COLOURS | MATERIALS
Colours provide both function and aesthetic
appeal in recycled plastics. Jennifer Markarian finds out more about colours, colour
measurement and colour control
Colours designed for improving recyclate
As plastic compounds containing post-consumer recyclate (PCR) make their way into a growing number of applications, colour pigments – from black and white to a range of brilliant shades and even special effects – play an important role in appearance and functionality. In some applications, it is crucial that colours are designed to allow sortation of parts at their end-of-life. While carbon black pigments, for example, prevent identification by near infrared (NIR) optical sorting technology in material recycling facilities, alternative NIR-detectable black pigments can be accurately sorted. “As the plastics industry works toward greater
recyclability, the need for alternatives to traditional carbon black has driven growing demand for NIR Black solutions,” said John Davidson, Colortech’s North American Commercial Director for Black Masterbatch. He noted that the company offers options of NIR-detectable black concentrates
www.plasticsrecyclingworld.com
tailored to requirements for appearance and cost. The company has also validated the performance of its NIR Detectable Black concentrates through independent third-party testing. Plastics that use an aluminium-pigment silver
effect can also cause difficulties with NIR detect- ability, particularly with finer particle sizes, depend- ing on the concentration. Eckart’s NIR silver, however, is designed to allow NIR detectability. The company said that it can provide guidelines on which pigments can be used to achieve the desired metallic effect and opacity. Eckart’s new Mastersafe Silvershine can be used in combination with its NIR Silver to ensure NIR detectability, the company noted. Mastersafe Silvershine is an aluminium pigment concentrate provided as a dust-free pellet that is easy to handle and is easily dispersible, with a pigment content of 80%. NIR-detectable black pigments from Vibrantz have been demonstrated to be able to be sorted
November/December 2025 | PLASTICS RECYCLING WORLD 15
Main image: Colouring PCR materials poses technical challenges
IMAGE: SHUTTERSTOCK
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