Enhancing Polymer Flame Retardancy by Reaction with Phosphorylated Polyols. Part 2. Cellulose Treated with a Phosphonium Salt Urea Condensate (Proban CC~(~R)) Flame Retardant

摘要

Phosphorylation of cellulose flame retarded with an ammonia-cured, polycondensed tetrakis(hydroxymethyl) phosphonium-urea derivative (as Proban CC~(~R), Rhodia) with a polyol diphosphoryl chloride or phosphorochloridate like spirocyclic pentaerythritol di(phosphoryl chloride) or diphosphorochloridate, SPDPC can yield phosphorus levels in excess of 10% (w/w). Such high levels suggest up to 82% yields of reaction if phosphorylation of the free secondary amine groups present in the cross-linked flame retardant is the assumed site. The presence of substituted pentaerythritol phosphate moieties significantly increases char formation above 400℃ and scanning electron microscopy indicates that the char has an intumescent structure. The char-forming characteristic is not influenced by subjecting the phosphorylated flame retardant cellulose to boiling in a 1% detergent solution in water thereby suggesting that the product is durable. The potential of this reaction to create a durable, intumescent flame retardant for cellulose is discussed.