Woven fabric, ion exchange membrane, electrodialysis device, diffusion dialysis device, water electrolysis device, and method for producing ion exchange membrane

Abstract

The present invention addresses the problem of providing a woven fabric advantageous in terms of environmental load and production, an ion exchange membrane using the woven fabric, a method for producing the same, an electrodialysis device, a diffusion dialysis device, and a water electrolysis device.　The present invention is a woven fabric in which each of a warp and a weft includes a flat yarn including a chlorine-based resin, and an ion exchange membrane that uses the woven fabric, an electrodialysis device, a diffusion dialysis device, a water electrolysis device, and a method for producing the ion exchange membrane.

Description

Woven fabric, ion exchange membrane, electrodialysis device, diffusion dialysis device, water electrolysis device, and method for manufacturing ion exchange membrane

[0001] The present invention relates to a woven fabric, an ion exchange membrane, an electrodialysis apparatus, a diffusion dialysis apparatus, a water electrolysis apparatus, and a method for producing an ion exchange membrane.

[0002] Ion exchange membranes are membranes that selectively allow cations or anions to pass through, and are used in a variety of applications, including the production of salt from seawater by electrodialysis, desalination and concentration of wastewater, the recovery of metal pickling wastewater by diffusion dialysis, and hydrogen production by anion exchange membrane water electrolysis. The paste method is a well-known industrial method for producing ion exchange membranes. In the paste method, a polymerizable composition containing a monomer capable of introducing ion exchange groups is filled into a substrate such as a woven fabric, the coating is polymerized, and the ion exchange groups are then introduced to produce the ion exchange membrane. Examples of substrates that can be used include woven fabric made of polyvinyl chloride resin fibers and porous membranes made of polyolefin resins.

[0003] Japanese Patent Publication No. 42-1438 Japanese Patent Application Publication No. 62-277433 Publication No. 48339-1983 Japanese Patent Publication No. 58-081613

[0004] The present invention provides a woven fabric that is advantageous in terms of environmental load and manufacturing, an ion exchange membrane using the woven fabric and a manufacturing method thereof, an electrodialysis apparatus, a diffusion dialysis apparatus, and a water electrolysis apparatus.

[0005] According to one embodiment, a woven fabric is provided, wherein each of the warp and weft yarns of the woven fabric comprises a flat yarn containing a chlorine-based resin.

[0006] According to one embodiment, an ion exchange membrane is provided, which includes a woven fabric according to one embodiment and an ion exchange resin supported on the woven fabric.

[0007] According to one embodiment, an electrodialysis device is provided, the electrodialysis device including an ion exchange membrane according to one embodiment.

[0008] According to one embodiment, a diffusion dialysis device is provided, the diffusion dialysis device including an ion exchange membrane according to one embodiment.

[0009] According to one embodiment, a water electrolysis device is provided, The water electrolysis device includes an ion exchange membrane according to one embodiment.

[0010] According to one embodiment, there is provided a method for manufacturing an ion exchange membrane according to one embodiment, the method including the steps of: filling a woven fabric with a polymerizable composition for forming an ion exchange resin to obtain a first composite membrane; polymerizing the first composite membrane to obtain a second composite membrane; and introducing ion exchange groups into the second composite membrane to obtain the ion exchange membrane.

[0011] According to one embodiment, there are provided a woven fabric that is advantageous in terms of environmental impact and manufacturing, an ion exchange membrane using this woven fabric and a manufacturing method thereof, an electrodialysis apparatus, a diffusion dialysis apparatus, and a water electrolysis apparatus.

[0012] 1A and 1B are a top view and a cross-sectional view, respectively, of an example of a woven fabric according to an embodiment of the present invention;

[0013] Fibers of chlorine-based resins, such as polyvinyl chloride resin fibers, are sometimes industrially produced by solution spinning, which uses a slurry or solution obtained by swelling or dissolving the resin in an organic solvent such as a mixed solvent of acetone and benzene, tetrahydrofuran, or cyclohexanone. However, such solution spinning uses a large amount of organic solvent, which places a heavy burden on the environment and is undesirable from the viewpoint of health issues. Furthermore, the use of a large amount of organic solvent requires a process for separating and recovering the solvent, which poses problems in terms of equipment and production costs.

[0014] On the other hand, in the melt spinning method that does not use an organic solvent, the melting point and thermal decomposition temperature of polyvinyl chloride resin are close to each other, and the melt viscosity is high, so it is necessary to add a plasticizer to lower the melting point and viscosity and to adjust the spinning conditions in a complex manner.

[0015] In a woven fabric according to one embodiment of the present invention, each of the warp and weft yarns comprises a flat yarn containing a chlorine-based resin. This flat yarn can be obtained, for example, by cutting a film containing a chlorine-based resin. Furthermore, a thermally processed film, which is produced more easily and widely than fibers, can be used. Therefore, this woven fabric can be produced without using a large amount of organic solvent. On the other hand, when a film using an organic solvent is used, no spinning equipment is required; a film can be produced using general cast film production equipment and then cut to obtain a flat yarn. Therefore, the woven fabric according to one embodiment of the present invention has advantages in terms of production. It is preferable that at least one of the warp and weft yarns of the woven fabric is composed exclusively of flat yarns containing a chlorine-based resin, and it is more preferable that both the warp and weft yarns are composed exclusively of flat yarns containing a chlorine-based resin.

[0016] Furthermore, this woven fabric is suitable for use in ion exchange membranes. In ion exchange membranes manufactured by the above-described paste method, the diffusion of ion exchange resin-forming monomer molecules into the woven fabric and the swelling of the woven fabric by the monomer are important. The diffusion of the monomer into the woven fabric forms ion conduction paths within the woven fabric resin, which would otherwise serve as a resistive layer, thereby reducing the resistance of the ion exchange membrane. Furthermore, the swelling of the woven fabric allows the woven fabric resin phase and the ion exchange resin phase to interpenetrate, improving adhesion. When this diffusivity is below a certain level, the mechanical strength of the ion exchange membrane can be sufficient. On the other hand, when the diffusivity is above a certain level, the resistance of the ion exchange membrane does not become too high. Furthermore, when the swelling property is above a certain level, the adhesion can be sufficient. The chlorine-based resin is a resin with appropriate monomer diffusivity and swelling property. Therefore, by using the woven fabric according to one embodiment, an ion exchange membrane can be realized that has low environmental impact and excellent resistance, adhesion, and mechanical strength similar to that of an ion exchange membrane using a woven fabric made of chlorine-based resin fibers.

[0017] [Woven Fabric] The woven fabric according to one embodiment may be any of plain weave, twill weave, and satin weave. In terms of high mechanical strength, the woven fabric is preferably plain weave.

[0018] The flat yarn is a yarn obtained by cutting a film containing a chlorine-based resin, and is also called a film yarn. The cross section of the flat yarn perpendicular to the fiber direction is, for example, square, rectangular, or flat.

[0019] The average length of the short sides of the flat yarn in a cross section perpendicular to the fiber direction is, for example, 10 μm or more and 300 μm or less. When used as a woven fabric for an ion exchange membrane, it is, for example, preferably 30 μm or more and 100 μm or less, and more preferably 40 μm or more and 80 μm or less. When the average length is 10 μm or more, the mechanical strength of the ion exchange membrane can be sufficient. When it is 300 μm or less, the resistance of the ion exchange membrane does not become too high.

[0020] The average length of the long sides of the flat yarn in a cross section perpendicular to the fiber direction is, for example, 100 μm or more and 5000 μm or less. When used as a woven fabric for an ion exchange membrane, it is, for example, preferably 200 μm or more and 1500 μm or less, and more preferably 300 μm or more and 1000 μm or less. When the average length is 100 μm or more, slitting of the film becomes easy to carry out industrially, and when it is 5000 μm or less, it becomes easy to fill the ion exchange resin at the intersections of the woven fabric where the warp and weft of the flat yarn intersect, and peeling of the ion exchange resin at the intersections of the woven fabric is easily prevented.

[0021] The tensile strength of the flat yarn measured by a tensile test is, for example, 30 MPa or more, preferably 80 MPa or more, from the viewpoint of the mechanical strength of the ion exchange membrane. The tensile strength is defined as a value measured under the conditions when a constant-speed extension tester according to JIS L1013 (Testing methods for chemical fiber filament yarns) is used.

[0022] In this specification, the term "chlorine-based resin" refers to a resin having at least one chlorine atom in the repeating unit. Examples of the chlorine-based resin contained in the flat yarn include at least one resin selected from the group consisting of polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinylidene chloride copolymer, chlorinated polyvinyl chloride, chlorinated polyethylene, chlorinated polypropylene, and chlorinated ethylene-propylene copolymer. When used in a woven fabric for an ion exchange membrane, it is preferable to contain polyvinyl chloride (PVC) resin, and more preferably to consist solely of polyvinyl chloride resin, because it has a suitable affinity with the monomer for forming the ion exchange resin.

[0023] From the viewpoint of the tensile strength of the flat yarn, the average degree of polymerization of the chlorine-based resin is, for example, from 600 to 3000, and preferably from 1000 to 1500. When the degree of polymerization is 600 or more, the tensile strength of the flat yarn increases, and when the degree of polymerization is 3000 or less, the viscosity of the chlorine-based resin slurry, which serves as a precursor for thermal processing or organic solvent cast film, decreases, making it easier to produce the film industrially.

[0024] The chlorine-based resin may be crosslinked. Using a crosslinked chlorine-based resin tends to reduce the diffusibility of the ion-exchange resin-forming monomer into the chlorine-based resin, thereby increasing the mechanical strength of the ion-exchange membrane. Crosslinking can be achieved by commonly known methods, such as chemical crosslinking using organic peroxides or radiation crosslinking using electron beams or gamma rays. On the other hand, without crosslinking, the swelling of the woven fabric tends to increase, resulting in improved adhesion of the ion-exchange resin. The gel fraction is used as a measure of the degree of crosslinking of the chlorine-based resin. The gel fraction is measured by immersing a sample in a soluble organic solvent, such as tetrahydrofuran, and determining the proportion of the insoluble portion. The gel fraction can be calculated by dividing the weight of the insoluble matter in the sample by the weight of the insoluble matter other than the chlorine-based resin, expressed as a percentage. The gel fraction of the chlorine-based resin is preferably 10% or more and 70% or less.

[0025] The flat yarn is preferably stretched. The mechanical strength of the stretched flat yarn tends to increase due to the stretching, and the mechanical strength of the ion exchange membrane tends to increase. The stretching ratio is preferably 2 times or more, and although there is no upper limit, it is preferably 8 times or less, which is generally sufficient for stretching.

[0026] The chlorine-based resin may contain a plasticizer. The flexibility of the flat yarn can be adjusted by adjusting the content of the plasticizer. The plasticizer may include, for example, at least one selected from the group consisting of phthalate esters, aliphatic dibasic acid esters, trimellitates, epoxy polymers, and polyester polymers. The proportion of the plasticizer in the chlorine-based resin is, for example, 50 mass% or less.

[0027] The opening rate of a woven fabric is, for example, 1% or more and 50% or less. The opening rate is calculated by observing the woven fabric from above using an optical microscope, and using the following formula: Opening rate (%) = (OP1 x OP2) / {(D1 + OP1) x (D2 + OP2)} x 100, where D1 is the diameter of the warp threads of the woven fabric (the length of the long side in a cross section perpendicular to the fiber direction), D2 is the diameter of the weft threads, OP1 is the opening length in the warp direction of an opening where no warp or weft threads of the woven fabric are present, and OP2 is the opening length in the weft direction.

[0028] Fig. 1 is a top view schematically illustrating an example of a woven fabric according to an embodiment. The plain weave fabric 1 shown in Fig. 1 is a woven fabric woven with warp threads 1a and weft threads 1b.

[0029] The woven fabric according to one embodiment can be manufactured, for example, by the following method. First, a film of a chlorine-based resin is prepared. The thickness of the film is, for example, 10 μm or more and 300 μm or less. The film may be a stretched film or a non-stretched film. The film may be crosslinked as described above and may contain a plasticizer.

[0030] Next, this chlorine-based resin film is cut to obtain a plurality of flat yarns. The method for cutting the film is not particularly limited. For example, in a roll-to-roll process, a single film can be cut into a plurality of strips by passing the film through a slitting device having a width equal to or greater than the short side of the film and equipped with a plurality of blades. The obtained strips of film are stretched to obtain flat yarns. Note that this stretching treatment may be omitted. Furthermore, crosslinking treatment may be performed during or after stretching.

[0031] The flat yarns thus obtained can be used as warp and weft threads and crossed in a specific weave to form a woven fabric.

[0032] [Ion Exchange Membrane] The woven fabric according to the above embodiment can be used as a substrate for an ion exchange membrane. The ion exchange membrane according to one embodiment includes the woven fabric according to the above embodiment and an ion exchange resin supported on the woven fabric. The ion exchange membrane may be a cation exchange membrane or an anion exchange membrane. The ion exchange membrane according to one embodiment can be used in hydrogen production devices, water electrolysis devices, fuel cells, electrodialysis devices, diffusion dialysis devices, pure water production devices, ion-exchanged water production devices, etc. The configuration of these devices and the method of using the ion exchange membrane in the device can be similar to those of known ion exchange membranes.

[0033] Specifically, for example, the electrodialysis device may have a structure in which electrodes are provided at both ends of a stack formed by stacking multiple repeating units of cation exchange membranes, concentration compartment gaskets and spacers, anion exchange membranes, and dilution compartment gaskets and spacers. At least one of the cation exchange membranes and anion exchange membranes may be an ion exchange membrane according to one embodiment of the present invention, or all of the ion exchange membranes may be ion exchange membranes according to one embodiment of the present invention. The gaskets are provided with passages through which the concentrate and dilute solutions flow without mixing. By applying a DC voltage to the electrodes at both ends while the liquids are flowing through the respective passages, a concentrate is obtained from the concentration compartment where ions are concentrated, and a desalted solution is obtained from the desalting compartment where ions are diluted.

[0034] The diffusion dialysis device may have a structure in which a stack is formed by stacking multiple repeating units of anion exchange membranes, concentration compartment gaskets and spacers, anion exchange membranes, and dilution compartment gaskets and spacers. At least one of the anion exchange membranes may be an ion exchange membrane according to one embodiment of the present invention, or all of the ion exchange membranes may be ion exchange membranes according to one embodiment of the present invention. The gaskets are provided with passages for allowing the concentrate and dilute solutions to flow without mixing. Water is passed through the concentrate and the dilute solution, and the waste acid is passed through the dilute solution. Due to the difference in concentration, only the acid selectively moves from the waste acid side to the water side, allowing the acid to be recovered in the concentration compartment.

[0035] The water electrolysis device may be, for example, an anion exchange membrane-based water electrolysis device, and may have, on both sides of the anion exchange membrane, electrodes responsible for the water electrolysis reaction, gas diffusion layers responsible for transporting substances, and bipolar plates with flow paths. An ion exchange membrane according to one embodiment of the present invention can be used as the anion exchange membrane. On the cathode side, H is produced by electrolysis of water. ２ and OH － The anion exchange membrane reacts with OH － to the anode side, and － Oxygen O produced by ２ By blocking the hydrogen, it is possible to selectively recover hydrogen.

[0036] The cation exchange group of the ion exchange resin may be a sulfonic acid group, a carboxylic acid group, a phosphonic acid group, a phenolic hydroxyl group, or the like, with the sulfonic acid group being a strongly acidic group being preferred.

[0037] Examples of the anion exchange group of the ion exchange resin include a quaternary ammonium group, a pyridinium group, a triazolium group, an imidazolium group, a primary amino group, a secondary amino group, and a tertiary amino group, and the strongly basic groups, such as a quaternary ammonium group and a quaternary pyridinium group, are preferred.

[0038] As the ion exchange resin, at least one of a hydrocarbon resin and a fluorine resin can be used as the main component resin. As the hydrocarbon resin, a styrene resin, an acrylic resin, etc. can be used. As the fluorine resin, a resin having a perfluorocarbon skeleton can be used. As the ion exchange resin, a hydrocarbon resin is preferably used, and a styrene resin is more preferably used. The styrene resin includes a styrene resin, a copolymer of a styrene derivative and a comonomer, etc. The styrene resin has at least one styrene skeleton in the repeating unit.

[0039] The ion exchange resin may contain a resin of a different type from the resin that is the main component. Examples of such resins include at least one selected from the group consisting of chlorine-based resins and hydrocarbon-based resins. From the viewpoint of adhesion, it is preferable to contain a chlorine-based resin. Examples of preferred chlorine-based resins include those similar to the chlorine-based resin contained in the woven fabric that is the substrate. The proportion of these resins in the ion exchange resin is, for example, 1% by mass or more and 50% by mass or less. These other resins may be scattered in the form of particles or islands in the matrix of the ion exchange resin.

[0040] The ion exchange resin may further contain an additive such as a plasticizer. Examples of the plasticizer include at least one selected from the group consisting of dibutyl phthalate, dioctyl phthalate, dibutyl phthalate, tributyl phosphate, and acetyl tributyl citrate. The proportion of these plasticizers in the ion exchange resin is, for example, 0.5% by mass or more and 20% by mass or less, and preferably 1% by mass or more and 10% by mass or less. When the plasticizer is 1% by mass or more, the time required to introduce ion exchange groups into the second composite membrane is shortened, and when it is 20% by mass or less, the ion selectivity of the ion exchange membrane is less likely to decrease.

[0041] The thickness of the ion exchange membrane is, for example, 20 μm to 400 μm, preferably 50 μm to 300 μm. When the thickness is 20 μm or more, the ion exchange membrane is likely to have sufficient strength, and when the thickness is 400 μm or less, low resistance is likely to be obtained.

[0042] Fig. 2 is a cross-sectional view schematically illustrating an example of an ion exchange membrane according to an embodiment. The ion exchange membrane 10 shown in Fig. 2 includes the plain weave fabric 1 shown in Fig. 1 and an ion exchange resin 11 supported on the plain weave fabric 1.

[0043] An ion exchange membrane according to one embodiment is manufactured by, for example, a paste method. The manufacturing method of an ion exchange membrane according to one embodiment includes, for example, a step of filling a woven fabric with a polymerizable composition for forming an ion exchange resin to obtain a first composite membrane, a step of polymerizing the first composite membrane to obtain a second composite membrane, and a step of introducing ion exchange groups into the second composite membrane. Here, filling a substrate with a polymerizable composition means filling the voids between fibers constituting the substrate with the polymerizable composition. More specifically, for example, the voids between fibers can be filled with the polymerizable composition by dipping a woven fabric transported by a roll-to-roll method into a paste-like polymerizable composition.

[0044] A method for manufacturing an ion exchange membrane according to one embodiment may include the steps of filling a woven fabric with a polymerizable composition for forming an ion exchange resin to obtain a first composite membrane, stacking the first composite membrane and a release sheet and winding them into a roll to obtain a first wound body, polymerizing the first wound body to obtain a second composite membrane, peeling the release sheet from the second composite membrane, and introducing ion exchange groups into the second composite membrane.

[0045] The release sheet may be, for example, a polyethylene terephthalate (PET) film, a polyvinyl alcohol film, a polycarbonate film, or a polytetrafluoroethylene film.

[0046] The polymerization method for the first composite membrane may be thermal polymerization, photopolymerization, or a combination of these. From the viewpoint of obtaining an ion exchange membrane with excellent adhesion, thermal polymerization is preferred.

[0047] The thermal polymerization temperature of the first composite membrane is, for example, 50° C. or more and 140° C. or less, and preferably 70° C. or more and 120° C. or less. The thermal polymerization time is, for example, 0.5 hours or more and 10 hours or less, and preferably 1 hour or more and 6 hours or less after the maximum temperature is reached.

[0048] The introduction of ion exchange groups is carried out, for example, by immersing the second composite membrane in a solution of a compound containing ion exchange groups. For example, an anion exchange membrane having quaternary ammonium groups introduced therein can be obtained by immersing a second composite membrane having chloromethylstyrene units in a trimethylamine solution for 12 hours or more. In another example, a cation exchange membrane having sulfonic acid groups introduced therein can be obtained by contacting a second composite membrane having styrene units with concentrated sulfuric acid.

[0049] The polymerizable composition for forming the ion exchange resin contains a monomer capable of introducing an ion exchange group, and may further contain a crosslinking agent, a thickener, a plasticizer, a polymerization initiator, and other additives.

[0050] The monomer capable of introducing an ion-exchange group includes at least one selected from the group consisting of styrene, styrene derivatives, vinylpyridine, and vinylpyridine derivatives. The monomer capable of introducing an ion-exchange group preferably includes at least one selected from the group consisting of styrene and styrene derivatives.

[0051] The styrene derivative may be at least one selected from the group consisting of chloromethylstyrene, vinyltoluene, vinylxylene, α-methylstyrene, vinylnaphthalene, and α-halogenated styrene.

[0052] The proportion of the monomer into which an ion exchange group can be introduced in the polymerizable composition is, for example, 10% by mass or more and 90% by mass or less, and preferably 30% by mass or more and 80% by mass or less.

[0053] The pyridine derivative may be at least one selected from the group consisting of 4-vinylpyridine and 2-methyl-5-vinylpyridine.

[0054] As the crosslinking agent, a monomer having a difunctional or higher polymerizable group is used, and as the crosslinking agent, at least one selected from the group consisting of divinylbenzene, divinyl sulfone, butadiene, chloroprene, divinylbiphenyl, divinylnaphthalene, diallylamine, divinylpyridine, and trivinylbenzene is preferably used, and divinylbenzene is more preferably used.

[0055] The proportion of the crosslinking agent in the polymerizable composition is, for example, 0% by mass or more and 30% by mass or less, and preferably 3% by mass or more and 20% by mass or less.

[0056] The thickener can be blended to increase the viscosity of the polymerizable composition and improve adhesion between the ion exchange resin and the substrate. For example, resin particles are used as the thickener. A chlorine-based resin is preferably used as the resin, and it is more preferable to use the same type of resin as the resin contained in the woven fabric, which is the substrate. The average particle size of the particles measured by the Coulter method is, for example, 0.1 μm or more and 20 μm or less.

[0057] The proportion of the thickener in the polymerizable composition is, for example, 1% by mass or more and 50% by mass or less, preferably 3% by mass or more and 30% by mass or less. As the thickener, it is preferable to use particles of a chlorine-based resin from the viewpoint of improving adhesion between the woven fabric and the ion exchange resin. The chlorine-based resin refers to a resin having at least one chlorine atom in the repeating unit. For example, at least one resin selected from the group consisting of polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinylidene chloride copolymer, chlorinated polyvinyl chloride, chlorinated polyethylene, chlorinated polypropylene, and chlorinated ethylene-propylene copolymer can be used.

[0058] Examples of the polymerization initiator include benzoyl peroxide, p-chlorobenzoyl peroxide, decanoyl peroxide, lauroyl peroxide, acetyl peroxide, tert-butyl (2-ethylhexanoyl) peroxide hexanoate, tert-butyl peroxyoctoate, and di-tert-butyl peroxide.

[0059] The plasticizer may be at least one selected from the group consisting of dibutyl phthalate, bis(2-ethylhexyl) phthalate, and tributyl acetyl citrate. The proportion of the plasticizer in the polymerizable composition is, for example, 1% by mass or more and 20% by mass or less.

[0060] The proportion of the polymerization initiator in the polymerizable composition is, for example, 0.1% by mass or more and 15% by mass or less, and preferably 1% by mass or more and 10% by mass or less.

[0061] Other additives contained in the polymerizable composition include a polymerization inhibitor and a hydrochloric acid scavenger.

[0062] Example 1 A polyvinyl chloride (PVC) film F1 containing a plasticizer (Sun Plastics Co., Ltd., uniaxially stretched inflation film K-2, thickness 60 μm) was cut into a width of 1 mm, and this slit film was passed between two heated rollers (distance between rollers 1.5 m) to perform roll-to-roll continuous heating and stretching.

[0063] The draw ratio was defined as the ratio of the let-off speed and the take-up speed of the heated roller. First, the fiber was drawn twice at a let-off roller speed of 7 m / min at 80°C and a take-up roller speed of 14 m / min at 80°C. The obtained two-fold drawn fiber was further drawn twice at a let-off roller speed of 4.7 m / min at 80°C and a take-up roller speed of 9.4 m / min at 80°C to obtain a four-fold drawn fiber. This fiber was then heat-treated at a constant length at a let-off roller speed of 7 m / min at 80°C and a take-up roller speed of 9.4 m / min at 90°C to obtain a PVC flat yarn.

[0064] The average length of the short side of this flat yarn in the cross section perpendicular to the fiber direction was 100 μm, and the average length of the long side in the cross section perpendicular to the fiber direction was 430 μm. A plain woven fabric was produced using this flat yarn. The thickness of the woven fabric was 211 μm, the porosity was 48%, and the open area ratio was 18%.

[0065] The woven fabric was dipped in a paste-like polymerizable composition, both sides of the woven fabric were covered with 50 μm-thick PET films, and both sides of the woven fabric were sandwiched between iron plates with a surface pressure of 0.22 MPa on the PET films. The polymerizable composition was filled into the woven fabric to obtain a first composite membrane. The first composite membrane sandwiched between the iron plates was placed in an autoclave and held at 30° C. for 10 minutes under a nitrogen pressure of 0.3 MPa. The temperature was then increased to 90° C. at a rate of 1° C. / min, and thermally polymerized at 90° C. for 180 minutes to obtain a second composite membrane.

[0066] The polymerizable composition used was 58 parts by mass of styrene (Wako Special Grade, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 15 parts by mass of chloromethylstyrene (CMS-P, manufactured by AGC Seimi Chemical Co., Ltd.), 18 parts by mass of a 55% divinylbenzene isomer mixture (Practical Grade, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 9 parts by mass of acrylonitrile (Wako 1st Grade, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 7 parts by mass of dibutyl phthalate (Wako Special Grade, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 3 parts by mass of benzoyl peroxide (Niper BW, manufactured by NOF Corporation, containing 25% water), and 6 parts by mass of polyvinyl chloride resin (ZEST P22, manufactured by Shin-Dai-ichi Vinyl Corporation).

[0067] The second composite membrane was immersed in chlorosulfonic acid at 40° C. for 2 hours, and then immersed in a 3.5 N aqueous NaOH solution to obtain a cation exchange membrane into which sulfonic acid groups had been introduced.

[0068] Example 2 A plasticizer-containing PVC film F2 (Sun Plastics Co., Ltd., uniaxially stretched inflation film HT-C501, thickness 30 μm) was cut into a width of 1 mm, and this slit film was passed between two heated rollers (distance between rollers 1.5 m) to perform roll-to-roll continuous heating and stretching.

[0069] The draw ratio was defined as the ratio of the let-off speed and the take-up speed of the heated roller. The let-off roller was set at 7 m / min at 70°C, and the take-up roller was set at 14 m / min at 70°C, to obtain a 2x drawn fiber. The obtained fiber was then heat-treated at a constant length at a let-off roller speed of 7 m / min at 90°C and a take-up roller speed of 7 m / min at 90°C, to obtain a PVC flat yarn.

[0070] The average length of the short sides of this flat yarn in a cross section perpendicular to the fiber direction was 47 μm, and the average length of the long sides in a cross section perpendicular to the fiber direction was 470 μm. A plain woven fabric was produced using this flat yarn. The thickness of the woven fabric was 132 μm, the porosity was 44%, and the opening ratio was 13%. A second composite membrane and a cation exchange membrane were obtained in the same manner as in Example 1, except that this woven fabric was used instead.

[0071] Example 3 A PVC film F3 (manufactured by Nippi Corporation, EW1748C, thickness 100 μm) containing a plasticizer and subjected to a crosslinking treatment was cut into a width of 1 mm to obtain a PVC flat yarn.

[0072] The average length of the short sides of this flat yarn in a cross section perpendicular to the fiber direction was 85 μm, and the average length of the long sides in a cross section perpendicular to the fiber direction was 987 μm. A plain woven fabric was produced using this flat yarn. The thickness of the woven fabric was 244 μm, the porosity was 38%, and the opening ratio was 3%. A second composite membrane and a cation exchange membrane were obtained in the same manner as in Example 1, except that this woven fabric was used instead.

[0073] Comparative Example 1: A multifilament high-density polyethylene fiber woven fabric was used. This woven fabric had a thickness of 87 μm, a porosity of 51%, and an opening ratio of 1%. A second composite membrane and a cation exchange membrane were obtained in the same manner as in Example 1, except that this woven fabric was used instead.

[0074] <Evaluation> (Thickness) The thickness of the woven fabrics and cation exchange membranes obtained in the Examples and Comparative Examples was measured using a Mitutoyo Digimatic Indicator ID-H0530 (flat probe φ5, granite comparator stand).

[0075] (Brittleness) The second composite membranes obtained in the examples and comparative examples were bent 180° so that one side of each membrane contacted the opposite side, and it was confirmed whether the second composite membrane would break. A second composite membrane that did not break was evaluated as OK (no problem). Here, breakage refers to a state in which the membrane was completely torn off.

[0076] (Burst Strength) The burst strength of the second composite membranes obtained in the examples and comparative examples was measured using a Mullen burst tester (manufactured by Toyo Seiki Seisakusho) in accordance with JIS-P8112.

[0077] (Electrical Resistance) The electrical resistance of the cation exchange membranes obtained in the Examples and Comparative Examples was measured. The ion exchange membrane was sandwiched in a two-compartment cell having platinum black electrodes, and both sides of the ion exchange membrane were filled with a 0.5 mol / L NaCl aqueous solution. The resistance between the electrodes at 25°C was measured using an AC bridge (frequency 1000 cycles / second). The difference between the inter-electrode resistance and the inter-electrode resistance when no ion exchange membrane was installed was used to determine the membrane resistance (Ω cm ２ The ion exchange membrane used in the above measurement was previously equilibrated in a 0.5 mol / L NaCl aqueous solution.

[0078] (Water Permeability) As an index of the adhesion between the substrate and the ion exchange resin, the water permeability under pressure of the cation exchange membranes obtained in the Examples and Comparative Examples was measured. ２ The ion exchange membrane was set in the pressure vessel, and pure water was pressurized at 0.1 MPa to measure the amount of water passing through per hour.

[0079] Table 1 shows the evaluation results of the second composite membrane and the cation exchange membrane in the examples and comparative examples.

[0080]

[0081] As is clear from the above results, the woven fabric according to one embodiment of the present invention uses flat yarns, which is advantageous in terms of environmental impact and manufacturing. Furthermore, ion exchange membranes obtained using such woven fabrics have excellent resistance, adhesion, and mechanical strength. Furthermore, such ion exchange membranes can be used as ion exchange membranes in devices such as electrodialysis devices, diffusion devices, and water electrolysis devices.

Claims

1. A woven fabric in which the warp and weft each comprise a flat yarn containing a chlorine-based resin.

2. The woven fabric according to claim 1, wherein the average length of the short sides of the flat yarn in a cross section perpendicular to the fiber direction is 10 μm or more and 300 μm or less.

3. The woven fabric according to claim 1 or 2, wherein the average length of the long sides of the cross section perpendicular to the fiber direction of the flat yarn is 100 μm or more and 5,000 μm or less.

4. The woven fabric according to any one of claims 1 to 3, wherein the chlorine-based resin is a polyvinyl chloride resin.

5. The woven fabric according to any one of claims 1 to 4, wherein the chlorine-based resin has been crosslinked.

6. The woven fabric according to any one of claims 1 to 5, wherein the chlorine-based resin has been subjected to a stretching treatment.

7. The woven fabric according to any one of claims 1 to 6, which is used as a substrate for an ion exchange membrane.

8. An ion exchange membrane comprising the woven fabric according to any one of claims 1 to 7 and an ion exchange resin supported on the woven fabric.

9. The ion exchange membrane of claim 8, wherein the ion exchange resin comprises a styrene-based resin.

10. An electrodialysis device comprising the ion exchange membrane according to claim 8 or 9.

11. A diffusion dialysis device comprising the ion exchange membrane according to claim 8 or 9.

12. A water electrolysis device comprising the ion exchange membrane according to claim 8 or 9.

13. A method for producing an ion exchange membrane according to claim 8 or 9, comprising the steps of: filling the woven fabric with a polymerizable composition for forming the ion exchange resin to obtain a first composite membrane; polymerizing the first composite membrane to obtain a second composite membrane; and introducing ion exchange groups into the second composite membrane to obtain an ion exchange membrane.

14. The method of claim 13, wherein the polymerizable composition comprises particles of a chlorine-based resin.

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