| 摘要 |
PURPOSE: To obtain a film excellent not only in elasticity and elastic recovery but also in mechanical strength by specifying an extrusion temp., a frosting line height, longitudinal stretching magnification (RMD) and an RMD/RTD ratio (TRD: lateral stretching magnification) to perform inflation molding. CONSTITUTION: A molten resin extruded from an extrusion die 3 is a butene-1 polymer with a melt index of 0.3-10 G/10 min. The extrusion temp. in film molding, that is, the temp. of the part of the annular slit 4 of the extrusion die 3 is set to 120-250 deg.C, pref., 140-220 deg.C and a frost line height is set to 38-100 cm, pref., 40-80 cm. Further, longitudinal stretching magnification (RMD) is set to 5 or more, pref., 6-20 and the ratio of the longitudinal stretching magnification (RMD) to lateral stretching magnification (RTD), that is, an RMD/RTD ratio is set to 2.5 or more, pref., 3.0-10. By this constitution, a film excellent in elasticity, elastic recovery and mechanical strength such as impact strength or the like can be obtained. |
