| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a porous film which possesses important shutdown characteristics in respect of insurance of safety while having an outstanding air permeability characteristic which contributes to an electric performance. <P>SOLUTION: The porous film has a layer which makes a poly 4-methyl-1-pentene polymer based resin composition a principal component in which at least one peak temperature of a loss tangent measured on a frequency of 10 Hz by a dynamic viscoelastic measurement exists at -100 to 20°C, wherein the poly 4-methyl-1-pentene polymer based resin composition is a resin composition including: a component which is a poly 4-methyl-1-pentene based polymer; and as a soft component, a component which is a copolymer of a vinyl aromatic compound and a conjugated diene or a hydrogenated derivative thereof, and the porous film is extended in at least one direction. <P>COPYRIGHT: (C)2012,JPO&INPIT |
