Stretch film, the first domestic production of PVC stretch film with PVC as the base material, DOA as the plasticizer and self-adhesive effect. Due to environmental protection issues, high cost (relative to PE’s high proportion, less unit packaging area), poor stretchability, etc., it was gradually eliminated when the domestic production of PE stretch film was started from 1994 to 1995. The PE stretch film first used EVA as the self-adhesive material, but its cost was high and it had a taste. Later, PIB and VLDPE were used as self-adhesive materials, and the base material was mainly LLDPE, including C4, C6, C8 and metallocene PE ( MPE).
In the early days, LLDPE stretched films were mostly blown films, from single-layer to two-layer and three-layer; LLDPE stretched films were mainly produced by the casting method. This is because the production of casting lines has the advantages of uniform thickness and high transparency. It is suitable for the requirements of high-rate pre-stretching. Because single-layer casting cannot achieve single-sided adhesion, the application field is limited. Single-layer and double-layer casting are not as wide as three-layer casting in terms of material selection, and the formulation cost is also high, so the three-layer co-extrusion structure is better. A high-quality stretch film should have the characteristics of high transparency, high longitudinal elongation, high yield point, high transverse tear strength, and good puncture performance.