| 摘要 |
PURPOSE:To obtain an easily tearable film, in a biaxially oriented polyolefin film, by a method wherein said polyolefin film is constituted from crystalline low molecular polyolefin with critical viscosity of 0.5-12 and the Charpy impact strength of said film in a width direction is adjusted to 0.5-4(kg-cm/cm). CONSTITUTION:Crystalline low molecular polyolefin is melt extruded. In the next step, the obtained molten extrudate is contacted with the surface of a running cooling support to be closely adhered to the contact point and peeled off from the cooling support. The critical viscosity of thus obtained cast film is within a range of 0.5-12. Succeedingly, the cast film is biaxially oriented so as to adjust the orientation magnification thereof to 4.5-10 times in a longitudinal direction and 6-15 times in a width direction and the Charpy impact strength of said film in a width direction is brought to a range of 0.5-4.0(kg-cm/cm). By this method, a film easily tearable by hand is obtained. |
