UV Curable Metal Coatings - Special Possibilities and Problems

Transparent and black pigmented UV crosslinking model formulations were investigated on steel and aluminium using various raw materials and curing conditions. Comparative tests were made, e.g., with respect to viscosity, conversion of acrylic double bonds, mechanical parameters, and resistance in the salt spray test. One of the results was that benzophenone and benzophenone derivatives led to the formation of intermediate products with strong UV-A absorption after initial irradiation of the given formulations. Despite an improvement in surface curing this can deteriorate through curing in deeper parts of the layer. Thus, criteria for the choice of photoinitiators and for an optimum order of UV radiators could be derived.