Bonding agent composition

An adhesive promoter composition, comprising:

• at least one film-forming resin;
• at least one aromatic polyisocyanate;
• at least one solvent;
• as well as
• at least one isocyanurate of the formula (I)
• wherein
• R1, independently of one another, stands for a linear or branched monovalent hydrocarbon radical having 1 to 12 carbon atoms, which optionally have one or more C—C multiple bonds and/or optionally cycloaliphatic and/or aromatic components;
• R2, independently of one another, stands for a linear or branched monovalent hydrocarbon radical having 1 to 12 carbon atoms, optionally having one or more heteroatoms and optionally one or more C—C multiple bonds and/or optionally cycloaliphatic and/or aromatic components;
• a stands for a value of 0, 1 or 2;
• R3, independently of one another, stands for a linear or branched, divalent hydrocarbon radical having 1 to 12 carbon atoms, optionally having one or more heteroatoms and optionally one or more C—C multiple bonds and/or optionally cycloaliphatic and/or aromatic components.