Abstract
In recent years, with downsizing of electronic information terminal devices and high-speed transmissions and processing of large capacity information, lower dielectric constant has been required for the circuit boards which are usually made of epoxy resins. Currently, active ester resins have been attracted much attention as epoxy hardeners which can afford low dielectric materials. The active esters give the cured epoxy resins low dielectric constants and high water resistance, because no hydroxyl groups derived from the epoxy resins are generated. In this study, we applied the concept of active ester resins, and aimed to create a new active phosphate ester curing agent of epoxy resins. We synthesized various phosphate esters and investigated their reactions with mono-functional epoxy resins. As a result, we found that dimethylphosphinate or N,N’-dimethylamidophosphate can react with mono-functional epoxy resin. Furthermore, we synthesized an multifunctional active phosphate hardener based on N,N’-dimethylamidophosphate, and prepared a cured epoxy resin. Contrary to expectation, the cured epoxy resin was high water absorption. However, Tg of the cured epoxy resin and char yield after thermal decomposition were high value. These data suggested that the phosphate hardener can give the high thermal resistance and flam retardancy.
