HEAT-SHRINKABLE POLYESTER FILM

摘要

PROBLEM TO BE SOLVED: To suppress the occurrence of the shrinkage irregularity in a hot-air type shrink tunnel by specifying the shrinkage factor at the time of heat and the maximum shrinkage velocity of a heat-shrinkable polyester film in one direction. SOLUTION: The polyester heat-shrinkable film has the shrinkage factor at 80 deg.C in one direction of 8 to 24% or preferably 8 to 35%, and the maximum shrinkage velocity at 100 deg.C of 0.5 to 24%/sec and at 140 deg.C of 10 to 40%/sec. The polyester resin used for the film is preferably resin composition which contains aromatic dicarboxylic acid or its ester forming derivative and polyvalent alcohol component as main ingredients and has glass transition temperature of relatively high value. To obtain the shrinkage factor of relatively low temperature of the polyester resin, it is preferable to contain polyoxytetramethylene glycol having a molecular weight of 300 to 3000 of a range of 1 to 10mol%.