SURFACE-TREATMENT OF PLASTIC MATERIAL BY PULSE CORONA INDUCED PLASMA CHEMICAL PROCESS - PPCP

A novel plasma chemical process PPCP (Pulse Corona Induced Plasma Chem ical Process) can produce copious active radicals in air under NTP (No rmal Temperature and Pressure) by using an extremely fast rising narro w high voltage pulse between corona electrodes and grounded counter el ectrodes so that intense streamer coronas are generated. This provides an effective means of surface treatment to a plastic material placed between the two electrodes through generation of free bonds on the sur face directed to the corona electrodes. Special features of this metho d are that it can cope with a complex shape of the material to be trea ted, and that it does not spark even at the periphery near the grounde d counter electrode. This method is suitable for the surface treatment of polypropylene bumpers so as to provide a strong adhesion of color paint to it. The adhesion strength of a paint film is raised from zero to ca. 1000 g/cm2 by PPCP treatment for 60 seconds.