Polymer -: carbon nanotube composites for electrostatic powder painting applications

Two polycarbonate (PC) composite materials with 2 and 5 wt% multiwalled carbon nanotube (MWNT) content were injection moulded to get samples for electrostatic painting experiments using a weather-resisting low temperature curing powder coating. In order to vary the electrical resistivities of the plates injection moulding was done using a two-level, four-factor factorial design which also was used to evaluate the influences of holding pressure, injection velocity, mould temperature, and melt temperature on the electrical surface and volume resistivities. For both composites variations in resistivity of the injection-moulded plates up to six orders of magnitude were found. The highest impact was determined for the injection velocity followed by the melt temperature and the interaction of both. For selected samples, electrostatic painting experiments using a coating based on a polyester resin and uretdione crosslinkers were performed. It could be shown that the all composites independent on theirs surface resistivities showed excellent paintability and adhesion properties of the paint layer.