New liquid additive masterbatch reduces yellowing in recycled-PET bottles

18-Feb-16

A new liquid additive masterbatch that minimizes yellowing and greying of PET (polyester terephthalate) polymers caused by the introduction of post-consumer-recycled resin (PCR) has been introduced by Clariant • The new optical brightening products, which are part of the HiFormer® family of liquid masterbatch solutions and application technology, can be used in a wide variety of PET resin grades and processes, including injection-blow molding, injection molding and extrusion. Typically, PET resins are used in bottles and formed-sheet packaging. The additive has received approval for food-contact applications from the U.S. Food & Drug Administration. • “Packagers are under heavy pressure from consumers and environmental advocates to use more PCR in their products,” explains Peter Prusak, Head of Marketing – Clariant Masterbatches North America, “but the recyclate tends to reduce or discolor the crystal clarity that PET is known for. Clariant’s new HiFormer PET-enhancing additives promise to minimize this problem, opening new opportunities for more sustainable packaging.” • The Clariant liquid masterbatches are resistant to sedimentation and segmentation so they offer extended storage-shelf life. They are also easy to use in gravimetric metering systems that ensure accurate dosing and clean operation. Let-down ratios as low as 0.025% have been used successfully. • The new liquid additives were tested on a production scale blow-molding machine in Clariant’s facility in East Chicago, IL. Bottles made using 25% recycled PET and 75% virgin PET and no brightening additive were compared against bottles made with the same PCR resin and the additive in concentrations of 0.025, 0.035 and 0.05%. While the unmodified bottles showed significant yellowing, all the bottles made with the HiFormer additive were visibly brighter (less yellow and more blue). This is evident in the following spectrophotometer readings: