epoxy resins hardened with amphiphilic block copolymers and powder coatings obtained from them.

A composition curable solid resin for use in compositions of powder coating and comprising (a) an epoxy resin and (b) an amphiphilic block copolymer containing at least one segment miscible with the epoxy resin block and at least one immiscible block segment with the epoxy resin, wherein the immiscible block segment comprises at least one polyether structure provided that the polyether structure of said immiscible block segment contains at least one or more monomer units of alkylene oxide having at least four carbon atoms, such that when the epoxy resin composition is cured, increases the toughness of the epoxy resin composition resulting cured, and wherein the final resin composition it is in solid form.