Guidelines for using recycled plastics in food packaging: Recycling processes

It's important to differentiate between 'recycling' and 'reuse.' Recycling refers to the processing of waste materials to make new food contact and packaging articles. Reuse is the action of using an article repeatedly. Usually, in reuse, the material remains intact and is reused in its original form, without additional processing. We won't discuss reuse in this document.

Recycling processes can be classified into 3 typesFootnote 1:

Primary recycling processes involve the physical reprocessing of industrial scrap materials produced during the manufacture of food-contact articles that have not yet been in contact with food and are recycled within the manufacturing site or at another site where an audited quality assurance system is in place. Since they have not yet been used by consumers, they are unlikely to suffer from post-manufacture misuse and therefore have a quality similar or identical to that of virgin plastic.

Secondary recycling processes (also known as mechanical processes) involve the physical reprocessing (for example, grinding, melting and reforming) of post-consumer use plastics collected by recycling programs. The basic chemical structure of the polymer isn't altered during this process. Secondary recycling process typically consists of 3 steps:

  1. incoming plastics are sorted by type, for example, polyethylene terephthalate (PET), polystyrene (PS), and ground into flakes, washed and surface-dried
  2. flakes undergo an additional deep-cleaning step
  3. flakes are melted and extruded to form new plastic pellets

Tertiary recycling (also known as chemical recycling) involves the chemical reprocessing of post-consumer plastics. Tertiary recycling covers a spectrum of technologies that aim to produce outputs that are re-introduced into plastics manufacturing as virgin equivalents. For instance, the chemical de-polymerization of PCR-PET, followed by purification of the resulting monomers, produces ethylene glycol and dimethyl terephthalate that are used to manufacture new PET. The de-polymerization and purification processes are expected to remove contaminants (for example, additives and pigments) bound in the polymer matrix. It should be noted that the chemical recycling industry is rapidly developing and publicly available literature about it is still limited. As such, the chemical safety assessment of tertiary recycling processes will evolve as new knowledge becomes available.

The potential for contamination is considered lower for primary and tertiary recycling processes, as source materials are not unlike virgin resins. As such, a resin resulting from a chemical recycling process is assessed in the same way as a new resin, and so the guidance provided in this document focuses on secondary (mechanical) recycling processes.

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