COLOURS AND MASTERBATCH | MATERIALS
Helping to improve the appearance of recyclates
Matching the aesthetics of recycled plastic materials to those achieved with virgin polymers is a challenge, but one that producers of colour pigments and masterbatches are gearing up to meet. By Mark Holmes
The increased use of recyclates presents recyclers and converters with a number of problems regard- ing the appearance of their materials. To improve the appearance of recyclates, issues such as preventing thermal degradation, processing, controlling the rheology, reduced yellowing, odour, gels and agglomerate formation all need to be considered. The wide variation in colour and quality of plastic recyclates also poses a problem for achieving consistent colours when using a high post-consumer-recycled (PCR) content. However, manufacturers of pigments and colour master- batches are developing new products and tech- nologies that can help meet this challenge. With growing demand for mechanically recycled polyolefins and the requirement for higher recy- cled material content in packaging applications, recyclers face several challenges to provide higher quality and easier processability of recycled material to plastics converters, according to LyondellBasell. “One of the main challenges faced by recyclers and converters is thermal degradation of the polymer from the multiple extrusion and compounding processes, which can lead to loss of mechanical performance and rheological issues,” says Núria Vallespí Salvadó, Marketing Manager, Colour Concentrates, LyondellBasell. “Thermal degradation can also reduce the aesthetic quality of the recycled polymer due to gel formation, yellow discolouration and increased odour. Other challenges may include high moisture and volatiles content coming from the sorted plastics washing process and contamination from mixed polymer recyclate, which can also lead to processing problems for the converter and a reduction in mechanical performance.” She says LyondellBasell offers a complete
product range of masterbatch additives, which help recyclers and converters to address some of these challenges. It also offers CirculenRecover
www.plasticsrecyclingworld.com
colour masterbatches using recyclate carrier resins to enable customers to maximise the recyclate content in their products. The company has a range of near-infrared (NIR) detectable colours, including black, to support effective sorting of plastics by polymer type in sorting centres. Vallespí Salvadó also highlights influences driving new developments in colours and pigments for plastics recyclates, which include regulations, the sustainability goals of brand owners and growing consumer awareness demanding the use of plastics recyclates. In addition, new colour developments still need to provide the brand identity of the end product but also need to consider sustainability attributes and future recyclability. The development of colour enhancers to improve the colour of transparent recyclate, such as PET, is also increasing; recyclate often has a yellow colour due to thermal degradation or
Masterbatch producer Broadway says consistency of the colour within PCR materials is continually being addressed at the company
November/December 2022 | PLASTICS RECYCLING WORLD 33
IMAGE: BROADWAY
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