Study on parameter optimization of corona charging for melt-blown polypropylene electret nonwoven web used as air filter

The application of melt-blown polypropylene electret nonwoven web used as air filter will mainly depend on its high electret charge storage stability. Corona charging is an important method to provide charges to nonwoven web. In this paper, corona charging apparatus is proposed and same or opposite polarity charging mode is available for melt-blown polypropylene nonwoven web. In addition, parameter optimization of corona charging is studied by means of filtration efficiency measurement with particle count method. The results show that there exists a threshold voltage, about 35 kV for the opposite polarity charging mode and about 30 kV for the same polarity charging mode. When charging voltage is higher than the threshold, the filtration efficiency almost doesn´t increase. Initial filtration efficiency in same polarity charging mode is slightly higher than that in opposite polarity charging mode, but the initial stability of filtration efficiency is better for the opposite polarity charging.