| 摘要 |
PURPOSE:To obtain polypropylene film, the heat shrinkage characteristics of which is uniform, with little curling at high temperature and which is suitable for self-adhering tape for food package or the like by a method wherein percentages of heat shrinkage to the direction of a longitudinal stretching axis and to that of a lateral stretching axis, the difference between the percentages of heat shrinkage in diagonal directions, the angle of bowing after heat shrinkage are respectively set within the specified ranges. CONSTITUTION:Percentages of heat shrinkage at 40 deg.C for 15min are respectively set to be 0-4% to the direction of a longitudinal stretching axis and -2-2% to the direction of a lateral stretching axis, the difference between the percentages of heat shrinkage in diagonal directions is set to be 0-6% and, at the same time, the angle of bowing after the heat shrinkage is set to be 0-2 deg. so as to constitute polypropylene film with little high temperature curling. At this time, propylene polymer for constituting the polypropylene film contains not only propylene homopolymer but also polymer between propylene and other polymer or the like. Thus, polypropylene film, the heat shrinkage characteristics of which are uniform and which has little curling at high temperature, especially at 120 deg.C or higher, is obtained. |
