Fast-Curing Oligomers for Enhanced Coating Performance
Formulators are often able to achieve increased cure rates using conventional free amine synergists such as methyl diethanol amine, dibutyl ethanol amine, triethyl amine and triethanol amine. These amines react synergistically with Type I hydrogen-abstracting photoinitiators such as benzophenone or isopropyl thioxanthone (ITX). Ultimately, they enable formulators to overcome oxygen inhibition, which negatively affects the surface cure of coatings.
However, conventional amine synergists present a number of formulating concerns. A key issue is odor, which can be a problem before, during and after UV curing. In addition, "blooming" of the amines to the surface may result in a grease-like film on the finished coating. Finally, conventional amine synergists may be a source of extractables in cured coatings.