A water-based bonding primer composition and a method of applying the same onto a metallic surface prior to adhesive bonding. The bonding primer composition is a water-based dispersion containing water, one or more epoxy resins, one or more curing agents, a silane compound, a low amount of propylene carbonate (PC), and optional additives. The bonding primer composition can form substantially smooth films by spraying, and at the same time, meet environmental regulations and provide high bonding performance.

Disclosed herein is a solvent-based bonding primer composition containing one or more organic solvents, one or more epoxy resins, one or more curing agents, a silane compound, and a low amount of core-shell rubber particles in nanometer size, submicron or micron size. Also disclosed is a method of applying the solvent-based bonding primer composition onto a metallic surface of a first substrate prior to bonding the metallic surface to a second substrate via a curable adhesive.

Disclosed herein is a solvent-based bonding primer composition containing one or more organic solvents, one or more epoxy resins, one or more curing agents, a silane compound, and a low amount of core-shell rubber particles in nanometer size, submicron or micron size. Also disclosed is a method of applying the solvent-based bonding primer composition onto a metallic surface of a first substrate prior to bonding the metallic surface to a second substrate via a curable adhesive.