Food-PET or Non-Food-PET, that is the Question

Differentiation of used PET bottles by means of UV fluorescence markers

The "Final Consortium Meeting" of the Polymark project was held at Sesotec GmbH in

Schönberg on 7th and 8th February 2017. Polymark was a three-year research project funded

by the European Commission that focused on a new technology for the identification and sorting

of plastics, particularly PET. The correct detection of plastics and the generation of high-quality

secondary raw materials should be further improved. The project involved participants from the

complete PET value creation chain.

The objective of the Polymark project was to increase the level of food-contact-approved

recyclate from the PET recycling process by differentiating between PET bottles that were used

for food (food bottles) and bottles that did not contain food (non-food bottles). On the one hand

marker substances were developed for this purpose that make it possible in the recycling

process to efficiently differentiate food-PET bottles from non-food PET bottles. These marker

substances are used to encode information about the properties and structure of the PET

bottles.

On the other hand the Polymark project also developed a sensor-based identification system

that detects the markers and decodes the information. In a next step the plastic packings are

separated in a mechanical sorting process. Sensor technology and mechanical components are

integrated in a sorting machine.

How does a marker substance work?

For the differentiation between food-PET and non-food-PET a bottle type is coated with an

invisible UV fluorescence marker. This marking substance is applied to the outside of the bottle

or is printed onto the label or the envelope and fluoresces when it is excited by UV light.

How does sorting work?

In an industrial PET recycling process the bottles usually pass through automated sorting

machines that separate the PET flow by colour and plastic type. In the Polymark project this

approach was used for the development of a prototype sorting machine that is able to sort food

and non-food bottles using a UV fluorescence sensor. Sesotec played a leading role in the

development of this sorting system.

"Our research partners have successfully developed a complete technology package", explains

Patrick Peuch of Petcore Europa. "The sorting technology was developed in parallel to the

marking technology, and test runs have demonstrated that the markers can be detected by the

sorting machine and that the respective bottles can be separated. Economically efficient and

profitable high-speed sorting with the result of pure food-PET for bottle-to-bottle recycling thus

has become possible."

The list of Polymark partners includes: Petcore Europa, European Federation of Bottled Waters

(EFBW), European Association of Plastics Recycling and Recovery Organisations (EPRO),

Plastics Recyclers Europe, UK Health and Environmental Research Institute (HERI), Fraunhofer

Institut für Photonische Mikrosysteme (IPMS), Sesotec GmbH, 4PET Recycling BV, Mikrolin

Hungary Kft. and Colormatrix Europe Ltd .