US Patent 7678531 Positive-working imageable elements

Positive-working imageable elements have a substrate and an imageable layer that can be used to prepare lithographic printing plates. The imageable elements also include a radiation absorbing compound, and a mixture of first and second polymers in the same imageable layer. The first polymer has two or more centered H-bonds (hydrogen bonds) within a non-covalently bonded unit, and the second polymer is a polyvinyl acetal. This mixture of polymers in the same imageable layer provides improved solvent resistance and processing latitude without a loss in imaging speed.