Engineering plastics, with their excellent mechanical strength, temperature resistance, and processing adaptability, are widely used in electronic and electrical appliances, automotive parts, new energy structural components, and other fields. Flame retardancy is a core safety threshold for such products to enter the market. Against the industry background of continuously tightening global halogen-free environmental regulations, red phosphorus flame retardants, with the advantage of leading flame-retardant efficiency per unit addition, have become a core choice combining performance and cost advantages in engineering plastic modification. Data show that the plastics sector has already accounted for 42.3% of global red phosphorus flame retardant consumption, and their application value and industry importance continue to become more prominent. Unlike most halogen-free flame retardants that rely on high filling to achieve flame retardancy, red phosphorus has a phosphorus content close to 100%. It mainly works via a condensed-phase flame-retardant mechanism. When heated, it transforms into polyphosphoric acid substances that catalyze rapid dehydration and crosslinking of polymers into char, forming a dense heat-insulating and oxygen-insulating protective layer on the material surface. Only a small amount of addition is needed for mainstream substrates such as nylon, polyester, and PC\/ABS to stably reach UL94 V-0 rating, while preserving the plastic's original impact strength, processing fluidity, and electrical insulation properties to the greatest extent.<\/p>\n