| 摘要 |
PURPOSE:To obtain a polyester shrinkable film which possesses excellent shrinkage properties and is superior in hot water resistance, weather resistance and heat sealability, by a method wherein a neck-in factor is limited beside limitation in shrinkage factor in either unidirection of a longitudinal and lateral directions of the film. CONSTITUTION:A shrinkage factor within hot water of 75 deg.C for 5 seconds in either unidirection of longitudinal or laterial directions of a film is decided to be 30% or higher, preferably 40% or higher and far preferably 45% or higher. The maximum shrinkage factors (neck-in factors) within the hot water of 75 deg.C for 5 seconds in a shrinking direction and vertical direction to be obtained when both end parts of the film in a main shrinking direction are fixed is decided to be 20% or lower, preferably 18% or lower. Then copolymer polyester obtained by adding an appropriate quantity of inorganic particles as a lubricant is extruded at a temperature of 200-320 deg.C after drying the same. An unstretched film quenched after extrusion is stretched at least in either unidirection of a longitudinal on lateral directions at least at 3 times or at most 5.0 times preferably. |
