WO2011154269A1 - Films polymères à base de polyazoles - Google Patents

Films polymères à base de polyazoles Download PDF

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Publication number
WO2011154269A1
WO2011154269A1 PCT/EP2011/058712 EP2011058712W WO2011154269A1 WO 2011154269 A1 WO2011154269 A1 WO 2011154269A1 EP 2011058712 W EP2011058712 W EP 2011058712W WO 2011154269 A1 WO2011154269 A1 WO 2011154269A1
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Prior art keywords
polymer
polyazoles
film
solvent
membrane
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PCT/EP2011/058712
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German (de)
English (en)
Inventor
Eckhard Hanelt
Martin Bortenschlager
Tobias Halbach
Stefan Haufe
Maria Leute
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Wacker Chemie Ag
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Publication of WO2011154269A1 publication Critical patent/WO2011154269A1/fr

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    • 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
    • C08J5/2256—Synthetic macromolecular compounds based on macromolecular compounds obtained by reactions other than those involving carbon-to-carbon bonds, e.g. obtained by polycondensation
    • 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
    • B01D67/0081—After-treatment of organic or inorganic membranes
    • B01D67/0093—Chemical modification
    • 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
    • B01D67/0081—After-treatment of organic or inorganic membranes
    • B01D67/0093—Chemical modification
    • B01D67/00931—Chemical modification by introduction of specific groups after membrane formation, e.g. by grafting
    • 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
    • B01D71/58—Other polymers having nitrogen in the main chain, with or without oxygen or carbon only
    • B01D71/62—Polycondensates having nitrogen-containing heterocyclic rings in the main chain
    • B01D71/64—Polyimides; Polyamide-imides; Polyester-imides; Polyamide acids or similar polyimide precursors
    • 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
    • C08J5/18—Manufacture of films or sheets
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/08—Specific temperatures applied
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/08—Specific temperatures applied
    • B01D2323/081—Heating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/30—Cross-linking
    • 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
    • C08J2379/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2361/00 - C08J2377/00
    • C08J2379/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
    • C08J2379/06—Polyhydrazides; Polytriazoles; Polyamino-triazoles; Polyoxadiazoles
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0065—Solid electrolytes
    • H01M2300/0082—Organic polymers
    • 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 invention relates to polymer films based on polyazoles, processes for their preparation and their use, in particular for the preparation of polymer electrolyte membranes.
  • Polyazoles especially polybenzimidazole (PBI), and membranes made therefrom have long been known.
  • Crosslinked polymer films of polybenzimidazole (PBI) are distinguished by high thermal and chemical resistance and are therefore used, for example, as semipermeable membranes as described, inter alia, in US Pat. No. 4,020,142 or as polymer electrolyte membranes for fuel cells as disclosed in EP-B 1 165 670.
  • crosslinking often leads to an improvement of the selectivity with simultaneously reduced permeability.
  • US 6,946,015 BB it is shown that the cross-linking of PBI does not adversely affect the ratio of selectivity to permeability. In this case, the C0 2 / CH 4 selectivity in the cross-linked PBI membrane decreases even less with increasing permeability than with the untwisted membrane.
  • a fuel such as hydrogen gas
  • the fuel and an oxidizing agent such as oxygen
  • the membrane contains an electrolyte which is permeable to protons but not to the reactive gases.
  • Materials used for this purpose are, for example, perfluorosulfonic acid polymers which have been swollen with water. or basic polymers containing strong acids as a liquid electrolyte.
  • EP-A 787 369 describes a process for producing a proton-conducting polymer electrolyte membrane in which a basic polymer such as polybenzimidazole is doped with a strong acid such as phosphoric acid or sulfuric acid.
  • a fuel cell with such a membrane is that it can be operated at temperatures above 100 ° C to about 200 ° C, because the polymer is sufficiently stable and the boiling point of the acid is well above 100 ° C.
  • the catalyst activity is increased at the electrodes, reduces the sensitivity of the catalysts against carbon monoxide contamination in the fuel gas and made the waste heat with higher temperature technically better usable.
  • Polybenzimidazoles were obtained from H. Vogel and CS. Marvel in “Polybenzimidazoles, new thermally stable polymers", Journal of Polymer Science 50 (154) p. 511-539 (1961). Particularly preferred for the preparation of polymer electrolyte membranes is the poly-2,2'- (m-henylene) -5, 5 1 -bi- benzimidazole.
  • the polymer chains of the polybenzimidazoles are generally in a polar, aprotic solvent such as at For example, N, N-dimethylacetamide or soluble in acids.
  • Membranes of PBI are therefore usually, for example, in US 4, 020, 142, A, EP 1 373 379 B, EP 1 425 336 B or WO
  • 05076401 A covalently using bifunctionally reactive additives or ionically crosslinked by additives with polar groups.
  • a solution which contains the basic polymer and a bridging reagent is used and then the bridging is carried out.
  • Bisphenol A diglycidyl ethers and 1,4-butyl diglycidyl ethers are used as particularly preferred bridging reagents.
  • ethers are easily radically oxidized at elevated temperature and can be cleaved by acids. Therefore, the long-term stability of the bridging is limited. According to EP-B 1 373 379 these membranes are also in need of improvement in terms of their mechanical strength and in particular the fracture toughness is still insufficient.
  • bridging reagent which preferably has at least two epoxide groups or isocyanate groups per molecule
  • the long-term stability of bridging is not improved by this measure.
  • Polybenzimidazole is characterized by exceptionally high thermal and chemical resistance.
  • Crosslinking with additional additives therefore always entails the risk that the bridging via the additive will in the long term be less stable.
  • bil is considered to be the pure PBI and therefore the mechanical stability of such a cross-linked PBI membrane is slowly decreasing, especially in an aggressive environment such as in a fuel cell.
  • the present invention relates to polymer films based on polyazoles, which are soluble in N, N-dimethylacetamide 0 to 20 wt .-% in terms of their Polyazolgehalt at 130 ° C and 1000 hPa, which can be prepared by that
  • the mixture obtained in the first step is applied to a support
  • the polymer film obtained in the third step is heated in the presence of oxygen to a temperature in the range of 200 to 500 ° C.
  • Another object of the present invention is a process for the preparation of polymer films based on polyazoles, characterized in that
  • the mixture obtained in the first step is applied to a support, in a third step
  • the polymer film obtained in the third step is heated in the presence of oxygen to a temperature in the range of 200 to 500 ° C.
  • the polymer films according to the invention are preferably 0 to 10% by weight, particularly preferably 0 to 5% by weight, in particular 0 to 2% by weight -, soluble.
  • the polyazoles (A) used according to the invention may be any and all known polyazoles which, in addition to the azole building block, contain at least one further aromatic or heteroaromatic.
  • polyazoles (A) used according to the invention are those based on monomers selected from pyrrole, pyrazole, benzpyrazole, oxazole, benzoxazole, thiazole, benzothiazole, imidazole and benzimidazole, and additionally aromatic or heteroaromatic groups, such as phenylene, naphthalene -, pyridine, pyrimidine or pyrazine groups.
  • the different groups can also be linked via amide, imide, ether, thioether or direct CC bonds.
  • the polyazoles (A) used according to the invention and processes for their preparation are already known. For example, see H. Vogel, CS.
  • the polyazoles (A) can be prepared by various and known methods and carry as end groups usually those of the monomers used for the preparation, such as amino and / or carboxylic acid groups and / or their esters, or introduced by subsequent chemical reaction any
  • End groups e.g. Alkyl, aryl, alkenyl, OH, epoxide, keto, aldehyde, ester, thiol, thioester, silyl, oxime,
  • polyazoles (A) are preferably those having amino and / or Carbonklareend- groups, particularly preferably NH 2 - and / or COOH end groups, in particular more than 50% of all end groups are NH 2 radicals ,
  • the polyazoles (A) are particularly preferably polybenzimidazoles (as described, for example, in H. Vogel, CS Marvel "Polybenzimidazoles, new thermally stable polymers", Journal of Polymer Science 50 (154), pages 511-539 (1961) ), in particular poly-2, 2 '- (m-phenylene) -5, 5 1 -dibenzimidazol with amino and / or carboxylic acid end groups, more preferably NH 2 and / or COOH end groups, in particular more than 50% of all end groups are NH 2 residues.
  • Polybenzimidazole (A) can be prepared by various and known methods, such as by polymerization of diaminobenzidine and isophthalic acid and / or their esters.
  • Polybenzimidazoles (A) may have, as end groups, amino and / or carboxylic acid groups and / or their esters, or end groups introduced by subsequent chemical reaction, such as, for example, alkyl, aryl, alkenyl, OH, epoxide, keto , Aldehyde, ester, thiol, thioester, silyl, oxime, amide, imide, urethane and urea groups.
  • the polyazoles (A) used according to the invention may have a different number of amino and / or carboxylic acid end groups.
  • the component (A) used according to the invention contains at least in part polyazoles having at least 3 NH 2 and / or COOH end groups, more preferably more than 20% of the polyazoles carry 4 NH 2 groups per molecule.
  • the polyazoles (A) used according to the invention have an inherent viscosity of preferably> 0.1 dl / g, particularly preferably from 0.1 to 2.5 dl / g, in particular from 0.3 to 1.5 dl / g, in each case measured on a 0.4% (w / v) solution, ie 0.4 g / 100 ml, of polyazole in H 2 S0 4 (95-97%) with an Ubbelhode viscometer at a temperature of 25 ° C and a Pressure of 1000 hPa.
  • the component (A) used according to the invention has a molecular weight M w of preferably 1,000 to 300,000 g / mol, particularly preferably 4,000 to 150,000 g / mol, measured in each case as absolute molecular weight by GPC coupled with static light scattering (mobile phase: DMAc mixed with 1% LiBr).
  • (A) is poly-2,2'- (m-phenylene) -5,5'-dibenzimidazole having amino and / or carboxylic acid end groups and an inherent viscosity of 0.3 to 1.5 dl / g measured on a 0.4% (w / v) solution, ie 0.4 g / 100 ml, of polyazole in H 2 S0 4 (95-97%) with an Ubbelhode viscometer at a temperature of 25 ° C and a pressure of 1000 hPa.
  • the mixture according to the first step of the invention preferably contains at least 1% by weight of polyazole (A), more preferably at least 5% by weight of polyazole, especially at least 10% by weight.
  • the mixture preferably contains at most 90% by weight, more preferably at most 70% by weight, in particular at most 50% by weight, of polyazole (A).
  • Examples of the solvents (B) used according to the invention are all polar aprotic solvents which do not react with the other mixture constituents (A) and (C).
  • solvent (B) are N, N-dimethylacetamide, dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone or mixtures of the abovementioned solvents, with N, N-dimethylacetamide being particularly preferred.
  • solvent does not mean that all components of the mixture must dissolve completely in it.
  • the mixture according to the first step of the invention contains solvent (B) in amounts of preferably from 10 to 99% by weight, more preferably from 30 to 95% by weight, in particular from 50 to 90% by weight.
  • the mixtures according to the first step of the invention may contain further substances (C), such as organic compounds which contain no reactive groups to NH groups, inorganic substances such as metal oxides or additives such as surfactants or adhesion promoters which contain no reactive groups to NH groups and can serve to modify the properties of the surface of the crosslinked polymer film, such as the surface tension. If further substances (C) are used, these are preferably inorganic substances.
  • the mixture according to the first step of the invention contains further substances (C) in amounts of preferably 0 to 90 parts by weight, more preferably 0 to 50 parts by weight, in particular 0 to 20 parts by weight, in each case based on 100 parts by weight of polyols. lyazol.
  • the mixture preferably contains no further substances (C).
  • the mixtures in the first step preferably contain no further constituents.
  • the components used according to the invention may each be one type of such a component as well as a mixture of at least two types of a respective component.
  • the mixture according to the first step can be prepared by any desired methods known per se, for example by simply mixing the individual constituents in any order and, if appropriate, stirring.
  • the first step according to the invention is carried out at temperatures of preferably 20 to 350.degree. C., particularly preferably 100 to 300.degree. C., in particular 150 to 250.degree.
  • the first step according to the invention is preferably carried out at the pressure of the surrounding atmosphere, ie 900 to 1100 hPa. It can also be performed at lower or higher pressures.
  • the first step according to the invention is preferably carried out in an inert gas atmosphere, such as under argon or nitrogen purge.
  • the first step according to the invention can be carried out continuously or discontinuously.
  • the mixture is preferably stirred until the polyazole (A) has preferably dissolved more than 90% by weight, more preferably completely, in the solvent (B). If desired, portions of component (A) and / or (C) that did not dissolve in solvent (B) may remain in the solution or be filtered off.
  • the mixture according to the first step is preferably a solution, a suspension or a paste.
  • the polyazole (A) and optionally used further substances (C) is dissolved in the solvent (B).
  • Suspension are particles of the polyazole (A) and / or other substances (C) dispersed in the solvent serving as a continuous phase.
  • the mixture of the first step is particularly preferably a solution, in particular having a honey-type viscosity.
  • the application of the mixture obtained in the first step according to the invention to a support can be carried out using any suitable discontinuous and continuous coating method known hitherto.
  • the application is carried out by pouring out the mixture on a planar substrate, by application with a roller or slot die, by the doctor blade method or spin coating.
  • the selected application method also depends on the desired layer thickness of the dry polymer film according to the third step of the invention.
  • Examples of carriers which can be used in the second step according to the invention are all carriers known hitherto, which are well wetted by the mixtures according to the invention, are largely resistant to the components (A), (B) and optionally (C) contained in the mixtures and have dimensional stability in the temperature range used.
  • Examples of such carriers are polymer films such as poly (ethylene terephthalate), polyimide, polyethyleneimide, polytetrafluoroethylene and polyvinylidene fluoride films, metal surfaces such as stainless steel strips, glass surfaces and siliconized papers.
  • the polymer film when the polymer film is to be removed from the carrier after the preparation, carriers are preferred which are chemically inert to the mixture according to the first step.
  • the application can also be carried out on a functional carrier, which is part of the respective application.
  • the mixture in the case of manufacturing a semi-permeable membrane, the mixture may be applied to an open-pored film or backing fabric.
  • the mixture When used as a fuel cell membrane, the mixture can be applied directly to the gas diffusion layer or the electrode thereon.
  • the carriers used are those which are wetted by the mixture according to the first step, wherein the contact angle of the mixture on the carrier is preferably less than 90 °, particularly preferably less than 30 °, in each case measured with inert gas as the surrounding Phase.
  • the second step according to the invention can be carried out continuously or discontinuously.
  • the second step of the invention is preferably carried out at temperatures below the boiling point of the solvent (B), more preferably in the temperature range of 10 to 80 ° C, in particular 15 to 40 ° C.
  • the second step of the invention is preferably carried out at the pressure of the surrounding atmosphere, ie 900 to 1100 hPa. It can also be performed at lower or higher pressures.
  • the second step according to the invention is preferably carried out in air in a low-dust environment or in a clean room environment, which helps to ensure a constant film quality.
  • the customary processes known from the prior art for drying can be used.
  • the polymer film is preferably heated to the extent that the solvent or solvent mixture escapes without impairing the homogeneity of the film.
  • the polymer film can be dried at different pressures, preferably at the pressure of the surrounding atmosphere, ie at 900 to 1100 hPa, or under reduced pressure.
  • the third step of the invention is preferably carried out at temperatures below the boiling point of the solvent (B), more preferably at 50 to 150 ° C, especially 80 to 150 ° C.
  • the third step according to the invention is preferably carried out in air in a low-dust environment or in a clean room environment, which contributes to ensuring a constant film quality.
  • the third step according to the invention can be carried out continuously or discontinuously. If the third step according to the invention is to be carried out continuously, for example, a drying oven or heated rolls / belts or a floating dryer can be used to remove the solvent by means of warm wind.
  • the desired thickness of the dry polymer film depends on the requirements of the particular application. As semipermeable membranes thin layers between 1 and 20 ⁇ are preferred, especially when the film is mechanically supported by a porous support.
  • the thickness of the dry polymer film is preferably between 20 and 200 .mu.m.
  • the third step according to the invention preference is given to producing polymer films having a thickness of from 1 to 500 ⁇ m, more preferably from 5 to 200 ⁇ m.
  • the dried polymer film can now be removed from the carrier in accordance with the third step or, if the carrier has sufficient thermal stability, remain thereon.
  • the heating of the polymer film at 200 ° C to 500 ° C in the fourth step can be carried out by any and all known methods, such as in a hot air oven or by contact with hot surfaces.
  • the maximum temperature in the fourth step of the invention is limited primarily by the stability of the polymer and the economics of the process. It is preferably below 450 ° C and more preferably below 400 ° C.
  • the temperature in the fourth step according to the invention is preferably in the range from 250 to 400.degree. C., more preferably from 300 to 400.degree.
  • the maximum duration of heating in the fourth step according to the invention is limited mainly by economic aspects. Annealing takes place over a period of preferably 1 second to 24 hours, more preferably 1 minute to 10 hours, in particular 1 to 4 hours.
  • the fourth step according to the invention is preferably carried out at the pressure of the surrounding atmosphere, ie 900 to 1100 hPa. It can also be performed at lower or higher pressures.
  • the fourth step according to the invention is carried out in the presence of oxygen, preferably using a gas mixture which contains more than 1% by weight of oxygen, more preferably more than 5% by weight of oxygen, in particular more than 10% by weight. Contains% oxygen.
  • the fourth step according to the invention is very particularly preferably carried out in the presence of air.
  • the fourth step according to the invention can be carried out continuously or discontinuously.
  • the polymer film can be guided, for example, over heatable rolls made of stainless steel or sintered metal.
  • a variant of the fourth step according to the invention is that the third and the fourth step continuously merge into each other, in which e.g. the coated carrier remains in the drying apparatus and this is heated to a temperature according to the fourth step.
  • polymer films are now obtained which have a polyazole fraction, optionally a residual amount of solvent and optionally further substances.
  • the quality of the resulting polymer films is assessed by determining the soluble in ⁇ , ⁇ , - dimethylacetamide shares of polyazole in the polymer film.
  • the polymer films according to the invention or produced according to the invention can now be used for all purposes for which polymer films have hitherto also been used.
  • the polymer film according to the invention can be modified in further process steps by methods known per se.
  • the polymer film obtained in the fourth step can be doped with a strong acid in a fifth step, if appropriate.
  • the doping takes place in accordance with the invention, if necessary. carried out fifth step, preferably below 200 ° C, more preferably at 20 to 160 ° C, in particular at 35 to 130 ° C.
  • the polymer film is immersed in a highly concentrated strong acid over a period of preferably at most 5 hours and more preferably 1 minute to 1 hour, wherein a higher temperature shortens the immersion time.
  • the amount of acid (D) used in the fifth process step optionally carried out is usually from 5 to 10,000 times the amount, preferably from 6 to 5000 times the amount, more preferably from 6 to 1000 times the amount , in each case based on the weight of the polymer (A) in the polymer film.
  • a strong acid may be metered onto the polymer film and the film heated until the film has completely absorbed the acid.
  • the amount of acid (D) used in the fifth process step optionally carried out in this variant is usually 2 to 10 times the amount, preferably 3 to 8 times, in each case based on the weight of the polymer film.
  • the polymer film for the production of a membrane electrode assembly is pressed between two acid-soaked gas diffusion electrodes.
  • the amount of the acid (D) used in the fifth invention optionally carried out Process step in this variant is usually 2 to 10 times the amount, preferably 3 to 8 times the amount, each based on the weight of the polymer film.
  • Strong acids in the fifth step according to the invention are protic strong acids (D), such as, for example, phosphorus-containing acids and sulfuric acid.
  • phosphorus-containing acids polyphosphoric acid, phosphonic acid (H 3 P0 3), Orthophosphorkla- acid (H 3 PO 4), pyrophosphoric acid (H 4 P 2 0 7), triphosphoric acid (H 5 P 3 O 10 ) and metaphosphoric acid.
  • the polyazole (A) in the film according to the invention can be impregnated with a larger number of molecules of strong acid with increasing concentration of the strong acid, the phosphorus-containing acid, in particular orthophosphoric acid, preferably has a concentration of at least 70% by weight. % and more preferably at least 85% by weight in water.
  • the optionally performed fifth process step according to the invention is carried out at the pressure of the surrounding atmosphere, ie 900 to 1100 hPa. It can also be performed at lower or higher pressures.
  • the polymer electrolyte membrane obtained according to the invention in the fifth step is proton-conducting and therefore can preferably be used as electrolyte for fuel cells.
  • the polymer electrolyte is not limited to the use for cells, but may for example also be used as the electrolyte for a display element, an electrochromic element or various sensors.
  • Another object of the invention are polymer electrolyte membranes based on polyazoles, which are soluble in terms of their Polyazolgehalt at 130 ° C and 1000 hPa in N, N-dimethylacetamide 0 to 20 wt .-%, which can be prepared thereby that, that
  • the mixture obtained in the first step is applied to a support
  • the polymer film obtained in the third step is heated in the presence of oxygen to above 200 to 500 ° C and
  • the polymer film obtained in the fourth step is doped with a strong acid.
  • Another object of the present invention is a process for the preparation of polymer electrolyte membranes based on polyazoles, characterized in that
  • the mixture obtained in the first step is applied to a support
  • the polymer film obtained in the third step is heated in the presence of oxygen to a temperature in the range of 200 to 500 ° C, and
  • the polymer film obtained in the fourth step is doped with a strong acid.
  • Each individual cell in a fuel cell usually contains a polymer electrolyte membrane according to the invention and two electrodes, between which the polymer electrolyte membrane is sandwiched.
  • the electrodes each have a catalytically active layer and a porous gas diffusion layer.
  • Another object of the invention is the use of the polymer electrolyte membranes according to the invention or inventively prepared for the production of membrane electrode units for fuel cells.
  • Another object of the invention is a membrane-electrode assembly containing at least one electrode and at least one inventive or inventively prepared polymer electrolyte membrane.
  • the invention therefore also relates to the use of the polymer films according to the invention or the polymer films produced according to the invention as a semipermeable membrane for the separation of liquids and gases.
  • the polymer films according to the invention have the advantage that they have high mechanical stability and excellent long-term thermal and chemical stability.
  • the method according to the invention has the advantage that it is easy to carry out.
  • the process according to the invention has the advantage that largely insoluble polymer films can be produced without the use of bridging reagents.
  • the air used in the experiments contains 23% by weight of oxygen and 50% of relative humidity.
  • solubility test the solubility of the polyazole portion of the polymer films produced was determined as follows ("solubility test"):
  • the membrane piece is dried at 150 ° C, weighed and extracted for one hour at 130 ° C and 1000 hPa in dimethylacetamide. After one hour, the membrane is again dried at 150 ° C and then weighed.
  • the inherent viscosity became. measured as follows:
  • the polymer is first dried at 160 ° C for 2 h. 400 mg of the thus dried polymer are then dissolved for 4 hours at 80 ° C in 100 ml of concentrated sulfuric acid (concentration 95- 97 wt.%). The inherent viscosity is determined from this 0.4% (w / v) solution according to ISO 3105 with an Ubbelhode viscometer at a temperature of 25 ° C. example 1
  • the polybenzimidazole thus prepared had an inherent viscosity of 0.70 dl / g.
  • the preparation of the polymer was carried out as described above under a) with the difference that the 3, 3 1 -Diaminobenzidin with 1.053 times (molar) of isophthalic acid (excess acid) is reacted.
  • the polybenzimidazole thus prepared had an inherent viscosity of 0.43 dl / g.
  • film 2b The film thus obtained is referred to below as film 2b.
  • tensile stress measurements were carried out.
  • film samples having a length of 6 cm and a width of 1 cm were clamped in a measuring apparatus from Zwick GmbH & Co. (model Z010 TN, sample holder 8106) and pulled apart at a speed of 5 cm / min.
  • the polymer film film 2a cracked at a tension of 142 N / mm 2 and an elongation of 4%.
  • the polymer film 2a was used to determine the soluble polyazole content in accordance with the solubility test described above. The weight difference was 1%.
  • polybenzimidazole according to Example la 12.0 g of polybenzimidazole according to Example la were dissolved in 88.0 g of N, N-dimethylacetamide (DMAc) in a pressure reactor (Büchi miniclave, 200 ml) with stirring at a temperature of 200 ° C. After filtration and degassing, the solution was applied by means of a film-drawing device with a gap of 0.4 mm to a carrier film of polyethylene terephthalate PET having a thickness of 0.175 mm (commercially available under the trade name "Melinex O" from Pütz GmbH, Germany) The film was separated from the base film at 80 ° C., 10 minutes at 100 ° C. and 30 minutes at 150 ° C.
  • DMAc N, N-dimethylacetamide
  • polybenzimidazole according to Example la 12.0 g of polybenzimidazole according to Example la were dissolved in 88.0 g of N, N-dimethylacetamide (DMAc) in a pressure reactor (Büchi miniclave, 200 ml) with stirring at a temperature of 200 ° C. After filtration and degassing, the solution was applied by means of a film-drawing device with a gap of 0.4 mm to a carrier film of polyethylene terephthalate PET having a thickness of 0.175 mm (commercially available under the trade name "Melinex O" from Pütz GmbH, Germany) The film was separated from the base film at 80 ° C., 10 minutes at 100 ° C. and 30 minutes at 150 ° C.
  • DMAc N, N-dimethylacetamide
  • Example 2aa The procedure described in Example 2aa is repeated with the modification that the last step is carried out for 300 min at 300 ° C in an argon atmosphere instead of air.
  • the argon-heated film almost completely dissolved.
  • Its soluble Polyazolanteil according to the solubility test described above was 79 wt .-%.
  • Example 2aa The procedure described in Example 2aa is repeated with the modification that the last step is carried out for 360 min at 300 ° C in air (film 5a).
  • Example 2ab The procedure described in Example 2ab is repeated with the modification that the last step is performed for 360 min at 300 ° C in air (film 5b).
  • the soluble fraction according to the above-described solubility test of the polymer film 5a with the amine-terminated polymer of Example la was less than 1%
  • the soluble portion of the polymer film 5b with the carboxy-terminated polymer of Example 1b was 4%.
  • the membrane-electrode unit from Example 7 was installed in a conventional arrangement in a test cell (quickCONNECT F25 from. Baltic-FuelCells GmbH, Germany) and closed with a pressing force of 3.5 kN.
  • the operation of the test cell was carried out on a MILAN test rig from Magnum Fuel Cell AG.
  • Figure 1 shows the course of the current-voltage curve at 160 ° C.
  • the gas flow for hydrogen was 196 nml / min and for air

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Abstract

L'invention concerne des films polymères à base de polyazoles, dont 0 à 20% en poids, par rapport à leur teneur en polyazole, sont solubles à 130°C et 1000 hPa dans du N,N-diméthylacétamide. L'invention concerne également un procédé pour la production desdits films ainsi que l'utilisation de ces derniers en tant que membrane échangeuse de protons pour la production d'unités membrane-électrode destinées à des piles à combustible et en tant que membrane semi-perméable pour la séparation de liquides et de gaz.
PCT/EP2011/058712 2010-06-11 2011-05-27 Films polymères à base de polyazoles WO2011154269A1 (fr)

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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4020142A (en) 1975-08-21 1977-04-26 Celanese Corporation Chemical modification of polybenzimidazole semipermeable
US5277981A (en) * 1992-05-28 1994-01-11 Hoechst Celanese Corp. Thermo-oxidatively stabilized polybenzimidazole-containing articles
EP0787369A1 (fr) 1994-11-01 1997-08-06 Case Western Reserve University Polymeres conducteurs des protons
EP1165670B1 (fr) 1999-01-27 2005-01-26 Pemeas GmbH Procede de production d'une membrane polymerique pontee et pile a combustible
WO2005076401A1 (fr) 2004-02-04 2005-08-18 Sartorius Ag Membranes pour piles a combustible, procede pour produire de telles membranes et pour produire des piles a combustibles en utilisant de telles membranes
EP1373379B1 (fr) 2001-03-07 2005-08-31 Pemeas GmbH Procede pour produire une membrane en polymere ponte et cellule electrochimique
US6946015B2 (en) 2003-06-26 2005-09-20 The Regents Of The University Of California Cross-linked polybenzimidazole membrane for gas separation
EP1425336B1 (fr) 2001-08-16 2008-03-26 BASF Fuel Cell GmbH Procede de fabrication d'une membrane constituee d'un melange a base de polymere ponte et pile a combustible associee

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4020142A (en) 1975-08-21 1977-04-26 Celanese Corporation Chemical modification of polybenzimidazole semipermeable
US5277981A (en) * 1992-05-28 1994-01-11 Hoechst Celanese Corp. Thermo-oxidatively stabilized polybenzimidazole-containing articles
EP0787369A1 (fr) 1994-11-01 1997-08-06 Case Western Reserve University Polymeres conducteurs des protons
EP1165670B1 (fr) 1999-01-27 2005-01-26 Pemeas GmbH Procede de production d'une membrane polymerique pontee et pile a combustible
EP1373379B1 (fr) 2001-03-07 2005-08-31 Pemeas GmbH Procede pour produire une membrane en polymere ponte et cellule electrochimique
EP1425336B1 (fr) 2001-08-16 2008-03-26 BASF Fuel Cell GmbH Procede de fabrication d'une membrane constituee d'un melange a base de polymere ponte et pile a combustible associee
US6946015B2 (en) 2003-06-26 2005-09-20 The Regents Of The University Of California Cross-linked polybenzimidazole membrane for gas separation
WO2005076401A1 (fr) 2004-02-04 2005-08-18 Sartorius Ag Membranes pour piles a combustible, procede pour produire de telles membranes et pour produire des piles a combustibles en utilisant de telles membranes

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LIU Z ET AL: "Study of the oxygen reduction reaction (ORR) at Pt interfaced with phosphoric acid doped polybenzimidazole at elevated temperature and low relative humidity", ELECTROCHIMICA ACTA, ELSEVIER SCIENCE PUBLISHERS, BARKING, GB, vol. 51, no. 19, 20 May 2006 (2006-05-20), pages 3914 - 3923, XP025168835, ISSN: 0013-4686, [retrieved on 20060520], DOI: 10.1016/J.ELECTACTA.2005.11.019 *
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MICHAEL JAFFE ET AL: "Thermal Characterization of High Performance PBI and 6F Polymers and Their alloys", POLYMER ENGINEERING AND SCIENCE, vol. 32, no. 17, 1 September 1992 (1992-09-01), pages 1236 - 1241, XP055005680 *
SAMMS ET AL: "Thermal Stability of Proton Conducting Acid Doped Polybenzimidazole in Simulated Fuel Cell Environment", JOURNAL OF THE ELECTROCHEMICAL SOCIETY, ELECTROCHEMICAL SOCIETY. MANCHESTER, NEW HAMPSHIRE, US, vol. 143, no. 4, 1 April 1996 (1996-04-01), pages 1225 - 1232, XP009016015, ISSN: 0013-4651 *
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