Fast-curing coatings for adhesion promotion between metallic oxides and thermoplastic polyurethane
The cost-effective production of high-performance and durable steel reinforced thermoplastic composites requires improvement of the adhesion encountered at the interface between metallic substrates (galvanized steel) and a thermoplastic elastomer (TPU). Combined requirements of processing speed, adhesion and durability were assessed by using cationic photo-polymerized coatings at the TPU-metal interface. The adhesion was studied by pull-out tests on co-molded TPU matrix - galvanized steel wires samples before and after different aging conditions. Several fast benchmark surface treatments were first studied and resulted in average adhesion and poor durability. Coupling primers were then investigated with γ-APS aminosilane films formed from different solutions and deposition parameters. They resulted in excellent adhesion and durability at the cost of a very low processing speed. Finally, cationic UV-curable coatings were used as an innovative adhesion-promoting interface achieving fast curing together with excellent adhesion and durability. The curing kinetics and the final degree of cure of these coatings was also investigated in order to reach the fastest processing rate. Maximum interfacial shear strength and energy release rate adhesion criteria were defined and discussed for the case of an elastomeric matrix in the light of FEM simulations considering residual stress, viscoelastic relaxation and temperature dependence.
Record created on 2012-09-03, modified on 2016-08-09