JP2014500567A - Mechanically stable polyazole - Google Patents

Abstract

I) a solution comprising at least one polyazole having at least one amino group in a repeating unit, and (i) at least one strong acid and (ii) at least one stabilizer, wherein the stabilization in this solution The total amount of agent ranges from 0.01 to 30% by weight),
ii) a mechanically stable polyazole comprising a step of performing a stabilization reaction directly and / or by heating to a temperature exceeding 25 ° C. in a subsequent processing step using at least one high-functionality polyether as a stabilizer. Manufacturing method.
The polyazole obtained in this way is characterized by a particularly high conductivity and very good mechanical stability. They are therefore particularly suitable for use in fuel cells.

Description

  The present invention firstly provides a mechanically stable polyazole, in particular a mechanically stable polyazole doped with an acid, its production method, its polymer electrolyte membrane (PEM), membrane electrode unit (MEU), PEM. It relates to use in fuel cells. Also, these mechanically stable polyazoles can be preferably used in many other fields.

  Polymer electrolyte membranes (PEM) are known and are used in particular in fuel cells. Often sulfonic acid modified polymers, especially sulfonic acid modified perfluorinated polymers are used. A famous example is Nafion from DuPont (USA). For proton conduction, the membrane needs to have a relatively high moisture content, usually 4-20 molecules of water per sulfonic acid group.

  Due to this required moisture content and the stability of the polymer to acidic water, hydrogen and oxygen reactant gases, the maximum operating temperature of a PEM fuel cell stack is usually limited to 80-100 ° C. Under pressure, this operating temperature can be raised to> 120 ° C. Without pressurization, the performance of the fuel cell degrades at high operating temperatures.

  However, for system reasons, high operating temperatures in excess of 100 ° C. are desirable in fuel cells. The activity of the noble metal-based catalyst present in the membrane electrode unit (MEU) is considerable at high operating temperatures. In particular, when so-called reformed oil obtained from hydrocarbon is used, since a certain amount of carbon monoxide is present in the reformer gas, it is usually necessary to remove it by complicated gas treatment or gas purification. At high operating temperatures, the tolerance of the catalyst to CO impurities increases to a few volume percent CO.

  Also, heat is generated during operation of the fuel cell. However, cooling these systems to below 80 ° C. is very costly and inconvenient. Depending on the power output, the cooling device can be simpler. This means that exhaust heat can be used more efficiently in a fuel cell system that operates at a temperature exceeding 100 ° C., and thus the efficiency of the fuel cell system can be increased by the combined production of power and heat.

  To achieve these temperatures, membranes with new conduction mechanisms are usually used. One direction for this purpose is to use a membrane that exhibits electrical conductivity without the use of water. Initial development in this direction is described, for example, in WO 96/13872. For example, WO 96/13872 discloses the use of an acid-doped polybenzimidazole film produced by a coating method.

  Similarly, a new generation acid-containing polyazole film that exhibits electrical conductivity without the use of water is described in WO02 / 088219. These acid-containing polyazole membranes disclosed in WO 02/088219 have already shown a good series of performances.

  However, in order to use the PEM fuel cell as intended, it is necessary to constantly improve the mechanical properties of these acid-containing polyazole membranes. For example, such membranes are still relatively soft and have insufficient mechanical durability, mechanical stability decreases with increasing temperature, and in the upper range of typical operating ranges (about 160 ° C. to 180 ° C.) Cause stability problems. Therefore, it is desirable to improve mechanical properties, particularly membrane stability, and at the same time achieve high conductivity.

  Mechanical stabilization by cross-linking reactions is already well known in polymer technology. However, the problem with this method is that even though the polymer itself has sufficient mechanical stability, impregnation / doping with a strong acid to impart proton conductivity can cause the polymer to have an inappropriate mechanical stability. Is to decline.

  Initial work to improve the mechanical stability of acid-containing polyazole films is found in WO 00/44816 and WO 02/070592. Here, first, a solution of an aprotic highly polar organic solvent of a polyazole polymer is prepared, and a crosslinking agent is added to this solution. After forming the film, the organic solvent is removed and a crosslinking reaction is performed. The film is then used after being doped with a strong acid. The resulting acid-containing polyazole film has improved mechanical stability and superior conductivity compared to the non-crosslinked acid-containing polyazole film.

  However, cross-linking (bridging) of polyazole polymers is possible by methods known to date, but it has been found that the use of aprotic highly polar organic solvents raises new limitations. In particular, high molecular weight polyazole has low solubility or insolubility in the above organic solvent, and therefore cannot be processed.

  The object of the present invention therefore represents a better method for the mechanical stabilization of polyazoles, preferably for the mechanical stabilization of polyazoles, preferably acid-doped polyazoles, in particular acid-doped polyazole-based membranes. That is. There is also a need to maintain or improve the excellent series of properties of polyazoles, preferably acid-doped polyazoles, more preferably acid-containing polyazole films, particularly conductivity. Another object is to improve the compression stability of the polyazole, preferably an acid-doped polyazole, more preferably its membrane, especially at temperatures in the range of 20 ° C to 200 ° C. It is also necessary that these polyazoles, preferably acid-doped polyazoles, more preferably these membranes, can be produced in a relatively simple manner at the lowest possible cost. Finally, another objective is to provide a solution that is very safe from a health perspective.

  These objects and other objects apparent from the above description are achieved by a method having all the features of claim 1. The dependent claims show particularly preferred embodiments of the method. Also, the stabilized polymer, membrane and membrane electrode assembly obtained by the present method and their preferred fields of use are protected.

Therefore, the present invention
I) a solution comprising at least one polyazole having at least one amino group in a repeating unit, and (i) at least one strong acid and (ii) at least one stabilizer, wherein the stabilization in this solution The total amount of agent ranges from 0.01 to 30% by weight),
II) Mechanically stable polyazole comprising a step of performing a stabilization reaction by heating to a temperature exceeding 25 ° C. directly and / or in a subsequent processing step using at least one high functionality polyether as a stabilizer. A manufacturing method is provided.

  The present invention provides a preferred method for mechanical stabilization of polyazoles, preferably acid-doped polyazoles, especially acid-containing proton conducting polyazole membranes. High molecular weight polyazoles known to date are unstable. Known polyazoles modified by bridging and / or crosslinking do not contain high molecular weight polyazoles.

  In addition, for the first time by the above invention, it is possible to obtain a polyazole having an improved elastic modulus and an improved elongation at break, particularly a proton-conducting high molecular weight polyazole polymer containing an acid. In particular, both properties are very important for use in polymer electrolyte membranes for fuel cells.

  Also, the conductivity of the inventive polymer (preferably a polymer in the form of a membrane comprising at least one inventive polymer) is very high.

  Also, the polymer of the present invention (preferably a polymer in the form of a membrane comprising at least one polymer of the present invention) has improved compression stability, especially at temperatures in the range of 20 ° C to 200 ° C. It is characterized by having a compressed stability.

  Finally, the results of the present invention can be implemented in a relatively simple manner at a low cost on an industrial scale and are absolutely safe from a health perspective.

Polyazole
The polyazole in the present invention is intended to mean a polymer having an aromatic ring having at least one nitrogen atom, preferably at least one repeating unit in the polymer. The aromatic ring is preferably a 5-membered or 6-membered ring having 1 to 3 nitrogen atoms, and this ring may be condensed with other rings, particularly with other aromatic rings. Individual nitrogen heteroatoms may be substituted with oxygen, phosphorus and / or sulfur atoms. The heteroaromatic ring is preferably in the polymer main chain, but may be in the side chain. Basic polymers having an unsaturated 5-membered or 6-membered aromatic unit in the repeating unit containing 1 to 5 nitrogen atoms in the ring or containing one or more other hetero atoms in addition to the nitrogen atom preferable.

The polyazole of the present invention has at least one amino group in the repeating unit. The amino group may be present as a primary amino group (NH ₂ group), or may be present as a secondary amino group (NH group) or a tertiary group, this group being cyclic, if necessary aromatic Or a part of a substituent on the aromatic unit.

  The polymer is basic because of the presence of amino groups in the repeat unit, and the repeat unit selectively reacts with the stabilizer (polyether) via the amino group. In consideration of the reactivity with the stabilizer, the amino group in the repeating unit is preferably a primary or secondary amino group, more preferably a cyclic secondary amino group (suitably a ring of an azole repeating unit). Part of it).

  The method of the present invention is particularly useful for the production of mechanically stable polyazole-based polymer membranes.

  In a first particularly preferred embodiment, the process according to the invention consists of the following steps:

a) producing a film comprising at least one polyazole having at least one amino group in a repeating unit;
b) treating the film from step a) with a solution comprising (i) at least one strong acid and (ii) at least one stabilizer (the total amount of stabilizer in this solution is 0.01-30). A range of weight percent),
c) heating to a temperature in excess of 25 ° C. and performing a stabilization reaction in the film obtained in step b) directly or in a subsequent film processing step;
d) if necessary, further doping the membrane obtained in step c) with a strong acid using at least one high functionality polyether as a stabilizer or concentrating the strong acid present except for the water present. .

  The production of films or foils containing polyazoles is known. Manufacture is performed as described in, for example, WO2004 / 024797, and includes the following steps.

A) one or more aromatic tetraamino compounds and one or more aromatic carboxylic acids or esters thereof having at least two acid groups per carboxylic acid monomer, or one or more aromatic and / or Mixing a heteroaromatic diaminocarboxylic acid in polyphosphoric acid to form a solution and / or dispersion;
B) applying a layer on the support using the mixture from step A);
C) heating the planar structure / layer obtained in step B) under inert gas up to 350 ° C., preferably up to 280 ° C. to form a polyazole polymer;
D) hydrolyzing the polymer membrane formed in step C) (until self-supporting), E) removing the polymer membrane formed in step D) from the support,
F) A step of removing the existing polyphosphoric acid or phosphoric acid and drying it.

  The aromatic and heteroaromatic tetraamino compounds used in the present invention are preferably 3,3 ′, 4,4′-tetraaminobiphenyl, 2,3,5,6-tetraaminopyridine, 1,2, 4,5-tetraaminobenzene, 3,3 ′, 4,4′-tetraaminodiphenyl sulfone, 3,3 ′, 4,4′-tetraaminodiphenyl ether, 3,3 ′, 4,4′-tetraaminobenzophenone 3,3 ′, 4,4′-tetraaminodiphenylmethane, 3,3 ′, 4,4′-tetraaminodiphenyldimethylmethane, and salts thereof, in particular their monohydrochlorides, dihydrochlorides, Hydrochloride and tetrahydrochloride derivatives.

The aromatic carboxylic acid used in the present invention is a dicarboxylic acid and a tricarboxylic acid, a tetracarboxylic acid, or an ester or anhydride thereof, or an acid chloride thereof. “Aromatic carboxylic acid” also includes heteroaromatic carboxylic acids. The aromatic dicarboxylic acid is preferably isophthalic acid, terephthalic acid, phthalic acid, 5-hydroxyisophthalic acid, 4-hydroxyisophthalic acid, 2-hydroxyterephthalic acid, 5-aminoisophthalic acid, 5-N, N-dimethylaminoisophthalic acid. Acid, 5-N, N-diethylaminoisophthalic acid, 2,5-dihydroxyterephthalic acid, 2,6-dihydroxyisophthalic acid, 4,6-dihydroxyisophthalic acid, 2,3-dihydroxyphthalic acid, 2,4-dihydroxyphthalic acid Acid, 3,4-dihydroxyphthalic acid, 3-fluorophthalic acid, 5-fluoroisophthalic acid, 2-fluoroterephthalic acid, tetrafluorophthalic acid, tetrafluoroisophthalic acid, tetrafluoroterephthalic acid, 1,4-naphthalenedicarboxylic acid 1,5-naphthalenedicarboxylic acid 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenic acid, 1,8-dihydroxynaphthalene-3,6-dicarboxylic acid, diphenyl ether-4,4′-dicarboxylic acid, benzophenone-4,4′- Dicarboxylic acid, diphenylsulfone 4,4′-dicarboxylic acid, biphenyl-4,4′-dicarboxylic acid, 4-trifluoromethylphthalic acid, 2,2-bis (4-carboxyphenyl) hexafluoropropane, 4,4 ′ - aryl esters or their acid anhydrides or acid chlorides, - stilbene dicarboxylic acid, 4-carboxycinnamic cinnamic acid or their _C 1 _{-C 20,} - alkyl esters or _C 5 _{-C 12.}

Aromatic tricarboxylic acids, tetracarboxylic acids or their C ₁ -C ₂₀ -alkyl esters or C ₅ -C ₁₂ -aryl esters, or their anhydrides or their acid chlorides are preferably 1, 3, 5 -Benzenetricarboxylic acid (trimesic acid), 1,2,4-benzenetricarboxylic acid (trimellitic acid), (2-carboxyphenyl) iminodiacetic acid, 3,5,3'-biphenyltricarboxylic acid, 3,5,4 ' -Biphenyltricarboxylic acid.

The aromatic tetracarboxylic acids, or their C ₁ -C ₂₀ -alkyl esters or C ₅ -C ₁₂ -aryl esters, or their anhydrides, or their acid chlorides are preferably 3,5,3 ′ , 5′-biphenyltetracarboxylic acid, benzene-1,2,4,5-tetracarboxylic acid, benzophenonetetracarboxylic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, 2,2 ′, 3 3,3′-biphenyltetracarboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid, 1,4,5,8-naphthalenetetracarboxylic acid.

The heteroaromatic carboxylic acid used in the present invention is a heteroaromatic dicarboxylic acid, tricarboxylic acid and tetracarboxylic acid, or an ester or an anhydride thereof. A heteroaromatic carboxylic acid shall mean an aromatic system containing at least one nitrogen, oxygen, sulfur or phosphorus atom in the aromatic ring. These are preferably pyridine-2,5-dicarboxylic acid, pyridine-3,5-dicarboxylic acid, pyridine-2,6-dicarboxylic acid, pyridine-2,4-dicarboxylic acid, 4-phenyl-2,5- Pyridine dicarboxylic acid, 3,5-pyrazole dicarboxylic acid, 2,6-pyrimidine dicarboxylic acid, 2,5-pyrazine dicarboxylic acid, 2,4,6-pyridine tricarboxylic acid, benzimidazole-5,6-dicarboxylic acid, and these C ₁ -C ₂₀ -alkyl ester or C ₅ -C ₁₂ -aryl ester, or an acid anhydride thereof, or an acid chloride thereof.

  The content of tricarboxylic acid or tetracarboxylic acid is 0 to 30 mol%, preferably 0.1 to 20 mol%, particularly 0.5 to 10 mol%, based on the dicarboxylic acid used.

  The aromatic and heteroaromatic diaminocarboxylic acids used in the present invention are preferably diaminobenzoic acid and its monohydrochloride and dihydrochloride derivatives.

  In step A), it is preferred to use a mixture of at least two different aromatic carboxylic acids. It is particularly preferred to use a mixture comprising an aromatic carboxylic acid and a heteroaromatic carboxylic acid. The mixing ratio of the aromatic carboxylic acid and the heteroaromatic carboxylic acid is 1:99 to 99: 1, preferably 1:50 to 50: 1.

  These mixtures are in particular mixtures of N-heteroaromatic dicarboxylic acids and aromatic dicarboxylic acids. Non-limiting examples include isophthalic acid, terephthalic acid, phthalic acid, 2,5-dihydroxyterephthalic acid, 2,6-dihydroxyisophthalic acid, 4,6-dihydroxyisophthalic acid, 2,3-dihydroxyphthalic acid, 2,4-dihydroxyphthalic acid, 3,4-dihydroxyphthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenic acid 1,8-dihydroxynaphthalene-3,6-dicarboxylic acid, diphenyl ether 4,4′-dicarboxylic acid, benzophenone-4,4′-dicarboxylic acid, diphenylsulfone 4,4′-dicarboxylic acid, biphenyl-4,4 ′ -Dicarboxylic acid, 4-trifluoromethylphthalic acid, pyridine-2,5-dicar Acid, pyridine-3,5-dicarboxylic acid, pyridine-2,6-dicarboxylic acid, pyridine-2,4-dicarboxylic acid, 4-phenyl-2,5-pyridinedicarboxylic acid, 3,5-pyrazole dicarboxylic acid, Examples include 2,6-pyrimidine dicarboxylic acid and 2,5-pyrazine dicarboxylic acid.

The polyphosphoric acid used in step A) includes, for example, commercially available polyphosphoric acid available from Riedel de Haen. The content of polyphosphoric acid H _{n + 2} P _n O _{3n + 1} (n> 1) calculated as P ₂ O ₅ (according to acid titration method) is usually at least 83%. Instead of the monomer solution, a dispersion / suspension can also be produced. The weight ratio of the mixture obtained in step A) to the total amount of polyphosphoric acid total monomers is 1: 10000 to 10000: 1, preferably 1: 1000 to 1000: 1, in particular 1: 100 to 100: 1. is there.

  This layer is formed in step B) by methods known from the prior art of polymer film production (casting, spraying, knife coating). Suitable supports are all supports that are inert under these conditions. However, in addition to these inert supports, other supports such as polymer membranes, woven fabrics and non-woven fabrics which are combined with the layer formed in step B) to form a laminate are also suitable. . Phosphoric acid (concentrated phosphoric acid, 85%) can be added to this solution if necessary to adjust the viscosity. This makes it possible to adjust the viscosity to the target value and facilitate film formation. The thickness of the layer obtained in step B) is suitable for subsequent use and is not particularly limited. Usually, the thickness of the formed layer is 1 to 5000 μm, preferably 1 to 3500 μm, particularly 1 to 100 μm.

  The polyazole-based polymer formed in step C) is the same as the above-mentioned polyazole preferably used in the present invention, and is represented by the general formula (I) and / or (II) and / or (III) and / or (IV) and / or (V) and / or (VI) and / or (VII) and / or (VIII) and / or (IX) and / or (X) and / or (XI) and / or (XII) and / or (XIII) ) And / or (XIV) repeating azole units.

Where
Ar may be the same or different and each is a tetravalent aromatic group or a heteroaromatic group, which may be monocyclic or polycyclic,
Ar ¹ may be the same or different and each is a divalent aromatic group or heteroaromatic group, which may be monocyclic or polycyclic,
AR ² may be the same or different and each is a divalent or trivalent aromatic group or heteroaromatic group, which may be monocyclic or polycyclic,
Ar ³ may be the same or different and each is a trivalent aromatic group or a heteroaromatic group, which may be monocyclic or polycyclic,
Ar ⁴ may be the same or different and each is a trivalent aromatic group or a heteroaromatic group, which may be monocyclic or polycyclic,
Ar ⁵ may be the same or different and each is a tetravalent aromatic group or a heteroaromatic group, which may be monocyclic or polycyclic,
Ar ⁶ may be the same or different and each is a divalent aromatic group or a heteroaromatic group, which may be monocyclic or polycyclic,
Ar ⁷ may be the same or different and each is a divalent aromatic group or heteroaromatic group, which may be monocyclic or polycyclic,
Ar ⁸ may be the same or different and each is a trivalent aromatic group or a heteroaromatic group, which may be monocyclic or polycyclic,
Ar ⁹ may be the same or different and each is a divalent, trivalent or tetravalent aromatic group or heteroaromatic group, which may be monocyclic or polycyclic,
Ar ¹⁰ may be the same or different and each is a divalent or trivalent aromatic group or heteroaromatic group, which may be monocyclic or polycyclic,
Ar ¹¹ may be the same or different and each is a divalent aromatic group or heteroaromatic group, which may be monocyclic or polycyclic,
X may be the same or different, each having an oxygen, sulfur or hydrogen atom and another group having from 1 to 20 carbon atoms, preferably an optionally branched alkyl or An amino group having an alkoxy group or an aryl group,
R may be the same or different and is hydrogen, an alkyl group or an aromatic group;
n and m are each an integer of 10 or more, preferably an integer of 100 or more.

  Preferred aromatic or heteroaromatic groups are benzene, naphthalene, biphenyl, diphenyl ether, diphenylmethane, diphenyldimethylmethane, bisphenone, diphenylsulfone, quinoline, pyridine, bipyridine, pyridazine, pyrimidine, pyrazine, triazine, tetrazine, pyrrole, pyrazole, anthracene. , Benzpyrrole, benzotriazole, benzoxathiadiazole, benzoxadiazole, benzopyridine, benzopyrazine, benzopyrazidine, benzopyrimidine, benzopyrazine, benzotriazine, indolizine, quinolidine, pyridopyridine, imidazopyrimidine, pyrazinopyrimidine, carbazole , Acridine, phenazine, benzoquinoline, phenoxazine, phenothiazine, acrididine, Nzoputerijin, phenanthroline, those of phenanthrene, are those necessary replaced.

The substitution pattern of Ar ¹ and Ar ⁴ , Ar ⁶ , Ar ⁷ , Ar ⁸ , Ar ⁹ , Ar ¹⁰ , Ar ¹¹ is arbitrary. In the case of phenylene, for example, Ar ¹ , Ar ⁴ , Ar ⁶ , Ar ⁷ , Ar ⁸ , Ar ⁹ , Ar ¹⁰ , Ar ¹¹ are ortho-, meta-, and paraphenylene. Particularly preferred are groups derived from benzene and biphenylene,
These may be substituted if necessary.

  Preferred alkyl groups are short-chain alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, n- or i-propyl, t-butyl groups.

  A preferred aromatic group is a phenyl group or a naphthyl group. These alkyl groups and aromatic groups may be substituted.

  Preferred substituents are halogen atoms such as fluorine, amino groups, hydroxy groups, or short-chain alkyl groups such as methyl groups and ethyl groups.

  Preference is given to polyazoles having repeating units of the formula (I) in which the X groups in one repeating unit are identical.

  These polyazoles can in principle also have different repeating units with different X groups, for example. However, it is preferable to have a single X group in one repeating unit.

Other preferred polyazole polymers are polyimidazole, polybenzothiazole, polybenzoxazole, polyoxadiazole, polyquinoxaline, polythiadiazole, poly (pyridine), poly (pyrimidine), poly (tetraazapyrene).
In another embodiment of the invention, the polymer having repeating azole units is a copolymer or blend having at least two mutually different units of formulas (I) to (XIV). These polymers may be in the form of block copolymers (diblocks, triblocks), random copolymers, periodic copolymers and / or alternating polymers.

  In a particularly preferred embodiment of the invention, the polymer having repeating azole units is a polyazole having only units of the formula (I) and / or (II).

  The number of repeating azole units in the polymer is preferably an integer of 10 or more. Particularly preferred polymers contain at least 100 repeating azole units.

In the present invention, a polymer having a repeating benzimidazole unit is preferred. Some examples of highly suitable polymers containing repeating benzimidazole units are shown in the following formula.

  In the last formula, the azole unit and the two fluorinated components may be bonded to each other in any arrangement. It can be produced as a polymer, random copolymer or block copolymer.

  N and m in the above formula are each independently an integer of 10 or more, preferably an integer of 100 or more.

  The method of the invention applies in principle to all polyazoles, irrespective of the molecular weight. However, this method has been found to be particularly useful for stabilizing high molecular weight polyazoles not available by any other method. It is known that the high molecular weight measured as the intrinsic viscosity of high molecular weight polyazoles, especially high molecular weight polybenzimidazoles, is at least 18 dl / g, preferably at least 2.0 dl / g, particularly preferably at least 2.5 dl / g. It has been. This upper limit is preferably 8.0 dl / g or less, more preferably 6.8 dl / g or less, and particularly preferably 6.5 dl / g or less. Thus, the molecular weight is much higher than commercial polybenzimidazole (IV <1.1 dl / g).

  The intrinsic viscosity is measured as follows: For this, the polymer is first dried at 160 ° C. for 2 hours. 100 mg of this dry polymer is then dissolved in 100 mL of concentrated sulfuric acid (at least 96% by weight) at 80 ° C. for 4 hours. The intrinsic viscosity or intrinsic viscosity is determined from this solution according to ISO 3105 (DIN 51562, ASTM-D2515) at a temperature of 25 ° C. using an Ubbelohde viscometer.

  If the mixture of step A) also contains a tricarboxylic acid or a tetracarboxylic acid, this results in branching / crosslinking of the polymer formed along the main chain. This improves the mechanical properties.

  In one embodiment of the method, it is possible to form oligomers and / or polymers simply by heating the mixture from step A) to a temperature of up to 350 ° C., preferably to a temperature of up to 280 ° C. is there. Depending on the temperature and time selected, the heating in step C) can then be partly or completely eliminated. This embodiment is also suitable for the production of films that are necessary for step a), preferably containing high molecular weight polyazoles.

  When using an aromatic dicarboxylic acid (or heteroaromatic dicarboxylic acid), for example, isophthalic acid, terephthalic acid, 2,5-dihydroxyterephthalic acid, 4,6-dihydroxyisophthalic acid, 2,6-dihydroxyisophthalic acid, Diphenic acid, 1,8-dihydroxynaphthalene-3,6-dicarboxylic acid, diphenyl ether 4,4′-dicarboxylic acid, benzophenone-4,4′-dicarboxylic acid, diphenylsulfone 4,4′-dicarboxylic acid, biphenyl-4, 4′-dicarboxylic acid, 4-trifluoromethylphthalic acid, pyridine-2,5-dicarboxylic acid, pyridine-3,5-dicarboxylic acid, pyridine-2,6-dicarboxylic acid, pyridine-2,4-dicarboxylic acid, 4-Phenyl-2,5-pyridinedicarboxylic acid, 3,5-pyrazole dicarbo When using acid, 2,6-pyrimidine dicarboxylic acid, 2,5-pyrazine dicarboxylic acid-or if it is desired that the oligomer and / or polymer be formed as early as in step A)-suitable in step C) It has been found that the maximum temperature is in the range of up to 300 ° C, preferably in the range of 100 ° C to 250 ° C.

  The polymer layer obtained in step C) can be processed in various ways to produce the film required for step b).

  In one embodiment (embodiment A), the polyphosphoric acid or phosphoric acid present is left in the film because it does not adversely affect other processing. In this case, the polymer layer produced in step C) is treated in the presence of moisture at a temperature and time sufficient to allow the layer to have sufficient strength for the intended end use. This treatment can be performed until the membrane becomes self-supporting and can be peeled from the support without being damaged (step E). Steps D) and E) can also be carried out simultaneously or subsequently. Also, Steps D) and E) can be combined with Steps b) and c) and, if necessary, Step d). For example, the hydrolysis in step D) is performed by treating the polymer film formed in step C) with a solution containing (i) at least one strong acid and (ii) at least one stabilizer. (Note that the total amount of stabilizer in the solution is in the range of 0.01 to 30% by weight). The stabilization reaction in step c) can be carried out in combination with thermal drying or concentration of the acid present.

  This polymer membrane is in step D) at a temperature above 0 ° C. and below 150 ° C., preferably at a temperature between 10 ° C. and 120 ° C., in particular at a temperature between room temperature (20 ° C.) and 90 ° C. Alternatively, it is treated in the presence of steam and / or up to 85% hydrous phosphoric acid. This treatment is preferably performed under standard pressure, but may be performed under pressure. It is essential that this treatment be carried out in the presence of sufficient moisture and that the resulting polyphosphoric acid is partially hydrolyzed to low molecular weight polyphosphoric acid and / or phosphoric acid to strengthen the membrane. It has been found that a sol-gel transition occurs as a result of this hydrolysis step, which gives the membrane a specific shape.

  Partial hydrolysis of polyphosphoric acid in step D) strengthens the polymer membrane, which makes the membrane self-supporting and reduces the layer thickness.

  The intramolecular and intermolecular structures present in the polyphosphate layer of step B) cause regular film formation in step C), thus improving the performance of the polymer film formed.

  The upper limit temperature of the process D) is generally 180 ° C. If the moisture is allowed to act for a very short time, for example with very superheated water vapor, the steam may be even hotter. An essential factor for the upper limit temperature is the processing time.

  This partial hydrolysis (step D) can also be carried out in an environmentally controlled tank in which the hydrolysis is controlled by specific moisture action. In this case, the humidity can be adjusted in a controlled state by the temperature or saturation of the gas or water vapor such as air, nitrogen, carbon dioxide or the like in the environment in contact. The processing time depends on the variables selected above.

  This processing time also depends on the film thickness.

  In general, the treatment time is, for example, several seconds to several minutes in the treatment with superheated steam, but may be a full day at, for example, room temperature and low relative air humidity. This treatment time is preferably 10 seconds to 300 hours, in particular 1 minute to 200 hours.

  When the moisture treatment is performed at room temperature (20 ° C.) with ambient air having a relative air humidity of 40 to 80%, the treatment time is preferably 1 to 200 hours.

  The polymer membrane obtained in step D) is preferably self-supporting so that it can be peeled off from the support without being damaged in step E), and then, if necessary, other processing is preferably performed directly.

  If the polymer membrane obtained in step C) is processed on a support, for example as a composite membrane, step D) can be completely or partially removed.

  If the polyphosphoric acid or phosphoric acid present after step C) remains in the membrane (embodiment A), the treatment of the film in step b) can be carried out in a hydrolysis bath as in step D). . In this case, the polyphosphoric acid or phosphoric acid present in the film comprises (i) at least one strong acid and (ii)

  Completely or at least partially substituted with a solution containing at least one stabilizer. The stabilization reaction in step c) may be carried out in the hydrolysis bath or afterwards, preferably immediately afterwards. Depending on the stability of the membrane, the treatment in the hydrolysis bath may be carried out on the support or, if necessary, this support can be removed in advance so that step E) can be omitted or brought forward. May be.

  This embodiment also forms part of the subject of the present invention.

  In another embodiment (embodiment B), the existing polyphosphoric acid or phosphoric acid is removed from the membrane. For this, the polymer layer obtained in step C) is treated at a temperature and time sufficient to form a layer with sufficient strength for other handling in the presence of moisture. Accordingly, hydrolysis in step D) and removal in step E) can be carried out simultaneously. This simplification of hydrolysis needs to be present in the treatment in step b) because the existing polyphosphoric acid or phosphoric acid needs to be completely removed and a fresh solution containing a strong acid is supplied later in step b). It is possible when there is no.

  When it is necessary to remove the polyphosphoric acid or phosphoric acid remaining in the polymer film in step F), this can be carried out with a processing liquid within the temperature range from room temperature (20 ° C.) to the boiling point (standard pressure) of the processing liquid. .

  This treatment liquid used in the present invention comprises alcohols and ketones, alkanes (aliphatic and alicyclic), ethers (aliphatic and alicyclic), glycols, esters, carboxylic acids (the above group of compounds are halogenated). A solvent that is liquid at room temperature (ie, at 20 ° C.) selected from the group consisting of:

C ₁ -C ₁₀ -alcohol, C ₂ -C ₅ -ketone, C ₁ -C ₁₀ -alkane (aliphatic and alicyclic), C ₂ -C ₆ -ether (aliphatic and alicyclic), C Preference is given to using _2- C ₅ -esters, C ₁ -C ₃ -carboxylic acids, dichloromethane, water, and mixtures thereof.

  Then the process liquid introduced in step F) is removed once more. This is preferably done by drying, in which case the temperature and ambient pressure values are chosen as a function of the vapor partial pressure of the treatment liquid. Usually, drying is performed at a standard pressure and a temperature of 20 ° C to 200 ° C. It is also possible to dry more gently under reduced pressure. Instead of drying, the membrane can be tapped and dried to remove excess processing liquid. This order is not important.

A polyazole-containing film can also be produced by partially changing the above method. In this case, the following steps are performed:
i) one or more aromatic tetraamino compounds in the form of one or more aromatics having at least two acid groups per carboxylic acid monomer in a molten state at a temperature of at most 350 ° C., preferably at most 300 ° C. Reacting with a carboxylic acid or ester thereof or with one or more aromatic and / or heteroaromatic diaminocarboxylic acids;
ii) dissolving the solid prepolymer obtained in step i) in polyphosphoric acid;
iii) heating the solution obtained in step ii) to a temperature of up to 300 ° C., preferably up to 280 ° C. under an inert gas to form a dissolved polyazole polymer;
iv) forming a membrane on the support using the solution of the polyazole polymer of step iii);
v) A step of treating the film formed in step iv) until it becomes self-supporting.

In addition to the above embodiments, this shaping can also be performed by the following steps:
I) dissolving a polymer, in particular polyazole, in polyphosphoric acid;
II) heating the solution obtained in step I) to a temperature of up to 400 ° C. under inert gas;
III) forming a membrane on a support using the polymer solution of step II);
IV) A step of treating the film formed in step III) until it becomes self-supporting.

  In both embodiments, steps v) or IV) are followed by steps E) and F), which can be both embodiments A) and B).

  Although preferred embodiments of the raw materials and process parameters in steps A), B), C) and D) have already been described, these also apply to this embodiment.

In a further particularly preferred embodiment, the process according to the invention consists of the following steps:
A ′) producing a solution or dispersion of at least one polyazole having at least one amino group in the repeating unit in orthophosphoric acid and / or polyphosphoric acid;
B ′) mixing the solution or dispersion from step A1) with a solution comprising (i) at least one strong acid and (ii) at least one stabilizer (the total amount of stabilizer in the solution is 0 0.01 to 30% by weight),
C ′) heated to a temperature above 25 ° C. directly and / or in downstream processing steps,
Performing a stabilization reaction in the solution obtained in step B1) or in a dispersion;
D ′) If necessary, doping the polymer obtained in step C) with a strong acid using at least one high functionality polyether as stabilizer, or concentrating the strong acid present except for the water present.

  Also in this embodiment of the invention, the use of the preferred polyazoles mentioned above is particularly advantageous.

This solution or dispersion can be prepared by simply mixing these components in step A ′). Alternatively, concentrate H ₃ PO ₄ and / or polyphosphoric acid in a composition with a low P ₂ O ₅ concentration, or dilute a composition with a relatively high P ₂ O ₅ concentration, ie remove water or Supply is also possible.

In this regard, however, in some cases, especially at low temperatures and / or high solids content, the dissolution or dispersion of polyazoles in normal phosphoric acid and / or polyphosphoric acid is kinetically inhibited. It should be noted. In that case, the composition is still present in a heterogeneous form. At high temperatures above 100 ° C., more water is vaporized from the composition and the concentration of H ₃ PO ₄ and / or polyphosphoric acid changes over time.

Therefore, this solution or dispersion is appropriately produced by the following method in step A ′).
a ′) At least one polyazole is dissolved and / or dispersed in orthophosphoric acid and / or polyphosphoric acid (note that calculated as P ₂ O ₅ relative to the total amount of H ₃ PO ₄ and / or polyphosphoric acid and / or water) The concentration of H ₃ PO ₄ and / or polyphosphoric acid is less than 72.0%, preferably less than 71.7%, more preferably?%, Even more preferably less than 71.0%, in particular less than 70.5%. Selected), also
b ') step a') excluding water from the solution or dispersion from _(H 3 PO ₄ and / or polyphosphoric acid and / or _H 3 PO ₄ and / or polyphosphoric calculated as _P 2 _{O 5} to the total amount of water The acid concentration is preferably increased to at least 0.1%, more preferably at least 0.5%, particularly preferably at least 1.0%, in particular at least 1.5%).

  The solution or dispersion from step a ') can generally be prepared by known methods, for example by mixing the components. Other manufacturing methods are described in WO 02/08829.

  More preferably, a solution or dispersion comprising at least one polyazole and polyphosphoric acid is hydrolyzed to obtain the solution or dispersion from step a '). Such a solution or dispersion can be produced by polymerizing the above monomers in polyphosphoric acid.

  The solution or dispersion from step a ′) is preferably in an amount of at least 1.8% by weight, more preferably at least 2.0% by weight, in particular 2.2 to 2.5% by weight, based on its total weight. % Of polyazoles having an intrinsic viscosity in the range of 3.0-8 g / dL measured in at least one 96% by weight sulfuric acid in an amount in the range of%. The amount of normal phosphoric acid, water and, if necessary, phosphoric acid is preferably at most 98.2% by weight, more preferably in the range of 90.0-98.0% by weight, in particular 95.0-97.8% by weight. % Range.

  In step b '), it is preferred that the water is preferably vaporized, in particular the composition from step a') is heated to a temperature in excess of 100 ° C and / or reduced in vacuo to be vaporized off. The composition from step a ′) for at least about 1 hour at most 48 hours, in particular at least 2 hours to at most 24 hours, at a temperature between 120 ° C. and 240 ° C. A method of heating in the range of 120 ° C. to 160 ° C. is particularly preferable.

In another preferred embodiment of the invention, the composition comprises
I ′) First, a solution or dispersion of polyazole in polyphosphoric acid having an intrinsic viscosity measured in at least 96% by weight sulfuric acid in the range of 3.0 to 8.0 g / dL, the temperature exceeding 160 ° C. , Preferably over 180 ° C., in particular in the range of 180 ° C. to 240 ° C. (in this case P ₂ O ₅ (acids relative to the total amount of H ₃ PO ₄ and / or polyphosphoric acid and / or water) The concentration of H ₃ PO ₄ and / or polyphosphoric acid calculated as by titration method is greater than 72.4%, preferably 73.0%, more preferably 74.0%, even more preferably 75.0% , Especially greater than 75.45%)
II ′) The total amount of H ₃ PO ₄ and / or polyphosphoric acid calculated as P ₂ O ₅ (according to acid titration method) relative to the total amount of H ₃ PO ₄ and / or polyphosphoric acid and / or water in the mixture Preferably it is in the range of 71.0-75.0%, more preferably in the range of 71.5-74.0%, still more preferably in the range of 71.7-73.0, until it is in the range of 70.5-75.45%. % Orthophosphoric acid and / or polyphosphoric acid is added to this solution or dispersion until it is in the range of%, especially 72.0-72.4%,
III ′) Produced by homogenization while maintaining the total amount of H ₃ PO ₄ and / or polyphosphoric acid within the range defined in step II ′).

  The solution or dispersion from step I ') can generally be obtained in a known manner, for example by mixing the components. Other manufacturing methods are described in WO 02/08829.

  More preferably, the solution or dispersion from step I ') is obtained by polymerizing the above monomers in polyphosphoric acid.

The solution or dispersion from step I ′) is based on its total weight—preferably at least 1.8% by weight, more preferably at least 2.0% by weight, in particular 2.2 to 2.5% by weight. At least one of the ranges, a polyazole having an intrinsic viscosity measured in at least 96% by weight sulfuric acid in the range of 3.0-8 g / dL;
-Preferably up to 98.2% by weight, more preferably in the range 90.0 to 98.0% by weight, in particular in the range 95.0 to 97.8% by weight polyphosphoric acid and, if necessary, orthophosphoric acid and / or Contains water.

The polyphosphoric acid used may be, for example, a commercially available polyphosphoric acid available from Riedel de Haen. The polyphosphoric acid _{H n + 2 P n O 3n} + 1 (n> 1), content is calculated as (by acid titration) P 2 _{O 5} is preferably at least 83%.

  When such a composition is hydrolyzed by conventional methods, a composition with reduced fluidity that cannot be processed under standard conditions is obtained. Therefore, it is preferable to carry out steps II ') and III').

  The addition in step II ') may be carried out in portions or continuously.

After the addition, the mixture is based on its total weight
The limit measured in at least 96% by weight sulfuric acid, preferably at least 1.6% by weight, more preferably at least 1.8% by weight, in particular in the range from 2.0 to 2.3% by weight. A polyazole having a viscosity in the range of 3.0-8 g / dL;
-Preferably up to 98.4% by weight of polyphosphoric acid, preferably in the range of 90.0 to 98.2% by weight, in particular in the range of 95.0 to 98.0% by weight and, if necessary, normal phosphoric acid and / or Contains water.

  As a result of the addition in step II '), a heterogeneous mixture is first formed. By “non-uniform” is meant a change in optical or physical properties that changes the uniformity of the properties of the entire system, or changes the homogeneity of the appearance of the solution. Usually, the change in homogeneity of this solution is either as an interface shaping (separation of liquid from viscous material), as a color change (usually from green to yellow), or as a particle or solid particle that is clearly seen from a homogeneous solution Appears as a separation. If the appearance is the same as a polyazole solution or dispersion of polyazole, the solution is considered homogeneous and the only difference is the viscosity.

  The homogenization in step III ') is preferably carried out in a closed system, for example in an autoclave. Moreover, it is preferable to condense the water to be vaporized and reflux the mixture, and it is particularly preferable to condense and reflux the water to be vaporized, preferably with at least one reflux condenser directly connected to the reaction vessel.

  Surprisingly, the solution is homogenized after a certain time, preferably in less than 4 hours, in particular within 2 hours. The solution viscosity of the mixture decreases, forming a composition that can be used in the present invention.

  In another particularly preferred embodiment of the invention, orthophosphoric acid is added in step II ').

The process consisting of steps A ′), B ′), C ′) and D ′) is preferably also used for the production of acid-doped polyazole films. To this end, the process optionally comprises i) forming a membrane on the support using the polyazole composition from step A ′), B ′), C ′) or D ′);
ii) treating the film formed in step i) until it is self-supporting.

  Preferred process parameters for these steps have already been detailed above. These also apply to this embodiment of the invention.

Other blend ingredients
In addition to the above preferably high molecular weight polyazoles, blends of one or more preferably high molecular weight polyazoles with other polymers can also be used. This blend component essentially has the role of improving mechanical properties and reducing material costs. Preferred blending components are described in German patent application no. It is a polyether sulfone described in 10052242.4.

Preferred polymers that can be used as blend components include polyolefins such as poly (chloroprene), polyacetylene, polyphenylene, poly (p-xylylene), polyarylmethylene, polyalmethylene, polystyrene, polymethylstyrene, polyvinyl alcohol, polyvinyl acetate. , Polyvinyl ether, polyvinylamine, poly (N-vinylacetamide), polyvinylimidazole, polyvinylcarbazole, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl chloride, polyvinylidene chloride, polytetrafluoroethylene, polyhexafluoropropylene, PTFE and hexafluoropropylene Perfluoropropyl vinyl ether, trifluoronitrosomethane, sulfonyl fluoride vinyl ether, carboal Alkoxy copolymers of perfluoroalkoxy vinyl ether, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, acrolein, polyacrylamide, polyacrylonitrile, poly cyanoacrylates, poly methacrylamide, cyclic olefin copolymers (especially norbornene copolymer);
Polymers having a C—O bond in the main chain, such as polyacetal, polyoxymethylene, polyether, polypropylene oxide, polyepichlorohydrin, polytetrahydrofuran, polyphenylene oxide, polyether ketone, polyester, especially polyhydroxyacetic acid, polyethylene terephthalate , Polybutylene terephthalate, polyhydroxybenzoate, polyhydroxypropionic acid, polypivalolactone, polycaprolactone, polymalonic acid, polycarbonate;
Polymers having a C—S bond in the main chain, such as polysulfide ethers, polyphenylene sulfides, polyether sulfones;
Polymers having a C—N bond in the main chain, such as polyimine, polyisocyanide, polyetherimine, polyaniline, polyamide, polyhydrazide, polyurethane, polyimide, polyazole, polyazine;
Liquid crystal polymers, especially Vectra,
Examples include inorganic polymers such as polysilane, polycarbosilane, polysiloxane, polysilicic acid, polysilicate, silicone, polyphosphazene, and polythiazyl.

  For use in a fuel cell with a sustained use temperature exceeding 100 ° C., the glass transition temperature or Vicat softening temperature VST / A / 50 is at least 100 ° C., preferably at least 150 ° C., most preferably at least 180 ° C. Blend polymers are preferred. Polysulfone having a Vicat softening temperature VST / A / 50 of 180 ° C to 230 ° C is preferred.

  Preferred polymers include polysulfone, particularly polysulfone having an aromatic ring in the main chain.

In one aspect of the present invention, preferred melt volume flow rate MVR300 / 21.6, measured according to ISO1133 of polysulfone and polyether sulfone, or less 40 cm ^3/10 min, in particular 30 cm ^3/10 minutes or less, more preferably not more than 20 cm ^3/10 min.

Other additives
In order to further improve the performance of the product, other fillers, in particular proton-conducting fillers, can also be added to this preferably high molecular weight polyazole.

  Examples of non-limiting proton conductive fillers include:

Sulfates such as CsHSO ₄ , Fe (SO ₄ ) ₂ , (NH ₄ ) ₃ H (SO ₄ ) ₂ , LiHSO ₄ , NaHSO ₄ , KHSO ₄ , RbSO ₄ , LiN ₂ H ₅ SO ₄ , NH ₄ HSO ₄ ,
Phosphates, for _{example, Zr 3 (PO 4) 4} , Zr (HPO 4) 2, HZr 2 (PO 4) 3, UO2PO 4 · 3H 2 O, H 8 UO 2 PO 4, Ce (HPO 4) 2, Ti (HPO ₄ ) ₂ , KH ₂ PO ₄ , NaH ₂ PO ₄ , LiH ₂ PO ₄ , NH ₄ H ₂ PO ₄ , CsH ₂ PO ₄ , CaHPO ₄ , MgHPO ₄ , HSbP ₂ O ₈ , HSb ₂ P ₂ O ₁₄ , H ₅ Sb ₅ P ₂ O ₂₀ ,

Polybasic acids, _{e.g., H 3 PW 12 O 40 ·} nH 2 O (n = 21-29), H 3 SiW 12 O 40 · nH 2 O (n = 21-29), HXWO 3, HSbWO 6, H 3 _{PMo 12 O 40, H 2 Sb} 4 O 11, HTaWO 6, HNbO 3, HTiNbO 5, HTiTaO 5, HSbTeO 6, H 5 Ti 4 O 9, HSbO 3, H 2 MoO 4

Selenite and arsenide, for example, (NH ₄ ) ₃ H (SeO ₄ ) ₂ , UO ₂ AsO ₄ , (NH ₄ ) ₃ H (SeO ₄ ) ₂ , KH ₂ AsO ₄ , Cs ₃ H (SeO ₄ ) ₂ , Rb ₃ H (SeO ₄ ) ₂ ,
Phosphides such as ZrP, TiP, HfP

Oxides such as Al ₂ O ₃ , Sb ₂ O ₅ , ThO ₂ , SnO ₂ , ZrO ₂ , MoO ₃
Silicates such as zeolites, zeolites (NH ₄ +), sheet silicates, reticulated silicates, H-natrolite, H-mordenite, NH ₄ -anarsine, NH ₄ -borosodalite, NH ₄ -galite , H-montmorillonite, silicic acid Si (OH) 4 and other condensation products and their salts and esters,
Polysiloxanes of the general formula H ₃ Si— (O—SiH ₂ —) n—O—SiH ₃ , especially also other clay minerals such as montmorillonite and bentonite, kaolinite, wax, talc, chlorite, muscovite, mica , Smectite, hallosite, vermiculite, hydrotalcite
Acids such as HClO ₄ , SbF ₅

Fillers, such as carbides (especially SiC), Si ₃ N ₄ , fibers (especially glass fibers), glass powders and / or polymer fibers (preferably polyazole-based and partially crosslinked).

  These additives can be present in the amounts conventionally used, but the preferred performance of the polyazole, especially its membrane, such as high conductivity, long life, and high mechanical stability, can be added in excess. It must not be greatly impaired by the addition of objects.

  In general, the polyazole, especially the membrane, contains up to 80% by weight additive, preferably up to 50% by weight, more preferably up to 20% by weight. These additives can be present in different particle shapes and sizes, and can be present as a mixture, more preferably in the form of nanoparticles.

Stabilization In step I), the polyazole is treated with a solution comprising (i) at least one strong acid and (ii) at least one stabilizer.

  Suitable stabilizers in this case are in particular all compounds which can mechanically stabilize this preferably high molecular weight polyazole.

  The organic compound used as a stabilizer must be sufficiently stable against strong acids present in the solution. Further, they have sufficient solubility in strong acid, and the total amount of stabilizer in the solution of step I) is appropriately in the range of 0.01 to 20% by weight, preferably 0.1 to 15% by weight. More preferably, it should be in the range of 0.25 to 10% by weight, particularly 1 to 5% by weight. If the stabilizer does not have sufficient solubility in strong acid, a small amount of other inert solubilizers can be added.

  Overall, however, this solubility is determined by the fact that the solution of step I) is such that the total amount of stabilizer is -0.01 to 100 moles (per repeat unit of polyazole polymer) relative to the polyazole present in the reagent-film. %, Preferably 10 to 80 mol%, in particular 15 to 65 mol%.

  If the proportion of stabilizer chosen is too low, the mechanical strength of this polyazole, in particular the polymer membrane, is not sufficiently improved. If the selected ratio is too high, this polyazole will make the membrane particularly fragile, making the series of properties of the polyazole, especially the membrane, unsuitable.

  In addition, the electrolyte can participate in the crosslinking reaction. Stabilizers will react or interact partially or completely with the electrolyte. This reaction or interaction likewise stabilizes the membrane mechanically and / or chemically and is stabilized against the phosphate environment. When the electrolyte participates in the stabilization reaction, the acid strength can be reduced.

  The proton conductivity at 160 ° C. of the stabilized polyazole, in particular the stabilized membrane, is about 30-300 mS / cm, preferably 90-250 mS / cm.

  Proton conductivity is measured using impedance spectroscopy (Zener IM5 or IM6 spectrometer) and a 4-point test cell. The specific method is as follows.

  In order to prepare the sample, a sample having a size of about 3.5 × 7 cm was cut out, and these membrane samples were rolled 10 times with a 500 g roller-like weight in order to remove excess acid. The thickness of the sample was suitably measured using a Mitutoyo “Absolute Digimatic” thickness meter at three points (the start, center, and end of the sample piece), and the average was obtained. As shown in FIG. 1, the sample is appropriately fixed to the test cell.

The numbers in the table indicate the following:
(1): I ₋
(3): U ₊
(5): U ₋
(7): I ₊
(9): Connector (11): Pt wire
(13): Seal (15): Membrane (17): Pt plate

  The test cell screws are preferably hand tightened and the cell is placed in a controlled oven, preferably operated with the temperature-frequency program described in Table 1.

Ｉ（接点間の距離）＝２ｃｍ、
ｂ（膜幅）＝３．５ｃｍ、
ｄ＝膜厚み（ｃｍ）、
Ｒ＝抵抗測定値（オーム） This oven program is started, and the impedance spectrum is preferably changed from 20 ° C. to 160 ° C., and conversely from −160 ° C. to 20 ° C., using a Zener Electric ZIM6 impedance spectrometer equipped with a 4-point dry test cell. Is measured every 20 ° C., preferably with a holding time before measurement of 10 minutes. This spectrum is stored and preferably evaluated by the methods of the Bode and Niquist literature. Proton conductivity is calculated by the following formula:

I (distance between contacts) = 2 cm,
b (film width) = 3.5 cm,
d = film thickness (cm),
R = resistance measurement (ohms)

  In the present invention, at least one high functionality polyether, preferably at least one polyetherol, is used as a stabilizer.

  In the present invention, a high functionality polyetherol is produced with at least 3, preferably at least 6, more preferably at least 10 OH groups in pendant or terminal positions together with the ether groups forming the polymer backbone. It shall mean a thing. The polymer skeleton may be linear or branched. There is in principle no upper limit on the number of terminal or pendant functional groups, but products with a very large number of functional groups can have undesirable performance, such as high viscosity and poor solubility. The polyfunctional polyetherol used in the present invention usually has not more than 500 terminal functional groups or pendant functional groups, and preferably has not more than 100 terminal OH functional groups or pendant OH functional groups. The high functionality polyetherols used according to the invention are preferably on average at least 3, more preferably at least 4, even more preferably at least 5, in particular at least 6 di-, tri- or higher polyvalents. A condensation product formed from an alcohol. In this case, it is further preferred that the condensation product is formed on average from at least 3, more preferably at least 4, in particular at least 5, in particular at least 6 trivalent or higher polyhydric alcohols. preferable.

  In certain preferred embodiments, these high functionality polyethers are hyperbranched polyetherols. In the present invention, these multi-branched polyether polyols mean uncrosslinked polymer molecules having hydroxyl groups and ether groups which are structurally and molecularly heterogeneous. On the one hand, they can have a dendrimer-like structure extending from the central molecule, but the chain length of the branches is not uniform. On the other hand, they can also have linear regions with functional side groups. For the definition of dendrimeric multibranched polymers, see P.C. J. et al. Flory, J.M. Am. Chem. Soc. 1952, 74, 2718; Frey et al. Chem. Eur. J. et al. 2000, 6, 15 no. 14, 2499.

  In the present invention, “multi-branching” means the degree of branching (DB), that is, the average number of dendritic bonds and the average number of terminal groups per molecule is the sum of the average values of dendritic bonds, linear bonds and terminal bonds. The value obtained by multiplying by 100 is 10 to 99.9%, preferably 20 to 99%, and more preferably 20 to 95%. In the present invention, “dendrimer property” means that the degree of branching is 99.9 to 100%. For the definition of the degree of branching, see H. Frey et al. , Acta Polym. See 1997, 48, 30.

  The trihydric or higher alcohol used is, for example, triol such as trimethylolmethane, trimethylolethane, trimethylolpropane (TMP), 1,2,4-butanetriol. Similarly, tetraols such as bistrimethylolpropane (di-TMP) and pentaerythritol can also be used. Also, more polyvalent polyols such as bispentaerythritol (di-penta) and inositol can be used. Moreover, it is also possible to use an alkoxylation product of the alcohol or glycerol, preferably having 1 to 40 alkylene oxide units per molecule. As trihydric or higher alcohols, aliphatic alcohols, particularly those having primary hydroxyl groups, such as trimethylolmethane, trimethylolethane, trimethylolpropane, di-TMP, pentaerythritol, di-penta, and alkoxylates thereof. Particular preference is given to using glyceryl ethoxylates having 1 to 30 ethylene oxide units per molecule and also having 1 to 30 ethylene oxide units per molecule. Trimethylolpropane, pentaerythritol, and these ethoxylates having an average of 1 to 20 ethylene oxide units per molecule, and the use of glyceryl ethoxylate having 1 to 20 ethylene oxide units per molecule are very preferred. It is likewise preferred to use the above alcohols in the mixture.

  Preference is given to compounds having two OH groups on directly adjacent carbon atoms as trihydric or higher alcohols. Under the conditions of the present invention, desorption of these compounds tends to cause a separation reaction, which proceeds in preference to the etherification reaction. Under the etherification conditions of the present invention, the presence of unsaturated compounds that form by-products gives reaction products that cannot be used in industrially relevant materials. In particular, such side reactions occur with glycerol.

  These trihydric or higher alcohols can also be used as a mixture with dihydric alcohols. Examples of compounds having two OH groups include ethylene glycol, diethylene glycol, triethylene glycol, 1,2- and 1,3-propanediol, dipropylene glycol, tripropylene glycol, neopentyl glycol, 1,2- 1,3- and 1,4-butanediol, 1,2-, 1,3- and 1,5-pentanediol, hexanediol, dodecanediol, cyclopentanediol, cyclohexanediol, cyclohexanedimethanol, bis (4 -Hydroxycyclohexyl) methane, bis (4-hydroxycyclohexyl) ethane, 2,2-bis (4-hydroxycyclohexyl) propane, ethylene oxide, propylene oxide, butylene oxide, or mixtures thereof. Ether polyols or polytetrahydrofuran and the like. It will also be appreciated that dihydric alcohols can be used in the mixture.

  These diols help to fine tune the properties of the polyether polyol. If a dihydric alcohol is used, the ratio of dihydric alcohol to trihydric or higher alcohol is determined by those skilled in the art depending on the desired properties of the polyether. Generally, the amount of these dihydric alcohols is 0 to 99 mol%, preferably 0 to 80 mol%, more preferably 0 to 75 mol%, most preferably 0 to 50 mol%, based on the total amount of all alcohols. %. By changing the amount of trivalent or higher alcohol and diol added during the reaction, a block copolyether such as a diol-terminated polyether can be obtained.

  According to the present invention, a dihydric alcohol can be precondensed to form an oligomer having an OH terminal, and then a trihydric or higher alcohol can be added. Similarly, a multi-branched polymer having a linear block structure can be obtained.

  Monools can also be added to control the OH functionality during or after the conversion of the trihydric or higher alcohol. Such monools may be, for example, linear or branched aliphatic or aromatic monools. These preferably have more than 3, more preferably more than 6 carbon atoms. Monofunctional polyetherols are also suitable as monools. It is preferable to add 50 mol% or less of monool with respect to the total amount of trivalent or higher alcohol.

  A very suitable polyether in the present invention is a reaction of triethylene glycol and pentaerythritol, preferably in a molar ratio range of 1:10 to 10: 1, more preferably 1: 5 to 5: 1, still more preferably. It can be obtained by reaction of a triethylene glycol / pentaerythritol mixture in the range of 1: 2 to 2: 1, especially 1.5: 1 to 1: 1.5, most preferably 1: 1.

  For the purposes of the present invention, the number average molecular weight of this polyether is preferably in the range from 100 g / mol to 5000 g / mol, in particular in the range from 700 g / mol to 1500 g / mol. Its weight average molecular weight is in the range of about 1000 g / mol to 100000 g / mol, in particular in the range of 5000 g / mol to 50000 g / mol.

  These molecular weights can be determined by known methods, and in particular by gel permeation chromatography using a suitable standard reagent.

  Other details of these high functionality polyethers and their formulations are described in WO 2009/101141, the disclosure of which is expressly incorporated by reference.

  In another preferred embodiment of the invention, a glycerol-based high functionality polyether is used as a stabilizer. The production of glycerol-based polyethers is likewise described. For example, US Pat. No. 3,932,532 and DE 10307172 disclose the production of glycerol-based high-functionality polyethers which give oligomeric polyethers with strong alkali catalysts, and WO 2004/074346 describes the modification with monohydric alcohols. Quality is disclosed.

DE 10307172 also describes the weight of glycerol in the presence of an acidic catalyst (eg, HCl, H ₂ SO ₄ , sulfonic acid or H ₃ PO ₄ ) in the absence of water at a temperature of 200 ° C. to 280 ° C. for 5 to 15 hours. Condensation is disclosed.

  EP 141253, DE 44 46 877 and US 5,728,796 disclose the reaction of tri- or higher alcohols in the presence of acetone or epoxy compounds under acidic reaction conditions. The resulting product has a low molecular weight and is modified with alcohol.

  WO 2004/074346 discloses an alkali polycondensation of glycerol followed by reaction of the resulting condensation product with an aliphatic alcohol under acidic conditions. As a result, polyglycerol modified with oil-based alcohol is obtained.

  Multibranched polyglyceryl ethers are also described in DE 199447631 and DE 10211664. The preparation is carried out by a ring opening reaction of glycidol in the presence of a multifunctional starting molecule if necessary.

  In another preferred embodiment of the invention, a high functionality polyether consisting only of trimethylolpropane units and / or a high functionality polyether consisting only of pentaerythritol units and / or copolymers thereof are used as stabilizers. Is done.

  The hyperbranched polyetherol can also be produced by ring-opening polymerization of 1-ethyl-1-hydroxymethyloxetane with a specific catalyst as disclosed in WO00 / 56802, for example. This polymer structure consists only of trimethylolpropane units. Nishikubo et al. , Polymer Journal 2004, 36 (5) 413, a highly branched polyether polyol comprising only pentaerythritol units can be obtained by ring-opening reaction of 3,3-bis (hydroxymethyl) oxetane.

  Chen et. al, J. et al. Poly. Sci. Part A: Polym. Chem. 2002, 40, 1991 describes a synthesis in which 1-ethyl-1-hydroxymethyloxetane and 3,3-bis (hydroxymethyl) oxetane are simultaneously ring-opening polymerized. Thereby, the polyether which consists of a mixture of a trimethylol propane unit and a pentaerythritol unit is obtained.

  In step II), the polyazole is heated to a temperature above 25 ° C., preferably above 50 ° C., more preferably above 100 ° C., preferably in the range from 100 ° C. to 180 ° C., in particular from 120 ° C. It is stabilized by heating to a temperature in the range of 160 ° C., preferably for 5 minutes to 120 minutes, preferably 15 minutes to 100 minutes, more preferably 60 minutes.

  If necessary, the stabilized film may be post-treated in an acid-containing solution for 10 to 60 minutes at a temperature of 20 ° C. to 80 ° C., more preferably at a temperature of 60 ° C.

  The strong acid used in the present invention is a protonic acid, preferably phosphoric acid and / or sulfuric acid.

In this specification, “phosphoric acid” means polyphosphoric acid, phosphonic acid (H ₃ PO ₃ ), orthophosphoric acid (H ₃ PO ₄ ), pyrophosphoric acid (H ₄ P ₂ O ₇ ), triphosphoric acid (H ₅ P). ₃ O ₁₀ ), metaphosphoric acid, derivatives, especially organic derivatives (eg cyclic organic phosphoric acid), and derivatives thereof (eg acid esters). The concentration of this phosphoric acid, in particular the concentration of orthophosphoric acid, is preferably at least 80% by weight, more preferably at least 90% by weight, even more preferably at least 95% by weight, most preferably at least 98% by weight. This concentration value is a value for the effective concentration of acid in the membrane or during hydrolysis.

  This polyazole, in particular the film, may be further doped after stabilization in step II) for adjustment for later use. In this case, the additives mentioned at the beginning can be added, or the above-mentioned strong acid may be further added to adjust the degree of doping. Also, the water present can be removed from this polyazole, in particular from the membrane, for example by concentrating strong acids present. For the stabilization reaction, it is possible to add a mixture of the required catalyst and various qualifying agents from the above group.

  The present invention also provides a membrane comprising at least one mechanically stable polyazole obtained by the method of the present invention.

  The acid-containing polyazole membrane of the present invention obtained from a stabilized, preferably high-molecular-weight polyazole polymer, reacts with the above acid to form an acid-based complex, and thus has proton conductivity even without water. Become. Due to this mechanism, the so-called Grotus conduction mechanism, it can be used in high-temperature fuel cells with a sustained operating temperature of at least 120 ° C., preferably in high-temperature fuel cells with at least 140 ° C., in particular at least 160 ° C. Become. Therefore, the membrane of the present invention can be used as an electrolyte for electrochemical cells, particularly for fuel cells.

  The acid-containing polyazole membranes of the present invention obtained from stabilized, preferably high molecular weight polyazole polymers are characterized by their improved mechanical properties. For example, the modulus of elasticity of the membrane of the present invention is at least 3 MPa, if appropriate at least 4 MPa, preferably at least 5 MPa, more preferably at least 6 MPa, desirably at least 7 MPa, especially at least 8 MPa. Further, the breaking elongation of the film of the present invention is at least 150%, preferably at least 200%, particularly at least 250%.

This tensile strain characteristic is preferably measured with a Zwick Z010 standard tensile tester, and the following method has been found useful. The sample is first cut into small pieces, suitably 1.5 cm wide and 12 cm long. It is preferable to make 2-3 samples, analyze each sample, and average the results. The thickness of the sample is preferably measured at three points (preferably at the start, center, and end of the strip) using a Mitutoyo absolute digimatic thickness gauge, and the average is preferably taken. This measurement is preferably performed as follows. A small piece of the sample is gripped, and the initial force is held at 0.1 N for 1 minute. Then, until the elastic modulus (MPa) is measured, the tensile rate is preferably 5 mm / min, preferably at RT (25 ° C.), and the measurement is automatically performed (automatic measurement by Zwick Software TextExpert (Ver. 11)). ). Thereafter, the measurement is continued until the sample piece is cut at a tensile speed of preferably 30 mm / min. After the measurement is completed, the fracture toughness (kJ / m ² ) and the elongation at break (%) are determined.

  The conductivity of the acid-containing polyazole membrane of the present invention obtained from a stabilized, preferably high molecular weight polyazole polymer is preferably at least 50 mS / cm, more preferably at least 100 mS / cm, in particular at least 150 mS / cm. It is.

  The acid-containing polyazole membrane of the present invention obtained from a stabilized, preferably high molecular weight polyazole polymer, is also characterized by excellent stability when used as a proton conducting membrane in a high temperature operating fuel cell. There is. When operating such a system, particularly when operating a phosphoric acid system, it is necessary to further improve the stability of the acid-containing polyazole film. The membranes of the present invention are characterized by such improved stability and are preferably insoluble in 99% phosphoric acid over a temperature range of 85 ° C to 180 ° C. “Insoluble” means that the swelling does not exceed 300% even in the presence of an excess of acid, and dissolution of the self-supporting film does not occur.

Also, the acid-containing polyazole membranes of the present invention obtained from stabilized, preferably high molecular weight polyazole polymers, have an improved compressibility. The relative decrease in film thickness is typically less than 40% in a 160 ° C., 120 minute Weiser imprint test, and the relative decrease in film thickness of the corresponding unstabilized film under the same conditions is approximately Contrast with 80%. The Weiser imprint test for measuring compressibility is performed as follows as appropriate:
In order to measure the characteristic dent of the film, a film sample having an area of 4.91 cm ² (diameter 2.5 cm) was prepared with a punch and placed on a hot plate having a Kapton film as a base material. A metal die guided by a metal guide with 3 embedded bolts (d = 1 mm) is placed on the membrane sample and the hot plate temperature is 160 ° C. using a Mitutoyo DCIII thickness gauge for 120 minutes. The decrease in thickness of the membrane sample was recorded. The measured thickness was normalized with the initial thickness and plotted against time.

  The stable membrane of the present invention is also characterized by improved long-term stability.

  Other applications include electrolytes for display devices, electrochromic devices or various sensors.

  The present invention also preferably provides the use of the polymer electrolyte membrane of the present invention in a single cell (MEU) for a fuel cell.

  A single cell for a fuel cell has at least one membrane of the present invention and two electrodes, and a proton conducting membrane is sandwiched between them.

  Each of the electrodes has a catalytically active layer and a gas diffusion layer for sending to the reaction gas and the catalytically active layer. This gas diffusion layer is porous so that a reactive gas can pass therethrough.

  The polymer electrolyte membrane of the present invention can be used as an electrolyte membrane. One or both of the catalytically active layers can produce the electrolyte membrane and a precursor for a single cell (MEU). The single cell can also be manufactured by fixing the gas diffusion layer on the precursor.

  The present invention is also a fuel cell having a plurality of single cells (MEU), each single cell having a membrane and two electrodes manufactured by the above method, and a membrane sandwiched between these electrodes. Provide what is being arranged.

  The stabilization of the present invention can also be performed after manufacturing the MEU from the membrane. For this purpose, doping with a film stabilizer is carried out as described above. However, the stabilization reaction in step II) or c) or the activation of the stabilizing component is then carried out in the MEU arranged in a sandwich.

  More preferably, this stabilization is carried out at a temperature in the range from 100 ° C. to 180 ° C., in particular at a temperature in the range from 120 ° C. to 160 ° C. The reaction time is several minutes to several hours depending on the reactivity of the reactants. The stabilization reaction in the MEU can be performed in one or more stages (by changing the temperature).

  Hereinafter, the present invention will be described with reference to some examples, but these do not limit the concept of the present invention.

  Example 1: Preparation of a polyether polyol from pentaerythritol and triethylene glycol

General Method The polymerization was carried out in a 4 l glass flask equipped with a distillation apparatus with stirrer, reflux condenser and vacuum line fitting. A mixture of pentaerythritol, triethylene glycol and catalyst in the amounts shown in Table 2 was placed under vacuum and gradually heated to a pressure of 200-300 mbar with a 180 ° C. oil bath. After reaching the reaction temperature, the reaction mixture was stirred and water was removed with the distillation system. The water removed by distillation was collected in a cooled round bottom flask and weighed, and the conversion was determined as a percentage of the complete conversion theoretically possible.

  The reaction mixture was then allowed to cool under reduced pressure. KOH was added to the reaction solution for neutralization. The mixture was then stripped and cooled.

  Example 2: Production of a polyether polyol from pentaerythritol, triethylene glycol and neopentyl glycol

  Polymerization was carried out in a 4 liter glass flask equipped with a distillation apparatus having a stirrer, reflux condenser and vacuum line fitting. A mixture of pentaerythritol, neopentyl glycol, triethylene glycol and catalyst in the amounts shown in Table 2 was placed under vacuum and gradually heated to a pressure of 200-300 mbar with a 180 ° C. oil bath. After reaching the reaction temperature, the reaction mixture was stirred and water was removed with the distillation system. The water removed by distillation was collected in a cooled round bottom flask and weighed, and the conversion was determined as a percentage of the complete conversion theoretically possible.

  The reaction mixture was then allowed to cool under reduced pressure. KOH was added to the reaction solution for neutralization. The mixture was then stripped and cooled.

  Example 3: Preparation of a polyether polyol from ethoxylated trimethylolpropane and triethylene glycol

  Polymerization was carried out in a 4 liter glass flask equipped with a distillation apparatus having a stirrer, reflux condenser and vacuum line fitting. A mixture of ethoxylated trimethylolpropane, triethylene glycol and catalyst in the amounts shown in Table 2 was placed under vacuum and gradually heated to a pressure of 200-300 mbar with a 180 ° C. oil bath. After reaching the reaction temperature, the reaction mixture was stirred and water was removed with the distillation system. The water removed by distillation was collected in a cooled round bottom flask and the conversion was determined as a percentage of the complete conversion theoretically possible.

  The reaction mixture was then allowed to cool under reduced pressure. KOH was added to the reaction solution for neutralization. The mixture was then stripped and cooled.

  The product of the invention was analyzed by gel permeation chromatography using a refractometer as the detector. The mobile phase used was hexafluoroisopropanol (HFIP). The standard reagent used for molecular weight determination was polymethyl methacrylate (PMMA). The OH number was measured according to DIN 53240.

Example 4: Implementation of stabilization of the present invention (path 1)
Preferably 50% to 85% of a multi-branched polyether, preferably 1-5% by weight (preferably based on pentaerythritol and triethylene glycol, as shown in Table 2) in a 1000 mL Schott Duran glass bottle. About 800 mL of a phosphoric acid solution was prepared.

A standard polyazole film having a thickness of 350 μm (CD114), an A5 size, a phosphoric acid concentration of about 50% by weight, and a polyazole solid content of about 5% by weight is added to the H ₃ PO ₄ solution to give 1-5 wt. Heated to 60 ° C. with% of the above multi-branched polyether. The residence time in this solution is 1 hour. The membrane was then removed from the solution and treated between the two support materials, preferably in a 120-160 ° C. oven for 1 hour. After stabilization, the membrane was placed in 50% phosphoric acid, preferably for 15-30 minutes.

Example 4a): Implementation of the stabilization of the present invention (path 2.1)
Preferably 1 to 5% by weight of a multi-branched polyether (preferably relative to pentaerythritol and triethylene glycol as shown in Table 2), preferably 2.0 to 2.5% by weight. Add to a solution of high molecular weight polyazole and preferably 99-103% phosphoric acid and heat the mixture, preferably at 80-120 ° C., with stirring for 1 hour.

  Next, using this reaction solution, a coating knife is used to obtain a film having a thickness of about 350 μm. The membrane is treated between two support materials, preferably in a 120-160 ° C. oven for 1 hour. After stabilization, the membrane is preferably placed in 50% phosphoric acid for 15-30 minutes.

Example 4b): Implementation of the stabilization of the present invention (path 2.2)
Preferably 1-5% by weight of a hyperbranched polyether (preferably based on pentaerythritol and triethylene glycol as shown in Table 2), preferably 2.0-2.5% by weight. Add to a solution of high molecular weight polyazole and preferably 99-103% phosphoric acid and heat the mixture, preferably at 80-120 ° C. with stirring for 1 hour.

  Next, using this reaction solution, a film having a thickness of about 350 μm is obtained using a coating knife. The membrane is placed in 50% phosphoric acid, preferably for 15-30 minutes. The membrane is then removed from the solution and treated between the two support materials, preferably in an oven at 120-160 ° C. for 30 minutes.

The stirring temperature was 80 ° C. and the oven temperature was 160 ° C. Using 1% by weight of 3, the following performance is obtained by route 2.2:
Insolubility of membranes in 99% phosphoric acid at −160 ° C. Proton conductivity at 160 ° C .: 196.4 mS / cm
-Elastic modulus: 3.5 MPa
-Compression ratio: relative decrease in film thickness at 160 ° C: <30% after 120 minutes (Weiser imprint test)
The oven temperature was 160 ° C., and the multibranched polyether No. 1 in Table 1 was used. For use in 85% phosphoric acid at 1% by weight of 2, route 1 provides the following performance:
-Insolubility of membrane in 99% phosphoric acid at -160 ° C-Elastic modulus: 29 MPa
-Compression ratio: relative decrease in film thickness at 160 ° C: <30% after 120 minutes (Weiser imprint test)
The stirring temperature was 80 ° C., the oven temperature was 160 ° C., and the multibranched polyether No. 1 in Table 1 was used. Using 5% by weight of 5, the following performance is obtained by route 1:
-Insolubility of membrane in 99% phosphoric acid at -160 ° C-Elastic modulus: 26 MPa
-Compression ratio: relative decrease in film thickness at 160 ° C: <30% after 120 minutes (Weiser imprint test)
For comparison: unstabilized polyazole-phosphate membrane:
Solubility of membranes in 99% phosphoric acid at −160 ° C. Proton conductivity at 160 ° C .: 120 mS / cm
-Elastic modulus: 3.5 MPa
-Compression ratio: relative reduction in film thickness at 160 ° C: about 80% after 120 minutes (Weiser imprint test)

Claims (15)

I) a solution comprising at least one polyazole having at least one amino group in a repeating unit, and (i) at least one strong acid and (ii) at least one stabilizer, wherein the stabilization in this solution The total amount of agent ranges from 0.01 to 30% by weight),
ii) a mechanically stable polyazole comprising a step of performing a stabilization reaction directly and / or in a subsequent processing step using at least one high functionality polyether as a stabilizer and heating to a temperature above 25 ° C. Manufacturing method.   The method of claim 1, wherein the polyazole has a molecular weight (measured as intrinsic viscosity) of at least 1.8 dl / g.   Process according to claim 1 or 2, wherein the solution of step I) comprises at least one strong protic acid, in particular phosphoric acid and / or sulfuric acid based protic acid. The phosphoric acid is polyphosphoric acid, phosphonic acid (H ₃ PO ₃ ), orthophosphoric acid (H ₃ PO ₄ ), pyrophosphoric acid (H ₄ P ₂ O ₇ ), triphosphoric acid (H ₅ P ₃ O ₁₀ ), metalin 4. The method of claim 3, comprising acids and derivatives thereof, in particular organic derivatives (e.g. derivatives such as cyclic organophosphoric acids and acid esters thereof).   The process according to at least one of claims 1 to 4, wherein the polyether is prepared from triethylene glycol and pentaerythritol.   6. A process according to claim 5, wherein the polyether is produced from a triethylene glycol / pentaerythritol mixture having a molar ratio in the range of 1:10 to 10: 1.   The method according to claim 1, wherein the polyether has a number average molecular weight in the range of 100 g / mol to 5000 g / mol.   The method according to claim 1, wherein the polyether has a weight average molecular weight of 1000 g / mol to 100,000 g / mol. a) producing at least one film comprising a polyazole having at least one amino group in the repeating unit; b) producing a film from step a) by (i) at least one strong acid and (ii) at least one stable. Treatment with a solution containing a oxidant (the total amount of stabilizer in the solution is in the range of 0.01 to 30% by weight);
c) directly or in a subsequent film processing step, in the film obtained in step b), heated to a temperature exceeding 25 ° C. to carry out a stabilization reaction;
d) If necessary, the membrane obtained in step c) can be doped with a strong acid using at least one high functionality polyether as stabilizer, or a strong acid present by removing the water present. The method according to at least one of claims 1 to 8, further comprising the step of concentrating. A ′) producing a solution or dispersion of at least one polyazole having at least one amino group in the repeating unit in orthophosphoric acid and / or polyphosphoric acid;
B ′) mixing the solution or dispersion from step A ′) with a solution comprising (i) at least one strong acid and (ii) at least one stabilizer (the total amount of stabilizer in the solution is 0.01 to 30% by weight)
C ′) in the processing step directly and / or downstream, in the solution or dispersion obtained in step B ′) and heated to a temperature of more than 25 ° C., and D ′) if necessary, at least Claims comprising the step of doping the polymer obtained in step C ') with a strong acid using a high functionality polyether as a stabilizer or concentrating the strong acid present by removing the water present. Item 9. The method according to at least one of Items 1-8.   Membrane comprising at least one mechanically stable polyazole obtained by the method of the method according to claim 1.   The membrane of claim 11 having a solubility less than 0.5 wt% polyazole polymer in 99% phosphoric acid over a temperature range of 85C to 120C.   Use of the membrane according to claim 11 or 12 for the manufacture of a membrane electrode unit.   13. A membrane electrode unit comprising at least one membrane according to claim 11 or 12.   A method of using the membrane electrode unit according to claim 14 for the manufacture of a fuel cell.

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