The invention relates to the use of a one-component aqueous polyurethane dispersion composition (PD) as a primer for the adhesion of plastic films (KF) by means of an aqueous one-component polyurethane dispersion adhesive (DK). The aqueous polyurethane dispersion composition (PD) comprises a polyurethane (P1) and carbodiimide groups and/or carboxyl groups, and the polyurethane dispersion adhesive (DK) comprises a polyurethane (P2) and carbodiimide groups, and carboxyl groups such that the aqueous polyurethane dispersion composition (PD) and the aqueous polyurethane dispersion adhesive (DK) react with one another in a polyaddition reaction when heated to a temperature of 50° C. or more. The invention also relates to primer-coated plastic films, to composite bodies produced therefrom and to methods for the production thereof.