Automated recyclate coloring with new inline coloring system

Picture: ROWASOL

The modern plastics industry is faced with the challenge of continuously developing more sustainable and efficient product solutions. The innovative CLOOPMIX® dosing system from OPM Mechatronic, in conjunction with liquid colors from ROWASOL GmbH, offers a pioneering answer to these requirements, especially for compounding recycled materials.

 At the heart of the system is a precise interplay of intelligent recipe management, piston pumps and continuous color control. Liquid colors are fed directly into the extruder via up to six dosing stations. These piston dispensers work almost without pulsation and dispense the colors precisely - regardless of the pressure build-up in the system. The special feature: Instead of a rigid setting, the system continuously adjusts to achieve exact results even with fluctuations in the material composition.

Color control is carried out using the highly developed GranuTrack® system. Granules are removed directly from the production process via a drawer system and measured in a protected area to exclude external in fluences. A spectral color sensor precisely monitors the color values of the material. As soon as deviations from the target value are detected, the central control system sends correction commands to the dosing stations. The system uses the CIELAB color space to fine-tune the color along the three axes - lightness (L*), red-green (a*) and blue-yellow (b*). Even the smallest color changes can be registered and corrected. An impressive detail is the CLOOPMIX®’s ability to achieve precise color results with just four setting colors. These colors are coordinated in such a way that in combination they enable all corrections along the color axes.

During a successful practical test on a Leistritz compounding line at sister company ROMIRA in Pinneberg, the CLOOPMIX® system was able to prove its efficiency. Despite the natural color variations of the recyclate, the coloring remained constant and the system reacted promptly to material changes. The very accurate measurement enabled a color deviation of less than ΔE 1 - proof of how precisely the interaction between liquid colors, control and dosing works.

The successful test run illustrates the close partnership between ROWASOL and OPM Mechatronic, who have created a pioneering solution for the automation of recyclate compounding with the CLOOPMIX® system. The system makes it possible to process even challenging recycled materials with minimal use of resources and consistently high color quality. Thanks to the precise interaction of liquid colors, intelligent control and real-time color measurement, the coloring remains stable even with material fluctuations. This project is another milestone in sustainable plastics processing and impressively demonstrates that efficiency, precision and environmental protection can go hand in hand.