June 25, 2009
by Canadian Packaging Staff
Amcor PET Packaging, a leader in hot fill engineering located in Ann Arbor, MI , has created an industry first with the introduction of it 2.5-ounce hot fill PET (polyethylene terephthalate) container now being used for the natural energy Steaz Energy Shot.
The one-of-a-kind mini bottle is available in 12 count and is produced at Amcor’s state-of-the-art facility in Nicholasville, KY. The entire package is 100 percent recyclable and although the 2.5 ounce bottle is a relatively simple cylindrical shape, adapting technology used in larger containers was not a straightforward reduction process. Every size container and each design nuance impacts PET performance and presents new challenges.
Amcor principal engineer – innovation Kirk Maki explains: “Perhaps the most difficult part was getting heat set properties into a bottle this size. Vacuum control in hot filling and cooling is the other critical issue, which also required considerable manipulation.”
Maki says Amcor had modify its quipment and add specialty machine controls. “We then had to downsize and modify the tooling to create a scaled down version of how we would normally process the container in order to drive heat set properties to a level high enough to prevent deformation under the heat. We accomplished what we set out to do. The heat set testing has come back at levels equal to or better than some of our other larger heat set containers.”
Maki acknowledged there were challenges with the overall bottle design relating to vacuum control. Testing and calculations based on container diameter were run upfront to ensure that specialty paneling wouldn’t be needed. The paneling was fine when initial hot filling and cooling trials were run, but “the panel rib design had issues. Nothing critical, but we felt it just wasn’t quite right,” Maki said.
So the team continued the quest for perfection by modifying the rib portion of the design. In the process, they developed a superbly smooth area of labeling.
The mini bottle’s finish area added to the complexity. Whereas the standard finish recalls an earlier PET era, it is not the kind of heat set finish one typically finds on a store shelf today. A wide mouth, 28-mm finish is considered a natural sized opening to drink from, compared to the 20-mm finish on energy drink bottles that have drawn criticism.
“When you have a relatively large 28 mm opening on a 2.5 ounce container, compared to a 43 mm opening on top of 500 ml bottle, you can’t simply transfer technology,” revealed Maki. “Although not as light in weight as some newer designs, it has a versatile finish. What allowed us to use it here is the fact that the bottle is small, so there is relatively little heat capacity.”
The closure itself is a standard design, borrowed from pharmaceutical packaging for this beverage application. It also takes custom equipment to fill these small bottles. Not many fillers are currently set up to do it because there hasn’t been a demand for hot fill in bottles this size until now.
“We know it’s a little difficult to maintain the heat when filling small containers while also maintaining throughput,” said Chris Curtis, Amcor PET account manager, North East. “Most of the hot fill in the industry has been with much larger containers.”
For more information, visit www.amcor.com.