POLYESTER FILM HAVING IMPROVED TWIST PROPERTY, THERMAL, CHEMICAL, SOLVENT RESISTANCES AND MECHANICAL PROPERTY

摘要

PURPOSE: Provided is polyester film having reduced twist back and twist property, thermal, chemical, solvent resistances and mechanical property useful for manufacturing twist package as apiece package of soft candies such as chocolate, caramel. CONSTITUTION: The polyester film is prepared by extending polyester based sheet with not less than 60 deg.C of glass-transition temperature in one direction at from the glass-transition temperature to higher temperature by 40 deg.C above the glass-transition temperature and thermally fixing the extended sheet at not more than 150 deg.C for 0.1 to 10 seconds after the extension. The polyester film has 50% or less of twist back on at least one direction, 0.03 or more of double refraction rate, and 1.380 or less of specific gravity.