In the early days, LLDPE stretch films were mostly blown films, which developed from single layer to two layers and three layers. Nowadays, LLDPE stretch films are mainly produced by the casting method. The process is shown in the figure below. The advantages of uniformity and high transparency can be applied to the requirements of high magnification pre-stretching. Because single-layer casting cannot achieve single-sided adhesion, the application field is limited. Single-layer and double-layer casts are not as extensive in material selection as three-layer casts, and the cost of the formula is high, so a three-layer co-extrusion structure is preferred. A high-quality stretch film should have high transparency, high longitudinal elongation, high yield point, high transverse tear strength, and good puncture performance.