A mixture of hydroxyarylphosphine oxides comprising (a) a mono(hydroxyaryl)phosphine
oxide, (b) a bis(hydroxyaryl)phosphine oxide, (c) a tris((hydroxyaryl)phosphine
oxide, and, optionally (d) a tri- aryl, alkyl, or aralkyl-substituted phosphine
oxide combined with a phenolic co-crosslinking composition is useful as a polyhtdroxy
mixture for co-crosslinking an epoxy resin which also imparts flame resistance.
