A new study coming out of the United States has confirmed what companies involved in food and beverage packaging and recycling in South Africa have known for some time – despite the strides made in reducing the environmental impact of PET beverage bottles, the insensitive selection of other packaging elements such as labels and glues can dramatically reduce their recyclability.
“The big takeaway (from the study) is that the bottles are probably reaching the technical limit of what the light-weight bottle could handle, but at the same time, they could be better from a recycler’s point of view,” said Marcio Amazonas, one of three authors of the paper.
“For example, water bottle designers have lowered the weight of containers to 7.5 to 8.5 grams in some low-priced products but PET recycling can become contaminated by using the wrong label material or inks that bleed. Even the type of glue used can have an impact.
“Paper labels, for example, can be more difficult to remove in the recycling process. And bits of paper fibre 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.
“Designers should pay more attention to these issues to create fewer problems for PET recyclers,” he said.
Executive director of the South African National Bottled Water Association (SANBWA), Charlotte Metcalf, concurred: “As an organisation, SANBWA was among the first worldwide to require its members to follow specific recycling guidelines.
“In this respect, it was advised by PETCO in South Africa (the local plastic industry’s first joint effort to self-regulate post-consumer PET recycling), and requires its members only use recycling friendly materials or recycling optimal materials as stipulated in the SANBWA Bottled Water Standard and published on https://petco.co.za/wp-content/uploads/2016/08/PETCO_Design-4-Recycling-Guide.pdf
“In addition, members must only support PET bottle suppliers which contribute to the PETCO recycling levy, establish a drop-off centre for the public at the bottling facility and all distribution centres and add the ‘please recycle’ sign on all labels.
“This goes a long way to minimising the environmental impact of the PET bottles used by SANBWA’s members, and we call on all beverage bottlers to follow suit,” she said.
PETCO’s Design-4-Recycling Guide addresses all elements of packaging from the form of the package (for bottles, for example, wide necks assist in washing the bottle at the recycler), material type, material identification (to facilitate the visual identification of plastic types during manual separation), composite materials and barrier layers, additives, colour, and closures, closure liners and sleeves.
When it comes to labels and inks, the Guide suggests:
- adhesive use and surface coverage should be minimised
- sleeves and safety seals should be designed to completely detach from the container or else they become contaminants,
- water soluble at 60 – 80°C and hot melt alkali soluble adhesives are those of choice
- paper labels are not ideal and paper labels on plastic film represent a significant problem to conventional recycling
- labels should not delaminate in the washing process; polyethylene and polypropylene are preferred
- label materials
- foil safety seals that leave remnants of foil and / or adhesive should be avoided
- use of paper labels, metallised/foil labels on film represents a significant problem to conventional recycling; these labels are costly to remove, increase contamination and, if left, significantly devalue the quality of the collected material
- deposition techniques that provide a very thin layer of metal (only atoms deep) are acceptable
- however and are the method of choice to provide a metallised effect on labels
When it comes to inks, the Guide suggests:
- heavy metal inks should not be used for printing as they may contaminate the recovered plastic
- inks that would dye the wash solution should be avoided as this may discolour the recovered plastic diminishing its value
“Importantly, SANBWA formally audits its members’ compliance with respect to environmental stewardship,” said Metcalf.
“It will soon also audit non-members, and inform these bottlers when or if they find any shortfalls in their packaging, and suggests changes. Bottled water bottlers – whether they are SANBWA members or not – must remember that extended producer responsibility is a legal requirement for doing business in South Africa.
“SANBWA urges designers to consider the possibility of including recycled plastics in their packaging for both environmental and commercial reasons. The specification of recycled materials in the design of new products supports the recovery of plastics by providing a market for reprocessed material. Other advantages include a potential cost saving, marketing benefits and reduced environmental impact,” she concluded.