Isamu Sakane: Porous films of polytetrafluoroethylene and process for producing said films. Sumitomo Electric, Sughrue Rothwell Mion Zinn and Macpeak, September 20, 1977: US04049589 (55 worldwide citation)

A porous film of polytetrafluoroethylene having an accurately controlled pore diameter and a superior pore diameter distribution, and a process for preparing the film.