Ion exchange membrane and method for producing same

Abstract

Provided is an ion exchange membrane which is not susceptible to liquid leakage. An ion exchange membrane provided with a porous base material (11) and an ion exchange resin layer laminated on a first surface (11a) of the porous base material (11) or an ion exchange resin layer (13) impregnated on the first surface (11a) side of the porous base material (11), the porous base material (11) having voids left on at least a second surface (11b) side on the opposite side from the first surface (11a), gaps in the peripheral edge of the porous base material (11) are blocked by a filling resin (14).

Description

Technical Field

[0001] The present invention relates to an ion exchange membrane and a method for manufacturing the same. Background Art

[0002] Ion exchange membranes such as anion exchange membranes and cation exchange membranes are used in electrodialysis, reverse electrodialysis, etc. In electrodialysis, anion exchange membranes and cation exchange membranes are alternately arranged to form desalination chambers and concentration chambers. If, for example, seawater is supplied to each chamber and an electric current is passed through, desalted water and concentrated brine can be produced. Electrodialysis is a technique used in the production of table salt from seawater, desalination in the food field such as soy sauce and oligosaccharides, desalination / concentration of leachate from final disposal sites, desalination / concentration of process waste liquids, recovery of pickling acid waste liquids from aluminum window frames, recovery of alkaline waste liquids, etc.

[0003] Reverse electrodialysis is a technique in which, similarly to electrodialysis, anion exchange membranes and cation exchange membranes are alternately arranged to form a dilute chamber and a concentrated chamber, a low-concentration electrolyte solution is supplied to the dilute chamber, and a high-concentration electrolyte solution is supplied to the concentrated chamber, thereby converting the concentration difference energy into electric power using the ion exchange membrane. Reverse electrodialysis can be used, for example, in power generation using fresh water taken from a river and seawater taken from the sea. In addition, seawater and concentrated seawater with a higher concentration than seawater discharged from a seawater desalination facility based on distillation or reverse osmosis can also be used.

[0004] As the ion exchange membrane, an ion exchange membrane having an ion exchange resin layer provided on one surface side of a porous substrate is known.

[0005] As the porous substrate used in the ion exchange membrane, there are porous films, nets, knitted fabrics, woven fabrics, non-woven fabrics, etc. Among them, non-woven fabrics can firmly bond the ion exchange resin layer and are inexpensive, so they are considered to be preferable as the substrate of the ion exchange membrane (Patent Document 1).

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: International Publication No. 2018 / 164143 Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] However, in the porous substrate, particularly the porous substrate formed of non-woven fabric, even when pressurized, the pore portions sometimes remain without collapsing. Therefore, even under the use conditions of the ion exchange membrane, the pore portions sometimes remain, and liquid leakage occurs from the end face of the porous substrate.

[0011] In view of the above circumstances, an object of the present invention is to improve liquid leakage of an ion exchange membrane having an ion exchange resin layer provided on one surface side of a porous substrate.

[0012] Means for Solving the Problem

[0013] The present invention has the following aspects.

[0014] [1] An ion exchange membrane comprising: a porous substrate, and an ion exchange resin layer laminated on the first surface of the porous substrate or an ion exchange resin layer impregnated into the first surface side of the porous substrate,

[0015] The porous substrate has voids remaining at least on the second surface side opposite to the first surface,

[0016] The voids in the peripheral portion of the porous substrate are blocked by a filling resin.

[0017] [2] An ion exchange membrane comprising: a pair of porous substrates, and an ion exchange resin layer laminated between the first surfaces of the pair of porous substrates or an ion exchange resin layer impregnated into the first surface sides of the pair of porous substrates,

[0018] The pair of porous substrates have voids remaining at least on the second surface side opposite to the first surface,

[0019] The voids in the peripheral portions of the pair of porous substrates are blocked by a filling resin.

[0020] [3] The ion exchange membrane according to [1] or [2], wherein the filling resin contains one or more selected from hydrocarbon resins and hydrocarbon elastomers.

[0021] [4] The ion exchange membrane according to [3], wherein the filling resin contains a high molecular weight component and a low molecular weight component, the high molecular weight component is one or more selected from hydrocarbon resins and hydrocarbon elastomers having a weight average molecular weight of 10,000 or more, and the low molecular weight component contains one or more hydrocarbon resins having a weight average molecular weight of less than 10,000.

[0022] [5] The ion exchange membrane according to [3], wherein the filling resin contains one or more selected from polyolefins, polybutadiene, polyisoprene, polyisobutene, ethylene-propylene rubber, and styrene-diene-based elastomers.

[0023] [6] The ion exchange membrane according to [3], wherein the filling resin contains one or more selected from styrene-butadiene copolymers and their hydrides, and styrene-isoprene copolymers and their hydrides.

[0024] [7] The ion exchange membrane according to any one of [1] to [6], wherein the aforementioned filled resin contains one or more selected from polyvinyl alcohol and ethylene-vinyl alcohol copolymer.

[0025] [8] The ion exchange membrane according to any one of [1] to [7], wherein the aforementioned filled resin contains one or more selected from chlorinated polyethylene and chlorosulfonated polyethylene.

[0026] [9] The ion exchange membrane according to any one of [1] to [8], wherein the aforementioned filled resin contains one or more solvent-soluble fluororesins.

[0027]

[10] The ion exchange membrane according to any one of [1] to [9], wherein the aforementioned porous substrate is a non-woven fabric composed of one or more selected from ethylene-tetrafluoroethylene copolymer, polytetrafluoroethylene, tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer, and polyolefin.

[0028]

[11] The ion exchange membrane according to any one of [1] to

[10] , wherein the aforementioned porous substrate is a porous film composed of polyolefin.

[0029]

[12] A method for manufacturing an ion exchange membrane, wherein a solution of a filled resin is coated on the peripheral portion of the second surface of the following porous substrate for the ion exchange membrane body,

[0030] The ion exchange membrane body includes: a porous substrate, and an ion exchange resin layer laminated on the first surface of the aforementioned porous substrate or an ion exchange resin layer infiltrated into the first surface side of the aforementioned porous substrate, and voids remain on the second surface side of at least the side opposite to the aforementioned first surface of the aforementioned porous substrate.

[0031]

[13] A method for manufacturing an ion exchange membrane, wherein a solution of a filled resin is coated on the peripheral portion of the second surface of each of the following pair of porous substrates for the ion exchange membrane body, the ion exchange membrane body includes: a pair of porous substrates, and an ion exchange resin layer laminated between the first surfaces of the aforementioned pair of porous substrates or an ion exchange resin layer infiltrated into the first surface side of each of the aforementioned pair of porous substrates, and voids remain on the second surface side of at least the side opposite to the aforementioned first surface of the aforementioned pair of porous substrates.

[0032]

[14] The method for manufacturing an ion exchange membrane according to

[12] or

[13] , wherein the aforementioned coating is performed by screen printing.

[0033] Advantages of the invention

[0034] The ion exchange membrane of the present invention is not prone to liquid leakage. In addition, according to the manufacturing method of the ion exchange membrane of the present invention, an ion exchange membrane that is not prone to liquid leakage can be manufactured. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a plan view of the ion exchange membrane of the first embodiment of the present invention.

[0036] Figure 2 is Figure 1 II-II sectional view of.

[0037] Figure 3 It is a plan view of the ion exchange membrane of the second embodiment of the present invention.

[0038] Figure 4 is Figure 4 IV-IV sectional view of.

[0039] Figure 5 It is an example of an electrodialysis device using the ion exchange membrane of the first embodiment.

[0040] Figure 6 It is a plan view of the ion exchange membrane manufactured in the examples.

[0041] Figure 7 It is an explanatory diagram of the evaluation method of the ion exchange membrane of the examples. DETAILED DESCRIPTION OF THE INVENTION

[0042] The definitions of the following terms in this specification and claims are as follows.

[0043] "Monomer" refers to a compound having a polymerizable carbon-carbon double bond.

[0044] The weight average molecular weight of the polymer (hereinafter referred to as "Mw".) is the polymethyl methacrylate converted molecular weight obtained by measurement by gel permeation chromatography (hereinafter referred to as "GPC".) using a standard curve prepared using a standard polymethyl methacrylate sample.

[0045] "~" indicating a numerical range means including the numerical values described before and after it as the lower limit value and the upper limit value.

[0046] <First Embodiment>

[0047] Use Figure 1 , Figure 2 , the ion exchange membrane 10 of the first embodiment of the present invention will be described. The ion exchange membrane 10 includes a porous substrate 11 and an ion exchange resin layer 13 provided on the first surface 11a of the porous substrate 11.

[0048] The ion exchange resin layer 13 can be stacked in contact with the porous substrate 11, or a part or all of the ion exchange resin layer 13 can be impregnated into the porous substrate 11.

[0049] In the present invention, the "ion exchange resin layer laminated on the first surface of the porous substrate" refers to an ion exchange resin layer laminated in direct contact with the porous substrate, and the "ion exchange resin layer formed by impregnating the first surface side of the porous substrate" refers to an ion exchange resin layer in which a part or all of the surface of the porous substrate and the voids formed on the surface are impregnated with the ion exchange resin.

[0050] However, even when the ion exchange resin layer 13 is impregnated into the porous substrate 11, there is a portion on the second surface 11b side opposite to the first surface 11a of the porous substrate 11 where the voids are not filled with the ion exchange resin layer 13 and the voids remain as they are.

[0051] A part of the voids of the porous substrate 11 is blocked by the filling resin 14. Specifically, at the peripheral portion of the porous substrate 11, the voids remaining in the porous substrate 11 are filled with the filling resin 14, and the filled portion is blocked.

[0052] It should be noted that the peripheral portion is not limited to the annular portion along the outer periphery of the porous substrate 11 as shown in Figure 1 , Figure 2 . For example, it may also be an annular portion slightly inside the outer periphery of the porous substrate 11. In addition, it is not limited to the annular shape along the same shape as the porous substrate 11, and for example, it may also be a circular ring shape.

[0053] [Porous substrate]

[0054] Examples of the porous substrate 11 include a porous film, a net, a knitted fabric, a woven fabric, and a non-woven fabric. Among them, from the aspect of easily having fine voids, a porous film, a woven fabric, and a non-woven fabric are preferred, and a non-woven fabric is particularly preferred from the aspect of being inexpensive and easily obtainable.

[0055] The porous substrate 11 can have a single-layer structure or a laminated structure.

[0056] The fiber diameter of the fibers constituting the nonwoven fabric is not particularly limited, and known fiber diameters can be used. Specifically, it is preferably 0.1 to 30 μm. Among them, more preferably 4 to 30 μm, and particularly preferably 5 to 20 μm. By being above the lower limit value of the preferred range, it is easy to improve the strength of the nonwoven fabric. By making the fiber diameter below the upper limit value of the preferred range, the smoothness of the surface of the nonwoven fabric is maintained, the anchoring effect is easily exhibited, and the ion exchange resin layer 13 is easily maintained. In addition, based on these fibers, fibers having a fiber diameter finer than the fibers used can be added after adjusting the voids and strength. For example, when the fiber diameter of the nonwoven fabric used is 4 μm or more, ultrafine fibers having a fiber diameter of less than 4 μm can be mixed at a ratio within 20% of the unit area weight of the entire nonwoven fabric.

[0057] As the nonwoven fabric, a nonwoven fabric composed of one or more selected from polyolefins, ethylene-tetrafluoroethylene copolymers, polytetrafluoroethylene, and tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymers is preferred.

[0058] These nonwoven fabrics are likely to have voids remaining only by simple pressing, and thus are suitable for the application of the present invention.

[0059] Examples of the polyolefin constituting the nonwoven fabric include polypropylene, polyethylene, polyisobutylene, polyisoprene, and their blends.

[0060] When the nonwoven fabric is made of polyolefin, from the aspect of easy manufacture of the nonwoven fabric, it is preferably made into a thermally bondable composite fiber.

[0061] Examples of the thermally bondable composite fiber include a core-sheath type having a low-melting-point component as the sheath part and a high-melting-point component as the core part, and a side-by-side type in which one side of the cross section is a low-melting-point component and the other side is a high-melting-point component. Examples of the core-sheath type thermally bondable composite fiber include a composite fiber formed by a core of polypropylene and a sheath of polyethylene, and a composite fiber formed by a core of high-density polyethylene (HDPE) and a sheath of low-density polyethylene (LLDPE or LDPE).

[0062] As the porous film, from the aspects of low cost and chemical resistance, a porous film made of polyolefin is preferred.

[0063] As the polyolefin constituting the porous film, known polyolefins can be used, and examples include polypropylene, polyethylene, ethylene vinyl acetate copolymer, and polymethylpentene.

[0064] For example, in the case of polyethylene, ultra-high molecular weight polyethylene, high-density polyethylene (HDPE), or those obtained by mixing them in any ratio can be used, but it is not limited to these.

[0065] As the woven fabric, known materials can be used, for example, polyolefin fiber woven fabric, glass fiber woven fabric, carbon fiber woven fabric, metal fiber woven fabric, polyether ether ketone fiber woven fabric, PFA (tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer fiber woven fabric. Among them, from the aspects of low cost and chemical resistance, polyolefin fiber woven fabric is preferred.

[0066] The thickness of the porous substrate film measured with a micrometer (manufactured by Mitutoyo Corporation) is preferably 30 to 300 μm, more preferably 60 to 250 μm. By making the thickness of the porous substrate 11 within the preferred range, appropriate membrane resistance and strength can be achieved.

[0067] In addition, in the present invention, preferably, in the concentration chamber and the desalination chamber shown in the specific usage examples of the present invention, the liquid flowing through is easily permeated or infiltrated into the layer of the porous substrate where the ion exchange resin is not filled. From this perspective, the porous substrate is also preferably subjected to treatments such as corona treatment, plasma treatment, electron beam treatment, and infiltration treatment of a surfactant into a solution, which are examples of treatments to improve the wettability with the liquid. This treatment can be performed before and after infiltrating the ion exchange resin, and before and after the step of coating the solution of the filling resin of the present invention. When the treatment affects the ion exchange resin layer and the filling resin, it is preferably performed before infiltrating the ion exchange resin.

[0068] [Ion exchange resin layer]

[0069] The ion exchange resin layer 13 can be a cation exchange resin layer, can be an anion exchange resin layer, or can also be a laminate of a cation exchange resin layer and an anion exchange resin layer. In the case of a laminate of a cation exchange resin layer and an anion exchange resin layer, any layer can be on the side of the porous substrate 11.

[0070] The thickness of the ion exchange resin layer 13 (in the case of infiltration, the total thickness of the infiltrated part and the non-infiltrated part) is preferably 5 to 250 μm, more preferably 10 to 120 μm. By making the thickness of the ion exchange resin layer 13 within the preferred range, appropriate membrane resistance can be achieved.

[0071] The ion exchange resin layer 13 can have a single-layer structure or a laminated structure. In the case of a laminated structure, the same ion exchange resin layer can be overlapped, or a cation exchange resin layer and an anion exchange resin layer can be overlapped. In addition, it can also be a resin layer mixed with a cation exchange resin and an anion exchange resin.

[0072] The method for forming the ion exchange resin layer is not particularly limited and can be formed by known methods. Specifically, it is formed from an ion exchange resin that is dissolved in an organic solvent and can be shaped by coating. For example, it has a structure in which an ion exchange group exhibiting ion exchange ability, specifically a cation exchange group or an anion exchange group, is introduced into a substance selected from the group consisting of polymers obtained by polymerizing monomers having an ethylenically unsaturated double bond such as vinyl-based, styrene-based, and acrylic-based monomers; or polymers having an aromatic ring in the main chain such as polysulfone, polyphenylene sulfide, polyether ketone, polyether ether ketone, polyether imide, polyphenylene ether, polyether sulfone, and polybenzimidazole; and furthermore hydrocarbon-based resins such as styrene-based elastomers such as polystyrene-poly(ethylene-butene)-polystyrene triblock copolymer, polystyrene-poly(ethylene-propylene)-polystyrene triblock copolymer, polystyrene-polyisoprene block copolymer, and their hydrogenated products.

[0073] In addition, methods not limited to the above, such as those disclosed in JP-T-2019-532116 and JP-A-2018-204021, can be cited, but are not limited to these.

[0074] The ion exchange group is a functional group that can become negatively or positively charged in an aqueous solution. In the case of a cation exchange group, examples include a sulfonic acid group, a carboxylic acid group, and a phosphonic acid group. Generally, the sulfonic acid group as a strongly acidic group is suitable. In the case of an anion exchange group, examples include primary to tertiary amino groups, quaternary ammonium groups, pyridyl groups, imidazolyl groups, and quaternary pyridinium groups. Generally, the strongly basic quaternary ammonium group and quaternary pyridinium group are suitable.

[0075] Examples of specific cation exchange resins include polymers obtained by polymerizing sulfonic acid-based monomers such as α-halovinylsulfonic acid, styrenesulfonic acid, and vinylsulfonic acid, carboxylic acid-based monomers such as methacrylic acid, acrylic acid, and maleic anhydride, phosphonic acid-based monomers such as vinylphosphoric acid, and their salts or esters. Furthermore, polymers in which a cation exchange group such as a sulfonic acid group is introduced into the aforementioned polymers having an aromatic ring in the main chain or styrene-based elastomers are cited. From the viewpoints of easy control of the amount of the cation exchange group and excellent formability from an organic solvent, a polymer in which a cation exchange group is introduced into a polymer having an aromatic ring in the main chain is more preferable.

[0076] As an example of a specific anion exchange resin, polymers obtained by polymerizing amine-based monomers such as vinylbenzyltrimethylamine and vinylbenzyltriethylamine, nitrogen-containing heterocyclic monomers such as vinylpyridine and vinylimidazole, their salts or esters can be cited. These can also be used after amination or methylation before and after the polymerization of the monomers. In addition, polymers in which a halogenated alkyl group such as chloromethyl or bromobutyl is introduced into a polymer or a styrene-based elastomer having an aromatic ring in the main chain, and then the halogenated alkyl group is quaternized to introduce an anion exchange group can be cited. From the viewpoint of easy control of the amount of anion exchange groups and excellent formability from an organic solvent, a polymer having an anion exchange group introduced into a polymer or a styrene-based elastomer having an aromatic ring in the main chain is more preferable.

[0077] These ion exchange resins can also have a crosslinked structure as long as a solution dissolved in an organic solvent can be prepared. For example, crosslinking can be carried out using a polyfunctional monomer represented by a divinyl compound such as divinylbenzene, divinyl sulfone, butadiene, chloroprene, divinyl biphenyl, trivinylbenzenes, divinylnaphthalene, diallylamine, and divinylpyridine.

[0078] It can also be a copolymer copolymerized with other monomers such as styrene, acrylonitrile, methylstyrene, acrolein, methyl vinyl ketone, and vinyl biphenyl.

[0079] In addition, these ion exchange resin layers can be formed on a porous substrate, or can be formed into a film shape by a casting method. Thereafter, for example, a crosslinked structure can be introduced by a method such as thermal crosslinking of sulfonic acid groups with each other.

[0080] As another method for forming an ion exchange resin layer, for example, the following method can also be adopted: into a monomer mixture obtained by adding a copolymerizable polymerizable monomer as needed to a polymerizable monomer into which an ion exchange group can be introduced, as needed, a polymer dissolved in the monomer mixture is added as a viscosity modifier and coated on a carrier film with a film thickness thinner than the thickness of the porous substrate, then the porous substrate is overlapped, the coating solution is infiltrated into the porous substrate, then polymerized, and then an ion exchange group is introduced.

[0081] As the carrier film, for example, a film made of polyethylene terephthalate, a fluororesin film, a polyolefin film, etc. can be used.

[0082] The thickness of the carrier film is not particularly limited, and from the viewpoint of ensuring the strength in the process, it is preferably 15 μm or more. In addition, in the case of problems such as warping, it is also preferable to make the thickness of the release film thick, for example, 50 μm or more.

[0083] On the other hand, if it is too thick, when continuous processes such as roll-to-roll are applied to the process, sometimes failures may occur due to hardness problems. Therefore, it is preferably set to 200 μm or less.

[0084] By making the thickness of the carrier film within the preferred range, warping of the ion exchange membrane main body can be avoided.

[0085] Examples of the polymerizable monomer (A) into which a cation exchange group can be introduced include monomers having an aromatic ring such as styrene, vinylnaphthalene, and methylstyrene, and epoxy group-containing polymerizable monomers such as allyl glycidyl ether, glycidyl acrylate, and glycidyl methacrylate.

[0086] Examples of the polymerizable monomer (B) into which an anion exchange group can be introduced include the polymerizable monomer represented by the following formula (1), and epoxy group-containing polymerizable monomers such as allyl glycidyl ether, glycidyl acrylate, and glycidyl methacrylate.

[0087]

[0088] In formula (1), A represents an alkylene group having 1 to 6 carbon atoms optionally containing an etheric oxygen. Z represents a halogen atom.

[0089] The carbon number of A is preferably 4 or less, more preferably 1 or 3. Examples of Z include fluorine, chlorine, bromine, and iodine. From the viewpoints of the stability, polymerizability, and convertibility to an ion exchange group of the monomer, chlorine or bromine is more preferred.

[0090] The polymerizable monomer (A) into which a cation exchange group can be introduced as described above can, after polymerization, be sulfonated with a sulfonating agent exemplified by concentrated sulfuric acid, hot concentrated sulfuric acid, fuming sulfuric acid, chlorosulfonic acid, etc. In addition, the epoxy group-containing polymerizable monomer can, after polymerization, be introduced with a sulfonic acid group as a cation exchange group using a sulfonating agent exemplified by sodium sulfite, etc.

[0091] The polymerizable monomer (B) into which an anion exchange group can be introduced as described above can, after polymerization, be reacted with a tertiary amine such as trimethylamine or triethylamine to introduce a quaternary ammonium structure anion exchange group.

[0092] Examples of the polymerizable monomer that can copolymerize with the group into which an ion exchange group can be introduced as described above include acrylonitrile, butadiene, isoprene, well-known alkyl methacrylates, alkyl acrylates, acrylamide, N-alkyl-substituted acrylamide, methacrylamide, N-alkyl-substituted methacrylamide, etc., but are not limited to these.

[0093] In addition, a compound having two or more polymerizable groups in the molecule can also be added on the basis of these. Specifically, examples include divinylbenzene, ethylene glycol methacrylate, etc., but are not limited to these.

[0094] Examples of the polymer added to these polymerizable monomers to adjust the viscosity include polystyrene, styrene-butadiene copolymer, polybutadiene, butadiene-acrylonitrile copolymer, block copolymers of polystyrene and polybutadiene, or polyisobutylene and polyisoprene, or their hydrogenated products, etc., but are not limited to these.

[0095] For the ion exchange resin as described above, from the viewpoints of reducing the membrane resistance, preventing dissolution in the electrolyte solution, and suppressing swelling, its ion exchange capacity is preferably in the range of 0.5 to 5.0 meq / g, particularly 1.0 to 3.8 meq / g, per dry mass. Therefore, it is preferable to introduce a cation exchange group or an anion exchange group so as to achieve such an ion exchange capacity.

[0096] [Packing resin]

[0097] The packing resin 14 is a resin or an elastomer. By filling the packing resin 14 into the voids at the peripheral portion of the porous substrate 11, the voids at the peripheral portion of the porous substrate 11 are blocked, thereby preventing liquid leakage from the end face.

[0098] The packing resin 14 needs to be substantially insoluble in the aqueous electrolyte solution used in electrodialysis and have resistance (such as acid resistance, etc.).

[0099] In addition, the packing resin 14 is preferably solvent-soluble from the aspect of being easily infiltrated into the porous substrate 11.

[0100] "Solvent-soluble" means that at 30 °C, 20 g or more is dissolved in 100 g of any solvent selected from xylene, methyl ethyl ketone, mineral spirits, ethyl 3-ethoxypropionate, tetrahydrofuran, ethanol, propanol, butanol, and water, or a mixture thereof to form a uniform phase.

[0101] As the packing resin 14, hydrocarbon resins and hydrocarbon elastomers, polyvinyl alcohol and ethylene-vinyl alcohol copolymers, chlorinated polyethylene and chlorosulfonated polyethylene, and solvent-soluble fluorine-containing resins can be used.

[0102] Among them, from the aspect of excellent compatibility between the polymer component and the oligomer component described later, it is preferable to contain one or more selected from hydrocarbon resins and hydrocarbon elastomers, and more preferably to be composed of one or more selected from hydrocarbon resins and hydrocarbon elastomers.

[0103] Hydrocarbon resins and hydrocarbon elastomers refer to resins or elastomers whose main chain is composed of carbon atoms, the total content of carbon and hydrogen exceeds 90% by mass relative to the mass of the entire polymer, and the oxygen content is 1% by mass or less.

[0104] The hydrocarbon resin and the hydrocarbon elastomer may contain one or more atoms selected from halogen, nitrogen, sulfur, phosphorus, and silicon within a range of 10% by mass or less based on the total mass of the polymer.

[0105] As the hydrocarbon resin and the hydrocarbon elastomer, one or more selected from polyolefin, polybutadiene, polyisoprene, polyisobutene, ethylene - propylene rubber, and styrene - diene - based elastomer are preferred. Among them, styrene - diene - based elastomer is preferred.

[0106] As the styrene - diene - based elastomer, one or more selected from styrene - butadiene copolymer and its hydride, and styrene - isoprene copolymer and its hydride can be cited.

[0107] The styrene content in the styrene - diene - based elastomer is not particularly limited, and preferably 12 - 67%. When it is above the lower limit value, it is easy to obtain the strength required for the filled resin to exhibit sealing performance. When it is below the upper limit value, soft characteristics can be obtained, and homogeneous sealing performance can be easily obtained.

[0108] When the filled resin 14 contains one or more selected from the hydrocarbon resin and the hydrocarbon elastomer, the filled resin 14 preferably contains a high - molecular - weight component and an oligomer component. The high - molecular - weight component is one or more selected from the hydrocarbon resin and the hydrocarbon elastomer having a weight - average molecular weight of 10,000 or more, and the oligomer component contains one or more hydrocarbon resins having a weight - average molecular weight of less than 10,000.

[0109] The weight - average molecular weight of the high - molecular - weight component is preferably 10,000 - 700,000, more preferably 20,000 - 500,000.

[0110] The number - average molecular weight of the oligomer component is preferably 300 - 3,000, more preferably 500 - 1,000.

[0111] By using the above - mentioned high - molecular - weight component, embrittlement of the filled resin 14 can be avoided. By using the above - mentioned oligomer component, an increase in the viscosity of the solution of the filled resin 14 can be suppressed, and the concentration of the filled resin 14 in the solution can be increased. Therefore, it is easy to fill a sufficient amount of the filled resin 14 into the voids of the porous substrate 11.

[0112] When the filled resin 14 is composed of one or more selected from the hydrocarbon resin and the hydrocarbon elastomer, the ratio [A / B] of the component [A] as the above - mentioned high - molecular - weight component to the component [B] as the above - mentioned oligomer component is preferably 2 / 8 - 8 / 2, more preferably 3 / 7 - 6 / 4. By making [A / B] above the lower limit value of the preferred range, embrittlement of the filled resin 14 can be avoided. By making [A / B] below the upper limit value of the preferred range, it is easy to fill a sufficient amount of the filled resin 14 into the voids of the porous substrate 11.

[0113] The filling resin 14 may also contain one or more selected from polyvinyl alcohol and ethylene-vinyl alcohol copolymer. Examples of polyvinyl alcohol and ethylene-vinyl alcohol copolymer include the commercially available A-type GOHSENOL series, G-type GOHSENOL series, K-type GOHSENOL series manufactured by Nippon Gohsei Chemical Industry Co., Ltd., JPOVAL series manufactured by JAPAN VAM&POVAL CO., LTD., DENKA POVAL series manufactured by Denka Co., Ltd., KURARAY POVAL PVA series, KURARAY EVAL EVOH series manufactured by Kuraray Co., Ltd., etc.

[0114] The filling resin 14 may also contain one or more selected from chlorinated polyethylene and chlorosulfonated polyethylene.

[0115] Chlorinated polyethylene is a resin obtained by chlorinating polyethylene, and chlorosulfonated polyethylene is a rubber synthesized by chlorinating and chlorosulfonating polyethylene.

[0116] For chlorinated polyethylene and chlorosulfonated polyethylene, the chlorine content is preferably 10 to 60% by mass based on the total mass of the polymer.

[0117] The filling resin 14 may also contain one or more solvent-soluble fluororesins. Examples of solvent-soluble fluororesins include the following fluororesins.

[0118] (i) A fluorine-containing copolymer obtained by polymerizing a monomer mixture containing a fluoroolefin, a monomer having a crosslinkable group, and a monomer having no fluorine atom and no crosslinkable group (for example, LUMIFLON manufactured by AGC Inc.).

[0119] (ii) A copolymer of tetrafluoroethylene and propylene (for example, AFLAS manufactured by AGC Inc.).

[0120] (iii) A vinylidene fluoride-based copolymer (for example, Viton manufactured by Chemours Company, a copolymer of vinylidene fluoride and hexafluoropropylene).

[0121] [Manufacturing Method]

[0122] The ion exchange membrane 10 can be manufactured by coating a solution of the filling resin on an ion exchange membrane main body including a porous substrate 11 and an ion exchange resin layer 13 provided on the first surface 11a of the porous substrate 11.

[0123] The manufacturing method of the ion exchange membrane main body is not limited. For example, it can be obtained by sequentially laminating an ion exchange resin layer 13 and a porous substrate 11 on a carrier film such as polyethylene terephthalate.

[0124] In the ion exchange membrane main body, the ion exchange resin layer 13 may be laminated in contact with the porous substrate 11, or a part or all of the ion exchange resin layer 13 may be impregnated into the porous substrate 11. However, even when the ion exchange resin layer 13 is impregnated into the porous substrate 11, there is a part on the second surface 11b side of the porous substrate 11 opposite to the first surface 11a where the voids remain as they are without being filled with the ion exchange resin layer 13.

[0125] Coating is performed on the peripheral portion of the second surface 11b of the porous substrate 11. Moreover, in the peripheral portion, the filling resin 14 is impregnated into the porous substrate 11 from the second surface 11b, and the filling resin 14 is filled into the voids remaining in the peripheral portion to block the filled portion.

[0126] It should be noted that, as described above, the peripheral portion is not limited to a Figure 1 , Figure 2 ring-shaped portion along the outer periphery of the porous substrate 11 as shown.

[0127] The solution of the filling resin used in the coating can be obtained by dissolving the filling resin in a solvent.

[0128] As the solvent, a solvent with a high boiling point is preferably used. Thereby, coating based on screen printing becomes possible. The boiling point of the solvent is preferably 70 to 300 °C, more preferably 100 to 250 °C.

[0129] Specific examples of the preferred solvent include xylene, toluene, cyclohexane, and solvent naphtha.

[0130] When the filling resin is polyvinyl alcohol, water is also preferably used as the solvent. In addition, when the filling resin is an ethylene-vinyl alcohol copolymer, a mixed solvent of ethanol, propanol, butanol and water or dimethyl sulfoxide is also preferably used as the solvent. When the filling resin is a vinylidene fluoride-based copolymer, dimethylformamide, dimethylacetamide, etc. are also preferably used as the solvent.

[0131] The viscosity of the solution of the filling resin at 25 °C measured by a B-type viscometer is preferably 10 to 5000 mPa·s, more preferably 100 to 4000 mPa·s.

[0132] When the viscosity of the solution of the filling resin is preferably above the lower limit value, the concentration of the solid component of the solution can be increased, and the filling resin can be filled efficiently. In addition, when the viscosity of the solution of the filling resin is below the preferred upper limit value, the coating becomes easier.

[0133] As coating methods, screen printing, bar coating, calender coating, inkjet, spraying, comma coating, gravure coating, and dispenser coating can be mentioned. Among them, screen printing is preferred from the viewpoint of balancing productivity and cost. The coating can be repeated two or more times. Thereby, it is possible to coat a sufficient amount of the filling resin for blocking the voids at the peripheral portion of the porous substrate 11.

[0134] The drying temperature of the coating is preferably 25 to 90 °C, more preferably 40 to 70 °C. By setting the drying temperature to be equal to or higher than the preferred lower limit value, drying can be performed in a short time. By setting the drying temperature to be equal to or lower than the preferred upper limit value, warping of the ion exchange membrane main body can be reduced.

[0135] When the coating is repeated two or more times, the drying temperature for the second and subsequent coatings can be higher than that for the first coating. This is because the shape is not easily changed according to the resin coated for the first time. The drying temperature for the second and subsequent coatings is preferably 25 to 120 °C, more preferably 40 to 100 °C. By setting the drying temperature for the second and subsequent coatings to be equal to or higher than the preferred lower limit value, drying can be performed in a short time. By setting the drying temperature for the second and subsequent coatings to be equal to or lower than the preferred upper limit value, warping of the ion exchange membrane main body can be reduced.

[0136] When a coating liquid containing a polymerizable monomer capable of introducing an ion exchange group or the like is coated on the carrier film and the porous substrate is overlapped thereon and the filling resin 14 is filled, in order to facilitate the treatment, a method of peeling the carrier film after coating the filling resin 14 can be used.

[0137] <Second Embodiment>

[0138] With Figure 4 、 Figure 5 The ion exchange membrane 20 of the second embodiment of the present invention will be described. The ion exchange membrane 20 includes: a first porous substrate 21 and a second porous substrate 22 (a pair of porous substrates), and an ion exchange resin layer 23 provided between the first surface 21a of the first porous substrate 21 and the first surface 22a of the second porous substrate 22.

[0139] The ion exchange resin layer 23 can be laminated in contact with the first porous substrate 21 and the second porous substrate 22, respectively, or a part or all of the ion exchange resin layer 23 can be impregnated into one or both of the first porous substrate 21 and the second porous substrate 22.

[0140] However, even when the ion exchange resin layer 23 infiltrates the first porous substrate 21, there are still portions on the second surface 21b side of the first porous substrate 21, which is opposite to the first surface 21a, where the voids remain as they are without being filled by the ion exchange resin layer 23. Additionally, even when the ion exchange resin layer 23 infiltrates the second porous substrate 22, there are still portions on the second surface 22b side of the second porous substrate 22, which is opposite to the first surface 22a, where the voids remain as they are without being filled by the ion exchange resin layer 23.

[0141] Part of the voids is blocked by the filling resin 24. Specifically, at the peripheral portion of the first porous substrate 21, the filling resin 24 is filled into the voids remaining in the first porous substrate 21, and the filled portions are blocked. Additionally, at the peripheral portion of the second porous substrate 22, the filling resin 24 is filled into the voids remaining in the second porous substrate 22, and the filled portions are blocked.

[0142] It should be noted that the peripheral portion is the same as that described in the first embodiment, and is not limited to the annular portion along the outer periphery of the first porous substrate 21 and the second porous substrate 22.

[0143] As the first porous substrate 21 and the second porous substrate 22, the same substrates as the porous substrate 11 in the first embodiment can be used, and the preferred embodiments are the same. Additionally, as the ion exchange resin layer 23, the same examples as the ion exchange resin layer 13 in the first embodiment can be used, and the preferred embodiments are the same. Additionally, as the filling resin 24, the same examples as the ion exchange resin layer 13 in the first embodiment can be used, and the preferred embodiments are the same.

[0144] [Manufacturing Method]

[0145] The ion exchange membrane 20 can be manufactured by coating a solution of the filling resin on an ion exchange membrane main body including the first porous substrate 21, the second porous substrate 22, and the ion exchange resin layer 23 provided therebetween.

[0146] The manufacturing method of the ion exchange membrane main body is not limited. For example, a method of sequentially laminating the first porous substrate 21, the ion exchange resin layer 23, and the second porous substrate 22 on a carrier film such as polyethylene terephthalate can be cited.

[0147] Additionally, the following method can be cited: After laminating the ion exchange resin layer 23 on the carrier film, the first porous substrate 21 is laminated. After peeling this laminate from the temporary carrier film, and then, if necessary, the same or different materials are laminated as the ion exchange resin layer 23, and then the second porous substrate 22 is sequentially laminated.

[0148] In the ion exchange membrane main body, the ion exchange resin layer 23 may be laminated in contact with the first porous substrate 21 and the second porous substrate 22, or a part or all of the ion exchange resin layer 23 may be impregnated into one or both of the first porous substrate 21 and the second porous substrate 22.

[0149] However, even if the ion exchange resin layer 23 is impregnated into the first porous substrate 21, there is a part on the second surface 21b side of the first porous substrate 21 opposite to the first surface 21a where the voids remain as they are without being filled by the ion exchange resin layer 23. In addition, even if the ion exchange resin layer 23 is impregnated into the second porous substrate 22, there is a part on the second surface 22b side of the second porous substrate 22 opposite to the first surface 22a where the voids remain as they are without being filled by the ion exchange resin layer 23.

[0150] The peripheral portion of the second surface 21b of the first porous substrate 21 and the peripheral portion of the second surface 22b of the second porous substrate 22 are respectively coated. Then, the filling resin 24 is impregnated into the first porous substrate 21 from the peripheral portion of the second surface 21b of the first porous substrate 21, and the filling resin 24 is impregnated into the second porous substrate 22 from the peripheral portion of the second surface 22b of the second porous substrate 22, filling the voids remaining in each peripheral portion and plugging the filled portions.

[0151] Regarding the coating method, the solution of the filling resin used in the coating and its solvent, and their preferred modes, they are the same as those in the first embodiment.

[0152] <Electrodialysis device>

[0153] As an example of the utilization mode of the ion exchange membrane 10, Figure 5 an example of an electrodialysis device is shown. Figure 5 The electrodialysis device includes: a power source 1, a cathode 2 and an anode 3 connected to the power source 1, and an arbitrary number of cation exchange membranes 4 and anion exchange membranes 5 are alternately laminated between the cathode 2 and the anode 3. In Figure 5 an example is shown where the cation exchange membrane 4 is the ion exchange membrane 10 of the present embodiment.

[0154] Between each cation exchange membrane 4 and anion exchange membrane 5, a chamber frame (not shown) is inserted as a spacer, and each spacer forms an ion exchange chamber.

[0155] In addition, bipolar membranes 6 are respectively disposed between the cathode 2 and the cation exchange membrane closest to the cathode 2, and between the anode 3 and the bipolar membrane closest to the anode 3, to isolate the liquid in the ion exchange chamber from the liquid in the electrode chamber and prevent the mixing of the liquids with each other.

[0156] The ion exchange chamber includes a desalting chamber 7 and a concentration chamber 8. The desalting chamber 7 is formed between a cation exchange membrane 4 and an anion exchange membrane 5 located on the anode 3 side with respect to the cation exchange membrane 4. The concentration chamber 8 is formed between the anion exchange membrane 5 and a cation exchange membrane 4 located on the anode 3 side with respect to the anion exchange membrane 5. Thus, a structure in which a plurality of desalting chambers 7 and concentration chambers 8 are alternately arranged is formed.

[0157] In Figure 5 the electrodialysis device, for example, if a treatment liquid containing salts such as NaCl is circulated and supplied to the desalting chamber 7, and an electrolyte solution is supplied to the concentration chamber 8 while circulating, and a voltage is applied between the cathode 2 and the anode 3, then the cations (e.g., Na + ) in the treatment liquid move through the cation exchange membrane 4 to the adjacent concentration chamber 8. On the other hand, the anions (e.g., Cl - ) in the treatment liquid move through the anion exchange membrane 5 to the adjacent concentration chamber 8.

[0158] In this way, desalting is performed from the treatment liquid circulated and supplied to the desalting chamber 7, and a low-concentration electrolyte solution is recovered as a desalination product. On the other hand, the salt concentration in the electrolyte solution circulated and supplied to the concentration chamber 8 gradually increases, and finally a high-concentration electrolyte solution is recovered as a concentration product.

[0159] It should be noted that Figure 5 shows an example of using the ion exchange membrane 10 as the cation exchange membrane 4, but the ion exchange membrane 20 can also be used instead of the ion exchange membrane 10 as the cation exchange membrane 4. In addition, the ion exchange membrane 10 or the ion exchange membrane 20 can be used as the anion exchange membrane 5. The ion exchange membrane of the present invention is not limited to Figure 3 the electrodialysis device shown, and can be used in reverse electrodialysis devices, diffusion dialysis devices, electrolysis devices, batteries, etc.

[0160] Examples

[0161] Hereinafter, examples are given to illustrate the present invention, but the present invention is not limited to these examples.

[0162] <Main body sheet>

[0163] 75 g of an aromatic polysulfone polymer (Amoco Japan Corporation, trade name: Radel R5000NT) was dissolved in 1020 mL of 1,1,2,2-tetrachloroethane, 400 g of chloromethyl methyl ether and 4.5 g of anhydrous stannic chloride were added, and a chloromethylation reaction was carried out at 80 °C for 6 hours.

[0164] After the reaction was completed, 5000 mL of methanol was used to precipitate the reaction product, which was then washed to obtain the chloromethylated polymer (1). The content of chloromethyl in the chloromethylated polymer (1) was 3.84 meq / g, and the ion exchange capacity when all the chloromethyl groups reacted with trimethylamine was 3.1 meq / g of dry resin.

[0165] A mixture of 71 parts by mass of the chloromethylated polymer (1) and 29 parts by mass of polyethersulfone (trade name: PES5200P, manufactured by Sumitomo Chemical Co., Ltd.) was dissolved in N,N-dimethylformamide (hereinafter referred to as DMF) to prepare a solution containing 15% by mass of the polymer mixture. It should be noted that the content of chloromethyl in the polymer mixture was 2.7 mmol / g, and the ion exchange capacity when all the chloromethyl groups reacted with trimethylamine was 2.3 meq / g of dry resin.

[0166] Next, while stirring the above solution at 0 °C, a mixture of a 1 mol / L DMF solution of trimethylamine and 2-methoxyethanol (mixing ratio by mass: 1 mol / L DMF solution of trimethylamine / 2-methoxyethanol = 97 / 3) was slowly added dropwise. Thus, an aminated solution A in which 40 mol% of the chloromethyl groups reacted with trimethylamine was obtained.

[0167] The aminated solution A was cast on a glass plate and dried at 60 °C for 2 hours to produce a cast film A with a thickness of 20 μm. Next, a non-woven fabric composed of short fibers formed by a core of polypropylene and a sheath of polyethylene was laminated and adhered to one surface layer of the cast film A to obtain a reinforced film A. The reinforced film A was immersed in a 0.75 mol / L methanol solution of N,N,N′,N'-tetramethyl-1,2-diaminopropane at 55 °C for 24 hours to react the remaining chloromethyl groups with the diamine compound.

[0168] Through the above steps, a main sheet having an ion exchange resin layer formed on one surface (the first surface) of the non-woven fabric was obtained. The ion exchange resin layer did not penetrate to the other surface (the second surface) of the non-woven fabric, and voids remained on the other surface.

[0169] <Filling resin solution raw materials>

[0170] Using the following raw materials, the filling resin solutions for each example were prepared.

[0171] Polymeric component: Styrene-butadiene thermoplastic elastomer, weight-average molecular weight of about 100,000, styrene content of 20 parts by weight, and MFR obtained by the MFR measurement method specified in JIS K 7210-1 (ISO1131-1) was 4 g / 10 min (190 °C, 2.16 kg).

[0172] Oligomer composition: hydrogenated petroleum resin, number average molecular weight 710.

[0173] Solvent: aromatic hydrocarbon solvent, boiling point 178 - 209 °C.

[0174] <Example 1>

[0175] On the other side (the second side) of the non-woven fabric of the main body sheet, as Figure 6 shown, a plurality of frame-shaped printing portions 32 with a square outer periphery having a side length of 1,120 mm are formed, and the inside thereof is used as the non-printing portion 31.

[0176] Regarding the width of the printing portion 32, the peripheral portions on the upper and lower sides in the drawing are set to 115 mm, and the peripheral portions on the left and right sides in the drawing are set to 50 mm. The total area of the printing portion 32 is approximately 0.35 m 2 .

[0177] Prepare a filled resin solution using the composition in Table 1, and apply the prepared filled resin solution to the printing portion 32. The viscosity of the prepared filled resin solution (viscosity at 25 °C obtained by a B-type viscometer. The same applies hereinafter.) is as shown in Table 1.

[0178] The application is carried out in two steps. Specifically, the filled resin solution obtained by application at a coating amount (including solvent) of 50 g / m 2 is applied by screen printing (60-mesh screen), dried at 60 °C for 20 minutes, and the filled resin is embedded in the voids of the non-woven fabric.

[0179] Furthermore, on the above-embedded filled resin, the above-mentioned filled resin solution is applied again by screen printing at a coating amount (including solvent) of 50 g / m 2 and dried at 80 °C for 3 hours, and the filled resin is embedded in the voids of the non-woven fabric again.

[0180] Thereafter, a 12-cm square is cut out in a manner including the entire printing portion 32 to obtain the ion exchange membrane 30 of Example 1. The amount of resin (solid content) remaining in the dried printing portion 32 is as shown in Table 1.

[0181] It should be noted that for the amount of resin (solid content) remaining in the dried printing portion 32, it is obtained by calculating the following difference: cutting out a 5-cm square from the dried printing portion 32, measuring its weight, and converting it to a value per 1 m 2 weight value, and the difference from the weight per 1 m 2 calculated for the dried non-printing portion 31 by the same procedure. The same applies hereinafter.

[0182] <Example 2>

[0183] Prepare a filled resin solution according to the composition in Table 1. Further, set the first drying at 80 °C for 20 minutes. Otherwise, operate in the same manner as in Example 1 to obtain the ion exchange membrane 30 of Example 2. The viscosity of the prepared filled resin solution is shown in Table 1. In addition, the coating amounts (including the solvent) for the first and second times are the same as in Example 1, and the resin amounts (solid components) remaining after drying are shown in Table 1.

[0184] <Example 3>

[0185] Prepare a filled resin solution according to the composition in Table 1. Otherwise, operate in the same manner as in Example 2 to obtain the ion exchange membrane 30 of Example 3. The viscosity of the prepared filled resin solution is shown in Table 1. In addition, the coating amounts (including the solvent) for the first and second times are the same as in Example 2, and the resin amounts (solid components) remaining after drying are shown in Table 1.

[0186] <Example 4>

[0187] Prepare a filled resin solution according to the composition in Table 1. Coat the filled resin solution on the printing section 32 to obtain the ion exchange membrane 30 of Example 4. The viscosity of the prepared filled resin solution is shown in Table 1.

[0188] The coating is carried out only once. Specifically, by the screen printing method (100 - mesh screen), the coating amount (including the solvent) is 47 g / m 2 Coat the obtained filled resin solution and dry it at 55 °C for 60 minutes to embed the filled resin into the voids of the non - woven fabric. The resin amount (solid component) remaining after drying is shown in Table 1.

[0189] <Example 5>

[0190] Cut out a 12 - cm square directly from the main body sheet as the ion exchange membrane 30 of Example 5.

[0191] <Evaluation>

[0192] Through Figure 7 The air permeability of the evaluation unit shown is used to evaluate the degree of liquid leakage of the ion exchange membranes of each example.

[0193] The evaluation unit is constructed as follows.

[0194] Lower - side SUS plate 41: A stainless - steel plate with a thickness of 2 cm, slightly larger than 12 cm square, having a 5 - cm square recess 41a formed in the center and an air inlet 41b for introducing air into the recess.

[0195] Upper - side SUS plate 42: A stainless - steel plate with a thickness of 2 cm, slightly larger than 12 cm square.

[0196] Cell frame 43: A frame made of polypropylene with a thickness of 1 mm, measuring 12 cm square and having a hole portion 43a with a side length of 5 cm hollowed out at the center.

[0197] Ion exchange membrane 44: A hole portion 44a with a side length of 5 cm is formed at the center of a 12 cm square ion exchange membrane 30. Let the membrane area excluding this hollowed-out portion be S (cm 2 ), and let the area of the hollowed-out portion be S′ (cm 2 ).

[0198] Gasket 45: A gasket made of EPDM with a thickness of 1 mm, measuring 12 cm square and having a hole portion 45a with a side length of 5 cm hollowed out at the center.

[0199] Rubber sheet 46: An EPDM sheet measuring 12 cm square.

[0200] Stack 10 ion exchange membranes 44 and 11 cell frames 43 alternately. Fasten this stack to the lower SUS plate 41 and the upper SUS plate 42 with the gasket 45 in between. Further place a rubber sheet 46 between the gasket 45 and the upper SUS plate 42 to form an evaluation unit. Let the space volume inside the evaluation unit at this time be V (cm 3 ). Fasten it with a hydraulic jack so that the pressure P on each fastening surface is approximately 0.75 - 0.8 MPa.

[0201] Send compressed air into each evaluation unit. When the pressure in each unit stabilizes, close the valve of the compressed air supply to stop the supply, and take the pressure at this time as the initial air pressure P0 (MPa).

[0202] Take the pressure after time t (time) (about 2 minutes later in Example 1, about 1 minute later in Examples 2 and 3, about 45 seconds later in Example 4, and 1 second later in Example 5) as the final air pressure P1 (MPa).

[0203] Use the following formula to calculate the actual fastening surface pressure and the air leakage rate of each evaluation unit. The results are shown in Table 2.

[0204] Actual fastening surface pressure (MPa) = (P × S - P1 × S′) / S

[0205] Leakage rate (L / hr) = (P0 - P1) / 0.1013 × V / t / 1000

[0206] [Table 1]

[0207]

[0208] [Table 2]

[0209]

[0210] As shown in Table 2, in Examples 1 to 4 where the voids of the nonwoven fabric were filled with a filling resin, compared with Example 5 where no filling was done, the air leakage rate became smaller, and sufficient sealing performance was obtained. In particular, for Examples 1 to 3 where an oligomer component was added to reduce the viscosity and increase the resin solid content, and further the coating was performed in two steps and a sufficient amount of filling resin was filled, the air leakage rate decreased significantly.

[0211] Based on the results in Table 1, it can be confirmed that liquid leakage can be improved by the present invention.

[0212] It should be noted that the entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2022-205511 filed on December 22, 2022 are incorporated herein by reference as the disclosure of the specification of the present invention.

[0213] Explanation of reference numerals

[0214] 1 Power supply

[0215] 2 Cathode

[0216] 3 Anode

[0217] 4 Cation exchange membrane

[0218] 5 Anion exchange membrane

[0219] 6 Bipolar membrane

[0220] 7 Desalination chamber

[0221] 8 Concentration chamber

[0222] 10 Ion exchange membrane

[0223] 11 Porous substrate

[0224] 11a First surface

[0225] 11b Second surface

[0226] 13 Ion exchange resin layer

[0227] 14 Filling resin

[0228] 20 Ion exchange membrane

[0229] 21 First porous substrate

[0230] 21a First surface

[0231] 21b Second surface

[0232] 22 Second porous substrate

[0233] 22a First surface

[0234] Second side of 22b

[0235] 23 Ion exchange resin layer

[0236] 24 Packed resin

Claims

1. An ion exchange membrane, comprising: a porous substrate, and an ion exchange resin layer laminated on the first surface of the porous substrate or an ion exchange resin layer infiltrated into the first surface side of the porous substrate, wherein the porous substrate has voids remaining at least on the second surface side opposite to the first surface, and the voids in the peripheral portion of the porous substrate are blocked by a filling resin.

2. An ion exchange membrane, comprising: a pair of porous substrates, and an ion exchange resin layer laminated between the first surfaces of the pair of porous substrates or an ion exchange resin layer infiltrated into the first surface sides of the pair of porous substrates, wherein the pair of porous substrates have voids remaining at least on the second surface side opposite to the first surface, and the voids in the peripheral portions of the pair of porous substrates are blocked by a filling resin.

3. The ion exchange membrane according to claim 1 or 2, wherein The filling resin contains one or more selected from hydrocarbon resins and hydrocarbon elastomers.

4. The ion exchange membrane according to claim 3, wherein, The filling resin contains a high molecular weight component and a low molecular weight component. The high molecular weight component is selected from one or more of hydrocarbon resins and hydrocarbon elastomers having a weight average molecular weight of 10,000 or more, and the low molecular weight component contains one or more hydrocarbon resins having a weight average molecular weight of less than 10,000.

5. The ion exchange membrane according to claim 3, wherein, The filling resin contains one or more selected from polyolefins, polybutadiene, polyisoprene, polyisobutene, ethylene-propylene rubber, and styrene-diene elastomers.

6. The ion exchange membrane according to claim 3, wherein, The filling resin contains one or more selected from styrene-butadiene copolymers and their hydrogenated products, and styrene-isoprene copolymers and their hydrogenated products.

7. The ion exchange membrane according to claim 1 or 2, wherein The filling resin contains one or more selected from polyvinyl alcohol and ethylene-vinyl alcohol copolymers.

8. The ion exchange membrane according to claim 1 or 2, wherein The filling resin contains one or more selected from chlorinated polyethylene and chlorosulfonated polyethylene.

9. The ion exchange membrane according to claim 1 or 2, wherein The filling resin contains one or more solvent-soluble fluororesins.

10. The ion exchange membrane according to claim 1 or 2, wherein The porous substrate is a non-woven fabric composed of one or more selected from ethylene-tetrafluoroethylene copolymers, polytetrafluoroethylene, tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymers, and polyolefins.

11. The ion exchange membrane according to claim 1 or 2, wherein The porous substrate is a porous film composed of polyolefins.

12. A method for manufacturing an ion exchange membrane, wherein, For the ion exchange membrane body, a solution of the filling resin is coated on the peripheral portion of the following second surface of the following porous substrate, wherein the ion exchange membrane body comprises: a porous substrate, and an ion exchange resin layer laminated on the first surface of the porous substrate or an ion exchange resin layer infiltrated into the first surface side of the porous substrate, and voids remain at least on the second surface side opposite to the first surface of the porous substrate.

13. A method for manufacturing an ion exchange membrane, wherein, For the ion exchange membrane body, a solution of the filling resin is coated on the peripheral portion of the following second surface of each of the following pair of porous substrates, wherein the exchange membrane body comprises: a pair of porous substrates, and an ion exchange resin layer laminated between the first surfaces of the pair of porous substrates or an ion exchange resin layer infiltrated into the first surface sides of the pair of porous substrates, and voids remain at least on the second surface side opposite to the first surface of the pair of porous substrates.

14. The method for manufacturing an ion exchange membrane according to claim 12 or 13, wherein, The coating is performed by screen printing.

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