EP1899409A1

EP1899409A1 - Aqueous formulations containing polyaromatic compounds with acid groups

Info

Publication number: EP1899409A1
Application number: EP06777500A
Authority: EP
Inventors: Alexander Khvorost; Gerhard Eugen Wahsner; Sven Thate; Harald BÖHNKE; Dennis LÖSCH
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2005-06-30
Filing date: 2006-06-29
Publication date: 2008-03-19
Also published as: NO20076664L; CA2613190A1; CN101233174A; TW200706557A; WO2007003568A1; JP2008545030A; DE102005030970A1; US7776957B2; KR20080030634A; US20080214719A1

Abstract

The invention relates to the following: a method for production of aqueous formulations (A) containing at least one polyaromatic particularly sulphonated compound with acid groups and aqueous formulations (A), produced by said method; a method for production of dried formulations (B) by removal of the water from aqueous formulations (A) and the dried formulation (B) itself; a formulation (C), comprising said dried formulation (B) and water or the formulation (A) and a water-containing formulation (D) containing the aqueous formulation (A) or the formulation (C) and in addition at least 2 wt. % of an organic solvent; a dry formulation (E), obtained by removal of water and solvent from the aqueous formulation (D); the use of aqueous formulation (D) and the dry formulation (E) obtained therefrom for the production of a polymer electrolyte membrane itself and a membrane/electrode unit (MEA) and a fuel cell comprising said polymer electrolyte membrane.

Description

Aqueous formulations containing polyaromatic compounds bearing acid groups

description

The present invention relates to a process for the preparation of aqueous formulations (A) comprising at least one acid group-carrying, in particular sulfonated, polyaromatic compound and aqueous formulations (A), which are prepared according to the inventive method. Furthermore, the present invention relates to a process for preparing dried formulations (B) by removing the water from the aqueous formulations (A) and the dried formulations (B) themselves. Furthermore, the present invention relates to a formulation (C) comprising the dried formulation according to the invention (B) and water and a water-containing formulation (D) comprising the novel aqueous formulation (A) or the inventive formulation (C) and additionally at least 2 wt .-% of an organic solvent. Furthermore, the present invention relates to dry formulations (E) which are obtained by removal of water and solvent from the aqueous formulations (D) according to the invention. The present invention further provides for the use of the water-containing formulations (D) according to the invention and of the dry formulations (E) obtained therefrom for producing a polymer electrolyte membrane and the polymer electrolyte membrane itself and a membrane-electrode assembly (MEA), and a fuel cell comprising the inventive polymer electrolyte membrane.

Functionalized, especially sulfonated, polyaromatic compounds and their use are known in the art. For example, in fuel cell technology, functionalized polyaromatic compounds are used as or in polymer electrolyte membranes. Furthermore, sulfonated polyaromatic compounds can be used in electrolytic cells, for example chloroalkali cells, as well as in or as catalysts for numerous chemical reactions and in processes such as inverse osmosis or ultrafiltration.

Polymer electrolyte membranes prepared from the acid group-bearing, in particular sulfonated, polyaromatic compounds are generally prepared by dissolving the polyaromatic compounds bearing acid groups in an organic solvent such as DMAc (N, N-dimethylacetamide), DMF (dimethylformamide), DMSO (dimethylsulfoxide ) or NMP (N-methylpyrrolidone) and subsequent precipitation or removal of the solvent. The disadvantage is that the said solvents are expensive and have high boiling points, so that their removal is difficult. For reasons of cost reduction, environmental protection as well as for occupational hygiene reasons, it would therefore be desirable to enable the processing of polyaromatic compounds bearing acid groups in aqueous solutions. Another reason for this is that especially in the field of the production of noble metal catalyst materials, the use of heteroatom-containing, in particular chlorine-, sulfur- and nitrogen-containing solvents should be avoided or minimized, since these can act as catalyst poisons. Therefore, for example, for the preparation of gas diffusion electrodes for fuel cells or electrolysis units or for the production of membrane electrode assemblies (MEA) for fuel cells, aqueous formulations of acid group-bearing polyaromatic compounds are of interest.

The problem with the preparation of aqueous formulations of polyaromatic compounds bearing acid groups is their solubility, especially when polyaromatic compounds bearing acid groups are used which have a low or medium number of acid groups, since such polyaromatic compounds bearing acid groups are particularly difficult to dissolve in aqueous solvents.

WO 98/55534 discloses a process for the preparation of aqueous, aqueous and nonaqueous solutions of polymers functionalized with acid groups, the heat required for the preparation of the solution being supplied by microwave radiation. The solutions serve as starting material for the production of gas diffusion electrodes, fuel cells and polymer electrolyte stabilized platinum nanoparticles. The polymers functionalized with acid groups are, for example, sulfonated polyether ketones (PEK), polyether ether ketones (PEEK) and polyether ether ketone ketones (PEEKK).

Since irradiation with microwaves is complicated and a corresponding apparatus is not readily available for irradiation, it is desirable to provide aqueous and water-containing formulations containing polyaromatic compounds bearing acid groups, without requiring microwave irradiation. It is desirable that the aqueous and aqueous formulations have the highest possible solids content (content of polyaromatic compounds bearing acid groups). This object is achieved by a process for producing a formulation comprising at least one polyaromatic compound bearing acid groups, comprising the step (i):

(i) contacting the at least one acid group-carrying polyaromatic compound with water at a temperature of 120 to 280 ° C, preferably 150 to 200 ° C, more preferably 170 to 200 ⁰ C in a closed reactor, wherein an aqueous formulation A is obtained.

With the aid of the process according to the invention, aqueous formulations A of polyaromatic compounds bearing acid groups can be obtained which have high solids contents. The aqueous formulations A are generally solutions or dispersions of at least one polyaromatic compound bearing acid groups.

For the purposes of the present application, the term "water" means water, preferably tap water, with the quantities of impurities customary for tap water It is likewise possible, for example, to use partially or fully demineralized water The addition of further components such as salts and emulsifiers can be carried out, but not in a preferred embodiment of the method according to the invention.

For the purposes of the present application, "acid groups" are preferably sulfonic, phosphoric, carboxyl and / or boric acid groups, sulfonic acid groups being particularly preferred.

The proportion of acid groups in the polyaromatic compounds is generally from 0.5 to 2 mmol of acid groups per g of polyaromatic compound (ion exchange capacity, IEC), preferably from 1 to 1.8 mmol of acid groups per g of polyaromatic compound.

For the purposes of the present application, "polyaromatic compound" is to be understood as meaning a polymer which has a plurality of arylene groups within the polymer chain, preferably a plurality of phenylene groups. In US 2002/0091225, WO 2005/049696, WO 2005/050671, JP2004-345997, US 2004/0149965, EP-A-1 479 714 and EP-A 1 465 277. The term "polyaromatic compound" is to be understood as meaning a compound selected from the group consisting of polyethers, polyketones, polyaryletherketones, polythioetherketones, polyarylsulphones, polyethersulphones, polythioethersulphones, polyphenylenesulphides, polysulphones, particularly preferably the "polyaromatic compound" selected from polyaryletherketones, Polyarylsulfones, polyethersulfones, polyphenylene sulfides and polysulfones. Very particular preference is given to polyaryl ether ketones.

The polyaromatic compounds may carry the acid groups on their aromatic nuclei or on side chains. The side chains are, for example, aryl, alkyl, alkylaryl, arylalkyl, alkenylaryl, arylalkenyl or alkenyl groups which are substituted by the acid groups. The side chains can be linked to each atom of the polymer backbone. Preferably, they are linked to the aromatic nuclei of the polyaromatic compounds. Suitable examples are:

wherein

X = acid group

A = CR ₂ , NR, S, O

B = CR, N

R = substituted or unsubstituted alkyl or substituted or unsubstituted aryl n = 0 to 10.

The examples are for illustrative purposes only. It is known to those skilled in the art that numerous further linkages of the acid groups with the polyaromatic compounds are possible, which are encompassed by the disclosure of the present application. The preparation of polyaromatic compounds bearing acid groups is carried out by methods known to those skilled in the art.

Particularly preferably, the polyaromatic compounds bearing acid groups are sulfonated polyaryl ether ketones.

Suitable sulfonated polyaryl ether ketones are all known sulfonated polyaryl ether ketones. These are generally obtained by sulfonation of the corresponding polyaryl ether ketones. Suitable sulfonation processes are known to the person skilled in the art and are disclosed inter alia in EP-A 0 008 895, WO 03/03198, DE-A 3402471, DE-A 3321860, EP-A 0 574 791, EP-A 815 159 and WO 2004/076530 , The polyaryletherketones are commercially available or can be prepared by methods known to those skilled in the art.

The sulfonated polyaryl ether ketones are preferably selected from the group consisting of sulfonated polyether ketones (sPEK), sulfonated polyether ether ketones (sPEEK), sulfonated polyether ketone ketones (sPEKK) and sulfonated polyether ether ketone ketones (sPEEKK).

The degree of sulfonation of the sulfonated polyaryl ether ketones used according to the invention is generally from 10 to 90%, preferably from 20 to 80%, particularly preferably from 30 to 60%, very particularly preferably from 35 to 55%. Suitable processes for the preparation of sulfonated polyaryl ether ketones having the stated degrees of sulfonation are mentioned in the abovementioned documents.

In the process according to the invention, formulations are preferably prepared which contain polyaromatic compounds which carry 1 to 5 acid groups, polyaromatic compounds which preferably carry 1 or 2 acid groups, and particularly preferably polyaromatic compounds which carry 1 acid groups.

In addition to the polyaromatic compound bearing at least one acid group, the formulations according to the present application may contain other polymeric compounds, in particular acid-bearing polymeric compounds which are not aromatic, e.g. As sulfonated tetrafluoroethylene polymers such as Nafion ® included. It is z. For example, it is possible for the formulations A to be prepared by jointly dissolving the polyaromatic compound bearing at least one acid group with the further polymeric compound in step I). Step i) contacting the polyaromatic compound bearing at least one acid group with water

For the preparation of aqueous formulations A comprising at least one polyaromatic compound bearing acid groups, the polyaromatic compound carrying at least one acid group is brought into contact with water according to the process of the invention.

Step i) is carried out at a temperature of 120 to 280 ^° C., preferably 150 to 200 ^° C., particularly preferably 170 to 200 ^° C. If temperatures higher than those mentioned are used, decomposition of the polyaromatic compounds bearing acid groups occurs. At lower than the temperatures mentioned, the polyaromatic compounds carrying acid groups do not go into solution or only slightly dissolve.

Step i) is carried out in a closed reactor which is pressure-stable. Suitable reactors are known to the person skilled in the art. For example, step (i) is carried out in an autoclave. Thus, step (i) takes place at a pressure which corresponds at least to the autogenous pressure formed at said temperatures.

Aqueous formulations A are obtained with the aid of the process according to the invention, the polyaromatic compound containing at least one acid group being present unchanged by analysis by means of gel permeation chromatography (eluent: DMAc (+ LiBr), detector: differential refractometer ERC7515A), that is, no change the molecular weight of the acid group-carrying polyaromatic compound is carried out.

The aqueous formulation A obtained according to the process according to the invention in step (i) has a high content of the at least one polyaromatic compound bearing acid groups. This is generally 1 to 25 wt .-%, preferably 5 to 25 wt .-%, particularly preferably 10 to 20 wt .-%, most preferably 15 to 20 wt .-%, wherein the sum of the at least one acid groups carrying polyaromatic compound and water gives 100 wt .-%. In this case, the polyaromatic compound carrying at least one acid group is dissolved or dispersed in the aqueous formulation A. With the aid of the method according to the invention it is thus possible to achieve higher solids contents than hitherto possible with the aid of methods according to the prior art. The aqueous formulations according to the invention thus generally contain from 1 to 25% by weight, preferably from 5 to 25% by weight, particularly preferably from 10 to 20% by weight, very particularly preferably from 15 to 20% by weight of at least one acid group. the polyaromatic compound and generally 75 to 99 wt .-%, preferably 75 to 95 wt .-%, particularly preferably 80 to 90 wt .-%, most preferably 80 to 85 wt .-% water, wherein the sum of the at least one polyaromatic compound bearing acid groups and water is 100% by weight.

The novel aqueous formulation A, which generally has a content of polyaromatic compounds bearing acid groups of from 1 to 25% by weight, has a significantly lower viscosity than formulations of sulfonated polyaryl ether ketones with the same amount of sulfonated polyaryl ether ketone in organic solvents such as DMSO (dimethyl sulfoxide ), DMAc (N, N-dimethylacetamide), DMF (dimethylformamide) or NMP (N-methylpyrrolidone). Furthermore, the aqueous formulations A according to the present invention have the advantage over organic formulations that water has a lower boiling point than said organic solvents and is also non-toxic.

The aqueous formulations obtained in step i) can subsequently be further treated in step (ii).

Step H) Removal of the water

In a further step, step ii), the water can be removed from the formulation A obtained in step i). In this case, a dried formulation B is obtained.

The removal of the water from the aqueous formulations may be accomplished by any method known to those skilled in the art. For example, a removal of the water by applying a vacuum and optionally gentle heating or spray drying is possible.

The dried formulation B obtained in step ii), which contains the at least one polyaromatic compound bearing acid groups, is very soluble in water even at room temperature. This is surprising since the polyaromatic compounds bearing acid groups used in step i) are generally water-insoluble. A change in the molecular weights of the acid group-bearing polyaromatic compounds has not occurred according to analysis by gel permeation chromatography. Without being bound to it, one reason for the good could be Water Solubility of the Dried Formulations B A process carried out by the process carried out in step i) was changed morphology of the polyaromatic compounds bearing acid groups. This means that the aqueous formulations A produced according to the process according to the invention in step i) comprise at least one polyaromatic compound bearing acid groups and the dried formulations B prepared according to steps i) and ii) containing at least one polyaromatic compound of im The prior art discloses aqueous or dried formulations containing at least one polyaromatic compound bearing acid groups.

Another object of the present application is therefore an aqueous formulation A prepared according to the inventive method comprising step i). Another object of the present application is a dried formulation B prepared according to the inventive method comprising the steps i) and ii). Suitable process conditions and preferably used components of the formulations are already mentioned above.

The dried formulations B according to the invention can be processed further in various ways.

On the one hand, it is possible with the aid of the dried formulations according to the invention to prepare aqueous formulations which have an even higher proportion of fatty substances in dissolved or dispersed polyaromatic compounds having acid groups than the aqueous formulations obtained in step i) according to the process of the invention. This is effected by adding water to the dried formulation B according to the invention. By dissolving the dried formulation B according to the invention in water, aqueous formulations are obtainable which have a content of the at least one sulfonated polyaryl ether ketone of up to 25% by weight, based on the sum of dried Formulation B and water.

A further subject of the present application is therefore a formulation C containing

a) a dried formulation B according to the invention, and b) water or an aqueous formulation A according to the invention.

The above inventive formulation C preferably contains from 1 to 75% by weight, particularly preferably from 7 to 25% by weight, very particularly preferably from 10 to 20 % By weight of the polyaromatic compound bearing at least one acid group, based on the sum of the dried formulation B and water or aqueous formulation A.

The polyaromatic compound bearing at least one acid group may be derived from the dried formulation or from the dried formulation B and the aqueous formulation A.

Thus, a formulation C is particularly preferred

a) 1 to 25 wt .-%, preferably 5 to 25 wt .-%, particularly preferably 10 to 25 wt .-%, most preferably 15 to 20 wt .-% of a dried formulation according to the invention B, and b) 75 bis 99 wt .-%, preferably 75 to 95 wt .-%, particularly preferably 75 to 90 wt .-%, most preferably 80 to 85 wt .-% water,

wherein the sum of the dried formulation B and water gives 100 wt .-%.

Another preferred embodiment relates to a formulation C containing

a) 75 to 99 wt .-%, preferably 85 to 90 wt .-% of a dried formulation of the invention B, and

b) 1 to 25 wt .-%, preferably 10 to 15 wt .-% of a dried formulation according to the invention A.

In addition to aqueous formulations (formulations A and C) containing at least one polyaromatic compound bearing acid groups and water, aqueous formulations of interest which additionally contain an organic solvent are of interest. Suitable organic solvents are, for example, NMP (N-methylpyrrolidone), DMAc (N, N-dimethylacetamide), DMF (dimethylformamide), DMSO (dimethylsulfoxide), alcohols (for example methanol, ethanol, propanol, dialcohols such as ethylene glycol, Trialcohols such as glycerol) or mixtures thereof. The ratio of water to the organic solvent is generally 93: 2 to 30: 70, preferably 85: 5 to 50: 50, particularly preferably 75: 5 to 65: 20.

A further subject of the present application are therefore water-containing formulations D containing (A) an aqueous formulation A according to the invention, as obtained by means of a process according to step i), or a formulation C according to the invention as obtained by adding water or an aqueous formulation A according to the invention to the dried formulation B according to the invention, and

b) at least 2 wt .-%, based on the total amount of the formulation of an organic solvent.

Suitable organic solvents are already mentioned above. The proportion of the organic solvent in the aqueous formulation is generally at least 2 wt .-%, preferably 5 to 25 wt .-%, particularly preferably 7 to 15 wt .-%, based on the total amount of the aqueous formulation.

The water-containing formulation D according to the invention is obtained by adding at least 2% by weight, based on the total amount of the formulation, of an organic solvent to the aqueous formulation A according to the invention, as obtained in step i) of the process according to the invention, or to the formulation according to the invention C containing the dried formulation B according to the invention and water or the aqueous formulation A according to the invention. Suitable organic solvents and suitable amounts of the solvents are already mentioned above.

The polyaromatic compound bearing acid groups is present in the water-containing formulations D according to the invention in solution or in the form of a dispersion.

The water-containing formulations D according to the invention can not be prepared by dissolving polyaromatic compounds bearing acid groups in a mixture of water and solvent, owing to the water insolubility of the polyaromatic compounds bearing acid groups.

It has surprisingly been found that drying a water-containing formulation D according to the invention with a content of organic solvents of> 2% by weight gives a water-insoluble residue. The advantage of such a water-insoluble residue is that, based on the water-containing formulations D according to the invention, it is possible to prepare water-insoluble membranes containing polyaromatic compounds bearing acid groups. Such membranes are suitable, for example, for applications in fuel and electrolysis cells. In a membrane preparation starting from the water-containing formulations D according to the invention, a faster drying at low temperatures can be carried out since the boiling point of water is significantly lower than the boiling point of the organic solvents used in membrane production starting from acid groups-carrying polyaromatic compounds according to the prior art the technique can be used. Furthermore, the residual content of the organic solvent in the membranes can be adjusted in a controlled manner starting from aqueous formulations according to the invention. Furthermore, the aqueous formulations according to the invention have a low viscosity, which facilitates filtration during membrane production. Furthermore, higher solids contents can be achieved with the water-containing formulations D according to the invention.

A further subject of the present application is therefore a process for the preparation of a dry formulation E comprising at least one polyaromatic compound bearing acid groups by drying the water-containing formulation D according to the invention.

Suitable drying processes are known to the person skilled in the art, for example drying can be carried out by applying a vacuum at optionally elevated temperatures or by spray-drying.

Another object of the present application is a dry formulation E prepared according to the inventive method mentioned above.

As already mentioned above, the dry formulation E, which is prepared from a water-containing formulation D with a content of solvent of at least 2 wt .-%, has the advantage that it is water-insoluble and thus for the production of membranes for fuel and Electrolysis cells can be used. Advantages of membrane preparation starting from the aqueous formulation D have already been mentioned above.

Starting from the water-containing formulation D, water-insoluble membranes can thus be prepared.

The dry formulation E may additionally contain at least one further polymer and / or further inorganic and / or organic compounds, which may be solid or liquid, which may be added before or after drying of the water-containing formulation D. This involves mixing the dry formulation E with the other polymers and / or the inorganic and / or organic compounds conceivable. It is also conceivable to deposit the further polymers in the form of a film on a membrane which was prepared starting from the water-containing formulation D.

Suitable further polymers are, for example, thermoplastic polymers, preferably polyethersulfones and polysulfones.

Another object of the present application are therefore dry formulations E, which additionally contain at least one further polymer, preferably at least one polyethersulfone and / or polysulfone, particularly preferably at least one polyether sulfone, and optionally further inorganic and / or organic compounds.

The weight ratio between the at least one polyaryletherketone of the dry formulation and the at least one further polymer is generally from 1: 99 to 99: 1, preferably from 2: 1 to 20: 1.

The inorganic and / or organic compounds which are suitable as further constituents are generally low molecular weight or polymeric solids, which, for example, may be capable of absorbing or releasing protons.

Among these compounds capable of accepting or releasing protons are, for example:

Phyllosilicates such as bentonites, montmorillonites, serpentine, kalinite, talc, pyrophyllite, mica. For further details, reference is made to Hollemann-Wiberg, Lehrbuch der Anorganischen Chemie, 91st - 100th Edition, p. 771 ff (2001).

Aluminosilicates such as zeolites.

Non-water-soluble organic carboxylic acids, for example those containing from 5 to 30, preferably from 8 to 22, more preferably from 12 to 18 carbon atoms, having a linear or branched alkyl radical which may optionally have one or more further functional groups, particularly hydroxyl groups being used as functional groups, CC double bonds or carbonyl groups are mentioned. Examples which may be mentioned are the following carboxylic acids: valeric acid, isovaleric acid, 2-methylbutyric acid, pivalic acid, caproic acid, önanthic acid, caprylic acid, pelgonic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, melissinic acid, tubercolostearic acid, palmitoleic acid, oleic acid, erucic acid, sorbic acid, Linoleic acid, linolenic acid, elaeostearic acid, arachidonic acid, culpanodonic acid and docosahexanoic acid or mixtures of two or more thereof.

Polyphosphoric acids, as described, for example, in Hollemann-Wiberg, loc. Cit., P. 659 et seq.

Mixtures of two or more of the above solids.

Likewise, another, preferably non-functionalized polymer can be added. In the context of the present invention, the term "non-functionalized polymer" is understood as meaning polymers which contain neither perfluorinated and sulfonated (ionomeric) polymers, such as Nafion® or Flemion®, for example, to obtain sufficient proton conductivity with suitable groups, for example -SO ₃ H groups or -COOH groups are functionalized polymers. With respect to these non-functionalized polymers useful in the present invention, there are no particular limitations as long as they are stable within the fields of application in which the polymer systems of the present invention are used. According to a preferred use of these used in fuel cells, as are polymers to be used, up to 100 ⁰ C and preferably up to 200 ⁰ C or higher are thermally stable, and a possible liehst high chemical stability. Preferably used are:

Aromatic backbone polymers such as polyimides, polysulfones, polyethersulfones such as Ultrason®, polybenzimidazoles.

Fluorinated backbone polymers such as Teflon® or PVDF. - Thermoplastic polymers or copolymers such as polycarbonates such as polyethylene carbonate, polypropylene carbonate, polybutadiene carbonate or polyvinylidene carbonate or polyurethanes, as described inter alia in WO 98/44576.

Crosslinked polyvinyl alcohols Vinyl polymers such as

Polymers and copolymers of styrene or methylstyrene, vinyl chloride, acrylonitrile, methacrylonitrile, N-methylpyrrolidone, N-vinylimidazole, vinyl acetate, vinylidene fluoride.

Copolymers of vinyl chloride and vinylidene chloride, vinyl chloride and acrylonitrile, vinylidene fluoride and hexafluoropropylene.

Terpolymers of vinylidene fluoride and hexafluoropropylene and a compound selected from the group consisting of vinyl fluoride, tetrafluoroethylene and trifluoroethylene.

Such polymers are disclosed, for example, in US Pat. No. 5,540,741, the relevant disclosure of which is incorporated in the context of the present application in its entirety. Phenol-formaldehyde resins, polytrifluorostyrene, poly-2,6-diphenyl-1,4-phenylene oxide, polyaryl ether sulfones, polyarylene ether sulfones, phosphonated poly-2,6-dimethyl-1,4-phenylene oxide. Homopolymers, block copolymers and copolymers prepared from:

Olefinic hydrocarbons such as ethylene, propylene, butylene, isobutene, propene, hexene or higher homologues, butadiene,

Cyclopentene, cyclohexene, norbornene, vinylcyclohexane. Acrylic acid or methacrylic acid esters such as methyl, ethyl, - propyl, isopropyl, butyl, isobutyl, hexyl, octyl, decyl, dodecyl, 2-ethylhexyl, cyclohexyl, benzyl, trifluoromethyl, or Hexafluoropropyl ester or tetrafluoropropyl acrylate or tetrafluoropropyl methacrylate.

Vinyl ethers such as methyl, ethyl, - propyl, isopropyl, butyl, isobutyl, hexyl, octyl, decyl, dodecyl, 2-ethyl hexyl, cyclohexyl, benzyl, trifluoromethyl, or hexafluoropropyl - or tetrafluoropropyl vinyl ether.

All of these non-functionalized polymers can be used in principle in crosslinked or uncrosslinked form.

The formulations according to the invention are suitable for numerous applications known to the person skilled in the art. It is essential that with the aid of the inventive are accessible to formulations which can be used as ion-exchanging polymer systems, for example in fuel cells, for example as ionomer or polymer electrolyte membrane, for example in membrane-electrode assemblies (MEA).

A further subject of the present invention is therefore the use of a dry formulation E according to the invention as an ionomer or polymer electrolyte membrane as well as ionomers or polymer electrolyte membranes prepared from the dry formulation E according to the invention or the water-containing formulation D according to the invention. It is likewise possible to use the formulations A, B according to the invention , C and D for the preparation of ionomer formulations or polymer electrolyte membranes, optionally after further treatment of the formulations.

In principle, the preparation of the polymer electrolyte membrane according to the invention can be carried out according to all suitable methods known to the person skilled in the art. The preparation of the polymer electrolyte membrane according to the invention is preferably carried out by preparing a casting solution or casting dispersion comprising at least one polyaromatic compound bearing acid groups. The casting solution can be the water-containing formulation D according to the invention or the dry formulation E according to the invention, dissolved in at least one of the abovementioned solvents. The casting solution or casting dispersion is applied to a suitable support, for example by spreading the casting solution or dispersion with a doctor blade. Suitable carriers are, for example, a glass plate or PET film. It is also possible to apply the casting solution or casting dispersion, for example by dipping, spin coating, roll coating, spray coating, printing and letterpress, gravure, flat or screen printing processes or by extrusion, if necessary, to a carrier material. The further work-up can be carried out in a customary manner, for example by removing the solvent or the mixture of water with a suitable solvent by drying at room temperature or elevated temperature, if appropriate under reduced pressure. It is likewise possible to prepare polymer electrolyte membranes in such a way that the solvent or mixture of solvent and water is evaporated off to a solids concentration of 50 to 99% by weight according to processes known to the person skilled in the art and the membrane is subsequently treated with a precipitating agent according to methods known to the person skilled in the art. which is miscible with the membrane adhering solvent and water, is precipitated. The membrane is then removed from the solvent or mixture in a manner known to those skilled in the art Solvent and water freed. The processes for the preparation of the electrolyte membranes are known to the person skilled in the art and are disclosed, for example, in EP-A 0 574 791, DE-A 42 11 266 and DE-A 34 02 471.

Preferably, polymer electrolyte membranes are prepared which have a thickness of 5 to 500 microns, preferably 10 to 500 microns and more preferably 10 to 200 microns (thickness of the dry polymer electrolyte membrane).

Another object of the present application is a composite body containing at least a first layer containing at least one acid group-bearing polyaromatic compound in the form of a dry formulation E according to the invention, and such a composite body, the at least one first layer, the at least one acid group-carrying polyaromatic compound in the form of a dry formulation according to the invention in the form of a membrane and further comprising at least one electrically conductive catalyst layer (Catalyst Coated Membrane, CCM). Suitable CCMs include a catalyst layer, e.g. B. composed of a polymer, preferably a dry formulation E, carbon black and a catalyst, preferably a noble metal catalyst or a catalyst layer, which is prepared by applying so-called catalyst ink to the membrane. Suitable catalyst inks contain z. B. Agglomerates of catalytically active noble metals (such as catalytic platinum or ruthenium agglomerates) and at least one solvent. Suitable solvents are water, alcohols (monohydric or polyhydric alcohols, for example alcohols having one, two or three OH groups), DMAc (N, N-dimethylacetamide), DMF (dimethylformamide), DMSO (dimethylsulfoxide) or NMP (N-methylpyrrolidone ). Preferred catalyst inks are the below-mentioned aqueous catalyst formulations. The catalyst inks can, for. B. by spraying, knife coating or printing and other methods known in the art are applied to the membrane.

Further, in addition to the membrane and the catalyst layer (s), the composite may include one or more gas diffusion layers (GDL), e.g. B. have a carbon mat. The catalyst layer (s) is (are) arranged on the or the gas distribution layer (s), wherein a membrane electrode assembly (MEA) is obtained.

Suitable membrane-electrode assemblies and catalyst-coated membranes and their preparation are known in the art. For example, a suitable MEA is prepared by coating a catalyst ink on a GDL to give a coated GDL. Two coated GDLs are then processed together with a polymer electrolyte membrane interposed between the GDLs to form an MEA, eg by means of a hot pressing process. Preferred catalyst inks and polymer electrolyte membranes are the catalyst inks and polymer electrolyte membranes of the present invention. Suitable processes for the preparation of the MEA are known to the person skilled in the art.

Furthermore, this composite body may comprise one or more bipolar electrodes.

A further subject of the present application is a fuel cell containing at least one polymer electrolyte membrane according to the invention or a composite body according to the invention.

Preferred polyaromatic compounds bearing acid groups have already been mentioned above.

Furthermore, the novel aqueous and aqueous formulations according to the invention can be used for the preparation of catalyst formulations (polymer electrolyte + carbon black + noble metal catalyst, water and optionally solvent, preferably a water-miscible solvent) and for the application of polyaromatic compounds bearing acid groups to membranes and Gas diffusion electrodes are used. An advantage of the formulations according to the invention is that they allow a higher degree of utilization of the noble metal catalyst due to their altered polymer morphology. As a result, a lower loading of the catalyst with noble metal than in the prior art is possible and the production of noble metal catalysts is thus cheaper. Furthermore, when using the water-containing formulations according to the present invention, the dissolution of the membrane can be specifically controlled for better contacting between the membrane and the catalyst layer. Furthermore, the above-mentioned aqueous or hydrous catalyst formulations (catalyst inks) are characterized by a high flammability, which facilitates handling of the pyrophoric catalyst.

In order to achieve a uniform distribution of the particles in the catalyst ink, it is in the preparation of catalyst inks according to the prior art, for. As EP-A 1 503 439, required to use high-boiling solvents and / or dispersants. The use of dispersants in a preparation of the invention appropriate catalyst inks not required. Furthermore, the proportion of high-boiling solvents in the catalyst inks according to the invention can be avoided or at least greatly reduced.

The following examples further illustrate the invention.

example 1

20 g of sPEEK (degree of sulfonation 40%) are mixed with 80 g of water and treated in an autoclave at 180 ° C for 20 minutes. Existing solid is separated from the solution by centrifugation. The yield is 65.4 g of the sPEEK-containing aqueous solution. The degree of sulfonation of the soluble fractions is 40% by weight and the solution has a solids content of 18.1% by weight.

Example 2

17.5 g of sPEEK (degree of sulfonation 55%) are added to 82.5 g of water and treated in an autoclave at 180 ° C for 20 minutes. Existing solid is separated from the solution by centrifugation. The yield is 65 g of the sPEEK-containing aqueous solution. The degree of sulfonation of the soluble components is 55% and the solids content of the solution is 18% by weight.

Claims

claims

A process for the preparation of a formulation comprising at least one polyaromatic compound bearing acid groups, comprising the step (i):

(i) contacting the at least one sulfonated polyaromatic ether ketone with water at a temperature of 120 to 280 ° C in a closed reactor, whereby an aqueous formulation A is obtained.

2. The method according to claim 1, characterized in that the acid group-carrying polyaromatic compound is selected from sulfonic acid, phosphoric acid, carboxyl and / or boric acid-bearing polyaryletherketones, polyarylsulfones, polyethersulfones, polyphenylsulfides and polysulfones.

3. The method according to claim 1 or 2, characterized in that the proportion of acid groups in the polyaromatic compounds is 0.5 to 2 mmol acid groups per g polyaromatic compound.

4. Aqueous formulation A prepared according to a method according to any one of claims 1 to 3.

5. Aqueous formulation A according to claim 4, characterized in that it is 1 to 25 wt .-%, preferably 5 to 25 wt .-%, particularly preferably 10 to 20

Wt .-%, most preferably 15 to 20 wt .-% of at least one acid group-carrying polyaromatic compound and 75 to 99 wt .-%, preferably 75 to 95 wt .-%, particularly preferably 80 to 90 wt .-%, completely particularly preferably 80 to 85 wt .-% water, wherein the sum of the at least one sulfonated polyaryletherketone and water 100 wt .-% results.

6. The method according to any one of claims 1 to 3, characterized in that it additionally comprises the step (ii):

(ii) removing the water from aqueous formulation A obtained in step i) to obtain a dried formulation B.

7. Dried formulation B prepared according to a method according to claim 6.

8. containing formulation C.

a) a dried formulation B according to claim 7, and b) water or an aqueous formulation A according to claim 4 or 5.

9. Formulation C according to claim 8, comprising

a) 1 to 25 wt .-%, preferably 5 to 25 wt .-%, particularly preferably 10 to 25 wt .-%, most preferably 15 to 20 wt .-% of at least one

B) from 75 to 99% by weight, preferably from 75 to 95% by weight, particularly preferably from 75 to 90% by weight, very particularly preferably from 80 to 85% by weight, of water,

the sum of the dried formulation B and water being 100% by weight

% yields, or

a) 1 to 99 wt .-%, preferably 10 to 25 wt .-%, particularly preferably 15 to 20 wt .-% of at least one acid group-carrying polyaromatic

Compound, and b) from 1 to 99% by weight, preferably from 75 to 90% by weight, particularly preferably from 80 to 85% by weight, of an aqueous formulation A according to Claim 4 or 5,

wherein the sum of the dried formulation B and the aqueous formulation A gives 100% by weight.

10. containing water-containing formulation D.

a) an aqueous formulation A according to claim 4 or 5, or a formulation C according to claim 8 or 9, and b) at least 2 wt .-%, based on the total amount of the formulation, of an organic solvent.

11. A water-containing formulation D according to claim 10, characterized in that the organic solvent is selected from the group consisting of N-methylpyrrolidone, N, N-dimethylacetamide, dimethylformamide, dimethyl sulfoxide and mixtures thereof.

12. A process for the preparation of a water-containing formulation D according to claim 10 or 11 by adding at least 2 wt .-%, based on the total amount of the formulation, of an organic solvent to an aqueous formulation A according to claim 4 or 5, or addition of at least 2 weight

%, based on the total amount of the formulation D, of an organic solvent to a formulation C according to claim 8 or 9.

13. A process for preparing a dry formulation E comprising at least one polyaromatic compound bearing acid groups by drying the aqueous formulation D according to claim 10 or 11.

14. Dry formulation E prepared by a process according to claim 13.

15. Dry formulation E according to claim 14 additionally containing at least one further polymer, preferably at least one polyethersulfone and / or at least one polysulfone.

16. Use of a water-containing formulation D according to any one of claims 10 or 11 for the preparation of a polymer electrolyte membrane.

17. A polymer electrolyte membrane prepared from a hydrous formulation according to one of claims 10 or 11.

18. A composite body comprising at least one first layer, the at least one acid group-carrying polyaromatic compound in the form of a dry formulation E according to claim 14 or 15 in the form of a membrane and further at least one electrically conductive catalyst layer.

19. A composite body comprising at least one first layer comprising at least one polyaromatic compound in the form of a dry formulation E as claimed in claim 14 or 15 in the form of a membrane and also at least one electrically conductive catalyst layer and one or more gas distribution layers, the catalyst layer (s) being is (are) arranged on the or the gas distribution layer (s).

20. Fuel cell containing at least one polymer electrolyte membrane according to claim 17 or at least one composite body according to claim 18 or 19.