Ammonium Polyphosphate (APP)

A salt of polyphosphoric acid and ammonia, which has various names depending on the company but can be generalized as Ammonium Polyphosphate 484 (APP 484). It has low water solubility and its largest use is as a highly efficient flame retardant. It can also be used as an emulsifier and fertilizer. Used as a flame retardant in paint and coatings and in a variety of polymers -- polyolefins and polypropylene, where APP is part of intumescent systems. Also used in thermosets where APP is used in unsaturated polyesters and gel coats, epoxies, and polyurethane castings (intumescent systems). Also applied to flame retard polyurethane foams.