PACKAGING FILM

摘要

A packaging film comprising a main film made of a stretchable polymer film material and having a multiplicity of holes on the main film includes is four conditions. A first condition means that a ratio of aeration percentage over final weight is greater than or equal to 14 meters per gram. The aeration percentage is calculated for a predetermined length of the packaging film as the total area covered by the holes over the total area of the packaging film including the area of the holes, when the packaging film is stretched to an elongation equal to the elongation at the Natural Draw Ratio point (NDR point). The final weight is the weight of the packaging film per film meter measured in grams per meter, when the packaging film is stretched at an elongation equal to the elongation at the NDR point. The second condition is that the width of the packaging film is reducible by less than 15% between a condition before any stretching of the packaging film and a condition when the packaging film is stretched at an elongation equal to the elongation at the NDR point. The third condition is that a ratio of an absolute value of the difference of a holding force of the packaging film minus a predetermined target holding force divided by the target holding force is less than or equal to 5%. The holding force of the packing film is determined as the tensile force at the NDR point. The force condition is that a ratio of an elongation at break of the packaging film measured along a transverse direction transverse to the main direction over the elongation at the NDR point is greater than or equal to 50%.