SUSTAINABILITY | ADDITIVES FOR RECYCLING
Right: ColorMatrix Amosorb 4020G oxygen scavenger reduces haze and yellowing by up to 50% in PET recycling
for rigid PET packaging – ColorMatrix Amosorb 4020G. The company says the new grade offers up to 50% lower haze and also reduces yellowing by 50% during the mechanical recycling process compared to earlier grades of Amosorb oxygen scavenger. The company says that, with the increas- ing use of rPET in rigid containers, brand owners must be sure their oxygen scavenger system is maintaining efficacy. Its tests showed that the 4020G additive had negligible effects on efficacy for the rPET grades tested compared to competitive materials, which it says lost almost all oxygen scavenging ability with rPET content as low as 20%. Another concern for rPET is the increased levels
Below: Avient’s ColorMatrix AAzure process aid can reduce acetaldehyde content by up to 80% in the preform to tackle off-taste issues
of acetaldehyde (AA) created during the recycling process, which can lead to off-taste in bottled contents. Avient’s ColorMatrix AAzure Acetalde- hyde Control Additive is a process aid for PET and rPET preforms that can also reduce AA by up to 80% in the preform. As a process aid, the additive helps overcome the risk of blowouts, so higher levels of rPET can be used. The additive is commer- cially available in major global markets and meets direct food contact regulatory requirements, the company says. Avient’s Colormatrix Smartheat RHC was intro- duced in September last year to improve the quality of PET bottles contained recycled resin. The liquid dispersion processing aid is intended for use by rPET producers and manufacturers of preforms for injection stretch blow moulding and is claimed to improve rPET processing and product quality. The company says the additive helps improve thermal stability and reduce yellowing and provides a more effective alternative to the addition of toners or colorants to mask yellowing caused by heat exposure. The company suggests that a wider uptake of the additive in the rPET chain would even- tually improve overall quality of the recycle stream. A new addition to Avient’s ColorMatrix Lactra light blocking additive technology family for PET dairy packaging is also said to be compatible with PET
recycling streams (there have been concerns that mineral modifiers may have a negative effect on the rPET stream for fibre). The new additive contains less than 1wt% titanium dioxide (TiO2
) and less than
4wt% inorganic content; it is also available as a TiO2
-free version. According to the company, tests
show that the Lactra additives are suitable for closed-loop bottle-to-bottle recycling. The low levels of TiO2
in the productsalso helps packaging prod- ucts comply with new European TiO2
Waste Framework Directive 2008/98/EC), it says. A new impact modifier masterbatch from
Sukano allows use of virgin or rPET in monomate- rial, recyclable packages for cold, flash-frozen, and room-temperature food trays, replacing specialised copolyester resins or other hard-to-recycle film structures. The company offers several other masterbatches to improve rPET, including anti- yellowing, melt enhancing, and NIR-detectable colours and blacks (the latter have been tested using the French COTREP protocol and found suitable for recycling).
Targeting HDPE After PET, HDPE is the second most widely sorted PCR stream in most material recycling facilities (MRFs). Some of the primary challenges with recycling HDPE are retaining its physical and rheological properties, says Paul Albee, Consultant for Addisperse (AFI Global). A lack of understand- ing in the recycled compound industry regarding formulation technology, which can help solve these problems, is a further challenge. Addisperse introduced its NC203C stabiliser, which is based on reactive chemistry, to rebuild molecular weight and boost physical properties in reprocessed and recycled HDPE compounds. The additive also improves process stability during extrusion and increases “melt uniformity and hot strength, dramatically improving foaming,” says Albee. For example, in a PCR HDPE milk bottle resin the addition of 2% NC203C allows foam density to be reduced from 0.89 to 0.61 gm/cc
36 COMPOUNDING WORLD | October 2020
www.compoundingworld.com restrictions (EU
IMAGE: AVIENT
IMAGE: AVIENT
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