Crosslinked phenoxyphosphazene compounds, process for the preparation thereof, flame retardants, flame-retardant resin compositions, and moldings of flame-retardant resins

摘要

This invention provides a halogen-free flame retardant which advantageously has a high melting point and a low volatility and does not impair the inherent properties of resins. The flame retardant of the invention is a phosphazene compound crosslinked with a crosslinking group such as a phenylene group, wherein each of the crosslinking groups is interposed between the two oxygen groups left after the elimination of phenyl groups from the phosphazene compound; the crosslinked phenoxyphosphazene compound does not have any free hydroxyl groups (derived from crosslinking groups); and the amount of the phenyl groups in the crosslinked compound is 50 to 99.9%, based on the total number of the phenyl groups in the phosphazene compound.