| 摘要 |
Disclosed is a microporous polyproplene film comprising a propylene homopolymer, a copolymer of propylene with other copolymerizable monomer or a blend thereof, which has an intrinsic viscosity ( eta ) of 1.9 to 3.0 dl/g, especially 2.0 to 3.0 dl/g, as measured at 135 DEG C. in tetralin, said microporous film having a network structure comprising intercommunicating pores having a maximum pore size smaller than 1 mu and an average pore size of 0.005 to 0.6 mu and having a porosity of 30 to 90%, an air permeability of 5 to 500 sec/100 cc and a thickness of 5 to 200 mu , said microporous film being molecularly oriented by stretching.
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