Non-contact Laser Sealing of Thin Polyester Food Packaging Films

We describe a laser-based, non-contact sealing technique for thin, polyester-based lidding films, used in PET containers for food packaging. The method uses a beam-steered laser to seal the container, thereby enabling virtually instant change over from one product line to another. Unlike conventional sealing PET film processes, no bespoke tooling is required to hold the package components in close proximity and under pressure whilst the seal is formed. This greatly reduces sealing machine tooling costs and potential downtime at product changeovers. Results are presented that show that the process is able to produce seals of higher strength using thin (26 µm) polyester film than those from the conventional thermal/mechanical process. This provides a potential for increased production flexibility, reduction in product wastage, and for reducing the cost and embodied energy in construction of a less massive sealing machine.