を付与することができず、水蒸気との親和性が低く加湿用途として向いていない場合がある。１００重量％を超える場合は、中空糸膜強度が低く、製膜困難になる場合がある。また、フィンガーボイド構造の形成を妨げる場合もある。   The polyvinyl pyrrolidone added as the hydrophilic polymer substance has a weight average molecular weight of about 10,000 (equivalent to K-15) to 1200000 (equivalent to K-90), preferably 20 per 100% by weight of the polysulfone resin. -100% by weight, more preferably 30-70% by weight. When the amount is less than 20% by weight with respect to the polysulfone resin, hydrophilicity cannot be imparted, and the affinity with water vapor is low, which may not be suitable for humidification. When it exceeds 100% by weight, the strength of the hollow fiber membrane is low, and it may be difficult to form the membrane. Moreover, formation of a finger void structure may be prevented.

中空糸膜の膜厚中央部に空隙部分を存在させる為には、重量平均分子量１００００〜４０００００のポリビニルピロリドンを用いることが好ましい。重量平均分子量１０００よりも小さい場合は親和性に乏しい中空糸膜となり、重量平均分子量４０００００を超える場合は、中空糸膜構造が非対称又は均質構造になり、フィンガーボイド構造の形成を妨げ、加湿性能が乏しくなる場合がある。場合によっては２種類以上の異なった分子量のポリビニルピロリドンを用いてもかまわない。   In order to make a void part exist in the film thickness center part of the hollow fiber membrane, it is preferable to use polyvinylpyrrolidone having a weight average molecular weight of 10,000 to 400,000. When the weight average molecular weight is less than 1000, the hollow fiber membrane has poor affinity, and when the weight average molecular weight exceeds 400000, the hollow fiber membrane structure is asymmetric or homogeneous, preventing the formation of a finger void structure, and humidifying performance is reduced. It may become scarce. In some cases, two or more different molecular weight polyvinylpyrrolidones may be used.

本発明の加湿用中空糸膜は具体的には以下のように作製されるが、これに限定されるものではない。   The humidifying hollow fiber membrane of the present invention is specifically produced as follows, but is not limited thereto.

本発明の加湿用中空糸膜は、オリフィス型二重円筒型口金から製膜原液と芯液を吐出させて、中空糸状に製膜を行う工程、温水で洗浄する工程、洗浄後に巻き取る工程を有する加湿用膜の製造方法で作製される。さらに巻き取る工程の後に乾熱乾燥機を用いて、４０℃以上１７０℃以下で３０分以上乾燥させる工程を有することが好ましい。   The humidifying hollow fiber membrane of the present invention comprises a step of forming a hollow fiber-like film by discharging a film-forming stock solution and a core solution from an orifice-type double cylindrical die, a step of washing with warm water, and a step of winding after washing. It is produced by a method for producing a humidifying film. Furthermore, it is preferable to have the process of drying at 40 degreeC or more and 170 degrees C or less for 30 minutes or more using a dry-heat dryer after the winding process.

本発明の加湿用中空糸膜はポリスルホンを用いて作製することができ、ポリスルホン中空糸膜を例として説明する。本発明で使用するポリスルホンは市販品をそのまま使用することができる。例えばソルベー社製品ＵＤＥＬ Ｐ１７００またはＰ３５００等が例に挙げられる。   The humidifying hollow fiber membrane of the present invention can be produced using polysulfone, and the polysulfone hollow fiber membrane will be described as an example. As the polysulfone used in the present invention, a commercially available product can be used as it is. For example, Solvay product UDEL P1700 or P3500 is an example.

ポリスルホン樹脂を製膜成分とする製膜原液は、ポリスルホン樹脂に親水性ポリビニルピロリドン、水溶性有機溶媒および水が添加されることで得られる。   A film-forming stock solution containing a polysulfone resin as a film-forming component can be obtained by adding hydrophilic polyvinylpyrrolidone, a water-soluble organic solvent and water to the polysulfone resin.

水溶性有機溶媒としては、ジメチルホルムアミド、ジメチルアセトアミド、Ｎ−メチル−２−ピロリドン等の非プロトン性極性溶媒が用いられる。   As the water-soluble organic solvent, an aprotic polar solvent such as dimethylformamide, dimethylacetamide, or N-methyl-2-pyrrolidone is used.

ポリスルホン系樹脂は、製膜原液中約１０〜２５重量％、好ましくは約１５〜２０重量％の濃度で用いられることが好ましい。ポリスルホン濃度が１０重量％の場合は中空糸膜の強度不足により製膜が困難となり、２５重量％以上だとポリスルホン中のサイクリックダイマーにより、製膜原液が白濁し製膜中に圧力上昇が起こる。この現象によって製膜困難な状況になる場合がある。さらに、このような濃度範囲より少なくてもあるいは多くても、所望の孔径を有する中空糸膜は得られない場合がある。   The polysulfone-based resin is preferably used at a concentration of about 10 to 25% by weight, preferably about 15 to 20% by weight, in the membrane forming stock solution. When the polysulfone concentration is 10% by weight, film formation becomes difficult due to insufficient strength of the hollow fiber membrane. When the polysulfone concentration is 25% by weight or more, the cyclic dimer in the polysulfone causes the membrane forming stock solution to become cloudy and the pressure rises during film formation. . This phenomenon may make it difficult to form a film. Furthermore, a hollow fiber membrane having a desired pore size may not be obtained if the concentration range is less than or greater than this range.

次に、製膜原液をオリフィス型二重円筒型口金の外側の管より吐出する。この時、芯液としてポリスルホンに対しての良溶媒と貧溶媒の混合液、もしくはポリスルホンに対しての貧溶媒の単独液を内側の管より吐出することで、中空糸型に成型する。   Next, the film-forming stock solution is discharged from a tube outside the orifice-type double cylindrical die. At this time, as a core solution, a mixture of a good solvent and a poor solvent for polysulfone, or a single solution of a poor solvent for polysulfone is discharged from the inner tube to form a hollow fiber mold.

吐出された製膜原液を、温度３０℃の雰囲気の乾式部３５０ｍｍを通過した後、凝固溶液中で凝固させる。凝固させた中空糸膜は４０〜９０℃の温水で洗浄され、巻き取られる。４０℃以下の洗浄では有機溶媒等の洗浄が不十分になり、中空糸膜からの溶出物が加湿時に影響を及ぼす場合があり、９０℃以上では、親水性高分子を必要以上に洗浄してしまうため中空糸膜の親水性が低くなる場合がある。   The discharged film forming stock solution passes through a dry part 350 mm in an atmosphere at a temperature of 30 ° C., and is then solidified in a coagulating solution. The coagulated hollow fiber membrane is washed with warm water of 40 to 90 ° C. and wound up. Washing at 40 ° C. or lower may cause insufficient washing of organic solvents, etc., and the eluate from the hollow fiber membrane may affect the humidification. At 90 ° C. or higher, the hydrophilic polymer is washed more than necessary. Therefore, the hydrophilicity of the hollow fiber membrane may be lowered.

次いで、この巻き取った湿潤状態の膜束を、所望の孔径に熱セットするために乾燥処理を行うことで、本発明の加湿用中空糸膜が得られる。熱セットとは、湿潤状態の加湿用膜を乾燥させることにより、膜孔径を縮めるものであり、この処理後、中空糸膜の保湿（グリセリン付与、もしくは水充填）は不必要になる。   Subsequently, the humidified hollow fiber membrane of the present invention is obtained by performing a drying process to heat-set the wound membrane bundle thus wound up to a desired pore size. In the heat setting, the membrane pore diameter is reduced by drying the humidified membrane, and after this treatment, the moisture retention (glycerin provision or water filling) of the hollow fiber membrane is unnecessary.

本加湿用中空糸膜の乾燥処理方法として、数百本から数千本に小分けし、４０℃以上１７０℃以下の乾熱乾燥機で３０分以上乾燥することが好ましく、５０℃以上がより好ましく、１５０℃以下がより好ましい。４０℃より低い温度による乾燥では、乾燥時に時間がかかることと、外部雰囲気によっては温度コントロールが困難になり中空糸膜孔径を制御できない場合がある。１７０℃以上の温度に上げると、ポリスルホンを用いた場合に、そのガラス転移点に近づくため、加湿用膜に損傷を与えてしまう場合がある。乾燥時間は３０分以上が好ましく、さらには５時間以上が好ましい。乾燥時間の上限は特には設けないが作業効率より、７２時間以内であることが好ましい。３０分より少ない時間での乾燥は中空糸膜の水分を飛ばしきることができず、中空糸膜孔径が不安定な状態となり、空気漏洩量が増加する場合がある。   As the method for drying the humidifying hollow fiber membrane, it is preferably subdivided into hundreds to thousands and dried in a dry heat dryer at 40 ° C. or higher and 170 ° C. or lower for 30 minutes or more, more preferably 50 ° C. or higher. 150 ° C. or lower is more preferable. When drying at a temperature lower than 40 ° C., it may take time during drying, and depending on the external atmosphere, temperature control may be difficult and the hollow fiber membrane pore diameter may not be controlled. When the temperature is raised to 170 ° C. or higher, when the polysulfone is used, the glass transition point is approached, so that the humidifying membrane may be damaged. The drying time is preferably 30 minutes or longer, and more preferably 5 hours or longer. The upper limit of the drying time is not particularly set, but is preferably within 72 hours from the viewpoint of work efficiency. If the drying time is less than 30 minutes, the water content of the hollow fiber membrane cannot be exhausted, the hollow fiber membrane pore diameter becomes unstable, and the amount of air leakage may increase.

次に実施例について本発明を説明する。   Next, the present invention will be described with reference to examples.

（１）中空糸膜の空隙部観察
製膜した中空糸膜１本の中空糸膜の長手に垂直な断面方向の膜構造を電子顕微鏡で１０００倍の倍率で観察を行った。図２、図３に空隙部分の写真の例を示す。この時、内表面近傍５０と外表面近傍３０の空隙部分よりも中央部の空隙部分４０が大きいかどうかや、フィンガーボイド構造の有無を確認した。図６に中央部に空隙部分が存在しない非対称構造の例を示す。 (1) Observation of void portion of hollow fiber membrane The membrane structure in the cross-sectional direction perpendicular to the length of one hollow fiber membrane formed was observed with an electron microscope at a magnification of 1000 times. FIG. 2 and FIG. 3 show examples of photographs of gap portions. At this time, it was confirmed whether or not the gap portion 40 in the center portion was larger than the gap portions in the vicinity of the inner surface 50 and the vicinity of the outer surface 30 and the presence or absence of the finger void structure. FIG. 6 shows an example of an asymmetric structure in which there is no gap portion at the center.

（２）水蒸気透過性能の測定
図４を用いて説明する。φ６のステンレス管に加湿用中空糸膜を３本通して両端を接着剤で固定した有効長０．１ｍのステンレス管モジュールを作製（以下、ミニモジュール１４０）し、８５℃の条件下で、中空糸の内側に乾燥ガス（スイープガス）、外側に加湿装置１１０で加湿された湿潤ガス（オフガス）を入り１２０、出１３０の１パスのクロスフローで流し、中空糸内部の線速を空気流量計８０で１０００ｃｍ／ｓｅｃになるように設定した。この時のスイープガス入り６０・出９０の温・湿度を、測定個所７０、１００で測定した。この数値から水蒸気透過量（ｇ）を時間（分）、中空糸の有効面積（ｃｍ２）、スイープガスの空気入り圧力（Ｍｐａ）で割った数値を水蒸気透過係数とした（図４）
空気流量は３点以上の中空糸線速を振り、おのおのの水蒸気透過係数から検量線（数式）を用いて線速１０００ｃｍ／ｓｅｃ時の数値を算出する事も可能である。 (2) Measurement of water vapor transmission performance This will be described with reference to FIG. A stainless steel pipe module with an effective length of 0.1 m (hereinafter referred to as a mini module 140) was prepared by passing three humidifying hollow fiber membranes through a 6 mm diameter stainless steel pipe and both ends fixed with an adhesive. A dry gas (sweep gas) inside the yarn and a wet gas (off gas) humidified by the humidifier 110 on the outside enter 120, and flow in a one-pass cross flow of 130, and the linear velocity inside the hollow fiber is measured by an air flow meter. 80 was set to be 1000 cm / sec. At this time, the temperature and humidity of the sweep gas 60 / out 90 were measured at measurement points 70 and 100. The value obtained by dividing the water vapor transmission rate (g) from this value by the time (minutes), the effective area of the hollow fiber (cm 2 ), and the air pressure (Mpa) of the sweep gas was taken as the water vapor transmission coefficient (FIG. 4).
It is also possible to calculate the numerical value at a linear velocity of 1000 cm / sec by using a calibration curve (formula) from the water vapor transmission coefficient for each air flow rate at three or more hollow fiber linear velocities.

中空糸の有効面積とは、スイープガスを中空糸内側に流す場合、中空糸内径（ｃｍ）×円周率×中空糸長（ｃｍ）で求められる面積である。   The effective area of the hollow fiber is an area obtained by hollow fiber inner diameter (cm) × circumference ratio × hollow fiber length (cm) when sweep gas is allowed to flow inside the hollow fiber.

（３）空気漏洩（エアーリーク）量測定
図５を用いて説明する。ミニモジュールの中空糸内部の一方に空気５０ｋＰａをかけ、もう一方に栓１６０をした。この時、中空糸外側に流出してくる空気漏洩量を流量計１５０で測定した。該流量から中空糸膜１本分の空気漏洩量を求めた（図５）。空気漏洩量を測定するミニモジュールは、４０℃の乾燥機で２４時間乾燥させたものを使用した。 (3) Measurement of Air Leakage (Air Leakage) A description will be given with reference to FIG. 50 kPa of air was applied to one of the hollow fibers of the mini module, and a plug 160 was attached to the other. At this time, the amount of air leakage flowing out of the hollow fiber was measured with a flow meter 150. The amount of air leakage for one hollow fiber membrane was determined from the flow rate (FIG. 5). The mini-module for measuring the amount of air leakage was one that was dried for 24 hours with a dryer at 40 ° C.

（４）中空糸糸径測定
製膜した中空糸膜を抜き取り、中空糸長手方向断面をマイクロウォッチャーの２００倍レンズ（ＫＥＹＥＮＣＥ社製、ＶＨ−Ｚ１００）で測定して中空糸膜内径、膜厚を求めた。 (4) Hollow fiber yarn diameter measurement The formed hollow fiber membrane is extracted, and the hollow fiber longitudinal section is measured with a microwatcher 200 × lens (manufactured by KEYENCE, VH-Z100) to determine the hollow fiber membrane inner diameter and film thickness. Asked.

（５）中空糸膜開孔面積平均径測定
西華産業社製ナノパームポロメーターを用いて、中空糸膜のヘリウムガス透過性から開孔面積平均径を求めた。 (5) Measurement of average diameter of open area of hollow fiber membrane Using a nano palm porometer manufactured by Seika Sangyo Co., Ltd., the average diameter of the open area was determined from the helium gas permeability of the hollow fiber membrane.

（実施例１）
ポリスルホン樹脂（ソルベー社製Ｐ３５００）１８部、ポリビニルピロリドン（ＩＳＰ社製Ｋ３０）９部、およびジメチルアセトアミド７２部、水１部からなる製膜原液を９０℃で溶解後、５０℃に保温し、１．０／０．７ｍｍからなる２重管口金からジメチルアセトアミド４０部、水６０部からなる芯液と同時に吐出させ、３０℃の乾式部３５０ｍｍを通り、水９０部、ジメチルアセトアミド１０部の凝固浴４０℃に浸漬させ、凝固させた。次いで凝固させた中空糸膜を８０℃の水洗浴で洗浄後、中空糸膜が湿潤状態のままカセに巻き取った。このときの製膜速度は１５ｍ／ｍｉｎとし、中空糸膜内径は６３０μｍ、膜厚は１００μｍであった。 Example 1
A film-forming stock solution consisting of 18 parts of a polysulfone resin (P3500 manufactured by Solvay), 9 parts of polyvinylpyrrolidone (K30 manufactured by ISP), 72 parts of dimethylacetamide, and 1 part of water was dissolved at 90 ° C, and kept at 50 ° C. A coagulating bath of 90 parts of water and 10 parts of dimethylacetamide is discharged from a double tube cap made of 0.0 / 0.7 mm simultaneously with the core liquid consisting of 40 parts of dimethylacetamide and 60 parts of water, passing through a dry part 350 mm at 30 ° C. It was immersed in 40 degreeC and solidified. Next, the solidified hollow fiber membrane was washed in a water washing bath at 80 ° C., and then wound around a cassette while the hollow fiber membrane was still wet. The film forming speed at this time was 15 m / min, the inner diameter of the hollow fiber membrane was 630 μm, and the film thickness was 100 μm.

巻き取った中空糸膜０．３ｍ、１０００本単位に小分けし、５０℃の乾熱乾燥機で２４時間乾燥を行い、加湿用中空糸膜を得た。   The wound hollow fiber membrane was subdivided into 0.3 m, 1000 units, and dried for 24 hours with a dry heat dryer at 50 ° C. to obtain a humidifying hollow fiber membrane.

この加湿用中空糸膜を３本取り出し、０．１ｍのミニモジュールを作製後、空気漏洩量を測定したところ０．０００２Ｌ／ｍｉｎであり、水蒸気透過係数が０．５２ｇ／ｍｉｎ／ｃｍ２／ＭＰａであった。加湿用中空糸膜の開孔面積平均径は１．４ｎｍであり、長手方向断面を電子顕微鏡で観察すると壁厚中央部に空隙部分が確認できた。面積９５００μｍ２あたりに、７個のフィンガーボイド構造が確認できた。 Three of these humidifying hollow fiber membranes were taken out to produce a 0.1 m mini-module, and the amount of air leakage was measured. As a result, it was 0.0002 L / min, and the water vapor transmission coefficient was 0.52 g / min / cm 2 / MPa. Met. The hole area average diameter of the humidifying hollow fiber membrane was 1.4 nm, and when the longitudinal section was observed with an electron microscope, a void portion could be confirmed in the central portion of the wall thickness. Seven finger void structures were confirmed per area of 9500 μm 2 .

（実施例２）
実施例1で溶解した製膜原液を、５０℃に保温し、１．０／０．７ｍｍからなる２重管口金からジメチルアセトアミド６０部、水４０部からなる芯液と同時に吐出させ、３０℃の乾式部３５０ｍｍを通り、水９０部、ジメチルアセトアミド１０部の凝固浴４０℃に浸漬させ、凝固させた。次いで凝固させた中空糸膜を８０℃の水洗浴で洗浄後、中空糸膜が湿潤状態のままカセに巻き取った。このときの製膜速度は１８ｍ／ｍｉｎとし、中空糸膜内径は６７０μｍ、膜厚は８５μｍであった。 (Example 2)
The film-forming stock solution dissolved in Example 1 was kept at 50 ° C., and simultaneously discharged from a double tube cap made of 1.0 / 0.7 mm with a core solution made of 60 parts of dimethylacetamide and 40 parts of water. Was dried and solidified by being immersed in a coagulation bath 40 ° C. of 90 parts of water and 10 parts of dimethylacetamide. Next, the solidified hollow fiber membrane was washed in a water washing bath at 80 ° C., and then wound around a cassette while the hollow fiber membrane was still wet. The film forming speed at this time was 18 m / min, the inner diameter of the hollow fiber membrane was 670 μm, and the film thickness was 85 μm.

巻き取った中空糸膜０．３ｍ、１０００本単位に小分けし、１７０℃の乾熱乾燥機で５時間乾燥を行い、加湿用中空糸膜を得た。   The wound hollow fiber membrane was subdivided into units of 0.3 m and 1000 pieces, and dried for 5 hours with a dry heat dryer at 170 ° C. to obtain a humidified hollow fiber membrane.

この加湿用中空糸膜を３本取り出し、０．１ｍのミニモジュールを作製後、空気漏洩量を測定したところ０．０１８Ｌ／ｍｉｎであり、水蒸気透過係数が０．６６ｇ／ｍｉｎ／ｃｍ２／ＭＰａであった。加湿用中空糸膜の開孔面積平均径は２．１ｎｍであり、長手方向断面を電子顕微鏡で観察すると壁厚中央部に空隙部分が確認できた。面積９５００μｍ２あたりに、６個のフィンガーボイド構造が確認できた。 Three of these humidifying hollow fiber membranes were taken out, a 0.1 m mini-module was produced, and the amount of air leakage was measured. As a result, it was 0.018 L / min, and the water vapor transmission coefficient was 0.66 g / min / cm 2 / MPa. Met. The hole area average diameter of the humidifying hollow fiber membrane was 2.1 nm, and when the longitudinal section was observed with an electron microscope, a void portion could be confirmed in the central portion of the wall thickness. Six finger void structures were confirmed per area of 9500 μm 2 .

（実施例３）
実施例1で溶解した製膜原液を、５０℃に保温し、１．０／０．７ｍｍからなる２重管口金からジメチルアセトアミド６０部、水４０部からなる芯液と同時に吐出させ、３０℃の乾式部３５０ｍｍを通り、水９０部、ジメチルアセトアミド１０部の凝固浴４０℃に浸漬させ、凝固させた。次いで凝固させた中空糸膜を８０℃の水洗浴で洗浄後、中空糸膜が湿潤状態のままカセに巻き取った。このときの製膜速度は１８ｍ／ｍｉｎとし、中空糸膜内径は６７０μｍ、膜厚は８５μｍであった。 (Example 3)
The film-forming stock solution dissolved in Example 1 was kept at 50 ° C., and simultaneously discharged from a double tube cap made of 1.0 / 0.7 mm with a core solution made of 60 parts of dimethylacetamide and 40 parts of water. Was dried and solidified by being immersed in a coagulation bath 40 ° C. of 90 parts of water and 10 parts of dimethylacetamide. Next, the solidified hollow fiber membrane was washed in a water washing bath at 80 ° C., and then wound around a cassette while the hollow fiber membrane was still wet. The film forming speed at this time was 18 m / min, the inner diameter of the hollow fiber membrane was 670 μm, and the film thickness was 85 μm.

巻き取った中空糸膜０．３ｍ、１０００本単位に小分けし、５０℃の乾熱乾燥機で２４時間乾燥を行い、加湿用中空糸膜を得た。   The wound hollow fiber membrane was subdivided into 0.3 m, 1000 units, and dried for 24 hours with a dry heat dryer at 50 ° C. to obtain a humidifying hollow fiber membrane.

この加湿用中空糸膜を３本取り出し、０．１ｍのミニモジュールを作製後、空気漏洩量を測定したところ０．０６５Ｌ／ｍｉｎであった。しかし、水蒸気透過性能を測定時には中空糸膜が水蒸気によって湿り、空気漏洩量は０．０００１Ｌ／ｍｉｎ以下となっていたため、水蒸気透過係数の測定が可能であり、水蒸気透過係数は０．７２ｇ／ｍｉｎ／ｃｍ２／ＭＰａであった。加湿用中空糸膜の開孔面積平均径は２．５ｎｍであり、長手方向断面を電子顕微鏡で観察すると壁厚中央部に空隙部分が確認できた。面積９５００μｍ２あたりに、６個のフィンガーボイド構造が確認できた。 Three of the humidifying hollow fiber membranes were taken out and a 0.1 m mini-module was produced, and the amount of air leakage was measured and found to be 0.065 L / min. However, when measuring the water vapor transmission performance, the hollow fiber membrane was wetted by water vapor, and the amount of air leakage was 0.0001 L / min or less, so that the water vapor transmission coefficient could be measured, and the water vapor transmission coefficient was 0.72 g / min. / Cm 2 / MPa. The average hole area diameter of the humidifying hollow fiber membrane was 2.5 nm. When the longitudinal section was observed with an electron microscope, a void portion was confirmed at the center of the wall thickness. Six finger void structures were confirmed per area of 9500 μm 2 .

（比較例１）
ポリスルホン樹脂（ソルベー社製Ｐ３５００）１６部、ポリビニルピロリドン（ＩＳＰ社製Ｋ３０）６部、ポリビニルピロリドン（ＩＳＰ社製Ｋ９０）３部およびジメチルアセトアミド７２部、水１部からなる製膜原液を９０℃で溶解後、５０℃に保温し、１．０／０．７ｍｍからなる２重管口金からジメチルアセトアミド４０部、水６０部からなる芯液と同時に吐出させ、３０℃の乾式部３５０ｍｍを通り、水９０部、ジメチルアセトアミド１０部の凝固浴４０℃に浸漬させ、凝固させた。次いで凝固させた中空糸膜を８０℃の水洗浴で洗浄後、中空糸膜が湿潤状態のままカセに巻き取った。このときの製膜速度は１５ｍ／ｍｉｎとし、中空糸膜内径は７６０μｍ、膜厚は９５μｍであった。 (Comparative Example 1)
A film-forming stock solution comprising 16 parts of a polysulfone resin (P3500 manufactured by Solvay), 6 parts of polyvinylpyrrolidone (K30 manufactured by ISP), 3 parts of polyvinylpyrrolidone (K90 manufactured by ISP), 72 parts of dimethylacetamide, and 1 part of water at 90 ° C. After dissolution, the mixture is kept at 50 ° C., discharged from a double tube cap of 1.0 / 0.7 mm at the same time as the core liquid consisting of 40 parts of dimethylacetamide and 60 parts of water, passes through a dry part 350 mm at 30 ° C., 90 parts and 10 parts of dimethylacetamide were immersed in a coagulation bath at 40 ° C. and solidified. Next, the solidified hollow fiber membrane was washed in a water washing bath at 80 ° C., and then wound around a cassette while the hollow fiber membrane was still wet. The film forming speed at this time was 15 m / min, the inner diameter of the hollow fiber membrane was 760 μm, and the film thickness was 95 μm.

巻き取った中空糸膜０．３ｍ、１０００本単位に小分けし、５０℃の乾熱乾燥機で２４時間乾燥を行い、加湿用中空糸膜を得た。   The wound hollow fiber membrane was subdivided into 0.3 m, 1000 units, and dried for 24 hours with a dry heat dryer at 50 ° C. to obtain a humidifying hollow fiber membrane.

この加湿用中空糸膜を３本取り出し、０．１ｍのミニモジュールにしたところ空気漏洩量は０．０００１Ｌ／ｍｉｎ以下であり、水蒸気透過係数が０．３２ｇ／ｍｉｎ／ｃｍ２／ＭＰａであった。加湿用中空糸膜の開孔面積平均径は０．９ｎｍであり、長手方向断面を電子顕微鏡で観察すると壁厚中央部に空隙部分は存在せず、内表面から外表面にかけての空隙部分が大きくなる非対称構造であることが確認でき、フィンガーボイド構造は確認できなかった。（図６）。 When three of these humidifying hollow fiber membranes were taken out and made into a 0.1 m mini-module, the amount of air leakage was 0.0001 L / min or less, and the water vapor transmission coefficient was 0.32 g / min / cm 2 / MPa. . The average diameter of the hole area of the humidifying hollow fiber membrane is 0.9 nm, and when the longitudinal section is observed with an electron microscope, there is no void in the central portion of the wall thickness, and the void from the inner surface to the outer surface is large. The asymmetric structure was confirmed, and the finger void structure was not confirmed. (FIG. 6).

（比較例２）
ポリスルホン樹脂（ソルベー社製Ｐ３５００）１８部、ポリビニルピロリドン（ＩＳＰ社製Ｋ３０）６部、ポリビニルピロリドン（ＩＳＰ社製Ｋ９０）３部およびジメチルアセトアミド７２部、水１部からなる製膜原液を９０℃で溶解後、５０℃に保温し、１．０／０．７ｍｍからなる２重管口金からジメチルアセトアミド４０部、水６０部からなる芯液と同時に吐出させ、３０℃の乾式部３５０ｍｍを通り、水９０部、ジメチルアセトアミド１０部の凝固浴４０℃に浸漬させ、凝固させた。次いで凝固させた中空糸膜を８０℃の水洗浴で洗浄後、中空糸膜が湿潤状態のままカセに巻き取った。このときの製膜速度は１５ｍ／ｍｉｎとし、中空糸膜内径は６５０μｍ、膜厚は９５μｍであった。 (Comparative Example 2)
A film-forming stock solution consisting of 18 parts of a polysulfone resin (P3500 manufactured by Solvay), 6 parts of polyvinylpyrrolidone (K30 manufactured by ISP), 3 parts of polyvinylpyrrolidone (K90 manufactured by ISP), 72 parts of dimethylacetamide, and 1 part of water at 90 ° C. After dissolution, the mixture is kept at 50 ° C., discharged from a double tube cap of 1.0 / 0.7 mm at the same time as the core liquid consisting of 40 parts of dimethylacetamide and 60 parts of water, passes through a dry part 350 mm at 30 ° C., 90 parts and 10 parts of dimethylacetamide were immersed in a coagulation bath at 40 ° C. and solidified. Next, the solidified hollow fiber membrane was washed in a water washing bath at 80 ° C., and then wound around a cassette while the hollow fiber membrane was still wet. The film forming speed at this time was 15 m / min, the inner diameter of the hollow fiber membrane was 650 μm, and the film thickness was 95 μm.

巻き取った中空糸膜０．３ｍ、１０００本単位に小分けし、５０℃の乾熱乾燥機で２４時間乾燥を行い、加湿用中空糸膜を得た。   The wound hollow fiber membrane was subdivided into 0.3 m, 1000 units, and dried for 24 hours with a dry heat dryer at 50 ° C. to obtain a humidifying hollow fiber membrane.

この加湿用中空糸膜を３本取り出し、０．１ｍのミニモジュールにしたところ空気漏洩量は０．０００１Ｌ／ｍｉｎ以下であり、水蒸気透過係数が０．２８ｇ／ｍｉｎ／ｃｍ２／ＭＰａであった。加湿用中空糸膜の開孔面積平均径は０．８ｎｍであり、長手方向断面を電子顕微鏡で観察すると壁厚中央部に空隙部分は存在せず、内表面から外表面にかけての空隙部分が大きくなる非対称構造であることが確認でき、フィンガーボイド構造は確認できなかった。 When three of these humidifying hollow fiber membranes were taken out and made into a 0.1 m mini-module, the amount of air leakage was 0.0001 L / min or less, and the water vapor transmission coefficient was 0.28 g / min / cm 2 / MPa. . The average diameter of the hole area of the humidifying hollow fiber membrane is 0.8 nm. When the longitudinal section is observed with an electron microscope, there is no void in the central portion of the wall thickness, and the void from the inner surface to the outer surface is large. The asymmetric structure was confirmed, and the finger void structure was not confirmed.

（比較例３）
ポリスルホン樹脂（ソルベー社製Ｐ３５００）１８部、ポリビニルピロリドン（ＩＳＰ社製Ｋ３０）９部、およびジメチルアセトアミド７２部、水１部からなる製膜原液を９０℃で溶解後、５０℃に保温し、１．０／０．７ｍｍからなる２重管口金からジメチルアセトアミド４０部、水６０部からなる芯液と同時に吐出させ、３０℃の乾式部３５０ｍｍを通り、水９０部、ジメチルアセトアミド１０部の凝固浴４０℃に浸漬させ、凝固させた。次いで凝固させた中空糸膜を８０℃の水洗浴で洗浄後、中空糸膜が湿潤状態のままカセに巻き取った。このときの製膜速度は１５ｍ／ｍｉｎとし、中空糸膜内径は６３０μｍ、膜厚は１００μｍであった。 (Comparative Example 3)
A film-forming stock solution consisting of 18 parts of a polysulfone resin (P3500 manufactured by Solvay), 9 parts of polyvinylpyrrolidone (K30 manufactured by ISP), 72 parts of dimethylacetamide, and 1 part of water was dissolved at 90 ° C, and kept at 50 ° C. A coagulating bath of 90 parts of water and 10 parts of dimethylacetamide is discharged from a double tube cap made of 0.0 / 0.7 mm simultaneously with the core liquid consisting of 40 parts of dimethylacetamide and 60 parts of water, passing through a dry part 350 mm at 30 ° C. It was immersed in 40 degreeC and solidified. Next, the solidified hollow fiber membrane was washed in a water washing bath at 80 ° C., and then wound around a cassette while the hollow fiber membrane was still wet. The film forming speed at this time was 15 m / min, the inner diameter of the hollow fiber membrane was 630 μm, and the film thickness was 100 μm.

巻き取った中空糸膜は乾燥処理を行わなかった。   The wound hollow fiber membrane was not dried.

この加湿用中空糸膜を３本取り出し、０．１ｍのミニモジュールを作製後、空気漏洩量を測定したところ、長手方向断面を電子顕微鏡で観察すると壁厚中央部に空隙部分が確認でき、面積９５００μｍ２あたりに、７個のフィンガーボイド構造が確認できたが、空気漏洩量は０．１Ｌ／ｍｉｎ以上であり、空気リーク量が多いため、水蒸気透過性能は測定できなかった。 After taking out three of these humidifying hollow fiber membranes and making a 0.1 m mini-module, the amount of air leakage was measured, and when the longitudinal section was observed with an electron microscope, a void portion could be confirmed at the center of the wall thickness. Seven finger void structures were confirmed per 9500 μm 2 , but the air leakage amount was 0.1 L / min or more and the air leakage amount was large, so that the water vapor transmission performance could not be measured.

１０：フィンガーボイド構造のＸ軸
２０：フィンガーボイド構造のＹ軸
３０：中空糸膜断面の外表面近傍（空隙が存在する中空糸膜）
４０：中空糸膜断面の中央部の空隙部分
５０：中空糸膜断面の内表面近傍（空隙が存在する中空糸膜）
６０：スイープガス入り
７０：温・湿度測定個所
８０：空気流量計
９０：スイープガス出
１００：温・湿度測定個所
１１０：加湿装置
１２０：オフガス入り
１３０：オフガス出
１４０：ミニモジュール
１５０：空気流量計
１６０：栓
１７０：中空糸膜断面の外表面近傍（空隙が存在しない中空糸膜）
１８０：中空糸膜断面の内表面近傍（空隙が存在しない中空糸膜） 10: X axis of finger void structure 20: Y axis of finger void structure 30: Near outer surface of hollow fiber membrane cross section (hollow fiber membrane with voids)
40: Cavity portion at the center of the cross section of the hollow fiber membrane 50: Near the inner surface of the cross section of the hollow fiber membrane (hollow fiber membrane having a void)
60: With sweep gas 70: Temperature / humidity measurement location 80: Air flow meter 90: Sweep gas output 100: Temperature / humidity measurement location 110: Humidifier 120: With off gas 130: Off gas output 140: Mini module 150: Air flow meter 160: Plug 170: Near outer surface of hollow fiber membrane cross section (hollow fiber membrane without voids)
180: Near the inner surface of the cross section of the hollow fiber membrane (hollow fiber membrane without voids)

Claims (8)

電子顕微鏡を用いて、中空糸膜の長手に垂直な断面方向の膜構造を、１０００倍の倍率で観察を行った時に、フィンガーボイド構造を有し、水蒸気透過係数が０．４ｇ／ｍｉｎ／ｃｍ２／ＭＰａ以上であり、空気漏洩量が０．１Ｌ／ｍｉｎ以下である加湿用中空糸膜。 When the membrane structure in the cross-sectional direction perpendicular to the length of the hollow fiber membrane is observed at an magnification of 1000 times using an electron microscope, it has a finger void structure and a water vapor transmission coefficient of 0.4 g / min / cm. A humidifying hollow fiber membrane having a rate of 2 / MPa or more and an air leakage amount of 0.1 L / min or less. 面積９５００μｍ２あたりに、フィンガーボイドが２つ以上ある請求項１記載の加湿用中空糸膜。 The humidifying hollow fiber membrane according to claim 1, wherein there are two or more finger voids per area of 9,500 µm 2 . 該加湿用中空糸膜の内径が３００μｍ以上１５００μｍ以下、膜厚が５０μｍ以上２００μｍ以下である請求項１または２に記載の加湿用中空糸膜。 The humidifying hollow fiber membrane according to claim 1 or 2, wherein the humidifying hollow fiber membrane has an inner diameter of 300 µm to 1500 µm and a film thickness of 50 µm to 200 µm. 該加湿用中空糸膜がポリスルホンを含む請求項１〜３のいずれかに記載の加湿用中空糸膜。 The humidifying hollow fiber membrane according to any one of claims 1 to 3, wherein the humidifying hollow fiber membrane contains polysulfone. 該加湿用中空糸膜が親水性高分子を含む請求項１〜４のいずれかに記載の加湿用中空糸膜。 The humidifying hollow fiber membrane according to any one of claims 1 to 4, wherein the humidifying hollow fiber membrane contains a hydrophilic polymer. 該親水性高分子がポリビニルピロリドンであり、該ポリビニルピロリドンの分子量が４０００００以下である請求項５に記載の加湿用膜。 The humidifying membrane according to claim 5, wherein the hydrophilic polymer is polyvinyl pyrrolidone, and the molecular weight of the polyvinyl pyrrolidone is 400,000 or less. 該ポリビニルピロリドンがポリスルホンに対して３０〜７０重量％である請求項５に記載の加湿用膜。 The humidifying membrane according to claim 5, wherein the polyvinyl pyrrolidone is 30 to 70% by weight based on polysulfone. 請求項１〜７のいずれかに記載の加湿用中空糸膜を内蔵した加湿用膜モジュール。 A humidifying membrane module incorporating the humidifying hollow fiber membrane according to any one of claims 1 to 7.
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