JPS6153083B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a separation membrane for fluids such as gas mixtures, liquid mixtures, and solutions, and a method for producing the same. For example, a gas separation membrane is a membrane-shaped molded body used to selectively separate gases in a gas mixture containing different types of gases, and various types of forming materials and forms are known. ing. Fluid separation membranes made of cellulose acetate have been commonly used as fluid separation membranes, but they have the disadvantage of being highly hygroscopic and are not resistant to acids and bases. Because it does not have this property, it may not be usable depending on the purpose, and it is difficult to say that it is a fluid separation membrane that is fully satisfactory for practical purposes. On the other hand, fluid separation membranes made of poly(arylsulfone), which is chemically stable and has excellent heat resistance, have been known for some time, but their permeation performance is not high enough, so they are not satisfactory. I can not say. In general, the basic performance required of fluid separation membranes is permeation performance, which evaluates the permeation rate at which fluid components such as gas mixtures, liquid mixtures, and solutes in solutions permeate through the membrane; It is well known that there is a separation performance that is an evaluation of how much of the material is preferentially transmitted. It is also well known that when fluid separation membranes are classified according to their structure, they are broadly divided into three types: homogeneous membranes, porous membranes, and asymmetric membranes. A homogeneous membrane is a membrane obtained by simply forming a conventional membrane-forming polymer into a membrane, and the membrane layer does not substantially have a porous structure. Therefore,
Although homogeneous membranes have excellent separation performance, their permeation performance is significantly inferior. On the other hand, porous membranes with a porous structure within the membrane layer generally have an excellent permeation rate;
There is a problem that the separation performance is not sufficient. By taking advantage of the advantages of these homogeneous membranes and porous membranes,
Asymmetric membranes have been developed to alleviate this disadvantage, and are porous membranes with a thin homogeneous layer on one side of the membrane. Since the asymmetric membrane has such a structure, its permeation performance is at a higher level than that of a homogeneous membrane, and its separation performance is also at a higher level than that of a porous membrane. Since there is a known technology to improve the basic performance of fluid separation membranes by improving the membrane structure as described above, we have developed the characteristics of poly(arylsulfone), which has excellent chemical resistance and heat resistance, as described above. Attempts are also being made to take advantage of this and develop separation membranes that have practically excellent permeation performance and separation performance. For example, the specification of JP-A-51-129880 discloses a gas separation membrane in which poly(arylsulfone) is formed into an asymmetric membrane. Since this gas separation membrane is in the form of an asymmetric membrane, the permeability is improved compared to a homogeneous membrane, but it is still not fully satisfactory from a practical standpoint. The present invention provides gas mixtures, liquid mixtures, which have excellent heat resistance and chemical resistance, and which have a practically high level of permeation performance and separation performance.
The object is to provide a separation membrane for separating each component of a fluid such as a solution, and this object can be achieved by the separation membrane of the present invention as described below. That is, the separation membrane of the present invention has (A)
Poly(arylsulfone) and (B) poly-(2.
6-diphenylphenylene oxide) and/or nitrated poly-(2,6-diphenylphenylene oxide), and the weight ratio of component (A) to component (B) is 98 :2~60:40 (A:B)
A fluid separation membrane in the form of a porous membrane or an asymmetric membrane, characterized in that it is within the range of . Poly(arylsulfone) has the formula It is a polymer consisting of repeating structural units represented by the following, and is a substance known as a film-forming polymer. Poly-(2,6-diphenylphenylene oxide) is known as a polymeric material with industrial uses such as films, heat-resistant fibers, flame-retardant fibers, electrical insulation, and protective coatings. nitrated poly-
(2,6-diphenylphenylene oxide) is
It can be produced by nitration of poly-(2,6-diphenylphenylene oxide) by a known method. Polymers particularly suitable for use in the present invention
(2,6-diphenylphenylene oxide) is manufactured by the method disclosed in the specification of Japanese Patent Publication No. 55-23298, that is, the atomic ratio of copper and nitrogen is 1:1.5 to 100. A poly-(2,6- Examples include those with a high degree of polymerization such as diphenylphenylene oxide). Nitrated poly-(2,6-diphenylphenylene oxide) can be easily produced, for example, by the method described below. Poly-(2,6-diphenylphenylene oxide) is dissolved in an organic solvent such as chloroform, and fuming nitric acid is added dropwise to the resulting solution under stirring. After the addition is complete, water is added to the reaction system, and then the organic solvent layer is separated. After repeatedly washing this organic solvent layer with water to remove the nitric acid contained therein, methanol was added to precipitate the product, which was separated and nitrated poly(2.6
-diphenylphenylene oxide). Poly(aryl sulfone) contained in the composition used in the membrane of the present invention...named as component (A), and poly(2,6-diphenylphenylene oxide) and/or nitrated poly(2. 6-diphenylphenylene oxide)...named as component (B), must be within the range of 98:2 to 60:40 (A:B) in terms of weight ratio. If the ratio of component (A) to component (B) is higher than 98:2, that is, if component (A) is used in an amount greater than the above range, the intended effects of the present invention cannot be achieved. On the other hand, if the ratio of component (A) to component (B) is lower than 60:40, that is, if component (B) is used in a larger amount than the above range, the film forming ability will decrease, for example, "unevenness" will appear on the surface of the formed film. This method is inappropriate for achieving the purpose of the present invention because phenomena such as the formation of a The fluid separation membrane of the present invention is formed in the form of a porous membrane or an asymmetric membrane. A preferred manufacturing method for manufacturing the separation membrane of the present invention is as follows:
(A) poly(arylsulfone) and (B) poly-
(2,6-diphenylphenylene oxide) and/or nitrated poly-(2,6-diphenylphenylene oxide) in a ratio of 98:2 to 60:40 (A:B)
The method is characterized by forming a solution dissolved in a solvent at a weight ratio within the range of , preferably by a solution casting method, into a thin film, and then extracting and removing the solvent of the solution from the obtained thin film. Examples of manufacturing methods include: poly(arylsulfone), and poly(2.
As the solvent for dissolving nitrated poly-(2,6-diphenylphenylene oxide) and/or nitrated poly(2,6-diphenylphenylene oxide), solvents that can dissolve each of these components, such as dimethylformamide, dimethyl Examples include a mixed solvent of formamide and tetrahydrofuran, N-methylpyrrolidone, and the like. In order to prepare a thin film from a polymer solution, it is preferable to use a solution casting method. This solution casting method is a method in which a solution is cast into a thin film of 0.05 to 2 mm thick on a plate such as a glass plate using, for example, a doctor blade, and then the thin film is prepared by removing the solvent. Since the method itself is well known, detailed explanation will be omitted. In order to create a porous film by creating a porous structure in the thin film obtained by the solution casting method, it is necessary to use a solvent that is miscible with the solvent used to prepare the solution for forming the film and does not dissolve the film. By treating the thin film with a solvent such as a lower alcohol such as methanol, propanol, or butanol, water, or a mixed solvent of these lower alcohols and water, the solvent used in the film forming component solution can be removed. Known methods such as coagulating the membrane-forming components during extraction may be used. In order to produce an asymmetric membrane, a known method can be used, such as blowing air onto one side of the membrane being produced during or immediately after the solution casting method. In addition,
In order to use the fluid separation membrane of the present invention efficiently, the thickness of the membrane is preferably 0.1 to 2 mm. The separation membrane of the present invention having the above-described configuration has both high levels of permeation performance and separation performance,
In addition to advantages such as providing particularly high permeation rates,
Furthermore, as is clear from the characteristics of each component used to form the membrane, it has a high degree of heat resistance and chemical resistance, making it an excellent membrane for use in fluid separation in industrial processes. It is. Note that the fluid to be separated by the separation membrane of the present invention is not particularly limited, and includes various gas mixtures, liquid mixtures, solutions and suspensions containing various components in a dissolved or suspended state. For example, a desired gas can be selectively separated from a mixture of various gases. Examples of combinations of gases constituting such a gas mixture include hydrogen and carbon monoxide, oxygen and nitrogen, hydrogen and nitrogen, carbon dioxide and methane, helium and methane, helium and nitrogen, and the like. The separation membrane of the present invention is particularly useful for separating hydrogen and carbon monoxide. It can also be used for purposes such as ultrafiltration of solutions. Next, examples will be described to explain the present invention in more detail. The samples and test methods used in each of the Examples described below are described below. [Preparation of film-forming solution (dope)] (1) Film-forming components (a) Poly(arylsulfone): Polysulfone (manufactured by Union Carbide; p-3500) (b) Poly-(2,6-diphenylphene) Nylene oxide): one with an intrinsic viscosity [η] of 1.08 obtained by the method described in the specification of Japanese Patent Publication No. 55-23298 (c) Nitrated poly-(2,6-diphenylphenylene oxide) ): Obtained by the method described below using poly-(2,6-diphenylphenylene oxide) with an intrinsic viscosity [η] = 1.08 as described in (b) above as a raw material, and is nitrated by about 0.5 per monomer unit. thing. Poly-(2,6-diphenylphenylene oxide) was dissolved in chloroform to prepare a solution with a concentration of 6.3%, and poly-(2,6-
Diphenylphenylene oxide) 1ml per 1g
Drop in fuming nitric acid (d=1.5). After the reaction, water is added to the reaction mixture, the chloroform layer is separated and taken out, and this chloroform solution is
Repeatedly wash with water until the washing solution no longer shows acidity. This chloroform solution is then poured into methanol and the precipitated product is separated. (2) Preparation of film-forming solution (dope) A 25% by weight dimethylformamide (DMF) solution of the film-forming components was prepared under a nitrogen atmosphere.
This solution was degassed by pressing through paper with a retention size of 5 μm to obtain a dope. [Evaluation of gas permeation performance and gas separation performance] The permeation performance and separation performance of the separation membrane were measured using hydrogen gas (H ₂ ) and carbon monoxide gas (CO) according to a known evaluation method. The specific method for measuring gas permeation rate used to evaluate the separation membrane of the present invention is as follows. The membrane to be measured was set in a stainless steel cell with a membrane area of 14.65 ^cm2 , and 0.5% hydrogen gas was added to one side of the cell.
A pressure of Kg/cm ² was introduced, and the rate at which hydrogen gas permeated through the membrane was measured using a flowmeter. Carbon monoxide was also measured in the same way. Note that the measurement temperature was maintained constant at 30°C using a constant temperature bath. From the obtained measured values, the transmittance and resolution were calculated according to the following equations. Permeability (P') = Permeated gas amount/membrane area (14.65cm ² ), permeation time (seconds), pressure difference (0.5 x 76cmHg) Separation rate = Hydrogen permeability (P' _H2 )/monooxide Carbon permeability (P' _cp ) Example 1 20 g of poly(arylsulfone) and 5 g of nitrated poly-(2,6-diphenylphenylene oxide)
g in 75 g of dimethylformamide (DMF), pressure-filtered and defoamed to form poly(arylsulfone) and nitrated poly-(2,6-diphenylphenylene oxide) at a weight ratio of 80:20. A dope containing This dope is applied by solution casting method.
After being cast into a film with a thickness of 0.2 mm on a glass plate,
It was dried for 2 minutes at 60°C in a nitrogen atmosphere. Next, this cast membrane was immersed in a coagulation bath consisting of methanol for one day and night to solidify it, and then dried in air to produce a porous membrane. Example 2 A porous membrane was produced in the same manner as in Example 1, except that water containing 2% DMF and 0.5% lauryl sulfate sodium salt was used instead of methanol as the coagulation bath. Example 3 The drying time of the dope casting film was changed to 1 minute instead of 2 minutes.
A porous membrane was manufactured in the same manner as in Example 1, except that the time was 10 minutes. Example 4 23.75g of poly(arylsulfone) and poly-
(2,6-diphenylphenylene oxide) 1.25
A dope containing poly(aryl sulfone) and poly-(2,6-diphenylphenylene oxide) at a weight ratio of 95:5 was prepared by dissolving 7.5 g of DMF and pressurizing and defoaming. . This dope was cast onto a glass plate in the form of a film with a thickness of 0.2 mm by the solution casting method, and then immediately immersed in a coagulation bath consisting of water containing 2% DMF and 0.5% sodium lauryl sulfate salt overnight. and solidified. Then, it was dried in air to produce a porous membrane. Comparative Example 1 A porous membrane was produced in the same manner as in Example 1, except that a dope containing 25 g of poly(arylsulfone) and 75 g of DMF was used. Comparative Example 2 12.5 g of poly(arylsulfone), nitrated poly-(2,6-diphenylphenylene oxide)
Same as Example 1 except that 12.5 g and 75 g of DMF were used and a dope containing poly(aryl sulfone) and nitrated poly-(2,6-diphenylphenylene oxide) in a weight ratio of 50:50 was used. A porous membrane was produced. The obtained porous membrane had "unevenness" on its surface. The gas permeation rate of each of the porous membranes obtained in Example 1-4 and Comparative Example 1-2 was measured by the method described above, and the permeability of hydrogen and the degree of separation between hydrogen and carbon monoxide were determined. Calculated. The results obtained are shown in Table 1.

[Table] As is clear from the separation data shown in Table 1, the membranes obtained in each example exhibited the characteristics of a porous membrane. The porous membrane obtained in Example 1-4 shows superior hydrogen permeation performance compared to the porous membrane formed using only poly(arylsulfone) (Comparative Example 1). . Example 5 22.5 g of poly(aryl sulfone) and nitrated poly-(2,6-diphenylphenylene oxide)
2.5g, DMF and THF (tetrahydrofuran)
Poly(arylsulfone) was dissolved in 7.5 g of a mixed solvent (THF/DMF=1.5) with
and nitrated poly-(2,6-diphenylphenylene oxide) in a weight ratio of 90:10. This dope was cast onto a glass plate in the form of a film with a thickness of 0.2 mm by a solution casting method, and then left as it was at room temperature for 1 minute. Next, this cast membrane was immersed in a coagulation bath consisting of methanol overnight to solidify it, and then dried in air to produce an asymmetric membrane. Example 6 Poly(arylsulfone) 17.5g, poly-
(2,6-diphenylphenylene oxide) 7.5
g, and a mixed solvent of DMF and THF (THF/
The same procedure as in Example 5 was carried out except that 75 g of DMF=1.5) was used and a dope containing poly(aryl sulfone) and poly-(2,6-diphenylphenylene oxide) at a weight ratio of 70:30 was used. An asymmetric membrane was produced. Comparative example 3 25g of poly(arylsulfone) and DMF
An asymmetric membrane was produced in the same manner as in Example 5, except that a dope containing 75 g of a mixed solvent with THF (THF/DMF=1.5) was used. The gas permeation rate was measured for each of the asymmetric membranes obtained in Examples 5-6 and Comparative Example 3 by the method described above, and the hydrogen permeation rate and the degree of separation between hydrogen and carbon monoxide were calculated. . The results obtained are shown in Table 2.

[Table] As is clear from the data shown in Table 2, the separation membrane of the present invention (Examples 5-6) was formed using poly(arylsulfone) even when formed into an asymmetric membrane.
This shows a higher hydrogen permeability compared to an asymmetric membrane formed using only asymmetric membranes.

Claims (1)

[Claims] 1. (A) poly(aryl sulfone) and (B) poly-
(2,6-diphenylphenylene oxide) and/or nitrated poly-(2,6-diphenylphenylene oxide), and the weight of component (A) and component (B) Ratio is 98:2 to 60:40
A fluid separation membrane in the form of a porous membrane or an asymmetric membrane, characterized in that the ratio is within the range of (A:B). 2 (A) poly(arylsulfone) and (B) poly-
(2,6-diphenylphenylene oxide) and/or nitrated poly-(2,6-diphenylphenylene oxide) in a ratio of 98:2 to 60:40 (A:B)
1. A method for producing a fluid separation membrane, which comprises forming a solution dissolved in a solvent at a weight ratio within the range of 1 to 1 in a thin film, and then extracting and removing the solvent of the solution from the obtained thin film.