JPH0824602A - Surface-improve gas separation membrane and its preparation - Google Patents

Abstract

PURPOSE:To provide a gas separation membrane wherein performance of the membrane is not easily decreased when it is brought into contact with water and a method for preparation thereof. CONSTITUTION:This membrane is a hydrophilic polymer membrane integrated as a composite at least on the outer surface of a polymer hollow fiber membrane, and the method for preparing a surface-improved gas separation membrane is a method wherein the hydrophilic polymer membrane is prepd. by bringing at least the outer surface of a surface-improved gas separation membrane and a polymer hollow fiber membrane consisting of a polymer of an unsatd. carboxylate with two double bounds of a general formula CH2=CR<2> CO-OR<1>O-COCR<3>=CH2 (wherein OR<1>O- is a lower alkylene glycol residue or a polylower alkylene glycol residue and R<2> and R<3> are each hydrogen or a methyl group), into contact with the above described unsatd. corboxylate or prepolymer and polymerizing them.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a gas separation membrane suitable as a carbon dioxide separation membrane and a method for producing the same.

[0002]

2. Description of the Related Art In order to separate and concentrate carbon dioxide (CO ₂ ) from a mixed gas, the mixed gas is brought into contact with one side of a separation membrane (CO ₂ adsorption side), and the other side of the separation membrane (CO ₂ adsorption side). A method of separating and concentrating carbon dioxide on the (CO ₂ releasing side) is known. In the carbon dioxide separation / concentration technology, the carbon dioxide separation efficiency is greatly affected by the performance of the separation membrane, and there is a demand for the development of a separation membrane having a high carbon dioxide separation coefficient. As a gas separation membrane, a membrane formed by forming a plasma polymer thin film of a fluorine compound on a porous membrane is known (JP-A-62-204285, JP-A-62-204826, and JP-A-62-204827). However, these separation membranes have a CO ₂ / N ₂ separation coefficient of 3.
Since it is as low as 9 to 8.0, it cannot be applied as a practical carbon dioxide separation membrane. Further, as a gas separation membrane, a membrane using an aromatic polyimide which is a reaction product of an aromatic tetracarboxylic acid and an aromatic diamine is known (JP-A-60-150806 and 61-13310).
No. 6, 63-126420). The CO ₂ / N ₂ separation coefficient of these aromatic polyimide-based separation membranes is usually 20 to 20.
Although it is relatively high as 30, it cannot be said that it is still an efficient carbon dioxide separation membrane. A membrane in which polyethylene glycol is impregnated and held porous is known as a membrane having a high number of CO ₂ / N ₂ separation liquids (Journal of the Chemical Society of Japan, N
o. 6 (1983) p. 847-853). Although this separation membrane shows a high CO ₂ / N ₂ separation coefficient of 110,
There is a problem that the retention of polyethylene glycol on the porous material is poor, and the polyethylene glycol is eluted when it comes into contact with water, and the membrane performance is reduced. further,
It is also known to use an immobilized liquid membrane in which an aqueous alkali metal carbonate solution is impregnated and held in a porous membrane as a carbon dioxide separation membrane (Science, 156, 1481-1484).
(1967)). However, this separation membrane also has a poor retention of the aqueous solution, and when it comes into contact with water, the aqueous solution is easily eluted and the membrane performance is deteriorated.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a gas separation membrane whose membrane performance does not easily deteriorate even when it comes into contact with water, and a method for producing the same.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention.

That is, according to the present invention, a hydrophilic polymer membrane is compounded on at least the outer surface of a polymer hollow fiber membrane, and the hydrophilic polymer membrane has a general formula CH ₂ = CR ² CO—OR ¹ O—COCR ³ ＣＨCH ₂ (wherein —OR ¹ O— represents a lower alkylene glycol residue or a poly lower alkylene glycol residue having a polymerization degree of 1 to 24, and R ² and R ³ represent (Indicating hydrogen or methyl group). The surface-modified gas separation membrane is characterized by comprising an unsaturated carboxylic acid ester polymer having two double bonds represented by the following formula:

Further, according to the present invention, a hydrophilic polymer membrane is compounded on at least the outer surface of a polymer hollow fiber membrane, and the hydrophilic polymer membrane has the general formula CH ₂ = CR in ^{2 CO-oR 1 O-COCR} 3 = CH 2 ( wherein, -OR ¹ O-represents a poly lower alkylene glycol residues of lower alkylene glycol residue or a polymerization degree 1 to 24, R ² and R ³ And a surface-modified gas separation membrane comprising a polymer of a polymerizable unsaturated carboxylic acid ester mixture containing an unsaturated carboxylic acid ester having two double bonds represented by hydrogen or methyl group). To be done.

Further, according to the present invention, at least on the outer surface of the polymer hollow fiber membrane, a general formula CH ₂ ＣＲCR ² CO—OR ¹ O—COCR ³ ＣＨCH ₂ (wherein —OR ¹ O— Represents a lower alkylene glycol residue or a poly-lower alkylene glycol residue having a polymerization degree of 1 to 24, and R ² and R ³ represent hydrogen or a methyl group). Alternatively, there is provided a method for producing a surface-modified gas separation membrane, which comprises contacting and polymerizing a prepolymer.

Furthermore, the general formula CH ₂ ═CR ² CO—OR ¹ O—COCR ³ ═CH ₂ (wherein —OR ¹ O— is a lower alkylene glycol residue) is present on at least the outer surface of the polymer hollow fiber membrane. Group or a poly (lower alkylene glycol) residue having a degree of polymerization of 1 to 24, and R ² and R ³ represent hydrogen or a methyl group). Provided is a method for producing a surface-modified gas separation membrane, which comprises contacting and polymerizing a saturated carboxylic acid ester mixture or a prepolymer thereof.

In the general formula (1), -OR ¹ O-
As the lower alkylene glycol residue or poly lower alkylene glycol residue represented by the following, the following can be exemplified. (Lower alkylene glycol residue) The lower alkylene glycol residue has 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms.
Can be derived from the lower alkylene glycol of, and specific examples thereof include the following. —OC ₂ H ₄ O—, OC ₃ H ₆ O—, —OC ₄ H ₈ O— and the like. (Poly lower alkylene glycol residue) Examples of the poly lower alkylene glycol residue include those derived from a polymer of a lower alkylene glycol having 1 to 6, preferably 1 to 4 carbon atoms. In this case, the degree of polymerization is 1 to 24, preferably 9 to 23. Specific examples of such a residue include the following. _{-O (C 2 H 4 O)} n -, - O (C 3 H 6 O) n -, - O (C
_{4 H 8 O) n -,} - O (C 2 H 4 O) p- (C 3 H 6 O) q-,
_{-O (C 3 H 6 O)} p- (C 2 H 4 O) q- or the like. However, in the above formula, n represents a number of 1 to 24, preferably 9 to 23. In addition, p and q represent one or more numbers whose sum is 2 to 29, preferably 12 to 26.

In the present invention, the unsaturated carboxylic acid ester represented by the above-mentioned general formula (1) (hereinafter, also simply referred to as a bifunctional unsaturated carboxylic acid ester) can be used alone, and can be used in other polymerizations. It can be used in the form of a mixture with an unsaturated carboxylic acid ester. Unsaturated carboxylic acid esters which can be blended with the bifunctional unsaturated carboxylic acid ester include monofunctional unsaturated carboxylic acid esters having one double bond, bifunctional unsaturated carboxylic acid esters having two double bonds, Polyfunctional unsaturated carboxylic esters having three or more heavy bonds are included. The unsaturated carboxylic acid ester preferably blended with the bifunctional unsaturated carboxylic acid ester represented by the general formula (1) is shown below.

(Monofunctional unsaturated carboxylic acid ester) In the present invention, it is preferable to use those represented by the following general formula (2). ^{_{CH 2 = CR 5 CO-OR}} 4 OR 6 (2) ( wherein, -OR ⁴ O-lower alkylene glycol residue or a polymerization degree 10, preferably poly lower alkylene glycol residues 6-9 And R ⁵ represents hydrogen or a methyl group, and R ⁶ represents an aliphatic group or an aromatic group.) Specific examples of —OR ⁴ O— in the general formula (2) include
Specific examples of the -OR ⁴ O-may be mentioned those given for the -OR ¹ O-. The aliphatic group represented by R ⁶ has 1 to 10 carbon atoms, preferably 1 to 4 carbon atoms. Examples of such an aliphatic group include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, and octyl. Examples of the aromatic group represented by R ⁶ include aryl groups such as phenyl and tolyl. These substituents R ⁶ may have a substituent such as an amino group, a nitro group, or an alkoxy. (Polyfunctional Unsaturated Carboxylic Acid Ester) The General Formula (1)
Examples of the polyfunctional unsaturated carboxylic acid ester preferably blended with the above monofunctional unsaturated carboxylic acid ester include the following. Trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol pentaacrylate, pentaerythritol pentamethacrylate, dipentaerythritol hexaacrylate, dipentaerythritol hexamethacrylate, etc.

In order to produce the gas separation membrane of the present invention, at least on the outer surface of the polymer hollow fiber membrane, the general formula (1)
Is contacted with an unsaturated carboxylic acid ester having two double bonds or a mixture of polymerizable unsaturated carboxylic acid esters containing the same (hereinafter, these are also simply referred to as polymerization raw materials), and a polymerization reaction is performed in this state. In this case, the polymerization raw material may be a prepolymer (B-stage resin) so as to be easily contacted and held on the surface of the polymer hollow fiber membrane, and may be polymerized while being held in contact with the surface of the polymer hollow fiber membrane.

As a method of bringing the polymerization raw material into contact with at least the outer surface of the polymer hollow fiber membrane, a method of immersing the polymer hollow fiber membrane in the polymerization raw material or its prepolymer or a solution thereof, a method of polymer hollow fiber membrane A method of spraying a polymerization raw material, a prepolymer thereof, or a solution thereof onto the outer surface of the substrate. As a solvent for obtaining the solution, any solvent can be used as long as it can dissolve the polymerization raw material or its prepolymer. Examples of such a solvent include water, lower alcohols such as methanol, ethanol, and propanol; hydrocarbons such as hexane, heptane, cyclohexane, benzene, etc .; methylethylketone, dioxane, dimethylformamide, dimethylsulfoxide, etc. Is mentioned.
The concentration of the polymerization raw material or its prepolymer in the solution is 0.1%.
It is from 0.5 to 50% by weight, preferably from 0.1 to 10% by weight. As the polymerization method, a conventionally known polymerization method such as a thermal polymerization method, a polymerization method by ultraviolet irradiation, a polymerization method by electron beam irradiation, or a polymerization method by plasma irradiation can be adopted.

When the polymerization is carried out by a thermal polymerization method, a radical polymerization initiator is added to the polymerization raw material. Examples of the radical polymerization initiator include, for example, azo-based polymerization initiators such as azobisisobutyronitrile and azobisvaleronitrile, and peroxide-based polymerization initiators such as benzoyl peroxide, methyl ethyl ketone peroxide and lauryl peroxide. Can be used. In this case, a chain transfer agent such as mercaptan may be used for adjusting the degree of polymerization. The compounding amount of the radical polymerization initiator with respect to the polymerization raw material is 0.1 to 3% by weight, preferably 0.2 to 1% by weight. The polymerization temperature is 70 to 150 ° C, preferably 80 to 1
The polymerization time is 30 to 800 minutes, preferably 90 to 600 minutes.

When polymerization is carried out by a polymerization method using ultraviolet irradiation, a photopolymerization initiator is blended with the polymerization raw material.
As the photopolymerization initiator, an azo compound such as azobisinbutyronitrile; benzoin such as benzoin, benzoin methyl ether, benzoisoethyl ether, benzoin propyl ether, benzoin isobutyl ether, α-methylbenzoin, α-phenylbenzoin Kind;
Anthraquinones such as anthraquinone, methylanthraquinone, and chloranthraquinone; onium salts such as p-methoxybenzenediazonium, hexafluorophosphate, diphenyliodonium, and triphenylsulfonium; benzyl, diacetyl, acetophenone, benzophenone, and methylbenzoyl Formate, diphenyl sulfide, dithiocarbamate, acrylic flavin, fluorescein and the like can be mentioned. These photopolymerization initiators are used alone or in a mixture. Further, urea, N, N-disubstituted-P-aminobenzonitrile and the like can be compounded as a sensitizer in the polymerization raw material. The amount of the photopolymerization initiator used is usually
It is 0.1 to 10% by weight, preferably 0.5 to 7% by weight. The amount of the sensitizer used is based on 100 parts by weight of the polymerization raw material.
Usually, it is 0.1 to 5 parts by weight. Electric power at ultraviolet irradiation is 1
The irradiation time is 0 to 200 W, preferably 20 to 100 W, and the irradiation time is 1 second or longer, preferably 1 to 30 minutes.

When the polymerization is carried out by the plasma irradiation polymerization method, the raw material for polymerization is preferably blended with a crosslinking accelerator, but this is not essential. As the crosslinking accelerator, 1
-Hydroxycyclohexyl phenyl ketone, benzyl dimethyl ketal, etc. are mentioned. The compounding amount is 0.05 to 5% by weight, preferably 0.1 to
It is 1% by weight. If necessary, the photopolymerization initiator as described above can be added to the heavy raw material. Ammonia, methane, ethane, propane, hydrogen, nitrogen, argon, or the like can be used as a plasma generating gas in the plasma irradiation. The temperature of the electrode plate in the plasma irradiation polymerization is 0 to 100 ° C, preferably 10 to 100 ° C.
70 ° C. and pressure is 0.01-2 Torr, preferably 0.1-1 Torr. Plasma irradiation power is 10
２００200W, preferably 20-100W. The plasma irradiation time is 120 minutes or less, preferably 3 seconds to 10 minutes.

In this plasma irradiation polymerization method, the bifunctional unsaturated carboxylic acid ester contained in the polymerization raw material is cross-linked and polymerized, and the strong hydrogen abstraction effect by the plasma causes a gap between the polymerization raw material and the polymer hollow fiber membrane. The reaction also occurs, and the polymer obtained by the polymerization of the polymerization raw material is firmly bonded to the surface of the polymer hollow fiber membrane. Therefore, from the viewpoint of the adhesive strength of the polymer membrane to the surface of the polymer hollow fiber membrane, it is preferable to use the plasma irradiation polymerization method.

When a mixture of the bifunctional unsaturated carboxylic acid ester represented by the above general formula (1) and the monofunctional unsaturated carboxylic acid ester is used as a raw material for polymerization, the proportion of the bifunctional unsaturated carboxylic acid ester used is as follows: It is at least 15% by weight, preferably at least 25% by weight, based on the mixture of both, and the proportion of the monofunctional unsaturated carboxylic acid ester used is at most 85% by weight, preferably at most 75% by weight, based on the mixture of both. is there. When a mixture of the bifunctional unsaturated carboxylic acid ester represented by the general formula (1) and a polyfunctional unsaturated carboxylic acid ester having three or more double bonds is used as a polymerization raw material, the bifunctional unsaturated carboxylic acid is used. The proportion of the ester used is 25 to 90% by weight, preferably 30 to 70% by weight, based on the mixture of both, and the proportion of the polyfunctional unsaturated carboxylic acid ester used is 10 to 75% by weight based on the mixture of both. %, Preferably 30 to 70% by weight.

Since the polymerization raw material used in the present invention contains a bifunctional unsaturated carboxylic acid ester having two double bonds, the polymer obtained from the polymerization raw material has a cross-linked structure and is It is insoluble in solvents such as methanol and ethanol, has excellent mechanical strength, and its polymer also has a melting point of 300 ° C. (33 in DSC measurement).
(0-350 ° C.) or more, and excellent in heat resistance. Polymer film as the formed on a polymer hollow fiber membranes, in its molecular structure, in order to have the the formula -OR ¹ O-with a hydrophilic group represented, hydrophilic gases such as , CO ₂ , SO ₂ , NO ₂ , NO, N ₂ O
It has high transmission performance with respect to the like. The thickness of the polymer film on the polymer hollow system is 0.01 to 5 μm, preferably 0.0 to 5 μm.
It is 5 to 1.0 μm.

The polymer hollow fiber membrane in the present invention includes:
Various conventionally known materials can be used. As the polymer in the polymer hollow fiber membrane, for example, polyimide,
Examples thereof include polyethersulfone, silicon, polypropylene, polyethylene, and polycarbonate. Any material can be used as long as it can be formed into a hollow fiber. In the present invention, the polymer hollow fiber membrane may have a porous structure, and in this case, the pore diameter forming the porous structure is 0.5 μm or less, preferably 0.1 μm or less. . The inner diameter of the hollow fiber in the polymer hollow fiber membrane is 100 to 500 μm, preferably 150 to 4 μm.
It is 00 μm. Also, the thickness of this polymer hollow fiber membrane is
It is 20 to 100 μm, preferably 40 to 80 μm.
From the viewpoint of obtaining a gas separation membrane having good gas permeation performance, as a polymer hollow fiber membrane, for example, a polymer hollow fiber membrane having a carbon dioxide permeation rate of 1 × 10 ⁻⁴ cm ³ / cm ² · sec · cmHg or more is used. Use is preferred.

In order to separate and collect or concentrate a hydrophilic gas from a mixed gas containing a hydrophilic gas (for example, carbon dioxide) using the polymer hollow fiber membrane of the present invention as a gas separation membrane, the polymer hollow fiber is used. The membrane is modularized and the gas mixture is brought into contact with the outside (or inside) of the membrane and the pressure of the gas mixture is kept higher than the inside (or outside) pressure on the opposite side of the membrane. When the mixed gas is brought into contact with one side of the separation membrane in this way, each component in the mixed gas is
Due to the partial pressure difference on both sides of the membrane, it diffuses and permeates through the separation membrane,
The components other than the hydrophilic gas have no affinity for the membrane, whereas the hydrophilic gas has affinity for the membrane. Therefore, the amount of the hydrophilic gas that permeates the membrane is extremely large, and the separation and recovery of the hydrophilic gas is performed. Alternatively, separation and concentration are achieved.

[0022]

EXAMPLES The present invention will now be described in more detail with reference to Examples. The gas permeation performance of the membrane in the following experiment was measured as follows.

(Measurement of Gas Permeability of Membrane) A pure gas of CO ₂ or N ₂ is supplied to the outside of the polymer hollow fiber membrane at a pressure of 5 kg / cm ² G, and the amount of gas permeating through the membrane is measured. Measurements were made with a soap film flow meter to determine the permeation rate Q (CO ₂ ), Q (N ₂ ) and the separation coefficient α = Q (CO ₂ ) / Q (N ₂ ).

Example 1 The following monomer A and monomer B were mixed and dissolved at a weight ratio of 9: 1, and then the following crosslinking accelerator C was added in an amount of 1 wt.
% To dissolve the mixture, and the mixture was diluted with water to 3 wt% to prepare a reaction solution. A non-porous polyimide asymmetric hollow fiber membrane as a polymer hollow system was dipped in the obtained reaction solution, and the hollow fiber membrane had a bell jar type reaction vessel with an equilibrium plate electrode inside, and a hollow fiber membrane of 13.56 MHz. Set between both electrode plates of a plasma processing device having a plasma generating power source, while introducing ammonia into the system at 22 cc / min, plasma treatment is performed for 3 minutes at a pressure of 0.5 Torr and an irradiation power of 150 W, thereby performing cross-linking polymerization. Then, a polymer hollow fiber composite membrane was obtained.

(Monomer A) (Polyethylene glycol dimethacrylate) CH ₂ ＣC (CH ₃ ) COO (C ₂ H ₄ O) ₁₄ COC (CH
₃ ) = CH ₂ (14G manufactured by Shin-Nakamura Chemical Co., Ltd.) (Monomer B) (Methoxypolyethylene glycol methacrylate) CH ₂ ═C (CH ₃ ) CO (OCH ₂ CH ₂ ) ₉ OCH ₃ (Shin Nakamura Chemical Co., Ltd. Co., Ltd., M-90G) (Crosslinking accelerator C) 1-hydroxycyclohexyl phenyl ketone

Example 2 In Example 1, the concentration of the mixed solution in the reaction solution was 1 wt.
%, The plasma irradiation power was 20 W, and the plasma irradiation time was 30 seconds, and the same experiment was conducted to obtain a polymer hollow fiber composite membrane.

Example 3 A reaction solution was prepared by diluting a mixed solution to 5 wt% with a mixed solvent of ethanol and hexane (mixing weight ratio = 1: 4) in Example 1, and a pressure of 0.2 Torr was applied. A polymer hollow fiber composite membrane was obtained in the same manner except that the plasma treatment was performed at a power of 50 W and a treatment time of 10 minutes.

Example 4 In Example 1, the mixture was diluted to 1.3 wt% with a mixed solvent of ethanol and hexane (mixing weight ratio = 1: 4) to prepare a reaction solution. A polymer hollow fiber composite membrane was obtained in the same manner as above except that the plasma treatment was performed with a torr, an irradiation power of 20 W, and an irradiation time of 10 minutes.

Example 5 The same as Example 1 except that polyethylene glycol dimethacrylate represented by the following formula was used in place of the monomer A, and the plasma treatment was performed under a pressure of 0.2 Torr, an irradiation power of 50 W and an irradiation time of 10 minutes. To obtain a polymer hollow fiber composite membrane. _{CH 2 = C (CH 3)} COO (C 2 H 4 O) 9 COC (CH 3) = C
H ₂ (9G, Shin-Nakamura Chemical Co., Ltd.)

Example 6 The same procedure as in Example 1 was carried out except that polyethylene glycol dimethacrylate represented by the following formula was used in place of the monomer A, and a plasma treatment was performed at a pressure of 0.5 Torr, an irradiation power of 100 W, and an irradiation time of 5 minutes. Thus, a polymer hollow fiber composite membrane was obtained. CH ₂ = C (CH ₃ ) COO (C ₂ H ₄ O) ₂₃ COC (CH ₃ ) =
CH ₂ (manufactured by Shin-Nakamura Chemical Co., Ltd., 23G)

Example 7 In Example 1, the monomers A and B were mixed at a weight ratio of 1: 2, and the crosslinking accelerator C was not used.
Dilute the mixture to 20 wt% with water to prepare a reaction solution,
Furthermore, a polymer hollow fiber composite membrane was obtained in the same manner except that the plasma treatment was performed at a pressure of 0.5 Torr, an irradiation power of 100 W, and an irradiation time of 10 minutes.

Example 8 In Example 2, the polymer hollow fiber membrane had a carbon dioxide permeability of 5.2 × 10 ⁻³ cm ³ / cm ² · sec.
A polymer hollow fiber composite membrane was obtained in the same manner except that the one having cmHg was used.

Comparative Example 1 In Example 1, the polymer hollow fiber membrane was subjected to plasma treatment in the same manner as in Example 1 at a pressure of 0.5 Torr, an irradiation power of 100 W, and an irradiation time of 10 minutes. A fibrous membrane was obtained.

Table 1 shows the results of measuring the gas permeation performance of the surface-modified polymer hollow fiber membranes obtained in Examples 1 to 8 and Comparative Example 1 above. Reference Example 1 shown in Table 1 shows the polymer hollow fiber membrane used as the base material in Example 1, and Reference Example 2
Shows the polymer hollow fiber membrane used as the substrate in Example 8.

[0035]

[Table 1]

Example 9 The monomer A and the monomer B shown in Example 1 were added in a weight ratio of 4:
6, and mixed with 2,2'- as a polymerization initiator.
After adding 1 wt% of azobis (isobronitrile), this mixture was dissolved in a mixture of ethanol and isooctane (weight ratio = 1: 4) to obtain a reaction solution in which the mixture was diluted to 2 wt. After the reaction solution of the polyimide hollow fiber membrane was immersed for 5 seconds in, under N ₂ atmosphere 8
Polymerization reaction was carried out by heating at 0 ° C. for 8 hours to obtain a polymer hollow fiber composite membrane. Table 2 shows the gas permeation performance at 24 ° C.
Shown in The gas permeability of the polyimide hollow fiber membrane at 24 ° C. was 2.2 × 10 ⁻⁴ cm ³ / cm ² · sec.
cmHg.

Examples 10 to 14 Polymer hollow fiber composite membranes were obtained in the same manner as in Example 9 except that the monomers shown in Table 2 were used. Table 2 shows the gas permeation performance at 24 ° C. of these products. The specific contents of the monomers indicated by the reference symbols in Table 2 are as follows. (1) 14G CH ₂ ＣC (CH ₃ ) COO (C ₂ H ₄ O) ₁₄ COC (CH ₃ ) =
_{CH 2 (2) M90G CH 2} = C (CH 3) CO (OCH 2 CH 2) 9 OCH 3 (3) 23G CH 2 = C (CH 3) COO (C 2 H 4 O) 23 COC (CH 3) =
_{CH 2 (4) A600 CH 2} = CHCOO (C 2 H 4 O) 4 COCH = CH 2 (5) TMPT CH 3 CH 2 (CH 2 OCOC (CH 3) = CH 2) 3

[0038]

[Table 2]

[0039]

EFFECT OF THE INVENTION The gas separation membrane of the present invention has excellent separation performance, excellent heat resistance and durability, and excellent solvent resistance. Therefore, its surface is wet with a liquid such as water. However, the performance of the separation membrane does not easily deteriorate. The gas separation membrane of the present invention is a hydrophilic gas separation membrane, in particular,
It is suitable as a carbon dioxide separation membrane.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Yanagishita 1-1, Higashi, Tsukuba-shi, Ibaraki Institute of Industrial Science and Technology, Institute of Materials Engineering (72) Inventor Kenji Haratani 1-1, East, Tsukuba-shi, Ibaraki Material Institute of Engineering and Technology

Claims (10)

[Claims] 1. A composite of a hydrophilic polymer membrane on at least the outer surface of a polymer hollow fiber membrane, the hydrophilic polymer membrane having the general formula CH ₂ = CR ² CO-OR ¹ O-COCR ³ = CH ₂ (wherein, -OR ¹ O-represents a poly lower alkylene glycol residues of lower alkylene glycol residue or a polymerization degree 1 to 24, R ² and R ³ represents a hydrogen or a methyl group ) A surface-modified gas separation membrane comprising a polymer of an unsaturated carboxylic acid ester having two double bonds. 2. A polymer hollow fiber membrane comprising at least an outer surface of a hollow fiber membrane and a hydrophilic polymer membrane complexed on at least the outer surface of the hollow fiber membrane, wherein the hydrophilic polymer membrane has a general formula: CH ₂ = CR ² CO—OR ¹ O-COCR ³ ＣＨCH ₂ (wherein —OR ¹ O— represents a lower alkylene glycol residue or a poly lower alkylene glycol residue having a polymerization degree of 1 to 24, and R ² and R ³ represent hydrogen or a methyl group. A surface-modified gas separation membrane comprising a polymer of a polymerizable unsaturated carboxylic acid ester mixture containing an unsaturated carboxylic acid ester having two double bonds represented by the following formula: 3. A polymerizable unsaturated carboxylic acid ester mixture represented by the general formula: CH ₂ ＝ CR ⁵ CO—OR ⁴ O—R ⁶ (wherein —OR ⁴ O— is a lower alkylene glycol residue or a polymerization degree of 1 to 4). R ⁵ represents hydrogen or a methyl group, and R ⁶ represents an aliphatic group or an aromatic group). The surface-modified gas separation membrane according to claim 2, comprising: 4. The surface-modified gas separation separation membrane according to claim 2, wherein the polymerizable unsaturated carboxylic acid ester mixture contains an unsaturated carboxylic acid ester having three or more double bonds. 5. A polymer of the general formula CH ₂ ＣＲCR ² CO—OR ¹ O—COCR ³ ＣＨCH ₂ (wherein —OR ¹ O— is a lower alkylene glycol residue) on at least the outer surface of the polymer hollow fiber membrane. Or a poly (lower alkylene glycol residue having a polymerization degree of 1 to 24, and R ² and R ^{3 each} represent hydrogen or a methyl group). And producing a surface-modified gas separation membrane. 6. A polymer of the general formula CH ₂ ═CR ² CO—OR ¹ O—COCR ³ ═CH ₂ (wherein —OR ¹ O— is a lower alkylene glycol residue) on at least the outer surface of the polymer hollow fiber membrane. Or a poly (lower alkylene glycol residue having a degree of polymerization of 1 to 24, and R ² and R ³ represent hydrogen or a methyl group), and a polymerizable unsaturated compound containing an unsaturated carboxylic acid ester having two double bonds A method for producing a surface-modified gas separation membrane, which comprises contacting a carboxylic acid ester mixture or a prepolymer thereof to polymerize them. 7. The polymerizable unsaturated carboxylic acid ester mixture has a general formula CH ₂ ═CR ⁵ CO—OR ⁴ O—R ⁶ (wherein —OR ⁴ O— is a lower alkylene glycol residue or a polymerization degree 1 to 10 represents a poly-lower alkylene glycol residue, R ⁵ represents hydrogen or a methyl group, and R ⁶ represents an aliphatic group or an aromatic group), and an unsaturated carboxylic acid ester having one double bond The method for producing a surface-modified gas separation membrane according to claim 6, which comprises. 8. The method for producing a surface-modified gas separation membrane according to claim 6, wherein the polymerizable unsaturated carboxylic acid ester mixture contains an unsaturated carboxylic acid ester having three or more double bonds. 9. The method for producing a surface-modified gas separation membrane according to claim 6, wherein the polymerization is carried out by plasma irradiation. 10. The surface-modified gas separation membrane according to claim 1, wherein the surface-modified gas separation membrane is a carbon dioxide separation membrane.