Improvement of Heat Resistance of PFA Film Electret using Silica Agglomerates

Abstract

The silica agglomerates were formed on PFA film by the application of colloidal silica followed by drying to prepared the silica-agglomerates electret. Three methods, inkjet-printing, air-spray and ultrasonic nebulization, were used to apply the colloidal silica on the film. The prepared electrets were heated on a hot plate to investigate the heat resistance. The silica-agglomerates electret showed higher charge retention than the PFA electret over 200℃. The electret on which silica agglomerates were formed by inkjet-printing or air-spray indicated that the charge retention was monotonically increased with the area fraction of silica agglomerates. Furthermore, the prepared electrets were kept under humidity of 60 to 70% to investigate the humidity resistance. The charge retention of the electret n which silica agglomerates were formed by inkjet-printing was not changed while it was gradually decreased when silica agglomerates were formed by ultrasonic nebulization. These results suggested that the application of silica agglomerates was effective method to enhance heat resistance of fluorine resin film.