PIN flame retardants in flexible polyurethane foam
Polyurethane foams are increasingly used in furniture, transport applications and in building materials, for seats and cushions, mattresses, insulation, sound and vibration damping and shaping forms. However, these foams post an inherent high fire risk. Burning occurs in two stages: a solid phase, with yellow smoke including HCN, and then a liquid burning pool stage, generating considerable heat and toxic carbon monoxide. An increasing range of PIN flame retardants are being developed for polyurethane foams.
N. Usta showed that power station fly ash combined with ammonium polyphosphate improved both fire resistance and thermal stability of rigid polyurethane foam. Yingjie et al. compared 10% loading of a phosphorus-nitrogen PIN FR (MPOP triazine triamine phosphate) to 10% loading of brominated flame retardant (HBB/TBECH), showing that the PIN FRs achieved a slightly lower peak heat release than the brominated FRs (271 vs. 284 Kw/m2, compared to over 600 kW/m2 for non-treated foam) and that the brominated FR treated foam had higher smoke toxicity, reaching WX class toxicity (mice comatose) for brominated FR loading > 4%.“Investigation of Fire Behavior of Rigid Polyurethane Foams Containing Fly Ash and Intumescent Flame Retardant by Using a Cone Calorimeter”, N. Usta, J. Applied Polymer Science, 124(4), 3372-3382, 2012 http://onlinelibrary.wiley.com/doi/10.1002/app.35352/abstract
“The effect of flame retardant additives on the combustion performance of flexible polyurethane foam”, C. Yingjie, Bulgarian Chemical Communications, Volume 46, Number 4 (pp. 882 – 886) 2014 http://bcc.bas.bg/BCC_Volumes/Volume_46_Number_4_2014/Chien-46-4-882-886.pdf