Early缠绕film was mostly blow-molded, evolving from single-layer to double and triple-layer. Currently, cast film production is predominant, as shown in the following diagram. This is due to the even thickness and high transparency of cast film lines, which meet the requirements for high pre-stretching rates. Single-layer cast film cannot achieve one-sided adhesion, limiting its application fields. Single and double-layer cast films have a narrower material selection compared to triple-layer cast films, and the formulation cost is higher, so a triple-layer co-extrusion structure is more ideal.缠绕film should possess high transparency, high longitudinal elongation, high yield point, high transverse tear strength, and good puncture resistance.