Thermally curable resin blend and its use in composite materials

Abstract

A thermally curable resin blend, comprising a) from 50 to 90 wt% cycloaliphatic curable epoxy resin having an epoxy equivalent weight of greater than 350, b) from 2 to 25 wt% of a tri- or tetra- functional epoxy reactive diluent having an epoxy equivalent weight of less than 200, and c) a curing agent. The cycloaliphatic curable epoxy resin preferably comprises 60-85 wt% of the composition, and preferably has an epoxy equivalent weight greater than 400, more preferably greater than 450 and particularly greater than 500. The tri or tetra functional epoxy reactive diluent preferably has an epoxy equivalent weight of less than 170, particularly less than 140. A process of thermally curing the disclosed resin blend comprising exposing the resin blend to an elevated temperature and / or pressure wherein the time taken to reach 95% conversion at 95°C is less than 140 minutes, the cured resin resulting therefrom, a prepreg impregnated with the curable resin blend, and a composite material obtainable by curing such a prepreg are also disclosed. The cured resin is disclosed to have a glass transition temperature of greater than 100°C.