ADDITIVES | NUCLEATORS AND CLARIFIERS


you could add more to tailor the properties and improve stiffness-impact balance.” Key perfor- mance characteristics compared to sodium benzoate are shown in Figure 1.


Figure 1: Comparison of key performance characteristics of homopolymer PP nucleated with ADK Stab NA-908HT and sodium benzoate Source: Adeka Corporation


Migration Limit’ substance that must be monitored and tested for, reducing the compliance burden on customers,” says Gandhi. In addition to packaging applications, Gandhi says nucleators for PP — and also for PE — are seeing strong growth in automotive applications.


Driven by weight Light-weighting is the key goal for automotive customers. “There is a mandate for lightweighting, but parts must also pass emissions and collision testing. Nucleating agents improve stiffness and heat resistance, as well as speeding moulding cycles,” according to Amit Gupta, Product Line Manager for nucleating and clarifying agents at Amfine Chemical Corporation in the US (a joint venture between Adeka Corporation and Mitsubi- shi Corporation). Adeka’s ADK Stab NA-27 nucleat- ing agent, for example, works in talc-filled formulas but can also be used to replace talc, to increase flexural modulus without increasing density. Among the latest introductions from Amfine and


Adeka is ADK Stab NA-908HT. It is described as a cost-effective formulation using organophosphate technology to improve stiffness as an alternative to sodium benzoates, which have potential to cause skin irritation and poor flow in humid conditions. “With NA-908HT, the formulation cost and


shrinkage properties are matched to that of sodium benzoate, so users do not have to change tooling. In addition, users do not have to add a separate acid scavenger,” says Gupta. “NA-908T can be used at less than half the levels of sodium benzoate, or


58 COMPOUNDING WORLD | June 2021


Clarifying options Clarifiers, which are a subset of nucleating agents, are frequently used to make PP clear enough to replace polymers such as PET and PS in packaging applications. Clarified PP can even replace glass in some uses. The work-from-home trend resulting from the pandemic has boosted use of food packaging, as consumers have been doing more grocery shopping, as well as driven an increase in take-out packaging. Packaging integrity (most nota- bly stiffness), sustainability, aesthetics (including clarity) and affordability are all important in these applications, says Gupta. Amfine is currently expanding production capacity at its manufacturing plant in Kentucky for its ADK STAB NA-71 clarifier, with the new capacity expected to be online by the end of 2021. Gupta says that the additive has been well accepted in the market and is proving especially effective in retort packaging, which requires improved thermal stability so the package does not warp under the high retort temperatures. He says that NA-71, which is an organophosphate chemistry, offers similar clarity and much lower extractable levels than competitive clarifiers. Low extractability and clarity are important in food packaging and are particularly key for some medical applications, such as syringes and drip bags. E-commerce and consumer concerns about sustainable packaging are two megatrends that are “opening new opportunities for clear, lightweight packaging materials,” says Zach Adams, Global Product Line Manager, Plastic Additives at Milliken & Company. Milliken offers both the Millad NX 8000 clarifier and NX UltraClear masterbatches containing the clarifier. “The two largest opportuni- ties are replacing polystyrene packaging with a more sustainable solution to meet brands’ environ- mental goals, and replacing glass packaging that is problematic for the growing e-commerce market due to weight and breakage,” he says. The clarifier has been certified to help proces- sors save energy. Brand owners using PP clarified with Milliken’s Millad NX 8000 ECO clarifier can display a UL Environmental Claim Validation label on their injection moulded parts, explains Adams. Milliken has similarly certified some Hyperform nucleator grades, which by lifting the resin crystal- lisation temperature allow moulders to cut cycle times and reduce energy use. Milliken is building a new manufacturing facility


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