ADDITIVES | FLAME RETARDANTS
recyclable flame retardants, but also by putting them at work in a wide range of applications and formulations,” he says.
Comparing performance The company has focused on two major E&E applications: glass fibre reinforced PA66 and PBT, both rated V-0. For PA66 compounds, ICL-IP used a methodology based on five cycles of injection moulding and mechanical recycling, with cycles 2-5 performed by mixing 50% of virgin compound with 50% of recycled material from the previous cycle. It tested six formulations: one with no FR; one with ICL-IP brominated PS (FR-803P) and ATO as a synergist; one with FR-803P and no ATO; one with ICL-IP high molecular weight brominated epoxy (F-2400) and ATO; one with F-2400 alone; and finally one with a commercial non-halogenated flame retardant. The results were conclusive, Leifer says. Regard- ing Izod impact strength, all brominated FR formulations exhibit high initial results compared to the non-FR compound, in the range of ±10%, while the non-halogenated FR showed a 40% decrease. Similar trends have been noted for all five recycling cycles (Figure 1). In terms of tensile strength, the two brominated
epoxy-based formulations showed similar initial strength compared with the non-FR alternative. The brominated PS formulations exhibited a 10% decrease, and values for the non-halogenated
compound were lower by 25%. Once again, the differences changed little over the four rounds of recycling. The same methodology was used for the PBT compounds, and again there were six formulations: no FR; ICL-IP brominated polyacrylate (FR-1025) + ATO; FR-1025 alone; high molecular weight brominated epoxy (F-2100) + ATO; F-2100 alone; and a commercial non-halogenated flame retardant. Brominated polyacrylate showed higher impact
strength at all stages of the experiment, higher even than the one achieved by the non-FR formula- tion. The non-halogenated FR showed a 40% decrease for the initial compound and the first recycling round and further recycling cycles could not be performed any further. As far as tensile strength was concerned, the
brominated epoxy-based formulations, with and without ATO, showed 10% higher values than the non-FR alternative at all cycles. Non-halogenated FR values were lower by 50% and could not be taken beyond the first recycling round. “Polymeric brominated flame retardants not only allow mechanical recycling over several cycles but contribute to maintain critical mechanical proper- ties over time,” says Leifer. “By combining the proven sustainability of these high molecular weight materials, the contribution of ICL-IP Poly- meric Brominated flame retardant to the circular economy efforts is thus clear and significant.”
Multi-functionality FRX Polymers promoted two new applications for its Nofia polymeric and reactive phosphonate flame retardants at K2019: recycled PET and polycarbon- ate/PET blends for medical equipment. In PC/PET blends, Nofia provides not only flame retardance but also chemical resistance and heat resistance. This is interesting, says Sales & Marketing VP Ina Jiang, because usually the more flame retardants in a compound, the lower its chemical resistance. This is a problem for medical equipment, which often needs to be sanitised with strong chemicals that can cause stress cracking and other forms of degradation. Thermal properties as measured by HDT are also
better with Nofia compared with incumbent liquid-based phosphorus systems, which tend to plasticise the compound. FRX says customer trials are on-going and claims that some applications are close to commercialisation. With so many drinks now bottled in PET, recycled
Figure 1: Recycling performance of different flame retardant systems in 30% glass fibre reinforced PA66, UL94 V @1.6mm. Impact strength versus reference with no flame retardant Source: ICL-IP
26 COMPOUNDING WORLD | December 2019
PET is obviously a very hot topic in the new world of the Circular Economy. “We see a big advantage for Nofia in PET,” says Jiang, “because we get a chain extension reaction with the PET, and we get not only
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