Screen printing stencil composition with improved water resistance

The invention relates to polymeric preparations that can be used in screen printing processes. Further, the invention relates to a film or a liquid polymeric composition that when used in combination with aqueous alkaline liquids, such as an alkaline ink, can form sharp long-lived stencil/screen assemblies used in screen printing operations. More particularly, the invention relates to polyvinylpyridine (or pyridinium) containing films that can be cast from aqueous solutions which, after imaging and in contact with an alkaline liquid such as a screen printing ink, at a pH greater than 7, forms screen stencils with increased or improved water resistance that can be used in screen printing processes. The composition of the invention can be reclaimed from the screen using an aqueous acidic reclaiming composition. The invention resides in a photosensitive composition for screen printing. Preferably, the composition of the invention comprises a polymer comprising a vinylpyridine monomer or polymer having a pyridinium salt character and a photoreactable constituent. The resulting stencil, once dried, exposed, cured, and subjected to alkaline treatment obtains enhanced solvent/water resistance but can be reclaimed using an acidic wash. In use, the stencil provides a screen/stencil assembly or blockout utility of high structural integrity through repeated use and screen printing images of high resolution and quality.