JP6038622B2 - Gas separation membrane - Google Patents

Description

  The present invention relates to a gas separation membrane capable of selectively separating a specific gas species from a mixed gas.

  Studies on separation membranes for coal gasification thermal power generation are in progress. In such applications, it is required to selectively separate carbon dioxide from a mixed gas containing water vapor.

  In selectively separating carbon dioxide from a mixed gas containing carbon dioxide, it becomes a problem to improve its selectivity (carbon dioxide selectivity) and recover high-concentration carbon dioxide. In order to obtain a separation membrane with excellent carbon dioxide selectivity, it has been proposed to use a material having high affinity for carbon dioxide. For example, a polyamine support is impregnated with a polyamidoamine dendrimer that is a liquid substance at room temperature. Proposed separation membranes have been proposed (Non-Patent Documents 1 and 2).

  There has been proposed a gas separation membrane in which a hydrophilic polymer material crosslinked with a crosslinking agent is used as a matrix and a layer containing a specific amine compound is formed on the surface of the porous support membrane (Patent Document 1). ).

  In addition, the present inventors previously proposed a gas separation membrane in which a polyamidoamine dendrimer is included in a combination of a vinyl alcohol polymer modified with a specific amount with a carboxyl group and a crosslinking agent having an azetidinium group (Patent Document 2). This gas separation membrane can stably support a polyamidoamine dendrimer even in an environment containing water vapor, and exhibits excellent carbon dioxide selectivity.

JP 2008-68238 A International Publication Number WO2011 / 102326A1

J. et al. Am. Chem. Soc. 122 (2000) 7594-7595 Ind. Eng. Chem. Res. 40 (2001) 2502-2511

  In the separation membranes disclosed in Non-Patent Documents 1 and 2, the carbon dioxide selectivity shown as the carbon dioxide permeation rate relative to the nitrogen permeation rate is an excellent numerical value of 1000 or more under the condition where no mixed gas is pressurized to the separation membrane. Although carbon dioxide membrane permeation rate is low, on the other hand, polyamidoamine dendrimer flows out from the support over time under the condition that the mixed gas is supplied under pressure to the separation membrane, and carbon dioxide selectivity cannot be maintained. .

  The separation membrane disclosed in Patent Document 1 can be said to be a separation membrane that not only has high carbon dioxide selectivity but can withstand a certain pressure difference. However, when water vapor is contained in the mixed gas to be separated, moderate hydrophilicity for developing affinity between the mixed gas and the membrane surface and structural change of the separation membrane occur in a water vapor atmosphere. The contradictory nature of water resistance is required. In the composite membrane, when a mixed gas is supplied in a water vapor atmosphere, the contained amine compound flows out from the composite membrane over time, and carbon dioxide selectivity cannot be maintained. It was difficult to provide.

  The separation membrane disclosed in Patent Document 2 was able to stably carry a polyamidoamine dendrimer even in an environment containing water vapor, and succeeded in expressing excellent carbon dioxide selectivity. However, from the standpoint of providing a separation membrane for practical use, the membrane material is guaranteed to have a hydrophilic property for developing a higher affinity between the water vapor and the membrane material for the mixed gas containing water vapor. It is desirable to further improve the membrane permeation rate of carbon dioxide. In terms of obtaining a membrane permeation rate of carbon dioxide sufficient for practical use, it is desirable to further improve hydrophilicity than the separation membrane. For example, from the viewpoint of imparting hydrophilicity, it is conceivable to further increase the carboxyl group-modified amount of the vinyl alcohol polymer of Patent Document 2. However, if the radical copolymerization is usually more than 5 mol%, the polymerization property is poor, and thus the polymerization is poor. Since the speed was lowered and the degree of polymerization was lowered, it was difficult to obtain a desired vinyl alcohol polymer, and a separation membrane could not be obtained. In view of the above, development of a separation membrane that can efficiently separate carbon dioxide from a mixed gas containing water vapor has been eagerly desired by ensuring that the membrane material has higher hydrophilicity than before.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a gas separation membrane capable of selectively separating carbon dioxide from a mixed gas containing water vapor.

  As a result of intensive studies to solve the above problems, the present inventors have found that a gas composed of an amine compound and a vinyl alcohol polymer modified with a carboxyl group in a larger amount than before. By providing a separation membrane, an improvement in the membrane permeation rate of carbon dioxide was recognized, and the above-described problems were solved, and the present invention was achieved.

  That is, the above problem is that the amine compound (A) is 15 to 85% by mass and the carboxyl group is more than 5 mol% and not more than 30 mol% (the total of the monomer units constituting the vinyl alcohol polymer is 100 mol%). It is solved by providing a gas separation membrane containing 85 to 15% by mass of the vinyl alcohol polymer (B) contained in (the total of the component (A) and the component (B) is 100% by mass). .

In the gas separation membrane, the carboxyl group in the vinyl alcohol polymer (B) is preferably partially or completely neutralized with an alkali metal. More specifically, it is preferable that the neutralization degree with respect to the carboxyl group by an alkali metal is 0.2-1.
Here, the degree of neutralization represents the molar ratio of the neutralized carboxyl group when the carboxyl group reacts stoichiometrically with the alkali metal compound used for neutralization.

  The vinyl alcohol polymer is a block copolymer containing a carboxyl group-containing polymer block and a vinyl alcohol polymer block, or a graft copolymer in which a carboxyl group is grafted to a vinyl alcohol polymer. It is preferable that

［式中、Ａ^１は炭素数１〜３の二価有機残基を示し、ｎは０または１の整数を示す。］
で示される基および／または式（２）

［式中、Ａ^２は炭素数１〜３の二価有機残基を示し、ｎは０または１の整数を示す。］
で示される基を１〜９ｍｅｑ／ｇ含有したポリアミドアミンデンドリマー（Ａ１）であることが好ましい。 The amine compound (A) is represented by the formula (1)

[Wherein, A ¹ represents a C 1-3 divalent organic residue, and n represents an integer of 0 or 1. ]
And / or formula (2)

[Wherein, A ² represents a divalent organic residue having 1 to 3 carbon atoms, and n represents an integer of 0 or 1. ]
It is preferable that it is a polyamidoamine dendrimer (A1) which contained 1-9 meq / g of group shown by these.

  The amine compound (A) preferably includes the polyamide amine dendrimer (A1) and an amine polymer (A2) containing 10 to 35 meq / g of primary amino group.

  It is preferable to use potassium hydroxide or sodium hydroxide as the alkali metal.

  According to the present invention, a gas separation membrane having excellent performance for selectively separating a specific gas species can be provided.

  The gas separation membrane of the present invention comprises 15 to 85% by mass of an amine compound (A) and 85 to 15% by mass of a vinyl alcohol polymer (B) containing more than 5 mol% and not more than 30 mol% of a carboxyl group. It is characterized by being a gas separation membrane containing.

  As described above, in the gas separation membrane of the present invention, each content rate of the amine compound (A) and the vinyl alcohol polymer (B) containing the carboxyl group in an amount of more than 5 mol% and not more than 30 mol% is in an appropriate range. Therefore, it is possible to remarkably improve the separation performance of a specific gas species and further the membrane permeation rate.

(Amine compound)
The content rate of the amine compound (A) used by this invention is 15-85 mass%. Thus, when the gas separation membrane of the present invention contains a certain amount of the amine compound (A), the film-forming property is good and the carbon dioxide selectivity is high. When the content of the amine compound (A) is less than 15% by mass, a gas separation membrane having high carbon dioxide selectivity may not be obtained, and is preferably 25% by mass or more, preferably 35% by mass or more. More preferably, it is more preferably 45% by mass or more. On the other hand, when the content of the amine compound (A) exceeds 85% by mass, the film-forming property of the obtained gas separation membrane may be deteriorated, preferably 75% by mass or less, and preferably 65% by mass or less. More preferably.

  In addition, the amine compound (A) used in the present invention preferably has high compatibility with the vinyl alcohol polymer (B). Amine-based compounds can be applied. For example, various amine-based polymers (A2) having a structural unit of polyamidoamine dendrimer, polyallylamine, polyvinylamine, or polyethyleneimine are preferable. Among them, the above formula (1) and / or formula ( The polyamidoamine dendrimer (A1) containing 1 to 9 meq / g of the group represented by 2) is preferred, and among these, the polyamidoamine dendrimer (A1) having a group represented by the formula (1) is preferred. Furthermore, it is more preferable to use a combination of the polyamidoamine dendrimer (A1) and the polyamine (A2) because a gas separation membrane having good film-forming properties and high carbon dioxide selectivity can be obtained. .

In formula (1) or formula (2), the divalent organic residue having 1 to 3 carbon atoms represented by A ¹ and A ² is, for example, a linear or branched alkylene group having 1 to 3 carbon atoms. Is mentioned. Specific examples of such alkylene _{groups, -CH 2 -, - CH 2} -CH 2 -, - CH 2 -CH 2 -CH 2 -, - CH 2 -CH (CH 3) - is like, Of these, —CH ₂ — is particularly preferable. In Formula (1) or Formula (2), n = 1 is preferable because affinity with a mixed gas containing water vapor increases.

  The polyamidoamine dendrimer (A1) used in the present invention contains 1 to 9 meq / g of the group represented by the above formula (1) and / or the group represented by the above formula (2). “Eq / g” represents the content of the functional group in the polyamidoamine dendrimer (A1), that is, the equivalent number of functional groups in 1 g of the polyamidoamine dendrimer (A1) (sometimes referred to as the number of moles). 1 meq / g means having 1 milliequivalent functional group in 1 g of molecule. Thereby, a gas separation membrane having high carbon dioxide selectivity can be obtained.

The polyamidoamine dendrimer (A1) used in the present invention can increase the number of primary amino groups in the molecule by forming a branched structure by an amidation reaction with ethylenediamine and increasing the number of branches. In the present invention, any number of polyamidoamine dendrimers can be suitably used without being limited by the number of branches. However, the content of primary amino groups is high, and the following is expected to be advantageous for the expression of the molecular gate mechanism. A 0th generation polyamidoamine dendrimer selected from the formulas (3) to (8) is particularly preferably used.

  Further, the amine compound (A) used in the present invention may contain another amine polymer (A2) in addition to the polyamide amine dendrimer (A1). Examples of the amine polymer (A2) include polyallylamine, polyvinylamine, and polyethyleneimine as described above, and these polymers may be partially modified. Of these, polyallylamine is preferred from the viewpoint of the stability of the film structure in a water vapor atmosphere.

  The content of each of the polyamidoamine dendrimer (A1) and the amine polymer (A2) in the compound (A) used in the present invention is (A1) / (A2) = 40/60 to 95/5 (mass ratio). It is preferable to do. Thus, when the content of both amine compounds is within a certain range, a gas separation membrane having good film forming properties and high carbon dioxide selectivity can be obtained. The total content of the polyamide amine dendrimer (A1) and the amine polymer (A2) is 100% by mass, and the content of the polyamide amine dendrimer (A1) is preferably 92% by mass or less, and 85% by mass or less. More preferably.

(Vinyl alcohol polymer)
Next, the vinyl alcohol polymer (B) used in the present invention will be described. The vinyl alcohol polymer (B) used in the present invention contains a carboxyl group in an amount of more than 5 mol% and not more than 30 mol%, with the total of monomer units constituting the vinyl alcohol polymer as 100 mol%. If a carboxyl group is contained, the hydrophilicity of the vinyl alcohol polymer (B) is improved, so that the permeation rate of carbon dioxide as a gas separation membrane is improved. The effect can be confirmed even when the content is 5 mol% or less as compared with the unmodified vinyl alcohol polymer. However, in order to provide a practical gas separation membrane for large-scale carbon dioxide emission sources such as coal gasification power generation, the permeation rate of carbon dioxide is still inadequate when the content is 5 mol% or less. It may be sufficient, and it is desirable to use a vinyl alcohol polymer having improved hydrophilicity. As a result of intensive studies, it was found that a vinyl alcohol polymer having a content of more than 5 mol% can be obtained by using a block copolymer or a graft copolymer, and a high carbon dioxide membrane permeation rate can be obtained. did it. On the other hand, it is difficult to produce a vinyl alcohol polymer having a carboxyl group content exceeding 30 mol%. As for the content rate of a carboxyl group, 7-20 mol% is preferable.

  In the gas separation membrane of the present invention, the total amount of the amine compound (A) and the vinyl alcohol polymer (B) is 100% by mass, and the content of the vinyl alcohol polymer (B) is 15 to 85% by mass. is there. Thus, by containing a certain amount of the vinyl alcohol polymer (B), it becomes possible to have a high carbon dioxide selectivity as well as a good film forming property. When the content rate of a vinyl alcohol type polymer (B) is less than 15 mass%, there exists a possibility that the film forming property of the gas separation membrane obtained may worsen. On the other hand, when the content of the vinyl alcohol polymer (B) exceeds 85% by mass, the absolute amount of the compound (A) to be contained is insufficient, so that sufficient carbon dioxide selectivity may not be obtained. It is preferably at most mass%, more preferably at most 65 mass%, further preferably at most 50 mass%.

  Furthermore, if the carboxyl group in the vinyl alcohol polymer (B) is partially or completely neutralized with an alkali metal, an osmotic pressure is generated by the dissociation of the alkali metal ion from the carboxyl group, and a vinyl alcohol polymer ( B) It is preferable because the water absorbing power of itself can be greatly increased. As a material for neutralizing the carboxyl group in the vinyl alcohol polymer (B) used in the present invention, it is preferable to use a compound containing an alkali metal, and any alkali metal-containing compound such as lithium, sodium, potassium, etc. However, potassium hydroxide or sodium hydroxide is preferably used. By improving the water absorption of the vinyl alcohol polymer (B), the hydrophilicity of the separation membrane material is further improved, and a large amount of water vapor can be retained in the membrane material. As a result, the chemical reactivity of carbon dioxide and water vapor increases, and the amount of reaction product increases, so that the membrane permeation rate of carbon dioxide can be further improved. From the viewpoint of increasing the effect of improving the membrane permeation rate of carbon dioxide, the degree of neutralization is preferably 0.1 or more, more preferably 0.2 or more, and more preferably 0.3 or more. Is more preferable.

Examples of the vinyl alcohol polymer (B) containing a carboxyl group used in the present invention include acrylic acid, methacrylic acid, crotonic acid, itaconic acid and the like in a vinyl alcohol polymer aqueous solution having a thiol group at the terminal. A carboxyl group-containing polymer block (B1) obtained by polymerizing a monomer having a carboxyl group or an acid anhydride thereof (see JP-A-59-187003 and JP-A-2001-233678). And a block copolymer containing the vinyl alcohol polymer block (B2).

  Moreover, as a vinyl alcohol polymer (B) containing a carboxyl group used in the present invention, a methanol solution of vinyl acetate and thioacetic acid esters (for example, thioacetic acid S-7-octen-1-yl ester) is used. A copolymer of vinyl acetate and a thioester monomer obtained by adding azobisisobutyronitrile to polymerize was saponified by a conventional method to obtain a polyvinyl alcohol having a mercapto group in the side chain. The carboxyl group-containing polymer (B′1) was grafted to the vinyl alcohol polymer (B′2) obtained by polymerizing the above monomer having a carboxyl group in the presence of a polymerization catalyst. A graft copolymer is mentioned.

  The saponification degree of the vinyl alcohol polymer (B) used in the present invention is preferably 50.0 to 99.9 mol%. If the saponification degree is less than 50.0 mol%, the water resistance of the gas separation membrane may be reduced. If it exceeds 99.9 mol%, workability during film formation may be reduced, or the gas separation membrane may be reduced. There is a possibility that the viscosity stability of the solution at the time of preparing the product is lowered. The saponification degree of the vinyl alcohol polymer (B) is more preferably 70.0 to 99.5 mol%. Thus, the vinyl alcohol polymer (B) used in the present invention can contain unsaponified vinyl ester units in addition to the vinyl alcohol units.

  The vinyl alcohol polymer (B) is a monomer unit other than the vinyl alcohol unit, the vinyl ester unit, the ethylene unit, and the unit containing a carboxyl group, as long as the effects of the present invention are not impaired. You may contain. Examples of such a monomer unit include ethylene, methyl acrylate, ethyl acrylate, acrylic acid esters such as n-propyl acrylate and i-propyl acrylate; methyl methacrylate, ethyl methacrylate, Methacrylic acid esters such as n-propyl methacrylate and i-propyl methacrylate; acrylamide; acrylamide derivatives such as N-ethylacrylamide; methacrylamide; methacrylamide derivatives such as N-methylmethacrylamide and N-ethylmethacrylamide; methyl vinyl ether , Vinyl ethers such as ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether; nitriles such as acrylonitrile and methacrylonitrile; vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride Halogenated vinyl; allyl acetate, allyl compounds allyl chloride; vinyl silyl compounds such as vinyltrimethoxysilane; a unit derived from monomers such as isopropenyl acetate and the like. The content of these monomer units is preferably 10 mol% or less, and more preferably 5 mol% or less.

［式中、Ｒ^１及びＲ^２は、それぞれ独立して、置換基を有してもよい炭素数１〜２０のアルキレン基であり、Ｘ^１、Ｘ^２、Ｘ^３、Ｘ^４、Ｘ^５及びＸ^６は、それぞれ独立して水素原子、水酸基、置換基を有してもよい炭素数１〜２０の有機基であり、Ｙ⁻は、アニオンである。］ In the gas separation membrane of the present invention, a crosslinking agent may be appropriately blended in order to ensure necessary water resistance or pressure resistance against water vapor and pressure of the mixed gas. The crosslinking agent here includes a crosslinking agent having an azetidinium group represented by the following formula (8), a compound having two or more functional groups such as an epoxy group, an aldehyde group, and a halogen atom, a titanium crosslinking agent, and a zirconium crosslinking agent. Are mentioned as preferred.

[Wherein, R ¹ and R ² are each independently an alkylene group having 1 to 20 carbon atoms which may have a substituent, and X ¹ , X ² , X ³ , X ⁴ , X ⁵ and X ⁶ is each independently a hydrogen atom, a hydroxyl group, or an organic group having 1 to 20 carbon atoms that may have a substituent, and Y ⁻ is an anion. ]

(Gas separation membrane)
The amine compound (A) and the vinyl alcohol polymer (B) include water, organic solvents such as dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N, N dimethylacetamide (DMAc), and mixtures thereof. In particular, the membrane-forming stock solution is preferably prepared by dissolving and mixing in water, and the stock solution is discharged from the die into a film shape or formed into a hollow fiber shape from a nozzle to form a dried gas separation membrane. The film thickness of the gas separation membrane is preferably from 0.01 to 100 μm, more preferably from 0.1 to 20 μm, still more preferably from 0.1 to 10 μm.

(Supporting membrane)
The gas separation membrane of the present invention is in the form of a support membrane and a composite membrane by forming the gas separation membrane by discharging the stock solution onto the support membrane and drying it, and the form of the composite membrane is practically used. It is preferably used as possible. The polymer constituting the support membrane is not particularly limited, and examples thereof include polysulfone, polyethersulfone, polyamide, polyimide, polyacrylonitrile, polystyrene, polyvinylidene fluoride, polyvinyl chloride, and polymethyl methacrylate. A porous membrane formed from these polymers can be used as a support membrane. The membrane shape may be various shapes such as a film and a hollow fiber. The size of the hole, the film thickness, and the like can be appropriately selected in consideration of the gas permeation amount and the mechanical strength of the film.

  The gas separation membrane of the present invention thus obtained is excellent in the ability to selectively separate specific gas species, particularly carbon dioxide, and can be suitably used in thermal power plants, steelworks, cement factories and the like. .

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in more detail, this invention is not limited at all by these Examples.

[Measurement of permeation rate and carbon dioxide selectivity]
The carbon dioxide permeation rate Q (CO ₂ ) (m ³ / m ² · s · Pa) and the helium permeation rate Q (He) (m ³ / m ² · s · Pa) were measured as follows. Carbon dioxide selectivity α (CO ₂ / He) was determined.
A gas having a composition of CO ₂ / He = 80/20 (ml / min), a temperature of 40 ° C., and a relative humidity of 90 RH% was supplied to the gas separation membranes obtained in the examples and comparative examples, and on the permeate side The permeation rate of the separation membrane was measured by an isobaric method in which argon was supplied at 10 ml / min as a sweep gas.
Q (CO ₂ ) = (CO ₂ permeation flow rate) / (membrane area) · (CO ₂ supply partial pressure−CO ₂ permeation partial pressure)
Q (He) = (He permeation flow rate) / (membrane area) · (He supply partial pressure−He permeation partial pressure)
α = Q (CO ₂ ) / Q (He)

[Production of gas separation membrane]
Example 1
As vinyl alcohol polymer (B), acrylic acid is used as a modified monomer, and block copolymerization with PVA having an SH terminal with a polymerization degree of 1500 contains 7 mol% of carboxyl groups, and the degree of saponification of vinyl acetate units. A 98.6 mol% PVA 5 mass% aqueous solution was prepared, but the aqueous solution was stable. This modified PVA 5% aqueous solution, 0th generation polyamidoamine dendrimer (A1) of formula (3) (surface group: —CONHCH ₂ CH ₂ NH ₂ , number of surface groups: 4, inclusion of group represented by formula (1) Rate: 7.74 meq / g) 20% by mass methanol solution (manufactured by Aldrich) and polyallylamine (primary amino group content 17.5 meq / g) as an amine polymer (A2) (Nittobo Co., Ltd.) Manufactured and trade name “PAA-15C”) was used to prepare a solution by mixing each so as to have a blending ratio shown in Table 1. This solution was cast and dried at 20 ° C. to obtain a gas separation membrane having a thickness of 5 μm. A composite membrane was produced by forming the separation membrane on an ultrafiltration membrane (trade name Biomax, manufactured by Millipore) using a molecular weight cut off of 300,000 and polyethersulfone as a raw material, and the membrane permeation rate Q (CO ₂ ) was obtained. The obtained results are summarized in Table 1.

Example 2
As vinyl alcohol polymer (B), acrylic acid is used as a modified monomer and graft copolymerization with PVA having a degree of polymerization of SH groups in the side chain contains 10 mol% of carboxyl groups, vinyl acetate units A 5 mass% PVA aqueous solution with a degree of saponification of 98.5 mol% was prepared, but the aqueous solution was stable. This modified PVA 5% aqueous solution, 0th generation polyamidoamine dendrimer (A1) of formula (3) (surface group: —CONHCH ₂ CH ₂ NH ₂ , number of surface groups: 4, inclusion of group represented by formula (1) Rate: 7.74 meq / g) 20% by mass methanol solution (manufactured by Aldrich) and 15% by mass aqueous solution of polyallylamine (content of primary amino group 17.5 meq / g) as amine polymer (A2) (Nittobo Co., Ltd., trade name “PAA-15C”) was used to prepare a solution by mixing so as to achieve the blending ratio shown in Table 1. This solution was cast and dried at 20 ° C. to obtain a gas separation membrane having a thickness of 5 μm. A composite membrane was produced by forming the separation membrane on an ultrafiltration membrane (trade name Biomax, manufactured by Millipore) using a molecular weight cut off of 300,000 and polyethersulfone as a raw material, and the membrane permeation rate Q (CO ₂ ) was obtained. The obtained results are summarized in Table 1.

Example 3
As a vinyl alcohol polymer (B), acrylic acid is used as a modified species monomer, 7 mol% carboxyl group is contained by block copolymerization with PVA having an SH terminal with a polymerization degree of 1500, and neutralized with sodium hydroxide. The solution was neutralized at a degree of 0.1 to prepare a 5% by mass aqueous solution of PVA having a vinyl acetate unit saponification degree of 98.6 mol%, but the aqueous solution was stable. This modified PVA 5% aqueous solution, 0th generation polyamidoamine dendrimer (A1) of formula (3) (surface group: —CONHCH ₂ CH ₂ NH ₂ , number of surface groups: 4, inclusion of group represented by formula (1) Rate: 7.74 meq / g) 20% by mass methanol solution (manufactured by Aldrich) and 15% by mass aqueous solution of polyallylamine (content of primary amino group 17.5 meq / g) as amine polymer (A2) (Nittobo Co., Ltd., trade name “PAA-15C”) was used to prepare a solution by mixing so as to achieve the blending ratio shown in Table 1. This solution was cast and dried at 20 ° C. to obtain a gas separation membrane having a thickness of 5 μm. A composite membrane was produced by forming the separation membrane on an ultrafiltration membrane (trade name Biomax, manufactured by Millipore) using a molecular weight cut off of 300,000 and polyethersulfone as a raw material, and the membrane permeation rate Q (CO ₂ ) was obtained. The obtained results are summarized in Table 1.

Example 4
As a vinyl alcohol polymer (B), acrylic acid is used as a modified species monomer, 7 mol% carboxyl group is contained by block copolymerization with PVA having an SH terminal with a polymerization degree of 1500, and neutralized with sodium hydroxide. The solution was neutralized at a degree of 0.2 to prepare a 5% by mass aqueous solution of PVA having a vinyl acetate unit saponification degree of 98.6 mol%, but the aqueous solution was stable. This modified PVA 5% aqueous solution, 0th generation polyamidoamine dendrimer (A1) of formula (3) (surface group: —CONHCH ₂ CH ₂ NH ₂ , number of surface groups: 4, inclusion of group represented by formula (1) Rate: 7.74 meq / g) 20% by mass methanol solution (manufactured by Aldrich) and 15% by mass aqueous solution of polyallylamine (content of primary amino group 17.5 meq / g) as amine polymer (A2) (Nittobo Co., Ltd., trade name “PAA-15C”) was used to prepare a solution by mixing so as to achieve the blending ratio shown in Table 1. This solution was cast and dried at 20 ° C. to obtain a gas separation membrane having a thickness of 5 μm. A composite membrane was produced by forming the separation membrane on an ultrafiltration membrane (trade name Biomax, manufactured by Millipore) using a molecular weight cut off of 300,000 and polyethersulfone as a raw material, and the membrane permeation rate Q (CO ₂ ) was obtained. The obtained results are summarized in Table 1.

Example 5
As a vinyl alcohol polymer (B), acrylic acid is used as a modified species monomer, 7 mol% carboxyl group is contained by block copolymerization with PVA having an SH terminal with a polymerization degree of 1500, and neutralized with sodium hydroxide. The solution was neutralized at a degree of 0.8 to prepare a 5% by mass aqueous solution of PVA having a vinyl acetate unit saponification degree of 98.6 mol%, but the aqueous solution was stable. This modified PVA 5% aqueous solution, 0th generation polyamidoamine dendrimer (A1) of formula (3) (surface group: —CONHCH ₂ CH ₂ NH ₂ , number of surface groups: 4, inclusion of group represented by formula (1) Rate: 7.74 meq / g) 20% by mass methanol solution (manufactured by Aldrich) and 15% by mass aqueous solution of polyallylamine (content of primary amino group 17.5 meq / g) as amine polymer (A2) (Nittobo Co., Ltd., trade name “PAA-15C”) was used to prepare a solution by mixing so as to achieve the blending ratio shown in Table 1. This solution was cast and dried at 20 ° C. to obtain a gas separation membrane having a thickness of 5 μm. A composite membrane was produced by forming the separation membrane on an ultrafiltration membrane (trade name Biomax, manufactured by Millipore) using a molecular weight cut off of 300,000 and polyethersulfone as a raw material, and the membrane permeation rate Q (CO ₂ ) was obtained. The obtained results are summarized in Table 1.

Example 6
As a vinyl alcohol polymer (B), acrylic acid is used as a modified species monomer and 7 mol% of carboxyl groups are contained by sodium hydroxide by block copolymerization with PVA having an SH terminal with a polymerization degree of 1500. An aqueous solution of 5% by mass PVA with a saponification degree of 98.6 mol% of vinyl acetate units was prepared. The aqueous solution was stable. This modified PVA 5% aqueous solution, 0th generation polyamidoamine dendrimer (A1) of formula (3) (surface group: —CONHCH ₂ CH ₂ NH ₂ , number of surface groups: 4, inclusion of group represented by formula (1) Rate: 7.74 meq / g) 20% by mass methanol solution (manufactured by Aldrich) and 15% by mass aqueous solution of polyallylamine (content of primary amino group 17.5 meq / g) as amine polymer (A2) (Nittobo Co., Ltd., trade name “PAA-15C”) was used to prepare a solution by mixing so as to achieve the blending ratio shown in Table 1. This solution was cast and dried at 20 ° C. to obtain a gas separation membrane having a thickness of 5 μm. A composite membrane was produced by forming the separation membrane on an ultrafiltration membrane (trade name Biomax, manufactured by Millipore) using a molecular weight cut off of 300,000 and polyethersulfone as a raw material, and the membrane permeation rate Q (CO ₂ ) was obtained. The obtained results are summarized in Table 1.

Example 7
As vinyl alcohol polymer (B), acrylic acid is used as a modified monomer, and block copolymerization with PVA having an SH terminal with a polymerization degree of 1500 contains 7 mol% of carboxyl groups, and the degree of saponification of vinyl acetate units. A 98.6 mol% PVA 5 mass% aqueous solution was prepared, but the aqueous solution was stable. This modified PVA 5% aqueous solution, 0th generation polyamidoamine dendrimer (A1) of formula (3) (surface group: —CONHCH ₂ CH ₂ NH ₂ , number of surface groups: 4, inclusion of group represented by formula (1) A 20% by mass methanol solution (manufactured by Aldrich) with a rate of 7.74 meq / g was used to prepare a solution by mixing so as to achieve the blending ratio shown in Table 1. This solution was cast and dried at 20 ° C. to obtain a gas separation membrane having a thickness of 5 μm. A composite membrane was produced by forming the separation membrane on an ultrafiltration membrane (trade name Biomax, manufactured by Millipore) using a molecular weight cut off of 300,000 and polyethersulfone as a raw material, and the membrane permeation rate Q (CO ₂ ) was obtained. The obtained results are summarized in Table 1.

Example 8
In exactly the same manner as in Example 7, a 5% by mass aqueous solution of vinyl alcohol polymer (B) and a 20% by mass methanol solution (manufactured by Aldrich) of 0th generation polyamide amine dendrimer (A1) were used. The solution was prepared by mixing so as to achieve the blending ratio shown. This solution was cast and dried at 20 ° C. to obtain a gas separation membrane having a thickness of 5 μm. A composite membrane was produced by forming the separation membrane on an ultrafiltration membrane (trade name Biomax, manufactured by Millipore) using a molecular weight cut off of 300,000 and polyethersulfone as a raw material, and the membrane permeation rate Q (CO ₂ ) was obtained. The obtained results are summarized in Table 1.

Example 9
A gas separation membrane was prepared in exactly the same manner as in Example 1 except that potassium hydroxide was used as a neutralizing material for the carboxyl group of the vinyl alcohol polymer (B). A composite membrane was produced by forming the separation membrane on an ultrafiltration membrane (trade name Biomax, manufactured by Millipore) using a molecular weight cut off of 300,000 and polyethersulfone as a raw material, and the membrane permeation rate Q (CO ₂ ) was obtained. The obtained results are summarized in Table 1.

Comparative Example 1
As a vinyl alcohol polymer (B), PVA having a carboxyl group content of 1 mol%, a saponification degree of vinyl acetate units of 98.6 mol%, and a polymerization degree of 1800 by random copolymerization using itaconic acid as a modified species monomer. A gas separation membrane was produced in exactly the same manner as in Example 8 except that was used. A composite membrane was produced by forming the separation membrane on an ultrafiltration membrane (trade name Biomax, manufactured by Millipore) using a molecular weight cut off of 300,000 and polyethersulfone as a raw material, and the membrane permeation rate Q (CO ₂ ) was obtained. The obtained results are summarized in Table 1.

Comparative Example 2
As the vinyl alcohol polymer (B), acrylic acid is used as a modified species monomer, and by graft copolymerization with PVA having an SH group in the side chain with a polymerization degree of 1000, 10 mol% of carboxyl group is contained, sodium hydroxide Was neutralized with a neutralization degree of 0.8 to prepare a 5% by mass aqueous solution of PVA having a vinyl acetate unit saponification degree of 98.5 mol%, but the aqueous solution was stable. This modified PVA 5% aqueous solution, 0th generation polyamidoamine dendrimer (A1) of formula (3) (surface group: —CONHCH ₂ CH ₂ NH ₂ , number of surface groups: 4, inclusion of group represented by formula (1) Rate: 7.74 meq / g) 20% by mass methanol solution (manufactured by Aldrich) and 15% by mass aqueous solution of polyallylamine (content of primary amino group 17.5 meq / g) as amine polymer (A2) (Nittobo Co., Ltd., trade name “PAA-15C”) was used to prepare a solution by mixing so as to achieve the blending ratio shown in Table 1. This solution was cast and dried at 20 ° C. to obtain a gas separation membrane having a thickness of 5 μm. A composite membrane was produced by forming the separation membrane on an ultrafiltration membrane (trade name Biomax, manufactured by Millipore) using a molecular weight cut off of 300,000 and polyethersulfone as a raw material, and the membrane permeation rate Q (CO ₂ ) was obtained. The obtained results are summarized in Table 1.

Comparative Example 3
As a vinyl alcohol polymer (B), acrylic acid is used as a modified species monomer, 7 mol% of carboxyl group is contained by block copolymerization with PVA having an SH terminal with a polymerization degree of 1500, and neutralized with sodium hydroxide. The solution was neutralized at a degree of 0.8 to prepare a 5% by mass aqueous solution of PVA having a vinyl acetate unit saponification degree of 98.6 mol%, but the aqueous solution was stable. This modified PVA 5% aqueous solution, 0th generation polyamidoamine dendrimer (A1) of formula (3) (surface group: —CONHCH ₂ CH ₂ NH ₂ , number of surface groups: 4, inclusion of group represented by formula (1) Rate: 7.74 meq / g) 20% by mass methanol solution (manufactured by Aldrich) and 15% by mass aqueous solution of polyallylamine (content of primary amino group 17.5 meq / g) as amine polymer (A2) (Nittobo Co., Ltd., trade name “PAA-15C”) was used to prepare a solution by mixing so as to achieve the blending ratio shown in Table 1. This solution was cast and dried at 20 ° C. to obtain a gas separation membrane having a thickness of 5 μm. Under these conditions, the amount of the amine compound (A) was too large, so the film-forming property was poor, and the carbon dioxide membrane A specimen used for measurement of the permeation speed Q (CO ₂ ) could not be produced.

  The gas separation membrane according to the present invention is excellent in the performance of selectively separating a specific gas species, particularly carbon dioxide, from a mixed gas, particularly a mixed gas containing water vapor, and is produced from coal gasification thermal power generation. Since it is useful in, for example, separation of carbon dioxide from water shift gas, it has industrial applicability.

  Although the preferred embodiments of the present invention have been described above by way of example, those skilled in the art can make various modifications, additions and substitutions without departing from the scope and spirit of the present invention disclosed in the claims. It will be understandable.

Claims (6)

Vinyl alcohol containing 15 to 85% by mass of the amine compound (A) and more than 5 mol% and 30 mol% or less of carboxyl groups (the total of monomer units constituting the vinyl alcohol polymer is 100 mol%). system polymer (B) and 15 to 85 wt% seen including,
The amine compound (A) includes a polyamide amine dendrimer (A1) and / or an amine polymer (A2) that is compatible with the vinyl alcohol polymer (B).
The vinyl alcohol polymer (B) is a block copolymer containing (a) a carboxyl group-containing polymer block and a vinyl alcohol polymer block, or (b) a carboxyl group is added to the vinyl alcohol polymer. gas separation membranes containing polymer and said graft copolymer der Rukoto grafted.   The gas separation membrane according to claim 1, wherein the carboxyl group in the vinyl alcohol polymer (B) is partially or completely neutralized with an alkali metal.   The gas separation membrane according to claim 2, wherein the degree of neutralization of the carboxyl group by the alkali metal is 0.2 to 1. The polyamidoamine dendrimer (A1) is represented by the formula (1)

[Wherein, A ¹ represents a C 1-3 divalent organic residue, and n represents an integer of 0 or 1. ]
And / or formula (2)

[Wherein, A ² represents a divalent organic residue having 1 to 3 carbon atoms, and n represents an integer of 0 or 1. ]
The gas separation membrane according to claim 1, which is a polyamidoamine dendrimer (A1) containing 1 to 9 meq / g of the group represented by formula (1). Said amine compound (A), the polyamide amine dendrimer (A1), according to claim 1, characterized in that it comprises a primary amino group of 10~35meq / g containing amine based polymer (A2), the Gas separation membrane. The gas separation membrane according to any one of claims 2 to 5 , wherein potassium hydroxide or sodium hydroxide is used as the alkali metal.