Abstract: A flame retardant in the form ultramicro microencapsulated red phosphorus（MRP）was prepared by encapsulating red phosphorus with phenol-formaldehyde(PF) resin via in-situ polymerzation. The MRP was characterized using infrared spectroscopy, scanning electron microscope, X-ray photoelectron spectroscopy, laser particle size analyzer and thermogravimetric analysis, The average size of MRP was 7.5 μm and a compactness surface was formed. The ignition point of MRP rose to 485 ℃. The moisture absorption was less than 1.8 %, oxidation resistance 7.8 mg/g·h, and phosphine emission 3.6 μg/g·h. In contrast with red phosphorus, the performance of MRP was obviously improved.

Key words: microcapsule, ultramicro red phosphorus, phenol-formaldehyde resin, preparation, characterization, flame retardant