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Although a certain amount of leeway is possible for many products depending on customer expectations or the area of application, manufacturers are often faced with the problem of not being able to be sure in advance what color will come out at the end of the production process when using more recycled material. The SKZ Plastics Center has therefore been conducting intensive research into possible solutions.

As part of a project funded by the German Federal Ministry for Economic Affairs and Climate Protection (BMWK) via the Central Innovation Programme for SMEs (ZIM) (funding reference KK5068029GR1), SKZ scientists worked with industrial partner inno-spec GmbH to develop a camera-based measuring system for optimized colour formulation in plastics recycling.

As part of the project, a color measurement system for the visible wavelength range was developed, consisting of a conveyor belt, an illumination unit and a hyperspectral camera (HSI). The lighting was converted from halogen to LED technology in order to improve measurement accuracy. The recorded color values were correlated with a commercial spectrophotometer and served as the basis for machine learning. A software demonstrator for predicting color values was developed and successfully tested.

Through extensive practical tests both at the SKZ and at the industrial partner inno-spec, color measurement values could be correlated through the images using test specimens and regrind blending and used as a basis for the iterative development of various algorithms as well as for the training of AI models.

"The most precise color formulation possible is crucial for the use of recycled plastic. The successful development of the software in this project was therefore an important contribution to the sustainable use of plastics. The project is a prime example of how important it is to work together on an interdisciplinary basis in a world that is also becoming increasingly complex in technical terms. The broad expertise in a wide range of areas within the SKZ enables us to be a competent development partner, even for complex issues," says Christoph Kugler, Group Manager Digitalization at the SKZ.

The project shows how modern technologies such as hyperspectral imaging and machine learning can revolutionize the plastics recycling industry. The results provide a promising basis for the further development and market launch of the system.

Further information: Digitization