Black plastic packaging visible for sorting systems

With CESA^® IR, Clariant now offers a new additive masterbatch to make dark-coloured plastics visible to the near-infrared (NIR) sensors used in automated polymer sorting systems. Many manufacturers use black packaging to emphasise the brands of their prestige products. However, this is a disadvantage in recycling systems and has led to calls to remove black from the range. The new masterbatch helps to solve this problem and enables increased recycling rates in Europe and other regions.

The new product is available in several polymer- and application-orientated formulations and is part of the ‚Design for Recycling‘ programme at Clariant. Recycling is fundamental to a circular economy. Clariant's Masterbatches Business Unit and its Packaging Market Group are therefore mobilising significant resources along the packaging industry value chain to ensure that an increasingly higher percentage of packaging waste is recycled. plastic packaging can be recycled can.

In most automated sorting systems, packaging materials are sorted with Infrared light is irradiated. As different polymers reflect this light in different ways, NIR sensors can differentiate between high and low density polyethylene as well as polypropylene, polyester and various other packaging plastics commonly used today. Unfortunately absorb However, the carbon black pigments commonly used to colour plastics black absorb most of the NIR rays directed at them. Consequently, the sorting sensors can do not „see“ black packaging“ and polymers coloured in this way.

„Due to this phenomenon, a large proportion of the dark-coloured materials in the recycling streams have not yet been recycled“
Alessandro Dulli, Global Head of Packaging at Clariant Masterbatches

Many brand owners were therefore forced to abandon black for environmental reasons.

In close cooperation with the brand manufacturers concerned and as one of the market leaders in the field of sorting technology, Clariant has developed a convincing solution for the black colouring of plastics that does not impair their basic recognition in the recycling process.

For differentiated IR detection of black injection moulded and extrusion blow moulded products made of HDPE and LDPE, black film and injection moulded parts made of polypropylene as well as black sheet and film made of PET and C-PET, Clariant has developed specific formulations of CESA IR developed.

In tests at Tomra Systems ASA, a leading Norwegian company in the market for instrumentation of recycling solutions, conventionally carbon black pigmented polypropylene proved to be largely indistinguishable under NIR light from black background surfaces such as a conveyor belt. However, when the same material was analysed with another colour system including CESA IR additive masterbatch pigmented was recognised without any problems, whereby the Reflectivity was approximately the same as that of uncoloured polypropylene.

Source: Clariant International Ltd