Red Phosphorus is one of the most efficient and potent halogen-free flame retardants available, particularly for engineering plastics. Due to its handling and safety concerns (flammability, phosphine generation), it is exclusively sold as a stabilized, non-dusting masterbatch.

Flame Retardant Mechanism Red Phosphorus has an extremely powerful dual-action mechanism:

1. Condensed Phase Action: In a fire, it oxidizes to form phosphoric acid. This is a potent acid catalyst that promotes the dehydration and cross-linking of the polymer, forming a very stable, thick, insulating char layer.

2. Gas Phase Action: It also releases phosphorus-based radicals (PO, P) into the gas phase. These radicals are the most effective flame-quenching species known, aggressively trapping H• and OH radicals to shut down the fire’s chain reaction.

Key Application Areas

• Polyamides (PA): The classic, high-efficiency FR for glass-fiber reinforced PA6 and PA66, providing excellent V-0 ratings at very low dosages (e.g., 5-10%).

• PBT & TPEs: Also used in PBT and certain TPEs where its dark red/brown color is acceptable.