Early缠绕film was mainly produced by blowing, evolving from single-layer to double-layer and triple-layer. Now, cast film production is the main method, as shown in the following illustration. This is because cast film lines offer advantages such as even thickness and high transparency, suitable for high-rate pre-stretching requirements. Single-layer cast film cannot achieve one-sided adhesion, limiting its application areas. Single and double-layer cast films have a narrower material selection than triple-layer cast films, and the formula cost is higher, so a triple-layer co-extrusion structure is more ideal.缠绕film should have characteristics such as high transparency, high longitudinal elongation, high yield point, high transverse tear strength, and good puncture resistance.