JPH07157580A - Production of porous membrane - Google Patents
Production of porous membraneInfo
- Publication number
- JPH07157580A JPH07157580A JP30790293A JP30790293A JPH07157580A JP H07157580 A JPH07157580 A JP H07157580A JP 30790293 A JP30790293 A JP 30790293A JP 30790293 A JP30790293 A JP 30790293A JP H07157580 A JPH07157580 A JP H07157580A
- Authority
- JP
- Japan
- Prior art keywords
- gas
- oxygen concentration
- mol
- nozzle
- hollow fiber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、多孔質膜、即ち膜の片
側表面から他の表面に連通した細孔を有する膜の改良さ
れた製造方法に関する。FIELD OF THE INVENTION The present invention relates to an improved process for the production of porous membranes, i.e. membranes having pores communicating from one surface of the membrane to the other.
【０００２】本発明により製造される多孔質膜は、精密
濾過膜、限外濾過膜、複合膜の支持体、膜型人工肺、液
体からの脱気、液体への気体溶解、膜蒸留、透湿防水フ
ィルム、滅菌器具包装材などの用に供せられる。Porous membranes produced by the present invention include microfiltration membranes, ultrafiltration membranes, composite membrane supports, membrane oxygenators, degassing from liquids, gas dissolution in liquids, membrane distillation, and permeation. It is used for wet waterproof film, sterilization instrument packaging material, etc.
【０００３】[0003]
【従来の技術】結晶性の熱可塑性重合体を溶融押し出し
成形してフィルム状、管状、中空糸状の中間体を得、こ
れを延伸してこれらの中間体を多孔質化する多孔質膜の
製法（以下溶融法と称する）が知られている（例えば特
開昭５９−１９９８０８、特開昭５４−１３８６２
３）。溶融法の溶融押し出し成形においては、ノズルか
ら押し出された溶融状態にある膜前駆体は気体により冷
却され固化するが、冷却用気体としては、空気、窒素な
ど任意の気体であればよいとされ、通常空気が用いられ
てきた。また中空糸状に溶融紡糸する場合には、気体を
芯剤として溶融押し出しされるが、芯剤気体もまた任意
の気体であればよいとされ、空気や窒素が使用されてい
た。2. Description of the Related Art A method for producing a porous membrane in which a crystalline thermoplastic polymer is melt-extruded to obtain a film-shaped, tubular or hollow-fiber-shaped intermediate, which is stretched to make these intermediates porous. (Hereinafter referred to as a melting method) is known (for example, JP-A-59-199808 and JP-A-54-13862).
3). In the melt extrusion molding of the melting method, the film precursor in a molten state extruded from the nozzle is cooled and solidified by a gas, but the cooling gas may be any gas such as air and nitrogen, Usually air has been used. Further, in the case of melt spinning into a hollow fiber, a gas is melt-extruded using a core agent, but the core agent gas may be any gas, and air or nitrogen has been used.
【０００４】しかし、冷却用気体、芯剤気体のいずれに
ついても、気体種の違いや濃度が多孔質膜の構造や特性
に及ぼす効果については知られておらず、使用可能な気
体の中で好ましい気体について言及されることはなかっ
た。However, regarding any of the cooling gas and the core gas, the effect of the difference or concentration of the gas species on the structure and characteristics of the porous membrane is not known, and it is preferable among the usable gases. There was no mention of gas.
【０００５】[0005]
【発明が解決しようとする課題】溶融法により高い流体
透過速度を有する膜を成形するには、膜の平面内や厚み
方向において、細孔の存在密度の低い部分が存在しない
様に成形することが肝要である。溶融法による多孔質膜
について、これまで、高いフラックスを得るために紡
糸、熱処理、延伸、熱固定などの工程の製造条件検討が
成されてきた。しかしながら、これらの最適条件で製造
された多孔質膜でも、電子顕微鏡で観察すると、局所的
に細孔が存在しない部分が存在するなど、得られた膜は
いまだ不十分なものであった。また、高いフラックスを
実現するための最適条件の範囲は狭く、工業的生産にお
いて、特性の変動と歩留まりの悪化を招いていた。本発
明が解決しようとする課題は、膜中の細孔存在密度の低
い部分の発生を除去し、高い流体透過速度を有する多孔
質膜を製造することにある。In order to form a membrane having a high fluid permeation rate by the melting method, the membrane should be formed so that there are no portions with low density of pores in the plane of the membrane or in the thickness direction. Is essential. Regarding the porous film produced by the melting method, the production conditions of the processes such as spinning, heat treatment, drawing, and heat setting have been studied so far in order to obtain a high flux. However, even with the porous membranes manufactured under these optimum conditions, when observed with an electron microscope, the obtained membranes were still inadequate, such as the local presence of pore-free portions. In addition, the range of optimum conditions for achieving high flux is narrow, which has led to fluctuations in characteristics and deterioration of yield in industrial production. The problem to be solved by the present invention is to remove the generation of a portion having a low density of pores in a membrane to produce a porous membrane having a high fluid permeation rate.
【０００６】[0006]
【課題を解決するための手段】本発明者等は、溶融法に
よる多孔質膜の形成機構について鋭意研究した結果、細
孔の存在密度の低い部分が形成される要因として、ノズ
ルから押し出された溶融状態にある膜前駆体に接触する
気体中の酸素濃度があることを見いだし、本発明に到達
した。Means for Solving the Problems As a result of earnest studies on the formation mechanism of a porous film by the melting method, the present inventors have found that a portion having a low density of pores is extruded from a nozzle. The present invention has been reached by finding that there is an oxygen concentration in the gas that comes into contact with the film precursor in a molten state.
【０００７】即ち、本発明の要旨は、ノズルから結晶性
熱可塑性重合体を気体中に溶融押し出しし、次いで延伸
することにより多孔質化する多孔質膜の製法であって、
ノズルから押し出された溶融状態にある膜前駆体の一方
の面が酸素濃度１〜１０モル％の気体に接し、他の面が
酸素濃度１０モル％以下の気体に接した状態で冷却固化
することを特徴とする多孔質膜の製造方法にある。That is, the gist of the present invention is a process for producing a porous membrane in which a crystalline thermoplastic polymer is melt-extruded into a gas from a nozzle and then stretched to make it porous.
One side of the molten film precursor extruded from the nozzle is in contact with a gas having an oxygen concentration of 1 to 10 mol% and the other side is in contact with a gas having an oxygen concentration of 10 mol% or less to be cooled and solidified. And a method for producing a porous membrane.
【０００８】以下本発明をさらに詳細に説明する。本発
明の製造方法により得られる多孔質膜は、フィルム状、
管状、中空糸状等の形状に成形された、膜の片側表面か
ら他の表面に連通した細孔を有する膜である。The present invention will be described in more detail below. The porous membrane obtained by the production method of the present invention is in the form of a film,
The membrane is formed into a tubular shape, a hollow fiber shape, or the like and has pores communicating from one surface of the membrane to the other surface.
【０００９】本発明に使用される重合体は結晶性熱可塑
性重合体である。重合体は到達結晶化度が３０％以上の
ものであることが、優れた性能の多孔質膜を製造する上
で好ましい。また、本発明に使用される結晶性熱可塑性
重合体は、結晶融点が高いものや、酸素による酸化分解
性を示す物の場合に、本発明の効果が高くなる。The polymer used in the present invention is a crystalline thermoplastic polymer. It is preferable that the polymer has an ultimate crystallinity of 30% or more in order to produce a porous film having excellent performance. Further, the crystalline thermoplastic polymer used in the present invention exhibits a high effect of the present invention when it has a high crystal melting point or exhibits oxidative decomposition by oxygen.
【００１０】結晶性熱可塑性重合体の例としては、ポリ
エチレン、ポリプロピレン、ポリ−４−メチルペンテン
−１、ポリ−３−メチルブテン−１などのポリオレフィ
ン、ポリアセタ−ル、ポリオキシエチレン、ポリフェニ
レンオキサイドなどのポリエ−テル、ポリメチレンサル
ファイド、ポリエチレンサルファイド、などのポリチオ
エーテル、ポリ塩化ビニリデンなどの塩素含有ポリマ
ー、ポリフッ化ビニリデンなどのフッ素含有ポリマー、
ナイロン６、ナイロン６６などのポリアミド、ポリエチ
レンテレフタレ−トなどのポリエステル、ポリスチレ
ン、などを挙げることができる。勿論これらの共重合体
であってもよい。Examples of crystalline thermoplastic polymers include polyolefins such as polyethylene, polypropylene, poly-4-methylpentene-1, poly-3-methylbutene-1 and the like, polyacetal, polyoxyethylene, polyphenylene oxide and the like. Polythioethers such as polyether, polymethylene sulfide, polyethylene sulfide, chlorine-containing polymers such as polyvinylidene chloride, fluorine-containing polymers such as polyvinylidene fluoride,
Examples thereof include polyamides such as nylon 6 and nylon 66, polyesters such as polyethylene terephthalate, polystyrene, and the like. Of course, these copolymers may be used.
【００１１】これらの中で、ポリオレフィンが到達結晶
化度が高く良好な多孔質体が得られる上、物性や耐熱性
などの面で実用性が高く好適である。さらにポリオレフ
ィンの中では、ポリ−４−メチルペンテン−１、および
４−メチルペンテン−１を主要な成分とする（５０重量
％以上含有する）共重合体が、結晶融点が高く、酸素に
よる酸化分解性を示すため、本発明の効果が特に明確に
現れ、好ましい。４−メチルペンテン−１を主要な成分
とする共重合体の好ましい共重合成分の例としては、エ
チレン、プロピレン、ブテン−１、イソブチレン、ペン
テン類、ヘキセン類、その他のαオレフィンなどのオレ
フィン類が挙げられる。Of these, polyolefin is preferable because it has a high degree of crystallinity and can obtain a good porous material, and is highly practical in terms of physical properties and heat resistance. Further, among polyolefins, poly-4-methylpentene-1 and a copolymer containing 4-methylpentene-1 as a main component (containing 50% by weight or more) have a high crystal melting point and are oxidatively decomposed by oxygen. Since the effect of the present invention is exhibited, the effects of the present invention are particularly clear and preferable. Examples of preferred copolymerization components of the copolymer having 4-methylpentene-1 as a main component include ethylene, propylene, butene-1, isobutylene, pentenes, hexenes, and other olefins such as α-olefins. Can be mentioned.
【００１２】本発明の製造方法は、まず結晶性熱可塑性
重合体（以下単に重合体と称する場合もある）を使用し
て、フィルム状、管状、中空糸状などの形状に溶融押し
出し成形する。本発明は、この際、ノズルから押し出さ
れた溶融状態にある膜前駆体の両面を酸素濃度１〜１０
モル％の気体雰囲気にすることが特徴である。ただし、
片面は酸素濃度１モル％以下の気体であってもよい。以
下、酸素濃度１〜１０モル％の気体あるいは酸素濃度１
０モル％以下の気体を低酸素気体と称する。ここでいう
溶融状態にある膜前駆体とは、ノズルから押し出されて
膜状に成形されているが、まだ固化していない溶融重合
体のことをいう。In the production method of the present invention, first, a crystalline thermoplastic polymer (which may be simply referred to as a polymer hereinafter) is used and melt-extruded into a film shape, a tubular shape, a hollow fiber shape or the like. In this case, according to the present invention, the oxygen concentration of 1 to 10 is applied to both surfaces of the film precursor in a molten state extruded from the nozzle.
The feature is that the gas atmosphere is mol%. However,
One surface may be a gas having an oxygen concentration of 1 mol% or less. Hereinafter, a gas having an oxygen concentration of 1 to 10 mol% or an oxygen concentration of 1
A gas of 0 mol% or less is referred to as a low oxygen gas. The film precursor in a molten state as used herein means a molten polymer which has been extruded from a nozzle and formed into a film, but which has not been solidified yet.
【００１３】以下、説明の簡略化のため、特記した場合
を除いて、中空糸膜の場合について説明する。他の形状
の膜についても同様のことが当てはまる。但しフィルム
状の膜に於ては、中空糸膜の場合の外側／内側は、膜の
一方の側／他の側となる。For the sake of simplification of description, the case of a hollow fiber membrane will be described below unless otherwise specified. The same applies to membranes of other shapes. However, in the case of a film-shaped membrane, the outside / inside in the case of a hollow fiber membrane is one side / other side of the membrane.
【００１４】中空糸膜の場合には、中空糸紡糸ノズルを
用いて、気体を芯剤として重合体を溶融押し出しし、ド
ラフト（溶融状態での延伸）を掛けながら冷却固化させ
る（以上の工程を溶融紡糸と称する）。この際、ノズル
から押し出され溶融状態にある膜前駆体の内側を酸素濃
度が１０モル％以下の低酸素気体と接触させ、外側を１
〜１０モル％の低酸素気体と接触させることが好まし
い。溶融状態にある膜前駆体の内側を低酸素気体と接触
させるには、中空糸溶融紡糸時の芯剤として低酸素気体
を使用する方法で実施できる。溶融状態にある膜前駆体
の外側を低酸素気体と接触させるには、冷却用気体とし
て低酸素気体を使用する方法で実施できる。In the case of a hollow fiber membrane, a hollow fiber spinning nozzle is used to melt-extrude a polymer using gas as a core agent and cool and solidify it while drafting (stretching in a molten state). Referred to as melt spinning). At this time, the inside of the melted film precursor extruded from the nozzle is brought into contact with a low oxygen gas having an oxygen concentration of 10 mol% or less, and the outside is
It is preferable to contact with a low oxygen gas of 10 mol%. In order to bring the inside of the membrane precursor in a molten state into contact with low oxygen gas, a method using low oxygen gas as a core agent during hollow fiber melt spinning can be used. In order to bring the outside of the film precursor in a molten state into contact with the low oxygen gas, a method using a low oxygen gas as a cooling gas can be used.
【００１５】ノズルから押し出された膜前駆体と接触す
る雰囲気気体の酸素濃度を、膜の一方を１〜１０モル％
に、他方を１０モル％以下、好ましくは７モル％以下と
することにより、少なくとも片面が空気と接触している
場合に比べて、流体の膜透過速度が明白に向上する。少
なくとも一方の面が空気雰囲気である場合は部分的に細
孔のないところが出来易いため好ましくない。また、接
触させる低酸素気体の酸素濃度の下限については、酸素
濃度が１モル％以上であっても、両面の酸素濃度が極め
て低い場合（例えば０．００１モル％未満）とほぼ同等
の特性が得られる。一方、低酸素気体の酸素濃度を０に
近付けるほど気体のコストは増加する。従って、冷却用
の低酸素気体としては酸素濃度１％以上であることが好
ましい。しかし、気体の使用量が少量で済む芯剤気体に
ついては、酸素濃度が１モル％以下、例えば０．００１
〜１モル％の気体であることも好ましい。フィルム状の
膜の場合は両面とも１〜１０モル％の気体であることが
経済面的に好ましい。The oxygen concentration of the atmosphere gas in contact with the film precursor extruded from the nozzle is set to 1 to 10 mol% for one of the films.
By setting the other amount to 10 mol% or less, preferably 7 mol% or less, the membrane permeation rate of the fluid is clearly improved as compared with the case where at least one surface is in contact with air. If at least one surface is in an air atmosphere, it is easy to form a part without pores, which is not preferable. Regarding the lower limit of the oxygen concentration of the low oxygen gas to be contacted, even if the oxygen concentration is 1 mol% or more, almost the same characteristics as when the oxygen concentration on both sides is extremely low (for example, less than 0.001 mol%) are obtained. can get. On the other hand, as the oxygen concentration of the low oxygen gas approaches zero, the cost of the gas increases. Therefore, the low oxygen gas for cooling preferably has an oxygen concentration of 1% or more. However, for a core agent gas that requires a small amount of gas, the oxygen concentration is 1 mol% or less, for example, 0.001
It is also preferred that the gas is ˜1 mol%. In the case of a film-like membrane, it is economically preferable that both sides are 1 to 10 mol% gas.
【００１６】低酸素気体の酸素以外の成分としては、使
用する重合体と非反応性の気体であれば任意である。例
えば、窒素、炭酸ガス、アルゴンなどが好ましいが、樹
脂を透過散逸する速度が低くコストも低い点で窒素を主
要な成分とした気体がより好ましい。窒素を主要な成分
とした気体の窒素と酸素以外の成分は、アルゴン、炭酸
ガス、水蒸気などであり得る。窒素を主要な成分とした
気体としては、高純度窒素をそのままあるいは空気など
の他の気体と混合して用いてもよいし、窒素富化空気を
使用してもよい。窒素富化空気は、分離膜式やＰＳＡ
（吸着式）などにより製造することができる。これらの
窒素富化空気は、動力源や高圧空気源があれば無制限に
製造できるため、ボンベ交換などの手間がかからない
上、低コストで製造できるため特に好ましい。Any component other than oxygen in the low oxygen gas may be used as long as it is a gas that is non-reactive with the polymer used. For example, nitrogen, carbon dioxide gas, argon and the like are preferable, but a gas containing nitrogen as a main component is more preferable because it has a low rate of permeating and dispersing a resin and a low cost. The components other than nitrogen and oxygen, which are gases containing nitrogen as a main component, may be argon, carbon dioxide, water vapor, and the like. As the gas containing nitrogen as a main component, high-purity nitrogen may be used as it is or as a mixture with other gas such as air, or nitrogen-enriched air may be used. Nitrogen-enriched air can be separated membrane type or PSA
(Adsorption type) or the like. These nitrogen-enriched airs are particularly preferable because they can be produced without any limitation as long as they have a power source and a high-pressure air source, and therefore they do not require the trouble of replacing the cylinder and can be produced at low cost.
【００１７】本発明における低酸素気体は、ノズルから
押し出された膜前駆体が溶融状態にある部分が上記の値
であればよい。即ち、ノズルから押し出された膜前駆体
が固化するまでの部分に低酸素気体を接触させれば良
く、固化後の高温にある中空糸を冷却する気体は任意で
ある。The low oxygen gas in the present invention may have the above-mentioned value at the portion where the film precursor extruded from the nozzle is in a molten state. That is, a low oxygen gas may be brought into contact with the portion of the membrane precursor extruded from the nozzle until it solidifies, and any gas may be used to cool the hollow fiber at high temperature after solidification.
【００１８】従って、例えば、少なくともノズルから押
し出された膜前駆体の固化点までの範囲を低酸素気体と
し、少なくとも固化点より離れた、固化後のまだ高温に
ある中空糸をさらに冷却する気体として空気を使用する
ことも、製造の経済面から好ましい。Therefore, for example, at least the range up to the solidification point of the film precursor extruded from the nozzle is set as a low oxygen gas, and at least the hollow fiber which is still at a high temperature after solidification and which is far from the solidification point is further cooled. The use of air is also preferable from the economical aspect of manufacturing.
【００１９】ノズル面から膜前駆体の固化点、即ちノズ
ルから押し出された膜前駆体が実質的に固体となる位置
までの距離は、ノズルから押し出された後細くなりつつ
ある中空糸の外径が一定になる距離として、あるいは接
触法により測定できる。The solidification point of the film precursor from the nozzle surface, that is, the distance from the nozzle to the position at which the film precursor extruded from the nozzle becomes substantially solid is the outer diameter of the hollow fiber which is becoming thinner after being extruded from the nozzle. Can be measured as a constant distance or by a contact method.
【００２０】溶融紡糸の条件は、ノズルから押し出され
まだ溶融状態にある膜前駆体の両側に接触する気体を低
酸素気体とすることを除いて、公知の溶融法多孔質膜の
製造方法と同様であり、用いる重合体の種類により、形
成しようとする膜に最適な条件を選べば良い。即ち、溶
融押出し温度は重合体の結晶融解温度（Ｔｍ）以上の温
度、好ましくは（Ｔｍ＋１０）℃〜（Ｔｍ＋１００）℃
であり、溶融押し出し可能な範囲で、できるだけ低い温
度であることが好ましい。ドラフトは５０〜１０００
０、好ましくは１００〜１０００である。冷却は気体中
での冷却が好ましく、冷却用気体の温度や風速は、押出
された中空糸前駆体の固化点が、好ましくはノズルから
５〜２００ｍｍ、さらに好ましくは１０〜５０ｍｍにな
る様に調節する。 溶融紡糸された中空糸（本明細書に
おいては、溶融紡糸され、まだ多孔質構造を有しない中
空糸状の中間体を中空糸と称する）を多孔質膜化する工
程についても、公知の溶融法多孔質膜の製造方法の場合
と同様である。以下、その工程について述べる。The melt spinning conditions are the same as those of the known method for producing a porous film by the melting method, except that the gas extruded from the nozzle and contacting both sides of the film precursor which is still in a molten state is low oxygen gas. Therefore, the optimum conditions for the film to be formed may be selected depending on the type of polymer used. That is, the melt extrusion temperature is a temperature equal to or higher than the crystal melting temperature (Tm) of the polymer, preferably (Tm + 10) ° C. to (Tm + 100) ° C.
It is preferable that the temperature is as low as possible within the range where melt extrusion is possible. Draft is 50-1000
It is 0, preferably 100 to 1000. Cooling is preferably performed in a gas, and the temperature and the wind speed of the cooling gas are adjusted such that the solidification point of the extruded hollow fiber precursor is preferably 5 to 200 mm, more preferably 10 to 50 mm from the nozzle. To do. The step of forming a melt-spun hollow fiber (in this specification, a hollow-fiber-like intermediate that has been melt-spun and does not yet have a porous structure is referred to as a hollow fiber) into a porous film is also known as a melt-processed porous material. This is the same as in the case of the method for producing a membrane. The process will be described below.
【００２１】溶融紡糸された中空糸は、必要に応じて熱
処理される。熱処理温度は重合体のＴｇ（ガラス転移温
度）以上、Ｔｍ（結晶融解温度）以下である。熱処理を
施すことにより重合体の結晶化度の増加や結晶欠陥の減
少を計り、中空糸を多孔質化し易くすることができる。
熱処理もまた、酸素濃度１０モル％未満の低酸素雰囲気
中、特に好ましくは窒素濃度９０モル％以上の窒素雰囲
気中で処理されることが好ましい。The melt-spun hollow fiber is heat-treated if necessary. The heat treatment temperature is Tg (glass transition temperature) or more and Tm (crystal melting temperature) or less of the polymer. By performing the heat treatment, the crystallinity of the polymer can be increased and the crystal defects can be reduced, and the hollow fiber can be easily made porous.
The heat treatment is also preferably performed in a low oxygen atmosphere having an oxygen concentration of less than 10 mol%, particularly preferably in a nitrogen atmosphere having a nitrogen concentration of 90 mol% or more.
【００２２】溶融紡糸されたまたは熱処理された中空糸
は、延伸することにより中空糸壁が多孔質化される。中
空糸壁が多孔質化される機構は、溶融押し出しした結晶
性重合体を、ドラフトによる適当な張力下、かつ適当な
温度勾配下で冷却すると、繊維軸に直角な面内に積層板
状結晶が発達し、それを延伸すると結晶間が開裂し多孔
質体となる機構によるといわれている。In the melt-spun or heat-treated hollow fiber, the hollow fiber wall is made porous by stretching. The mechanism by which the hollow fiber wall is made porous is that when the melt-extruded crystalline polymer is cooled under an appropriate tension by a draft and under an appropriate temperature gradient, laminated plate-like crystals are formed in a plane perpendicular to the fiber axis. It is said that this is due to the mechanism in which the crystal develops, and when it is stretched, the crystals are cleaved to form a porous body.
【００２３】延伸温度、延伸倍率、延伸速度などは特に
限定する必要はなく、重合体に応じて適当な値を選ぶこ
とができる。例えば、延伸温度は（Ｔｍ−１０）℃以下
であることが好ましく、（Ｔｇ＋５０）℃以下であるこ
とが好ましい。延伸温度の下限は特に設ける必要はな
く、液体窒素温度（マイナス１９６℃）でも可能であ
る。延伸倍率は１．３〜６が好ましく、２〜４がさらに
好ましい。延伸温度が高いほど延伸倍率を高くすること
好ましい。The stretching temperature, the stretching ratio, the stretching speed, etc. are not particularly limited, and an appropriate value can be selected according to the polymer. For example, the stretching temperature is preferably (Tm-10) ° C or lower, and preferably (Tg + 50) ° C or lower. It is not necessary to set the lower limit of the stretching temperature, and the liquid nitrogen temperature (minus 196 ° C.) is also possible. The stretch ratio is preferably 1.3 to 6, and more preferably 2 to 4. The higher the stretching temperature, the higher the stretching ratio is preferably.
【００２４】延伸は多段延伸であってよく、温度を順次
上昇させた多段延伸であることが好ましい。多段延伸の
場合には、延伸温度が（Ｔｇ＋５０）℃以下での延伸を
含むことが好ましい。多段延伸の場合には、各段の延伸
倍率は１．１以上であることが好ましく、かつトータル
の延伸倍率が１．３〜６であることが好ましく、２〜４
がさらに好ましい。延伸温度の高い段ほど、その段の延
伸倍率を高くすることが好ましい。The stretching may be a multi-stage stretching, preferably a multi-stage stretching in which the temperature is successively increased. In the case of multi-stage stretching, it is preferable that the stretching temperature includes (Tg + 50) ° C. or less. In the case of multi-stage drawing, the draw ratio of each stage is preferably 1.1 or more, and the total draw ratio is preferably 1.3 to 6, and 2 to 4
Is more preferable. The higher the drawing temperature, the higher the draw ratio of that step.
【００２５】延伸により形成された多孔質膜は、熱固定
を施すことにより寸法安定性と耐熱性を付与する事が好
ましい。熱処理温度は重合体のＴｇ以上Ｔｍ以下であり
かつ延伸温度より高い温度である。The porous membrane formed by stretching is preferably heat-fixed to impart dimensional stability and heat resistance. The heat treatment temperature is not lower than Tg and not higher than Tm of the polymer and higher than the stretching temperature.
【００２６】形成された多孔質膜の寸法は任意である
が、中空糸膜にあっては外径０．０５〜３ｍｍ、厚み
０．００５〜０．５ｍｍ、フィルム状膜では厚み０．０
１〜１ｍｍ、管状膜では直径３〜１０００ｍｍが好まし
い。いずれの多孔質膜に於ても、細孔の平均孔径０．０
１〜１０μｍであることが好ましい。The size of the formed porous membrane is arbitrary, but in the hollow fiber membrane, the outer diameter is 0.05 to 3 mm, the thickness is 0.005 to 0.5 mm, and the thickness of the film membrane is 0.0.
It is preferably 1 to 1 mm, and the diameter of the tubular membrane is 3 to 1000 mm. In any of the porous membranes, the average pore diameter is 0.0
It is preferably 1 to 10 μm.
【００２７】[0027]
【実施例】以下実施例により本発明をさらに具体的に説
明するが、これにより本発明が制限されるものではな
い。 ［実施例１］ ＜中空糸膜の製造＞結晶性熱可塑性重合体としてポリ−
４−メチルペンテン−１（三井石油化学工業（株）製、
ＴＰＸ−ＲＴ−１８）を使用し、６ホ−ルの外径６ｍｍ
円環型紡糸ノズルを用いて、紡糸温度２７５℃にて溶融
紡糸した。この時、円環型紡糸ノズルから重合体を押し
出し、円環の内側に設けられた芯剤導入孔から酸素濃度
０．０１モル％未満の窒素を導入して、ドラフト５００
で引き取りつつ、紡糸筒のノズル下３〜２３ｃｍの範囲
から、膜式酸素富化装置で作製した酸素濃度７モル％の
窒素富化空気を０．１ｍ／秒で吹送することにより冷却
して中空糸を巻き取った。この中空糸を１９５℃の空気
浴中で３分間熱処理したのち、３５℃にて延伸倍率１．
３、次いで１３０℃にて延伸倍率１．８だけ延伸し、そ
の後１９５℃の空気浴中に１分間滞留させることにより
熱固定を行い、中空糸膜を得た。The present invention will be described in more detail with reference to the following examples, which should not be construed as limiting the present invention. [Example 1] <Production of hollow fiber membrane> Poly- as a crystalline thermoplastic polymer
4-methylpentene-1 (manufactured by Mitsui Petrochemical Industry Co., Ltd.,
TPX-RT-18), 6-hole outer diameter 6 mm
Melt-spinning was performed at a spinning temperature of 275 ° C. using an annular spinning nozzle. At this time, the polymer was extruded from the annular spinning nozzle, and nitrogen having an oxygen concentration of less than 0.01 mol% was introduced from a core agent introducing hole provided inside the annular ring to prepare a draft 500.
While blowing in, the nitrogen-enriched air with an oxygen concentration of 7 mol% produced by a membrane oxygen enricher was blown at a rate of 0.1 m / sec from a range of 3 to 23 cm below the nozzle of the spinning tube to cool and hollow. I wound up the thread. This hollow fiber was heat treated in an air bath at 195 ° C. for 3 minutes, and then stretched at 35 ° C. to a draw ratio of 1.
3, then, drawn at a draw ratio of 1.8 at 130 ° C., and then heat-set by being retained in an air bath at 195 ° C. for 1 minute to obtain a hollow fiber membrane.
【００２８】得られた中空糸膜の寸法は外径２６６μ
ｍ、内径２０８μｍであり、走査型電子顕微鏡（ＳＥ
Ｍ）にて観察したところ、内表面には全面に長径約０．
１μｍ、短径約０．０３μｍの細孔が密に存在し、外表
面には全面に長径約０．１５μｍ、短径約０．０４μｍ
の細孔が、内表面より存在密度はやや低いものの、密に
存在した。また中空糸を斜めに切断した断面には全体に
長径約０．０６μｍ、短径約０．０４μｍの細孔が密に
存在した。また、水銀圧入法で測定した孔径分布のピー
クは０．０３６μｍであった。この中空糸膜の窒素透過
速度は、２５℃、圧力差１ｋｇｆ／ｃｍ2 において３
３．４［Ｎｍ3／ｍ2（外表面積），ｈｒ］であった。な
お、重合体（ＴＰＸ−ＲＴ−１８）について、３００℃
で作製した溶融プレスフィルムを１９０℃にて３０分熱
処理したサンプルの、Ｘ線回折法により測定された結晶
化度は約５５％であった。The obtained hollow fiber membrane has an outer diameter of 266 μ.
m, inner diameter 208 μm, scanning electron microscope (SE
As a result of observation with (M), the inner surface has a major axis of about 0.
There are dense pores with a diameter of 1 μm and a minor axis of about 0.03 μm, and a major axis of about 0.15 μm and a minor axis of about 0.04 μm on the entire outer surface.
The pores were densely present, though the existence density was slightly lower than the inner surface. Further, in the cross section obtained by obliquely cutting the hollow fiber, pores having a major axis of about 0.06 μm and a minor axis of about 0.04 μm were densely present on the whole. The peak of the pore size distribution measured by the mercury porosimetry was 0.036 μm. The nitrogen permeation rate of this hollow fiber membrane was 3 at a temperature difference of 25 ° C. and a pressure difference of 1 kgf / cm 2 .
It was 3.4 [Nm 3 / m 2 (external surface area), hr]. The temperature of the polymer (TPX-RT-18) was 300 ° C.
The crystallinity of the sample obtained by subjecting the melt-pressed film produced in 1. above to heat treatment at 190 ° C. for 30 minutes was about 55% as measured by X-ray diffractometry.
【００２９】［実施例２］冷却用気体として、紡糸筒の
ノズル下３〜１０ｃｍの範囲から、膜式窒素富化装置に
より製造した酸素濃度７モル％の窒素富化空気を風速
０．１ｍ／秒で吹送し、１５〜４５ｃｍの範囲から空気
を風速０．１ｍ／秒で吹送したこと以外は実施例１と同
様にして中空糸多孔質膜を作製した。この時、ノズル下
０〜５ｃｍの範囲の酸素濃度は７モル％であった。また
中空糸の固化点はノズル下５ｃｍであった。 得られた
中空糸膜の寸法および細孔径は実施例１と同様であっ
た。実施例１と同様にして測定したこの中空糸膜の窒素
透過速度は、３５．０［Ｎｍ3／ｍ2（外表面積），ｈ
ｒ］であった。[Example 2] As a cooling gas, nitrogen-enriched air with an oxygen concentration of 7 mol% produced by a membrane-type nitrogen-enriching device was blown from a range of 3 to 10 cm below the nozzle of the spinning tube at a wind speed of 0.1 m / m. A hollow fiber porous membrane was produced in the same manner as in Example 1 except that the air was blown at a rate of 0.1 m / sec from the range of 15 to 45 cm. At this time, the oxygen concentration in the range of 0 to 5 cm below the nozzle was 7 mol%. The solidification point of the hollow fiber was 5 cm below the nozzle. The dimensions and pore size of the obtained hollow fiber membrane were the same as in Example 1. The nitrogen permeation rate of this hollow fiber membrane measured in the same manner as in Example 1 was 35.0 [Nm 3 / m 2 (external surface area), h
r].
【００３０】［実施例３］芯剤および冷却用気体とし
て、膜式窒素富化装置により製造した酸素濃度７モル％
の窒素富化空気を使用したこと以外は実施例１と同様に
して中空糸多孔質膜を作製した。[Example 3] As a core agent and a cooling gas, an oxygen concentration of 7 mol% produced by a membrane type nitrogen enrichment apparatus was used.
A hollow fiber porous membrane was produced in the same manner as in Example 1 except that the nitrogen-enriched air of 1 was used.
【００３１】得られた中空糸膜の寸法は、外径約２６４
μｍ、内径約２０５μｍであり、ＳＥＭにて観察した細
孔径は実施例１と同様であった。実施例１と同様にして
測定したこの中空糸膜の窒素透過速度は、３２．５［Ｎ
ｍ3／ｍ2（外表面積），ｈｒ］であった。The size of the obtained hollow fiber membrane has an outer diameter of about 264.
μm, inner diameter of about 205 μm, and the pore diameter observed by SEM was the same as in Example 1. The nitrogen permeation rate of this hollow fiber membrane measured in the same manner as in Example 1 was 32.5 [N
m 3 / m 2 (external surface area), hr].
【００３２】［実施例４］冷却用気体として、膜式窒素
富化装置により製造した酸素濃度３モル％の窒素富化空
気を使用したこと以外は実施例１と同様にして中空糸多
孔質膜を作製した。得られた中空糸膜の寸法および細孔
径は実施例１と同様であった。実施例１と同様にして測
定したこの中空糸膜の窒素透過速度は、３８．１［Ｎｍ
3／ｍ2（外表面積），ｈｒ］であった。[Example 4] A hollow fiber porous membrane was prepared in the same manner as in Example 1 except that nitrogen-enriched air having an oxygen concentration of 3 mol% produced by a membrane-type nitrogen enricher was used as a cooling gas. Was produced. The dimensions and pore size of the obtained hollow fiber membrane were the same as in Example 1. The nitrogen permeation rate of this hollow fiber membrane measured in the same manner as in Example 1 was 38.1 [Nm.
3 / m 2 (outer surface area), hr].
【００３３】［比較例１］冷却用気体として空気を使用
したこと以外は実施例１と同様にして中空糸膜を作製し
た。得られた中空糸膜の寸法は実施例１と同様であっ
た。ＳＥＭにて観察したところ、内表面には全面に長径
約０．１μｍ、短径約０．０３μｍの細孔が密に存在
し、外表面には長径約０．２μｍ、短径約０．０７μｍ
の細孔が多数存在したが、部分的に細孔の全く存在しな
い範囲も観察された。また中空糸を斜めに切断した断面
には全体に長径約０．０６μｍ、短径約０．０４μｍの
細孔が密に存在した。実施例１と同様にして測定したこ
の中空糸膜の窒素透過速度は、２２．３［Ｎｍ3／ｍ
2（外表面積），ｈｒ］であった。Comparative Example 1 A hollow fiber membrane was prepared in the same manner as in Example 1 except that air was used as the cooling gas. The dimensions of the obtained hollow fiber membrane were the same as in Example 1. As a result of SEM observation, pores having a major axis of about 0.1 μm and a minor axis of about 0.03 μm were densely present on the entire inner surface, and a major axis of about 0.2 μm and a minor axis of about 0.07 μm were present on the outer surface.
Although a large number of pores were present, a range in which no pores exist at all was also observed. Further, in the cross section obtained by obliquely cutting the hollow fiber, pores having a major axis of about 0.06 μm and a minor axis of about 0.04 μm were densely present on the whole. The nitrogen permeation rate of this hollow fiber membrane measured in the same manner as in Example 1 was 22.3 [Nm 3 / m
2 (outer surface area), hr].
【００３４】［比較例２］芯剤および冷却用気体として
空気を使用したこと、および芯剤気体の導入量を若干多
目にし、中空糸の外径を実施例１とほぼ同じ値になるよ
う調節したこと以外は実施例１と同様にして中空糸膜を
作製した。得られた中空糸膜の寸法は、外径約２６７μ
ｍ、内径約２０７μｍであった。ＳＥＭにて観察したと
ころ、内外両表面には長径約０．２μｍ、短径約０．０
６μｍの細孔が多数存在したが、部分的に細孔の全く存
在しない範囲も観察された。一方、中空糸を斜めに切断
した断面には全体に長径約０．０６μｍ、短径約０．０
４μｍの細孔が密に存在した。実施例１と同様にして測
定したこの中空糸膜の窒素透過速度は、１７．７［Ｎｍ
3／ｍ2（外表面積），ｈｒ］であった。[Comparative Example 2] The use of air as the core agent and the cooling gas, and the introduction amount of the core agent gas were slightly increased so that the outer diameter of the hollow fiber was almost the same value as in Example 1. A hollow fiber membrane was produced in the same manner as in Example 1 except that the adjustment was performed. The obtained hollow fiber membrane has an outer diameter of about 267 μ.
m and the inner diameter was about 207 μm. When observed by SEM, the major axis is about 0.2 μm and the minor axis is about 0.0 on both the inner and outer surfaces.
Although a large number of 6 μm pores were present, a region where no pores were present at all was also observed. On the other hand, the cross section obtained by obliquely cutting the hollow fiber has a major axis of about 0.06 μm and a minor axis of about 0.06.
There were dense 4 μm pores. The nitrogen permeation rate of this hollow fiber membrane measured in the same manner as in Example 1 was 17.7 [Nm.
3 / m 2 (outer surface area), hr].
【００３５】[0035]
【発明の効果】多孔質膜の表面などに形成される細孔存
在密度の低い部分の発生を除去でき、液体及び気体の透
過速度の高い多孔質膜が得られる。EFFECTS OF THE INVENTION It is possible to remove the generation of a portion having a low density of pores formed on the surface of a porous membrane, and to obtain a porous membrane having a high liquid and gas permeation rate.
Claims (7)
中に溶融押し出しし、次いで延伸することにより多孔質
化する多孔質膜の製法であって、ノズルから押し出され
た溶融状態にある膜前駆体の一方の面が酸素濃度１〜１
０モル％の気体に接し、他の面が酸素濃度１０モル％以
下の気体に接した状態で冷却固化することを特徴とする
多孔質膜の製造方法。1. A method for producing a porous membrane in which a crystalline thermoplastic polymer is melt-extruded into a gas from a nozzle and then stretched to obtain a porous film, which is a precursor film in a molten state extruded from a nozzle. One side of the body has an oxygen concentration of 1-1
A method for producing a porous film, which comprises cooling and solidifying in a state of being in contact with 0 mol% gas and the other surface being in contact with a gas having an oxygen concentration of 10 mol% or less.
素濃度１０モル％以下の気体が、窒素を主要な気体成分
とする気体である請求項１記載の製造方法。2. The method according to claim 1, wherein the gas having an oxygen concentration of 1 to 10 mol% and the gas having an oxygen concentration of 10 mol% or less are gases containing nitrogen as a main gas component.
を用いて、酸素濃度１０モル％以下の気体を芯剤とし、
酸素濃度１〜１０モル％の気体中に中空糸状に溶融押し
出しする請求項１記載の製造方法。3. A crystalline thermoplastic polymer using a hollow fiber nozzle, using a gas having an oxygen concentration of 10 mol% or less as a core agent,
The production method according to claim 1, wherein the resin is melt-extruded into a hollow fiber shape in a gas having an oxygen concentration of 1 to 10 mol%.
る請求項３記載の製造方法。4. The method according to claim 3, wherein the core agent is a gas having an oxygen concentration of 1 mol% or less.
の窒素富化空気を吹送することにより、ノズル面から少
なくとも溶融状態にある膜前駆体の固化点までの範囲の
酸素濃度を１〜１０モル％に保ち、次に固化点より離れ
た部分に空気を吹送することにより、固化した中空糸を
さらに冷却することを特徴とする請求項４記載の製造方
法。5. The oxygen concentration near the nozzle is 1 to 10 mol%.
By blowing in the nitrogen-enriched air, the oxygen concentration in the range from the nozzle surface to at least the solidification point of the film precursor in the molten state is maintained at 1 to 10 mol%, and then the air is evacuated to the part away from the solidification point. The method according to claim 4, wherein the solidified hollow fiber is further cooled by blowing.
１〜５のいずれかに記載の製造方法。6. The method according to claim 1, wherein the polymer is polyolefin.
合体である請求項６記載の製造方法。7. The method according to claim 6, wherein the polymer is a 4-methylpentene-1 type polymer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30790293A JP3475363B2 (en) | 1993-12-08 | 1993-12-08 | Method for producing porous membrane |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30790293A JP3475363B2 (en) | 1993-12-08 | 1993-12-08 | Method for producing porous membrane |
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| Publication Number | Publication Date |
|---|---|
| JPH07157580A true JPH07157580A (en) | 1995-06-20 |
| JP3475363B2 JP3475363B2 (en) | 2003-12-08 |
Family
ID=17974553
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP30790293A Expired - Fee Related JP3475363B2 (en) | 1993-12-08 | 1993-12-08 | Method for producing porous membrane |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3475363B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6878276B2 (en) | 2001-12-11 | 2005-04-12 | Zenon Environmental Inc. | Methods of making stretched filtering membranes and modules |
| US9643129B2 (en) | 2011-12-22 | 2017-05-09 | Bl Technologies, Inc. | Non-braided, textile-reinforced hollow fiber membrane |
-
1993
- 1993-12-08 JP JP30790293A patent/JP3475363B2/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6878276B2 (en) | 2001-12-11 | 2005-04-12 | Zenon Environmental Inc. | Methods of making stretched filtering membranes and modules |
| US9643129B2 (en) | 2011-12-22 | 2017-05-09 | Bl Technologies, Inc. | Non-braided, textile-reinforced hollow fiber membrane |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3475363B2 (en) | 2003-12-08 |
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