Heat Durability and Curing Behavior of Phenoxy Resin by Epoxy Resin Doping with Post-crosslinking by Thermal Treatment

Abstract

Phenoxy resin is an engineering plastic that is widely used as an insulating mold material, for example, in selfwelding insulating sheets that have superior moldability and low material costs. To improve the heat durability of phenoxy resin, the material can be doped with epoxy resin, which is a thermosetting material, and with an epoxy resin-phenolic resin mixture. We investigated the behavior of doped phenoxy resin in a heat-treatment process. We also investigated the heat durability, in terms of a thermal index (T_i), of these resins by using thermogravimetric analysis with the Ozawa－Flynn－Wall method. The thermally treated phenoxy resin doped with epoxy resin formed intermolecular-crosslinking, and its chemical heat durability improved compared with that of the phenoxy resin alone. On the other hand, phenoxy resin crosslinked by epoxy resin and phenolic resin closslinked by epoxy resin formed in the thermally treated phenoxy resin doped with the epoxy resin-phenolic resin mixture. By adding an appropriate amount of epoxy resin-phenolic resin mixture, its heat durability could be raised higher than that of phenoxy resin alone and of epoxy-resin-doped phenoxy resin.