Pervaporation membrane

Abstract

A pervaporation membrane 10A according to the present invention comprises a separation functional layer 1 and a porous support 5 that supports the separation functional layer 1. The separation functional layer 1 includes a polymer P. The porous support 5 has a body 6 and a microporous layer 7 arranged on the body 6. The microporous layer 7 is positioned between the body 6 and the separation functional layer 1. The polymer P is present in the microporous layer 7 from a surface 7a on the side of the microporous layer 7 that is toward the separation functional layer 1 to a position X inside the microporous layer 7 along the thickness direction of the microporous layer 7.

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 (PV) 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 separating volatile organic compounds from an aqueous solution containing the organic compounds, there is a need to reduce the decrease in separation performance when a defect occurs in a pervaporation membrane. The present invention provides a pervaporation membrane that is suitable for separating volatile organic compounds from an aqueous solution containing the organic compounds, even when a defect occurs in the membrane.

[0006] The present invention provides a pervaporation membrane comprising: a separation functional layer containing a polymer; and a porous support supporting the separation functional layer, wherein the porous support has a main body portion and a microporous layer disposed on the main body portion, the microporous layer is positioned between the main body portion and the separation functional layer, and the polymer is present within the microporous layer from the surface of the microporous layer facing the separation functional layer along the thickness direction of the microporous layer to position X within the microporous layer.

[0007] According to the present invention, it is possible to provide a pervaporation membrane that is suitable for separating volatile organic compounds from an aqueous solution containing the organic compounds, even when defects occur.

[0008] 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 a modified example of a pervaporation membrane. FIG. 3 is a schematic cross-sectional view of a membrane separation device equipped with 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. FIG. 6 is a graph showing the relationship between the average diameter L of the openings H of the porous support used in producing the pervaporation membranes of Examples 1 to 6 and Comparative Examples 1 to 5 and the weight average molecular weight M of the polyorganosiloxane. FIG. 7 is a graph showing the relationship between the air resistance R of the porous support used in producing the pervaporation membranes of Examples 1 to 6 and Comparative Examples 1 to 5 and the weight average molecular weight M of the polyorganosiloxane.

[0009] A pervaporation membrane according to a first aspect of the present invention is a pervaporation membrane comprising: a separation functional layer containing a polymer; and a porous support supporting the separation functional layer, wherein the porous support has a main body portion and a microporous layer disposed on the main body portion, the microporous layer is positioned between the main body portion and the separation functional layer, and the polymer is present within the microporous layer from the surface of the microporous layer facing the separation functional layer along the thickness direction of the microporous layer to position X inside the microporous layer.

[0010] In a second aspect of the present invention, for example, in the pervaporation membrane according to the first aspect, the distance in the thickness direction from the surface of the microporous layer to the position X is 10% or more and 70% or less of the thickness of the microporous layer.

[0011] In a third aspect of the present invention, for example, in the pervaporation membrane according to the first or second aspect, a filler is present in the pores of the microporous layer, and the filler contains the polymer.

[0012] In a fourth aspect of the present invention, for example, in the pervaporation membrane according to the third aspect, the filler and the separation functional layer are connected to each other.

[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 polymer is a silicone resin.

[0014] In a sixth aspect of the present invention, for example, in the pervaporation membrane according to the fifth aspect, the silicone resin is formed from an addition type silicone resin composition.

[0015] In a seventh aspect of the present invention, for example, in the pervaporation membrane according to the fifth or sixth aspect, the silicone resin is formed from a silicone resin composition having a solvent content of 5 wt % or less.

[0016] In an eighth aspect of the present invention, for example, in the pervaporation membrane according to any one of the first to seventh aspects, the microporous layer contains polysulfone.

[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 further contains a filler.

[0018] In a tenth aspect of the present invention, for example, in the pervaporation membrane according to the ninth aspect, the filler includes silica.

[0019] In an eleventh aspect of the present invention, for example, in the pervaporation membrane according to the ninth or tenth aspect, the filler has a surface modified with a modifying group containing a hydrocarbon group.

[0020] In a twelfth aspect of the present invention, for example, the pervaporation membrane according to any one of the first to eleventh aspects is used to separate volatile organic compounds from an aqueous solution containing the organic compounds.

[0021] In a thirteenth aspect of the present invention, for example, in the pervaporation membrane according to the twelfth aspect, the organic compound is an alcohol.

[0022] 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.

[0023] <Embodiment of Pervaporation Membrane> Figure 1 is a cross-sectional view schematically showing a pervaporation membrane according to one embodiment of the present invention. The pervaporation membrane 10A of this embodiment comprises a separation function layer 1 containing a polymer P and a porous support 5 supporting the separation function layer 1. The porous support 5 has a main body 6 and a microporous layer 7 disposed on the main body 6, with the microporous layer 7 being positioned between the main body 6 and the separation function layer 1. The polymer P is present in the microporous layer 7 from a surface 7a of the microporous layer 7 facing the separation function layer 1 to a position X inside the microporous layer 7 along the thickness direction of the microporous layer 7.

[0024] A filler containing polymer P is present in the pores of microporous layer 7. That is, the filler containing polymer P is embedded in the pores of microporous layer 7. The filler may completely or partially fill the pores from surface 7a to position X inside microporous layer 7 along the thickness direction of microporous layer 7. Typically, the filler and separation functional layer 1 are connected.

[0025] The separation function layer 1 has, for example, a surface that is in direct contact with the porous support 5 (surface 7a of the microporous layer 7) and a surface that is exposed to the outside of the pervaporation membrane 10A. The pervaporation membrane 10A is composed of, for example, only the separation function layer 1 and the porous support 5.

[0026] The pervaporation membrane 10A 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 10A is suitable for reducing a decrease in separation performance when a defect occurs in the separation functional layer 1 that contacts the permeate or another component when separating the organic compounds C from the aqueous solution S, and is suitable for separating the organic compounds from an aqueous solution containing volatile organic compounds even when a defect occurs in the separation functional layer 1. The pervaporation membrane 10A is also suitable for improving separation performance in the initial state, particularly the flux of the permeating fluid that permeates the pervaporation membrane 10A. Therefore, the pervaporation membrane 10A is suitable for improving separation performance for separating organic compounds from an aqueous solution containing volatile organic compounds, both in the initial state and when a defect occurs.

[0027] (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 is typically a dense layer (non-porous layer) in which no pores are visible when observed at a magnification of 5000 times using a scanning electron microscope (SEM).

[0028] The separation functional layer 1 contains a polymer P. The polymer P is typically a silicone resin.

[0029] The silicone resin is formed, for example, from a silicone resin composition. The silicone resin composition includes, for example, a silicone base material and a curing agent. The silicone base material is, for example, a mixture of polyorganosiloxanes. The curing agent includes, for example, a curing catalyst. The curing agent may further include polyorganosiloxane in some cases.

[0030] The weight average molecular weight M of the silicone base material (polyorganosiloxane mixture) may be, for example, 1,000 or more, 5,000 or more, 10,000 or more, or even 20,000 or more. The weight average molecular weight M may be, for example, 1,000,000 or less, 500,000 or less, 200,000 or less, 100,000 or less, 80,000 or less, or even 50,000 or less. The weight average molecular weight of the curing agent may be 10,000 or more and 200,000 or less.

[0031] The silicone resin is not particularly limited, and may be, for example, 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. Addition type silicone resin compositions 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 is preferably formed from a silicone resin composition containing 5 wt % or less of a solvent such as an organic solvent, and more preferably formed from a solventless silicone resin composition that is substantially free of solvents such as an organic solvent.

[0032] [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.

[0033] 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.

[0034] 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.

[0035] 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. The polyorganosiloxane P1 is preferably PDMS.

[0036] The weight average molecular weight of polyorganosiloxane P1 is, for example, 1000 or more, 5000 or more, 10,000 or more, or even 20,000 or more. The weight average molecular weight of polyorganosiloxane P1 is, for example, 1 million or less, 500,000 or less, 100,000 or less, 80,000 or less, or even 50,000 or less.

[0037] 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.

[0038] Examples of the polyorganosiloxane P2 include polymethylhydrogensiloxane, poly(dimethylsiloxane-methylhydrogensiloxane), and hydrosilyl-terminated polydimethylsiloxane.

[0039] The weight average molecular weight of polyorganosiloxane P2 is, for example, 100 or more, and may be 10,000 or more. The weight average molecular weight of polyorganosiloxane P2 is, for example, 1,000,000 or less, 500,000 or less, 100,000 or less, 80,000 or less, or even 50,000 or less.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] [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.

[0045] 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.

[0046] 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.

[0047] The polyorganosiloxane P3 is, for example, a polyorganosiloxane in which silanol groups have been introduced into the polyorganosiloxane described above for the polyorganosiloxane P1.

[0048] The weight average molecular weight of polyorganosiloxane P3 is, for example, 1000 or more, 5000 or more, 10,000 or more, or even 20,000 or more. The weight average molecular weight of polyorganosiloxane P3 is, for example, 1 million or less, 500,000 or less, 100,000 or less, 80,000 or less, or even 50,000 or less.

[0049] 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.

[0050] 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.

[0051] Examples of the curing catalyst include tin-based catalysts, such as organotin catalysts such as dibutyltin dilaurate, dibutyltin diacetate, and dibutyltin dioctate.

[0052] 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.

[0053] [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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] The weight average molecular weight of polyorganosiloxane P5 is, for example, 1000 or more, 5000 or more, 10,000 or more, or even 20,000 or more. The weight average molecular weight of polyorganosiloxane P5 is, for example, 1 million or less, 500,000 or less, 100,000 or less, 80,000 or less, or even 50,000 or less.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] The weight-average molecular weight of compound P6 is, for example, 1,000 or more, and may be 5,000 or more, 10,000 or more, or even 20,000 or more. The weight-average molecular weight of compound P6 is, for example, 1,000,000 or less, and may be 500,000 or less, 100,000 or less, 80,000 or less, or even 50,000 or less.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] The weight average molecular weight of polyorganosiloxane P7 is, for example, 1000 or more, 5000 or more, 10,000 or more, or even 20,000 or more. The weight average molecular weight of polyorganosiloxane P7 is, for example, 1 million or less, 500,000 or less, 100,000 or less, 80,000 or less, or even 50,000 or less.

[0067] 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.

[0068] The separation functional layer 1 may contain polymer P as a main component, or may be composed essentially of polymer P. That is, the separation functional layer 1 may contain silicone resin as a main component, or may be composed essentially of silicone resin. The "main component" refers to the component that is contained in the largest amount by weight in the separation functional layer 1.

[0069] The thickness of the separation functional layer 1 is, for example, 200 μm or less, and may be 100 μm or less, 50 μm or less, or even 20 μm or less. The thickness of the separation functional layer 1 may be 0.05 μm or more, 0.1 μm or more, 0.5 μm or more, or even 1 μm or more. The thickness of the separation functional layer 1 may be 1 μm or more and 50 μm or less. In this specification, the thickness of the separation functional layer 1 is the distance from the surface 7a of the microporous layer 7 to the surface of the separation functional layer 1 exposed to the outside of the pervaporation membrane 10A.

[0070] (Porous Support) The porous support 5 supports the separation functional layer 1. The porous support 5 preferably contains a polymer material, more preferably consists essentially of a polymer material, and even more preferably consists only of a polymer material.

[0071] The porous support 5 includes a main body 6 and a microporous layer 7 disposed on the main body 6. In the pervaporation membrane 10A, the microporous layer 7 is located between the main body 6 and the separation functional layer 1, and is in direct contact with both the main body 6 and the separation functional layer 1. The porous support 5 is typically an ultrafiltration membrane.

[0072] The main body 6 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. This can improve the flux of the permeating fluid passing through the pervaporation membrane 10A.

[0073] 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 main body 6 is, for example, a nonwoven fabric made of polyester fiber. The nonwoven fabric is preferably a polyethylene terephthalate (PET) nonwoven fabric.

[0074] 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.

[0075] 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.

[0076] The main body 6 has an average pore size of, for example, 1 μm to 50 μm.

[0077] The microporous layer 7 is a layer having an average pore size smaller than that of the main body portion 6 .

[0078] Polymer P is present in microporous layer 7 from surface 7a of microporous layer 7 to position X inside microporous layer 7 along the thickness direction of microporous layer 7, and typically, a filler containing polymer P is embedded in the pores of microporous layer 7 to position X inside microporous layer 7. For example, polymer P is impregnated into microporous layer 7 from surface 7a of microporous layer 7 to position X inside microporous layer 7 along the thickness direction of microporous layer 7. In this specification, "the inside of microporous layer 7" does not include the surface of microporous layer 7. That is, in pervaporation membrane 10A according to this embodiment, polymer P is present from surface 7a of microporous layer 7 to depth position X that is x % of the thickness of microporous layer 7, where x satisfies 0<x<100.

[0079] The ratio of the distance in the thickness direction from surface 7a of microporous layer 7 to position X to the thickness of microporous layer 7 is preferably 10% or more and 70% or less, more preferably 20% or more and 60% or less, even more preferably 30% or more and 60% or less, and particularly preferably 40% or more and 50% or less. In this specification, this ratio may be referred to as the "permeation ratio of polymer P."

[0080] The penetration rate of polymer P can be determined, for example, by the following method. First, pervaporation membrane 10A is cut to a width of 5 mm x length of 30 mm and immersed in liquid nitrogen to freeze. Then, a measurement sample is prepared by cutting it further to a width of 5 mm x length of 15 mm with a feather blade and depositing platinum on the cross section. Elemental analysis based on scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX) is performed on the platinum-deposited surface of the measurement sample in the thickness direction of pervaporation membrane 10A to measure the intensity of elements contained in polymer P but not contained in microporous layer 7 (when polymer P is a silicone resin, Si element). From the measurement results, when the intensity of the above element in separation functional layer 1 is set to 100, polymer P is considered to be present up to the position in microporous layer 7 where the intensity of the above element is 30 or more, and the position just before the intensity becomes less than 30 is designated as position X. Therefore, when the only position in the microporous layer 7 where the intensity of the above element is 30 or more is the surface 7a of the microporous layer 7 that is in contact with the separation functional layer 1, this means that the polymer P is not present inside the microporous layer 7 (x=0). When the intensity of the above element is 30 or more from the surface 7a to the other surface 7b of the microporous layer 7 opposite the surface 7a, this means that the polymer P is present throughout the microporous layer 7, and position X is not located inside the microporous layer 7 (x=100). The distance D in the thickness direction of the microporous layer 7 from the surface 7a of the microporous layer 7 to position X, and the thickness of the microporous layer 7, can be measured from an SEM photograph. The penetration rate of the polymer P can be calculated using the following formula: Penetration rate [%] = 100 × distance D [μm] / thickness of the microporous layer [μm]

[0081] Examples of materials for microporous layer 7 include fluororesins such as polyvinylidene fluoride and polytetrafluoroethylene; polyarylethersulfones such as polysulfone and polyethersulfone; and polyimides, and microporous layer 7 preferably contains polysulfone. In porous support 5 used to fabricate pervaporation membrane 10, microporous layer 7 has an average pore size of, for example, 0.01 μm to 0.4 μm.

[0082] The average diameter L of the openings H on the surface of the porous support 5 used to prepare the pervaporation membrane 10A facing the separation function layer 1 (surface 7a of the microporous layer 7) is, for example, 0.001 μm or more, preferably 0.002 μm or more, and more preferably 0.005 μm or more. The average diameter L of the openings H on the surface 7a of the microporous layer 7 is, for example, 0.20 μm or less, preferably 0.11 μm or less, more preferably 0.08 μm or less, even more preferably 0.07 μm or less, and particularly preferably 0.06 μm or less.

[0083] The average diameter L of the openings H in the surface 7a of the microporous layer 7 of the porous support 5 used to fabricate the pervaporation membrane 10A can be determined by the following method. First, the surface 7a of the microporous layer 7 is observed using an SEM. The surface 7a is observed, for example, on the porous support 5 removed from the pervaporation membrane 10A and from which the filler has been removed. Note that the surface 7a may also be observed on the microporous layer 7 of the porous support 5 before it is used to fabricate the pervaporation membrane 10A.

[0084] As an example, the magnification of the SEM is adjusted to about 20,000 times, and openings H are identified in the obtained SEM image within a range greater than 4.8 μm in length × 6.0 μm in width. Specifically, the identification of openings H is performed by using software (e.g., Image J) to convert the SEM image into a binary image of openings H and portions other than openings H (non-openings). The area (opening area h) of each identified opening H is calculated by image processing. The diameter of a circle having the same area as the calculated area for each opening is regarded as the diameter d of opening H. Based on the obtained results, the average diameter L of openings H can be determined using the following formula. As shown in the following formula, the average diameter L is a weighted average value of diameters d weighted by opening area h. Average diameter L [μm] = Σ {opening area h [μm 2 ]×Diameter d [μm]} / ΣOpening area [μm 2 ]

[0085] The average diameter L of the openings H and the weight average molecular weight M of the polyorganosiloxane in the silicone resin composition used to form the polymer P preferably satisfy the relationship 0.6L-12,000≦M≦0.6L+60,000.

[0086] The surface (surface 7a of microporous layer 7) of porous support 5 used to prepare pervaporation membrane 10 on the separating function layer 1 side has an opening ratio of, for example, 1% or more, preferably 5% or more, and more preferably 10% or more. The opening ratio of surface 7a of microporous layer 7 is, for example, 30% or less, preferably 25% or less, more preferably 20% or less, and even more preferably 15% or less.

[0087] The opening ratio can be determined by the following method. First, the surface 7a of the microporous layer 7 is observed with an SEM using the method described above for the average diameter, and the openings H are identified. The ratio of the total area of ​​the openings H in the SEM image can be considered to be the opening ratio of the surface 7a of the microporous layer 7.

[0088] The air permeability resistance R in the thickness direction from the surface (surface 7a of the microporous layer 7) on the separation function layer 1 side of the porous support 5 used to prepare the pervaporation membrane 10A is, for example, 100 seconds / 100 mL or more, preferably 200 seconds / 100 mL or more, more preferably 330 seconds / 100 mL or more, even more preferably 350 seconds / 100 mL or more, particularly preferably 500 seconds / 100 mL or more, and most preferably 700 seconds / 100 mL or more. The air permeability resistance R of the porous support 5 is, for example, 3000 seconds / 100 mL or less, preferably 2000 seconds / 100 mL or less, more preferably 1000 seconds / 100 mL or less. The air permeability resistance R can be determined as air permeability resistance [seconds / 100 mL] in accordance with the Oken type testing machine method defined in JIS P8117:2009. The recommended size of the test piece in the Oken testing machine method is 50 mm x 50 mm, but even if the size of the waterproof breathable member to be evaluated does not meet this recommended size, it is possible to evaluate the air permeability resistance in accordance with the Oken testing machine method by using a measuring jig.

[0089] It is preferable that the air resistance R and the weight average molecular weight M satisfy the relationship -75R+63,000≦M≦-75R+135,000.

[0090] 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.

[0091] The thickness of the microporous layer 7 is, for example, 1 μm or more, and may be 5 μm or more, or even 10 μm or more. The thickness of the microporous layer 7 is, for example, 100 μm or less, and may be 50 μm or less.

[0092] The surface of the porous support 5 (surface 7a of the microporous layer 7) in contact with the separation 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.

[0093] (Method for manufacturing pervaporation membrane) The pervaporation membrane 10A can be produced, for example, by forming a separation function layer 1 on the microporous layer 7 of the porous support 5. In detail, first, a coating liquid containing the material of the separation function layer 1 is prepared. The coating liquid is, for example, a silicone resin composition (an addition type silicone resin composition, a condensation type silicone resin composition, or a UV-curable silicone resin composition). Next, the coating liquid is applied to the microporous layer 7 of the porous support 5 to obtain a coating film. At this time, a portion of the coating liquid is impregnated into the microporous layer 7. By curing the coating film and the coating liquid impregnated into the microporous layer 7, the separation function layer 1 and a filler in the pores of the microporous layer 7 are formed. Typically, the coating film (separation function layer 1) and the coating liquid (filler) impregnated into the microporous layer 7 are cured integrally, forming the separation function layer 1 and a filler connected to the separation function layer 1. Curing can be performed at room temperature or in a heated environment. Curing can also be carried out by irradiation with active energy rays such as UV rays.

[0094] When the coating film and the coating liquid impregnated into the microporous layer 7 are cured by heating, the heating conditions are not particularly limited. For example, the heating temperature of the coating film may be 80°C or higher, 90°C or higher, 100°C or higher, or even 120°C or higher. The higher the heating temperature, the more sufficiently the curing reaction of the components in the silicone resin composition proceeds. The upper limit of the heating temperature is not particularly limited and is, for example, 200°C. The heating time can be adjusted appropriately depending on the composition of the silicone resin composition used.

[0095] The viscosity of the coating liquid at 25°C may be 0.05 Pa·s or more and 150 Pa·s or less, 0.05 Pa·s or more and 125 Pa·s or less, 0.05 Pa·s or more and 50 Pa·s or less, 0.05 Pa·s or more and 10 Pa·s or less, 0.1 Pa·s or more and 5 Pa·s or less, 0.3 Pa·s or more and 3 Pa·s or less, or even 0.4 Pa·s or more and 3 Pa·s or less.

[0096] (Uses of Pervaporation Membrane) The pervaporation membrane 10A of this embodiment is suitable for use in, for example, 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, when the organic compound C has a high concentration in an aqueous solution, it 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, the organic compound C may not generate an aqueous phase and an organic phase.

[0097] 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.

[0098] 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 n-butanol, 2-butanol, isopropanol, and ethanol being preferred, and n-butanol and isopropanol being more preferred. Examples of the aryl alcohol include phenol, etc.

[0099] 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.

[0100] The ester may be a fatty acid alkyl ester composed only of an alkyl group and an ester group, such as ethyl acetate.

[0101] 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).

[0102] 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 %.

[0103] 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.

[0104] 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.

[0105] (Pervaporation Membrane Characteristics) The pervaporation membrane 10A of this embodiment tends to have good separation performance for separating organic compounds C from aqueous solution S (particularly, the flux of permeating fluid (organic compounds C) that permeates the pervaporation membrane).

[0106] In the pervaporation membrane 10A, the separation factor of the organic compound C relative to water is not particularly limited. For example, the separation factor α1 of isopropanol (IPA) relative to water in the pervaporation membrane 10A is, for example, 5 or more, and may be 8 or more, 9 or more, or even 10 or more. The upper limit of the separation factor α1 is, for example, 100.

[0107] The separation factor α1 can be measured by the following method. With a mixed liquid consisting of IPA and water in contact with one side of the pervaporation membrane 10A (e.g., the main surface of the pervaporation membrane 10A on the separation function layer 1 side), the space adjacent to the other side of the pervaporation membrane 10A (e.g., the main surface of the pervaporation membrane 10A on the porous support 5 side) is depressurized. This results in a permeated fluid that has permeated the pervaporation membrane 10A. The weight ratio of water and the weight ratio of IPA in the permeated fluid are measured. In the above operation, the IPA content in the mixed liquid is 10 wt %. The mixed liquid that is brought into contact with the pervaporation membrane 10A has a temperature of 40°C. The space adjacent to the other side of the pervaporation membrane 10A is depressurized to 1.5 kPa. The separation factor α1 can be calculated from the following formula. In the formula, X A and X Bare the weight ratios of IPA and water in the mixed liquid, respectively. A and Y B are the weight ratios of IPA and water in the permeated fluid that has permeated the pervaporation membrane 10A, respectively. Separation coefficient α1=(Y A / Y B ) / (X A / X B )

[0108] Under the measurement conditions for the separation factor α1, the flux f1 of IPA permeating the pervaporation membrane 10A is not particularly limited and may be, for example, 0.05 kg / m 2 / hr or more, and may be 0.10 kg / m 2 / hr or more, 0.20kg / m 2 / hr or more, 0.30kg / m 2 / hr or more, and even 0.35 kg / m 2 The flux f1 of IPA permeating the pervaporation membrane 10A may be 1.0 kg / m 2 / hr or less, and may be 0.9 kg / m 2 / hr or less, and even 0.8 kg / m 2 / hr or less.

[0109] In this embodiment, the separation functional layer 1 tends to reduce the decrease in separation performance even when there are defects on the surface of the separation functional layer 1. Therefore, the pervaporation membrane 10A has a good separation coefficient and a good flux of the organic compound C permeating the pervaporation membrane when separating the organic compound C from the aqueous solution S, even when there are defects on the surface of the separation functional layer 1.

[0110] As an example, the separation factor α2 of IPA relative to water of the pervaporation membrane 10A after performing Test 1 below may be, for example, 5 or more, 8 or more, 9 or more, or even 10 or more. The upper limit of the separation factor α2 is, for example, 100. The separation factor α2 can be measured using the same method as the separation factor α1, except that the pervaporation membrane 10A after Test 1 is used. Test 1 is a scratch test using a pencil hardness tester and is performed as follows. Test 1: The pencil hardness tester is set so that the tip of a pencil with a pencil hardness of 6B applies a load of 750±10 g to the surface of the separation functional layer 1 of the pervaporation membrane 10A. With the pencil angle fixed at 45±1° relative to the direction of travel, the pencil is run through the pencil hardness tester at a speed of 0.5 to 1.0 mm / s to scratch a 7.5 cm width on the surface of the separation functional layer 1. In measuring the separation factor α2, a circular cut out of the pervaporation membrane 10A having a diameter equal to the 7.5 cm scratch made in Test 1 is used as the measurement membrane.

[0111] Under the measurement conditions for the separation factor α2 of the pervaporation membrane 10A after performing the above-mentioned test 1, the flux f2 of IPA permeating the pervaporation membrane 10A is, for example, 0.05 kg / m 2 / hr or more, and may be 0.10 kg / m 2 / hr or more, 0.20kg / m 2 / hr or more, 0.30kg / m 2 / hr or more, and even 0.35 kg / m 2 / hr or more. The IPA flux f2 is 1.0 kg / m 2 / hr or less, and may be 0.9 kg / m 2 / hr or less, and even 0.8 kg / m 2 / hr or less.

[0112] The pervaporation membrane 10A of this embodiment tends to have good adhesion between the separation function layer 1 and the porous support 5. As an example, the peel strength of the pervaporation membrane 10A measured by the following test 2 may be, for example, 0.15 N / 20 mm or more, 0.3 N / 20 mm or more, 0.4 N / 20 mm or more, 0.5 N / 20 mm or more, 0.7 N / 20 mm or more, or even 0.8 N / 20 mm or more. The upper limit of the peel strength is not particularly limited and is, for example, 20 N / 20 mm. Test 2: The pervaporation membrane 10A is cut into a width of 20 mm and a length of 150 mm to prepare a test specimen. Using the test specimen, the separation function layer 1 is peeled off from the porous support 5 at a peel angle of 180° and a tensile speed of 300 mm / min.

[0113] The above test 2 is carried out in detail by the following method. First, the pervaporation membrane 10A to be evaluated is cut into a width of 20 mm x length of 150 mm to prepare a test piece. Next, the entire surface of the porous support 5 provided on the test piece is superimposed on an acrylic test plate via double-sided tape (e.g., Nitto Denko Corporation, No. 5000NS), and a 2 kg roller is moved back and forth once to press them together. The acrylic test plate has a size of, for example, a width of 150 mm x length of 150 mm. Next, the separation function layer 1 is manually peeled off from the porous support 5 by 90 mm in the direction from one end of the test piece to the other end. Using a commercially available tensile tester, the peeled separation function layer 1 and the vicinity of one end of the test piece are gripped with a chuck, and the remaining separation function layer 1 is peeled off from the porous support 5 at a peel angle of 180 ° and a tensile speed of 300 mm / min. The average value of the peel force at this time is specified as peel strength A. The initial distance between the chucks of the tensile tester is 150 mm, and the test is carried out in an atmosphere of 25°C.

[0114] In the above test 2, the separation functional layer 1 is sufficiently fixed to the porous support 5, so that the separation functional layer 1 cannot be peeled off by hand from the porous support 5, and if an attempt is made to peel it off forcefully, the separation functional layer 1 may break. This phenomenon is presumed to be caused by the above peel strength (N / 20 mm) being greater than the breaking strength (N / 20 mm) of the separation functional layer 1. Therefore, in this case, the breaking strength of the separation functional layer 1 is separately specified, and the above peel strength can be considered to be equal to or greater than the breaking strength (i.e., peel strength (N / 20 mm) ≧ breaking strength (N / 20 mm)).

[0115] The breaking strength of the separation functional layer 1 can be determined by the following method. First, a layer having the same composition and thickness as the separation functional layer 1 of the pervaporation membrane 10A is formed on a release liner, and the release liner is removed to form a free-standing membrane of the separation functional layer 1. Next, the free-standing membrane of the separation functional layer 1 is cut into a width of 20 mm and a length of 60 mm to form a test piece. The test piece is set in a commercially available tensile tester, and a tensile test is performed under the following measurement conditions. Measurement conditions: Temperature: 25°C, Tensile direction: Longitudinal direction of the test piece, Initial chuck distance: 20 mm, Tensile speed: 300 mm / min

[0116] In the tensile test, the strength B (N / mm 2 Strength B (N / mm 2 ), the thickness (mm) of the separation functional layer 1, and the width (20 mm) of the test piece, the breaking strength (N / 20 mm) can be calculated using the following formula: Breaking strength (N / 20 mm) = Strength B (N / mm 2 ) x thickness (mm) x 20 x (1 / 20)

[0117] <Modified example of pervaporation membrane> Figure 2 is a cross-sectional view schematically showing a modified example of the pervaporation membrane. As shown in Figure 2, in the pervaporation membrane 10B, the separation functional layer 1 has a matrix 2 containing a polymer P and a filler 3 dispersed in the matrix 2. Except for the above, the structure of the pervaporation membrane 10B is the same as that of the pervaporation membrane 10A. Therefore, elements common to the above-mentioned pervaporation membrane 10A and the modified pervaporation membrane 10B are given the same reference numerals, and their description may be omitted. In other words, the descriptions of each embodiment can be mutually applied as long as there is no technical contradiction. Furthermore, as long as there is no technical contradiction, each embodiment may be combined with each other.

[0118] As described above, in the pervaporation membrane 10B, the separation functional layer 1 further includes filler 3. All or part of the filler 3 is embedded in the matrix 2. Within the matrix 2, all of the filler 3 may be spaced apart from one another, or may be partially aggregated.

[0119] The polymer P contained in the matrix 2 is typically a silicone resin, such as those described above for the pervaporation membrane 10A.

[0120] The filler 3 includes an inorganic material such as zeolite, silica, or bentonite. The filler 3 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 polymer P (particularly silicone resin) contained in the matrix 2. Increasing the free volume of the resin tends to improve the separation characteristics of the pervaporation membrane 10B, particularly the flux of the permeating fluid (organic compound C) that permeates the pervaporation membrane. The filler 3 allows for appropriate adjustment of the viscosity of the resin composition, which tends to facilitate the preparation of a resin composition suitable for coating.

[0121] Silica usually means silicon dioxide. Filler 3 may be a silica filler containing silicon dioxide as a main component. Silica filler does not have, for example, a crystalline structure. Silica filler can be produced, for example, by reacting metal silicon with oxygen. Silica filler can also be produced by a sol-gel method, a precipitation method, an aqueous solution wet method, or the like. Filler 3 may be composed essentially of silicon dioxide alone. Silica filler does not need to have micropores with a diameter of 2 nm or less.

[0122] However, the filler 3 may also contain zeolite. Examples of zeolites contained in the filler 3 include high-silica zeolites having a high ratio of silica to alumina, and silicalites that do not contain alumina. Examples of fillers 3 that contain high-silica zeolites 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. The filler 3 containing zeolite may have micropores with a diameter of 2 nm or less, mesopores with a diameter of 2 nm to 50 nm, or macropores with a diameter of 50 nm or more.

[0123] The filler 3, particularly the silica filler, preferably has a surface modified with a modifying group containing a hydrocarbon group. In other words, the filler 3 is preferably surface-modified with a modifying group. The surface-modified filler 3 has high dispersibility in the resin and is suitable for suppressing the occurrence of cracks during the production of the separation functional layer 1, etc.

[0124] 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.

[0125] 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.

[0126] 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 3 with a known silane coupling agent.

[0127] 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.

[0128] From the viewpoint of dispersibility in the resin, it is preferable that the filler 3 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 3 is small. Whether the filler 3 is sufficiently surface-modified with a modifying group can be determined, for example, from the pH of the dispersion of the filler 3 or the Hansen solubility parameter (HSP value) of the filler 3. The Hansen solubility parameter is obtained by dividing the solubility parameter introduced by Hildebrand 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 "Hansen Solubility Parameters; A Users Handbook (CRC Press, 2007)" and the like.

[0129] In this embodiment, the pH of the dispersion of filler 3 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 3 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.

[0130] The shape of the filler 3 is, for example, particulate. In this specification, "particulate" includes spherical, ellipsoidal, scaly, and fibrous shapes. The filler 3 may be powdery. The average particle size of the filler 3 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 3 is less likely to detach from the separation functional layer 1. Furthermore, a separation functional layer 1 containing filler 3 with a small average particle size tends to easily disperse stress applied to the separation functional layer 1 and has, for example, high adhesion to the porous support 5. The lower limit of the average particle size of the filler 3 is not particularly limited and is, for example, 1 nm. The average particle size of the filler 3 may be 5 nm or more, 10 nm or more, or even 100 nm or more. In this specification, the average particle size refers to the primary particle size.

[0131] The average particle size of the filler 3 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 3.

[0132] The content of filler 3 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 content of filler 3 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 content of filler 3 is 50 wt% or less, a decrease in the flux of the permeating fluid passing through the pervaporation membrane 10B can be prevented. In addition, the occurrence of defects such as cracks tends to be sufficiently suppressed during the production of the separation functional layer 1. The content of filler 3 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.

[0133] The content of the matrix 2 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 %.

[0134] The surface area D1 of the filler 3 per weight of the matrix 2 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 2 contained in the separation functional layer 1, and the weight W2 (g) of the filler 3 contained in the separation functional layer 1, the D1(m 2 / g) = D2(m 2 / g)×W2(g) / W1(g)

[0135] The pervaporation membrane 10B can be produced in the same manner as the above-described pervaporation membrane 10A by further adding filler 3 to the coating liquid containing the material of the separation functional layer 1.

[0136] <Embodiment of Membrane Separation Apparatus> As shown in Figure 3, the membrane separation apparatus 100 of this embodiment includes a pervaporation membrane 10A and a tank 23. In the membrane separation apparatus 100, the pervaporation membrane 10B described in Figure 2 can be used instead of the pervaporation membrane 10A. 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 10A.

[0137] Pervaporation membrane 10A is disposed inside tank 23. Inside tank 23, pervaporation membrane 10A separates first chamber 21 from second chamber 22. Pervaporation membrane 10A extends from one of a pair of walls of tank 23 to the other.

[0138] 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 permeation space (second chamber 22). The outlet 21b is an opening for discharging the aqueous solution S that has not permeated the pervaporation membrane 10A (non-permeated fluid S2) from the supply space (first chamber 21). The inlet 21a, the outlet 21b, and the outlet 22a are each formed, for example, on a wall surface of the tank 23.

[0139] The membrane separation apparatus 100 is suitable for a continuous membrane separation method, but may also be used for a batch membrane separation method.

[0140] (Method of Operating 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 21a. This allows the aqueous solution S to come into contact with one surface of the pervaporation membrane 10A (e.g., the main surface on the separation functional layer 1 side).

[0141] Next, with the aqueous solution S in contact with the one surface of the pervaporation membrane 10A, the space adjacent to the other surface of the pervaporation membrane 10A (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.

[0142] 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 10A. 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.

[0143] 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.

[0144] As described above, the pervaporation membrane 10A 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.

[0145] <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 10A (or a pervaporation membrane 10B).

[0146] 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.

[0147] In addition to the pervaporation membrane 10A, the laminate 27 further includes a feed-side channel material 28 and a permeate-side channel material 29. The laminate 27 is wound around the central tube 26. The membrane separation device 110 may further include an exterior material (not shown).

[0148] 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.

[0149] 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 10A 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.

[0150] <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.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] 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.

[0157] 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.

[0158] Unless otherwise specified, each of the paths of the membrane separation system 200 is made up of, for example, metal or resin piping.

[0159] 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.

[0160] <Preparation of Pervaporation Membrane> (Example 1) A silicone resin composition (coating liquid) was prepared by adding 2 parts by weight of a curing agent containing polyorganosiloxane P1 (SRX212 containing a platinum catalyst, manufactured by Dow-Toray Industries, Inc.) to 100 parts by weight of a silicone base material (BY24-489, manufactured by Dow-Toray Industries, Inc.), which is a polyorganosiloxane mixture. A coating film (thickness 10 μm) was obtained by applying the coating liquid onto a porous support. CF-30S manufactured by Nitto Denko Corporation (a laminate of a polysulfone microporous layer and a PET nonwoven fabric) was used as the porous support. The coating film was formed on the polysulfone microporous layer of CF-30S. In Example 1, the weight average molecular weight M of the silicone base material was 25,200.

[0161] Next, the coated film was heated at 150° C. for 10 minutes to be cured, thereby preparing a separation functional layer having a thickness of 4 μm. In this manner, the pervaporation membrane of Example 1 was prepared.

[0162] (Example 2) To 90 parts by weight of a silicone base material (BY24-489, manufactured by Dow Toray Industries, Inc.), which is a polyorganosiloxane mixture, 2 parts by weight of a curing agent containing polyorganosiloxane P1 (SRX212 containing a platinum catalyst, manufactured by Dow Toray Industries, Inc.) was added, and 10 parts by weight of a silica filler (manufactured by Nippon Aerosil Co., Ltd., AEROSIL (registered trademark) RX50) was added to obtain a coating solution. Except for the above, a pervaporation membrane of Example 2 having a 4 μm thick separation functional layer was prepared in the same manner as in Example 1. In Example 2, the weight average molecular weight M of the silicone base material was 25,200.

[0163] Example 3 10 parts by weight of a curing agent containing polyorganosiloxane P2 (CAT-106F, manufactured by Shin-Etsu Silicones Co., Ltd.) was added to 100 parts by weight of a silicone base material (KE-106F, manufactured by Shin-Etsu Silicones Co., Ltd.), which is a polyorganosiloxane mixture, to form a coating solution. A pervaporation membrane of Example 3 having a 5 μm thick separation functional layer was produced in the same manner as in Example 1, except for the above. In Example 3, the weight average molecular weight M of the silicone base material was 50,800.

[0164] Example 4 A pervaporation membrane of Example 4 having a 4 μm-thick separation functional layer was prepared in the same manner as in Example 3, except that the porous support was changed to RS-50 manufactured by Nitto Denko Corporation.

[0165] Example 5 50 parts by weight of a silicone polyorganosiloxane mixture (KE-1935A, manufactured by Shin-Etsu Silicones Co., Ltd.) was added to 50 parts by weight of a silicone polyorganosiloxane mixture (KE-1935B, manufactured by Shin-Etsu Silicones Co., Ltd.), and this was used as a coating solution. A pervaporation membrane of Example 5 having a 7 μm thick separation functional layer was produced in the same manner as in Example 4, except for the above. In Example 5, the weight average molecular weight M of the silicone was 97,500.

[0166] Example 6 A pervaporation membrane of Example 6 having a 7 μm-thick separation functional layer was produced in the same manner as in Example 5, except that the porous support was changed to NTU-3175 manufactured by Nitto Denko Corporation.

[0167] Comparative Example 1 A pervaporation membrane of Comparative Example 1 having a 2 μm-thick separation functional layer was produced in the same manner as in Example 1, except that the porous support was changed to RS-50 (a laminate of a PVDF microporous layer and a PET nonwoven fabric) manufactured by Nitto Denko Corporation.

[0168] Comparative Example 2 A pervaporation membrane of Comparative Example 2 having a 2 μm-thick separation functional layer was produced in the same manner as in Example 2, except that the porous support was changed to RS-50 manufactured by Nitto Denko Corporation.

[0169] Comparative Example 3 A pervaporation membrane of Comparative Example 3 having a 2 μm-thick separation functional layer was produced in the same manner as in Example 1, except that the porous support was changed to NTU-3175 manufactured by Nitto Denko Corporation (a laminate of a microporous layer made of polysulfone and a PET nonwoven fabric).

[0170] Comparative Example 4 A pervaporation membrane of Comparative Example 4 having a 2 μm-thick separation functional layer was produced in the same manner as in Example 2, except that the porous support was changed to NTU-3175 manufactured by Nitto Denko Corporation.

[0171] Comparative Example 5 A pervaporation membrane of Comparative Example 5 having a 10 μm-thick separation functional layer was produced in the same manner as in Example 5, except that the porous support was changed to CF30-S manufactured by Nitto Denko Corporation.

[0172] [Opening Rate] The opening rate of the surface (surface 7a of the microporous layer) facing the separating functional layer of the porous support used to prepare the pervaporation membrane was measured by the method described above.

[0173] [Average Diameter] For the porous support used in producing the pervaporation membrane, the average diameter L of the openings H on the surface facing the separation functional layer (surface 7a of the microporous layer) was determined by the method described above. Figure 6 shows the relationship between the average diameter L and the weight average molecular weight M of the polyorganosiloxane of the silicone resin composition for Examples 1 to 6 and Comparative Examples 1 to 5.

[0174] [Air Permeability Resistance] The air permeability resistance R of the porous support used to prepare the pervaporation membrane was measured in the thickness direction from the surface of the microporous layer on the separating function layer side by the method described above. Figure 7 shows the relationship between the air permeability resistance R and the weight average molecular weight M of the polyorganosiloxane of the silicone resin composition for Examples 1 to 6 and Comparative Examples 1 to 5.

[0175] [Penetration ratio] The penetration ratio of the silicone resin constituting the separation functional layer into the microporous layer of the fabricated pervaporation membrane was determined by the method described above. Elemental analysis based on SEM-EDX was performed using a scanning electron microscope (SU-3800, manufactured by Hitachi High-Tech Corporation).

[0176] [Peel Strength] The above test was performed on the prepared pervaporation membrane to measure the peel strength. The tensile tester used was an Autograph AGS-50NX manufactured by Shimadzu Corporation. In Examples 1 to 6 and Comparative Examples 1 to 5, the separation functional layer was sufficiently fixed to the porous support, and the separation functional layer could not be peeled off from the porous support by hand; attempting to peel it off forcefully caused the separation functional layer to break. In this case, the breaking strength of the separation functional layer was measured using the method described above. As described above, the peel strength can be considered to be a value equal to or greater than the breaking strength.

[0177] [PV Performance] The separation factor α1 of the pervaporation membrane for isopropanol (IPA) relative to water before and after Test 1 was measured using the following method.

[0178] First, a flat membrane-shaped 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%. 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 1.5 kPa while stirring the mixed liquid using a stirrer placed in the cell. As a result, the mixed liquid permeated through the pervaporation membrane, and a gaseous permeation fluid was obtained. The gaseous permeation fluid was cooled using 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 α1, separation factor α2, the flux f1 of IPA permeating the pervaporation membrane before test 1 was performed, and the flux f2 of IPA permeating the pervaporation membrane after test 1 were calculated.

[0179]

[0180] The abbreviations in Table 1 are as follows: BY24489: silicone base (manufactured by Dow-Toray Industries, Inc., BY24-489) KE106F: silicone base (manufactured by Shin-Etsu Silicones, KE-106F) KE1935: silicone base (manufactured by Shin-Etsu Silicones, KE-1935A) RX50: silica filler (manufactured by Nippon Aerosil Co., Ltd., AEROSIL (registered trademark) RX50, surface modifying group: trimethylsilyl (TMS) group) CF30S: laminate of polysulfone microporous layer and PET nonwoven fabric (manufactured by Nitto Denko Corporation, CF30-S) RS50: laminate of PVDF microporous layer and PET nonwoven fabric (manufactured by Nitto Denko Corporation, RS-50) NTU3175: laminate of polysulfone microporous layer and PET nonwoven fabric (manufactured by Nitto Denko Corporation, NTU-3175)

[0181] The pervaporation membranes of Examples 1 to 6 had better separation factors α2 and flux f2 of IPA permeating the pervaporation membrane after Test 1 than the pervaporation membranes of Comparative Examples 1 to 4. Furthermore, the pervaporation membranes of Examples 1 to 6 had better initial separation factors α1 and flux f1 of IPA permeating the pervaporation membrane than the pervaporation membranes of Comparative Examples 1 to 4. The pervaporation membrane of Comparative Example 5 had a good initial separation factor α1 and flux f1 of IPA permeating the pervaporation membrane, but the adhesion between the separation functional layer and the porous support was low, so the separation functional layer peeled off after Test 1. Therefore, the pervaporation membrane of Comparative Example 5 could not measure the flux f2 of IPA permeating the pervaporation membrane after Test 1, and the separation factor α2 was 0. From the above, the pervaporation membranes of Examples 1 to 6 have sufficient separation performance even when defects occur, and can reduce the deterioration of separation performance when defects occur in the separation functional layer. Furthermore, the pervaporation membranes of Examples 1 to 6 had a peel strength between the separating functional layer and the porous support that was equal to or greater than the breaking strength of the separating functional layer, demonstrating good adhesion.

[0182] 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 containing a polymer; and a porous support supporting the separation functional layer, wherein the porous support has a main body and a microporous layer disposed on the main body, the microporous layer being positioned between the main body and the separation functional layer, and the polymer being present within the microporous layer from the surface of the microporous layer facing the separation functional layer along the thickness direction of the microporous layer to position X within the microporous layer.

2. The pervaporation membrane according to claim 1, wherein the distance in the thickness direction from the surface of the microporous layer to the position X is 10% or more and 70% or less of the thickness of the microporous layer.

3. The pervaporation membrane of claim 1, wherein a filler is present within the pores of said microporous layer, said filler comprising said polymer.

4. The pervaporation membrane according to claim 3, wherein the filler and the separation functional layer are connected.

5. The pervaporation membrane of claim 1, wherein the polymer is a silicone resin.

6. The pervaporation membrane of claim 5, wherein the silicone resin is formed from an addition type silicone resin composition.

7. The pervaporation membrane according to claim 5, wherein the silicone resin is formed from a silicone resin composition containing 5 wt % or less of a solvent.

8. The pervaporation membrane of claim 1, wherein the microporous layer comprises polysulfone.

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

10. The pervaporation membrane of claim 9, wherein the filler comprises silica.

11. The pervaporation membrane of claim 9, wherein the filler has a surface modified with a modifying group containing a hydrocarbon group.

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

13. The pervaporation membrane of claim 12, wherein the organic compound is an alcohol.

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