Powder coating composition for forming a composite material having an expanded epoxy resin layer

摘要

A composite material having a substrate and an expanded, cured layer of an epoxy resin composition which is provided over a surface of the substrate and in which a major portion of the cells are present in a location adjacent to the interface between the substrate and the expanded layer and substantially no cells are present on the top surface portion of the expanded layer. The epoxy resin composition includes an acid anhydride curing agent and an alkali metal carbonate blowing agent. The composition is coated over the substrate and the coating is heated to cure and expand the composition while maintaining the top surface of the coating below the expansion temperature.