JP4702277B2 - Gas separation membrane and separation method - Google Patents
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本発明は、スキン層と多孔質層とから構成される非対称構造を有するガス分離膜であって、ガスの膜透過成分が多孔質層を透過するときの抵抗を小さくすることによって膜透過成分の膜透過速度を大きくしていること、かつ、中空糸ガス分離膜として実用レベル以上の機械的強度を持っていることを特徴とするガス分離膜に関する。また、前記のガス分離膜を用いた除湿方法に関する。 The present invention is a gas separation membrane having an asymmetric structure composed of a skin layer and a porous layer, wherein the resistance of the membrane permeation component is reduced by reducing the resistance when the gas membrane permeation component permeates the porous layer. The present invention relates to a gas separation membrane characterized in that the membrane permeation rate is increased and the hollow fiber gas separation membrane has mechanical strength higher than a practical level. The present invention also relates to a dehumidification method using the gas separation membrane.
種々のガス分離工程においてガス分離膜が使用されている。これらの多くは、ガス選択透過性が高いガラス状ポリマーで形成されたガス分離膜である。概してガラス状ポリマーはガス選択透過性（分離度）は高いけれども、ガス透過係数が小さいという短所がある。このため、多くのガラス状ポリマーで形成されたガス分離膜は、多孔質層（支持層）と薄いスキン層（分離層）とから構成される非対称構造、すなわちガスの透過抵抗を生じる分離層を薄くして、ガス透過速度が小さくなり過ぎないようにして用いられている。 Gas separation membranes are used in various gas separation processes. Many of these are gas separation membranes formed of a glassy polymer with high gas selective permeability. In general, glassy polymers have high gas selective permeability (separation), but have a disadvantage of low gas permeability coefficient. For this reason, a gas separation membrane formed of many glassy polymers has an asymmetric structure composed of a porous layer (support layer) and a thin skin layer (separation layer), that is, a separation layer that generates a gas permeation resistance. It is used in such a manner that the gas permeation rate does not become too small by reducing the thickness.
ガス分離膜は、通常、多数の中空糸膜からなる中空糸膜束を、少なくとも混合ガスの導入口、透過ガスの排出口、未透過ガスの排出口とを有する容器内に収納して構成される中空糸ガス分離膜モジュールとして用いられる。中空糸ガス分離膜モジュールにおいては、混合ガスは中空糸膜の内側あるいは外側に接する空間へ供給され、中空糸膜に接して流れる間に混合ガス中の特定成分（膜透過成分）が選択的に膜を透過し透過ガスの排出口から回収され、特定成分（膜透過成分）が除かれたガスが非透過ガスの排出口から回収されることによって、ガス分離がおこなわれる。 A gas separation membrane is usually configured by storing a hollow fiber membrane bundle consisting of a number of hollow fiber membranes in a container having at least a mixed gas inlet, a permeate gas outlet, and an unpermeated gas outlet. It is used as a hollow fiber gas separation membrane module. In the hollow fiber gas separation membrane module, the mixed gas is supplied to a space in contact with the inside or outside of the hollow fiber membrane, and a specific component (membrane permeable component) in the mixed gas is selectively selected while flowing in contact with the hollow fiber membrane. Gas separation is performed by collecting the gas that has passed through the membrane and collected from the permeate gas discharge port and from which the specific component (membrane permeation component) has been removed, from the non-permeate gas discharge port.
非対称構造の膜では、膜透過成分が膜を透過する透過速度の律速過程は、スキン層を透過する過程である。多孔質層を透過する過程は透過抵抗が比較的小さいので、膜透過成分が膜を透過する透過速度への影響は、多くの場合、実際上は無視できる。 In a film having an asymmetric structure, the rate-determining process of the permeation rate at which the membrane permeation component permeates the membrane is the process of permeation through the skin layer. Since the permeation resistance in the process of permeating through the porous layer is relatively small, the effect of the membrane permeation component on the permeation rate through the membrane is practically negligible.
ところが、スキン層を極めて薄くして膜透過成分が膜を透過する透過速度を大きくする場合や、膜透過成分の膜を透過する透過速度が極めて大きい場合には、膜透過成分が膜を透過する透過速度は、膜透過成分がスキン層を透過する過程のみならず多孔質層を透過する過程によっても実際上無視できない影響を受ける。この場合には、非対称構造の膜であっても膜透過成分が膜を透過する透過速度は改良の余地があり、これを改良してより高効率でよりコンパクトな高性能ガス分離膜の開発が求められていた。特に、膜透過成分が水蒸気の場合は、水蒸気が膜を透過する透過速度が他の無機ガスに比べて極めて大きい（数百倍から数千倍に達する）ので、膜を透過する水蒸気の透過速度は多孔質層の透過抵抗によって実際上無視できない影響を受けている。このため、水蒸気が多孔質層を透過するときの透過抵抗が小さくなるように改良して、水蒸気が膜を透過する透過速度を大きくした高効率でコンパクトな高性能除湿膜の開発が求められていた。 However, when the skin layer is extremely thin to increase the permeation rate of the membrane permeation component through the membrane, or when the permeation rate of the membrane permeation component through the membrane is extremely high, the membrane permeation component permeates the membrane. The permeation speed is influenced not only by the process of the membrane permeation component permeating through the skin layer but also by the process of permeation through the porous layer. In this case, even if the membrane has an asymmetric structure, there is room for improvement in the permeation rate at which the membrane permeation component permeates the membrane, and this has been improved to develop a high-performance and more compact high-performance gas separation membrane. It was sought after. In particular, when the membrane permeation component is water vapor, the permeation rate at which water vapor permeates through the membrane is extremely large (several hundred to several thousand times) compared to other inorganic gases. Is influenced by the permeation resistance of the porous layer, which cannot be ignored in practice. For this reason, there has been a demand for the development of a highly efficient and compact high-performance dehumidifying membrane that improves the permeation resistance when water vapor passes through the porous layer and increases the permeation rate of water vapor through the membrane. It was.
しかしながら、非対称膜において単に多孔質層の多孔性を高めて膜透過成分が膜を透過するときの透過抵抗をより小さくすることによって膜透過成分が膜を透過する透過速度を大きくしようとすると、透過速度は大きくできるが多孔質層が担うべき膜の支持機能即ち機械的強度が低下するので、向上された透過速度と実用レベルの機械的強度の両方を併せ持つ実用的な高性能ガス分離膜を得ることは困難であった。また、高強度材料の選択によって機械的強度が低下するという課題を解決しようとする試みもあるが、高強度材料は一般的にガス透過係数がより小さいのでこの課題の解決に至っていなかった。 However, if an attempt is made to increase the permeation rate of the membrane permeation component through the membrane by simply increasing the porosity of the porous layer in the asymmetric membrane and reducing the permeation resistance when the membrane permeation component permeates the membrane, Although the speed can be increased, the support function of the membrane, that is, the mechanical strength that the porous layer should bear, is reduced, so that a practical high-performance gas separation membrane having both an improved permeation rate and a practical level of mechanical strength is obtained. It was difficult. In addition, there is an attempt to solve the problem that the mechanical strength is lowered by the selection of a high-strength material, but the high-strength material generally has a smaller gas permeability coefficient, so that this problem has not been solved.
本発明は、この様な状況に鑑みてなされたものであり、本発明者らは、少なくとも１種類のポリイミドを含む２種類以上のポリマーの混合物で非対称膜を形成することによって、多孔質層の膜透過成分が膜を透過するときのガス透過抵抗を小さく（ガス透過速度を大きく）しながら、かつ、膜の機械的強度を実用レベル以上に保持し得ることを見出して本発明に到達した。 The present invention has been made in view of such a situation, and the present inventors have formed a porous film by forming an asymmetric membrane with a mixture of two or more kinds of polymers including at least one kind of polyimide. The present inventors have found that the mechanical strength of the membrane can be maintained at a practical level or more while reducing the gas permeation resistance when the membrane permeation component permeates the membrane (increasing the gas permeation rate).
すなわち、本発明は、スキン層（分離層）と多孔質層（支持層）から構成される非対称構造を有し、水蒸気透過速度（Ｐ’H20）が２．５×１０-3ｃｍ3（ＳＴＰ）／ｃｍ2・ｓｅｃ・ｃｍＨｇ以上で、水蒸気と窒素の透過速度比（Ｐ’H2O／Ｐ’N2）が５０以上である膜において、前記膜の多孔質層（支持層）のヘリウム透過速度（Ｐ’He）が３．０×１０-3ｃｍ3（ＳＴＰ）／ｃｍ2・ｓｅｃ・ｃｍＨｇ以上で、中空糸膜での引張強度が２．５ｋｇｆ／ｍｍ2以上、破断伸度が１０％以上であることを特徴とするガス分離膜に関する。また、少なくとも１種類のポリイミドを含む２種類以上のポリマーの混合物で形成された前記のガス分離膜に関する。更に、前記のガス分離膜を用いた除湿方法に関する。 That is, the present invention has an asymmetric structure composed of a skin layer (separation layer) and a porous layer (support layer), and has a water vapor transmission rate (P ′ H20 ) of 2.5 × 10 −3 cm 3 (STP). ) / Cm 2 · sec · cmHg or more, and in a membrane having a water vapor and nitrogen permeation rate ratio (P ′ H2O / P ′ N2 ) of 50 or more, the helium permeation rate of the porous layer (support layer) of the membrane ( in P 'the He) is 3.0 × 10 -3 cm 3 (STP ) / cm 2 · sec · cmHg or more, tensile strength of the hollow fiber membrane is 2.5 kgf / mm 2 or more, elongation at break of 10% or more The present invention relates to a gas separation membrane. The present invention also relates to the gas separation membrane formed of a mixture of two or more types of polymers including at least one type of polyimide. Furthermore, the present invention relates to a dehumidification method using the gas separation membrane.
前記の膜の水蒸気透過速度（Ｐ’H20）と水蒸気と窒素の透過速度比（Ｐ’H2O／Ｐ’N2）、膜の多孔質層（支持層）のヘリウム透過速度（Ｐ’He）は、５０℃におけるものである。
また、ヘリウム透過速度（Ｐ’He）は膜の多孔質層（支持層）のガス透過抵抗を示すものとして用いており、次のようにして測定した値で規定されるものである。即ち、非対称中空糸膜を酸素プラズマ処理によって表面のスキン層を削り、ヘリウムガスと窒素ガスの透過速度比が実質的に均質膜の透過係数比とは認められない領域に到達したときのヘリウムガスの透過速度（Ｐ’He）である。具体的には、プラズマ処理前のヘリウムと窒素の透過速度比（Ｐ’He／Ｐ’N2）が２０以上の膜をプラズマ処理して、前記透過速度比（Ｐ’He／Ｐ’N2）が１．２以下になったときの、ヘリウムガスの透過速度である。このヘリウム透過速度（Ｐ’He）の値が大きいとその膜の多孔質層のガス透過抵抗が小さいことを意味し、ヘリウム透過速度（Ｐ’He）の値が小さいとその膜の多孔質層のガス透過抵抗が大きいことを意味する。
The water vapor transmission rate (P ′ H20 ) of the membrane and the water vapor / nitrogen transmission rate ratio (P ′ H2O / P ′ N2 ), and the helium transmission rate (P ′ He ) of the porous layer (support layer) of the membrane are It is at 50 ° C.
The helium permeation rate (P ′ He ) is used to indicate the gas permeation resistance of the porous layer (support layer) of the membrane, and is defined by the value measured as follows. That is, the helium gas when the skin layer on the surface of the asymmetric hollow fiber membrane is scraped by oxygen plasma treatment and reaches a region where the transmission rate ratio of helium gas and nitrogen gas is not substantially recognized as the transmission coefficient ratio of the homogeneous membrane. Permeation rate (P ′ He ). Specifically, a film having a transmission rate ratio (P ′ He / P ′ N2 ) of helium and nitrogen before plasma treatment of 20 or more is plasma-treated, and the transmission rate ratio (P ′ He / P ′ N2 ) is This is the permeation rate of helium gas when it becomes 1.2 or less. If the value of this helium permeation rate (P ′ He ) is large, it means that the gas permeation resistance of the porous layer of the membrane is small, and if the value of the helium permeation rate (P ′ He ) is small, the porous layer of the membrane This means that the gas permeation resistance is large.
また、本発明における機械的強度は膜を中空糸としたときの引張強度と破断伸度で表している。これらは温度２３℃にて引張試験機を用いて試料の有効長２０ｍｍ、引張速度１０ｍｍ／分で測定した値である。引張強度は中空糸の引張り破断時の応力を中空糸の断面積で除した値［ｋｇｆ／ｍｍ2］であり、破断伸度は中空糸の元の長さをＬ0、引張り破断時の長さをＬとしたときの（Ｌ−Ｌ0）／Ｌ0×１００の値［％］である。 Further, the mechanical strength in the present invention is represented by the tensile strength and elongation at break when the membrane is a hollow fiber. These are values measured at a temperature of 23 ° C. using a tensile tester at an effective length of the sample of 20 mm and a tensile speed of 10 mm / min. The tensile strength is a value [kgf / mm 2 ] obtained by dividing the stress at the time of tensile break of the hollow fiber by the cross-sectional area of the hollow fiber, and the elongation at break is L 0 , the original length of the hollow fiber, and the length at the time of tensile break This is a value [%] of (L−L 0 ) / L 0 × 100, where L is L.
本発明のガス分離膜は、ガス透過速度をより向上させた非対称膜であり、しかも、実用レベルの機械的強度を有する。このため、本発明のガス分離膜を用いれば、ガス分離速度が向上したより高効率でよりコンパクトな高性能中空糸ガス分離膜モジュールを提供でき、高効率のガス分離を実現できる。また、本発明のガス分離膜は、少なくとも１種類のポリイミドを含む２種類以上のポリマーの混合物で非対称構造を有する膜を形成することで得ることが出来る。 The gas separation membrane of the present invention is an asymmetric membrane with a further improved gas permeation rate, and has a mechanical strength at a practical level. For this reason, if the gas separation membrane of the present invention is used, a more efficient and more compact high-performance hollow fiber gas separation membrane module with improved gas separation speed can be provided, and highly efficient gas separation can be realized. In addition, the gas separation membrane of the present invention can be obtained by forming a membrane having an asymmetric structure with a mixture of two or more types of polymers including at least one type of polyimide.
特に、水蒸気を含む混合ガスから水蒸気を除去する（除湿する）場合には、極めて高効率に、除湿を実施することが可能になる。 In particular, when water vapor is removed (dehumidified) from a mixed gas containing water vapor, dehumidification can be performed with extremely high efficiency.
本発明の透過ガスの透過速度が改良された非対称ガス分離膜は、多孔質層のガス透過抵抗を小さく（ガス透過速度を大きく）した膜であり、しかも、中空糸膜としての機械的強度を実用レベル以上に保持したガス分離膜である。即ち、本発明の非対称ガス分離膜は、多孔質層のガス透過速度がヘリウムガスの透過速度（Ｐ’He）で３．０×１０-3ｃｍ3（ＳＴＰ）／ｃｍ2・ｓｅｃ・ｃｍＨｇ以上となるようにし、かつ、中空糸膜での引張強度が２．５ｋｇｆ／ｍｍ2以上、破断伸度が１０％以上とすることによって、水蒸気透過速度（Ｐ’H20）が２．５×１０-3ｃｍ3（ＳＴＰ）／ｃｍ2・ｓｅｃ・ｃｍＨｇ以上の高い透過速度を持ち、かつ、中空糸膜としての優れた耐圧性と工業的に分離膜モジュールへの加工が可能な実用レベルの機械的強度を持つ非対称構造を有するガス分離膜である。 The asymmetric gas separation membrane with improved permeation rate of the permeated gas of the present invention is a membrane in which the gas permeation resistance of the porous layer is reduced (the gas permeation rate is increased), and the mechanical strength as a hollow fiber membrane is increased. It is a gas separation membrane that is maintained at a practical level or higher. That is, in the asymmetric gas separation membrane of the present invention, the gas permeation rate of the porous layer is 3.0 × 10 −3 cm 3 (STP) / cm 2 · sec · cmHg or more in terms of the helium gas permeation rate (P ′ He ). And the tensile strength at the hollow fiber membrane is 2.5 kgf / mm 2 or more and the elongation at break is 10% or more, so that the water vapor transmission rate (P ′ H20 ) is 2.5 × 10 − It has a high permeation rate of 3 cm 3 (STP) / cm 2 · sec · cmHg or more, has excellent pressure resistance as a hollow fiber membrane, and can be industrially processed into a separation membrane module. It is a gas separation membrane having an asymmetric structure with strength.
膜の多孔質層のガス透過速度が、ヘリウムガスの透過速度（Ｐ’He）で３．０×１０-3ｃｍ3（ＳＴＰ）／ｃｍ2・ｓｅｃ・ｃｍＨｇ以上、好ましくは３．５×１０-3ｃｍ3（ＳＴＰ）／ｃｍ2・ｓｅｃ・ｃｍＨｇ以上であれば、多孔質層のガス透過抵抗が小さいので、膜の透過速度への影響が少なくなるか実質的に無視できるようになり、膜の水蒸気透過速度（Ｐ’H20）が２．５×１０-3ｃｍ3（ＳＴＰ）／ｃｍ2・ｓｅｃ・ｃｍＨｇ以上のものが得られる。逆に多孔質層のガス透過速度がヘリウムガスの透過速度（Ｐ’He）で３．０×１０-3ｃｍ3（ＳＴＰ）／ｃｍ2・ｓｅｃ・ｃｍＨｇ以下であると、多孔質層のガス透過抵抗が大きいので、膜のガス透過速度が小さくなり、改良された水蒸気透過速度を持つ高性能ガス分離膜を得ることは出来ない。 The gas permeation rate of the porous layer of the membrane is 3.0 × 10 −3 cm 3 (STP) / cm 2 · sec · cmHg or more, preferably 3.5 × 10 6 in terms of helium gas permeation rate (P ′ He ). If it is −3 cm 3 (STP) / cm 2 · sec · cmHg or more, since the gas permeation resistance of the porous layer is small, the influence on the permeation rate of the membrane is reduced or can be substantially ignored. A film having a water vapor transmission rate (P ′ H20 ) of 2.5 × 10 −3 cm 3 (STP) / cm 2 · sec · cmHg or more can be obtained. Conversely, if the gas permeation rate of the porous layer is 3.0 × 10 −3 cm 3 (STP) / cm 2 · sec · cmHg or less in terms of the helium gas permeation rate (P ′ He ), Since the permeation resistance is large, the gas permeation rate of the membrane becomes small, and a high-performance gas separation membrane having an improved water vapor permeation rate cannot be obtained.
また、中空糸膜での引張強度が２．５ｋｇｆ／ｍｍ2以上、好ましくは３．０ｋｇｆ／ｍｍ2以上であり、且つ、破断伸度が１０％以上あれば、中空糸膜をモジュール化するときに容易に破断することなく取扱いが可能になり、工業的に加工することが出来きる。更に、前記の引張強度があれば中空糸膜モジュールとして優れた耐圧性を有するので有用なガス分離膜になる。一方、引張強度が２．５ｋｇｆ／ｍｍ2以下、あるいは、破断伸度が１０％以下であると、加工時に中空糸膜が破断し易くなるので工業的に分離膜モジュールへ加工することが困難になり、更に、中空糸膜モジュールとしても耐圧性が低くなり用途や使用条件が限定されるので有用なガス分離膜モジュールではなくなる。 Further, when the hollow fiber membrane is modularized if the tensile strength of the hollow fiber membrane is 2.5 kgf / mm 2 or more, preferably 3.0 kgf / mm 2 or more and the elongation at break is 10% or more. Can be handled easily without breaking, and can be industrially processed. Furthermore, if it has the said tensile strength, since it has the pressure | voltage resistance outstanding as a hollow fiber membrane module, it will become a useful gas separation membrane. On the other hand, if the tensile strength is 2.5 kgf / mm 2 or less, or the breaking elongation is 10% or less, the hollow fiber membrane is easily broken during processing, making it difficult to process into a separation membrane module industrially. Furthermore, the pressure resistance of the hollow fiber membrane module is low, and the usage and use conditions are limited. Therefore, the hollow fiber membrane module is not a useful gas separation membrane module.
水蒸気と窒素の透過速度比（Ｐ’H2O／Ｐ’N2）が５０以上のガス分離膜は、ガスの選択透過性が実用レベル以上にあることを意味し、特に水蒸気を選択的に除去して−１５℃以下の露点を持つ乾燥空気を容易に得ることが出来るので除湿膜として有用である。 A gas separation membrane having a permeation rate ratio of water vapor to nitrogen ( P'H2O / P'N2 ) of 50 or more means that the gas selective permeability is more than a practical level. Since dry air having a dew point of −15 ° C. or lower can be easily obtained, it is useful as a dehumidifying film.
本発明のガス分離膜は、少なくとも１種類のポリイミドを含む２種類以上のポリマーの混合物で膜を形成することで得ることが可能であり、好ましくは、２種類以上のポリイミドの混合物で膜を形成することで得ることが可能である。１種類のポリイミドで多孔質層の多孔性を高めるとガス透過速度は改良出来るが機械的強度が低下するので、本発明のガス分離膜を得ることは出来ない。尚、前記の１種類のポリイミドとは、同一のモノマー組成が繰り返し単位として化学結合（重合）しているポリイミドである。従って、複数種のモノマー組成が繰り返し単位として化学結合（共重合）したポリイミドも、１種類のポリイミドである。また、本発明において、ポリイミド以外のポリマーは特に限定されないが、芳香族ポリアミド、芳香族ポリアミドイミド、芳香族ポリスルホン、芳香族ポリカーボネートなどを挙げることができる。 The gas separation membrane of the present invention can be obtained by forming a membrane with a mixture of two or more types of polymers containing at least one type of polyimide, and preferably forms a membrane with a mixture of two or more types of polyimides. Can be obtained. Increasing the porosity of the porous layer with one kind of polyimide can improve the gas permeation rate, but the mechanical strength decreases, so the gas separation membrane of the present invention cannot be obtained. The one type of polyimide is a polyimide in which the same monomer composition is chemically bonded (polymerized) as a repeating unit. Therefore, a polyimide in which a plurality of types of monomer compositions are chemically bonded (copolymerized) as a repeating unit is also one type of polyimide. In the present invention, the polymer other than polyimide is not particularly limited, and examples thereof include aromatic polyamide, aromatic polyamideimide, aromatic polysulfone, and aromatic polycarbonate.
本発明で用いるポリマー混合物は、少なくとも１種類の高いガス選択透過性を持つポリイミドと、少なくとも１種類のガス分離特性を持ち優れた機械的強度を持つポリイミドあるいはポリイミド以外のポリマーを含む混合物である。これらのポリマー混合物は同一の溶媒に均一に溶解し得るものである。本発明のガス分離膜は、前記のポリマー混合物の溶液を用いて、Ｌｏｅｂらが提案（例えば、米国特許３，１３３，１３２号）した方法、即ち、ポリマー溶液をノズルから押し出して目的形状物とし空気または窒素浴空間を通過させた後で凝固浴に浸漬する、いわゆる乾湿式法により製造することが出来る。乾湿式法では凝固過程においてノズルから目的形状に押し出されたポリマー溶液から溶媒が除去されて多孔質構造が形成されるが、本発明のポリマー混合物溶液の場合には、少なくとも１種類のポリイミドを含む２種類以上のポリマーの混合物間で少なくとも分子鎖レベルで不均一化或いは相分離が進行して、より多孔性が高められながら機械的強度の低下は抑制されると推定される。ポリマー混合物でなくポリマー混合物と同一のモノマー組成からなる１種類の共重合ポリマーを用いて膜を形成しても、改良されたガス透過速度と実用レベルの機械的強度の両方を併せ持つガス分離膜を得ることは出来ない。 The polymer mixture used in the present invention is a mixture containing at least one polyimide having a high gas selective permeability and at least one polymer having a gas separation property and excellent mechanical strength, or a polymer other than polyimide. These polymer mixtures can be uniformly dissolved in the same solvent. The gas separation membrane of the present invention is a method proposed by Loeb et al. (For example, U.S. Pat. No. 3,133,132) using a solution of the above polymer mixture, that is, a polymer solution is extruded from a nozzle to obtain a desired shape. It can be produced by a so-called dry-wet method in which it is immersed in a coagulation bath after passing through air or a nitrogen bath space. In the dry-wet method, the solvent is removed from the polymer solution extruded into the target shape from the nozzle in the solidification process to form a porous structure. In the case of the polymer mixture solution of the present invention, at least one polyimide is included. It is presumed that heterogeneity or phase separation proceeds at least at the molecular chain level between a mixture of two or more kinds of polymers, and a decrease in mechanical strength is suppressed while further increasing the porosity. Even if a membrane is formed using one type of copolymer having the same monomer composition as the polymer mixture instead of the polymer mixture, a gas separation membrane having both an improved gas permeation rate and a practical level of mechanical strength. I can't get it.
本特許のガス分離膜の製造方法は、より詳しくは次のとおりである。即ち、１種類のポリイミドを含む２種類以上のポリマーを同一溶媒に溶解したポリマー混合物溶液を調製し、これをノズルから中空糸状などの目的とする形状に吐出させ、吐出直後に空気あるいは窒素雰囲気中を通したあと、ポリマー混合物を実質的には溶解せず、しかも、ポリマー混合物溶液の溶媒と相溶性を有する凝固液に浸漬して、非対称構造を形成し、その後乾燥、加熱工程を経て分離膜を製造する。ポリマー混合物溶液は、１種類のポリイミドを含む２種類以上のポリマーの溶液を別々に調製後それらを混合しても良いし、１種類のポリイミドを含む２種類以上のポリマーを順次同一溶液に溶解しても良い。ポリマー混合物溶液の濃度は１０〜２０重量％が製膜上好ましい。また、ノズルから吐出させるポリマー混合物溶液の溶液粘度（回転粘度）は、吐出温度で５０〜１５０００ポイズ、特に１００〜１００００ポイズが中空糸状などの吐出後の形状を安定に得ることが出来るので好ましい。凝固液への浸漬は、一次凝固液に浸漬して中空糸状などの膜の形状が保持できる程度に凝固した後、案内ロールに巻き取られ、次いで二次凝固液に浸漬して膜全体を十分に凝固させることが好ましい。凝固液の乾燥は置換溶媒を用いて凝固液と置換した後乾燥する方法が効率的である。熱処理は用いられている１種類のポリイミドを含む２種類以上のポリマーの軟化点又は二次転移点よりも低い温度で実施されることが好ましい。 The manufacturing method of the gas separation membrane of this patent is as follows in more detail. That is, a polymer mixture solution in which two or more kinds of polymers including one kind of polyimide are dissolved in the same solvent is prepared, and this is discharged from a nozzle into a desired shape such as a hollow fiber shape. After passing, the polymer mixture is not substantially dissolved, and it is immersed in a coagulating liquid having compatibility with the solvent of the polymer mixture solution to form an asymmetric structure, and then subjected to a drying and heating step to a separation membrane. Manufacturing. The polymer mixture solution may be prepared by separately preparing two or more types of polymer solutions containing one type of polyimide, or by dissolving two or more types of polymers containing one type of polyimide sequentially in the same solution. May be. The concentration of the polymer mixture solution is preferably 10 to 20% by weight for film formation. Further, the solution viscosity (rotational viscosity) of the polymer mixture solution discharged from the nozzle is preferably 50 to 15000 poise, particularly 100 to 10000 poise at the discharge temperature, because the shape after discharge such as a hollow fiber shape can be stably obtained. For immersion in the coagulation liquid, the film is immersed in the primary coagulation liquid and solidified to such an extent that the shape of the membrane such as a hollow fiber can be maintained, wound on a guide roll, and then immersed in the secondary coagulation liquid to fully saturate the entire film. It is preferable to solidify. For drying the coagulating liquid, a method of drying after replacing the coagulating liquid with a substitution solvent is efficient. The heat treatment is preferably performed at a temperature lower than the softening point or the second order transition point of two or more kinds of polymers including one kind of polyimide used.
本発明のガス分離膜のスキン層の厚さは１０〜２００ｎｍであり、好ましくは２０〜１００ｎｍである。また、本発明のガス分離膜の多孔質層の厚さは２０〜２００μｍであり、好ましくは３０〜１００μｍである。スキン層の厚さが１０ｎｍ以下は製造が困難であり、２００ｎｍ以上にするとガス透過速度が小さくなる。また、多孔質層が２０μｍ以下では機械的強度が小さくなって支持機能が果たせなくなり、２００μｍ以上になると多孔質層のガスの透過抵抗が大きくなり改良されたガス透過速度を得られなくなる。 The thickness of the skin layer of the gas separation membrane of the present invention is 10 to 200 nm, preferably 20 to 100 nm. The thickness of the porous layer of the gas separation membrane of the present invention is 20 to 200 μm, preferably 30 to 100 μm. Manufacturing is difficult when the thickness of the skin layer is 10 nm or less, and when the thickness is 200 nm or more, the gas permeation rate decreases. Further, when the porous layer is 20 μm or less, the mechanical strength becomes small and the supporting function cannot be achieved. When the porous layer is 200 μm or more, the gas permeation resistance of the porous layer becomes large and an improved gas permeation rate cannot be obtained.
本発明のガス分離膜は、中空糸膜として好適に用いられるが、中空糸膜の内径は３０〜５００μｍのものが好適である。また、本発明の中空糸膜は通常の分離膜モジュールとして好適に用いることが出来る。例えば、中空糸膜は適当な長さに切断したものが１００〜２０００００本程度束ねられ、中空糸の端部が開口状態を保持した状態で両端部を熱硬化性樹脂などからなる管板で固着され、少なくとも混合ガス導入口と透過ガス排出口と未透過ガス排出口とを備える容器内に収納され、管板は容器内の空間を隔絶するようにＯ−リングや接着剤などによって容器に密閉して取り付けられる。供給される混合ガスは、中空糸膜の内側あるいは外側に接する空間へ供給され、中空糸膜に接して流れる間に混合ガス中の特定成分が選択的に膜を透過し、ガス分離が行われる。 The gas separation membrane of the present invention is suitably used as a hollow fiber membrane, and the hollow fiber membrane preferably has an inner diameter of 30 to 500 μm. The hollow fiber membrane of the present invention can be suitably used as a normal separation membrane module. For example, about 100 to 200,000 hollow fiber membranes cut to an appropriate length are bundled, and both ends are fixed with tube plates made of thermosetting resin or the like while the end of the hollow fiber is kept open. And is housed in a container having at least a mixed gas inlet, a permeate gas outlet, and a non-permeate gas outlet, and the tube plate is sealed to the container with an O-ring or an adhesive so as to isolate the space in the container. Can be attached. The supplied mixed gas is supplied to a space in contact with the inside or outside of the hollow fiber membrane, and specific components in the mixed gas selectively permeate the membrane while flowing in contact with the hollow fiber membrane, and gas separation is performed. .
本発明のガス分離膜を用いて水蒸気を分離する場合、即ち、除湿をおこなう場合、前記のガス分離膜モジュールに、水蒸気を含有する混合ガスを中空糸膜の内側あるいは外側に接する空間へ供給し、水蒸気を選択的に膜の透過側へ透過し、未透過ガスとして除湿されたガスを極めて効率よく得ることが出来る。 When water vapor is separated using the gas separation membrane of the present invention, that is, when dehumidification is performed, a mixed gas containing water vapor is supplied to the gas separation membrane module to a space in contact with the inside or outside of the hollow fiber membrane. Water vapor can be selectively permeated to the permeate side of the membrane, and a dehumidified gas as an unpermeated gas can be obtained very efficiently.
次に、本発明における中空糸ガス分離膜の製造とその特性について具体的に説明する。尚、本発明は実施例に限定されるものではない。 Next, the production and characteristics of the hollow fiber gas separation membrane in the present invention will be specifically described. In addition, this invention is not limited to an Example.
（ポリマー濃度が１２重量％のポリイミドＡ溶液の調製）３，３’，４，４’−ビフェニルテトラカルボン酸二無水物（以下、ｓ−ＢＰＤＡ）２９．４２２ｇと、２，２’−ビス（３，４−ジカルボキシフェニル）ヘキサフルオロプロパン二無水物（以下、６ＦＤＡ）４４．２０２ｇと、ジメチル−３，７−ジアミノ−−ジベンゾチオフェン−５，５−ジオキシド（以下、ＴＳＮ）５４．８６８ｇを、溶媒のパラクロロフェノール（以下、ＰＣＰ）８８９．４２ｇと共にセパラブルフラスコ中にて重合温度１８０℃で４時間重合し、回転粘度が１５００ポイズ、ポリマー濃度が１２重量％のポリイミドＡ溶液を得た。 (Preparation of a polyimide A solution having a polymer concentration of 12% by weight) 29.422 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (hereinafter referred to as s-BPDA) and 2,2′-bis ( 3,4-dicarboxyphenyl) hexafluoropropane dianhydride (hereinafter 6FDA) 44.202 g and dimethyl-3,7-diamino-dibenzothiophene-5,5-dioxide (hereinafter TSN) 54.868 g. Polymerization was performed for 4 hours at a polymerization temperature of 180 ° C. in a separable flask together with 889.42 g of parachlorophenol (hereinafter referred to as PCP) as a solvent to obtain a polyimide A solution having a rotational viscosity of 1500 poise and a polymer concentration of 12% by weight. .
（ポリマー濃度１３重量％のポリイミドＢ溶液の調製）ｓ−ＢＰＤＡ２８．２４５ｇと、ＴＳＮ２４．６９１ｇと、４，４’−ジアミノジフェニルエーテル（以下、４，４’ＤＡＤＥ）２．００２ｇを、溶媒のＰＣＰ３４３．５４ｇと共にセパラブルフラスコ中にて重合温度１８０℃で４時間重合し、回転粘度が１５００ポイズ、ポリマー濃度が１３重量％のポリイミドＢ溶液を得た。 (Preparation of a polyimide B solution having a polymer concentration of 13% by weight) 28.245 g of s-BPDA, 24.691 g of TSN, and 2.002 g of 4,4′-diaminodiphenyl ether (hereinafter, 4,4′DADE) were added to PCP343. Polymerization was carried out together with 54 g in a separable flask at a polymerization temperature of 180 ° C. for 4 hours to obtain a polyimide B solution having a rotational viscosity of 1500 poise and a polymer concentration of 13% by weight.
（ポリマー濃度１０重量％のポリイミドＢ溶液の調製）ｓ−ＢＰＤＡ２８．２４５ｇと、ＴＳＮ２４．６９１ｇと、４，４’−ジアミノジフェニルエーテル（以下、４，４’ＤＡＤＥ）２．００２ｇを、溶媒のＰＣＰ４６３．３４ｇと共にセパラブルフラスコ中にて重合温度１８０℃で２０時間重合し、回転粘度が１０００ポイズ、ポリマー濃度が１０重量％のポリイミドＢ溶液を得た。 (Preparation of a polyimide B solution having a polymer concentration of 10% by weight) 28.245 g of s-BPDA, 24.691 g of TSN, and 2.002 g of 4,4′-diaminodiphenyl ether (hereinafter, 4,4′DADE) were added to a PCP463. Polymerization was carried out together with 34 g in a separable flask at a polymerization temperature of 180 ° C. for 20 hours to obtain a polyimide B solution having a rotational viscosity of 1000 poise and a polymer concentration of 10% by weight.
（ポリマー濃度１２重量％のポリイミドＣ溶液の調製）Ｓ−ＢＰＤＡ２９．４２２ｇと、６ＦＤＡ４４．２０２ｇと、ＴＳＮ２７．４３４ｇと、２，２’，５，５’−テトラクロロ−４，４’−ジアミノビフェニル（ＴＣＢ）３２．２２０ｇを、溶媒のＰＣＰ９２４．５７ｇと共にセパラブルフラスコ中にて重合温度１８０℃で８時間重合し、回転粘度が１２００ポイズ、ポリマー濃度１２重量％のポリイミドＣ溶液を得た。 (Preparation of a polyimide C solution having a polymer concentration of 12% by weight) 29.422 g of S-BPDA, 44.202 g of 6FDA, 27.434 g of TSN, 2,2 ′, 5,5′-tetrachloro-4,4′-diaminobiphenyl 32.220 g of (TCB) was polymerized in a separable flask together with 924.57 g of PCP for 8 hours at a polymerization temperature of 180 ° C. to obtain a polyimide C solution having a rotational viscosity of 1200 poise and a polymer concentration of 12% by weight.
（ポリマー濃度１２．３重量％のポリイミドＤ溶液の調製）ｓ−ＢＰＤＡ１９．１２４ｇと、６ＦＤＡ１５．３１５ｇと、ＴＳＮ２６．６１１ｇとＤＡＤＥ０．６０１ｇとを、溶媒のＰＣＰ４１３．８８ｇと共にセパラブルフラスコ中に加えて、１８０℃で攪拌しながら４時間重合し、回転粘度１３００ポイズ、ポリマー濃度１２．３重量％のポリイミドＤ溶液を得た。このポリイミドＤのモノマー成分の組成はポリイミドＡとポリイミドＢを等量混合した混合物のモノマー成分の組成とほぼ同一のものである。 (Preparation of polyimide D solution having a polymer concentration of 12.3% by weight) 19.124 g of s-BPDA, 15.315 g of 6FDA, 26.611 g of TSN, and 0.601 g of DADE were added to a separable flask together with 413.88 g of PCP as a solvent. Polymerization was carried out for 4 hours while stirring at 180 ° C. to obtain a polyimide D solution having a rotational viscosity of 1300 poise and a polymer concentration of 12.3% by weight. The composition of the monomer component of polyimide D is almost the same as the composition of the monomer component of a mixture in which equal amounts of polyimide A and polyimide B are mixed.
（非対称中空糸膜の製造方法）ポリイミド溶液、または、ポリイミド混合物溶液を、４００メッシュの金網で濾過したあと、中空糸紡糸ノズル（円形開口部外径１０００μｍ、円形開口部スリット幅２００μｍ、芯部開口部外径４００μｍ）から吐出させ、吐出した中空糸状体を窒素雰囲気中に通した後、０℃の７２重量％エタノール水溶液からなる凝固液に浸漬し湿潤糸とした。これを５０℃のエタノール中に２時間浸漬し脱溶媒処理を完了し、更に、７０℃のイソオクタン中に３時間浸漬洗浄して溶媒を置換後、１００℃絶乾状態まで乾燥し、その後２５０℃で１時間の熱処理を行った。更に、中空糸膜の表面の滑りを整えるためにシリコンオイルでオイリング処理を施し中空糸膜を製造した。得られた中空糸膜はいずれも、外径寸法４７０μｍ、内径寸法３２０μｍ、膜厚７５μｍのものであった。 (Method for Producing Asymmetric Hollow Fiber Membrane) After filtering a polyimide solution or a polyimide mixture solution through a 400 mesh wire mesh, a hollow fiber spinning nozzle (circular opening outer diameter 1000 μm, circular opening slit width 200 μm, core opening) The hollow fiber-like body was discharged from a part outer diameter of 400 μm, passed through a nitrogen atmosphere, and then immersed in a coagulation liquid composed of a 72 wt% aqueous ethanol solution at 0 ° C. to obtain a wet thread. This was immersed in ethanol at 50 ° C. for 2 hours to complete the solvent removal treatment, and further washed by immersion in 70 ° C. isooctane for 3 hours to replace the solvent, and then dried to 100 ° C. and then dried to 250 ° C. Then, heat treatment was performed for 1 hour. Further, an oiling treatment was performed with silicone oil to prepare a hollow fiber membrane in order to adjust the slip of the surface of the hollow fiber membrane. The obtained hollow fiber membranes all had an outer diameter of 470 μm, an inner diameter of 320 μm, and a film thickness of 75 μm.
（中空糸膜の水蒸気透過性能の測定方法）約１０本の中空糸膜と、ステンレスパイプと、エポキシ樹脂系接着剤とを使用して有効長が２０ｍｍの透過性能評価用のエレメントを作成し、これをステンレス容器に装着してペンシルモジュールとした。このペンシルモジュールの中空糸の外側へ水蒸気量１５００ｐｐｍの窒素ガスを一定量供給し、透過側へは一定量のキャリアガス（Ａｒガス）を流しながら水蒸気分離をおこない、未透過ガス及び透過ガスの水蒸気量を鏡面式の露点計で検出した。測定した水蒸気量（水蒸気分圧）と供給ガス量及び有効膜面積から膜の水蒸気透過速度を算出した。尚、これらの測定は５０℃でおこなった。 (Measuring method of water vapor transmission performance of hollow fiber membrane) Using about 10 hollow fiber membranes, a stainless steel pipe, and an epoxy resin-based adhesive, an element for evaluating permeation performance having an effective length of 20 mm is prepared. This was attached to a stainless steel container to form a pencil module. A fixed amount of 1500 ppm of nitrogen gas is supplied to the outside of the hollow fiber of the pencil module, and water vapor is separated while flowing a fixed amount of carrier gas (Ar gas) to the permeate side. The amount was detected with a specular dew point meter. The water vapor transmission rate of the membrane was calculated from the measured amount of water vapor (water vapor partial pressure), the amount of supplied gas, and the effective membrane area. These measurements were made at 50 ° C.
（中空糸膜の窒素ガス透過性能の測定方法）約１５本の中空糸膜と、ステンレスパイプと、エポキシ樹脂系接着剤とを使用して有効長が１０ｃｍの透過性能評価用のエレメントを作成し、これをステンレス容器に装着してペンシルモジュールとした。それに一定圧力の窒素純ガスを供給して透過流量を測定した。測定した透過窒素ガス量と供給圧力及び有効膜面積から窒素ガスの透過速度を算出した。尚、これらの測定は５０℃でおこなった。 (Method for measuring nitrogen gas permeation performance of hollow fiber membrane) Using about 15 hollow fiber membranes, a stainless steel pipe, and an epoxy resin adhesive, an element for evaluating permeation performance having an effective length of 10 cm was prepared. This was attached to a stainless steel container to form a pencil module. A permeate flow rate was measured by supplying nitrogen pure gas at a constant pressure. The permeation rate of nitrogen gas was calculated from the measured amount of permeated nitrogen gas, supply pressure, and effective membrane area. These measurements were made at 50 ° C.
（中空糸膜の多孔質層のヘリウムガス透過性能の測定方法）プラズマ処理装置に多数本の中空糸膜を均一にひろげて設置し、印加電圧２０Ｖで酸素プラズマ処理をおこなった。酸素プラズマ処理を５分間おこなう毎に中空糸の一部（数本）を取り出して、プラスマ処理時間の異なった中空糸膜を得た。これらの中空糸膜を用いて前記と同様の方法でガス透過測定用ペンシルモジュール（有効長１０ｍｍ）を作成し、これに窒素純ガスあるいはヘリウム純ガスを一定量圧力で供給してそれぞれの透過流量を測定し、測定した透過流量と供給圧力及び有効膜面積から窒素あるいはヘリウムの透過速度を算出した。２０分間以上プラズマ処理した中空糸膜のこれらの値の比即ちＰ’He／Ｐ’N2は１．２以下になったので、２０分間処理した中空糸膜のヘリウムの透過速度（Ｐ’He）を、本発明で用いる膜の多孔質層のヘリウムの透過速度とした。尚、これらの測定は５０℃でおこなった。 (Measuring method of helium gas permeation performance of porous layer of hollow fiber membrane) A large number of hollow fiber membranes were uniformly spread in a plasma processing apparatus, and oxygen plasma treatment was performed at an applied voltage of 20V. Every time oxygen plasma treatment was performed for 5 minutes, some (several) hollow fibers were taken out to obtain hollow fiber membranes with different plasma treatment times. Using these hollow fiber membranes, a gas permeation measuring pencil module (effective length 10 mm) is prepared by the same method as described above, and nitrogen permeation gas or helium pure gas is supplied at a constant pressure to each permeate flow rate. The permeation rate of nitrogen or helium was calculated from the measured permeation flow rate, supply pressure, and effective membrane area. Since the ratio of these values of the hollow fiber membrane treated with plasma for 20 minutes or more, that is, P ′ He / P ′ N2, was 1.2 or less, the permeation rate of helium (P ′ He ) through the hollow fiber membrane treated for 20 minutes. Was the helium permeation rate of the porous layer of the membrane used in the present invention. These measurements were made at 50 ° C.
（中空糸膜の引張強度と破断伸度の測定）引張試験機を用いて有効長２０ｍｍ、引張速度１０ｍｍ／分で測定した。破断面積は破断面を光学顕微鏡を用いて寸法を測定して算出した。 (Measurement of tensile strength and breaking elongation of hollow fiber membrane) Using a tensile tester, the tensile strength was 20 mm and the tensile speed was 10 mm / min. The fracture area was calculated by measuring the dimensions of the fractured surface using an optical microscope.
〔実施例１〕
前記ポリマー濃度１２．０重量％のポリイミドＡ溶液の５８３．３ｇと、前記ポリマー濃度１３．０重量％のポリイミド溶液Ｂの２５０ｇとを、セパラブルフラスコにて１３０℃で３時間攪拌してポリイミド混合物溶液を調製した。この混合物溶液のポリマー濃度は１２．３重量％であり、回転粘度は１５００ポイズであった。このポリイミド混合物溶液を用いて、前記の非対称中空糸膜の製造方法に基づいて、中空糸膜を製造した。この中空糸膜のガス透過性能と機械的特性を前記の方法によって測定した。結果は表−１のとおりであった。
[Example 1]
A polyimide mixture obtained by stirring 583.3 g of the polyimide A solution having a polymer concentration of 12.0 wt% and 250 g of the polyimide solution B having a polymer concentration of 13.0 wt% in a separable flask at 130 ° C. for 3 hours. A solution was prepared. The polymer concentration of this mixture solution was 12.3% by weight, and the rotational viscosity was 1500 poise. Using this polyimide mixture solution, a hollow fiber membrane was produced based on the method for producing an asymmetric hollow fiber membrane. The gas permeation performance and mechanical properties of this hollow fiber membrane were measured by the above methods. The results are shown in Table 1.
〔実施例２〕
前記ポリマー濃度１２．０重量％のポリイミドＣ溶液３５０ｇと前記のポリマー濃度１３．０重量％のポリイミドＢ溶液１５０ｇとを実施例１と同様の混合方法に従って混合し、混合物溶液を調整した。この混合物溶液のポリマー濃度は１２．３重量％であった。このポリイミド混合物溶液を用いて、前記の非対称中空糸膜の製造方法に基づいて、中空糸膜を製造した。この中空糸膜のガス透過性能と機械的特性を前記の方法によって測定した。結果は表−１のとおりであった。
[Example 2]
350 g of the polyimide C solution having a polymer concentration of 12.0 wt% and 150 g of the polyimide B solution having a polymer concentration of 13.0 wt% were mixed according to the same mixing method as in Example 1 to prepare a mixture solution. The polymer concentration of this mixture solution was 12.3% by weight. Using this polyimide mixture solution, a hollow fiber membrane was produced based on the method for producing an asymmetric hollow fiber membrane. The gas permeation performance and mechanical properties of this hollow fiber membrane were measured by the above methods. The results are shown in Table 1.
〔実施例３〕
前記ポリマー濃度１２．０重量％のポリイミドＡ溶液４００ｇと前記のポリマー濃度１３．０重量％のポリイミドＢ溶液４００ｇとを実施例１と同様の混合方法に従って混合し、混合溶液を調整した。この混合物溶液のポリマー濃度は１２．５重量％であった。このポリイミド混合物溶液を用いて、前記の非対称中空糸膜の製造方法に基づいて、中空糸膜を製造した。この中空糸膜のガス透過性能と機械的特性を前記の方法によって測定した。結果は表−１のとおりであった。
Example 3
400 g of the polyimide A solution having a polymer concentration of 12.0 wt% and 400 g of the polyimide B solution having a polymer concentration of 13.0 wt% were mixed according to the same mixing method as in Example 1 to prepare a mixed solution. The polymer concentration of this mixture solution was 12.5% by weight. Using this polyimide mixture solution, a hollow fiber membrane was produced based on the method for producing an asymmetric hollow fiber membrane. The gas permeation performance and mechanical properties of this hollow fiber membrane were measured by the above methods. The results are shown in Table 1.
〔比較例１〕
前記ポリイミドＡ溶液を用いて、前記の非対称中空糸膜の製造方法に基づいて、中空糸膜を製造した。この中空糸膜のガス透過性能と機械的特性を前記の方法によって測定した。結果は表−１のとおりであった。
[Comparative Example 1]
Using the polyimide A solution, a hollow fiber membrane was produced based on the method for producing an asymmetric hollow fiber membrane. The gas permeation performance and mechanical properties of this hollow fiber membrane were measured by the above methods. The results are shown in Table 1.
〔比較例２〕
前記ポリマー濃度１３．０重量％のポリイミドＢ溶液を用いて、前記の非対称中空糸膜の製造方法に基づいて、中空糸膜を製造した。この中空糸膜のガス透過性能と機械的特性を前記の方法によって測定した。結果は表−１のとおりであった。
[Comparative Example 2]
A hollow fiber membrane was produced using the polyimide B solution having a polymer concentration of 13.0% by weight based on the method for producing an asymmetric hollow fiber membrane. The gas permeation performance and mechanical properties of this hollow fiber membrane were measured by the above methods. The results are shown in Table 1.
〔比較例３〕
前記ポリマー濃度１０．０重量％のポリイミドＢ溶液を用いて、前記の非対称中空糸膜の製造方法に基づいて、中空糸膜を製造した。この中空糸膜のガス透過性能と機械的特性を前記の方法によって測定した。結果は表−１のとおりであった。
[Comparative Example 3]
A hollow fiber membrane was produced using the polyimide B solution having a polymer concentration of 10.0% by weight based on the method for producing an asymmetric hollow fiber membrane. The gas permeation performance and mechanical properties of this hollow fiber membrane were measured by the above methods. The results are shown in Table 1.
〔比較例４〕
前記のポリマー濃度１２．３重量％のポリイミドＤ溶液を用いて、前記の非対称中空糸膜の製造方法に基づいて、中空糸膜を製造した。この中空糸膜のガス透過性能と機械的特性を前記の方法によって測定した。結果は表−１のとおりであった。
[Comparative Example 4]
Using the polyimide D solution having the polymer concentration of 12.3% by weight, a hollow fiber membrane was produced based on the asymmetric hollow fiber membrane production method. The gas permeation performance and mechanical properties of this hollow fiber membrane were measured by the above methods. The results are shown in Table 1.
実施例と比較例に示した中空糸膜の、水蒸気透過速度、水蒸気と窒素の透過速度比、中空糸膜の機械的強度、多孔質層のヘリウム透過速度の測定結果は表−１に示すとおりであった。実施例１〜３の膜は、水蒸気透過速度（Ｐ’H2O）が２．５×１０-3ｃｍ3（ＳＴＰ）／ｃｍ2・ｓｅｃ・ｃｍＨｇ以上であり、水蒸気と窒素の透過速度比（Ｐ’H2O／Ｐ’He）が５０以上であり、多孔質層のヘリウム透過速度（Ｐ’He）が３．０×１０-3ｃｍ3（ＳＴＰ）／ｃｍ2・ｓｅｃ・ｃｍＨｇ以上であり、中空糸膜での引張強度が２．５Ｋｇｆ／ｍｍ2以上であり、破断伸度が１０％以上である。これらの分離膜は、改良された優れた水蒸気透過速度を持ち、かつ、実用レベルの機械的強度を持つので分離膜モジュールへの加工が容易におこなうことが出来る高性能中空糸ガス分離膜である。しかしながら、比較例１の膜は多孔質層のヘリウム透過速度や膜の水蒸気透過速度は優れているが中空糸膜の引張強度が２．５Ｋｇｆ／ｍｍ2以下で破断伸度が１０％以下であり、実用レベルの機械的強度がなく分離膜モジュールへの加工が工業的に困難なものである。また、比較例２、３は、中空糸膜としての機械的強度は実用レベル以上であるが、多孔質層のヘリウム透過速度や膜の水蒸気透過速度が低いものである。更に、比較例４は、ポリイミドＡとポリイミドＢを等量混合した混合物のモノマーの成分組成とほぼ同一のモノマー成分組成を共重合した１種類のポリイミドＤからなる中空糸膜であるが、得られた中空糸膜の破断伸度は１０％以下であり実用レベルの機械的強度がなく分離膜モジュールへの加工が工業的には困難なものである。また、比較例４の中空糸膜はポリイミドＡとポリイミドＢの混合物で形成した中空糸膜（実施例３）に比べると水蒸気透過速度が低いものである。 Table 1 shows the measurement results of the water vapor transmission rate, the water vapor and nitrogen transmission rate ratio, the mechanical strength of the hollow fiber membrane, and the helium transmission rate of the porous layer of the hollow fiber membranes shown in Examples and Comparative Examples. Met. The membranes of Examples 1 to 3 have a water vapor transmission rate (P ′ H2O ) of 2.5 × 10 −3 cm 3 (STP) / cm 2 · sec · cm Hg or more, and a water vapor / nitrogen transmission rate ratio (P ' H 2 O / P' He ) is 50 or more, the helium permeation rate (P ' He ) of the porous layer is 3.0 × 10 -3 cm 3 (STP) / cm 2 · sec · cm Hg or more, and hollow The tensile strength at the yarn film is 2.5 kgf / mm 2 or more, and the elongation at break is 10% or more. These separation membranes are high-performance hollow fiber gas separation membranes that have improved and excellent water vapor transmission rate and mechanical strength at a practical level, so that they can be easily processed into separation membrane modules. . However, the membrane of Comparative Example 1 is excellent in the helium permeation rate of the porous layer and the water vapor permeation rate of the membrane, but the tensile strength of the hollow fiber membrane is 2.5 kgf / mm 2 or less and the elongation at break is 10% or less. However, there is no mechanical strength at a practical level and it is industrially difficult to process the separation membrane module. In Comparative Examples 2 and 3, the mechanical strength of the hollow fiber membrane is not less than a practical level, but the helium permeation rate of the porous layer and the water vapor permeation rate of the membrane are low. Further, Comparative Example 4 is a hollow fiber membrane composed of one type of polyimide D copolymerized with the same monomer component composition as the monomer component composition of a mixture of polyimide A and polyimide B in equal amounts. Further, the elongation at break of the hollow fiber membrane is 10% or less, and there is no mechanical strength at a practical level, and it is industrially difficult to process the separation membrane module. Further, the hollow fiber membrane of Comparative Example 4 has a lower water vapor transmission rate than the hollow fiber membrane (Example 3) formed from a mixture of polyimide A and polyimide B.
本発明のガス分離膜は、ガス透過速度をより向上させた非対称膜であり、しかも、実用レベルの機械的強度を有する。このため、本発明のガス分離膜を用いれば、ガス分離速度が向上したより高効率でよりコンパクトな高性能中空糸ガス分離膜モジュールを提供でき、高効率のガス分離を実現できる。また、本発明のガス分離膜は、少なくとも１種類のポリイミドを含む２種類以上のポリマーの混合物で非対称構造を有する膜を形成することで得ることが出来る。 The gas separation membrane of the present invention is an asymmetric membrane with a further improved gas permeation rate, and has a mechanical strength at a practical level. For this reason, if the gas separation membrane of the present invention is used, a more efficient and more compact high-performance hollow fiber gas separation membrane module with improved gas separation speed can be provided, and highly efficient gas separation can be realized. In addition, the gas separation membrane of the present invention can be obtained by forming a membrane having an asymmetric structure with a mixture of two or more types of polymers including at least one type of polyimide.
特に、水蒸気を含む混合ガスから水蒸気を除去する（除湿する）場合には、極めて高効率に、除湿を実施することが可能になる。 In particular, when water vapor is removed (dehumidified) from a mixed gas containing water vapor, dehumidification can be performed with extremely high efficiency.
Claims (4)
なお、ポリイミドＡはｓ−ＢＰＤＡ、６ＦＤＡ、ＴＳＮからなるポリイミドであり、ポリイミドＢはｓ−ＢＰＤＡ、ＴＳＮ、ＤＡＤＥからなるポリイミドであり、ポリイミドＣはｓ−ＢＰＤＡ、６ＦＤＡ、ＴＳＮ、ＴＣＢからなるポリイミドであり、
ｓ−ＢＰＤＡは３，３'，４，４'−ビフェニルテトラカルボン酸二無水物を表し、６ＦＤＡは２，２'−ビス（３，４−ジカルボキシルフェニル）ヘキサフルオロプロパン二無水物を表し、ＴＳＮはジメチル−３，７−ジアミノ−ジベンゾチオフェン−５，５−ジオキシドを表し、ＤＡＤＥは４，４'−ジアミノジフェニルエーテルを表し、ＴＣＢは２，２'，５，５'−テトラクロロ−４，４'−ジアミノビフェニルを表す。 A skin layer (separation layer) and a porous layer formed of a mixture of two types of polymers composed of polyimide A and polyimide B, or a mixture of two types of polymers composed of polyimide B and polyimide C A gas separation membrane having an asymmetric structure composed of a layer (support layer).
Polyimide A is a polyimide made of s-BPDA, 6FDA, TSN, polyimide B is a polyimide made of s-BPDA, TSN, DADE , and polyimide C is a polyimide made of s-BPDA, 6FDA, TSN, TCB. Yes,
s-BPDA represents 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 6FDA represents 2,2′-bis (3,4-dicarboxylphenyl) hexafluoropropane dianhydride, TSN represents dimethyl-3,7-diamino-dibenzothiophene-5,5-dioxide, DADE represents 4,4′-diaminodiphenyl ether, TCB represents 2,2 ′, 5,5′-tetrachloro-4, 4'-diaminobiphenyl is represented.
前記ポリマー混合物溶液をノズルから押し出して目的形状物とし空気又は窒素浴空間を通過させた後で凝固浴に浸漬する工程、
からなることを特徴とするスキン層（分離層）と多孔質層（支持層）とから構成される非対称構造を有するガス分離膜の製造方法。
なお、ポリイミドＡはｓ−ＢＰＤＡ、６ＦＤＡ、ＴＳＮからなるポリイミドであり、ポリイミドＢはｓ−ＢＰＤＡ、ＴＳＮ、ＤＡＤＥからなるポリイミドであり、ポリイミドＣはｓ−ＢＰＤＡ、６ＦＤＡ、ＴＳＮ、ＴＣＢからなるポリイミドであり、
ｓ−ＢＰＤＡは３，３'，４，４'−ビフェニルテトラカルボン酸二無水物を表し、６ＦＤＡは２，２'−ビス（３，４−ジカルボキシルフェニル）ヘキサフルオロプロパン二無水物を表し、ＴＳＮはジメチル−３，７−ジアミノ−ジベンゾチオフェン−５，５−ジオキシドを表し、ＤＡＤＥは４，４'−ジアミノジフェニルエーテルを表し、ＴＣＢは２，２'，５，５'−テトラクロロ−４，４'−ジアミノビフェニルを表す。 A step of preparing a polymer mixture solution in which a mixture of two types of polymers composed of polyimide A and polyimide B or a mixture of two types of polymers composed of polyimide B and polyimide C is uniformly dissolved in a solvent;
A step of extruding the polymer mixture solution from a nozzle to form a target shape, passing through an air or nitrogen bath space and then immersing in a coagulation bath;
A method for producing a gas separation membrane having an asymmetric structure composed of a skin layer (separation layer) and a porous layer (support layer).
Polyimide A is a polyimide made of s-BPDA, 6FDA, TSN, polyimide B is a polyimide made of s-BPDA, TSN, DADE , and polyimide C is a polyimide made of s-BPDA, 6FDA, TSN, TCB. Yes,
s-BPDA represents 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 6FDA represents 2,2′-bis (3,4-dicarboxylphenyl) hexafluoropropane dianhydride, TSN represents dimethyl-3,7-diamino-dibenzothiophene-5,5-dioxide, DADE represents 4,4′-diaminodiphenyl ether, TCB represents 2,2 ′, 5,5′-tetrachloro-4, 4'-diaminobiphenyl is represented.
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| JPH05508103A (en) * | 1990-04-03 | 1993-11-18 | ヘキスト・セラニーズ・コーポレーション | Gas separation membranes containing miscible blends of polyimide polymers |
| JPH08501977A (en) * | 1992-09-02 | 1996-03-05 | イー・アイ・デユポン・ドウ・ヌムール・アンド・カンパニー | Gas separation membranes made from aromatic polyimide, polyamide or blends of polyamide-imide polymers |
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| US4717394A (en) * | 1986-10-27 | 1988-01-05 | E. I. Du Pont De Nemours And Company | Polyimide gas separation membranes |
| US4717393A (en) * | 1986-10-27 | 1988-01-05 | E. I. Du Pont De Nemours And Company | Polyimide gas separation membranes |
| JPH0693987B2 (en) * | 1989-02-23 | 1994-11-24 | 宇部興産株式会社 | Gas separation membrane and gas separation method |
| US5074891A (en) * | 1989-07-27 | 1991-12-24 | Hoechst Celanese Corp. | Method of gas separation and membranes therefor |
| US4954144A (en) * | 1989-09-12 | 1990-09-04 | Air Products And Chemicals, Inc. | Polyimide membranes and their use for gas separation |
| JP2544229B2 (en) * | 1990-03-31 | 1996-10-16 | 宇部興産株式会社 | Pervaporation separation method of organic compound mixture |
| JP2631253B2 (en) * | 1991-08-23 | 1997-07-16 | 宇部興産株式会社 | Highly selective gas separation membrane and its production method |
| EP0648812B1 (en) * | 1993-10-19 | 2003-09-10 | L'air Liquide, S.A. à Directoire et Conseil de Surveillance pour l'Etude et l'Exploitation des Procédés Georges Claude | Blends of polyethersulfones with aromatic polyimides, polyamides or polyamide-imides and gas separation membranes made therefrom |
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| JPH08501977A (en) * | 1992-09-02 | 1996-03-05 | イー・アイ・デユポン・ドウ・ヌムール・アンド・カンパニー | Gas separation membranes made from aromatic polyimide, polyamide or blends of polyamide-imide polymers |
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