The invention relates to an impregnation resin mixture and to the use thereof. In one embodiment, an impregnation resin mixture includes a) at least one epoxide resin component selected from the group consisting of polyepoxides based on bisphenol A and/or F, and advancement resin produced therefrom, based on epoxidized halogenated bisphenols and/or epoxidized novolaks and/or polyepoxide esters based on phthalic acid, hexahydrophthalic acid, or based on terephthalic acid, epoxidized polyaddition products from dicyclopentadiene and phenol or cycloaliphatic compounds, b) as reactive diluents, 2 to 30 wt. % lactones with respect to the sum of the epoxy resin components, c) BCI3 and/or BCI3 complexes and/or a compound selected from the group of imidazoles and d) optionally additional additives, wherein the impregnation resin mixture does not contain any carboxylic acid anhydrides.