| 摘要 |
PROBLEM TO BE SOLVED: To reduce the draw down of a film having rigidity, improve the molding precision, and make the thickness thinner by a method wherein a C axis orientation factor in the direction being orthogonal to the flowing direction of a polypropylene film having a specified property, and a surface orientation index are specified. SOLUTION: For a polypropylene film which is used, the mmmm pendant component ratio by<13> C-NMR, is 0.85-0.95. Then, the C axis orientation factor in the direction (TD direction) being orthogonal to the flowing direction of the biaxially drawn polypropylene film, is 0.40-0.60. This C axis orientation factor is a value to quantitatively represent the degree of an axial orientation in the TD direction of the polypropylene crystal C axis, which is obtained by an X-ray diffraction. In the meantime, the surface orientation index of the biaxially drawn polypropylene film, is 0.60-0.80. The surface orientation index is an index to represent the degree of a surface orientation to a surface being in parallel with the film surface of a polypropylene crystal 010 surface, which is obtained by an X-ray diffraction method. |
