Gas separation composite membrane

The present invention relates to a gas separation composite membrane and a method for producing a porous body for use in a support provided in the gas separation composite membrane.

The gas separation membrane separates gases such as oxygen, nitrogen and carbon dioxide from air, or increases (concentrates) the concentration of these gases, or carbon monoxide and nitrogen oxidation mixed from a combustion system, reaction system, etc. It is used for the purpose of removing highly toxic gases such as substances and sulfur oxides. In particular, in the fields of combustion equipment, air conditioning equipment, medical equipment, health equipment, etc., the concentration of oxygen in the air has attracted attention, and a gas separation membrane for the purpose of oxygen enrichment (hereinafter referred to as "oxygen enrichment membrane"). ) Has been developed so far.

For example, a siloxane-based polymer known as a material used for an oxygen-enriched membrane has a separation coefficient between oxygen and nitrogen (PO).₂/ PN₂) Is 1.5 ~ 2.5 [-], oxygen permeability coefficient is 1 × 10^-8~1×10^-9[cm³(STP) cm / cm²-Sec · cmHg] (see, for example, Patent Document 1), and oxygen-enriched air can be obtained by allowing air to permeate through a thin film of this siloxane-based polymer having a thickness of about 100 nm.

Since it is difficult to handle a thin film as described above by itself, a gas separation composite membrane laminated on a support as a gas separation membrane is usually used for purposes such as oxygen enrichment.

As the support for laminating thin films, a breathable porous body is often used. As the porous body used for the gas separation composite membrane, for example, a porous body made of polyimide (see, for example, Patent Document 2), a porous body made of fluororesin (for example, see Patent Document 3), and the like are known. However, although these porous bodies are excellent in terms of mechanical strength and the like, they are expensive. Therefore, a porous body made of an ethylene-based polymer, which is a cheaper material, is generally used.

As a method for obtaining a porous body made of an ethylene polymer, a stretching method obtained by opening the particle interface by stretching an ethylene polymer mixed with particles such as silica (see, for example, Patent Document 4). Or, an extraction method obtained by extracting a liquid agent from an ethylene-based polymer mixed with a liquid agent to form a predetermined shape (see, for example, Patent Document 5), and sintering fine powder of the ethylene-based polymer. (For example, refer to Patent Document 6) and the like are known. Among these, the porous body produced by the stretching method is the cheapest and is used for various purposes such as electronic devices and building materials.<patcit num="1"><text>Japanese Patent Application Laid-Open No. 56-26504</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 2001-145826</text></patcit><patcit num="3"><text>Japanese Unexamined Patent Publication No. 3-179038</text></patcit><patcit num="4"><text>Japanese Unexamined Patent Publication No. 3-80923</text></patcit><patcit num="5"><text>Japanese Unexamined Patent Publication No. 4-170446</text></patcit><patcit num="6"><text>Japanese Unexamined Patent Publication No. 2002-265657</text></patcit>

<p> As a method for obtaining a gas-separated composite membrane, a polymer thin film is formed by developing a polymer organic solvent solution on the water surface using surface tension, and the thin film is scooped up with a support to remove water. (Hereinafter referred to as "water surface development method") is preferably used. According to the water surface development method, a gas separation layer made of a thin film having a film thickness of 100 nm or less can be efficiently formed.</p><p> However, when the porous body of the ethylene polymer obtained by the stretching method is used as the support, in the gas separation composite membrane obtained by a production method involving contact between the material and water, such as a water surface development method or the like. Has a problem that the gas separation layer laminated on the support is likely to be lifted from the support or the gas separation layer is easily broken.</p><p> When such floating or tearing occurs, it is difficult to fulfill the function of the gas separation composite film. In particular, when the water surface development method or the like is adopted, in order to efficiently obtain the gas separation composite film, the gas separation composite film is lifted or broken. There is a strong demand to suppress the occurrence of tears.</p><p> The present invention has been made in view of the above circumstances, and provides a gas separation composite membrane that can be manufactured at low cost while suppressing the occurrence of floating and tearing of the gas separation layer and has excellent gas permeability. The purpose is to provide.</p>

<p> In order to solve the above problems, the gas separation composite film of the present invention is a gas separation composite film provided with a gas separation layer on a support, and the support is a porous body of an unstretched ethylene polymer. The gas-separated layer is characterized by being composed of a polymer thin film that is phase-separated into a phase in a rubber state or a molten state and a phase in a glass state or a crystalline state.</p><p> By combining such a support and a gas separation layer, it is possible to manufacture the gas at low cost while suppressing the occurrence of floating and tearing of the gas separation layer, and the gas has excellent gas permeability. A separation composite membrane is obtained.</p><p> When the water surface development method is adopted, water absorption and dehydration are involved in the support. Therefore, it is possible to use a porous body having excellent dimensional stability in the process of water absorption and dehydration as the support. It is considered to be effective for suppressing the occurrence of tearing.</p><p> According to the present invention, the unstretched porous body of the ethylene-based polymer is superior in dimensional stability in the process of water absorption and dehydration as compared with the porous body of the ethylene-based polymer obtained by the stretching method. They found. This is because the strain applied during stretching remains in the stretched porous body of the ethylene-based polymer, and permeation occurs when the water that fills the open pores of the porous body is removed by water absorption. When the pressure is released, the porous body shrinks so as to eliminate the strain, whereas in the porous body made of an unstretched ethylene polymer, the strain as described above remains. It is presumed that this is because it has not been done.</p><p> However, even if a support having excellent dimensional stability as described above is used, if the adhesion between the support and the gas separation layer is insufficient, floating may easily occur, and this adhesion should be enhanced. Also became clear to be important.</p><p> As a result of further studies based on this finding, the polymer whose support is phase-separated into a specific polymer, that is, a phase in a rubber state or a molten state and a phase in a glass state or a crystalline state. By combining the above as a gas separation layer, the adhesion between the support and the gas separation layer can be enhanced while maintaining the strength and heat resistance of the gas separation layer, and a sufficient effect of preventing floating can be obtained. The finding has led to the completion of the present invention.</p><p> Since the above-mentioned polymer has a property that the phase in the rubber state or the molten state is easily deformed, the polymer as a whole is easily stretched. Therefore, the gas separation layer has excellent shape followability, and even if air is embraced between the support and the gas separation layer and a portion where the gas separation layer floats occurs, the gas separation layer follows the surface shape of the support. By gradually deforming the gas separation layer in this way, the final floating is suppressed.</p><p> Ethylene-based polymers that make up the support are generally considered to have poor chemical affinity with other polymers, but when combined with a thin film of a specific polymer as described above, good adhesion is achieved. Sex is obtained.</p><p> Further, the gas separation layer may be a polymer thin film containing an organopolysiloxane skeleton represented by the following general formula (1) and an imide skeleton represented by the following general formula (2).</p><p><chemistry num="1"><img file="JP2005296821A_D0001.tif" /></chemistry></p><p><chemistry num="2"><img file="JP2005296821A_D0002.tif" /></chemistry>[In the formula, R¹, R², R³And R⁴Are independently monovalent aliphatic groups or monovalent aromatic groups, X is a tetravalent aromatic group, Y, Z¹And Z²Independently indicate a divalent aliphatic group or a divalent aromatic group, and r is a positive integer. ]</p><p> Such a thin film containing an organopolysiloxane skeleton and a polymer containing an imide skeleton (hereinafter referred to as "polyimidesiloxane") has an excellent shape-following property due to the inclusion of the organopolysiloxane skeleton, and is an ethylene-based polymer. Adhesion to the porous body made of is improved. Therefore, by combining with the support having excellent dimensional stability as described above, the occurrence of floating and tearing is suppressed, and a gas separation layer particularly suitable for oxygen enrichment can be obtained.</p><p> In the structure of the polyimidesiloxane, a linear molecular chain composed of an organopolysiloxane skeleton is spirally wound, and the spiral functions as a path for permeating the gas, so that the gas is permeable. Is considered to be high. Further, the organopolysiloxane skeleton is considered to preferentially permeate oxygen because it contains abundant oxygen atoms and has high solubility of oxygen gas.</p><p> The polyimidesiloxane preferably contains the above-mentioned organopolysiloxane skeleton in an amount of 35% by mass or more based on the mass of the polyimidesiloxane. By setting the content of the organopolysiloxane skeleton to 35% by mass or more, the thin film becomes more easily stretchable, and the gas permeability of the obtained gas separation composite membrane is further enhanced.</p><p> The polyimidesiloxane as described above is usually referred to as a phase containing an organopolysiloxane skeleton as a main component (hereinafter referred to as "siloxane phase") and a phase containing an imide skeleton as a main component (hereinafter referred to as "imide phase"). The siloxane phase is in a rubber state or a molten state, and the imide phase is in a glass state at room temperature. By having the imide phase, the heat resistance and mechanical strength of the polyimidesiloxane as a whole are maintained.</p><p> The polymer is preferably a polymer having an elongation of 80% or more in order to further enhance the adhesion to the support.</p><p> Further, since the polymer thin film is a thin film obtained by developing the polymer on the water surface, it is easy to reduce the thickness of the gas separation layer, and the gas separation composite film is excellent in gas permeability. Is preferable because it can be obtained efficiently.</p><p> It is preferable that the unstretched porous body of the ethylene polymer has a shrinkage rate of 0 to 10% when immersed in water at 20 ° C. for 10 seconds and further left at 23 ± 2 ° C. for 1 hour. .. By setting the shrinkage rate in the above range, it becomes easier to obtain the effect of suppressing lifting and tearing.</p><p> Further, this porous body is particularly excellent in dimensional stability because it has open pores in which cohesive fine particles are attached to the pore wall, and the following porous body of the present invention is produced. It is preferable in that it can be efficiently obtained by adopting the method.</p><p> The present invention is also a method for producing a porous body for use as a support for a gas separation composite membrane, in which the liquid agent is removed from a mixture of a cohesive fine particles, a liquid agent, and an unstretched ethylene polymer. It is characterized by doing. The porous body obtained by this production method is excellent in dimensional stability, and can be suitably used, for example, as a support for the gas separation composite membrane of the present invention.</p>

<p> According to the present invention, it is possible to obtain a gas separation composite membrane which can be manufactured at low cost while suppressing the occurrence of floating and tearing of the gas separation layer and has excellent gas permeability.</p>

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts are designated by the same reference numerals, and duplicate description will be omitted.

(Gas Separation Composite Membrane) FIG. 1 is a cross-sectional view schematically showing a gas separation composite membrane according to an embodiment of the present invention. The gas separation composite membrane 100 shown in FIG. 1 includes a sheet-shaped support 10 and a gas separation layer 20 provided on the support 10.

The support 10 is made of a porous body containing an unstretched ethylene polymer. Since the ethylene polymer is a hydrophobic polymer, it is suitable for adopting a water surface development method or the like as a method for forming the gas separation layer 20. It also has the advantage of being inexpensive as compared with other hydrophobic polymers such as fluororesin and polyimide resin.

The ethylene-based polymer is a polymer mainly composed of a polyethylene skeleton, and is, for example, polyethylene, polypropylene, an ethylene-acrylic acid copolymer, an ethylene-α olefin copolymer, an ethylene-unsaturated ester copolymer, or an ethylene-non-polymer. Saturated carboxylic acid copolymer and the like can be mentioned.

Among these, polyethylene is preferable because it has a high crystallinity, is inexpensive, and is suitable for obtaining a porous body by a method (extraction method) described later. Further, polyethylene preferably has a crystallinity of 90% or more, more preferably 95% or more. A high crystallinity is advantageous in that it is difficult to take in the liquid agent used in the extraction method, heat resistance, and the like.

As polyethylene, high-density polyethylene (density: 0.95 to 0.98 g / cm)³) Is preferable in that there are few short chain branches and the crystallinity is high. Furthermore, among high-density polyethylenes, so-called ultra-high molecular weight polyethylenes with a molecular weight of 1 million or more flow and deform even at high mechanical properties such as breaking strength and at the melting point of 135 ° C or higher. It is more preferable because it does not occur and has excellent heat resistance.

The unstretched ethylene-based polymer is an ethylene-based polymer that has not been subjected to a stretching operation in the process of its production, and the support made of a porous body containing the unstretched ethylene-based polymer has moisture content. Excellent dimensional stability in the process of adsorption and dehydration. Usually, an ethylene polymer produced by a stretching method is produced by being stretched at a stretching ratio of about 2 times or more for the purpose of improving its mechanical strength, but in the present invention, such stretching is not performed. Use an ethylene polymer.

Generally, in a material made of a crystalline polymer such as an ethylene-based polymer, crystals called lamella crystals are generated when the material is cooled from the molten state. When the material is stretched, the lamellar crystals tend to disappear as the molecular chains are oriented along the stretching direction. Therefore, the fact that the ethylene polymer is unstretched means that it is unstretched. It may be confirmed from the fact that most of the lamella crystals remain.

The porous body as the support 10 is preferably composed of only an unstretched ethylene-based polymer, but may further contain other components such as a plasticizer, if necessary.

The porous body used as the support 10 is preferably immersed in water at 20 ° C. for 10 seconds and then left at 23 ± 2 ° C. for 1 hour, preferably having a shrinkage rate of 0 to 10%. More preferably, it is 1%. Here, the shrinkage ratio is such that when a sheet-like porous body having a length of 50 to 150 mm, a width of 50 to 150 mm, and a thickness of 0.05 to 1.00 mm is treated under the above conditions, the vertical or horizontal shrinkage before and after the treatment. A value defined as the rate of change in length (after / before processing). In the case of a porous body obtained by a method described later using an unstretched ethylene polymer, the shrinkage rate is usually within the above range.

Further, it is preferable that the support 10 is made of a porous body in which open pores with cohesive fine particles adhered to the pore walls are formed, from the viewpoint of particularly excellent dimensional stability.

The shape of the support 10 is a sheet shape in the gas separation composite membrane 100, but as a modification thereof, it may be a tube shape, a granular shape, a bulk shape, or the like. However, in consideration of the convenience of permeating and separating air, it is preferably in the form of a sheet. When the support 10 is in the form of a sheet, its thickness is preferably 20 to 300 μm, more preferably 50 to 100 μm. If the thickness of the support 10 is less than 20 μm, the mechanical strength tends to decrease and the handleability tends to deteriorate, and if it exceeds 300 μm, the resistance tends to increase when air permeates.

In the porous body used for the support 10, it is preferable that open pores communicating with the outside air are formed, and the average pore diameter thereof is preferably 3 times or less with respect to the thickness of the gas separation layer 20. .. If the average pore size is larger than this, the gas separation layer 20 tends to be easily torn when the gas separation composite membrane 100 is used. In the present invention, the thickness of the gas separation layer 20 is preferably 10 to 1000 nm, but the average pore size of the porous body to be combined with this is preferably 30 to 3000 nm, more preferably 30 to 100 nm. preferable.

If the porosity of the porous body is less than 30% by volume, the resistance tends to increase when air permeates, and if it exceeds 80% by volume, the mechanical strength tends to decrease and the handleability tends to deteriorate. Therefore, it is preferably 30 to 80% by volume, more preferably 40 to 60% by volume.

The support 10 made of the porous body as described above can be suitably obtained by, for example, an extraction method using cohesive fine particles, as will be described later.

The gas separation layer 20 is a high phase separated into a phase in a rubber state or a molten state (hereinafter referred to as soft phase) and a phase in a glass state or a crystalline state (hereinafter referred to as hard phase). It is composed of a thin film of a polymer (polygonide siloxane) containing a molecule or an organopolysiloxane skeleton represented by the general formula (1) and an imide skeleton represented by the general formula (2). In the soft phase, a rubber state region and a molten state region may be mixed, and in the hard phase, a glass state region and a crystalline state region may be mixed.

In the above-mentioned polymer that is phase-separated into a soft phase and a hard phase, a microphase-separated structure composed of these two phases is usually formed. The soft phase is a phase that exhibits a glass transition phenomenon in a region lower than normal temperature and is in a rubber state or a molten state at normal temperature. On the other hand, the hard phase is a phase in which the glass does not undergo a glass transition below room temperature, but the glass transitions or melts at a higher temperature above room temperature. It is preferable that at least a part of the component constituting the soft phase and the component constituting the hard phase are covalently bonded from the viewpoint of heat resistance and the like. As such a polymer, for example, a copolymer containing a skeleton (soft segment) mainly forming a soft phase and a skeleton (hard segment) mainly forming a hard phase is suitable.

The fact that the polymer is phase-separated into such a soft phase and a hard phase means that, for example, when dynamic viscoelasticity measurement is performed, the glass transition point (first transition point) below room temperature and the high temperature It can be confirmed by observing the glass transition point or the melting point (second transition point) of.

This first transition point is usually 20 ° C or lower, more preferably -20 ° C or lower. On the other hand, the second transition point is usually 100 ° C or higher, more preferably 130 ° C or higher. These transition points are values measured by dynamic viscoelasticity measurement with a measurement frequency of 1 Hz and a heating rate of 10 ° C / min.

One of the effects of suppressing the occurrence of the phenomenon (floating) that a part of the gas separation layer 20 is peeled off from the support 10 and floats is that the above-mentioned polymer thin film has a property of being easily stretched. It is thought that it is due to the fact that it is doing.

When the gas separation layer 20 is formed on the support 10, the air trapped between the ethylene polymer 11 constituting the support and the gas separation layer 20 causes, for example, voids as shown in FIG. 30 may be formed, and the gas separation layer 20 in that portion may be in a floating state. Even in such a state, if the gas separation layer 20 has a property of being easily stretched, the gas separation layer 20 in the vicinity of the void 30 is deformed over time so as to follow the unevenness of the surface of the ethylene polymer 11. Then, it is considered that the void 30 disappears within a few tens of seconds to a few minutes, and as a result, the floating does not occur.

In order to further enhance the effect of suppressing floating, the polymer constituting the thin film as the gas separation layer 20 preferably has an elongation of 80% or more, more preferably 500% or more. However, this elongation shall be a value obtained by conducting a tensile test on a test piece made of a polymer constituting a thin film by a method specified in JIS K7311. As a result of the studies by the present inventors, it is clear that using this parameter as an index is effective as an index of the adhesion between the support 10 composed of the ethylene polymer 11 and the gas separation layer 20. became.

When the elongation is less than 80%, the state in which the void 30 is formed tends to be maintained for a long period of time as shown in FIG. In this case, even when a slight external force is applied to the gas separation composite membrane 100, the gas separation layer in the portion forming the void 30 may be torn. On the other hand, in the case of a polymer having an elongation of more than 500%, even if the void 30 is formed, it disappears in an extremely short time.

Further, in the case of a thin film having an elongation of 80% or more, when compressed air is blown to the portion where the void 30 is formed, the air in the void 30 escapes through the open pore of the support 10 until the void 30 disappears. You can also save time. This method can be performed with almost no problem in the case of a thin film having an elongation of 80% or more, but if this method is adopted when the elongation of the thin film is less than 80%, the thin film tends to be easily torn by air pressure. ..

The thickness of the gas separation layer 20 is preferably 10 to 1000 nm, more preferably 50 to 200 nm. If the thickness exceeds 1000 nm, the gas permeability tends to be insufficient, and if it is less than 10 nm, the handleability tends to decrease. The thickness of the gas separation layer 20 is, for example, a step between a place where a part of the gas separation layer 20 is removed from the support 10 and a place where the gas separation layer 20 remains and a place where the gas separation layer 20 is removed, such as AFM. It can be quantified by measuring with.

In the above polymer, examples of the skeleton (soft segment) mainly constituting the soft phase include a skeleton composed of an ethylene-butylene copolymer, an ethylene-styrene copolymer, an acrylic acid ester polymer, an organopolysiloxane, and the like. Be done. Among these, the organopolysiloxane skeleton is preferable from the viewpoint of gas permeability.

Examples of the skeleton (hard segment) mainly constituting the hard phase include a crystalline polymer such as polyethylene, and an amorphous rigid skeleton such as polyimide and polycarbonate. Among these, polyimide is preferable from the viewpoint of heat resistance and the like.

In polyimidesiloxane, a microphase-separated structure is usually formed, which is mainly composed of a soft phase mainly composed of an organopolysiloxane skeleton and a hard phase mainly composed of an imide skeleton. The gas separation layer 20 is particularly preferably made of a thin film containing this polyimidesiloxane from the viewpoints of gas permeability, oxygen enrichment, heat resistance, mechanical strength and the like.

As the polyimidesiloxane, those already containing the organopolysiloxane skeleton represented by the following general formula (1) and the imide skeleton represented by the following general formula (2) are preferable. The organopolysiloxane skeleton and the imide skeleton may be bonded to each other in a block shape, or may be bonded to each other at random.

<chemistry num="3"><img file="JP2005296821A_D0003.tif" /></chemistry>

<chemistry num="4"><img file="JP2005296821A_D0004.tif" /></chemistry>

In the above-mentioned polyimidesiloxane, the content of the organopolysiloxane skeleton, which is a soft segment, is preferably 35% by mass or more, more preferably 35 to 97% by mass, and 40 to 40% by mass, based on the entire polyimidesiloxane. It is more preferably 97% by mass. When the content of the organopolysiloxane is large, the mechanical properties of the polyimidesiloxane tend to be elastomeric, and become rich in flexibility and elasticity. When this content is 35% by mass or more, the gas separation layer 20 becomes particularly easy to stretch, and the adhesion to the support 10 becomes better than when it is less than 35% by mass. Further, when this content exceeds 97% by mass, the heat resistance and the mechanical strength tend to decrease.

This polyimidesiloxane contains, for example, a repeating unit consisting of a skeleton represented by the following general formula (3) (including an organopolysiloxane skeleton represented by the above general formula (1)) and the above general formula (2). It may have a repeating unit composed of an imide skeleton represented by.

<chemistry num="5"><img file="JP2005296821A_D0005.tif" /></chemistry>

Further, the polyimidesiloxane may have a repeating unit represented by the following general formula (4). Note that n in Eq. (4) indicates a positive integer.

<chemistry num="6"><img file="JP2005296821A_D0006.tif" /></chemistry>

R in the above general formulas (1) to (4)¹, R², R³And R⁴Independently indicate a monovalent aliphatic group or a monovalent aromatic group, which may be substituted with a fluorine atom. Examples of the monovalent aliphatic group include a monovalent saturated hydrocarbon group and a monovalent unsaturated hydrocarbon group. Examples of the monovalent saturated hydrocarbon group include an alkyl group having 1 to 22 carbon atoms, and examples thereof include a methyl group, an ethyl group, and a propyl group. Examples of the monovalent unsaturated hydrocarbon group include an alkenyl group having 2 to 22 carbon atoms, and examples thereof include a vinyl group and a propenyl group. Examples of the monovalent aromatic group include an aryl group having 6 to 24 carbon atoms and an aralkyl group. R¹, R², R³And R⁴In particular, a methyl group or a phenyl group is preferable. Further, r indicates a positive integer, and is preferably an integer of 10 to 10,000.

Further, X in the above general formulas (1) to (4) indicates a tetravalent aromatic group, and the following general formulas (5a) to (5k), (5m), (5n), (5p) and (5q) ) Are preferably tetravalent aromatic groups.

<chemistry num="7"><img file="JP2005296821A_D0007.tif" /></chemistry>

<chemistry num="8"><img file="JP2005296821A_D0008.tif" /></chemistry>

<chemistry num="9"><img file="JP2005296821A_D0009.tif" /></chemistry>

<chemistry num="10"><img file="JP2005296821A_D0010.tif" /></chemistry>

<chemistry num="11"><img file="JP2005296821A_D0011.tif" /></chemistry>

<chemistry num="12"><img file="JP2005296821A_D0012.tif" /></chemistry>

<chemistry num="13"><img file="JP2005296821A_D0013.tif" /></chemistry>

<chemistry num="14"><img file="JP2005296821A_D0014.tif" /></chemistry>

In the above equations (5a) to (5k), (5m), (5n), (5p) and (5q), R⁵And R⁶Independently indicate a hydrogen atom, a methyl group, a trifluoromethyl group or a phenyl group, respectively.⁷And R⁸Independently indicate a hydrogen atom, a trifluoromethyl group or a phenyl group. s represents a positive integer, preferably an integer from 1 to 20. Also, R⁹And R¹⁰Independently represent a trifluoromethyl group or a phenyl group, and A represents an ethylene group or a divalent aromatic group represented by the following general formulas (6a) to (6c).

<chemistry num="15"><img file="JP2005296821A_D0015.tif" /></chemistry>

Further, in the above general formulas (1) to (4), Z¹And Z²Independently indicate a divalent aliphatic group or a divalent aromatic group, and these groups may be substituted with a fluorine atom. Examples of the divalent aliphatic group include a divalent saturated hydrocarbon group and a divalent unsaturated hydrocarbon group. Examples of the divalent saturated hydrocarbon group include an alkylene group having 1 to 22 carbon atoms, and examples thereof include a methylene group, an ethylene group, and a propylene group. Examples of the divalent unsaturated hydrocarbon group include an unsaturated carbon hydrogen group having 2 to 22 carbon atoms, and examples thereof include a vinylene group, a propenylene group, and an alkylene group having an unsaturated double bond at the terminal. Examples of the divalent aromatic group include a phenylene group having 6 to 24 carbon atoms, a phenylene group substituted with an alkyl group, and an aralkylene group. Z¹And Z²In particular, a propylene group, a phenylene group, and an aralkylene group are preferable.

Further, Y in the above general formulas (1) to (4) indicates a divalent aliphatic group or a divalent aromatic group, and is represented by the following general formula (7) or the following general formula (8) 2 It is preferably a valent aromatic group. In equation (8), t represents a positive integer, preferably an integer from 1 to 22.

<chemistry num="16"><img file="JP2005296821A_D0016.tif" /></chemistry>

<chemistry num="17"><img file="JP2005296821A_D0017.tif" /></chemistry>

The polyimidesiloxane used for the gas separation layer 20 preferably has a standard polystyrene-equivalent weight average molecular weight (Mw) of 1,000 to 100,000, more preferably 5,000 to 50,000, by gel permeation chromatography (GPC).

The polyimidesiloxane having the repeating unit represented by the general formula (1) and the repeating unit represented by the general formula (2) is an organopoly having an amino group at the terminal represented by the following general formula (9). Obtained by subjecting a diamine mixture consisting of siloxane (hereinafter referred to as "siloxane diamine") and a siloxane-free diamine represented by the following general formula (10) to a dehydration condensation reaction with a polybasic acid dianhydride. Can be done. This dehydration condensation reaction can be carried out by adopting a conventionally known method. The reference numerals in the chemical formulas in the following description indicate the same structure as the contents in the above chemical formulas.

<chemistry num="18"><img file="JP2005296821A_D0018.tif" /></chemistry>

<chemistry num="19"><img file="JP2005296821A_D0019.tif" /></chemistry>

As the diacid anhydride of the polybasic acid, the tetracarboxylic dianhydride represented by the following general formula (11) is preferably used.

<chemistry num="20"><img file="JP2005296821A_D0020.tif" /></chemistry>

Commercially available siloxane diamines represented by the above general formula (9) include X-22-9409, X-22-1660B, X-22-161AS, X-22-161A, and X-22-. 161B (above, manufactured by Shin-Etsu Chemical Co., Ltd.) and the like. These can be used alone or in combination of two or more.

As the diamine represented by the above general formula (10), an aromatic diamine is preferably used. Examples of the aromatic diamine include compounds represented by the following formula (12) or the following general formula (13).

<chemistry num="21"><img file="JP2005296821A_D0021.tif" /></chemistry>

<chemistry num="22"><img file="JP2005296821A_D0022.tif" /></chemistry>

The aromatic diamine represented by the above general formula (13) is 4,4. ́-Diaminophenoxymethane, 1,2-bis (4-aminophenoxy) ethane, 1,3-bis (4-aminophenoxy) propane, 1,4-bis (4-aminophenoxy) butane, 1,5-bis (4-Aminophenoxy) Pentane, 1,6-bis (4-Aminophenoxy) Hexane, 1,7-Bis (4-Aminophenoxy) Heptadecane, 1,8-Bis (4-Aminophenoxy) Octadecane, 1,9 -Bis (4-aminophenoxy) nonadecane, 1,10-bis (4-aminophenoxy) decane, 1,11-bis (4-aminophenoxy) undecane, 1,12-bis (4-aminophenoxy) dodecane, 1 , 13-bis (4-aminophenoxy) tridecane, 1,14-bis (4-aminophenoxy) tetradecane, 1,15-bis (4-aminophenoxy) pentadecane, 1,16-bis (4-aminophenoxy) hexadecane , 1,17-bis (4-aminophenoxy) heptadecane, 1,18-bis (4-aminophenoxy) octadecane, 1,19-bis (4-aminophenoxy) nonadecane, 1,20-bis (4-aminophenoxy) ) Ikosan etc. can be mentioned. These can be used alone or in combination of two or more.

Examples of the tetracarboxylic dianhydride represented by the above general formula (11) include pyromellitic dianhydride, methylpyromellitic dianhydride, trifluoromethylpyrimellitic dianhydride, and phenylpyro. Merit acid dianhydride, diphenylpyromeric acid dianhydride, 3,3 ́,4,4 ́-biphenyltetracarboxylic dianhydride, 2,2 ́-diphenyl-3,3 ́,4,4 ́-biphenyl Tetetracarboxylic dianhydride, 2,2 ́-ditrifluoromethyl-3,3 ́,4,4 ́-biphenyltetracarboxylic dianhydride, 2,2 ́,3,3 ́-biphenyltetracarboxylic dianhydride , 3,3 ́,4,4 ́-benzophenonetetracarboxylic dianhydride, 2,2 ́,3,3 ́-benzophenonetetracarboxylic dianhydride, 3,3 ́,4,4 ́-diphenylsulphon Tetetracarboxylic dianhydride, 3,3 ́,4,4 ́-diphenylhexafluoroisopropyridenetetracarboxylic dianhydride, 1,1 ́-bis (3,4-dicarboxyphenyl) -1-phenyl-2 , 2,2-Trifluoroethanedianhydride, 3,3 ́,4,4 ́-Diphenylisopropyridenetetracarboxylic dianhydride, 3,3 ́,4,4 ́-diphenylmethanetetracarboxylic dianhydride, 3,3 ́,4,4 ́-benzosulfidetetracarboxylic dianhydride, 2 , 2 ́,3,3 ́-benzosulfide tetracarboxylic dianhydride, 3,3 ́,4,4 ́-diphenylamine tetracarboxylic dianhydride, 3,3 ́,4,4 ́-diphenylamide tetracarboxylic Acid dianhydride, 2,2-bis (3,4-dicarboxyphenoxy) diphenylpropane dianhydride, bis (3,4-dicarboxyphenoxy) benzene dianhydride, bis (3,4-dicarboxyphenoxy) Etan dianhydride, bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride, 4,4 ́-bis (3,4-dicarboxyphenoxy) diphenylsulfide dianhydride, 4,4 ́-oxydiphthalic acid Examples thereof include dianhydride and bis (3,4-dicarboxyphenyl) phosphinoxide dianhydride. These can be used alone or in combination of two or more.

The polyimidesiloxane having the repeating unit represented by the general formula (4) can be obtained by reacting a polyimide having an acid anhydride group at the terminal with a siloxane diamine represented by the general formula (9).

The thin film as the gas separation layer 20 is preferably composed of only a polymer such as polyimidesiloxane as described above, but further contains other components such as a plasticizer and inorganic particles, if necessary. But it may be.

(Manufacturing Method of Gas Separation Composite Membrane) Regarding a suitable manufacturing method for obtaining the gas separation composite membrane 100 as described above, a method for manufacturing a porous body used as the support 10, a gas separation layer on the support 10. The method of forming 20 will be described in detail below.

The porous body used as the support 10 can be preferably obtained by a method of removing the liquid agent from a mixture of the cohesive fine particles, the liquid agent, and the unstretched ethylene polymer. By using the cohesive fine particles, it is possible to reduce the volume change of the entire porous body when the liquid agent is removed, and the dimensional stability of the obtained porous body becomes particularly excellent.

In this method, first, a mixture of cohesive fine particles, a liquid agent, and an unstretched ethylene polymer is obtained. At this time, an adhering material as shown in FIG. 4 in which the liquid agent is adhered to the cohesive fine particles may be separately prepared, and the adhering material and the ethylene polymer may be mixed, or the cohesive fine particles, the liquid agent and ethylene may be mixed. The polymer may be mixed by being put into a kneader at the same time.

In mixing, in order to uniformly disperse the cohesive fine particles 1 and the liquid agent 2, it is preferable to knead the cohesive fine particles 1 and the liquid agent 2 at a temperature higher than the melting point of the ethylene polymer by a kneading device such as an extruder or a kneader. Normally, the agglomeration state of particles changes at any time depending on the history of kneading, but kneading can be performed with good reproducibility by controlling the product of torque output and kneading time and the resin temperature in kneading.

In addition, the porosity of the obtained porous body can be controlled by the amount of the liquid agent contained in the mixture. In order to keep the porosity of the obtained porous body in a preferable range, the amount of the liquid agent is preferably 30 to 80% by volume, more preferably 40 to 60% by volume, based on the entire mixture.

The kneaded mixture is once processed into pellets, veils, belts, etc., and then molded into sheets by an extruder, calendar, roll, belt, etc. to obtain a precursor of a porous material. Is preferable. When an extruder is used, kneading and molding can be performed at once. The apparatus or the like used for kneading may be other than the above.

FIG. 5 is a cross-sectional view schematically showing a sheet-shaped precursor 10a made of the above mixture after undergoing kneading and molding. In the precursor 10a, the region formed by incorporating the liquid agent 2 into the agglomerates of the cohesive fine particles 1 is dispersed in the ethylene polymer 11. At the stage where the ethylene polymer is melted during kneading, the liquid agent 2 is also incorporated into the ethylene polymer, but after molding, the mixture is cooled and the ethylene polymer crystals (lamella crystals) grow. As a result, the liquid agent 2 is discharged from the ethylene-based polymer and is taken into the agglomerates of the cohesive fine particles 1 again, resulting in a state as shown in the precursor 10a shown in FIG.

FIG. 4 is a cross-sectional view schematically showing the adhered body used at the time of mixing. In the adherent 5 shown in FIG. 4, the liquid agent 2 is adhered so as to soak into the gaps between the aggregates of the primary particles of the cohesive fine particles 1 (hereinafter referred to as aggregates). Since the cohesive fine particles 1 form aggregates, the adherent 5 as shown in FIG. 2 can be easily obtained by adhering the liquid agent 2. The adhering body 5 is obtained, for example, by kneading a mixture of the cohesive fine particles 1 and the liquid agent 2 with a pressure kneader or the like.

Examples of the cohesive fine particles 1 include Ketjen black, silica, synthetic wet calcium carbonate, and acrylic crosslinked particles. However, the cohesive fine particles 1 have high cohesiveness and have a property of easily holding a liquid agent even in a mixture with an ethylene polymer. Therefore, silica is preferable. This silica refers to silicon oxide (silicic acid), and includes those obtained by pulverizing natural anhydrous silicic acid such as quartz, and synthetic silica such as wet silica and fumigant silica. Among these, the cohesive fine particles 1 are preferably synthetic silica in terms of cohesiveness.

It is generally known that the cohesive force of cohesive fine particles can be quantified by the absorption amount of the oil or the like. For example, in ASTM D2414-93, the fine particles are determined by the absorption amount (DBP oil absorption amount) of DBP (dibutyl phthalate). A method for quantifying the cohesiveness of phthalate is specified. For the cohesive fine particles 1, the above DBP oil absorption is 50 [cm].³It is preferably 200 ~ 400 [cm] or more.³/ 100g] is more preferable. DBP oil absorption is 50 [cm³If it is less than / 100g], the holding power of the liquid agent tends to be insufficient.

The primary particle size of the cohesive fine particles 1 is preferably 1.0 μm or less, and more preferably 0.05 μm or less. When the primary particle size exceeds 1.0 μm, the cohesive force tends to decrease. When the agglomerates composed of the cohesive fine particles 1 are regarded as particles, the particle size thereof is preferably 100 μm or less, and more preferably 10 μm or less. When this particle size exceeds 100 μm, the pore diameter of the pores formed in the obtained porous body becomes large, and the gas separation layer 20 tends to be easily broken.

The content of the cohesive fine particles 1 in the adhering body 5 may be appropriately determined according to the type thereof. For example, the DBP oil absorption amount of the cohesive fine particles 1 is 200 to 400 [cm].³In the case of [/ 100 g], the weight ratio to the liquid agent 2 is preferably 1/5 to 1/2.

As the liquid agent 2, it is preferable to use a liquid that can efficiently absorb the aggregates of the cohesive fine particles 1. Specifically, paraffinic oil, phthalate ester and the like are suitable.

The paraffinic oil preferably has a molecular weight of 500 or less, and more preferably 10 to 100, in order to increase the efficiency of removal from the precursor 10a. The viscosity is preferably 1000 mPa · s or less, and more preferably 10 to 100 mPa · s.

Phthalate esters are diesters of phthalates and alcohols, such as dioctyl phthalate (DOP) and diisononyl phthalate (DINP). The alcohol preferably has 3 to 12 carbon atoms, and more preferably 7 to 10 carbon atoms. When the number of carbon atoms is 3 or less, the boiling point is low and it tends to be lost due to volatilization during mixing or molding. When the number of carbon atoms exceeds 18, the fluidity is lost at room temperature and the particles adhere to the cohesive fine particles 1. Tends to be difficult.

Next, pores are formed by removing the liquid agent 2 from the precursor 10a, and a sheet-like support 10 made of a porous body as shown in FIG. 6 is obtained. FIG. 6 is a cross-sectional view schematically showing the support 10 in which the open pores to which the cohesive fine particles 1 are attached are formed on the pore wall.

The liquid agent 2 can be preferably removed by extracting the liquid agent 2 with an extraction solvent. Extraction is performed, for example, by immersing the precursor 10a in an extraction solvent such as toluene, hexane, xylene, various alcohols, rubber volatile oil, hot water, and boiling water. The conditions for extraction may be appropriately determined according to the extraction solvent to be used and the like. After the immersion, the extraction solvent adhering to the porous body is removed (dried) to obtain the support 10. This drying may be natural drying or forced drying by heating or blowing air.

By laminating the gas separation layer 20 on the support 10 obtained as described above, the gas separation composite film 100 can be obtained. As a method for forming the thin film of the gas separation layer 20, the water surface development method in which the polymer is developed on the water surface is preferable.

In this water surface development method, a polymer solution in which a polymer is dissolved in a solvent is dropped on the water surface, and the polymer is developed as a solution on the water surface to form a thin film. The dropped polymer solution immediately develops on the water surface due to surface tension, and the solvent evaporates almost at the same time as the development to form a polymer thin film. Subsequently, when the formed thin film is scooped up by the submerged support 10 and brought into contact with the surface thereof, the thin film adheres to the support 10 and both are integrated. Further, the gas separation composite film 100 can be obtained by removing the water adhering to the support 10 and the thin film (gas separation layer 20).

The solvent used for the polymer solution is preferably selected from those having good solubility of the polymer constituting the gas separation layer 20. For example, when the polymer is polyimidesiloxane, organic solvents such as toluene, methyl ethyl ketone, and N-methylpyrrolidone are preferable. The polymer concentration of this solution is preferably 5 to 30% by mass with respect to the entire polymer solution.

A dispenser, a syringe, a dropper, or the like can be preferably used to drop the polymer solution onto the water surface. Alternatively, the polymer solution supply device may be installed in water and floated on the water surface by the buoyancy of the solution to be deployed.

When the support 10 is a long sheet, the support 10 is sent out by a feeding device, once passed through water, and while scooping the thin film formed on the water surface, the support 10 is sequentially wound by the winding device. A continuous process can also be adopted. When adopting such a continuous process, it is preferable to adjust the supply amount of the solution according to the feed rate of the support. Further, the thickness of the gas separation layer 20 can be adjusted by repeating the lamination of the thin film on the support 10 a plurality of times.

The contents of the present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.

(Example 1) &lt;Preparation of porous body A&gt; 100 parts by weight of paraffin oil (Lucant 360, trade name, manufactured by Mitsui Kagaku Co., Ltd.) and primary particles with an average particle size of 16 nm are aggregated to form an average particle size of 9 μm. Wet silica particles (Nipseal LP, trade name, manufactured by Nippon Silica Industry Co., Ltd.) mixed with 50 parts by weight are kneaded with a pressure kneader at room temperature to form an agglomerate of silica particles which are cohesive fine particles. , An adhering material to which paraffin oil, which is a liquid agent, was attached was obtained. Next, using two rolls whose temperature was adjusted to about 160 ° C, high-density ultra-high molecular weight polyethylene with a molecular weight of about 3 million (HIZEX Million 220, trade name, molecular weight of about 3 million, Mitsui Chemicals Co., Ltd.) (Manufactured) 100 parts by weight and 300 parts by weight of the adhered material obtained above were mixed and kneaded to obtain a sheet-like precursor having a white mixture and a thickness of about 0.2 mm. In this precursor, these are mixed in a ratio of 100 parts by weight of ultra-high molecular weight polyethylene, 200 parts by weight of paraffin oil, and 100 parts by weight of silica particles, and about 44.5% by volume of paraffin oil is added to the total volume of the precursor. Was occupied.

Next, a pair of mirror-finished stainless steel plates sandwich the above precursor cut to 15 x 15 cm, and this is 100 kgf / cm with a pair of press machines whose temperature is adjusted to 180 ° C.²Pressed at the pressure of 3 minutes. Then, while maintaining the pressurized state, the temperature of the press machine was cooled to 60 ° C. by flowing cooling water through the press machine for 5 minutes, and then the precursor was taken out. Further, this precursor was immersed in toluene in a vat at room temperature for 3 hours, taken out, left at room temperature for a whole day and night, and further blown with warm air with a dryer to obtain a white opaque porous body A. .. When this porous body A was cut into 100 × 100 mm and its thickness and weight were measured, the thickness was 195 μm and the weight was 1.0271 g. Therefore, the porosity φ of this porous body A was calculated to be 41% from the following equation (1). However, the true specific gravity of the porous body A is 1.285 g / cm.³Met. φ = {M / (C V)} 100 (1) (In the formula, M is the mass of the support [g] and C is the true specific gravity of the support [g / cm.³], V is the volume of the support [cm³] Are shown respectively. )

When the surfaces of the front and back surfaces of the porous body A were observed with an electron microscope, it was confirmed that innumerable pores having a diameter of 30 to 60 nm were formed on each surface. Further, when the sheet-shaped porous body A whose size was measured in advance was immersed in water at 20 ° C. for 10 seconds and left at 23 ° C. for 1 hour, the shrinkage rate was 0.5%. From this, it was found that the porous body A obtained by the extraction method using silica particles as described above has a small shrinkage in the process of water absorption and dehydration, and is suitable for laminating thin films by the water surface development method.

(Comparative Example 1) &lt;Preparation of Porous Body B&gt; High-density polyethylene with a molecular weight of about 100,000 using a pressurized kneader whose temperature is adjusted to about 160 ° C (HIZEX 5500S, trade name, Mitsui Chemicals, Inc.) A mixture of 100 parts by weight of wet silica particles (Nipseal LP, trade name, manufactured by Nippon Silica Industry Co., Ltd.) and 20 parts by weight was kneaded to obtain the mixture. The obtained mixture was crushed with two rolls whose temperature was adjusted to 150 ° C. to obtain a white sheet-like precursor having a thickness of about 0.2 mm.

The precursor was heated by being held in a heat drum whose temperature was adjusted to 120 ° C., and then stretched 2.15 times and 1.85 times in the elongated direction and the vertical direction thereof, respectively, with a stretching roll. After stretching, the silica that had fallen off was dispelled to obtain a white opaque porous body B. When the porous body B was cut into 100 × 100 mm and its thickness and weight were measured, the thickness was 103 μm and the weight was 0.303 g. Therefore, from the above equation (1), it was calculated that the porosity φ of the porous body B was 28%. However, the true specific gravity of the porous body B is 1.050 g / cm.³Met. When the front and back surfaces of the porous body B were observed with an electron microscope, it was confirmed that innumerable pores having a diameter of 10 to 50 nm were formed. The shrinkage rate of the porous body B measured in the same manner as in Example 1 was 48%.

(Example 2) &lt;Preparation of gas separation composite membrane&gt; It has a structure represented by the following general formula (14) (in the formula, p and q each independently indicate a positive integer), and 50% by mass. A tensile test was performed on a polyimide siloxane containing an organopolysiloxane skeleton (SMP4001 manufactured by Shin-Etsu Chemical Industry Co., Ltd.) formed into a sheet having a thickness of 2 mm, and the breaking strength and elongation of the sheet were measured. The intensity was 9.87 MPa and the elongation was 578%. The tensile test was carried out using a tensile tester (Tencilon, manufactured by Toyo Seiki Co., Ltd.) with a No. 2 dumbbell piece according to the test method of JIS K7311.

<chemistry num="23"><img file="JP2005296821A_D0023.tif" /></chemistry>

This polyimidesiloxane was dissolved in a mixed solvent of toluene and N-methylpidridone to prepare a polymer solution having a solid content of 10% by mass. When 0.01 mL of this polymer solution was dropped on the water surface in a 30 x 30 x 20 cm bat containing 5 L of water with a burette, a thin film of polymer developed into a clean concentric circle with a diameter of about 20 cm. Was done. The thickness of the developed thin film is calculated to be about 30 nm. A few seconds after unfolding, the porous body A obtained in Example 1 was cut out into a sheet having a size of 15 × 15 cm, and the obtained support was dropped into water and gently scooped up the thin film. I pulled it up. Immediately after pulling up, there was a floating part that slightly held an air layer at the end of the support, and this part gave off a rainbow-colored glow, but after a few seconds, this floating part disappeared and the entire surface became full. It turned white. Then, it was left at room temperature to remove water adhering to the support and the thin film (gas separation layer) to obtain a gas separation composite film.

When the obtained gas separation composite membrane was floated on the water surface with the gas separation layer facing down, it was not confirmed that water had infiltrated into the support, so that the gas separation layer had no defects such as tearing. confirmed. Further, when the compressed air was wiped on the gas separation layer at the time of removing the water, the gas separation layer did not appear to be peeled off from the support. When the gas separation composite membrane was cut into a circle with a diameter of 60 mm and a gas permeation test (23 ± 2 ° C, 1 atm decompression) was performed, the oxygen permeability coefficient was 9.11 × 10.^-8[cm³(STP) cm / cm² Second cmHg], nitrogen permeability coefficient is 4.25 × 10^-8[cm³(STP) cm / cm²-Sec · cmHg], which was excellent in gas permeability. In addition, the separation coefficient PO of oxygen and nitrogen₂/ PN₂Was 2.14 [-], which was also excellent in oxygen enrichment performance.

(Example 3) &lt;Preparation of gas separation composite membrane&gt; Polyimide siloxane having a structure represented by the above general formula (14) and having an organopolysiloxane skeleton content of 40% by mass (Shinetsu Chemical Industry Co., Ltd.) When a tensile test was conducted on SMP5010) manufactured by the same company in the same manner as in Example 2, the breaking strength was 15.43 MPa and the elongation was 88%. A gas separation composite membrane was prepared in the same manner as in Example 2 except that the polyimidesiloxane was replaced with SMP5010. When the support was pulled up from the water surface, a part where the gas separation layer was turned up and not supported on the support was observed at the end of the support. When this was left at room temperature, the part that was not turned up gradually turned white, and after 45 minutes, almost the entire part except the part that was turned up and its surroundings became white, and gas separation was performed. The layer adhered to the support.

When the obtained gas separation composite membrane was floated on the water surface in the same manner as in Example 2, it was not confirmed that water had infiltrated into the support, so that the gas separation layer had no defects such as tearing. confirmed. In addition, when compressed air was wiped on the gas separation layer when removing water, a part of the gas separation layer was torn off and blew off, but most of the gas separation layer did not appear to be peeled off from the support. .. When a gas permeation test was conducted on this gas separation composite membrane in the same manner as in Example 2, the oxygen permeation coefficient was 8.67 × 10.^-10[cm³(STP) cm / cm² Second cmHg], nitrogen permeability coefficient is 2.03 × 10^-10[cm³(STP) cm / cm²-Sec · cmHg], which was excellent in gas permeability. In addition, the separation coefficient PO of oxygen and nitrogen₂/ PN₂Was 4.27 [-], which was also excellent in oxygen enrichment performance.

(Example 4) &lt;Preparation of gas separation composite membrane&gt; Polyimide siloxane (SMP3001 manufactured by Shin-Etsu Chemical Industry Co., Ltd.) having an organopolysiloxane skeleton content of 30% by mass is tensioned in the same manner as in Example 2. When tested, the breaking strength was 51.21 MPa and the elongation was 76%. A gas separation composite membrane was prepared in the same manner as in Example 2 except that the polyimidesiloxane was replaced with SMP3001. When the gas was pulled up from the surface of the water, the gas separation layer was turned up at the end of the support, and a part not supported on the support was observed. In this gas separation composite membrane, the gas separation layer was almost in close contact with the support as a whole, but after being left at room temperature for 1 hour, the gas separation layer was raised in addition to the part that was turned up. However, a little more was observed as compared with the gas separation composite membrane of Example 3.

(Comparative Example 2) A gas separation composite membrane was prepared in the same manner as in Example 2 except that the porous body A was replaced with the porous body B obtained in Comparative Example 2. However, when the water contained in the support was removed, the whole was severely distorted. When this gas separation composite membrane was floated on the water surface, it was confirmed that water had infiltrated the support over the entire surface in contact with the water surface. Therefore, this gas separation composite membrane could not obtain the function of gas separation.

<figref num="1">FIG. 1 is a cross-sectional view schematically showing a gas separation composite membrane according to an embodiment of the present invention.</figref><figref num="2">FIG. 2 is a cross-sectional view schematically showing a state in which voids are formed in a part of the gas separation composite membrane.</figref><figref num="3">FIG. 3 is a cross-sectional view schematically showing a state after the voids shown in FIG. 2 disappear in a part of the gas separation composite membrane.</figref><figref num="4">FIG. 4 is a cross-sectional view schematically showing an adhering body to which a liquid agent is attached to cohesive fine particles.</figref><figref num="5">FIG. 5 is a cross-sectional view schematically showing a precursor of a porous body.</figref><figref num="6">FIG. 6 is a cross-sectional view schematically showing a support made of a porous body.</figref>

Code description

1 ... cohesive fine particles, 2 ... liquid agent, 5 ... adhering material, 10 ... support, 10a ... precursor, 11 ... ethylene polymer, 20 ... gas separation Layers, 30 ... voids, 100 ... gas separation composite membranes.