For years, a glass jar sealed by a metal lug closure with a vacuum safety button was the container of choice for hot-filled food products. Today, brand owners have the option to pack those products in a lighter-weight, unbreakable PET (polyethylene terephthalate) packaging while still retaining the benefits of the metal lug safety closure. The ParaPET lug closure, now available from Silgan Closures (silganclosures.com), makes that possible.
The first commercial use of the new closure took place in August 2016 when MegaMex, a joint venture of Hormel Foods and Mexican brand Herdez del Fuerte, launched its LA VICTORIA salsa in PET jars sealed with the ParaPET closure.
The critical challenge for Silgan Closures was to find a metal closure that could seal the PET container securely without deforming the heated and softened neck finish. The vacuum safety button that consumers prefer demands a tight seal. Silgan Closures’ patented ParaPET solution features more (at least five as opposed to four) and longer lugs that distribute pressure more evenly around the container neck, eliminating deformation.
ParaPET’s second new feature is a stepped radius design that stabilizes the container neck during exposure to heat. The new design matches the width of the closure channel to the size of the PET neck, preventing it from flexing and enabling a tight seal. As the closure is applied the neck is forced into the channel, which is lined with Silgan Closures’ proprietary Plastisol compound, which engages it and provides additional lateral stability, holding the neck secure as the closure is tightened.
A third important benefit is that, because ParaPET maintains the same overall configuration as the traditional lug closures it replaces, in most cases it can be filled and capped on existing production line equipment.
The introduction of ParaPET means that Silgan Closures now offers brand owners multiple closure choices: the traditional four-lug closure for use with glass, a closure with the traditional lug closure shape but more and larger lugs for use with PET, and the stepped closure design, also for use with PET. The new closure designs are available in 63-, 70- and 82-millimeter sizes.