When Small Planet Foods Inc., based in Minneapolis, Minnesota (www.cascadianfarm.com), wanted to convert its Cascadian Farm organic cereal box liners to bio-PE, they went to Printpack Inc. in Atlanta, Georgia (www.printpack.com), to develop the new films. The only source for bio-PE was Braskem, which produces a range of bio-LLDPE and bio-LDPE film grades, but very limited HDPE film grades, so developing a combination of grades to match an existing petro-film product wasn’t easy. (Based on Braskem’s website, the company offers five blown-film grades of bio-LLDPE, six blown-film grades of bio-LDPE, and two bimodal film grades of bio-HDPE.)

The choice of bio-HDPE was important since HDPE supplies a moisture barrier, which is critical for dry cereal. Braskem’s bio-HDPE is mostly for injection molding and would have the wrong melt index and melt strength for film. Printpack ended up using a non-film grade of HDPE with enough moisture barrier to work in the new film structure with “no compromise in moisture barrier, seal properties, and caliper vs. the petro original,” Printpack says.

Cascadian Farm launched the bio-film liners in its Cinnamon Crunch cereal boxes in 2013 with 57% bio-content, and gradually rolled the new liners out across all its cereal flavors. The second generation launched in 2015 and currently in grocery stores is 68% bio-based. Printpack won a Silver Award for Innovation from the Flexible Packaging Association (www.flexpack.org) in 2014 for the bio-content film structure.

Acknowledgement on the packages is modest. Some box-tops say, “We’re Growing a Better Package.” Some boxes say only, “USDA Certified Biobased Product, package 68%,” on the side-bottom, and, in fine print, “Bag inside this carton is USDA certified bio-based product.”