ADDITIVES | FILM
Right: Milliken partnered with Huhtamaki to develop a mono-material laminate for use in tubes for personal-care applications
masterbatches can help reduce the thickness of the EVOH layer, which can improve recyclability. The company says it is working to improve the barrier properties of HDPE film and flexible packaging to reduce the amount of film and the variety of barrier layers used. “We are improving the package’s overall barrier performance so that less materials need to be used in the package design and inter-material replacement of less circular package formulations can be achieved,” says Kellogg. Multi-material constructions are highly effective but can present a recyclability challenge. As a result, groups such as the Association of Plastic Recyclers (APR) in the US and RecyClass in Europe advocate the use of mono-material structures whenever possible. “Milliken UltraGuard Solutions improve barrier performance of HDPE up to 50% and enable mono-material flexible packaging made with less material,” Kellogg says. HDPE is often favoured over LDPE or LLDPE in PE-based structures when higher levels of moisture barrier are required. The addition of UltraGuard can allow HDPE to achieve a WVTR (water vapour transmission rate) below 2g/m2
/day per mil (25
micron) of film thickness. Some structures require blending different types
of PE in a single layer — LDPE may be added to HDPE to get a more stable bubble or to reduce wrinkling, for example. But adding LDPE can significantly reduce the barrier properties of the film. This can be compensated for by using UltraGuard, says Milliken. Where barrier is achieved with a core HDPE layer, the additive can be used to minimise its thickness. This helps to maintain other physical properties such as toughness and stiffness, which can often suffer when using HDPE. UltraGuard is said to work by controlling the
orientation of the polymer crystals to create a more tortuous path for permeation of molecules. Due to
Plant-based Einar 611 provides anti-fog performance in PE film packaging
the nature of the passive barrier, it is effective in reducing the permeation of any substance in HDPE, including water, oxygen, grease, carbon dioxide, alcohols, gasoline and fragrances, for example.
Mono-material option Milliken says it has partnered with Finnish flexible packaging company Huhtamaki Group to develop a more sustainable, mono-material laminate for use in tubes targeting cosmetics, toothpaste and other personal-care applications. The HDPE tube resulting from this joint development work was produced using Huhtamaki laminates optimised with the UltraGuard Solutions additive. “The tube resulting from this joint development work is opaque with a silver shine, making it ideal for beauty product applications,” says Dr Detlev Schulz, Senior Manager - Sustainability and Business Development for Huhtamaki’s Global Tube Laminates business. “White would work as well, offering outstanding moisture barrier and improved oxygen transmission for all who do not need a shiny silver option.” The most likely end uses will be in 40-200 ml tubes. The HDPE tube project fits with Huhtamaki’s blueloop initiative for sustainable, flexible packaging, which includes a range of recyclable solutions based on mono-material structures using PP, PE and paper. Milliken says it has committed to and has
validated targets with the Science Based Targets initiative (SBTi) towards reaching net-zero greenhouse gas emissions across the value chain by 2050. “For Milliken, this means focusing both on the footprint of the products we manufacture and on providing circular solutions to our customers,” says Kellogg. “Our efforts to promote circularity involve both enabling customers to design their parts to be more recyclable through mono-material construction and through technologies that
16 COMPOUNDING WORLD | January 2023
www.compoundingworld.com
IMAGE: MILLIKEN
IMAGE: PALSGAARD
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