Heretofore, whenever flame retardants were added to various thermoplastic polymers such as styrene resins, various physical properties were affected such as reduced impact strength. This is due to the fact that while imparting flame retardancy, the flame retardant causes embrittlement when added to produce the desired flame retardancy.
European Patent Applications 262,615 and 87/05615 to Haaf and Abolins, respectively, relate to flame retardant polyphenylene ether compositions and more specifically to compositions of a polyphenylene ether resin and a high impact polystyrene in which a post brominated polystyrene oligomer or polymer and antimony oxide are used in combination to impart better flame resistance, impact strength, and mold flow.
WIPO International Bureau 88/03542 relates to modified polyphenylene ether resins having improved flow properties and, in particular, it relates to modified polyphenylene ether resins incorporating a brominated alkenyl aromatic resin, a diester of tetrabromophthalic acid, and a flame retardant enhancer such as antimony trioxide. Flame retardant polystyrenes have various applications in injection molded products such as television cabinets, television racks, business machine housings, table-top and lap-top computers, smoke detector housings and modular furniture including hospital furniture.
The compositions of the present invention are also useful especially for making other molded articles such as medical disposal boxes for the receipt, storage, and eventual disposal of contaminated medical products; for electrical boxes and connectors, electrical materials, and the like.
While the impact properties of flame retardant polystyrene may be acceptable when the flame retardant is decabromodiphenyloxide without the use of a compatibilizer, in a preferred embodiment of the invention, the flame retardant excludes this composition and its analogs. These brominated diphenyl oxides may pyrolize to form furans which are potentially hazardous and environmentally toxic. Thus, it is preferred to use a flame retardant package of the present invention such as brominated polystyrene and to utilize the compatibilizing agent to improve the impact properties.