Phosphorus-containing flame retardants cover a wide range of inorganic and organic compounds and include both reactive products which are chemically bound into the polymer material as well as additive products which are integrated into the material by physical mixing only. They have a broad range of applications and good fire safety performance. The most important phosphorus-containing flame retardants are phosphate esters, phosphonates, and phosphinate.
Phosphorus-containing flame retardants are widely used in standard and engineering plastics, polyurethane foams, thermosets, coatings, and textiles. Phosphate esters are mainly used as flame retardant plasticizers in polyvinylchloride (PVC, alkyl/aryl phosphates) and engineering plastics, particularly in polyphenylene oxide/high impact polystyrene (PPO/HIPS), polycarbonate/ acrylonitrile butadiene styrene (PC/ABS) blends, and polycarbonate (PC, e.g. triphenylphosphate, resorcinol- and bisphenol A- bis-(diphenyl) phosphate). The latter is widely used in IT housings requiring high fire safety levels. Other applications include phenolic resins and coatings. Phosphates, phosphonates, and phosphinates are used as reactive phosphorus-containing flame retardants in flexible polyurethane foams for automotive and building applications. Additive organic phosphinates are a new class of flame retardants for use in engineering plastics, particularly in polyamides. Specific reactive phosphorus flame retardants are used in polyester fibers and for wash-resistant flame retardant textile finishes. Other reactive organophosphorus compounds can be used in epoxy resins in printed circuit boards.
Flame retardant grades based on red phosphorus are mainly used in glass fiber reinforced polyamide 6 and 66. Further applications are in polyethylene and ethylene-vinyl acetate (EVA), polyurethane foam, and thermosetting resins (unsaturated polyesters and epoxies). Ammonium polyphosphate grades are primarily used in intumescent coatings. They are also found in rigid and flexible polyurethane foams and polyolefins (injection-molded), in formulations for unsaturated polyesters, phenolics, epoxies, and coatings for textiles.