Stretch wrap, or LLDPE (linear low-density polyethylene) elastic film/packaging film, is a transparent, flexible, strong, non-toxic, and safe soft plastic film that meets international environmental health and safety standards. It is tough, impact-resistant, and self-adhesive, helping to reduce product loss, deter tampering, and reduce the risk of injury to workers. Stretch film wraps products on pallets and binds them securely, protecting against moisture and dust. Its effectiveness and cost-efficiency make it a great choice for securing cargo and reducing overall packaging costs.

The excellent viscosity of packaging film layers makes them stick together firmly, securely binding the goods. There are two ways to achieve this viscosity: adding PIB (Polyisobutylene) or PIB masterbatch to the polymer, or blending VLDPE (Very Low Density Polyethylene) with the polymer. PIB is a translucent and viscous liquid, and it is better to use PIB masterbatch for direct addition to the polymer due to the need for special equipment or machinery modification. It typically takes three days for the PIB to exude and make the stretch film’s surface sticky enough. The temperature can also affect the exudation process, as the viscosity is stronger when the temperature is higher, and vice versa. Thus, it is best to store the finished stretch film in a specific temperature range (ideally, 15°C to 25°C).

Using VLDPE instead of PIB will result in slightly lower viscosity, but there is no need for special equipment and the viscosity is quite stable, not affected by the time, but by temperature: it is more viscous when the temperature is higher than 30°C and slightly less sticky when it is lower than 15°C. You can adjust the amount of LLDPE in the adhesive layer to reach the required viscosity, which is usually adopted when doing a 3-layer co-extrusion.