Multi-stage pressing process for producing a molded part such as a bipolar plate from a highly filled thermosetting material

Process for producing a molded part forming a bipolar plate for a fuel cell from a highly filled thermosetting starting material, the process comprising:

• introducing the starting material into a prepressing tool, wherein the highly filled thermosetting starting material contains at least one of graphite and other predominantly carbon-containing compounds as filler in the starting materials with a filler content of at least 70 mass percent and wherein the starting material comprises 2-methylimidazole as a curing catalyst;
• producing a preform from the starting material, wherein the starting material is brought to a prepressing temperature by means of the prepressing tool including a prepressing lower die and a prepressing upper die each having contoured pressing surfaces and is compressed with a prepressing force to form the preform;
• removing the preform from the prepressing tool and introducing the preform into a finish pressing tool;
• and
• producing a finished part from the preform, wherein the preform is brought to a finish pressing temperature by means of the finish pressing tool and is compressed with a finish pressing force to form the finished part;
• wherein the prepressing temperature is lower than the finish pressing temperature;
• wherein the finish pressing temperature is at least as high as an onset temperature of a curing reaction of the starting material;
• and
• wherein the finish pressing force is varied during production of the finished part.