MATERIALS | ADDITIVES FOR FILM
Figure 1: Chart showing reduction in total gel count using Dover Chemical’s LGP12 antioxidant in production of PE film with 30% PIR and PCR content
Source: Dover Chemical
siloxanes. Doverclear 840 in an LLDPE carrier is recommended for resins with a melt index greater than one while Doverclear 841 is recommended for 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
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
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 16 FILM & SHEET EXTRUSION | March 2024
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
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 said 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.
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