Synthesis of Amidophosphate and Application to Flame Retardant for Epoxy Resin

Abstract

Printed wired board is one of the representative application of epoxy resin. In order to reduce fire risk, the printed wired board has been required flame retardancy, and it is achieved using tetrabromobisphenol A as a flame retardant.However, due to the increasing awareness of environmental problems in recent years, the use of halogen-containing flame retardants have been avoided, and halogen-free flame retardants are required. In our previous report, we reported that amidophosphate can be used as a curing agent for epoxy resin, and it is expected that the amidophosphate is useful as a flame retardant. In this report, we investigated the application of the amidophosphate to a flame retardant of epoxy resin. The use of the amidophosphate only could not achive the target flame retardancy. However, the use of the amidophosphate with a commercially available flame retardant achieved very high flame retardancy and high T_g of cured product. We investigated the flame retardant mechanism and found that the amidophosphate contributes to the heat insulating effect by the formation of a char layer, and that the combined commercially available flame retardant contributes to combustion inhibiting effect by the radical trap. It was suggested that the high flame retardancy was achieved by these effects.