Bio-based multilayer transparent barrier films are now reality

While flexible multilayer plastic packaging makes up over 75% of the food packaging used today, it tends to be neither recyclable nor compostable. Now, four key players in the bioplastics industry have joined together and come up with a solution. Eurotech Extrusion Machinery, NatureWorks, Nippon Gohsei and Sukano have successfully developed and processed a multilayer transparent bio-based barrier film.
PLA film made from Natureworks’ Ingeo resin is already commonly used in many types of flexible packaging. Not only does using Ingeo reduce the carbon footprint of the packaging, it also means that composting becomes an end of life option. For higher gas barrier requirements, a coating or a metallization surface treatment of the film is typically required. However, using a barrier polymer eliminates this need.
The coex film processed at Eurotech used a K5A 5 layer blown film lab machine in a
configuration using 2 extruders 25 mm., and 3 extruders 20 mm., including the die lip
of 100 mm. diameter and 1.4 mm gap.
The total film thicknesses were 45 microns, with a width of 280 mm width, contains Ingeo PLA 4043D from NatureWorks and is used in the inner A layer; an outer bubble layer E included Sukano masterbatch processing aids. These PLA-based Sukano masterbatches were specifically designed for this application. The tie layers use BTR8002P and the barrier layer uses G-polymer, both from Nippon Gohsei. This combination of formulation and process conditions yielded a stable bubble, excellent film transparency, and good roll quality.
Testing showed that the use of Sukano masterbatches offered increased melt
strength, and therefore better processability, good transparency and better adhesion
during sealing. Mechanical properties were also maintained. As an additional benefit,
each material used in the film has either been tested and certified or assessed to be
biodegradable and industrially compostable according to European norm EN 13432.
Less film sticking was managed via the use of slip agent bio-based masterbatches,
which increased the processing window and ensured good processability conditions
and a lower COF, conferring better film properties for secondary fabrication steps.
For the barrier layer, Nichigo G-Polymer, the world’s first extrudable high barrier
amorphous vinyl alcohol resin, was used. This provided key benefits in packaging,
such as excellent gas and aroma barrier and high transparency, while supporting
compostability and recyclability properties in the final film produced.

Outstanding water solubility for solution coating barrier applications and extrudability were also evident. The G-Polymer barrier is so effective that it can replace Alu-foil in many packaging applications. And even at 4mm thickness of mono-layer G-Polymer,
transparency was glass-like. The tie layer BTR8002P gives high adhesion between
layers, maintaining high transparency.
This new multilayer transparent bio-based barrier film offers packaging manufacturers a viable alternative to conventional, fossil fuel-based structures in dry food packaging such as lid films for coffee capsules or lidding films for cups and trays, flow packs, trays for snacks, and biscuits packages. And it may even extend to foods such as ham, fish, and meat when used with the proper packaging design.

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