Quickly separating black plastic packaging according to type

By OEM Update Editorial October 13, 2021 4:16 pm IST

With Bayferrox 303 T, the specialty chemicals company LANXESS has developed a black pigment for colouring black plastic that reflects 20 percent of near-infrared radiation. 

Consumers, environmental organisations, politicians and industry are increasingly taking action to reduce microplastics. Reusing plastic waste as a raw material also contributes to this, but requires that the different plastics be separated according to type first. Stefano Bartolucci, Global Market Segment Manager for Plastics in the Inorganic Pigments (IPG) business unit at LANXESS says, “With our latest black pigment, we can help to increase the recycling rate for plastic packaging, which is still far too low around the world.” 

With Bayferrox 303 T, the specialty chemicals company has developed a black pigment for colouring black plastic that reflects 20 percent of near-infrared radiation (NIR). This enables plastics to be identified efficiently and cost-effectively with the aid of NIR detectors like those used for sorting waste. “Plastic packaging coloured with carbon black, on the other hand, as is used in large part today, does not reflect any radiation and therefore cannot be detected in sorting plants,” says Bartolucci. 

Near-infrared detection of composite materials in automated sorting plants

Properly separating waste and producing recycling materials that are separated according to type is expensive. It is difficulties in sorting waste that are currently causing the recycling rate of plastic to remain far too low worldwide. Composite materials and black plastic are particularly difficult to sort, as are foils that are glued together or small transparent trays made from PET. The LANXESS pigment Bayferrox 303 T can make a decisive contribution to recycling black plastic packaging.

In automated recycling plants, near-infrared detection (NIR spectroscopy) is used to quickly sort plastic waste into different types. To this end, infrared cameras are installed above the conveyor belts in most cases. However, black plastic packaging such as foils cannot be identified correctly by the optical sensors due to its colour and consequently cannot be sorted. Unlike the carbon black pigments often used in the plastics industry, Bayferrox 303 T reflects infrared radiation, thus allowing identification with the aid of NIR detectors. As a result, black plastic items such as packaging films or trays can be better identified with the iron-manganese mixed oxide and sent for recycling.  

Complex inorganic coloured pigments (CICPs) and manganese ferrites, of which the latter are far more cost-effective, are high-quality alternatives to carbon black thanks to their property profiles – because they reflect infrared light. The iron-manganese mixed oxide Bayferrox 303 T from LANXESS also offers colour strength that is 20 percent higher than comparable pigments. 

“Thanks to a special manufacturing process, we have succeeded in synthesising a pigment with an extremely low magnetic value. If you compare our Bayferrox 303 T with standard manganese ferrites, the magnetism has been reduced by more than 50 percent,” says Bartolucci. “With our black pigment, false alarms in production can be avoided and a higher degree of process reliability can be achieved because there are fewer interruptions,” he adds.

For more info, visit: lanxess.com