Page 59 - Plastics News Issue May 2025
P. 59
TECHNOLOGY NEWS
Foamed Films Offer a New Solution
for Recyclable Packaging
Using Foaming to Enable Recyclability
To solve this problem, IKV researchers tested
chemical blowing agents to create a foamed
core in multilayer blown film structures. They
strategically foamed only the middle layer, which
reduced overall film density while maintaining
compact outer layers for structural stability. This
multilayer design helped preserve mechanical
properties like foldability, tensile strength, and
dead-fold angle, which are essential for packag-
ustainability in packaging remains a key ing performance. As a result, the film could re-
priority, and researchers at IKV in Ger- main functional for use in butter wrappers and
Smany actively seek to improve film recy- food labels while improving recyclability.
clability. Therefore, their ANTEC 2025 study Process Optimization and Key Findings
®
explores how foamed multilayer blown films re-
duce density while maintaining critical packag- The researchers evaluated films with 3 wt.% and
ing performance standards. By adjusting the film 5 wt.% of CBA in the core layer, using various
structure, they aim to meet mechanical sorting polyethylene (PE) grades. The 3 wt.% foamed
criteria and support more effective recycling of film reached a density of 0.75 g/cm , a signifi-
3
high-filled plastic materials. cant reduction of about 40% compared to un-
foamed films. Surprisingly, increasing the CBA to
The Problem with High-Filled Films
5 wt.% only marginally reduced density further,
3
Polyolefin films with high calcium carbonate con- to 0.72 g/cm , indicating diminishing returns.
tent are widely used in packaging due to their They also found that molecular weight and
paper-like look and mechanical properties. How- branching of the polyethylene grades strongly
ever, the added filler increases the film’s density influenced foam structure. Higher melt strength
beyond 1 g/cm , making it unsuitable for polyole- supported better foaming and more uniform cell
3
fin swim-sink recycling systems. Consequently, distribution. The layer mass ratio between outer
these films are misclassified during sorting and and inner layers also impacted the final mechani-
fail to enter proper recycling streams, despite cal properties.
being recyclable polymers. Therefore, improv- Balancing Performance and Sustainability
ing their density profile is crucial for enhancing
recovery and supporting circularity in flexible Although foaming reduced the film’s density and
plastic packaging applications. improved sortability, it negatively impacted the
May 2025 PLASTICS NEWS 59
