Reducing Channel Leaks in Flexible Packaging Through Multilayer Structure Design

Leakage in flexible packaging is a chronic challenge that leads to significant production loss, lower product quality and reduced shelf-life. Most leaks in flexible packages originate at discontinuities in seal areas. These discontinuities are inevitable at three-point or junction seals in vertical pouches, bottom gusset seals in stand-up pouches, or side gussets in larger bags. Unintended seal discontinuities also occur in wrinkles, folds, or when a contaminant is present in the seal area.

Leakage results when a continuous channel forms adjacent to these discontinuities along the seal width. The cross-sectional area of these channels will impact the amount of product or gas leakage out of or into the package. Reducing this channel area is particularly important in packaging for oxygen sensitive products where more Oxygen may ingress through a leak than permeate through the entire packaging film.

NOVA Chemicals has developed a new, quantitative test method for measuring the cross-sectional areas of channels at seal discontinuities in flexible pouches and used this method to evaluate many coextruded film structures. Results showed that the type of sealant, multilayer materials, and sealing conditions all affect the channel size. By understanding, controlling and optimizing these factors, these leaks can be minimized or eliminated.