Coextrusion of multiple layers of film can increase the options available in designing films.
For example, each layer can be optimised to perform a different function:
- A surface layer for sealing may contain an excellent sealing resin such as metallocene
- Non-sealing layers may contain a higher density blend to provide
stiffness without affecting sealing
- Antiblocking additives can be added to only the surface where they are required
- Stretch wrap film can be produced with high cling on only one side
- In some cases film can be produced with more slip on one side
- High gloss surfaces can be produced
- Films can be produced with high barrier resins (e.g. Nylon, EVOH)
although this can impact the recyclability of the film.
- Incompatible resins can be used in different layers
By taking advantage of some of these options, significant cost savings can be achieved. These cost savings are typically achieved by:
- Minimising the amount of expensive resins required
- Allowing down-gauging
- Replacing more expensive laminate products
The first Issue of the Qenos Multilayer Film Series provides an example of a typical PE Shrink Film.