Patent ID: 7678531

Claim:
A positive-working imageable element comprising a substrate having thereon a single, outermost thermally imageable layer, said element further comprising an infrared radiation absorbing compound that absorbs at a wavelength of from about 700 to about 1200 nm, wherein said single outermost thermally imageable layer comprises first and second polymers, said first polymer is an alkaline soluble polymer that comprises: (1) at least one covalently bonded unit that is derived from a polyfunctional material that is soluble or dispersible in an aqueous developer, and (2) at least one thermally reversible non-covalently bonded unit that includes a two or more centered H-bonds within that unit, and said second polymer is a polyvinyl acetal in which at least 50% of the recurring units are acetal units, wherein the weight ratio of said first polymer to said second polymer is from about 1:1 to about 15:1.