JP2013184139A - Steam separation membrane and method for manufacturing same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly durable steam separation membrane and a method for manufacturing the same.SOLUTION: A steam separation membrane includes a porous support membrane and a steam separative resin layer laminated on the porous support membrane. The porous support membrane contains an organic polymer resin and inorganic particles. Openings are formed in a face of the porous support membrane, the steam separative resin layer being laminated on the face. The inorganic particles exist at least in the openings. A ratio of an aperture ratio occupied by the inorganic particles on a face of the steam separative resin side to an opening ratio on a face of the porous support membrane, the steam separative resin layer being laminated on the face, is 0.2-4, a permeation coefficient of nitrogen of the steam separative resin is 1-900 barrer, and a separation factor of hydrogen to nitrogen is 2-15.

Description

  The present invention relates to a water vapor separation membrane and a method for producing the same.

  A process for removing water from a mixed solution of water and organic matter (hereinafter, dehydration process) has been widely used in various chemical processes.

  Conventionally, a dehydration method by distillation has been used as the dehydration process. However, when water is separated from a mixture of water and an organic compound such as ethanol or isopropanol by distillation, if the concentration of the organic compound exceeds a certain level, it becomes an azeotropic state. There is a problem that it is not enough. In addition, in the case of azeotropic state, it is necessary to use an azeotropic distillation method using an entrainer such as benzene, but the azeotropic distillation method requires an energy cost in addition to the need for a third component. Tend to be higher.

  Therefore, as a separation method that replaces the distillation method, a pervaporation (hereinafter referred to as PV method) method or a vapor permeation (hereinafter referred to as VP method) method, which is a separation method using a water vapor separation membrane, is a new separation method. Attention has been paid.

  In the PV method, separation is performed by supplying a mixture of liquids to be separated to the primary side (stock solution side) of the membrane and reducing the pressure on the secondary side (permeation side) of the membrane or ventilating the carrier gas. This is a separation method in which a substance to be permeated is passed through a membrane in a gaseous state.

  On the other hand, the VP method is a method in which the liquid mixture in the pervaporation method is heated to the boiling point of the liquid mixture or higher and supplied to the primary side of the membrane as a mixed vapor. The gas or vapor that has passed through the membrane is separated and recovered as a liquid by cooling and condensing on the secondary side.

  Both the PV method and the VP method are separation methods using a water vapor separation membrane, and are separation methods that utilize the fact that there is a difference in the permeation rate of the membrane in a gas state depending on the separation object. Various materials have been proposed as a water vapor separation membrane suitable for the PV method and the VP method.

  Non-Patent Document 1 proposes a polymer membrane as a water vapor separation membrane for the PV method. Further, a water vapor separation membrane made of an inorganic material such as a zeolite membrane has attracted attention (see Patent Document 1, Non-Patent Document 2, etc.).

JP-A-7-185275

Peter D. Chapman et al., “Membranes for dehydration of solvent by pervaporation”, Journal of Membrane Science, 318, (2008), 5-37. Shiguang Li et al., “Pervaporation of Water / THF Mixtures Using Zeolite Memranes”, Ind. Eng. Chem. Res. , 2001, 40, 457

  However, the water vapor separation membrane is required to maintain separation performance even after repeated use. Furthermore, a water vapor separation membrane having high separation performance and sufficient permeation flow rate is required.

  Therefore, an object of the present invention is to provide a water vapor separation membrane having excellent durability, high separation performance, and sufficient permeation flow rate, and a method for producing the same.

  As a result of intensive studies to solve the above problems, the inventors of the present invention are water vapor separation membranes in which a water vapor separation resin layer is laminated on a porous support membrane, and the porous support membrane includes an organic polymer resin and an inorganic substance. By forming a water vapor separation membrane comprising particles, wherein pores are formed on the surface of the porous support membrane on which the water vapor separation resin layer is laminated, and inorganic particles are present at least in the pores, It has been found that the water vapor separating resin is thin and uniform, and has high durability, and the present invention has been achieved. That is, the present invention is as follows.

[1] A water vapor separation membrane comprising a porous support membrane and a water vapor separation resin layer laminated on the porous support membrane, the porous support membrane comprising an organic polymer resin and inorganic particles, and porous An opening is formed on the surface of the porous support membrane on which the water vapor separating resin layer is laminated, and at least a part of the inorganic particles are present in the opening, and the water vapor separating resin layer of the porous support membrane is laminated. The ratio (B / A) of the area ratio (B) that the inorganic particles occupy on the surface on the water vapor-separating resin side with respect to the open area ratio (A) on the surface is 0.2 to 4, and the water-vapor separating resin layer is A water vapor separation membrane having a nitrogen permeability coefficient of 1 to 900 barrer and a hydrogen separation coefficient of 2 to 15 with respect to nitrogen.
[2] The water vapor separation membrane according to [1], wherein the porous support membrane has a communication hole therein, and a part of the communication hole forms an opening.
[3] The water vapor separation membrane according to [1] or [2], wherein the porous support membrane contains 25 to 85% by mass of inorganic particles.
[4] The water vapor separation membrane according to any one of [1] to [3], wherein the porous support membrane has a nitrogen permeation rate of 3500 GPU or more and a pressure by a bubble point method of 650 kPa or more.
[5] Any one of [1] to [4], wherein the inorganic particles have an average primary particle size of 0.005 to 0.5 μm and a specific surface area of 30 m ² / g to 500 m ² / g. The water vapor separation membrane described in 1.
[6] The water vapor separation membrane according to any one of [1] to [5], wherein the inorganic particles are silica.
[7] The water vapor separation membrane according to any one of [1] to [6], wherein the organic polymer resin is a thermoplastic resin.
[8] The water vapor separation membrane according to [7], wherein the thermoplastic resin contains at least one selected from the group consisting of polyolefin and halogenated polyolefin.
[9] The water vapor separation membrane according to any one of [1] to [8], wherein the water vapor separating resin contains a fluororesin.
[10] The fluororesin is a copolymer of perfluoro 2,2-dimethyl-1,3-dioxole and tetrafluoroethylene, polyperfluoromethyl vinyl ether, polyvinylidene fluoride, polyhexafluoropropylene, and poly The water vapor separation membrane according to [9], which is at least one selected from the group consisting of chlorotrifluoroethylene.
[11] The steam separation membrane according to any one of [1] to [10], wherein the shape of the steam separation membrane is hollow.
[12] The water vapor separation membrane according to any one of [1] to [11], wherein a separation factor of hydrogen with respect to nitrogen is 3 or more and less than 15.
[13] A water vapor permeable membrane for pervaporation using the water vapor separation membrane according to any one of [1] to [12].
[15] A method for producing a water vapor separation membrane according to any one of [1] to [13], comprising a step of melt-kneading a mixture containing an organic polymer resin, inorganic particles and a plasticizer, and melt-kneading Forming a molded product by obtaining a molded product, extracting a plasticizer from the molded product to obtain a porous support membrane, and laminating a water vapor separating resin layer on the surface of the porous support membrane; A method for producing a water vapor separation membrane.

  According to the present invention, it is possible to provide a water vapor separation membrane having excellent durability, high separation performance, and sufficient permeation flow rate, and a method for producing the same. Further, the water vapor separation membrane of the present invention can be suitably used as a water vapor separation membrane for PV method or VP method.

It is a conceptual sectional view of the water vapor separation membrane of this embodiment. It is a conceptual surface figure of the water vapor separation membrane of this embodiment. It is a conceptual diagram of the measuring apparatus used in the Example. It is a conceptual diagram of the measuring apparatus used in the Example. It is a SEM photograph of the porous support membrane obtained in the Example. It is a SEM photograph of the porous support membrane obtained in the Example. It is a SEM photograph of the porous support membrane obtained in the Example. It is a SEM photograph of the water vapor separation membrane obtained in the example.

  Hereinafter, modes for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail with reference to the drawings as necessary. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The accompanying drawings show an example of the embodiment, and the form is not construed as being limited thereto. The present invention can be implemented with appropriate modifications within the scope of the gist thereof. Note that the positional relationship such as up, down, left, and right in the drawing is based on the positional relationship shown in the drawing unless otherwise specified, and the dimensional ratio in the drawing is not limited to the illustrated ratio.

  The water vapor separation membrane of the present embodiment includes a porous support membrane and a water vapor separation resin layer laminated on the porous support membrane, and the porous support membrane includes an organic polymer resin and inorganic particles. The water vapor separation membrane is characterized in that an opening is formed on the surface of the porous support membrane on which the water vapor separating resin layer is laminated, and at least a part of the inorganic particles are present in the opening.

(Porous support membrane)
In the present embodiment, the porous support membrane includes an organic polymer resin and inorganic particles, and has a porous structure. Openings are formed on the surface of the porous support membrane, and a part of the inorganic particles are present in the openings.

[Organic polymer resin]
In the present embodiment, the organic polymer resin becomes a skeleton portion of the porous structure of the porous support membrane. In the present embodiment, it is preferable that a communication hole described later is formed between the skeletons containing the organic polymer resin.

  This porous structure can be formed by melting an organic polymer resin in a manufacturing method described later. The organic polymer resin is preferably a thermoplastic resin. Here, the thermoplastic resin is a resin that becomes soft when heated to the glass transition temperature or the melting point and can be molded into a desired shape.

  As the thermoplastic resin, at least one selected from the group consisting of polyolefin and halogenated polyolefin can be used.

Polyolefin is preferable as a base material for forming the structure of a porous support film because it is thermoplastic and has excellent handleability and is tough and therefore has excellent mechanical strength. Examples of the monomer olefin that is a raw material of polyolefin include ethylene, propylene, and butene. In this embodiment, the polyolefin may be a polymer of the above monomer alone or a copolymer containing two or more types.
The polyolefin may be a copolymer of the olefin monomer and another monomer. Examples of other monomers include vinyl alcohol, tetrafluoroethylene, hexane, vinylidene fluoride, ethylene tetrafluoride, propylene hexafluoride, and ethylene trifluoride chloride.

  As the polyolefin, polyethylene, polypropylene or a mixture thereof is preferable. Since these polyolefins have high crystallinity, they have high water resistance (mechanical strength when wet) and high hydrophobicity, mechanical strength, and chemical stability (chemical resistance, etc.). In addition, the moldability is also good and the manufacture becomes easy. In particular, polyethylene, polypropylene, and a mixture of both are particularly preferable because they have better moldability and are easy to dispose of because they do not contain halogen.

  The halogenated polyolefin is a polymer in which some or all of the hydrogen atoms of the polyolefin are substituted with halogen atoms. The halogen atom is preferably a fluorine atom, and specific examples of the fluorinated polyolefin include polyvinylidene fluoride and a vinylidene fluoride copolymer.

  In the present embodiment, the weight average molecular weight (Mw) of the organic polymer resin is preferably 10,000 or more and less than 1,000,000. When the Mw of the organic polymer resin is 10,000 or more, the resulting porous support membrane has a high elongation and a high mechanical strength. If Mw is less than 1,000,000, the fluidity at the time of melting tends to be high and the moldability tends to be high.

  Moreover, when using polyolefin as organic polymer resin, it is more preferable that the number average molecular weight (Mn) of this polyolefin is 15000 or more, and Mw is 600000 or less.

  Moreover, when using halogenated polyolefin as organic polymer resin, it is especially preferable that Mw is 100000 or more and less than 1 million. In particular, when the halogenated polyolefin contains a polyvinylidene fluoride resin or a vinylidene fluoride copolymer, it is particularly preferable that Mw is 100,000 or more and less than 1,000,000.

[Inorganic particles]
The inorganic particles of the present embodiment may be particles made of any inorganic compound. For example, metal oxide, metal composite oxide, metal, carbon, metal carbide, and the like. The metal according to the present embodiment includes silicon and germanium. Specific examples of metal oxides include silicon oxide (silica), aluminum oxide (alumina), ferrous oxide, cesium oxide, titanium oxide, yttrium oxide, zirconium oxide, magnesium oxide, manganese oxide, zinc phosphate, and oxidation. Examples include holmium. Specific examples of the metal complex oxide include zeolite and talc. Among these, silica, talc, alumina, and mica are preferable. These inorganic compound particles may be used alone or in combination of two or more. Any inorganic particles may be used as long as they are obtained by a conventionally known production method. For example, inorganic particles may be obtained by pulverizing an inorganic compound obtained by a gas phase method, a liquid phase method, and / or these methods. Of course, other methods may be used.

  A specific example of silica, which is one of the preferred inorganic particles, will be described in more detail.

  In general, silica is classified into natural silica and synthetic silica.

  Synthetic silica production methods can be broadly classified into two types, that is, a wet method and a dry method. The wet method is a method of synthesizing by reaction of sodium silicate and mineral acid, for example, by hydrolysis of alkoxysilane. Examples of the dry method include a method of synthesis by high-temperature hydrolysis of silicon halide in an oxyhydrogen flame. The synthetic silica is preferably amorphous.

  The amorphous silica is preferably produced by adding an acid at 60 to 90 ° C. to a mixture of water and alkali metal silicate. Water and / or alkali metal silicate may be heated separately or mixed and heated at the same time. The alkali metal silicate is a meta or disilicate alkali metal or alkaline earth metal salt, and is not particularly limited. It is preferable to use an electrolyte such as sodium sulfate as the reaction medium.

  In the present embodiment, fumed silica is given as another specific example of preferable synthetic silica. Such fumed silica can be produced by a dry method of hydrolyzing at high temperature using silicon tetrachloride, hydrogen, oxygen, and water, as described in JP-A-2000-86227. Specifically, it is obtained by using a volatile silicon compound as a raw material and thermally decomposing it at a high temperature of 1000 to 2100 ° C. in a flame burned by supplying it to a burner together with a mixed gas containing a combustible gas and oxygen. .

As a volatile silicon compound used as a raw material, for example, a volatile silicon halide compound is preferable. SiH ₄ , SiCl ₄ , CH ₃ SiCl ₃ , CH ₃ SiHCl ₂ , HSiCl ₃ , (CH ₃ ) ₂ SiCl ₂ , (CH ₃ ) ₃ SiCl, (CH ₃ ) ₂ SiH ₂ , (CH ₃ ) ₃ SiH, alkoxysilane and the like. The mixed gas containing combustible gas and oxygen is preferably one that generates water, and hydrogen, methane, butane, etc. are suitable, and oxygen, air, etc. are used as the oxygen-containing gas.

  The amount ratio of the volatile silicon compound and the mixed gas is such that the molar equivalent of the volatile silicon compound is 1 molar equivalent, and the molar equivalent of oxygen in the mixed gas containing hydrogen which is oxygen and the combustible gas is 2.5 to 3.5. And the molar equivalent of hydrogen is adjusted to the range of 1.5 to 3.5. Here, the molar equivalent for oxygen and hydrogen refers to the stoichiometric equivalent that reacts with the volatile silicon compound that is the raw material compound. Moreover, when using hydrocarbon fuels, such as methane, the molar equivalent of hydrogen conversion is pointed out.

  Of the fumed silica, hydrophobic fumed silica is more preferable. In the present embodiment, the hydrophobic fumed silica means that the volume% (MW value) of methanol completely wetted in a powder state is 30% or more. The “volume% (MW value) of methanol completely wetted in a powder state” as defined herein is a value measured by a methanol wettability method.

  By using hydrophobic fumed silica, silica is not aggregated, so that it can be uniformly present in the porous support membrane. Compared with the case of using hydrophilic silica, the affinity with hydrophobic organic polymer resin and plasticizer used in the production is increased, so that inorganic particles are uniformly dispersed microscopically. . As a result, a finer and more uniform porous structure is formed in three dimensions. The fine and uniform porous structure does not include, for example, a structure in which there are large pores called macrovoids or a structure in which cracked grooves called die lines exist.

  In this embodiment, synthetic silica manufactured by US Nanophase Technology, Inc., and Polyolefin Oligomeric Silsesquioxane (POSS) manufactured by Hybrid Plastics, US by the organic-inorganic hybrid method are also specific examples of preferable synthetic silica.

  In the present embodiment, it is also preferable that the inorganic particles are surface-coated with a silicon-containing compound. The method of covering the inorganic particles with the silicon-containing compound may be any method as long as it is a conventionally known method.

  A silane coupling agent etc. are mentioned as a specific example of the surface coating agent of a silicon-containing compound. Specific examples of the silane coupling agent include dimethyldichlorosilane treatment, hexamethyldisilazane treatment, octylsilane treatment, methacryloxysilane treatment, aminosilane treatment, hexamethyldisilazane treatment, dimethylsilicone oil treatment, diphenyldichlorosilane treatment, hexa Examples thereof include phenyldisilazane treatment, phenylalkylsilane treatment, phenylmethacryloxysilane treatment, phenylaminosilane treatment, and phenyl group-containing silicone oil treatment. Of course, any other silicon-containing compound that covers the surface of the inorganic compound may be used.

  The POSS of Hybrid Plastics, USA includes synthetic silica surface-coated with a low molecular compound or polymer, such as alcohol, phenol, amine, chlorosilane, epoxy, ester, fluoroalkyl, halide, isocyanate, methacrylate, Those having a surface coating with various low molecular compounds such as acrylate, silicone, nitrile, norborenyl, olefin, phosphine, silane, thiol, polystyrene, and various polymers are also included.

In the present embodiment, the inorganic particles preferably have an average primary particle size of 0.005 to 0.5 μm and a specific surface area of 30 m ² / g or more and 500 m ² / g or less. Thereby, the nitrogen permeation rate of the porous support membrane is 3500 GPU or more, and the pressure by the bubble point method of the porous support membrane, that is, the bubble point (BP) becomes 650 kPa or more. That the pressure is less than 650 kPa means that the maximum pore size of the porous support membrane is 0.095 μm or more, and it becomes difficult to laminate the water vapor separating resin thinly and uniformly. If the nitrogen permeation rate of the porous support membrane is lower than 3500 GPU, the function as a porous support membrane is not achieved, and the gas permeation performance is remarkably lowered when the water vapor separating resin is laminated.

Here, the permeation rate is expressed by gas permeation amount in unit time, unit area, and unit partial pressure difference. As a unit, GPU (Gasperation unit) = 10 ⁻⁶ cm ³ (STP) / cm ² · sec · cmHg is widely used. ing.

[Porous support membrane structure]
In the present embodiment, the porous support membrane has a structure in which openings are formed on the surface on which the water vapor separating resin layer is laminated, and at least a part of the inorganic particles are present in the openings.

  In the present embodiment, the presence of the inorganic particles in the pores allows the water vapor separating resin to be applied uniformly and thinly on the surface of the porous support membrane. Thereby, durability as a water vapor separation membrane is improved, and further, separation performance and permeation performance are improved.

  Moreover, in the porous support membrane in this embodiment, it is preferable that a communicating hole is formed inside the porous supporting membrane, and a part of the communicating hole forms the above-mentioned opening. The communication hole is preferably formed between the skeletons forming the porous structure of the porous support membrane. The skeleton includes an organic polymer resin. With such a structure, the permeation performance of the water vapor separation membrane is further improved. In particular, it is more preferable that the communication holes are continuously connected from the inside to the outer surface of the porous support membrane.

  The structure of the porous support membrane in this embodiment will be described in detail with reference to FIG. FIG. 1 is a conceptual cross-sectional view schematically showing a part of the water vapor separation membrane of the present embodiment.

  The water vapor separation membrane 1 has a water vapor separation resin layer 2 laminated on a porous support membrane 3, and has an opening 4 on the surface of the porous support membrane 3 on which the water vapor separation resin layer 2 is laminated. And the inorganic particle 5 exists in the opening at least. Further, the communication hole 6 is formed inside the membrane, and the communication hole 6 extends to the surface of the porous support membrane 3 on which the water vapor separating resin layer 2 is laminated to form the opening 4. preferable.

  In this embodiment, the area ratio of the inorganic particles in the surface of the porous support membrane on the side of the water vapor separating resin layer to the porosity (A) on the surface of the porous support membrane on which the water vapor separating resin layer is laminated The ratio (B / A) of (B) is 0.2 to 4, more preferably 0.8 to 3.5, and still more preferably 1.2 to 3.3.

  Hereinafter, the hole area ratio (A) and the area ratio (B) will be described with reference to FIG.

  FIG. 2 is a conceptual diagram when the porous support membrane is viewed from above. Open holes 4 are formed on the surface of the porous support membrane 3, and inorganic particles 5 exist in the open holes 4. In the region α, the inorganic particles 5 are located in the openings 4. In the region β, the inorganic particles 5 are positioned so as to cross the apertures 4, and in the region γ, the inorganic particles 5 are positioned so as to cover the apertures 4.

  At this time, the porosity (A) is the ratio of the area occupied by the pores on the surface of the porous support membrane on which the water vapor separating resin layer is laminated. For example, in FIG. 2, in the region γ, the inorganic particles 5 cover the apertures, and the aperture ratio (A) is calculated including the area of the apertures in this portion. That is, the porosity (A) is a value obtained by dividing the area of the pores existing on the surface by the projected area of the porous support membrane when the inorganic particles are removed from the membrane surface. Therefore, in FIG. 2, the value obtained by dividing the area of all the apertures 4 by the projected area of the porous support membrane is the aperture ratio (A).

In this embodiment, the porosity (A) of the outer surface of the porous support membrane is determined by immersing the porous support membrane in a 20 wt% NaOH aqueous solution at 70 ° C. for 1 hour, After extracting and removing the inorganic particles present in the surface, washing with water and drying, the electron micrograph of the outer surface is subjected to black and white binarization processing on the hole portion and the non-hole portion existing on the outer surface, Can be sought.
Outer surface area ratio (A) [%] = 100 × (hole part area) / {(hole part area) + (non-hole part area)}

  The magnification of the electron micrograph used needs to be large enough to clearly recognize the shape of the pores present on the surface of the porous support membrane on which the water vapor separating resin layer is laminated. Since it is necessary to measure the aperture ratio averaged as much as possible by making it as large as possible, it is not suitable if it is too large. The standard of the photographing magnification is 1000 to 5000 times if the area main body (hole diameter corresponding to 50% of the accumulated area) is about 1 to 10 μm, and 5000 to 20000 if the area is about 0.1 to 1 μm. If it is about 0.03 to 0.1 μm, it is 10,000 to 50,000 times.

  When performing black-and-white binarization processing, an electron micrograph taken at these magnifications may be used after being enlarged using a copier or other means. If a commercially available image analysis system is used, it is possible to perform black-and-white binarization processing in the system equipment directly from an electron micrograph or a copy thereof. Errors in aperture ratio measurement due to misidentification at the stage of black-and-white binarization processing, such as when the image is white, or when contrast is applied during shooting, parts that are not inorganic particles may become black similar to inorganic particles Is likely to occur and is inappropriate. In addition, the direct black-and-white binarization in the system equipment from the electron micrograph or a copy thereof is not actually a surface part, but the structure of the film thickness part that can be seen from the opening of the surface This may be mistaken for the structure, and may cause an error in the measurement of the surface area ratio of the inorganic particles. Therefore, when measuring the surface area ratio of inorganic particles by performing black-and-white binarization, a transparent sheet is placed on the electron micrograph used or a copy thereof, and the pores existing on the surface are colorless. By painting (transferring) black on a transparent sheet with a black magic pen, etc., and copying the transfer sheet onto a white paper, the inorganic particle part is clearly divided into black, and the non-inorganic particle part is clearly divided into white. It is necessary to obtain the surface area ratio using a commercially available image analysis system or the like.

  Next, the area ratio (B) is the ratio of the area occupied by inorganic particles in the projected area of the porous support membrane. Therefore, in FIG. 2, the value obtained by dividing the area of all inorganic particles 5 by the projected area of the porous support membrane is (B).

Here, the area ratio (B) is the ratio between the inorganic particle portion and the non-inorganic particle portion existing on the scanning electron microscope reflected electron image of the surface on which the water vapor separating resin layer of the porous support film is laminated. Can be obtained from the following equation.
Area ratio (B) [%] = 100 × (inorganic particle partial area) / {(inorganic particle partial area) + (non-inorganic particle partial area)}

  The magnification of the electron microscope image to be used needs to be high enough to clearly recognize the shape of the inorganic particles present on the surface, while the area within one field of view is made as large as possible, and the inorganic particles averaged as much as possible are used. It is not appropriate to be too expensive because it needs to be measured. The standard of the photographing magnification is 1000 to 5000 times if the surface main body of the surface inorganic particles (inorganic particles corresponding to an area cumulative value of 50%) is about 1 to 10 μm, and 5000 to 20000 if the surface inorganic particles are about 0.1 to 1 μm. If it is about 0.03 to 0.1 μm, it is 10,000 to 50,000 times.

  When binarization processing is performed, an electron microscope image taken at these magnifications may be enlarged after being enlarged using a copying machine or other means. Note that points to note when using a commercially available image analysis system are the same as described above.

  In the present embodiment, for example, (B / A) can be adjusted within a range of 0.2 to 4 by increasing or decreasing the content of inorganic particles or by increasing or decreasing the temperature during plasticizer extraction. For example, when the weight ratio of the inorganic particles to the organic polymer resin is increased, the value of B / A is increased. Conversely, when the weight ratio of the inorganic particles to the organic polymer resin is decreased, the value of B / A is increased. Get smaller. In addition, although the change is not as great as when the content of inorganic particles is increased or decreased, it is possible to reduce the B / A value by raising the temperature at the time of plasticizer extraction. By lowering the temperature during agent extraction. It is possible to slightly increase the value of B / A. In addition, B / A being 1 means that the area of the opening and the area occupied by the inorganic particles are the same. When B / A exceeds 1, the area occupied by the inorganic particles is the opening. It means that it is larger than the area.

  As a hole diameter of an opening, 0.001-1 micrometer is preferable and 0.05-0.5 micrometer is more preferable. The pore size of the opening is the average pore size of the pores existing in the porous support membrane. The average pore diameter of the membrane can be determined according to the method described in ASTM: F316-86 (also known as the half dry method). Note that what is determined by this half dry method is the average pore size of the minimum pore size layer of the membrane, and strictly speaking, it is different from the average pore size of the apertures. However, since the porous support membrane of the present invention has a homogeneous structure, the average pore size of the openings is the average of the minimum pore size layer of the membrane.

In this embodiment, measurement of the average pore size by the half-dry method was performed using ethanol as the liquid used and measuring at 25 ° C. and a pressure increase rate of 0.001 MPa / second as standard measurement conditions. The average pore diameter [μm] is obtained from the following formula.
Average pore diameter [μm] = (2860 × surface tension [mN / m]) / half dry air pressure [Pa]

Since the surface tension of ethanol at 25 ° C. is 21.97 mN / m (The Chemical Society of Japan, Chemistry Handbook Basic Edition, Rev. 3, II-82, Maruzen Co., Ltd., 1984), the standard measurement conditions in the present invention In the case of,
Average pore diameter [μm] = 62834.2 / (half dry air pressure [Pa])
It can ask for.

The maximum pore size of the membrane can be determined from the pressure when bubbles first emerge from the membrane in the half dry method (bubble point method). In the case of the above half dry method standard measurement conditions, from the pressure when bubbles first emerge from the hollow fiber membrane,
Maximum pore diameter [μm] = 62834.2 / (bubble generating air pressure [Pa])
It can be obtained more.

  Moreover, in this embodiment, it is preferable that the inside of the communicating hole inside the porous support membrane is filled with inorganic particles. By filling the inorganic particles in the communication holes, a porous support membrane having excellent mechanical strength and heat resistance can be obtained.

  Preferably, the inorganic particles are filled at 25 to 85% by mass with respect to the entire porous support membrane. More preferably, it is 35-75 mass%, More preferably, it is 40-70 mass%.

In the present embodiment, the mass fraction (%) filled with the inorganic particles is defined by the following equation.
Mass fraction (%) = {(mass of all inorganic particles in porous support membrane) / (mass of porous support membrane)} × 100

(Water vapor separating resin layer)
The water vapor separating resin layer of the present embodiment is a layer formed from a water vapor separating resin. The water vapor separating resin is a resin having a function of separating a gas. As the water vapor separating resin, a fluororesin is preferable, and a resin that can be dissolved or dispersed in an organic solvent is preferable in consideration of processability.

  As the fluororesin used in the present embodiment, commercially available Teflon (registered trademark) AF series (manufactured by DuPont), full-on series (manufactured by Asahi Glass), hyflon series (manufactured by Solvay Solexis), Cytop (Asahi Glass) ), THV series (manufactured by Sumitomo 3M), Neofuron series (manufactured by Daikin), Kyner series (manufactured by Arkema), Tedlar series (manufactured by DuPont), Dinion series (manufactured by Dinion), etc. . These can be used individually by 1 type or in mixture of 2 or more types.

Examples of the organic solvent for dissolving or dispersing the water vapor separating resin include CF ₃ CH ₂ OH, F (CF ₂ ) ₂ CH ₂ OH, (CF ₃ ) ₂ CHOH, F (CF ₂ ) ₃ CH ₂ OH, and F (CF _{2) 4 C 2 H 5 OH} , H (CF 2) 2 CH 2 OH, H (CF 2) 3 CH 2 OH, H (CF 2) 4 fluorinated alcohol solvent of _CH 2 OH, and the like; perfluoro benzene, Fluorine-containing aromatic solvents such as meta-xylene hexafluoride; CF ₄ (HFC-14), CHClF ₂ (HCFC-22), CHF ₃ (HFC-23), CH ₂ CF ₂ (HFC-32), CF ₃ CF ₃ (PFC-116), CF ₂ ClCFCl ₂ (CFC-113), C ₃ HClF ₅ (HCFC-225), CH ₂ FCF ₃ (HFC-134a), CH ₃ CF ₃ (HFC-143a), CH ₃ CHF ₂ (HFC-152a), CH ₃ CCl ₂ F (HCFC-141b), CH ₃ CClF ₂ (HCFC-142b), C ₄ F ₈ (PFC-C318), etc. Fluorocarbon solvents, etc .; hydrocarbon solvents such as xylene, toluene, Solvesso 100, Solvesso 150, hexane, etc .; methyl acetate, ethyl acetate, butyl acetate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether , Ester solvents such as diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, ethylene glycol acetate, diethylene glycol acetate; Ether, diethyl ether, dibutyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether Ether solvents such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether and tetrahydrofuran; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and acetone; N, N-dimethylacetamide, N-methylacetamide, Amide solvents such as cetamide, N, N-dimethylformamide, N, N-diethylformamide, N-methylformamide; sulfonic acid ester solvents such as dimethyl sulfoxide; methanol, ethanol, isopropanol, butanol, ethylene glycol, diethylene glycol, polyethylene A glycol (degree of polymerization 3-100) etc. are illustrated. These solvent can be used individually by 1 type or in mixture of 2 or more types. Of these, from the viewpoints of solubility, coating film appearance and storage stability, the above-mentioned various fluorine-based solvents, ketone-based solvents and ester-based solvents are preferable, and in particular, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cellosolve acetate, butyl acetate, More preferred are ethyl acetate, perfluorobenzene, metaxylene hexafluoride, HCFC-225, CFC-113, HFC-134a, HFC-143a and HFC-142b.

  The thickness of the water vapor separating resin layer is preferably thinner from the viewpoint of maximizing the gas permeation rate, and is preferably 10 μm or less, and more preferably 1 μm or less.

As a function of the water vapor separating resin layer, the nitrogen permeability coefficient is 1 barr to 900 barrer. Here, the permeation coefficient is a gas permeation rate per unit time, unit area, unit thickness, unit pressure (differential pressure), and is a physical constant specific to the material. The unit of the transmission coefficient is barrer, and barrer = 10 ⁻¹⁰ cm ³ (STP) cm / cm ² · sec · cmHg.
When the nitrogen permeation coefficient is less than 1 barrer, a sufficient water permeation rate tends not to be obtained when used in the PV method. Further, the permeation flow rate tends to be extremely low.
When the permeability coefficient exceeds 900 barrer, for example, when IPA and water are separated, the separability tends to be lowered.

  Moreover, the separation factor of hydrogen with respect to nitrogen (hereinafter referred to as “hydrogen / nitrogen separation factor”), which is the ratio of the hydrogen permeation rate to the nitrogen permeation rate, is 2 to 15, preferably 2.5 to 7. 0. When the hydrogen / nitrogen separation factor exceeds 15, the water permeation rate by the PV method tends to decrease. When the hydrogen / nitrogen separation factor is less than 2, when used in the PV method, for example, when separating IPA and water, the separability tends to decrease. The water vapor separating resin layer of this embodiment needs to have a high permeation rate. Therefore, it is necessary that the nitrogen permeability coefficient is 1 barr to 900 barrer and the hydrogen / nitrogen separation factor is 2 to 15.

The permeation performance of the water vapor separating resin can be expressed by a nitrogen permeation coefficient and a hydrogen / nitrogen separation coefficient. The nitrogen permeation coefficient and the hydrogen / nitrogen separation coefficient of the water vapor separating resin are values inherent to the material itself, regardless of the thickness of the layer when the water vapor separating resin is layered. Therefore, in order to measure the nitrogen permeability coefficient and the hydrogen / nitrogen separation coefficient of the water vapor separating resin, it is necessary to use a membrane having a known thickness and having no defects. Therefore, first, a water vapor-separating resin is cast so as to have a thickness of about 20 μm to 100 μm, and a self-supporting membrane made of only the material itself and containing no bubbles is produced. By measuring the obtained membrane based on JIS Z-1707, the nitrogen permeation coefficient and the hydrogen / nitrogen separation coefficient can be determined. In general, if the hydrogen / nitrogen separation coefficient of the gas separation membrane is α ′,
α ′ = fH ₂ [GPU] / fN ₂ [GPU]
It is written with. Here, fH ₂ is the hydrogen permeation rate of the gas separation membrane itself, and fN ₂ is the nitrogen permeation rate of the gas separation membrane itself. The gas permeation speeds of these gas separation membranes include both flux due to dissolution and diffusion of gas and Knudsen flow due to pinholes. In actual gas separation module design, these gas separation membranes themselves The gas permeation rate of In this case, the separation coefficient α ′ is a value specific to the material (not a physical constant but an apparent value determined for the gas separation membrane itself. If there is no Knudsen flow, α ′ is equal to the ideal separation coefficient α.

  Since the nitrogen permeability coefficient and hydrogen / nitrogen separation coefficient of the water vapor separation resin layer are physical constants specific to the material, the material should be selected appropriately so that the nitrogen permeability coefficient and the hydrogen / nitrogen separation coefficient are within the specified ranges. To do.

[Water vapor separation membrane]
The gas permeation performance of a water vapor separation membrane as a composite material composed of a water vapor separation resin layer and a porous support is expressed by a nitrogen permeation rate and a hydrogen / nitrogen separation coefficient. The water vapor separation membrane of this embodiment preferably has a nitrogen permeation rate of 20 GPU to 18,000 GPU. The hydrogen / nitrogen separation factor is preferably 3 or more and less than 15. Examples of the shape of the water vapor separation membrane include a hollow fiber shape and a flat membrane shape. A hollow fiber shape is preferred.

  The nitrogen permeation rate of the water vapor separation membrane falls within the above specified range by adjusting the thickness of the water vapor separation resin layer while taking into account the nitrogen permeation rate of the porous support membrane. Here, as the water vapor separation resin layer becomes thicker, the nitrogen permeation rate of the water vapor separation membrane decreases, but the water vapor separation resin having a low nitrogen permeability coefficient compared to the water vapor separation resin having a high nitrogen permeability coefficient is less than the layer thickness. The degree of decrease in nitrogen permeation rate is large. Further, the hydrogen / nitrogen separation coefficient of the water vapor separation membrane falls within the above specified range by appropriately combining the water vapor separation resin and the porous support membrane.

〔Production method〕
The method for producing a water vapor separation membrane of the present embodiment includes a step of melt-kneading a mixture containing an organic polymer resin, a plasticizer, and inorganic particles, a step of forming a melt-kneaded mixture to obtain a molded body, The method includes a step of obtaining a porous support membrane by extracting a plasticizer from the molded body, and a step of laminating a water vapor-separating resin on the surface of the porous support membrane. Hereinafter, the manufacturing method of this embodiment will be described in detail.

[Process of melt-kneading]
In the melt-kneading step of this embodiment, a mixture containing an organic polymer resin, a plasticizer, and inorganic particles is melt-kneaded.

  The blending amount of the inorganic particles, the plasticizer, and the organic polymer resin is preferably within the following range with respect to the total capacity of the mixture of the inorganic particles, the plasticizer, and the organic polymer resin. That is, the inorganic particles are preferably 3 to 60% by mass, more preferably 7 to 42% by mass, and still more preferably 15 to 30% by mass. 20-85 mass% is preferable, as for a plasticizer, 30-75 mass% is more preferable, and 40-70 mass% is further more preferable. The organic polymer resin is preferably 5 to 80% by mass, more preferably 10 to 60% by mass, and still more preferably 15 to 30% by mass.

  If the inorganic particles are 3% by mass or more, the inorganic particles can sufficiently adsorb the plasticizer, the mixture can be maintained in a powder or granule state, and it becomes easy to mold. Moreover, if it is 60 mass% or less, the fluidity | liquidity of the mixture at the time of fuse | melting will be good, and a moldability will become high. In addition, the strength of the obtained molded product is improved.

  If the plasticizer is 20% by mass or more, the amount of the plasticizer is sufficient, a sufficiently developed communication hole is formed, and a porous structure in which the communication hole is sufficiently formed can be obtained. Moreover, if it is 85 mass% or less, it will become easy to shape | mold and a porous support membrane with high mechanical strength will be obtained.

  When the organic polymer resin is 5% by mass or more, the amount of the organic polymer resin that forms the trunk of the porous structure is sufficient, and the strength and moldability are improved. Moreover, if it is 80 mass% or less, it can be set as the porous support membrane in which the communicating hole was fully formed.

  Examples of the mixing method of the inorganic particles, the plasticizer, and the organic polymer resin include a normal mixing method using a compounding machine such as a Henschel mixer, a V-blender, and a ribbon blender. As the mixing order, the inorganic particles, the plasticizer and the organic polymer resin are mixed at the same time, and the inorganic particles and the plasticizer are mixed to sufficiently adsorb the plasticizer to the inorganic particles, and then the organic polymer. Examples of the method include mixing and mixing a resin. When mixed in the latter order, the moldability at the time of melting is improved, the communication holes of the resulting porous support membrane are sufficiently developed, and the mechanical strength is also improved.

  In order to obtain a homogeneous ternary composition, the mixing temperature is in a temperature range in which the mixture is in a molten state, that is, in a temperature range not lower than the melt softening temperature of the organic polymer resin and not higher than the thermal decomposition temperature. However, the mixing temperature should be appropriately selected depending on the melt index of the organic polymer resin, the boiling point of the plasticizer, the type of inorganic particles, the function of the heating and kneading apparatus, and the like.

[Plasticizer]
In the present embodiment, the plasticizer refers to a liquid having a boiling point of 150 ° C. or higher. The plasticizer contributes to the formation of a porous structure when the melt-kneaded mixture is formed, and is finally extracted and removed. The plasticizer is not compatible with the organic polymer resin at a low temperature (normal temperature), but is preferably compatible with the organic polymer resin at the time of melt molding (high temperature).

  The plasticizer preferably has a solubility parameter (SP: δ) in the range of 15 to 21 [(MPa) 1/2]. More preferably, it is a plasticizer of 18-19 [(MPa) 1/2].

  Examples of plasticizers having a solubility parameter of 15 to 21 [(MPa) 1/2] include phthalate esters such as diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), and phosphoric acid. Examples include esters. Among these, in particular dioctyl phthalate (δ = 18.3 [(MPa) 1/2] (dispersion component δD = 16.6, polar component δP = 7.0, hydrogen bonding component δH = 3.1)), Dibutyl phthalate (δ = 20.2 [(MPa) 1/2] (δD = 17.8, δP = 8.6, δH = 4.1)) (J. BRANDRUP and EH IMMERGUT, POLYMER HANDBOOK THIRD EDITION, page VII-542, 1989), and mixtures thereof are preferred. Dioctyl phthalate is a general term for compounds having two ester moieties each having 8 carbon atoms, and includes, for example, di-2-ethylhexyl phthalate.

  Here, when mixing 2 or more types of plasticizers, the solubility parameter of the mixed plasticizers can be calculated by the following method.

  For example, the SP of the plasticizer (A) is δ (A), and the dispersion component, polar component, and hydrogen bond component of δ (A) are δD (A), δP (A), and δH (A), respectively. When the SP of the plasticizer (B) is δ (B), and the dispersion component, polar component, and hydrogen bond component of δ (B) are δD (B), δP (B), and δH (B), respectively, Δ (C), which is the SP of the mixture (C) in which the plasticizers (A) and (B) are mixed at a ratio of m: n, is a dispersion component δD (C) of δ (C) and a polar component δP (C) The hydrogen bond component δH (C) can be determined and determined.

δD (C) = {mδD (A) + nδD (B)} / (m + n)
δP (C) = {mδP (A) + nδP (B)} / (m + n)
δH (C) = {mδH (A) + nδH (B)} / (m + n)
δ (C) = [{δD (C)} 2+ {δP (C)} 2+ {δH (C)} 2] 1/2.

  It is preferable that δ (C), which is the SP of the mixed plasticizer, is in the range of 15 to 21 [(MPa) 1/2]. More preferably, the SP of the plasticizer to be mixed is in the range of 15 to 21 [(MPa) 1/2].

  In the present embodiment, the size of the pores of the porous support membrane can be controlled by appropriately selecting a plasticizer. From the viewpoint of water vapor permeability, it is better that the apertures are large. On the membrane surface, the presence of inorganic particles in the large apertures makes it possible to uniformly laminate the water vapor separating resin on the membrane surface. Specifically, for example, when polyethylene is included as the organic polymer resin of the porous support membrane, DBP is used as a plasticizer, and when PVDF is included, DOP is used as a plasticizer, thereby forming large pores. A porous support membrane is obtained.

  In addition, a lubricant, an antioxidant, an ultraviolet absorber, a plasticizer, a molding aid, and the like may be added as necessary as long as the effects of the present invention are not significantly impaired.

[Step of obtaining a molded body]
In the step of obtaining the molded body of this embodiment, a melt-kneaded mixture is molded. Examples of the method for forming the melt-kneaded mixture include extrusion molding such as T-die method, inflation method, and method using a hollow die, calendar molding, compression molding, injection molding, and the like. It is also possible to directly form the mixture by an apparatus having both kneading and extruding functions, such as an extruder and a kneader ruder.

  When molding, it is preferable to mold so that the thickness of the molded body is 0.01 to 50 mm. More preferably, it is 0.01-30 mm, More preferably, it is 0.02-0.5 mm. In the case of reducing the thickness, the molding method by the extrusion molding is suitable. Further, by appropriately selecting the molding method, the molded body can be formed into a hollow fiber shape, a flat membrane shape, or the like.

[Step of obtaining porous support membrane]
In the step of obtaining the porous support membrane of the present embodiment, the plasticizer is extracted from the molded body using a solvent. As a result, the organic polymer resin forms a porous structure having openings and communication holes, and a porous support membrane in which at least a part of the inorganic particles are present in the openings is obtained. In the formed porous support film, a part of the communication holes may form an opening. The solvent used for extraction can dissolve the plasticizer and does not substantially dissolve the organic polymer resin. Examples of the solvent used for extraction include methanol, acetone, halogenated hydrocarbons and the like. In particular, halogen-based hydrocarbons such as 1,1,1-trichloroethane and trichloroethylene are preferable.

  The extraction can be performed by a general extraction method such as a batch method or a countercurrent multistage method. After extraction of the plasticizer, the solvent may be removed by drying as necessary.

  The method for removing the plasticizer is not limited to the above-described extraction, and various commonly used methods can be employed.

[Stretching / shrinking process]
In this embodiment, it is preferable to have the process of extending | stretching a molded object and removing after that, before or after removal of a plasticizer. Thereby, even when the yarn is stretched to the maximum yarn length during drawing during use, it is not cut and the mechanical strength is improved.

In particular, when the formed body is in the form of a hollow fiber, it is preferable that the molded body is stretched along the length direction of the yarn and then contracted. At this time, with respect to the extent of stretching and shrinkage, the yarn length shrinkage represented by the following formula is preferably in the range of 0.3 to 0.9.
Yarn length shrinkage rate = {(maximum yarn length during drawing) − (yarn length after shrinkage)} / {(maximum yarn length during drawing) − (original yarn length)}

  For example, when a 10 cm yarn is stretched to 20 cm and then made 14 cm, the yarn length shrinkage (20-14) / (20-10) = 0.6 from the above formula. If the yarn length shrinkage is 0.9 or less, the gas permeability is high. If it is 0.3 or more, the tensile elastic modulus can be kept low. The yarn length shrinkage is more preferably 0.50 or more and 0.85 or less.

Further, the ratio Z representing the degree of guarantee of elongation at break is preferably 0.2 or more and 1.5 or less. Z can be defined by the following formula, where X is the draw ratio and Y is the yarn length shrinkage with respect to the yarn length increment by drawing.
Z = (maximum yarn length during drawing−yarn length after shrinkage) / yarn length after shrinkage = (XY−Y) / (X + Y−XY)

  If the value of Z is too small, the guarantee of elongation at break is reduced, and if it is too large, the possibility of breaking at the time of stretching increases, and the gas permeability also decreases. By including the process of extending | stretching and shrinking | contracting, the fracture | rupture at a tensile elongation at break becomes very few, and the distribution of tensile elongation at break can be narrowed. More preferably, Z is 0.3 or more and 1.0 or less.

  The space temperature in the step of stretching and then shrinking is preferably in the range of 0 ° C. or more and 160 ° C. or less from the viewpoint of shrinkage time and physical properties. More preferably, it is 0 degreeC or more and 100 degrees C or less. If it is lower than 0 ° C., it takes time to shrink and is not practical. If it exceeds 160 ° C., the elongation at break and the gas permeability are lowered.

[Process of laminating water vapor separating resin]
In the step of laminating the water vapor separating resin, the water vapor separating resin is laminated on the surface of the porous support membrane by a dip coating method or the like.

[Use of steam separation membrane]
The water vapor separation membrane of this embodiment is suitably used for separation methods such as the PV method and the VP method. In addition, it can be used as a membrane for various water vapor separations. Depending on the conditions, it is also possible to obtain a water vapor separation membrane that can maintain strength and heat resistance, and water vapor separation properties under heat resistant conditions. The water vapor separation membrane having such excellent performance can be used as, for example, a water vapor separation membrane for gas purification used in an internal combustion engine system.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

[B. Pressure measurement of porous support membrane by P method]
B. porous support membrane The pressure by the P method is a pressure when bubbles are first ejected from the film in the half dry method, and was performed by the following method. That is, ethanol was used as the liquid to be used, and measurement at 25 ° C. and a pressure increase rate of 0.001 MPa / second was used as standard measurement conditions. Since the surface tension of ethanol at 25 ° C. is 21.97 mN / m (The Chemical Society of Japan, Chemistry Handbook Basic Edition, Rev. 3, II-82, Maruzen Co., Ltd., 1984), the standard measurement conditions in the present invention In this case, the maximum pore diameter can be estimated by the following formula.
Maximum pore diameter [μm] = 62834.2 / (bubble generating air pressure [Pa])

[Measurement method of gas permeation rate and hydrogen / nitrogen separation coefficient of porous support membrane and water vapor separation membrane]
A pencil module for evaluating permeation performance having an effective length of 20 cm was formed using a single hollow fiber porous support membrane, a stainless steel pipe, and an epoxy resin adhesive. FIG. 3 shows a schematic diagram of the pencil module 10. The pencil module 10 includes a stainless pipe 11 having a fluid supply port 11a and a fluid discharge port 11b. Inside the stainless steel pipe 11, a permeation performance evaluation sample (porous support membrane or water vapor separation membrane) 12 is disposed, and both ends of the permeation performance evaluation sample 12 are fixed by an adhesive 13. At the end of the stainless steel pipe 11 on the fluid discharge port 11 b side, the opening at the end of the sample 12 for permeability performance and the opening of the stainless steel pipe 11 are closed by the adhesive 13. At the end of the stainless steel pipe 11 on the side of the fluid supply port 11a, the opening of the stainless steel pipe 11 is blocked by the adhesive 13, but the opening of the sample 12 for permeability performance evaluation is not blocked. A fluid discharge port 11c is formed. Although not shown, a measuring device for measuring the flow rate of the permeated fluid is connected to the permeating fluid discharge port 11c.

  Using the pencil module 10, nitrogen gas was supplied from the fluid supply port 11 a to the outside of the hollow fiber-shaped sample 12 for permeation performance evaluation at a temperature of 25 ° C. and a pressure of 35 kPa. Of the supplied nitrogen gas, the nitrogen gas that has not permeated the inside of the hollow fiber-shaped permeation performance evaluation sample 12 is discharged from the fluid discharge port 11b, and the gas that has permeated the inside of the permeation performance evaluation sample 12 is permeated fluid. It is discharged from the discharge port 11c. The flow rate discharged from the permeated fluid discharge port 11c was measured. The nitrogen permeation rate was calculated from the measured permeation flow rate, supply side pressure (35 kPa), permeation side pressure, and effective membrane area.

  Moreover, the gas permeation rate of the water vapor separation membrane in the standard state was calculated from the permeated flow rate, temperature, and atmospheric pressure, and the hydrogen / nitrogen separation factor was calculated from the ratio of the gas permeation rate of hydrogen and nitrogen.

[PV performance evaluation method]
The test which selectively isolate | separates water from IPA aqueous solution by PV method was done using the apparatus shown in FIG. 4 provided with the pencil module 10 shown in FIG. 3, and PV performance was evaluated. In the apparatus shown in FIG. 4, a hollow fiber water vapor separation membrane is arranged in the pencil module 10 as the permeation performance evaluation sample 12. In the evaluation of the PV performance, an IPA 50 mass% aqueous solution stored in the tank 15 is supplied to the fluid supply port of the pencil module 10 via the flow meter 17 through the pipe 14b by the circulation pump 16 in a state of 75 ° C. . At this time, the inside of the water vapor separation membrane in the pencil module 10 is decompressed by the vacuum pump 25. Of the supplied aqueous solution, the fluid that permeates from the outside to the inside of the water vapor separation membrane disposed in the pencil module 10 is sucked by the vacuum pump 25 and cooled by liquid nitrogen through the pipe 21a. 23. A vacuum gauge 22 is provided in the pipe 21a. On the other hand, of the supplied aqueous solution, the fluid that has not permeated the water vapor separation membrane is returned to the tank 15 through the pipe 14a.

This series of operations was performed for 100 minutes, and this was taken as one operation unit. Then, the mass of water in the cooling trap 23 collected for 100 minutes is measured, and the permeation flux (Q) [kg / m ² / hr] is obtained by determining the permeation amount per unit area and unit time of the membrane. Asked. In addition, by measuring the IPA concentration contained in the trapped water using a refractometer (digital isopropyl alcohol concentration meter PR-60PA: manufactured by Atago Co., Ltd.), the water separation factor for IPA (hereinafter referred to as “water / IPA”). "Separation factor"). Specifically, the IPA and water mass concentrations (initial concentrations) on the supply side are X1 mass% and X2 mass%, respectively, and the IPA and water concentrations in the trap on the transmission side are Y1 mass% and Y2 respectively. Assuming mass%, the water / IPA separation factor is calculated by the following equation.
Water / IPA separation factor = (X1 / X2) / (Y1 / Y2)

  The above measurement was repeated 12 times, and when the first water permeation flow rate was 100%, the value of the 12th water permeation flow rate was defined as the water permeation flow rate retention rate (%) and used as an index of durability. Moreover, the evaluation value of the permeation | transmission flow rate and water / IPA separation factor of a to-be-evaluated object was made into the average value of 12 measurements.

[Example 1]
25.5 parts by mass of finely divided silica (manufactured by Nippon Aerosil Co., Ltd .: R-972) as inorganic particles and 50.5 parts by mass of dibutyl phthalate (DBP) as a plasticizer are mixed with a Henschel mixer, and an organic polymer resin is mixed therewith. As a result, 24.0 parts by mass of high-density polyethylene (manufactured by Asahi Kasei Kogyo: SH800) was added and mixed again with a Henschel mixer. This mixture was mixed and pelletized with a twin-screw kneading extruder, and the resulting pellet was melt-kneaded at 220 ° C.

  The melt kneading was carried out from an annular hole for extruding a melt (outer diameter 1.40 mm, inner diameter 0.70 mm) with an extrusion surface of a hollow fiber forming spinning nozzle attached to an extrusion port in the head at the tip of the extruder. Inside the hollow part of the hollow fiber-like extrudate, the mixture is extruded and nitrogen gas is discharged as a hollow part forming fluid from a circular hole (diameter 0.6 mm) for discharging the hollow part forming fluid inside the annular hole for melt extrusion. And wound up at a speed of 10 m / min to obtain a hollow fiber-like product.

  The obtained hollow fiber-like material was immersed in methylene chloride as a solvent to extract and remove DBP as a plasticizer and then dried to obtain a porous support membrane. When the obtained porous support membrane was observed by SEM, it was found that pores were formed on the membrane surface and silica was present in the pores (FIG. 5 (b)). Moreover, when the cross section of the porous support membrane was observed by SEM, it was found that communication holes were formed inside the membrane and silica was present inside the communication holes (FIG. 5A). It was also found that the communication holes were connected to the membrane surface to form openings, and silica was present in the openings.

  Next, 1.2% by mass of water vapor separating resin A (manufactured by DuPont: Teflon AF1600) was dissolved in 98.8% by mass of a fluorine-based solvent Novec 7300 (manufactured by Sumitomo 3M) to obtain a coating solution. Using this coating solution, dip coating was performed on the outer surface of the porous support membrane at a lifting speed of 2.5 m / min and a drying condition of 120 ° C. for 3 minutes, and the water vapor separating resin A was laminated. A water vapor separation membrane was obtained. The result of having observed the obtained water vapor separation membrane by SEM is shown in FIG. It can be seen that the water vapor separating resin layer is uniformly formed. Table 1 shows the performance of the water vapor separating resin A used and the performance of the obtained porous support membrane and the water vapor separating membrane.

[Example 2]
In Example 1, a porous support membrane and a water vapor separation membrane were produced in the same manner as in Example 1 except that 8 parts by mass of fine silica, 68 parts by mass of DBP, and 24 parts by mass of high-density polyethylene were used. The performance of the obtained porous support membrane and water vapor separation membrane is shown in Table 1.

[Example 3]
In Example 1, a porous support membrane and a water vapor separation membrane were produced in the same manner as in Example 1 except that 69 parts by mass of finely divided silica, 7 parts by mass of DBP, and 24 parts by mass of high-density polyethylene were used. The performance of the obtained porous support membrane and water vapor separation membrane is shown in Table 1.

[Comparative Example 1]
A porous support membrane and a water vapor separation membrane were produced in the same manner as in Example 1 except that finely divided silica as inorganic particles was not added and DBP was changed to 76.0 parts by mass. When the obtained porous support membrane was observed using SEM, it was found that although pores were formed on the membrane surface, silica was not present in the pores (FIGS. 6A and 6B). )). The performance of the obtained porous support membrane and water vapor separation membrane is shown in Table 1.

[Comparative Example 2]
In Example 1, a porous support membrane and a water vapor separation membrane were produced in the same manner as in Example 1 except that 5 parts by mass of fine silica, 71 parts by mass of DBP, and 24 parts by mass of high-density polyethylene were used.

As shown in Comparative Example 1, when inorganic particles are not added, B. of the porous support membrane obtained is shown. P. Is less than 650 kPa, and the resulting B. P. The water vapor separation membrane obtained is low in water vapor separation (hydrogen / nitrogen) and water / IPA separation by the PV method. On the other hand, as shown in Comparative Example 2, even when the amount of inorganic particles added is not sufficient, almost no inorganic particles are present in the pores on the membrane surface (B / A is 0.1), and the resulting water vapor separation membrane is In addition, hydrogen / nitrogen separability, water / IPA separability by PV are low, durability is not sufficient, and water permeation flow rate retention is greatly below 80%.
In contrast, Examples 1 to 3 have a sufficient permeation flow rate, high durability, and high separability.

[Example 4]
23.0 parts by mass of finely divided silica (manufactured by Nippon Aerosil Co., Ltd .: R-972) as inorganic particles, 30.8% by mass of dioctyl phthalate and 6.2% by mass of dibutyl phthalate as plasticizers (SP of the mixture of the two) : 18.59 (MPa) 1/2) and a Henschel mixer, and the organic polymer resin is polyvinylidene fluoride having a mass average molecular weight of 290000 (manufactured by Kureha Chemical Industry Co., Ltd .: KF polymer # 1000 (product) Name)) 40% by mass was added and mixed again with a Henschel mixer. The obtained mixture was further melt-kneaded with a 48 mmφ twin screw extruder to form pellets.

  The pellets were continuously charged into a 30 mmφ biaxial extruder, and melt extruded at 240 ° C. while supplying air into the hollow portion from an annular nozzle attached to the tip of the extruder. The extrudate was cooled and solidified by passing through an air travel of about 20 cm through a water bath at 40 ° C. at a spinning speed of 20 m / min to obtain hollow fibers.

  This hollow fiber is continuously taken up at a speed of 20 m / min with a pair of first endless track belt take-up machines, and passed through a first heating tank (0.8 m long) controlled at a space temperature of 40 ° C. Further, the second endless track type belt take-up machine similar to the first endless track type belt take-up machine was pulled up 2.0 times at a speed of 40 m / min. Further, after leaving the second heating tank (0.8 m length) controlled at a space temperature of 80 ° C., the hollow fiber is taken up at a speed of 30 m / min with a third endless track belt take-up machine 1.5 times. And then wound up with a casserole having a circumference of about 3 m. The endless track type belt of any endless track type belt take-up machine is a belt in which an elastic body made of silicone rubber is bonded and integrated on a fiber reinforced belt, and the elastic body made of silicone rubber on the outer surface side in contact with the hollow fiber. The thickness was 11 mm and the compression modulus in the thickness direction was 0.9 MPa. The yarn length shrinkage with respect to the yarn length increment due to drawing is 0.5.

  Next, the hollow fibers were bundled and immersed in methylene chloride at 30 ° C. for 1 hour, and this was repeated 5 times to extract dioctyl phthalate and dibutyl phthalate, followed by drying to obtain a porous support membrane. When the obtained porous support membrane was observed using SEM, it was found that pores were formed on the membrane surface and silica was present in the pores (FIG. 7 (b)). Moreover, when the cross section of the porous support membrane was observed by SEM, it was found that pores were formed inside the membrane and silica was also present inside the pores (FIG. 7 (a)). It was also found that pores were formed on the film surface and silica was present in the pores.

  A water vapor separation membrane was produced in the same manner as in Example 1 except for the above. Table 2 shows the performance of the water vapor-separating resin A used and the performance of the obtained porous support membrane and water vapor separation membrane.

[Example 5]
In Example 4, a water vapor separation membrane was obtained in the same manner as in Example 4 except that the water vapor separation resin B (manufactured by DuPont: Teflon AF 2400) was used instead of the water vapor separation resin A (Teflon AF 1600). . Table 2 shows the performance of the water vapor separating resin B used and the performance of the obtained porous support membrane and water vapor separating membrane.

[Example 6]
In Example 4, instead of the water vapor separating resin A (Teflon AF1600), a coating composed of 1.2% by mass of water vapor separating resin C (manufactured by Asahi Glass Co., Ltd .: Cytop CTL-107MK) and 98.8% by mass of CT-SOLV100K. A water vapor separation membrane was obtained in the same manner as in Example 4 except that the liquid was used. Table 2 shows the performance of the water vapor separating resin C used and the performance of the obtained porous support membrane and the water vapor separating membrane.

[Comparative Example 3]
In Example 4, instead of the water vapor-separating resin A (Teflon AF1600), a coating liquid composed of 1.2% by mass of polysulfone P-3500 (manufactured by Solvay) and 98.8% by mass of N-methyl-2-pyrrolidone. A water vapor separation membrane was obtained in the same manner as in Example 4 except that. The performance of the water vapor separating resin D used, and the performance of the obtained porous support membrane and the water vapor separation membrane are shown in Table 1, and the performance of the porous support membrane and the water vapor separation membrane shown in Table 2.

  As shown in Examples 4 to 6, when a porous support membrane produced under predetermined conditions is used, various different water vapor separation resins can be applied, and the resulting water vapor separation membrane has sufficient physical properties. It showed excellent hydrogen / nitrogen properties, and water / IPA separation and durability by the PV method showed performance that could withstand practical use. On the other hand, Comparative Example 3 has a low nitrogen permeation rate of the water vapor separating resin and a very low permeation flow rate of the water vapor separation membrane.

  DESCRIPTION OF SYMBOLS 1 ... Steam separation membrane, 2 ... Steam separation resin layer, 3 ... Porous support membrane, 4 ... Opening hole, 5 ... Inorganic particle, 6 ... Communication hole, 10 ... Pencil module, 11 ... Stainless steel pipe, 11a ... Gas supply 11b ... Gas outlet, 11c ... Permeate gas outlet, 12 ... Porous support membrane, 13 ... Adhesive, 14a ... Pipe, 14b ... Pipe, 15 ... Tank, 16 ... Circulation pump, 17 ... Flow meter, 21a ... Piping, 21b ... Piping, 22 ... Vacuum gauge, 23 ... Cooling trap, 25 ... Vacuum pump.

Claims (14)

A water vapor separation membrane comprising a porous support membrane and a water vapor separation resin layer laminated on the porous support membrane,
The porous support membrane includes an organic polymer resin and inorganic particles,
An opening is formed on the surface of the porous support membrane on which the water vapor separating resin layer is laminated, and at least a part of the inorganic particles are present in the opening,
The ratio of the area ratio of the inorganic particles to the surface on the water vapor separating resin side to the hole area ratio on the surface on which the water vapor separating resin layer of the porous support membrane is laminated is 0.2 to 4. Yes,
The water vapor separation resin layer is a water vapor separation membrane having a nitrogen permeability coefficient of 1 to 900 barrer and a hydrogen separation coefficient of 2 to 15.   The water vapor separation membrane according to claim 1, wherein the porous support membrane has a communication hole therein, and a part of the communication hole forms the opening.   The water vapor separation membrane according to claim 1 or 2, wherein the porous support membrane contains 25 to 85 mass% of the inorganic particles.   The water vapor separation membrane according to any one of claims 1 to 3, wherein the porous support membrane has a nitrogen permeation rate of 3500 GPU or more and a pressure by a bubble point method of 650 kPa or more. The water vapor according to any one of claims 1 to 4, wherein the inorganic particles have an average primary particle size of 0.005 to 0.5 µm and a specific surface area of 30 m ² / g or more and 500 m ² / g or less. Separation membrane.   The water vapor separation membrane according to any one of claims 1 to 5, wherein the inorganic particles are silica.   The water vapor separation membrane according to any one of claims 1 to 6, wherein the organic polymer resin is a thermoplastic resin.   The water vapor separation membrane according to claim 7, wherein the thermoplastic resin contains at least one selected from the group consisting of polyolefins and halogenated polyolefins.   The water vapor separation membrane according to any one of claims 1 to 8, wherein the water vapor separation resin layer contains a fluororesin.   The fluororesin comprises a copolymer of perfluoro 2,2-dimethyl-1,3-dioxole and tetrafluoroethylene, polyperfluoromethyl vinyl ether, polyvinylidene fluoride, polyhexafluoropropylene, and polychlorotri The water vapor separation membrane according to claim 9, which is at least one selected from the group consisting of fluoroethylene.   The steam separation membrane according to any one of claims 1 to 10, wherein the shape of the steam separation membrane is hollow.   The water vapor separation membrane according to any one of claims 1 to 11, wherein a separation factor of hydrogen with respect to nitrogen is 3 or more and less than 15.   A water vapor permeable membrane for pervaporation using the water vapor separation membrane according to any one of claims 1 to 12. It is a manufacturing method of the water vapor separation membrane according to any one of claims 1 to 13,
Melting and kneading the mixture containing the organic polymer resin, the inorganic particles and the plasticizer;
Molding the melt-kneaded mixture to obtain a molded body;
Extracting the plasticizer from the molded body to obtain a porous support membrane;
Laminating a water vapor separating resin layer on the surface of the porous support membrane;
A method for producing a water vapor separation membrane.