Pervaporation membrane

Abstract

Provided is a pervaporation membrane suitable for performing an operation for separating a volatile organic compound from an aqueous solution containing the organic compound for a long period of time. A pervaporation membrane 10A according to the present invention is provided with a separation function layer 1 containing a silicone resin. The ratio R of the value obtained by subtracting the Young's modulus A1 from the Young's modulus A2 (MPa) of the separation function layer 1 after the test is performed to the Young's modulus A1 (MPa) of the separation function layer 1 before the test is performed is-30% or more. Test: the separation function layer (1) is immersed in a mixed liquid (L) obtained from n-butanol and water for three weeks. The separation function layer (1) is taken out from the mixed liquid (L), and the separation function layer (1) is dried. Here, the content of n-butanol in the mixed liquid L is 1.0 wt%, and the temperature of the mixed liquid L is 80 DEG C.

Description

Technical Field

[0001] The present invention relates to pervaporation membranes. Background Art

[0002] As a method for obtaining a valuable substance derived from non-petroleum, a method for utilizing fermentation based on microorganisms is known. For example, a method for producing volatile organic compounds (fermentation products) such as alcohol by fermenting carbon sources such as glucose using microorganisms has been developed. The fermentation of the carbon source is carried out, for example, in an aqueous solution. In this method, if the content of the fermentation product in the aqueous solution increases, the fermentation based on microorganisms is sometimes stopped. In order to continuously manufacture the fermentation product based on microorganisms, it is necessary to separate the fermentation product from the aqueous solution.

[0003] As an example of a method for separating a volatile organic compound from an aqueous solution containing the organic compound, a pervaporation method (pervaporation method) using a pervaporation membrane can be cited. The pervaporation method is suitable for separating volatile organic compounds from aqueous solutions containing various substances. Compared with the distillation method, the pervaporation method also tends to suppress energy consumption and carbon dioxide emissions. A specific example of the material of the pervaporation membrane used in the pervaporation method is a silicone resin (for example, Patent Document 1).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 4899122 Summary of the invention

[0007] Problems to be solved by the invention

[0008] According to the research of the inventors of the present application, conventional pervaporation membranes containing silicone resins are prone to deterioration due to long-term operation of separating volatile organic compounds from aqueous solutions containing the organic compounds. It is presumed that the deterioration of the pervaporation membrane is caused by the hydrolysis of the silicone resin. When the pervaporation membrane deteriorates, cracks are generated in the pervaporation membrane, and the separation performance of the pervaporation membrane also tends to be greatly reduced. Cracks are particularly significantly generated when fillers are added to the pervaporation membrane.

[0009] Therefore, an object of the present invention is to provide a pervaporation membrane suitable for long-term separation of volatile organic compounds from an aqueous solution containing the organic compounds.

[0010] Means for solving problems

[0011] The inventors of the present application have conducted intensive studies and, as a result, have newly discovered that the Young's modulus of a separation functional layer included in a pervaporation membrane can be used as an indicator of deterioration, thereby completing the present invention.

[0012] The present invention provides a pervaporation membrane having a separation functional layer containing a silicone resin.

[0013] The ratio R of the value obtained by subtracting the Young's modulus A1 (MPa) of the separation functional layer after the test from the Young's modulus A2 (MPa) of the separation functional layer after the test to the Young's modulus A1 (MPa) of the separation functional layer before the test is -30% or more.

[0014] Test: The separation functional layer was immersed in a mixed liquid of n-butanol and water for 3 weeks. The separation functional layer was taken out from the mixed liquid and dried. The content of n-butanol in the mixed liquid was 1.0 wt %, and the temperature of the mixed liquid was 80° C.

[0015] Furthermore, the present invention provides a pervaporation membrane comprising a separation functional layer containing a silicone resin.

[0016] The tin content in the separation functional layer is 1100 wtppm or less.

[0017] Effects of the Invention

[0018] According to the present invention, it is possible to provide a pervaporation membrane suitable for performing an operation of separating volatile organic compounds from an aqueous solution containing the organic compounds for a long period of time. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] [ Figure 1 ] is a cross-sectional view schematically showing a permeation vaporization membrane according to one embodiment of the present invention.

[0020] [ Figure 2 ] is a cross-sectional view schematically showing a modified example of the pervaporation membrane.

[0021] [ Figure 3 ] is a schematic cross-sectional view of a membrane separation device equipped with a pervaporation membrane.

[0022] [ Figure 4 ] is a stereoscopic diagram schematically showing a modified example of the membrane separation device.

[0023] [ Figure 5 ] is a schematic diagram showing an example of a membrane separation system. DETAILED DESCRIPTION

[0024] A pervaporation membrane according to a first aspect of the present invention is a pervaporation membrane including a separation functional layer containing a silicone resin.

[0025] The ratio R of the value obtained by subtracting the Young's modulus A1 (MPa) of the separation functional layer after the test from the Young's modulus A2 (MPa) of the separation functional layer after the test to the Young's modulus A1 (MPa) of the separation functional layer before the test is -30% or more.

[0026] Test: The separation functional layer was immersed in a mixed liquid of n-butanol and water for 3 weeks. The separation functional layer was taken out from the mixed liquid and dried. The content of n-butanol in the mixed liquid was 1.0 wt %, and the temperature of the mixed liquid was 80° C.

[0027] In a second aspect of the present invention, for example, in the pervaporation membrane according to the first aspect, the ratio R is 30% or less.

[0028] In a third aspect of the present invention, for example, in the pervaporation membrane according to the first or second aspect, the Young's modulus A1 is 0.1 MPa or more.

[0029] 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 content of tin in the separation functional layer is 1100 wtppm or less.

[0030] A fifth aspect of the present invention is a pervaporation membrane comprising a separation functional layer containing a silicone resin.

[0031] The tin content in the separation functional layer is 1100 wtppm or less.

[0032] 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 silicone resin is formed of an addition-type silicone resin composition.

[0033] In a seventh aspect of the present invention, for example, in the pervaporation membrane according to the sixth aspect, the addition-type silicone resin composition contains polyorganosiloxane P1 having an alkenyl group and polyorganosiloxane P2 having a hydrosilyl group.

[0034] In an eighth aspect of the present invention, for example, in the pervaporation membrane according to the sixth or seventh aspect, the addition-type silicone resin composition contains a curing catalyst containing platinum.

[0035] 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 includes a filler.

[0036] In a tenth aspect of the present invention, for example, in the pervaporation membrane according to the ninth aspect, the filler includes at least one selected from the group consisting of zeolite and silica.

[0037] 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.

[0038] In a twelfth aspect of the present invention, for example, in the pervaporation membrane according to the eleventh aspect, the modifying group includes at least one selected from the group consisting of an organosilyl group and a polyorganosiloxane group.

[0039] In a thirteenth aspect of the present invention, for example, the pervaporation membrane according to any one of the first to twelfth aspects is used to separate a volatile organic compound from an aqueous solution containing the organic compound.

[0040] In a fourteenth aspect of the present invention, for example, in the pervaporation membrane according to the thirteenth aspect, the organic compound is a fermentation product produced by a microorganism.

[0041] Hereinafter, the present invention will be described in detail, but the following description is not intended to limit the present invention to specific embodiments.

[0042] <Embodiment of pervaporation membrane>

[0043] like Figure 1 As shown, the pervaporation membrane 10A of the present embodiment includes a separation functional layer 1 including a silicone resin. The pervaporation membrane 10A is typically a membrane (separation membrane) that allows a volatile organic compound C to preferentially permeate from an aqueous solution S including the organic compound C. The pervaporation membrane 10A may further include a porous support 5 that supports the separation functional layer 1. The separation functional layer 1 has, for example, a surface that is directly in contact with the porous support 5 and a surface that is exposed to the outside of the pervaporation membrane 10. The pervaporation membrane 10 is, for example, composed only of the separation functional layer 1 and the porous support 5.

[0044] (Separation Functional Layer)

[0045] The separation functional layer 1 is, for example, a layer that allows the organic compound C to preferentially permeate the aqueous solution S, and is typically a dense layer (non-porous layer) in which no pores are observed when observed at a magnification of 5000 times using a scanning electron microscope (SEM).

[0046] In the present embodiment, the ratio R of the value obtained by subtracting the Young's modulus A1 (MPa) of the separation functional layer 1 after the test 1 described below from the Young's modulus A2 (MPa) of the separation functional layer 1 after the test 1 is -30% or more.

[0047] Test 1: The separation functional layer 1 was immersed in a mixed liquid L of n-butanol and water for 3 weeks. The separation functional layer 1 was taken out from the mixed liquid L and dried. Here, the content of n-butanol in the mixed liquid L was 1.0 wt %, and the temperature of the mixed liquid L was 80° C.

[0048] Specifically, the ratio R can be calculated by the following formula (1).

[0049] Ratio R (%) = 100 × (A2-A1) / A1 (1)

[0050] According to the research of the inventors of the present application, the separation functional layer 1 having a ratio R of -30% or more has a tendency to be suppressed from deteriorating even when in contact with an aqueous solution S containing a volatile organic compound C for a long period of time. This tendency is caused, for example, by the suppression of hydrolysis of the silicone resin contained in the separation functional layer 1. Since the pervaporation membrane 10A of the present embodiment suppresses the degradation of the separation functional layer 1, it can be said that it is suitable for the operation of separating the organic compound C from the aqueous solution S for a long period of time.

[0051] From the viewpoint of further suppressing the degradation of the separation functional layer 1, the ratio R is preferably -25% or more, and may be -20% or more, -15% or more, -10% or more, or -5% or more. It should be noted that during the above-mentioned test 1, when the curing reaction of the silicone resin in the separation functional layer 1 proceeds, the ratio R sometimes exceeds 0%. For the pervaporation membrane 10A, from the viewpoint of suppressing the change of the separation characteristics during use and stabilizing the quality, the upper limit of the ratio R is, for example, 50% or less, preferably 40% or less, 30% or less, 20% or less, and more preferably 10% or less. In particular, when the ratio R is 30% or less, there is a tendency that the separation functional layer 1 can be sufficiently suppressed from falling off due to the curing shrinkage during the long-term use of the pervaporation membrane 10A.

[0052] Young's modulus A1 can be measured by the following method. First, the porous support body 5 is removed from the pervaporation membrane 10A to produce a self-supporting membrane (single-layer membrane) of the separation functional layer 1. The method for producing a self-supporting membrane of the separation functional layer 1 is not limited to the above method. For example, a layer having the same composition and thickness as the separation functional layer 1 possessed by the pervaporation membrane 10A may be produced on a release liner, and the release liner may be removed to produce a self-supporting membrane of the separation functional layer 1. The self-supporting membrane of the separation functional layer 1 is dried as needed to be in a dry state. It should be noted that "dry state" means that the content of liquid such as water in the separation functional layer 1 is less than 0.5wt%.

[0053] Next, the self-supporting film of the separation functional layer 1 was cut into a strip shape of 10 mm×60 mm to prepare a test piece. The test piece was placed in a commercially available tensile testing machine and a tensile test was performed under the following measurement conditions.

[0054] ·Measurement conditions

[0055] Temperature: 25℃

[0056] Tensile direction: length direction of the test piece

[0057] Initial distance between chucks: 20mm

[0058] Stretching speed: 300 mm / min

[0059] Next, a stress-strain curve (SS curve) is prepared based on the result of the tensile test. A tangent line is drawn at the origin of the SS curve, and the Young's modulus A1 can be calculated from the slope of the tangent line.

[0060] The Young's modulus A1 is not particularly limited, and may be, for example, 0.1 MPa or more, 0.3 MPa or more, 0.5 MPa or more, 1.0 MPa or more, 3.0 MPa or more, 5.0 MPa or more, 8.0 MPa or more, or 10.0 MPa or more. The upper limit of the Young's modulus A1 is not particularly limited, and may be, for example, 50 MPa.

[0061] Young's modulus A2 can be measured according to the following method. First, a self-supporting film of the separation functional layer 1 is prepared by the above method. The above test 1 is performed on the self-supporting film of the separation functional layer 1. In detail, the separation functional layer 1 is immersed in the mixed liquid L at 80°C for 3 weeks. The separation functional layer 1 is taken out from the mixed liquid L and the separation functional layer 1 is dried. The drying conditions of the separation functional layer 1 are not particularly limited. For example, the drying temperature is 20°C to 60°C, and the drying time is 18 hours to 1 day. Thus, the separation functional layer 1 in a dry state is obtained.

[0062] Next, the self-supporting film of the separation functional layer 1 is cut into a strip of 10 mm × 60 mm as a test piece. The test piece is placed in a commercially available tensile testing machine for a tensile test, and based on the obtained results, the Young's modulus A2 can be calculated. It should be noted that the conditions of the tensile test and the calculation method of the Young's modulus A2 are the same as the calculation method described above for the Young's modulus A1.

[0063] The Young's modulus A2 is not particularly limited, and is, for example, 0.1 MPa or more, 0.3 MPa or more, 0.5 MPa or more, 1.0 MPa or more, 3.0 MPa or more, 5.0 MPa or more, 8.0 MPa or more, and may be 10.0 MPa or more. The upper limit of the Young's modulus A2 is not particularly limited, and is, for example, 50 MPa.

[0064] As described above, the separation functional layer 1 contains a silicone resin. The silicone resin is formed, for example, from a silicone resin composition. The silicone resin can also be formed from a condensation-type silicone resin composition or a UV-curable silicone resin composition, but is preferably formed from an addition-type silicone resin composition. In the present embodiment, the separation functional layer 1 is preferably formed from an addition-type silicone resin composition. The addition-type silicone resin composition can be cured with almost no use of metal species (especially tin) that promotes the 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 promotes the hydrolysis of the silicone resin, and is suitable for adjusting the above-mentioned ratio R to a smaller value.

[0065] [Addition type silicone resin composition]

[0066] The addition type silicone resin composition is a type of silicone resin composition that is cured by an addition reaction. The addition type silicone resin composition, for example, comprises a polyorganosiloxane P1 having an alkenyl group and a polyorganosiloxane P2 having a hydrosilane (SiH) group. The addition type silicone resin composition preferably further comprises a curing catalyst (hydrosilylation catalyst). The addition type silicone resin composition may be a commercially available silicone resin composition to which a curing catalyst is added. However, the addition type silicone resin composition may not contain a curing catalyst.

[0067] The addition-type silicone resin composition can be formed into a silicone resin by, for example, heat-treating the alkenyl group of the polyorganosiloxane P1 and the hydrosilyl group of the polyorganosiloxane P2 to react (hydrosilylation reaction). In the hydrosilylation reaction, the polyorganosiloxane P2 functions as a crosslinking agent.

[0068] Examples of the alkenyl group in the polyorganosiloxane P1 include vinyl and hexenyl groups. The number of alkenyl groups in the polyorganosiloxane P1 is, for example, 2 or more. The alkenyl group is, for example, located at the terminal of the polyorganosiloxane P1.

[0069] The polyorganosiloxane P1 is, for example, a polyalkylalkylsiloxane such as polydimethylsiloxane, polydiethylsiloxane, polymethylethylsiloxane; a polyalkylarylsiloxane; a polyorganosiloxane such as poly(dimethylsiloxane-diethylsiloxane) into which an alkenyl group is introduced.

[0070] The weight average molecular weight of the polyorganosiloxane P1 is, for example, 1000 or more, 10,000 or more, 100,000 or more, 200,000 or more, 300,000 or more, or 400,000 or more. The larger the weight average molecular weight of the polyorganosiloxane P1, the more the separation characteristics of the pervaporation membrane 10A tend to be improved. The upper limit of the weight average molecular weight of the polyorganosiloxane P1 is not particularly limited, and is, for example, 1,000,000.

[0071] The number of hydrosilyl groups in the polyorganosiloxane P2 is, for example, not less than 2. The hydrosilyl group may be located at the terminal of the polyorganosiloxane P2 or may be included in the main chain of the polyorganosiloxane P2.

[0072] Examples of the polyorganosiloxane P2 include polymethylhydrogensiloxane, poly(dimethylsiloxane-methylhydrogensiloxane), and hydrosilyl-terminated polydimethylsiloxane.

[0073] The weight average molecular weight of the polyorganosiloxane P2 is, for example, not less than 100, or not less than 10,000. The upper limit of the weight average molecular weight of the polyorganosiloxane P2 is not particularly limited, and is, for example, 1,000,000.

[0074] The weight ratio P2 / P1 of polyorganosiloxane P2 to polyorganosiloxane P1 is, for example, 500 wt% (weight %) or less, and may be 100 wt% or less, 50 wt% or less, 20 wt% or less, 10 wt% or less, or 5 wt% or less. The lower limit of the weight ratio P2 / P1 is, for example, 0.01 wt% or more.

[0075] As a curing catalyst, for example, a platinum-based catalyst can be cited. In other words, the addition-type silicone resin composition may contain a curing catalyst containing platinum. Specific examples of the platinum-based catalyst are chloroplatinic acid, an olefin complex of platinum, an olefin complex of chloroplatinic acid, and the like. As described above, the addition-type silicone resin composition may not contain a curing catalyst.

[0076] The addition type silicone resin composition may contain a compound that generates a catalyst active species that catalyzes an addition reaction when irradiated with active energy rays such as ultraviolet rays (UV). The addition type silicone resin composition containing such a compound can cause an addition reaction by, for example, UV irradiation.

[0077] The addition type silicone resin composition may 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 also be a solvent-free type that does not substantially contain an organic solvent or the like.

[0078] [Condensation type silicone resin composition]

[0079] The condensation type silicone resin composition is a silicone resin composition of the type that is cured by a condensation reaction. The condensation type silicone resin composition, for example, comprises a polyorganosiloxane P3 having a silanol (SiOH) group and a silane compound P4 having functional groups such as an alkoxy group, an alkenyl group, an acyloxy group, an amino group, a ketoxime group, and an amide group. The condensation type silicone resin composition may also include a curing catalyst. Among them, the curing catalyst used in the condensation type silicone resin composition generally includes a metal species (especially tin) that can promote the hydrolysis of the silicone resin. Therefore, in the present embodiment, the condensation type silicone resin composition preferably does not contain a curing catalyst.

[0080] The condensation type silicone resin composition can be formed into a silicone resin by, for example, heat-treating the silanol groups of the polyorganosiloxane P3 and the functional groups of the silane compound P4 to cause a reaction (condensation reaction) to proceed. In the condensation reaction, the silane compound P4 functions as a crosslinking agent.

[0081] The number of silanol groups in the polyorganosiloxane P3 is, for example, 2 or more. The silanol groups are, for example, located at the ends of the polyorganosiloxane P3. In the polyorganosiloxane P3, an alkyl group such as a methyl group or an ethyl group, a phenyl group, etc. may be introduced as a substituent of a side chain.

[0082] The polyorganosiloxane P3 is, for example, a product obtained by introducing a silanol group into the polyorganosiloxane described above with respect to the polyorganosiloxane P1.

[0083] The weight average molecular weight of polyorganosiloxane P3 is, for example, 1000 or more, 10,000 or more, 100,000 or more, 200,000 or more, 300,000 or more, or 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.

[0084] As described above, the silane compound P4 has functional groups such as an alkoxy group, an alkenyloxy group, an acyloxy group, an amino group, a ketoxime group, and an amide group. As an alkoxy group, a methoxy group, an ethoxy group, etc. can be mentioned. As an alkenyloxy group, an isopropenyloxy group, etc. can be mentioned. As an acyloxy group, an acetoxy group, etc. can be mentioned. As an amino group, a dimethylamino group, a diethylamino group, an ethylmethylamino group, etc. can be mentioned. As a ketoxime group, an acetoxime group, a methylethylketoxime group, etc. can be mentioned. As an amide group, an acetamide group, an N-methylacetamide group, an N-ethylacetamide group, etc. can be mentioned. The number of functional groups in the silane compound P4 is, for example, more than 2. In detail, the silane compound P4 preferably contains an alkoxysilyl group as an alkoxy group.

[0085] 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.

[0086] The condensation type silicone resin composition may contain an organic solvent in addition to the above components. Examples of the organic solvent include the organic solvents described above for the addition type silicone resin composition. The condensation type silicone resin composition may be a solvent-free type that does not contain a solvent such as an organic solvent.

[0087] [UV curable silicone resin composition]

[0088] The UV-curable silicone resin composition is a silicone resin composition of the type that is cured by ultraviolet (UV) irradiation. The UV-curable silicone resin composition undergoes a curing reaction, for example, by free radical polymerization, free radical addition, ionic polymerization, and the like. The UV-curable silicone resin composition that undergoes a curing reaction by free radical polymerization, for example, includes a polyorganosiloxane P5 having a double bond (specifically, a carbon-carbon double bond) derived from an alkenyl group, an acryloyl group, and the like. The UV-curable silicone resin composition that undergoes a curing reaction by free radical addition, for example, includes a polyorganosiloxane P5 having a double bond (specifically, a carbon-carbon double bond) derived from an alkenyl group, an acryloyl group, and the like, and a compound P6 having a functional group such as a thiol group that can undergo free radical addition. The UV-curable silicone resin composition that undergoes a curing reaction by ionic polymerization, for example, includes a polyorganosiloxane P7 having a functional group such as an epoxy group that can undergo ionic polymerization, and a compound that produces a catalyst active species that catalyzes ionic polymerization by UV irradiation.

[0089] According to the UV curable silicone resin composition that undergoes a curing reaction by radical polymerization, for example, double bonds contained in alkenyl groups, acryloyl groups, etc. of the polyorganosiloxane P5 undergo a radical polymerization reaction by UV irradiation, thereby forming a silicone resin.

[0090] Examples of the alkenyl group of the polyorganosiloxane P5 include vinyl and hexenyl groups. The number of alkenyl groups in the polyorganosiloxane P5 is, for example, 2 or more. The alkenyl group is, for example, located at the end of the polyorganosiloxane P5. In the polyorganosiloxane P5, as a substituent of the side chain, an alkyl group such as a methyl group or an ethyl group, a phenyl group, etc. may be introduced.

[0091] The polyorganosiloxane P5 is obtained by introducing a substituent having a double bond, such as an alkenyl group or an acryloyl group, into the polyorganosiloxane described above for the polyorganosiloxane P1, for example.

[0092] The weight average molecular weight of polyorganosiloxane P5 is, for example, 1000 or more, 10,000 or more, 100,000 or more, 200,000 or more, 300,000 or more, or 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.

[0093] According to the UV curable silicone resin composition that undergoes a curing reaction by radical addition, for example, by UV irradiation, the functional group capable of radical addition contained in compound P6 is radically added to the double bond contained in the alkenyl group, acryloyl group, etc. of polyorganosiloxane P5. Thus, the radical addition reaction can proceed to form a silicone resin.

[0094] In compound P6, the functional group capable of radical addition is, for example, a thiol group, an alkylthiol group, etc. Examples of the alkylthiol group include mercaptomethyl and mercaptoethyl groups. The number of the functional groups capable of radical addition in compound P6 is, for example, 2 or more.

[0095] Compound P6 may be a polyorganosiloxane containing a functional group capable of free radical addition. The functional group is, for example, located at the end of the polyorganosiloxane. In the polyorganosiloxane, an alkyl group such as a methyl group or an ethyl group, a phenyl group, etc. may be introduced as a substituent of a side chain.

[0096] Compound P6 is, for example, a compound obtained by introducing a functional group capable of radical addition, such as a thiol group, into the polyorganosiloxane described above with respect to polyorganosiloxane P1.

[0097] The weight average molecular weight of compound P6 is, for example, 1000 or more, 10,000 or more, 100,000 or more, 200,000 or more, 300,000 or more, or 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.

[0098] According to the UV curable silicone resin composition that undergoes curing reaction by ion polymerization, for example, by UV irradiation, a catalyst active species that catalyzes ion polymerization is generated, and ion polymerizable functional groups contained in the polyorganosiloxane P7 undergo ion polymerization reaction with each other, thereby forming a silicone resin.

[0099] In the polyorganosiloxane P7, the functional group capable of ion polymerization is, for example, an epoxy group. Examples of the substituent containing the epoxy group include the epoxy group itself, a glycidyl group, a glycidyloxypropyl group, and the like. The number of the functional groups capable of ion polymerization in the polyorganosiloxane P7 is, for example, 2 or more. The functional group capable of ion polymerization is, for example, located at the end of the polyorganosiloxane P7. In the polyorganosiloxane P7, as a substituent of the side chain, an alkyl group such as a methyl group or an ethyl group, a phenyl group, and the like can be introduced.

[0100] The polyorganosiloxane P7 is obtained, for example, by introducing an ion-polymerizable functional group such as an epoxy group into the polyorganosiloxane described above for the polyorganosiloxane P1.

[0101] The weight average molecular weight of polyorganosiloxane P7 is, for example, 1000 or more, 10,000 or more, 100,000 or more, 200,000 or more, 300,000 or more, or 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.

[0102] In addition to the above-mentioned components, the UV-curable silicone resin composition may also contain an organic solvent. 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; alcohol solvents such as methanol, ethanol, and butanol, etc. The organic solvent may be used alone or in combination of two or more. The UV-curable silicone resin composition may also be a solvent-free type that does not substantially contain an organic solvent or other solvents.

[0103] The separation functional layer 1 may contain silicone resin as a main component, or may be substantially composed of silicone resin alone. The “main component” refers to the component that is contained in the largest amount by weight in the separation functional layer 1 .

[0104] The separation functional layer 1 preferably has a low content of metal species that promotes hydrolysis of the silicone resin. In particular, when the tin content in the separation functional layer 1 is 1100 wtppm or less, hydrolysis of the silicone resin hardly proceeds even when the separation functional layer 1 comes into contact with water, and the above ratio R can be easily adjusted to a high value.

[0105] From another aspect, the present invention provides a pervaporation membrane 10A comprising a separation functional layer 1 containing a silicone resin.

[0106] The tin content in the separation functional layer 1 is 1100 wtppm or less.

[0107] The content of tin in the separation functional layer 1 is preferably less than 1000wtppm, and can be less than 800wtppm, less than 500wtppm, less than 300wtppm, less than 100wtppm, less than 80wtppm, less than 50wtppm, less than 30wtppm, less than 10wtppm, less than 5wtppm, and can also be less than 1wtppm. The separation functional layer 1 may be substantially free of tin. The content of each metal species such as tin can be determined, for example, by atomic absorption spectrometry. The content of each metal species in the separation functional layer 1 can also be calculated based on the content of each metal species in the material used to make the separation functional layer 1.

[0108] The thickness of the separation functional layer 1 is, for example, 200 μm or less, 100 μm or less, or 80 μm or less. The thickness of the separation functional layer 1 may be 1.0 μm or more, 10 μm or more, or 30 μm or more.

[0109] (Porous Support)

[0110] The porous support 5 includes, for example, 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 directly in contact with the main body 6 and the separation functional layer 1. The porous support 5 is typically an ultrafiltration membrane.

[0111] The main body 6 is, for example, a fiber structure such as a woven fabric or a nonwoven fabric, and is typically 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 fibers, rayon, vinylon, acetate fibers, polyvinyl alcohol (PVA) fibers, polyamide fibers, polyolefin fibers, and polyurethane fibers. The main body 6 is, for example, a nonwoven fabric made of polyester fibers. The main body 6 has, for example, an average pore size of 1 μm to 50 μm.

[0112] Examples of the material of the microporous layer 7 include fluororesins such as polyvinylidene fluoride and polytetrafluoroethylene, polyarylethersulfones such as polysulfone and polyethersulfone, and polyimide. The microporous layer 7 has an average pore diameter of, for example, 0.01 μm to 0.4 μm.

[0113] 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 100 μm or more. The thickness of the porous support 5 may be, for example, 300 μm or less, or 200 μm or less.

[0114] (Method for manufacturing pervaporation membrane)

[0115] The permeation vaporization membrane 10A can be produced, for example, by forming a separation functional layer 1 on the microporous layer 7 of the porous support 5. In detail, first, a coating liquid containing a material for the separation functional 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). Then, a coating film is obtained by applying the coating liquid on the porous support 5. The separation functional layer 1 is formed by curing the coating film. The curing of the coating film can be carried out at room temperature or in a heated environment. The curing of the coating film can also be carried out by irradiation with active energy rays such as UV.

[0116] When the coating film is cured by heating, the heating conditions of the coating film are not particularly limited. For example, the heating temperature of the coating film may be above 80°C, above 90°C, above 100°C, or above 120°C. The higher the heating temperature of the coating film, the more fully the curing reaction of the components in the silicone resin composition proceeds. In this case, when the above-mentioned test 1 is performed, there is a tendency to suppress the ratio R from exceeding 0%. The upper limit of the heating temperature of the coating film is not particularly limited, for example, 200°C. The heating time of the coating film can be appropriately adjusted according to the composition of the silicone resin composition used.

[0117] (Application of Pervaporation Membrane)

[0118] The permeation vaporization membrane 10A of the present embodiment is suitable for use, for example, in separating organic compound C from an aqueous solution S containing volatile organic compound C. There is no particular limitation on the organic compound C as long as it is volatile. In this specification, the so-called "volatile organic compound" refers to an organic compound having a boiling point of 20°C to 260°C at atmospheric pressure (101.325 kPa). It should be noted that for organic compound C, for example, when the concentration in the aqueous solution is high, an aqueous phase containing water as the main component and an organic phase having a higher content of organic compound C than the aqueous phase are generated. However, organic compound C may not generate an aqueous phase and an organic phase.

[0119] 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 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 may have, for example, 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 1.

[0120] As the organic compound C, for example, alcohol, ketone, ester, etc. can be mentioned, typically alcohol. Alcohol can be an alkyl alcohol consisting of only an alkyl group and a hydroxyl group, or an aryl alcohol containing an aryl group and a hydroxyl group. The alkyl alcohol can be any of linear, branched, and cyclic. As the alkyl alcohol, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, isobutanol, tert-butanol, n-pentanol, etc. can be mentioned. As the aryl alcohol, for example, phenol, etc. can be mentioned.

[0121] The ketone may be a dialkyl ketone consisting only of an alkyl group and a carbonyl group. Examples of the dialkyl ketone include methyl ethyl ketone (MEK) and acetone.

[0122] The ester may be a fatty acid alkyl ester consisting only of an alkyl group and an ester group. Examples of the fatty acid alkyl ester include ethyl acetate and the like.

[0123] It should be noted that the organic compound C is not limited to the above compounds and may be an aromatic hydrocarbon such as benzene, toluene, or xylene.

[0124] The aqueous solution S may contain one organic compound C, or may contain two or more organic compounds C. The content of the organic compound C in the aqueous solution S is, for example, 0.5 wt% or more, 1 wt% or more, 2 wt% or more, or 5 wt% or more. The upper limit of the content of the organic compound C is not particularly limited, and is, for example, 50 wt%.

[0125] The organic compound C may be a fermentation product produced by microorganisms fermenting carbon sources, or may be an alcohol (bioalcohol) produced by microorganisms. 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 the fermentation liquid, and may also be waste liquid or wastewater discharged from chemical equipment, etc.

[0126] In addition to water and organic compound C, aqueous solution S may also contain other components such as microorganisms that generate fermentation products, carbon sources, nitrogen sources, inorganic ions, etc. The microorganisms that generate fermentation products are typically bacteria. As carbon sources, polysaccharides such as starch and monosaccharides such as glucose can be cited.

[0127] (Pervaporation membrane characteristics)

[0128] The separation coefficient of the organic compound C with respect to water in the pervaporation membrane 10A is not particularly limited. As an example, the separation coefficient of n-butanol (BuOH) with respect to water in the pervaporation membrane 10A is α1 BuOH For example, it may be 10 or more, 15 or more, 20 or more, 25 or more, 30 or more, or 40 or more. Separation coefficient α1 BuOH The upper limit value of is, for example, 100.

[0129] Separation coefficient α1 BuOH It can be measured by the following method. While a mixed liquid obtained from BuOH and water is in contact with one side of the pervaporation membrane 10A (for example, the main surface 10a on the separation functional layer side of the pervaporation membrane 10A), the space adjacent to the other side of the pervaporation membrane 10A (for example, the main surface 10b on the porous support body side of the pervaporation membrane 10A) is depressurized to 15 hPa. Thus, a permeating fluid passing through the pervaporation membrane 10A is obtained. The weight ratio of water and the weight ratio of BuOH in the permeating fluid are measured. In the above operation, the content of BuOH in the mixed liquid is 1.0 wt%. The temperature of the mixed liquid in contact with the pervaporation membrane 10A is 30°C. The space adjacent to the other side of the pervaporation membrane 10A is depressurized to 15 hPa. Separation coefficient α1 BuOH It can be calculated according to the following formula. In the following formula, X A and XB are the weight ratio of BuOH and the weight ratio of water in the mixed liquid respectively. A and Y B They are respectively the weight ratio of BuOH and the weight ratio of water in the permeated fluid that has permeated the pervaporation membrane 10A.

[0130] Separation coefficient α1 BuOH =(Y A / Y B ) / (X A / X B )

[0131] The above separation coefficient α1 BuOH In the measurement conditions, the flux of BuOH passing through the pervaporation membrane 10A is not particularly limited, and is, for example, 0.01 (g / min / m 2 )~10.0(g / min / m 2 ).

[0132] In this embodiment, even when the separation functional layer 1 is in contact with the aqueous solution S containing the volatile organic compound C for a long time, there is a tendency to suppress degradation. Therefore, even when the pervaporation membrane 10A is in contact with the aqueous solution S for a long time, there is a tendency that the separation performance is not easily reduced. As an example, the separation coefficient α1 of BuOH for water of the pervaporation membrane 10A before the following test 2 is performed BuOH In other words, the separation coefficient α2 of BuOH to water of the pervaporation membrane 10A after the implementation of the test 2 is BuOH Subtract separation factor α1 BuOH The ratio R1 of the obtained values ​​is -30% or more.

[0133] Test 2: Pervaporation membrane 10A was immersed in a mixed liquid L of n-butanol and water for 3 weeks. Pervaporation membrane 10A was taken out from the mixed liquid L and dried. Here, the content of n-butanol in the mixed liquid L was 1.0 wt %, and the temperature of the mixed liquid L was 80° C.

[0134] Specifically, the ratio R1 can be calculated by the following formula (2).

[0135] Ratio R1(%)=100×(α2 BuOH -α1 BuOH ) / α1 BuOH (2)

[0136] The ratio R1 is preferably -25% or more, and may be -20%, -15%, -10%, or -5%. The upper limit of the ratio R1 is, for example, 50% or less, and may be 40%, 30%, 20%, or 10% or less.

[0137] It should be noted that the separation coefficient α2 BuOH In addition to using the pervaporation membrane 10A after the experiment 2, the separation coefficient α1 BuOH The same method was used to determine the separation factor α2 BuOH For example, it may be 10 or more, 15 or more, 20 or more, 25 or more, 30 or more, or 40 or more. Separation coefficient α2 BuOH The upper limit value of is, for example, 100.

[0138] In addition, the separation coefficient α1 of the pervaporation membrane 10A for isopropyl alcohol (IPA) to water is IPA For example, it may be 5 or more, 10 or more, or 15 or more. Separation coefficient α1 IPA The upper limit value of is, for example, 100.

[0139] Separation coefficient α1 IPA In addition to using a mixed liquid with an IPA content of 5 wt%, it is possible to BuOH The same method was used for determination.

[0140] In addition, in this embodiment, the separation coefficient α1 of IPA for water of the pervaporation membrane 10A before the above-mentioned test 2 is IPA In other words, the separation coefficient α2 of IPA to water of the pervaporation membrane 10A after the implementation of the test 2 is IPA Subtract separation factor α1 IPA The ratio R2 of the obtained values ​​is -30% or more.

[0141] Specifically, the ratio R2 can be calculated by the following formula (3).

[0142] Ratio R2(%)=100×(α2 IPA -α1 IPA ) / α1 IPA (3)

[0143] The ratio R2 is preferably -25% or more, and may be -20%, -15%, -10%, or -5%. The upper limit of the ratio R2 is, for example, 50% or less, and may be 40%, 30%, 20%, or 10% or less.

[0144] It should be noted that the separation coefficient α2 IPA In addition to using the pervaporation membrane 10A after the experiment 2, the separation coefficient α1 IPA The same method was used to determine the separation factor α2 IPAFor example, it may be 5 or more, 10 or more, or 15 or more. Separation coefficient α2 IPA The upper limit value of is, for example, 100.

[0145] <Modification of pervaporation membrane>

[0146] Figure 2 FIG. 2 is a cross-sectional view schematically showing a modified example of a pervaporation membrane. Figure 2 As shown, in the pervaporation membrane 10B, the separation functional layer 1 has a base 2 containing a silicone resin and a filler 3 dispersed in the base 2. Except for the above, the structure of the pervaporation membrane 10B is the same as that of the pervaporation membrane 10A. Therefore, in the pervaporation membrane 10A and the pervaporation membrane 10B of the modified example, the same reference numerals are given to the common elements, and their descriptions are sometimes omitted. That is, the descriptions related to the various embodiments can be applied to each other as long as there is no technical contradiction. In addition, the various embodiments can be combined with each other as long as there is no technical contradiction.

[0147] As described above, in pervaporation membrane 10B, separation functional layer 1 further includes filler 3. All or part of filler 3 is embedded in matrix 2. In matrix 2, all fillers 3 may be separated from each other or partially aggregated.

[0148] Examples of the silicone resin contained in the substrate 2 include the resins described above with respect to the pervaporation membrane 10A.

[0149] The filler 3 includes, for example, an inorganic material such as zeolite, silica, and bentonite. The filler 3 includes, for example, at least one selected from the group consisting of zeolite and silica, and preferably includes silica. The filler 3 including silica tends to have excellent hydrolysis resistance compared to the filler 3 including zeolite. Furthermore, according to the filler 3 including silica, the free volume of the silicone resin contained in the substrate 2 tends to increase. If the free volume of the silicone resin increases, the separation characteristics of the pervaporation membrane 10B, especially the separation coefficient α of BuOH relative to water, tends to be improved.

[0150] Silica generally refers to silicon dioxide. Filler 3 may be a silica filler containing silicon dioxide as a main component. The silica filler, for example, does not have a crystalline structure. The silica filler, for example, can be made by reacting metallic silicon with oxygen. The silica filler can be made by a sol-gel method, a sedimentation method, an aqueous solution wet method, etc. Filler 3 may be substantially composed only of silicon dioxide.

[0151] However, the filler 3 may also contain zeolite. As the zeolite contained in the filler 3, for example, high-silicon zeolite having a high ratio of silica to alumina and silica zeolite not containing alumina can be cited. As the filler 3 containing high-silicon zeolite, HSZ (registered trademark) manufactured by Tosoh Corporation, HiSiv (registered trademark) manufactured by Union Showa Co., Ltd., USKY manufactured by Union Showa Co., Ltd., and Zeoal (registered trademark) manufactured by Nakamura Superhard Co., Ltd. can be used.

[0152] The filler 3, in particular the silica filler, for example, does not have micropores with a diameter of 2 nm or less. However, the filler 3 may also have mesopores with a diameter of 2 nm to 50 nm, or macropores with a diameter of 50 nm or more.

[0153] The filler 3, especially the silica filler, preferably has a surface modified by a modifying group containing a hydrocarbon group. In other words, the filler 3 is preferably surface-modified by the modifying group. The surface-modified filler 3 has high dispersibility in the silicone resin and is suitable for suppressing the generation of cracks in the case of preparing the separation functional layer 1, etc.

[0154] The number of carbon atoms of the hydrocarbon group contained in the modifying group is not particularly limited, and is, for example, 1 to 25. The number of carbon atoms of 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.

[0155] The modifying group may further include a silicon atom, and a hydrocarbon group may be bonded to the silicon atom. The modifying group may include 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 and diorganosilyl groups such as dimethylsilyl. Examples of the polyorganosiloxane group include dimethylpolysiloxane groups, and the like.

[0156] The surface modification using the modifying group can be performed, for example, by reacting a hydroxyl group present on the surface of the filler 3 with a known silane coupling agent.

[0157] Specific examples of surface-modified silica fillers include "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.) manufactured by Japan Aerosil Co., Ltd.

[0158] As for filler 3, from the viewpoint of dispersibility in silicone resin, it is preferred that the surface of filler 3 is sufficiently modified by modifying groups. In other words, it is preferred that the number of hydroxyl groups present on the surface of filler 3 is small. Whether filler 3 is sufficiently surface-modified by modifying groups can be judged, for example, based on the pH of the dispersion of filler 3 and the Hansen solubility parameter (HSP value) of filler 3. It should be noted that the Hansen solubility parameter is obtained by dividing the solubility parameter introduced by Hildebrand into three components: dispersion term δD, polar term δP, and hydrogen bond term δH. The details of the Hansen solubility parameters are disclosed in "Hansen Solubility Parameters; A Users Handbook (CRC Press, 2007)" and the like.

[0159] In this embodiment, the pH of the dispersion of filler 3 measured by the following test 3 is, for example, 4.0 to 9.0, or 6.0 to 8.0. The pH of the dispersion is preferably neutral (near pH 7.0). When the pH of the dispersion is neutral, it can be said that the filler 3 is sufficiently surface-modified by the modifying group, and the number of hydroxyl groups present on the surface is small.

[0160] Test 3: A dispersion was prepared by mixing water, methanol and filler 3, and the pH of the dispersion was measured. Here, the content of filler 3 in the dispersion was 4 wt %, the weight ratio of water to methanol was 1:1, and the temperature of the dispersion was 25°C.

[0161] The shape of the filler 3 is, for example, particulate. In this specification, "particulate" includes spherical, ellipsoidal, scaly and fibrous shapes. The filler 3 can also be in powder form. The average particle size of the filler 3 is not particularly limited, for example, it is less than 50μm, it can be less than 20μm, less than 10μm, less than 1μm, less than 500nm, less than 100nm, less than 50nm, less than 30nm, and can also be less than 20nm. The separation functional layer 1 containing the filler 3 with a small average particle size is easy to disperse the stress applied to the separation functional layer 1, and tends to have high adhesion with the porous support body 5. The lower limit of the average particle size of the filler 3 of the separation functional layer 1 is not particularly limited, for example, it is 1nm, and it can also be 5nm.

[0162] 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 using a transmission electron microscope. In the obtained electron microscope image, the area of ​​a specific filler 3 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 the specific filler 3. The particle sizes of any number (at least 50) of fillers 3 are calculated separately, and the average value of the calculated values ​​is regarded as the average particle size of the filler 3.

[0163] The content of the filler 3 in the separation functional layer 1 is, for example, 1 wt% or more, and may be 5 wt% or more, 10 wt% or more, 20 wt% or more, 30 wt% or more, or 40 wt% or more. The upper limit of the content of the filler 3 in the separation functional layer 1 is not particularly limited, and is, for example, 70 wt% or less, and may be less than 50 wt%. When the content of the filler 3 is less than 50 wt%, there is a tendency to fully suppress the generation of defects such as cracks during the production of the separation functional layer 1. The content of the matrix 2 in the separation functional layer 1 is not particularly limited, and is, for example, 30 wt% to 99 wt%, and may be 30 wt% to 90 wt%.

[0164] The surface area D1 of the filler 3 per unit weight of the matrix 2 is not particularly limited, and is, for example, 5 m 2 / g or more, can be 10m 2 / g or more, 20m 2 / g or more, 30m 2 / g or more, 40m 2 / g or more, and can also be 50m 2 The upper limit of the surface area D1 is not particularly limited, but is, for example, 100 m 2 The surface area D1 can be determined based on the BET specific surface area D2 (m 2 / g), the weight W1 (g) of the substrate 2 contained in the separation functional layer 1, and the weight W2 (g) of the filler 3 contained in the separation functional layer 1 are calculated according to the following formulas.

[0165] D1(m 2 / g)=D2(m 2 / g)×W2(g) / W1(g)

[0166] <Embodiment of membrane separation device>

[0167] like Figure 3 As shown in FIG. 1 , the membrane separation device 20 of the present embodiment includes a pervaporation membrane 10A and a tank 22. It should be noted that the membrane separation device 20 may include a Figure 2 The tank 22 has a first chamber 23 and a second chamber 24. The first chamber 23 functions as a supply space to which a supply fluid (specifically, the aqueous solution S described above) is supplied. The second chamber 24 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 the permeated membrane 10A.

[0168] Pervaporation membrane 10A is disposed inside tank 22. Pervaporation membrane 10A partitions first chamber 23 and second chamber 24 inside tank 22. Pervaporation membrane 10A extends from one of a pair of wall surfaces of tank 22 to the other.

[0169] The first chamber 23 has an inlet 23a and an outlet 23b. The second chamber 24 has an outlet 24a. The inlet 23a is an opening for supplying the aqueous solution S to the supply space (the first chamber 23). The outlet 24a is an opening for discharging the permeated fluid S1 from the permeation space (the second chamber 24). The outlet 23b is an opening for discharging the aqueous solution S (non-permeated fluid S2) that has not permeated the permeation vaporization membrane 10A from the supply space (the first chamber 23). Each of the inlet 23a, the outlet 23b, and the outlet 24a is formed, for example, on the wall surface of the tank 22.

[0170] The membrane separation device 20 is suitable for a flow-through (continuous) membrane separation method. However, the membrane separation device 20 can also be used for a batch-type membrane separation method.

[0171] (Method for operating membrane separation device)

[0172] The operating method of the membrane separation device 20 is implemented as follows, for example. First, the aqueous solution S is supplied to the first chamber 23 of the membrane separation device 20 through the inlet 23a. Thereby, the aqueous solution S can be brought into contact with one surface (for example, the main surface 10a) of the pervaporation membrane 10A.

[0173] Next, while the aqueous solution S is in contact with one side of the pervaporation membrane 10A, the space adjacent to the other side (e.g., the main side 10b) of the pervaporation membrane 10A is decompressed. Specifically, the pressure in the second chamber 24 is reduced through the outlet 24a. The decompression in the second chamber 24 can be performed, for example, by a decompression device such as a vacuum pump. The pressure in the second chamber 24 is, for example, 50 kPa or less, and can be 20 kPa or less, 10 kPa or less, 5 kPa or less, 3 kPa or less, or 2 kPa or less. It should be noted that, in this specification, "pressure" refers to absolute pressure unless otherwise specified.

[0174] By reducing the pressure in the second chamber 24, 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 24. In the second chamber 24, the permeated fluid S1 is typically a gas. The permeated fluid S1 is discharged to the outside of the membrane separation device 20 through the outlet 24a.

[0175] On the other hand, the content of the organic compound C in the aqueous solution S gradually decreases from the inlet 23a to the outlet 23b of the first chamber 23. The aqueous solution S (non-permeable fluid S2) treated in the first chamber 23 is discharged to the outside of the membrane separation device 20 through the outlet 23b. The non-permeable fluid S2 is typically a liquid.

[0176] As described above, the pervaporation membrane 10A can preferentially permeate the organic compound C contained in the aqueous solution S. Therefore, the permeated fluid S1 obtained by operating the membrane separation device 20 has a higher content of organic compound C than the aqueous solution S supplied to the membrane separation device 20 .

[0177] <Modification of membrane separation device>

[0178] The membrane separation device 20 may be a spiral membrane element, a hollow fiber membrane element, a coil-type membrane element in which a plurality of pervaporation membranes are stacked, a plate-and-frame membrane element, or the like. Figure 4 A spiral type membrane element is shown. Figure 4 The membrane separation device 25 includes a central tube 26 and a stack 27. The stack 27 includes the pervaporation membrane 10A (or the pervaporation membrane 10B).

[0179] The central tube 26 has a cylindrical shape. A plurality of holes or slits are formed on the surface of the central tube 26 for allowing the permeating fluid S1 to flow into the interior of the central tube 26. Examples of the material of 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.

[0180] Laminated body 27 includes, in addition to pervaporation membrane 10A, feed-side flow path material 28 and permeate-side flow path material 29. Laminated body 27 is wound around core tube 26. Membrane separation device 25 may further include an exterior material (not shown).

[0181] As the supply side flow path material 28 and the permeate side flow path material 29, for example, a net, woven fabric or knitted fabric made of a resin obtained from polyethylene, polypropylene, polyethylene terephthalate (PET), polyphenylene sulfide (PPS) or ethylene-chlorotrifluoroethylene copolymer (ECTFE) can be used.

[0182] The membrane separation device 25 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 internal space of 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 interior of the central tube 26. The permeated fluid S1 passes through the central tube 26 and is discharged to the outside. The aqueous solution S (non-permeated fluid S2) treated in the membrane separation device 25 is discharged to the outside from the other end of the wound stack 27.

[0183] <Embodiment of membrane separation system>

[0184] like Figure 5 As shown in FIG. 1 , the membrane separation system 100 of the present embodiment includes the membrane separation device 20 described above. Figure 4 The membrane separation device 25 described above is used instead of the membrane separation device 20.

[0185] The membrane separation system 100 further includes a membrane separation device 20 and a tank 30. The tank 30 stores an aqueous solution S to be supplied to the membrane separation device 20. The tank 30 may be a fermentation tank for producing an organic compound C by fermentation of a carbon source by microorganisms.

[0186] The membrane separation system 100 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 20 during operation, and is connected to the outlet 31 of the tank 30 and the inlet 23a of the membrane separation device 20. The aqueous solution supply path 70 is provided with, for example, a pump 50 for controlling the flow rate of the aqueous solution S.

[0187] The non-permeated fluid discharge path 71 is a path for discharging the non-permeated fluid S2 from the membrane separation device 20 during operation, and is connected to the outlet 23b of the membrane separation device 20. For example, a pump 51 for controlling the flow rate of the non-permeated fluid S2 is arranged in the non-permeated fluid discharge path 71. It should be noted that the pump 51 may not be arranged 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 may be configured so that the non-permeated fluid S2 is delivered 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 in the aqueous solution supply path 70 and the non-permeated fluid discharge path 71. When the non-permeated fluid S2 is delivered to the tank 30, the aqueous solution S and the non-permeated fluid S2 are mixed in the tank 30, and the content rate of the organic compound C in the aqueous solution S is reduced. When the tank 30 is a fermentation tank, the fermentation stop by the microorganisms can be suppressed by reducing the content rate of the organic compound C in the aqueous solution S, thereby continuously producing the fermented product.

[0188] The permeate fluid discharge path 72 is a path for discharging the permeate fluid S1 from the membrane separation device 20 during operation, and is connected to the outlet 24a of the membrane separation device 20. For example, a decompression device 52 is arranged in the permeate fluid discharge path 72. The decompression device 52 can reduce the pressure in the permeate space of the membrane separation device 20. The decompression device 52 is preferably a vacuum device such as a vacuum pump. The vacuum pump is typically a gas-transporting vacuum pump, and a reciprocating vacuum pump, a rotary vacuum pump, etc. can be cited. As a reciprocating vacuum pump, a diaphragm type and a swing piston type vacuum pump can be cited. As a rotary vacuum pump, there can be cited: a liquid seal pump; an oil rotary pump (rotary pump); a mechanical booster pump; various dry pumps such as roots type, claw type, screw type, turbine type, and vortex type. The pump as the decompression device 52 can also be provided with a variable speed mechanism for changing the rotation speed, etc. An example of a variable speed mechanism is an inverter that drives the motor of the pump. By controlling the rotation speed of the pump, etc. using a variable speed mechanism, the pressure of the permeate space of the membrane separation device 20 can be appropriately adjusted.

[0189] A heat exchanger for cooling the permeated fluid S1 may be further arranged in the permeated fluid discharge path 72. The gas permeated fluid S1 can be condensed by the heat exchanger. The heat exchanger is, for example, a gas-liquid heat exchanger that performs heat exchange between a cooling medium such as an antifreeze liquid and the gas permeated fluid S1. The heat exchanger may be located between the membrane separation device 20 and the pressure reducing device 52 (on the upstream side of the pressure reducing device 52), or between the pressure reducing device 52 and the recovery unit 40 described later (on the downstream side of the pressure reducing device 52).

[0190] The membrane separation system 100 further includes a recovery unit 40. The recovery unit 40 recovers the permeated fluid S1 sent from the membrane separation device 20 and can store the permeated fluid S1. The recovery unit 40 is, for example, a tank storing the permeated fluid S1. The inlet 41 of the recovery unit 40 is connected to a permeated fluid discharge path 72.

[0191] The membrane separation system 100 may further include a controller 60 for controlling the various components of the membrane separation system 100. The controller 60 is, for example, a DSP (Digital Signal Processor) including an A / D conversion circuit, an input / output circuit, an operation circuit, a storage device, etc. The controller 60 stores a program for properly operating the membrane separation system 100.

[0192] Unless otherwise specified, each path of the membrane separation system 100 is constituted by, for example, a pipe made of metal or resin.

[0193] Example

[0194] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[0195] (Example 1)

[0196] First, 54 g of toluene (special grade, manufactured by FUJIFILM Wako Pure Chemical Corporation) as a diluent solvent and 1 g of a platinum catalyst (CAT-PL-50T, manufactured by Shin-Etsu Chemical Co., Ltd.) as a curing catalyst were added to 100 g of a silicone resin composition (manufactured by Shin-Etsu Chemical Co., Ltd., KS-847T, toluene solution, solid content 30 wt%) to prepare a coating liquid (addition type silicone resin composition). The coating liquid was applied to a porous support to obtain a coating film (thickness 500 μm). As a porous support, RS-50 (a laminate of a PVDF microporous layer and a PET nonwoven fabric) manufactured by Nitto Denko Corporation was used. The coating film was formed on the PVDF microporous layer of RS-50.

[0197] Next, the coated film was heated at 90° C. for 20 minutes to be cured, thereby producing a separation functional layer having a thickness of 50 μm. Thus, the pervaporation membrane of Example 1 was obtained.

[0198] (Examples 2~4)

[0199] Pervaporation membranes of Examples 2 to 4 were obtained by the same method as in Example 1 except that the silicone resin compositions shown in Table 1 below were used.

[0200] (Example 5)

[0201] To 50 g of a silicone resin composition (KE-1935A, manufactured by Shin-Etsu Chemical Co., Ltd.), 50 g of a silicone resin composition (KE-1935B, manufactured by Shin-Etsu Chemical Co., Ltd.) was added to prepare a coating liquid (addition-type silicone resin composition). The thickness of the coating film was changed to 70 μm, and the curing temperature of the coating film was changed to 150° C., and the permeation vaporization membrane of Example 5 was obtained by the same method as in Example 1.

[0202] (Example 6)

[0203] To 100 g of a silicone resin composition (YSR3022 manufactured by Momentive Performance Materials Japan LLC), 62 g of toluene (special grade manufactured by FUJIFILM Wako Pure Chemical Corporation) as a diluent solvent and 3 g of a tin-based catalyst (YC6831 manufactured by Momentive Performance Materials Japan LLC) as a curing catalyst were added to prepare a coating liquid (condensation-type silicone resin composition). Except for this, the permeation vaporization membrane of Example 6 was obtained by the same method as Example 1.

[0204] (Example 7)

[0205] First, 46.5 g of toluene (special grade, manufactured by FUJIFILM Wako Pure Chemical Corporation) and 1.5 g of a curing agent (SILPOT184, manufactured by Dow Corning Toray Co., Ltd.) as a diluent solvent were added to 15 g of a silicone resin composition (manufactured by Dow Corning Toray Co., Ltd.) to prepare a coating liquid (addition type silicone resin composition). The coating liquid was applied to a porous support (manufactured by Nitto Denko Corporation, RS-50), but since the coating liquid penetrated into the porous support, a pervaporation membrane could not be prepared.

[0206] (Example 8)

[0207] First, 46 g of toluene (special grade, manufactured by FUJIFILM Wako Pure Chemical Corporation) as a diluent solvent, 0.73 g of a curing agent (SILPOT184, manufactured by Dow Corning Toray Co., Ltd.) and 8 g of a zeolite filler (HSZ-890, manufactured by Tosoh Corporation) were added to 7.27 g of a silicone resin composition (manufactured by Dow Corning Toray Co., Ltd.) to prepare a coating liquid (addition type silicone resin composition). The coating liquid was applied to a porous support (manufactured by Nitto Denko Corporation, RS-50), but since the coating liquid penetrated into the porous support, a pervaporation membrane could not be prepared.

[0208] (Example 9)

[0209] First, 8 g of zeolite filler (HSZ-890 made by Tosoh Corporation) and 10 g of toluene (special grade made by FUJIFILM Wako Pure Chemical Corporation) were added to 2.4 g of silicone rubber macromolecular monomer (made by Gelest Inc., DMS-S12) and stirred. 36 g of toluene (special grade made by FUJIFILM Wako Pure Chemical Corporation), 5.09 g of silicone resin composition (made by Dow Corning Toray Co., Ltd., SILPOT184) and 0.51 g of curing agent (made by Dow Corning Toray Co., Ltd., SILPOT184) were added to the solution to prepare a coating liquid (addition type silicone resin composition). The coating liquid was applied to a porous support (made by Nitto Denko Corporation, RS-50), but since the coating liquid penetrated into the porous support, a permeation vaporization membrane could not be prepared.

[0210] (Example 10)

[0211] To 50 g of a silicone resin composition (KS-847T manufactured by Shin-Etsu Chemical Co., Ltd., toluene solution, solid content 30 wt%), 15 g of a silica filler (AEROSIL RX50 manufactured by Nippon Aerosil Co., Ltd.), 87 g of toluene as a dilution solvent (special grade manufactured by FUJIFILM Wako Pure Chemical Corporation), and 0.5 g of a platinum catalyst (CAT-PL-50T manufactured by Shin-Etsu Chemical Co., Ltd.) as a curing catalyst were added to prepare a coating liquid (addition-type silicone resin composition). Except for the above, the permeation vaporization membrane of Example 10 was obtained by the same method as Example 1.

[0212] (Example 11)

[0213] A pervaporation membrane of Example 11 was obtained in the same manner as in Example 1 except that a tin catalyst (YC6831 manufactured by Momentive Performance Materials Japan LLC) was added to the coating solution so that the tin content in the separation functional layer would be 500 wtppm.

[0214] (Examples 12~13)

[0215] The pervaporation membranes of Examples 12 to 13 were obtained by the same method as in Example 11 except that the amount of the tin catalyst added was adjusted so that the tin content in the separation functional layer would be the value shown in Table 1.

[0216] [Tin content]

[0217] The weight of tin contained in the separation functional layer is calculated based on the tin content in the material used to make the separation functional layer, and the tin content in the separation functional layer is calculated based on the calculated value. It should be noted that the weight of tin is the weight after removing water, organic solvent, etc. that evaporate during curing from the material used to make the separation functional layer.

[0218] [Young's modulus]

[0219] First, a layer having the same composition and thickness as the separation functional layer possessed by the pervaporation membranes of Examples 1 to 6 and 10 to 13 is prepared on a release liner. As a release liner, a polyethylene terephthalate (PET) film (MRE38, manufactured by Mitsubishi Chemical Corporation) subjected to a release treatment is used. The above-mentioned layer is prepared on the release surface of the release liner. Next, a self-supporting film of the separation functional layer is prepared by removing the release liner. For the self-supporting film, Young's moduli A1 and A2 are measured by the above-mentioned method. Furthermore, based on Young's moduli A1 and A2, the ratio R is calculated by the above-mentioned formula (1). It should be noted that in the measurement of Young's moduli A1 and A2, Autograph AGS-50NX manufactured by Shimadzu Corporation was used as a tensile testing machine.

[0220] [PV characteristics]

[0221] For Examples 1, 6, and 10 to 13, the separation coefficient α1 of BuOH for water of the pervaporation membrane before the implementation of Test 2 was determined by the above method. BuOH , the separation coefficient α2 of BuOH to water of the pervaporation membrane after the implementation of the test 2 BuOH , and ratio R1. Further, for Examples 2, 4, and 6, the separation coefficient α1 of the IPA to water of the pervaporation membrane before the implementation of Test 2 was determined by the above method. IPA , the separation coefficient α2 of IPA to water of the pervaporation membrane after the experiment 2 IPA , and ratio R2.

[0222] [Tack evaluation]

[0223] In Examples 1 to 6 and 10 to 13, the stickiness of the pervaporation membrane after the above-mentioned Test 2 was performed was evaluated. The stickiness was evaluated by placing a finger on the surface of the separation functional layer of the pervaporation membrane, leaving it still for 1 second, and then lifting the finger. When the finger was lifted, if a finger mark remained on the separation functional layer, it was judged to be sticky. If no finger mark remained on the separation functional layer, it was judged to be non-sticky.

[0224] [Crack Evaluation]

[0225] In Examples 1 to 6 and 10 to 13, the presence or absence of cracks was confirmed by visually checking the surface of the separation functional layer of the pervaporation membrane after the above-mentioned Test 2 was carried out.

[0226] [Table 1]

[0227]

[0228] [Table 2]

[0229]

[0230] The abbreviations in Table 1 are as follows.

[0231] KS847T: Silicone resin composition (manufactured by Shin-Etsu Chemical Co., Ltd., KS-847T)

[0232] KS847: Silicone resin composition (manufactured by Shin-Etsu Chemical Co., Ltd., KS-847)

[0233] KS3601: Silicone resin composition (manufactured by Shin-Etsu Chemical Co., Ltd., KS-3601)

[0234] KS3650: Silicone resin composition (manufactured by Shin-Etsu Chemical Co., Ltd., KS-3650)

[0235] KE1935: Silicone resin composition (manufactured by Shin-Etsu Chemical Co., Ltd., KE-1935)

[0236] YSR3022: Silicone resin composition (Momentive Performance Materials Japan LLC, YSR3022)

[0237] SILPOT184: Silicone resin composition (manufactured by Dow Corning Toray Co., Ltd., SILPOT184)

[0238] CAT-PL-50T: Platinum catalyst (manufactured by Shin-Etsu Chemical Co., Ltd., CAT-PL-50T)

[0239] YC6831: Tin-based catalyst (Momentive Performance Materials Japan LLC, YC6831)

[0240] HSZ-890: Zeolite filler (manufactured by Tosoh Corporation, HSZ-890)

[0241] RX50: silica filler (manufactured by Japan Aerosil Co., Ltd., AEROSIL RX50, surface modification group: trimethylsilane (TMS) group)

[0242] The pervaporation membranes having a separation functional layer with a ratio R of -30% or more (Examples 1 to 5 and 10 to 12) showed good results in viscosity evaluation and crack evaluation even when immersed in a mixed liquid L at 80°C for 3 weeks, and no degradation of the separation functional layer was confirmed. In particular, in Examples 1, 2, 4 and 10 to 12, there was almost no decrease in PV characteristics. On the other hand, in the pervaporation membranes having a separation functional layer with a ratio R of less than -30% (Examples 6 and 13), viscosity and cracks were generated due to immersion in a mixed liquid L at 80°C for 3 weeks, and degradation of the separation functional layer was confirmed. Furthermore, in Examples 6 and 13, PV characteristics were significantly reduced. Based on the above results, it is inferred that the pervaporation membranes of Examples 1 to 5 and 10 to 12 are sufficiently suppressed from deterioration when the operation of separating volatile organic compounds from an aqueous solution containing the organic compounds is carried out for a long time, and are suitable for such applications. It is to be noted that, as can be seen from Table 1, when the tin content in the separation functional layer is 1100 wtppm or less, the ratio R tends to be -30% or more.

[0243] Industrial Applicability

[0244] The pervaporation membrane of the present 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 comprising a silicone resin, in, The ratio R of the value obtained by subtracting the Young's modulus A1 (MPa) of the separation functional layer after the test from the Young's modulus A2 (MPa) of the separation functional layer after the test is -30% or more, Experiment: The separation functional layer is immersed in a mixed liquid obtained from n-butanol and water for 3 weeks; the separation functional layer is taken out from the mixed liquid and the separation functional layer is dried; wherein the content of n-butanol in the mixed liquid is 1.0wt%, and the temperature of the mixed liquid is 80°C.

2. The pervaporation membrane according to claim 1, wherein: The ratio R is 30% or less.

3. The pervaporation membrane according to claim 1, wherein: The Young's modulus A1 is 0.1 MPa or more.

4. The pervaporation membrane according to claim 1, wherein: The tin content in the separation functional layer is 1100 wtppm or less.

5. A pervaporation membrane comprising a separation functional layer comprising a silicone resin, in, The tin content in the separation functional layer is 1100 wtppm or less.

6. The pervaporation membrane according to claim 1 or 5, wherein: The silicone resin is formed from an addition-type silicone resin composition.

7. The pervaporation membrane according to claim 6, wherein: The addition-type silicone resin composition includes a polyorganosiloxane P1 having an alkenyl group and a polyorganosiloxane P2 having a hydrosilyl group.

8. The pervaporation membrane according to claim 6, wherein: The addition-type silicone resin composition includes a curing catalyst having platinum.

9. The pervaporation membrane according to claim 1 or 5, wherein: The separation function layer further comprises a filler.

10. The pervaporation membrane according to claim 9, wherein: The filler includes at least one selected from the group consisting of zeolite and silica.

11. The pervaporation membrane according to claim 9, wherein: The filler has a surface modified with a modifying group including a hydrocarbon group.

12. The pervaporation membrane according to claim 11, wherein: The modifying group includes at least one selected from the group consisting of an organosilyl group and a polyorganosiloxane group.

13. The pervaporation membrane according to claim 1 or 5, which is used for separating volatile organic compounds from an aqueous solution containing the organic compounds.

14. The pervaporation membrane according to claim 13, wherein: The organic compound is a fermentation product produced by microorganisms.

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