Phosphorus-Based Flame Retardant Coating

Phosphorus-based FR coatings use organophosphorus compounds (DOPO, DMMP, or ammonium polyphosphate at 10–25% add-on) in condensed or vapor phase mechanisms to inhibit combustion. Condensed-phase phosphorus promotes char formation in cellulosic substrates, increasing char yield from 5% to 25–35% at 500°C (TGA). Vapor-phase PH₂ and PO• radicals quench combustion in synthetic fiber coatings. LOI increases from 18–20% to 28–32%. Reactive phosphorus monomers (THPC for cotton) form covalent bonds surviving 50+ washes per BS 5867 Part 2. Nitrogen-phosphorus synergy (P:N ratio 1:2–1:4) reduces FR loading by 30–40% at equivalent performance.