HEAT-SHRINKABLE POLYESTER-BASED FILM AND PACKAGING MATERIAL

摘要

PROBLEM TO BE SOLVED: To provide a heat-shrinkable polyester-based film which has a high thermal shrinkage in the width direction and a low thermal shrinkage in the longitudinal direction and is high in mechanical strength in the longitudinal direction, good in perforation unsealability and excellent in shrinkage finishing.SOLUTION: A heat-shrinkable polyester-based film meets conditions (1) to (4). (1) The warm water thermal shrinkage at 98°C in a film main shrinkage direction is 55-90%; (2) the warm water thermal shrinkage at 98°C in the direction orthogonal to the film main shrinkage direction is -5 to 12%; (3) the difference in specific heat capacity &Dgr;Cbetween before and after Tg is 0.1-0.7 J/(g °C), when the reverse heat flow is measured by a temperature modulation DSC; and (4) the tensile fracture strength in the direction orthogonal to the film main shrinkage direction is 70-150 MPa.