Biobased anti-drip for PIN FR polyamide

A boron-nitrogen-phosphorus-AlPi PIN FR achieves UL 94 V-0 in PA6 loading, and no burning drip with 1% modified daidzein.  Daidzein is a natural isoflavone found in soy beans and other legumes. The boron-phosphorus PIN FR was laboratory synthesised by reacting 4-formylphylybroronic acid with 1,6-hexanediamine, DOPO and AlPi (aluminium diethylphosphinate). Both AlPi and this novel boron-nitrogen-phosphorus-aluminium PIN FR achieved UL 94 V-0 (1.6 mm) at 12% loading in polyamide-6, with LOI increased to c. 30 from c. 24 for neat PA6, and peak heat release rate reduced to 580 (AlPi) – 560 (BNP PIN FR) from 720 for neat PA6. Replacing 0.8 – 1% of the BNP PIN FR by modified daidzein prevented dripping whilst maintaining fire performance (UL 94, LOI, PHRR).

“A key role of a bio-based charring-coupling agent in flame retardant and anti-dripping performance of polyamide 6/aluminum diethylphosphinate”, W. Zhang et al., J Appl Polym Sci. 2023, 140:e54327,