additives feature | Clarifiers and nucleators Greater
transparency: thermoformed lids produced using Ultra- Clear PP
containing Milliken’s
Millad NX 8000
the amount used from about 200 to 2,000 ppm. Thus, users can target the amount of additive used to the degree of property improvement (e.g., clarity, HDT, flex modulus) required,” says Goman. Adeka’s ADK NA-902 was introduced a few years ago but has been growing in use. The clarifier is an organophosphorus salt with additional components that is formulated as an alternative to sodium benzoate, a widely used low-cost clarifier. “Some users want to replace sodium benzoate because, in humid climates, it absorbs moisture and has feeding problems. It also is a skin irritant. NA-902 replaces sodium benzoate at one-third of the loading level, which makes it cost-com- petitive,” says Goman. Although improvements have been made in clarifiers,
there is a need for further advancements, such as better material handling, more versatility or multi-functionali- ty, and more efficient dispersion within the PP during compounding, notes Braskem’s Krishnaswamy. Additive suppliers continue to search for improved
properties in areas such as the right balance of mechanical properties (stiffness vs impact strength), organoleptic properties, and dimensional stability, both during moulding and during hot-filling of containers, microwaving, and dishwashing, adds Tad Finnegan, head of BASF Plastic Additives’ Regional Application Center for North & South America. BASF’s Irgaclear XT 386 offers high clarity at lower
BASF’s Irgaclear XT 386 offers high clarity at lower loadings and minimizes organoleptic issues
loadings and also helps to minimize organoleptic issues, and novel addition techniques can be used to maintain good clarity, while improving mechanical performance, he says. Irgaclear XT 386, in addition to its current FDA clearance, received extended approval from the European Food Safety Authority (EFSA). The organisation issued an opinion improving the specific migration limit to 5.0 mg/kg and extending its applica-
tions from PP to all polyolefins as published in the 5th amendment (EU) 2015/174 of Regulation (EU) 10/2011.
Nucleating Agents Nucleating agents speed crystallization in polyolefins, providing benefits such as: faster cooling, which improves cycle times; improved stiffness, which can help with down-gauging or thin-walling; and other properties. Milliken launched a brand-new chemistry in late 2014
that creates a novel crystal structure in HDPE and LLDPE. Hyperform HPN 210M, the first in the product family, is claimed to improve the mechanical performance of HDPE to levels approaching PP impact copolymers. Reed Walker, business development and marketing manager for polyethylene additives at Milliken explains, “HDPE normally forms large spherulitic structures, but Hyperform HPN 210M creates a novel orientation of the crystals in the direction of polymer flow”. He adds that this orientation improves stiffness and thermal properties of injected moulded parts to levels typically obtained with impact copolymer PP. “We see a 20-70% improvement in stiffness, depending on the part, and a 10-40°C improvement in heat deflection temperature. At the same time the nucleated PE part retains the good impact properties of traditional PE.” While PE has a tendency to warp because of differen- tial shrinkage, the nucleator can help to reduce or eliminate warpage. These properties create the option to use PE in opaque applications that typically use PP, such as pallets, crates, bins, and totes. “This additive creates a unique attribute set that is almost like a new polymer – this type of orientation never existed before in HDPE,” claims Walker. With the large capacity of PE coming on stream, fuelled by shale gas, companies will be seeking new applications for PE, he adds. Milliken completed its first production campaign
early this year and the nucleator is now in use in the market, The company is in the process of obtaining FDA food contact approval and expects to have clearances
36 COMPOUNDING WORLD | May 2015
www.compoundingworld.com
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