| 摘要 |
PROBLEM TO BE SOLVED: To make the distribution of the physical properties of a film in the width direction uniform and eliminate its torsional phenomenon due to thermal treatment or the like after making bags of the film by specifying the difference between the absolute values of boiling water shrinkage factor in two different specified directions of the longitudinal direction at specified positions to the right and the left from the center of the entire width of the film. SOLUTION: The biaxially orientated polypropylene terephthalate film is cut, for example, each in the form of a 21 cm square piece from a position located equivalent to 40% of the entire width to the right/left from the center of the film. Next, a circle with a diameter of 20 cm in the middle of each of the samples as a center, for example, is drawn and further, a straight line which passes through the center of the circle in the directions of 0 deg., 45 deg., 90 deg. and 135 deg. longitudinally is drawn to measure the diameter of each of these directions as lengths before treatment. In addition, these samples are thermally treated in a boiling water, then water sticking to the surfaces of the samples is removed and air-dried, and the diameter in each of the directions is measured as the length after treatment. Further, absolute values of boiling water shrinkage factors in the direction of 45 deg. and in the direction of 135 deg. when the longitudinal direction is set at 0 deg., are sought, so that the difference between these absolute values is 3.5 or less. |
