BDMMP, a liquid, phosphorus-based PIN flame retardant shows fire performance, heat ageing and migration resistance. The PIN FR dimethyl methylphosphonate (DMMP) is widely used today in flexible polyurethane foams (PUR), but its low molecular weight can result in volatilisation and migration, with resulting loss in fire safety. A new and larger phosphorus-based molecule, bis((dimethoxyphosphoryl)methyl) phenyl phosphate (BDMPP) was synthetised, resulting in a liquid P-based PIN FR. This was compared to DMMP at 10% and 20% loading in flexible PUR foam. BDMPP showed improved fire performance (e.g. peak heat release rate kW/m2 276 @ 10% BDMPP compared to 300 @ 10% DMMP and 334 for neat PUR) and lower migration (DMMP foam @ 20% failed after 32 hours of accelerated heat ageing, BDMMP @ 20% only after 48 hours). BDMMP increases the density of the foam and slightly deteriorates tensile strength and elongation at break, compared to DMMP.
“Synthesis of a novel liquid phosphorus-containing flame retardant for flexible polyurethane foam: Combustion behaviors and thermal properties”, F. Zhou et al., Polymer Degradation and Stability 171 (2020) 109029 https://doi.org/10.1016/j.polymdegradstab.2019.109029