A multilayered microfiltration medium exhibiting high particle capture efficiency and minimal flow restriction having a base substrate layer, a fine fiber filtration or efficiency layer deposited on and adhered to the substrate layer and a nonhandleable, non-self-supporting protective cover layer which...http://www.google.com/patents/US4650506?utm_source=gb-gplus-sharePatent US4650506 - Multi-layered microfiltration medium
