Patent ID: 8240943

Claim:
A negative-working, on-press developable imageable element comprising a substrate having thereon an imageable layer comprising: a radically polymerizable component, an initiator composition capable of generating free radicals sufficient to initiate polymerization of free radically polymerizable groups upon exposure to imaging infrared radiation, a primary polymeric binder that has a backbone and is optionally present in the form of discrete particles, and an infrared radiation absorbing dye, said element further comprising a topcoat layer disposed on said imageable layer, said topcoat layer comprising a water-soluble polymer binder and a composition that is capable of changing color upon exposure to imaging infrared radiation, wherein said composition that is capable of changing color upon exposure to imaging infrared radiation comprises: (1) an acid-generating compound in an amount of from about 2 to about 25 weight %, and (2) an infrared radiation absorbing compound in an amount of from about 1 to about 12 weight %, both based on total dry weight of said topcoat layer, and wherein said initiator composition comprises a diaryliodonium cation and a boron-containing anion at a molar ratio of at least 1.2:1 and up to 3.0:1.