To provide a heat-shrinkable polyester film high in shrinkage characteristics in a longitudinal direction which is a main shrinkage direction, high in a mechanical strength in a width direction, also hardly forming a wrinkle on a manufactured film roll and excellent in perforation unsealability.
In the heat-shrinkable polyester film, the main shrinkage direction is provided by a longitudinal direction. In addition, hot-water heat shrinkage ratios in a longitudinal direction at 90C for 10 seconds and a width direction when the film is treated in hot water at 90C for 10 seconds, a maximum heat-shrinkable stress value in a longitudinal direction, and a natural shrinkage ratio after aging at an atmosphere of 40C and 65% RH for 700 hours or longer are controlled in predetermined ranges respectively.
HARUTA MASAYUKI
TAHODA TADASHI
NOSE KATSUHIKO
