Stretch film, stretch film, shrink film, the earliest the PVC-based materials, DOA plasticizers and self adhesive PVC film. Due to environmental protection issues, high costs (relative proportion of PE, unit packing area), stretching and poor reasons, when the 1994-1995 started domestic production of PE stretch film will be phased out. PE stretch film with EVA as self-adhesive materials, but its high cost and taste, developed PIB, VLDPE self-adhesive materials, substrates are now dominated by LLDPE, including C4, C6, C8 and metallocene PE (MPE).
Early LLDPE stretch film to film, from single layer to the two-tier, three-tier now dominated by casting production of LLDPE stretch film, the process shown in the following figure, this is because the casting production line with high thickness, transparency, requirements that could be applied to high power stretch. Because form does not extend the laminar flow to a single sticky, applications are limited.
Single, double cast in the choice of materials is not laminar extension of three broad formulation costs are high, so it is based on three-layer co-extruded structures better. High quality stretch film with high transparency, high longitudinal elongation, high yield point, horizontal high tear strength, puncture resistance and good characteristics.