Modification of phenolic resin and its effect on adhesive properties of polyurethane/metal

To solve the problem of poor bonding effect of polyurethane (PU)/metal at room temperature when Chemlok218 was used as adhesive, a highly active PU modifier was used to modify phenolic resin (PF) in Chemlok218 to form a PF@NCO transition layer between Chemlok218 coating and PU. FTIR and TG analysis showed that the NCO group in PU modifier reacted with the hydroxyl group of PF to form carbamate group, and the surface energy of PF@NCO could be improved. The compatibility with PU had increased. When the mass ratio of Chemlok218 to PU modifier is 80∶20, the peel strength of PF@NCO-20 reaches 23.4 kN·m⁻¹, which is 58.1% higher than that of pure Chemlok218, and the whole PU/metal bonding sample had no bonding weaknesses and defects. The purpose of this paper is to provide a reference for solving the problem of bonding strength of PU/metal at room temperature.