JP2016216769A - Reinforcing core material for cation exchange membrane, cation exchange membrane manufactured by using the reinforcing core material, and electrolytic cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reinforcing core material for a cation exchange membrane, which has excellent mechanical strength against folding or the like, can exhibit stable electrolytic performance for a long period of time and can be woven without using dummy yarns.SOLUTION: The reinforcing core material for a cation exchange membrane is made of a fabric having a structure comprising a PTFF fiber as a reinforcing core material, a PET multifilament, and a PET multifilament which are sequentially and repeatedly disposed as warps and wefts. The reinforcing core material for a cation exchange membrane includes, in a wale direction, at least either of a weft PET enlarged area where two PET multifilaments as wefts present between nearest two PTFE fibers as wefts are arranged at a wider interval than 1/3 of the distance between the two PTFE fibers in the wale direction and a weft PET narrowed area where the two PET multifilaments are arranged at a narrower interval than 1/3 of the distance between the two PTFE fibers in the wale direction. A cation exchange membrane is produced by using the above reinforcing core material. An electrolytic cell includes an anode, a cathode, and the cation exchange membrane disposed between the anode and the cathode.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a reinforcing core material for a cation exchange membrane, and a cation exchange membrane and an electrolytic cell manufactured using the reinforcing core material. More specifically, the present invention relates to a reinforcing core material for a cation exchange membrane that has excellent mechanical strength against bending and the like, can exhibit stable electrolysis performance for a long period of time, and can be woven without using a dummy yarn.

  Fluorine-containing ion exchange membranes are excellent in heat resistance and chemical resistance, and so on, including cation exchange membranes for electrolysis to produce chlorine and alkali by alkaline chloride electrolysis, membranes for ozone generation, and fuel cells It is used as various diaphragms for electrolysis such as water electrolysis and hydrochloric acid electrolysis. For example, as shown in FIG. 1, in an alkali chloride (ion exchange membrane salt) electrolysis process, current efficiency is high from the viewpoint of productivity, electrolytic voltage is low from the viewpoint of economy, and from the viewpoint of product quality. There is a demand for a low salt concentration in caustic soda.

  Among these demands, in order to develop high current efficiency, as shown in FIG. 2, a carboxylic acid layer having a carboxylic acid group having high anion-exclusion property as an ion exchange group and a low-resistance sulfonic acid group are ion-exchanged. An ion exchange membrane is generally used which is composed of at least two layers with a sulfonic acid layer as a base. Since such an ion exchange membrane is in direct contact with chlorine and caustic soda at 80 to 90 ° C. during the electrolysis operation, a fluorine-containing polymer having extremely high chemical durability is used as a material for the ion exchange membrane. However, since such a fluorine-containing polymer alone does not have sufficient mechanical strength as an ion exchange membrane, it can be reinforced by embedding a woven fabric made of polytetrafluoroethylene (PTFE) in the membrane as a reinforcing core material. Has been done.

  For example, the following Patent Document 1 discloses a fluorine-containing electrolysis that has large mechanical strength and excellent electrochemical properties, and is capable of electrolysis with a high current density and shift operation with a large change in current density. For the purpose of providing a cation exchange membrane, a first layer of a fluorinated polymer film having a cation exchange group reinforced by a woven fabric, and a fluorinated heavy polymer having a carboxylic acid group on the cathode side thereof. A fluorine-containing cation exchange membrane for electrolysis comprising a combined second layer, wherein the woven fabric is inserted such that 1/2 or more of its thickness protrudes from the first layer to the anode side, The protruding portion of the woven fabric is coated so as to be integrated with the first layer by a coating layer of a fluorinated polymer having a cation exchange group, and the anode side surface of the membrane corresponds to the surface shape of the woven fabric. Fluorine-containing cation exchange for electrolysis with irregularities Film has been proposed.

  However, in the cation exchange membrane disclosed in Patent Document 1, the reinforcing core material protrudes from the cation exchange membrane. Therefore, when the cation exchange membrane is rubbed with an electrode or the like due to vibration in the electrolytic cell, There is a problem that the resin that has covered the core material is scraped, and the reinforcing core material protrudes therefrom, so that the function of the membrane body as a reinforcing member cannot be achieved.

  When electrolysis is performed by attaching a cation exchange membrane to an electrolytic cell, the voltage (electrolysis voltage) required for electrolysis is reduced, and a low-resistance cation exchange membrane is used to achieve this, It is desired that the cation exchange membrane can exhibit stable electrolysis performance, but the woven fabric as the reinforcing core material is used when cations such as alkali ions flow in the membrane from the anode side to the cathode side. There is a problem that it becomes a shield and prevents the cation from smoothly flowing in the film from the anode side to the cathode side. Therefore, by forming holes (hereinafter referred to as “elution holes”) in the cation exchange membrane for securing a flow path for cations, electrolyte, etc., and securing the flow path for the electrolyte, The electrical resistance of the exchange membrane is reduced.

  However, there is a problem that such elution holes also reduce the membrane strength of the cation exchange membrane. For example, the cation exchange membrane is bent when the cation exchange membrane is attached to an electrolytic cell, or when the cation exchange membrane is carried, and the elution hole is easily bent or becomes a starting point of a pinhole as shown in FIG. There is a problem.

In order to solve such problems, the following Patent Document 2 discloses a cation exchange membrane that is excellent in mechanical strength against bending and can exhibit stable electrolysis performance for a long period of time, and an electrolytic cell and a cation using the cation exchange membrane. An exchange membrane manufacturing method has been proposed.
The cation exchange membrane disclosed in Patent Document 2 includes a membrane main body containing a fluorine-containing polymer having an ion exchange group, and two or more reinforcing core members arranged substantially parallel to the inside of the membrane main body. A cation exchange membrane provided at least, wherein in the membrane body, two or more elution holes are formed between the adjacent reinforcing cores, and the distance between the adjacent reinforcing cores is a, When the distance between the adjacent reinforcing core material and the elution hole is b, the distance between the adjacent elution holes is c, and the number of the elution holes formed between the adjacent reinforcing core materials is n A cation exchange membrane in which a, b, c, and n satisfy a specific relational expression are present. For example, between the first reinforcing cores satisfying the relationship of n = 2 and b> (a / 3) and between the second reinforcing cores satisfying the relationship of n = 2 and c> (a / 3). And cation exchange membranes that exist alternately, that is, the gap between the two polyethylene terephthalate (PET) threads (to form the elution holes) existing between the two PTEFs is widened and narrowed. It was made to exist alternately with things. That is, Patent Document 2 discloses a technique for preventing the occurrence of pinholes by shifting the bending start point from the elution hole by irregularizing the yarn arrangement.

  In Patent Document 2, in order to produce a reinforced core material with an irregular yarn arrangement, two or more reinforced core materials (PTFE), a sacrificial yarn (PET) having a property of being dissolved in acid or alkali, and the reinforcement Polyvinyl alcohol (PVA) dummy yarn having a property of being dissolved in a predetermined solvent that does not dissolve the core material and the sacrificial yarn, so that the sacrificial yarn and the dummy are interposed between the reinforcing core materials adjacent to each other. A step of obtaining a reinforcing material in which a yarn is disposed, a step of removing the dummy yarn from the reinforcing material by immersing the reinforcing material in the predetermined solvent, a reinforcing material from which the dummy yarn has been removed, and an ion A step of forming a membrane body having the reinforcing material by laminating an exchange group or a fluorine-containing polymer having an ion exchange group precursor that can be converted into an ion exchange group by hydrolysis; And a step of forming an elution hole in the membrane main body by immersing it in water and removing the sacrificial yarn from the membrane main body. That is, in Patent Document 2, a woven fabric having an irregular structure is manufactured using a reinforcing core material (PTFE), a dummy yarn (PVA), and a sacrificial yarn (PET), and the obtained woven fabric is used as a sacrificial yarn (PET). By first removing the dummy yarn (PVA), an anomalous fabric is produced, and the anomalous fabric is embedded in the fluoropolymer film as a reinforcing core, and then the sacrificial yarn (PET) Is removed to form an elution hole.

  In this specification, the term “reinforced core material” is broadly woven from PTFE and PET yarn (as a sacrificial yarn for forming an elution hole) to be embedded in a fluorine-containing polymer film. In the narrow sense, it refers only to PTFE that will eventually become the reinforcing core material of the membrane.

  However, in Patent Document 2, as shown in FIG. 4, it is necessary to drive a dummy yarn (PVA) as a weft once when manufacturing a woven fabric having a non-anomalous structure. There is a problem that the speed is reduced and the cost increase for PVA driving is unavoidable.

JP-A-4-308096 International Publication No. 2011/05238

  In view of the above-mentioned problem in Patent Document 2, the problem to be solved by the present invention is a positive strength that is excellent in mechanical strength against bending and the like, can exhibit stable electrolysis performance for a long period of time, and can be woven without using dummy yarn. It is to provide a reinforcing core material for an ion exchange membrane.

  The inventor of the present application has intensively studied and repeated experiments in order to solve the above-mentioned problems. The inventors have found that a woven fabric having an irregular structure can be produced in one step without driving the yarn as a weft, and have completed the present invention.

That is, the present invention is as follows.
[1] As warps, polytetrafluoroethylene (PTFE) fibers, polyethylene terephthalate (PET) multifilaments, and PET multifilaments in the course direction are repeatedly arranged in order, and wefts are reinforced in the wale direction. PTFE fiber as a core material, PET multifilament, reinforced core material for a cation exchange membrane consisting of a woven fabric having a structure in which PET multifilament is repeatedly arranged in order,
Weft PET spreading area where two PET multifilaments as wefts existing between the two nearest PTFE fibers as wefts are spread more than 1/3 of the distance between the two PTFE fibers in the wale direction And at least one of the weft PET narrowing regions arranged narrower than 1/3 of the distance between the two PTFE fibers in the wale direction is included in the wale direction,
In the above-mentioned weft PET spreading region, two PET multifilaments as warps existing between the two nearest PTFE fibers as warps, the two nearest PTFE fibers as wefts, and the wefts arranged between them Two PET multifilaments as the warp yarns in the same number-defining structure consisting of two PET multifilaments, respectively, are the two nearest PTFE fibers as the weft yarns and two PET as the weft yarns adjacent to them respectively. Two PET multifilaments as the warp which are not on the same side with respect to the multifilament have all the wefts in the same number-defining structure and the same number of flat-flat structures crossing alternately, and the warp As the two PET multifilaments, the two nearest PTFE fibers as the weft and the two wefts adjacent to them respectively. The number on the same side of the PET multifilament is 2 on one side of the diagonal line. The number of the same mouth-to-mouth tissue is 1, and the two PET multifilaments as the warp yarns are used as the weft yarns. When the nearest two PTFE fibers and the two PET multifilaments as wefts adjacent to each of them are located on the same side with one place on one side, the number of the same mouth-flat structure is 0.5, The following formula:
Same mouth ratio (%) = total number of mouths / number of same number of defined tissues in the region × 100
The same mouth rate expressed by is 37% or more,
In the weft PET narrowing region, two PET multifilaments as the warp yarns in the same number-defining structure are on the same side with respect to the two PET multifilaments as wefts in the number-of-combinations-defining structure in the formula. There is a single mouth PET tissue with one place on one side, and 50% or more of the same mouth PET tissue is included in the same mouth number defining tissue in the above formula,
The reinforced core material for a cation exchange membrane.
[2] The reinforcing core material for a cation exchange membrane according to the above [1], wherein the weft PET spreading region and the weft PET narrowing region are included in the wale direction and are alternately repeated.
[3] The reinforced core material for a cation exchange membrane according to [1] or [2], wherein the PTFE fiber as a reinforcing core material as the warp and weft is a monofilament.
[4] The following steps:
The reinforcing core material for a cation exchange membrane according to any one of the above [1] to [3], and a fluorine-containing polymer having an ion exchange group or an ion exchange group precursor capable of becoming an ion exchange group by hydrolysis. Laminating and forming a membrane body included in or on the surface of the reinforcing core; and immersing the membrane body in acid or alkali to remove PET multifilaments in the reinforcing core from the body. A step of forming elution holes in the membrane body,
A method for producing a cation exchange membrane, comprising:
[5] A cation exchange membrane produced by the method according to [4].
[6] An electrolytic cell in which the anode, the cathode, and the cation exchange membrane according to the above [5] are disposed therebetween.

  The reinforcing core material according to the present invention is a reinforcing core material for a cation exchange membrane that is an irregularly woven fabric that can be woven without using a dummy yarn. There is no need to drive in, and the weaving speed is improved compared to the case of driving this, leading to cost reduction for the PVA driving. Moreover, the cation exchange membrane manufactured using the reinforcement | strengthening core material which concerns on this invention is excellent in the mechanical strength with respect to bending etc., and can exhibit the electrolysis performance stabilized in the long term.

It is the schematic of an ion exchange membrane method salt electrolysis process. It is sectional drawing explaining the basic structure of an ion exchange membrane. It is the schematic explaining the damage generation | occurrence | production in the elution hole by the bending of an ion exchange membrane. It is the schematic explaining manufacturing a textile fabric of irregular structure by driving a dummy yarn (PVA) and weaving, and then removing the dummy yarn. It is the schematic explaining a plain weave structure. In contrast to plain weaves, in the case of irregularly woven fabrics, the tension between the warp and the weft is used to increase the distance between the two PET wefts between the two PTFE wefts, by applying tension to the warp. It is the schematic explaining that it can narrow. It is the schematic explaining the definition of the various structure | tissue which accept | permits the displacement of the weft in an irregular structure | tissue. It is the schematic explaining the example of calculation of the same mouth ratio in a weft PET spread area. It is a structure chart of the reinforcing core material of Examples 1 and 2. Specific examples of 83% and 67%. 6 is a structural diagram of a reinforcing core material of Example 3. FIG. A specific example of 38% share. It is a structure chart of the reinforcing core material of Examples 4 and 5. Specific examples of 100% and 50% share rate.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. The present invention is not limited to the following embodiment, and can be implemented with various modifications within the scope of the gist. In the drawings, positional relationships such as up, down, left and right are based on the positional relationships shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

<Cation exchange membrane>
FIG. 2 shows a side sectional view of an embodiment of the cation exchange membrane according to this embodiment. The cation exchange membrane includes at least a sulfonic acid layer having a sulfonic acid group as an ion exchange group and a carboxylic acid layer having a carboxylic acid group as an ion exchange group, and a reinforcing material for reinforcing core material described below. (PTFE) and elution holes after the sacrificial yarn of the reinforcing core material is removed are present in the membrane.
As shown in FIG. 1, the membrane body has a function of selectively permeating cations and includes a fluorine-containing polymer. Usually, the sulfonic acid layer is disposed on the anode side of the electrolytic cell, and the carboxylic acid layer is disposed on the cathode side of the electrolytic cell. The sulfonic acid layer is made of a material having low electric resistance, and is preferably thick from the viewpoint of film strength. The carboxylic acid layer preferably has a high anion exclusion property even if the film thickness is small. By using such a carboxylic acid layer, the selective permeability of cations such as sodium ions can be further improved. The membrane main body has a function of selectively permeating cations and may contain a fluorine-containing polymer, and the structure is not necessarily limited to the above structure. Here, the anion exclusion property refers to the property of hindering the penetration and permeation of anions into the cation exchange membrane.

  The fluorine-containing polymer used for the membrane body is a fluorine-containing polymer having an ion exchange group or an ion exchange group precursor that can be converted into an ion exchange group by hydrolysis. For example, the main chain of a fluorinated hydrocarbon And a polymer having a functional group which can be converted into an ion exchange group by hydrolysis or the like as a pendant side chain and which can be melt-processed. An example of a method for producing such a fluorinated polymer will be described below.

The fluorine-containing polymer is, for example, a copolymer of at least one monomer selected from the following first group and at least one monomer selected from the following second group and / or the following third group. Can be manufactured. Moreover, it can also manufacture by the homopolymerization of any one monomer of the following 1st group, the following 2nd group, or the following 3rd group.
Examples of the first group of monomers include vinyl fluoride compounds. Examples of the vinyl fluoride compound include vinyl fluoride, tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, perfluoro (alkyl vinyl ether) and the like. In particular, when the cation exchange membrane 1 according to the present embodiment is used as a membrane for alkaline electrolysis, the vinyl fluoride compound is preferably a perfluoro monomer, such as tetrafluoroethylene, hexafluoropropylene, perfluoro. A perfluoromonomer selected from the group consisting of (alkyl vinyl ether) is preferred.

Examples of the second group of monomers include vinyl compounds having a functional group that can be converted into a carboxylic acid group (carboxylic acid type ion exchange group). As a vinyl compound having a functional group that can be converted into a carboxylic acid group (carboxylic acid type ion exchange group), for example, a single quantity represented by CF ₂ = CF (OCF ₂ CYF) _s —O (CZF) _t —COOR (Wherein s represents an integer of 0 to 2, t represents an integer of 1 to 12, Y and Z each independently represent F or CF ₃ , and R represents a lower alkyl) Represents a group). Among _{them, CF 2 = CF (OCF 2} CYF) n -O (CF 2) a compound represented by _m -COOR are preferred. Here, n represents an integer of 0 to 2, m represents an integer of 1 to 4, Y represents F or CF ₃ , and R represents CH ₃ , C ₂ H ₅ , or C ₃ H ₇ . In particular, when the cation exchange membrane according to the present embodiment is used as a cation exchange membrane for alkaline electrolysis, it is preferable to use at least a perfluoro compound as a monomer. Since the alkyl group (R) is lost from the polymer when it is decomposed, the alkyl group (R) may not be a perfluoroalkyl group in which all hydrogen atoms are substituted with fluorine atoms. Among these, for example, the following monomers are more preferable: CF ₂ ═CFOCF ₂ CF (CF ₃ ) OCF ₂ COOCH ₃ , CF ₂ ═CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) ₂ COOCH ₃ , _{CF 2 = CF [OCF 2 CF} (CF 3)] 2 O (CF 2) 2 COOCH 3, CF 2 = CFOCF 2 CF (CF 3) O (CF 3) 3 COOCH 3, CF 2 = CFO (CF 2) ₂ COOCH ₃ , CF ₂ = CFO (CF ₂ ) ₃ COOCH ₃ .

Examples of the third group of monomers include vinyl compounds having a functional group that can be converted into a sulfonic acid group (sulfone ion exchange group). As the vinyl compound having a functional group that can be converted into a sulfonic acid group (sulfone-type ion exchange group), for example, a monomer represented by CF ₂ = CFO—X—CF ₂ —SO ₂ F is preferred (here, , X represents a perfluoro group). Specific examples thereof include the following monomers: CF ₂ = CFOCF ₂ CF ₂ SO ₂ F,
_{CF 2 = CFOCF 2 CF (CF} 3) OCF 2 CF 2 SO 2 F, CF 2 = CFOCF 2 CF (CF 3) OCF 2 CF 2 CF 2 SO 2 F, CF 2 = CF (CF 2) 2 SO 2 F , CF ₂ = CFO [CF ₂ CF (CF ₃₎ O] _{2 CF 2 CF 2 SO 2 F} , CF 2 = CFOCF 2 CF (CF 2 OCF 3) OCF 2 CF 2 SO 2 F. Among _{them, CF 2 = CFOCF 2 CF (} CF 3) OCF 2 CF 2 CF 2 SO 2 F, and _{CF 2 = CFOCF 2 CF (CF} 3) OCF 2 CF 2 SO 2 F is more preferred.

Copolymers obtained from these monomers can be produced by polymerization methods developed for homopolymerization and copolymerization of fluorinated ethylene, in particular, general polymerization methods used for tetrafluoroethylene. it can. For example, in the non-aqueous method, an inert solvent such as perfluorohydrocarbon or chlorofluorocarbon is used, and in the presence of a radical polymerization initiator such as perfluorocarbon peroxide or azo compound, the temperature is 0 to 200 ° C., the pressure is 0. The polymerization reaction can be performed under conditions of 1 to 20 MPa.
In the copolymerization, the type of monomer combination and the ratio thereof are not particularly limited, and are selected and determined depending on the type and amount of functional groups to be imparted to the resulting fluorinated polymer. For example, when a fluorine-containing polymer containing only a carboxylate ester functional group is used, at least one monomer may be selected from the first group and the second group and copolymerized. Further, when a polymer containing only a sulfonyl fluoride functional group is used, at least one monomer may be selected from the first group and third group monomers and copolymerized. Further, when a fluorine-containing polymer having a carboxylate ester functional group and a sulfonyl fluoride functional group is used, at least one monomer from each of the monomers of the first group, the second group, and the third group is used. It may be selected and copolymerized. In this case, the desired fluorine-containing system can also be obtained by separately polymerizing the copolymer consisting of the first group and the second group and the copolymer consisting of the first group and the third group and mixing them later. A polymer can be obtained. Further, the mixing ratio of each monomer is not particularly limited, but when increasing the amount of the functional group per unit polymer, if the ratio of the monomer selected from the second group and the third group is increased. Good.

  The total ion exchange capacity of the fluorinated copolymer is not particularly limited, but is preferably a dry resin of 0.5 to 2.0 mg equivalent / g, and a dry resin of 0.6 to 1.5 mg equivalent / g. A resin is more preferable. Here, the total ion exchange capacity refers to the equivalent of exchange groups per unit weight of the dry resin, and can be measured by neutralization titration or the like.

  The cation exchange membrane of this embodiment preferably further has a coating layer as necessary from the viewpoint of preventing gas from adhering to the cathode side surface and the anode side surface. Although it does not specifically limit as a material which comprises a coating layer, It is preferable that an inorganic substance is included from a viewpoint of gas adhesion prevention. Examples of the inorganic substance include zirconium oxide and titanium oxide. It does not specifically limit as a method of forming a coating layer, A well-known method can be used. For example, a method in which a liquid in which fine particles of inorganic oxide are dispersed in a binder polymer solution is applied by spraying or the like can be used.

<Reinforced core material>
As described above, the cation exchange membrane has the reinforcing core reinforcing material (PTFE) and the elution holes after the sacrificial yarn of the reinforcing core material is removed.
The reinforcing core material of the present embodiment is a warp yarn in which polytetrafluoroethylene (PTFE) fibers, polyethylene terephthalate (PET) multifilaments, PET multifilaments are repeatedly arranged in order in the course direction, and weft yarns As a reinforcing core material for a cation exchange membrane comprising a woven fabric having a structure in which PTFE fibers, PET multifilaments, and PET multifilaments are sequentially arranged in the wale direction,
Weft PET spreading area where two PET multifilaments as wefts existing between the two nearest PTFE fibers as wefts are spread more than 1/3 of the distance between the two PTFE fibers in the wale direction And at least one of the weft PET narrowing regions arranged to be narrower than 1/3 of the distance between the two PTFE fibers in the wale direction,
In the weft PET spreading region, two PET multifilaments as warps existing between the two nearest PTFE fibers as warps, the two nearest PTFE fibers as wefts, and the wefts arranged between them Two PET multifilaments as the warp yarns in the same number-defining structure consisting of two PET multifilaments, respectively, are the two nearest PTFE fibers as the weft yarns and two PET as the weft yarns adjacent to them respectively. Two PET multifilaments as the warp which are not on the same side with respect to the multifilament have all the wefts in the same number-defining structure and the same number of flat-flat structures crossing alternately, and the warp The two PET multifilaments are the two closest PTFE fibers as the weft and two PET fibers as the weft adjacent to them respectively. The number of the same mouth-to-mouth tissue in which the part on the same side of the rutile filament is diagonally two on one side is 1, and the two PET multifilaments as the warp yarns are the closest as the wefts, respectively. When the same number of the PTFE fibers and two PET multifilaments as wefts adjacent to each other on the same side is one on one side, the same number of the same mouth-flat structure is 0.5. Formula:
Same mouth ratio (%) = total number of mouths / number of same number of defined tissues in the region × 100
The same mouth rate expressed by is 37% or more,
In the weft PET narrowing region, two PET multifilaments as the warp yarns in the same number-defining structure are on the same side with respect to the two PET multifilaments as wefts in the number-of-combinations-defining structure in the formula. There is a single mouth PET tissue with one place on one side, and 50% or more of the same mouth PET tissue is included in the same mouth number defining tissue in the above formula,
Said reinforced core material for cation exchange membrane.

  A reinforced core material is a member that reinforces the mechanical strength and dimensional stability of a cation exchange membrane. Here, the dimensional stability refers to a property capable of suppressing the expansion / contraction of the cation exchange membrane within a desired range. A cation exchange membrane having excellent dimensional stability does not expand and contract more than necessary due to hydrolysis, electrolysis, etc., and has a stable dimension over a long period of time. The reinforcing core material includes at least a reinforcing yarn and a sacrificial yarn for forming an elution hole.

  The reinforced yarn is a member constituting the reinforced core material, and refers to a yarn that can impart desired mechanical strength to the cation exchange membrane and can stably exist in the cation exchange membrane. The material of the reinforcing yarn constituting the reinforcing core material is not particularly limited, but is preferably a material having resistance to acid, alkali and the like. In particular, those containing a fluorine-containing polymer are more preferable from the viewpoint of heat resistance and chemical resistance over a long period of time. Examples of the fluorine-containing polymer herein include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PTA), tetrafluoroethylene-ethylene copolymer (ETFE), and tetrafluoro. Examples thereof include an ethylene-hexafluoropropylene copolymer, a trifluorochloroethylene-ethylene copolymer, and a vinylidene fluoride polymer (PVDF). Among these, from the viewpoint of heat resistance and chemical resistance, polytetrafluoroethylene (PTFE) is used in the present embodiment.

  The yarn diameter of the reinforcing yarn used for the reinforcing core material is not particularly limited, but is preferably 20 to 300 denier, and more preferably 50 to 250 denier. The reinforcing yarn may be a monofilament or a multifilament, and these yarns and slit yarns may be used. A particularly preferable form of the reinforcing core material is a reinforcing core material containing PTFE from the viewpoint of chemical resistance and heat resistance, and from the viewpoint of strength, a tape yarn yarn or a highly oriented monofilament. Specifically, the form of the woven fabric remaining in the cation exchange membrane after removing the sacrificial yarn is a tape yarn obtained by slitting a high-strength porous sheet made of PTFE into a tape shape, or highly oriented made of PTFE. A woven fabric using monofilaments of 50 to 300 denier, a weaving density of 10 to 50 pieces / inch, and a thickness of 50 to 100 μm is preferable. Further, the opening ratio of the reinforcing core material in the form of a woven fabric remaining in the cation exchange membrane after removing the sacrificial yarn is not particularly limited, and is preferably 30% or more and 90% or less. The aperture ratio is preferably 30% or more from the viewpoint of the electrochemical properties of the cation exchange membrane, preferably 90% or less, more preferably 50% or more from the viewpoint of the mechanical strength of the membrane. More preferably, it is 60% or more.

  Here, the aperture ratio is the ratio of the total area (B) through which substances such as ions can pass through the cation exchange membrane to the total surface area (A) of the cation exchange membrane, and (B) / (A) It is represented by (B) is the total of the areas of the cation exchange membrane where cations, electrolytes, etc. are not blocked by the reinforcing core material, reinforcing yarns, etc. contained in the cation exchange membrane. A specific method for measuring the aperture ratio will be described. A surface image of a cation exchange membrane (cation exchange membrane before coating or the like) is taken, and the above (B) is obtained from the area of the portion where the reinforcing core material does not exist. And said (A) is calculated | required from the area of the surface image of a cation exchange membrane, and said aperture ratio is calculated | required by remove | dividing said (B) by said (A).

The form of the reinforcing core material of the present embodiment is a woven fabric composed of reinforcing yarns and sacrificial yarns, and the weaving method is not a plain weave structure but an irregular structure as described below. Although the thickness of a woven fabric is not specifically limited, It is preferable that it is 30-250 micrometers, and it is more preferable that it is 30-150 micrometers. Further, the weaving density of the reinforcing yarn (the number of driving per unit length) is not particularly limited, but is preferably 5 to 50 / inch.
FIG. 5 shows a plain weave structure. In a plain weave structure, ups and downs of warps are repeated alternately throughout the entire fabric.

  As described above, in the reinforcing core material of the present embodiment, the two PET multifilaments as the weft existing between the two nearest PTFE fibers as the weft are the distance between the two PTFE fibers in the wale direction. At least any one of the weft PET spread areas arranged wider than 1/3 and the weft PET narrow areas arranged narrower than 1/3 of the distance between the two PTFE fibers in the wale direction It is characterized by being included. Thereby, even when the membrane is bent when handling the cation exchange membrane, it is possible to prevent a problem that a pinhole is generated due to an excessive load applied to the portion of the sacrificial yarn elution hole.

The sacrificial yarn is a yarn that has a property of dissolving in an acid or an alkali and forms an elution hole in the cation exchange membrane. Examples of the sacrificial yarn include polyvinyl alcohol (PVA), rayon, polyethylene terephthalate (PET), cellulose, polyamide and the like. Among these, PET from the viewpoint of stability during weaving and solubility in acid or alkali. Is preferred.
The blended amount of the sacrificial yarn is preferably 10 to 80% by mass, more preferably 30 to 70% by mass, based on the entire reinforcing core material. The sacrificial yarn has a thickness of 20 to 50 denier and may be monofilament or multifilament.
In the reinforcing core material of the present embodiment, the dummy yarn that is expected to be removed under a condition that is milder than that of the sacrificial yarn is not woven between the sacrificial yarns or between the reinforcing yarn and the sacrificial yarn.

  The elution hole is a hole that can serve as a flow path for cations generated during electrolysis or an electrolyte. By forming the elution holes, the mobility of alkali ions generated during electrolysis and the electrolyte solution can be secured. The shape of the elution hole is not particularly limited. When producing a cation exchange membrane according to the production method described later, the sacrificial yarn dissolved in acid or alkali forms the elution hole of the membrane body, so that the shape of the elution hole becomes the shape of the sacrificial yarn. As shown in FIG. 2, the cation exchange membrane includes an elution hole formed in a direction perpendicular to the paper surface and an elution hole formed in the vertical direction of the paper surface. In other words, the elution holes formed in the vertical direction of the paper surface are formed along a direction substantially perpendicular to the reinforcing yarn (reinforcing material). The elution holes are preferably formed so as to alternately pass through the anode side (sulfonic acid layer side) and the cathode side (carboxylic acid layer side) of the reinforcing core material. With such a structure, the cation (for example, sodium ion) transported through the electrolyte filled in the elution hole can also flow to the cathode side of the reinforcing material, so that the cation flow is shielded. Therefore, the electric resistance of the cation exchange membrane can be further reduced.

Hereinafter, in the reinforcing core material of the present embodiment, two PET multifilaments as wefts existing between the two nearest PTFE fibers as wefts are 1/3 of the distance between the two PTFE fibers in the wale direction. At least one of the weft PET spreading area arranged more widely and the weft PET narrowing area arranged narrower than 1/3 of the distance between the two PTFE fibers in the wale direction is included in the wale direction The principle for forming an organization (hereinafter also referred to as an anomaly principle) will be described.
FIG. 6 shows an irregular weave structure in which the warp ups and downs of the plain weave structure is changed at four locations. In such an irregular weave structure, as shown in the sectional view of the second warp from the right, when the warp is tensioned, the weft is displaced away from the intersection of the warp and the weft. By arranging a woven structure that allows such displacement of the weft in a desired ratio in the entire woven fabric, it is possible to form a structure in which the weft PET spreading region and the weft PET narrowing region are included in the wale direction.

In FIG. 7, a structure that allows displacement of the weft is defined.
First, two PET multifilaments as warps existing between the two most recent PTFE fibers as warp yarns, two recent PTFE fibers as weft yarns, and two PET multifilaments as weft yarns arranged between them And the same number definition organization. As in FIG. 5, a cross indicates that the warp is behind the weft.

  Within the same number-defining structure, the two PET multifilaments as the warp are the same side with respect to the two nearest PTFE fibers as the weft and the two PET multifilaments as the weft adjacent to them respectively. In addition, two PET multifilaments as the warp define 0 as the same number of flat-flat textures crossing alternately with all the wefts in the same number-defining structure (upper left structure in FIG. 7). .

  Within the same number-defining structure, the two PET multifilaments as the warp are the same side with respect to the two nearest PTFE fibers as the weft and the two PET multifilaments as the weft adjacent to them respectively. Is defined as 1 (tissue on the upper right in FIG. 7). In the same mouth-same mouth structure, the PTFE yarn and the PET yarn are brought together on both sides (the two xx-marked portions on the diagonal line) by the anomaly principle described above.

  Within the same number-defining structure, the two PET multifilaments as the warp are the same side with respect to the two nearest PTFE fibers as the weft and the two PET multifilaments as the weft adjacent to them respectively. The number of the same mouth-flat structure having one place on one side is defined as 0.5 (the lower left structure in FIG. 7). In the same neck-flat structure, the PTFE yarn and the PET yarn are brought close to each other on one side (one xx mark portion) by the anomaly principle described above.

  Also, in the same-compartment-defining structure, a structure in which two PET multifilaments as warps are on the same side of two PET multifilaments as wefts on one side is defined as a same-mouth PET structure. (The organization at the lower right in FIG. 7). In such a same mouth PET structure, engaging PET fibers are brought together.

In the weft PET spreading region, the following formula:
Same mouth ratio (%) = total number of mouths / number of same number of defined tissues in the region × 100
Define the share rate expressed by.
FIG. 8 shows that when the number of defined mouthpieces is 6, the number of mouthpiece-to-mouth tissues is one, the number of mouth-to-flat tissues is four, and the number of head-to-flat tissues is one. An example of calculating the mouthpiece ratio in a certain case is shown. In this case, since the total number of joints in the weft PET spreading region is 3 and the number of defined mouthpieces is 6, the joint rate is calculated as 50%.

The joint ratio of the weft PET spreading area of the reinforcing core material of the present embodiment is 37% or more as described in the following examples, and the unit number of mouths defined in the weft PET narrowing area There is a homologous PET tissue, 50% or more of the homologous PET tissue is included in the homologous number defining tissue in the above formula, and the remaining tissues are all the flat-flat tissue. If the PET spreading area has a mouth opening ratio of less than 37%, the interval between two adjacent weft PETs cannot be sufficiently widened, and when the film is bent, the sacrificial yarn elution hole is overloaded. Therefore, the occurrence of pinholes cannot be prevented. . In addition, when the same mouth PET structure is less than 50%, the interval between two adjacent weft PET cannot be sufficiently narrowed, and when the membrane is bent, the sacrificial yarn elution hole is overloaded. , Can not prevent the occurrence of pinholes.
Thus, in the reinforcing core material of this embodiment, two PET multifilaments as wefts existing between the two nearest PTFE fibers as wefts are 1 / of the distance between the two PTFE fibers in the wale direction. At least one of the weft PET spreading region arranged wider than 3 and the weft PET narrowed region arranged narrower than 1/3 of the distance between the two PTFE fibers in the wale direction is in the wale direction. As a result of the formation of the contained structure, when a cation exchange membrane is produced using this structure, the generation of cracks can be effectively prevented by shifting the bending start point from the sacrificial yarn elution hole.

  4 to 10, the MD direction (machine direction) refers to a membrane main body and various reinforcing core materials (for example, reinforcing yarns, sacrificial yarns, etc. when weaving a reinforcing material in the production of a cation exchange membrane described later. It refers to the direction (“flow direction”) in which the resulting core material is conveyed. The MD yarn means a yarn woven (knitted) along the MD direction. The TD direction (traverse direction) means a direction substantially perpendicular to the MD direction. , Thread woven along the TD direction. In the reinforced core material of the woven fabric of this embodiment, the MD direction is a warp method, and the TD direction is a weft direction.

  Usually, the cation exchange membrane has a rectangular shape, and the longitudinal direction is often the MD direction and the width direction is often the TD direction. Such a cation exchange membrane is wound and transported around a cylinder such as a vinyl chloride tube until it is shipped or attached to the electrolytic cell. When winding around a cylinder, in order to shorten the length of the cylinder, the TD direction of the cation exchange membrane becomes a broken line, and the cation exchange membrane may be bent. Even in such a case, if the cation exchange membrane has the above-described configuration, it is possible to efficiently avoid the concentration of load in the TD direction, thereby effectively preventing the occurrence of pinholes.

<Manufacturing method>
The method for producing a cation exchange membrane according to this embodiment includes the following steps:
The reinforcing core material for a cation exchange membrane according to claim 1 or 2 and a fluorine-containing polymer having an ion exchange group or an ion exchange group precursor that can be converted into an ion exchange group by hydrolysis, are laminated, A step of forming a membrane body included in or on the surface of the core material; and the membrane body is immersed in an acid or alkali to remove PET multifilaments in the reinforced core material from the body; Forming elution holes;
including.

  In the manufacturing method of the reinforcing core material of the present embodiment, one of the features is that the intervals between the elution holes formed between the most recent reinforcing yarns are not equal, but in order to realize such a structure, Do not use dummy yarn (eg PVA yarn) that can be removed even under mild conditions.

  Although not shown, in MD yarns, a method of passing two or more yarns from among reinforcing yarns, sacrificial yarns, and the like, and reinforcing yarns, sacrificial yarns, etc. are passed through one weave of a loom. The sacrificial yarn or the like in the reinforcing core can be arranged at an arbitrary interval also by a method of providing a mesh that does not pass the yarn between the meshes. For example, in the MD direction, it can be adjusted by changing the combination of the types of yarns (reinforcing yarns, sacrificial yarns, etc.) that pass through one weave of the loom. For example, when passing a bundle of reinforcing yarn-sacrificial yarn through the first mesh, passing a bundle of sacrificial yarn-reinforced yarn through the second mesh, passing a sacrificial yarn-sacrificial yarn through the third mesh, The reinforcing yarn, the sacrificial yarn, the sacrificial yarn, the reinforcing yarn, the sacrificial yarn, and the sacrificial yarn can be arranged in this order. Thereby, the arrangement | positioning space | interval of the sacrificial yarn in a reinforcement can be controlled.

  However, in the method for manufacturing a reinforced core material according to the present embodiment, even under general weaving conditions of a plain weave structure, the plain weave structure is changed to a predetermined ratio to the irregular structure described above, thereby changing the warp tension. The weft is displaced by the anomaly principle, and a fabric with a desired anomalous structure can be produced. As a result, when producing a woven fabric that is a reinforcing core material for a cation exchange membrane, which is an irregularly woven fabric that can be woven without using a dummy yarn, it is not necessary to drive the dummy yarn (PVA) as a weft. Compared to the above, an advantageous effect as compared with the invention of the prior art that the weaving speed is improved and the cost for driving the PVA is reduced is exhibited.

The reinforcing material manufactured in this way can form a film body having a reinforcing core material by laminating the fluorine-containing polymer having an ion exchange group without the necessity of removing the dummy yarn. it can. As a preferable method for forming the film body, a method of performing the following steps (1) and (2) and the like can be mentioned.
(1) A fluorine-containing polymer layer containing a carboxylate ester functional group located on the cathode side (hereinafter referred to as “first layer”) and a fluorine-containing polymer layer having a sulfonyl fluoride functional group (Hereinafter referred to as “second layer”) is formed into a film by a coextrusion method. Further, the reinforcing material, the second layer / first layer composite film is provided on a flat plate or drum having a heating source and a vacuum source, and having pores on the surface thereof, through a heat-resistant release paper having air permeability. Laminate sequentially. Under the temperature at which each polymer melts, the pressure is reduced and the air is removed between the layers, and they are integrated.
(2) Separately from the second layer / first layer composite film, a fluorine-containing polymer layer having a sulfonyl fluoride functional group (hereinafter referred to as “third layer”) is formed into a single film in advance. A third layer film, a reinforcing material, a second layer / second layer are provided on a flat plate or drum having a heating source and a vacuum source and having pores on the surface via a heat-resistant release paper having air permeability. Laminate in order of one-layer composite film. Under the temperature at which each polymer melts, the pressure is reduced and the air is removed and the layers are integrated. In this case, the direction in which the extruded film flows is the MD direction.

  Here, co-extrusion of the first layer and the second layer contributes to increasing the adhesive strength of the interface. Moreover, the method of integrating under reduced pressure has the characteristic that the thickness of the 3rd layer on a reinforcing material becomes large compared with the press-pressing method. Furthermore, since the reinforcing core material is fixed inside the cation exchange membrane, the mechanical strength of the cation exchange membrane can be sufficiently maintained.

  For the purpose of further enhancing the durability of the cation exchange membrane, a layer containing both a carboxylic acid ester functional group and a sulfonyl fluoride functional group (hereinafter referred to as “fourth”) between the first layer and the second layer. It is also possible to use a layer containing both a carboxylic acid ester functional group and a sulfonyl fluoride functional group as the second layer. In this case, a method of mixing a polymer containing a carboxylic acid ester functional group and a polymer containing a sulfonyl fluoride functional group separately after production, or a monomer containing a carboxylic acid ester functional group may be used. And a method using a copolymer of both a monomer containing a sulfonyl fluoride functional group.

  When the fourth layer is configured as a cation exchange membrane, a coextruded film of the first layer and the fourth layer is formed, and the second layer and the third layer are separately formed into a film separately from the above, You may laminate by the method of. Alternatively, the first layer / fourth layer / second layer may be formed into a film by coextrusion at a time. In this way, a membrane body containing a fluorine-containing polymer having an ion exchange group can be formed on the reinforcing core material.

  Furthermore, the sacrificial yarn contained in the membrane main body is dissolved and removed with an acid or alkali to form elution holes in the membrane main body. The sacrificial yarn is soluble in acid or alkali in the cation exchange membrane manufacturing process or electrolysis environment, and the sacrificial yarn elutes to form elution holes. In this way, a cation exchange membrane having an elution hole formed in the membrane body can be obtained.

  Moreover, it is preferable that the cation exchange membrane which concerns on this embodiment has the protrusion part which consists only of the polymer which has an ion exchange group in the sulfonic acid layer side (anode surface side, refer FIG. 2). The protruding portion is preferably made of only resin. The projecting portion is formed by embossing the release paper that can be used when the second layer / first layer composite film and the reinforcing material are integrated. Is also possible.

  The cation exchange membrane according to this embodiment can be used in various electrolytic cells (see FIG. 1). The electrolytic cell includes at least an anode, a cathode, and a cation exchange membrane according to the present embodiment disposed between the anode and the cathode. Although an electrolytic cell can be used for various electrolysis, the case where it is used for electrolysis of aqueous alkali chloride solution is demonstrated as a typical example below.

Electrolysis conditions are not particularly limited, and can be performed under known conditions. For example, 2.5 to 5.5 normal (N) alkali chloride aqueous solution is supplied to the anode chamber, water or diluted alkali hydroxide aqueous solution is supplied to the cathode chamber, the electrolysis temperature is 50 to 120 ° C., and the current density is it is possible to electrolysis under the conditions of 5~100A / dm ^2.

  The configuration of the electrolytic cell according to this embodiment is not particularly limited, and may be, for example, a monopolar type or a bipolar type. The material constituting the electrolytic cell is not particularly limited. For example, the material for the anode chamber is preferably titanium or the like resistant to alkali chloride and chlorine, and the material for the cathode chamber is resistant to alkali hydroxide and hydrogen. Nickel or the like is preferred. The electrode may be arranged with an appropriate interval between the cation exchange membrane and the anode, but can be used without any problem even if the anode and the ion exchange membrane are arranged in contact with each other. In addition, the cathode is generally arranged at an appropriate distance from the cation exchange membrane, but even if it is a contact type electrolytic cell (zero gap type electrolytic cell) without this distance, it can be used without any problems. it can.

  In particular, the cation exchange membrane of this embodiment has elution holes arranged at unequal intervals as compared to a conventional cation exchange membrane in which elution holes serving as passages for various substances such as cations are arranged at equal intervals. This reduces the resistance of the cation. As a result, the electrolysis voltage is reduced. In addition, since the elution hole is arranged near the reinforcing yarn that shields the cation, the shielding region through which the cation passes is reduced, and the resistance of the cation is further reduced. As a result, the electrolytic voltage is further reduced. Become.

  Hereinafter, the present invention will be described specifically by way of examples. In addition, this invention is not limited to a following example.

[Measurement of bending resistance]
The degree of strength reduction (bending resistance) due to bending of the cation exchange membrane was evaluated by the following method. The bending resistance is the ratio of the tensile elongation of the cation exchange membrane after bending with respect to the tensile elongation of the cation exchange membrane before bending (tensile elongation ratio).
The tensile elongation was measured by the following method. A sample having a width of 1 cm was cut along a direction of 45 degrees with respect to the reinforcing yarn embedded in the cation exchange membrane. Then, the tensile elongation of the sample was measured according to JIS K6732 under the conditions of a distance between chucks of 50 mm and a tensile speed of 100 mm / min.

The cation exchange membrane was bent by the following method. The surface of the cation exchange membrane on the side of the carboxylic acid layer (refer to the carboxylic acid layer 144 in FIG. 1 and “polymer A layer” described later) was inward, and was bent with a load of 400 g / cm ² . In MD folding, the cation exchange membrane was folded and evaluated so that a fold line would be perpendicular to the MD yarn of the cation exchange membrane (MD folding). In the TD folding, the cation exchange membrane was folded and evaluated so that a fold line was formed in a direction perpendicular to the TD yarn of the cation exchange membrane (TD folding). Therefore, MD bending can measure the contribution to bending resistance by controlling the interval between the reinforcing core material and the elution hole arranged along the TD direction, and the TD bending is the reinforcement arranged along the MD direction. The contribution to bending resistance can be measured by controlling the distance between the core material and the elution hole.
The tensile elongation of the cation exchange membrane after performing MD bending or TD bending was measured, and the ratio to the tensile elongation before bending was determined to determine the bending resistance.

[Example 1]
As the reinforcing core material, a 90 denier monofilament made of polytetrafluoroethylene (PTFE) was used (hereinafter referred to as “PTFE yarn”). As the sacrificial yarn, a 40 denier, 6-filament polyethylene terephthalate (PET) twisted 200 times / m was used (hereinafter referred to as “PET yarn”).

  First, PTFE yarns were arranged so as to be arranged at approximately equal intervals of 24 pieces / inch. For the warp, three consecutive cocoons are used to pass a bundle of two PTFE and PET yarns through the first cocoon, and two bundles of two PET and PTFE yarns. A bundle of two yarns, a PET yarn and a PET yarn, was passed through the third kite through the third kite. Then, a bundle of yarns was sequentially passed through the reed so that this combination was repeated in order.

  Adjacent warp PTFE yarns use two wrinkle frames alternately, warp PET yarns use 12 different warp frames, PTFE warp yarns have two degrees of freedom, and PET warp yarns have 12 degrees of freedom. Gave a degree of freedom.

  As for the weft, as shown in Sample 1 of FIG. 9, the order of PTFE yarn, PET yarn, and PET yarn was repeatedly woven. In the sample 1 of FIG. 9, the x mark means that the warp is lifted up, and the unmarked means that the warp is lowered, and in the above-described weft PET spreading area, the mouthpiece ratio is 83%, and the weft PET narrowing area. Inside, a woven fabric (reinforcing material) having 67% of the same PET structure was obtained.

  The warp tension during weaving was 5 to 20 g / piece for both PTFE and PET yarns.

  Subsequently, the obtained reinforcing material was immersed in a 0.1N sodium hydroxide aqueous solution and pressed with a roll heated to 125 ° C.

Next, it is a copolymer of tetrafluoroethylene (CF ₂ = CF ₂ ) and CF ₂ = CFOCF ₂ CF (CF ₃ ) OCF ₂ CF ₂ COOCH _3, with a total ion exchange capacity of 0.85 mg equivalent / g A polymer A of a dry resin, and a copolymer of CF ₂ ═CF ₂ and CF ₂ ═CFOCF ₂ CF (CF ₃ ) OCF ₂ CF ₂ SO ₂ F, with a total ion exchange capacity of 1.05 mg equivalent / A dry resin polymer B, which is g, was prepared. Using the polymers A and B, a two-layer film X comprising a polymer A layer having a thickness of 13 μm and a polymer B layer having a thickness of 84 μm was obtained by a coextrusion T-die method. Further, a film Y having a thickness of 20 μm made of polymer B was obtained by a single layer T-die method.

  Next, a release paper, a film Y, a reinforcing material, and a film X were laminated in this order on a drum having a heating source and a vacuum source inside and having fine holes on the surface, and heated and decompressed. The processing temperature at this time was 219 ° C., and the degree of vacuum was 0.022 MPa. Thereafter, the release paper was removed to obtain a composite film. The obtained composite membrane was hydrolyzed by immersing it in an aqueous solution containing 30% by mass of dimethyl sulfoxide (DMSO) and 15% by mass of potassium hydroxide (KOH) at 90 ° C. for 1 hour, and then washed with water and dried. I let you. As a result, the sacrificial yarn (PET yarn) was dissolved to obtain a membrane body in which elution holes were formed.

Further, a suspension was prepared by adding and dispersing zirconium oxide having a primary particle diameter of 1 μm in a 5% by mass ethanol solution of an acid type polymer of polymer B in a proportion of 20% by mass. The suspension is sprayed on both sides of the composite membrane by spraying and dried to form a 0.5 mg / cm ² coating layer on the surface of the composite membrane, and the cation exchange membrane shown in FIG. Got. The cation exchange membrane of FIG. 2 has a membrane body (not shown) and a reinforcing core material inside thereof, and the membrane body has two elution holes between adjacent reinforcing core materials. Has a formed structure.

  The physical properties of the obtained cation exchange membrane are shown in Table 1 below. In Table 1 below, between the reinforcing core materials arranged alternately adjacent to each other in the TD direction of the cation exchange membrane of Example 1 is described as the reinforcing core material interval T1 and the reinforcing core material interval T2, respectively. In the MD direction, repeated structural units are described as the reinforcing core material M1 and the reinforcing core material M2. The following examples and comparative examples were also described in each table in the same manner. As shown in Table 1 below, it was confirmed that both MD folding and TD folding had a high tensile elongation retention.

[Example 2]
A cation exchange membrane was produced using the same material as in Example 1 except that the woven structure of the reinforcing core material was Sample 2 in FIG. The reinforced fabric (reinforcing material) having a mouth opening ratio of 67% in the PET spreading region of the obtained reinforcing core material and a mouth opening PET structure of 67% in the PET narrowing region was obtained. As shown in Table 1 below, the produced cation exchange membrane was confirmed to have a high tensile elongation retention rate in both MD folding and TD folding.

Example 3
A cation exchange membrane was prepared using the same material as in Example 1 except that the number of cocoon frames used for the warp PET was 8 and the woven structure of the reinforcing core material was Sample 3 in FIG. The reinforced fabric (reinforcing material) was obtained in which the joint opening ratio of the obtained reinforcing core material in the PET spreading region was 38%, and in the PET narrowing region, the mouth opening PET structure was 75%. As shown in Table 1 below, the produced cation exchange membrane was confirmed to have a high tensile elongation retention rate in both MD folding and TD folding.

Example 4
A cation exchange membrane was prepared using the same material as in Example 1 except that the number of cocoon frames used for the warp PET was 4 and the weaving structure of the reinforcing core material was Sample 4 in FIG. The reinforced fabric (reinforcing material) was obtained in which the joint ratio of the obtained reinforcing core material in the PET spreading region was 100%, and in the PET narrowing region, the joint mouth PET structure was 100%. As shown in Table 1 below, the produced cation exchange membrane was confirmed to have a high tensile elongation retention rate in both MD folding and TD folding.

Example 5
A cation exchange membrane was produced using the same material as in Example 1 except that the number of cocoon frames used for the warp PET was 4 and the woven structure of the reinforcing core material was Sample 5 in FIG. The reinforced fabric (reinforcing material) was obtained in which the joint ratio of the obtained reinforcing core material in the PET spreading region was 50%, and in the PET narrowing region, the joint mouth PET structure was 100%. As shown in Table 1 below, the produced cation exchange membrane was confirmed to have a high tensile elongation retention rate in both MD folding and TD folding.
Example 6
A cation exchange membrane was prepared in the same manner as in Example 3 except that the warp PTFE was a tape yarn twisted at a twisting number of 1120 T / m. The reinforced fabric (reinforcing material) was obtained in which the joint opening ratio of the obtained reinforcing core material in the PET spreading region was 38%, and in the PET narrowing region, the mouth opening PET structure was 75%. As shown in Table 1 below, the produced cation exchange membrane was confirmed to have a high tensile elongation retention rate in both MD folding and TD folding.

[Comparative Example 1]
A cation exchange membrane was prepared using the same material as in Example 1 except that the woven structure of the reinforcing core material was plain woven. In the obtained reinforcing core material, there was no distinction between the PET spreading region and the PET narrowing region, and a woven fabric (reinforcing material) was obtained in which the same mouth ratio was 0% and the same mouth PET structure did not exist. As shown in Table 1, the produced cation exchange membrane had a low tensile elongation retention rate in both MD bending and TD bending.

  Since the reinforcing core material according to the present invention is a reinforcing core material for a cation exchange membrane that is an irregularly woven fabric that can be woven without using dummy yarns, dummy yarns (PVA) are used as weft yarns when manufacturing such fabrics. There is no need to drive in, and the weaving speed is improved compared to the case of driving this, leading to cost reduction for the PVA driving. Moreover, the cation exchange membrane manufactured using the reinforcement | strengthening core material which concerns on this invention is excellent in the mechanical strength with respect to bending etc., and can exhibit the electrolysis performance stabilized in the long term. Therefore, the reinforcing core material according to the present invention can be suitably used as a reinforcing core material for a cation exchange membrane.

Claims (6)

As warps, polytetrafluoroethylene (PTFE) fibers, polyethylene terephthalate (PET) multifilaments, and PET multifilaments as reinforcing cores in the course direction are repeatedly arranged in order, and as wefts, as reinforcing cores in the wale direction PTFE fiber, PET multifilament, reinforced core material for a cation exchange membrane consisting of a woven fabric having a structure in which PET multifilament is repeatedly arranged in order,
Weft PET spreading area where two PET multifilaments as wefts existing between the two nearest PTFE fibers as wefts are spread more than 1/3 of the distance between the two PTFE fibers in the wale direction And at least one of the weft PET narrowing regions arranged narrower than 1/3 of the distance between the two PTFE fibers in the wale direction is included in the wale direction,
In the weft PET spreading region, two PET multifilaments as warps existing between the two nearest PTFE fibers as warps, the two nearest PTFE fibers as wefts, and the wefts arranged between them Two PET multifilaments as the warp yarns in the same number-defining structure consisting of two PET multifilaments, respectively, are the two nearest PTFE fibers as the weft yarns and two PET as the weft yarns adjacent to them respectively. Two PET multifilaments as the warp which are not on the same side with respect to the multifilament have all the wefts in the same number-defining structure and the same number of flat-flat structures crossing alternately, and the warp The two PET multifilaments are the two closest PTFE fibers as the weft and two PET fibers as the weft adjacent to them respectively. The number of the same mouth-to-mouth tissue in which the part on the same side of the rutile filament is diagonally two on one side is 1, and the two PET multifilaments as the warp yarns are the closest as the wefts, respectively. When the same number of the PTFE fibers and two PET multifilaments as wefts adjacent to each other on the same side is one on one side, the same number of the same mouth-flat structure is 0.5. Formula:
Same mouth ratio (%) = total number of mouths / number of same number of defined tissues in the region × 100
The same mouth rate expressed by is 37% or more,
In the weft PET narrowing region, two PET multifilaments as the warp yarns in the same number-defining structure are on the same side with respect to the two PET multifilaments as wefts in the number-of-combinations-defining structure in the formula. There is a single mouth PET tissue with one place on one side, and 50% or more of the same mouth PET tissue is included in the same mouth number defining tissue in the above formula,
The reinforced core material for a cation exchange membrane.   The reinforcing core material for a cation exchange membrane according to claim 1, wherein the weft PET spreading region and the weft PET narrowing region are included in the wale direction and are alternately repeated.   The reinforcing core material for a cation exchange membrane according to claim 1 or 2, wherein the PTFE fiber as the reinforcing core material as the warp and weft is a monofilament. The following steps:
A laminate of the reinforcing core material for a cation exchange membrane according to any one of claims 1 to 3 and a fluorine-containing polymer having an ion exchange group or an ion exchange group precursor capable of becoming an ion exchange group by hydrolysis. A step of forming a membrane main body included in or on the surface of the reinforcing core, and immersing the membrane main body in acid or alkali to remove PET multifilaments in the reinforcing core from the main body. A step of forming elution holes in the membrane body;
A method for producing a cation exchange membrane, comprising:   A cation exchange membrane produced by the method according to claim 4.   An electrolytic cell in which an anode, a cathode, and the cation exchange membrane according to claim 5 are disposed therebetween.

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