How inks affect plastic recycling

Inks and coatings may provide the solution to enable further & future use of recycled plastic materials.

Packaging needs to become more circular.

Pressure for a more circular economy in packaging is mounting. Put simply, as packaging manufacturers are increasingly expected to consider how their products affect the environment, more and more are focusing on methods to minimise virgin material use. Ensuring that packaging can be recycled and reused supports efforts keep raw materials available in the supply chain. Furthermore, using recycled materials avoids extracting new resources causing negative environmental impacts. 

The ideal outcome of this is that materials are reused again and again, creating a ‘circular’ lifecycle, reducing carbon emissions, and ultimately supporting businesses in their sustainability efforts.

Under the EU Strategy for Plastics in a Circular Economy (2018), packaging manufacturers have clear targets to reuse plastic packaging materials. By 2025, half of all plastics used in packaging are expected to be recycled, rising to 55% in 2030 – the deadline by which all plastics must be recyclable at the end of their lifespans. In the US, plans are underway to ensure all plastic packaging is reusable, recyclable, or compostable by 2025, and similar targets have been set by other countries including Australia and South Africa.

Achieving these goals will require a significant increase in the supply of quality recyclate. Around the world, the rising demand for recycled plastic is leaving many packaging producers short of sufficient material. In the US alone, if all brands follow through on their pledges to start using more recycled plastic, in 2030 demand for rPET would be triple the available supply.  

This problem is being exacerbated by the fact that not all recycled material is suitable for reuse. Plastic can be contaminated during the recycling process by the presence of other substances, leaving it ‘dirty’ or ‘cloudy’. This affects its characteristics, meaning it cannot be used for all future applications.

While the technology to keep plastic in use for years is improving, packaging manufacturers must support this initiative with ink and coating choices to maximise the available supply.

PET bottles, shrink sleeves, and labels are areas where the benefits of the latest ink technology for recycling are apparent. Although these products have different requirements and need various recycling solutions, innovations in inks and coatings make recycling and reuse much more manageable. Specifically, modern ink and coating technology is capable of vastly simplifying the recycling process, ensuring that inks and labels are safely removed and will not contaminate the resulting recyclate, keeping it suitable for repurposing into more packaging.

Collected PET waste is taken to a sorting facility and recycling centre, where it is shredded, washed, milled, and placed in a float sink tank that separates PET material from other types, such as polyethene and polypropylene. The collected material is then dried, milled again, and extruded before being reprocessed into new plastics.

However, shrink sleeves can present a complication to this process. Because PET bottles and recyclable shrink sleeves are made of the same material, the sleeve could be recycled alongside the bottle. In reality, the presence of inks and coatings means this is often not the case, and many shrink sleeves are instead separated and sent for landfill or combustion. Labels can present a similar hurdle; unless removed, inks used on the label can contaminate the recyclate. 

Any contaminants, such as ink, in the recycling process, can damage the quality of the resulting recyclate, potentially affecting its quality and colour to the point that it can no longer be melted down into high-quality plastic. This means that, too often, these materials are not reused at all.

At Flint Group, we have created the next generation of coating and primer products designed to simplify the PET recycling process and maximise the recovery of recycled material. Our Evolution series contains a Caustic Resistant Overprint Varnish (OPV) and a Deinking Primer, which avoid PET bottle flake contamination. This ensures that the substrate can be recycled and provide a high-quality feedstock.

Evolution Deinking Primer is applied to the substrate before the ink to provide strong ink adhesion throughout the life of the label. It enables the ink to be released (de-inked) into the recycling caustic wash and the substrate to be broken down into flakes, allowing for more than 99% recyclability.

The deinking process occurs after a PET bottle is shredded during the caustic wash. The wash-off coating ensures that the crystallisable PET shrink sleeve sinks to the bottom of the washing tank while inks float to the top, meaning the PET flakes can be collected together in one clean recycling yield.

In contrast, Evolution Varnish ensures that inks remain on the label during the caustic wash used in the recycling process. The varnish application avoids contamination of the washing solution while not impacting the floatability of the label. Therefore, the resulting quality of the reclaimed material is significantly improved. The protected ink can then be skimmed off with the floating label and directed to an alternative waste stream.

The Association of Plastic Recyclers (APR) recognised the Evolution product range for compliance with critical guidance for PET packaging and recently won the Environmental Sustainability category at the 2022 Global Label Awards at Labelexpo Americas.

The Evolution series is a revolution for circular PET packaging. By simplifying the recycling process, these products help boost the supply of quality recycled plastic available to packaging producers. What’s more, these UV-curable products are easy to implement and can be applied in a single pass on a press without any changes to existing ink systems or curing processes.

Products like Evolution can play an essential part in packaging manufacturers’ sustainability strategies, enabling them to keep plastics in the supply chain and reduce the industry’s reliance on raw material extraction. With the Evolution series, we are ensuring the recyclability of bottles and packs for years to come and contributing to a healthier, circular packaging economy.