Pervaporation membrane

Abstract

The present invention provides a pervaporation membrane suitable for improving separation performance when separating a volatile organic compound from an aqueous solution containing said organic compound. A pervaporation membrane 10 according to the present invention comprises a separation functional layer 1, the separation functional layer 1 having a porous layer 2 with holes 4, and a skin layer 3 formed on top of the porous layer 2. The pervaporation membrane 20 according to the present invention further comprises a porous support 5 that supports the separation functional layer 1.

Description

pervaporation membrane

[0001] The present invention relates to pervaporation membranes.

[0002] Microbial fermentation is a known method for obtaining valuable non-petroleum-derived materials. For example, a method has been developed for producing volatile organic compounds (fermented products) such as alcohols by fermenting a carbon source such as glucose using microorganisms. The carbon source is fermented, for example, in an aqueous solution. In this method, the microbial fermentation may stop if the content of the fermented product in the aqueous solution increases. To continuously produce the microbial fermented product, it is necessary to separate the fermented product from the aqueous solution.

[0003] One example of a method for separating volatile organic compounds from an aqueous solution containing the organic compounds is pervaporation using a pervaporation membrane. Pervaporation is suitable for separating volatile organic compounds from an aqueous solution containing various substances. Pervaporation also tends to reduce energy consumption and carbon dioxide emissions compared to distillation. Patent Document 1 discloses an example of a pervaporation membrane used in pervaporation.

[0004] Special Publication No. 2005-525224

[0005] When a pervaporation membrane is used to separate volatile organic compounds from an aqueous solution containing the organic compounds, there is a demand for improved separation performance.

[0006] The present invention provides a pervaporation membrane comprising a separation functional layer, the separation functional layer having a porous layer containing pores and a skin layer formed on the porous layer.

[0007] According to the present invention, a pervaporation membrane suitable for improving separation performance when separating volatile organic compounds from an aqueous solution containing the organic compounds can be provided.

[0008] Fig. 1 is a cross-sectional view schematically showing a pervaporation membrane according to one embodiment of the present invention. Fig. 2 is a cross-sectional view schematically showing another example of a pervaporation membrane according to one embodiment of the present invention. Fig. 3 is a schematic cross-sectional view of a membrane separation device including a pervaporation membrane. Fig. 4 is a perspective view schematically showing a modified example of a membrane separation device. Fig. 5 is a schematic configuration diagram showing an example of a membrane separation system.

[0009] A pervaporation membrane according to a first aspect of the present invention includes a separation functional layer, the separation functional layer having a porous layer including pores and a skin layer formed on the porous layer.

[0010] In a second aspect of the present invention, for example, in the pervaporation membrane according to the first aspect, the separation functional layer includes a resin material.

[0011] In a third aspect of the present invention, for example, in the pervaporation membrane according to the second aspect, the resin material is a silicone resin.

[0012] In a fourth aspect of the present invention, for example, in the pervaporation membrane according to any one of the first to third aspects, the pores have an average pore size of 1 nm or more.

[0013] In a fifth aspect of the present invention, for example, in the pervaporation membrane according to any one of the first to fourth aspects, the holes form communicating holes.

[0014] In a sixth aspect of the present invention, for example, in the pervaporation membrane according to any one of the first to fifth aspects, the porosity of the separating functional layer is 10% or more.

[0015] In a seventh aspect of the present invention, for example, the pervaporation membrane according to any one of the first to sixth aspects further comprises a porous support that supports the separating functional layer.

[0016] In an eighth aspect of the present invention, for example, in the pervaporation membrane according to the seventh aspect, the porous support is a fibrous structure.

[0017] In a ninth aspect of the present invention, for example, in the pervaporation membrane according to any one of the first to eighth aspects, the separation functional layer contains a filler.

[0018] In a tenth aspect of the present invention, for example, the pervaporation membrane according to any one of the first to ninth aspects is used to separate volatile organic compounds from an aqueous solution containing the organic compounds.

[0019] In an eleventh aspect of the present invention, for example, in the pervaporation membrane according to the tenth aspect, the organic compound is an alcohol.

[0020] In a twelfth aspect of the present invention, for example, in the pervaporation membrane according to the eleventh aspect, the alcohol is ethanol.

[0021] The present invention will be described in detail below, but the following description is not intended to limit the present invention to a specific embodiment.

[0022] 1 is a cross-sectional view showing a schematic diagram of a pervaporation membrane according to one embodiment of the present invention. The pervaporation membrane 10 of this embodiment includes a separation functional layer 1. The separation functional layer 1 includes a porous layer 2 including pores 4 and a skin layer 3 formed on the porous layer 2.

[0023] The pervaporation membrane of this embodiment is typically a membrane (separation membrane) that preferentially allows organic compounds C to permeate from an aqueous solution S containing volatile organic compounds C. The pervaporation membrane of this embodiment is suitable for improving the separation performance of separating organic compounds C from the aqueous solution S, in particular, the flux of a permeating fluid that permeates the pervaporation membrane.

[0024] (Separation functional layer) The separation functional layer 1 is, for example, a layer that allows preferential permeation of the organic compound C from the above-mentioned aqueous solution S. The separation functional layer 1 has a porous layer 2 and a skin layer 3. The porous layer 2 and the skin layer 3 usually have the same composition.

[0025] Skin layer 3 is typically a dense layer (non-porous layer) in which no pores are visible when observed at a magnification of 20,000 times using a scanning electron microscope (SEM), and is a layer that significantly contributes to the separation performance of pervaporation membrane 10. The thickness of skin layer 3 is not particularly limited and may be, for example, 1 nm or more, 10 nm or more, 50 nm or more, 100 nm or more, or even 1 μm or more. The thickness of skin layer 3 may be, for example, 30 μm or less, 20 μm or less, 10 μm or less, or even 5 μm or less.

[0026] The porous layer 2 is a layer that supports the skin layer 3. The porous layer 2 includes pores 4. The pores 4 included in the porous structure of the porous layer 2 may be closed pores, or two or more pores 4 may be interconnected to form interconnected pores. That is, the porous layer 2 may include at least one selected from the group consisting of interconnected pores and closed pores. In the porous layer 2, a plurality of pores 4 may be interconnected in a three-dimensional manner to form interconnected pores. A configuration in which the pores 4 form interconnected pores can improve the flux of the permeating fluid passing through the pervaporation membrane 10.

[0027] The average pore size of the pores 4 is not particularly limited and may be 1 nm or more, or 10 nm or more. The average pore size of the pores 4 may be 100 μm or less, 50 μm or less, 25 μm or less, or 10 μm or less.

[0028] The average pore size of the pores 4 can be determined, for example, by the following method: First, a cross section of the separation functional layer 1 is observed with a scanning electron microscope. In the obtained electron microscope image, the pore sizes of an arbitrary number (at least 20) of pores 4 are calculated, and the average of the calculated values ​​is regarded as the average pore size.

[0029] The thickness of the porous layer 2 is not particularly limited and may be, for example, 500 μm or less, 300 μm or less, 200 μm or less, or even 100 μm or less. The thickness of the porous layer 2 may be 100 nm or more, 10 μm or more, 30 μm or more, or even 50 μm or more.

[0030] The thickness of the separation functional layer 1 is, for example, 500 μm or less, and may be 300 μm or less, 200 μm or less, 150 μm or less, or even 110 μm or less. The thickness of the separation functional layer 1 may be 100 nm or more, 1 μm or more, 5 μm or more, 10 μm or more, 30 μm or more, or even 50 μm or more.

[0031] The porosity of the separation functional layer 1 may be 10% or more, or may be 20% or more. This configuration can improve the flux of the permeating fluid that permeates the pervaporation membrane 10. The porosity of the separation functional layer 1 may be 90% or less, 70% or less, 60% or less, 50% or less, or even 40% or less. This configuration can achieve a practical strength for the pervaporation membrane 10.

[0032] The porosity of the separation functional layer 1 can be determined, for example, by the following method. At least five locations on the cross section of the separation functional layer 1 are observed using a scanning electron microscope. The magnification is set so that the entire thickness of the separation functional layer 1 is included in the electron microscope image. The area ratio of the pores (pores 4) at each observation location is calculated using the formula: 100 × (total area of ​​pores (pores 4)) / (area of ​​separation functional layer 1), and the average of the calculated values ​​is regarded as the porosity of the separation functional layer 1.

[0033] The separation functional layer 1 preferably contains a resin material, such as a silicone resin, an acrylic resin, a phenolic resin, an epoxy resin, a polyolefin resin, a polyurethane resin, a polyimide resin, or a polyamide resin.

[0034] The resin material is preferably a silicone resin. The silicone resin is formed, for example, from a silicone resin composition. The silicone resin is not particularly limited and may be formed, for example, from a condensation type silicone resin composition, an addition type silicone resin composition, or a UV-curable silicone resin composition, but an addition type silicone resin composition is preferred. An addition type silicone resin composition can be cured using almost no metal species (especially tin) that can promote hydrolysis of the silicone resin. Therefore, the separation functional layer 1 containing a silicone resin formed from an addition type silicone resin composition contains almost no metal species that can promote hydrolysis of the silicone resin and tends to have high durability against the above-mentioned aqueous solution S. The silicone resin may be formed from a solventless silicone resin composition that is substantially free of solvents such as organic solvents.

[0035] [Addition-type silicone resin composition] The addition-type silicone resin composition is a type of silicone resin composition that cures by an addition reaction. The addition-type silicone resin composition contains, for example, a polyorganosiloxane P1 having an alkenyl group and a polyorganosiloxane P2 having a hydrosilyl (SiH) group. It is preferable that the addition-type silicone resin composition further contains a curing catalyst (hydrosilylation catalyst). The addition-type silicone resin composition may be a commercially available silicone resin composition to which a curing catalyst has been added. However, the addition-type silicone resin composition does not necessarily need to contain a curing catalyst.

[0036] The addition-type silicone resin composition can be formed by, for example, heat treatment, whereby the alkenyl groups of the polyorganosiloxane P1 react with the hydrosilyl groups of the polyorganosiloxane P2 (hydrosilylation reaction) to form a silicone resin. In this hydrosilylation reaction, the polyorganosiloxane P2 functions as a crosslinking agent.

[0037] Examples of the alkenyl group of the polyorganosiloxane P1 include a vinyl group and a hexenyl group. The number of alkenyl groups in the polyorganosiloxane P1 is, for example, 2 or more. The alkenyl groups are located, for example, at the terminals of the polyorganosiloxane P1.

[0038] The polyorganosiloxane P1 is, for example, a polyalkylalkylsiloxane such as polydimethylsiloxane (PDMS), polydiethylsiloxane, or polymethylethylsiloxane; a polyalkylarylsiloxane; or a polyorganosiloxane such as poly(dimethylsiloxane-diethylsiloxane) to which an alkenyl group has been introduced.

[0039] The weight-average molecular weight of polyorganosiloxane P1 is, for example, 1,000 or more, and may be 10,000 or more, 100,000 or more, 200,000 or more, 300,000 or more, or even 400,000 or more. The larger the weight-average molecular weight of polyorganosiloxane P1, the more likely it is that the separation characteristics of pervaporation membrane 10 will improve. The upper limit of the weight-average molecular weight of polyorganosiloxane P1 is not particularly limited and is, for example, 1,000,000.

[0040] The number of hydrosilyl groups in the polyorganosiloxane P2 is, for example, at least 2. The hydrosilyl groups may be located at the terminals of the polyorganosiloxane P2 or may be contained in the main chain of the polyorganosiloxane P2.

[0041] Examples of the polyorganosiloxane P2 include polymethylhydrogensiloxane, poly(dimethylsiloxane-methylhydrogensiloxane), and hydrosilyl-terminated polydimethylsiloxane.

[0042] The weight-average molecular weight of polyorganosiloxane P2 is, for example, 100 or more, and may be 10,000 or more. The larger the weight-average molecular weight of polyorganosiloxane P2, the more likely it is that the separation characteristics of pervaporation membrane 10 will improve. The upper limit of the weight-average molecular weight of polyorganosiloxane P2 is not particularly limited and is, for example, 1,000,000.

[0043] The weight ratio P2 / P1 of polyorganosiloxane P2 to polyorganosiloxane P1 is, for example, 500 wt% or less, 100 wt% or less, 50 wt% or less, 20 wt% or less, 10 wt% or less, or even 5 wt% or less. The lower limit of the weight ratio P2 / P1 is, for example, 0.01 wt% or more.

[0044] Examples of the curing catalyst include platinum-based catalysts. In other words, the addition-type silicone resin composition may contain a curing catalyst having platinum. Specific examples of platinum-based catalysts include chloroplatinic acid, platinum olefin complexes, and chloroplatinic acid olefin complexes. As described above, the addition-type silicone resin composition may not contain a curing catalyst.

[0045] The addition-type silicone resin composition may contain a compound that generates catalytically active species that catalyze the addition reaction when irradiated with active energy rays such as ultraviolet (UV) rays. With an addition-type silicone resin composition containing this compound, the addition reaction can be promoted by, for example, UV irradiation.

[0046] The addition type silicone resin composition may further contain an organic solvent in addition to the above-mentioned components. Examples of the organic solvent include hydrocarbon solvents such as cyclohexane, n-hexane, and n-heptane; aromatic solvents such as toluene and xylene; ester solvents such as ethyl acetate and methyl acetate; ketone solvents such as acetone and methyl ethyl ketone; and alcohol solvents such as methanol, ethanol, and butanol. The organic solvent may be used alone or in combination of two or more. The addition type silicone resin composition may be a solventless type that does not substantially contain a solvent such as an organic solvent.

[0047] [Condensation Type Silicone Resin Composition] The condensation type silicone resin composition is a type of silicone resin composition that cures by a condensation reaction. The condensation type silicone resin composition contains, for example, a polyorganosiloxane P3 having a silanol (SiOH) group and a silane compound P4 having a functional group such as an alkoxy group, an alkenyloxy group, an acyloxy group, an amino group, a ketoxime group, or an amide group. The condensation type silicone resin composition may or may not further contain a curing catalyst. The condensation type silicone resin composition may also be a commercially available silicone resin composition to which a curing catalyst has been added.

[0048] The condensation type silicone resin composition can be formed by, for example, heat treatment, whereby the silanol groups of the polyorganosiloxane P3 react with the functional groups of the silane compound P4 (condensation reaction), in which the silane compound P4 functions as a crosslinking agent.

[0049] The number of silanol groups in polyorganosiloxane P3 is, for example, 2 or more. The silanol groups are located, for example, at the terminals of polyorganosiloxane P3. Polyorganosiloxane P3 may have an alkyl group such as a methyl group or an ethyl group, or a phenyl group introduced as a substituent on the side chain.

[0050] The polyorganosiloxane P3 is, for example, a polyorganosiloxane in which silanol groups have been introduced into the polyorganosiloxane described above for the polyorganosiloxane P1.

[0051] The weight average molecular weight of polyorganosiloxane P3 is, for example, 1000 or more, and may be 10,000 or more, 100,000 or more, 200,000 or more, 300,000 or more, or even 400,000 or more. The upper limit of the weight average molecular weight of polyorganosiloxane P3 is not particularly limited and is, for example, 1,000,000.

[0052] As described above, the silane compound P4 has functional groups such as alkoxy groups, alkenyloxy groups, acyloxy groups, amino groups, ketoxime groups, and amide groups. Examples of alkoxy groups include methoxy groups and ethoxy groups. Examples of alkenyloxy groups include isopropenyloxy groups. Examples of acyloxy groups include acetoxy groups. Examples of amino groups include dimethylamino groups, diethylamino groups, and ethylmethylamino groups. Examples of ketoxime groups include acetoxime groups and methylethylketoxime groups. Examples of amide groups include acetamide groups, N-methylacetamide groups, and N-ethylacetamide groups. The number of functional groups in the silane compound P4 is, for example, two or more. In particular, it is preferable that the silane compound P4 contains an alkoxysilyl group as the alkoxy group.

[0053] The silane compound P4 may be a low molecular weight compound having a molecular weight of about 1000 or less, or may be a high molecular weight compound having a polysiloxane skeleton.

[0054] Examples of the curing catalyst include tin-based catalysts, such as organotin catalysts such as dibutyltin dilaurate, dibutyltin diacetate, and dibutyltin dioctate.

[0055] The condensation type silicone resin composition may further contain an organic solvent in addition to the above-mentioned components. Examples of the organic solvent include those described above for the addition type silicone resin composition. The condensation type silicone resin composition may be a solventless type that does not contain a solvent such as an organic solvent.

[0056] [UV-Curable Silicone Resin Composition] A UV-curable silicone resin composition is a type of silicone resin composition that cures upon exposure to ultraviolet (UV) light. In UV-curable silicone resin compositions, the curing reaction proceeds, for example, by radical polymerization, radical addition, ionic polymerization, or the like. A UV-curable silicone resin composition in which the curing reaction proceeds by radical polymerization includes, for example, polyorganosiloxane P5 having a double bond (specifically, a carbon-carbon double bond) derived from an alkenyl group, an acryloyl group, or the like. A UV-curable silicone resin composition in which the curing reaction proceeds by radical addition includes, for example, polyorganosiloxane P5 having a double bond (specifically, a carbon-carbon double bond) derived from an alkenyl group, an acryloyl group, or the like, and compound P6 having a functional group capable of radical addition, such as a thiol group. A UV-curable silicone resin composition in which the curing reaction proceeds by ionic polymerization includes, for example, polyorganosiloxane P7 having a functional group capable of ion polymerization, such as an epoxy group, and a compound that generates catalytically active species that catalyze ionic polymerization upon UV exposure.

[0057] According to a UV-curable silicone resin composition in which the curing reaction proceeds by radical polymerization, for example, upon UV irradiation, a radical polymerization reaction proceeds between double bonds contained in the alkenyl groups, acryloyl groups, etc. of the polyorganosiloxane P5, thereby forming a silicone resin.

[0058] Examples of the alkenyl group of polyorganosiloxane P5 include vinyl groups and hexenyl groups. The number of alkenyl groups in polyorganosiloxane P5 is, for example, 2 or more. The alkenyl groups are located, for example, at the terminals of polyorganosiloxane P5. Polyorganosiloxane P5 may have alkyl groups such as methyl groups and ethyl groups, or phenyl groups introduced as side chain substituents.

[0059] The polyorganosiloxane P5 is, for example, a polyorganosiloxane in which a substituent having a double bond, such as an alkenyl group or an acryloyl group, has been introduced into the polyorganosiloxane described above for the polyorganosiloxane P1.

[0060] The weight average molecular weight of polyorganosiloxane P5 is, for example, 1000 or more, and may be 10,000 or more, 100,000 or more, 200,000 or more, 300,000 or more, or even 400,000 or more. The upper limit of the weight average molecular weight of polyorganosiloxane P5 is not particularly limited and is, for example, 1,000,000.

[0061] In a UV-curable silicone resin composition in which the curing reaction proceeds by radical addition, for example, upon UV irradiation, a functional group capable of radical addition contained in compound P6 undergoes radical addition to a double bond contained in an alkenyl group or acryloyl group of polyorganosiloxane P5, thereby proceeding with the radical addition reaction to form a silicone resin.

[0062] In compound P6, functional groups capable of radical addition include, for example, a thiol group, an alkylthiol group, etc. Examples of alkylthiol groups include a mercaptomethyl group, a mercaptoethyl group, etc. The number of functional groups capable of radical addition in compound P6 is, for example, two or more.

[0063] Compound P6 may be a polyorganosiloxane containing a functional group capable of radical addition. The functional group may be located, for example, at the terminal of the polyorganosiloxane. The polyorganosiloxane may have an alkyl group such as a methyl group or an ethyl group, or a phenyl group introduced as a substituent on the side chain.

[0064] Compound P6 is, for example, a polyorganosiloxane as described above for polyorganosiloxane P1 to which a functional group capable of radical addition, such as a thiol group, has been introduced.

[0065] The weight-average molecular weight of compound P6 is, for example, 1,000 or more, and may be 10,000 or more, 100,000 or more, 200,000 or more, 300,000 or more, or even 400,000 or more. The upper limit of the weight-average molecular weight of compound P6 is not particularly limited, and is, for example, 1,000,000.

[0066] In the UV-curable silicone resin composition in which the curing reaction proceeds by ionic polymerization, for example, catalytically active species that catalyze ionic polymerization are generated by UV irradiation, and ionic polymerization reaction proceeds between functional groups capable of ionic polymerization contained in polyorganosiloxane P7, thereby forming a silicone resin.

[0067] In polyorganosiloxane P7, the functional group capable of ion polymerization is, for example, an epoxy group. Examples of substituents containing an epoxy group include the epoxy group itself, a glycidyl group, and a glycidyloxypropyl group. The number of functional groups capable of ion polymerization in polyorganosiloxane P7 is, for example, two or more. The functional group capable of ion polymerization is located, for example, at the end of polyorganosiloxane P7. Polyorganosiloxane P7 may have an alkyl group such as a methyl group or an ethyl group, or a phenyl group introduced as a side chain substituent.

[0068] Polyorganosiloxane P7 is, for example, the polyorganosiloxane described above for polyorganosiloxane P1 to which a functional group capable of ionic polymerization, such as an epoxy group, has been introduced.

[0069] The weight average molecular weight of polyorganosiloxane P7 is, for example, 1000 or more, and may be 10,000 or more, 100,000 or more, 200,000 or more, 300,000 or more, or even 400,000 or more. The upper limit of the weight average molecular weight of polyorganosiloxane P7 is not particularly limited and is, for example, 1,000,000.

[0070] The UV-curable silicone resin composition may further contain an organic solvent in addition to the above-mentioned components. Examples of the organic solvent include hydrocarbon solvents such as cyclohexane, n-hexane, and n-heptane; aromatic solvents such as toluene and xylene; ester solvents such as ethyl acetate and methyl acetate; ketone solvents such as acetone and methyl ethyl ketone; and alcohol solvents such as methanol, ethanol, and butanol. The organic solvent may be used alone or in combination of two or more. The UV-curable silicone resin composition may be a solvent-free type that does not substantially contain a solvent such as an organic solvent.

[0071] The separation functional layer 1 may contain a silicone resin as a main component, or may be composed essentially of a silicone resin. The "main component" refers to the component that is contained in the separation functional layer 1 in the largest amount by weight.

[0072] The separation functional layer 1 may further include a filler. For example, the separation functional layer 1 may have a matrix containing a silicone resin and a filler dispersed in the matrix. In this form, all or part of the filler is embedded in the matrix in the separation functional layer 1. Within the matrix, all of the fillers may be spaced apart from one another, or may be partially aggregated.

[0073] The filler includes an inorganic material such as zeolite, silica, or bentonite. The filler includes, for example, at least one selected from the group consisting of zeolite and silica, and preferably includes silica. Fillers containing silica tend to have better hydrolysis resistance than fillers containing zeolite. Furthermore, fillers containing silica tend to increase the free volume of the resin (particularly silicone resin) contained in the matrix. Increasing the free volume of the resin tends to improve the separation characteristics of the pervaporation membrane 10, particularly the separation coefficient α of ethanol relative to water. The filler allows the viscosity of the resin composition to be appropriately adjusted, which tends to make it easier to prepare a resin composition suitable for coating.

[0074] Silica usually means silicon dioxide. The filler may be a silica filler containing silicon dioxide as a main component. For example, the silica filler does not have a crystalline structure. For example, the silica filler can be prepared by reacting metal silicon with oxygen. The silica filler can also be prepared by a sol-gel method, a precipitation method, an aqueous solution wet method, or the like. The filler may be substantially composed of silicon dioxide only.

[0075] However, the filler may contain zeolite. Examples of zeolite contained in the filler include high-silica zeolite, which has a high ratio of silica to alumina, and silicalite, which does not contain alumina. Examples of fillers containing high-silica zeolite include HSZ (registered trademark) manufactured by Tosoh Corporation, HiSiv (registered trademark) manufactured by Union Showa Corporation, USKY (registered trademark) manufactured by Union Showa Corporation, and Zeoal (registered trademark) manufactured by Nakamura Choukou Co., Ltd.

[0076] The filler, particularly the silica filler, does not have micropores with a diameter of, for example, 2 nm or less, whereas the filler may have mesopores with a diameter of 2 nm to 50 nm and macropores with a diameter of 50 nm or more.

[0077] The filler, particularly the silica filler, preferably has a surface modified with a modifying group containing a hydrocarbon group. In other words, the filler is preferably surface-modified with a modifying group. The surface-modified filler has high dispersibility in the resin and is suitable for suppressing the occurrence of cracks during the production of the separation functional layer 1.

[0078] The number of carbon atoms in the hydrocarbon group contained in the modifying group is not particularly limited and is, for example, 1 to 25. The number of carbon atoms in the hydrocarbon group may be 5 or less. The hydrocarbon group may be linear, branched, or cyclic. Examples of the hydrocarbon group include alkyl groups such as methyl and ethyl groups.

[0079] The modifying group may further contain a silicon atom, and a hydrocarbon group may be bonded to the silicon atom. The modifying group may contain at least one selected from the group consisting of an organosilyl group and a polyorganosiloxane group. Examples of the organosilyl group include triorganosilyl groups such as trimethylsilyl groups and diorganosilyl groups such as dimethylsilyl groups. Examples of the polyorganosiloxane group include dimethylpolysiloxane groups.

[0080] The surface modification with the modifying group can be carried out, for example, by reacting the hydroxyl groups present on the surface of the filler with a known silane coupling agent.

[0081] Specific examples of surface-modified silica fillers include those available under the trade names "AEROSIL (registered trademark) RX series" (RX50, RX200, RX300, etc.), "AEROSIL (registered trademark) RY series" (RY50, RY200, RY200S, etc.), "AEROSIL (registered trademark) NY series" (NY50, NY50L, etc.), "AEROSIL (registered trademark) NAX series" (NAX50, etc.), and "AEROSIL (registered trademark) R series" (R972, R974, R976, etc.), all of which are manufactured by Nippon Aerosil Co., Ltd.

[0082] From the viewpoint of dispersibility in the resin, it is preferable that the filler be sufficiently surface-modified with a modifying group. In other words, it is preferable that the number of hydroxyl groups present on the surface of the filler is small. Whether the filler is sufficiently surface-modified with a modifying group can be determined, for example, from the pH of the filler dispersion or the Hansen solubility parameter (HSP value) of the filler. The Hansen solubility parameter is the solubility parameter introduced by Hildebrand, divided into three components: a dispersion term δD, a polarization term δP, and a hydrogen bonding term δH. Details of the Hansen solubility parameter are disclosed in, for example, "Hansen Solubility Parameters; A Users Handbook (CRC Press, 2007)."

[0083] In this embodiment, the pH of the filler dispersion measured by the following test is, for example, 4.0 to 9.0, and may be 6.0 to 8.0. The pH of the dispersion is preferably neutral (around pH 7.0). When the pH of the dispersion is neutral, it can be said that the filler has been sufficiently surface-modified with modifying groups, and the number of hydroxyl groups present on the surface is small. Test: A dispersion is prepared by mixing water, methanol, and filler, and the pH of the dispersion is measured. Here, the filler content in the dispersion is 4 wt %, the weight ratio of water to methanol is 1:1, and the temperature of the dispersion is 25°C.

[0084] The shape of the filler is, for example, particulate. In this specification, "particulate" includes spherical, ellipsoidal, scaly, and fibrous shapes. The filler may be powdery. The average particle size of the filler is not particularly limited and may be, for example, 50 μm or less, 20 μm or less, 10 μm or less, 1 μm or less, 500 nm or less, 100 nm or less, 50 nm or less, 30 nm or less, or even 20 nm or less. According to the above configuration, the filler is less likely to detach from the separation functional layer 1. Furthermore, a separation functional layer 1 containing a filler with a small average particle size is more likely to disperse stress applied to the separation functional layer 1 and tends to have high adhesion to, for example, the porous support described below. The lower limit of the average particle size of the filler is not particularly limited and is, for example, 1 nm. The average particle size of the filler may be 5 nm or more, or may be 10 nm or more. In this specification, the average particle size refers to the primary particle size.

[0085] The average particle size of the filler can be determined, for example, by the following method. First, a cross section of the separation functional layer 1 is observed with a transmission electron microscope. In the obtained electron microscope image, the area of ​​a specific filler is calculated by image processing. The diameter of a circle having the same area as the calculated area is regarded as the particle size (particle diameter) of that specific filler. The particle sizes of an arbitrary number (at least 50) of fillers are calculated, and the average of the calculated values ​​is regarded as the average particle size of the filler.

[0086] The filler content in the separation functional layer 1 may be, for example, 1 wt% or more, 5 wt% or more, 10 wt% or more, 20 wt% or more, 30 wt% or more, or even 40 wt% or more. The upper limit of the filler content in the separation functional layer 1 is not particularly limited and may be, for example, 50 wt% or less, or 20 wt% or less. When the filler content is 50 wt% or less, a decrease in the flux of the permeating fluid passing through the pervaporation membrane 10 can be prevented. In addition, there is a tendency for the occurrence of defects such as cracks to be sufficiently suppressed during the production of the separation functional layer 1. The filler content in the separation functional layer 1 may be 1 wt% or more and 50 wt% or less, or 5 wt% or more and 20 wt% or less.

[0087] The content of the matrix in the separation functional layer 1 is not particularly limited, and may be, for example, 30 wt % to 99 wt %, or may be 30 wt % to 90 wt %.

[0088] The surface area D1 of the filler per weight of the matrix is ​​not particularly limited, and may be, for example, 5 m 2 / g or more, and 2 / g or more, 20m 2 / g or more, 30m 2 / g or more, 40m 2 / g or more, even 50m 2 The upper limit of the surface area D1 is not particularly limited, and may be, for example, 100 m 2 The surface area D1 is the BET specific surface area D2 (m 2 / g), the weight W1 (g) of the matrix contained in the separation functional layer 1, and the weight W2 (g) of the filler contained in the separation functional layer 1, the D1(m 2 / g) = D2(m 2 / g)×W2(g) / W1(g)

[0089] (Porous Support) As shown in Fig. 2, the pervaporation membrane of this embodiment preferably further includes a porous support 5. The porous support 5 supports the separation function layer 1. In the pervaporation membrane 20 shown in Fig. 2, the surface of the porous layer 2 in the separation function layer 1 is in direct contact with the porous support 5, and the surface of the skin layer 3 forms the surface of the pervaporation membrane 20.

[0090] The pervaporation membrane 20 of this embodiment is composed of, for example, only the separating functional layer 1 and the porous support 5 .

[0091] In this embodiment, the porous support 5 may have only a main body portion and may not have a microporous layer. The porous support 5 is preferably a fibrous structure. Examples of the fibrous structure include a woven fabric, a nonwoven fabric, and a stretched porous membrane containing fibrils. The fibrous structure is typically a nonwoven fabric or a stretched porous membrane. As a result, the flux of the permeating fluid passing through the pervaporation membrane 20 can be improved.

[0092] When the fiber structure is a woven fabric or a nonwoven fabric, examples of the fibers contained in the fiber structure include natural fibers such as wood pulp, cotton, and hemp (e.g., Manila hemp); and chemical fibers (synthetic fibers) such as polyester fiber, rayon, vinylon, acetate fiber, polyvinyl alcohol (PVA) fiber, polyamide fiber, polyolefin fiber, and polyurethane fiber. The porous support 5 is, for example, a nonwoven fabric made of polyester fiber. Examples of the nonwoven fabric include polyethylene terephthalate (PET) nonwoven fabric and polyphenylene sulfide (PPS) nonwoven fabric.

[0093] When the fibrous structure is an expanded porous membrane, the fibrous structure preferably contains a fluororesin, such as polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), perfluoroalkoxy fluororesin (PFA), and tetrafluoroethylene-hexafluoropropylene copolymer (FEP), with PTFE being preferred.

[0094] For example, expanded porous PTFE membranes are formed by expanding paste extrusions or cast membranes containing PTFE particles. Expanded porous PTFE membranes are composed of fine PTFE fibrils and may have nodes where the PTFE is in a more aggregated state than the fibrils.

[0095] The porous support body 5 (main body) has an average pore size of, for example, 1 μm to 50 μm.

[0096] In some cases, the porous support 5 may include a main body portion and a microporous layer disposed on the main body portion. In the pervaporation membrane 10, the microporous layer is located between the main body portion of the porous support 5 and the separation functional layer 1.

[0097] Examples of materials for the microporous layer include fluororesins such as polyvinylidene fluoride and polytetrafluoroethylene, polyarylethersulfones such as polysulfone and polyethersulfone, and polyimides. The microporous layer has an average pore size of, for example, 0.01 μm to 0.4 μm.

[0098] The thickness of the porous support 5 is not particularly limited and may be, for example, 10 μm or more, 50 μm or more, or even 100 μm or more. The thickness of the porous support 5 is, for example, 300 μm or less, or may be 200 μm or less.

[0099] In this embodiment, the separation function layer 1 is in direct contact with, for example, a fiber structure (specifically, a nonwoven fabric). When the porous support 5 includes a main body and a microporous layer, the separation function layer 1 is in direct contact with the microporous layer.

[0100] The surface of the porous support 5 that comes into contact with the separating functional layer 1 may be subjected to an adhesion-facilitating treatment. Examples of the adhesion-facilitating treatment include surface treatments such as corona discharge treatment and plasma treatment.

[0101] The adhesion-facilitating treatment may also be a treatment involving the application of a molecular bonding agent. The molecular bonding agent contains a molecular bonding compound (hereinafter referred to as "compound C1") and, if necessary, a solvent such as an organic solvent or water. Compound C1 has a reactive group F1 capable of reacting with the surface of the porous support 5 and a reactive group F2 capable of reacting with a resin (particularly a silicone resin) contained in the separation functional layer 1. The reactive group F2 may be capable of reacting not only with the silicone resin but also with the surface of the porous support 5.

[0102] The reactive group F1 is, for example, at least one selected from the group consisting of an amino group, an azide group, a mercapto group, an isocyanate group, a ureido group, and an epoxy group, and is typically an azide group. The reactive group F2 is, for example, at least one selected from the group consisting of a silanol group and a group G that generates a silanol group by hydrolysis. A specific example of the group G is an alkoxysilyl group.

[0103] Compound C1 is represented, for example, by the following formula (1): A -Z-R B (1)

[0104] In formula (1), R A represents a reactive group F1 or a monovalent substituent having one or more reactive groups F1, and R B represents a reactive group F2, and Z represents a divalent organic group.

[0105] In formula (1), examples of Z include an alkylene group having 1 to 20 carbon atoms which may have a substituent, an alkenylene group having 2 to 20 carbon atoms which may have a substituent, an alkynylene group having 2 to 20 carbon atoms which may have a substituent, and an arylene group having 6 to 20 carbon atoms which may have a substituent.

[0106] Examples of alkylene groups having 1 to 20 carbon atoms include methylene, ethylene, propylene, trimethylene, tetramethylene, pentamethylene, and hexamethylene groups, with methylene, ethylene, and propylene being preferred, and propylene being more preferred. Examples of alkenylene groups having 2 to 20 carbon atoms include vinylene, propenylene, butenylene, and pentenylene groups. Examples of alkynylene groups having 2 to 20 carbon atoms include ethynylene and propynylene groups. Examples of arylene groups having 6 to 20 carbon atoms include o-phenylene, m-phenylene, p-phenylene, 2,6-naphthylene, and 1,5-naphthylene groups.

[0107] Examples of the substituent that the alkylene group, alkenylene group, and alkynylene group may have include halogen atoms such as a fluorine atom and a chlorine atom; alkoxy groups such as a methoxy group and an ethoxy group; alkylthio groups such as a methylthio group and an ethylthio group; and alkoxycarbonyl groups such as a methoxycarbonyl group and an ethoxycarbonyl group.

[0108] Examples of the substituent that the arylene group may have include a cyano group; a nitro group; a halogen atom such as a fluorine atom, a chlorine atom, or a bromine atom; an alkyl group such as a methyl group or an ethyl group; an alkoxy group such as a methoxy group or an ethoxy group; and an alkylthio group such as a methylthio group or an ethylthio group.

[0109] The above-mentioned substituents may be bonded to any position in the alkylene group, alkenylene group, alkynylene group, arylene group, or other group, and a plurality of substituents may be bonded to the same element or different elements.

[0110] R A Examples of the group include groups represented by the following formulas (2) to (4).

[0111] In formulas (2) to (4), * represents a bond to Z in formula (1). 1 represents a divalent hydrocarbon group having 1 to 10 carbon atoms. 2 and R 3 R each independently represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. 4 and R 5 each independently represents a reactive group F1 or a group represented by the above formula (2). 4 and R 5 When R is a group represented by formula (2), * in formula (2) represents a bond to a carbon atom constituting a triazine ring in formula (4). 6 is a single bond or -N(R 7 )- represents a divalent group. 7 represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms.

[0112] In formula (2), R 1 is preferably a divalent hydrocarbon group having 2 to 6 carbon atoms. 1 Examples of the alkylene group include alkylene groups or arylene groups having 1 to 10 carbon atoms, and specific examples include alkylene groups such as an ethylene group and a trimethylene group; and arylene groups such as an o-phenylene group, an m-phenylene group, and a p-phenylene group.

[0113] In formula (2), R 2 and R 3 are each independently preferably a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms. 2 and R 3Examples of the alkyl group include alkyl groups, alkynyl groups, and aryl groups having 1 to 20 carbon atoms, and specific examples thereof include alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl group, t-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, and n-decyl group; alkenyl groups such as vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 3-butenyl group, 4-pentenyl group, and 5-hexenyl group; alkynyl groups such as ethynyl group, propargyl group, and butynyl group; and aryl groups such as phenyl group, 1-naphthyl group, and 2-naphthyl group.

[0114] In formula (4), R 4 and R 5 are preferably the same reactive group F1.

[0115] In formula (4), R 6 is a single bond or -N(R 7 )- represents a divalent group. 7 The hydrocarbon group of the above R 2 and R 3 Examples of the hydrocarbon group of R include the same as those mentioned above. 6 Preferably, represents —NH—.

[0116] R A is preferably a group represented by formula (4) among the groups represented by formulas (2) to (4), and is a group represented by formula (4) and R 4 or R 5 is more preferably an azide group or a group represented by the above formula (2).

[0117] R A Examples of the group include a group represented by the following formula (5).

[0118] In formula (5), * represents a bond to Z in formula (1). 1 ~R 3 and R 6 are the same as those described above for equations (2) and (4), respectively. 1 ~R 3may be the same or different.

[0119] In formula (1), R B may be a group represented by the following formula (6): —Si(X) a (Y) 3-a (6)

[0120] In formula (6), X represents a hydroxy group or an alkoxy group having 1 to 10 carbon atoms, Y represents a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 3.

[0121] In formula (6), X is, for example, a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, etc., and an ethoxy group is preferable. 2 and R 3 Examples of the hydrocarbon group include those mentioned above.

[0122] R B In the formula (I), X is preferably a hydroxy group or an alkoxy group having 1 to 10 carbon atoms and a is 3, and more preferably X is a hydroxy group or an ethoxy group and a is 3.

[0123] R A is an amino group, examples of the compound C1 include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldimethoxymethylsilane, 3-aminopropyldiethoxymethylsilane, [3-(N,N-dimethylamino)propyl]trimethoxysilane, [3-(phenylamino)propyl]trimethoxysilane, trimethyl[3-(triethoxysilyl)propyl]ammonium chloride, and trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride.

[0124] R A Examples of the compound C1 in which is an azido group include (11-azidoundecyl)trimethoxysilane and (11-azidoundecyl)triethoxysilane.

[0125] R AExamples of the compound C1 in which is a mercapto group include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropyldimethoxymethylsilane.

[0126] R A Examples of the compound C1 in which is an isocyanate group include 3-(trimethoxysilyl)propyl isocyanate and 3-(triethoxysilyl)propyl isocyanate.

[0127] R A Examples of the compound C1 in which is a ureido group include 3-ureidopropyltrimethoxysilane and 3-ureidopropyltriethoxysilane.

[0128] R A Examples of the compound C1 in which is an epoxy group include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 3-glycidoxypropylmethyldiethoxysilane.

[0129] R A is a monovalent substituent having one or more reactive groups F1, examples of the compound C1 include 3-(2-aminoethylamino)propyltrimethoxysilane, 3-(2-aminoethylamino)propyltriethoxysilane, 3-(2-aminoethylamino)propyldimethoxymethylsilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and compounds represented by the following formulas (1-1) to (1-9).

[0130]

[0131] (1-1): N,N'-bis(2-aminoethyl)-6-(3-trihydroxysilylpropyl)amino-1,3,5-triazine-2,4-diamine (1-2): N,N'-bis(2-aminoethyl)-6-(3-trimethoxysilylpropyl)amino-1,3,5-triazine-2,4-diamine (1-3): N,N'-bis(2-aminoethyl)-6-(3-triethoxysilylpropyl)amino-1,3,5-triazine-2,4-diamine (1-4): N,N'-bis(2-aminomethyl)-6-(3-trihydroxysilylpropyl)amino-1,3,5-triazine-2,4-diamine (1-5): N,N'-bis(2-aminomethyl)-6-(3-trimethoxysilylpropyl)amino-1,3,5-triazine-2,4-diamine (1-6): N,N'-bis(2-aminomethyl)-6-(3-triethoxysilylpropyl)amino-1,3,5-triazine-2,4-diamine (1-7): 6-(3-trihydroxysilylpropyl)amino-1,3,5-triazine-2,4-diazide (1-8): 6-(3-trimethoxysilylpropyl)amino-1,3,5-triazine-2,4-diazide (1-9): 6-(3-triethoxysilylpropyl)amino-1,3,5-triazine-2,4-diazide

[0132] Compound C1 is preferably a compound represented by the above formulas (1-1) to (1-9), and more preferably a compound represented by formula (1-1) or formula (1-9).

[0133] The pervaporation membrane 20 may further include an intermediate layer disposed between the separating functional layer 1 and the porous support 5. The intermediate layer is typically formed from a pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition may be a composition containing a silicone-based polymer (a silicone-based pressure-sensitive adhesive).

[0134] The pervaporation membrane according to this embodiment does not necessarily have to include the porous support 5 .

[0135] (Method for manufacturing pervaporation membrane) The pervaporation membrane 10 can be produced, for example, by the following method. First, a coating liquid L is prepared that contains at least the material of the separation functional layer 1 and a dispersoid or foaming agent that disperses the material as a dispersion medium. The dispersoid is, for example, water or a hydrophilic compound. After the coating liquid L is applied to form a coating film, the coating film is cured. The separation functional layer 1 can be obtained by removing the dispersoid from the coating film or foaming the foaming agent.

[0136] The material of the separation functional layer 1 is typically a silicone resin composition.

[0137] The proportion of the silicone resin composition in the coating liquid L may be 20 wt % or more, 30 wt % or more, or even 40 wt % or more. The proportion of the silicone resin composition in the coating liquid L may be 70 wt % or less, 60 wt % or less, or even 50 wt % or less.

[0138] In a preferred embodiment of the method for producing a pervaporation membrane according to this embodiment, the coating liquid L contains water as a dispersoid. The coating liquid L is, for example, an emulsion in which water is dispersed in a silicone resin composition.

[0139] The coating liquid L may further contain additives, preferably inorganic thickeners and surfactants.

[0140] The inorganic thickener is added to increase the viscosity of water, facilitate the dispersion of water in the silicone resin composition, and stabilize the dispersion state. Examples of inorganic thickeners include natural or synthetic smectite clays such as bentonite, montmorillonite, hectorite, saponite, sauconite, beidellite, and nontronite; aluminum magnesium silicate; and composites of these with water-soluble organic polymers such as carboxyvinyl polymers. Preferred are smectite clays such as bentonite and montmorillonite. Examples of smectite clays commercially available include Sumecton SA (manufactured by Kunimine Industries), a hydrothermal synthesis product, and Bengel (manufactured by Hojun), a natural refined product. The content of the inorganic thickener is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, per 100 parts by mass of water.

[0141] The total mass ratio of water and inorganic thickener in the coating liquid L may be 30 wt % or more, 40 wt % or more, or even 50 wt % or more. The total mass ratio of water and inorganic thickener in the coating liquid L may be 80 wt % or less, 70 wt % or less, or even 60 wt % or less.

[0142] The surfactant typically includes a nonionic surfactant, and examples of the surfactant include glycerin fatty acid esters, polyglycerin fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, polyethylene glycol fatty acid esters, polypropylene glycol fatty acid esters, polyoxyethylene glycerin fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene-polyoxypropylene block copolymers, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, and polyoxyethylene fatty acid amides.

[0143] The surfactant preferably consists solely of a nonionic surfactant. According to the above-described configuration, water can be stably dispersed in the silicone resin composition, and a separation functional layer 1 having uniform and fine continuous pores can be formed. The coating liquid L may contain two or more surfactants, or may contain two or more nonionic surfactants.

[0144] The ratio of the surfactant to the silicone resin composition in the coating liquid L may be 0.1 wt % or more and 15 wt % or less, or may be 0.2 wt % or more and 3 wt % or less.

[0145] For example, the coating liquid L is prepared by emulsifying a water dispersion containing an inorganic thickener, the material for the separation functional layer 1 (specifically, a silicone resin composition), and a surfactant. The coating liquid L is applied to a substrate A to form a coating film. Then, a substrate B is placed on the surface of the coating film opposite the substrate A. The coating film is then cured (pre-cured). After removing one substrate (e.g., substrate B), the coating film is further cured (mainly cured), for example, by heating and drying, and the dispersoid is removed from the coating film. The separation functional layer 1 can then be obtained by removing the other substrate (e.g., substrate A). The separation functional layer 1 produced by the above method typically has an opening on the surface facing the porous layer 2, and the pores 4 form interconnected pores. The interconnected pores typically communicate with the openings.

[0146] The pre-curing of the coating film can be carried out at room temperature or in a heated environment. The pre-curing of the coating film can also be carried out by irradiation with active energy rays such as UV rays.

[0147] When the coating film is cured by heating, the heating conditions for pre-curing are not particularly limited. For example, the heating temperature of the coating film may be 50° C. or higher, 60° C. or higher, 70° C. or higher, or even 80° C. or higher. The upper limit of the heating temperature of the coating film in pre-curing is, for example, 110° C.

[0148] After removing one of the substrates A or B, the coating film is further heated and dried to volatilize water from the coating film and fully cure the resin composition in the coating film. The heating temperature at this time may be, for example, 100°C or higher, 120°C or higher, 130°C or higher, or even 150°C or higher. The higher the heating temperature of the coating film, the more sufficiently the curing reaction of the components in the resin composition progresses. The upper limit of the heating and drying temperature of the coating film is not particularly limited, and is, for example, 250°C. The heating and drying time can be appropriately adjusted depending on the composition of the resin composition used.

[0149] The substrates A and B are, for example, release liners. Examples of release liners include films containing resin; paper; and sheets containing metal materials such as aluminum and stainless steel. Sheets containing metal materials tend to have high heat resistance. The release liner is preferably a film containing resin because it has excellent surface smoothness. In the release liner, examples of polymers contained in the resin include polyolefins such as polyethylene, polypropylene, polybutene, polybutadiene, and polymethylpentene; polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyvinyl chloride, vinyl chloride copolymers; polyurethanes; and ethylene-vinyl acetate copolymers, with polyesters, particularly polyethylene terephthalate, being preferred.

[0150] The surface of the release liner may be subjected to a release treatment. The release treatment can be carried out, for example, by applying a release treatment agent to the surface of the release liner. Examples of release treatment agents include silicone-based release treatment agents, long-chain alkyl-based release treatment agents, fluorine-containing release treatment agents, and molybdenum sulfide-based release treatment agents. The release treatment agents may be used alone or in combination of two or more. The release liner is preferably a film made of polyethylene terephthalate (PET) that has been subjected to a release treatment.

[0151] The thickness of the release liner is not particularly limited, and is, for example, 5 to 100 μm, and preferably 10 to 50 μm.

[0152] In another preferred embodiment of the method for manufacturing a pervaporation membrane according to this embodiment, the coating liquid L contains a hydrophilic compound as a dispersoid. The hydrophilic compound is, for example, a polyether or a polyol, preferably polyethylene glycol (PEG) or glycerin. In this case, the coating liquid L does not need to contain an inorganic thickener or a surfactant.

[0153] For example, a coating liquid L containing PEG or glycerin dispersed in a material for the separation functional layer 1 (specifically, a silicone resin composition) is applied to a substrate A to form a coating film. Then, a substrate B is placed on the surface of the coating film opposite the substrate A. The coating film is then cured, and the coating film from which one substrate has been removed is washed to remove the PEG or glycerin. In this case, pre-curing may be performed, followed by removal of one substrate, and then further full-curing before washing, or pre-curing and full-curing may be performed consecutively, followed by removal of one substrate and washing. Washing is performed, for example, by immersion in a water bath. The separation functional layer 1 can be obtained in this manner. After washing, the coating film may be dried. The separation functional layer 1 produced by the above method typically has an opening on the surface facing the porous layer 2, and the pores 4 form interconnected pores. The interconnected pores typically communicate with the openings.

[0154] In another embodiment of the method for manufacturing a pervaporation membrane according to this embodiment, the coating liquid L contains a foaming agent. For example, the coating liquid L is prepared by mixing a silicone resin composition and a foaming agent. The coating liquid L is applied onto the substrate A to form a coating film, and the coating film is then heated to harden and foam. The substrate A is then removed to obtain a pervaporation membrane 10 made of the separation functional layer 1. Any appropriate foaming agent may be used. The foaming agent is preferably sodium bicarbonate or p,p'-oxybisbenzenesulfonylhydrazide (OBSH). In the separation functional layer 1 produced by the above method, the pores 4 of the porous layer 2 are typically closed pores.

[0155] In this manner, the pervaporation membrane 10 made of the separation functional layer 1 is produced.

[0156] The pervaporation membrane 20 further comprising the porous support 5 can be produced, for example, by laminating the separation functional layer 1 obtained by the above-described method for producing the pervaporation membrane 10 on the porous support 5. The separation functional layer 1 may be laminated on the surface of the porous support 5 that has been subjected to an easy-adhesion treatment.

[0157] Before laminating the separation functional layer 1 and the porous support 5, the surface of the separation functional layer 1 may be subjected to a surface modification treatment. Examples of the surface modification treatment include corona treatment, plasma treatment, excimer treatment, and flame treatment, with corona treatment being preferred. The surface modification treatment is carried out, for example, by irradiating the surface of the separation functional layer 1 with active energy rays. Specific examples of active energy rays include electron beams, ion beams, plasma beams, and ultraviolet rays.

[0158] The method for manufacturing the pervaporation membrane 20 is not limited to the above method. For example, in manufacturing the above-mentioned pervaporation membrane 10, a porous support 5 can be used as the above-mentioned substrate A, and a separation function layer 1 can be formed on the porous support 5, thereby manufacturing a pervaporation membrane 20 equipped with a porous support 5.

[0159] (Uses of Pervaporation Membrane) Hereinafter, matters described regarding pervaporation membrane 10 also apply to pervaporation membrane 20 unless otherwise specified. Pervaporation membrane 10 of this embodiment is suitable for applications such as separating organic compound C from an aqueous solution S containing volatile organic compound C. The organic compound C is not particularly limited as long as it is volatile. In this specification, a "volatile organic compound" refers to, for example, an organic compound having a boiling point of 20°C to 260°C under atmospheric pressure (101.325 kPa). Note that organic compound C, when its concentration in an aqueous solution is high, generates an aqueous phase containing water as a main component and an organic phase having a higher content of organic compound C than the aqueous phase. However, organic compound C may not generate an aqueous phase and an organic phase.

[0160] The number of carbon atoms in the organic compound C is not particularly limited and may be, for example, 10 or less, 8 or less, 6 or less, or even 4 or less. The lower limit of the number of carbon atoms in the organic compound C may be 1 or 2. The organic compound C has a functional group containing an oxygen atom, such as a hydroxyl group, a carbonyl group, an ether group, or an ester group. In the organic compound C, the number of functional groups containing an oxygen atom is typically one.

[0161] Examples of the organic compound C include alcohols, ketones, esters, etc., and are typically alcohols. The alcohol may be an alkyl alcohol composed only of an alkyl group and a hydroxyl group, or an aryl alcohol containing an aryl group and a hydroxyl group. The alkyl alcohol may be linear, branched, or cyclic. Examples of the alkyl alcohol include methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, isobutanol, t-butanol, and n-pentanol, with ethanol, isopropanol, and n-butanol being preferred, and ethanol being more preferred. Examples of the aryl alcohol include phenol, etc.

[0162] The ketone may be a dialkyl ketone consisting of only an alkyl group and a carbonyl group, such as methyl ethyl ketone (MEK) or acetone.

[0163] The ester may be a fatty acid alkyl ester composed only of an alkyl group and an ester group, such as ethyl acetate.

[0164] The organic compound C is not limited to the above-mentioned compounds, and may be an aromatic hydrocarbon such as benzene, toluene, or xylene, or an amide solvent such as N,N-dimethylformamide (DMF) or N-methyl-2-pyrrolidone (NMP).

[0165] The aqueous solution S may contain one type of organic compound C, or may contain two or more types of organic compounds C. The content of the organic compound C in the aqueous solution S may be, for example, 0.5 wt % or more, 1 wt % or more, 2 wt % or more, or even 5 wt % or more. The upper limit of the content of the organic compound C is not particularly limited and may be, for example, 50 wt %.

[0166] The organic compound C may be a fermentation product produced by fermenting a carbon source with a microorganism, or may be alcohol (bioalcohol) produced by a microorganism. That is, the aqueous solution S may be a fermentation liquid containing the organic compound C as a fermentation product. However, the aqueous solution S is not limited to a fermentation liquid, and may be waste liquid or wastewater discharged from a chemical plant or the like.

[0167] The aqueous solution S may further contain other components such as a microorganism that produces a fermented product, a carbon source, a nitrogen source, and inorganic ions in addition to water and the organic compound C. The microorganism that produces the fermented product is typically a fungus. Examples of carbon sources include polysaccharides such as starch and monosaccharides such as glucose.

[0168] (Pervaporation Membrane Characteristics) The separation coefficient of the organic compound C relative to water in the pervaporation membrane 10 is not particularly limited. As an example, the separation coefficient α of the pervaporation membrane 10 for ethanol (EtOH) relative to water is EtOH is, for example, 5 or more, and may be 6 or more, 7 or more, or even 8 or more. EtOH The upper limit is, for example, 100.

[0169] Separation factor α EtOHcan be measured by the following method. With a mixed liquid consisting of EtOH and water in contact with the main surface of the pervaporation membrane 10 on the skin layer 3 side of the separation functional layer 1, the space adjacent to the other main surface of the pervaporation membrane 10 (the surface of the separation functional layer 1 on the porous layer 2 side, or in the case of the pervaporation membrane 20, the main surface on the porous support 5 side) is depressurized. This allows a permeated fluid that has permeated the pervaporation membrane 10 to be obtained. The weight ratio of water and the weight ratio of EtOH in the permeated fluid are measured. In the above operation, the content of EtOH in the mixed liquid is 2.0 wt %. The mixed liquid that is brought into contact with the pervaporation membrane 10 has a temperature of 40°C. The space adjacent to the other surface of the pervaporation membrane 10 is depressurized to 15 hPa. Separation factor α EtOH can be calculated from the following formula: A and X B are the weight ratios of EtOH and water in the mixed liquid, respectively. A and Y B are the weight ratios of EtOH and water in the permeate fluid that has permeated the pervaporation membrane 10, respectively. EtOH = (Y A / Y B ) / (X A / X B )

[0170] The above separation factor α EtOH Under the measurement conditions, the flux of EtOH permeating the pervaporation membrane 10 is not particularly limited, and may be, for example, 0.001 kg / m 2 / hr or more, and may be 0.010 kg / m 2 / hr or more, 0.020kg / m 2 / hr or more, and even 0.050 kg / m 2 The flux of EtOH permeating through the pervaporation membrane 10 may be 1.0 kg / m 2 / hr or less, and may be 0.8 kg / m 2 / hr or less, and even 0.6 kg / m 2 / hr or less.

[0171] The separation factor α of isopropanol (IPA) relative to water of the pervaporation membrane 10 IPAis, for example, 5 or more, and may be 6 or more, 7 or more, 8 or more, or even 9 or more. IPA The upper limit is, for example, 100.

[0172] Separation factor α IPA is the separation factor α except that a mixed liquid of IPA and water with an IPA content of 10 wt % is used instead of a mixed liquid of EtOH and water. EtOH can be measured by the same method as

[0173] The separation factor α of n-butanol (BuOH) relative to water of the pervaporation membrane 10 BuOH is, for example, 8 or more, and may be 10 or more, 12 or more, or even 14 or more. BuOH The upper limit is, for example, 100.

[0174] Separation factor α BuOH is a value obtained by dividing the separation factor α by 1 except that a mixed liquid of BuOH and water containing 0.8 wt % BuOH is used instead of the mixed liquid of EtOH and water, and the temperature of the mixed liquid is 30°C. EtOH can be measured by the same method as

[0175] The pervaporation membrane 10 of this embodiment tends to have good separation performance (particularly the flux of the permeating fluid that permeates the pervaporation membrane) because the separation functional layer 1 has the porous layer 2 and the skin layer 3 .

[0176] <Embodiment of Membrane Separation Apparatus> As shown in Figure 3, the membrane separation apparatus 100 of this embodiment includes a pervaporation membrane 20 and a tank 23. In the membrane separation apparatus 100, it is also possible to use a pervaporation membrane 10 instead of the pervaporation membrane 20. The tank 23 has a first chamber 21 and a second chamber 22. The first chamber 21 functions as a supply space to which a supply fluid (specifically, the above-mentioned aqueous solution S) is supplied. The second chamber 22 functions as a permeation space to which a permeated fluid S1 is supplied. The permeated fluid S1 is obtained by the aqueous solution S permeating through the pervaporation membrane 20.

[0177] Pervaporation membrane 20 is disposed inside tank 23. Inside tank 23, pervaporation membrane 20 separates first chamber 21 and second chamber 22. Pervaporation membrane 20 extends from one of a pair of walls of tank 23 to the other.

[0178] The first chamber 21 has an inlet 21a and an outlet 21b. The second chamber 22 has an outlet 22a. The inlet 21a is an opening for supplying the aqueous solution S to the supply space (first chamber 21). The outlet 22a is an opening for discharging the permeated fluid S1 from the permeated space (second chamber 22). The outlet 21b is an opening for discharging the aqueous solution S that has not permeated the pervaporation membrane 20 (non-permeated fluid S2) from the supply space (first chamber 21). The inlet 21a, the outlet 21b, and the outlet 22a are each formed on, for example, a wall surface of the tank 23.

[0179] The membrane separation apparatus 100 is suitable for a continuous membrane separation method, but may also be used for a batch membrane separation method.

[0180] (Method of Operating the Membrane Separation Apparatus) The method of operating the membrane separation apparatus 100 is, for example, as follows: First, the aqueous solution S is supplied to the first chamber 21 of the membrane separation apparatus 100 through the inlet 21 a. This allows the aqueous solution S to come into contact with one surface of the pervaporation membrane 20 (for example, the main surface of the separation functional layer 1 on the porous layer 2 side).

[0181] Next, with the aqueous solution S in contact with one surface of the pervaporation membrane 20, the space adjacent to the other surface of the pervaporation membrane 20 (e.g., the main surface on the porous support 5 side) is depressurized. Specifically, the pressure inside the second chamber 22 is reduced through the outlet 22a. The pressure inside the second chamber 22 can be reduced by a depressurization device such as a vacuum pump. The pressure in the second chamber 22 is, for example, 50 kPa or less, and may be 20 kPa or less, 10 kPa or less, 5 kPa or less, 3 kPa or less, or even 2 kPa or less. In this specification, unless otherwise specified, "pressure" refers to absolute pressure.

[0182] By reducing the pressure inside the second chamber 22, a permeated fluid S1 having a high content of organic compound C can be obtained on the other side of the pervaporation membrane 20. In other words, the permeated fluid S1 is supplied to the second chamber 22. In the second chamber 22, the permeated fluid S1 is typically a gas. The permeated fluid S1 is discharged to the outside of the membrane separation device 100 through the outlet 22a.

[0183] On the other hand, the content of the organic compound C in the aqueous solution S gradually decreases from the inlet 21a to the outlet 21b of the first chamber 21. The aqueous solution S treated in the first chamber 21 (non-permeated fluid S2) is discharged to the outside of the membrane separation device 100 through the outlet 21b. The non-permeated fluid S2 is typically a liquid.

[0184] As described above, the pervaporation membrane 20 allows preferential permeation of the organic compounds C contained in the aqueous solution S. Therefore, the permeated fluid S1 obtained by operation of the membrane separation device 100 has a higher content of organic compounds C than the aqueous solution S supplied to the membrane separation device 100.

[0185] <Modifications of Membrane Separation Device> The membrane separation device 100 may be a spiral membrane element, a hollow fiber membrane element, a disk-tube membrane element in which multiple pervaporation membranes are stacked, a plate-and-frame membrane element, or the like. Fig. 4 shows a spiral membrane element. The membrane separation device 110 of Fig. 4 includes a central tube 26 and a stack 27. The stack 27 includes a pervaporation membrane 20. In the membrane separation device 110, it is also possible to use a pervaporation membrane 10 instead of the pervaporation membrane 20.

[0186] The central tube 26 has a cylindrical shape. A plurality of holes or slits are formed on the surface of the central tube 26 to allow the permeation fluid S1 to flow into the interior of the central tube 26. Examples of materials for the central tube 26 include resins such as acrylonitrile-butadiene-styrene copolymer resin (ABS resin), polyphenylene ether resin (PPE resin), and polysulfone resin (PSF resin); and metals such as stainless steel and titanium. The inner diameter of the central tube 26 is, for example, in the range of 20 to 100 mm.

[0187] In addition to the pervaporation membrane 20, the laminate 27 further includes a feed-side channel material 28 and a permeate-side channel material 29. The laminate 27 is wound around a central tube 26. The membrane separation device 110 may further include an exterior material (not shown).

[0188] As the feed-side flow path material 28 and the permeate-side flow path material 29, for example, a resin net, woven fabric, or knitted fabric made of polyethylene, polypropylene, polyethylene terephthalate (PET), polyphenylene sulfide (PPS), or ethylene-chlorotrifluoroethylene copolymer (ECTFE) can be used.

[0189] The membrane separation device 110 can be operated, for example, by the following method. First, the aqueous solution S is supplied to one end of the wound stack 27. The space inside the central tube 26 is depressurized. As a result, the permeated fluid S1 that has permeated the pervaporation membrane 20 of the stack 27 moves into the central tube 26. The permeated fluid S1 is discharged to the outside through the central tube 26. The aqueous solution S (non-permeated fluid S2) that has been treated in the membrane separation device 110 is discharged to the outside from the other end of the wound stack 27.

[0190] <Embodiment of Membrane Separation System> As shown in Fig. 5, a membrane separation system 200 of this embodiment includes the above-described membrane separation device 100. Note that the membrane separation system 200 may include the membrane separation device 110 described in Fig. 4 instead of the membrane separation device 100.

[0191] The membrane separation system 200 further includes a tank 30 in addition to the membrane separation apparatus 100. The tank 30 stores an aqueous solution S to be supplied to the membrane separation apparatus 100. The tank 30 may be a fermenter for producing an organic compound C by fermentation of a carbon source by microorganisms.

[0192] The membrane separation system 200 further includes an aqueous solution supply path 70, a non-permeated fluid discharge path 71, and a permeated fluid discharge path 72. The aqueous solution supply path 70 is a path for supplying the aqueous solution S from the tank 30 to the membrane separation device 100 during operation, and is connected to the outlet 31 of the tank 30 and the inlet 21a of the membrane separation device 100. The aqueous solution supply path 70 is provided with, for example, a pump 50 for controlling the flow rate of the aqueous solution S.

[0193] The non-permeated fluid discharge path 71 is a path for discharging the non-permeated fluid S2 from the membrane separation device 100 during operation, and is connected to the outlet 21b of the membrane separation device 100. For example, a pump 51 for controlling the flow rate of the non-permeated fluid S2 is disposed in the non-permeated fluid discharge path 71. The pump 51 does not necessarily have to be disposed in the non-permeated fluid discharge path 71. The non-permeated fluid discharge path 71 may be connected to the inlet 32 ​​of the tank 30 and configured to send the non-permeated fluid S2 to the tank 30 during operation. That is, during operation, the non-permeated fluid S2 may be mixed with the aqueous solution S in the tank 30 and circulated through the aqueous solution supply path 70 and the non-permeated fluid discharge path 71. When the non-permeated fluid S2 is sent to the tank 30, the aqueous solution S and the non-permeated fluid S2 are mixed in the tank 30, and the content of the organic compound C in the aqueous solution S decreases. When the tank 30 is a fermenter, the decrease in the content of the organic compound C in the aqueous solution S can prevent the fermentation by the microorganisms from stopping, thereby enabling the production of the fermented product to be carried out continuously.

[0194] The permeate discharge path 72 is a path for discharging the permeate fluid S1 from the membrane separation device 100 during operation and is connected to the outlet 22a of the membrane separation device 100. The permeate discharge path 72 is provided with, for example, a pressure reducing device 52. The pressure reducing device 52 can reduce the pressure inside the permeate space of the membrane separation device 100. The pressure reducing device 52 is preferably a vacuum device such as a vacuum pump. The vacuum pump is typically a gas transport vacuum pump, and examples thereof include a reciprocating vacuum pump and a rotary vacuum pump. Examples of reciprocating vacuum pumps include diaphragm-type and oscillating piston-type vacuum pumps. Examples of rotary vacuum pumps include liquid ring pumps; oil rotary pumps (rotary pumps); mechanical booster pumps; and various dry pumps such as roots-type, claw-type, screw-type, turbo-type, and scroll-type pumps. The pump serving as the pressure reducing device 52 may be equipped with a variable speed mechanism for changing the rotation speed, etc. An example of a variable speed mechanism is an inverter that drives the pump motor. By controlling the rotation speed of the pump with the variable speed mechanism, the pressure in the permeate space of the membrane separation device 100 can be adjusted appropriately.

[0195] A heat exchanger for cooling the permeated fluid S1 may be further disposed in the permeated fluid discharge path 72. The heat exchanger can condense the gaseous permeated fluid S1. The heat exchanger is, for example, a gas-liquid heat exchanger that causes heat exchange between a cooling medium such as antifreeze and the gaseous permeated fluid S1. The heat exchanger may be located between the membrane separation apparatus 100 and the pressure reducing device 52 (upstream of the pressure reducing device 52), or may be located between the pressure reducing device 52 and the recovery section 40 (downstream of the pressure reducing device 52), which will be described later.

[0196] The membrane separation system 200 further includes a recovery unit 40. The recovery unit 40 recovers the permeated fluid S1 sent from the membrane separation device 100 and can store the permeated fluid S1, for example. The recovery unit 40 is, for example, a tank that stores the permeated fluid S1. A permeated fluid discharge path 72 is connected to an inlet 41 of the recovery unit 40.

[0197] The membrane separation system 200 may further include a controller 60 that controls each component of the membrane separation system 200. The controller 60 is, for example, a DSP (Digital Signal Processor) including an A / D conversion circuit, an input / output circuit, an arithmetic circuit, a storage device, etc. The controller 60 stores a program for appropriately operating the membrane separation system 200.

[0198] Unless otherwise specified, each of the paths of the membrane separation system 200 is made up of, for example, metal or resin piping.

[0199] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto.

[0200] <Preparation of Pervaporation Membrane> (Example 1) First, a smectite dispersion was prepared by dispersing smectite (anionic polymer-composite purified bentonite; manufactured by Hojun Co., Ltd., Bengel W100U) in ion-exchanged water so that the content was 0.9 mass %. Next, a PDMS-containing silicone resin composition (SILPOT TM184: 100 parts by weight of base resin, 10 parts by weight of curing agent (110 parts by weight), 140 parts by weight of smectite dispersion in water, and 1.3 parts by weight of surfactants (Kao Corporation, Rheodol SP-O10V (HLB 4.3) 96% by weight, Rheodol SP-O30V (HLB 1.8) 4% by weight): were emulsified for 10 minutes using a Thinky Rentaro (Thinky Corporation). The emulsion was then degassed at 10 kPa using a Thinky Rentaro Vacuum Type (Thinky Corporation) to prepare a coating solution. The coating solution was applied to a release liner (Mitsubishi Chemical Corporation, MRE38) to obtain a coating film (thickness 80 μm). A release liner (Toray Industries, Inc., Lumirror 75S10) was then placed over the coating film, and the film was heated in a hot air oven at 85°C for 6 minutes to cure the silicone resin. After curing, one of the release liners was peeled off to expose the surface of the cured silicone resin, and the laminate was further dried by heating at 150°C for 10 minutes to obtain a laminate in which a separation functional layer was formed on the release liner.

[0201] Next, a PET nonwoven fabric was prepared as a porous support. The laminate was laminated on the porous support so that the surface of the porous support and the surface of the separation function layer were in contact with each other. The other release liner was then removed. In this manner, the pervaporation membrane of Example 1 was produced.

[0202] Example 2 A pervaporation membrane of Example 2 was produced in the same manner as in Example 1, except that the coating solution was applied so that the thickness of the coating film became 110 μm.

[0203] Example 3 A pervaporation membrane of Example 3 was produced in the same manner as in Example 1, except that the mixing ratio of the materials in the coating liquid was 110 parts by mass of the PDMS-containing silicone resin composition, 90 parts by mass of the smectite dispersion in water, and 1.3 parts by mass of surfactants (manufactured by Kao Corporation, Rheodol SP-O10V (HLB 4.3) 96% by mass, Rheodol SP-O30V (HLB 1.8) 4% by mass).

[0204] Example 4 A pervaporation membrane of Example 4 was produced in the same manner as in Example 1, except that the mixing ratio of the materials in the coating liquid was 110 parts by mass of the PDMS-containing silicone resin composition, 50 parts by mass of the smectite dispersion in water, and 1.3 parts by mass of surfactants (manufactured by Kao Corporation, Rheodol SP-O10V (HLB 4.3) 96% by mass, Rheodol SP-O30V (HLB 1.8) 4% by mass).

[0205] (Example 5) PDMS-containing silicone resin composition (SILPOT TM 184: 100 parts by weight of base agent, 10 parts by weight of curing agent), 110 parts by weight, and 100 parts by weight of polyethylene glycol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., PEG200) were emulsified for 10 minutes using a Thinky Rentaro (manufactured by Thinky Corporation). The emulsion was then degassed at 10 kPa using a Thinky Rentaro Vacuum Type (manufactured by Thinky Corporation) to prepare a coating solution. A coating film (80 μm thick) was obtained by applying the coating solution to a release liner (manufactured by Mitsubishi Chemical Corporation, MRE38). A release liner (manufactured by Toray Industries, Inc., Lumirror 75S10) was then placed over the coating film, which was then heated in a hot air oven at 80°C for 60 minutes and then at 120°C for 60 minutes to cure the silicone resin. After curing, one of the release liners was peeled off to expose the surface of the cured silicone resin. The cured silicone resin was washed by immersing it in a water bath at 50° C. for 12 hours, to obtain a laminate in which a separation functional layer was formed on the release liner.

[0206] Next, a PET nonwoven fabric was prepared as a porous support. The laminate was laminated on the porous support so that the surface of the porous support and the surface of the separation function layer were in contact with each other. The other release liner was then removed. In this manner, the pervaporation membrane of Example 5 was produced.

[0207] Example 6 A pervaporation membrane of Example 6 was produced in the same manner as in Example 5, except that polyethylene glycol was changed to glycerin (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

[0208] Example 7 A pervaporation membrane of Example 7 was produced in the same manner as in Example 1, except that a PPS nonwoven fabric was used as the porous support.

[0209] Example 8 A pervaporation membrane of Example 8 was prepared in the same manner as in Example 1, except that a laminate of a microporous layer made of polysulfone and a nonwoven fabric made of PET (CF-30S, manufactured by Nitto Denko Corporation) was used as the porous support.

[0210] Example 9 A pervaporation membrane of Example 9 was produced in the same manner as in Example 1, except that 2 parts by mass of Rheodol MO-60 (HLB 2.8) manufactured by Kao Corporation was used as the surfactant. That is, in Example 9, the mixing ratio of each material in the coating liquid was 110 parts by mass of the PDMS-containing silicone resin composition, 140 parts by mass of the smectite dispersion in water, and 2 parts by mass of the surfactant (Rheodol MO-60 (HLB 2.8) manufactured by Kao Corporation).

[0211] (Comparative Example 1) PDMS-containing silicone resin composition (SILPOT TM A coating film (25 μm thick) was obtained by applying a mixture of 184 (100 parts by weight of base agent and 10 parts by weight of curing agent) to a release liner (Lumirror 75S10, manufactured by Toray Industries, Inc.). The resulting mixture was then heated at 150° C. for 10 minutes to obtain a laminate in which a separation functional layer was formed on the release liner. The pervaporation membrane of Comparative Example 1 was prepared in the same manner as in Example 1, except for the above.

[0212] Comparative Example 2 A pervaporation membrane of Comparative Example 2 was produced in the same manner as in Comparative Example 1, except that the PDMS-containing silicone resin composition was applied so that the thickness of the applied film was 80 μm.

[0213] Comparative Example 3 A pervaporation membrane of Comparative Example 3 was produced in the same manner as in Comparative Example 1, except that the PDMS-containing silicone resin composition was applied so that the thickness of the applied film was 110 μm.

[0214] <Observation of the Structure of the Separation Functional Layer> A scanning electron microscope (SU-3800, manufactured by Hitachi High-Technologies Corporation) was used to observe the cross section of the separation functional layer to confirm the presence or absence of a porous layer in the separation functional layer. In the pervaporation membranes of Examples 1 to 9, the separation functional layer had a porous layer containing pores and a skin layer. The pores in the porous layer formed continuous pores with openings on the surface of the pervaporation membrane. In the pervaporation membranes of Comparative Examples 1 to 3, a porous layer containing pores was not observed in the separation functional layer. In addition, the thickness of the separation functional layer, the thickness of the skin layer, and the average pore size of the pores in the porous layer were measured by the above cross-sectional observation. The measurement results are shown in Table 1.

[0215] <Porosity of Separation Functional Layer> The porosity of the separation functional layer in the pervaporation membranes of Examples 1 to 9 was measured using the method described above. Specifically, a scanning electron microscope (SU-3800, manufactured by Hitachi High-Technologies Corporation) was used to observe the cross section of the separation functional layer at five locations. The average area ratio of the pores at each location was taken as the porosity of the separation functional layer. The magnification was 500x. The measurement results are shown in Table 1.

[0216] <Separation Performance> (EtOH Separation Performance) The separation coefficient α of ethanol (EtOH) relative to water was measured for the pervaporation membranes prepared in Examples 1 to 9 and Comparative Examples 1 to 3 by the following method. EtOH was measured. First, the pervaporation membrane was cut into a size of 74 mm in diameter to prepare a flat membrane-shaped test piece. This test piece was set in a batch-type membrane separation device (cell). A mixed liquid consisting of ethanol (EtOH) and water was supplied to the supply space of this cell. The EtOH content in the mixed liquid was 2.0 wt%.

[0217] Next, the cell was immersed in a water bath, and the temperature of the mixed liquid was adjusted to 40°C. Next, the pressure in the permeation space was reduced to 15 hPa while stirring the mixed liquid using a stirrer placed in the cell. This caused the mixed liquid to permeate the pervaporation membrane, and a gaseous permeation fluid was obtained. The gaseous permeation fluid was cooled by a cooling trap using liquid nitrogen, and the permeation fluid was condensed. The composition of the liquid permeation fluid was analyzed using gas chromatography, and based on the obtained results, the separation factor α EtOH , and the flux of EtOH permeating the pervaporation membrane [kg / m2 / hr] was calculated. The evaluation results are shown in Table 1.

[0218] (IPA Separation Performance) For the pervaporation membranes of Example 9 and Comparative Example 1, the separation coefficient α of isopropanol (IPA) relative to water was measured by the following method. IPA First, a flat membrane test piece was obtained in the same manner as described above, and the test piece was set in a batch-type membrane separation device (cell). A mixed liquid consisting of IPA and water was supplied to the supply space of this cell. The IPA content in the mixed liquid was 10 wt %.

[0219] Next, the cell was immersed in a water bath, and the temperature of the mixed liquid was adjusted to 40°C. Next, the pressure in the permeation space was reduced to 15 hPa while stirring the mixed liquid using a stirrer placed in the cell. This caused the mixed liquid to permeate the pervaporation membrane, and a gaseous permeation fluid was obtained. The gaseous permeation fluid was cooled by a cooling trap using liquid nitrogen, and the permeation fluid was condensed. The composition of the liquid permeation fluid was analyzed using gas chromatography, and based on the obtained results, the separation factor α IPA , and the flux of IPA that permeated the pervaporation membrane [kg / m 2 / hr] was calculated. The evaluation results are shown in Table 2.

[0220] (BuOH Separation Performance) The separation coefficient α of n-butanol (BuOH) relative to water was measured for the pervaporation membranes of Example 9 and Comparative Example 1 by the following method. BuOH First, a flat membrane test piece was obtained in the same manner as described above, and the test piece was set in a batch-type membrane separation device (cell). A mixed liquid consisting of BuOH and water was supplied to the supply space of this cell. The BuOH content in the mixed liquid was 0.8 wt%.

[0221] Next, the cell was immersed in a water bath, and the temperature of the mixed liquid was adjusted to 30°C. Next, the pressure in the permeation space was reduced to 15 hPa while stirring the mixed liquid using a stirrer placed in the cell. This caused the mixed liquid to permeate the pervaporation membrane, and a gaseous permeation fluid was obtained. The gaseous permeation fluid was cooled by a cooling trap using liquid nitrogen, and the permeation fluid was condensed. The composition of the liquid permeation fluid was analyzed using gas chromatography, and based on the obtained results, the separation factor α BuOH , and the flux of BuOH that permeated the pervaporation membrane [kg / m 2 The evaluation results are shown in Table 2.

[0222]

[0223]

[0224] The pervaporation membranes of Examples 1 to 9, in which the separation functional layer has a porous layer and a skin layer, have improved EtOH flux and practically acceptable separation factors α compared to the pervaporation membranes of Comparative Examples 1 to 3, in which the separation functional layer does not have a porous layer. EtOH Furthermore, the pervaporation membrane of Example 9 had improved IPA flux and BuOH flux compared to the pervaporation membrane of Comparative Example 1, and had a practically acceptable separation factor α IPA , and separation factor α BuOH From the above, the pervaporation membranes of Examples 1 to 9 are suitable for improving separation performance.

[0225] The pervaporation membrane of this embodiment is suitable for separating volatile organic compounds from an aqueous solution containing the organic compounds.

Claims

1. A pervaporation membrane comprising a separation functional layer, the separation functional layer having a porous layer containing pores and a skin layer formed on the porous layer.

2. The pervaporation membrane according to claim 1, wherein the separation functional layer includes a resin material.

3. The pervaporation membrane of claim 2, wherein the resin material is a silicone resin.

4. The pervaporation membrane of claim 1, wherein the pores have an average pore size of 1 nm or greater.

5. The pervaporation membrane of claim 1, wherein the pores form interconnected pores.

6. The pervaporation membrane according to claim 1, wherein the porosity of the separating functional layer is 10% or more.

7. The pervaporation membrane of claim 1, further comprising a porous support that supports the separation functional layer.

8. The pervaporation membrane of claim 7, wherein the porous support is a fibrous structure.

9. The pervaporation membrane of claim 1, wherein the separation functional layer includes a filler.

10. The pervaporation membrane of claim 1 used to separate volatile organic compounds from an aqueous solution containing said organic compounds.

11. The pervaporation membrane of claim 10, wherein the organic compound is an alcohol.

12. The pervaporation membrane of claim 11, wherein the alcohol is ethanol.

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