Analyzing Consumption of BPh as a Function of Film Depth and UV light Intensity (I0)

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.