What Causes Ink Adhesion Problems?

The $64 question is: what causes ink adhesion problems when screen printing polycarbonate film?  While some have suggested moisture absorption as the culprit, the most likely candidate is exposure  to UV light and oxygen.  As the polycarbonate absorbs UV light, it excites the photons of the atoms, which in turn creates free radicals. Free radicals...
http://bit.ly/1mAjm9U