Inventors:
Kwang C. Chao - Palo Alto CA
Mark C. Porter - Pleasanton CA
Assignee:
Nuclepore Corporation - Pleasanton CA
International Classification:
B29D 2700
Abstract:
A method for forming a microporous sheet of fluorocarbon polymer (e. g. , polytetrafluoroethylene). An aqueous dispersion of polytetrafluoroethylene which includes a dissolved water-soluble, crystallizable metallic organic salt, preferably sodium benzoate, is formed into a sheet. Water is evaporated from an exposed surface of the sheet to grow crystals of the organic salt dispersed throughout the sheet. Then, the sheet is sintered. After cooling, the salt crystals are leached from the sheet by dissolution in water to leave a porous structure suitable for such uses as a filtration membrane or as a separation barrier in batteries or electrolytic cells.