Moulding composition for producing bipolar plates

Abstract

Compositions comprising (a) an epoxy resin, (b) a hardener for the epoxy resin, (c) a product of the reaction of a microgel containing carboxylic acid groups and a nitrogen-containing base, and (d) an electrically conducting filler combination comprising, based on the total amount of filler, at least 75% by weight of graphite, are particularly suitable for producing bipolar plates.

1 . Composition comprising 
 (a) an epoxy resin,    (b) a hardener for the epoxy resin,    (c) a product of the reaction of a microgel containing carboxylic acid groups and a nitrogen-containing base, and    (d) an electrically conducting filler combination comprising, based on the total amount of filler, at least 75% by weight of graphite.    
     
     
         2 . Composition according to  claim 1 , comprising an epoxy phenol novolak or an epoxy cresol novolak as component (a).  
     
     
         3 . Composition according to  claim 1  or  2 , in which the microgel in component (c) is a copolymer of at least one unsaturated carboxylic acid and at least one polyfunctional crosslinker.  
     
     
         4 . Composition according to  claim 3 , in which the unsaturated carboxylic acid is acrylic acid or methacrylic acid.  
     
     
         5 . Composition according to  claim 3 , in which the polyfunctional crosslinker is a polyfunctional acrylate or methacrylate of an aliphatic, cycloaliphatic or aromatic polyol, an addition product of acrylic acid or methacrylic acid and a polyglycidyl compound, an addition product of acrylic acid or methacrylic acid and glycidyl acrylate or methacrylate, an alkenyl acrylate or alkenyl methacrylate, a dialkenylcyclohexane, or a dialkenylbenzene.  
     
     
         6 . Composition according to  claim 3 , in which the polyfunctional crosslinker is selected from ethylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol diacrylate, propylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, polypropylene glycol diacrylate, polypropylene glycol dimethacrylate, 1,1,1-trimethylolpropane triacrylate, 1,1,1-trimethylolpropanetrimethacrylate, bisphenol A diglycidyl ether diacrylate, bisphenol A diglycidyl ether dimethacrylate, allyl acrylate, allyl methacrylate, divinylcyclohexane, and divinylbenzene.  
     
     
         7 . Composition according to  claim 1  or  2 , in which the nitrogen-containing base in component (c) is an amine, a polyamine or an imidazole.  
     
     
         8 . Composition according to  claim 7 , in which the nitrogen-containing base is 2-phenylimidazole, 2-isopropylimidazole, 2-dodecylimidazole, 2-heptadecylimidazole, 2-ethylimidazole, or 2-ethyl-4-methylimidazole.  
     
     
         9 . Composition according to  claim 1 , in which the filler combination (d) comprises graphite powder with an average particle diameter of from 0.1 to 500 μm, preferably from 1 to 300 μm, more preferably from 10 to 250 μm, with particular preference from 50 to 100 μm.  
     
     
         10 . Composition according to  claim 1 , in which the filler combination (d) comprises graphite powder in the form of synthetic graphite.  
     
     
         11 . Composition according to  claim 1 , comprising from 0.1 to 25 parts by weight of component (c), based on 100 parts by weight of component (a).  
     
     
         12 . Composition according to  claim 1 , comprising from 50 to 90% by weight, preferably from 70 to 85% by weight, of component (d), based on the entire composition (a)+(b)+(c)+(d).  
     
     
         13 . Composition according to  claim 1 , also comprising an organosilane.  
     
     
         14 . Electrically conductive material produced by hardening a composition according to  claim 1 .  
     
     
         15 . Use of a composition according to  claim 1  for producing bipolar plates.