Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
  • B01D67/0002—Organic membrane manufacture
  • B01D67/0006—Organic membrane manufacture by chemical reactions
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/20—Manufacture of shaped structures of ion-exchange resins
  • C08J5/22—Films, membranes or diaphragms
  • C08J5/2206—Films, membranes or diaphragms based on organic and/or inorganic macromolecular compounds
  • C08J5/2218—Synthetic macromolecular compounds
  • C08J5/2231—Synthetic macromolecular compounds based on macromolecular compounds obtained by reactions involving unsaturated carbon-to-carbon bonds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
  • B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
  • B01D69/10—Supported membranes; Membrane supports
  • B01D69/107—Organic support material
  • B01D69/1071—Woven, non-woven or net mesh
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
  • B01D71/06—Organic material
  • B01D71/28—Polymers of vinyl aromatic compounds
  • B01D71/281—Polystyrene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
  • B01D71/06—Organic material
  • B01D71/30—Polyalkenyl halides
  • B01D71/301—Polyvinylchloride
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J39/00—Cation exchange; Use of material as cation exchangers; Treatment of material for improving the cation exchange properties
  • B01J39/04—Processes using organic exchangers
  • B01J39/05—Processes using organic exchangers in the strongly acidic form
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J39/00—Cation exchange; Use of material as cation exchangers; Treatment of material for improving the cation exchange properties
  • B01J39/08—Use of material as cation exchangers; Treatment of material for improving the cation exchange properties
  • B01J39/16—Organic material
  • B01J39/18—Macromolecular compounds
  • B01J39/20—Macromolecular compounds obtained by reactions only involving unsaturated carbon-to-carbon bonds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J47/00—Ion-exchange processes in general; Apparatus therefor
  • B01J47/12—Ion-exchange processes in general; Apparatus therefor characterised by the use of ion-exchange material in the form of ribbons, filaments, fibres or sheets, e.g. membranes
  • B01J47/127—Ion-exchange processes in general; Apparatus therefor characterised by the use of ion-exchange material in the form of ribbons, filaments, fibres or sheets, e.g. membranes in the form of filaments or fibres
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/20—Manufacture of shaped structures of ion-exchange resins
  • C08J5/22—Films, membranes or diaphragms
  • C08J5/2206—Films, membranes or diaphragms based on organic and/or inorganic macromolecular compounds
  • C08J5/2218—Synthetic macromolecular compounds
  • C08J5/2231—Synthetic macromolecular compounds based on macromolecular compounds obtained by reactions involving unsaturated carbon-to-carbon bonds
  • C08J5/2243—Synthetic macromolecular compounds based on macromolecular compounds obtained by reactions involving unsaturated carbon-to-carbon bonds obtained by introduction of active groups capable of ion-exchange into compounds of the type C08J5/2231
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2325/00—Details relating to properties of membranes
  • B01D2325/22—Thermal or heat-resistance properties
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2325/00—Details relating to properties of membranes
  • B01D2325/24—Mechanical properties, e.g. strength
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2325/00—Details relating to properties of membranes
  • B01D2325/26—Electrical properties
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2325/00—Details relating to properties of membranes
  • B01D2325/42—Ion-exchange membranes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
  • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
  • C08J2323/04—Homopolymers or copolymers of ethene
  • C08J2323/06—Polyethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2325/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Derivatives of such polymers
  • C08J2325/02—Homopolymers or copolymers of hydrocarbons
  • C08J2325/04—Homopolymers or copolymers of styrene
  • C08J2325/08—Copolymers of styrene
  • C08J2325/12—Copolymers of styrene with unsaturated nitriles
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2423/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
  • C08J2423/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
  • C08J2423/04—Homopolymers or copolymers of ethene
  • C08J2423/06—Polyethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2425/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Derivatives of such polymers
  • C08J2425/18—Homopolymers or copolymers of aromatic monomers containing elements other than carbon and hydrogen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2427/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
  • C08J2427/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
  • C08J2427/04—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing chlorine atoms
  • C08J2427/06—Homopolymers or copolymers of vinyl chloride
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
  • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
  • Y02A20/124—Water desalination
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/30—Hydrogen technology
  • Y02E60/50—Fuel cells

Definitions

• the present invention relates to a cation exchange membrane and a method for producing the same.
• the ion exchange membrane is a film of ion exchange resin, but it is mechanically brittle because it has a crosslinked structure as it is. Therefore, in order to improve the mechanical strength, a porous base material having a function as a reinforcing material is used, and the structure is such that an ion exchange resin layer is provided with this base material as a core.
• the so-called paste method is known as a method for producing such an ion exchange membrane, and according to this paste method, it is possible to have an ion exchange group or introduce an ion exchange group into a base material having a function as a reinforcing material.
• An ion exchange membrane is produced by applying a polymerizable monomer paste, then polymerizing the monomer, and then introducing an ion exchange group if necessary (see, for example, Patent Document 1).
• a polyolefin resin or polyvinyl chloride is generally used as a base material having a function as a reinforcing material.
• Polyolefin-based resins are superior to polyvinyl chloride in terms of alkali resistance, strength, and heat resistance. Therefore, in the ion exchange membrane used in the region where alkali resistance, strength and heat resistance are required, a polyolefin resin is used as a base material.
• Such a polyolefin-based resin base material is often used in the form of a woven fabric, a non-woven fabric, a porous sheet, or the like.
• the polyolefin-based resin base material is excellent in terms of alkali resistance, strength, and heat resistance, it can be used with an ion exchange resin obtained by polymerizing a polymerizable monomer and introducing an ion exchange group as necessary. It has the disadvantage of poor adhesion. Therefore, the expansion and deformation of the ion exchange resin cannot be suppressed, and for example, the base material and the ion exchange resin are easily peeled off due to repeated bending, and the function as an ion exchange membrane cannot be fulfilled.
• Patent Document 2 a technique has been found for improving the flexibility of an ion exchange membrane by polymerizing a polymerizable monomer at 110 ° C. or higher to improve adhesion.
• the polymerization is carried out at 110 ° C. or higher, the polyolefin resin base material itself is damaged and the strength of the polyolefin resin base material is lowered. Therefore, the base material is made thicker in order to maintain the strength. Then, there is a problem that the film resistance (electrical resistance) as the ion exchange membrane increases.
• the present invention has been made in view of the above points, and an object of the present invention is a cation exchange membrane using a polyolefin-based substrate, in which swelling of an ion exchange resin is suppressed and electrical resistance is small.
• the purpose is to provide a cation exchange membrane.
• the cation exchange membrane of the present invention is a cation exchange membrane provided with a base material made of a polyolefin-based woven fabric and a cation exchange resin having a sulfonic acid group, and polyvinyl chloride is formed on a portion other than the base material. It has a configuration containing 23% by mass or more and 35% by mass or less.
• the electrical resistance measured using 0.5 M saline solution at 25 ° C. is 1.5 ⁇ ⁇ cm 2 or more and 3.5 ⁇ ⁇ cm 2 or less, and the burst strength is 0.5 MPa or more and 1.2 MPa or less.
• the thickness of the base material may be 90 ⁇ m or more and 160 ⁇ m or less, and the opening ratio of the base material may be 35% or more and 50% or less.
• the base material may be made of a monofilament polyethylene-based woven fabric.
• the cation exchange resin may be a polystyrene-based cation exchange resin.
• the cation exchange resin may contain a component derived from ⁇ -alkylstyrene.
• the method for producing a cation exchange membrane of the present invention includes a monomer component containing a functional group into which a sulfonic acid group can be introduced or a monomer having a sulfonic acid group and a crosslinkable monomer, a polymerization initiator, and polychloride.
• the polymerizable composition for forming a cation exchange resin includes a copolymerization step of copolymerizing a monomer component, and the polyvinyl chloride is 55 parts by mass or more 98 parts by mass with respect to 100 parts by mass of the monomer component. It has a structure that it is contained in parts by mass or less.
• copolymerization step it is preferable to carry out copolymerization at 40 ° C. or higher and lower than 80 ° C.
• the base material may be made of a monofilament polyethylene-based woven fabric.
• the functional group into which a sulfonic acid group can be introduced or a monomer having a sulfonic acid group may be a styrene-based monomer having a functional group into which a sulfonic acid group can be introduced or a sulfonic acid group.
• the monomer component contains ⁇ -alkylstyrene, and the amount of ⁇ -alkylstyrene may be 1% by mass or more and 13% by mass or less with respect to the entire monomer component.
• the cation exchange membrane of the present invention uses a base material made of a polyolefin-based woven fabric, and since polyvinyl chloride is contained in a portion other than this base material in an amount of 23% by mass or more and 35% by mass or less, the ion exchange resin swells. And low electrical resistance can be achieved at the same time.
• a polyolefin resin or polyvinyl chloride is used as the base material of the cation exchange membrane.
• a polyolefin resin is used, and in such a case, polyvinyl chloride is not usually selected.
• the adhesion to the cation exchange resin is inferior, so that there is a problem that the cation exchange resin peels off from the base material when it absorbs water and swells.
• the inventors of the present application have conducted various studies to solve this problem, and have come up with the present invention of using a base material of a polyolefin-based woven fabric and polyvinyl chloride.
• the cation exchange film according to the first embodiment is a cation exchange film provided with a base material made of a polyolefin-based woven fabric and a cation exchange resin having a sulfonic acid group as a cation exchange group, and is formed on a portion other than the base material.
• Polyvinyl chloride is contained in an amount of 23% by mass or more and 35% by mass or less.
• polyolefin-based woven fabric examples include homopolymers of ⁇ -olefins such as ethylene, propylene, 1-butene and 4-methyl-1-pentene, and random or block copolymers thereof. Specific examples thereof include low-density polyethylene, high-density polyethylene, polypropylene, poly1-butene, and poly4-methyl-1-pentene. Among them, low-density polyethylene, high-density polyethylene, and polypropylene are preferable, and polyethylene-based polymers such as low-density polyethylene and high-density polyethylene are most preferable from the viewpoint of easy availability and resistance to chemicals.
• the polyolefin base material may have any form such as a woven fabric, a non-woven fabric, or a porous film, but a woven fabric is preferable from the viewpoint of strength.
• the opening ratio of the woven fabric is preferably 35% or more and 50% or less.
• the single yarn of the woven fabric can be used in either multifilament or monofilament, but the monofilament has a smaller contact area with the ion exchange resin, that is, a smaller gap between the ion exchange resin and the base material. Is preferable.
• the thickness of the polyolefin woven fabric is preferably 90 ⁇ m or more and 160 ⁇ m or less, and the wire diameter of the single yarn is 1 to 70 denier (10) from the viewpoint of balancing the strength and the film resistance. ⁇ 100 ⁇ m) is preferable.
• the cation exchange resin having a sulfonic acid group that forms a cation exchange membrane is known per se, for example, a resin that forms a skeleton into which a sulfonic acid group is introduced.
• the resin forming the skeleton include a polymer obtained by polymerizing a monomer having an ethylene-based unsaturated double bond such as vinyl-based, styrene-based, and acrylic-based, a copolymer polymer thereof, and polysulfone and polyphenylene.
• hydrocarbon-based resins such as polymers containing an aromatic ring in the main chain such as sulfide, polyether ketone, polyether ether ketone, polyetherimide, polyphenylene oxide, polyethersulfone, and polybenzimidazole.
• a styrene-based cation exchange resin mainly composed of a styrene-based monomer is preferable as the resin forming the skeleton.
• the cation exchange group is specified as a sulfonic acid group. Since the sulfonic acid group is a strongly acidic group, has a strong negative charge in an aqueous solution, and exhibits strong cation exchange property, the cation exchange film having this can be used particularly advantageously for various applications requiring cation exchange property. On the other hand, the affinity with the polyolefin resin base material becomes low, and the problem of poor adhesion becomes more remarkable. This inferior adhesiveness is satisfactorily improved by blending a specific amount of polyvinyl chloride with the cation exchange resin, and thus the effect of the present invention is particularly remarkably exhibited, which is preferable.
• polyvinyl chloride known ones can be used without any limitation.
• a homopolymer of a vinyl chloride monomer but also a copolymer obtained by copolymerizing another monomer can be used as long as the characteristics as polyvinyl chloride and the object of the present embodiment are not impaired.
• the copolymerizable monomer generally include ⁇ -olefins such as ethylene and propylene, and vinyl esters such as vinyl acetate.
• these polyvinyl chlorides may be used alone or in combination of two or more.
• the chlorine content of polyvinyl chloride is preferably in the range of 30 to 80% by mass, particularly 55 to 70% by mass. Those having a chlorine content within this range have a high affinity for styrene, and therefore have an advantageous effect in the bonding mechanism.
• the softening point is high, for example, the Crashberg flexible temperature (JIS K6734) is 60 ° C. or higher, more preferably 65 ° C. or higher. Those that meet the above range can maintain high adhesiveness even at high temperatures, so even during electrodialysis under high temperature conditions, stable electrodialysis can be performed without causing film peeling. Because it becomes.
• the Crashberg flexible temperature is generally 70 ° C. or lower.
• the average degree of polymerization of polyvinyl chloride is not particularly limited, but generally, it is preferably in the range of 500 to 3000, particularly 800 to 2000.
• the longer the molecular chain of polyvinyl chloride the greater the degree of entanglement with the molecule such as a cation exchange resin, and high adhesiveness can be obtained. However, if the molecular chain is too long, the solubility in a solvent decreases. If the average degree of polymerization is within the above range, high adhesiveness can be obtained and a leak-free cation exchange membrane can be obtained.
• Polyvinyl chloride may be used in a known form such as powder or pellet, but powder is preferable and has an average particle size of 0.1 ⁇ m to 30 ⁇ m as measured by a laser diffraction / scattering method.
• the powdery one is more preferable. This is because the powdered polyvinyl chloride has good compatibility with the resin forming the skeleton described later and is easily uniformly dispersed.
• Such a polyvinyl chloride powder can be obtained by a known suspension polymerization method.
• Polyvinyl chloride has extremely high affinity for monomers such as styrene and cross-linking agent components such as divinylbenzene, and therefore, as a cation exchange resin, cation exchange obtained by sulfonated a styrene-divinylbenzene copolymer is particularly high. It is preferable to use a resin.
• the polymerization is carried out in a state where polyvinyl chloride is compatible with a monomer having a sulfonic acid group, a monomer having a reactive group capable of introducing a sulfonic acid group, or a crosslinkable monomer, the molecule of the cation exchange resin This is because the polyvinyl chloride is present in the state of being entangled in the chain, the desorption of the polyvinyl chloride is effectively prevented, and the swelling of the ion exchange resin is effectively suppressed by the polyvinyl chloride.
• Polyvinyl chloride needs to be contained in the cation exchange membrane (relative to the dry mass) in a portion other than the base material in an amount of 23% by mass or more and 35% by mass or less.
• the amount is preferably 24% by mass or more and 32% by mass or less, and more preferably 25% by mass or more and 29% by mass or less. If the amount of polyvinyl chloride is too small, the cation exchange membrane swells and easily peels off, and if it is too large, the electrical resistance of the membrane may increase.
• the resistance of the cation exchange membrane from the viewpoint of efficient electrodialysis is a 1.5 [Omega ⁇ cm 2 or more 3.5 ⁇ ⁇ cm 2 or less, preferably 1.5 [Omega ⁇ cm 2 or more 3.2 ⁇ ⁇ cm 2 It is less than or equal to, more preferably 1.5 ⁇ ⁇ cm 2 or more and 3.0 ⁇ ⁇ cm 2 or less.
• Water permeability is a value measured by using a pressurized water 0.1MPa is not less 600ml / (m 2 ⁇ hr) or less, 500 ml / preferably (m 2 ⁇ hr) or less, 300ml / (m 2 ⁇ hr ) It is more preferable that it is as follows.
• the cation exchange membrane according to this embodiment is manufactured as follows.
• a polymerizable composition is prepared by mixing a polymerization curable component for forming a cation exchange resin such as a monomer having a sulfonic acid group, a crosslinkable monomer, and a polymerization initiator with polyvinyl chloride.
• the polymerizable composition is dipped in a polyolefin woven fabric as a base material to fill the voids of the woven fabric, and then the polymerizable composition is polymerized and cured to produce a cation exchange resin.
• the desired cation exchange membrane can be obtained.
• the polymerization curing temperature is preferably set to a temperature significantly lower than the melting point of the polyolefin-based woven fabric in order to suppress thermal deterioration of the polyolefin-based woven fabric.
• the upper limit of the polymerization curing temperature is preferably a temperature 40 ° C. lower than the melting point of the polyolefin constituting the base material.
• the polymerization curing temperature is preferably 40 ° C. or higher and lower than 80 ° C., more preferably 50 ° C. or higher and lower than 80 ° C.
• the polymerization is carried out at an excessively low temperature, the polymerization of the monomer does not proceed sufficiently and the unpolymerized portion increases, and voids are generated due to elution, which may lead to a decrease in current efficiency.
• the temperature is excessively high, the melting point of the polyolefin will be exceeded, and the strength of the polyolefin-based resin-based base material may decrease.
• the monomer having a sulfonic acid group in the polymerization curable component may be one conventionally used for producing a cation exchange resin.
• sulfonic acid-based monomers such as ⁇ -vinyl halide sulfonic acid, styrene sulfonic acid, vinyl sulfonic acid, salts and esters thereof and the like can be mentioned.
• the amount of the monomer having a sulfonic acid group is preferably 30% by mass or more and 98% by mass or less, and more preferably 40% by mass or more and 90% by mass or less with respect to the entire monomer component.
• ⁇ -alkylstyrene is contained as a part of the monomer, and the amount of ⁇ -alkylstyrene is 1% by mass or more and 13% by mass or less with respect to the entire monomer component. preferable.
• the crosslinkable monomer is used for densifying the cation exchange resin to enhance swelling inhibitory property, film strength and the like, and is not particularly limited, but for example, divinylbenzene and divinylsulfone. , Divinyl compounds such as butadiene, chloroprene, divinylbiphenyl, trivinylbenzenes, divinylnaphthalin, diallylamine, and divinylpyridine.
• such a crosslinkable monomer is preferably 0.1 to 50% by mass, more preferably 1 to 40% by mass, based on the entire monomer component.
• styrene styrene
• chloromethylstyrene acrylonitrile
• methylstyrene ethylvinylbenzene
• acrolein methyl vinyl ketone
• vinyl biphenyl vinyl biphenyl and the like are used.
• the amount of the other monomer to be blended varies depending on the purpose of addition, but in general, it is preferable to blend 0 to 50% by mass with respect to the entire monomer component, especially when flexibility is imparted. Is preferably blended in an amount of 5 to 40% by mass.
• the polymerization initiator conventionally known ones can be used without particular limitation, but those having a 10-hour half-life temperature of less than 80 ° C. are preferable. Specifically, organic peroxides such as diisobutyl peroxide, di (3,5,5-trimethylhexanoyl) peroxide, dilauroyl peroxide, disuccinic acid peroxide, and benzoyl peroxide are used.
• the polymerization initiator is preferably blended in an amount of 0.1 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, based on 100 parts by mass of the monomer component.
• a polymerizable composition is prepared by blending polyvinyl chloride with the above polymerization curable components so that the finally obtained cation exchange membrane has the above-mentioned composition. Specifically, it is preferable to mix 55 parts by mass or more and 98 parts by mass or less of polyvinyl chloride (preferably in powder form) with respect to 100 parts by mass of the monomer component. It is more preferably 57 parts by mass or more and 86 parts by mass or less, and particularly preferably 60 parts by mass or more and 75 parts by mass or less.
• the method of blending polyvinyl chloride is not particularly limited, and may be stirred so that the polymerizable composition is uniform with the polymerization curable component at room temperature, or the temperature is such that the polymerization of the polymerization curable component does not proceed. Specifically, it may be heated to a temperature of 40 ° C. or lower and stirred and mixed.
• the above-mentioned polymerizable composition may further contain a chlorinated polyolefin, a thickener, a known additive and the like, if necessary.
• the thickener examples include polyolefin powder having an average grain size of 10 ⁇ m or less, an ethylene-propylene copolymer, a saturated aliphatic hydrocarbon polymer such as polybutylene, and a styrene polymer such as a styrene-butadiene copolymer.
• the viscosity can be adjusted within a range that can effectively prevent sagging during the film forming operation.
• plasticizers such as dioctyl phthalate, dibutyl phthalate, tributyl phosphate, tributyl acetylcitrate, alcohol esters of fatty acids and aromatic acids, and hydrochloric acid trapping agents such as styrene side and ethylene glycol diglycidyl ether.
• the blending amount of the additive varies depending on the purpose of addition, but it is preferably 0.1 to 50 parts by mass, particularly 0.5 to 30 parts by mass with respect to 100 parts by mass of the monomer component.
• the method of impregnating the voids of the base material of the polyolefin-based woven fabric of the polymerizable composition is carried out by immersing a polyolefin base material in a tank filled with the above-mentioned polymerizable composition.
• impregnation of the polymerizable composition can be performed by a method such as spray coating or coating using a doctor blade.
• the polymerizable composition impregnated in the polyolefin-based woven fabric is heated in a polymerization apparatus such as a heating oven, copolymerized, and cured.
• this polymerization step a method of sandwiching a polyolefin-based woven fabric filled with a polymerizable composition between films such as polyester and raising the temperature from room temperature under pressure is generally adopted.
• the pressurization is generally performed at a pressure of about 0.1 to 1.0 MPa by pressurizing with an inert gas such as nitrogen or a roll.
• an inert gas such as nitrogen or a roll.
• polymerization conditions depend on the type of polymerization curable component and the like, and may be appropriately selected and determined from known conditions.
• the polymerization temperature is set to a temperature significantly lower than the melting point of the polyolefin-based woven fabric (specifically, 40 ° C. or higher and lower than 80 ° C.), and the polymerization time varies depending on the polymerization temperature and the like. Generally, it takes about 3 to 20 hours.
• a cation exchange membrane supported by the polyolefin-based woven fabric is obtained.
• a polymerization curable component for forming a cation exchange resin instead of the polymerization curable component for forming a cation exchange resin, a polymerization curable component for forming a cation exchange resin precursor resin having a reactive group capable of introducing a sulfonic acid group is used to form a cation exchange film. Can also be formed. Specifically, instead of the monomer having a sulfonic acid group, a monomer having a reactive group capable of introducing a sulfonic acid group is blended with the polymerizable composition to produce a cation exchange film precursor. In this case as well, the cation exchange film precursor may be prepared in the same manner as in the case of blending the monomer having a sulfonic acid group, except that the sulfonic acid group introduction step described later is added.
• the monomer having a reactive group into which a sulfonic acid group can be introduced may be one that has been conventionally used for producing a cation exchange resin.
• a cation exchange resin for example, styrene, methylstyrene, vinylxylene, ethylvinylbenzene, ⁇ -alkylstyrene (specifically, ⁇ -methylstyrene), vinylnaphthalene, ⁇ -halogenated styrenes and the like can be mentioned.
• ⁇ -alkylstyrene is contained as a part of the monomer, and the amount of ⁇ -alkylstyrene is 1% by mass or more and 13% by mass or less with respect to the entire monomer component. preferable.
• sulfonic acid group in addition to the monomer having a reactive group into which a sulfonic acid group can be introduced and the crosslinkable monomer, other monomers can be used if necessary.
• other monomers include chloromethylstyrene, acrylonitrile, acrolein, methyl vinyl ketone and the like.
• the sulfonic acid group introduction step is performed after the polymerizable composition is polymerized and cured to obtain a film of a cation exchange resin precursor resin.
• the obtained precursor resin in order to sulfonate, chlorsulfonate, etc., is treated with concentrated sulfuric acid or chlorosulfonic acid as a sulfonic acid group-introducing agent, or is subjected to a treatment such as hydrolysis to obtain a sulfonic acid. Introduce the group.
• the desired cation exchange membrane can be obtained.
• a polymerization curable component for forming a cation exchange resin precursor resin.
• the present embodiment has an important feature in that a cation exchange film is formed from a polymerizable composition obtained by adding polyvinyl chloride to a polymerization curable component, but the polymerization curing in which a sulfonic acid group is introduced. This is because polyvinyl chloride exhibits higher solubility in the polymerization-curable component in which the sulfonic acid group is not introduced than in the sex component.
• the thickness of the cation exchange membrane produced as described above is preferably in the range of 100 to 300 ⁇ m. If this thickness is too thin, the strength of the cation exchange membrane may be significantly reduced. If the thickness is excessively thick, there is a risk of causing inconvenience such as an increase in electrical resistance.
• the burst strength of the cation exchange film depends on the thickness, but the filament diameter and thickness of the polyolefin-based woven fabric and the crosslinkable monomer in the polymerization curable component so as to be 0.5 MPa or more and 1.2 MPa or less. The blending amount is adjusted.
• a polyolefin-based woven fabric is used as a base material, and polyvinyl chloride is contained in an amount of 23% by mass or more and 35% by mass or less of a portion other than the base material. Since a large amount of polyvinyl chloride is contained in this way, the monomer that is the raw material of the cation exchange resin enters the inside of the polyvinyl chloride powder or the like and is then copolymerized, so that the cation exchange membrane absorbs water. It is possible to suppress the degree of swelling and prevent the base material and the cation exchange resin from peeling off. Therefore, the strength of the entire cation exchange membrane can be increased without increasing the thickness of the base material. Further, since the cation exchange resin and the polyvinyl chloride are integrated as described above, the polyvinyl chloride does not block the opening portion of the base material, and it is possible to suppress an increase in the electrical resistance of the cation exchange membrane.
• the cation exchange membrane of the present invention having such properties can be used as a membrane for electrodialysis used in salt production and desalting processes in the food field, as an electrolyte membrane for fuel cells, and metal ions generated in the steel industry and the like. It can be usefully used in many fields such as membranes for diffusion dialysis used for acid recovery from acids containing.
• the same ion exchange membrane was immersed in a 0.5 mol / l-FeCl2 aqueous solution for 1 hour or more, and thoroughly washed with ion exchange water. Then, it was immersed in 10% by mass hydrogen peroxide solution for 6 hours or more, and the obtained solid content was recovered by a filter.
• the base material was recovered by washing the solid content with acetone, dried at 60 ° C. for 3 hours, and the weight (Bg) of the base material at the time of drying was measured.
• acetone was distilled off from the above-mentioned acetone washing solution using an evaporator, and the obtained solid content was analyzed by infrared spectroscopy to confirm that it was polyvinyl chloride. Then, the dry weight (Yg) of the obtained polyvinyl chloride was measured. Based on the above measured values, the polyvinyl chloride content in the resin of the ion exchange membrane was determined by the following formula.
• Polyvinyl chloride content 100 x Y / (DB) [%]
• the counterion of the ion exchange group is replaced with sodium ion from hydrogen ion with a 1 mol / l-NaCl aqueous solution, and the liberated hydrogen ion is replaced with a potential differential titrator (AT-710, Kyoto Electronics Industry Co., Ltd.) using a sodium hydroxide aqueous solution. Quantified (Amol).
• the same ion exchange membrane was immersed in a 1 mol / l-NaCl aqueous solution for 4 hours or more, and thoroughly washed with ion-exchanged water. Then, the water on the surface was wiped off with a tissue paper, and the mass (Wg) of the film when wet was measured. Further, it was dried under reduced pressure at 60 ° C. for 5 hours, and the weight (Dg) at the time of drying was measured. Based on the above measured values, the ion exchange capacity and water content of the ion exchange membrane were determined by the following equations.
• Ion exchange capacity A ⁇ 1000 / D [meq / g-dry mass]
• Moisture content 100 x (WD) / D [%]
• Thickness of ion exchange membrane After immersing the ion exchange membrane in a 0.5 mol / l-NaCl aqueous solution for 4 hours or more, wipe off the moisture on the surface of the membrane with tissue paper, and use a micrometer (MDE-25MX, manufactured by Mitutoyo). Measured using.
• the sodium hydroxide concentration of the recovered liquid and the initial liquid was quantified by a potentiometric titrator (AT-710, manufactured by Kyoto Denshi Kogyo Co., Ltd.) using an aqueous sulfuric acid solution, and the current efficiency was calculated using the following formula.
• CB-CS Current efficiency / (I ⁇ t / F) ⁇ 100 [%]
• CB is the concentration of the initial liquid
• CS is the concentration of the liquid recovered after energization
• I is the current value (A)
• t is the energization time (sec)
• F is the Faraday constant (96500 C / mol).
• Example 1 A monomer mixture of the following formulation was prepared.
• Styrene (St) 58.1% by mass Chloromethylstyrene (CMS) 17.6% by mass Divinylbenzene (DVB: purity 57%, the rest is ethylvinylbenzene) 8.2% by mass Acrylonitrile (AN) 13.1% by mass ⁇ -Methylstyrene ( ⁇ -MeSt) 3.0% by mass
• Ethylene glycol diglycidyl ether 0.8 parts by mass Tributyl acetylcitrate (ATBC) 17.4 parts by mass Lauroyl peroxide (Perloyl L made by Nippon Oil & Fats) 2.0 parts by mass is mixed, and further 65.3 parts by mass of vinyl chloride powder (ZEST P22 manufactured by Shin Daiichi PVC) was added, and the mixture was stirred for 2 hours to obtain a uniform polymerizable composition.
• High density polyethylene monofilament woven fabric (PE33D 120/120); Number of meshes: 120 Linear: 76 ⁇ m (33 denier) Thickness: 132 ⁇ m Opening rate: 41% Burst strength: 1.0 MPa
• the polymerizable composition obtained above was applied onto the high-density polyethylene monofilament woven fabric (PE33D 120/120), coated on both sides with a polyester film as a release agent, and then preheated at 45 ° C. for 1 hour. After that, polymerization was carried out at 70 ° C. for 3 hours.
• the obtained film-like polymer was sulfonated with chlorosulfonic acid at 40 ° C. for 45 minutes to obtain a cation exchange film.
• the characteristics of the obtained cation exchange membrane were as follows.
• High density polyethylene monofilament woven fabric PE33D 120/120; Number of meshes: 120 Linear: 76 ⁇ m (33 denier) Thickness: 132 ⁇ m Opening rate: 41% Burst strength: 1.0 MPa
• a cation exchange membrane was prepared in the same procedure as in Example 1 except that the polymerizable composition was changed to the above.
• the characteristics of the obtained cation exchange membrane were as follows.
• High density polyethylene monofilament woven fabric PE33D 120/120; Number of meshes: 120 Linear: 76 ⁇ m (33 denier) Thickness: 132 ⁇ m Opening rate: 41% Burst strength: 1.0 MPa
• a cation exchange membrane was prepared in the same procedure as in Example 1 except that the polymerizable composition was changed to the above.
• the characteristics of the obtained cation exchange membrane were as follows.
• High density polyethylene monofilament woven fabric PE33D 100/100; Number of meshes: 100 Linear: 76 ⁇ m (33 denier) Thickness: 132 ⁇ m Opening rate: 49% Burst strength: 0.9 MPa
• a cation exchange membrane was prepared in the same procedure as in Example 1 except that the polymerizable composition was changed to the above.
• the characteristics of the obtained cation exchange membrane were as follows.
• Example 5 A cation exchange membrane was prepared in the same procedure as in Example 4 except that the amount of vinyl chloride powder (ZEST P22 manufactured by New First PVC) added to the monomer mixture was changed to 58.0 parts by mass.
• the characteristics of the obtained cation exchange membrane were as follows.
• Example 6 A cation exchange membrane was prepared in the same procedure as in Example 2 except that the amount of vinyl chloride powder (ZEST P22 manufactured by New First PVC) added to the monomer mixture was changed to 80.0 parts by mass.
• the characteristics of the obtained cation exchange membrane were as follows.
• Example 7 A cation exchange membrane was prepared in the same procedure as in Example 2 except that the amount of vinyl chloride powder (ZEST P22 manufactured by New First PVC) added to the monomer mixture was changed to 90.0 parts by mass.
• the characteristics of the obtained cation exchange membrane were as follows.
• Styrene (St) 58.1% by mass Chloromethylstyrene (CMS) 17.6% by mass Divinylbenzene (DVB: purity 57%, the rest is ethylvinylbenzene) 8.2% by mass Acrylonitrile (AN) 13.1% by mass ⁇ -Methylstyrene ( ⁇ -MeSt) 3.0% by mass
• Ethylene glycol diglycidyl ether 0.8 parts by mass Tributyl acetylcitrate (ATBC) 17.4 parts by mass Lauroyl peroxide (Perloyl L made by Nippon Oil & Fats) 2.0 parts by mass is mixed, and further 65.3 parts by mass of vinyl chloride powder (ZEST P22 manufactured by Shin Daiichi PVC) was added, and the mixture was stirred for 2 hours to obtain a uniform polymerizable composition.
• High density polyethylene monofilament woven fabric (PE33D 130/130); Number of meshes: 130 Linear: 76 ⁇ m (33 denier) Thickness: 132 ⁇ m Opening rate: 37% Burst strength: 1.1 MPa
• the polymerizable composition obtained above was applied onto the high-density polyethylene monofilament woven fabric (PE33D 130/130), coated on both sides with a polyester film as a release agent, and then preheated at 45 ° C. for 1 hour. After that, polymerization was carried out at 70 ° C. for 3 hours.
• the obtained film-like polymer was sulfonated with chlorosulfonic acid at 40 ° C. for 45 minutes to obtain a cation exchange film.
• the characteristics of the obtained cation exchange membrane were as follows.
• ⁇ Comparative example 1> A cation exchange membrane was prepared in the same procedure as in Example 4 except that the amount of vinyl chloride powder (ZEST P22 manufactured by New First PVC) added to the monomer mixture was changed to 45.0 parts by mass. The characteristics of the obtained cation exchange membrane were as follows.
• ⁇ Comparative example 2> A cation exchange membrane was prepared in the same procedure as in Example 2 except that the amount of vinyl chloride powder (ZEST P22 manufactured by New First PVC) added to the monomer mixture was changed to 100.0 parts by mass.
• the characteristics of the obtained cation exchange membrane were as follows.

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