ADDITIVES | POLYAMIDES
question about whether some phosphorous-nitro- gen FRs would break down,” he says. Some low-molecular weight halogenated flame
retardants present toxicity concerns and have the potential to produce corrosive fumes; as a result, most of these were phased out of E&E applications in Europe nearly 20 years ago. Polymeric bromi- nated flame retardants, however, are said to be an option; they are effective and are lower cost than halogen-free flame retardants, and suppliers say they are sustainable.
“Some newer polymeric halogenated flame
retardants are being adopted (such as the Emerald technology in polystyrene), but some older polymeric halogenated flame retardants used in nylons successfully for many years are being scrutinised,” says Avakian. Melamine cyanurate is also under scrutiny in Europe, he adds.
One to watch There is an ongoing push for moving to halogen- free flame retardants, especially in Europe. New halogen-free technologies continue to be devel- oped. For example, organophosphorus FRs based on DOPO [9,10-dihydro-9-oxa-10-phosphaphenan- threne-10-oxide] are nonvolatile and can be derivatised to fit into different polymers. While these chemicals have not yet been adopted broadly, because of limitations in supply and in obtaining commercial registrations, the technology is one to watch, Avakian suggests. Christian Panofen, Global Marketing Director for Huber Engineered Materials’ Fire Retardant Additives business, points to the EU’s Green Deal and the subsequent Chemicals Strategy for Sustainability, which was introduced in October 2020, as driving support for halogen-free flame retardants (HFFRs) and smoke suppressants. “Increased regulatory compliance for use of fire
retardants will continue to play a major role in the future. The strong, positive momentum for use of
environmentally friendly, halogen-free fire retard- ants will increase,” says Panofen. “The trend of combining and blending non-halogenated fire retardants will most likely increase to optimise flame retardancy and smoke suppression and enhance material performance,” he adds.
Phosphate option Huber’s Safire 400 nitrogen-phosphorus (N-P) fire retardant technology is a new melamine poly (zinc phosphate) intended for use in PA. Panofen says that, compared with melamine polyphosphate at the same loading levels, Safire 400 offers equiva- lent fire retardant and process performance as well as having some additional advantages. These include a dual fire-retardant mechanism of intu- mescence and strong smoke suppression via char formation in most polymers, improved smoke opacity and toxicity performance, reduced bloom- ing, higher comparative tracking index (CTI) performance, and a lighter colour. It can also act as a synergist with phosphinates and other HFFRs. Huber offers other HFFR technologies, including alumina trihydrate (ATH) and magnesium hydrox- ide (MDH). At the end of 2021, Huber Engineered Materials (HEM) completed the acquisition of RHI Magnesita’s 50% ownership stake in Magnifin Magnesiaprodukte, which had been a 50/50 joint venture with Martinswerk (Martinswerk has been part of Huber since 2016). The synthetically produced, fine particle-size of Magnifin MDH is said to allow processors to produce flame retarded PAs without halogen or phosphorous containing compounds. “Today’s existing products contain approximately 10 to 20% glass fibre, with about 30 to 55% of Magnifin,” says Panofen. He says the product ensures very low levels of smoke density and allows users to achieve a UL94 V-0 compound with CTI of 600V in a glass fibre-reinforced formula- tion that can be made in any colour. In electric vehicles (EVs), both flame retardancy
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