| abstract |
A provided stretched porous polytetrafluoroethylene membrane has an air permeability of 4 cm3/(sec·cm2) or more, as expressed in terms of Frazier air permeability, in a thickness direction, and has a total cohesion of 1.9 (N/20 mm)2 or more, the total cohesion being expressed by a product of a peel cohesion in a first in-plane direction and a peel cohesion in a second in-plane direction perpendicular to the first direction. The above stretched porous membrane is highly air-permeable and, for example, when included in a filter member, being less likely to suffer breakage at the time of handling the member or placing the member on a housing or the like. |