| 摘要 |
PURPOSE:To improve the tensile strength as well as the surface strength of a porous film or sheet by a method wherein the film, obtained by inflation molding while rotating a rotary die capable of turning a die lip and a core relatively with a specified number of rotation, is stretched into the direction of take-off under a specified condition. CONSTITUTION:Thermoplastic resin compound, consisting of 100 weight parts of thermoplastic resin mixed with 25-400 weight parts of filler and provided with melt index less than 10g/10min, is molded by inflation molding. In this case, an inflation molding device, capable of rotating either one of a die lip or a core through an annular slit or having a movable die lip and core capable of being rotated mutually into opposing directions, is employed while at least one of the movable die lip or the core is rotated with the number of rotation higher than the value of a rotating index S, shown by a formula (I), and lower than the 15 times of the rotating index S to mold a film or a sheet. Then, the obtained film or sheet is stretched into the direction of take-off with the draw ratio of 1.2-8 times. |
