| 摘要 |
[Problem] To provide a heat-shrinkable polyester film having adequate heat shrinkage properties in the main direction of shrinkage, which is the longitudinal direction, low heat-shrinkage rate in the widthwise direction perpendicular to the main direction of shrinkage, and high conformability to a container which is the object to be packaged during shrinkage and less tendency to loosen due to not having excessively high shrinkage stress in the main direction of shrinkage and having small attenuation of shrinkage stress. [Solution] A heat-shrinkable polyester film in which the main direction of shrinkage is the longitudinal direction, wherein the heat-shrinkable polyester film is characterized in that (1) the hot-water shrinkage rate of the main direction of shrinkage of the film is 40-80% when treated over a period of 10 seconds in 98°C water, (2) the hot-water shrinkage rate of the direction perpendicular to the main direction of shrinkage of the film is -5%-10% when treated over a period of 10 seconds in 98°C water, (3) for the shrinkage stress of the main direction of shrinkage of the film measured in 90°C hot air, the shrinkage stress ratio shown by the following formula is 0.6-1.0, and (4) the refractive index of the main direction of shrinkage of the film is 1.600 or higher. |
