WO1998051733A1 - Procede de preparation de membranes composites echangeuses d'ions - Google Patents

Procede de preparation de membranes composites echangeuses d'ions Download PDF

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Publication number
WO1998051733A1
WO1998051733A1 PCT/US1997/007955 US9707955W WO9851733A1 WO 1998051733 A1 WO1998051733 A1 WO 1998051733A1 US 9707955 W US9707955 W US 9707955W WO 9851733 A1 WO9851733 A1 WO 9851733A1
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Prior art keywords
polymer
highly fluorinated
precursor
microporous support
sulfonyl halide
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PCT/US1997/007955
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English (en)
Inventor
Shoibal Banerjee
John Donald Summers
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E.I. Du Pont De Nemours And Company
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Priority to PCT/US1997/007955 priority Critical patent/WO1998051733A1/fr
Publication of WO1998051733A1 publication Critical patent/WO1998051733A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H01M4/92—Metals of platinum group
    • H01M4/925—Metals of platinum group supported on carriers, e.g. powder carriers
    • H01M4/926—Metals of platinum group supported on carriers, e.g. powder carriers on carbon or graphite
    • 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
    • C08J5/2275—Heterogeneous membranes
    • C08J5/2281—Heterogeneous membranes fluorine containing heterogeneous membranes
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B13/00—Diaphragms; Spacing elements
    • C25B13/04—Diaphragms; Spacing elements characterised by the material
    • C25B13/08—Diaphragms; Spacing elements characterised by the material based on organic materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/102—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer
    • H01M8/1023—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer having only carbon, e.g. polyarylenes, polystyrenes or polybutadiene-styrenes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/102—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer
    • H01M8/1025—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer having only carbon and oxygen, e.g. polyethers, sulfonated polyetheretherketones [S-PEEK], sulfonated polysaccharides, sulfonated celluloses or sulfonated polyesters
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1039—Polymeric electrolyte materials halogenated, e.g. sulfonated polyvinylidene fluorides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1041—Polymer electrolyte composites, mixtures or blends
    • H01M8/1044—Mixtures of polymers, of which at least one is ionically conductive
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1041—Polymer electrolyte composites, mixtures or blends
    • H01M8/1053—Polymer electrolyte composites, mixtures or blends consisting of layers of polymers with at least one layer being ionically conductive
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1058—Polymeric electrolyte materials characterised by a porous support having no ion-conducting properties
    • H01M8/106—Polymeric electrolyte materials characterised by a porous support having no ion-conducting properties characterised by the chemical composition of the porous support
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1067—Polymeric electrolyte materials characterised by their physical properties, e.g. porosity, ionic conductivity or thickness
    • 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
    • C08J2327/00—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
    • C08J2327/02—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
    • C08J2327/12—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 fluorine atoms
    • C08J2327/18—Homopolymers or copolymers of tetrafluoroethylene
    • 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
    • C08J2381/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing sulfur with or without nitrogen, oxygen, or carbon only; Polysulfones; Derivatives of such polymers
    • C08J2381/08—Polysulfonates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1004—Fuel cells with solid electrolytes characterised by membrane-electrode assemblies [MEA]
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a process for making composite ion exchange membranes of highly fluorinated ion exchange polymer combined with a microporous support of highly fluorinated nonionic polymer.
  • Ion exchange polymer membranes have found utility in a number of electrochemical and other processes.
  • One use has been as membranes for solid polymer electrolyte cells.
  • Solid polymer electrolyte cells typically employ a membrane of an ion exchange polymer which serves as a physical separator between the anode and cathode while also serving as an electrolyte. These cells can be operated as electrolytic cells for the production of electrochemical products or they may be operated as fuel cells for the production of electrical energy.
  • Ion exchange polymer membranes are also used for facilitated transport, diffusion dialysis, electrodialysis, pervaporation and vapor permeation separations.
  • Membranes of highly fluorinated polymers such as perfluorinated sulfonic acid polymer membranes are particularly well-suited for such uses due to excellent chemical resistance, long life, and high conductivity.
  • the tensile strength of such membranes is not as high desired and reinforcements are sometimes incorporated into the membranes to increase strength.
  • woven reinforcements are incorporated into the membranes. While woven reinforcements work well in use, the fabrics are expensive and processes for incorporation of the fabrics into the membranes are cumbersome.
  • Woven fabrics are generally unsuitable for membranes for fuel cells since membranes incorporating fabrics typically do not have the flat surfaces needed for contact with the electrodes employed in use in a fuel cell.
  • Composite ion exchange membranes have been developed which incorporate porous supports of a highly fluorinated nonionic polymer such as expanded polytetrafluoroethylene (EPTFE) to increase tensile strength and improve dimensional stability.
  • EPTFE expanded polytetrafluoroethylene
  • the processes known for making such membranes are not particularly suitable for commercial manufacturing operations.
  • U.S. Patent 5,082,472 dislocloses a process for making composite membrane intended for facilitated transport end use. In the process of this patent, the following steps are disclosed:
  • the invention provides a method for making a composite ion exchange membrane including fabricating a layered membrane precursor including a microporous support of highly fluorinated nonionic polymer adhered to a layer of highly fluorinated sulfonyl halide polymer, hydrolyzing the layered membrane precursor to convert the highly fluorinated sulfonyl halide polymer to highly fluorinated sulfonate polymer, impregnating the microporous support with a dispersion of highly fluorinated sulfonate polymer or precursor thereof in a polar liquid medium after hydrolyzing, removing the polar liquid medium, and heating to coalesce the highly fluorinated sulfonated polymer in the support.
  • fabricating of the layered membrane precursor is performed under conditions which cause sufficient flow of the highly fluorinated sulfonyl halide polymer to form a consolidated layered membrane precursor that does not delaminate during hydrolyzing.
  • the layered membrane precursor is fabricated by laminating a film of highly fluorinated sulfonyl halide polymer to the microporous support at a temperature of at least about 280°C, most preferably at a temperature of at least about 300°C.
  • the side of the membrane with the highly fluorinated sulfonate polymer layer is contacted with a dry gas to cause at least partial removal of the polar liquid by passage through the layer of highly fluorinated sulfonate polymer.
  • Especially preferred liquid media include alcohols having 1 to 4 carbon atoms and mixtures thereof.
  • the impregnating is performed such that the microporous support is fully embedded in the highly fluorinated sulfonate polymer.
  • the layered membrane precursor further comprises a layer of highly fluorinated carboxylate polymer precursor adhered to the side of the highly fluorinated sulfonyl halide polymer layer opposite from the microporous support, the carboxylate polymer precursor being converted to carboxylate polymer during hydrolysis.
  • the highly fluorinated carboxylate polymer precursor is highly fluorinated methyl carboxylate polymer.
  • the layered membrane precursor is fabricated by laminating a bifilm of highly fluorinated carboxylate polymer precursor and highly fluorinated sulfonyl halide polymer to the support with the sulfonyl halide polymer contacting the microporous support.
  • the composite ion exchange membranes made by the process have a thickness of 20 ⁇ m to about 400 ⁇ m, most preferably, 30 ⁇ m to about 60 ⁇ m.
  • the microporous support further comprises an attached fabric, most preferably a woven fabric.
  • the sulfonyl halide polymer used in the process is perfluorinated. It is also preferable for the nonionic polymer of the microporous support to be perfluorinated.
  • the microporous support comprises expanded polytetrafluoroethylene having a microstructure of polymeric fibrils, most preferably, a microstructure of nodes interconnected by the fibrils.
  • the method in accordance with the present invention employs highly fluorinated sulfonate polymer, i.e., having sulfonate functional groups in the resulting composite membrane.
  • Highly fluorinated means that at least 90% of the total number of univalent atoms in the polymer are fluorine atoms. Most preferably, the polymer is perfluorinated.
  • sulfonate functional groups is intended to refer to either to sulfonic acid groups or salts of sulfonic acid groups, preferably alkali metal or ammonium salts.
  • the functional groups are represented by the formula -S0 3 X wherein X is H, Li, Na, K or N(R i )(R 2 )(R 3 )(R 4 ) and R 1 , R 2 , R 3 , and R 4 are the same or different and are H, CH 3 or C H 5 .
  • the sulfonic acid form of the polymer is preferred, i.e., where X is H in the formula above.
  • the sodium salt form of the polymer is preferred, i.e., where X is Na in the formula above.
  • the polymer comprises a polymer backbone with recurring side chains attached to the backbone with the side chains carrying the cation exchange groups.
  • Possible polymers include homopolymers or copolymers of two or more monomers. Copolymers are typically formed from one monomer which is a nonfunctional monomer and which provides carbon atoms for the polymer backbone. A second monomer provides both carbon atoms for the polymer backbone and also contributes the side chain carrying the cation exchange group or its precursor, e.g., a sulfonyl halide group such a sulfonyl fluoride (-S0 2 F), which can be subsequently hydrolyzed to a sulfonate functional group.
  • a sulfonyl halide group such as a sulfonyl fluoride (-S0 2 F)
  • copolymers of a first fluorinated vinyl monomer together with a second fluorinated vinyl monomer having a sulfonyl fluoride group can be used.
  • Possible first monomers include tetrafluoroethylene (TFE), hexafluoropropylene, vinyl fluoride, vinylidine fluoride, trifluorethylene, chlorotrifluoroethylene, perfluoro (alkyl vinyl ether), and mixtures thereof.
  • Possible second monomers include a variety of fluorinated vinyl ethers with sulfonate functional groups or precursor groups which can provide the desired side chain in the polymer.
  • the first monomer may also have a side chain which does not interfere with the ion exchange function of the sulfonate functional group. Additional monomers can also be incorporated into these polymers if desired.
  • the preferred polymers include, for example, polymers disclosed in U.S. Patent 3,282,875 and in U.S. Patents 4,358,545 and 4,940,525.
  • One preferred polymer comprises a perfluorocarbon backbone and the side chain is represented by the formula -0-CF 2 CF(CF 3 )-0-CF 2 CF 2 S0 3 X, wherein X is as defined above. Polymers of this type are disclosed in U.S.
  • TFE tetrafluoroethylene
  • PMMAF perfluoro(3,6-dioxa-4-methyl-7-octenesulfonyl fluoride)
  • Patents 4,358,545 and 4,940,525 has the side chain -0-CF 2 CF 2 S0 3 X, wherein X is as defined above.
  • highly fluorinated carboxylate polymer i.e., having carboxylate functional groups in the resulting composite membrane, is also employed as will be discussed in more detail hereinafter.
  • carboxylate functional groups is intended to refer to either to carboxylic acid groups or salts of carboxylic acid groups, preferably alkali metal or ammonium salts.
  • the functional groups are represented by the formula -CO2X wherein X is H, Li, Na, K or N(R')(R 2 )(R 3 )(R 4 ) and R i , R 2 , R 3 , and R 4 are the same or different and are H, CH 3 or C 2 H 5 .
  • the sodium salt form of the polymer preferred, i.e., where X is Na in the formula above.
  • the polymer comprises a polymer backbone with recurring side chains attached to the backbone with the side chains carrying the carboxylate functional groups.
  • Polymers of this type are disclosed in U.S. Patent 4,552,631 and most preferably have the side chain -0-CF 2 CF(CF 3 )-0-CF 2 CF 2 C0 2 X.
  • IXR ion exchange ratio
  • cation exchange capacity of a polymer is often expressed in terms of equivalent weight (EW).
  • equivalent weight (EW) is defined to be the weight of the polymer in acid form required to neutralize one equivalent of NaOH.
  • the equivalent weight range which corresponds to an IXR of about 7 to about 33 is about 700 EW to about 2000 EW.
  • IXR range is about 12 to about 21 which corresponds to about 900 EW to about 1350 EW.
  • IXR is used in this application to describe either hydrolyzed polymer which contains functional groups or unhydrolyzed polymer which contains precursor groups which will subsequently be converted to the functional groups during the manufacture of the membranes.
  • the highly fluorinated sulfonate polymer used in the process of the invention preferably has ion exchange ratio of about 8 to about 23, more preferably about 9 to about 14 and most preferably about 10 to about 13.
  • microporous supports useful in a process of the invention are made of highly fluorinated nonionic polymers.
  • "highly fluorinated” means that at least 90% of the total number of halogen and hydrogen atoms in the polymer are fluorine atoms.
  • the microporous support is preferably is made of a perfluorinated polymer.
  • the polymer for the porous support can be polytetrafluoroethylene (PTFE) or a copolymer of tetrafluoroethylene with
  • C F 2 C F0 — ( C F 2 C ⁇ FO ) ' m m Cn 2 n i i + ,l C F 3
  • Microporous PTFE sheeting is well known and is particularly suitable for use as the microporous support.
  • One preferred support is expanded polytetrafluoroethylene polymer (EPTFE) having a microstructure of polymeric fibrils, most preferably, a microstructure of nodes interconnected by the fibrils. Films having a microstructure of polymeric fibrils with no nodes present are also useful.
  • EPTFE expanded polytetrafluoroethylene polymer
  • Films having a microstructure of polymeric fibrils with no nodes present are also useful.
  • the preparation of such suitable supports is described in U.S. patents 3,593,566 and U.S. 3,962,153. These patents disclose the extruding of dispersion-polymerized PTFE in the presence of a lubricant into a tape and subsequently stretching under conditions which make the resulting material more porous and stronger.
  • Suitable microporous PTFE supports are available commercially from W. L. Gore & Associates, Elkton Maryland, under the trademark GORE-TEX® and from Tetratec, Feasterville, Pennsylvania, under the trademark TETRATEX®.
  • Microporous supports made using other manufacturing processes with other highly fluorinated nonionic polymers may also be used in the process of the invention.
  • Such polymers may be selected from the broad spectrum of homopolymers and copolymers made using flurorinated monomers.
  • Possible fluorinated monomers include vinyl fluoride; vinylidene fluoride; trifluoroethylene; chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (TFE); hexafluoropropylene (HFP); perfluoro(alkyl vinyl) ethers such as perfluoro(methyl vinyl) ether (PMVE), perfluoro(ethyl vinyl) ether (PEVE), and perfluoro(propyl vinyl) ether (PPVE); perfluoro(l,3-dioxole); perfluoro(2,2-dimethyl-l,3-dioxole) (PDD); F(CF 2 ) n CH
  • the microporous support may also include an attached fabric, preferably a woven fabric.
  • fabrics are made of a yarn of a highly fluorinated polymer, preferably PTFE. If such fabrics are to be used, they are preferably securely attached to the PTFE support as supplied for use in the process.
  • Suitable woven fabrics include scrims of woven fibers of expanded PTFE, webs of extruded or oriented fluoropolymer or fluoropolymer netting, and woven materials of fluoropolymer fiber. Nonwoven materials include spun-bonded fluoropolymer may also be used if desired.
  • the process for manufacturing the composite membranes described in accordance with the invention involves a series of steps.
  • the process includes fabricating a layered membrane precursor including a porous support of expanded highly fluorinated nonionic polymer adhered to a layer of highly fluorinated sulfonyl halide polymer. This can be accomplished by a variety of methods including lamination, melt deposition " and other methods.
  • a film of sulfonyl halide polymer such as sulfonyl fluoride polymer for lamination to the support is suitably made by extrusion at a temperature in the range of about 200°C to about 300°C. Preferable film thicknesses are about 10 ⁇ m to about 250 ⁇ m.
  • a bifilm of a layer of highly fluorinated sulfonyl halide polymer and a layer highly fluorinated carboxylate polymer precursor can be coextruded for subsequent lamination.
  • a preferred total thickness for the composite ion exchange membrane is about 20 ⁇ m to about 400 ⁇ m, most preferably, about 30 ⁇ m to about 60 ⁇ m.
  • the layered membrane precursor is fabricated under conditions so that sufficient flow of the highly fluorinated sulfonyl halide polymer occurs to form a consolidated layered membrane precursor which does not delaminate during subsequent hydrolysis. Preferably, this is accomplished by laminating the film of highly fluorinated sulfonyl halide polymer to the microporous support at a temperature of at least about 280°C, most preferably at a temperature of at least about 300°C. These temperatures provide thermoplastic flow of the polymer sufficient to form the preferred consolidated layered membrane precursor.
  • the lamination process is preferably performed under pressure.
  • Pressures in the range of about 0.5 to about 1 atmosphere have been found to be suitable. Such pressures are advantageously applied by subjecting the microporous support to a vacuum while keeping the sulfonyl halide polymer film side at atmospheric pressure. Depending on the temperature, contact times can be as little as 5 seconds but generally are less than 90 seconds to avoid overheating and degradation of the polymer.
  • the layered membrane precursor is suitably hydrolyzed using methods known in the art.
  • the membrane may be hydrolyzed to convert it to the sodium sulfonate form by immersing it in 25% by weight NaOH for about 16 hours at a temperature of about 90°C followed by rinsing the film twice in deionized 90°C water using about 30 to about 60 minutes per rinse.
  • Another possible method employs an aqueous solution of 6-20% of an alkali metal hydroxide and 5-40% polar organic solvent such as dimethyl sulfoxide with a contact time of at least 5 minutes at 50°-100°C followed by rinsing for 10 minutes.
  • the carboxylate polymer precursor such as methyl carboxylate polymer, if present, is converted to carboxylate polymer at the same time.
  • the membrane precursor can be converted if desired to another ionic form by contacting the membrane in a bath containing a 1-5% aqueous salt solution containing the desired cation or, to the acid form, by contacting with a 2-20%) aqueous acid solution and rinsing.
  • the membrane is usually in the sulfonic acid form.
  • the membrane precursor is typically used in the sodium form.
  • Impregnation of the microporous support of the hydrolyzed precursor laminate is performed with liquid composition of highly fluorinated sulfonic acid polymer or precursor thereof in a polar liquid medium.
  • polar liquid medium liquids which can be transported by a highly fluorinated sulfonate membrane.
  • Suitable compositions of sulfonic acid polymer in polar media are disclosed in U.S. Patents 4,433,082 and 4,453,991 in which polymer particles are dispersed in mixtures of water and alcohols.
  • the polar medium contains a high content of an alcohol which facilitates wetting of the microporous support and which is volatile to facilitate the removal of the liquid medium from the membrane.
  • the liquid compositions contain at least about 90% of an alcohol selected from the group consisting of alcohols with 1 to 4 carbon atoms.
  • a suitable concentration of polymer in the liquid medium is about 2 to about 10% by weight.
  • Compositions with high alcohol contents can be made by concentrating the compositions as disclosed in U.S. Patents 4,433,082 and 4,453,991 by evaporation and subsequent dilution with the desired alcohol. Impregnation is performed so that the pores of the microporous support are at least partially filled, but preferably are completely filled with polymer.
  • impregnation is performed so that the microporous support is embedded in the highly fluorinated sulfonate polymer, i.e., an unreinforced layer of the sulfonate polymer is present on the surface of the microporous support.
  • Impregnation can be carried out using a variety of methods such as dipping, soaking, brushing, painting and spraying as well as using conventional coating methods such as forward roll coating, reverse roll coating, gravure coating, doctor coating, kiss coating etc.
  • conventional coating methods such as forward roll coating, reverse roll coating, gravure coating, doctor coating, kiss coating etc.
  • Removal of the liquid medium can be accomplished by heating and the liquid medium can be recycled if desired.
  • the side of the membrane with the highly fluorinated sulfonate polymer layer is contacted with a dry gas to cause at least partial removal of the polar liquid by passage through the layer of highly fluorinated sulfonate polymer.
  • a dry gas as used herein is meant a gas which has a sufficiently low content of vapor of the polar liquid medium to cause removal of the medium from the membrane.
  • the sulfonate polymer layer on the membrane thus serves to draw liquid composition into the microporous support and assists with the impregnation process.
  • the ability to remove the liquid medium by transport through the membrane enables the process to be performed very quickly which is very helpful for continuous processes.
  • the polymer impregnating the porous support can be coalesced by heating to a temperature which renders the polymer insoluble. While the coalescence temperature varies with the IXR of the polymer and polymer type, typically the membrane should be heated to above about 120°C. A preferred temperature range is about 120 to about 150°C for compolymers of TFE and PDMOF in the normal IXR ranges employed. For other polymers and for higher IXR values, higher temperatures may be desirable.
  • the time needed coalesce varies with the temperature employed a suitable range has been found to be about one minute to about one hour. Coalescence is conveniently carried out together with or immediately following the removal of the liquid medium if desired.
  • steps needed to fabricate the layered membrane precursor are combined in to one stage using roll stock of the microporous support and laminating to sulfonyl halide or bifilm film roll stock or by extrusion deposition of the sulfonyl halide polymer, optionally coextruded with the carboxylate polymer precursor.
  • the layer membrane precursor can be wound up using a roll wind-up if desired.
  • Hydrolysis and acid exchange if used
  • Impregnation can be performed after hydrolysis in a continuous fashion if desired. Generally, however, it is more advantageous to perform the steps of impregnation, removal of the liquid medium and coalescence of the polymer together as a stage of the process.
  • a microporous PTFE film prepared as disclosed in U.S. Patents 3,962,153 (Gore) and 3,953,566 (Gore) is used as a microporous support in in the composite membrane.
  • the PTFE film has a nominal thickness of 0.0009 to 0.001 inch (23 ⁇ m to 25 ⁇ m) and an apparent density of about 0.38 g/cc.
  • a 0.001 inch (25 ⁇ m) thick sulfonyl fluoride polymer film 1080 equivalent weight (15 IXR) is prepared by melt extrusion.
  • the polymer is a copolymer of TFE and PDMOF.
  • the polymer is melt extruded onto a rotating drum, the cast film then being conveyed and co-wound on a steel core with polyethylene as a spacer to prevent self-adhesion of the cast film. Extrusion temperatures are approximately 275°C.
  • the sulfonyl fluoride film is then laminated to the microporous
  • PTFE film by vacuum lamination at 310°C.
  • the resulting laminate is then exposed to a 22 weight % potassium hydroxide, 7.5 weight % dimethylsulfoxide solution in water at 70°C for 40 minutes to hydrolyze the laminate to the potassium salt form.
  • the laminate is then rinsed in deionized water and converted to the acid (H + ) form by immersion in 10% nitric acid under ambient conditions for 30 minutes. After a final rinse in deionized water, the laminate is dried and conveyed to a wind-up roll for convenient handling and storage.
  • the membrane After the final spray coat the membrane, still suspended in the stainless steel frame, is heated under vacuum at 150°C for 2 hours to remove residual solvent and to coalesce the polymer.
  • the composite membrane is then conditioned by immersion in a 10% nitric acid bath at 100°C for two hours.
  • the composite membrane emerges from this treatment as a clear and colorless product suitable for membrane electrode assembly (MEA) preparation.
  • the dried thickness is nominally 1.7 mils (43 ⁇ m).
  • a catalyst ink containing a catalyst of platinum supported on carbon particles and perfluorinated sulfonyl fluoride polymer (copolymer of TFE and PDMOF - 940 EW, 12 IXR) as binder is prepared in a solvent which is a mixture of perfluoro(methyl-di-n-butyl)amine and perfluoro(tri- n-butylamine) sold under the trademark FLUOROINERT FC-40, by 3M of St. Paul, Minnesota. Decals are made by coating the ink onto a substrate and drying.
  • the decals are hot pressed on to either side of the composite membrane described above to transfer the catalyst mixture onto the membrane and thus form catalyst coated membrane (CCM) with a 50 cm 2 active area and a platinum loading of 0.3 mg platinum/cm 2 .
  • CCM catalyst coated membrane
  • the CCM is sandwiched between two treated carbon papers with act as gas diffusion backing to form a membrane electrode assembly (MEA).
  • MEA membrane electrode assembly
  • the MEA is then assembled in a fuel cell fixture and is evaluated for performance in a test station obtained from Los Alamos National Laboratories, Los Alamos, New Mexico. The measurements are carried out under different experimental conditions of temperature, pressure, reactant and cathode gas compositions.
  • the MEA is evaluated for both instantaneous and steady state performance.
  • Example 2 Composite Membrane for Chloralkali Electrolysis
  • An unsintered expanded microporous PTFE support prepared as disclosed in U.S. Patents 3,962,153 (Gore) and 3,953,566 (Gore) omitting the sintering step, is used as a microporous support in a composite membrane.
  • the EPTFE has a nominal thickness of 4 mil (100 ⁇ m) and an apparent density of about 0.38 g/cc with a pore size of 0.2 ⁇ m.
  • a bifilm of 1 mil (25 ⁇ m) 1050 EW highly fluorinated carboxylate film adhered to 4 mil (0.004 inch, 100 ⁇ m) 1080 EW sulfonyl fluoride film is prepared by coextrusion of the component polymers to make a two layer film.
  • the bifilm is then laminated to the microporous PTFE support by vacuum lamination at 280°C. with the sulfonyl fluoride side of the bifilm contacting the support.
  • the bifilm laminate is then cut from the roll stock.
  • the bifilm laminate is then exposed to a solution of 10 weight % potasium hydroxide, 30 weight % dimethyl sulfoxide and 60 weight % water on a steam bath for 30 minutes to hydrolyze the laminate to the potassium salt form, and washed thoroughly in deionized water.
  • the PTFE support side of the laminate is then sprayed several times with a liquid composition of 5 weight % perfluorosulfonic acid polymer (copolymer of TFE and PDMOF) having an equivalent weight of 922 (12 IXR) in a 5 weight % water/95 weight % ethyl alcohol mixture until the membrane becomes translucent and allowing the laminate to air dry between treatments.
  • the coating cycle is repeated until the membrane retains its clear appearance in the dry state, visually indicating complete deposition of ionomer in the voids of the EPTFE layer. A total of 4 coating cycles are required to accomplish this.
  • the bifilm laminate is dried for a period of several days at a temperature of 110°C to remove residual solvent and to fully consolidate the laminate and form a composite membrane suitable for testing electrical performance.
  • the membrane was then coated with gas release coating according to the teachings of U.S. 4,552,631 (Bissot et al.) on both sides and put into chloralkali cells for testing. After 94 days continuous cell testing duplicate membranes show 3.04V, 95.3% current efficiency and 3.07V, 96.4%) current efficiency. This performance is equivalent to that of good commercial membranes.

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Abstract

L'invention concerne un procédé de préparation d'une membrane composite échangeuse d'ions consistant à fabriquer un précurseur de membrane en couches comprenant un support microporeux en polymère non ionique hautement fluoré collé à une couche de polymère d'halogénure de sulfonyle hautement fluoré, à hydrolyser le précurseur de membrane en couches afin de transformer le polymère d'halogénure de sulfonyle hautement fluoré en polymère de sulfonate hautement fluoré, à imprégner le support microporeux d'une dispersion d'un polymère de sulfonate hautement fluoré ou d'un précurseur de celui-ci dans un milieu liquide polaire après hydrolyse, à enlever le milieu liquide polaire et à chauffer pour coalescer le polymère sulfoné hautement fluoré dans le support.
PCT/US1997/007955 1997-05-09 1997-05-09 Procede de preparation de membranes composites echangeuses d'ions WO1998051733A1 (fr)

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Cited By (10)

* Cited by examiner, † Cited by third party
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WO2000079629A1 (fr) * 1999-06-18 2000-12-28 3M Innovative Properties Company Membranes d'elecrolytes polymeres ameliorees a partir de dispersions melangees
WO2001070858A2 (fr) * 2000-03-22 2001-09-27 Victrex Manufacturing Limited Materiau d'echange d'ions composite
WO2001080336A2 (fr) * 2000-04-18 2001-10-25 3M Innovative Properties Company Ensemble electrode a membrane possedant une membrane d'electrolyte polymerique recuite
US6689501B2 (en) 2001-05-25 2004-02-10 Ballard Power Systems Inc. Composite ion exchange membrane for use in a fuel cell
EP1610347A1 (fr) * 2003-03-28 2005-12-28 Sumitomo Chemical Company, Limited Appareil et procede continu de production d'une membrane d'electrolyte polymere
WO2009086364A1 (fr) * 2007-12-27 2009-07-09 3M Innovative Properties Company Encres d'électrodes contenant des solvants coalescents
WO2011093495A1 (fr) * 2010-02-01 2011-08-04 旭化成イーマテリアルズ株式会社 Produit de revêtement et corps stratifié
CN102237534A (zh) * 2010-04-28 2011-11-09 中国科学院金属研究所 一种钒电池用全氟磺酸离子交换膜制备工艺
CN104262665A (zh) * 2014-09-29 2015-01-07 上海金由氟材料股份有限公司 一种可连续化生产全氟磺酸质子交换膜的制备方法
CN114288855A (zh) * 2021-11-25 2022-04-08 国家电投集团氢能科技发展有限公司 一种水电解膜及其制备方法

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EP0385427A2 (fr) * 1989-02-28 1990-09-05 E.I. Du Pont De Nemours And Company Membrane d'échangeur de cation renforcé avec un tissu d'échangeur de cation
US5066682A (en) * 1989-06-05 1991-11-19 Asahi Kasei Kogyo Kabushiki Kaisha Process for preparing an ion exchange membrane
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US4913817A (en) * 1987-06-19 1990-04-03 Asahi Kasei Kogyo Kabushiki Kaisha Reinforced ion exchange membrane and a process for producing the same
WO1990006337A1 (fr) * 1988-11-30 1990-06-14 W.L. Gore & Associates, Inc. Membrane composite renforcee de tissu
EP0385427A2 (fr) * 1989-02-28 1990-09-05 E.I. Du Pont De Nemours And Company Membrane d'échangeur de cation renforcé avec un tissu d'échangeur de cation
US5066682A (en) * 1989-06-05 1991-11-19 Asahi Kasei Kogyo Kabushiki Kaisha Process for preparing an ion exchange membrane
US5082472A (en) * 1990-11-05 1992-01-21 Mallouk Robert S Composite membrane for facilitated transport processes

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6277512B1 (en) 1999-06-18 2001-08-21 3M Innovative Properties Company Polymer electrolyte membranes from mixed dispersions
WO2000079629A1 (fr) * 1999-06-18 2000-12-28 3M Innovative Properties Company Membranes d'elecrolytes polymeres ameliorees a partir de dispersions melangees
KR100776933B1 (ko) * 1999-06-18 2007-11-20 쓰리엠 이노베이티브 프로퍼티즈 캄파니 혼합 분산액으로부터의 개량된 중합체 전해질 막 및 그 제조 방법
US6902801B2 (en) 2000-03-22 2005-06-07 Victrex Manufacturing Limited Composite ion exchange material
WO2001070858A2 (fr) * 2000-03-22 2001-09-27 Victrex Manufacturing Limited Materiau d'echange d'ions composite
WO2001070858A3 (fr) * 2000-03-22 2001-12-27 Victrex Mfg Ltd Materiau d'echange d'ions composite
JP2013030490A (ja) * 2000-04-18 2013-02-07 Three M Innovative Properties Co アニールされたポリマー電解質膜を有する膜電極アセンブリ
WO2001080336A2 (fr) * 2000-04-18 2001-10-25 3M Innovative Properties Company Ensemble electrode a membrane possedant une membrane d'electrolyte polymerique recuite
US6649295B2 (en) 2000-04-18 2003-11-18 3M Innovative Properties Company Membrane electrode assembly having annealed polymer electrolyte membrane
WO2001080336A3 (fr) * 2000-04-18 2002-03-21 3M Innovative Properties Co Ensemble electrode a membrane possedant une membrane d'electrolyte polymerique recuite
JP2004501484A (ja) * 2000-04-18 2004-01-15 スリーエム　イノベイティブ　プロパティズ　カンパニー アニールされたポリマー電解質膜を有する膜電極アセンブリ
US6689501B2 (en) 2001-05-25 2004-02-10 Ballard Power Systems Inc. Composite ion exchange membrane for use in a fuel cell
EP1610347A1 (fr) * 2003-03-28 2005-12-28 Sumitomo Chemical Company, Limited Appareil et procede continu de production d'une membrane d'electrolyte polymere
EP1610347A4 (fr) * 2003-03-28 2009-02-25 Sumitomo Chemical Co Appareil et procede continu de production d'une membrane d'electrolyte polymere
WO2009086364A1 (fr) * 2007-12-27 2009-07-09 3M Innovative Properties Company Encres d'électrodes contenant des solvants coalescents
CN101953013A (zh) * 2007-12-27 2011-01-19 3M创新有限公司 含聚结溶剂的电极墨水
WO2011093495A1 (fr) * 2010-02-01 2011-08-04 旭化成イーマテリアルズ株式会社 Produit de revêtement et corps stratifié
CN102725363A (zh) * 2010-02-01 2012-10-10 旭化成电子材料株式会社 涂料和层积体
CN102725363B (zh) * 2010-02-01 2015-05-06 旭化成电子材料株式会社 涂料和层积体
US9340648B2 (en) 2010-02-01 2016-05-17 Asahi Kasei E-Materials Corporation Coating material and layered body
CN102237534A (zh) * 2010-04-28 2011-11-09 中国科学院金属研究所 一种钒电池用全氟磺酸离子交换膜制备工艺
CN104262665A (zh) * 2014-09-29 2015-01-07 上海金由氟材料股份有限公司 一种可连续化生产全氟磺酸质子交换膜的制备方法
CN114288855A (zh) * 2021-11-25 2022-04-08 国家电投集团氢能科技发展有限公司 一种水电解膜及其制备方法
CN114288855B (zh) * 2021-11-25 2023-03-10 国家电投集团氢能科技发展有限公司 一种水电解膜及其制备方法

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