Single-component thermosetting epoxy resin with improved adhesion

One-component heat-curing epoxy resin adhesive comprising

• a) at least one epoxy resin having an average of more than one epoxy group per molecule;
• b) at least one latent hardener for epoxy resins;
• and
• c) at least one carboxylic acid selected from substituted or unsubstituted adipic acid, substituted or unsubstituted succinic acid, substituted or unsubstituted phthalic acid, substituted or unsubstituted terephthalic acid, substituted or unsubstituted isophthalic acid, substituted or unsubstituted benzenetricarboxylic acid and substituted or unsubstituted nitrobenzoic acid, excluding 2-hydroxysuccinic acid and 2,3-dihydroxysuccinic acid as carboxylic acid,
• wherein the epoxy resin adhesive contains 0.0015 to 0.04 mol of the at least one carboxylic acid per 100 g of the epoxy resin adhesive and the epoxy resin adhesive has a viscosity of 500-5000 Pas at 25° C., wherein the viscosity is determined by oscillographic means using a rheometer having a heatable plate (MCR 301, AntonPaar) (1000 μm gap, measurement plate diameter:
• 25 mm (plate/plate), deformation 0.01 at 5 Hz, temperature:
• 25° C.).