First Hot-Fill PET Jar With Metal Lug Closure

Amcor Rigid Plastics, Ann Arbor, Mich., claims to be the first to achieve a hotly pursued goal of using metal lug closures on hot-fill PET jars and bottles. The company recently launched a stock 24-oz PET jar with 63-mm neck opening designed for pasta sauces. It’s designed for easy conversion from glass because it uses the same type of capping machinery as hot-fill glass jars with metal lug closures, saving the need for new investment to utilize plastic.

According to Bunlim Ly, Amcor senior marketing manager, metal lug closures are also less costly than some alternatives available for capping hot-fill PET containers. For consumers, the benefit of using familiar metal lug closures is the "pop" of the tamper-evident indicator button on the closure when the hermetic seal is broken. Consumers associate that "pop" with freshness and quality, Ly notes. He said Amcor’s next targets for hot-fill PET with metal lug closures will be 82-mm salsa jars and 38-mm bottles for hot-fill juice and tea beverages.

The "enabling technology" for this development is a patent-pending system Amcor calls A-PEX. It involves special engineering of the PET container and slight modification of the lug closure. Ly calls it a breakthrough technology because it’s the first to overcome obstacles of deformation of the PET container neck to achieve proper sealing necessary for the "pop" on first opening the container. Ly says the A-PEX63 containers are within the industry average range in weight—neither extra-heavy nor extra-light—and meet the industry average for opening torque. The pasta-sauce jar is made by reheat stretch-blow molding using a blow-trim process whereby a "dome" of extra material is cut off the neck of the container after blowing.