European recycling initiative RecyClass (Brussels; www.recyclass.eu) has updated its guidelines after its research found that PP-based, printed in-mould labels (IMLs) were fully compatible with recycling of coloured polypropylene containers, provided the weight of the ink does not exceed 1% of the container’s weight.

However, the initiative warns that such labelling is not compatible with recovery streams involving white or ‘natural’ material, due to the presence of the inks, which cannot be separated during the recycling process.

Commenting on the research, RecyClass said its analysis demonstrated that while the IML itself does not strongly impact the quality of the recyclate, “the printing ink used for such applications led to the presence of unmelted particles of inks in the recyclate”.

Related: RecyClass traceability certification gets official recognition from Circular Plastics Alliance

After having updated its guidelines for HDPE containers and tubes following the IML study, RecyClass also announced it had endorsed the results of tests carried out by US institute Plastic Technologies (Holland, Ohio; www.plastictechnologies.com), which confirmed three resins developed by compatriot firm Kraton Polymers (Houston, Texas; www.kraton.com) – CirKular+, C2000 and C3000 – were fully compatible with rigid HDPE and PP recycling streams.

Similarly, RecyClass has approved research by Aimplas (Valencia, Spain; www.aimplas.net) on PP film technology using Toppyl PB 8310M and Toppyl PB 8220M polybutene-1 (PB-1) grades by LyondellBasell (LYB, Houston, Texas; www.lyondellbasell.com), which has deemed it compatible with the PP recycling stream. Over a year ago, the Spanish research institute had been approved as one of several certification bodies of the traceability scheme offered by RecyClass (see Plasteurope.com of 09.04.2021).