The application is directed toward a process for forming an electret filter medium. The process includes the steps of: (1) providing a thin film of a dielectric material; (2) placing the thin film on a pattern anvil having a pattern of raised areas wherein the height of the raised areas is greater than...http://www.google.es/patents/US5370830?utm_source=gb-gplus-sharePatente US5370830 - Hydrosonic process for forming electret filter media
Hydrosonic process for forming electret filter media
