| 摘要 |
The present invention provides a microporous polypropylene film where film formability is improved in accordance with a .beta.-crystal technique which allows microporous films to be continuously manufactured at low cost. In addition, a microporous polypropylene film of which the specific gravity is further reduced is provided. Furthermore, a microporous polypropylene film with a significantly high permeability is provided. In addition, manufacturing methods for these microporous polypropylene films are provided. As for the means for solving the above, a microporous polypropylene film comprising a polypropylene with the Trouton ratio of not less than 30, a microporous polypropylene film with the Trouton ratio of not less than 6, a microporous polypropylene film comprising a polypropylene having a long chain branch in the main chain, a microporous polypropylene film comprising a polypropylene where the relationship between the melt strength (MS) and the melt flow rate (MFR), measured at 230 °C , can be represented by the following formula (1) and/or the melt strength (MS) , measured at 230 °C , is less than 5 cN and the relationship between the MS and the melt flow rate (MFR) can be represented by the following formula (2), or a microporous polypropylene film where the following formula (3) is satisfied in the in-plane intensity distribution profile scanned in the direction of an azimuthal angle for (-113) plane in accordance with X-ray diffraction method, and which has a .beta.-crystal activity and a specific gravity of 0.1 to 0.6 and/or a porosity of 30 % to 95 %. log (MS) > -0.61 log (MFR) + 0.82 (1) log (MS) > -0.9 log (MFR) + 0.6 (2) 0.5 <= I(MD) / I (TD) <= 8 (3) [Here, I (MD) is the integral intensity in the longitudinal direction and I (TD) is the integral intensity in the transverse direction.] |
