| abstract |
Disclosed is a material capable of forming a PTFE porous film which can readily be stretched biaxially, is capable of uniform stretching even at high stretching ratios, and has low pressure loss. The disclosed polytetrafluoroethylene mixture is of a modified polytetrafluoroethylene having fibrillation properties and a homo-polytetrafluoroethylene, wherein said homo-polytetrafluoroethylene has a breaking strength of 25N or greater. |