Phosphorus flame retardants in thermoset resins

Composites based on thermoset resins like unsaturated polyesters or epoxies are used to a wide extent in the transportation area. In the event of a fire on board a moving train, immediate evacuation of the people is not possible. Therefore, it is essential that the materials used in the construction and furnishing of coaches are such that they are not easily ignited and have a low total emission of heat, smoke and toxic fume when exposed to an ignition source. Modern railways have to be lighter and more environmentally friendly. Production has to get faster and more inexpensive. It is shown in this work that non-halogen, phosphorus-containing flame retardants are very effective in thermoset resins. Their advantages lie in their high effectiveness, which enables very low concentrations to be used. while at the same time meeting the most stringent requirements. The formulations can, due to the low viscosity of the resin mixture, be processed by hand lay-up, pultrusion, spray laminating, winding and resin transfer moulding. The low density of the composites makes them useful for all mass transport applications. The phosphorus compounds do not affect the curing reactions of the resins and can be used in cold and hot cured systems. (Examples: polyester resins, epoxy resins, sheet molding compound.)