Silicone derivatives as new flame retardants for aromatic thermoplastics used in electronic devices

New silicone derivatives that generate no toxic gas during combustion have been developed for use as flame retardants in the aromatic thermoplastics (polycarbonate and its derivatives, acrylonitrile–butadiene–styrene, polystyrene) used in many electronic devices. A special silicone with a branched chain structure, a phenyl-rich mixture of phenyl and methyl groups in the chain and methyl groups at the chain terminals was found to be effective in retarding the combustion of these plastics, and particularly so for polycarbonate (PC) and its derivatives. These silicone derivatives have shown themselves to be a perfect replacement for halogen compounds, which have been claimed to have a potential environmental hazard when the materials are subjected to combustion. Further, adding these silicone derivatives to PC does not adversely affect important other properties, such as strength, moldability and heat resistance; impact strength is in fact better than that of PC containing a bromine compound as a flame retardant. © 1998 John Wiley & Sons, Ltd.