Upscaling PLA Compounds with Carbios Active for Home-Compostable Packaging
Gaia Biomaterials was tasked to validate the upscaling potential of PLA-based compounds and Carbios Active enzymes for rigid packaging using the sheet extrusion- and thermoforming process. We made clamshell validators from three different compounds.
The compounds form Natureplast and GAIA was processed together with 5 % Carbios Active enzymes. Introducing Carbios Active in the compounding process is not recommended. Instead we added the enzymes in the sheet extrusion process to ensure we had the greatest number of active enzymes survive.
In the sheet extrusion process we had a melt temperature of 175 C, which is about 15 degrees lower than we process compounds normally without Carbios Active. Thus, using Carbios Active narrows the process window and converters needs to be careful not to be outside of the window, 160-180 C melt temperature.
The sheet extrusion process with Carbios Active went well. We did not notice any difference in the output. This is important for the upscaling potential because any decline in overall output could be deal breaker for industrial converters.
We did notice a slight odour change, a yellow tint and softness of the sheet caused by Carbios Active. This is noticeable in the clamshell demonstrators. We are however not concerned the change in odour will impact the overall taste impression of final produce used in the clamshell. The yellowish tint can also be counter acted with a colour masterbatch and does not impact the overall impression of the clamshell. The slight softening of the sheet compared to the reference did not hinder processing.
In the thermoforming process we did not notice and difference in processing window. The thermoforming process is very convenient because the temperatures heating up the sheet is between 120-130 Celsius and forming process is also much less harsh on the material compared with the injection moulding process. In the thermoforming process we could not see any loss in production speed and the clamshells was easy to process.
We produced 2800 pcs of clamshells in total. And another 2000 pcs of A-PET reference clamshells were produced weeks later.
We are confident that with only a few modification converters can process PLA based materials with Carbios Active on an industrial scale. Most importantly is to set up the temperatures correctly and make sure to discard residual material that has been in the extruder longer than 2-3 minutes. Other limitations may be the loss in transparency limiting the use for fresh produce and customer interaction with the packaging. Overall, we are excited by the prospect of home compostable PLA based rigid packaging due to the overall processability, this is a potential game changer.
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