ADDITIVES | ANTIOXIDANTS AND STABILISERS
they are termally stabilised, conventionally recycled polyolefins show reduced mechanical properties due to polymer chain length reduction caused during previous processing, the company says. The new stabiliser system is designed to repair this damage, which it is said to do to such an extent that the polymer can be used like virgin material and processed into high performance applications. In addition, the new system contains renewable raw materials, which contributes further to a reduced carbon footprint. The first products using the new polyolefin
Figure 1: Colour change of an LLDPE sample as produced then after three successive recycling cycles. The upper sequence shows samples contain- ing 800ppm of an Irganox 1076 equivalent commodity stabiliser; the lower sequence samle containing Doverphos LGP12
“Sumilizer GP possesses unique properties and has advantages over commodity type antioxidants,” according to Sumitomo. It cites good processing stability and colour stability at a lower loading level than conventional stabilisers (Figure 2). The stabiliser is also free of nonylphenol (an SVHC). Sumilizer GP has been approved for food contact use by the European Food Safety Authority (EFSA) based on Specific Migration Limits (SML), Sumitomo says, adding: “The use of Sumilizer GP in a single additive system or as part of the recipe will give you improved colour stability of polyolefin-derived final products during storage and product lifetime, due to high resistance to NOx gas discoloration.” Sumilizer GP is intended for high added value
applications, which is reflected in the price. How- ever, because it has both phenolic and phosphite functionalities, the required dosage is lower than with other antioxidant systems. Sumitomo also wants to address recycling applications, where it emphasises the benefit of its low loading concept. According to a spokesperson for Sumitomo in
Europe, increasing attention to non-intentionally added substances (NIAS) is opening the window of opportunity for this additive, which has what the company describes as “a completely different chemical composition from standard AOs” which gives it a completely different reading for NIAS. “We have high interest in Europe from producers of polypropylene and polyethylene in particular, especially for food packaging products, as caps and closures. Market pull is coming from concerns relating to products coming into contact with water, soft drinks, dairy and so on, so a number of applications are arising.” Polyolefin reyclates are the target for a new
stabilisation development from Brüggemann, working together with Fraunhofer LBF. Although
82 COMPOUNDING WORLD | September 2021
repair technology — Bruggolen R-8895 and Bruggolen TP-R2090 — are optimised for recycling PP. The company says it plans to release new additives using the same repair technology in early 2022 for recycling PE. Brüggemann presented its first reactive chain modifiers for PA recyclates at K2019. “Small quantities and a single extrusion step are sufficient to result in recyclates whose properties are on a par with those of virgin materials,” the company claims.
Film solutions With line speeds at some BOPP film producers hitting 600m/min or more, and with the market calling for increased sustainability and higher levels of recycling, enhanced antioxidant formulations are required to provide improved performance throughout the BOPP value chain, says Mohamed Sidqi, Global Segment Manager for Polymer Producers & Fiber at Clariant. He says the company has responded to that need with a new additive package for use by polymer producers — AddWorks PKG 118 — which it says ensures improved stability
Figure 2: Spider web chart comparing key performance characteristics of Sumitomo Chemical’s Sumilizer GP with two conventional commercial AO systems Source: Sumitomo Chemical
www.compoundingworld.com
IMAGE: DOVER CHEMICALS
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