ADDITIVES | FLEXIBLE FILMS
resins with fractional melt indices. Both the LLDPE grades have FDA food-contact approval. The PPAs are typically used at 0.5-2.5% in the final product and they are also available in other carrier resins. The OMS (organo-modified siloxane) line of
processing aids from Evonik includes two non- fluorine PPA masterbatches for films: Tegomer 6810 for PE films and Tegomer 6850 for PP films. These OMS PPA masterbatches prevent sharkskin and die buildup at a loading level of 0.5-2%, said Chris Roland, Technical Service Polymer Chemist at Evonik in North America, in a presentation given at AMI’s North American Compounding World Expo last November. Advantages of the OMS PPAS when compared to
Figure 2: Time to clear melt fracture in blown film production for standard processing aid against Baerlocher’s new PFAS Baerolub AIDS 2201 and 2002 products Source: Baerlocher
compound made with post-industrial recyclate (PIR) and significantly reduced them in a compound made with PCR [Figure 1]. In addition to acting as an antioxidant to prevent polymer degradation, the additive has a lubricating effect that can further prevent larger gels by reducing material-hangups in dead-spots, Cook says. DoverClear 800 is offered as a masterbatch of up to 8% loading, with typical final product loadings of 0.5-4%. It has FDA food-contact approval in LLDPE and HDPE. Polymer processing aids (PPAs) are widely used
to prevent melt fracture during film processing. However, due to the potential threat of European and US regulations restricting the use of fluorinated materials in the future, both plastics processors and additive suppliers are seeking alternatives.
Grouping concern Fluoropolymers are significantly different from the per and polyfluoroalkyl substances (PFAS) that have been identified as a concern. However, regulators are currently grouping all materials together and potential exceptions are yet to be determined. In addition, short-chain oligomers in siloxanes have been categorised as substances of very high concern (SVHCs) by the European Chemical Agency (ECHA). With an eye on pending regulations, many additive suppliers are developing “PFAS-free” PPAs as well as “siloxane free” PPAs. Dover’s latest DoverClear PPAs, which are
offered as masterbatches, do not contain PFAS or siloxanes. Doverclear 840 in an LLDPE carrier is recommended for resins with a melt index greater than one while Doverclear 841 is recommended for
18 COMPOUNDING WORLD | January/February 2024
fluorinated PPAs are said to include shorter set-up and cleaning times, no corrosive wear to the extruder, and high heat-resistance for use in cast film. The masterbatches have US FDA food-contact approval, and they are under review for food-con- tact approval with other agencies globally. The Tego XP 21051 grade already has food contact approval globally, including FDA approval for up to 0.2% in the final product. Evonik also recently introduced a new PPA — Tego XP 21052 — which is both non- silicone and non-PFAS and can be used in PP and PE blown and cast film. It has global food-contact approvals and is now available for sampling.
Alternative PPAs The Baerolub Aid family of PPAs, from Baerlocher, is formulated without PFAS or siloxane. The company says that tests have shown that the new PPAs perform well in blown film, with rapid clearing of melt fracture and reduced die build-up in LLDPE and high molecular weight HDPE. “In the US, brand companies are driving replace-
ment of PFAS PPAs in packaging, particularly in metallocene-catalysed LLDPE films, which require PPAs for good processability,” says Baerlocher’s Nunez. “They want to know how quickly and at what cost the conversion can be made — not if it can be made. The good news is that we have found our new solution clears melt fracture even faster than conventional fluoropolymer PPAs in many conven- tional blown film formulations and processes.” Baerlocher says it has been working on the
platform for more than two years and that positive results have been repeated in many trials. The company says that four polymer producers have reached production stage as they introduce PFAS-free resins into the market. “The product has been running with a large film
converter for more than a year, and we have evaluated how it runs in real production situations
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