Design for Recycling Guidelines do NOT recommend paper labels on PET bottles:
- RecyClass/EPBP (Europe) list in RED (paper labels with fiber loss) or ORANGE (paper labels without fiber loss): https://recyclass.eu/guidelines/clear-pet-bottles/
- The APR (USA) guidelines specifically indicate the paper labels are not preferred for PET containers due to contamination either in the filtering process to separate the paper labels from the PET chips or if they pass to the extrusion step, then the black spec contamination you cite: The Association of Plastics Recyclers | PET Design Guidance (plasticsrecycling.org)
What is the reason?
Paper labels will sink together with the PET flakes and cause impurities / specs in the recycled PET . Additionally if the papers used are not alkaki / water resistant, which is often the case, they will “ pulp up “ into very small fragments causing blockages in the equipment .
>> Two problems: First of all, paper labels can damage recycling equipment and then it can contaminate the recycled PET resins.
(Source: FINAT)
Some additional information from ALPLA (one of the largest producers of PET and HDPE bottles and owner of own recycling facilities):
As also stated in the RecyClass Guidelines (orange or red category), paper labels cause problems in our recycling plants in HDPE and PET recycling. The main problem is located in the washing area – after separation of the paper labels in the floating sink tank, a paper sludge is produced. This is very heavy by weight due to the water absorption and the disposal of this sludge is a three-digit euro amount per ton. In addition, the water has to be treated at high cost due to impurities that can be caused by paper labels and paper fibers. In addition to the problems caused by paper labels in the wash, paper labels can cause problems in the extrusion of HDPE and PET. Paper residues can lead to black spots on the flakes in the final product (PET or HDPE pellets).
Further Sources:
- Labels and Narrow Web article: How Label Materials Impact Container Recyclability | Label and Narrow Web
In all cases, paper labels are detrimental to the recycling of plastic containers, regardless of the polymer, because the paper contaminates the wash water and can stick to the flake, resulting in reduced quality. The hot caustic bath used for PET recycling, in particular, renders paper labels into pulp that can’t be filtered out. Small fibers will remain and carbonize when the material is extruded, resulting in unacceptable quality. Non-pulping paper can resist the bath, but it’s heavier than water and sinks with the PET flake, again contaminating the rPET. - Article of CCL in Packaging Europe magazine: Boosting the recycling of PET bottles – which labels and sleeves should I use? | Article | Packaging Europe
Study conducted by PTI (www.plastictechnologies.com) in 2017, which is still valid, as the materials and recycling technologies for PET recycling have not very much changed since then: Study:-Labels-impact-PET-bottle-recyclability | Plastics News
„Paper labels, for example, can be more difficult to remove in the recycling process. And bits of paper fiber and glue that remain on PET after the separation process can burn and cause black marks when flake is later heated. Cheaper inks, which will bleed while in the water-based separation process, also can contaminate recycled flake and cause discoloration of recycled plastic.“
