Polytetrafluoroethylene porous film and preparation and use thereof
AssigneeDaikin Industries, Ltd.
InventorsShinji Tanaru, Osamu Tanaka, Hirofumi Nishibayashi, Osamu Inoue, Katsutoshi Yamamoto, Toshio Kusumi
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Abstract
A polytetrafluoroethylene porous film, which is prepared by stretching a semisintered polytetrafluoroethylene material and heating the stretched material at a temperature higher than the melting point of sintered polytetrafluoroethylene, has an area ratio of fibrils to nodes of from 99:1 to 75:25, an average fibril diameter of from 0.05 to 0.2 .mu.m, a largest node area of not larger than 2 .mu.m.sup.2 and an average pore size of from 0.2 to 0.5 .mu.m and achieves low pressure loss.
Claims12
A polytetrafluoroethylene porous film which is prepared by stretching a semisintered polytetrafluoroethylene material and heating the stretched material at a temperature higher than the melting point of sintered polytetrafluoroethylene and has an area ratio of fibrils to nodes of from 99:1 to 75:25, an average fibril diameter of from 0.05 to 0.2 .mu.m and a largest node area of not larger than 2 .mu.m.sup.2 which are determined by an image processing of a scanning electron microscopic photograph, and an average pore size of from 0.2 to 0.5 .mu.m.
A polytetrafluoroethylene porous film having an average pore size of from 0.2 to 0.5 .mu.m, and a pressure loss of from 10 to 100 mmH.sub.2 O when an air is passed through at a flow rate of 5.3 cm/sec.
A polytetrafluoroethylene porous film which is prepared by biaxially stretching a semisintered polytetrafluoroethylene material at an area draw ratio of at least 50 and heat setting the stretched film at a temperature higher than a melting point of sintered polytetrafluoroethylene.
Dependencies are inferred from the claim text.