Process and Quality Control during UV Curing of Acrylate Coatings Using Near-Infrared Reflection Spectroscopy

摘要

Near-infrared (NIR) reflection spectroscopy was used to monitor the actual conversion of acrylic double bonds after UV curing directly in the running coating line. Quantitative data were obtained after calibration either to FTIR spectroscopy or to specific properties of the coatings such as their hardness which responds extremely sensitively even to small changes of the conversion. In-line monitoring of the degree of cure by NIR spectroscopy was carried out in pilot scale for clear and pigmented acrylate coatings on various substrates. Another interesting application are UV-curable acrylic hot-melts for pressure sensitive adhesives. The effect of changes of the irradiation dose, the emission spectrum of the UV source, inertization, and other parameters on the conversion was studied.