Recyclability of black plastic packaging report

Options for making black plastic packaging easier to recycle.

The majority of black plastic packaging is coloured using carbon black pigments which do not enable the pack to be sorted by the optical sorting systems being used widely in plastics recycling. As a result, black plastic packaging commonly ends up as residue waste and is disposed of in landfill or recycled into lower value materials where polymer sorting is not required.

WRAP has worked in partnership with key players in the retail supply chain to improve the recyclability of black plastics and prevent these materials from going to landfill.

This work was carried out in three phases and based on the results of this work, it is recommended that detectable black colourants be used as a viable option to carbon black pigments in the manufacture of black packaging such as amorphous  polyethylene terephthalate (APET), crystallised polyethylene terephthalate (CPET),  polyethylene (PE) and polypropylene (PP) packaging.

Phase 1

A range of potential solutions was investigated including the use of alternative sorting technologies and alternative coloration systems. Novel NIR (near-infrared) detectable black colourants were developed and shown to look satisfactory in APET, CPET and PP food trays, and enable the packs to be sorted by polymer using NIR sorting systems used commercially in plastics recycling. It is anticipated that the incremental costs of using detectable black colourants will reduce over time as demand and volume increases.

Phase 2

WRAP investigated the masking strength (covering power) of the novel detectable black colourants in more detail. The ability to mask mixed colours is helpful to plastics processors as it allows them to re-use production waste and off-cuts of all colours.

A key finding from this phase of work was that UK converters generally do not mix coloured skeletal waste and therefore inferior masking strength is not a limiting factor for most converters in the UK.

Phase 3

The objectives of this work were to ensure that UK plastics sorters are able to sort detectable black plastic (particularly PET) into the correct polymer and colour streams and to identify end markets for coloured jazz rPET containing detectable black APET and CPET. Our research reveals:

  • Plastic recyclers can sort packaging with the detectable black pigments by polymer type and colour without adversely affecting the value of other streams (such as clear PET or CPET)
  • End markets are available for coloured PP (polypropylene) and PET
  • There is potential for closed-loop recycling of black CPET for the very first time.

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