An additive is a material added in small amounts to the main raw material to give the film a particular property or to make production easier. It is usually fed to the extruder together with the granules in the form of masterbatch.
Additives commonly found in bag films include slip agents, antiblock agents that stop film layers sticking together, antistatic additives, UV stabilisers and processing aids. Additives can have side effects as well as benefits: some migrate to the film surface over time and can affect print and seal quality. For this reason, additives are chosen with the film’s later processing in mind.