JPH0363418B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a novel separation membrane used when separating a specific liquid component from a mixture of two or more organic liquids or a solution of organic compounds by a pervaporation method. [Technical background] From an organic liquid mixture or a solution of an organic compound (hereinafter collectively referred to as a liquid mixture),
A pervaporation method is known as an effective separation method for separating specific liquid components. In the pervaporation method, a liquid mixture is supplied to one chamber (processed liquid chamber) divided by a separation membrane, and the other chamber (permeated vapor chamber) is evacuated or depressurized to extract a specific liquid from the liquid mixture. This method takes out the components in a vaporized state into a permeation vapor chamber. Membranes used in such separation methods are required to have two properties: selective permeability to a specific substance in a liquid mixture and high absolute permeation rate. It is not necessarily clear what properties of the membrane are responsible for these two characteristics, but they are due to differences in polarity, molecular weight, or molecular structure of the composition components in the liquid mixture, and the strong and weak polar charges present in the separation membrane. It is believed that this is determined by the difference in pore size and distribution, or the size and length of pores existing on a microscopic scale. [Prior art and problems to be solved by the invention] Conventionally, as polymer membranes used in this pervaporation method, cellulose polymer membranes, polyethylene, polypropylene, polyacrylonitrile,
polyvinyl alcohol, polyvinyl acetal,
Membranes of polystyrene, polyester, polyamide, polytetrafluoroethylene, or copolymers thereof, or membranes surface-treated with ultraviolet rays, etc., and ion-exchanged polymer chains with sulfonic acid groups, carboxylic acid groups, etc. Membranes incorporating groups have been proposed. However, in reality, there are almost no membranes with high permeability coefficients and high separation coefficients. That is, in the pervaporation method using these polymer membranes, although the permeability coefficient generally shows a somewhat high value, the separation coefficient is small and the separation efficiency is extremely poor. [Means for Solving the Problems] The present inventors have conducted repeated research in order to develop a separation membrane with a high permeability coefficient and a high separation coefficient in the pervaporation method. As a result, the inventors discovered that an anion exchange membrane obtained by copolymerizing specific monomers can significantly improve the separation coefficient while maintaining a high permeability coefficient, leading to the completion of the present invention. The present invention provides at least acrylonitrile and/or
Or a quaternary pyridinium group consisting of a resin obtained by copolymerizing methacrylnitrile (hereinafter referred to as a nitrile compound), vinylpyridine, and a crosslinking agent, and the proportion of the nitrile compound in the resin is 2 to 30% by weight. This is a separation membrane for pervaporation consisting of a type anion exchange membrane. In the present invention, vinylpyridines are not particularly limited as long as they can be copolymerized with acrylonitrile and can be easily quaternized.
One or more of -vinylpyridine, 2-methyl-5vinylpyridine, 2-vinylpyridine, etc. is preferably used. In addition, as the crosslinking agent, a polyfunctional monomer having two or more ethylenic double bonds in the molecule can be used without particular restriction, but from the viewpoint of copolymerizability with allylonitrile and vinylpyridines, generally Divinylbenzene is preferred. In the present invention, the separation membrane for pervaporation (hereinafter also simply referred to as separation membrane) is made of a resin obtained by copolymerizing at least the above-mentioned vinylpyridines, a nitrile compound, and a crosslinking agent,
It is characterized by comprising a quaternary pyridinium-based anion exchange membrane in which the proportion of the nitrile compound in the resin is 2 to 30% by weight, preferably 5 to 25% by weight. That is, the present inventors copolymerized the resin constituting the anion exchange membrane with these three component monomers and selected the proportion of acrylonitrile, so that the anion exchange membrane could be used in the pervaporation method. They discovered that the separation coefficient could be dramatically improved. Therefore, even if vinylpyridines are replaced with other monomers capable of introducing anion exchange groups in the present invention, the separation membrane obtained in combination with acrylonitrile has little effect on improving the separation coefficient in the pervaporation method. Does not perform well. Furthermore, if the proportion of acrylonitrile is outside the above range, the separation coefficient of the separation membrane will be significantly reduced, and in particular, if it exceeds the above range, the permeability coefficient will also be reduced, making it impossible to achieve the object of the present invention. Furthermore, in the absence of a crosslinking agent, the anion exchange membrane will swell upon contact with the liquid to be treated, making it impractical and impairing the effect of improving the separation coefficient. The proportion of vinylpyridines in the resin constituting the separation membrane of the present invention is generally 45% by weight or more, preferably 60% by weight or more. When the proportion of vinylpyridines is less than the above range, the permeability coefficient of the separation membrane tends to decrease. In addition, the upper limit of the proportion of vinylpyridines is acrylonitrile,
It is determined by the addition ratio of a crosslinking agent, etc., which will be described later. If the proportion of the crosslinking agent is too small, swelling will be severe due to contact with the liquid to be treated, whereas if it is too large, the permeability coefficient will tend to decrease.
It is generally in the range of 1 to 25% by weight, preferably 2 to 15% by weight. In the present invention, the resin constituting the separation membrane can be obtained by copolymerizing the three monomers described above with other monomers within the range that acrylonitrile does not affect the performance of the resulting separation membrane. . Examples of such monomers include styrene, methyl methacrylate, methyl acrylate, ethyl methacrylate, dimethylaminoethyl methacrylate, and the like. The proportion of the above monomer in the resin is 20% by weight or less, preferably
Desirably 15% by weight or less. Further, known additives may be added to the resin without any particular restrictions. For example, polyvinyl chloride fine powder, polyethylene fine powder, rubbers, etc. are added in an amount of 1 to 10% by weight. A typical method for manufacturing the separation membrane of the present invention is a paste method. That is, a common method is to apply a monomer mixture containing vinylpyridines, acrylonitrile, and a crosslinking agent together with a radical polymerization initiator to a support such as a woven fabric, nonwoven fabric, knitted fabric, or microporous synthetic resin sheet, and then polymerize it. be.
The above polymerization temperature is generally suitably 60 to 120°C.
In addition, the thickness of the resin layer is 10 to 200μ, preferably
It may be adjusted to 50 to 150μ. The membrane-like material obtained by the above method is quaternized by a known method to form a quaternary pyridinium group which is an anion exchange group. Quaternization is generally carried out using a methyl iodide solution. The operating conditions for the pervaporation method using the separation membrane of the present invention are not particularly limited, but the pressure on the side of the mixed liquid chamber for supplying the liquid mixture is preferably 1 to 10 atmospheric pressure or less, preferably from the viewpoint of the strength of the membrane. A pressure of 1 to 2 atmospheres is preferred. In addition, in the pervaporation method, it is necessary to evaporate the liquid component that has permeated the separation membrane on the membrane surface on the permeation gas chamber side and take it out in a vapor state, so the pressure on the permeation gas chamber side must be It is preferable to maintain the pressure as low as possible than the vapor pressure of the substance passing through, and the pressure is usually 100 Torr or less, preferably 20 Torr or less. The temperature of the liquid mixture in the processing liquid chamber is not particularly limited, but a high temperature is preferable in terms of the permeability coefficient. However, if the temperature is too high, the film will crack and its durability will deteriorate, so generally the temperature is 10 to 100℃.
The temperature is preferably in the range of 30 to 80°C. The pervaporation method using the separation membrane of the present invention is preferably applied to a liquid mixture in which at least one component is a polar solvent and does not have a negative effect on the separation membrane. Examples of liquid mixtures consisting of two components include methanol/water, ethanol/water, iso- or normal-propanol/
water, methyl ethyl ketone/water, dioxane/water,
Liquid mixtures such as methanol/acetone and benzene/n-hexane may be mentioned. [Effects and Functions] As understood from the above explanation, the separation membrane of the present invention separates liquid components with an extremely high separation coefficient compared to separation membranes conventionally employed in pervaporation methods. Moreover, it is an epoch-making device that has a sufficiently high transmission coefficient. Therefore, according to the present invention, due to such excellent separation properties, liquid components can be separated from a liquid mixture very efficiently. [Examples] Hereinafter, embodiments of the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. Example 1 100 parts by weight of 4-vinylpyridine, 10 parts by weight of divinylbenzene (purity 50%), 1 part by weight of polyvinyl chloride fine powder, and 1 part by weight of benzoyl peroxide were used, and acrylonitrile was added to the total amount of the above monomer and resin. Six types of paste-like liquids were created by mixing and stirring at different ratios. The addition ratio of acrylonitrile is as shown in Table 1. These paste-like liquid materials were applied to a polyvinyl chloride cloth and polymerized by heating at 70° C. for 4 hours to form a polymer film. These polymer membranes were immersed in a quaternization solution consisting of methyl iodide and methanol = 1:1 at room temperature for 16 hours to carry out a quaternization reaction, thereby obtaining an anion exchange membrane. These anion exchange membrane membrane areas 40
A separation test of a mixed solution of i-propanol and water was conducted using the pervaporation method using a two-chamber liquid of 2 cm. The i-propanol concentration of the liquid to be treated was 90 wt%, the liquid temperature was 60°C, and the degree of vacuum on the permeate gas chamber side was 10 Torr. Permeability coefficient Q (Kg/m ² hr) and separation coefficient α of each membrane
are shown in Table 1. Separation coefficient α=C ₁ /C ₂ C ₁ : Water concentration on the permeate gas chamber side C ₂ : Water concentration in the liquid to be treated

[Table] Example 2 50 parts by weight of 2-methyl 5-vinylpyridine, 50 parts by weight of 4-vinylpyridine, 20 parts by weight of divinylbenzene (purity 50%), 2 parts by weight of fine polyvinyl chloride powder, 10 parts by weight of styrene, 20 parts by weight of acrylonitrile. (13.2% by weight) was mixed with benzoyl peroxide and stirred to prepare a paste-like liquid part. Next, apply this to a polyvinyl chloride cloth and apply it for 70 minutes.
Polymerization was carried out by heating at ℃ for 4 hours. The obtained polymer film was mixed with 4 consisting of methyl iodide:methanol=1:1.
It was immersed in a grading solution for 12 hours at room temperature to carry out a quaternization reaction and obtain anion exchange. IPA and water were separated under the same conditions as in Example 1, and the separation characteristics of the membrane were measured. As a result, the amount of permeate Q was 1.36Kg/
The m ² ·hr separation coefficient α was 370. Comparative Example The separation performance of the anion exchange membrane prepared in Example 2 without adding acrylonitrile was
1.27Kg/m ² hr, α was 100. Example 3 An anion exchange membrane was prepared in the same manner as in Example 2 except that acrylonitrile was replaced with methacrylonitrile, and the separation performance was measured. Q is
1.20Kg/m ² ·hr, α was 270. Comparative Example An anion exchange membrane was prepared in the same manner as in Example 2, except that acrylonitrile was changed to methyl acrylate, and the separation performance was measured. Q
was 0.84Kg/m ² ·hr and α was 130. Example 4 100 parts of 4-vinylpyridine, 25 parts of divinylbenzene
(purity 50%), 1 part polyvinyl chloride fine powder, 2 parts benzoyl peroxide, acrylonitrile
Mix and stir 10 parts and use a paste-like liquid.
An anion exchange membrane was prepared in the same manner as in Example 1. Similar to Example 1, a separation test between i-propanol (80 wt%) and water (20 wt%) was conducted.
The pervaporation conditions were the same as in Example 1. Separation performance is Q: 2.62Kg/m ²・hr, α: 280
It was hot. Example 5 Using the membrane prepared in Example 1 and having No. 49 acrylonitrile content of 12%, ethanol (85wt%)
A separation test was conducted on a mixed solution of 15% and water (15wt%).
The temperature of the mixed liquid is 50℃, and the degree of vacuum on the permeate gas chamber side is
It was 10 Torr. Permeated liquid amount Q is 1.05Kg/m ²・hr,
The separation factor α water/ethanol was 260. Comparative Example The separation performance of the anion exchange membrane prepared in Example 5 without adding acrylonitrile was that Q was 0.91.
Kg/m ² ·hr, α was 40.

Claims (1)

[Scope of Claims] 1. Consists of a resin obtained by copolymerizing at least acrylonitrile and/or methacrylonitrile, vinylpyridines, and a crosslinking agent, and the proportion of acrylonitrile and/or methacrylonitrile in the resin is 2 to 30% by weight. % of a quaternary pyridinium-based anion exchange membrane for pervaporation. 2. The separation membrane for pervaporation according to claim 1, wherein the crosslinking agent is divinylbenzene. 3. The separation membrane for pervaporation according to claim 1, wherein the proportion of the crosslinking agent in the resin is 1 to 25% by weight. 4 The proportion of vinylpyridines in the resin is 45% by weight
The separation membrane for pervaporation according to claim 1, which is as described above.