HEAT-SHRINKABLE POLYESTER FILM AND PACKAGE

摘要

Provided is a heat-shrinkable polyester film that suppresses deterioration of the shrinkage finish property associated with a decline in performance during aging and does not loosen even after being used as a label. This heat-shrinkable polyester film comprising a polyester of a predetermined composition fulfills all of the following: (1) a ratio A1/A2 of the absorbancy (A1) at 1340 cm−1 and the absorbancy (A2) at 1.410 cm−1 of the film measured by polarized ATR-FTIR from 0.45 to 0.75 or from 0.40 to less than 0.45 in either the width direction or longitudinal direction of the film; (2) a ratio (shrinkage stress after 30 seconds/maximum shrinkage stress) of the shrinkage stress after 30 seconds when the film is heat shrunk for 30 seconds in 90° C. hot air (shrinkage stress after 30 seconds) and the maximum shrinkage stress of from 75% to 100%; and (3) a hot-water shrinkage in the width direction of from 30% to 55% when, after aging the film for 672 hours in a 30° C., 85% RH atmosphere, the aged film is dipped in 70° C. water for 10 seconds.

主权项

1. A heat-shrinkable polyester film, having an ethylene terephthalate unit, and containing a constituent unit derived from butanediol in a content of 1 to 25% by mole, a constituent unit derived from ε-caprolactone in a content of 1 to 25% by mole, and a constituent unit derived from one or more monomers capable of forming an amorphous component other than the constituent units derived from butanediol and ε-caprolactone in a content not less than 18% by mole in 100% by mole of the whole polyester resin component, the heat-shrinkable polyester film satisfying the following requirements (1) to (3):
(1) the film has a ratio A1/A2 (absorbancy ratio) of an absorbancy A1 at 1340 cm−1 to an absorbancy A2 at 1410 cm−1 measured by a polarized ATR-FTIR method of not less than 0.45 and not more than 0.75 in either of the width direction and longitudinal direction of the film; (2) the film has a ratio (shrinkage stress after 30 seconds/maximum shrinkage stress) of a shrinkage stress after 30 seconds when the film is heat shrunk in hot air of 90° C. for 30 seconds (shrinkage stress after 30 seconds) to the maximum shrinkage stress of not less than 75% and not more than 100%; and (3) the film has a hot-water heat shrinkage in the width direction of not less than 30% and not more than 55% when the film is aged for 672 hours in an atmosphere of 30° C. and 85% RH, and then the aged film is dipped in hot water of 70° C. for 10 seconds.