The influence of UV light intensity (I0) on Benzophenone (BPh) photo decomposition at different depths of UV cured films was studied using a new approach that is a combination of the traditional UV spectra analysis and statistical calculation. UV absorption of a UV curable formulation is a function of Photo initiator concentration [PhI]. In the ideal case (without interference from UV absorption of photo decomposition by-products), UV absorption of BPh can be used to monitor the photo decomposition of BPh and photopolymerization. A depth profile of BPh consumption at different depths of a module formulation was analyzed. This investigation was performed with a variety of film depth, different curing speeds and different I0 (mW/cm2) with different or equal UV Exposure. The purpose of this paper is to help formulators and end-users learn how to correctly use BPh / N-mathyldienthanol amine (MDEA) and to choose UV lamps that improve and balance the surface curing and the through curing in their UV curing applications.
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