Monomer beads for producing a proton-conducting membrane

Abstract

Monomer beads which can be obtained according to a process in which i. one or more aromatic tetraamino compounds are mixed with one or more aromatic carboxylic acids comprising at least two acid groups per carboxylic acid monomer in an extruder and melted at 190° C.-270° C.; ii. the melt is dropletized at 190° C.-270° C. by means of a die located at the extruder outlet; iii. the liquid droplets are collected, cooled and allowed to solidify. The monomer beads are particularly suited to the production of a proton-conducting polymer membrane based on polyazoles.

1 - 19 . (canceled) 
     
     
         20 . A monomer bead which comprises one or more aromatic tetraamino compounds and one or more aromatic carboxylic acids and can be obtained by
 i. mixing one or more aromatic tetraamino compounds with one or more aromatic carboxylic acids comprising at least two acid groups per carboxylic acid monomer in an extruder and melted at 190° C.-270° C.;   ii. the melt is dropletized at 190° C.-270° C. by means of a die located at the extruder outlet;   iii. collecting, cooling and allowing the liquid droplets to solidify.   
     
     
         21 . The monomer bead according to  claim 20 , wherein the ratio of the amino groups derived from the tetraamino compounds to the carboxylic acid groups derived from the aromatic carboxylic acids is in the range from 2.1:1 to 1.9:1. 
     
     
         22 . The monomer bead according to  claim 20 , wherein the molar proportion of amide groups and/or imide groups based on the total number of all amino groups is less than 1:1. 
     
     
         23 . The monomer bead according to  claim 20 , having a number average degree of polymerization, measured by means of GPC, of less than 10. 
     
     
         24 . A process for producing a proton-conducting polymer membrane based on polyazoles, which comprises the steps
 A) Mixing the monomer beads according to  claim 20  with polyphosphoric acid to form a solution and/or dispersion,   B) Applying a layer to a support using the mixture according to step A),   C) Heating of the sheet-like structure/layer which can be obtained according to step B) to temperatures of up to 350° C., to form the polyazole polymer, and   D) Treating the membrane formed in step C) in the presence of moisture at temperatures and for a time which are sufficient for the membrane to be self-supporting.   
     
     
         25 . The process according to  claim 24 , wherein a polymer comprising recurring benzimidazole units of the formula 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         where n and m are each an integer greater than or equal to 10 is formed in step C). 
       
     
     
         26 . The process according to  claim 24 , wherein the viscosity is adjusted by addition of phosphoric acid after step B) and before step C). 
     
     
         27 . The process according to  claim 24 , wherein the membrane produced according to step C) is treated in the presence of moisture at temperatures and for a time sufficient for the membrane to be self-supporting and be able to be detached without damage from the support. 
     
     
         28 . The process according to  claim 24 , wherein an electrode is selected as support in step B) and the treatment according to step D) is carried out in such a way that the membrane formed is no longer self-supporting. 
     
     
         29 . The monomer bead according to  claim 20 , wherein the average residence time of the mixture of tetraamino compounds and carboxylic acids in the extruder is less than 10 minutes. 
     
     
         30 . The monomer bead according to  claim 20 , wherein the molar proportion of amide groups and/or imide groups based on the total number of all amino groups is less than 0.5:1. 
     
     
         31 . The monomer bead according to  claim 20 , wherein the molar proportion of amide groups and/or imide groups based on the total number of all amino groups is less than 0.33:1. 
     
     
         32 . The monomer bead according to  claim 20 , wherein the molar proportion of amide groups and/or imide groups based on the total number of all amino groups is less than 0.1:1. 
     
     
         33 . The monomer bead according to  claim 20 , having a number average degree of polymerization, measured by means of GPC, of less than 5. 
     
     
         34 . The monomer bead according to  claim 20 , having a number average degree of polymerization, measured by means of GPC, of less than 2. 
     
     
         35 . The monomer bead according to  claim 32 , having a number average degree of polymerization, measured by means of GPC, of less than 2.